Method for systematically controlling mobile operation post noise

Abstract

The invention discloses a method for systematically controlling mobile operation post noise. The method comprises the following steps: identifying and distinguishing noise sources of mobile operation points; determining the standard-exceeding contribution rate of each noise source of the mobile operation point to post noise, and taking the operation point noise source with the standard-exceeding contribution rate exceeding 10% as a treatment point; determining a noise abatement point location and a noise reduction target; arranging a sound insulation cover and other sound insulation facilities for the noise treatment point, determining a noise reduction material conforming to a noise reduction target, and calculating the actual sound insulation amount of the sound insulation cover; calculating the air volume required by ventilation of the acoustic shield; arranging silencers at the air inlet and the air outlet, and calculating the silencing amount; and simulating and evaluating a flow post noise control effect. According to the method, the problem of mobile post noise treatment is systematically and comprehensively solved from the aspects of source identification, treatment target determination, economic and effective selection of noise reduction materials, safe and stable operation of equipment and the like, and the problems of disorder, high cost, poor effect, secondary potential safety hazards and the like of post noise treatment are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of noise control, and in particular to a method for systematically controlling noise at mobile work stations. Background Art

[0002] Noise work refers to work in which workers are exposed to noise equivalent to a sound level ≥80dB for 8h / d or 40h / week.

[0003] At present, the types of worker jobs are mainly fixed jobs and mobile jobs. "Fixed jobs" are jobs where workers always work in the same place or a small area. Fixed job noise control can reduce job noise to below the occupational exposure limit by engineering control of clear noise sources in fixed work points or shortening the working time; "mobile jobs" are jobs where workers move around in a large area and do not have a fixed work location. There are many noise equipment and noise sources involved during the movement of these jobs. There is no effective way to control the noise of mobile jobs, that is, the 8h equivalent A sound level. It often happens that the noise of mobile jobs still exceeds the standard after engineering control, which is mainly manifested as:

[0004] 1. Only focus on equipment noise control, not job noise control. From the perspective of protecting workers' occupational health and national occupational exposure limits, there are no relevant requirements for equipment noise, but there is an occupational exposure limit of 85dB(A) for job noise, which is the 8h equivalent A sound level. Therefore, the protection of workers' health cannot only look at the intensity of equipment noise, but also the intensity of noise exposure of workers in this position-whether the 8h equivalent A sound level exceeds the occupational exposure limit of 85dB(A). The level of the 8h equivalent A sound level is related to the level of equipment noise and the length of time workers are exposed to noise. Controlling equipment noise may not necessarily reduce job noise to below the occupational exposure limit.

[0005] 2. The overlapping influence of noise sources leads to inaccurate identification, resulting in incomplete or inaccurate treatment. After treating one or several high noise sources that the mobile post is exposed to, it is found that there are other high noise sources around, causing the noise of the mobile post to still exceed the standard.

[0006] 3. It is impossible to accurately screen the noise source that contributes most to the excessive noise, resulting in the mobile post noise still exceeding the standard after treatment. Whether the mobile post noise exceeds the standard is determined by the noise intensity of each work point and the work residence time. If the noise source with the highest noise intensity has a very short residence time and the second highest noise source has a very long residence time, then the second highest noise source may be the point that contributes most to the excessive noise of the post and should be treated first; but the company gave priority to treating the noise source with the highest noise intensity and the shortest contact time, and as a result, the mobile post noise may still exceed the standard. Considering the economic cost, it is impossible for the company to treat all the noise sources at all mobile work points.

[0007] 4. The selection of noise reduction material parameters in noise control is relatively simple. It often happens that no matter whether the intensity of the noise source to be controlled is high or low, the sound absorption and sound insulation materials with the same noise reduction parameters are selected for combination. In the end, a combination of materials with low sound insulation parameters may be used to soundproof and reduce the high noise source, and the effect is not up to standard.

[0008] 5. The ventilation and heat dissipation of the soundproof enclosure is poor, and the safe and stable operation of the equipment is not guaranteed. The closed enclosure has a good sound insulation and noise reduction effect, but most of the closed soundproof enclosures on the market have poor ventilation and heat dissipation effects. In summer, the temperature inside the soundproof enclosure is 60°C or even higher, which leads to the failure of lubricating oil and damage to important components such as motors and bearings. In order to prevent high-temperature damage to the equipment, some companies choose to open the inspection door of the soundproof enclosure for convection ventilation, which causes the soundproof enclosure to lose its sound insulation effect and the noise of mobile posts exceeds the standard.

