Jun Inumaru

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

Study on char deposition characteristics on the heat exchanger tube in a coal gasifier: relationship between char formation and deposition characteristics

Abstract In a coal gasifier and heat exchanger, adhered and deposited ash and char inhibit heat transfer making the stable operation of the gasifier difficult. Since heat transfer performance of the heat exchanger directly affects the output of Integrated Coal Gasification Combined Cycle plants, it is important to understand the effect of char on the characteristics of adhesion and deposition on the heat exchanger tube beforehand. However, very few studies have been conducted concerning the relationship between chars property and its adherability, which varies depending on the coal type and the operating conditions. In this study, we first conducted an analysis of the characteristics of heat transfer in the heat exchanger of the pilot plant gasifier to understand the effects of the properties of the char on the heat transfer in the heat exchanger. Using a bench-scale gasifier at CRIEPI, a transformation of the char morphology took place as the gasification reaction progressed. In the experiment, char from three distinct coal types was made to adhere on a plate and then allowed to re-entrain, so that the inter-particle adhesion strength of the char could be measured. Using the char from the same coals, deposition experiments on a horizontal tube placed in a drop tube furnace were also conducted to examine the mechanism of char adhesion on the heat exchanger tube.

Development of Oxy-Fuel IGCC System With CO2 Recirculation for CO2 Capture: Experimental Examination on Effect of Gasification Reaction Promotion by CO2 Enriched Using Bench Scale Gasifier Facility

To cope with global warming problem, utility companies are required to reduce CO2 emission from pulverized coal fired power plants. Japanese utility companies are advancing various measures to improve plant thermal efficiency and to promote utilization of biomass as a fuel. In Europe and America, CO2 capture and storage (CCS) technology is regarded as one effective approach, and various demonstration projects are planned all over the world. However, the introduction of conventional CO2 capture system to power station causes a decrease in the plant thermal efficiency and an increase in the power generating cost. In this reason, it is necessary to develop a new power generating system with high thermal efficiency. Therefore, Central Research Institute of Electric Power Industry (CRIEPI) proposed an innovative integrated coal gasification combined cycle power generating system (IGCC) with CO2 capture whose plant thermal efficiency is very high, and is working on the research and development of the new system. This is a system to combine a new oxygen-CO2 blown coal gasifier in that captured CO2 is used with the closed gas turbine in which coal gas from the gasifier is burned with the gas mixed oxygen and recycled exhaust CO2 . The system has the following features. The gasification performances improve greatly. The processes of concentrating and separating CO2 are unnecessary. It is estimated that the carbon conversion efficiency (CCE) and the cold gas efficiency (CGE) in oxygen-CO2 blown gasifier improve more than conventional oxygen blown gasifiers by the effect of the gasification reaction promotion of CO2 by gasifying coal with oxygen and CO2 . As a result, the gasifier and the char recycling system can make to compact, and the equipment cost can be reduced. This paper reports on examination of CO2 promotion effect on the gasification performances by gasification test using a bench scale gasifier facility.Copyright

Numerical Simulation of Coal Ash Particle Behavior in Entrained Flow Coal Gasifier

The objective of this study is to develop an evaluation tool for a design and performance of a coal gasifier by a numerical simulation technique. In the present paper, a gas-particle two phase reacting flow calculation is carried out for a prediction of phenomena in an entrained flow coal gasifier due to coal and ash particles behavior, such as ash deposition on the wall. A transportation of the coal particles is modeled via a Lagrangian manner. The ash particle adhesion on the wall of the gasifier is discriminated by an empirical ash adhesion model based on a liquid phase fraction concept in the ash particle. The gas phase properties are calculated by three dimensional time-mean Eulerian conservation equations. The turbulent flow field is determined by the k-e two equations model. Radiative heat transfer is calculated by the discrete transfer radiation method. Coal gasification reaction model is composed of three chemical processes in the current model: a pyrolysis, a char gasification and gas phase reactions. 2 tons/day (t/d) air-blown pressurized entrained flow coal gasifier, which has been constructed and operated by Central Research Institute of Electric Power Industry (CRIEPI) was targetted. As a result, a relationship between an operating condition (air ratio) of the gasifier and the gasifier performance is presented. The trend of the ash deposition on the gasifier inner wall is also presented. Comparison between the computational and the experimental results shows that the most feature of the gasifier performance and the profile of the ash deposition have been captured by the present model. It was confirmed that the numerical simulation approach is very useful for the assessment of gasifier performance and operation support.Copyright

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.

Development of a new measurement method of velocity vectors using a high speed VTR.

A new measurement method of two-dimensional velocity vectors was developed using a high speed VTR and image processing system. The visualized turbulent flow with tracer is tracked by the high speed camera and the image data is sent to the image processor. The mean velocity vectors are automatically obtained by the cross-correlation calculation of tracer concentration signals between two points on the image. Applicability of the method was investigated in the velocity vectors measurements of an axisymmetric turbulent free jet and normal impingement of the jct. As a result, it was found that the measurement of higher velocity was possible by reducing data sampling interval Δt. And the measured velocity vectors of the impinging jet showed a good agreement with the other calculation and experimental results.