Energy Management: Strategies for Efficient Energy Use and Cost Savings, Lecture notes of Engineering Science and Technology

Download Energy Management: Strategies for Efficient Energy Use and Cost Savings and more Lecture notes Engineering Science and Technology in PDF only on Docsity! SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 1 OF 22 Waste heat is heat generated in a process by way of fuel combustion or chemical reaction,which is then “dumped” into the environment and not reused for useful and economic purposes. The essential fact is not the amount of heat, but rather its “value”. The mechanism to recover the unused heat depends on the temperature of the waste heat gases and the economics involved. Large quantities of hot flue gases are generated from boilers, kilns, ovens and furnaces. If some of the waste heat could be recovered then a considerable amount of primary fuel could be saved. The energy lost in waste gases cannot be fully recovered. However, much of the heat could be recovered and adopting the following measures as outlined in this chapter can minimize losses. Heat Pumps The majority of heat pumps work on the principle of the vapour compression cycle. In this cycle, the circulating substance is physically separated from the source (waste heat, with a temperature of Tin) and user (heat to be used in the process, Tout) streams, and is re-used in a cyclical fashion, therefore being called 'closed cycle'. In the heat pump, the following processes take place: § In the evaporator, the heat is extracted from the heat source to boil the circulating substance; § The compressor compresses the circulating substance, thereby raising its pressure and temperature. The low temperature vapor is compressed by a compressor, which requires external work. The work done on the vapor raises its pressure and temperature to a level where its energy becomes available for use. § The heat is delivered to the condenser; § The pressure of the circulating substance (working fluid) is reduced back to the evaporator condition in the throttling valve, where the cycle repeats. The heat pump was developed as a space heating system where low temperature energy from the ambient air, water, or earth is raised to heating system temperatures by doing compression work with an electric motor-driven compressor. The arrangement of a heat pump is shown in figure SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 2 OF 22 The heat pumps have the ability to upgrade heat to a value more than twice the energy consumed by the device. The potential for application of heat pumps is growing and a growing number of industries have been benefited by recovering low grade waste heat by upgrading it and using it in the main process stream. Heat pump applications are most promising when both the heating and cooling capabilities can be used in combination. One such example of this is a plastics factory where chilled water from a heat is used to cool injection-moulding machines, whilst the heat output from the heat pump is used to provide factory or office heating. Other examples of heat pump installation include product drying, maintaining dry atmosphere for storage and drying compressed air. Principles of energy conservation: 1. Maximum thermodynamic efficiency 2. Maximum cost effectiveness Energy Conservation measures in industry: 1. The selection and process should be such that it involves efficient use of energy. 2.The plant and equipment should be selected with special emphasis on reliability, maintainability and energy efficiency vis-à-vis quality and control of output. 3.The location of plant and equipment should be such that energy costs of transportation of raw materials and finished products are minimum. 4.The use of renewable sources of energy i.e. solar, wind, etc. should be encouraged to reduce the consumption of non-renewable source of energy i.e. electricity oil etc. 5.The regular cleaning, inspection, and lubrication should be adhered with a view to eliminate unreliability in production and have a proper quantity quality to output. 6.The production schedule and service should be planned and implemented with minimum use of resources i.e. labors, machine, materials etc. 7.Expensive purchase of raw material and stocking of finished products should be avoided. 8.The wastage in production and service must be kept at minimum. 9.all motors, cables, switches, gears etc. of the production machines should be adequately loaded. Overloading and under loading should be avoided. 10. The latest maintenance techniques and tools should be used to prolong the life of machines like preventive maintenance, predictive maintenance etc. based on requirements. 11. The lighting in and around the factory area should be as per the standard and with minimum requirements. 12. Use of waste heat from the process of plants should be effectively used. 13. The use of service facilities like air cooling, air conditioning, humidification, steam, water, compressed air etc. should be very efficiently and effectively used. 14. The peak load of the electricity requirements should be kept as near the average load as possible to control the maximum demand i.e. to reduce loads factors. 15. The power factor of the electrical load should be kept higher than 0.90 to 0.95 SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 5 OF 22 - Energy consumption monitoring - Planing energy conservation - Implementing energy conservation measures - Organization of HRD programmes - Achieve EC objectives. 