High-pressure starting method for six-phase 40-pair-rod reduction furnace

Abstract

The invention relates to the technical field of polycrystalline silicon production, in particular to a high-voltage starting method of a six-phase 40-pair rod reduction furnace, which comprises the following steps: simultaneously starting 4 pairs of rod silicon cores and 6 pairs of rod silicon cores in an A1 phase, a B1 phase and a C1 phase at high voltage; after the silicon cores in the phase A1, the phase B1 and the phase C1 are broken down and converted into parallel operation, 8 pairs of rod silicon cores in the phase A2, the phase B2 and the phase C2 are started at high voltage: two pairs of silicon cores before the CJ1 contactor breaks down are directly converted into two pairs of silicon cores before the CJ3 contactor operates; the CJ1 contactor breaks down the third pair of silicon cores and the fourth pair of silicon cores, the CJ2 contactor maintains the third pair of silicon cores and the fourth pair of silicon cores after breakdown, and the first four pairs of silicon cores of the CJ3 contactor operate; the CJ2 contactor directly maintains the fifth and sixth pairs of silicon cores, then maintains the seventh and eighth pairs of silicon cores and then maintains the fifth, sixth and seventh and eighth pairs of silicon cores for parallel operation, two loops are arranged, the first loop operates the first four pairs of silicon cores through the CJ3 contactor, and the second loop operates the last four pairs of silicon cores through the CJ2 contactor. According to the high-voltage starting method, the breakdown process is simplified, and the damage rate of the silicon core is reduced.

Description

Technical Field

[0001] This invention relates to the field of polycrystalline silicon production technology, and in particular to a high-pressure start-up method for a six-phase 40-pair rod reduction furnace. Background Technology

[0002] The polysilicon reduction furnace is a key piece of equipment used to produce high-purity polysilicon. It is mainly used in the chemical vapor deposition (CVD) process to react trichlorosilane or silicon tetrachloride with hydrogen to reduce polysilicon to high purity at high temperatures. Each silicon core group in the polysilicon reduction furnace is equipped with a corresponding start-up circuit, primarily used to subject the silicon cores of the silicon core group to high-voltage breakdown.

[0003] In existing technologies, the high-voltage start-up method is generally as follows: the test rods are divided into several groups, and each group completes the breakdown and maintenance of the silicon core in sequence before proceeding to the next group, until all groups have completed the operation and then maintenance is performed.

[0004] For example, in the prior art, there is a Chinese invention patent document with publication number CN110683547A and publication date of January 14, 2020. The technical solution disclosed in this patent document is as follows: When the silicon core of the first phase is broken down, 8 pairs of silicon cores are broken down first. Since the voltage after breakdown is only 1 / 4 of the highest breakdown voltage, these 8 pairs of silicon cores are maintained by 4 high-voltage breakdown cabinets. The other 4 high-voltage breakdown cabinets then break down the remaining 4 pairs of silicon cores of the first phase. After the 12 pairs of silicon cores are broken down, they are then uniformly handed over to the power control cabinet for control.

[0005] Taking an 8-pair silicon core as an example, existing technology generally first breaks down the first two pairs of silicon cores through contactor CJ1. After breakdown, contactor CJ2 maintains the first two pairs, and then contactor CJ3 operates the first two pairs of silicon cores. Contactor CJ1 breaks down the third and fourth pairs of silicon cores. After breakdown, contactor CJ2 maintains the third and fourth pairs of silicon cores, and then contactor CJ3 operates the first four pairs of silicon cores. Contactor CJ1 breaks down the fifth and sixth pairs of silicon cores, then contactor CJ1 breaks down the seventh and eighth pairs of silicon cores. Contactor CJ1 breaks down four pairs (the fifth, sixth, seventh, and eighth pairs of silicon cores), and contactor CJ2 directly maintains the fifth and sixth pairs of silicon cores, then maintains the seventh and eighth pairs of silicon cores, and then maintains four pairs (the fifth, sixth, seventh, and eighth pairs of silicon cores). For example, in the existing technology, there is a Chinese invention patent document with publication number CN117277778A and publication date of December 22, 2023.

