Freeze dryer refrigeration and vacuum system maintenance and common problems
Pick To: analyze its daily maintenance and common questions from two aspects of the lyophilizer refrigeration and vacuum systems.
Key words: freeze dryer; refrigeration system; vacuum system; routine maintenance; maintenance measures;
Freeze-drying machines are widely used in pharmaceutical production. However, due to the uninterrupted nature of the freeze-drying production process, once the freeze dryer malfunctions, it will seriously affect production and bring losses to the enterprise. Therefore, the author analyzes the daily maintenance and common problems of the two major refrigeration and vacuum systems, and hopes to inspire users of freeze dryers.
1 refrigeration system
1.1 daily maintenance
( 1 ) Routine inspection before each start: 1 ) All shut-off valves (compressor suction and exhaust valves, liquid supply valves, hand valves, etc.) are open; 2 ) Whether the pressure gauge readings are normal ( 0.6 to 0.7) MPa ); 3 ) Whether the compressor oil level is normal ( 1/4 to 3/4 ); 4 ) The cooling water pressure ( above 0.1 MPa ) and whether the temperature is normal.
( 2 ) After power transmission, please pay attention to: 1 ) whether the compressor automatically collects liquid; 2 ) whether the oil pressure difference is reset, etc.; 3 ) check the heating of the crankcase heater, the temperature of the crankcase should be higher than the ambient temperature
( 3 ) Pay attention after starting: 1 ) Whether the compressor running sound is normal; 2 ) Whether the refrigeration pipeline has abnormal vibration; 3 ) Whether the vibration of the compressor itself is minimum; 4 ) Whether the flow rate of the liquid mirror is normal; 5 ) Expansion valve Frosting; 6 ) Compressor frosting .
(4) compressor refrigeration oil as the case may be replaced every six months or once a year.
( 5 ) The water condenser needs to be cleaned regularly, usually for 1 year. It can be washed and washed, or it can be rinsed with water treatment detergent. For air-cooled units, clean the outer surface of the condenser in time.
( 6 ) Note that the compressor cannot be started frequently, and the start interval should be longer than 3 min .
1.2 Common problems and solutions
( 1 ) If there are too many refrigerants and the exhaust pressure is high, part of the refrigerant should be released.
( 2 ) The cooling water temperature is high, the flow rate is insufficient or the water condenser is fouled.
( 3 ) There is leakage in the low-pressure section of the refrigeration pipeline, and air is taken in.
( 4 ) The high-pressure exhaust valve is not open or damaged, resulting in poor exhaust.
It can be reset by the alarm reset button, and the button switch is on the high pressure relay.
( 1 ) The oil return is not smooth, resulting in insufficient oil level in the crankcase of the compressor, and the oil pump cannot absorb oil. A new oil separator is generally required.
( 2 ) The oil is dirty, causing the oil pump filter to clog. Change oil and clean the oil filter.
( 3 ) The oil pressure difference relay fails. Replace the new oil pressure difference relay.
( 4 ) The oil pump has failed. Replace the new oil pump.
( 5 ) The refrigeration system does not evaporate well and refrigerant enters the crankcase. Bringing the frozen oil into the system causes the oil pressure to be too low. Close the supply valve at the outlet of the small condenser or adjust the thermal expansion valve (increasing the superheat of the system).
After the compressor starts for 90 s , the oil pressure difference relay works. If there is no oil pressure difference, it will alarm. After the alarm, the alarm can be reset by the reset button on the oil pressure difference relay.
The system has insufficient return air and the motor is not sufficiently cooled.
Solution: ( 1 ) Adjust the medium-cooling expansion valve to increase the circulation of the system to fully cool the motor. ( 2 ) Check if the liquid supply pipeline is clogged (liquid supply shut-off valve, dry filter, solenoid valve, filter screen before expansion valve, etc.), if it is blocked, it should be solved. ( 3 ) Check the suction filter of the return air line and the compressor for blockage and blockage for repair. ( 4 ) Check for the lack of refrigerant, if it is missing.
After the electronic thermal protection alarm, the thermal protection 220 V control power is turned off and restarted to eliminate the alarm.
( 1 ) The cooling water pressure is lower than the pressure set by the water pressure relay. It is necessary to ensure that the cooling water pressure is higher than the pressure set by the water pressure relay; the pressure set by the water pressure relay can be appropriately lowered in the case of ensuring the cooling effect that the compressor high pressure does not alarm.
