Polycrystalline silicon reduction furnace control method

Abstract

The invention relates to the technical field of polycrystalline silicon material preparation, in particular to a polycrystalline silicon reduction furnace control method. The method comprises the following steps: determining a polycrystalline silicon rod temperature reference curve; determining a temperature characterization function f (T) of the polycrystalline silicon rod; calculating an instant temperature Ti through a silicon rod temperature characterization function f (T), and comparing the instant temperature Ti with a silicon rod temperature reference curve; and if the temperature difference value exceeds the set range value, the current is adjusted. The control method has the advantages that (1) the control method is simple and effective; and (2) the precise control of the reduction furnace can be realized. And (3) the quality of the polycrystalline silicon rod can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of polysilicon material preparation, and in particular to a polysilicon reduction furnace control method. Background Art

[0002] When using the Siemens method to produce polysilicon, the silicon core temperature is mainly controlled by current during the entire reduction furnace operation cycle, and the power supply is mainly controlled by constant current transformer. At present, as the polysilicon production technology becomes more mature, the control of the reduction furnace is becoming more and more precise and refined. When the control is getting closer to the critical point, some changes in working conditions often cause abnormal production, which in turn affects product quality and consumption. Therefore, it is particularly important to detect changes in working conditions in a timely manner and fine-tune the control.

[0003] At present, the control of polysilicon reduction furnace is mainly controlled by the distributed control system (DCS) to adjust the material ratio, but it is also necessary to manually observe the conditions in the reduction furnace regularly to see if they are appropriate. If the working conditions such as material composition change, if the DCS operator does not find it in time, the on-site inspection personnel must observe the working conditions in the reduction furnace. Therefore, there are problems such as reliance on manual operation and manual experience, imprecise control, and unstable product quality. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a polysilicon production control system, which can make automatic adjustments in time according to comprehensive calculations such as the heat balance of the reduction furnace, the material balance, and the resistance characteristics of the silicon material. That is, when the operating conditions change and affect the silicon rods, the relevant parameters are automatically detected and calculated in real time and compared with the optimal parameters, and the ratio and current are automatically adjusted.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows.

[0006] In a first aspect, the present invention provides a method for controlling a polysilicon reduction furnace.

[0007] A method for controlling a polysilicon reduction furnace, the method comprising:

[0008] Determine the temperature reference curve of polysilicon rods;

[0009] Determine the temperature characterization function f of the polysilicon rod (T) ;

[0010] Characterize the function f by the silicon rod temperature (T) Calculate instantaneous temperature T i , compared with the silicon rod temperature reference curve;

[0011] If the temperature difference exceeds the set range value, the current is adjusted.

[0012] Furthermore, the method for determining the polysilicon rod temperature reference curve is to obtain the silicon rod temperature reference curve based on the operating data of the existing reduction furnace;

[0013] Specifically, the average diameter growth rate V(d) of the silicon rod is defined as:

[0014]

[0015] Where m is the mass of the silicon rod, t is the growth time of the silicon rod, L is the length of the silicon rod, ρ m is the density of silicon;

[0016] The silicon rod temperature curve corresponding to the silicon rod growth time t is expressed as T t =f(m,t), then we get T t The temperature curve has values ​​between 1200 and 1400K.

[0017] Furthermore, the silicon rod temperature characterization function f (T) for:

[0018]

[0019] In formula (1), A is the conductivity of polysilicon at 0°C, Q T To maintain T 0 The required heat, B is the correction factor, T 0 is the optimal growth temperature of silicon rod, D is the diameter of silicon rod, Q R The resistor generates heat.

[0020] Furthermore, the resistance heat Q R The calculation formula is Q R =I 2 Rt, where I is the current intensity, R is the resistance, and t is the time.

[0021] Furthermore, the calculation formula of the correction coefficient B is B=AαL / 2π, where A is the conductivity of polysilicon at 0°C, α is the temperature coefficient of resistivity of polysilicon, and L is the length of the silicon rod.

[0022] Furthermore, the calculation formula of the silicon rod diameter D is D=ρL / πR;

[0023] In the formula: ρ is the resistivity of the silicon rod, L is the length of the silicon rod, and R is the resistance.

[0024] Furthermore, the calculation formula of the silicon rod resistivity ρ is ρ=ρ 0 (1+αT),

[0025] In the formula: The silicon rod temperature is at the optimal temperature T 0 Under this condition, the resistivity of silicon rod is ρ0 is a constant ρ 0 =2.3*10 5 Ω·cm, ρ 0 =2.3*10 5 Ω·cm, α is the temperature coefficient of resistivity of polysilicon.

[0026] Furthermore, the control method further comprises: if the temperature difference exceeds the set range, adjusting the real-time current so that the instantaneous temperature T i Infinitely close to the reference temperature, precise control of the polysilicon reduction furnace can be achieved.

