Evaluation method of the energy conversion efficiency of coal gasification and related applications

Abstract

Summary Traditional gasification parameters, such as cold gas efficiency, hot gas efficiency, or thermal efficiency, only evaluate the heat energy utilisation efficiency of gasifiers and do not take into account the gasification processes expending electricity and other types of energies. Therefore, the energy conversion efficiency cannot be assessed using these parameters. The calculation process on the energy conversion efficiency of underground coal gasification (UCG) is the basis for obtaining quantitative data of carbon emission reduction and establishing the carbon trading methodology of UCG. Moreover, the energy conversion efficiency both for surface coal gasification and UCG is a key research topic because it directly affects the economic and environmental benefits of gasification projects. This study proposed that two parameters, the integrated gasification efficiency (hcom) and the hot gas integrated gasification efficiency ( hnormalcnormalonormalm′), should be included into the coal gasification parameters and used to evaluate the energy conversion efficiency of coal gasification. In addition, the calculation methods of these two parameters for both surface gasification and UCG were established. Using the method, hcom and hnormalcnormalonormalm′, of the UCG and Texaco gasification under the same scale was compared and that of various UCG processes was calculated. The results proved the necessity and reasonability of the two parameters and suggested that a certain amount of CO2 was favourable to improve hcom and hnormalcnormalonormalm′ of UCG. However, a certain amount of pure O2 can improve hcom of UCG without direct influences on hnormalcnormalonormalm′. Under the condition of each process, to maximise hcom and hnormalcnormalonormalm′, there must be an optimal steam (CO2) to O2 rate. Copyright © 2015 John Wiley & Sons, Ltd.

Experimental Study of Coal Pyrolysis under the Simulated High-Temperature and High-Stress Conditions of Underground Coal Gasification

“…In addition, methane emissions are reduced. − The resources that are buried deep underground are inaccessible for traditional mining methods. , However, these kinds of resources can be utilized by UCG. Therefore, UCG is an efficient method for directly converting deep coal resources into clean energy and reducing carbon emissions. − However, the technology has several limitations. It can have significant environmental consequences including aquifer contamination and ground subsidence.…”

Life Cycle Analysis of Integrated Gasification Combined Cycle Power Generation in the Context of Southeast Asia

“…These include mining, transport, drying and pulverizing, power generation, and waste disposal, but exclude gasification and pre-combustion carbon capture. The energy consumption for the gasification process is 15.74 kWh/t-coal as converted from [32]. The energy input for steam-methane reforming and water-gas shift reactions is 3.93 MJ/Mt-H 2 for natural gas and 0.15 MJ/Mt-H 2 for electricity as obtained from [33].…”

Experimental Studies of the Effect of Design and Technological Solutions on the Intensification of an Underground Coal Gasification Process

“…Currently, production of energetically valuable liquid fuel from coal is the industrially developed process; in this context, reactions of incomplete coal oxidation are quite often to Energies 2021, 14, 4369 2 of 18 have in surface gas generators [12,13]. A main disadvantage of surface gas generators is their high cost and considerable expenditures for coal extraction and transportation to the place of processing [14]. Underground coal gasification (UCG) is a prospective tendency of deep coal processing; that provides the reactions of incomplete coal oxidation in terms of underground conditions immediately within the place of coal seam occurrence-in an underground gas generator-with production of gas (after its corresponding surface-based processing), which is close to natural gas in its consumer properties [15,16].…”