[0006] In summary, existing start-up methods all involve relatively cumbersome processes, requiring multiple contactor actions and switching between silicon core breakdown states. This necessitates constantly turning the silicon core on and off, which significantly damages the silicon core density. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a high-pressure start-up method for a six-phase 40-pair rod reduction furnace, which effectively solves the problem of cumbersome start-up methods, simplifies the breakdown process, and reduces the damage rate of silicon cores.

[0008] This invention is achieved by adopting the following technical solution: A high-pressure start-up method for a six-phase 40-pair rod reduction furnace, wherein the furnace bottom plate silicon core has a total of six phases: A1, A2, B1, B2, C1, and C2; the inner ring is the B1 phase, with 4 pairs of silicon cores distributed; the second ring is the C2 phase, with 8 pairs of silicon cores distributed; the third ring is the A1 and C1 phases, with 6 pairs of silicon cores distributed each; the outermost ring is the A2 and B2 phases, with 8 pairs of silicon cores distributed each. The high-pressure start-up method is carried out in two stages, specifically including the following steps: Step S1. Simultaneously, high voltage is applied to start 4 pairs of silicon core rods and 6 pairs of silicon core rods in phases A1, B1, and C1; Step S2. After the silicon cores in phases A1, B1, and C1 break down and switch to parallel operation, the high-voltage start-up of the 8 pairs of rod silicon cores in phases A2, B2, and C2 is performed. The high-voltage start-up method for the 8 pairs of rod silicon cores is as follows: the first two pairs of silicon cores are broken down by the CJ1 contactor in the control power cabinet, and the CJ3 contactor is directly switched to run the first two pairs of silicon cores; the CJ1 contactor then breaks down the third and fourth pairs of silicon cores, and after the breakdown, the CJ2 contactor maintains the third and fourth pairs of silicon cores, and the CJ3 contactor runs the first four pairs of silicon cores; the CJ2 contactor directly maintains the fifth and sixth pairs of silicon cores, then maintains the seventh and eighth pairs of silicon cores, and then maintains the fifth, sixth, seventh, and eighth pairs of silicon cores, running in parallel. Two circuits are set up: the first circuit runs the first four pairs of silicon cores by the CJ3 contactor, and the second circuit runs the fifth, sixth, seventh, and eighth pairs of silicon cores by the CJ2 contactor.

[0009] When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operating current is greater than 405A, the CJ2 contactor and the CJ3 contactor will trip, the circuit breaker will close, and the circuit will switch to series operation.

[0010] When the CJ1 contactor breaks down, a low-power step-up transformer is used, while the CJ2 contactor uses a 10kV dry-type transformer. Different transformers are used by switching between them.

[0011] The high-voltage starting method for the 4-pair silicon core is as follows: Close the CJ1 contactor in the power cabinet to break down the first pair of silicon cores, close the CJ2 contactor to maintain the first pair of silicon cores, and turn the CJ3 contactor to run the first pair of silicon cores; close the CJ1 contactor to break down the second pair of silicon cores, close the CJ2 contactor to maintain the second pair of silicon cores, and turn the CJ3 contactor to run the first two pairs of silicon cores; close the CJ1 contactor to break down the third pair of silicon cores, close the CJ2 contactor to maintain the third pair of silicon cores, and turn the CJ3 contactor to run the first three pairs of silicon cores; close the CJ1 contactor to break down the fourth pair of silicon cores, close the CJ2 contactor to maintain the fourth pair of silicon cores, and turn the CJ3 contactor to run the four pairs of silicon cores in parallel.

[0012] When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operation current is greater than 80A, the CJ3 contactor trips, the circuit breaker closes, and the circuit switches to series operation.

[0013] The high-voltage starting method for the 6-pair silicon core is as follows: Close the CJ1 contactor in the power cabinet to break down the first pair of silicon cores, close the CJ2 contactor to maintain the first pair of silicon cores, and turn the CJ3 contactor to run the first pair of silicon cores; close the CJ1 contactor to break down the second pair of silicon cores, close the CJ2 contactor to maintain the second pair of silicon cores, and turn the CJ3 contactor to run the first two pairs of silicon cores; close the CJ1 contactor to break down the third and fourth pairs of silicon cores, close the CJ2 contactor to maintain the third and fourth pairs of silicon cores, and turn the CJ3 contactor to run the first four pairs of silicon cores; close the CJ1 contactor to break down the fifth and sixth pairs of silicon cores, close the CJ2 contactor to maintain the fifth and sixth pairs of silicon cores, and run in parallel, setting up two circuits. The first circuit is run by the CJ3 contactor to run the first four pairs of silicon cores, and the second circuit is run by the CJ2 contactor to run the fifth and sixth pairs of silicon cores.

