Study Of Pressure Swing Adsorption Oxygen Plant Operation Optimization

With the development of economy and society,people have more higher requirement of domestic water,industrial water and water environment,which sets higher requirement of all kinds of water treatment technology in water supply and drainage field.Pressure swing adsorption(PSA)oxygen produce process has been widely used in all kinds of water supply and drainage project for its obvious advantage,such as,low energy consumption,easy to start and shut down,user-friendly,less investment and so on,especially in disinfection system and contaminant oxidation.PSA oxygen produce process has become one important technology component of water treatment,and a not to be ignored part in new water treatment technology development and application,so study on PSA oxygen produce process has become a new direction to scientific and technological workers in water supply and drainage field.Along with the development and application of higher oxygen nitrogen separation coefficient and low silica-alumina ratio lithium-based molecular sieve,PSA process has become the most widely used production technology for non-high purity oxygen(purity<95%)production.To PSA oxygen production process,the study focuses on oxygen molecular sieve development,adsorber structure design enhance and process optimization.Software simulation and study on small experimental facility has become an important research method for PSA oxygen production process optimization,process optimization can enhance oxygen purity,increase recovery ratio,and make energy consumption lower.Besides,more intelligent automatic control technology is developed and applied to PSA oxygen production plant to reduce the power consumption of oxygen production.The cycle of software simulation and study on small experimental facility to optimize PSA oxygen production process is normally short,and experimental data is less,the condition and result between small experimental facility or software simulation and large-scale PSA plant always has some deviation.Besides,study on large-scale PSA oxygen production plant optimization is still less.This thesis takes running large-scale PSA oxygen production plant as the research object,get plant process data through Aspen Process Data,then calculate specific power consumption of oxygen production(i.e.spec power).Study the relationship between main influencing factor and spec power.Find that when air inlet temperature increases from-5℃to 35℃,original spec power decreases firstly and then increase,there is an obvious quadratic relationship between original spec power and air inlet temperature.Too high or too low air inlet temperature will lead to high original spec power,the best air inlet temperature is16.2℃,which will lead to the lowest power consumption of oxygen.When inlet air temperature increases or decreases 1℃relative to 16.2℃,the original spec power of oxygen production will increase 7.4463kwh/Nm~3.During oxygen purity variation in a short time,the higher oxygen purity will lead to high original spec power,there is an linear relationship between original spec power and oxygen purity,original spec power will increase 0.0071kwh/Nm~3～0.0074kwh/Nm~3when purity increasing 1%.Besides,original spec power increase even more when purity changing from low to high than purity changing from high to low.In the cycle of inlet filter differential pressure changing,there is an obvious linear relationship between corrected spec power and inlet filter differential pressure after temperature correction and purity conversion.the relationship is not obvious before temperature correction and purity conversion,even original spec power reduce with differential pressure increase appear,which goes against the basic principle of power consumption increase when differential pressure increases.This is further show that temperature correction and purity conversion of original spec power is reasonable and necessary,besides,meeting the actual needs for analysis and calculation.Power consumption of oxygen production(i.e.corrected spec power)will increase 0.0008kwh/Nm~3when differential pressure of inlet filter increases 1mbar.After identifying the incidence of main the other influencing factor on power consumption of oxygen production in PSA plant operation,analyze the influence of cycle step time on final spec power through response surface analysis by using Design Expert 10.0.4.Throughout the process cycle,take the time of air feed(step 2),air feed&produce oxygen(step 3),provide purge(step 5)as the influencing factor,take final spec power and oxygen flow as response,design central composite experiment and conduct running test per the experimental plan.Calculate original spec power under different process step time parameter,get the final corrected specific power consumption of oxygen production(i.e.final spec power)by using the formula determined in previous chapter,namely final spec power has same baseline.Input response value into software and analyze it,the regression model of final spec power is determined,and has statistical significance and high significance for its probability value(P-value)less than0.0001.The model has adequate precision,and the residual distribution is nearly a straight line,and Lack of Fit is not significant,it means that fitting effect of the regression model is good and can be used to replace real test point for results analysis.Through analyzing two-dimensional contour graph and three-dimensional response surface diagram,the order of the influence that the cycle step time has on final spec power is determined,the order of influence significance is step 2,step 5,step 3.After optimization,when step 2 is 7.8s,step 3 is 4s and step 5 is 3.6s,the final spec power is minimal.Running plant repeatedly with the optimized time of cycle step to verify real final spec power is match with regression model predicted value or not.Relative deviation between model predicted value and the average value of repeated plant real running is 3.02%.Multiple plant running result show that the regression model of final spec power has good accuracy,practicality and predictive ability.The model not only can be used to analyze the influence of cycle step time on final spec power,but also can be used to predict final spec power of different cycle step time.Through plant practical running by using optimized steps time,the power consumption of one cubic meter oxygen reduces 5.42%by comparing with plan design spec power of oxygen production.Plant operation optimization can reduce power consumption of oxygen production effectively,and lead to obvious economic benefit.The strategy of study influence factor of power consumption of oxygen production and plant operation optimization can provide basis and method for PSA plant performance assessment and plant operation optimization.