Cold hydrogenation feed method
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Please discuss in detail the advantages and disadvantages of the cold hydrogenation feeding methods: bottom feeding (using gas transport), middle feeding (under pressure and by gravity), and top feeding via an inlet sleeve.
Each method has its advantages and disadvantages; when feeding from the middle or upper part, the feeding device needs to be quite tall, while feeding from the bottom brings about problems related to gas transportation
Currently, bottom feeding is the most common method, although top feeding is also used in the synthesis of trichlorosilane. As for that form, the requirements of the manufacturing process need to be taken into account.
In the synthesis of trichlorosilane, more feed is used at the bottom, while cold hydrogenation feed is mainly applied at the middle and top levels. Several feeding methods have their own characteristics.
In my opinion, feeding from the bottom facilitates fluidization, and the silicon powder stays in the bed for a longer period of time； As for central or top feeding, fine silicon powder is easily carried away by the process gas, increasing the dust removal workload. . .
These three types of feedstock are chosen based on process conditions and pressure levels; the use of no feed at low pressures is common in the TCS synthesis process. The method of feeding depends on whether it involves a furnace of the fish-type design, and the purpose of this feeding method is to use HCl gas to boil the silicon powder, thereby facilitating the reaction. The method of feeding from the middle is less common; top feeding relies on the material’s own weight, which reduces the need for pneumatic transport, but it results in more waste of silicon powder and requires larger filters.