Zhiguo Tang

Research on an Approach to High Temperature Flameless Combustion Technology of Biomass

In this paper the situation of biomass (straw) utilization technology is depicted. Besides, the present questions of biomass gasification, liquefaction along with direct combustion are analyzed. Biomass gasification and liquefaction are complex processes that not only increase the cost of investment, but also decrease the total available energy efficiency. The heat value of product of gasification and liquefaction is lower, and the technologies of steady running, elimination of tar and gas purification need to be improved. The direct combustion technology has obvious advantages of high efficiency and no second pollution of tar. However, the present direct combustion mode is restricted because of a series of problems. The combustion temperature is low, the ash is gathered, clinker is formed by the low melting ember, and granule is produced in the progress of combustion which can do harm to the health of person. Therefore it is important and difficult to study and invent the high efficient combustion technology of biomass containing much water in the direct combustion. Based on excess enthalpy combustion, a new biomass utilized technology is put forward to exploit biomass economically, safely, cosmically and at a high level. This new technology includes flameless combustion, slag tapping, staged combustion，excess enthalpy combustion and circulation of the exit gases. With these measures, highly efficiency and low pollutant emission will be realized.

Numerical simulation of a new two-stage dry feed gasifier for double-high coal

In order to study the characteristics of a new two-stage dry feed gasifier with multi underneath nozzles jetting tangentially, numerical simulation and analysis of the gasifier for high ash melting point pulverized coal was conducted based on Fluent. A comprehensive mathematical model for simulation of pulverized coal gasifier has been developed in this paper, chemical process was described with presumed PDF mode, a gasification look-up table was built to describe the relationship between mixture fraction and the scalars of temperature, species, et al. Body fitted hexahedron mesh was adopted and k-ε RNG turbulent model was used to make a closure for turbulence equations. Dispersed phase model (DPM) were employed to describe the coupling effect between gas phase and discrete phase, and Stochastic Tracking Method (STM) were used to track turbulent dispersion of char particles and to consider the turbulent disturbance effects on particle motion on gasification process. In addition, User Defined Functions (UDF) was used to mend heterogeneous gasification reactions model, including carbon with O2, H2O, CO2 and H2. The numerical simulation and analysis of the inner velocity, temperature and species concentrations of the two-stage entrained flow coal gasifier for high ash melting point pulverized coal shown that spatial gasification reactions can be achieved in the gasifier, inner temperature grads reduce remarkably and temperature field become more even, and the key gasification parameters, such as [O]/[C] atom ratio, steam/coal ratio, were optimized through simulation, will offer reference for the further research on the gasifier for high ash melting point pulverized coal.

A Comprehensive Heat-Equilibrium Analysis of Swiss-Roll Combustor and Its Thermal Energy Utilization System

With the background of the normal energy drying out, the utilization of low caloric value fuel is becoming more and more important. The Swiss-roll combustor is very applicable to low caloric value gas fuel. In order to make the combustor satisfied to combust the changing concentration low heat value gas fuel, the paper improves the conventional-scale Swiss-roll burner in which the SiC porous media, globar electric heating unit and heat extraction unit were added into the center. On this basis, the dynamic heat balance model of the whole system is built and the experimental research is also conducted. These are useful to solve the combustion zone drifting problem and provide important control parameters for design of the following control system. The results show that taking out the surplus heat which is determined by the gas fuel concentration and flow rate could make the combustion reaction zone in the center of the porous media.

Research on the Three Different Kinds of Technologies to Achieve Flameless Combustion and Their Applications

Flameless combustion was first to developed suppress thermal NOx formation and raise the efficiency of combustion. Now in further research, three different combustion technologies can be used to achieve flameless combustion those are high temperature air combustion (HTAC), normal temperature air combustion (NTAC) and oxy-fuel flameless combustion. This paper presents a description of the three different technologies, the development of their application in gaseous, liquefied and solid fuels combustion as well as their industrial applications at a research stage. These flameless combustion applied combustion technologies guarantees the uniform temperature distribution, fuel consumption reduction and productivity when applied, for example, to coal gasification, and to low calorific fuel combustion.

Discussion on Gasification of High Ash Melting Point Pulverized Coal Using Excess Enthalpy Combustion

The paper presents the principle and development of excess enthalpy combustion, and recommends that excess enthalpy combustion (high temperature air combustion or flameless combustion ) was applied to correlative researches such as combustion and gasification of solid fuel-pulverized coal. Based on the characteristics and gasification difficulty of coal in China, this paper also puts forward that Normal Temperature Air Flameless Combustion developed by our research team can be apply to gasification of high ash melting points coal. The feasibility and the key difficulty of this technology are analyzed from the effect factors of gasification process. and then draw a conclusion that the technology has the characteristics of a wide range of fuel applicability, low oxygen consumption, high heat value of syngas, the more active content (CO+H2) in syngas, the more high overall process efficiency and molten ash extracted swimmingly and completely. It is likely that the pulverized coal with high ash melting point will be gasified commendably using the technology.