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ORC power plant for electricity production from forest and agriculture biomass
Energy Conversion and Management xxx (2014) xxx–xxx
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Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman
ORC power plant for electricity production from forest and agriculture biomass A. Borsukiewicz-Gozdur ⇑, S. Wis´niewski, S. Mocarski, M. Ban´kowski ORC Power Plants Research and Development Centre, West Pomeranian University of Technology, al. Piastów 17, Szczecin, Poland
a r t i c l e
i n f o
Article history: Available online xxxx Keywords: ORC CHP Wood biomass Working fluid Cogeneration
a b s t r a c t The paper presents the calculation results for three variants of CHP plant fuelled by sawmill biomass. The plant shall produce electricity and heat for a drying chamber. An analysis of the system efficiency for four different working fluids was conducted: octamethyltrisiloxane, methylcyclohexane, methanol and water. The highest electric power was obtained for the system with internal regeneration and methylcyclohexane applied as the ‘‘dry’’ working fluid, the highest temperature to supply the drying chamber was obtained for the system with external regeneration and octamethyltrisiloxane applied as the working fluid. The results of the analysis indicate that, by proper choice of the working fluid and of the regeneration variant (internal or external), it is possible to ‘‘adjust’’ the work of the system to the needs and expectations of the plant investor (user). Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction For many years, the West Pomeranian University of Technology in Szczecin, Poland, has conducted research aimed at developing technologies for distributed generation of electricity by using the ORC technology, with a particular focus having been placed on utilization of geothermal energy [1] and low temperature waste heat [2]. This paper presents proposals of the ORC power plant solutions to be applied for utilization of sawmill waste and other types of wood waste. Currently, in Poland, plants of this kind utilize sawmill waste for heating and drying only. On the other hand, as shown in [3], both generation and utilization of the respective source heat can be optimized. Effectiveness of the wood dryers performance is there analyzed for various drying technologies (such with air heat exchangers or with standard or absorption heat pumps), and electricity and heat consumption are for those processes presented and referenced to the cumulative sawmill production in Sweden. Sawmill waste, as well as other types of biomass (straw, corn stalks) can be converted into some intermediate fuel, e.g. in the form of pellets, if the plant possesses a suitable production line and marketing ability. Examples of respective energy conversion systems are presented in [4]. However, the trends in the energy developments are to produce electricity ‘‘on site’’, that is without a need to transport biomass waste to power plants, which also fits ⇑ Corresponding author. E-mail address: [email protected] (A. Borsukiewicz-Gozdur).
in perfectly with the idea of distributed generation. In addition, the combined production of electricity and heat (i.e. not only of heat as it is usually done now) is one of the best ways to increase the efficiency of energy conversion processes. At present, there are principally two technologies of the distributed combined heat and power generation that are considered in respect to the biomass utilization: – internal combustion piston engine (IC Engine) fuelled with syngas generated in a biomass gasification system, – turbine based CHP plant with either steam turbine or vapour turbine working with organic fluids (ORC plant), with energy input from appropriate biomass boilers. Such plant can be also driven with heat from the biogas fired boilers. Other CHP technologies, such as those based on fuel cells, gas turbines, Stirling engines and others are still in the developing phase and are expected to be commercially available in the next few years. The techno-economic analysis of the ORC system with input from a gasification system is presented in [5] for the case of bioenergy applications. It results from that analysis that, in respect to the proportion of generation of electricity versus heat, the high temperature system incorporating biomass gasification and biogas fired piston engine appears as more advantageous. On the other hand, biomass combustion and the resulting heat conversion by means of the ORC system is technologically more matured and burdened with less risk, and is applied more frequently. A comparative analysis of the
http://dx.doi.org/10.1016/j.enconman.2014.04.098 0196-8904/Ó 2014 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx
Nomenclature cp h _ m p P S T Td,max Q_ DT
g
specific heat at constant pressure, kJ/kg K specific enthalpy, kJ/kg mass flow rate, kg/s pressure, MPa power, kW entropy, kJ/kg K temperature, °C maximum temperature value of air supplied to the drying chamber, °C heat flow rate, kW temperature difference in pinch point, K efficiency, %
Subscripts a air cr critical d drying
relevant systems (i.e. those based on ORC and IC Engine) is given in [6]. In that case, the economic effectiveness for systems with varying power outputs is made with account of Polish and German support schemes for conversion of energy from renewable energy sources. A sawmill integration with a pellet plant and a CHP plant (biomass waste combustion in dedicated steam power plant) is investigated in [7]. The results show that up to 18% of the biomass by-products of the sawmill can be saved in case of the integrated production process. The energy-economic analysis for biomass based CHP plants working according to various technologies: Stirling engine, ORC, steam engine, steam turbine and gas engine is presented in [8]. The analysis yields that, for Serbian conditions, the installation of CHP plants in small capacity sawmills (about 10,000 m3/year) is not justified economically. The forest biomass and other biomass waste can be also utilized in distributed hybrid energy conversion systems. A proposal of the hybrid biomass-solar power plant is presented in [9], with utilization of various biomass types (wood chips, urban wood waste) and parabolic trough collectors. A hybrid CHP plant with direct solar supply and biomass energy is discussed in [10]. Biomass is combusted in a fluidized bed boiler and solar energy is collected via a concentrated receiver, with thermal energy being converted into electricity by using Stirling engine. The thermo-economic analysis of a micro gas turbine supplied with externally fired natural gas and biomass is presented in [11]. 2. Description of the CHP plant systems fuelled with sawmill biomass In the present work, three variants of the CHP plant based on organic Rankine cycle and fuelled with sawmill waste have been analysed. The CHP plants are to produce electricity and to supply heat for drying processes. The variants of CHP plant systems result from the type of the working fluid used in the system: wet or dry [12]. Selected parameters of the working fluids chosen for the calculation are shown in Table 1, and the shapes of the saturation curves, determining the type of the fluid (dry, wet) are shown in Fig. 1.
