Defu Che

Pyridine and pyrrole oxidation under oxy-fuel conditions

ABSTRACT In this article, a study on pyridine and pyrrole oxidation under oxy-fuel conditions has been carried out. The experimental results indicate that when the temperature is above 800°C, concentration of N2O in the offgas quickly destructs mainly into N2 with the increase of temperature. Both NO and N2O concentrations can be enlarged, obviously due to the increase of oxygen concentration. In addition, the effect of gas atmosphere on pyrrole oxidation is quite different from that on pyridine oxidation. Introduction of high content CO2 in oxy-fuel combustion can lead to a certain migration change of fuel nitrogen.

Adsorption of Alkali Metal by High-temperature Acid-treated Coal Char

Gas phase alkali metal compounds contribute to fouling, slagging, corrosion, and agglomeration problems in a gasifier system. Vapors of alkali metal compounds can be removed by quench of gases and the adsorption of char/ash in a chemical quench process. In the present study, an experimental investigation was performed to describe the properties of alkali vapor adsorption by the high-temperature coal char with NaCl as the alkali metal model compound. The experimental results may be helpful to control the alkali metal corrosion in coal gasifier.

A study on air-cooling waste heat recovery from molten slag of slag-tap boilers

For a better utilization of Zhundong coals which have high fouling and slagging tendency, the slag-tap boiler has attracted much attention. To avoid the high sensible heat loss of discharged molten slag, an air-cooling waste heat recovery system is proposed. Energy and economic analyses are conducted to investigate the effectiveness of heating the desulfurized flue gas by hot air and the influences of partially substituting the secondary air by hot air on heat transfer of air preheater and thermal efficiency of boiler. A case study is performed by referring to a typical 50 MW cyclone boiler with nine types of low fusion temperature coals. The results show that for coals with low ash content, the temperature increment of desulfurized flue gas can be over 7 ℃. While for coals with high ash content, the flue gas temperature can be heated to more than 70 ℃, and the surplus hot air can be sent to the furnace. When the hot air is introduced to partially substitute the secondary air, an instantaneous impact on the air preheater will give rise to a decrement of quantity of heat transferred and increments of temperatures of exit flue gas and hot secondary air. The variations of these thermodynamic parameters become smaller with increasing hot air temperature. After introduction of hot air, the thermal efficiency of boiler can increase, resulting in a decrease of fuel consumption rate. In addition, the heating surface area of air preheater can be reduced.

Comparative Study of Three Modes of Flue Gas Treatment for Power Plants

AbstractFlue gas treatment systems have been widely installed in power plants to recover the remaining energy from the exhaust flue gas and to address pollutant emissions by heating the cleaned flu...

A New Model Coupling Interface Tracking Methods and Two‐Fluid Model for Simulation of Incompressible Gas‐liquid Two‐Phase Flow

A model coupling two basic models, the model with interface tracking method and two‐fluid model, for simulation of incompressible gas‐liquid two‐phase flow is proposed. A united solution frame shared by the two basic models is built. In the shared solution frame, the Navier—Stokes equations of the two basic models can be dealt with in a uniform form. In the proposed model, there are three phases, which are divided not only by physics but also by the length scale of interface, including the liquid phase, the large‐length‐scale‐interface gas phase and the small‐length‐scale‐interface gas phase. The special treatment named by “void fraction redistribution” is adopted for the special grids which contain all three phases. Based on the united solution frame, MCBA—SIMPLE algorithm is used to solve the equations. Two problems are calculated to show that the proposed model has the merits of the two basic models.