[0014] When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operating current is greater than 120A, the CJ2 contactor and the CJ3 contactor will trip, the circuit breaker will close, and the circuit will switch to series operation.

[0015] When operating in series, constant current control is used.

[0016] The operating current is 60A.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. During the transition from CJ1 contactor breakdown to CJ2 contactor, the silicon core involves both lighting up and extinguishing. Existing technologies require continuous lighting and extinguishing of the silicon core, which significantly damages its density and can easily lead to furnace collapse. This invention addresses this by simultaneously activating the intermediate small phases (4 and 6 pairs of rods), namely A1, B1, and C1 phases, to raise the intermediate furnace temperature. After breakdown and parallel operation, the large phases (8 pairs of rods), namely A2, B2, and C2 phases, are activated for three-phase breakdown operation. This simplifies the breakdown process for the 8-pair silicon core and reduces the silicon core damage rate.

[0018] 2. In this invention, by using a suitable transformer, the frequency of use of low-power step-up transformers can be reduced, thereby reducing the failure rate.

[0019] 3. When operating in series, constant current control is used, which makes the output current less affected by the load (output voltage) and the ambient temperature, and the internal resistance is infinite, thereby ensuring that the current flows stably to the load.

[0020] 4. In this invention, the high-voltage start-up method of 4 pairs of silicon core rods and the high-voltage start-up method of 6 pairs of silicon core rods are used in combination to enable the high-voltage start-up of silicon cores in phases A1, B1 and C1 at the same time. Since the last two pairs in phases A1 and C1 break down in groups of two at the same time, when the last two pairs of silicon cores in phases A1 and C1 can break down, it means that the furnace temperature can meet the breakdown condition of the two pairs of silicon cores. Therefore, after the breakdown of phases A1 and C1 is completed and parallel operation is started, the large phases, namely phases A2, B2 and C2, can be started.

[0021] 5. Since the higher the current, the higher the temperature inside the furnace and the faster the breakdown speed, but excessive current can easily cause the silicon core to melt. In order to simplify the breakdown process when starting the 8 pairs of silicon core rods in phases A2, B2 and C2 under high voltage, and to eliminate the breakdown of the fifth, sixth, seventh and eighth pairs of silicon cores, the present invention specifically sets the operating current to 60A, thereby improving the stability and safety of the system operation while ensuring the breakdown efficiency. Attached Figure Description

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein: Figure 1 This is a schematic diagram of the arrangement of silicon cores in the furnace bottom plate of the present invention; Figure 2 This is a schematic diagram of the power cabinet layout in this invention. Detailed Implementation

[0023] Example 1 As a basic embodiment of the present invention, the present invention includes a high-pressure start-up method for a six-phase 40-pair rod reduction furnace. The furnace bottom plate silicon core has a total of six phases: A1, A2, B1, B2, C1, and C2. The inner ring is the B1 phase, with 4 pairs of silicon cores distributed. The second ring is the C2 phase, with 8 pairs of silicon cores distributed. The third ring consists of the A1 and C1 phases, each with 6 pairs of silicon cores distributed. The outermost ring consists of the A2 and B2 phases, each with 8 pairs of silicon cores distributed. The high-pressure start-up method is carried out in two stages, specifically including the following steps: Step S1. Simultaneously start the 4 pairs of rod silicon cores and 6 pairs of rod silicon cores in phases A1, B1 and C1 under high voltage.

[0024] Step S2. After the silicon cores in phases A1, B1, and C1 break down and switch to parallel operation, the eight pairs of rod silicon cores in phases A2, B2, and C2 are started under high voltage.

