Energy Issues for Industrial Development

Copyright © IFAC 12th Triennial World Congress, Sydney, Australia, 1993

ENERGY ISSUES FOR INDUSTRIAL DEVELOPMENT CH. Cho ConsultinK Engineer. 39 Sllranllc Street. Ooh/J.\· Ferry . NY IIJ522 . USA

Abstrac~. There aTC 11l.~n~ energy issul! s whidl arc criti cailo industriaillt;vc1opl1lcllt : rt.:souru; s managclllcnl allli planning. infraSITUf..:lUfC

to cstah.hsh ~n~r.g.y

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and l.:.o Jcs . .l!lIcrg y alhll:;tlion alllI pricing . Icchnolngy issues focusing

Oil

energ y cfti cienc y of c4uipmcIH,

production lal:llulcs. and protc ctH)JI 01 environlllent. In auditioll . cllt:rgy issues should al so e nco mpass c on se rva ti o n of Ih t: natural ~cso ur~cs.

manpower training . lIse of alternati ve fuel s, anll optimum all m.: atioIl anti util ization

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hyprodw.:t fuel s . For a grass rool

mdustrlal ~Ia.nt ~ )r rc.novation of exi sting ,plant s. the IrCl1l..l is to ilH;IUlk a rcal time co mputer systcm for 1l1onilOring anLl l:ontrol /optll1l1zatlOn 01 cncrgy systcms as an IIHc!!ral part \If plant wiLlt.: lllallllf~ll:turing strate gy to optimilC anLl rt.: L1ucc tht.: proLlw.:tioll l:osts . Key Words . Ent.:rgy polil:ics ; t.: 11I..: rgy systcm s; Illonito ri ng. U lIlt w l anLl llptimi zal inn; proLlut:ti oll costs; encrgy cflit: icllcy

It encourages use of alternati ve fuel s. e .g .. coal. in stead of natural gas and oil in new hoiiers, - gas turhine units, comhustion engines and some comhined cycle units . DOE (Department of Energy) is rC4uired to establish rules defining a "major fuel hurning installati o n. " to devise a cost measure f(lr determining economic hardship , to set conditions for exempting cogeneration projects.

I . INTRODUCTION Among the many energy issues which are essential to industrial development, government policies and programs. energy resources development and management , and effective utilization of energy and conservation and manpower training are some of the key elements that must he addressed . In order to maintain the health of the manufacturing and process industry, it is the responsihility of governmcnt. states , educational institutions and industry to work together in order to develop and implement a rational strategic energy policy and direction for the present and future growth of economy .

2 .2 Energy Tax

It encourages and provides incentive to industry to switch to an alte rnative fuel or modifying e4uipme nt to reduce energy consumption hy offering energy tax credit in addition to the normal investment tax credit. Furthermore . the Department of Treasury is re4uired to estahlish performance and quality standards for e4uipment eligihle for additional tax credit. and to determine the amount of equipment that is eligihle .

Some of the major issues for industrial development are to : -

Develop energy resources Insure availability of energy supply Encourage and use of energy efficient e4uipment Develop and implement energy conservation and management technology Recovery and use of hy -product fuels utilization Develop and Implement intelligent huilding automation policy including energy conservation Research and develop alternative energy sources Manpower training

2.3 Puhlic Utilities Regulatory Policies

It re4uires state utility regul ators to consider adopting the rate making standards for electricity co nsumptio n: -

The capacity of industrial output of any nation depends largely on sustained energy supply at the reasonahle price. Therefore, it is important to have in place an infrastructure to coordinate. develop and implement policies that promote energy resources development, management and distrihution .

Time of day Seasonal demand Interruptihle rates Load management

For e xample . plams consuming most of their electrical energy during times of peak demand on the utility can expect a major increase in electrical costs . The Federal Energy Regulatory Commission is also authorized to promulgate rules to encourage development of industrial cogeneration and small power production projects: eliminate the threat of utility regulation, require utilities to provide necessary hackup power, granting eligibility for energy investment tax credit , and establishing guidelines for rates at which industrial gene rators can sell excess electricity back to the utility.

