The Research On Optimization Of Noise Reduction For The Pipeline’s Noise-reducing And Pressure-controlling Valve

In iron and steel industry, during the process of smelting iron and steel theoff-gas is produced after generating electricity through TRT device, containingcomparatively high pressure and available constituent. In addition, the mainconstituent of the off-gas is coal gas. Through the regulation of a series of commonvalves group, the high pressure gas is changed into the low-pressure gas for theresidents’ daily use. However, on the other side, the noise for the moment of openingand closing common valves to adjust the air pressure would reach95-140dB. It iswell known that the noise, doing harm to people’s health physically and mentally,has become the third most serious public hazard coming after the air pollution andwater pollution. Although constructing airtight anechoic chamber outside of thecommon valves group is helpful for controlling and reducing the noise to reach thelevel required by the relevant industry standards and regulations, the cost of landresource and construction for airtight anechoic chamber is huge. This paper focuseson developing a new valve, namely noise-reducing and pressure-controlling valve,which has effect in adjusting air pressure automatically and reducing noisesuccessfully. It is meaningful and promising in the resource conservation, emissionreduction, and environmental protection.Basis on the study of the relevant acoustic and muffler theory, we found that thenoise, namely the mechanical and aerodynamic noise, mainly comes from theprocess of opening and closing the new valve. Specifically, while opening or closingthe valve, the mechanical noise is produced by the vibration of the peripheral cavitydue to the high speed airflow impacting on the surrounding solid structure; theaerodynamic noise is produced by gas flow turbulence generated by the airflow itself.According to the micro perforated muffler noise reduction theory proposed byProfessor MA Da-you working in acoustic institute of CAS, related parameters of apractical engineering case, and a company’s application invention patent, we designthe form of structure for a new noise-reducing and pressure-controlling valve. After in-depth understanding and analysis of this engineering issue, it found thatNoise-reducing and Pressure-controlling Valve in the pipeline process have theeffect of the gas flow rate and pressure regulation and must solve the problem of bigpipe air flow and size, the right end of the pipe air flow to be adjustable, having sealeffect while it was cut off, easy to produce noise due to left side and right sidepressure difference was bigger, also it shows that the upstream pressure is210kPa inthe normal load condition, downstream pressure was19kPa, gas flow rate was300000m3/h, the working temperature was165-265℃. the structure form of thevalve is designed firstly, and then structure schematic diagrams and engineeringdrawings in details are completed, diagrams and drawings which meets therequirements of the piping system, and the size of the detailed design was that, inletpipe diameter was2020mm, thickness was18mm, inner diameter of microperforated plate was650mm, length was600mm, thickness was18mm, diameter ofupstream cavity was3000mm, length was500mm, diameter of downstream was3000mm, length was500mm. Next through the finite element method we calculatethe structure of the noise-reducing and pressure-controlling valve with one certaingeometric dimensions for obtaining the geometric dimensions in structure, such asthe suitable radius, length, thickness of micro perforated plate, aperture and porearrangement of geometry size, etc.. On the basis of all the information obtainedabove, acoustic performance simulation of noise-reducing and pressure-controllingvalve is conducted. The conclusion can be drawn that the noise-reducing andpressure-controlling valve’s noise produced in the piping system is within the scopeof the relevant industrial standard after comparing the calculation results of thesound pressure level values with the actual industrial noise standard. Moreover,acoustic performance of noise-reducing and pressure-controlling valve was acquiredthrough the fluid-structure interaction method in the finite element method foranalyzing the acoustic finite element of the noise-reducing and pressure-controllingvalve. Finally, compared the result of the acoustic performance to the noise result ofanechoic chamber outside of the common valves group, it shows that thenoise-reducing and pressure-controlling valve has more obvious advantages in theaspects of regulating the fluid pressure and reducing noise in the piping system. Onthis process, after changing the radius of the micro perforated plate and acousticfinite element analysis of the sound pressure reducing valve again, and thecalculation results and comparing the results of the post-processing with result ofthe in front valve can be learned that the changing the radius of the micro perforatedplate for noise-reducing and pressure-controlling valve has a certain degree of influence,increase the radius of the micro perforation plate can improve the effect of noisereduction of noise-reducing and pressure-controlling valve. after changing the length ofthe micro perforated plate and acoustic finite element analysis of the sound pressurereducing valve again, and the calculation results and comparing the results of thepost-processing with result of the in front valve can be learned that the changing thelength of the micro perforated plate for noise-reducing and pressure-controlling valvehas a certain degree of influence, increase the length of the micro perforation platecan improve the effect of noise reduction of noise-reducing and pressure-controllingvalve. The obtained data about mechanical properties and acoustic performance ofthe noise-reducing and pressure-controlling valve, and the relevant conclusion in thispaper will be beneficial for further developing and designing the noise-reducing andpressure-controlling valve.