Cooling method of furnace body and materials in furnace

Abstract

The present invention provides a method for cooling a furnace body and materials in the furnace, the method comprising: measuring the outlet temperature T of the furnace body; 出气 and furnace temperature T 炉 , get T 出气 and T 炉 The functional relationship T 出气 (T 炉 ); in T max Determine multiple fixed amplitude intervals within the following temperature range; according to Q 安全 The calculation formula calculates the gas flow rate #imgabs1# in any fixed amplitude interval within the preset time #imgabs0#; in T max Multiple adjustment intervals are determined within the following temperature range, and the left value of any adjustment interval is Ti, and the right value is Ti+20·N; the minimum value in #imgabs2# of multiple fixed-amplitude intervals associated with any adjustment interval (Ti, Ti+20·N) is taken as the adjustment ventilation flow #imgabs3# of the adjustment interval; the adjustment ventilation flow #imgabs4# of each adjustment interval is substituted into the first calculation formula or the second calculation formula to calculate the final ventilation flow #imgabs5# of each adjustment interval, and according to the calculation result of the final ventilation flow #imgabs6#, air is introduced into the furnace body through the furnace body inlet in the multiple adjustment intervals, and the air in the furnace body is discharged through the furnace body outlet.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor equipment production, and in particular to a method for cooling a furnace body and materials in the furnace. Background Art

[0002] As a third-generation semiconductor material, silicon carbide has a broad application market. The oxidation process is a crucial link in the production and preparation process of silicon carbide. The tubular oxidation furnace currently made of quartz material has the problem of taking a long time to cool down, which seriously restricts the production efficiency of silicon carbide powder. Although it is known in the art to remove the heat in the furnace by introducing air into the furnace body, it is currently difficult to control the rate of introduction of air into the furnace. If the ventilation volume per unit time is too small, it is difficult to shorten the cooling time of the furnace body, and if the ventilation volume per unit time is too large, the outlet of the furnace body will heat up rapidly, which is very likely to cause dust explosion accidents, and will also increase the risk of cracking of the furnace body and silicon carbide. Summary of the Invention

[0003] In view of this, the present invention provides a method for cooling the furnace body and materials in the furnace, which not only shortens the cooling time of the oxidation furnace body, but also eliminates the explosion hazard and reduces the risk of cracking of the furnace body and materials.

[0004] The cooling method of the furnace body and the materials in the furnace of the present invention is based on ventilation flow control, and includes:

[0005] Step A

[0006] Measure the outlet temperature T of the furnace 出气 and furnace temperature T 炉 , and get about T 出气 and T 炉 The functional relationship T 出气 (T 炉 );

[0007] Step B

[0008] In T max Determine multiple fixed amplitude intervals within the following temperature range. The left value of any fixed amplitude interval is equal to , the rvalue is equal to ,

[0009] Among them, T max and T min The furnace temperature T 炉 The take-off and landing temperature and target temperature, n is the fixed amplitude interval from T max to T min Ordinal numbers in descending order;

[0010] Step C

[0011] according to Calculate the time of any fixed amplitude interval in the preset time Gas intake ,

[0012] Among them, Q 安全 is the furnace temperature T 炉 From T max The sum of the heat dissipation of the furnace body and the heat dissipation of the materials in the furnace after the temperature drops by 100°C in S0 minutes.

[0013] S0 is the temperature of the furnace body and the materials in the furnace max Started to cool down and lost Q 安全 The minimum allowable time for heat, t = , Δt=100,

[0014] c 空气 is the specific heat capacity of the air entering the furnace, m 空气 To take away Q 安全 The mass of air used for heat, T 进气 is the inlet temperature of the furnace;

[0015] Step D

[0016] In T max Multiple adjustment intervals are determined within the following temperature range. The left value of any adjustment interval is Ti, and the right value is Ti+20·N. The value set of N is {1, 2, 3, 4};

[0017] Step E

[0018] In the case of multiple fixed amplitude intervals associated with any adjustment interval (Ti, Ti + 20·N) The minimum value is taken as the regulated ventilation flow in the regulation interval , wherein the multiple fixed amplitude intervals associated with the adjustment interval are arranged in descending order and include:

[0019] (Ti, Ti + 100),

[0020] (Ti-20, Ti+80),

[0021] (Ti-40, Ti+60),

[0022] ...、

[0023] (Ti+20·N-80, Ti+20·N+20),

[0024] (Ti+20·N-100, Ti+20·N);

[0025] Step J

[0026] Adjust the ventilation flow in each adjustment interval Substitute into the first calculation formula Or the second formula Calculate the final ventilation flow for each regulation interval , according to the final ventilation flow The air is introduced into the furnace through the furnace inlet and discharged from the furnace through the furnace outlet within multiple adjustment intervals according to the calculation results.

[0027] Compared with the prior art, the cooling method of the furnace body and the materials in the furnace of the present invention adopts a ventilation flow rate that is gradually changed according to the order of the adjustment interval to introduce air into the furnace body. The ventilation flow rate specifically changes with the temperature T 炉 Decrease and gradually increase. As the furnace body and the material in the furnace are cooled, the air introduction rate of the latter adjustment interval is greater than the air adjustment rate of the previous adjustment interval. The ventilation flow rate of each adjustment interval is closer to and does not exceed the ventilation flow rate upper limit of the adjustment interval. In this way, the furnace body temperature can be reduced from the right value of each adjustment interval to the left value of the adjustment interval more quickly, thereby significantly shortening the total time for the furnace body to drop from the starting and lowering temperature to the target temperature. It can also ensure that in each adjustment interval, dust explosion accidents will not be caused by excessively high furnace body outlet temperature and too rapid heating, and the risk of furnace body cracking and silicon carbide cracking is reduced. Ultimately, it can ensure that no dust explosion accidents will occur in the entire process of furnace body cooling, the quality of silicon carbide products is improved, and the performance and service life of the furnace body are guaranteed.

[0028] In some embodiments, in step C, m 空气 = ,ρ 空气 is the density of the air entering the furnace, X is the value of any fixed amplitude interval in step C within the preset time Gas intake , preset duration Not less than .

[0029] In some embodiments, the method further comprises

[0030] Step F

[0031] Under the ventilation condition of ventilation flow rate of 1.8m³ / h and taking 900℃ as the starting and ending temperature, =900℃=t+Δt, t=800℃, Δt=100℃ Calculate Q 安全 .

[0032] In some embodiments, the functional relationship T 出气 (T 炉 ) includes the third and fourth calculation formulas,

[0033] The third calculation formula is T 出气 = , the fourth calculation formula is T 出气 =0.3915T 炉 -55.02;

[0034] If Q obtained based on the third formula 安全 >Q obtained based on the fourth formula 安全 , and finally Q 安全 The value of Q is obtained based on the fourth calculation formula 安全 ;

[0035] If Q obtained based on the third formula 安全 <Q obtained based on the fourth calculation formula 安全 , and finally Q 安全 The value of Q is obtained based on the third calculation formula 安全 .

[0036] In some embodiments, in step F, m 空气 = , where ρ 空气 is the density of the air entering the furnace, V0 = 1.8m³ / h, S0 is the loss of Q by the furnace and the material 安全 The minimum allowable time for heat is S0 = 20 minutes.

[0037] In some embodiments, in step J, the regulated ventilation flow rate of each regulation interval is Substitute into the first calculation formula Calculate the final ventilation flow for each regulation interval , .

[0038] In some embodiments, in step J, the regulated ventilation flow rate of each regulation interval is And the compensation ventilation flow V required for each adjustment interval 补偿 Substitute into the second calculation formula Calculate the final ventilation flow for each regulation interval , =σ×( +V 补偿 ), 0.2≤σ≤0.6;

[0039] The method for cooling the furnace body and the material in the furnace further comprises:

[0040] Step G

[0041] Calculate the heat dissipation Q of the furnace body in each adjustment range (Ti, Ti + 20·N) 炉 And the heat dissipation Q of the material in the furnace 材料 sum Q 总 ;

[0042] Step H

[0043] Calculate the heat Q taken away by the air through convection heat transfer in each adjustment interval (Ti, Ti + 20·N) 热对流 ;

[0044] Step I

[0045] Calculate the required compensation ventilation flow V in each adjustment interval (Ti, Ti + 20·N) 补偿 , where V 补偿 = , where c 空气 is the specific heat capacity of the air entering the furnace, ρ 空气 is the density of the air entering the furnace.

