Application of Chlorine-Hydrogen Treated Centrifugal Compressor in Chlorine Compressed Transportation Tang Hongjian's advantages and disadvantages of 'Jian Jianhong (Xinjiang Tianye Group) T-Limited Company, Xinjiang Shihezi 832000).
2丨 Logo Code 丨 B丨 Article Number 丨1008―133X(2009)07-丨丨å”红建(1972-) Male, engineer, graduated from Liaoning University of Engineering and Technology, School of Mechanical Engineering, Department of Equipment Engineering and Management, now in Xinjiang Tianye (Group) ) Co., Ltd. works.
In the production of chlor-alkali, there are many ways of compressing and conveying chlorine gas, and it is possible to adopt a centrifugal blower, a liquid ring compressor, a reciprocating compressor, a screw compressor, and a centrifugal compressor. Since the range of machines for various compression conveyors is different, the choices vary from factory to plant.
The more commonly used chlorine gas compression delivery methods are liquid ring compressors and centrifugal compressor processes. Xinjiang Tianye (Group) Co., Ltd. uses a liquid ring compressor to deliver chlorine gas. The new centrifugal compressor delivers chlorine gas, which is effective after use. The liquid ring compressor of the liquid ring compressor uses concentrated sulfuric acid as the liquid ring and sealing medium, and uses a sulfuric acid cooling cycle to take away the heat generated when the chlorine gas is compressed.
The process is as follows: 98% concentrated sulfuric acid from the pump acid high tank is throttled into the liquid ring compressor, and the operation of the compressor forms a sealed liquid flow ring around the impeller, so that the normal temperature chlorine gas in the inlet manifold is sucked into Compressor; under the compression of the compressor, the chlorine gas is pressurized (Q 15MPa) while the chlorine gas stream with sulfuric acid enters the gas-liquid separator. In the gas-liquid separator, the chlorine gas is centrifugally separated by a cyclone and is directed upward into the chlorine gas outlet manifold. After the sulfuric acid is separated, it enters the sulfuric acid cooler from the bottom of the separator, is cooled by the industrial water to normal temperature, and then returns to the compressor, thus repeating the cycle.
Because the working pressure of the liquid ring compressor is not high, most of the heat generated by the compression is carried away by the sulfuric acid, and the sulfuric acid cooler performs the task of cooling the sulfuric acid to normal temperature. The chlorine gas temperature at the compressor outlet does not generally exceed 80 ° C (the actual gas phase temperature is below 60 ° C) and does not corrode carbon steel material equipment and piping. Therefore, the chlorine gas cooler is not installed in the liquid ring compressor process.
In the liquid ring compressor process, the mass fraction of sulfuric acid is required to be not less than 92% to weaken the corrosion of the compressor at high temperatures. In addition, due to incomplete dehydration and drying of chlorine gas, the gas phase still contains a certain amount of water, which is absorbed by sulfuric acid in the compressor. Therefore, the mass fraction of sulfuric acid in the circulating liquid will be reduced, and it needs to be supplemented with 98% of concentrated sulfuric acid. Circulating sealing solution.
The schematic diagram of the liquid ring compressor process is shown.
2 Centrifugal Compressor Chlorine centrifugal compressor is suitable for large-flow, medium-low discharge pressure of chlorine gas. It is a new type of compressor developed to meet the needs of continuous improvement of chlorine treatment process and continuous improvement of technical requirements. Since the moisture content in the gas phase chlorine gas after purification has been lower than that of the chloral-hydrogen treatment book1 chlor-alkali industry year and does not contain acid mist, it is completely suitable for the compressed transportation of chlorine gas.
The process (see) is: after the treated purified chlorine gas is sucked into the first-stage inlet of the centrifugal compressor and compressed by the impeller under the pressure of more than 0 085 MPa (absolute pressure), the gas phase temperature rises while static pressure It can be increased and taken out into the interstage cooler to cool the chlorine gas to normal temperature. Then, it is sucked again into the secondary inlet. After the impeller is compressed, the gas pressure rises and the static pressure increases again. It is led out into the interstage cooler to cool the chlorine gas to normal temperature. After several cycles of compression, until the gas outlet pressure reaches the rated pressure (rated pressure is determined by the design requirements) and then sent to the chlorine department by the distribution station.
Schematic diagram of the centrifugal compressor system flow In this compression conveying process, in order to adapt to changes in the electrolytic load, a control means for self-controlled shifting or self-controlled return air volume adjustment is provided. Return the outlet gas of the turbine compressor unit to the compressor inlet or the drying system inlet or the chlorine scrubber outlet (if it is an indirect cooling process, return to the industrial water titanium cooler inlet) to ensure the pressure of the chlorine outlet manifold at the anode outlet of the cell. Constant.
The working mechanism of the centrifugal compressor unit is firstly the formation of continuous gas flow in the compressor: when the compressor wheel rotates at a certain speed, the gas remaining in the flow path of the working impeller blades is driven by the blades to rotate together with the working impeller. The gas is forced into the flow path of the diffuser behind the impeller under the centrifugal force generated by the high-speed rotation (when the compressor transfers mechanical energy to the gas to generate kinetic energy of the gas phase). A thin strip of vacuum is formed in the vane flow path of the working impeller, thereby filling the outside of the gas from the suction chamber into the vane flow path of the working impeller to fill the vacuum thin zone. As the compressor continues to rotate at high speed, the gas is continuously thrown out of the impeller; the outside gas is continuously sucked into the impeller, thus forming a continuous flow of gas in the compressor.
Secondly, the compressor performs work on the gas: the gas undergoes the compression work generated by the centrifugal force of the working impeller, and the kinetic energy and a certain amount of static pressure energy and heat energy are obtained, so that the air flow speed is greatly improved. Because chlorine gas is a relatively high-density gas compressor that works on the gas, it generates extremely large airflow and friction and impact loss in the flow path of the impeller. This part of the work loss is converted into heat energy, which causes the gas temperature to rise.