( 2 ) The water pressure relay fails. The water pressure relay needs to be replaced.
As long as the water pressure is higher than the pressure set by the water pressure relay, the alarm can be eliminated.
( 1 ) One of the high-pressure alarm, oil pressure difference alarm, electronic thermal protection, and water pressure alarm. Need to find the cause of the alarm and eliminate the alarm.
( 2 ) The instantaneous starting current is too large, resulting in thermal overload protection or air switch protection. It is necessary to find out the cause of the large current and start the thermal overload after resetting.
( 3 ) The compressor crankshaft is killed and the piston cylinder is killed. Need to repair the compressor.
( 4 ) Control system failure, no output control for the compressor. Should be solved by our company software staff.
( 5 ) Electrical system failures such as PLC failure, AC contactor failure, etc. Replace the electrical components after confirming that they have failed.
( 1 ) At least one of the high pressure alarm, oil pressure difference alarm, electronic thermal protection and water pressure alarm during operation.
( 2 ) AC contactor failure during operation, overload protection, and the compressor motor suddenly burned out.
( 3 ) A liquid or oil strike occurs during operation, and a piston or crankshaft is killed.
( 4 ) The runtime control program appears to be unstable instantaneously, and suddenly there is no output.
1.2.7 refrigeration system cooling effect is not good
( 1 ) The expansion valve is opened too large or too small. If the expansion valve is opened too much, the compressor itself is seriously frosted, the amount of fluid is too large, the expansion valve is too small, and the fluid volume is insufficient. The expansion valve needs to be adjusted to achieve the best working condition of the compressor.
( 2 ) The refrigeration system is not blocked properly, such as the filter is clogged, the expansion valve is blocked, the relevant valve is not open or not fully open, and the solenoid valve is malfunctioning. Need to find the location and cause of the blockage, and clean it in time.
( 3 ) The refrigerant is not enough. Need to add the right amount of refrigerant.
( 4 ) The paper pad on the upper part of the compressor valve or the lower part of the cylinder is broken or broken or the compressor suction and exhaust valve piece is broken. A new paper pad or vent valve plate needs to be replaced.
1.3 common maintenance measures
(1) the system pressure, nitrogen filled to 1.4 MPa, to be high, medium, low, the oil pressure gauge 4 balance reading is recorded each table, holding pressure for several hours (typically less than 24 h), the pressure gauge to see each Whether the reading is declining, if it is falling, it indicates the leak point of the system, and suspicious points can be applied with soapy water for leak detection.
( 2 ) The premise of checking the suspicious points with halogen lamps is that the system has refrigerant, and the four tables are balanced ( 0.5 MPa or more).
( 3 ) With the advanced leak detector, you can use the helium mass spectrometer to vacuum the pipeline first. After pumping the limit, turn off the vacuum pump, use the helium mass spectrometer to vacuum, spray the helium gas to the suspected leak point, and pass the helium mass spectrometer. The instrument on the display shows that the specific location of the leak point is very high.
1.3.2 How to charge refrigerant
( 1 ) Before charging the refrigerant, it is necessary to determine the quality of the refrigerant. After confirming that the quality is no problem, it can be filled. The inferior refrigerant has great destructive power to the compressor and the refrigeration system, but it affects the operation of the refrigeration system. The machine is damaged.
( 2 ) It can be charged from the low pressure suction port of the compressor. The cylinder is strictly prohibited to be placed upside down and lying down. When charging, air is prohibited from entering the refrigeration system.
( 3 ) Before filling the refrigerant, please make sure that the system is filled with integrity or supplementary charge. If it is the former (special
Don't just carry out the pressure-holding leak detection operation. It is recommended to vacuum the system first; for the latter, please clean the air in the system and replenish the refrigerant.
( 4 ) If the refrigerant is azeotrope, it is not necessary to invert the cylinder and lay it flat and directly fill it into the system; if it is a non-azeotropic refrigerant, consider putting the cylinder upside down and lying down (ie, the outlet is liquid), but The refrigerant tank valve should be kept as small as possible to avoid liquid hammering of the compressor.
( 5 ) Before filling, please ensure that the connected pipe does not leak, connect it to the refrigerant tank discharge port, then open the valve to remove the refrigerant in the connecting pipe, and then connect the other end of the connecting pipe to the gas-liquid separator. On the upper angle valve; observe the pressure value of each pressure gauge, the number of bubbles on the mirror and the defrosting of the compressor to determine the refrigerant charge.