2. NATIONAL ENERGY POLICY Federal government has the power to mandate and enforce policies which are designed to serve the hest interest of a nation . For example, the National Energy Act(NEA) of 1978 in the United States was the first maj or legislative effort to establish a comprehensive national energy policy . This legislation contains five components which , I helieve, can he applicable to many nations :

2.4 National Gas Po licy

2.1 Powerplants and Industrial Fuel Use

693

develop and demonstrate the methodology through which universities may provide assistance to small manufacturing firms in identifying and analyzing energy conservation opportunities. The program consists of the following steps:

The major requirement this poli~ y addresses phase in decontrolled wellhead prices for natural gas. estahlishing curtailment policies during shortages . and increasing the priu: of natural gas for specific industrial users until it equals alternative fuel costs. 2.5 National Energy Conservation

- Analyzing energy consumption and costs for two year period - Conducting one day on -s ite energy audit - Analyzing each energy conservation opportunities for potential energy consumption and cost savings - Preparing report to the firm which contains specific recommendations of economically feasible energy conservat ion opportunities - Providing firm with appropriate financial analysis

Poli~y

This policy requires metals and metal produ~ts. paper. textile . and ruhher industries to estahlish target s for the in~reased use of energy saving recovered materials . The Se~retary of Department of Energy is to conduct a study of energy conservation potential of electric pumps. motors and other indu strial equipment.

The main emphasis of the process is on quantifying potential energy savings so that the firm has the necessary quantitative data for making a capital decision . Further, the entire process is des~rihed in sufficient detail to permit other universities to follow the field tested methodology and develop their own programs.

2.6 Department o f Energy Program The Department of Energy Program in Industrial Energy Conservation Technology Department is ~harged with responsihility of meeting Federal industrial energy conservation ohjeetives hy cost shared research. development, and demonstration leading to commer~iali zation of energy efficient technology. Considerations for project selection are: energy sav ings . acceleration of implementation. levcl of private effort. henefits to industry. cost sharing and degree of risk.

4 . TECHNOLOGY ISSUES

The specific ohjectives outlined in the industrial energy conservation te~hno logy program are:

Energy requirement for industrial plants and large institutional buildings constitute a very large percent of operating costs. Depending on the nature of manufacturing and process operations. the opportunities for energy management varies considerahly from plant to plant, and institution to institution . In general. the utilities which are essential to most of the energy intensive plants may include :

- Achieve maximum implementation of existing and new energy conservation technologies in as a short time possihle - Substitute. where possihle . ahundant fuels for s~ar~e fuels - Minimize the ene rgy loss emhodied in waste streams of all types

-

The approach taken hy the Department of Energy is to estahlish a partne rship with industry to jointly develop the process and the program to achieve these ohje~tives.

Most of the technology issues as related to entrgy conservation research and development for industrial plants can he grouped into the following three major areas:

Implementation of the strategy starts with an analysis of energy use to define target areas having major potential for energy conservation . In some ~ases. modest savings are possible in a large numher of applications a~ross industry se~tors such as comhustion ~ontrol and ~ogent:ration under a category of horizontal technology. in other ca s~s the target areas are specific to pro~e sses in the industry s u~h as steel. chemical. petro -~ hemical. and textiles. et~ .. requiring energy conservation and solutions for the verti~al le~hnology asso~iated with processes in these indu strie s.

4 . 1 Utility Generation

Ele~tri~ity

Steam Refrigeration (e.g., chillers) Cooling water (e.g .. cooling towers) Compressed air process air

In many instances . steam electricity. chilled water and other utilities arc either produ~ed in the plant or purchased from the outside s"ur~e. There haw heen considerahle effort in the past two decades or so in the development and applications of advanced process control and optimization in utility generation. taking advantage of readily availahle computer systems. Today . computer systems are extensively used in the plant to monitor , alarm, control and management of utility complex and equipment for optimum generation of various utilities for manufacturing and process operations.

