Towards commercialisation of MHD power plants—A look at the international programmes

Energy Convers. Mgmt Vol. 25, No. 2, pp. 225-247, 1985 Printed in Great Britain. All rights reserved

0196-8904/85 $3.00+ 0.00 Copyright © 1985PergamonPress Ltd

TOWARDS COMMERCIALISATION OF M H D POWER P L A N T S - - A LOOK AT THE INTERNATIONAL PROGRAMMES V. R. MALGHAN MHD Research Project, Bharat Heavy Electricals Limited, Tiruchirapalli 620 014, India (Received 27 February 1984)

Abstraet--"If we solve this [making MHD cost effective], we will succeed, otherwise MHD will be in proceedings and papers"--Academician Scheindlin. The first commercial-scale MHD power plant of 500 MW is expected to be operational by 1988 in the USSR. Various countries have identified their national programmes towards the development of MHD power plants. The eighth international conference on MHD electrical power generation at Moscow in September 1983, provided a useful forum for presentation and discussion of the activities of various countries. A critical look at these activities provides an insight into the efforts required towards the commercialisation of MHD power plants. The MHD activities of the USSR, U.S.A., Japan, China, India, The Netherlands, Australia. Poland, Finland and the co-operative work of CMEA countries have been summarised. The problem areas and required future efforts are discussed. The material presented in this paper is based on the conference proceedings, private communications, and personal discussions the author had with various international specialists during the conference. It is hoped that this summary paper will be of interest to a wide spectrum of readers. MHD

Powerplants

Plasma

1. INTRODUCTION Since the historic MHD experiment of Michael Faraday on 12 January 1832 on the River Thames, London, MHD development has come a long way. Due to its various advantages such as higher overall efficiency, less pollution and lower water requirement, Magneto-Hydro-Dynamics (MHD) electrical power generation has attracted the attention of a number of countries. National programmes have been drawn up in various countries with the aim of achieving early commercialisation of the MHD electrical power generation system, The Russian programme is on its way to establish the first 500-MW commercial MHD power plant by 1988. The Component Development and Integration Facility (CDIF), an engineering-scale test facility of 50-100-MW capacity, at Butte, Montana in the U.S.A., has completed testing with oil-fired ash injection experiments and is now ready for tests with direct burning of coal. At the Electro Technical Laboratory (ETL) of Japan, a total of 430 hr of tests at 15-MW input on the ETL Mark VII generator have been completed, and valuable engineering data have been collected and the generator is ready for experiments to simulate coal combustion. At Shanghai Power Plant Equipment Research Institute, China, long-duration tests of 200 hr of continuous operation on the oil-fired facility have been successfully completed along with downstream steam power generation. Coal-fired tests on the 5-MW facility are

under way at the Institute of Electrical Engineering Beijing, China. A 5-MW thermal input, Indian pilot plant facility at Tiruchirapalli is in the final stages of erection and commissioning. The Netherlands MHD Association (NMA) is offering consultancy services for technical and commercial studies of MHD systems and components and five series of useful experiments have been completed at the Eindhoven 5-MW blow-down facility. The Australian facility of 4-MW thermal input at the White Bay power station, with provision to test both disk and linear generators is getting ready for conducting experiments. Poland's activity is concentrated on coal gasification by using exhaust gases from MHD, and Finland is concentrating on MHD material research. With this background of MHD activity in the international field, the Eighth International Conference on MHD Electrical Power Generation at Moscow during September 1983 provided a useful forum for presentation and discussion of MHD activities. The conference was successful in discussing various technological problems and future courses of action towards the earlydevelopment of commercialscale MHD power plants. The conference discussed various technological developments, national programmes, future prospects, etc. It was thought appropriate to summarise the status and programmes of MHD activities in the various countries and critically evaluate the programmes with reference to early commercialisation of MHD power plants. These aspects are discussed in the present paper. The

225

AVCO Mark-VI UTSI CDIF

I

Beijing Indian M H D pilot plant Blow-down facility closed cycle Ar-CS plasma White Bay facility

ETL Mark VII Shanghai

U-02 U-25 U-25G K-I M- 10 M-25 500MW

Facility name

f

4.0

5.0 5.0 15.0 5.0

15.0 5.0

20.2 20.0 50.0 100.0

4.0 300.0 -20.0-30.0 10.0 25.0 ll00.0

I C - - I r o n core magnet; SC--super conducting magnet.

Australia

The Netherlands

India

China

Japan

U.S.A.

USSR

Country

Thermal input (MW)

0.35 (for 2 MW)

1.4-1.44 1.0 3.0 5.0 (Ar)

3.1 -8.0 (with oil + ash) 9.6 (with coal) 2.0 1.0

0.6-1.0 40.0-45.0 5.0 2.0-3.0 2.0 5.0 230.0

Comb. product mass flow rate (kg/sec)

Coal + alcohol/ slurry & alcohol

Coal BWG

Kerosene + coal Diesel oil

Coal/oil + ash Coal Oil + ash & coal Coal

gas

gas

gas/coal gas

Fuel Natural Natural Coal Natural Coal Coal Natural

50

--

23 40

100 23

-100 45

50 40 40 85 40-50 50 23

02 (~o)

--

1500 1500

-1450

1600

1300 1200 900 -1300 727 1700

Preheat temp. (°C)

Oxidiser

Table I. Parameters of the important M H D facilities in the world

2.00 1.82 1.60 2.00 2.00

4.00 2.10 3.00 6.00

IC: 2.70

SC: 4.70

IC: IC: to IC: IC:

IC: IC: IC: SC:

IC: 1.70 IC: 2.00 SC: 4.00 IC: 2.00 --SC: 6-4.00

Magnetic field (tesla)

--

360 kW

0.48 kW --

100 kW 14.9kW

200 kW --582MW ( M H D + steam) 183 kW -4 MW (oil expt)

75kW 25 MW

Maximum power output

10 sec

50 min --

430 hr 100hr

100 hr with oil expt

2 hr

>200hr > 1000 hr -30-40 min > 250 hr -Comm.plant

Maximum operating time

Z

O :~ t'rl

.Z.

r">

o~

MALGHAN: MHD POWER PLANTS material presented in this paper is mainly based on the conference proceedings [l-41], personal discussions the author had with various international specialists during the conference, private communication received from various specialists (Kusaka, 1984; Kayukawa, 1983; Giessen, 1983; Kruger, 1983; Brozowski, 1983; Kuttunen, 1983) and some of the recent published work [42-46].

2. INTERNATIONAL ACTIVITIES After the historical experiment of Michael Faraday in 1832, the first experiments to develop an M H D generator were conducted at the Westinghouse Research Laboratories, U.S.A., during the early forties. A number of countries have started M H D programmes since then. Great Britain, France, and the Federal Republic of Germany, at one time, had ambitious programmes and have now sharply curtailed their efforts. At present, the USSR, U.S.A., Japan, China, India, The Netherlands, Australia, Poland and Finland have major national programmes to develop M H D power generation systems. The CMEA countries have a co-operative programme for the development of M H D power plants. The programmes cover mainly development of fossil-fuel-based combustion plasma open-cycle M H D power generation systems. Some work is also devoted to closed-cycle M H D systems. The discussions in this paper are concentrated on the fossil fuel based open cycle facilities. Major parameters and overall status of the activities of important M H D facilities in the world are given in Table 1. In the following sections, the M H D activities in various countries are described,

2.1. USSR M H D activities in the USSR started in the early sixties with the establishment of U-02, a small-scale complete M H D pilot plant, and then the establish-

227

Research and Development Institute. The ministry work includes the construction of a natural-gas-based 500-MW M H D commercial power plant and research and development work for the construction of the main M H D coal-based power plant of 1000MW. The U-02, U-25, U-25B, U-25G facilities at Moscow, the K-l M H D facility in the Ukraine Republic, the M-10 and M-25 facilities of the Krizhizhanovskii Power Research Institute and Estonian Energy Trust are some of the important M H D experimental facilities of the USSR. Topping all these facilities and of considerable current interest is the 500-MW M H D commercial power plant under construction at Ryazan near Moscow. 2.1.1. U-02, U-25, U-25BandU-25Gfacilities. The details of the U-02, U-25 facilities and work carried out there are well known in the literature. Figure 1 shows a view of the U-25 facility. In U-25B, a bypass facility at the main U-25 installation at the Institute of High Temperature of the USSR Academy of Sciences (IVTAN), experiments have been conducted under the joint USSR-U.S.A. programme by using a superconducting magnet. The superconducting magnet was supplied by Argonne National Laboratory, U.S.A. The U-25G is the recent modification at U-25 to study coal combustion. The Unit has been developed as a prototype for a commercial power plant based on coal combustion. It is located in the main U-25 facility in the same area as the U-25B facility. The U-25G facility has been designed to develop: (1) Coal injection systems. (2) Hall voltage isolation for the system. (3) Development of combustors burning coal with a high degree of seed ionization, with minimum losses and capable of long-duration operation of 5000-10,000 hr. (4) Investigation of channel construction and physical processes in the presence of ash at electrode and insulation wall under strong electrical and magnetic fields. (5) Development of high-efficiency diffusers.

ment of U-25, a large-scale fully fledged M H D pilot plant facility, in the late sixties. Both the U-02 and U-25 facilities have provided valuable data for embarking on the 500-MW commercial-scale M H D power plant. Construction work on the 500-MW power plant is under progress at Ryazan near Moscow, and it is expected to be operational by 1988. This will be the first 500-MW M H D commercial plant in the world.

(6) Development of steam generators, ash removal and seed removal systems. (7) Development of seed injection and extraction system along with the study of ash and seed reaction along the path of the system. (8) Investigation of ecological problems. (9) Development of diagnostic methods.