[0025] The high-voltage starting method for the 8 pairs of silicon core rods is as follows: The first two pairs of silicon core rods are broken down by contactor CJ1 in the control power cabinet, directly switching to contactor CJ3 to operate the first two pairs. Contactor CJ1 then breaks down the third and fourth pairs of silicon core rods. After breaking down, contactor CJ2 maintains the third and fourth pairs, switching to contactor CJ3 to operate the first four pairs. Contactor CJ2 directly maintains the fifth and sixth pairs, then the seventh and eighth pairs, and then the fifth, sixth, seventh, and eighth pairs. Parallel operation is achieved through two circuits: the first circuit operates the first four pairs of silicon core rods via contactor CJ3, and the second circuit operates the fifth, sixth, seventh, and eighth pairs via contactor CJ2.

[0026] Example 2 In a preferred embodiment of the present invention, the present invention includes a high-pressure start-up method for a six-phase 40-pair rod reduction furnace. The furnace bottom plate of the reduction furnace has a total of six phases: A1, A2, B1, B2, C1, and C2. The inner ring is the B1 phase, with 4 pairs of silicon cores distributed; the second ring is the C2 phase, with 8 pairs of silicon cores distributed; the third ring consists of the A1 and C1 phases, each with 6 pairs of silicon cores; and the outermost ring consists of the A2 and B2 phases, each with 8 pairs of silicon cores. The high-pressure start-up method is performed in two stages, specifically including the following steps: Step S1. Simultaneously start the 4 pairs of rod silicon cores and 6 pairs of rod silicon cores in phases A1, B1 and C1 under high voltage.

[0027] Step S2. After the silicon cores in phases A1, B1, and C1 break down and switch to parallel operation, the eight pairs of rod silicon cores in phases A2, B2, and C2 are started under high voltage.

[0028] The high-voltage starting method for the 8 pairs of silicon cores is as follows: The first two pairs of silicon cores are broken down by contactor CJ1 in the control power cabinet, directly switching to contactor CJ3 to operate the first two pairs. Contactor CJ1 then breaks down the third and fourth pairs of silicon cores. After breaking down, contactor CJ2 maintains the third and fourth pairs, switching to contactor CJ3 to operate the first four pairs. Contactor CJ2 directly maintains the fifth and sixth pairs, then the seventh and eighth pairs, and then the fifth, sixth, seventh, and eighth pairs. Parallel operation is achieved using two circuits: the first circuit operates the first four pairs of silicon cores using contactor CJ3, and the second circuit operates the fifth, sixth, seventh, and eighth pairs using contactor CJ2. When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V, and the parallel operation current exceeds 405A, contactors CJ2 and CJ3 open, the circuit breaker closes, and the system switches to series operation. During series operation, constant current control is used.

[0029] When the CJ1 contactor breaks down, a low-power step-up transformer is used, while the CJ2 contactor uses a 10kV dry-type transformer. Different transformers are used by switching between them.

[0030] Example 3 As another preferred embodiment of the present invention, the present invention includes a high-pressure start-up method for a six-phase 40-pair rod reduction furnace. The furnace bottom plate silicon core of the reduction furnace has a total of six phases: A1, A2, B1, B2, C1, and C2. The inner ring is the B1 phase, with 4 pairs of silicon cores distributed; the second ring is the C2 phase, with 8 pairs of silicon cores distributed; the third ring is the A1 phase and the C1 phase, with 6 pairs of silicon cores distributed respectively; and the outermost ring is the A2 phase and the B2 phase, with 8 pairs of silicon cores distributed respectively.

[0031] The high-voltage start-up method is carried out in two stages, specifically including the following steps: Step S1. Simultaneously start the 4 pairs of rod silicon cores and 6 pairs of rod silicon cores in phases A1, B1 and C1 under high voltage.

[0032] The high-voltage starting method for the four pairs of silicon cores is as follows: Close contactor CJ1 in the power cabinet to break down the first pair of silicon cores; close contactor CJ2 to maintain the first pair of silicon cores; then switch contactor CJ3 to operate the first pair of silicon cores. Close contactor CJ1 to break down the second pair of silicon cores; close contactor CJ2 to maintain the second pair of silicon cores; then switch contactor CJ3 to operate the first two pairs of silicon cores. Close contactor CJ1 to break down the third pair of silicon cores; close contactor CJ2 to maintain the third pair of silicon cores; then switch contactor CJ3 to operate the first three pairs of silicon cores. Close contactor CJ1 to break down the fourth pair of silicon cores; close contactor CJ2 to maintain the fourth pair of silicon cores; then switch contactor CJ3 to operate all four pairs of silicon cores in parallel.