el o th wf 1, 2, 2d,
electric heat carrier (thermal oil) thermal working fluid 2r, 2s, 3, 4, 4s, 4r 5, 6 characteristic points of cycle
Abbreviations (also used as subscripts) B boiler C condenser D drying chamber G generator HE heat exchanger ORC organic Rankine cycle P pump R internal regenerator T turbine
The boiler (B) with a capacity of Q_ B ¼ 250 kW, in which the combustion of biomass waste from sawmill occurs, is the source of energy for the CHP plant. The heat Q_ B generated by combustion is, via a heat carrier – thermal oil, transferred in the heat exchanger (HE) to the working fluid in the power plant:
_ o cp;o ðT o1 T o2 Þ ¼ m _ wf ðh1 h4 Þ Q_ B ¼ m
ð1Þ
It was assumed that the thermal oil temperature at the boiler outlet is To1 = 300 °C, and at the boiler return tap it is To2 = 240 °C. Thermal oil supplied from the boiler to the heat exchanger HE causes: preheating (process 4-5), evaporation (process 5-6) and superheating (process 6-1) of the working fluid. Next, the vapour of the working fluid is directed to the turbine (T) where vapour expansion (process 1-2) follows. The expanded working fluid vapour from the turbine is directed to the condenser (C) that is cooled by air. The heat flux removed from the condenser
_ wf ðh2 h3 Þ Q_ C ¼ m
ð2Þ
Table 1 Selected properties of the working fluids adopted in the calculations. Working fluid
Critical temperature (°C)
Pressure (MPa @ T = 25 °C)
Type of fluid
Methylcyclohexane MDM octamethyltrisiloxane Methanol Water
299.05 290.94
0.006177 0.000498
Dry Dry
239.45 373.95
0.016981 0.003170
Wet Wet
2.1. CHP plant with wet working fluid – variant A The thermodynamic conversion cycle for the CHP plant with wet working fluids (water or methanol) is shown in Fig. 2, while the scheme of the plant system is given in Fig. 3.
Fig. 1. Shapes of the saturation curves of the selected working fluids.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx
Fig. 2. Thermodynamic processes in the Clausius–Rankine cycle for wet working fluid.
3
Fig. 4. Thermodynamic processes in the Clausius–Rankine cycle with internal regeneration, for dry working fluid.
Fig. 5. Scheme of the power plant with internal regeneration, for dry working fluid. Fig. 3. Scheme of the power plant with wet working fluid.
is used to heat the chamber (D), in which wood drying is performed, thereby the temperature of the condensing process T3 must be adjusted to the temperature required in the process of drying the wood Td. The heat flux Q_ D of the drying process was determined according to the relation
Q_ D ¼ Q_ C
ð3Þ
_ a can be whereas according to (4), the cooling flow rate m determined.
_ a cp;a ðT a T d Þ Q_ D ¼ m
ð4Þ
The maximum temperature value of air supplied to the drying chamber may be determined by the following relation:
T d;max ¼ T 2 DT
ð5Þ
According to [13], wood drying temperature depends mainly on the type of wood and on the moisture content, and this value is typically in the range of 30–80 °C, but high temperature drying technologies (Td > 100 °C) are also used. For this reason, in the CHP plant system under consideration varying condensation temperatures of the working fluids were adopted, i.e. T3 = 50; 80 and 110 °C, which according to Eq. (5) allows to reach the air temperature supplied the dryer Td = 45, 75 and 105 °C (assuming that DT = 5 °K). 2.2. CHP plant with dry working fluid – variant with internal regeneration (variant B) In the case of the power plant system with application of the working fluids from the so called ‘‘dry’’ fluids group it is possible to use the internal heat regeneration [14] in the power plant system. In such situation, the working fluid vapour from the turbine exit first passes through a heat exchanger called the regenerator (process 2-2r), and only then it is directed to the condenser. The liquid of the working fluid from the condenser is directed to the circulation pump (process 3-4), and then it is heated with the regeneration heat (process (4-4r). Thermodynamic processes of the cycle for the power plant with the dry fluid (with indication
of the regeneration heat qR) are shown in Fig. 4, while the power plant scheme for this option is shown in Fig. 5. Regeneration heat flux can be calculated from the formula
_ wf ðh2 h2r Þ Q_ R ¼ m
ð6Þ
while the heat flux removed from the condenser from
_ wf ðh2r h3 Þ Q_ C ¼ m
ð7Þ
The heat flux Q_ D of the drying process for this option can be determined from Eq. (3) and the maximum temperature value of air supplied to the drying chamber determines the relationship:
T d;max ¼ T 2r DT
ð8Þ
The values of the condensing temperature and of the temperature of air directed to the drying chamber are the same as in the case with wet working fluid. 2.3. CHP plant with dry working fluid – variant with external regeneration (variant C) Application of the dry working fluid in the vapour power plants is associated with the fact that the vapour expansion process takes place in the superheated region and the vapour temperature at the turbine outlet usually by far exceeds the condensation temperature. This property is used for the internal regeneration, but there is also the possibility to apply external regeneration – the variant shown in Figs. 6 and 7.
Fig. 6. Thermodynamic processes in the power plant with external regeneration, for dry working fluid.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx
In this variant the condensation temperature of the working fluid T3 is 25 °C. 3. Indicators for evaluation of power plant variants and assumptions
Fig. 7. Scheme of the power plant with external regeneration, for dry working fluid.
Pel ¼ PT PP
Table 2 Summary of the assumptions made in the calculations.
Q_ B (kW) To1 (°C) To2 (°C) T1 (°C) T3 (°C)
gT gP
The main indicators for evaluation of different options of the CHP plants are assumed to be: power Nel and efficiency of power plant gth, as well as the heat flux for supplying the dryers Q_ D and the maximum temperature of the drying air Td,max. Electric power for all the variants was determined by the relations
ð12Þ
where
Variants A and B
Variant C
250
250
300 240 285 50, 80, 100 0.85 0.75
300 240 285 25 0.85 0.75
_ wf ðh1 h2 ÞgT PT ¼ m
ð13Þ
_ wf ðh4 h3 Þ=gP PP ¼ m
ð14Þ
Enthalpy values of the relevant working fluids for each point of the cycle were determined using the REFPROP 9.1 [15]. Efficiency of power plants was determined according to
P
The purpose to apply the external regeneration originates from the wish to obtain a higher temperature of air supplied to the drying chamber, without having to raise the condensation temperature of the working fluid. In this variant the heat flux supplied to the drying chamber can be determined from the relationship:
_ wf ðh2 h2d Þ Q_ D ¼ m
ð9Þ
while the heat flux removed from the condenser is obtained from the relation
_ wf ðh2d h3 Þ Q_ C ¼ m
gth ¼ _ el : QB
ð15Þ
Relationships that determine heat fluxes to supply the dryer Q_ D for individual variants of calculations and maximum air drying temperatures Td,max were presented in individual subsections describing the variants of the power plants. The values assumed in calculations are presented in Table 2. In all variants of the calculations, it was assumed that the process of vapour expansion in the turbine takes place entirely in the superheated region, and starts or ends at the saturation line, x = 1.