[0027] In a second aspect, the present invention provides a method for controlling polycrystalline silicon rods in a polycrystalline silicon reduction furnace.

[0028] A method for controlling polycrystalline silicon rods by a polycrystalline silicon reduction furnace, wherein the control method is used to control the growth rate and density of the polycrystalline silicon rods.

[0029] Furthermore, the control method is combined with real-time component feeding control to improve the growth rate and quality of silicon rods.

[0030] The present invention provides a polysilicon reduction furnace control method, which uses the accumulated reduction furnace operation data to first obtain a silicon rod temperature reference curve; when the reduction furnace is running, the instantaneous temperature T can be calculated in real time by formula (1). i , compared with the silicon rod temperature reference curve, if the difference exceeds the set range, the current is adjusted in real time to make the instantaneous temperature T i Infinitely close to the reference temperature, so as to achieve accurate control of the polysilicon reduction furnace. Using the control method provided by the present invention, the growth rate and density of polysilicon rods can be controlled.

[0031] At the same time, an online component analyzer is installed on the reduction furnace feed main pipeline to monitor component changes in real time, so that the reduction furnace feed molar ratio can be adjusted according to the component changes and the silicon rod temperature reference curve can be corrected.

[0032] The present invention provides a polysilicon reduction furnace control method, which controls the silicon rod temperature representation function f (T) , which avoids the silicon rod temperature being easily affected by the measurement accuracy and unable to be accurately judged and evaluated in real time, and uses the temperature control characterization function f provided by the present invention (T) According to the reference curve, the current can be adjusted in real time to make the silicon rod grow in an environment with an optimal temperature, which is more conducive to ensuring the growth rate and density of the silicon rod. On the other hand, by measuring the feed composition in real time, the anomaly in the reduction furnace caused by component fluctuations can be effectively eliminated, ensuring the normal growth of silicon rods and product quality.

[0033] Compared with the prior art, the advantages of the polysilicon reduction furnace control method provided by the present invention are:

[0034] (1) The control method is simple and effective.

[0035] (2) Precise control of the reduction furnace can be achieved.

[0036] (3) It can effectively improve the quality of polysilicon rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic flow chart of a method for controlling polysilicon rods in a polysilicon reduction furnace provided by the present invention. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail in the following examples. The following examples are only used to illustrate the invention but are not used to limit the scope of the present invention.

[0039] In a first aspect, the present invention provides a method for controlling a polysilicon reduction furnace.

[0040] A method for controlling a polysilicon reduction furnace, the method comprising:

[0041] Determine the temperature reference curve of polysilicon rods;

[0042] Determine the temperature characterization function f of the polysilicon rod (T) ;

[0043] Characterize the function f by the silicon rod temperature (T) Calculate instantaneous temperature T i , compared with the silicon rod temperature reference curve;

[0044] If the temperature difference exceeds the set range value, the current is adjusted.

[0045] Furthermore, the method for determining the polysilicon rod temperature reference curve is to obtain the silicon rod temperature reference curve based on the operating data of the existing reduction furnace;

[0046] Specifically, the average diameter growth rate V(d) of the silicon rod is defined as:

[0047]

[0048] Where m is the mass of the silicon rod, t is the growth time of the silicon rod, L is the length of the silicon rod, ρ m is the density of silicon;

[0049] The silicon rod temperature curve corresponding to the silicon rod growth time t is expressed as T t =f(m,t), then we get T tThe temperature curve has values ​​between 1200 and 1400K.

[0050] Furthermore, the silicon rod temperature characterization function f (T) for:

[0051]

[0052] In formula (1), A is the conductivity of polysilicon at 0°C, Q T To maintain T 0 The required heat, B is the correction factor, T 0 is the optimal growth temperature of silicon rod, D is the diameter of silicon rod, Q R The resistor generates heat.

[0053] Furthermore, the resistance heat Q R The calculation formula is Q R =I 2 Rt, where I is the current intensity, R is the resistance, and t is the time.

[0054] Furthermore, the calculation formula of the correction coefficient B is B=AαL / 2π, where A is the conductivity of polysilicon at 0°C, α is the temperature coefficient of resistivity of polysilicon, and L is the length of the silicon rod.

[0055] Furthermore, the calculation formula of the silicon rod diameter D is D=ρL / πR;

[0056] In the formula: ρ is the resistivity of the silicon rod, L is the length of the silicon rod, and R is the resistance.