[0033] The high-voltage starting method for the 6-pair silicon core is as follows: Close contactor CJ1 in the power cabinet to break down the first pair of silicon cores; close contactor CJ2 to maintain the first pair of silicon cores; then switch contactor CJ3 to operate the first pair of silicon cores. Close contactor CJ1 to break down the second pair of silicon cores; close contactor CJ2 to maintain the second pair of silicon cores; then switch contactor CJ3 to operate the first two pairs of silicon cores. Close contactor CJ1 to break down the third and fourth pairs of silicon cores; close contactor CJ2 to maintain the third and fourth pairs of silicon cores; then switch contactor CJ3 to operate the first four pairs of silicon cores. Close contactor CJ1 to break down the fifth and sixth pairs of silicon cores; close contactor CJ2 to maintain the fifth and sixth pairs of silicon cores. These are operated in parallel, with two circuits. In the first circuit, contactor CJ3 operates the first four pairs of silicon cores; in the second circuit, contactor CJ2 operates the fifth and sixth pairs of silicon cores.

[0034] Step S2. After the silicon cores in phases A1, B1, and C1 break down and switch to parallel operation, the eight pairs of rod silicon cores in phases A2, B2, and C2 are started under high voltage.

[0035] The high-voltage starting method for the 8 pairs of silicon core rods is as follows: The first two pairs of silicon core rods are broken down by contactor CJ1 in the control power cabinet, directly switching to contactor CJ3 to operate the first two pairs. Contactor CJ1 then breaks down the third and fourth pairs of silicon core rods. After breaking down, contactor CJ2 maintains the third and fourth pairs, switching to contactor CJ3 to operate the first four pairs. Contactor CJ2 directly maintains the fifth and sixth pairs, then the seventh and eighth pairs, and then the fifth, sixth, seventh, and eighth pairs. Parallel operation is achieved by setting up two circuits: the first circuit operates the first four pairs of silicon core rods via contactor CJ3, and the second circuit operates the fifth, sixth, seventh, and eighth pairs via contactor CJ2.

[0036] Example 4 As another preferred embodiment of the present invention, the present invention includes a high-pressure start-up method for a six-phase 40-pair rod reduction furnace, as described in the appendix to the specification. Figure 1 The furnace bottom plate of the reduction furnace has a total of six phases: A1, A2, B1, B2, C1, and C2. The inner ring is the B1 phase, with 4 pairs of silicon cores. The second ring is the C2 phase, with 8 pairs of silicon cores. The third ring consists of the A1 and C1 phases, each with 6 pairs of silicon cores. The outermost ring consists of the A2 and B2 phases, each with 8 pairs of silicon cores.

[0037] The high-voltage start-up method is carried out in two stages, specifically including the following steps: Step S1. Simultaneously start the 4 pairs of rod silicon cores and 6 pairs of rod silicon cores in phases A1, B1 and C1 under high voltage.

[0038] The high-voltage start-up method for the four pairs of silicon core rods is as follows: refer to the appendix of the instruction manual. Figure 2 When the CJ1 contactor in the power cabinet breaks down the first pair of silicon cores, the CJ2 contactor maintains the first pair of silicon cores, and the CJ3 contactor operates the first pair of silicon cores with a current of 60A. When the CJ1 contactor breaks down the second pair of silicon cores, the CJ2 contactor maintains the second pair of silicon cores, and the CJ3 contactor operates the first two pairs of silicon cores with a current of 60A. When the CJ1 contactor breaks down the third pair of silicon cores, the CJ2 contactor maintains the third pair of silicon cores, and the CJ3 contactor operates the first three pairs of silicon cores with a current of 60A. When the CJ1 contactor breaks down the fourth pair of silicon cores, the CJ2 contactor maintains the fourth pair of silicon cores, and the CJ3 contactor operates all four pairs of silicon cores in parallel with a current of 60A. When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operating current is greater than 80A, the CJ3 contactor trips, the circuit breaker closes, and the circuit switches to series operation.

