Modeling,Optimization And Control Of Efficient Water Preparation System For Medical Injection

The water for medical injection is the distilled water that can be used for human pharmaceutical injection in accordance with the provisions of the Chinese Pharmacopoeia.It has a huge amount of consumption in the pharmaceutical preparation and medical device cleaning of pharmaceutical enterprises,and is a major energy consumer of pharmaceutical enterprises.At present,medical injection water preparation equipment based on vertical tube falling film multi-effect distillation technology is widely used in pharmaceutical enterprises at home and abroad.There are three main problems in the vertical tube equipment:Firstly,the heat transfer efficiency of vertical tube falling film evaporator is low and the temperature difference between effects is large.Second,there is no energy recovery device,the steam produced by end effect evaporator is discharged as product water,steam cycle utilization is insufficient,resulting in a huge waste of energy.Third,the system has poor anti-interference ability and is susceptible to heat source disturbance.To solve these problems,under the guidance of my tutor,this paper developed the first prototype of efficient water preparation system for medical injection based on horizontal falling film multi-effect distillation with thermal vapor compressor technology which has independent property rights and multiple transformation technologies in the world.The main characteristics are as follows:Firstly,the horizontal falling film multi-effect distillation technology is used to improve the heat transfer efficiency of the evaporator compared with the vertical tube multi-effect distillation technology.Secondly,for the first time,the high efficiency and strong robustness ejector is introduced into the water preparation system to realize the exhaust steam recycling,which greatly reduces energy consumption and improves the stability of the system.Thirdly,the control model of efficient water preparation system is established,and a stable and reliable control system is designed,which provides a basis for the optimization of the subsequent control system.The operation data of the efficient water preparation system prototype show that compared with the vertical tube equipment,the water production ratio of the new equipment is increased by 111%,and the energy consumption is saved by 50%.Steam ejector is the key component of the efficient water preparation system,and its performance determines the operation efficiency and energy consumption of the system.At present,the application of ejector in the field of medical water preparation is still blank,and the design method of high-performance ejector is lacking.Moreover,the ejector involves complex fluid phenomena such as turbulence,shock wave and supersonic,and the research on the mixing mechanism of ejector is not thorough,which makes the design of high-performance ejector very difficult.Due to the neglect of the ubiquitous condensation phenomenon in the model of ejector and the insufficient research on the influence mechanism of wall roughness and adiabatic properties,the prediction accuracy of the current ejector model is insufficient.The complex and changeable operating conditions of medical water preparation system also put forward higher requirements for the robustness of the ejector.Aiming at these problems,this paper carried out the system modeling analysis and the research of high efficiency and strong robustness ejector under complex working condition disturbance.Based on the combination of mechanism modeling,CFD(Computational Fluid Dynamics)simulation and experimental verification,the influence mechanism of ejector wall roughness and adiabatic properties based on non-equilibrium condensation was studied.The design method of efficient water preparation system and high efficiency and strong robustness ejector was proposed.The control-oriented system model and prototype were established,and the effectiveness of system model and ejector design method was verified by prototype.The research results of this paper can improve the water production efficiency of the system,reduce energy consumption,improve the stability and robustness of equipment operation,and promote the realization of the national "emission peak and carbon neutrality" goal,which has important theoretical value and broad application prospects.The main research work is as follows:Aiming at the problems of large energy consumption and poor anti-interference of vertical tube equipment,an efficient preparation system for medical injection water based on horizontal falling film multi-effect distillation with thermal vapor compressor technology was developed.The thermodynamic model of efficient water preparation system and ejector was established,which provided theoretical basis for the design and optimization of the system and ejector.Based on the established thermodynamic model,the influence of the ejector on the performance and stability of the water preparation system was analyzed,and the necessity of the design of high efficiency and strong robustness ejector was verified.In view of the widespread non-equilibrium condensation phenomenon in the steam ejector,the "wet steam" model based on the real gas state equation was established.The effect of wall conditions on the performance of the ejector was analyzed by CFD simulation.The correction formula of isentropic efficiency and entrainment performance of the ejector based on roughness was proposed,which improved the prediction accuracy and universality of the ejector model.The simulation results showed that when the roughness of the ejector inner wall is less than 5um,the influence on the performance of the ejector can be ignored.The poor wall insulation property of the ejector will increase the possibility of the condensation droplets adhering to the ejector inner wall which may damage the wall.Research results of this chapter provided theoretical guidance for the design,optimization and processing of the ejector.Point at the problem that the performance deterioration of the ejector under low operating conditions leads to the decline of the water preparation system performance,this paper started from the sensitivity of the ejector geometric parameters,studied the effect of the primary nozzle profile on the performance of the ejector in detail,and put forward the streamlined primary nozzle optimization method to improve the applicability and entrainment performance of the ejector under low operating conditions.Compared with the benchmark AT ejector,the entrainment performance of the B3T ejector with the optimal design had an improvement of 1.23%under the set working condition,and the improvement effect was more obvious under the low working condition.Especially,the AT ejector entered the reflux invalid state at 450 kPa.while the B3T ejector still had an entrainment performance of 0.12,which improved the application ability of the ejector and the water preparation system under variable working conditions.Aiming at the problem of unreliable operation of the system caused by heat source fluctuation,a geometric parameter calculation model of the primary nozzle was established to maintain the flow stability of the ejector,and a design method of annular ejector with strong robustness was proposed.Taking the set working condition and two low working conditions(the primary flow pressure is 550 kPa and 450 kPa)as an example,a dual-annular strong robustness ejector was designed to maintain the stable outlet flow under three working conditions.Based on CFD simulation analysis,it was found that the dual-annular ejector can maintain the stability of the outlet flow under three working conditions,and the variation is less than 0.65%compared with the outlet flow of B3T ejector under the set working condition.The dual-annular ejector can significantly improve the ejector performance at low operating conditions.Compared with the B3T ejector,the ejector performance of the dual-annular ejector increases by 44.72%at the primary fluid pressure of 500 KPa and 365.5%at the primary fluid pressure of 450 kPa.The control model and control system of the water preparation system was established,and the prototype of the efficient water preparation system was built.The effectiveness of the ejector and the system model and the operation efficiency of the prototype were verified by experiments.The experimental verification showed that the predicted data of the ejector model are in good agreement with the experimental data,and the determination coefficient(R2)of the predicted data and the experimental data was greater than 0.99,which comfirmed the proposed ejector calculation model can accurately predict the performance of the ejector.The prototype operation data showed that the water production ratio of the new medical water preparation equipment developed in this paper is about 111%higher than that of the vertical tube equipment system,and the steam consumption can be saved by about 50%per hour.Taking the 1 t/h equipment as an example,the new medical water preparation equipment can save 227.8 thousand steam costs per year,which had remarkable economic benefits and industrial promotion potential.