4 Formulation of supply strategies and energy conservation plans 5 Awareness and Involvement. 6 Introduce suggestions, schemes and award schemes. 7 Appoint or select energy Audit Team or consultants. 8 To obtain report on EC measures. 9 To obtain technical assistant report (TA-report) Instructions in TA report a) EC measures b) Do or Don’t c) Operation and maintenance instructions. d) Recommendation of a new technology. 10 Implementation of TA report and EC measures. 11 Implement E-optimized operation and maintenance practices. 12 Establish practice of monitoring energy consumption and effectiveness of ECM’s. 13 Recycling of scrap, waste material, etc. 14 To review and optimize new design of the plant and equipment and to allocate finds for retro fitting. SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 6 OF 22 Energy strategies (planning) Power sector (Electricity) Supply side management Oil or Gas Coal Non commercial & renewable Consumption/ demand side Industrial sector Agricultural Household (domestic) & commercial Transport Others SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 7 OF 22 Supply side Power sector Electrical energy management Generation of power- Thermal (coal/gas, Hydro, Nuclear) Transmission (AC, high voltage interconnections, SCADA systems) Utilization of energy (Plant, industry, managed by SCADA systems) Fuel (Oil, natural gas, coal, fire-wood, chemicals etc) Non commercial/ renewable energy (a) Land biomass, solar, wind, geothermal, tidal etc. (b) human energy (labor) (c) Animal energy SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 10 OF 22 Energy Planning for each Sector Exploration/ Extraction/ onversion Processing/ by products/ Cleaning Storage/ Transport/ Transmission Distribution/ Supply Data Collection Determine the resources available Strategies are formed Plan the entire energy routes Determine the demand Evaluation of trends Evaluate the economic viability & fixing of tariff/ Rates Formulate the long/ medium/ short term plan SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 11 OF 22 Organization Structure Listing of essential activities Grouping of activities – whether it is related to space heating, power, fuel, Decision of responsibilities Interfacing between the groups Organization Non- energy (They just consume energy & produce products) Energy Intensive (which are using, as well as producing energy + products) Non- Energy Organization Chart Operation & maintenance manager with additional Responsibilities of EM Line Managers Delegation Interfacing Plant Manager SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 12 OF 22 Strategies Adopted by Indian Government for E.M 1 Apply Reforms to Energy & Power sectors, with de-control, privatization and the international help for raid growth. 2 Accelerate production and supply of energy though fast-track energy routes e.g. unbundling the potential in existing industries particularly those, which are generating their own power by improving plant load factor (PLF) and carrying out renovation and modernization; improve energy management system; accelerate fast- track liquid & gas fuel supply. 3 Increase the per capita energy consumption rural sector. 4 Improve efficiency and plant load factor (PLF) from the present 60% to 85% and reduce the transmission losses from 20-25% to 10-12%. 5 Encourage EC Measures and improve energy demand side management and recycling of the wastes. 6 Reduce the energy imports and achieve self-reliance in energy. 7 Encourage the use of non-conventional energies in industries and other sectors. 8 Encourage rural-electrification. 9 Encourage privatization in energy sector. 10 Reduce or minimize the pollution. 11 Encourage the forest development. 12 Encourage the conversion of Bio-waste to useful energy. 13 Encourage the R & D in energy sector for energy efficiency prospects and for finding alternatives for the future. SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 15 OF 22 • Becoming—or continuing to be—economically competitive in the global marketplace, which requires reducing the cost of production or services, reducing industrial energy intensiveness, and meeting customer service needs for quality and delivery times. Significant energy and dollar savings are available through energy management. Most facilities (manufacturing plants, schools, hospitals, office buildings, etc) can save according to the profile shown in Figure 1.1. Even more savings have been accomplished by some programs.  Low cost activities first year or two: 5 to 15%  Moderate cost, significant effort, three to five years: 15 to 30%  Long-term potential, higher cost, more engineering: 30 to 50% Figure 1.1 Typical Savings through Energy Management Thus, large savings can be accomplished often with high returns on investments and rapid paybacks. Energy management can make the difference between profit and loss and can establish real competitive enhancements for most companies. Energy management in the form of implementing new energy efficiency technologies, new materials and new manufacturing processes and the use of new technologies in equipment and materials for business and industry is also helping companies improve their productivity and increase their product or service quality. Often, the energy savings is not the main driving factor when companies decide to purchase