Seok Woo Chung

Considerations for the Design and Operation of Pilot-Scale Coal Gasifiers

Although there are many successful commercial coal gasifiers, the basic form and concept have not been improved for the last 20 years or so. Details on the design and operation for the commercial coal gasifiers are closely guarded as proprietary information. Considering the recent technology jump in CFD and monitoring systems, at least some coal gasifiers should come out as a more revolutionary style. Especially its important to test the novel gasifier types when the gasification has widened the application scope in environmental and biomass areas. Many research ideas should have a chance to design and test in the more realistic conditions of high pressure and high temperature with molten slags. This chapter wants to give an introduction and practical considerations to design and operate the bench scale to pilot scale gasifiers at the actual coal gasification conditions.

Accident Cases and Safety Issues in Gasification Plants

Institute for Advance Engineering in Korea has developed and tested the pilot-scale gasifiers since 1994 and has experienced several accidents and has solved safety issues during the last two decades. Actual accident cases are discussed with the inherent safety issues related to syngas facilities, specifically on the safety/toxicity issues related to syngas and syngas-related explosion. In addition, suggestions for the safe operation in gasification plants are summarized.

Pneumatic transport characteristics of coarse size pulverized coal for the application of fast circulating fluidized bed gasification

The pneumatic transport characteristics of pulverized coal with very coarse grain size were investigated, especially related to fast circulating fluidized bed gasifier. The lock hopper system was used along with the top discharge blow tank technology to examine the transportation characteristics of pulverized coal. The most important factors among the pulverized coal transportation properties were mass flow rate of pulverized coal and the solid loading ratio, which changed with the amount of fluidization nitrogen and differential pressure between injection hopper and gasifier. The mass flow rate of the pulverized coal and the solid loading ratio were linearly proportional to changes in differential pressure, and were inversely proportional to changes in the amount of fluidization nitrogen. In the case of extended transport line, similar feeding characteristics were obtained by increasing the differential pressure while the level of fluidization nitrogen was kept constant. Pressure losses were observed with changes in the mass flow rate of pulverized coal, solid loading ratio, and the transport gas density in horizontal and vertical, both upward and downward, straight pipelines and at bends. Characteristics of pressure losses under various operating conditions were correlated with the nondimensional numbers such as the Reynolds number, Froude number, solid/gas density ratio, and solid loading ratio. Such correlations were reasonably consistent with the experimental results.