The USSR ministry of power, within the framework of the national programme for the development of M H D power plants, co-ordinates various research and development activities. Under this programme, research and development work is carried out at (a) experimental M H D power plants U-02-500, (b) Krizhizhanovskii Power Research Institute and Estonian Energy Trust, (c) Kohtla Yarbeski Thermal Power Plant, (d) Moscow Unit of the Institute of Atomic and Thermo Electro Project and (e) Kazak Energy

Major parameters of the U-25G facility are given in Table 2. Investigations on U-25G facility are planned for the coming years. It is expected that U-25G will give valuable data for coal-based commercial M H D power plants. 2.1.2. K-1 MHD facility. The K-l M H D facility comes under the Institute for Modeling of Energy Problems, Academy of Sciences, Ukraine. The K-l M H D facility is a 20-30 MW thermal input shortduration (30-40 rain) facility. It uses natural gas as

228

MALGHAN:

MHD POWER PLANTS

Fig. 1. A view of U-25 facility, USSR.

fuel and air with oxygen enrichment up to 85% without preheat as oxidiser. The seed is in the form of a K 2CO3 solution. The combustion product flow rate is 2.3 kg/sec. A Faraday-type diagonal channel has been used with magnetic field of 2 tesla. An electrode current density up to 1 A/cm 2 has been achieved. A maximum power output of 200 kW with specific power of 2.8 MW/m 3 was obtained in short duration tests of 3 ~ 4 0 min. 2.1.3. M-lOand M-25MHDfacilities. The M-10 with 10-MW thermal input and M-25 with 25-MW thermal input coal-based MHD facilities come under the Krizhizhanovskii Power Research Institute and Estonian Energy Trust. These facilities are located at Riga. These facilities provide data for the development of prototype equipment for solid-fuel-fired MHD power plants. In these facilities, coal is used as fuel, preheated enriched oxygen as oxidiser. The oxidiser enrichment is up to 40-50% and preheating is up to 1000K. Electrophysical and thermophysical properties applicable to MHD facilities are being studied in these facilities. 2.1.4. 500-MW MHD commercialpower plant. The first MHD commercial power plant of 500 MW is under erection at Ryazan near Moscow. Construction of a 500-MW MHD commercial plant based on natural gas will serve as a basis for solid fuel plants. The project is controlled by the Ministry of Energy and Electrification. Scientific work of the project is handled by IVTAN. Total power generated will be 582MW, with 270 MW from MHD and 312 MHD from steam. The

superconducting magnet provides a 6-tesla magnetic field. Major parameters of the plant are given in Table 3. The equipment for the plant is being manufactured by various large industrial plants. Seventeen such large industrial plants are involved. High-temperature air preheaters for 1700°C and 10-atm operation are constructed by the Ukraine State Institute for Design of Metallurgical Factories. The combustion chamber of l l00-MW thermal input capacity is developed by the Podolski machine-building factory. The same company is developing and constructing the steam generator ofsupercritical parameters based on combustion products containing potassium compounds. The 500-MW MHD commercial power plant project was started in 1980. Considerable work on research and development and detailed design has been completed. Construction activity was started in 1982. A film showing the construction activity was screened during the conference. It showed the com-

Table 2. Parametersof U-25G facility USSR Fuel

Coat

Seed Magnet

air preheated to 900~C 50% K2CO 3 solution Superconductingmagnet

Combustionproduct flow rate Oxidiser

5 kg/sec

Oxygen-enriched

with 4-tesla field

Machnumberat channelinlet Stagnationtemperatureat the channel entrance Faradayfield Electrodecurrent density

0.8-0.9 2800-2850K 1.5-2kV/m 0.8-1.5A/cm 2

MALGHAN:

MHD POWER PLANTS

Table 3. Major parameters of 500-MW MHD commercialpower plant, USSR Thermal input ll00 MW Power output 582 MW (total) MHD 270MW Steam 312 MW Fuel Natural gas Oxidiser preheat 1700°C temperature Combustor First versionis w i t h o u t refractory lining.Combustor is water cooled by water screen Combustionproduct 230kg/sec mass flow rate Combustor heat loss 80 MW Combustor pressure 10atm Plasma temperature 3040K at channelinlet Plasma velocityat channel 1000m/sec~ sonic MHD channellength 30m Hall potential 40kV Magnet Superconductingmagnetwith a field of 6 tesla at inlet and 4 tesla at the outlet Steam generator Contact type with supercritical parameters. Fuel economy 16% Capacity cost/kW 200roubles

pletion of the foundation work and other erection work under progress. Work planned for 1982-83 has been completed. By the end of 1985, the MHD block will be introduced. The system is expected to be ready for commissioning in 1987 and power generation to start in 1988. 2.1.5. Other activities. Apart from the abovedescribed facilities and activities, the USSR MHD programme includes co-operation/collaboration work with other countries. These include the U.S.A., India, Poland, Finland and other countries. The USSR is a member of the CMEA countries in the field of MHD power generation, 2.2. U.S.A. The Westinghouse Research Laboratories in the U.S.A. attempted to develop MHD generators during and after World War II. Several preliminary studies of MHD power generation processes were made in the U.S.A. in the late 1950s; interest in MHD for both utility power stations and defence applications were apparent. Early work on MHD generators at the AVCO Everett Research Laboratory under the leadership of Arthur Kantrovitz has greatly contributed to the understanding of MHD generators and paved the way for further development worldwide. M H D work in the U.S.A. is being carried out at various universities, laboratories, through government funding and through private consultants, Under the new energy policy, the private sector participation has assumed a greater importance, Important centres are (1) AVCO Everett Research Laboratory, (2) coal fired facilities at the University of Tennessee's Space Institute, Tullahoma, Tennessee, (3) coal combustion work at TRW, California, (4) U.S. Department of Energy's Component

229

Development and Integration Facility (CDIF) at Butte, Montana, (5) Gas Dynamics Laboratory, Stanford University, (6) Arnold Engineering Development Centre, Tullahoma, Tennessee, (7) STD Research Corporation, California (8) Argonne National Laboratory, Illinois, (9) MHD Energy Centre, Mississippi State University, (10) Fluiddyne Engineering Corporation, Minnesota. 2.2.1. A VCO Everett Research Laboratory. The credit for demonstrating the scientific feasibility of MHD power generation goes to AVCO, under the leadership of Arthur R. Kantrovitz. This was demonstrated in an arc-heated argon plasma with seeding in the AVCO Mark I facility in the 1950s. Since the first MHD generator, AVCO has developed and tested a number of generator designs. These generators, from Mark I to Mark VIII, are well known in the literature. Recent work in AVCO is concentrated on coal plasma. A two-stage slagging coal combustor developed by TRW was integrated with an MHD generator developed by AVCO in its Mark VI flow train. Figure 2 shows the experimental facility. The experimental components were rated for 20-MW input. These were engineering prototypes of the 50-MW input to be tested at CDIF. Two types of tests were carried out (1) with coal firing and slag removal, (2) oil-fired ash injected combustor. The objective of these two tests together was to validate the use of oil-fired Ash Injected Combustors (AIC) for the development of coal-fired MHD generators. In these tests, the overall length of the supersonic channel was 2.5 m, with 147 pairs of electrodes. Copper electrodes, clad with various corrosion-resistant metallic caps on the gas side, provided useful data on the behaviour of various electrode materials. Boron nitride was used as the interelectrode insulating material. Dry seed injection was adopted. Roll apart iron core magnets provided a 4-tesla magnetic field. The total test duration was 2 hr. Out of this, 1 hr was for slag development and conductivity measurement and 1 hr was for power generation tests. A maximum steady-state power of 183 kW was obtained. For the ash-injected oil combustion experiments, the same channel was used along with the AVCO designed AIC combustor. To make the comparison as valid as possible, the MHD components were not removed from the facility or in any way modified between the two tests. To get useful comparisons between coal-fired and AIC experiments, the electrical conductivity at the channel inlet of the AIC was maintained the same as in coal combustion. This required reduced seed percentage in the AIC, and the channel output was more or less the same. With the same seed percentage power output in the AIC was more. This leads to the conclusion that the seed injection system, especially the position of the injection nozzle, in the coal combustor was not optimum. However, rectification of this is believed to be straightforward. These experiments have provided

230

MALGHAN: MHD POWER PLANTS

Fig. 2. AVCO coal-fired facility Mark VI, U.S.A.

the basis for coal-fired and AIC tests. These tests have demonstrated the coupling of a slagging combustor to a supersonic generator for 20-MW thermal input conditions. A number of studies related to channel performance have been conducted. These include the effect of current control circuits, cathode slag polarization, etc. The experiments on the Mark VI generator have shown that current control provides uniformities in current distribution and eliminates the excessive electrode erosion common to slagging diagonal generators, The slag polarization produces a more coarse resegmentation, and this results in an increased shortening of the Hall field and associated power loss. This power loss is proportional to electrode pitch to channel height. The relative losses, therefore, decrease with channel size. The most conductive slag results in a 10~ power reduction on Mark VII sized channels, and it is estimated to have less than a 2 ~ effect on a power plant size channel.

2.2.2. University of Tennessee Space Institute (UTSI). Since the first demonstration of successful M H D generator operation with a coal slag in 1974 by the University of Tennessee group, work on coal combustion is continuing. UTSI studies have significantly contributed to the operation of M H D systems with coal combustion. The coal-fired M H D facility has 2-MW input capacity. Pulverised coal and seed mixture is burnt with oxygen. The iron core magnet provides a maximum of about 2.1 tesla,

Recent work included the study of slag polarisation effects and performance of refractories in a coal-fired M H D test train.

2.2.3. Coal combustor development at TRW, California. The TRW Corporation is involved in the development of a 50-MW two-stage slagging coal combustor for the C D I F facility at Butte, Montana. In this direction the 20-MW two-stage slagging coal combustor, which is the engineering prototype of the 50-MW size, has been designed, constructed, and tested by integration with the AVCO Mark VI facility. The combustor is a two-stage vortex flow, allmetal, water-cooled type designed to operate with 2900°F preheated oxidiser at a pressure of 6.0 atm. The first-stage outer shell is made up of SS 304L, and the internal gas side shell is made up of Inconel 625 and Inconel 825. The second stage is constructed with oxygen-free copper. The initial testing of the 50-MW coal combustor is completed for 1984.