ð10Þ
The maximum value of the air temperature supplied to the drying chamber determines the relationship:
T d;max ¼ T 2 DT
ð11Þ
4. Calculation results The calculations were performed for the three variants of the CHP plants. For variant A water or methanol were applied and
Table 3 The parameters of water and methanol at various points of the cycle – variant A. T3 °C
T1 °C
h1 kJ/kg
T2 °C
h2 kJ/kg
h3 kJ/kg
T4 °C
Water 50 80 110
285 285 285
3043.8 3038.3 3027.7
50 80 110
2591.3 2643.0 2691.1
209.3 335.0 461.4
50.02 80.03 110.04
Methanol 50 80 110
285 285 285
1485.3 1447.4 1397.7
50 80 110
1087.8 1114.2 1134.0
40.09 44.97 138.39
50.4 80.9 111.6
h4 kJ/kg
T5 °C
h5 kJ/kg
T6 °C
h6 kJ/kg
209.5 335.3 462.0
105.1 136.3 165.4
440.5 573.4 699.1
105.1 136.3 165.4
2683.5 2728.6 2763.2
37.2 50.4 1467.0
171.5 202.2 224.7
367.2 509.0 641.6
171.5 202.2 224.7
1132.0 1117.7 1059.5
Table 4 Calculation results for the power plants – variant A. T3
_o m
_ wf m
Pel
gth
°C
kg/s
kg/s
kW
%
Q_ D kW
°C
Water
50 80 110
1.07 1.07 1.07
0.088 0.920 0.097
33.9 31.0 27.7
13.6 12.4 11.09
210.1 213.5 217.3
45 75 105
Methanol
50 80 110
1.07 1.07 1.07
0.16 0.18 0.20
54.2 48.1 40.4
21.7 19.2 16.2
185.2 191.3 198.9
45 75 105
Td,max
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx Table 5 MDM and methylcyclohexane working fluid parameters for each point of the cycle – variant B. T3 °C
T1 °C
h1 kJ/kg
T2 °C
h2 kJ/kg
T2r °C
MDM 50 80 110
285 285 285
360.95 360.95 360.95
207.0 219.9 230.5
255.20 279.51 299.34
55 85 115
164.13 183.72 200.16
443.79 484.16 518.24
55 85 115
Methylcyclohexane 50 285 631.37 80 285 631.37 110 285 631.37
h2r kJ/kg
h3 kJ/kg
T4 °C
h4 kJ/kg
T4r °C
h4r kJ/kg
T5 °C
h5 kJ/kg
0.95 44.25 91.52
203.11 146.29 87.40
50.4 80.4 110.5
201.48 144.6 85.662
177.9 194.3 208.4
54.67 90.66 122.15
285 285 285
315.95 315.95 315.95
245.88 292.66 342.69
108.40 46.01 20.86
50.7 80.8 110.9
104.49 42.00 24.92
139.8 162.3 181.8
93.42 149.50 200.47
285 285 285
525.41 525.41 525.41
Table 6 Calculations results for the CHP plants – variant B. T3
_o m
_ wf m
Pel
gth
°C
kg/s
kg/s
kW
%
Q_ R kW
Q_ D kW
°C
MDM
50 80 110
1.07 1.07 1.07
0.82 0.92 1.05
69.6 59.6 49.6
27.88 23.8 19.8
209.1 217.6 217.7
165.0 176.2 187.3
45 75 105
Methylcyclohexane
50 80 110
1.07 1.07 1.07
0.46 0.52 0.58
69.3 59.4 49.5
27.7 23.7 19.8
92.0 99.4 101.9
164.6 175.7 186.7
45 75 105
Td,max
Table 7 The relevant temperature and enthalpy of the working fluids: MDM and methylcyclohexane at different points of the cycle – variant C.
MDM Methylcyclohexane
T1 °C
h1 kJ/kg
T2 °C
h2 kJ/kg
T °C
h3 kJ/kg
T4 °C
h4 kJ/kg
T5 °C
h5 kJ/kg
285 285
361.0 631.4
194.3 144.4
231.5 404.3
25 25
249.1 157.1
25.3 25.7
247.5 153.3
285 285
316.0 525.4
for variants B and C the calculations were made by using methylcyclohexane or MDM fluids. Table 3 shows the values of temperature and enthalpy appropriate for each point in the steam (vapour) power plant cycles with, respectively, water and methanol as working fluids, for three different condensing temperatures, while the calculation results for this variant are given in Table 4. Values of enthalpy and temperature of MDM and methylcyclohexane in the characteristic points of the cycle with internal regeneration are presented in Table 5, and the calculation results for the respective CHP plants are given in Table 6. Since the use of dry fluids methylcyclohexane and MDM enable to apply external regeneration (variant C), Tables 7 and 8 show the values of temperature and enthalpy at characteristic points of the cycle for these working fluids and the results of calculations for CHP plants in variant C.
Table 8 Calculation results of the CHP plants with MDM and methylcyclohexane – variant C.