In general, after compression by the compressor stage impeller, the gas cannot reach the required pressure at once. Because of the diffuser limit of the diffuser, the rated pressure of this level can be achieved, and the chlorine gas needs to be taken out of the machine for interstage cooling, so that the gas temperature is cooled to the normal temperature, and then the secondary compression is performed, so that the multi-stage compression is performed. After cooling, the chlorine gas reaches the required outlet pressure.
The advantage of a 22-chlorine centrifugal compressor requires only one chlorine-cylinder centrifugal compressor to be sufficient to maintain full-load production.
The shaft sealing device of the compressor has a simple structure and a long service life.
The chlorine gas centrifugal compressor unit adopts a more advanced inflatable labyrinth seal, which makes the “shaft seal†more reliable and effective; at the same time, the unit has fewer wearing parts. The unit has high structural reliability, relatively few faults, and can work continuously and with high efficiency.
The chlorine gas centrifugal compressor has high operating efficiency. When the conveying capacity is within the applicable range of the turbo compressor, the operating efficiency is higher than other types of compressors. Liquid ring compressors are even less able to compare. Because the discharge pressure of the turbo compressor is high and the amount of gas delivered is large, the required power is relatively small. Even if the pressure of the chlorine pipe network is higher than the rated discharge pressure, it will not affect the normal operation of the unit, and it is even less likely that back pressure will occur.
In addition, the chlorine gas turbine compressor has fundamentally got rid of the sulphuric acid corrosion. Compared with the "liquid ring compressor", it is undoubtedly a big step forward, so that in the chlorine gas treatment process, 1 chlorine gas eliminates Tang Hongjian, etc.: Application of centrifugal compressor in chlorine gas compression and transportation Chlorine-hydrogen treatment bookmark2 consumption of sulfuric acid decreased by 7kg can save 700t of sulfuric acid throughout the year (4 wins centrifugal compressor group is small. Large volume of chlorine gas turbine compressor's own volume comparison Small, so it occupies less space and takes up less space. At the same time, the integration of each system is formed, and the whole unit realizes integration, modularization, pocketing and high precision.
(5) The turbine compressor discharge airflow is not pulsating, and the operation is stable and reliable. Under full-load operating flow, the unit's inlet and outlet pressures and compression ratios at all levels are very stable and do not fluctuate. Under the conditions of large flow and full load, the chlorine gas turbine compressor unit runs very smoothly, and the larger the flow rate, the more stable. Even if some of the chlorine user's failures cause the network airflow to fluctuate, the turbine unit can still run smoothly. In addition, the turbo compressor unit is equipped with a precision automatic control system (DCS) with reliable instrumentation and interlocking devices to ensure reliable and smooth operation of the chlorine turbine compressor unit.
The disadvantages of 23 chlorine gas centrifugal compressors are very high on the quality of chlorine gas treatment. The chlorine gas turbine compressor is a relatively sophisticated chemical equipment for compression and transportation, so the moisture contained in the conveying medium and the degree of cleanliness are very high. It is generally required that the mass fraction of water in the transport medium chlorine gas is less than 001%. The suitability of the chlorine gas turbine compressor unit is not wide. This type of chlorine compressor can only be used in high-flow, medium-low discharge pressures, and companies with small production scales are excluded from use.
The opening and stopping steps of the turbine unit are cumbersome. Because the unit is a system engineering, the implementation of the driving steps must start from each system. First, the subsystems of the sealed gas system, the oil system of the unit, the accident handling system, the automatic control system, the high voltage system, and the low voltage system are operating normally. It can be seen that the chlorine gas turbine compressor unit is not as convenient and random as the liquid ring compressor.
At the exit of the unit, if the chlorine gas discharge pressure exceeds the standard for a long time, the safe operation of the unit will be threatened, and surge will most likely occur, causing serious damage to the unit. This is also something that cannot be ignored.
Although chlorine gas centrifugal compressors have some shortcomings, with the gradual improvement of equipment, centrifugal compressors will have a wide space for use.
(Continued from page 20) and the Nt evaporation mass concentration of 125g/I per 1ti% of production is 12367g/I. The evaporation efficiency is about 40kg.
(5) This method improves the resistance of the electrolytic cell to a wide range of fluctuations in production load (electrolytic current). Especially under the condition that the production load of the chlor-alkali industry caused by the current international financial crisis has dropped drastically, the effect of this method is more obvious.
However, this method may also have the following disadvantages: (1) increase the liquid level of the catholyte, reduce the space of the cathode chamber, and increase the amount of hydrogen in the chlorine. (The control of the chlorine in the modified diaphragm electrolyzer of Xianglong chlorate plant is better. 2) The length of the short circuit cannot be adjusted arbitrarily, and the concentration of the single-slot electrolyte that needs to be adjusted cannot be controlled at will.
4 Conclusion The method of increasing the electrolyte concentration of the main pipe by increasing the liquid level of the catholyte in the electrolysis tank has been used in the chlor-alkali plant of Xianglong Co., Ltd. for more than one year. On the one hand, the electrolysis cell with a single-tank electrolyte concentration exceeding 140g/L can be controlled. A very low ratio (such as 10%) achieves a higher overall current efficiency; on the other hand, it ensures that the concentration of light alkali produced by the electrolysis process is within the control range - it can meet the needs of evaporation production, so it can be considered The method has more advantages than disadvantages for production and consumption.
Table 2 Changes in oxygen content in chlorine before and after the insertion of the alkali tube Intubation time The number of cells in the electrolysis cell / kA intubation before the intubation increased the average
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