2.2.4. Component Development and Integration Facility (CDIF) at Butte, Montana. The Component Development and Integration Facility (CDIF) at Butte, Montana, belongs to the U.S. Department of Energy, and it is operated by the Montana State Energy Incorporated. The facility has been designed to provide a thermal input of 50 M W to the experimental components, with capability for expansion to 100-MW input. The testing facility for coal-fired, as well as oil-fired, ash-injection exist. Two test bays, one with a 3-tesla iron core magnet and another bay with a 6-tesla superconducting magnet, provide test-

MALGHAN:

MHD POWER PLANTS

231

Table 4. Major parameters of CDIF facility, Butte, Montana, U.S.A. Thermal input Fuel

50 MW/100 MW (a) Oil-ash injection (b) Coal 12,0001b/hr at 375 psia 7001b/hr at 180 psia 13,800 lb/hr at 180 psia Air enriched with oxygen (a) No preheating for oil-ash injection test (b) Preheating up to 2900°F for coal-fired tests 75,000 lb/hr at 215 psia 30,000 lb/hr at 300 psia (This is obtained from liquid oxygen storage tanks via electrically heated vaporizers)

(i) Oil flow rate (max) (ii) Fly ash injection rate (max) (iii) Coal injection rate (max) Oxidiser (i) Air flow rate (max) (ii) Gaseous oxygen flow rate (max) Combustion products (i) Oil ash injection test (nominal) (ii) Coal-fired tests Seed (i) Dry anhydrous K 2CO 3 seed flow rate (max) (ii) Liquid seed 50°~ K2CO 3 flow rate (max) Magnet (A) Iron core (i) Field (ii) Warm bore (iii) Power consumption (B) Superconducting (i) Field (ii) Warm bore Channel (i) Configuration with external adjustment (ii) Power dissipation Downstream system

63,690 lb/hr at 88 psia and 4800°F 76,183 Ib/hr at 88 psia and 4700°F 22501b/hr at 180 psia for coal-fired tests 7060 lb/hr at 300 psia at 220°F 3.0 tesla 3.5(L)m × (0.70 x 0.40 m at inlet) to (0.70 x 0.60 m at outlet) 5.3 MW 6.0 tesla 3.1(L)m x (0.78 × 0.98 m at inlet) to (0.98 × 0.98 m at outlet) Faraday/diagonal Through 2800 water-cooled resistors Combustion products are cooled to 190°F by direct quenching with water No provision for testing heat and seed recovery systems

i n g at t w o d i f f e r e n t fields a n d also for o p e r a t i o n w i t h a s u p e r c o n d u c t i n g m a g n e t . T h e r e is n o p r o v i s i o n for t e s t i n g o f h e a t a n d seed r e c o v e r y s y s t e m s . T h e s e a r e b e i n g p l a n n e d to be d e v e l o p e d by u s i n g t h e coal-fired facility o f t h e U n i v e r s i t y o f T e n n e s s e e S p a c e I n s t i t u t e (UTSI). Details of the important systems and parame t e r s o f t h e C D I F facility a r e g i v e n in T a b l e 4. D u r i n g

ii~

~~!!~ii~i~i '

oil-fired tests, t h e c o m b u s t o r is s u p p l i e d w i t h 2 0 0 ° F o x i d i s e r w i t h n o f u r t h e r p r e h e a t i n g . F o r coal-fired tests, t h e c o m b u s t i o n o x i d i s e r c a n be p r e h e a t e d in a n i n d i r e c t l y oil-fired r e c u p e r a t i v e h e a t e r to c a . 1200°F a n d f u r t h e r h e a t e d to 2 9 0 0 ° F w i t h a v i t i a t i o n h e a t e r . A n o v e r a l l view o f t h e M o n t a n a facility is s h o w n in Fig. 3.

!!~ii!~!~iilj!i~F~i

Fig. 3. Overall view of C D I F Butte, Montana, U.S.A. ECM

252

G*

~!~

~

232

MALGHAN:

MHD POWER PLANTS

Table 5. CDIF--oil-ash injected test programme details December 1980 Oil-firedash-injectedtests with air and no power extraction February 1981 Oil-ashinjected tests with air + 02 and no power extraction April 1981 Switch-over from no power to powergeneration tests June 1981 Additional ash injectiontests February 1982 Facilitypower modedemonstrationwith 4-MW output April 1982 Inverter tests April 1982" Coal processed May 1982" Slagging/non-power/power tests October 1982 I MW supplied to grid October 1982 Channelrepair and upgrading April 1983 of channel for 1000-hr test April 1983 15-25hr conductivity tests July 1983 8-hr combustor tests *Coal combustors tested separately.

The testing of the CDIF commenced in 1980 with initial firing of the ash-injected combustor without the MHD channel in place. These tests were continued up to April 1981 when power generation occurred. It required about 5-6 months of testing time from initial testing to first power generation tests. A series of tests up to July 1983 have been completed with the oil-ash injected combustor. The details of these tests are given in Table 5. The 50-MW facility is getting ready for testing with the coal-fired combustor in 1984. The CDIF facility will provide a data base for the Engineering Tests Facility (ETF) design and to simulate the ETF design conditions and eventually include the operation of components prototypic of the ETF. 2.2.5. Other laboratories. Apart from the MHD work described above, MHD research and development work is carried out at various laboratories and institutes. These include the Gas Dynamic Laboratory of Stanford University; Argonne National Laboratory in Illinois; Arnold Engineering Development Center in Tullahoma, Tennessee; STD Research Corporation in Arcadia, California; MHD Energy Center of Mississippi State University; and some private consultants' work. The work in these laboratories is concerned with various problems associated with MHD generators, boundary layers, electrode arcing, numerical analysis of flow problems, etc. The work in these and other institutes in the U.S.A. contributed substantially to the understanding of detailed physical characteristics of MHD generators under various conditions. 2.2.6. Conceptual studies. Apart from the various experiments and theoretical investigations a number of conceptual studies relating to large and commercial-scale M H D power plants have been conducted. Generally, these studies have been sponsored by U.S. Department of Energy (DOE). The interagency-funded, NASA-co-ordinated Energy Conversion Alternative Studies (ECAS) by General Electric and Westinghouse on various MHD cycles is quite well known. The Department of Energy (DOE) is engaged in a national programme to

facilitate early commercialization of MHD-steam power plants with overall efficiencies around 50~o, higher than that of existing base load power plants, meeting all environmental, health and safety standards and to achieve lower costs of electricity. In this direction, recent works include the Magneto-HydroDynamics (MHD) Engineering Test Facility (ETF) 200- MW Power Plant [48] and the conceptual design study of a Potential Early Commercial MHD power plant (CSPEC) [49]. The ETF 200-MW power plant objective is to demonstrate and test an integrated combined coalfired MHD steam system supplying power to a grid, which is prototypic of an early commercial plant. The Conceptual Design Engineering Report (CDER) has been completed, and it provides an initial conceptual design of the ETF and establishes an engineering and economic basis for the ETF project. The major parameters of the ETF system design are given in Table 6. The Conceptual design Study of a Potential Early Commercial power plant (CSPEC) was carried out independently by the AVCO Everett Research Laboratory and General Electric Company. The study was for design of a ca. 1000-MW open-cycle MHD steam plant with oxygen-enriched combustion air preheated to an intermediate temperature in a metallic heat exchanger. Details of the system parameters and estimates by AVCO and General Electric Company are given in Table 7. The AVCO design had an overall efficiency, estimated overnight capital cost, and cost of electricity as 43.9~o, $644/kW and 43.99 mill/kWh, respectively, as against General Electric's estimates of 42.7~o, $907/kW, and 56.7mill/ kWh for the same parameters. AVCO has concluded that its MHD plant design compared favourably in cost of electricity with conventional coal-fired plants of similar capacity. The General Electric Company is making such a comparison as part of a follow-on study. Both AVCO and General Electric have concluded that the MHD plant design had reasonable part load power performance. Dual MHD power trains were not found to be cost-effective. A NASA study on the effect of plant size, preheat temperature and oxidiser enrichment on the CSPECtype MHD plant has shown that (a)the 1000-MW

Table 6. Major parameters of 200-MWETF systemdesign,U.S.A. Typeof plant For base load Thermal input (fuel) 532 MW Poweroutput (net) 202MW Fuel Montana Rosebudcoal Oxidiser Preheated enrichedoxidiserwith 30% of o2 by vol. with temperature of I I00°F Combustor Two-stage coal combustor with combustionproduct temperatureof 4380°F MHD generator Diagonally connected Faraday with gross output of 87.1 MW Magnet Rectangular saddle type with peak field of 6 tesla Heatrecoveryand Radiant boilerconventionpas and ESP seed recovery

MALGHAN:

M H D P O W E R PLANTS

Table 7. Details of system parameters and estimates for 1000-MW open cycle MHD steam power plant, U.S.A. Parameter

Plant size (MW)

Coal type

Combustor Oxidiser (mole% 02) Oxidiser/fuelratio (~ of

AVCO design 949

Montana Rosebud Single-stage 34

0.9 stoichiometric) Seed (~ potassium by wt) 1,0 Generator Diagonal Generator length (m) 21.50 Peak magnetic field (tesla) 6.50 Magnet warm bore area/Generator 1.50 flow area Overall efficiency(~) 43.90 Levelizedcost of electricity 42.99 (mill/kWh)

Overnight capital cost total (M$,--mid-1978) Overnight capital cost per kW ($kW, mid-1978) Construction period (yr)

G.E. design 1090

Montana Rosebud Two-stage 37.6

0.9

1.6 18.0 6.0 3.0

Diagonal

42.7

56.47

614.4

989.1

644.0 5.75

907.0 6.0

plant has about three points higher efficiency than that of the 200-MW plant, (b) preheating to 1600°F gives an efficiency of about 1½ points higher than preheating to 800°F for all plant sizes, (c) for each plant size and preheat temperature there is an oxidiser enrichment level and M H D generator length that gives the highest plant efficiency, The conceptual design study for an early commercial 500 M W (about 225 M W net) has been done by an M H D consultant [3]. The aim of the study was to give thought to near-term commercial M H D power

233

plants as these will influence current work o n c o m ponent development and arrangement of an advanced test facility. It estimates an overall plant efficiency of 4 5 ~ and uses only preheated air of 1300K without oxygen in a radiant heater.

