Reduction furnace pressure difference control
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I would like to ask everyone: what impact does controlling the pressure difference between the evaporator in the reduction furnace and inside the reduction furnace have on the growth of silicon rods? What is the practical significance of pressure difference control without changing the flow rates of hydrogen and TCS?
This is a good question that deserves attention!
Let’s make an assumption: if the operating pressure of the reduction furnace is kept constant and one wishes to change (increase or decrease) the operating pressure of the evaporator, this will inevitably affect the vaporization temperature of the TCS. With the feed composition and flow rate remaining unchanged, the temperature and pressure of the feed will necessarily change. It affects the growth of silicon rods. (There is definitely an impact; I’m not sure exactly what that impact will be.) If the pressure in the evaporator is kept constant while the operating pressure of the furnace is changed, as we know, changes in the furnace’s operating pressure affect both the density and shape of the silicon rods. If two variables are changed at the same time, there will definitely be an impact. In my opinion, the significance of controlling the pressure difference lies in controlling the composition of TCS+H2 and the feeding conditions.
That’s not the case in reality; it’s not the control pressure, but rather the pressure difference. That is, the pressure difference between the evaporator and the reduction furnace, which is generally controlled by adjusting the opening degree of the valve between them. I assume that controlling the pressure difference is to ensure that the flow rate of the gas stream is fast enough. I would like to ask whether a faster gas flow rate results in denser growth of the silicon rods? Does the growth of silicon rods become looser in areas where the air flow velocity is low?