The exterior windows of the workshop are sealed and prohibited from opening. The sealing scheme is to first press the window slit with a sealing strip and then seal all the window slits with epoxy resin. Fresh air filtration In the case of closed doors and windows, in order to ensure that the workers in the workshop breathe enough fresh air, a suction fan with a sub-high efficiency filter is installed on the four outer windows of the workshop.
The dust concentration of the inlet air (particle size >0.5"m) <300 grains / liter. The air supply can also ensure that the workshop is in a positive pressure state, preventing the outdoor dirty air from infiltrating into the workshop when the door is opened for a short time. Painted on the floor to reduce indoor dust and dust, and easy to clean. Personnel protection Workers engaged in graphite processing must wear neat work clothes and work shoes, wear work caps, masks, white gloves to reduce the cleanliness of the human body. Adverse effects (and also reduce the impact of graphite dust on the human body).
Other personnel should also wear overalls and put on shoe covers when entering the workshop. The surface cleaning graphite block of graphite is packed with polyethylene drunk fiber paper before and after processing to protect it from dust and moisture. The graphite component is purged with clean compressed air before being loaded into the core.
The graphite dust control in the three processing workshops 1 The particle size distribution of the graphite dust According to the graphite processing experts: the proportion of particles with dP> work 0pm in the graphite processed powder is >8. Therefore, we control the particle discharge and filtration in the graphite processing process. Particles larger than 100 pm are free to fall and then concentrated. We have a suction hood on each lathe (see l). The inner diameter of the suction hood is D=200Inln, and the distance from the lower edge to the surface of the graphite workpiece is x=0.12m. The suction hood passes through the suction pipe and the exhaust pipe. The wind system branches are connected.
The suction pipe is a rubber serpentine tube that can be telescopic or moved within a certain range, which is very convenient for vacuuming. A plug-in valve is installed on each branch pipe to adjust the suction amount. Suction tube cutting tool suction catcher /, long) graphite component lathe graphite processing and dust suction arrest indicating the sedimentation velocity of graphite particles Calculate the Reynolds number of particles RepRe.
The above is the theoretical calculation of u, and is the free settling velocity of the particles. Considering that the particle has an initial velocity and direction uncertainty after being cut, the suction speed vl=l.Om/s is taken to draw the graphite particles below 100"m into the exhaust dust removal system as much as possible. Expert introduction: Under the operating conditions of the ventilation system, 9.5% of the I0o graphite particles can be trapped.
The remaining 0.5% of PMlo is in an unstable state and is temporarily freed from the air, eventually being sucked or settled down. The suction air volume Q0 and the total exhaust air volume of the suction hood QD Longyi 4Q0 2 3600V: (10x+A)m3/h, where x is the distance from the lower edge of the suction hood to the graphite processing surface, x=0.12(m) , A is the suction cover area A = D is the suction hood cover inner diameter D two 0.1 (resistant.
The entire graphite component processing workshop has a total of 9 suction ports working at the same time. The total exhaust volume of the workshop is Q=9 field 2,49020 mine/h. Considering the air leakage of the ventilation system and the bag filter, the additional coefficient of the air volume is 1.15 on the day. Determine the air volume of the fan selection L2 pQ=5658m, /h. The concentration of free graphite particles is 2.6kg/h, of which PMlo has 2.6x0.2 two 0.52kg/h, which may be after the capture. The free yang 10 is 0.52xzo6xo.5% two 260omg/h.
It is known that the fresh air volume Q. of the workshop is equal to the exhaust air volume Q, that is, Qi=4920 contribution/h, and the mass concentration of free graphite particles in the air can be determined as S.=2600+4920 two 0.53 mg/m. This value is much smaller than the limit of “the maximum allowable concentration of graphite dust is 6mg/m,†as specified in national standard GB10328-89 “Sanitary Standard for Graphite Dust in Workshop Air†ts1.
Controlling the emission concentration of graphite dust The graphite dust sucked from the graphite processing machine is sent to the pulse bag type dust collector through the exhaust pipe for centralized treatment, and then discharged into the atmosphere through the chimney. This value is also far below the limit of the maximum allowable emission concentration of graphite dust specified in the national standard for industrial “three wastes†(GBJ4-73) “100mg/m3â€.
Conclusion At present, the processing task of graphite components has been successfully completed, and graphite components have been successfully used in HTR-10. All emission indicators are in line with design parameters, and graphite processing personnel are also very satisfied with the ventilation purification and dust removal effects in the workshop. Through this work, the author has accumulated experience in the design and operation of the graphite processing ventilation and dust removal system, and improved the theoretical calculation ability.
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