2.3. Japan The M H D programme in Japan is supported by the Agency of Industrial Science and Technology (AIST) and the Ministry of International Trade and Industry (MITI). This is one of the large scale research and development projects for energy conservation, under what is called the "Moonlight Project". The major facility is handled by the Electro Technical Laboratory. Figure 4 shows the ETL Mark VII M H D facility. Table 8 shows the ETL Mark I - M a r k VII M H D generator specifications and performances. The first phase of the project, from 1966 to 1975, was to specify the system concept, to develop components necessary for the system and to test these components in five test facilities--ETL Mark I1 to ETL Mark VI. These tests included (a) high-power short-duration experiments--ETL Mark II, 1980 kW for l min and Mark V, 482 kW for 3 hr; (b) lowpower long-duration experiments--Mark III, 2 kW for 140 hr and Mark V1, 1 kW for 470 hr. In spite of the component developments and testing in two directions as above, it was not possible to provide data for the Engineering Test Plant because of the inability to develop durable and reliable M H D channels in the power generation mode. The second phase of the programme (1976-83)

Fig. 4. ETL Mark VII M H D facility, Japan.

234

Generator ETL Mark I ETL Mark II ETL Mark III ETL Mark IV ETL Mark V ETL Mark VI ETL Mark VII

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Table 8. Specificationsand performances of ETL Mark I Mark VII MHD generators, Japan Magnetic Thermal Mass flow Power flux input rate output Operation density (MW) (kg/sec) (kW) duration (tesla) Remarks 1.2

0.145

2

25.0

3.000 0.350 0.450 0.190

1180

0.025

25.0

3.000

482

13.0

0.340

1

15.0

2.000

100

3.6 2.0

2

10 min

2,2

For basic research

1 min

3.5

Includingair preheater for preheating air to 1320C

140 hr

1.9

Maximumcontinuous running 200 hr

1min

2.0

3 hr

4.5

World's first experiment in combination with superconducting magnet (SCM) Equippedwith SCM and helium gas liquefier

Total 470 hr Total 430 hr

1,0

provided the establishment of the Mark VII facility at Takasago, capable of providing design data for construction of the Engineering Test Plant (10-MW class M H D generator) with special emphasis on durability and reliability of M H D generating channels. The factors influencing the durability of the M H D channel, such as current density, heat flux, plasma flow velocity, electric field, in the E T L M a r k VII facility, can be equal to or simulate those of commercial-scale plants, The E T L M a r k VII uses kerosene as fuel, oxygenenriched air as oxidiser, 480~o K O H aqueous solution as seed and has the capacity for thermal input of 15.1 MW. The iron core magnet can give a maximum of 2.56-tesla magnetic field. SO2 is added to simulate the high sulphur content of the fuel and to confirm the desulphurisation effect of the seeding material and to examine the erosion effect of sulphur content, After completion of the M a r k VII facility in 1981, four runs, as detailed below, have been conducted till 1982. Run No. 1. The aim was to adjust the system components and to confirm the designed functions of the facility as a whole. The M H D power output of 100 kW was confirmed, and the emission standards at the stack were met satisfactorily. Run No. 2. Continuous 200-hr duration tests with SO2 injection were planned. Due to some troubles in the combustor, diffuser and electrostatic precipitators, the plant had to be stopped after 128 hr of operation, Run No. 3. In this run, 100 hr of power generation was achieved. However, after 67 hr of operation the heat input had to be reduced because of overheating of the downstream duct. Run No. 4. M H D power generation at rated output was achieved for 203 continuous hours in 1982. Several kinds of materials and both Faraday and diagonal mode of generation were studied. The behaviour of N O x was also studied, These four runs on the E T L M a r k VII generator have provided a total of about 430 hr of power generation tests with a total of 600 hr of operation of

2.5

Operationof system equipped with air preheaters and seed recovery devices Demonstrationof channel durability

the system with the combustor on. During these tests the accumulated power was 19,983 kWh of which 19,420kWh was at the rated conditions. These experiments provided the designs for the electrode configuration of the generating channel for 2000-MW t h e r m a l i n p u t commercial M H D steam power plants. The life-span of the tested cold wall channel with C u - W cathodes and Pt anodes could be extrapolated to over 2000hr of operation. The alumina coating method was found not to meet always the expectation of durability of several thousand hours, and it is necessary to improve this. Further runs in the E T L Mark VII with coal addition, Run Nos 5 7 have been performed in 1983. These tests include a total of 95 hr of combustion time and 49 hr of power generation time. Coal was injected for a total of 43.5hr. Run No. 7 was completely with coal addition, and the maximum power output of 149 kW was obtained. The objectives of the experiments were to examine the difference of generation characteristics and exhaust gas control technologies with and without coal. The results of these studies are being analysed and will be presented at the 22nd Symposium on Engineering Aspects of M H D at Mississippi, U.S.A., in June 1984 (Kusaka, 1984, personal communication). All seven runs (Runs Nos 1-7) in the E T L Mark VII facility have given very useful data for the Engineering Development facility to demonstrate the component performance in the system. These experiments have demonstrated the capability of the M H D - s t e a m power plant to meet all environmental regulation standards. Apart from the M a r k VII M H D facility, the E T L has a 1.5-MW thermal input with diesel oil or coal/oil as fuel and oxygen as oxidiser; a simulation test facility and a small-size test stand with 350-kW heat input. In the small test stand, propane-coal is used as fuel and oxygen-enriched air as oxidiser. Various kinds of ceramic electrodes and insulators have been tested, and many electrical and thermal parameters have been measured in the simulation test facility. In the small test stand, gas temperatures and potassium

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Table 9. Steps towards commercialMHD power plant in Japan Step Year Remarks Basic research 1930-63 Scientificfeasibilitysystem concept Elementary research and development 1964-83 To specifythe system concept and develop necessarycomponent technologies Engineering developmentplant (ETP) (-) To demonstrate component performances in the system--10MW Demonstration plant (DP) (-) To demonstrate system performance Commercial demonstration (-) Overall evaluation

concentrations have been measured to evaluate the combustion plasma characteristics. Also, electrode phenomena in slagging conditions are studied, Based on the work of Phases I and II, the system study, viz. component line-up, heat balance, emission control, research and development approach, economic feasibility, etc., has been done by the M H D power generation system committee. The committee consisted of experts from universities, national institutions, industrial and utility circles. This committee has completed the conceptual design of the 2000-MW thermal-input coal-fired M H D steam combined power plant. The overall efficiency projected is 48.7~o, with the estimated cost of electricity comparable to a conventional coal power plant, The Japanese programme towards the development of a commercial-scale M H D power plant is envisaged in five steps from basic research to commercial demonstration as given in Table 9. The Japanese programme has completed the second step - - t h e elementary research and development--and is, at present, considering the next step of the engineering Test Plant with a power output of 10 M W with an objective to demonstrate component performance in the system and to confirm the scaling laws of MHD. Because of financial constraints, it has become impossible to start immediately after Phase II to proceed on M H D research and development on a national project for the establishment of the Engineering Test Facility (Kusaka, 1983, personal communication). The emphasis during 1984 and 1985 is for the development of coal combustion, and a hightemperature air preheater in slagging conditions. The proposed M H D research and development activities from 1984 is as follows (Kusaka, 1983, personal communication): (!) Coal Combustor--mechanical engineering laboratory at Tsukuba will start the fundamental research of a coal combustor from 1984. (2) Generating channel----electrotechnical laboratory at Tsukuba will restart the fundamental research of slagging channel from 1984 and promote this research and development programme as a whole, (3) Seed and slag reproduction---chemical engineering laboratory will start the fundamental research of this technology from 1985. (4) Refractory materials for high-temperature air heater--government industrial research institute, Nagoya, will start the selection of promising materials from 1985.

(5) ETL Mark V I I - - n o further experiments on the ETL facility is planned. However, it will be maintained for a few years.

2.4. China M H D power generation studies in China are being conducted Principally at three centres: (1) Institute of Electrical Engineering, Academia Sinica, Beijing-coal-fired M H D facility, (2) Shanghai Power Plant Research Institute, Shanghai--a pilot-scale MHDsteam combined cycle power plant and (3) Energy Conversion Research Laboratory, Nanjing Institute of Technology, Nanjing----conceptual studies and theoretical evaluation of 10-MW coal-fired M H D steam pilot plant.

2.4.1. Coal-fired facility at the Institute of Electrical Engineering, Beijing. The work at the Institute of Electrical Engineering, Beijing, has started in the 1960s. For the last 20 years, oil was used as fuel. Both long-duration and short-duration tests have been carried out. The work on coal firing has started recently. This work consisted of three stages. First the calculation of the thermodynamic and electrophysical properties of coal-fired M H D plasmas; second, experiments with ash injection into an oil combustor; and, third, direct coal firing experiments. The oil fired facility was reconstructed for direct burning of coal. This facility was completed in September 1982, and experiments were conducted in October 1982. Figure 5 shows a view of the facility. Coal ash addition to an oil combustor consisted of two runs. In the first run (1980) of 3-hr duration, the coal ash was injected for about 40 min. Oil and ash were mixed before they were injected into the R-5 combustor. The total combustion product mass flow rate was 1.4 kg/sec with coal ash of 1.7 g/sec. The amount of ash addition was to simulate 80-90~ ejection of coal slag in the coal-fired case. The power output decreased first then increased and reached a maximum at about 20 min after stopping of the ash injection. In the test where the channel insulation was damaged, the power continuously increased and reached a maximum after about 20 min of stopping the ash injection. These results indicate the possibility of slag acting as a protective layer and reducing the electrode voltage drop and also improvement of insulation due to slag. However, these conclusions need further confirmation. In another experiment in 1981, a 10-hr duration test with ash addition were carried out. The

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Fig. 5. MHD facility Beijing, China.

R-8 combustor was used wherein an oil and seed mixture were injected through a set of injectors and ash was injected through another set of injectors. The parameters were the same as of the 1980 experiments, The power output in this test increased gradually after addition of coal ash and reached a maximum after about 1 hr and then gradually decreased. After the experiments, it was found that the channel insulation, on the whole, was degraded. Any definite conclusions on ash injection could not be made with the limited experiments, Some experiments were conducted with direct firing of coal in an oil-fired R-8 combustor without slag ejection. Because of direct burning without slag ejection, the refractory lining of both the combustor and channel were seriously damaged. The preheated air pipe lined with AI203, through which pulverised coal was passed, was seriously eroded especially at the lower part. The ZrO2 lining of the combustor was thinned, and the LaCaCrO3 electrodes were damaged to a certain extent. The MgO lining was very much damaged. However, the high-temperature-alloy electrodes were found to be in good condition. These results point towards the importance of solving material problems in coal-fired facilities. In September 1982, the oil-fired facility was reconstructed for handling coal combustion. The first coal-fired experiment in the R-I 1 combustor with ash injection was conducted in October 1982. The R-11 combustor was of vertical construction with onestage slag ejection and was lined inside with silicon carbide. The vertical type construction helped easy slag ejection.