1.3.3 How to adjust the expansion valve
( 1 ) Rotate clockwise to reduce the flow rate of the expansion valve, and counterclockwise to increase the flow rate of the expansion valve.
( 2 ) The amount of frost on the suction port of the compressor and the amount of bubbles in the liquid mirror can indirectly reflect the degree of opening of the expansion valve. When adjusting the expansion valve, the adjustment amount should not be too large, and the time interval between the two is not Below 15 min to observe the operating trend of the system. Once the expansion valve is set, do not move again unless the operating conditions vary greatly.
1.3.4 How to collect liquid
First a water condenser liquid valve is closed, the compressor starts after 10 s cold plate is opened and the solenoid valve solenoid valves condensation, operation of the compressor 5 ~ 8 min, check pressure compressor, the pressure in the intermediate pressure 0 kgf / cm or so Stop the compressor operation and close the water condenser inlet valve. The Freon is drained into the water condenser.
1.3.5 Replace the cleaning filter
After the refrigeration system has been in operation for more than 1 year, it is recommended to replace the filter element of the dry filter and the filter element of the return air filter. Preferably changed once a year, can not be removed for replacement and washed with petrol.
1.3.6 How to change the refrigeration oil
1.3.6.1 Use of frozen oil
Generally speaking, the refrigeration system should be replaced after the first 100 hours of operation. After the operation of 10 000 ~ 12 000 h , the refrigeration oil should be replaced. When the oil is changed, as long as the oil level is 1/4 of the sight glass , it is not necessary to add more. It is easy to cause oil blows when oil is too much. In general, special refrigeration oil should be used in accordance with the requirements specified by the manufacturer.
( 1 ) Close the compressor suction valve, manually reset the oil pressure safety controller, start the compressor, and discharge the refrigerant in the compressor into the system. When the pressure in the compressor is balanced with the atmospheric pressure, turn off the compressor (cut off the power supply) ), close the compressor exhaust cut-off valve, at this time the pressure inside the compressor will rise again, open the joint on the exhaust cut-off valve, and store the stored air.
( 2 ) Unscrew the oil drain from the compressor drain port and take out the oil filter to release the dirty oil.
( 3 ) Wash the metal powder on the oil filter oil with gasoline, dry it, reload it and tighten the oil plug.
( 4 ) Unscrew the compressor from the upper left side of the oil mirror, connect it to the oil drum with the oil filling pipe, and vacuum the compressor. The freezing oil is automatically sucked into the compressor by the action of atmospheric pressure.
( 5 ) As long as the oil change is exposed, the compressor oil is exposed to the oil mirror 1/4 , and then the wire plug is tightened.
( 6 ) The air in the compressor is extracted by a vacuum pump.
( 7 ) Turn on the compressor suction and exhaust shutoff valve to put the compressor into operation.
Close the water condenser outlet valve, start the compressor, open the plate cold valve and the condensing valve after 10 s , and then turn off the compressor after 5 minutes of continuous operation . After 10 minutes , let the refrigerant cool to liquid, the air is all in the liquid. Above, through the water condenser inlet valve, unscrew the nut next to it and turn the valve stem clockwise to discharge the air.
Liquid refrigerant or lubricating oil can damage the suction valve plate as it is drawn into the compressor cylinder. Liquid hammer can cause damage to the valve plate, piston, connecting rod, crankshaft, and piston pin in a short period of time. Reducing or avoiding liquid entering the cylinder prevents liquid slamming. The most common phenomenon of liquid hammer is the breakage of the suction valve and the breakage of the connecting rod.
The liquids causing the compressor to slam are mainly the following: ( 1 ) liquid return, that is, liquid refrigerant or lubricating oil flowing back from the evaporator to the compressor; ( 2 ) foam with liquid start; ( 3 ) compressor There is too much oil inside.
2 vacuum system
2.1 daily maintenance
( 1 ) Before turning on the vacuum pump, check the oil level of the vacuum pump (usually the oil sight glass 1/2 ).
( 2 ) Before opening the vacuum pump and small butterfly valve, ensure that the front door is closed and all valves are closed. Before the vacuum pump starts to vacuum the tank, it must be ensured that the rear tank is dry. If there is water vapor, the condenser temperature should be lower than
( 3 ) If the vacuum pump and Roots pump are water-cooled, make sure that the cooling water is in place before the vacuum pump is turned on. You can touch the temperature of the pump body by hand during operation. Roots pump start should not be too early (controlled by electric contact pressure gauge).
