Research On The Performance Of NO_x Adsorbent And Its Removal Equipment

The NO_x emitted from the flue gas of coal-fired boilers triggers a series of environmental problems including smog,acid rain and photochemical smog,which seriously threaten human health.Aiming at the problems of low removal efficiency of multi-component gas,easy secondary pollution and easy poisoning of complex components in flue gas,the existing flue gas denitration technology proposes a method of adsorption,desorption and concentration.The removal method removes NOx from the simulated boiler flue gas.In this paper,the existing polyacrylonitrile activated carbon fiber felt is used as raw material,and the activated carbon fiber sample after pretreatment and nitric acid modification is used as the adsorbent of nitrogen oxide,and the activated carbon fiber sample is measured by the specific surface area tester and Boehm titration method.Characterization of physical and chemical adsorption properties;firstly,the effects of different treatment methods,adsorption temperature,O₂concentration and flue gas flow rate on NO adsorption efficiency of activated carbon fibers were studied by means of laboratory gas distribution;then adsorption under optimal adsorption conditions,the desorption experiment was carried out to study the effect of multiple desorption on the adsorption capacity of activated carbon fiber.Secondly,the flow field calculation module and multi-component concentration field calculation module in COMSOL software were used.The numerical simulation of the physical adsorption of NO by activated carbon fiber was carried out.Finally,based on the above experimental study,a set of flue gas denitration system was designed with the actual coal-fired boiler as an example,and the actual adsorbent dosage and its arrangement were calculated.The research results are as follows:?1?Under the N₂ environment,the activated carbon fiber modified by nitric acid increased the oxygen-containing functional group on the surface,which promoted the chemical adsorption of NO by ACF-AR.The adsorption efficiency of ACF-AR to NO at150? was 19.6%.With the increase of temperature,the adsorption efficiency of NO by ACF-AR increased first and then decreased,and the optimum adsorption temperature was 150?.The presence of O₂ was beneficial to the adsorption of NO by activated carbon fiber.When the concentration of O₂ reached 8%,The adsorption efficiency of NO by activated carbon fiber is almost unchanged.At this time,the adsorption efficiency is 42.5%.The flow rate of flue gas has certain influence on the adsorption of NO by activated carbon fiber.The larger the flow rate,the more unfavorable the adsorption of NO by activated carbon fiber.When the adsorption conditions were 150?,O₂ concentration 8%,and flue gas flow rate 0.038 m/s,the adsorption efficiency of activated carbon fiber to NO was42.5%.?2?The desorption experiment of the activated carbon fiber after adsorption was carried out,and the optimum desorption temperature was 300? by TG analysis.The adsorption capacity of the activated carbon fiber in the adsorption-desorption cycle experiment decreased continuously with the increase of the number of cycles.And the decreasing trend is gradually decreasing,eventually reaching 4.2 mg NO/g ACF.?3?In the simulation process,the effects of adsorption temperature,O₂ concentration and gas flow rate on the adsorption of NO on activated carbon fibers were also considered.The conclusions obtained were basically consistent with the experimental results:the higher the temperature,the O₂ concentration was 8%,and the gas flow rate was smaller.The adsorption efficiency of activated carbon fiber for NO is higher.?4?Taking the actual coal-fired boiler with a volume of 12000 Nm³/h as an example,it is calculated that the adsorption cycle is 30 days,the amount of activated carbon fiber is required to be 1174 kg,and the concentration of nitrogen oxides in the final emission to the environment is 80 mg/m³ is increased to 97.5 mg/m³,meeting the nitrogen oxide emission standards set by the Ministry of Environmental Protection.