Details of the facility with important parameters of the first coal-fired experiment with slag ejection are given in Table 10. The results are preliminary in nature and need further investigation.

2.4.2. Oil-fired pilot plant facility at Shanghai Power Plant Research Institute. The Shanghai Power Plant equipment Research Institute along with the Shanghai Electric Machinery Manufacturing Works have been engaged in MHD power research since 1966. In 1971 the short-time low-voltage Faraday generator SM-2 was developed. It gave a power output of 580 kW in the run time of 3 min. In 1973, the high-voltage Hall type MHD generator SM-3 was tested for l hr, and power output of 102kW at 1200V was obtained. Since 1974, the concentration was on utility-type MHD power generation. The work was planned in Table 10. Parameters of coal-fired facility and first coal-fired experiment with slag ejection at Institute of Electrical Engineering Academia Sinica,Beijing, China 5 tonnes

Coal-handling capacity Ratio of coal to N 2 in

30~50:1

Thermal input to combustor

Single-stage slag ejection vertical type--R-I 1 5 MW

fluidisedtransport of coal Typeof combustor Totalmass flow rate Massflow rate of coal Preheat air temperature Time of operation of

1.4-1.44kg/sec 170gm/sec 145(~1500'C 50 min

first experiment Heatloss in the combustor Plasma velocity Plasmaconductivity Hall parameter

17.2'!,, 680 m/sec

Power output

0.48 kW

1.2mho/m 1.6

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237

Table 11. Major parameters of MHD-steam combined cycle pilot plant at Shanghai, China Combustor heat release rate 75.40 MW/m3 Combustion product mass 1 kg/sec flow rate Theoretical combustion 2768K temperature Oxidiser Air preheated to 1450°C in pebble bed regenerative indirectly heated air preheater Fuel Diesel oil

the development of the SM-4 generator. The whole system operated satisfactorily. The longest duration of operation was 200 hr, and the maximum power output was 18 kW with power density of 2.2 M W / m 3.

Total channel length Effectivechannel length Inlet cross-section of channel Exit cross-section of channel Pitch between electrodes Maximum MHD power output Magnet

pressure (14 kg/cm 2) steam at 4 T/hr. This steam can drive a 500-kW generator. As a 500-kW generator set

Seed

Diffuser length Waste heat boiler rating Superheated steam

pressure and temperature Turbogenerator set

Electrostatic precipitators

K2CO3 1500mm

700 mm 150 mm x 70 mm (H × W) 180 mm x 70 mm (H x W) 25 mm 18 kW Iron core magnet with field of 1.82 tesla at center and 1.6 tesla average 1800mm 4.5 T/hr steam 14kg/cm 2, 350cc Low-pressure, single-cylinder impulse, speed reduction condensing turbine; 4-pole 750 kW 1500rpm: 6300 V 50 cycle/secgenerator Effective cross-section of5.1m 2 with capacity of 11,000-1,1,700 m3/hr

two phases. The first phase was devoted to the development of generators with output capacity up to 2 0 k W and operating time of more than 100hr. During this stage, effort was not concentrated on the downstream portion of t h e c o m p l e t e pilot plant. The second phase of operation was devoted to the complete M H D - s t e a m pilot plant to obtain experience in operating the M H D - s t e a m combined cycle, as a whole, and to obtain data for the design and development of individual components of a utility-type M H D - s t e a m combined cycle power plant. The first phase of work was completed in 1976 with

In the second stage of operation, the M H D - s t e a m combined cycle pilot plant was designed, manufactured and operated. The exhaust gas flow from the SM-4 generator at 1850°C was equivalent to the thermal power of 3600 kW. This could produce low-

was not available, a turbine generator set of 750-kW rating was chosen and operated on low load. The major parameters of the M H D - s t e a m combined cycle pilot plant along with details of the individual c0mponents is given in Table 11. Figure 6 shows a view of the facility. The pilot plant was completed in October 1979. M o r e than one year was spent in trial running of various units and assemblies of the combined cycle and the system as a whole. These tests were categorised into (a) separate tests on the individual units of the system, (b) boiler rating tests, (c) commercial operation tests on the steam power generation portion and (d) commissioning tests on the combined system. After these tests, long-duration tests were conducted in June 1981. The total duration of the test was 212 hr including the time for starting of auxiliary equipment and air preheaters. Out of this, 150 hr was spent on continuous operation of the system as a whole. During this time, power generation was for 100hr with a maximum M H D power output of 14.9 kW and steam power of 500 kW. The M H D power was consumed in the test load, and the steam power was fed to the Shanghai grid. Typical parameters of the 100-hr test are given in Table 12. These tests have proved the feasibility of the M H D - s t e a m cycle and verified the design and layout of the plant. Detailed tests on the waste heat boiler

Fig. 6. MHD-steam pilot plant facility, Shanghai, China.

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Table 12. Major parameters of 100hr operation of MHD-steam combined cycle pilot plant at Shanghai, China Combustion product 1 kg/sec Pressure at combustion chamber 1.45 arm abs Pressure at the inlet of the effectivesection 0.830 atm abs of the channel Pressure at the outlet of the effectivesection 0.815 atm abs of the channel Pressure at the inlet diffuser 0.74 atm abs Number of electrodes 34 pairs Magnetic field at the centre 1.77 tesla Average working voltage 81 V Hall voltage 400V Maximum MHD power output 14.9kW Maximum steam power output 500 kW

and electrostatic precipitators have provided very useful data for future designs. The simple techniques used for Hall voltage insulation have been proved to be very satisfactory and have paved the way for large combined cyles. The various electrode materials testing has provided the guidelines for the development of highly efficient electrodes for future M H D channels. The 100-hr test on the M H D - s t e a m combined cycle pilot plant is considered as a great step forward in the M H D power plant programme in China.

2.5. India The Indian M H D p r o g r a m m e is concentrating in establishing a 5-15 M W thermal input M H D pilot plant at Bharat Heavy Electricals Limited, Tiruchirapalli, Tamilnadu. The project is sponsored by the Department of Science and Technology, G o v e r n m e n t of India. Bharat Heavy Electricals Limited (BHEL) and Bhabha Atomic Research Centre (BARC) are involved in establishing the facility. Under the cooperative agreement between the G o v e r n m e n t of India and the G o v e r n m e n t of the USSR, the High Temperature Institute ( I V T A N ) at Moscow is associated with the project. The pilot plant is now commissioned and M H D grade plasma was obtained in March 1985. Power generation experiments are planned at the end of 1985. Apart from the pilot plant work at Tiruchirapalli, M H D work is also being carried out by various universities and industries. Important a m o n g these are the Indian Institute of Technology, Delhi and Bombay. At B A R C , Bombay, smaller experimental rigs A R K 100-100-kW input argon arc plasma facility, 50-kW combustion plasma facility using L P G and 02, and 500-kW combustion plasma facility using alcohol and 02, have been established. These facilities have been useful in developing diagnostic instruments and material characterisation. Test rigs to develop combustors, air preheaters, seed spray characterisation and aerodynamic studies have been established at the M H D Project, Bharat Heavy Electricals Limited, Tiruchirapalli.

2.5.1. Indian M H D pilot plant at BHEL Tiruchirapalli. The Indian M H D Pilot Plant at the Bharat Heavy Electricals Limited, Tiruchirapalli, is a 515-MW thermal input pilot plant facility. It uses blue

water gas (BWG), a coal gas, as fuel; and enriched air (with oxygen enriched up to 40~o) preheated to 1500°C as oxidiser. Pebble bed regenerative air preheaters are used for preheating the oxidiser. K 2CO3 in aqueous solution is used as seed. An iron core magnet with split yoke provides the magnetic field up to a maximum of 2 tesla. The split yoke designed with magnet on the rails provides an easy and quick access to the channel when required. The M H D pilot plant is adequately instrumented and precise control of various parameters during operation is possible through PDP-11 computer. The major parameters of the pilot plant along with its sub-systems detail are given in Table 13. Following is the description of the major facilities and components. (1) BWG fuel system. The fuel system consists of three B W G generators, gas holder and gas compressors. The capacity of the main gas holder is 4250 m 3. Two generators in cyclic operation can produce 60,000 m 3/day of gas with calorific value of 2720 kcal/nm 3. There are two gas compressors, each can deliver 1400 nm 3/hr of gas at a pressure of 7 atm. The system has been completely erected and tested for gas generation. The gas production has met all the requirements with reference to operating sequence, safety regulations, gas compositions, etc. (2) Air compressors. There are two reciprocating type air compressors. Each compressor can deliver 2500 nm 3/hr at 7 atm. The compressors have been installed and tested for their performance. (3) Oxygen plant. Three oxygen plants, each rated for 140nm3/hr of oxygen with 99.5~ purity provide the oxygen for oxygen enrichment of the air. U p to 45~o oxygen enrichment is possible for 1 kg/sec of combustion products through the combustor. The oxygen plants have been erected and are commissioned. (4) Cooling water system. A water treatment plant with capacity of 25m3/hr has been erected and commissioned. It provides 10 m3/hr ofdemineralised

Table 13. Major parameters of the Indian MHD pilot plant at BHEL Tiruchirapalli, India Thermal input 5-15 MW Fuel Blue water gas (BWG) Oxidiser 40% oxygen-enriched air preheated to 1500°C Air preheater 3 Nos. Pebble bed separately fired regenerative air preheaters Seed Aqueous solution of K2CO 3 Combustion product mass 1-3 kg/sec flow rate Maximumcombustion 2800K product temperature Combustor major dimensions ~b350mm, length 1 m Nozzle 350mm dia at inlet and 70 mm x 84 mm at the exit Channel inlet cross-section 70x84mm Channel outlet cross-section 70 x 124mm Active length at channel 1200mm Magnet Iron core magnet with split yoke on rails producing maximum field of 2 tesla Control and data logging of ThroughPDP 11 computer the pilot plant

