Design And Research Of Coke Oven Gas Hydrogen Production System Based On Molecular Exchange Flow And Its Automatic Control

China has the largest output of coke.Hydrogen production from coke oven gas has gradually become one of the important means of hydrogen production,and hydrogen production from coke oven gas is one of the applications of gas separation technology.Molecular exchange flow is a novel method for gas separation.When there is a temperature gradient in the micro-channel,the mixed gas presents two kinds of heat flow from low temperature to high temperature and Poiseuille flow from high temperature to low temperature in the micro-channel,which is the heat flow effect.According to the heat flux effect,the molecular exchange flow can be constructed by setting the temperature difference and pressure difference at both ends of the microchannel.The gas separation device based on molecular exchange flow has simple structure,no moving parts and can be driven by low grade heat energy,which has distinct characteristics compared with the mainstream gas separation device.In this paper,the characteristics of heat flow and poiseuille flow and the separation of mixed gas in microchannel are analyzed.With coke oven gas as an example,studied the poiseuille coefficient,coefficient of heat flow from along with the change of driving force,discusses the construction of molecular exchange flow conditions and coke oven gas components in the molecular flow exchange flow behavior,the results show that the increase of temperature difference along with the driver,will strengthen the heat flow movement and weaken the berth against Ye Liu,and H₂ is most significant.It is feasible to use molecular exchange flow to produce hydrogen from coke oven gas.In this way,H₂ is the easiest to separate,followed by CO,and CO₂ is the most difficult.The driving conditions of molecular exchange flow were also analyzed.Based on molecular exchange flow,a gas separation unit and a 6-stage series hydrogen production system of coke oven gas were designed.Under the driving temperature difference and pressure difference of 6000Pa required by molecular exchange flow,the product rate of the system could reach 75%and the output hydrogen concentration could reach over 96%.100°C high temperature industrial waste hot water is used as the driving hot flow medium,and 5°C frozen water is used as the driving cold flow medium.The results show that the critical temperature of the molecular exchange flow increases linearly with the increase of the characteristic size of the microchannel.The critical upper temperature increases almost linearly with the increase of component concentration.With the increase of concentration,the influence of temperature on the driving force of output concentration becomes less and less.With the increase of the series,the lower the concentration of hydrogen in the raw gas,the more difficult it is to separate,and the maximum concentration of the product that can be obtained also decreases.Based on the system model,the co-simulation is carried out by using Matlab algorithm and the temperature automatic control model built in Simulink environment.The system adjusts the fluid temperature through the motor speed.The sensitivity of the system is improved by 57.54%compared with the conventional PID control system after using PID control method and optimizing parameters by PSO.The performance and energy consumption of the system are analyzed,and the total hydrogen energy consumption per unit product of the system decreases by 63.2%in the process of the system reaching the stable state from the beginning of operation.With the operation of the system,the hydrogen energy consumption per unit product is reduced by 43.6%compared with the conventional design method,but the hydrogen concentration of the product obtained will also be reduced.Compared with the conventional psa hydrogen production process,the energy consumption is reduced by 38.6%.Finally,the system is simulated in Proteus environment.The simulation model mainly relies on the SCM integrated temperature and concentration sensor to achieve concentration detection,temperature detection feedback,AD conversion,PID control,PWM signal control motor speed and LED real-time data display.The temperature error is between-0.56°C and 0.74°C,and the PWM duty cycle error is between-0.006 and 0.008.