[0039] The high-voltage starting method for the 6-pair silicon core is as follows: Close contactor CJ1 in the power cabinet to break down the first pair of silicon cores, close contactor CJ2 to maintain the first pair of silicon cores, and then switch contactor CJ3 to operate the first pair of silicon cores with an operating current of 60A. Close contactor CJ1 to break down the second pair of silicon cores, close contactor CJ2 to maintain the second pair of silicon cores, and then switch contactor CJ3 to operate the first two pairs of silicon cores with an operating current of 60A. Close contactor CJ1 to break down the third and fourth pairs of silicon cores, close contactor CJ2 to maintain the third and fourth pairs of silicon cores, and then switch contactor CJ3 to operate the first four pairs of silicon cores with an operating current of 60A. Close contactor CJ1 to break down the fifth and sixth pairs of silicon cores, and close contactor CJ2 to maintain the fifth and sixth pairs of silicon cores. The system operates in parallel with an operating current of 60A, using two circuits. The first circuit operates the first four pairs of silicon cores using contactor CJ3, and the second circuit operates the fifth and sixth pairs of silicon cores using contactor CJ2. When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operating current is greater than 120A, the CJ2 contactor and the CJ3 contactor will trip, the circuit breaker will close, and the circuit will switch to series operation.

[0040] Step S2. After the silicon cores in phases A1, B1, and C1 break down and switch to parallel operation, the eight pairs of rod silicon cores in phases A2, B2, and C2 are started under high voltage.

[0041] The high-voltage starting method for the 8 pairs of silicon cores is as follows: The first two pairs of silicon cores are broken down by contactor CJ1 in the control power cabinet, directly switching to contactor CJ3 to operate the first two pairs of silicon cores with an operating current of 60A. Contactor CJ1 then breaks down the third and fourth pairs of silicon cores. After breakdown, contactor CJ2 maintains the third and fourth pairs of silicon cores, then contactor CJ3 operates the first four pairs of silicon cores with an operating current of 60A. Contactor CJ2 directly maintains the fifth and sixth pairs of silicon cores, then the seventh and eighth pairs, and then the fifth, sixth, seventh, and eighth pairs. Parallel operation is implemented with an operating current of 60A. Two circuits are set up: the first circuit operates the first four pairs of silicon cores using contactor CJ3, and the second circuit operates the fifth, sixth, seventh, and eighth pairs of silicon cores using contactor CJ2. When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V, and the parallel operating current is greater than 405A, contactors CJ2 and CJ3 open, the circuit breaker closes, and the system switches to series operation.

[0042] More specifically, in series operation, constant current control is employed, which is a power supply control method that maintains a constant output current. Its basic circuit mainly consists of an input stage and an output stage. The input stage provides a reference current, and the output stage outputs the required constant current. This control method minimizes the impact of the load (output voltage) and ambient temperature on the output current, resulting in infinite internal resistance and ensuring a stable current flow to the load.

[0043] The above-described startup method involves simultaneously starting the intermediate small phases (4 and 6 pairs of rods), namely phases A1, B1, and C1, to raise the intermediate temperature inside the furnace. After breakdown and parallel operation, the large phases (8 pairs of rods), namely phases A2, B2, and C2, are started. This ensures that the furnace temperature meets the requirements when starting the silicon cores in the large phases. By simplifying the breakdown process of these 8 pairs of rod silicon cores, the damage rate of the silicon cores can be reduced. Furthermore, a low-power step-up transformer is used when the CJ1 contactor breaks down, while the CJ2 contactor uses a 10kV dry-type transformer. By matching the transformers used, the frequency of use of the low-power step-up transformer can be reduced, thus reducing the failure rate.

[0044] In summary, any other corresponding modifications made by those skilled in the art after reading this invention document, without requiring creative mental effort, based on the technical solutions and concepts of this invention, are all within the scope of protection of this invention.