[0009] 6. The above four problems exist simultaneously in the process of noise control at mobile posts, which seriously affects the effect, cost and safe and stable operation of equipment of noise control at mobile posts. Summary of the invention

[0010] In view of the problems existing in the above-mentioned prior art, the present invention proposes a method for systematically controlling noise in mobile work positions, which has a reasonable design, overcomes the shortcomings of the prior art, and has good effects.

[0011] In order to achieve the above object, the present invention adopts the following technical solution:

[0012] A method for systematically controlling noise at mobile workstations, comprising the following steps:

[0013] S1. Identify and distinguish the noise sources at the mobile operation points;

[0014] S2. Determine the contribution rate of each noise source at the mobile operation point to the excessive noise at the post, sort them by the contribution rate, and take the noise source at the operation point where the contribution rate exceeds 10% as the control point;

[0015] S3. Determine the noise control points and noise reduction targets, and predict the noise control effects at mobile posts;

[0016] S4. Set up a soundproof enclosure for the noise control point, determine the noise reduction materials that meet the noise reduction target, and calculate the actual sound insulation of the soundproof enclosure;

[0017] S5. The soundproof enclosure is provided with air inlets and air outlets for ventilation and heat dissipation, and the air volume required for ventilation of the soundproof enclosure is calculated;

[0018] S6. Install silencers at the air inlet and outlet, and calculate the sound reduction capacity;

[0019] S7. Simulate and evaluate the noise control effect at mobile posts.

[0020] Furthermore, based on the beamforming principle, an acoustic imager is used to perform far-field and near-field acoustic imaging of the centrally arranged high-noise equipment. Far-field acoustic imaging distinguishes the noise intensity of each noisy device, and near-field acoustic imaging identifies the noise source of a single noisy device.

[0021] Furthermore, in S2, calculating the contribution rate of noise exceeding the standard at each mobile operation point includes the following sub-steps:

[0022] S21. Calculate the allowable noise contact time T for each mobile operation point i ′:

[0023]

[0024] Among them, L Aeq,Ti T for each mobile operation point i Equivalent continuous A-weighted sound pressure level during the time period;

[0025] T i It is the actual noise exposure time of a single mobile operation point;

[0026] S22. Calculate the single point exposure dose at each mobile operation point:

[0027]

[0028] S23. Calculate the contribution rate of noise exceeding the standard at each mobile operation point:

[0029]

[0030] Furthermore, in S3, all mobile operation points with an excess contribution rate exceeding 10% are adjusted in descending order of excess contribution rate. Aeq,Ti Then substitute the value into formula (4):

[0031]

[0032] Among them, L Aeq,T Indicates the equivalent sound level throughout the day;

[0033] Indicates the equivalent continuous A-weighted sound pressure level in the time period Ti;

[0034] T represents the total time of these time periods;

[0035] Ti represents the time of time period i;

[0036] n represents the total number of time periods;

[0037] Calculate the 8h equivalent sound level:

[0038]

[0039] Among them, L EX,8h The noise intensity during the actual working hours of a day is normalized to the equivalent sound level of working for 8 hours;

[0040] T e The working hours are the actual working hours on the working day;

[0041] L Aeq,Te is the equivalent sound level of an actual working day;

[0042] T0 is the standard working day time;

[0043] If L EX,8h <85dB(A), then the noise level of each mobile operation point after adjustment L Aeq,Ti The value is used as the noise reduction target value. If L EX,8h >85dB(A), then continue to adjust the noise L Aeq,Ti Value, up to L EX,8h <85dB(A).

[0044] Furthermore, in S4, the following sub-steps are included:

[0045] S41. Specify the actual sound insulation of the proposed soundproof enclosure at each noise control point, which is equal to the noise L of the operation point where the contribution rate of the noise standard exceeds 10% before the control. Aeq,Ti Value - adjusted noise L of the operation point with an excess contribution rate of more than 10% Aeq,Ti Numeric value;

[0046] S42. Select parameters of various sound insulation materials according to the actual sound insulation amount to be selected, including the thickness of the steel plate, the surface density of glass wool and rock wool;

[0047] S43, substituting the selected sound insulation material parameters into the theoretical average sound insulation calculation formula, and adjusting the parameters until the actual sound insulation IL meets the actual sound insulation requirements of the proposed sound insulation cover;

[0048] Furthermore, in S43, the theoretical average sound insulation formula is:

[0049]

[0050] m is the surface density of the sound insulation material;

[0051] The actual sound insulation formula is:

[0052]

[0053] in, is the average sound absorption coefficient of the sound absorbing material.

