Vacuum degassers, which are widely found in many industries such as chemical, food, pharmaceutical, electronics, etc., can efficiently remove gases from liquid or solid materials by virtue of their unique working principle.
The core working principle of vacuum degassers is based on the relationship between gas solubility and pressure and temperature, following Henry’s Law. Simply put, the solubility of a gas in a liquid at a given temperature is directly proportional to the partial pressure of that gas . When the pressure on the surface of the liquid is reduced, the solubility of the gas originally dissolved in the liquid is reduced, and it will escape in the form of bubbles, thus realising the purpose of degassing.
The key role of vacuum degasser in various industries, its stable operation is crucial. Vacuum degasser for scientific and effective maintenance as well as timely and accurate fault diagnosis, become a key link to protect the smooth progress of industrial production.
一.Points of daily maintenance
Seals check: seals are the key components to ensure the vacuum degasser vacuum, each time before use, to carefully check the degassing chamber and the pipeline connections of the seals, such as seals, gaskets, etc., to see whether there is aging, deformation, signs of damage. If the seals are found to be defective, they should be replaced in time to prevent air leakage, which will affect the vacuum degree and degassing effect. For example, in the food and beverage industry vacuum degassing production line, once the seals leak, not only will lead to incomplete degassing, affecting product quality, but also may make the outside impurities into the degassing chamber, contamination of products .
Instrumentation check: Pay close attention to the readings of the vacuum gauge, pressure gauge, temperature gauge and other types of instruments to ensure that they accurately display the operating parameters of the equipment. Check whether the instrument pointer can rotate flexibly and whether the display is clear and trouble-free. If you find the instrument reading is abnormal, it should be calibrated or replaced in time. For example, inaccurate readings of the vacuum gauge may cause the operator to misjudge the vacuum level in the degassing chamber, which may affect the degassing effect or even damage the equipment.
Equipment appearance check: Check whether there is any damage, deformation, corrosion, etc. on the appearance of the equipment, and check whether the pipeline is loose, broken, leaking and other problems. Timely cleaning of the surface of the equipment, dust, oil and other debris, to keep the equipment clean, to avoid the accumulation of debris affecting the heat dissipation of the equipment or lead to other failures. In the chemical production environment, the surface of the equipment may come into contact with a variety of corrosive chemicals, if not cleaned in a timely manner, may accelerate the corrosion of the equipment, shortening the service life of the equipment.
Operation status monitoring: In the process of equipment operation, pay attention to observe whether the equipment has abnormal sound, vibration or odour. If abnormalities are found, the machine should be shut down immediately to check, find out the reasons and solve them in time. For example, if there is a sharp friction sound when the vacuum pump is running, it may be that the parts in the pump are worn out seriously and need to be repaired or replaced in time to avoid more serious damage.
二.Regular maintenance process and method
Regular maintenance can carry out comprehensive and systematic inspection and maintenance of the equipment, effectively prevent the occurrence of potential failures and prolong the service life of the equipment, according to different time cycles, the following maintenance plan can be formulated.
Monthly maintenance: conduct a more comprehensive inspection and cleaning of the equipment every month. Use a clean cloth or brush to clean the dirt and impurities inside the degassing chamber, the inner wall of the pipeline and the surface of the filter to prevent the accumulation of dirt from affecting the degassing efficiency. Check whether the electrical connection parts are loose, make sure the wires are not broken, aging phenomenon, if there is any problem, tighten or replace them in time. Carry out simple maintenance for vacuum pump, check the oil level and oil quality of vacuum pump oil, if the oil level is too low, it should be replenished in time, and the oil quality is poor, then the vacuum pump oil needs to be replaced.
Quarterly maintenance: Every quarter, in addition to completing the items in the monthly maintenance, a more in-depth inspection of the key components of the equipment is required. Perform sealing tests on the degassing chamber, either by vacuum test method or pressure test method, to ensure good sealing performance of the degassing chamber. Check the opening and closing flexibility and sealing of the valves, if there is any stagnation or leakage phenomenon, timely repair or replacement . Calibrate all kinds of instruments to ensure that their measurement accuracy meets the requirements. Conduct a comprehensive inspection of the vacuum pump, including the pump impeller, bearings, seals, etc., and replace the parts with serious wear and tear in time to ensure the stable performance of the vacuum pump. In the electronic industry, quarterly maintenance is vital to guarantee the stable operation of vacuum degasser under the requirement of high precision, which can effectively avoid the production defects of electronic components caused by equipment failure.
Annual maintenance: Annual maintenance is the most comprehensive and in-depth maintenance work. The equipment needs to be disassembled, and each component is inspected, cleaned and maintained in detail. Replacement of all wear parts such as seals, valves, filter elements, etc. Conduct a comprehensive inspection of the degassing chamber, including wall thickness measurement, internal structure inspection, etc., to ensure that the degassing chamber is free from damage and deformation. Overhaul the vacuum pump, check and adjust the various performance parameters of the pump, and replace the worn mechanical parts, such as rotor and stator. Carry out comprehensive testing and maintenance of the electrical system, including controllers, sensors, circuit boards, etc., to ensure the reliability of the electrical system . In addition, it is also necessary to carry out a comprehensive performance test of the equipment, such as vacuum test, degassing efficiency test, etc., according to the test results of the equipment for adjustment and optimisation.