MDM Methylcyclohexane
_o m
_ wf m
P el
gth
kg/s
kg/s
kW
%
Q_ C kW
Q_ D kW
°C
1.07 1.07
0.41 0.32
43.5 58.2
17.4 23.3
84.3 114.64
113.2 64.24
189.3 139.4
T d;max
80 methylcyclohexane MDM methanol water
70 60
Pel kW 50 40 30
5. Discussion of results 20
The electric power output of the prospective CHP plant is the basic parameter for economic justification for the CHP plant investment in a wood processing plant. Value of that power plant output depends also on the assumed condensation temperature. Fig. 8 shows the impact of the type of the fluid and of the condensing temperature (having a direct impact on the temperature of the air used for drying) on the power plant output. The analysis of the data shown in Fig. 8 indicates that the use of dry organic fluids (variant B), i.e. the use of the ORC power plant, allows to obtain much higher electric power values than those for wet fluids (variant A). Since the heat flux supplied from the
50
60
70
80
90
100
110
T3°C Fig. 8. Influence of the condensing temperature T3 and the type of working fluid on electric power Pel of the power plant.
boiler to each variant of the power plant is the same and amounts 250 kW then a higher electric power output is accompanied by a lower heat flux Q_ D for drying. Also, the air temperature at the inlet of the drying chamber is another important parameter for the drying process. The combination of these three parameters which characterize the CHP plant is shown in Fig. 9.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx
The analysis of the data indicates that:
250 Pel
200
TD,max
QD
150 100
MDM - variant C
MDM-variant B
methylcyclohexanevariant C
methylcyclohexane variant B
methanol-variant A
0
water- variant A
50
Fig. 9. Influence of the working fluid and the type of the CHP plant on the electric power Pel [kW], the maximum air temperature T d;max [°C] and the heat flux directed to the dryer exchanger Q_ D [kW].
It is easy to note from diagram shown in Fig. 9 that the values of the electric power output, drying heat flux and drying air temperature depend strongly on both the power plant variant and applied cycle working fluid. It can be stated that a wide range of chemicals that can be used as working fluids in CHP plants allow the design of the CHP plant system to meet the requirements of the user. A good example proving this claim is a system with MDM working fluid. The use of the power plant with the internal regeneration (variant B) allows to obtain the electric power of 49.6 kWel, drying heat flux of 187 kWth and drying air temperature at 105 °C, while the use of the system with the external regeneration (variant C) allows to receive the electric power of 43.5 kWel, drying heat flux of 113 kWth and drying air temperature at 189 °C. When a low-temperature drying process is used at the wood processing plant then it is possible to select such operating parameters as to obtain the electric power of 69.6 kWel, drying heat flux of 165 kW and drying air temperature at 45 °C. It results from the analysis that, in case of the CHP plants dedicated for the wood processing plants, application of dry working fluids appears as more advantageous (variants B and C). Moreover, in case of application of such fluids in the CHP systems designed according to variant C a higher electric power output is achievable at more flexible choice of the drying air temperature. Such flexibility is important in view of the varying drying requirements that depend on initial wood size, on varying moisture contents and on ambient temperature. 6. Conclusions In the paper, three variants of the CHP systems that use steam or vapour power plant technology are presented in applications for wood processing plants. The performance of each power plant variant depends mainly on the type of fluid working in the vapour cycle (water, methanol, MDM and methylcyclohexane). The heat from the CHP system is intended for wood drying processes. The performance of the CHP plants is analyzed on the basis of three parameters, which mainly characterize the CHP plant, i.e. electric power output Pel, heat power output Q_ D and temperature of air used for drying purposes Td,max.
– systems with wet working fluid (variant A – water or methanol) are advisable for the wood processing plants at which the relatively high heat flux is desired together with low value of temperature of drying air; – the use of dry organic fluids with internal regeneration (variant B), allows to obtain much higher electric power values than those for wet fluids (water, methanol – variant A); – application of dry working fluid in system without internal regeneration (variant C) allows to obtain high temperature of drying air. – In summary, it can be concluded that the proper selection of the working fluid of the prospective CHP system allows the latter to match the desirable operating parameters of the biomass ORC power plant.
Acknowledgements The work presented in the paper was financed by the National Centre for Research and Development (NCBiR), Poland, in frame of the Project No. PBS1/A4/7/2012. References [1] Nowak W, Borsukiewicz-Gozdur A, Klonowicz P, Stachel A, Hanausek P, Klonowicz W. Initial experimental investigation of prototype small scale ORC power plant supplied with water at 100 °C. Prz Geologiczny 2010;7:622–5. [2] Borsukiewicz-Gozdur A. Experimental investigation of R227ea applied as working fluid in the ORC power plant with hermetic turbogenerator. Appl Therm Eng 2013;56:126–33. [3] Anderson JO, Westerlund L. Improved energy efficiency in sawmill drying system. Appl Energy 2014;113:891–901. [4] Renstrom R. The potential of improvements in the energy systems of sawmills when coupled dryers are used for drying of wood fuels and wood products. Biomass Bioenergy 2006;30:452–60. [5] Rentizelas A, Karellas S, Kakaras E, Tatsiopoulos I. Comparative technoeconomic analysis of ORC and gasification for bioenergy applications. Energy Convers Manage 2009;50:674–81. [6] Tanczuk M, Ulbrich R. Implementation of a biomass-fired co-generation plant supplied with an ORC (Organic Rankine Cycle) as a heat source for small scale heat distribution system e A comparative analysis under Polish and German conditions. Energy 2013;62:132–41. [7] Anderson JO, Toffolo A. Improving energy efficiency of sawmill industrial sites by integration with pellet and CHP plants. Appl Energy 2013;111:791–800. [8] Danon G, Furtula M, Mandi M. Possibilities of implementation of CHP (combined heat and power) in the wood industry in Serbia. Energy 2012;48:169–76. [9] Peterseim JH, Tadros A, Hellwig U, White S. Increasing the efficiency of parabolic trough plants using thermal oil through external superheating with biomass. Energy Convers Manage 2014;77:784–93. [10] Angrisani G, Bizon K, Chirone R, Continillo G, Fusco G, Lombardi S, et al. Development of a new concept solar-biomass cogeneration system. Energy Convers Manage 2013;75:552–60. [11] Pantaleo AM, Camporeale SM, Shah N. Thermo-economic assessment of externally fired micro-gas turbine fired by natural gas and biomass: applications in Italy. Energy Convers Manage 2013;75:202–13. [12] Badr O, O’Callaghan WP, Probert SD. Thermodynamic and thermophysical properties of organic working fluids for Rankine-cycle engine. Appl Energy 1985;19:1–40. [13] http://www.jwd.pl/suszenie,drewna/ [in Polish]. [14] Borsukiewicz-Gozdur A. Influence of the ORC power plant heat recuperation solutions on effectiveness of the supplied waste heat utilization. Arch Thermodyn 2010;4:111–24. [15] Lemmon EW, Huber ML, McLinden MO. Refprop 9.1, NIST standard reference database 23. Version 9.1, USA; 2013.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman
ORC power plant for electricity production from forest and agriculture biomass A. Borsukiewicz-Gozdur ⇑, S. Wis´niewski, S. Mocarski, M. Ban´kowski ORC Power Plants Research and Development Centre, West Pomeranian University of Technology, al. Piastów 17, Szczecin, Poland
a r t i c l e
i n f o
Article history: Available online xxxx Keywords: ORC CHP Wood biomass Working fluid Cogeneration
a b s t r a c t The paper presents the calculation results for three variants of CHP plant fuelled by sawmill biomass. The plant shall produce electricity and heat for a drying chamber. An analysis of the system efficiency for four different working fluids was conducted: octamethyltrisiloxane, methylcyclohexane, methanol and water. The highest electric power was obtained for the system with internal regeneration and methylcyclohexane applied as the ‘‘dry’’ working fluid, the highest temperature to supply the drying chamber was obtained for the system with external regeneration and octamethyltrisiloxane applied as the working fluid. The results of the analysis indicate that, by proper choice of the working fluid and of the regeneration variant (internal or external), it is possible to ‘‘adjust’’ the work of the system to the needs and expectations of the plant investor (user). Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction For many years, the West Pomeranian University of Technology in Szczecin, Poland, has conducted research aimed at developing technologies for distributed generation of electricity by using the ORC technology, with a particular focus having been placed on utilization of geothermal energy [1] and low temperature waste heat [2]. This paper presents proposals of the ORC power plant solutions to be applied for utilization of sawmill waste and other types of wood waste. Currently, in Poland, plants of this kind utilize sawmill waste for heating and drying only. On the other hand, as shown in [3], both generation and utilization of the respective source heat can be optimized. Effectiveness of the wood dryers performance is there analyzed for various drying technologies (such with air heat exchangers or with standard or absorption heat pumps), and electricity and heat consumption are for those processes presented and referenced to the cumulative sawmill production in Sweden. Sawmill waste, as well as other types of biomass (straw, corn stalks) can be converted into some intermediate fuel, e.g. in the form of pellets, if the plant possesses a suitable production line and marketing ability. Examples of respective energy conversion systems are presented in [4]. However, the trends in the energy developments are to produce electricity ‘‘on site’’, that is without a need to transport biomass waste to power plants, which also fits ⇑ Corresponding author. E-mail address: [email protected] (A. Borsukiewicz-Gozdur).
in perfectly with the idea of distributed generation. In addition, the combined production of electricity and heat (i.e. not only of heat as it is usually done now) is one of the best ways to increase the efficiency of energy conversion processes. At present, there are principally two technologies of the distributed combined heat and power generation that are considered in respect to the biomass utilization: – internal combustion piston engine (IC Engine) fuelled with syngas generated in a biomass gasification system, – turbine based CHP plant with either steam turbine or vapour turbine working with organic fluids (ORC plant), with energy input from appropriate biomass boilers. Such plant can be also driven with heat from the biogas fired boilers. Other CHP technologies, such as those based on fuel cells, gas turbines, Stirling engines and others are still in the developing phase and are expected to be commercially available in the next few years. The techno-economic analysis of the ORC system with input from a gasification system is presented in [5] for the case of bioenergy applications. It results from that analysis that, in respect to the proportion of generation of electricity versus heat, the high temperature system incorporating biomass gasification and biogas fired piston engine appears as more advantageous. On the other hand, biomass combustion and the resulting heat conversion by means of the ORC system is technologically more matured and burdened with less risk, and is applied more frequently. A comparative analysis of the
http://dx.doi.org/10.1016/j.enconman.2014.04.098 0196-8904/Ó 2014 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx
Nomenclature cp h _ m p P S T Td,max Q_ DT
g
specific heat at constant pressure, kJ/kg K specific enthalpy, kJ/kg mass flow rate, kg/s pressure, MPa power, kW entropy, kJ/kg K temperature, °C maximum temperature value of air supplied to the drying chamber, °C heat flow rate, kW temperature difference in pinch point, K efficiency, %
Subscripts a air cr critical d drying
relevant systems (i.e. those based on ORC and IC Engine) is given in [6]. In that case, the economic effectiveness for systems with varying power outputs is made with account of Polish and German support schemes for conversion of energy from renewable energy sources. A sawmill integration with a pellet plant and a CHP plant (biomass waste combustion in dedicated steam power plant) is investigated in [7]. The results show that up to 18% of the biomass by-products of the sawmill can be saved in case of the integrated production process. The energy-economic analysis for biomass based CHP plants working according to various technologies: Stirling engine, ORC, steam engine, steam turbine and gas engine is presented in [8]. The analysis yields that, for Serbian conditions, the installation of CHP plants in small capacity sawmills (about 10,000 m3/year) is not justified economically. The forest biomass and other biomass waste can be also utilized in distributed hybrid energy conversion systems. A proposal of the hybrid biomass-solar power plant is presented in [9], with utilization of various biomass types (wood chips, urban wood waste) and parabolic trough collectors. A hybrid CHP plant with direct solar supply and biomass energy is discussed in [10]. Biomass is combusted in a fluidized bed boiler and solar energy is collected via a concentrated receiver, with thermal energy being converted into electricity by using Stirling engine. The thermo-economic analysis of a micro gas turbine supplied with externally fired natural gas and biomass is presented in [11]. 2. Description of the CHP plant systems fuelled with sawmill biomass In the present work, three variants of the CHP plant based on organic Rankine cycle and fuelled with sawmill waste have been analysed. The CHP plants are to produce electricity and to supply heat for drying processes. The variants of CHP plant systems result from the type of the working fluid used in the system: wet or dry [12]. Selected parameters of the working fluids chosen for the calculation are shown in Table 1, and the shapes of the saturation curves, determining the type of the fluid (dry, wet) are shown in Fig. 1.