[0054] Furthermore, in S5, the air volume required for ventilation and heat dissipation in the soundproof enclosure is calculated:

[0055]

[0056] Among them, Q is the waste heat generated by the generator, supercharger, and oil station dynamic equipment;

[0057] C is the mass specific heat of air, and its value is: 1.01 kJ / kg·℃;

[0058] l is the density of air 1.29kg / m 3 ;

[0059] t p Allowable air temperature for indoor or hood;

[0060] t0 is the outdoor or hood air temperature;

[0061] Further,

[0062]

[0063] Where, η is the motor power;

[0064] P is the rated power of the working machine.

[0065] Further, in S6, the sound attenuation requirement is determined according to the actual sound insulation value, and the length and width of the sound attenuation section, the effective sound attenuation length and the sound absorbing material parameters of the designed single-channel muffler are substituted into the following formula to calculate the sound attenuation ΔL:

[0066]

[0067] in, is the sound attenuation coefficient;

[0068] is the average sound absorption coefficient;

[0069] P is the circumference of the anechoic section;

[0070] S is the cross-sectional area of ​​a single silencing channel;

[0071] L is the effective length of the silencing channel;

[0072] Determine whether the noise reduction volume ΔL meets the noise reduction volume requirement. If not, continue to adjust the parameters of the silencer until ΔL meets the noise reduction volume requirement.

[0073] Use the following formula to determine whether the airflow regeneration noise affects the noise reduction effect:

[0074]

[0075] LW =(18±2)+60×logV; (12)

[0076] Among them, L W is the sound power level of the muffler airflow regeneration noise A;

[0077] T is the cross-sectional area of ​​the total silencing channel;

[0078] T = S × R, R is the number of anechoic channels;

[0079] v is the air velocity in the muffler;

[0080] V is the air volume required for ventilation and heat dissipation in the soundproof enclosure;

[0081] If L W If the sound pressure level A of the noise source is greater than that of the actual sound pressure level A after the silencer is installed, the cross-sectional area of ​​a single silencer channel or the number of silencer channels should be adjusted until L W It is smaller than the actual sound pressure level A of the noise source after installing the muffler.

[0082] Furthermore, the sound field simulation software Canada A was used to simulate the sound field environment of the mobile post to determine the noise control situation of each work point in the mobile post, Simcenter 3D was used to simulate the sound insulation and silencing effects of acoustic components, and the motion flow field simulation software ANSYS FLUENT was used to simulate the flow field of ventilation and heat dissipation. After simulation, if the sound insulation cover and silencer can achieve the equipment noise reduction target, the ventilation and heat dissipation of the sound insulation cover has no effect on the safe and stable operation of the equipment, the noise of the work point with an excessive contribution rate of more than 10% is effectively controlled, and the noise of the mobile post is controlled within 85dB (A), then the designed sound insulation cover and silencer will be applied to the actual mobile post.

[0083] Beneficial technical effects brought by the present invention:

[0084] (1) Accurately identify noise sources and locate the source of treatment to avoid incorrect selection of treatment targets and failure to meet standards;

[0085] (2) Accurately screen out the noise sources that contribute most to the exceeding of the standard, and rank the contribution rate of each noise source at the patrol mobile work point to the exceeding of the standard, clarify the control order and focus, determine the noise reduction target value of the control point and predict the noise control effect of the mobile post, so as to avoid blind and ineffective selection of post noise control objects;

[0086] (3) Determine the noise reduction materials that meet the noise reduction goals, ensuring both noise reduction effect and economic efficiency, and avoiding the situation where the noise reduction materials are effective but costly or low-cost but ineffective;

[0087] (4) Solve the ventilation and heat dissipation problems of the closed soundproof enclosure, reduce noise while ensuring the safe and stable operation of the equipment, and avoid opening the inspection door of the soundproof enclosure for ventilation for a long time due to concerns that ventilation and heat dissipation will affect the safe and stable operation of the equipment, resulting in the noise reduction effect not meeting the standard;

[0088] (5) Systematically and comprehensively address the noise control issues at mobile workplaces from the aspects of source identification, control target determination, economical and effective selection of noise reduction materials, and ensuring safe and stable operation of equipment, so as to avoid the problems of disorderly, high-cost, poorly effective, and secondary safety hazards in workplace noise control. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 It is a flow chart of a method for systematically controlling noise at mobile work stations in the present invention; DETAILED DESCRIPTION

[0090] The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0091] The terms used in this disclosure are for the purpose of describing characteristic embodiments only and are not intended to limit the disclosure. The singular forms "a", "the" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0092] The specific implementation of the present invention is further described below in conjunction with specific embodiments:

[0093] A systematic method for controlling noise in mobile workstations, such as Figure 1 As shown, the following steps are included:

[0094] S1. Identify and distinguish the noise sources at the mobile operation points;

[0095] It is mainly aimed at high-noise equipment that is relatively concentrated, affects each other, has high background noise, and is difficult to distinguish the noise intensity of a single noise device. According to the principle of beamforming, an acoustic imager is used to perform far-field and near-field acoustic imaging on the concentrated high-noise equipment. Far-field acoustic imaging distinguishes the noise intensity of each noise device, and near-field acoustic imaging identifies the noise source of a single noise device;

[0096] S2. Determine the contribution rate of each noise source at the mobile operation point to the excessive noise at the post, clarify the control order and focus, sort them by the contribution rate, and the noise source at the operation point with an excessive contribution rate of more than 10% shall be the control point;

[0097] Calculating the contribution rate of noise exceeding the standard at each mobile operation point includes the following sub-steps:

[0098] S21. Calculate the allowable noise contact time T for each mobile operation point i ′:

[0099]

[0100] Among them, L Aeq,Ti T for each mobile operation point i Equivalent continuous A-weighted sound pressure level during the time period;

[0101] T i It is the actual noise exposure time of a single mobile operation point;

[0102] S22. Calculate the single-point exposure dose at each mobile operation point: the actual noise exposure time T of a single operation point i Divide by the allowable contact time T of noise at a single operating point i ′;

[0103]

[0104] S23. Calculate the contribution rate of noise exceeding the standard at each mobile operation point:

[0105]

[0106] S3. Determine the noise control points and noise reduction targets, and predict the noise control effects at mobile posts;

[0107] Adjust the noise L of all mobile operation points whose contribution rate exceeds 10% in descending order according to the contribution rate of exceeding the standard. Aeq,Ti Then substitute the value into formula (4):

[0108]

[0109] In a workplace with non-steady-state noise, divide the working hours of a day into n time periods according to the principle of similar sound levels, and use an integrating sound level meter to measure the equivalent sound level L of each time period. Aeq,Ti , calculate the equivalent sound level for the whole day according to formula (4);

[0110] Among them, L Aeq,T Indicates the equivalent sound level throughout the day;

[0111] Indicates the equivalent continuous A-weighted sound pressure level in the time period Ti;

[0112] T represents the total time of these time periods;

[0113] Ti represents the time of time period i, without any change;

[0114] n represents the total number of time periods;

[0115] Calculate the 8h equivalent sound level:

[0116]

[0117] According to the equal energy principle, the noise intensity during the actual working hours of a day is normalized to the equivalent sound level of working for 8 hours and calculated according to formula (5);

[0118] Among them, L EX,8h The noise intensity during the actual working hours of a day is normalized to the equivalent sound level of working for 8 hours;

[0119] T e The working hours are the actual working hours on the working day;

[0120] L Aeq,Te is the equivalent sound level of an actual working day;

[0121] T0 is the standard working day time;

[0122] If L EX,8h <85dB(A), then the noise level of each operation point after adjustment L Aeq,Ti The value is used as the noise reduction target value. If L EX,8h >85dB(A), then continue to adjust the noise L Aeq,Ti Value, up to L EX,8h <85dB(A).

[0123] S4. Determine the noise reduction materials that meet the noise reduction goals;

[0124] In S4, the following sub-steps are included:

[0125] S41. Clarify the actual sound insulation of the proposed soundproof enclosures at each noise control point: The noise level of the operation point where the contribution rate of the noise standard exceeds 10% before control L Aeq,Ti Value - adjusted noise L of the operation point with an excess contribution rate of more than 10% Aeq,Ti Numeric value;

[0126] S42. Select the parameters of each sound insulation material according to the actual sound insulation combination to be selected, including the thickness of the steel plate, the surface density of glass wool and rock wool, etc., and ultimately effectively reduce noise on the basis of ensuring economic rationality;

[0127] S43, substituting the selected surface density parameter of the sound insulation material into the sound insulation calculation formula, adjusting the surface density parameter until the actual sound insulation IL meets the actual sound insulation requirement of the proposed sound insulation cover, that is, the insertion loss value;

[0128] Theoretical average sound insulation formula:

[0129]

[0130] Actual sound insulation formula:

[0131]

[0132] in, is the average sound absorption coefficient of the sound absorbing material.