[0046] In some embodiments, Q 总 =Q 炉 +Q 材料 , , , where c 炉 and m 炉 are the specific heat capacity and mass of the furnace body, c 材料 and m 材料 are the specific heat capacity and mass of the material in the furnace, respectively.

[0047] In some embodiments, , m 空气 =V 通入 ·ρ 空气 ,ΔT=20·N,V 通入 = ,in:

[0048] V 通入 is the volume of air undergoing convective heat transfer in each adjustment interval;

[0049] is the ventilation flow V and furnace temperature T 炉 The functional relationship of ;

[0050] is the derivative of the function g(s), g(s) is the furnace temperature T 炉 The function relationship between and time s is: ;

[0051] is the inverse function of the function g(s), a=Ti+20·N, b=Ti, for The function value when the independent variable is a, for The function value when the independent variable is b.

[0052] In some embodiments, the take-off and landing temperature T max The value range is 700℃≤T max ≤1000℃, target temperature T min The value range is 15℃≤T min ≤35℃, preset time It is 30 minutes, N=1, σ=0.4. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The function graph of the third calculation formula in one embodiment of the present invention and the temperature sampling data used to determine the third calculation formula;

[0054] Figure 2 The function graph of the fourth calculation formula in one embodiment of the present invention and the temperature sampling data used to determine the fourth calculation formula;

[0055] Figure 3 The ventilation flow rate V and the furnace temperature T in one embodiment of the present invention are shown in FIG. 炉 Functional relationship The function graph of ;

[0056] Figure 4 The furnace temperature T in one embodiment of the present invention is 炉 The function graph of g(s) as a function of time s. DETAILED DESCRIPTION

[0057] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0059] The present invention provides a method for cooling the furnace body and materials within an oxidation furnace. The oxidation furnace is a facility and material reaction site for the oxidation process, which is a crucial step in the silicon carbide production and preparation process. The furnace body of the oxidation furnace is filled with silicon carbide material, and the furnace body is provided with an inlet and an outlet. The inlet is used for external air to enter the furnace body, and the outlet is used for air to be discharged from the furnace body. After entering the furnace body, the external air can remove heat from the furnace body and the silicon carbide material within the furnace, thereby cooling the furnace body and the silicon carbide. When air is introduced into the furnace body, an external air source is connected to the inlet of the furnace body. The external air source is a device that supplies air to the furnace body. When the external air source introduces air into the furnace body, the air flow rate at the inlet can be monitored in real time. Unless otherwise specified, the units of various air flow rates appearing in the present invention are all m³ / h.

[0060] In some embodiments, the oxidation furnace is made of quartz and is tubular. A temperature measuring device is provided at the outlet of the furnace body. The temperature measuring device can measure the outlet temperature T of the furnace body in real time. 出气 Normally, the outlet temperature of the furnace is T 出气 and the inner cavity temperature of the furnace body (referred to as furnace temperature, T 炉 There is a functional relationship between the two, so the outlet temperature T 出气 Approximately know the furnace temperature T 炉 . Outlet temperature T 出气 and furnace temperature T 炉 The functional relationship between them is expressed as T 出气 (T 炉 ) indicates that in practice, T 出气 (T 炉 ) can be obtained through multiple test measurements, for example, by measuring several outlet temperatures T during the furnace cooling process. 出气 Value, each time the outlet temperature T is measured 出气 At the same time, the furnace temperature T is measured using a high temperature resistant temperature measuring device. 炉 , then at the outlet temperature T 出气 —Furnace temperature T 炉 Determine the coordinates of the above temperature measurement results in the coordinate system, and finally plot the points to get the function T 出气 (T 炉 ).