el o th wf 1, 2, 2d,
electric heat carrier (thermal oil) thermal working fluid 2r, 2s, 3, 4, 4s, 4r 5, 6 characteristic points of cycle
Abbreviations (also used as subscripts) B boiler C condenser D drying chamber G generator HE heat exchanger ORC organic Rankine cycle P pump R internal regenerator T turbine
The boiler (B) with a capacity of Q_ B ¼ 250 kW, in which the combustion of biomass waste from sawmill occurs, is the source of energy for the CHP plant. The heat Q_ B generated by combustion is, via a heat carrier – thermal oil, transferred in the heat exchanger (HE) to the working fluid in the power plant:
_ o cp;o ðT o1 T o2 Þ ¼ m _ wf ðh1 h4 Þ Q_ B ¼ m
ð1Þ
It was assumed that the thermal oil temperature at the boiler outlet is To1 = 300 °C, and at the boiler return tap it is To2 = 240 °C. Thermal oil supplied from the boiler to the heat exchanger HE causes: preheating (process 4-5), evaporation (process 5-6) and superheating (process 6-1) of the working fluid. Next, the vapour of the working fluid is directed to the turbine (T) where vapour expansion (process 1-2) follows. The expanded working fluid vapour from the turbine is directed to the condenser (C) that is cooled by air. The heat flux removed from the condenser
_ wf ðh2 h3 Þ Q_ C ¼ m
ð2Þ
Table 1 Selected properties of the working fluids adopted in the calculations. Working fluid
Critical temperature (°C)
Pressure (MPa @ T = 25 °C)
Type of fluid
Methylcyclohexane MDM octamethyltrisiloxane Methanol Water
299.05 290.94
0.006177 0.000498
Dry Dry
239.45 373.95
0.016981 0.003170
Wet Wet
2.1. CHP plant with wet working fluid – variant A The thermodynamic conversion cycle for the CHP plant with wet working fluids (water or methanol) is shown in Fig. 2, while the scheme of the plant system is given in Fig. 3.
Fig. 1. Shapes of the saturation curves of the selected working fluids.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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Fig. 2. Thermodynamic processes in the Clausius–Rankine cycle for wet working fluid.
3
Fig. 4. Thermodynamic processes in the Clausius–Rankine cycle with internal regeneration, for dry working fluid.
Fig. 5. Scheme of the power plant with internal regeneration, for dry working fluid. Fig. 3. Scheme of the power plant with wet working fluid.
is used to heat the chamber (D), in which wood drying is performed, thereby the temperature of the condensing process T3 must be adjusted to the temperature required in the process of drying the wood Td. The heat flux Q_ D of the drying process was determined according to the relation
Q_ D ¼ Q_ C
ð3Þ
_ a can be whereas according to (4), the cooling flow rate m determined.
_ a cp;a ðT a T d Þ Q_ D ¼ m
ð4Þ
The maximum temperature value of air supplied to the drying chamber may be determined by the following relation:
T d;max ¼ T 2 DT
ð5Þ
According to [13], wood drying temperature depends mainly on the type of wood and on the moisture content, and this value is typically in the range of 30–80 °C, but high temperature drying technologies (Td > 100 °C) are also used. For this reason, in the CHP plant system under consideration varying condensation temperatures of the working fluids were adopted, i.e. T3 = 50; 80 and 110 °C, which according to Eq. (5) allows to reach the air temperature supplied the dryer Td = 45, 75 and 105 °C (assuming that DT = 5 °K). 2.2. CHP plant with dry working fluid – variant with internal regeneration (variant B) In the case of the power plant system with application of the working fluids from the so called ‘‘dry’’ fluids group it is possible to use the internal heat regeneration [14] in the power plant system. In such situation, the working fluid vapour from the turbine exit first passes through a heat exchanger called the regenerator (process 2-2r), and only then it is directed to the condenser. The liquid of the working fluid from the condenser is directed to the circulation pump (process 3-4), and then it is heated with the regeneration heat (process (4-4r). Thermodynamic processes of the cycle for the power plant with the dry fluid (with indication
of the regeneration heat qR) are shown in Fig. 4, while the power plant scheme for this option is shown in Fig. 5. Regeneration heat flux can be calculated from the formula
_ wf ðh2 h2r Þ Q_ R ¼ m
ð6Þ
while the heat flux removed from the condenser from
_ wf ðh2r h3 Þ Q_ C ¼ m
ð7Þ
The heat flux Q_ D of the drying process for this option can be determined from Eq. (3) and the maximum temperature value of air supplied to the drying chamber determines the relationship:
T d;max ¼ T 2r DT
ð8Þ
The values of the condensing temperature and of the temperature of air directed to the drying chamber are the same as in the case with wet working fluid. 2.3. CHP plant with dry working fluid – variant with external regeneration (variant C) Application of the dry working fluid in the vapour power plants is associated with the fact that the vapour expansion process takes place in the superheated region and the vapour temperature at the turbine outlet usually by far exceeds the condensation temperature. This property is used for the internal regeneration, but there is also the possibility to apply external regeneration – the variant shown in Figs. 6 and 7.
Fig. 6. Thermodynamic processes in the power plant with external regeneration, for dry working fluid.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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In this variant the condensation temperature of the working fluid T3 is 25 °C. 3. Indicators for evaluation of power plant variants and assumptions
Fig. 7. Scheme of the power plant with external regeneration, for dry working fluid.
Pel ¼ PT PP
Table 2 Summary of the assumptions made in the calculations.
Q_ B (kW) To1 (°C) To2 (°C) T1 (°C) T3 (°C)
gT gP
The main indicators for evaluation of different options of the CHP plants are assumed to be: power Nel and efficiency of power plant gth, as well as the heat flux for supplying the dryers Q_ D and the maximum temperature of the drying air Td,max. Electric power for all the variants was determined by the relations
ð12Þ
where
Variants A and B
Variant C
250
250
300 240 285 50, 80, 100 0.85 0.75
300 240 285 25 0.85 0.75
_ wf ðh1 h2 ÞgT PT ¼ m
ð13Þ
_ wf ðh4 h3 Þ=gP PP ¼ m
ð14Þ
Enthalpy values of the relevant working fluids for each point of the cycle were determined using the REFPROP 9.1 [15]. Efficiency of power plants was determined according to
P
The purpose to apply the external regeneration originates from the wish to obtain a higher temperature of air supplied to the drying chamber, without having to raise the condensation temperature of the working fluid. In this variant the heat flux supplied to the drying chamber can be determined from the relationship:
_ wf ðh2 h2d Þ Q_ D ¼ m
ð9Þ
while the heat flux removed from the condenser is obtained from the relation
_ wf ðh2d h3 Þ Q_ C ¼ m
gth ¼ _ el : QB
ð15Þ
Relationships that determine heat fluxes to supply the dryer Q_ D for individual variants of calculations and maximum air drying temperatures Td,max were presented in individual subsections describing the variants of the power plants. The values assumed in calculations are presented in Table 2. In all variants of the calculations, it was assumed that the process of vapour expansion in the turbine takes place entirely in the superheated region, and starts or ends at the saturation line, x = 1.
