Automatic control method for polycrystalline silicon reduction furnace

Abstract

The invention relates to the technical field of polycrystalline silicon production, in particular to an automatic control method for a polycrystalline silicon reduction furnace, which comprises the following steps of: before the reduction furnace operates, inputting a current curve and an ideal temperature curve in an operation period of the reduction furnace into a control system of the reductionfurnace; dividing the operation period of the reduction furnace into a first stage and a second stage which respectively comprise a plurality of time points, and measuring the temperature of a silicon rod in real time at each time point; in the first stage, calculating a first compensation current according to the difference value between the measured actual temperature of the silicon rod at a certain time point and the ideal temperature corresponding to the time point on the ideal temperature curve and the current value corresponding to the time point on the current curve, so that the temperature of the surface of the silicon rod is maintained within a set temperature range; and in the second stage, calculating, by the control system, a second compensation current according to the radiation power change. According to the control method provided by the invention, the temperature of the reduction furnace in the whole production process can be accurately controlled.

Description

technical field [0001] The invention relates to the technical field of polysilicon production, in particular to an automatic control method for a polysilicon reduction furnace. Background technique [0002] For a polysilicon reduction furnace of a specific furnace type, polysilicon manufacturers often adjust the operating process parameters in combination with market demand. Generally, under certain ratio, pressure and temperature conditions of silicon-containing gas and reducing gas, the deposition efficiency of elemental silicon is certain, and under sufficient gas transportation conditions, the diameter of silicon rods can maintain a constant growth rate. Joule heat power is equal to the product of the square of the flowing current and the average resistance of the silicon rod conductor (resistivity at each point is related to temperature). As the diameter of the silicon rod increases at a constant speed, the average resistance value of the silicon rod is inversely propor...

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Problems solved by technology

However, the heat loss during the production and operation of the reduction furnace does not increase continuously with the operation time. Especially in the middle and late stages, when the diameter of the silicon rod grows to the set diameter, the radiation heat loss and convective heat loss in the reduction furnace will increase. It tends to be flat, and the existing control methods are difficult to ensure accurate control of the temperature in the entire production process of the reduction furnace

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