(4) vacuum pump oil to be regularly replaced, its cycle is generally once a year. When the vacuum pump is running, pay attention to the change of oil color in the liquid level meter. If white turbidity caused by white small droplets appears in the upper part of the oil during operation, it means that water vapor or organic solvent enters the vacuum pump. Please open the gas vibration valve for a period of time (depending on the actual situation, usually about 1 h ); if the pump oil appears all milky white, black or other colors for a long time, the oil has deteriorated and emulsified, and the vacuum pump oil needs to be replaced.
( 5 ) After running the vacuum pump, please do not open the small butterfly valve, let the vacuum pump pump the vacuum tube for a period of time, observe whether the vacuum pump generates noise during operation, and whether it can draw the ultimate vacuum within the normal time. If there is any change, please check whether the vacuum pump oil has deteriorated, whether the pump head solenoid valve is normally open, and whether the connection parts on the pump head are loose.
2.2 Reasons for unsatisfactory vacuum and treatment
First observe the oil level of the vacuum pump and whether the oil is polluted. If the quality of the vacuum pump oil drops significantly, after the emulsification phenomenon, it needs to be replaced immediately, and the cause is found. If the vacuum pump draws in a small amount of water, the gas ballast valve can be opened, and the vacuum pump oil is observed after 1 hour . Whether it is improved, whether the vacuum is reduced. If the vacuum pump has not changed significantly after repeated oil changes, it can be regarded as a vacuum pump failure, and the vacuum pump needs to be repaired.
2.2.2 System leakage
Please use the exclusion method to check the points, valves and related seals that may leak.
2.2.3 There is water inside the box
The condenser is not completely defrosted, and the water is not drained, causing the water at the bottom of the tank to volatilize and affect the vacuum.
( 1 ) During the process of using the vacuum gauge, some moisture or other volatile liquids are inside, which causes the vacuum display to be bounced and inaccurate. Please use a blower to dry the inside and put it into use.
( 2 ) The vacuum gauge is not installed correctly. The correct method is: regulate the vertical installation, the installation position should be close to the suction port, and away from the air outlet.
( 3 ) The operator does not regulate the use of the vacuum gauge. For example, when the gauge is charged, the connecting wires are arbitrarily inserted and removed. When the load is regulated, the detachment is arbitrarily removed, and the handle is not handled lightly. Regulation has been undermined.
( 4 ) The performance of the regulation itself is gradually reduced with the passage of time. The inside of the regulation can be cleaned with acetone solvent, and the display accuracy is checked after air drying.
2.3 common maintenance measures
2.3.1 Oil change of vacuum pump
Be sure to use the oil number specified correctly, otherwise the performance of the pump will be degraded and the vacuum pump may be damaged.
( 1 ) Open the oil plug, then unscrew the oil drain plug, and use the corresponding container to catch the discharged waste oil. After draining, screw on the oil drain plug.
( 2 ) Add fresh vacuum pump oil as long as the oil level is slightly exposed to the sight glass. After running the vacuum pump for 5 s , turn off the vacuum pump and repeat the procedure of ( 1 ).
( 3 ) If the discharged oil is still dirty after the step ( 2 ), consider re-cleaning the vacuum pump. Finally add the vacuum pump oil, the oil level should be maintained at 1/2 between the two oil level indication lines ( indicated by the upper and lower limits on the casting line and the label on the pump casing).
( 4 ) Start the vacuum pump for testing, and wait until the pump temperature rises to judge its vacuuming performance. If the vacuum is still not ideal, there may be deposits such as sludge in the pump or mechanical reasons.
The vacuum pump should be maintained by the operator whether it is used or not. For example, the vacuum pump should be turned on to open the gas vibration valve every week, and it can be operated for about 2 hours under no-load conditions . Check whether the pump body leaks oil. Whether there is noise or not during work.
Generally speaking, when the drug powder enters the vacuum pump, the powder pump will have a great influence on the rotary oil of the pump oil and the vacuum pump. When the vacuum pump has water or pollution, the limit pressure rises and the mechanical friction of the pump increases. In severe cases, the pump will not work; even more serious, the motor will burn out due to overload. Therefore, it is strictly forbidden to let the vacuum pump work on a highly corrosive drug. If the general corrosive drug is vacuumed, it should be treated as appropriate. Carry out maintenance.