三.Common failure types and performance
1.Insufficient vacuum: this is one of the most common failures of vacuum degasser, mainly manifested as the equipment can not reach the set vacuum degree, resulting in poor degassing effect. For example, in the pharmaceutical industry, if the vacuum of the vacuum degasser is insufficient, the gas in the raw materials of the drug can not be fully removed, which may affect the purity and stability of the drug and reduce the quality of the drug. The reasons for insufficient vacuum are complicated, it may be vacuum pump failure or performance decline, such as vacuum pump internal parts wear and tear, resulting in reduced pumping capacity; it may also be pipeline sealing is poor, there is a leakage phenomenon, the air from the sealing of the joints, valves, and other parts of the system into the system, destroying the vacuum environment; in addition, the vacuum gauge is damaged or inaccurate calibration, which will make the operator misjudgment of the vacuum level, the actual vacuum and the display value does not match. The actual vacuum degree is inconsistent with the display value.
2.Low degassing efficiency: there is still a large amount of dissolved gas in the liquid treated by the equipment, which indicates that the degassing efficiency is low. In the production of food and beverage, low degassing efficiency will leave more gas in the beverage, affecting the taste and shelf life. Low degassing efficiency is mainly due to the degassing chamber temperature is too high or too low, the temperature is not appropriate will change the solubility of the gas in the liquid and escape velocity, thus affecting the degassing effect; liquid flow rate is too fast, resulting in the liquid in the degassing chamber is not fully in contact with the vacuum environment on the outflow of the gas can not escape in time; the degassing chamber internal structure is damaged or serious accumulation of scale, such as baffles in the degassing chamber, filler and other parts of the damage to the effect of gas-liquid separation, scale accumulation will prevent the gas separation Damage to the internal structure of the degassing chamber or serious accumulation of scale, such as damage to the baffle, packing and other components in the degassing chamber, affecting the gas-liquid separation effect, and the accumulation of scale will hinder the escape channel of the gas.
3.Equipment abnormal noise or vibration is too large: equipment operation produces abnormal noise or vibration, which not only affects the normal operation, but also may indicate that there are serious problems with the equipment. For example, in the large industrial circulating water system, vacuum degasser noise or vibration is too large, may interfere with the stable operation of the entire system. The reasons may be unstable installation of equipment, loose feet, resulting in equipment shaking during operation; parts wear or loose, such as vacuum pump impeller, bearing wear, loose connection bolts, etc., will produce abnormal sound and vibration during operation; motor or transmission device failure, such as motor bearing damage, belt slack or wear, etc., will also trigger abnormal vibration and noise of the equipment .
4.Liquid sucking back: after the equipment stops running, the liquid is sucked back into the vacuum pump or pipeline from the degassing chamber. In some industries that require high purity of liquid, such as the electronics industry, liquid backsiphonage may contaminate the vacuum pump and piping and damage the equipment. The causes of this kind of failure are mainly the failure or improper installation of check valves, which can not effectively stop the backflow of liquids; the unreasonable design of pipelines, with the risk of backflow, such as improperly set pipeline gradient, without the installation of the necessary backflow prevention devices, etc.
四.Diagnostic process and method
Observation phase: after the discovery of equipment anomalies, the first thing to do is to carry out a comprehensive and detailed observation. Observe the operating status of the equipment, including the vibration of the equipment, whether there is abnormal noise, whether the temperature is too high, whether the vacuum gauge and pressure gauge readings are normal, etc. . Check the appearance of the equipment to see whether there is obvious damage, deformation, leakage, etc., while paying attention to whether there is an abnormal odour or traces of liquid leakage around the equipment. For example, if the equipment shell is found to have oil stains, it may imply that there is a problem of poor sealing inside the equipment; if you smell the smell of burning, it may be a failure of the electrical system . In addition, it is necessary to observe the working environment of the equipment, such as temperature, humidity, dust and other environmental factors have an impact on the equipment, if the equipment is in a high-temperature, high humidity environment, it may accelerate the aging and corrosion of electrical components .
Detection stage: through professional tools and equipment for equipment testing, to obtain more accurate fault information. For the vacuum pump, to test its pumping performance, you can use a vacuum gauge to measure the vacuum pump’s ultimate vacuum and pumping rate, to determine whether the vacuum pump is working properly; check the sealing of the piping system, can be coated with soapy water in the piping connections, to observe whether there are bubbles, you can also use professional leakage detector detection; testing of the electrical system, the use of multimeters to measure the power supply voltage, resistance and other parameters, to check whether the electrical components are damaged, using insulated equipment to prevent damage to the electrical components. Check whether the electrical components are damaged, use insulation resistance meter to test the grounding resistance of the equipment to ensure good grounding. For the internal structure of the degassing chamber, it can be inspected by endoscope and other tools to check whether there is any accumulation of dirt, damage and so on.
Vacuum degasser as a key equipment in industrial production, in the production process of various industries play an indispensable role. From chemical to food, from pharmaceutical to electronic, each line must attach great importance to the vacuum degasser maintenance and fault diagnosis work, it will be included in the daily production management of the important links, the establishment of a perfect equipment maintenance management system. Through scientific maintenance and diagnosis, to ensure the stable operation of the vacuum degasser, to create greater economic and social benefits for the enterprise.
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