MALGHAN: MHD POWER PLANTS

239

Fig. 7. Indian MHD pilot plant facility under erection. water and 15 m3/hr of low-conductivity water with conductivity between 0.1 and 0.5/~mho/cm. Lowconductivity water is used for cooling components affected by the Hall potential. Apart from this, heat exchangers to cool the low-conductivity water in the closed loop by the town water system, along with treated water pumps, town water pumps, cooling tower from the complete water system, (5) Air preheater system. The air preheater system consists of three separately fired pebble bed regenerative air preheaters along with hot air ducts and high temperature valves. The air preheaters are filled with high-alumina ceramic pebbles of 20-mm diameter. The bed diameter is 1.2 m, and the bed height is 4.5 m. Refractory and insulating brick lining provide thermal insulation. The shell of the air preheater is water cooled. These air preheaters operate in a cycle and deliver the required quantity of preheated (1500°C) oxidiser (0.8-2.4 kg/sec) to the combustor. In the first phase of a 5-MW input, two air preheaters, and in the second phase of 15-MW input, three air preheaters in cyclic operation are required, (6) Combustion system. The combustor is designed to burn BWG with hot oxidiser. The combustion chamber consists of a double-walled water-cooled metallic vessel with stabilized zirconia lining inside, The seed is injected in the combustion chamber. The combustion chamber has an i.d. of 350 mm and length of 1 m. A water-cooled stainless steel nozzle after the combustion chamber accelerates the plasma from about 60 m/sec to 800 m/sec in a short distance of200mm. (7) Channel and diffuser. The channel and diffuser sections from the nozzle outlet to the diffuser outlet

can be 5.5 m long. The available working section length is 3.0m. The power from the channel is dissipated in a resistive load. Several types of channel designs have been envisaged. A section of the channel was designed, fabricated and tested at the U-02 facility at Moscow, USSR, during May 1980. The total test duration was 65 hr. Though some insulator wall ceramics came off during the tests, the tests could be continued and very valuable results were obtained. An electrode current density of 1 A/cm 2 could be achieved during the tests. These tests have given experience in the design and fabrication of channels. (8) Magnet. A split yoke iron core magnet on rails provides the maximum field of 2 tesla. The split yoke design helps easy movement of the magnet for quick and easy channel access. The warm bore of the magnet is 500 mm x 650 mm x 3000 mm. The power consumption of the magnet is 750 kW. (9) Downstream heat and seed recovery system. Hot gases from the channel, in the first phases, are cooled by a spray cooling system. A waste heat boiler is envisaged in the second phase. Wet seed recovery is achieved through the foaming apparatus, venturi scrubber and cyclone separator. The equipment, as described above, has been designed, fabricated and are in the advanced stage of erection, testing and commissioning. Figure 7 shows the part of the facility under erection. An overview of the Indian M H D pilot plant is shown in Fig. 8. The pilot plant was commissioned in March 1985 and power generation experiments to start in the end of 1985. Valuable design and performance data on various equipment and plant, as a whole, will be collected during the coming years.

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Future plans include the study of coal combustion, commercial-scale power plant conceptual designs and application of M H D to power-intensive processes like aluminium extraction, 2.6. The Netherlands

M H D activities in the Netherlands are controlled by the Netherlands M H D Association (NMA). This association was established in 1978 by a group of Dutch industries and institutes with the aim to promote both industrial research and development in the field of M H D power generation and early introduction of M H D power systems in Western Europe. The following organisations are members of the association: (1) FDO Engineering Consultants, Amsterdam, (2) Stork Boilers, Hengelo, (3) Holec, Electrical Machines and Systems, Hengelo, (4) ESTS Engineering, ljmuiden, (5) Netherlands Energy Research Foundation ECN Petten, (6) National Aerospace Laboratory NLR Amsterdam, (7) Eindhoven University of Technology, Eindhoven. The activities of the association are supported by the Dutch Government. The activities in past years covered conceptual design studies of base load power stations with open and closed cycle M H D topping cycles, plasma physical experiments at the Eindhoven University of Technology, material research and development for MHD applications, code develop-

ment for M H D generators and systems, and component developments. The component developments included a coal combustor with clean exhaust gases, high-temperature regenerator and recuperator, MHD channel, super conducting magnet, D C - A C conversion, radiant boilers, etc. The main M H D activity in the Netherlands is concentrated on the closed cycle MHD conversion process. The 5-MW blow-down facility at the Eindhoven University of Technology is the largest closed cycle facility in the world. A general view of the facility is shown in Fig. 9. The work at the Eindhoven University of Technology is continuing since 1965. The 5-MW blow-down facility has been designed and constructed for a fossil fuel operation. The Ar-Cs plasma is used in the non-equilibrium MHD generator. Argon gas is heated by a fossil-fuel-fired heat exchanger. The heat source for the heater is propane and air. An argon mass flow rate of 5 kg/sec during a 60-sec blow-down can be obtained at a temperature of 2000K. The cryogenic magnet provides a magnetic field of 5 tesla during the operation. A stagnation temperature of 1900K and pressure of 7 bar were used during the experiments. The first gas dynamic experiments on the Eindhoven blow down facility were reported in the 7th International Conference on MHD in 1980 [50]. After successful completion of the first series of experiments, the second to fifth series of experiments have been completed. The aim of the second series of experiments was to test the complete facility up to the nominal conditions of all subsystems and to achieve substantial enthalpy extraction. In this series of experiments, the channel of the first series, which

Fig. 8. Overview of the Indian MHD pilot plant.

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241

Fig. 9. A view of the Eindhoven blow down facility, The Netherlands.

was in good condition, was used. Boron nitride (BN) A development programme to arrive at a new was the inside lining material. In the third series of concept for a pulverised coal combustor combined experiments, the new channel, with the same geom- with a high-temperature filter to remove slag or fly etry but lined inside with silicon nitride (Si3N4), was ash in the exhaust gases has been established in 1983 tested. The fourth series of experiments was for (Giessen, personal communication). A new design studying M H D generator performance with pre- eliminates the slag or fly ash in the exhaust gases and heated walls. These sets of experiments were con- has the capability to desulphurise. In recent months, ducted as a joint programme of the U.S.A. and the techno-economical evaluation has shown that a Netherlands. The inner wall of the channel was BN significant cost saving can be achieved with this new with electrodes of molybdenum. Due to a mal- type of coal combustor with high-temperature filter function in one of the cooling panels of the channels, as compared to a conventional cyclone-type coal the experiments in the preheated mode could not be combustor. A patent application for this new type of continued, combustor has been made in November 1983. The results indicate that the power would start Other activities include basic design for a 65-MW fllowing when the magnetic field B was greater than generator, and this has given valuable information 3.5 tesla and stop when B is less than 2.77 tesla, with respect to start up, part load operation and Power output was more than proportional to B 2. A improvement of reliability. Also, the effect of up and maximum enthalpy extraction of7.1~o with 360-kW down scaling and its economic impact has been power has been achieved. The aim is to reach 20~o established for the complete power train. enthalpy extraction during 10 sec of operation. The For the near future, the following activities have experiments have shown that it is possible to obtain been planned as part of the Dutch M H D programme a smooth electrical power output with a highly (Giessen, 1983, personal communication): non-homogeneous discharge structure in the bulk of the plasma. (a) Coupling of closed cycle M H D to the power Apart from the blow-down facility, a 5-MW shock grid. In this effort, the work includes; system study tunnel facility has increased the scientific information and optimisation of electrode configuration including on closed cycle M H D conversion processes substan- pitch length, diagonal conducting walls and disc tiaily. The facility has generated 1.4-MW power with geometry; design, construction and operation of a an electrical power density up to 104-MW/m 3 and an D C - A C inverter unit at 30-kW level; connection of enthalpy extraction of 24~ during the 5 msec test inverter system to one electrode pair of the blowtime. down facility and operation of the system.

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Fig. 10. White Bay MHD facility, Australia. (b) Research work towards improving the life of refractory materials for M H D high-temperature regenerative and recuperative heat exchangers. Predesign for recuperative heat exchanger. (c) The burner development with laboratory tests and detailed design and subsequent testing of an 8-MW pilot installation, (d) Further design optimisation of power train in 1984, as part of an integral topping system design project and initial hardware testing. (e) Disc generator experiments. Funds have been made available for this, and the programme has been started, The Netherlands M H D Association, as engineers and consultants, offer to undertake detailed technical and commercial studies of M H D systems and components, 2. 7. Australia Interest in M H D power generation in Australia is not because of savings in fuel cost due to higher efficiency of MHD, but is due to the substantially reduced cooling water requirements of M H D power plants. This is because coal is available in plenty, power stations are located very near to the coal mines, and the mining costs are very much less. The saving in fuel cost due to higher efficiency does not have much impact on the cost of electricity in Australia. As new power plants have to move to more remote areas in Australia where water is scarce, the reduced water requirement associated with higher efficiency has a significant impact on the power

system planning in Australia. The M H D activities were started on a small scale in the early 1960s at the School of Electrical Engineering, Sydney University. Since 1978, significant expansion of M H D activites has taken place when the work on 4-MW thermal M H D facility was started at the White Bay power station of the Electricity Commission of NSW. Apart from the School of Electrical Engineering at the University of Sydney, CSIRO, the University of Newcastle (NSW) and Monash University (Victoria) are involved in coal studies relevant to MHD. The White Bay M H D facility has a thermal input capacity of 4 MW and supports a linear duct experiment of 2-MW thermal input and disc experiment of 3-MW thermal input. Figure 10 shows a general view of the facility. A conventional electromagnet serves both the experiments. The White Bay facility has been designed and constructed. All the components except the cast magnet yoke has been constructed by the School of Electrical Engineering. The programme was greatly helped by close co-operation with the high-temperature gas dynamics laboratory at Stanford University, U.S.A. The major parameters of the facility are given in Table 14. The 2-MW linear facility consists of combustor, dwell chamber of plenum, duct, diffuser and quench system. The combustor is made of stainless steel, the channel of copper and the diffuser of brass. All sections are independently water cooled. The combustor plenum and duct are lined with 95~ MgO commercial refractory bricks out to shape. The combustor uses ethyl alcohol as fuel. A coal-alcohol slurry was used in the slagging experiments. Coal to alcohol ratio of 1:7 by

MALGHAN: MHD POWER PLANTS weight was used to simulate the combustion of pure coal in a combustor with 90~o slag rejection. The 3-MW disc generator work is proceeding along both experimental and theoretical lines. The disc is designed for a radial outflow geometry, and swirl is introduced in the combustor to assess the effect of low swirl values on the performance, The magnet is a conventional water-cooled electromagnet producing a maximum flux density of 2.7 tesla. The yoke halves have been split vertically to provide easy access to the generators, Data acquisition is through a system built around the PDP 11/03. Both a solid-state invertor system and a rotary invertor system for operation with the 2-MW linear duct has been designed and constructed, Apart from the experimental facility, studies on the characteristics of Australian coal and generator performance analysis and simulation are being carried out. 2.8. Poland Work connected with M H D in Poland is concentrated at the Institute of Nuclear Research, Swirek, and the Institute of Heat Technology Polytechnic of Gdansk, Gdansk. The Polish effort has been directed towards coal combustion of pulverised coal to produce exhaust gases with an electrical conductivity of 6-8 mho/m with a thermal input level of 5 MW. This work has been performed jointly with the U.S. DOE and the ENIN, USSR. Several hundred hours of operation with coal combustion have been accumulated. The work on the design, construction and testing of the M H D generator with insulation walls and electrodes uniformly covered by a slag layer and with special leak-proof solution for water circuits has been jointly carried out with IVTAN, USSR; half of the generator was built in Poland, another half was built in the USSR. The generator walls and electrodes were covered by a slag layer. Short-duration tests of several hours have been conducted on this generator, and the correctness of the design confirmed.

