Masami Ashizawa

Modelling and Simulation for Extra Heavy Oil Gasification on Entrained Flow Gasifier

The objective of this study is to develop an evaluation tool for a design and performance of an extra heavy oil gasifier by a numerical simulation technique. The modelling and the numerical simulation for the extra heavy oil gasification on the 2.4 tons/day entrained flow gasifier of CRIEPI are described in this paper. The gas phase properties are calculated by three dimensional time-mean Eulerian conservation equations, in addition to the k-e turbulence model. The fuel droplet behavior is modelled via a Lagrangian particle tracking approach. Four reaction processes are modelled in the present paper: atomization (micro-explosion), pyrolysis, coke gasification reaction, and gaseous phase reaction. As a result of the simulation, in a relationship between an oxygen ratio of the gasifier and the gasifier performance, such as heating value of the product gas, carbon conversion efficiency are presented. Distribution of gas temperature and gas composition in the gasifier, and the product gas composition are also presented. Comparison between the computational and the experimental results shows that the most features of the gasifier performance have been captured accurately by the computational procedure. The numerical simulation approach is very useful for the assessment of gasification performance, operation support and optimization of the gasifier design.© 2002 ASME

Upgrading of Wet Biomass by Oil Slurry Dewatering Process: Calcium Addition and Catalytic Activity for Gasification

A food processing waste with ca. 65wt％ moisture content has been subjected to dewatering treatment in kerosene with simultaneous calcium addition for gasification. Special attention was paid to the dispersion state of calcium and its catalytic activity for subsequent char gasification. Gasification reactivities of the chars were determined under isothermal conditions by thermogravimetry (TG) analysis. It was found that reactivities increased with Ca content up to a saturation level (SL) of about 2.7 wt％, above which the reactivities were approximate constant. The different catalytic activities of calcium were interpreted as being due to its dispersion state. For loading content lower than SL, Ca(OH)2 highly dispersed into matrix without crystallization, whereas the excess addition led to the formation of the crystallized structure, and therefore had no additional catalytic activity. The results of the present study indicated that oil slurry dehydrating process could provide an effective and practical catalyst loading procedure for biomass fuels with high water content.

Examination of Gasification Characteristics of Pressurized Two-Stage Entrained Flow Coal Gasifier. Comparison of Basic Performance with 2T/D and 200T/D Coal Gasifier.

The program for a 200T/D entrained flow coal gasification pilot plant was initiated in fiscal year 1986 and successfully finished fiscal year 1996. In this program, a two stage pressurized air-blown entrained flow coal gasifier was adopted, which CRIEPI and Mitsubishi Heavy Industry, Ltd, have developed jointly using a 2T/D bench scale P.D.U.. In the 200T/D pilot plant, domestic Taiheiyo coal, and Australian Moura, Warkworth coal were used for test runs. On the other hand, the commissioned tests of these 3 types of coals by NEDO/IGC Association have been carried out in CRIEPIs 2T/D coal gasifier, prior to the pilot plant operation. The research results obtained by the 2T/D gasifier were reflected in the operation of the pilot plant. From gasification test results with 2T/D and 200 T/D gasifiers, the gasification characteristics such as carbon conversion efficiency, cold gas efficiency and heat absorption rate to gasifier wall were evaluated.

CHARACTERISTICS OF A 2T/D PRESSURIZED TWO-STAGE ENTRAINED FLOW GOAL GASIFIER

Publisher Summary This chapter discusses the characteristics of a 2T/D pressurized two-stage entrained flow coal gasifier. It illustrates the flow scheme of the process development unit. The pulverized coal is pressurized in the lock hopper and transported to the gasifier by the primary air. The secondary air is fed into the combustor. The char contained in the product gas is collected by the cyclone and then transported to the combustor. The coal ash in the form of molten slag is discharged from the combustor, quenched and crushed in the ash hopper. The gasifier is a refractory lining structure (excluding watercooled walls of the combustor). The gasifier is operated at the pressure of 1.96 MPa and the coal feed rate is 100 kg/h (40 kg/h to the combustor). The coal feed rate and the primary air feed rate are unchanged, and the operating condition is changed by adjusting the secondary air feed rate into the combustor.