Claims

1. A high-pressure start-up method for a six-phase 40-pair rod reduction furnace, characterized in that: The furnace bottom plate of the reduction furnace has a total of six phases: A1, A2, B1, B2, C1, and C2. The inner ring is the B1 phase, with 4 pairs of silicon cores distributed; the second ring is the C2 phase, with 8 pairs of silicon cores distributed; the third ring consists of the A1 and C1 phases, each with 6 pairs of silicon cores; and the outermost ring consists of the A2 and B2 phases, each with 8 pairs of silicon cores. The high-voltage start-up method is carried out in two stages, specifically including the following steps: Step S1. Simultaneously, high voltage is applied to start 4 pairs of silicon core rods and 6 pairs of silicon core rods in phases A1, B1, and C1; Step S2. After the silicon cores in phases A1, B1, and C1 break down and switch to parallel operation, the high-voltage start-up of the 8 pairs of rod silicon cores in phases A2, B2, and C2 is performed. The high-voltage start-up method for the 8 pairs of rod silicon cores is as follows: the first two pairs of silicon cores are broken down by the CJ1 contactor in the control power cabinet, and the CJ3 contactor is directly switched to run the first two pairs of silicon cores; the CJ1 contactor then breaks down the third and fourth pairs of silicon cores, and after the breakdown, the CJ2 contactor maintains the third and fourth pairs of silicon cores, and the CJ3 contactor runs the first four pairs of silicon cores; the CJ2 contactor directly maintains the fifth and sixth pairs of silicon cores, then maintains the seventh and eighth pairs of silicon cores, and then maintains the fifth, sixth, seventh, and eighth pairs of silicon cores, running in parallel. Two circuits are set up: the first circuit runs the first four pairs of silicon cores by the CJ3 contactor, and the second circuit runs the fifth, sixth, seventh, and eighth pairs of silicon cores by the CJ2 contactor.

2. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 1, characterized in that: When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operating current is greater than 405A, the CJ2 contactor and the CJ3 contactor will trip, the circuit breaker will close, and the circuit will switch to series operation.

3. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 1, characterized in that: When the CJ1 contactor breaks down, a low-power step-up transformer is used, while the CJ2 contactor uses a 10kV dry-type transformer. Different transformers are used by switching between them.

4. A high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 1 or 3, characterized in that: The high-voltage starting method for the 4-pair silicon core is as follows: close the CJ1 contactor in the power cabinet to break down the first pair of silicon cores, close the CJ2 contactor to maintain the first pair of silicon cores, and turn the CJ3 contactor to run the first pair of silicon cores; close the CJ1 contactor to break down the second pair of silicon cores, close the CJ2 contactor to maintain the second pair of silicon cores, and turn the CJ3 contactor to run the first two pairs of silicon cores. Close CJ1 contactor breaks down the third pair of silicon cores, close CJ2 contactor to maintain the third pair of silicon cores, and turn CJ3 contactor to run the first three pairs of silicon cores. When contactor CJ1 is closed, the fourth pair of silicon cores is broken down. When contactor CJ2 is closed, the fourth pair of silicon cores is maintained. When contactor CJ3 is turned on, the four pairs of silicon cores are operated in parallel.

5. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 4, characterized in that: When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operation current is greater than 80A, the CJ3 contactor trips, the circuit breaker closes, and the circuit switches to series operation.

6. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 4, characterized in that: The high-voltage starting method for the 6-pair silicon core is as follows: close the CJ1 contactor in the power cabinet to break down the first pair of silicon cores, close the CJ2 contactor to maintain the first pair of silicon cores, and turn the CJ3 contactor to run the first pair of silicon cores; close the CJ1 contactor to break down the second pair of silicon cores, close the CJ2 contactor to maintain the second pair of silicon cores, and turn the CJ3 contactor to run the first two pairs of silicon cores. Close CJ1 contactor breaks down the third and fourth pairs of silicon cores, close CJ2 contactor to maintain the third and fourth pairs of silicon cores, and turn CJ3 contactor to run the first four pairs of silicon cores. When contactor CJ1 is closed, the fifth and sixth silicon core pairs are broken down. When contactor CJ2 is closed, the fifth and sixth silicon core pairs are maintained. They operate in parallel, setting up two circuits. In the first circuit, contactor CJ3 operates the first four silicon core pairs, and in the second circuit, contactor CJ2 operates the fifth and sixth silicon core pairs.

7. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 6, characterized in that: When the sum of the main circuit voltage and the branch circuit voltage is less than 2650V and the parallel operating current is greater than 120A, the CJ2 contactor and the CJ3 contactor will trip, the circuit breaker will close, and the circuit will switch to series operation.

8. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 7, characterized in that: When operating in series, constant current control is used.

9. The high-pressure start-up method for a six-phase 40-pair rod reduction furnace according to claim 7, characterized in that: The operating current is 60A.

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