Exergy Destruction Mechanism of Coal Gasification by Combining the Kinetic Method and the Energy Utilization Diagram

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Handong Wu ◽  
Sheng Li ◽  
Lin Gao
Keyword(s):  
Chemical Reactions ◽  
Coal Gasification ◽  
Kinetic Method ◽  
Steam Gasification ◽  
Energy Utilization ◽  
Exergy Destruction ◽  
Steam Content ◽  
Carbon Gasification ◽  
Destruction Mechanism ◽  
Gasification Reaction

Gasification is the core unit of coal-based production systems and is also the site where one of the largest exergy destruction occurs. This paper reveals the exergy destruction mechanism of carbon gasification through a combined analysis of the kinetic method and the energy utilization diagram (EUD). Instead of a lumped exergy destruction using the traditional “black-box” and other models, the role of each reaction in carbon gasification is revealed. The results show that the exergy destruction caused by chemical reactions accounts for 86.3% of the entire carbon gasification process. Furthermore, approximately 90.3% of exergy destruction of chemical reactions is caused by the exothermal carbon partial oxidation reaction (reaction 1), 6.0% is caused by the carbon dioxide gasification reaction (reaction 2), 2.4% is caused by the steam gasification reaction (reaction 3), and 1.3% is caused by other reactions under the base condition. With increasing O2 content α and decreasing steam content β, the proportion of exergy destruction from reaction 1 decreases due to the higher gasification temperature (a higher energy level of energy acceptor in EUD), while the proportions of other reactions increase. This shows that the chemical efficiency is optimal when the extent of reactions 1 and 3 is equal and the shift reaction extent approaches zero at the same time.

Novel Coal-Steam Gasification With a Thermochemical Regenerative Process for Power Generation

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Dandan Wang ◽  
Sheng Li ◽  
Lin Gao ◽  
Handong Wu ◽  
Hongguang Jin
Keyword(s):  
Energy Level ◽  
Coal Gasification ◽  
Combined Cycle ◽  
Steam Gasification ◽  
Energy Utilization ◽  
Plant Performance ◽  
The Novel ◽  
Sensible Heat ◽  
Exergy Destruction ◽  
Separation Unit

In this paper, a novel high-efficiency coal gasification technology is proposed in which a regenerative unit is applied to recover syngas sensible heat to generate steam; then, the high-temperature steam is used to gasify coke from a pyrolyzer. Through such a thermochemical regenerative unit, the sensible heat with a lower energy level is upgraded into syngas chemical energy with a higher energy level; therefore, high cold gas efficiency (CGE) is expected from the proposed system. aspenplus software is selected to simulate the novel coal gasification system, and the key parameters are validated by experimentation. Then energy, exergy, and energy-utilization diagram (EUD) analyses are applied to disclose the plant performance enhancement mechanism. It is revealed that 83.2% of syngas sensible heat can be recovered into steam agent with the CGE upgraded to 90%. In addition, with the enhancement of CGE, the efficiency of an integrated gasification combined cycle (IGCC) based on the novel gasification system can be as high as 51.82%, showing a significant improvement compared to 45.2% in the general electric company (GE) gasification-based plant. In the meantime, the irreversible destruction of the gasification procedure is reduced to 25.7% through thermochemical reactions. The increase in the accepted energy level (Aea) and the decreases in the released energy level (Aed) and heat absorption (ΔH) contribute to the reduction in exergy destruction in the gasification process. Additionally, since the oxygen agent is no longer used in the IGCC, 34.5 MW exergy destruction in the air separation unit (ASU) is avoided.

scholarly journals A Chemical Reaction Can Save Mankind -A Review of Experiment Research on CO2+C=2CO and Application

2021 ◽  
Vol 13 (2) ◽  
pp. 1
Author(s):  
Jia-Min Jin
Keyword(s):  
Catalytic Activity ◽  
Power Plant ◽  
Chemical Reaction ◽  
Flue Gas ◽  
Physical Phenomenon ◽  
Experiment Research ◽  
Carbon Gasification ◽  
Long Time ◽  
Gasification Reaction ◽  
Climate Crisis

There are two contents of this article. The first is briefly to review the experiment research on the catalysis mechanism of Carbon Gasification Reaction-CGR(C+CO2=2CO) from 60s -90s. The results show that the catalytic phenomenon is physical phenomenon rather than chemical, and the catalyst does not participate in the chemical reaction. The catalytic activity and selectivity of catalyst are related to the electronegativity or energy level of the catalyst. The second is to clarify the applications of CGR for save mankind. The lime is first proposed to capture CO2 in flue gas of power plant. The lime can be recycled. The coal is used to convert CO2 from cement steel produce into CO, producing both energy and lime and iron. The capture CO2 is used to treat waste such as firewood and plastic, eliminate white pollution. The author considers that using the CGR which has been used for a long time can solve the three problems which people worry about: energy exhaustion, environmental pollution and climate crisis.

