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[en] Absorption of low temperature steam in the acid concentrate raises the temperature of diluted acid stream. Heat pump based on this principle, called as acid absorption chemical heat pump (AACHP) is coupled with high energy demanding separation unit like distillation column to reduce the heat requirements. This article highlights the advantages of employing AACHPs. AACHP eliminates the need for sophisticated compressors. AACHP based on acid-water system is described. About 95% of supplied heat to the distillation unit is wasted through the cooling water to the environment, but net saving in heat is found to be approximately 40% if a distillation column is coupled with AACHP.(M.G.B.)
[en] Highlights: • A methodology for energy efficiency of large-scale chemical plants is developed. • A multi-level data extraction for energy requirement definition is introduced. • The practice of total site integration with the combination of levels is shown. • The suitable utilities are integrated and optimized for different proposals. • A Pareto analysis is performed to find the optimum combination of levels. - Abstract: This study presents a methodology based on process integration techniques to improve the energy efficiency of a large-scale chemical plant. The key to the approach is to represent the energy requirements with different heat transfer interfaces. Considering difficulties of data extraction for a large-scale plant, a multi-level data extraction scheme is introduced based on different heat transfer interfaces and includes five levels of growing complexity: black-box, grey-box, white-box, simple-model and detailed-model analysis. A combination of these levels instead of a single definition for the energy requirement has been applied on an industrial case study. Different steps of the approach are explained in detail and their potential are highlighted. The Single Process Integration (SPI) and Total Site Integration (TSI) has been performed and revealed that a higher potential of heat recovery could be driven through the TSI. The optimized site utility integration together with heat recovery improvement scenarios have considerably increased the energy saving potential in our case study. A multi-objective optimization has also been performed to find the optimum combination of units with different energy requirement levels. In conclusion, results from our case study have indicated that using a combination of different energy requirement levels will reduce the required modification of the actual site configuration
[en] Heat transformers are a promising technology for optimal exploitation of waste heat streams. The use of heat transformers is efficient for energetic, exergetic, and economic reasons. Heat transformers are environment-friendly, and reduce both thermal pollution and the pollution by greenhouse gases. The practical use of heat transformers is however still limited to the water/LiBr pair. The application of new media and the multistage heat transformer are promising new developments. (A.S.)
[en] For three sites located in Burundi, Madagascar and Rwanda which have been selected after a previous study, this document reports a feasibility study and the definition of the characteristics of micro geothermal plants which could be installed there. These plants convert thermodynamic energy into mechanical and electric energy, with a recoverable power of 15 kWe. After a description of the operation of such micro-plants (principle, hot water and cold water circuits, exchangers, engine, freon circuit, electric power production, regulation and automatism), and a description of the selected sites (location, physical and chemical characteristics), a pre-sizing is reported (fluid selection, needed water flow rates, components). The report discusses the use of the produced electric power, and reports an assessment of construction costs (site development, plant construction and installation), discusses the exploitation and installation of the plant. Results are globally discussed in terms of thermal and cold water flow rates, of possible electric power, and of chemistry of underground waters. If the operation appears to be technically feasible, the cost appears to be high due to the characteristics of the thermal water temperature
[en] In the frame work of rationalization of energy resources, USSR implemented a wide program to utilize nuclear energy for heat generation. The different solutions adopted in the existing and under construction plants are described and reviewed. The actual trend is to prefer low power cogeneration plants to be located close to large urban areas
[en] These specifications aim at describing the typical process and content of an assessment study of unavoidable heat potentials which are available within a specific territory, thus allowing deeper and more targeted studies to be performed for the implementation of unavoidable heat recovery projects. This concerns any effluent type, whatever its type (gas, liquid) and origin (industry, waste incineration plants, energetic valorisation units, data-centres, and so on) are. Four main phases are identified and discussed: inventory of unavoidable heat sources, assessment of the local valorisation potential, proposition of a strategy of actions, and study communication.
[en] Highlights: • Trigeneration technologies classified and reviewed according to prime movers. • Relevant heat recovery equipment discussed with thermal energy storage. • Trigeneration evaluated based on energy, exergy, economy, environment criteria. • Design, optimization, and decision-making methods classified and presented. • System selection suggested according to user preferences. - Abstract: Electricity, heating, and cooling are the three main components constituting the tripod of energy consumption in residential, commercial, and public buildings all around the world. Their separate generation causes higher fuel consumption, at a time where energy demands and fuel costs are continuously rising. Combined cooling, heating, and power (CCHP) or trigeneration could be a solution for such challenge yielding an efficient, reliable, flexible, competitive, and less pollutant alternative. A variety of trigeneration technologies are available and their proper choice is influenced by the employed energy system conditions and preferences. In this paper, different types of trigeneration systems are classified according to the prime mover, size and energy sequence usage. A leveled selection procedure is subsequently listed in the consecutive sections. The first level contains the applied prime mover technologies which are considered to be the heart of any CCHP system. The second level comprises the heat recovery equipment (heating and cooling) of which suitable selection should be compatible with the used prime mover. The third level includes the thermal energy storage system and heat transfer fluid to be employed. For each section of the paper, a survey of conducted studies with CHP/CCHP implementation is presented. A comprehensive table of evaluation criteria for such systems based on energy, exergy, economy, and environment measures is performed, along with a survey of the methods used in their design, optimization, and decision-making. Moreover, a classification diagram of the main CHP/CCHP system components is summarized. A general selection approach of the appropriate CCHP system according to specific needs is finally suggested. In almost all reviewed works, CCHP systems are found to have positive technical and performance impacts.
[en] Highlights: • A new practical heat integration framework was developed for complex and diverse production lines. • Heat recovery was maximised by direct and indirect heat integration at zonal and factory levels. • A novel approach to stream data extraction was proposed to account for both stream capacity and availability. • A case study was carried out on a multi-product confectionery factory. - Abstract: Heat integration is a key measure to improving energy efficiency and maximising heat recovery. Since the advent of Pinch analysis in the 1980s, direct and indirect integration approaches have developed in separate domains with very few examples where both approaches are utilised together to maximise heat recovery. This paper presents a novel decision-making framework for heat integration in complex and diverse production lines, with the aim to provide the user with a step-by-step guide to evaluate all heat recovery opportunities through a combination of direct and indirect heat integration. This framework involves analysis at both the zonal level and the factory level. The proposed framework was applied to a case study based on a confectionery factory in the UK that manufactured multiple products across a diverse range of food technologies. It demonstrates that the framework can effectively identify the significant streams to be considered in the heat integration analysis, and address practical factors such as diverse production times, geographical proximity, and potential of compromise to product quality when the direct and indirect heat integration opportunities are proposed and assessed both within and between production zones. This practical framework has the potential to benefit the wider food industry and beyond