[0061] Specifically, T 出气 and T 炉 The functional relationship T 出气 (T 炉 ) includes the third and fourth calculation formulas, the third calculation formula is T 出气 = , the fourth calculation formula is T 出气 =0.3915T 炉-55.02. The function graphs of the third formula in the first quadrant and the fourth formula in the first quadrant are both increasing functions, where T 出气 and T 炉 The unit of temperature is Celsius. Unless otherwise specified, all temperature parameters in this invention are expressed in Celsius. Figure 1~Figure 2 , Figure 1 The function graph of the third calculation formula obtained by plotting points and linear regression fitting is: Figure 2 The function graph of the fourth calculation formula obtained by plotting points and fitting by linear regression method.

[0062] During the cooling process of the furnace body and the silicon carbide material in the furnace, the furnace temperature T 炉 The temperature of the silicon carbide material is approximately equal to that of the silicon carbide material in real time, that is, the temperature of the silicon carbide material is also T 炉 Indicates that the furnace body and silicon carbide material are heated from the starting and ending temperature T max Start to drop to the target temperature T min . Take-off and landing temperature T max Equivalent to the furnace temperature T when the external gas source starts to ventilate the furnace 炉 , target temperature T min It is equivalent to the temperature at the end of the furnace body and the material cooling. The target temperature is basically near the room temperature, so the starting and ending temperature T max and target temperature T min The difference (T max -T min ) is defined as the total temperature drop. In some embodiments, the starting and ending temperature T max The value range is 700℃≤T max ≤900℃, target temperature T min The value range is 15℃≤T min ≤35℃.

[0063] Before formally introducing the cooling method of the furnace body and the materials in the furnace of the present invention, the background knowledge and technical status of this field are first introduced. At present, the average time consumption for cooling the furnace body and the materials in the furnace of the oxidation furnace in the industry is 29 hours, that is, the oxidation furnace currently takes an average of 29 hours to cool down from the starting and lowering temperature to the target temperature, which undoubtedly greatly restricts the production efficiency of silicon carbide powder. Although it is known in the art that increasing the rate of air introduction from the external gas source into the furnace body and increasing the ventilation flow at the furnace body inlet can speed up the heat dissipation rate of the furnace body and the materials in the furnace, thereby shortening the cooling time of the oxidation furnace, few people dare to implement it. The main reason is that no one in the art currently knows the maximum upper limit of the ventilation flow at the furnace body inlet. Once the rate of air introduction into the furnace body is too large, it will inevitably cause the outlet of the furnace body to heat up rapidly, which will cause a silicon carbide dust explosion accident. In addition, the excessive rate of air introduction will also increase the risk of cracking of the furnace body and silicon carbide. For the sake of safe production, the art currently generally introduces air into the furnace body at a constant rate, and the art can determine: the furnace temperature T 炉 From the take-off and landing temperature T max It is safe to drop 100℃ within 20 minutes, and the furnace temperature T 炉 From the take-off and landing temperature T max It is undoubtedly safer to drop the temperature by 100℃ in more than 20 minutes.

[0064] The following describes a method for cooling a furnace body and materials in the furnace according to the present invention, which comprises the following steps:

[0065] Step A

[0066] Measure the outlet temperature T of the furnace 出气 and furnace temperature T 炉 , and get about T 出气 and T 炉 The functional relationship T 出气 (T 炉 );

[0067] Step B

[0068] In T max Determine multiple fixed amplitude intervals within the following temperature range. The left value of any fixed amplitude interval is equal to , the rvalue is equal to ,

[0069] Among them, T max and T min The furnace temperature T 炉 The take-off and landing temperature and target temperature, n is the fixed amplitude interval from T max to T min Ordinal numbers in descending order;

[0070] Step C

[0071] according to Calculate the time of any fixed amplitude interval in the preset time Gas intake ,

[0072] Among them, Q 安全 is the furnace temperature T 炉 From T max The sum of the heat dissipation of the furnace body and the heat dissipation of the materials in the furnace after the temperature drops by 100°C in S0 minutes.