[0057] Furthermore, the calculation formula of the silicon rod resistivity ρ is ρ=ρ 0 (1+αT),

[0058] In the formula: The silicon rod temperature is at the optimal temperature T 0 Under this condition, the resistivity of silicon rod is ρ 0 is a constant ρ 0 =2.3*10 5 Ω·cm, ρ 0 =2.3*10 5 Ω·cm, α is the temperature coefficient of resistivity of polysilicon.

[0059] Furthermore, the control method further comprises: if the temperature difference exceeds the set range, adjusting the real-time current so that the instantaneous temperature T i Infinitely close to the reference temperature, precise control of the polysilicon reduction furnace can be achieved.

[0060] In a second aspect, the present invention provides a method for controlling polycrystalline silicon rods in a polycrystalline silicon reduction furnace.

[0061] A method for controlling polycrystalline silicon rods by a polycrystalline silicon reduction furnace, wherein the control method is used to control the growth rate and density of the polycrystalline silicon rods.

[0062] Furthermore, the control method is combined with real-time component feeding control to improve the growth rate and quality of silicon rods.

[0063] Example 1

[0064] Combination Figure 1 As shown, a method for controlling a polysilicon reduction furnace, the method comprising:

[0065] (1) Determine the temperature reference curve of the polysilicon rod;

[0066] The method for determining the polysilicon rod temperature reference curve is to obtain the polysilicon rod temperature reference curve based on the operating data of the existing reduction furnace;

[0067] Specifically, the average diameter growth rate V(d) of the silicon rod is defined as:

[0068]

[0069] Where m is the mass of the silicon rod, t is the growth time of the silicon rod, L is the length of the silicon rod, ρ m is the density of silicon;

[0070] The silicon rod temperature curve corresponding to the silicon rod growth time t is expressed as T t =f(m,t), then we get T t The temperature curve has values ​​between 1200 and 1400K.

[0071] (2) Determine the temperature characterization function f of the polysilicon rod (T) ;

[0072] The silicon rod temperature characterization function f (T) for:

[0073]

[0074] In formula (1), A is the conductivity of polysilicon at 0°C, Q T To maintain T 0 The required heat, B is the correction factor, T 0 is the optimal growth temperature of silicon rod, D is the diameter of silicon rod, Q R The resistor generates heat.

[0075] Furthermore, the resistance heat Q R The calculation formula is Q R =I2Rt, where I is the current intensity, R is the resistance, and t is the time.

[0076] Furthermore, the calculation formula of the correction coefficient B is B=AαL / 2π, where A is the conductivity of polysilicon at 0°C, α is the temperature coefficient of resistivity of polysilicon, and L is the length of the silicon rod.

[0077] Furthermore, the calculation formula of the silicon rod diameter D is D=ρL / πR;

[0078] In the formula: ρ is the resistivity of the silicon rod, L is the length of the silicon rod, and R is the resistance.

[0079] Furthermore, the calculation formula of the silicon rod resistivity ρ is ρ=ρ 0 (1+αT),

[0080] In the formula: The silicon rod temperature is at the optimal temperature T 0 Under this condition, the resistivity of silicon rod is ρ 0 is a constant ρ 0 =2.3*10 5 Ω·cm, ρ 0 =2.3*10 5 Ω·cm, α is the temperature coefficient of resistivity of polysilicon.

[0081] (3) Characterization function f by silicon rod temperature (T) Calculate instantaneous temperature T i , compared with the silicon rod temperature reference curve;

[0082] (4) If the temperature difference exceeds the set range, adjust the current. If the temperature difference exceeds the set range, adjust the real-time current so that the instantaneous temperature T i Infinitely close to the reference temperature, precise control of the polysilicon reduction furnace can be achieved.

[0083] Example 2

[0084] Combination Figure 1 As shown, a method for controlling a polysilicon reduction furnace, the method comprising:

[0085] (1) Determine the temperature reference curve of the polysilicon rod;

[0086] The method for determining the polysilicon rod temperature reference curve is to obtain the polysilicon rod temperature reference curve based on the operating data of the existing reduction furnace;

[0087] Specifically, the average diameter growth rate V(d) of the silicon rod is defined as:

[0088]

[0089] Where m is the mass of the silicon rod, t is the growth time of the silicon rod, L is the length of the silicon rod, ρ m is the density of silicon;

[0090] The silicon rod temperature curve corresponding to the silicon rod growth time t is expressed as T t =f(m,t), then we get T t The temperature curve has values ​​between 1200 and 1400K.

[0091] (2) Determine the temperature characterization function f of the polysilicon rod (T) ;

[0092] The silicon rod temperature characterization function f (T) for:

[0093]

[0094] In formula (1), A is the conductivity of polysilicon at 0°C, Q T To maintain T 0 The required heat, B is the correction factor, T 0 is the optimal growth temperature of silicon rod, D is the diameter of silicon rod, Q R The resistor generates heat.