Table 14. Parameters of White Bay M H D facility, Australia Thermal input

Fuel Oxidiser Seed Slaggingexperiments Magnet Linear duct facility a. Thermal input b. Cross-sectionuniform c. Electrode pairs d. Estimatedpower output e. Load factor Disc generator a. Thermal input b. Flow Inventors Data acquisitionsystem

E.C.M. 25/2 H

4 MW

Alcohol 02 and air KOH With coal-alcoholslurry Verticallysplit conventional electro magnet with maximum of 2.7-teslafield 2 MW 30 mm x 100mm 20 8kW 0.7 3MW Radial outflow Solid-stateand rotary t y p e System built up around PDP 11/03 computer

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The 5-MW M H D facility at the Institute of Nuclear Research, Swirek, has been modified and retrofitted for testing the process of coal gasification based on sub-stoichiometric combustor operation and very rapid pyrolysis by combination gases. This method of coal gasification leads to extremely small dimensions as compared to the existing classical solution. At the Polytechnic of Gdansk, M HD generator outlet conditions were simulated by burning propane with oxygen to get 2300°C. These gases were used for gasification of ground coal in a reactor with a liquid slag layer. Chemical regeneration of heat in the M H D cycle was used to produce coal gas containing CO and H2. Some experiments on the devolatisation of ground coal by using exhaust gases from the M H D generator in a grateless fluidised bed boiler are in progress. This process enables one to obtain complex hydrocarbons rather than simple combustible gases. Recently, Poland's Ministry of Energy decided to put more effort into work on problems of coal gasification for the combined cycle (gas + steam turbine) (Brozowski, 1983, personal communication). Hence, the M H D activities have been considerably curtailed, and the M H D test rigs have been converted for testing new methods of fast pyrolysis applied to coal gasification. 2.9. Finland The work of M H D power generation in Finland is being carried out at the Tampere University of Technology. This includes academic research and development in selected areas as well as development of components for an industrial M H D power plant by the Finnish industrial companies. The areas of study include (Kuttunen, 1983, pesonal communication):

(1) the study of electrophysical near-electrode process under M H D channel conditions; (2) research and development of high-temperature materials for M H D channels; (3) the study of electro-technical problems connecting M H D generator to electric power network. 2.10. Co-operative work o f C M E A countries in M H D field

The Council for Mutual Economic Assistance (CMEA) member countries have a co-operative programme towards the development of M H D power plants. The aim of the CMEA countries' co-operative work in this area is to establish M H D power plants using gaseous, liquid and solid fuels and to introduce the M H D method of energy transformation into industry. The USSR, Bulgaria, Yugoslavia, Poland, Romania and Czechoslovakia are actively participating in this programme. CMEA activities are described in Refs [45] and [46]. Activities carried out by some of the CMEA members have already been described in the previous sections. The following

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paragraphs describe important M H D activities and achievements of the CMEA. Bulgaria, Yugoslavia, Poland and Romania have carried out a feasibility study on the efficiency of M H D power stations under conditions of rational power systems. The possibilities of using the coal reserves of these countries for M H D power stations have been studied, At the " F E R O X " enterprise (Czechoslovakia), a unique helium TK-3200 cryostat has been manufactured by order from IVTAN, USSR, to test sections of large superconducting magnetic systems, Czechoslovak and Soviet specialists have made a technical proposal for a steam generator of the 500-MW industrial M H D power stations, The USSR and Hungary have produced experimental stands to study electrode processes in the plasma of combustion products with an alkaline admixture. The studies have been conducted with the use of laser-holographic methods worked out by Hungarian experts. Experts from Czechoslovakia and Yugoslavia have developed methods and algorithms for computing the electrophysical thermodynamic and transport properties of plasma combustion products in M H D generators, A feasibility study has been carried out in Bulgaria on high-temperature heaters for technological processes in ferrous and non-ferrous metallurgy. These are being proposed for heat exchangers in industry by the USSR and Bulgaria.

3. ANALYSIS OF INTERNATIONAL PROGRAMMES AND DIRECTIONS The M H D effort described in the previous sections gives an insight into the efforts of various countries towards the development of commercial M H D power plants. The present effort and direction can be classified into various categories based on the size of the plant; operating time and type of fuels used; and type of oxidiser and preheating requirement. From the analysis of various programmes, the present direction towards commercial plants appears to follow the following lines. (1) Laboratory-scale facilities. These facilities have been generally designed for short-duration experiments. The operation time varies from a few minutes to a few hours. The effort in these test facilities is towards the development of materials, generator configurations, diagnostic techniques, etc. The emphasis is on solving fundamental physical problems, All countries are having continued efforts on this scale of experiments. (2) Pilot plant facilities of 5-15-MW thermal input. The facilities in this range give a good amount of flexibility to simulate various parameters of commercial-scale power plants. The operating time in these facilities is generally of the order of a few

hundreds of hours. The pilot plant experiments are used to develop various M M H D components. The USSR, U.S.A., Japan and China have already built facilities in this class and have operated for more than 100 hr of continuous operation. The Australian facility has been constructed. The Indian facility completed first run in March 1985 and MHD grade plasma is obtained. In this class of facility, the fuels natural gas, coal gas, oil with ash injection, and direct burning of coal have been tried, and also the oxidisers with oxygen enrichment and preheating. These facilities have offered the testing of complete MHDsteam combined cycles under various operating conditions and have provided valuable experience and data towards commercial M H D power plants. (3) Pilot plants of 50-100-MW thermal input. As the M H D process is a volume process, the size effect plays a very important role. This size of plant provides the evaluation of larger sized components and establishment of scaling laws. The USSR's U-25 and U.S.A.'s CDIF facilities come under this category. Japan's proposed ETL 10-MW electric output facility comes under this class. The U-25 experiments have paved the way for the USSR's going for a 500-MW commercial plant. The U.S.A.'s CDIF has established a 50-MW facility and has completed more than 100 hr of continuous testing with oil. The CDIF facility envisages upgrading to 100-MW input. This class of facility is very important in the development of commerical M H D power plants. (4) Large-scale facilities of 500-MW thermal input class (200 MW). In this class of facility, the aim is to demonstrate and test an integrated combined MHDsteam power plant which is to be prototypic of early commercial plants. The U.S.A. and Japan are having proposals in this direction. The USSR has, however, skipped this step and has gone directly for a 500-MW commercial plant. (5) 500-MW early commercial plants. Early commercial plants of this class will demonstrate the expected advantages along with meeting pollution standards on commercial-scale plants. These first generations of commercial plants will provide data and experience for the next generation and larger size plants. (6) 1000-MW commercial plants. MHD-steam commercial plants will eventually reach this class of capacity. The U.S.A. has completed a conceptual design of commercial plants in this class. From the above discussions it is clear that the USSR has reached the 500-MW commercial-scale plant, the U.S.A. and Japan following it. The efforts in other countries is concentrated at present around 5-15-MW thermal input class facilities. Though the USSR has embarked on a 500-MW commercial plant, it is to be noted that this is based on natural gas as the fuel. Eventually, commercial plants are to be based on direct burning of coals. The USSR is putting efforts in this direction of direct coal cornbustion. The effort of the U.S.A. in establishing the

MALGHAN: MHD POWER PLANTS 200-MW Engineering Test Facility (ETF) with coal combustion would be very valuable, Vertically split or roll apart magnets have been used in some of the facilities, e.g. AVCO, CDIF, White Bay Australian facility and the Indian facility, This design of magnet gives easy and quick access to the channel when required. It is important to develop this type of magnet design for commercial plants, It is worth emphasising that almost all facilities had problems during the first few runs, and experiments were either stopped or continued at reduced parameters. For most facilities, it took from 6 months to more than a year to commission after the facility had been constructed. These points only highlight the number of problems still associated with establishing and testing various classes of M H D facilities, 4. PROBLEM AREAS AND FUTURE EFFORTS The discussion in the previous section gives the general direction of international efforts towards commercialisation of M H D power plants. Many problems are to be solved while proceeding in this direction. These problems and required future efforts were very effectively presented by Academician Scheindlin in his lecture delivered after receiving the Faraday Medal at the Eighth International Conference on M H D Electrical Power Generation. Accordingly, the problems can be classified as (1) physicotechnical problems, (2) technological and engineering problems, and (3)cost-related problems.

(1) Physico-technicalproblems These problems are related to the plasma characteristics. The choice between equilibrium and nonequilibrium plasma is not yet clear. So also, the use of a liquid metal generator is not ruled out. The present-day combustion plasma electrical conductivity of the order of 10 mho/m is not satisfactory, The low electrical conductivity of the plasma forces the use of a superconducting magnet of 5-6 tesla, Increasing the plasma conductivity to 200-1000 mho/m is a very important problem. Today, we do not know how to achieve this. Micro-arc discharges lead to the destruction of electrodes. This curtails the life of channels. These micro-arcs induce fast fluctuations in the channel. It is possible to create suitable electronic circuits to avoid micro-arcs.