( 1 ) When starting the first time, be sure to check the running direction of the circulating pump (the green light is normal and the red light is reversed).
( 2 ) Observe the level of the balance tank ( 1/3 to 1/2 ) before starting each time .
( 3 ) After opening the circulation pump, observe the pressure gauge reading (normal value is 0.1 MPa ). Whether the pressure gauge pointer is shaking, if it is shaking, it means that there is air in the circulation system, and air should be excluded. The way to remove air is as follows: connect one end of a plastic hose to the exhaust valve on the heat transfer tubing, and the other end into the balance tank; open the exhaust valve and turn on the circulation pump to allow the heat transfer oil and air to enter the balance tank through the pipe. The end of the cycle is marked: the pressure gauge pointer is stable, there are no obvious bubbles on the plastic pipe and the circulation pump is no longer automatically switched; observe the heat transfer oil inlet and outlet temperature, especially the inlet temperature, to ensure that the heat transfer oil inlet temperature is accurate. During the operation, it must be considered that the circulation pump itself also has the performance of heating, which requires the operator to take into account the role of the circulation pump when not performing electric heating. Replacement of conducting oil: Note that the performance of heat transfer fluid, typically three yuan per year for a second mixture, silicone oil change every 5 years. Heat transfer fluid filling: circulation circuit provided with two filling valve, it is located in the most significant bit and the least significant bit of the cycle, before filling them from the exhaust gas and to ensure the filling action. The circuit can be filled after leak detection, drying and venting. When charging, when the heat transfer fluid is reflected from the level gauge of the balance tank, the circulating pump is started to exhaust, and the liquid is exhausted while filling, until the air in the drain line is drained, and the liquid is filled to the balance tank level meter. At 1/3 , all valves are closed and the charge is completed.
3 Conclusion
The refrigeration and vacuum system is the two major systems of the freeze dryer, which plays a decisive role in the freeze-drying process and the final product quality. Therefore, it is also the content that the pharmaceutical company employees must clearly understand. Of course, there are other components in the lyophilizer. Any problem with any system will affect the quality of the final product. Only by fully understanding the structure and principle of the lyophilizer can the problem be analyzed and eliminated to ensure a smooth lyophilization process.
Pressure Compensated Emitter Products
Shandong Chunyu Water-saving Irrigation Equipment Co., Ltd., founded in 2011, is located in Laiwu High-tech Zone, Jinan City. It is a high-tech enterprise focusing on innovative and efficient emitter mold manufacturing and emitter product research and development and production. After nearly ten years of innovation and development, it is the invisible champion enterprise in Shandong Province, and now it is in a leading position in this field in China.
Spring rain people-oriented, build talent highland. At present, the company has 16 high, fine and advanced technical personnel, and cooperates with a number of scientific research institutes, forming a mold design, emitter testing, flow testing and other professional technical personnel team. In recent years, it has obtained 3 invention patents, 33 utility model patents and 3 patent awards. In 2019, it was identified as an intellectual property advantage enterprise in Jinan. It has undertaken 4 provincial science and technology innovation projects and won 2 second prizes of Shandong Science and Technology Progress Award. The company has built Jinan drip emitter mold engineering technology research center, the company has a slow wire cutting, CNC machining center, precision EDM machine, 3D projection measuring instrument, CNC engraving, laser engraving and other advanced processing equipment. Mature technology and rich experience support the excellent quality of Chunyu. Spring Rain pays attention to every link of production, implements 8S management, strictly controls the quality of products at the beginning, the middle and the end, and forms the seamless link of production management. The company has independently researched and developed flat emitter molds with full hot runner, cylindrical emitter molds with full hot runner and other products. With excellent quality, competitive price and good after-sales service, the company is well known at home and abroad, and has been sold well in Egypt, India, Iran, Turkey, Saudi Arabia, the United States and other countries.
With the vision of "building a global professional emitter mold supplier" and the mission of "providing solutions for efficient and innovative production of global water-saving irrigation enterprises", the company takes "scientific and technological innovation to scale new heights; Keep improving, the pursuit of excellence; Honesty and trustworthiness, win-win cooperation "for the values of the enterprise. For the construction of water - saving and resource-saving society to make a positive contribution.
Pressure Compensated Emitter Products,Pressure Compensated Emitter,Button Pressure Compensation Drip,Pressure Compensation Emitter Mold
Shandong Spring Rain Water Saving Irrigation Equipment Co.,Ltd. , https://www.drippermould.com