[0095] Furthermore, the resistance heat Q R The calculation formula is Q R =I 2 Rt, where I is the current intensity, R is the resistance, and t is the time.

[0096] Furthermore, the calculation formula of the correction coefficient B is B=AαL / 2π, where A is the conductivity of polysilicon at 0°C, α is the temperature coefficient of resistivity of polysilicon, and L is the length of the silicon rod.

[0097] Furthermore, the calculation formula of the silicon rod diameter D is D=ρL / πR;

[0098] In the formula: ρ is the resistivity of the silicon rod, L is the length of the silicon rod, and R is the resistance.

[0099] Furthermore, the calculation formula of the silicon rod resistivity ρ is ρ=ρ 0 (1+αT),

[0100] In the formula: The silicon rod temperature is at the optimal temperature T 0 Under this condition, the resistivity of silicon rod is ρ 0 is a constant ρ 0 =2.3*10 5 Ω·cm, ρ 0 =2.3*10 5 Ω·cm, α is the temperature coefficient of resistivity of polysilicon.

[0101] (3) Characterization function f by silicon rod temperature (T) Calculate instantaneous temperature T i , compared with the silicon rod temperature reference curve;

[0102] (4) If the temperature difference exceeds the set range, adjust the current. If the temperature difference exceeds the set range, adjust the real-time current so that the instantaneous temperature T i Infinitely close to the reference temperature, precise control of the polysilicon reduction furnace can be achieved.

[0103] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various changes can be made to the technical scheme of the present invention. These simple variations all belong to the protection scope of the present invention.

[0104] It should also be noted that the various specific technical features and steps described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0105] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A polysilicon reduction furnace control method, It is characterized in that The method includes: Determine the temperature reference curve of polysilicon rods; Determine the temperature characterization function f of the polysilicon rod (T) ; Characterize the function f by the silicon rod temperature (T) Calculate instantaneous temperature T i , compared with the silicon rod temperature reference curve; If the temperature difference exceeds the set range value, the current is adjusted.

2. A polysilicon reduction furnace control method according to claim 1, Features: The method for determining the polysilicon rod temperature reference curve is to obtain the polysilicon rod temperature reference curve based on the operating data of the existing reduction furnace; Specifically, the average diameter growth rate V(d) of the silicon rod is defined as: Where m is the mass of the silicon rod, t is the growth time of the silicon rod, L is the length of the silicon rod, ρ m is the density of silicon; The silicon rod temperature curve corresponding to the silicon rod growth time t is expressed as T t =f(m,t), then we get T t The temperature curve has values ​​between 1200 and 1400K.

3. A polysilicon reduction furnace control method according to claim 1, It is characterized in that The silicon rod temperature characterization function f (T) for: In formula (1), A is the conductivity of polysilicon at 0°C, Q T To maintain T 0 The required heat, B is the correction factor, T 0 is the optimal growth temperature of silicon rod, D is the diameter of silicon rod, Q R The resistor generates heat.

4. A polysilicon reduction furnace control method according to claim 3, Features: The resistance heat Q R The calculation formula is Q R =I 2 Rt, where I is the current intensity, R is the resistance, and t is the time.

5. A polysilicon reduction furnace control method according to claim 3 or 4, Features: The calculation formula of the correction coefficient B is B=AαL / 2π, where A is the conductivity of polysilicon at 0°C, α is the temperature coefficient of resistivity of polysilicon, and L is the length of the silicon rod.

6. A polysilicon reduction furnace control method according to claim 3 or 4, Features: The calculation formula of the silicon rod diameter D is D=ρL / πR; In the formula: ρ is the resistivity of the silicon rod, L is the length of the silicon rod, and R is the resistance.

7. A polysilicon reduction furnace control method according to claim 1, It is characterized in that The calculation formula of the silicon rod resistivity ρ is ρ=ρ 0 (1+αT), In the formula: The silicon rod temperature is at the optimal temperature T 0 Under this condition, the resistivity of silicon rod is ρ 0 is a constant ρ 0 =2.3*10 5 Ω·cm, ρ 0 =2.3*10 5 Ω·cm, α is the temperature coefficient of resistivity of polysilicon.

8. A polysilicon reduction furnace control method according to claim 1, It is characterized in that The control method further includes: if the temperature difference exceeds the set range, adjusting the real-time current so that the instantaneous temperature T i Infinitely close to the reference temperature, precise control of the polysilicon reduction furnace can be achieved.

9. A polysilicon reduction furnace control method according to claim 1, It is characterized in that The control method is used to control the growth rate and density of polycrystalline silicon rods.

10. A polysilicon reduction furnace control method according to claim 1, It is characterized in that The control method is combined with real-time component feeding control to improve the growth rate and quality of silicon rods.

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