Pipe Cooling for Trichlorosilane Production
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Solution Overview
Problem
Cooling methods for discharge gases from fluidized-bed reactors cause aluminum chloride to solidify and adhere to pipes, leading to blockages and stress-corrosion cracking due to temperature differences.
Innovation Solution
A method involving a pipe design where a fluid, such as air or high-temperature water, flows through a space inside the pipe's side wall, maintaining a surface temperature above 110°C to prevent aluminum chloride solidification and reduce temperature gradients, thus preventing blockages and stress-corrosion cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling water is brought into contact with the side wall of the pipe to cool the discharge gas, then the discharge gas is cooled and trichlorosilane is condensed, but aluminum chloride solidifies and accumulates on the pipe causing blockage
Solution Approach 1:
The invention changes the temperature parameter of the cooling medium from low-temperature cooling water to high-temperature water (100-200°C). This parameter change prevents the pipe surface temperature from dropping below the aluminum chloride sublimation point (160°C), thereby eliminating the harmful deposition while still achieving effective cooling of the discharge gas for trichlorosilane condensation.
2Object-generated harmful factors
If high-temperature water is used to cool the discharge gas, then aluminum chloride deposition is prevented, but the pipe surface undergoes sharp temperature drop causing stress-corrosion cracking
Solution Approach 1:
The invention introduces a heating section that preheats the pipe surface before the cooling section is activated. This preliminary action ensures the pipe surface maintains sufficient temperature even when high-temperature cooling water is used, preventing thermal shock and stress-corrosion cracking while still allowing effective cooling for condensation.
3Object-generated harmful factors
If the pipe surface temperature is maintained above 110°C to prevent aluminum chloride solidification, then deposition is prevented, but cooling efficiency may be reduced
Solution Approach 1:
The invention changes the cooling medium temperature parameter to high-temperature water (100-200°C) and controls the pipe surface temperature to be 110-200°C. This parameter optimization prevents aluminum chloride deposition while maintaining sufficient temperature difference for effective heat transfer and condensation, thus balancing deposition prevention with cooling efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents aluminum chloride deposition on the pipe and reduces the risk of stress-corrosion cracking by maintaining a surface temperature above the sublimation point of aluminum chloride, ensuring continuous operation and extended pipe lifespan.
Implementation Method 1
causing a fluid to flow through a space inside a side wall of a pipe... in such a manner that the side wall has a surface with which the discharge gas flowing through the space is in contact, the surface having a temperature of not lower than 110° C.
Implementation Method 2
a means is known of (i) externally bringing high-temperature water into contact with the side wall 101 of the pipe 100 including an inner-space section 102 through which a discharge gas flows and (ii) causing the high-temperature water to evaporate, in order to cool the discharge gas.
Implementation Method 3
the method includes (i) bringing cooling water into contact with the side wall 101 to condense a discharge gas flowing through the inner-space section 102 and (ii) further condensing the above-condensed discharge gas with use of a compressor, for collection of trichlorosilane.
Data Source
AI summary
To prevent solidified aluminum chloride from adhering to and accumulating on a pipe and also prevent stress-corrosion cracking in the pipe, a method for producing trichlorosilane includes a cooling step of cooling a discharge gas that is discharged from a fluidized-bed reactor and that contains the trichlorosilane, the cooling step involving causing a fluid to flow through a space (4) inside a side wall (3) of a pipe (10), the pipe being a pipe for discharging the discharge gas from the fluidized-bed reactor, in such a manner that the side wall (3) has a surface (1a) having a temperature of not lower than 110° C.