Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Exhaust gas processing and utilization

The Effect of Composite Additive on the SNCR

Author HuangXia
Tutor WuShaoHua
School Harbin Institute of Technology
Course Thermal Power Engineering
Keywords SNCR NO_x additive chemical mechanism sensitivity analysis
CLC X701
Type Master's thesis
Year 2008
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NOx emitting from coal combustion in power plant is one of major sources of air pollution which is subject to the attention of all of the world. The effective post combustion NOx reduction technologies are the selective catalytic reduction (SCR) and the selective non-catalytic reduction (SNCR). The SNCR is a more economical techonoly because of none catalyst needed, but the limited optimum reaction temperature window and the lower NOx reduction efficiency inhibit the application. This paper studies the influence of single additives and compound additives on SNCR denitrification reaction process by numerical simulation and test drawing on the predecessors.Based on the SNCR actual reaction process and the characteristics of ideal continuous flow reactor model, this paper chooses the Plug Flow Reactor. Compared the mechanisms, this paper selects the most suitable mechanism SKG03 as the basis of simulated.Firstly it simulates the effect of NH3/NOx molar ratio, NOx initial concentration and residence time on the SNCR denitrification reaction with no additive using ChemKin4.0 software. Secondly it simulates the inpact of the single additive CH4, CO or H2, which abtains the single additives can reduce the SNCR optimum reaction temperature window which is not able to widening at all and the remaining NH3 rapid declines at the low-temperature, but the maximum denitrification efficiencies decrease at some conditions. Then compared to the single, the two component additives: CH4 and CO、CO and H2、CH4 and H2 can reduce the optimum reaction temperature window further. It’s knowed the effect of H2 is the largest ,CH4 is the follower, CO is the least.Because the single additives which are often used for SNCR are included in the coke oven gas, the water gas, the biomass gas etc. which have extensive sources, practicality and economics, this paper discusses the SNCR reaction adding the gas.It is analysised the test and simulation results and gets the trend of the test line is silimar to the simulation with none additive and the test lines can authenticate the additive can decrease the SNCR optimum reaction temperature window with the single CH4 or CO and the coke oven gas or the water gas.Finally, this paper finds the most important reactions through NO sensitivity analysis at the condition of adding single CH4、CO、H2 or gas compound additives.

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