Study And Application Of Mixture Of Chemical Exhaust And Low Nitrogen Combustion In Coal-fired Boilers

With the continuous development of national technology and industry,the demand for energy is also constantly increasing.Combined with national conditions,in order to reduce dependence on imported oil and other resources,coal-toliquid technology will have great development prospects.Every year,the coal-to-liquid process production of chemical plants is accompanied by a large number of by-products of high-calorific combustible tail gas,and the cost of recycling and reproducing coal chemical tail gas is too high.In response to the national call for energy conservation and emission reduction,it is necessary to make full use of this part of the secondary energy to improve economic efficiency and reduce environmental pollution.This article mainly takes the steam boiler of a thermal power workshop of a coal-to-liquid company in the north as the research object,and makes full use of the energy of coal chemical tail gas.The original boiler is retrofitted with chemical tail gas and combined with environmental protection requirements to carry out low-nitrogen combustion transformation.Try to get closer to the ultra-ultra-low nitrogen requirements as much as possible.This article introduces the gas produced by the coal chemical industry.Briefly introduce the composition and thermal properties of coal chemical gas.With reference to relevant research,briefly introduce the development status of domestic and foreign pulverized coal boilers co-firing gas.Summarize the possible problems of mixed gas burning before the transformation,including high temperature corrosion of the water wall after mixing,low temperature corrosion on the flue gas side,furnace load,and combustion product emissions.Combining the design and test coal types and the composition and properties of the coal chemical tail gas to be burned,the thermal calculation is performed to determine whether the influence is beneficial to the operation of the boiler.Relevant countermeasures were put forward for the adverse effects,the feasibility of this transformation was analyzed,and the theoretical basis for the transformation was provided.According to the relevant regulations,the performance requirement index for the transformation is formulated.Combining the design parameters of the original boiler and the characteristics of the test blended coal types,the boiler combustion system was modified.In order to meet the low nitrogen emission standards,the reform plan of "thick and thin combustion + air staging combustion" is adopted.Taking into account the effect of stabilizing combustion,the gas nozzle is placed in the middle of the furnace.Change the primary and secondary air volume and the size of the tangent circle,make the secondary air close to the wall to reduce the degree of coking.After the transformation was completed,a thermal adjustment test was carried out to determine the optimal air-to-coal ratio of the coal mill,as well as the optimal operating oxygen content and burnout damper opening under different load conditions.The test shows that the boiler’s coal-burning chemical tail gas is operating well,and the NO＿x emission is reduced under the premise of ensuring the boiler’s efficiency,which has achieved the purpose of transformation and created huge economic and environmental benefits.