[0133] S5. Calculate the air volume required for ventilation of the closed soundproof enclosure;

[0134] Since moving equipment generally generates a lot of heat, the ventilation and heat dissipation of the equipment needs to be considered when setting up a closed soundproof enclosure. The air volume required for ventilation and heat dissipation in the soundproof enclosure is calculated according to the following:

[0135]

[0136] Among them, Q is the waste heat generated by the generator, supercharger, and oil station dynamic equipment;

[0137] C is the mass specific heat of air, and its value is: 1.01 kJ / kg·℃;

[0138] l is the density of air 1.29kg / m 3 ;

[0139] t p Allowable air temperature for indoor or hood;

[0140] t0 is the outdoor or hood air temperature;

[0141] Usually there are:

[0142]

[0143] Where, η is the motor power;

[0144] P is the rated power of the working machine;

[0145] In the above formula, t p According to the "Design Code for Heating, Ventilation and Air Conditioning of Industrial Buildings" (GB50019-2012), t0 is selected according to the outdoor calculated temperature of summer ventilation in the project area, t p Select the temperature based on the allowable temperature of the production plant work location in summer in the area where the project is located.

[0146] S6. Design the muffler;

[0147] The closed soundproof enclosure needs to be ventilated and heat-dissipated, so holes need to be opened in the shell of the soundproof enclosure, and mechanical air inlets and exhaust ports are set for ventilation and heat dissipation. In order to prevent the noise inside the soundproof enclosure from leaking to the outside of the soundproof enclosure through the air inlet and exhaust ports, a muffler is set at the air inlet and exhaust ports, which ensures both ventilation and heat dissipation and noise reduction effects.

[0148] Determine the sound reduction requirement based on the actual sound insulation value, and substitute the length and width of the sound reduction section, effective sound reduction length and sound absorption material parameters of the designed single-channel muffler into the following formula to calculate the sound reduction:

[0149]

[0150] in, is the sound attenuation coefficient, is the average sound absorption coefficient, P is the circumference of the silencing section, S is the cross-sectional area of ​​the silencing channel, and L is the effective length of the silencing channel;

[0151] Determine whether the noise reduction volume ΔL meets the noise reduction volume requirement. If not, continue to adjust the parameters of the muffler until ΔL meets the noise reduction volume requirement.

[0152] Use the following formula to determine whether the airflow regeneration noise affects the noise reduction effect:

[0153]

[0154] L W =(18±2)+60×logV; (12)

[0155] Among them, L W is the sound power level of the silencer airflow regeneration noise A, T is the total silencer channel cross-sectional area, T = S × R, R is the number of silencer channels, v is the airflow velocity in the silencer, and V is the air volume required for ventilation and heat dissipation in the soundproof enclosure;

[0156] If L W If the sound pressure level A of the noise source is greater than that of the actual sound pressure level A after the silencer is installed, the cross-sectional area of ​​a single silencer channel or the number of silencer channels should be adjusted until L W It is smaller than the actual sound pressure level A of the noise source after installing the muffler.

[0157] S7. Simulation of noise control effect at mobile posts;

[0158] The sound field simulation software Canada A is used to simulate the sound field environment of mobile posts to determine the noise control situation of each work point in the mobile posts. Simcenter 3D is used to simulate the sound insulation and silencing effects of acoustic components. The motion flow field simulation software ANSYS FLUENT is used to simulate the flow field of ventilation and heat dissipation. After simulation, if the sound insulation cover and silencer can achieve the equipment noise reduction target, the ventilation and heat dissipation of the sound insulation cover has no effect on the safe and stable operation of the equipment, the noise at the work point with an excessive contribution rate of more than 10% is effectively controlled, and the noise of the mobile posts is controlled within 85dB (A), then the designed sound insulation cover and silencer will be applied to the actual mobile posts.

[0159] Effect evaluation after implementation. After the noise control of mobile posts, the equivalent A sound level (L EX,8h )<85dB(A), the temperature rise inside and outside the soundproof enclosure is <5℃.

[0160] Embodiment 1:

[0161] The external operator of a 300,000-ton hydrogenation unit in operation is a mobile post with a total of 10 operating points. The operating shift system is four shifts and three operations. At present, the noise level of this mobile post is L EX,8h =94.27dB(A) greater than 85dB(A) - the occupational exposure limit required by "Occupational Exposure Limits for Hazardous Factors in the Workplace - Physical Factors" (GBZ2.2-2007), which requires the noise of the mobile post to be reduced to below 85dB(A).

