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Hybrid Energy Systems—Strategy for Decarbonization
Published in Yatish T. Shah, Hybrid Energy Systems, 2021
Many process industries, such as chemical plants, oil refineries, and pulp and paper mills, require large amounts of process heat for such operations as chemical reactors, distillation columns, steam driers, and other uses. This heat, which is usually used in the form of steam, can be generated at the typically low pressures used in heating, or can be generated at much higher pressure and passed through a turbine first to generate electricity. In the turbine, the steam pressure and temperature are lowered as the internal energy of the steam is converted to work. The low-pressure steam leaving the turbine can then be used to process heat.
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Published in Clark W. Gellings, The Smart Grid: Enabling Energy Efficiency and Demand Response, 2020
Generally, process heat is used for melting, heating and drying operations. Specific applications include distilling, annealing, fusing, cooking, softening and moisture removal. There are a variety of electric heating systems currently available, and there are many emerging technologies. The most common electric process heat technologies include resistance heaters, induction heaters, infrared systems, dielectric systems (RF and microwave), electric salt bath furnaces, and direct arc electric furnaces. The following section of this chapter summarizes some of the energy efficiency opportunities for process heat applications.
Vapor and Advanced Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
It was mentioned earlier in Chapter 5 that even a best efficient heat engine requires about 250 kJ of energy input for producing 100 kJ of work. The remaining 150 kJ of energy is rejected to the surroundings in another form as waste heat but not as work. This waste heat, being of low quality, cannot be used for any purpose. However, there are many systems that require energy in the form of heat known as process heat as in the case of sugar industries, textiles, paper mills, refineries, steel manufacturing units, and some chemical industries. These systems require process heat supplied by the steam at a pressure of 5–7 bar and temperature around 200°C for heating and drying purposes. Saturated steam at the desired temperature is suitable for constant temperature heating as steam is good medium. Usually saturated steam is condensed at that temperature so that isothermal conditions are achieved. The power plant that is simultaneously producing the electric power and process heat is called a cogeneration plant. Cogeneration is producing more than one form of useful energy from the same source of energy.
Assessment of decarbonization possibilities in Lithuania’s chemical industry
Published in Energy Sources, Part B: Economics, Planning, and Policy, 2023
Egidijus Norvaiša, Arvydas Galinis, Eimantas Neniškis
Process heat (the essential energy carrier in the industry) is supplied by traditional utility infrastructure based on boilers supplying steam or hot water for the whole production site (indirect heat) or by direct combustion of the fuels inside the production processes. The required temperature level is determined by the nature of the process and could exceed 1400°C, for example, in cement manufacturing. Consequently, we separated four process heat categories: direct/indirect and below 150°C/above 150°C, with the specified shares based on data from Danish Energy Agency (Danish Energy Agency and Energinet 2020a). Such an assumption was made due to the lack of data on the shares of different temperature heat energy consumed by the Lithuanian chemicals sector, dominated by only two major fertilizer facilities. For the chemical sector, indirect heat constitutes 80% (of which 8% is low and 72% high temperature), while direct heat 20% (of which 2% is low and 18% high temperature) based on (Danish Energy Agency and Energinet 2020a). Such differentiation is necessary due to the utilized technology’s distinct technical, economic, and environmental parameters.
Optimizing vehicle fleet and assignment for concentrating solar power plant heliostat washing
Published in IISE Transactions, 2022
Jesse G. Wales, Alexander J. Zolan, Alexandra M. Newman, Michael J. Wagner
Concentrating Solar Power (CSP) technologies can utilize the heat from sunlight that is redirected by a field of sun-tracking mirrors, i.e., heliostats, to a central location. The heat produced by this process may be: (i) directly used as industrial process heat; (ii) converted to electricity using conventional power cycle technology; and/or (iii) paired with thermal energy storage in the form of molten salts, which may be stored and dispatched at a later time. Thermal energy storage makes the electricity produced by CSP highly dispatchable and, therefore, unique among non-hydropower renewable energy resources, whose intermittency can limit their value to the grid (Gowrisankaran et al., 2016). The value proposition offered by solar-powered baseload and dispatchability, combined with reductions in thermal energy storage costs, has contributed to growth in CSP adoption in recent years (Gauché et al., 2017). The foremost CSP technologies at the research and commercial scales are: (i) parabolic trough; (ii) central-receiver (also known as a “power tower”); (iii) linear Fresnel; and (iv) dish engine. Parabolic troughs and central receivers currently compose about 95% of all CSP plants (Xu et al., 2016), and central-receiver systems represent the greatest opportunity for efficiency gains and cost reduction (Margolis et al., 2012). Figure 1 displays an example solar field for a central-receiver CSP plant. We focus on the washing operations costs in central-receiver systems related to soiling, which reduces the reflectivity of the heliostats and, therefore, the efficiency of the system. We present a model for planning wash vehicle fleet size, mix, and assignment to minimize revenue losses due to soiling and costs due to washing operations.
Waste heat recovery through cascaded thermal energy storage system from a diesel engine exhaust gas
Published in International Journal of Ambient Energy, 2020
Cyril Joseph Daniel, Radhika Koganti, Anish Mariadhas
Stationary diesel engines are utilised in a wide number of applications in industrial, commercial, marine and municipal locations. Diesel engines are most commonly used together with a generator to produce electricity for prime or emergency conditions. The crunch of energy demand has driven energy developing countries to find an efficient alternative renewable energy source which is further accelerated with increasing emission concern and fossil fuel depletion (Venu et al. 2020; Rameshbabu et al. 2020). In the present energy crisis, situation energy saving/storing technology is must. A major result of the energy conservation drive is the development of process heat recovery, aimed at reducing the amount of waste heat discharged to the environment, thus increasing the overall efficiency of various processes and systems. Many techniques of heat recovery systems and new developments are continually being introduced (Su et al. 2020; Venkitaraj, Suresh, and Venugopal 2018; Jayaraman et al. 2019; Jayaraman et al. 2020). Diesel engines are used in automobiles, stationary power generating plants, air compressors and construction machinery, etc. About one-third of the heat generated is lost into the surroundings of the combustion space, remainder being dissipated through exhaust and radiation from the engine. As the fuel prices continue to escalate, the relevance of efficient energy management is apparent to companies everywhere, from the smallest concerns to the largest multinationals. The methods and techniques adopted to improve energy utilisation will vary depending on circumstances. Large quantity of hot flue gases is generated from Diesel Generating (DG) set. If some of this waste heat could be recovered, 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 loss minimised by adopting various waste heat recovery systems (Kanimozhi et al. 2014).