[0073] S0 is the temperature of the furnace body and the materials in the furnace max Started to cool down and lost Q 安全 The minimum allowable time for heat is S0 = 20 minutes, t = , Δt=100,

[0074] c 空气 is the specific heat capacity of the air entering the furnace, m 空气 To take away Q 安全 The mass of air used for heat, T 进气 is the inlet temperature of the furnace;

[0075] Step D

[0076] In T max Multiple adjustment intervals are determined within the following temperature range. The left value of any adjustment interval is Ti, and the right value is Ti+20·N. The value set of N is {1, 2, 3, 4};

[0077] Step E

[0078] In the case of multiple fixed amplitude intervals associated with any adjustment interval (Ti, Ti + 20·N) The minimum value is taken as the regulated ventilation flow in the regulation interval , wherein the multiple fixed amplitude intervals associated with the adjustment interval are arranged in descending order and include:

[0079] (Ti, Ti + 100),

[0080] (Ti-20, Ti+80),

[0081] (Ti-40, Ti+60),

[0082] ...、

[0083] (Ti+20·N-80, Ti+20·N+20),

[0084] (Ti+20·N-100, Ti+20·N);

[0085] Step J

[0086] Adjust the ventilation flow in each adjustment interval Substitute into the first calculation formula Or the second formula Calculate the final ventilation flow for each regulation interval , according to the final ventilation flow The air is introduced into the furnace through the furnace inlet and discharged from the furnace through the furnace outlet within multiple adjustment intervals according to the calculation results.

[0087] The method for cooling the furnace body and the material in the furnace of the present invention adopts a ventilation flow rate stepwise variation method to introduce air into the furnace body according to the order of the adjustment interval. The adjustment interval is determined by step D. The adjustment interval is specifically T max The following temperature ranges have a span of 20·N℃ for each adjustment interval. The span of the adjustment interval is the difference between the right value and the left value of the same adjustment interval. The larger the span of the adjustment interval, the fewer the number of adjustment intervals to be determined, and vice versa. Before determining the adjustment interval, determine multiple fixed amplitude intervals and the preset time length of each fixed amplitude interval. Gas intake , the fixed amplitude range is also lower than T max The temperature interval within the temperature range, the span of each fixed amplitude interval is equal to 100℃.

[0088] According to step B, starting and ending temperature T max Starting from, all fixed amplitude intervals are arranged in descending order as follows (T max -100, T max )、(T max -200, T max -100), (T max -300, T max -200), (T max -400, T max -300), ..., that is, the first fixed amplitude interval, the second fixed amplitude interval, the third fixed amplitude interval, and the fourth fixed amplitude interval are (T max -100, T max )、(T max -200, T max -100), (T max -300, T max -200), (T max -400, T max -300), the ordinal numbers n of the first fixed amplitude interval, the second fixed amplitude interval, the third fixed amplitude interval, and the fourth fixed amplitude interval are 1, 2, 3, 4, ..., and so on. In this embodiment, the take-off and landing temperature T maxThe temperature is 900°C, and the first fixed amplitude interval, the second fixed amplitude interval, the third fixed amplitude interval and the fourth fixed amplitude interval are (800, 900), (700, 800), (600, 700) and (500, 600) respectively.

[0089] Specifically, the method for cooling the furnace body and the material in the furnace further includes step F, which comprises: under a ventilation condition with a ventilation rate of 1.8 cubic meters per hour (1.8 m³ / h),

[0090] With 900℃ as the starting and ending temperature, T max =900℃=t+Δt, t=800℃, Δt=100℃ Calculate Q 安全 .

[0091] At present, it can be determined in this field that: when the external gas source is stably ventilated to the furnace inlet at a ventilation flow rate of 1.8m³ / h, the furnace temperature T 炉 It is safe to reduce the temperature from 900℃ to 800℃ within 20 minutes by 100℃ without causing dust explosion and cracking of furnace material. Therefore, step F is to find the furnace temperature T 炉 The heat lost by the oxidation furnace and the materials in the furnace is reduced by 100°C from 900°C in 20 minutes. In this embodiment, S0 = 20 minutes. In other embodiments, S0 can also be greater than 20 minutes, as long as S0 is not less than 20 minutes. The larger S0 is, the lower the temperature of the oxidation furnace and the furnace is from T max Q is lost when the temperature drops by 100℃ 安全 The slower the oxidation, the safer it is for the furnace and the material.

