Influence Of Syngas Spray Chilling On Heat Transfer Process In The Fire Tube Waste Heat Boiler

Fire-tube waste heat boiler is the core equipment of gaseous hydrocarbon non-catalytic partial oxidation process in which methane is converted into syngas(CO+H2)and then the syngas is used to make a wide spectrum of hydrocarbons or alcohols.In the project,fire tube waste heat boiler often has problems such as over-temperature and tube damage.In order to solve these problems,this paper proposes a cooling scheme in front of the waste heat boiler,which spray cooling before high temperature syngas enters the waste heat boiler,and carries out process analysis and simulation study.The main contents are summarized as follows:(1)A droplet evaporation model under high temperature airflow is established.The effects of droplet size,droplet temperature,droplet velocity and ambient temperature on evaporation time are investigated.The time of droplet evaporation under different conditions is determined to ensure that droplets can be completely evaporated in limited space and time,so as to lay a foundation for the later spray cooling scheme in the tube.(2)Based on the operating parameters of industrial installation,the computational fluid dynamics is adopt to research the spray chilling process of high temperature syngas in the tube.The distribution of flow field and temperature field in the pipeline are calculated by cold simulation and hot simulation respectively.Finally,the best solution is determined by comparing the flow field distribution and temperature field distribution under different nozzle parameters and cooling water flow.(3)Flow and heat transfer model is set up for the tube plate cooling chamber of the fire-tube waste heat boiler.The tube wall temperature distribution of the chamber before and after spray cooling is compared.It is shown that the spray cooling scheme has a significant cooling effect.The thermal stress analysis method is used to calculate the maximum thermal stress distribution at the entrance of the fire tube.After cooling the maximum thermal stress fulfils the calibrating standard,and the feasibility of spray cooling scheme is verified.Eliminate the hidden danger of high temperature from the source.