[0162] S1. Clearly define the location of each mobile operation point;

[0163] Through on-site investigation, the inspection route of the mobile post is as follows: external operation room - high pressure pump room - first floor of compressor plant - second floor of compressor plant - lean amine liquid high pressure pump room - reaction feed pump room - hot oil pump room - cold oil pump room - oil transfer pump area - external operation room;

[0164] Identification of noise sources at each mobile operation point;

[0165] By using an acoustic imager, we can identify the far-field sound source of each work point, identify the difference in noise intensity of the noise equipment involved in each work point, and clarify which 90dB(A) high-noise equipment has the greatest impact on job site noise; use the near field to accurately identify the noise source of the determined high-noise equipment, and clarify the location of the noise source and the noise spectrum of the high-noise equipment;

[0166] After effective identification of high noise equipment and noise sources at each operation point, the following table shows:

[0167] Table 1 High noise equipment and noise source identification

[0168] Serial number Work Point High noise equipment Noise Source 1 High pressure pump room High pressure pump Couplings 2 Compressor plant compressor Drainage port 3 Compressor plant second floor compressor Drainage port 4 Lean amine liquid high pressure pump room Lean amine pump Couplings 5 Reaction feed pump room Reaction feed pump Motor 6 Hot oil pump room Hot oil pump Couplings 7 Cold oil pump room Oil Pump Motor 8 Oil pump area Oil pump Motor

[0169] S2. Calculate the excess contribution rate according to formulas (1), (2) and (3).

[0170]

[0171] Among them, L Aeq,Ti T for each mobile operation point i Equivalent continuous A-weighted sound pressure level during the time period;

[0172]

[0173]

[0174] The excess contribution rate is shown in Table 2;

[0175] Table 2 Contribution rate of exceeding the standard

[0176]

[0177] S3, determine the noise reduction target;

[0178] The operating points with the excess contribution rate exceeding 10% are the high-pressure pump room and the lean amine pump room, which are 73.85% and 18.46% respectively. The adjusted values ​​are substituted into formulas (4) and (5) to calculate the noise values ​​of the two operating points until L EX,8h <85dB(A);

[0179]

[0180] Among them, L Aeq,T Indicates the equivalent sound level throughout the day;

[0181] Indicates the equivalent continuous A-weighted sound pressure level in the time period Ti;

[0182] T represents the total time of these time periods;

[0183] Ti represents the time of time period i, without any change;

[0184] n represents the total number of time periods;

[0185] Calculate the 8h equivalent sound level:

[0186]

[0187] See Table 3 for details;

[0188] Table 3 Noise reduction targets

[0189]

[0190] S4. Determine the noise reduction materials that meet the noise reduction goals;

[0191] According to Table 3, the noise reduction target for the high-pressure pump room should be >108-85=23dB(A), and the noise reduction target for the lean amine liquid high-pressure pump room should be >102-85=17dB(A). In order to reduce the noise intensity at the workplace, it is necessary to reduce the time that workers are exposed to noise hazards. Therefore, soundproof covers are set up for high-pressure pumps, lean amine liquid high-pressure pumps and other equipment to reduce the number of workers entering. Select the material and substitute the material parameters into formulas (6) and (7) to calculate the actual sound insulation of the soundproof cover;

[0192] The theoretical average sound insulation formula is:

[0193]

[0194] m is the surface density of the sound insulation material;

[0195] The actual sound insulation formula is:

[0196]

[0197] in, is the average sound absorption coefficient of the sound absorbing material.

[0198] As shown in Table 4:

[0199] Table 4 Noise reduction material selection

[0200]

[0201] S5, soundproof enclosure with closed ventilation and heat dissipation design;

[0202] The design dimensions of the soundproof enclosures for the high-pressure pump and the lean amine liquid pump are 2.5m*4m*3.5m(h) and 2.3m*3m*4m(h) respectively; the rated power P of the high-pressure pump motor is 800kW, the motor efficiency η is 94.8%, the temperature difference between the inside and outside of the soundproof enclosure is less than 5℃, and the ventilation heat exchange is calculated by substituting into formulas (8) and (9) to obtain a heat exchange of 24435.37m3 / h; the rated power P of the lean amine liquid pump motor is 630kW, the motor efficiency η is 94.4%, the temperature difference between the inside and outside of the soundproof enclosure is less than 5℃, and the ventilation heat exchange is calculated by substituting into formulas (8) and (9) to obtain a heat exchange of 20810.89m3 / h.

[0203] Calculate the air volume required for ventilation and heat dissipation in the soundproof enclosure:

[0204]

[0205] Among them, Q is the waste heat generated by the generator, supercharger, and oil station dynamic equipment;

[0206] C is the mass specific heat of air, and its value is: 1.01 kJ / kg·℃;

[0207] l is the density of air 1.29kg / m 3 ;

[0208] t p Allowable air temperature for indoor or hood;

[0209] t0 is the outdoor or hood air temperature;

[0210]

[0211] Where, η is the motor power;

[0212] P is the rated power of the working machine.