Introducing a Novel Reactor Concept: Indirectly Fired Integrated Gasification and Steam Generation System

2010 ◽  
Author(s):  
Monem Alyaser ◽  
Rory Monaghan ◽  
Abdlmonem Beitelmal ◽  
Drazen Fabris
Keyword(s):  
Heat Exchanger ◽  
Plug Flow ◽  
Reaction Rates ◽  
Reacting Flows ◽  
Steam Gasification ◽  
Reacting Flow ◽  
Steam Generation ◽  
Integrated Gasification ◽  
Gasification Reaction ◽  
Char Conversion

This paper introduces a novel gasification reactor that uses steam gasification of carbonaceous feedstock by indirectly heating the reacting flow through a high temperature heat exchanger without the need for partial combustion with oxygen. It demonstrates the importance of gasification as a method for increasing power plant efficiency and reducing emissions. This paper also describes the computational model created to model this novel gasifier and the results of the model that illustrates the efficiency and purity advantages of the new gasifier. The reactor was modeled as a 1D counter-reacting flows heat exchanger, using the effectiveness-number of transfer units (ε-Ntu) method. The heating flow was assumed to be fully combusted at the inlet. The gasification stream was modeled as a plug flow, where the reaction is kinetically controlled. A simplified version of the Random Pore Model (RPM) was used to predict the char consumption. The results indicate that the gasification of coal with steam without partial combustion with oxygen using this new concept is feasible. The gasification reaction rates are found to be slow at temperatures less than 1200°C, but most of the char conversion, which reached about almost 100% completion, occurred at higher than 1200°C.

scholarly journals Characterizations of the hot blast furnace slag on coal gasification reaction

2016 ◽  
Vol 98 ◽  
pp. 936-943 ◽  
Author(s):  
Wenjun Duan ◽  
Qingbo Yu ◽  
Junxiang Liu ◽  
Limin Hou ◽  
Huaqing Xie ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Coal Gasification ◽  
Hot Blast ◽  
Gasification Reaction ◽  
Furnace Slag

Carbothermic Reduction of Zinc Ferrite by Microwave Heating

2013 ◽  
Vol 32 (5) ◽  
pp. 485-491 ◽  
Author(s):  
Xin Wang ◽  
Shao-Hua Ju ◽  
C. Srinivasakannan ◽  
Da-Jin Yang ◽  
Jin-Hui Peng
Keyword(s):  
Particle Size ◽  
Microwave Power ◽  
Carbothermic Reduction ◽  
Decomposition Temperature ◽  
Mechanism Of Formation ◽  
Carbon Gasification ◽  
Gasification Reaction ◽  
Kinetics Of ◽  
Hsc Chemistry ◽  
Equilibrium Calculations

AbstractThe kinetics of carbothermic reduction of ZnFe2O4 in the temperature range 823–1223 K, was investigated in a microwave reactor. The mechanism of formation of ZnO and Fe3O4/FeO by decomposition of ZnFe2O4 was explained using the equilibrium calculations and thermodynamics analysis using HSC chemistry software 6.0. In addition the effect of parameters such as the decomposition temperature, C/ZnFe2O4 ratio, particle size and microwave power were assessed on the decomposition kinetics. Zn recovery as high as 98.83% could be achieved at a decomposition temperature of 1023 K, C/ZnFe2O4 ratio of 1:3, particle size of +74–61 µm and microwave power of 1200 W. The kinetics of decomposition was found to be carbon gasification reaction controlled, with the activation energy of 39.21 kJ/mol.

scholarly journals Development of new technology for coal gasification purification and research on the formation mechanism of pollutants

2021 ◽  
Author(s):  
Shu Zheng ◽  
Yixiang Shi ◽  
Zhiqi Wang ◽  
Pengjie Wang ◽  
Gang Liu ◽  
...  
Keyword(s):  
Power Generation ◽  
Fuel Cell ◽  
Power Systems ◽  
Formation Mechanism ◽  
Transition Metal Oxides ◽  
Coal Gasification ◽  
Removal Rate ◽  
New Technology ◽  
Coal Particles ◽  
Gasification Reaction

Abstract Coal-fired power generation is the main source of CO2 emission in China. To solve the problems of declined efficiency and increased costs caused by CO2 capture in coal-fired power systems, an integrated gasification fuel cell (IGFC) power generation technology was developed. The interaction mechanisms among coal gasification and purification, fuel cell and other components are further studied for IGFCs. Towards the direction of coal gasification and purification, we studied gasification reaction characteristics of ultrafine coal particles, ash melting characteristics and their effects on coal gasification reactions, the formation mechanism of pollutants. We further develop an elevated temperature/pressure swing adsorption rig for simultaneous H2S and CO2 removals. The results show the validity of the Miura-Maki model to describe the gasification of Shenhua bituminous coal with a good fit between the predicted DTG curves and experimental data. The designed 8-6-1 cycle procedure can effectively remove CO2 and H2S simultaneously with removal rate over 99.9%. In addition, transition metal oxides used as mercury removal adsorbents in coal gasified syngas were shown with great potential. The techniques presented in this paper can improve the gasification efficiency and reduce the formation of pollutants in IGFCs.

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