ð10Þ
The maximum value of the air temperature supplied to the drying chamber determines the relationship:
T d;max ¼ T 2 DT
ð11Þ
4. Calculation results The calculations were performed for the three variants of the CHP plants. For variant A water or methanol were applied and
Table 3 The parameters of water and methanol at various points of the cycle – variant A. T3 °C
T1 °C
h1 kJ/kg
T2 °C
h2 kJ/kg
h3 kJ/kg
T4 °C
Water 50 80 110
285 285 285
3043.8 3038.3 3027.7
50 80 110
2591.3 2643.0 2691.1
209.3 335.0 461.4
50.02 80.03 110.04
Methanol 50 80 110
285 285 285
1485.3 1447.4 1397.7
50 80 110
1087.8 1114.2 1134.0
40.09 44.97 138.39
50.4 80.9 111.6
h4 kJ/kg
T5 °C
h5 kJ/kg
T6 °C
h6 kJ/kg
209.5 335.3 462.0
105.1 136.3 165.4
440.5 573.4 699.1
105.1 136.3 165.4
2683.5 2728.6 2763.2
37.2 50.4 1467.0
171.5 202.2 224.7
367.2 509.0 641.6
171.5 202.2 224.7
1132.0 1117.7 1059.5
Table 4 Calculation results for the power plants – variant A. T3
_o m
_ wf m
Pel
gth
°C
kg/s
kg/s
kW
%
Q_ D kW
°C
Water
50 80 110
1.07 1.07 1.07
0.088 0.920 0.097
33.9 31.0 27.7
13.6 12.4 11.09
210.1 213.5 217.3
45 75 105
Methanol
50 80 110
1.07 1.07 1.07
0.16 0.18 0.20
54.2 48.1 40.4
21.7 19.2 16.2
185.2 191.3 198.9
45 75 105
Td,max
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx Table 5 MDM and methylcyclohexane working fluid parameters for each point of the cycle – variant B. T3 °C
T1 °C
h1 kJ/kg
T2 °C
h2 kJ/kg
T2r °C
MDM 50 80 110
285 285 285
360.95 360.95 360.95
207.0 219.9 230.5
255.20 279.51 299.34
55 85 115
164.13 183.72 200.16
443.79 484.16 518.24
55 85 115
Methylcyclohexane 50 285 631.37 80 285 631.37 110 285 631.37
h2r kJ/kg
h3 kJ/kg
T4 °C
h4 kJ/kg
T4r °C
h4r kJ/kg
T5 °C
h5 kJ/kg
0.95 44.25 91.52
203.11 146.29 87.40
50.4 80.4 110.5
201.48 144.6 85.662
177.9 194.3 208.4
54.67 90.66 122.15
285 285 285
315.95 315.95 315.95
245.88 292.66 342.69
108.40 46.01 20.86
50.7 80.8 110.9
104.49 42.00 24.92
139.8 162.3 181.8
93.42 149.50 200.47
285 285 285
525.41 525.41 525.41
Table 6 Calculations results for the CHP plants – variant B. T3
_o m
_ wf m
Pel
gth
°C
kg/s
kg/s
kW
%
Q_ R kW
Q_ D kW
°C
MDM
50 80 110
1.07 1.07 1.07
0.82 0.92 1.05
69.6 59.6 49.6
27.88 23.8 19.8
209.1 217.6 217.7
165.0 176.2 187.3
45 75 105
Methylcyclohexane
50 80 110
1.07 1.07 1.07
0.46 0.52 0.58
69.3 59.4 49.5
27.7 23.7 19.8
92.0 99.4 101.9
164.6 175.7 186.7
45 75 105
Td,max
Table 7 The relevant temperature and enthalpy of the working fluids: MDM and methylcyclohexane at different points of the cycle – variant C.
MDM Methylcyclohexane
T1 °C
h1 kJ/kg
T2 °C
h2 kJ/kg
T °C
h3 kJ/kg
T4 °C
h4 kJ/kg
T5 °C
h5 kJ/kg
285 285
361.0 631.4
194.3 144.4
231.5 404.3
25 25
249.1 157.1
25.3 25.7
247.5 153.3
285 285
316.0 525.4
for variants B and C the calculations were made by using methylcyclohexane or MDM fluids. Table 3 shows the values of temperature and enthalpy appropriate for each point in the steam (vapour) power plant cycles with, respectively, water and methanol as working fluids, for three different condensing temperatures, while the calculation results for this variant are given in Table 4. Values of enthalpy and temperature of MDM and methylcyclohexane in the characteristic points of the cycle with internal regeneration are presented in Table 5, and the calculation results for the respective CHP plants are given in Table 6. Since the use of dry fluids methylcyclohexane and MDM enable to apply external regeneration (variant C), Tables 7 and 8 show the values of temperature and enthalpy at characteristic points of the cycle for these working fluids and the results of calculations for CHP plants in variant C.
Table 8 Calculation results of the CHP plants with MDM and methylcyclohexane – variant C.
MDM Methylcyclohexane
_o m
_ wf m
P el
gth
kg/s
kg/s
kW
%
Q_ C kW
Q_ D kW
°C
1.07 1.07
0.41 0.32
43.5 58.2
17.4 23.3
84.3 114.64
113.2 64.24
189.3 139.4
T d;max
80 methylcyclohexane MDM methanol water
70 60
Pel kW 50 40 30
5. Discussion of results 20
The electric power output of the prospective CHP plant is the basic parameter for economic justification for the CHP plant investment in a wood processing plant. Value of that power plant output depends also on the assumed condensation temperature. Fig. 8 shows the impact of the type of the fluid and of the condensing temperature (having a direct impact on the temperature of the air used for drying) on the power plant output. The analysis of the data shown in Fig. 8 indicates that the use of dry organic fluids (variant B), i.e. the use of the ORC power plant, allows to obtain much higher electric power values than those for wet fluids (variant A). Since the heat flux supplied from the
50
60
70
80
90
100
110
T3°C Fig. 8. Influence of the condensing temperature T3 and the type of working fluid on electric power Pel of the power plant.
boiler to each variant of the power plant is the same and amounts 250 kW then a higher electric power output is accompanied by a lower heat flux Q_ D for drying. Also, the air temperature at the inlet of the drying chamber is another important parameter for the drying process. The combination of these three parameters which characterize the CHP plant is shown in Fig. 9.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098
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A. Borsukiewicz-Gozdur et al. / Energy Conversion and Management xxx (2014) xxx–xxx
The analysis of the data indicates that:
250 Pel
200
TD,max
QD
150 100
MDM - variant C
MDM-variant B
methylcyclohexanevariant C
methylcyclohexane variant B
methanol-variant A
0
water- variant A
50
Fig. 9. Influence of the working fluid and the type of the CHP plant on the electric power Pel [kW], the maximum air temperature T d;max [°C] and the heat flux directed to the dryer exchanger Q_ D [kW].