(2) Technological andengineeringproblems Many technological problems are associated with component developments. For the air preheat temperatures of 1700-2000°C required for commercial M H D power plants, presently regenerative air preheaters have been considered. However, according to the second law of thermodynamics, a penalty is paid in regeneration. Effort is required towards the development of recuperators,

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Today, there do not appear to be any large problems in the manufacture of superconducting cables. However, today's superconducting magnet design does not have a convenient structure. Working with this magnet arrangement is very cumbersome. For commercial plants, a warm bore of about 2 m dia and 20 m length is required. The channel has to be located in this warm bore. This has to be dismantled. This is a very cumbersome process. Hence, the development of a superconducting magnet with a facility for easy and quick access to the channel is very important. This is a realistic problem. The inverter substation is an extra component in the M H D system, as M H D produces DC power. Inverter units tend to be very large. The inverter must be simplified to reduce its cost. The development of coal-fired MHD facilities is very important. Applying coal is not easy. Slag removal, slag and seed interaction and removal of seed from slag are important and exceedingly difficult problems. Engineering solutions to these are not yet available. (3) Cost-related problems Cost is ultimately the decisive factor in acceptability of M H D power stations by the utility cornpanics. Making MHD power plants cost-effective is very important. To quote Academician Scheindlin: "If we solve this, we will succeed, otherwise M H D will be in proceedings and papers". Seed in the downstream section is unpleasant. M H D should be considered in applications where seed is not harmful but beneficial. Application of M H D in a combined cycle with gasification of coal using exhaust gases from the M H D channel is very important. Poland has started effort in this direction. Future efforts should be directed towards solving many of these problems. Towards this end, it is important to establish a couple of early commercial M H D power plants. These plants only will solve many technological and operation problems of MHD commercial power plants. With the coming of the first 500-MW M H D commercial plant in the USSR by 1988, it is projected that a couple of M H D commerical plants will come up by the year 2000. 5. CONCLUSIONS The Eighth International Conference on M H D Electrical Power Generation at Moscow, on 12-18 September 1983, provided a useful forum for presentation and discussion of various national M H D programmes and efforts towards commercialization of M H D power plants. The first 500-MW M H D commercial plant is expected to be operational in the USSR by 1988. The effort of the U.S.A. has reached testing in the 50-100-MW thermal input M H D facility. Japan has completed a 5-15-MW thermal input class facility. China has built and completed 100hr of continuous testing in a 5-

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15-MW class facility. In this 5 - 1 5 - M W t h e r m a l i n p u t class, the A u s t r a l i a n W h i t e Bay Facility has been constructed, a n d the I n d i a n M H D Pilot P l a n t is n o w commissioned. T h e N e t h e r l a n d s 5 - M W t h e r m a l b l o w - d o w n facility has gone t h r o u g h five series o f tests. P o l a n d ' s efforts are c o n c e n t r a t e d on coal gasification using exhaust gases from a M H D generator, F i n l a n d ' s p r o g r a m m e emphasizes M H D material development. M a n y physico-technical, technological a n d engineering, a n d cost-related p r o b l e m s are to be solved before M H D commercial plants b e c o m e a reality. It is projected t h a t a couple o f M H D power plants will come u p by the year 2000. However, it is i m p o r t a n t to realise A c a d e m i c i a n Scheindlin's statem e n t on the i m p o r t a n c e of cost-effectiveness, are due to colleagues in the MHD project for many useful discussions. The author is thankful to the management of BHEL for permission to publish this paper and giving the opportunity to attend the Eighth International Conference on MHD Electrical Power Generation at Moscow, without which this paper could not have been possible. This work was carried out under the project sponsored by DST/CASE Government of India. Acknowledgements--Thanks

REFERENCES I. Papers f r o m 8th International Conference on M H D Electrical Power Generation, Moscow, 12-18 September 1983

1. F. A. Hals, C. C. P. Pian et al., Results from comparative analysis of different MHD generator and power train designs for early commercial power plant applications. Paper No. AI. 2. S. Cervenka and R. A. van der Laken, Results from study of a 500 MW coal fired closed cycle MHD-plant. Paper No. A3. 3. S. Way, Conceptual design study for an early commercial 500 MW (th) MHD-Power Plant. Paper No. A6. 4. V. M. Maslennikov, V. M. Belaikin et al., Analysis and optimization of comprehensive energy-effective scheme of MHD power plant involving the processing of coal and production of bound nitrogen. Paper No. A8. 5. V. A. Kirillin, A. E. Scheindlin et al., Development and designing of gas and oil fired commercial MHD power generating unit. Paper No. A9. 6. Yu. Cherven, Studies aimed at providing technical and economic grounds for the development of pilot powergenerating unit topped with MHD generator. Paper No. A13. 7. W. D. Jackson, T. R. Johnson et al., Technical status of MHD in the United States: an overview. Paper No. AI4. 8. V. R. Ramaprasad, Commercial outlook for MHDsteam power plants in India. Paper No. A16. 9. W. D. Jackson, Integration of power stations with electric utility networks. Paper No. AI7. 10. Y. Kusaka, K. Takano et al., Experiments of ETL Mark VII MHD-facility. Paper No. B1. 11. N. I. Mazur, A. I. Bystryi et al., K-I MHD facility: basic parameters and investigation results. Paper No. B2. 12. Changgi Yang, Bingnan Wang et al., 2-MW MHDgenerator test facility. Paper No. B3. 13. H. J. Flinsenberg, W. J. M. Balemans et al., Power extraction experiments with the Eindhoven MHD blow-down facility. Paper No. B4.

14. G. Enos, R. Kessler et al., MHD-generator performance comparisons between coal and oil + ash firing. Paper No. B5. 15. Chengze Liu, Zongxum Shu et al., Experimental investigations on a pilot-scale MHD-steam combined cycle plant. Paper No. B6. 16. V. M. Batenin, R. R. Grigoriants et al., U-25G MHD facility for coal firing. Paper No. B7. 17. Changqi Yand, Zi-Xiang Ju et al., Preliminary investigation of the coal-fired MHD power generating. Paper No. B8. 18. Aiqiang Zhu and Yiqian Xu, Calculation and thermodynamic analysis for projects of a 10 MW coal-fired MHD-steam combined cycle pilot power plant. Paper No. B9. 19. D. G. Zhimerin, E. A. Aman et al., Research and development work related to prototype equipment for solid fuel-fired MHD power plant, conducted by Krzhizhanovskii Power Research Institute and Estonian Energy Trust within the framework of the U.S.S.R. program for the development of open-cycle MHD power plants. Paper No. B10. 20. H. K. Messerle, S. W. Simpson et al., MHD studies in Australia. Paper No. BII. 21. D. G. Zhimerin and F. V. Sapozhnikov, Research and development carried out by the U.S.S.R. Ministry for Power within the framework of the National program for the development of MHD power plants. Paper No. B12. 22. Changqi Yan, The investigation of MHD power generation in China. Paper No. B13. 23. A. M. Demirjian, V. J. Hruby et al., The effect of current control circuits on MHD generator performance. Paper No. CI. 24. A. Adamusz and V. Lysiak, Special design MHD generator utilizing coal combustion products. Paper No. C2. 25. V. A. Bityurin, V. A. Zhelnin et al., Numerical modeling of nonuniform flows in MHD generator channel and its application in the processing of experimental data. Paper No. C3. 26. A. K. Baulin, A. V. Karpukhin et al., MHD channel of U-25G facility utilizing direct coal combustion products. Paper No. C4. 27. N. Kayukawa, Y. Aoki et al., Experimental investigation on the performance improvements for an MHD generator through transversal shaping of the magnetic induction. Paper No. C5. 28. S. W. Petty, Effects of cathode slag polarization on MHD generator performance. Paper No. C9. 29. C. Ambasankaran, V. K. Rohatgi et al., Indo-Soviet MHD experiment. Paper No. C12. 30. R. Hernberg, E. Hakala e~ al., Boundary layer breakdown and discharges on cold cathodes in an alkaliseeded plasma. Paper No. D3. 31. C. H. Kruger and S. L. Girshick, A review of MHD Boundary layer research at Stanford, with emphasis on measurements of the effects of secondary flows. Paper No. E5. 32. J. M. Sherik and G. E. Staats, Status of testing at US Department of Energy's component development and integration facility (CDIF). Paper No. El5. 33. O. Hassi, Research and development in Finland for MHD power generation. Paper No. GI2. 34. M. Bauer, R. Braswell et al., Development status of the TRW 20 MW coal combustor. Paper No. HI5. 35. D. P. Saari, High temperature and intermediate ternperature ceramic oxidant heaters for open cycle MHD. Paper No. I8. 36. D. van der Giessen, Optimization strategy for regenerative argon heater park for closed cycle MHD. Paper No. 19.

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37. B. Vasudevan and S. A. Arunachalam, Development of Combustors for regenerative preheaters. Paper No. I17. 38. V. R. Malghan, K. Thiagarajan et al., Development of high temperature pebble bed regenerative air preheaters for Indian installation. Paper No. I18. 39. W. S. Brzozowski, J. Dul et al., Coal gasification method based on MHD technology. Paper No. N5. 40. W. Pudlik, J. Stasiek et al., Experimental with gasification of ground coal by outlet gases from the MHD generator. Paper No. N7. 41. M. Rogowski, W. Pudlik, Devolatilization of ground coal by exhaust gases from an MHD generator in a grateless fluidized bed reactor. Paper No. N9.

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II. Other published literature 42. Gilbert-Commonwealth Engineers-Consultants, DOE/ NASA/0224-1, NASA CR-165452 Vol. 1 (1981). 43. P. J. Staiger and P. F. Penko, DOE/NASA/10769-21, NASA TM-82734 (1982). 44. M. M. Sluyter, A. L. Liccardi et al., 7th Int. Conf. MHD electrical power generation, Boston, 16-20 June 1980, Paper No. A4 (1980). 45. Multilateral Scientific and Technological Co-operation Among the C M E A Member Countries. CMEA Secretariat Publication, Moscow (1982). 46. N. I. Gorbonova, S. I. Pishikov et al., Paper distributed at 8th Int. Conf. on MHD electrical power generation, Moscow (1983).