Yongping Yang

Gaseous emissions from the combustion of a waste mixture containing a high concentration of N2O.

This paper is focused on reducing the emissions from the combustion of a waste mixture containing a high concentration of N2O. A rate model and an equilibrium model were used to predict gaseous emissions from the combustion of the mixture. The influences of temperature and methane were considered, and the experimental research was carried out in a tabular reactor and a pilot combustion furnace. The results showed that for the waste mixture, the combustion temperature should be in the range of 950-1100 degrees C and the gas residence time should be 2s or higher to reduce emissions.

Product gas combustion in fluidized bed for N 2 O reduction

The experimental research on removing N2O with biomass gas was carried out in a small-fluidized bed reactor tube. The decomposition rate of N2O and the production rate of NO impacted by reaction temperature, residence time, reburning position, rate of fuel, initial oxygen content of flue gas and the height of material bed were researched. The results showed that the decomposition rate of N2O was more than 99% with some biomass gas and residence time was 0.32 sec in the reducing zone. The decomposition rate of N2O was increased with the increasing of the distance from air distributor, was decreased with the increasing of the initial oxygen fraction, and was in direct proportion to the height of material bed and the fraction of ejected biomass gas.

Reburning Characteristics Research of Combustible Gas in CFB

Experimental research on the characteristics of co-combustion coal and combustible gas has been carried out. The influence of nozzle position and combustible gas reburning ratio on N2O and NO removal rate were carried out at CFB experimental platform. It is found that N2O removal rate achieved a maximum value when the reburning gas was injected into furnace from nozzle C with a height-diameter ratio of 8.3, and the NO removal rate is about 50%; When the combustible gas were injected into furnace from nozzle C, the N2O removal rate kept increasing with the increase of reburning ratio (Rm), which can reach 99% when the Rm value is 10.5%. In addition, the NO removal rate is increasd after the first reduction with the increase of Rm, when the rate is about 39% with Rm is 10.5%.

The interaction between HCl and Fe 2 O 3 during the chemical looping combustion of MSW

In order to avoid dioxin emission from municipal solid waste combustion (MSW), chemical looping combustion was considered. The interaction between HCl and Fe2O3 was studied in this paper and experiments were carried out in a fixed bed reactor. Chlorine was measured by methyl orange spectrophotometric method. The intermediate reactions were calculated with standard Gibbs free energy and reaction equilibrium constants. The result showed that: when Fe2O3 is used as oxygen carrier, the conversion of HCl to chlorine can be suppressed, thus reduce Dioxin emission.

Modeling the gasification based biomass co-firing in a 600MW pulverized coal boiler

Gasification based biomass co-firing was an attractive technology for utilizing biomass as an additional fuel in utility boilers. Compared to directly co-firing biomass and coal, it showed following benefits: (1) avoiding biomass delivery into the boiler, (2) reduced boiler slagging, (3) avoiding altered ash characteristics. In co-firing demonstration project, higher percentage of biomass gas for co-firing was expected. But the effect of percentage of biomass gas on combustion efficiency, boiler efficiency and pollutant emission was not clear. In the study, numerical simulation of co-firing producer gas from biomass gasification and coal in a 600MWe tangential PC boiler was carried out with CFD method. Combustion behavior and pollutant emission for the coal fired only case and six co-firing cases were compared. The results showed that The effect of co-firing on combustion efficiency was slight, the reduction of NOx emission can be achieved. The NO removal rate was between 45% and 71%. In addition, slagging can be reduced for the temperature decreasing. And the convection heat transfer area should be increased or the biomass gas should be limited to a low percentage to achieve higher boiler efficiency.

Experimental research on gas-solid flow in a dual fluidized bed

Chemical-looping combustion (CLC) is a new method for the combustion of fuel gas with inherent separation of carbon dioxide. The cold interconnected fluidized beds (Ø100) were set-up for the hot model design in this work. The pressure drop of both air reactor (AR) and fuel reactor (FR) were measured and used for CLC system design. The effects of superficial gas velocity on pressure distribution of both AR and FR were presented. Before fluidization, the pressure drop characteristics of two reactors in interconnected dual fluidized bed for CLC sharply increase with the increasing of gas velocity, which just similar to that of conventional circulating fluidized bed. And after fluidization, the pressure drop of two reactors in dual fluidized bed decreased with the increasing gas velocity. It could be seen that uFR must be increased with an enhancive uAR value to ensure exchange of bed material, and the higher of the gas velocity, the more material could be exchanged.

Modeling of straw lignin molecule

The pyrolysis of straw was one of the important ways for biomass utilization. Chemical structure of straw lignin had great impact on the decomposition process of straw. In this paper, lignin molecule was modeled with an average structure method and optimized with Density Functional Theory (DFT). The most stable conformations of structural units and structural model of straw lignin were obtained by the optimizing calculation.

Sludge auto-thermal drying and incineration generation simulation with ASPEN PLUS

Based on the ASPEN PLUS simulation platform, drying and fluidized bed incineration process of mechanically dewatered sludge with 70% moisture content was simulated. Compared with other calculation methods, this method could achieve sludge incineration simulation rapidly, and could further optimize the technology or adjust the stream parameter conveniently. The results obtained showed that: The heat of flue gas (about 300°C–400°C) could be used to dry the initial sludge, and the moisture content of sludge could be reduced to 60% without additional energy and the generation efficiency increased with the decrease of moisture content from 70% to 60%.

Mechanism Study on N2O Reduced with Biomass Gas

The reduction of N2O by adding biomass gas as reburning fuel is studied on a small-scale vertical reactor tube and experimental results are analyzed using the theory of chemical kinetics. The result showed that for the flue gas containing a certain concentration of N2O, when the biomass gas contained H2, CH4, CO and CO2 was used, the reburning fuel ratio should be more than 1.4%. The decomposition of N2O is caused by free radicals, including H and OH in the process.

Kinetics simulation of N 2 O reduced with combustible gas CO

The reduction machinism and kinetics characteristic of the reaction of carbon oxide (CO) and Nnitrous oxide (N2O), which contained the influence of reaction time on the reactants and products, were studied in the paper. The radical reaction of CO and N2O was assumped in a ideal reactor with a high temperature and a constant pressure, and was analyzed with chemical reaction kinetics theory. The result showed that the reduction effect of CO on N2O could be forecasted and simulated by the model built under certain temperature and pressure, of which the mechnism contained 3 elements, 12 components and 26 reactions.