new equipment, use new processes, and use new high-tech materials. However, the combination of increased productivity, increased quality, reduced environmental emissions, and reduced energy costs provides a powerful incentive for companies and organizations to implement these new technologies. Total Quality Management (TQM) is another emphasis that many businesses and other organizations have developed over the last decade. TQM is an integrated approach to operating a facility, and energy cost control should be included in the overall TQM program. TQM is based on the principle that front-line employees should have the authority to make changes and other decisions at the lowest operating levels of a facility. If employees have energy management training, they can make informed decisions and recommendations about energy operating costs. • Maintaining energy supplies that are: — Available without significant interruption, and — Available at costs that do not fluctuate too rapidly. SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 16 OF 22 SOME SUGGESTED PRINCIPLES OF ENERGY MANAGEMENT If energy productivity is an important opportunity for the nation as a whole, it is a necessity for the individual company. It represents a real chance for creative management to reduce that component of product cost that has risen the most since 1973. Those who have taken advantage of these opportunities have done so because of the clear intent and commitment of the top executive. Once that commitment is understood, managers at all levels of the organization can and do respond seriously to the opportunities at hand. Without that leadership, the best designed energy management programs produce few results. In addition, we would like to suggest four basic principles which, if adopted, may expand the effectiveness of existing energy management programs or provide the starting point of new efforts. The first of these is to control the costs of the energy function or service provided, but not the Btu of energy. As most operating people have noticed, energy is just a means of providing some service or benefit. With the possible exception of feed stocks for petrochemical production, energy is not consumed directly. It is always converted into some useful function. The existing data are not as complete as one would like, but they do indicate some surprises. In 1978, for instance, the aggregate industrial expenditure for energy was $55 billion. Thirty-five percent of that was spent for machine drive from electric motors, 29% for feedstocks, 27% for process heat, 7% for electrolytic functions, and 2% for space conditioning and light. As shown in Table 1.1, this is in blunt contrast to measuring these functions in Btu. Machine drive, for example, instead of 35% of the dollars, required only 12% of the Btu. In most organizations it will pay to be even more specific about the function provided. For instance, evaporation, distillation, drying, and reheat are all typical of the uses to which process heat is put. In some cases it has also been useful to break down the heat in terms of temperature so that the opportunities for matching the heat source to the work requirement can be utilized. In addition to energy costs, it is useful to measure the depreciation, maintenance, labor, and other operating costs involved in providing the conversion equipment necessary to deliver required services. These costs add as much as 50% to the fuel cost. It is the total cost of these functions that must be managed and controlled, not the Btu of energy. The large difference in cost of the various Btu of energy can make the commonly used Btu measure extremely misleading. In November 1979, the cost of 1 Btu of electricity was nine times that of 1 Btu of steam coal. Table 1.2 shows how these values and ratios compare in 2005. SCHX1036 ENERGY ENGINEERING UNIT V ENERGY CONVERSION AND MANAGEMENT PREPARED BY: Dr.D.JOSHUA AMARNATH PAGE: 17 OF 22 One of the most desirable and least reliable skills for an energy manager is to predict the future cost of energy. To the extent that energy costs escalate in price beyond the rate of general inflation, investment pay backs will be shortened, but of course the reverse is also true. A quick glance at Table 1.2 shows the inconsistency in overall energy price changes over this period in time. Even the popular conception that energy prices always go up was not true for this period, when normalized to constant dollars. This volatility in energy pricing may account for some business decisions that appear overly conservative in establishing rate of return or payback period hurdles. Availabilities also differ and the cost of maintaining fuel flexibility can affect the cost of the product. And as shown before, the average annual price increase of natural gas has been almost three times that of electricity. Therefore, an energy management system that controls Btu per unit of product may completely miss the effect of the changing economics and availabilities of energy alternatives and the major differences in usability of each fuel. Controlling the total cost of energy functions is much more closely attuned to one of the principal interests of the executives of an organization — controlling costs. NOTE: The recommendation to control energy dollars and not Btus does not always apply. For example, tracking building energy use per year for comparison to prior years is best done with