3. INDUSTRY/ UNIVERSITY COOPERATION The engineering and resear~h oriented uni versities are increasingly playing a major role as an active memher of a consortium (i.e . . government. industry and universit y) to address and solve the national issues whi~h require . resear~h development, and solutions. In addition. the university is largel y responsihle for educating a nd meeting the skilled manpower requirement for multi - dis~iplined le~hni~al personnel in heat transfer s~ience. ~omhustion. control /optimization. computer appli~ations developme nt. and equipment design. etc .. including programs for continuous education via short ~ourses and video hased intera~tive teaching aids for updating and maintaining skills for the fast changing technological devclopment.

4 .2 Utility Distrihution The distrihution of generated utility to the point of users is an extremely important function in energy management. For example, the steam is distributed to different users through steam headers having different levels of pressure and temperature. Therefore, the steam undergoes a state transformation of the thermodynamic properties: enthalpy and entropy . Therefore, the steam distrihution and allocation strategy should he hased on maximi zing of the use of available work while satisfying the heat requirement of the process operations. And. in the case of in-plant generation, a plant model can he developed to determine. on real time basis, an optimum steam allocation strategy for the hy -product generation while satisfying the steam demand.

In the 1970s. a large teac hing and re sea r~h uni vers it y was selected hy the Department of Energy III develop and demonstrate the concept of an Energy Anal ysis and Diagnos ti~s Ce nter as a part of Ihe it s Indu strial Energy Conservation Program . The ohje~tive of the program is to

4.3 Utility Consumption

694

The huilding energy management system is a suhset of building automation system which includes regulatory / sequential control and monitoring. and supervisory and optimization contml. The huilding energy management system is a real time sensor hased system in which the vital building operational parameters and cOll1rol units as well as the status of the huilding utilit y systems arc monitored. logged and rrescntcd to the operational personnel for their information and attention. Computer systems have hcen used in huilding management systems either as an advisory system or on -line real time management system. In reality. the energy management computer system for huilding management has to perform the tasks which are similar to that of an industrial plant. The heating ventilation and air conditioning management and control is an integral part of the building aut
The opportunity for saving energy is greater in the unit operations than those of utility generation and distrihution . It requires an in-depth study and analysis of process unit operations to insure that the conservation measures would not interfere with the target yield and ljuality of product. 4.4 Energy Accounting Energy accounting has heen viewed as a vital. integral part of energy management system. To evaluate the energy utilization efficiency of the plant. it is important to measure units of energy delivered to the users as accurately as possihle . Energy accounting system may include: - On line energy balance (e.g .. an ahnormal condition can he detected such as steam leak and Cllmpn:ssed air leak) - Develop energy standard for each of the cost centers - Evaluation of effective use of steam - Use of historical data for energy planning - Effective management of contracted purchase of natural gas and electrical power. etc.

6 . IIIFRARCIIICAL ENERGY MANAGEMENT SYSTEM

The trend is dcl'initel y toward hierarchical computer managemcnt system in which a nUlllher of interrelated energy management functions can he implemented: Level I with process measurement /control / optimization. l,evel 2 with process. and Level l with process managemcnt and optimization. Levels 4 and 5 are dedicated to plant and corporate management functions.

4.5 Plant Model For an optimum solution for energy allocations in a plant. there are number of well defined optimization techniques commonly used in energy management solutions: pattern search. linear programming. and direet experimental search . Linear programming technique has heen used to analyze and evaluate the decision variahles (e.g.. steam gelll:ration. kilowatts generated and or purchased) in the utility plant that can be used for energy allocation and system planning.

There arc basicall y two ways in which distrihuted control system can improvc energy cl'ficienc y in process unit operations: regulation and cOll1rol of [lrocess variables closed to a desired value. and application of optimization tcchniljues to allocate plall1 -wide energy loads. resulting in minimum total

To executive this program. the plant model is necessary hy assembling suhmodels of the various components in a plant's steam and electrical distrihution system. Elements of the steam distribution system that are represented as variahles in the model are hoilers. flash tanks. pressure reducing valves. desuperheating stations. deaerators. hoilcr feed water heaters. and turbines. In addition. a numher of constraints are placed on the model. These include material halanu:s for each pressure of these submodels. purchased fuel and power costs under the existing contract must he introduced so that impact of total energy cost can he evaluated as a function of utilitv demand variations and their peaks. To form an integrated plant model. the submodels are connected to each other usin~ mass and heat halances aecording to actual pla,;t configuration.

energy COqs.

