工业余热回收利用英文文献翻译 ABSTRACT
This paper describes the results of an analysis of the opportunity for industrial waste heat to power in the United States using the organic Rankine cycle. The EPA National Emissions Inventory databases are used to quantify the available heat content and temperature of the sources. By frequency, the majority of waste heat sources are at temperatures below 450°F (232°C) however, more than half of the total opportunity for waste heat to power comes from sources with exhaust gas temperature between 500°F and 1000°F (260 and 538°C). While these temperatures are not high enough to make steam based generation attractive they are high enough that working fluid decomposition must be considered in the opportunity analysis. For sources under 1000°F (538°C) including the limitations of working fluid decomposition brings the technically recoverable power from 44 to 32 GW. Total opportunity, including all sources over 300°F (149°C) is estimated to be 51 GW. In addition to opportunity analysis the kinetics of working fluid decomposition are discussed and calculated for several widely used fluids as a function of temperature.
INTRODUCTION
Lawrence Berkeley National Laboratory (LBNL) predicts there is 100 GW of waste heat to electric power potential in the United States (Baily and Worrell 2005). This figure represents over 10% of the current installed capacity of electric generators in the country. This potential presents an opportunity to produce low cost, virtually zero emissions, local generation to assist in meeting power quality needs and pending clean energy regulations such as Renewable Portfolio Standards.
In many cases industrial process heat is discharged to the atmosphere still containing 60+% of the heat from the combustion process. Unless there is an opportunity for use of this heat at the industrial site, it is almost certainly wasted. However, conversion of the waste heat to electricity provides energy that can be used either at the site, or it can be economically transported over long distances to another customer. As long ago as 1979, studies investigated technology capable of transforming waste heat into electricity (General Electric 1979). With increases in fuel and electricity prices, the economic case for harvesting this wasted energy has become even more compelling.
Industrial heat sources vary widely with respect to size, exhaust temperature, primary fuel source, duty cycle, and contaminant content. Depending on the relative influence of these factors, different technologies may be more appropriate than others for converting the heat to power. Rankine cycle power generation is a well known technology and, with steam as a working fluid, is the basis for the vast majority of power generation worldwide. It remains the premier choice for power generation for waste heat to electric power conversion in many high temperature applications. Because of the thermal stability of steam it can be used in cases where the source temperatures are very high without fear of thermal decomposition. However, because of turbine size, vacuum conditions in the condenser, and the need to avoid condensation in the turbine, steam is most appropriate for the largest sources of high temperature waste heat. Also, because of design considerations with small molecular weight working fluids, steam turbines generally have lower efficiency than organic working fluid turbines for sizes below several megawatts (Table 1 after Abbin and Leuenberger 1974). For waste heat sources below 1000°F (538°C) or smaller than 1 MW output capacity, organic working fluids are more likely to provide better overall economics. Exceptions include industrial facilities that require process steam or existing power plants where steam is already being used as a working fluid. Even in cases where very high temperature sources are present, environmental conditions such as access to water, permitting requirements, and maintenance costs may influence the ultimate decision regarding whether or not to consider steam as a working fluid.3016
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