CAS researchers have successfully carried out a 1.0MPa, long period (up to 72 hours) high pressure testing on a semi-industrial platform of pressurized ash agglomerating fluidized bed (AFB) coal gasification, which was jointly developed by the CAS Institute of Coal Chemistry (ICC) and Jincheng Anthracite Mining Group, both being in north China's Shanxi Province.
As China's energy portfolio is characterized with abundance in coal and deficiency in petroleum and natural gas, the technology for coal gasification has widely been used in various sectors, ranging from chemical engineering, metallurgy to the urban gas supply, providing a large amount of feedstock and fuel gases. With the rapid social and economic growth, advanced large-scale gasification technology featuring low energy consumption, wide adaptability and environmental friendliness will become a development mainstream.
ICC researchers have been carried out studies on gasification technology as early as in 1980, and developed ash agglomerating fluidized bed (AFB) process for coal gasification. The process, which has filed for an invention patent, includes technological steps such as coal feeding, gas agents distribution, gasifier controlling, dust removal and waste heat recovery. Its apparatus is composed of units for fluidized-bed gasifier, agglomerated ash separation and discharge, fly ash circulation and waste heat recovery. Its' most important feature is adapting to use different coal types with high ash content (>25.% wt) and high ash fusion temperature (>1500ºC).
Based on the past 20 years of strenuous studies, large-scale AFB gasifier developed by ICC researchers has been successfully run or will be run for syngas (the mixture of CO and H2) production in several fertilizer plants or methanol plants. A wide variety of coal with high ash content and ash fusion temperature had been used. In order to improve gasification efficiency, capacity, and to reduce the down-stream compressing consumption, a Shanxi Coal Gasification Engineering Research Center has been set up jointly by ICC and the Jincheng Anthracite Mining Group to develop high pressurized AFB coal gasification technology.
A pilot plant of pressurized AFB gasifier with a designed capacity under 3.0MPa was installed in 2006 and put in trial operation recently. During the test, all facilities were operating smoothly and have reached various preset indices, marking an R&D breakthrough of the technology.
The experiment shows that, with anthracite mined from Jincheng as its feedstock, the platform could process 2.5 tons of coal per hour (or 60 tons per day) under the operation temperature between 1020-1050ºC, with the carbon conversion rate reaching 87%, gas yield as many as 1.8Nm3 dry gas/kg coal, and content of effective gases (CO plus H2) up to 66%. The test indicates that the capacity of 1.0 MPa industrial scale unit (with 2.4 meter inside diameter) could be 600 tons of coal daily matched for a middle-sized methanol plants to synthesize NH3.
It is slated that the 3.0MPa testing will be done in 2008, providing strong technical support to the rapid development of large-scale coal-based chemical plants and poly-generation systems.
