Local sound insulation measures for coal millDate: 2019-07-04 Views:
This paper introduces the noise generating principle and noise control method of coal mill, and selects the noise control design and device structure of making local sound insulation hood to control the noise of coal mill, and obtains good sound insulation effect, which is praised by the enterprise and workshop staff.
Coal mill is A necessary equipment for coal-fired boilers in thermal power plants, and it emits strong noise during the operation of coal mill. When multiple coal mills are running at the same time, the sound pressure level in the workshop can exceed 110dB(A), which is close to the maximum limit that human body can bear.
1. Noise source analysis of coal mill
, also called tube mill coal grinding machine is mainly composed of large tank cylinder, the size of the gear, bearing, gear, electric motor, etc. When the coal mill during, shell, raw coal mixed with steel ball, the centrifugal force and the effects of the friction cylinder bushing work was brought to a certain height, under the action of gravity to do initial velocity of free fall, falling ball impact its bottom of raw coal, the coal breaking, so coal mill noise consists of steel ball, hit each other between material and lining board and grinding, this belongs to the mechanical noise, noise radiated outward from the surface of the tank, this is the main noise source;Second, the mechanical meshing noise generated by the gear transmission part;Third, motor noise and exhaust noise generated by the motor
2. Noise control design
The noise control method of coal mill wang should adopt the following methods: 1. Put the coal mill under the sound insulation cover assembled by steel structure.(2) the use of heat resistant lining control method. The coal mill cylinder body manganese steel lining is replaced with a certain elastic heat resistant lining, reduce the impact noise of the coal mill;(3) the use of closed sound insulation room method. Put the coal mill in the civil structure sound insulation room, reduce the coal mill noise leakage;(4) the use of simple barrel bandaging method, in the coal mill barrel external bandaging some sound insulation materials, reduce the barrel radiation noise
3. Local sound insulation housing structure
3.1 design requirements
In accurate determination of the noise intensity and frequency spectrum of coal grinding machine, based on the comparison of various materials of acoustic absorption index, select the most appropriate sound absorption material, construction square local type sound insulation, sound insulation cover to fully its concrete measures are as follows: (1) the coal mill (except motor and gear) are contained in the square sound insulation cover, form overall sound insulation effect;2. The heating problem of the coal mill in the square muffler is solved by natural ventilation. That is to say, a muffler is installed directly above the muffler with a size of 1800mmx1400mmx1000mm.(3) the sound insulation door (1800mmx1000mm) and sound insulation observation window (500mmx500mm) are set on the ball side of the square sound insulation cover to facilitate the maintenance of the coal mill during operation;(4) the square sound insulation cover adopts dismountable installation, at the same time to achieve sound insulation effect, does not affect normal work, convenient maintenance, less investment, reduce noise intensity 15 ~ 18dB(A) above.
3.2 selection and use of sound insulation hood materials
The total thickness of the acoustic insulation panel is 120rmn, which is composed of 7 layers of corrugated perforated board, acoustic insulation board, sound absorbing material, acoustic insulation net, glass silk cloth, damping paint, paint and other materials
3.3 structural design
Taking local type coal mill sound insulation cover acoustic method, are the two bearing inside the coal mill building sound insulation cover, a local type coal mill in the length direction of airtight, coal grinding mechanical and electrical machine noise is beyond the scope of governance and its transmission device, it is beneficial to the coal mill for noise control, and shall not affect the coal mill and its transmission device operation and maintenance of mechanical and electrical machine. The coal mill sound insulation cover the lower part of the local type for a rectangular shape, the upper for one and a half down the cylinder, but in the big gear end significantly out of a great circle
This scheme has a good effect on noise reduction, improves the working environment of the boiler workshop, improves the working efficiency of the staff, effectively guarantees the physical and mental health of the staff, and is conducive to maintaining the operation of the equipment in the boiler workshop and eliminating the subtle safety risks.