| Oxygen is crucial in the vital activities of human body. Oxygen is gotten through breathing from the outside world and participates in biological oxidation in vivo to supply the body with energy. Hypoxia can cause human body metabolism disorders, even be a threat to human lives. Timely supplementary oxygen can effectively increase the cure rate of critically ill patients, and accelerate recovery speed of the weak body. Oxygen therapy is also an effective treatment method for treatment of some diseases of respiratory system, cardiovascular and cerebrovascular diseases, and altitude diseases. Moreover, daily oxygen health care can rapidly eliminate fatigue and enhance the identification capability.Treatment of patients during the disaster assistance or in war time both needs a great deal of oxygen for breathing. Oxygen can be generated by the oxygen generating equipment on site and supplied through the oxygen supplying equipment. Oxygen generating and supplying technologies include oxygen generating technology and oxygen pressurization technology. One of the common oxygen generating technologies is pressure swing adsorption(PSA), which with air as raw material, powered by electricity and through molecular sieve adsorption separation effect, can continuously generate oxygen and is widely used in small and medium-sized oxygen generating system. The main oxygen pressurization technology is the piston gas pressurization technology, which is a continuous oxygen pressurization technology with wide pressure range, high efficiency, and well adaptive capacity. The current generating and supplying equipments mainly include modularized oxygen generating and supplying equipment, assembled oxygen generating and supplying equipment and integrative oxygen generating and supplying equipment, all of which could meet general oxygen demand, but majority have single function and could not meet the demand of both generating atmospheric oxygen for direct breathing and supplying pressurized oxygen for breathing machines and anaesthesia machines.Based on the technologies of PSA and piston gas pressurization, this research established the technological process of oxygen generating and supplying. Taking the design of mechanical-electrical integration and the control technology of programmable logic controller(PLC), this research also optimized the structure layout design and designed the automatic control system of the generating and supplying equipment. The continuous generating and supplying equipment was developed later.The established technological process of oxygen generating and supplying included oxygen generating unit, oxygen pressurization unit and controlling unit. The oxygen generating unit, consisting of air compressor, adsorption tower, buffer tanks and other components, realized the separation of oxygen and nitrogen in the air, generated atmospheric oxygen for direct breathing or for the pressurization unit. The oxygen pressurization unit, consisting of booster pump, buffer tank and other components, pressurized the oxygen from the oxygen generating unit for breathing machines and anaesthesia machines. The controlling unit, consisting of PLC, A/D module, Human Machine Interface(HMI) and other components, realized the function of monitoring and managing the whole equipment running.Taking the control technology of PLC and HMI, the control system of oxygen generating and supplying equipment was designed. PLC received the sensor signals transmitted by A/D module, realized man-machine interaction through HMI and exported control signals. The control flow of oxygen generating and supplying equipment was established according to the control principle. The selected PLC, A/D module, HMI and sensors were compatible. By the software design of PLC, the I/O addresses were planned, the terminals were defined, and the safety alarms were set. By the software design of HMI, the user interfaces were realized and the parameters were correctly displayed. The control system of oxygen generating and supplying equipment monitored the whole equipment running state and parameters such as oxygen flow, oxygen concentration, and oxygen pressure in real time. It could deal with security incidents independently, realize man-machine interaction and ensure safe, steady and continuous operation of the whole equipment.By the selection of main components such as adsorption tower, air compressor, booster pump and buffer tanks of the oxygen generating and supplying equipment, using SolidWorks software do the layout design and the whole structure design, selecting 304 stainless steel as the material of frame, brackets and panels, the equipment was made. The external dimension was 537×709×880mm, the quality was 91 kg, the power was AC220V/50 Hz, 650W(oxygen generating)/900W(oxygen generating and supplying). Statics analyses of the whole frame, the brackets of adsorption tower, air compressor, booster pump and buffer tanks were executed by ANSYS software in order to ensure the stability and security of the oxygen generating and supplying equipment. The analysis showed that the maximum stress of the frame was 30.595 MPa, far less than the yield strength of 304 stainless steel, and the maximum deflection was 0.12211 mm, a relatively small value. The maximum stresses of the brackets of adsorption tower, air compressor, booster pump and buffer tanks respectively were 25.2MPa、28.02 MPa and 0.15 MPa, each less than the yield strength of 304 stainless steel, the maximum stress of the brackets were 0.043mm、0.33 mm and 0.0001 mm, each not affect normal use. Moreover, in order to avoid resonance damage to printed circuit board(PCB), The modal parameters of the PCB were calculated using finite element method. That changing the fixed way from corners fixed supports to three edges fixed supports improved the first six order natural frequency, especially the first order frequency from 50.584 Hz to 203.65 Hz. The seismic performance was improved significantly and fully met the demand of work.In order to further study the performance of the oxygen generating and supplying equipment, the oxygen generating performance and oxygen supplying performance of the equipment were analyzed and detected. The oxygen generating performance analysis showed that 3 minutes after booting oxygen concentration could be up to 90%, which proved good booting performance. Along with the time increasing, the oxygen flow was maintained at 8.6L/min and the oxygen concentration was maintained at 90.8%. Actually the oxygen concentration had relation to both oxygen flow and oxygen recovery rate. The oxygen concentration decreased with the increase of the oxygen flow, and also decreased with the increase of the oxygen recovery rate. when the oxygen recovery rate was more than 35%, the decrease tendency of the oxygen recovery rate increased obviously. The oxygen supplying performance analysis showed that the oxygen pressure, oxygen flow and oxygen concentration remained about the same with the increase of the running time. The oxygen pressure was 0.38 MPa, the oxygen flow was 8.9L/min and the oxygen concentration was 93.8%. The oxygen supplying performance was stable.Adopting the technologies of PSA and piston gas pressurization, the oxygen generating and supplying equipment could continuously generated atmospheric oxygen for direct breathing or continuously pressurized oxygen for breathing machines and anaesthesia machines. With stable, safe and reliable performance, the equipment could replace oxygen bombs. On-board and be used independently, either during the disaster assistance or in war time, it had a vast application prospect. |
PDF Full Text Request