Backflow of condensate in the exhaust pipe During the operation of the refrigeration system, the low-temperature low-pressure liquid refrigerant turns into a gas after being absorbed by heat in the evaporator. The gas is compressed by the compressor and compressed into a high-temperature and high-pressure gas; the discharged hot gas condenses into a liquid when it encounters a cooling medium. Usually this happens in the condenser. When the installation height of the condenser is above the compressor and the height difference between them is large, after the system is stopped for a period of time, the residual hot air in the exhaust pipe dissipates heat to the outside through the pipe wall, generating a condensed liquid when condensing When the amount of liquid is too large, it will adversely affect the operation of the system to a certain extent.
The condenser in the system is installed 16m above the compressor, and the pipeline between the oil separator and the condenser is relatively long. After the system has been out of operation for a period of time, the hot gases in the exhaust pipe condense into liquid back to the oil separator. Since the exhaust pipe is long, the amount of condensate is relatively large, and the liquid level in the oil separator is increased; the liquid level of the oil separator is controlled by the liquid level controller, and the oil level is raised, the oil is raised. The valve between the separator and the crankcase of the compressor is opened, and the oil in the oil separator is returned to the crankcase together with the condensate.
When the system is turned on again, the refrigerant in the oil violently boils, causing the phenomenon of cylinder flushing. After running for a period of time, it will cause damage to the compressor cylinder; in addition, a large amount of flash will be generated while the refrigerant is boiling. The gas causes a sharp change in the oil pressure in the crankcase, and the compressor generates oil pressure protection (that is, it stops immediately after starting up), which is also the reason why the compressor sometimes cannot be normally opened. In order to solve this problem, we decided to install a check valve at the gas outlet of the oil separator, as shown in Figure 2: After the check valve is installed, it can prevent the condensate in the exhaust pipe from flowing back to the oil separator. After stopping the operation for a period of time, the condensed liquid temporarily remains in the exhaust pipe. When the system is turned on again, the condensate can be discharged into the condenser with the high temperature and high pressure gas. After the transformation in this way, the system resumes normal operation, and so far, the above-mentioned undesirable phenomenon has not occurred.
Burnout of the motor In the actual use, the phenomenon of motor burnout often occurs. There are many reasons for this phenomenon, including the quality problem of the motor, the voltage instability, and the cooling capacity of the compressor and the motor. However, more than 95% of the motor burnout is caused by improper use, especially in the harsh environment, the frequent start and stop, the most likely cause the motor to burn out. Under normal circumstances, according to the range of the amount of cooling, the following number of starts and stops should be followed: (1) 960W ~ 5220W fluorine refrigerator, the number of opening and stopping is 20 times / h, the time of each start-up operation should not be less than 2min; 2) 7460W ~ 14920W fluorine refrigerator, the number of start and stop is 12 times / h, the time of each start-up operation should not be less than 3min; (3) 14920W ~ 37300W fluorine refrigerator, the number of start and stop is 8 times / h, The time of each boot operation should not be less than 5 minutes.
Return air protection of the compressor During the operation of the system, when the return air volume of the compressor is insufficient, the compressor will generate protection and stop; the reasons for this phenomenon are usually the following: (1) Charge of the refrigerant in the system Insufficient fluence is often more likely to occur when the distance between the chiller and the warehouse is relatively long or the supply line is long. Because in a small fluoro refrigeration unit, the capacity of the reservoir itself is only applicable. When the distance between the refrigerator and the warehouse is relatively close or the liquid supply pipeline is short, the liquid supply pipeline is long, and the liquid storage in the pipeline is large when the system is running, which easily causes the system to supply insufficient liquid, thereby causing the compressor to return air. Insufficient, resulting in return air protection. Generally, when the length of the liquid supply pipeline exceeds 50 m, calculation should be carried out so that another liquid reservoir can be provided to avoid the phenomenon of return air protection. (2) Thermal expansion valve mismatch When the cooling capacity of the selected thermal expansion valve is less than the actual cooling capacity required for the system operation, it will also lead to insufficient liquid supply of the system, so that the compressor generates return air protection. (3) Blockage of the refrigeration system pipelines When the refrigeration equipment and the thermal components are normal, the return air protection is generated. The system piping should be checked for dirty, oily or ice blocking. In addition, there will be other situations, which need further research and summary.
Oil balance when multiple compressors are connected in parallel Due to the mutual solubility between Freon and lubricating oil, the oil return of fluorine refrigeration system is a long-term concern, but how to make the returned oil evenly return to multiple parallel use Compressor, here is the following simple analysis: When the evaporation temperature is ≥ -15 °C, there is no oil balance pipe between the two parallel compressors, but certain measures should be taken on the return air line, as shown in Figure 3. As shown; oil balance pipe must be added between two or more parallel compressors.
The technical parameters of the compacted modified fiber ball filter passed the on-site application test in the oil production plant of Daqing Oilfield Co., Ltd., and the compacted modified fiber ball filter has good working performance under the design index, and the filtered water quality is oily. The median value of suspended solids and particle size reached the water quality standard of low permeability and water infusion.
The test shows that the compacted modified fiber ball filtration technology has high filtration speed and large processing capacity, and is suitable for advanced treatment of oily sewage in oilfield injection zone. The effluent reaches the water injection standard of low permeability layer, the head loss increases slowly, and the backwash cycle is long. The filter material has the characteristics of small interception of polymer, low operating cost and remarkable efficiency, and has a very broad application prospect in the advanced treatment of oily wastewater in oil fields.
Molybdenum can increase steel`s corrosion resistance in the acid-based solutions and liquid metals, thus improve its wear resistance, hardenability, weldability, and heat resistance. As an element which easy to form carbides, molybdenum can effectively avoid oxidation during steel making process, and it can be used alone or mix with other alloy element to achieve the best performance.
High temperature smelting additives
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