A typical hierarchical system architecture is shown in Figure ) All of the kwls and their associated process control. supervision. plant and business management functions are shown in the system configuration. With integration of the manufacturing automation and management information system. a plall1 -w ide database is supported for many different applications. 7. CONCLlISIONS

Thc issues for industrial de velopment differ from plant to plant. allll nation to nation . I [owever. the intend of this paper is to present an overview of some of the major elemell1s which ma y fit into to an over all schell1e of structuring and addressing the critical needs of energy issues for industrial development. Technology development and applications are vital to conscrving non -rencwahle natural resources and seeking alternative energy sources for ever increasing demand of the energy needs in the industry . Government, industry. and universit y cooperation is critical in the development of national energy polic y which support a rational and orderly growth of the industry while complying with the international standards in environmental protection. It is also responsibility of scientific and engineering community of the world to activel v seek. cooperate and solve many energy and environmell1al issucs through research and development.

Linear programming offers a real time solution to total energ y allocation needs of a complex utility plant which can he implemented as a advisory system in which "how to operate information" is given to the operations personnel for their actions or it can he configured for a totally automatic system. Boiler model hased optimization techniljue. as a suhmodel of the total plant. is depicted in Figure I. Figure I is a functional diagram representing the application of the individual unit cost allocation technique to single fuel hoilers. I'or hoiler load a\location. the master demand variahle is steam header pressure; the master demand controller setpoint is the operator entered pressure setpoint. The allocation ohjective is to load boilers ha sed on the operating economics which utilize the individual hoiler and its real time stcam generation cost. This is a typical example of how the optimum setpoints from a computer optimization program can he implemented in the powerhouse. having a numher of dissimilar parallel hoilers with different fuel types and efficiencies which contrihute to different incremental steam generation costs.

X REFERENCES CllO. (' 11 (19R4). Computer Based Fnergy Management Sys tell1s and Applications. Academic Press. Inc. New York Cho. CII. and N Norden (19X2) Computer Optimization of RcI'rigeration Systems in a Textile Plant - A Case history. II'A('. Automatica. VoI.IX. Nov . 6. PP . 67S6Xl

5. BUILDING ENERGY MANAGEMENT SYSTEM

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Cho, C.H. (1974). Let's Examine the Role of the Compute r in a Plant Energy Conserva tion Program , ISA International Conferen ce , New York Cho, C.H. (1991) . Modelling and Control in Energy Managem ent, IMEKO TC7 International Symposium on Artificial Intelligence hased Measurement and Control. Kyoto , Japan

SYSTEM DEMAND SIGNAL (HEADER PRESSURE)

BOILER LOADS

BOILER AVAILABILIT Y STATUS

OPTIMIZER BOILER MASTER BIAS ADJ.

STEAM COSTS

PROCESS VARIABLES EFFICIEHCIE S

UNIT COST ARRAY

Fig. 1. Funct ion Block Diagra m - Boile r Load Alloc ation

Level 5

- BIlling - Payroll - Personnel

- Research and Development - Order Processing - Accounting

Level 4

- Inventory Control - Work in Process - Production Planning - Materials Planning - Cost Accounting

- Electronic Data Interchange - Preventive Maintenance - Repair Order Management - Spare Parts

Level 3

- Date Hlstorian/ Batch Tlacking - Scheduling - Optimization

Process Management

- Process Simulation - Product Ouality I Process OA I SPC

Level 2

- Alarming - Process Graphics - Process Trending

Process Supervision

- Report Generation - Recipe Management

Level 1

Plant Management

- Process Control (PlO) - Process Interlocks - Discrete Control I Logic - Advanced Control - Advanced Sequenclng - Third Party Interlaces

Process Control

- Batch Control

Fig. 2. Hiera rchic al System Arch itectu re

696