The issue of exhaust gas collection in open systems
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Our factory has recently installed a low-temperature evaporation unit that covers an area of about 6 square meters. The solid waste coming out of the slag discharge outlet has a strong odor; how should we design the exhaust gas collection system? A DN80 exhaust duct was pre-installed above the machine during installation, but it is too small and lacks suction, so it’s not effective. Would it be feasible to install a large, movable exhaust hood right above the slag discharge outlet? (Fixing it might affect the operations of the technicians on site) Is it necessary to install a fan on the pipeline? I hope someone experienced can give me some advice. Thank you!
Consider using a large, movable exhaust hood installed directly above the slag discharge opening; such a design can effectively collect exhaust gases without interfering with operations. Due to the small size of the exhaust duct at DN80 and the lack of suction, it is recommended to replace it with a duct of larger diameter in order to increase air volume and suction, ensuring that the exhaust gases can be effectively removed. Additionally, to ensure that the exhaust gas under the wind shield is effectively drawn out, you should install a fan with an appropriate power rating on the pipeline. When selecting a fan, factors such as the required air volume and pressure, as well as the length and degree of bending of the ducts, need to be taken into account. Professional calculations must be carried out to select the appropriate fan, ensuring the efficient operation of the system. .
Adding a wind shield can help improve the situation; the key is to have sufficient wind power
It’s not very practical to make it airtight; the attached diagram shows that another manufacturer has used a simple cover
This wind shield needs to be larger; do I need to replace the pipes with bigger ones?
The key is the fan – it needs to have an appropriate power rating, sufficient air volume, and the right pressure; adequate power is essential. Secondly, there is the issue of the air shroud setup as well as the duct resistance
For the same reason as range hoods, this cover is too small and has weak suction power.
I have been paying attention to issues like this for a long time, and dust removal fans similar to this also have this problem. The coal crusher in the boiler system, the ash discharge equipment outdoors, and the location where the finished powder is packaged – even with fans equipped to generate high suction power, the suction effect remains poor. Similar to the range hoods in kitchens, the reason is the larger space. Either seal it off and reduce the space, or install a vacuum pump with very high power. For manufacturers, this fan cover serves more as a psychological comfort measure; it’s only useful when the cover is in place. When discharging the material, it’s very likely that the workers will still not be able to handle it. Here is a solution: air curtains at the entrances of supermarkets and restaurants can address issues related to space sealing and operational efficiency.
This effect isn’t very good; our company has tried it before as well. It’s now designed with sealed exhaust, and the results are quite good.
It’s a bit difficult to increase the suction force; at most, the fan in the spray tower can be adjusted to produce more airflow, but it’s too far away, so there probably won’t be much air pressure reaching this end.