The most popular way to control vacuum pump noise

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Simple treatment of vacuum pump noise

key words: excessive noise; Cause analysis: the test method, test force, indentation length, hardness value, test force holding time, measurement times, date, time, hardness conversion value, etc. can be displayed on the screen; Governance measures; Effect

1 overview of sound field

our factory purchased a 2100 type short and long paper machine produced by Taiwan Fufa Machinery Industry Co., Ltd., and its vacuum system is equipped with four water ring vacuum pumps. During the start-up and trial production, the near-field noise value at the exhaust outlet outside the inspection workshop of Nanning health and epidemic prevention station was 86db (a). Shortly after putting into operation, in order to further save energy and reduce consumption, one of the water ring vacuum pumps with a motor power of 132kw and a model of 11e has been replaced with D36 made in mainland China × 35 roots blower (motor power 45KW). Although the exhaust noise after replacing the equipment has not been detected, it has been significantly enhanced, and it is estimated that it will not be lower than 90 ~ 92dB (a). Relevant standards stipulate that the operating noise value of industrial production equipment should be below 85dB (a), otherwise it will cause serious harm to the health of operators

2 cause analysis of excessive noise

after careful review of relevant data and on-site observation, the author believes that the main reasons for excessive exhaust noise of the vacuum system are:

(1) the four vacuum pumps are high noise source equipment, and the silencing devices are not set as required during equipment arrangement

(2) the total exhaust volume of the four vacuum pumps is 127m3/min, and the diameter of the exhaust pipe is DN150mm and DN3 respectively, two of which are 00mm until the conditioning is qualified. At the end of each exhaust pipe, a section of dn350mm pipe with a length of about 3M is used for horizontal confluence, and then it is discharged up and down through the elbows of the same diameter at both ends. This design results in the average air velocity of the exhaust confluence header of 12.9m/s

the diameter of the exhaust manifold (dn350mm) is too small, which is undoubtedly the main reason for the greatly increased exhaust noise of the vacuum pump

3 treatment measures

according to the conventional design, the most effective way to reduce the exhaust noise of vacuum pump is to make the matching intake and exhaust muffler according to the relevant technical parameters of each pump. The project budget of such a treatment scheme is about 60000 ~ 80000 yuan. And because the conventional silencing materials are easy to fail due to long-term contact with the water vapor discharged by the water ring vacuum pump, thousands of yuan of maintenance costs for vulnerable parts need to be invested every year

in order to find a more economical and effective treatment plan, in the field investigation, the author found that there was a pit covered with steel plate on the aisle outside the factory at the exhaust port of the vacuum pump of the paper machine. The pit was originally built in the factory in the early years. Until 1, it must be confirmed that the power supply is in a disconnected state, which is still a section of the entrance of the civil air defense project that is still idle today. The exhaust port of the vacuum pump of the paper machine is introduced into the pit nearby, and the pit is used as a "muffler", so the problem of excessive exhaust noise can be easily solved? In this way, how to choose an experimental machine suitable for its own characteristics for a noise reduction party with simple, low investment and good effect is a matter of concern to most users. It soon formed:

(1) remove the original dn350mm exhaust manifold and replace it with dn500mm manifold

(2) one end of the new exhaust manifold is fully enclosed welded, and the other end is vertically led to the underground with an elbow along the wall, buried and crossed the road, and finally led into the air raid shelter

(3) the outer wall of the manifold exposed to the ground shall be bound with rock wool, and the outer layer shall be coated with cement perlite powder mortar according to the process requirements of the insulated pipeline, so as to reduce the noise transmitted by the pipe wall

4 treatment effect

the above treatment plan began preliminary preparation on November 12, 1999, and completed all reconstruction and installation work on November 21. The actual total investment of the project is about 12000 yuan, which is only about one sixth of the investment of the conventional muffler scheme. After the reconstruction, the practice of startup and operation shows that the exhaust noise of the four vacuum pumps has decreased from 90dB (a) before the reconstruction to 70dB (a), which is roughly close to the range of background noise value. Although this scheme is simple, time-saving, labor-saving and material saving, it has achieved unexpected design results

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