In this paper, effect of gasification temperature and residence time on gasification characteristics of typical pulverized coals under atmosphere pressure were studied on a one-dimensional electric heating drop tube f...In this paper, effect of gasification temperature and residence time on gasification characteristics of typical pulverized coals under atmosphere pressure were studied on a one-dimensional electric heating drop tube furnace system to evaluate gasification characteristics of pulverized coal at medium temperature. The results show that the gasification rate increases with the raising of the gasification temperature under the temperature among 1150℃and1450℃, and as the temperature is above1350℃, the increasing rate become slower. Cold gas efficiency?and?carbon conversion meet the maximum value when the temperature approaches the ash fusion point of coal. With the further rise of the temperature, ash on the surface of the char starts to be melted,?the gasification reaction rate decreases, due to the hindrance of the effective contact between coal char and gasification agent. The gasification efficiency would become steady when the residence time exceeds 8s.展开更多
The current studies on power plant technologies suggest that Integrated Gasification Combined Cycle(IGCC)systems are an effective and economic CO_(2) capture technology pathway.In addition,the system in conventional c...The current studies on power plant technologies suggest that Integrated Gasification Combined Cycle(IGCC)systems are an effective and economic CO_(2) capture technology pathway.In addition,the system in conventional configuration has the advantage of being more“CO_(2) capture ready”than other technologies.Pulverized coal boilers(PC)have,however,proven high technical performance attributes and are economically often most practical technologies.To highlight the pros and cons of both technologies in connection with an integrated CO_(2) capture,a comparative analysis of ultrasupercritical PC and IGCC is carried out in this paper.The technical design,the mass and energy balance and the system optimizations are implemented by using the ECLIPSE chemical plant simulation software package.Built upon these technologies,the CO_(2) capture facilities are incorporated within the system.The most appropriate CO_(2) capture systems for the PC system selected for this work are the oxy-fuel system and the postcombustion scheme using Monoethanolamine solvent scrubber column(MEA).The IGCC systems are designed in two configurations:Water gas shift reactor and Selexol-based separation.Both options generate CO_(2)-rich and hydrogen rich-gas streams.Following the comparative analysis of the technical performance attributes of the above cycles,the economic assessment is carried out using the economic toolbox of ECLIPSE is seamlessly connected to the results of the mass and energy balance as well as the utility usages.The total cost assessment is implemented according to the stepcount exponential costing method using the dominant factors and/or a combination of parameters.Subsequently,based on a set of assumptions,the net present value estimation is implemented to calculate the breakeven electricity selling prices and the CO_(2) avoidance cost.展开更多
In energy industries, it is always of difficulty to produce high heat value（HHV） gas continuously using pulverized coal. In this paper, a new type furnace for partitioned alternative gasification using pulverized co...In energy industries, it is always of difficulty to produce high heat value（HHV） gas continuously using pulverized coal. In this paper, a new type furnace for partitioned alternative gasification using pulverized coal is developed, in which the oxidation and reduction reaction occur alternatively with the dropping of pulverized coal and finally HHV gas could be continuously obtained at the reduction zone exit and low heat value（LHV） gas at the oxidation zone exit. Furthermore, the gasification characteristics and their factors in furnace are numerically simulated under two dimensional model with a self-coded program, based on heat, mass and energy transfer as well as reaction principles. It is found that the producing rate of HHV gas is 1.10Nm3/kg with heat value of ll.72MJ/Nm3, how- ever, that of LHV gas is 2.58Nm3/kg with heat value of 5.30MJ/Nm3, and the coal gas efficiency is 81.16% under optimized conditions.展开更多
文摘In this paper, effect of gasification temperature and residence time on gasification characteristics of typical pulverized coals under atmosphere pressure were studied on a one-dimensional electric heating drop tube furnace system to evaluate gasification characteristics of pulverized coal at medium temperature. The results show that the gasification rate increases with the raising of the gasification temperature under the temperature among 1150℃and1450℃, and as the temperature is above1350℃, the increasing rate become slower. Cold gas efficiency?and?carbon conversion meet the maximum value when the temperature approaches the ash fusion point of coal. With the further rise of the temperature, ash on the surface of the char starts to be melted,?the gasification reaction rate decreases, due to the hindrance of the effective contact between coal char and gasification agent. The gasification efficiency would become steady when the residence time exceeds 8s.
文摘The current studies on power plant technologies suggest that Integrated Gasification Combined Cycle(IGCC)systems are an effective and economic CO_(2) capture technology pathway.In addition,the system in conventional configuration has the advantage of being more“CO_(2) capture ready”than other technologies.Pulverized coal boilers(PC)have,however,proven high technical performance attributes and are economically often most practical technologies.To highlight the pros and cons of both technologies in connection with an integrated CO_(2) capture,a comparative analysis of ultrasupercritical PC and IGCC is carried out in this paper.The technical design,the mass and energy balance and the system optimizations are implemented by using the ECLIPSE chemical plant simulation software package.Built upon these technologies,the CO_(2) capture facilities are incorporated within the system.The most appropriate CO_(2) capture systems for the PC system selected for this work are the oxy-fuel system and the postcombustion scheme using Monoethanolamine solvent scrubber column(MEA).The IGCC systems are designed in two configurations:Water gas shift reactor and Selexol-based separation.Both options generate CO_(2)-rich and hydrogen rich-gas streams.Following the comparative analysis of the technical performance attributes of the above cycles,the economic assessment is carried out using the economic toolbox of ECLIPSE is seamlessly connected to the results of the mass and energy balance as well as the utility usages.The total cost assessment is implemented according to the stepcount exponential costing method using the dominant factors and/or a combination of parameters.Subsequently,based on a set of assumptions,the net present value estimation is implemented to calculate the breakeven electricity selling prices and the CO_(2) avoidance cost.
文摘In energy industries, it is always of difficulty to produce high heat value（HHV） gas continuously using pulverized coal. In this paper, a new type furnace for partitioned alternative gasification using pulverized coal is developed, in which the oxidation and reduction reaction occur alternatively with the dropping of pulverized coal and finally HHV gas could be continuously obtained at the reduction zone exit and low heat value（LHV） gas at the oxidation zone exit. Furthermore, the gasification characteristics and their factors in furnace are numerically simulated under two dimensional model with a self-coded program, based on heat, mass and energy transfer as well as reaction principles. It is found that the producing rate of HHV gas is 1.10Nm3/kg with heat value of ll.72MJ/Nm3, how- ever, that of LHV gas is 2.58Nm3/kg with heat value of 5.30MJ/Nm3, and the coal gas efficiency is 81.16% under optimized conditions.