It is easy to note from diagram shown in Fig. 9 that the values of the electric power output, drying heat flux and drying air temperature depend strongly on both the power plant variant and applied cycle working fluid. It can be stated that a wide range of chemicals that can be used as working fluids in CHP plants allow the design of the CHP plant system to meet the requirements of the user. A good example proving this claim is a system with MDM working fluid. The use of the power plant with the internal regeneration (variant B) allows to obtain the electric power of 49.6 kWel, drying heat flux of 187 kWth and drying air temperature at 105 °C, while the use of the system with the external regeneration (variant C) allows to receive the electric power of 43.5 kWel, drying heat flux of 113 kWth and drying air temperature at 189 °C. When a low-temperature drying process is used at the wood processing plant then it is possible to select such operating parameters as to obtain the electric power of 69.6 kWel, drying heat flux of 165 kW and drying air temperature at 45 °C. It results from the analysis that, in case of the CHP plants dedicated for the wood processing plants, application of dry working fluids appears as more advantageous (variants B and C). Moreover, in case of application of such fluids in the CHP systems designed according to variant C a higher electric power output is achievable at more flexible choice of the drying air temperature. Such flexibility is important in view of the varying drying requirements that depend on initial wood size, on varying moisture contents and on ambient temperature. 6. Conclusions In the paper, three variants of the CHP systems that use steam or vapour power plant technology are presented in applications for wood processing plants. The performance of each power plant variant depends mainly on the type of fluid working in the vapour cycle (water, methanol, MDM and methylcyclohexane). The heat from the CHP system is intended for wood drying processes. The performance of the CHP plants is analyzed on the basis of three parameters, which mainly characterize the CHP plant, i.e. electric power output Pel, heat power output Q_ D and temperature of air used for drying purposes Td,max.
– systems with wet working fluid (variant A – water or methanol) are advisable for the wood processing plants at which the relatively high heat flux is desired together with low value of temperature of drying air; – the use of dry organic fluids with internal regeneration (variant B), allows to obtain much higher electric power values than those for wet fluids (water, methanol – variant A); – application of dry working fluid in system without internal regeneration (variant C) allows to obtain high temperature of drying air. – In summary, it can be concluded that the proper selection of the working fluid of the prospective CHP system allows the latter to match the desirable operating parameters of the biomass ORC power plant.
Acknowledgements The work presented in the paper was financed by the National Centre for Research and Development (NCBiR), Poland, in frame of the Project No. PBS1/A4/7/2012. References [1] Nowak W, Borsukiewicz-Gozdur A, Klonowicz P, Stachel A, Hanausek P, Klonowicz W. Initial experimental investigation of prototype small scale ORC power plant supplied with water at 100 °C. Prz Geologiczny 2010;7:622–5. [2] Borsukiewicz-Gozdur A. Experimental investigation of R227ea applied as working fluid in the ORC power plant with hermetic turbogenerator. Appl Therm Eng 2013;56:126–33. [3] Anderson JO, Westerlund L. Improved energy efficiency in sawmill drying system. Appl Energy 2014;113:891–901. [4] Renstrom R. The potential of improvements in the energy systems of sawmills when coupled dryers are used for drying of wood fuels and wood products. Biomass Bioenergy 2006;30:452–60. [5] Rentizelas A, Karellas S, Kakaras E, Tatsiopoulos I. Comparative technoeconomic analysis of ORC and gasification for bioenergy applications. Energy Convers Manage 2009;50:674–81. [6] Tanczuk M, Ulbrich R. Implementation of a biomass-fired co-generation plant supplied with an ORC (Organic Rankine Cycle) as a heat source for small scale heat distribution system e A comparative analysis under Polish and German conditions. Energy 2013;62:132–41. [7] Anderson JO, Toffolo A. Improving energy efficiency of sawmill industrial sites by integration with pellet and CHP plants. Appl Energy 2013;111:791–800. [8] Danon G, Furtula M, Mandi M. Possibilities of implementation of CHP (combined heat and power) in the wood industry in Serbia. Energy 2012;48:169–76. [9] Peterseim JH, Tadros A, Hellwig U, White S. Increasing the efficiency of parabolic trough plants using thermal oil through external superheating with biomass. Energy Convers Manage 2014;77:784–93. [10] Angrisani G, Bizon K, Chirone R, Continillo G, Fusco G, Lombardi S, et al. Development of a new concept solar-biomass cogeneration system. Energy Convers Manage 2013;75:552–60. [11] Pantaleo AM, Camporeale SM, Shah N. Thermo-economic assessment of externally fired micro-gas turbine fired by natural gas and biomass: applications in Italy. Energy Convers Manage 2013;75:202–13. [12] Badr O, O’Callaghan WP, Probert SD. Thermodynamic and thermophysical properties of organic working fluids for Rankine-cycle engine. Appl Energy 1985;19:1–40. [13] http://www.jwd.pl/suszenie,drewna/ [in Polish]. [14] Borsukiewicz-Gozdur A. Influence of the ORC power plant heat recuperation solutions on effectiveness of the supplied waste heat utilization. Arch Thermodyn 2010;4:111–24. [15] Lemmon EW, Huber ML, McLinden MO. Refprop 9.1, NIST standard reference database 23. Version 9.1, USA; 2013.
Please cite this article in press as: Borsukiewicz-Gozdur A et al. ORC power plant for electricity production from forest and agriculture biomass. Energy Convers Manage (2014), http://dx.doi.org/10.1016/j.enconman.2014.04.098