[0213] S6. Design of ventilation muffler for soundproof enclosure;

[0214] According to the noise reduction of 23dB(A) for the high-pressure pump and 17dB(A) for the lean amine pump, the effective length of the silencer channel, the length and width of the single silencer channel section and the sound-absorbing material parameters are designed, and the parameters are substituted into formula (10) to calculate the noise reduction; the number of silencer channels and whether the airflow regeneration noise affects the noise reduction effect are determined by formulas (11) and (12). Finally, a silencer with an effective silencer length of 1000mm, a length and width of 800*100mm, 10 silencer channels, a silencer sheet thickness of 100mm, and an average sound absorption coefficient of 0.8 is selected. The airflow velocities of the silencer channels of the high-pressure pump and the lean amine pump are 8.5m / s and 7.2m / s respectively, and the maximum airflow regeneration noise is 75.7dB(A) and 71.4dB(A) respectively, which is much smaller than the noise reduction target of the soundproof cover, ensuring that the silencer can achieve a noise reduction of 27dB(A), and the noise reduction effect is not lower than that of the soundproof cover with a noise reduction of 25.3dB.

[0215] Noise reduction ΔL:

[0216]

[0217] in, is the sound attenuation coefficient;

[0218] is the average sound absorption coefficient;

[0219] P is the circumference of the anechoic section;

[0220] S is the cross-sectional area of ​​a single silencing channel;

[0221] L is the effective length of the silencing channel;

[0222]

[0223] L W =(18±2)+60×logV; (12)

[0224] Among them, LW is the sound power level of the muffler airflow regeneration noise A;

[0225] T is the cross-sectional area of ​​the total silencing channel;

[0226] T = S × R, R is the number of anechoic channels;

[0227] v is the air velocity in the muffler;

[0228] V is the air volume required for ventilation and heat dissipation in the soundproof enclosure;

[0229] S7. Simulation of noise control effect at mobile posts;

[0230] The sound field simulation software Canada A should be used to simulate the sound field environment of mobile posts to confirm the noise control situation of each work point in the mobile posts, Simcenter 3D should be used to simulate the sound insulation and noise reduction effects of acoustic components, and the flow field simulation software ANSYS FLUENT should be used to simulate the flow field of ventilation and heat dissipation. After simulation, the sound insulation and noise reduction acoustic components can achieve the equipment noise reduction target, the ventilation and heat dissipation of the sound insulation cover has no effect on the safe and stable operation of the equipment, the noise of the work points with a contribution rate of more than 10% exceeding the standard is effectively controlled, and the noise of mobile posts can be controlled within 85dB (A).

[0231] S8. Evaluation of the effectiveness of the implementation of systematic noise control in mobile posts;

[0232] After the noise control of mobile workstations, the 8-hour equivalent A-level sound level (LEX,8h) of the workstation noise measured using an individual sound level meter was 83.4dB(A), and the temperature rise inside and outside the soundproof enclosure was about 3°C.

[0233] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for systematically controlling noise at mobile workstations, characterized in that: The following steps are involved: S1. Identify and distinguish the noise sources at the mobile operation points; S2. Determine the contribution rate of each noise source at the mobile operation point to the excessive noise at the post, sort them by the contribution rate, and take the noise source at the operation point where the contribution rate exceeds 10% as the control point; S3. Determine the noise control points and noise reduction targets, and predict the noise control effects at mobile posts; S4. Set up a soundproof enclosure for the noise control point, determine the noise reduction materials that meet the noise reduction target, and calculate the actual sound insulation of the soundproof enclosure; S5. The soundproof enclosure is provided with air inlets and air outlets for ventilation and heat dissipation, and the air volume required for ventilation of the soundproof enclosure is calculated; S6. Install silencers at the air inlet and outlet, and calculate the sound reduction capacity; S7. Simulate and evaluate the noise control effect at mobile posts.

2. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: Based on the principle of beamforming, an acoustic imager is used to perform far-field and near-field acoustic imaging of centrally arranged high-noise equipment. Far-field acoustic imaging distinguishes the noise intensity of each noisy device, while near-field acoustic imaging identifies the noise source of a single noisy device.

3. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: In S2, calculating the contribution rate of noise exceeding the standard at each mobile operation point includes the following sub-steps: S21. Calculate the allowable noise contact time T for each mobile operation point i ′: Among them, L Aeq,Ti T for each mobile operation point i Equivalent continuous A-weighted sound pressure level during the time period, T i It is the actual noise exposure time of a single mobile operation point; S22. Calculate the single point exposure dose at each mobile operation point: S23. Calculate the contribution rate of noise exceeding the standard at each mobile operation point:

4. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: In S3, all mobile operation points with an excess contribution rate exceeding 10% are adjusted in descending order of excess contribution rate. Aeq,Ti Then substitute the value into formula (4): Among them, L Aeq,T Represents the equivalent sound level throughout the day, It represents the equivalent continuous A-weighted sound pressure level in time period Ti, T represents the total time of these time periods, Ti represents the time of time period i, and n represents the total number of time periods; Calculate the 8h equivalent sound level: Among them, L EX,8h The noise intensity during the actual working hours of a day is normalized to the equivalent sound level of 8 hours of work, T e is the actual working time of the working day, L Aeq,Te is the equivalent sound level of an actual working day, and T0 is the standard working day time; If L EX,8h <85dB(A), then the noise level of each mobile operation point after adjustment L Aeq,Ti The value is used as the noise reduction target value. If L EX,8h >85dB(A), then continue to adjust the noise L Aeq,Ti Value, up to L EX,8h <85dB(A).

5. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: In S4, the following sub-steps are included: S41. Specify the actual sound insulation of the proposed soundproof enclosure at each noise control point, which is equal to the noise L of the operation point where the contribution rate of the noise standard exceeds 10% before the control. Aeq,Ti Value - adjusted noise L of the operation point with an excess contribution rate of more than 10% Aeq,Ti Numeric value; S42. Select parameters of various sound insulation materials according to the actual sound insulation amount to be selected, including the thickness of the steel plate, the surface density of glass wool and rock wool; S43. Substitute the selected sound insulation material parameters into the theoretical average sound insulation calculation formula, and adjust the parameters until the actual sound insulation IL meets the actual sound insulation requirements of the proposed sound insulation cover.

6. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: In S43, the theoretical average sound insulation formula is: m is the surface density of the sound insulation material; The actual sound insulation formula is: in, is the average sound absorption coefficient of the sound absorbing material.

7. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: In S5, calculate the air volume required for ventilation and heat dissipation in the soundproof enclosure: Among them, Q is the waste heat generated by the generator, supercharger, and oil station dynamic equipment, C is the mass specific heat of air, its value is: 1.01kJ / kg·℃, l is the density of air 1.29kg / m 3 , t p is the allowable air temperature indoors or inside the hood, and t0 is the outdoor or outside air temperature.

8. A method for systematically controlling noise at mobile workstations according to claim 7, characterized in that: Among them, η is the motor power and P is the rated power of the working machine.

9. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: In S6, the sound reduction requirement is determined according to the actual sound insulation value, and the length and width of the sound reduction section, the effective sound reduction length and the sound absorption material parameters of the designed single-channel muffler are substituted into the following formula to calculate the sound reduction ΔL: in, is the sound attenuation coefficient, is the average sound absorption coefficient, P is the perimeter of the silencing section, S is the cross-sectional area of ​​a single silencing channel, and L is the effective length of the silencing channel; Determine whether the noise reduction volume ΔL meets the noise reduction volume requirement. If not, continue to adjust the parameters of the muffler until ΔL meets the noise reduction volume requirement. Use the following formula to determine whether the airflow regeneration noise affects the noise reduction effect: L W =(18±2)+60×logV; (12) Among them, L W is the sound power level of the silencer airflow regeneration noise A, T is the total silencer channel cross-sectional area, T = S × R, R is the number of silencer channels, v is the airflow velocity in the silencer, and V is the air volume required for ventilation and heat dissipation in the soundproof enclosure; If L W If the sound pressure level A of the noise source is greater than that of the actual sound pressure level A after the silencer is installed, the cross-sectional area of ​​a single silencer channel or the number of silencer channels should be adjusted until L W It is smaller than the actual sound pressure level A of the noise source after installing the muffler.

10. A method for systematically controlling noise at mobile workstations according to claim 1, characterized in that: The sound field simulation software Canada A is used to simulate the sound field environment of mobile posts to determine the noise control situation of each work point in the mobile posts. Simcenter 3D is used to simulate the sound insulation and silencing effects of acoustic components. The motion flow field simulation software ANSYSFLUENT is used to simulate the flow field of ventilation and heat dissipation. After simulation, if the sound insulation cover and silencer can achieve the equipment noise reduction target, the ventilation and heat dissipation of the sound insulation cover has no effect on the safe and stable operation of the equipment, the noise of the work point with an excessive contribution rate of more than 10% is effectively controlled, and the noise of the mobile posts is controlled within 85dB (A), then the designed sound insulation cover and silencer will be applied to the actual mobile posts.

Images