I have a question regarding dust-free silica
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I’m facing a headache-related problem, so I’ve come to seek advice from all of you seniors! Background: We are involved in the recovery of hydrogen-containing waste gas. This hydrogen contains silicon powder, silica, as well as some chlorosilanes. As shown in the diagram, it’s easy to capture silicon powder using bag filters; however, silica is a problem – it cannot be trapped at all. 400-mesh filter bags are essentially useless in this case. We initially considered finding the source workshop to address the issue there, but our management required us to solve it at the end point. Question: What kind of filter can filter dust and silica? Some people say that sintered filters are really great, but the problem is that while they capture silica, they also increase the system pressure difference. In fact, the operating pressure of our dust collectors is around 10 kPa, and we cannot allow too high pressures or large pressure drops; if the pressure gets too high, some of the equipment in other exhaust sections at the front end will not be able to function properly. So, have those who have used these filters any suggestions or opinions? Or does anyone who has done similar work have anything to share? Also, after adding this sintering filter, is it necessary to add other facilities simultaneously? Can devices that have already been formed be added just like those that haven’t been formed yet? Or apart from this solution, do any of you guys’ companies have any other approaches? First of all, I would like to thank everyone here; many thanks! https://bbs.hcbbs.com/forum.php?mod=image&aid=1774957&size=300x300&key=0812198b10953c05&nocache=yes&type=fixnone https://bbs.hcbbs.com/forum.php?mod=image&aid=1774958&size=300x300&key=7e8f0dc0bff0a74c&nocache=yes&type=fixnone
It is effective if a low voltage drop is desired. Gravity settling or electrostatic dust removal can be considered.
Spray dust removal is also an option to consider.
OP, are you referring to the process of using metallic silicon to produce TCS, with hydrogen being recovered in that process? To solve the problem of silica at its root, one must find the reasons for its formation. Because there can be no silica in the system for no reason. After the reaction, there are metal silicon powder and chlorosilane, and silica is produced, unless water enters the system, in which case chlorosilane hydrolyzes to form silica. To solve this problem fundamentally, you need to find ways to reduce the moisture content of the feed and lower the dew point of the gas. Rather than what to do after silicon dioxide is produced. To be honest, silica is quite difficult to deal with; from the photos of the blockage, it seems that there’s a fairly high amount of silica present. It’s probably because the moisture level wasn’t controlled properly.
There can be no silica in a polysilicon system; did it get there as a result of hydrolysis after the filter was removed?
At the source, there’s no issue with the nitrogen dew point. As for the synthesized silicon powder, even if it contains moisture, that moisture doesn’t reach our equipment. Moreover, it has been proven that the moisture content in the silicon powder is within acceptable limits. The source of moisture in the system is definitely related to processes such as reduction and cold hydrogenation. The problem is that, even though we’re aware of this, the management insists that the problem be resolved by those who receive the material from us. Personally, I’m not a fan of filters, as they can only address the issue related to silicon powder; they can’t deal with silica. Even if sintered filters could filter out silica, I’m still concerned that when silica is trapped, the system pressure will increase, and our system doesn’t allow high pressure levels. This means we’d have to consider using pulses or vibrations to handle the situation, but these methods also seem fragile and may become ineffective after just a few uses. So that’s also a headache! That’s why I’m asking if there are any better solutions!
The system should still function fine even with silica present; there might be some issues, especially when it comes to exhaust gas treatment and recovery