[0092] In step C, the preset time length of each fixed amplitude interval is obtained. Gas intake Before that, you need to perform step F first.

[0093] Then Q 安全 Substitution For example, calculate the first fixed amplitude interval in the preset time Gas intake When n=1, t+Δt=T max ; Calculate the second fixed amplitude interval in the preset time Gas intake When n=2, t+Δt=T max -100; calculate the third fixed amplitude interval in the preset time Gas intake When n=3, t+Δt=T max -200; calculate the fourth fixed amplitude interval in the preset time Gas intake When n=4, t+Δt=T max -300; calculate the fifth fixed amplitude interval in the preset time Gas intake When n=5, t+Δt=T max -400, and so on. In addition, when calculating the preset time length of each fixed amplitude interval, Gas intake When Δt is taken as 100℃.

[0094] It is worth noting that when executing step F to calculate Q 安全 When T 出气 (T 炉 )'s third formula T 出气 = And the fourth calculation formula T 出气 =0.3915T 炉 -55.02 are substituted , that is, find the two Q 安全 , then in the two Q 安全 The smaller one is selected as the final Q 安全 , then execute step C to calculate the time of each fixed amplitude interval Gas intake When both Q 安全 Substitute the smaller one , that is:

[0095] If Q obtained based on the third formula 安全 >Q obtained based on the fourth formula 安全 , and finally Q 安全 The value of Q is obtained based on the fourth calculation formula 安全 ;

[0096] If Q obtained based on the third formula 安全 <Q obtained based on the fourth calculation formula 安全 , and finally Q 安全 The value of Q is obtained based on the third calculation formula 安全 .

[0097] Preferably, before executing step F to calculate Q 安全 hour,

[0098] T 出气 (T 炉 )'s third formula T 出气 = Substitution Compared with the fourth calculation formula, the third calculation formula can more accurately reflect the outlet temperature T 出气 and furnace temperature T 炉The quantitative relationship between them is based on the Q obtained by the third calculation formula. 安全 <Q obtained based on the fourth calculation formula 安全 , and finally Q 安全 The smaller the value, the safer the furnace body and the materials inside the furnace are and the lower the risk of cracking.

[0099] Furthermore, in step C, m 空气 = ,ρ 空气 is the density of the air entering the furnace, X is the result required in step C, that is, X represents the value of any fixed amplitude interval in the preset time. Gas intake , preset duration Not less than ; In step F, m 空气 = , where ρ 空气 is the density of the air entering the furnace, V0 = 1.8m³ / h, V0 represents the initial rate of air entering the oxidation furnace through the furnace inlet to cool the furnace and the material, S0 is the rate at which the furnace and the material lose Q 安全 The minimum allowable time for heat is S0 = 20 minutes. In steps C and F, c 空气 The value is 1.003kJ / (kg·K), ρ 空气 The value is 1.29kg / m³; the inlet temperature of the furnace is T 进气 It can be measured by a temperature measuring device set at the entrance of the furnace. Preferably, in step C, the preset time The value of is 30 minutes. In other embodiments, It can be longer or shorter than 30 minutes, as long as No less than 20 minutes, preset duration The larger the value, the safer the oxidation furnace and the materials inside the furnace, and the lower the risk of dust explosion accidents, but the cooling efficiency is worse and the heat dissipation takes longer.

[0100] Step D aims to max The following temperature range determines multiple adjustment intervals with equal temperature spans. These adjustment intervals will be used by workers to adjust the ventilation rate of the external air source to change the temperature range of the furnace body and the material cooling rate. The temperature span of the adjustment interval is expressed in 20·N. In general, the oxidation furnace and the material in the furnace drop a certain temperature each time to make the furnace temperature T 炉Every time the temperature drops by about 20°C, workers will conduct a production inspection. Production inspection is an opportunity for workers to adjust the ventilation rate of air supplied from the external air source to the oxidation furnace. The smaller N is, the smaller the temperature span of the adjustment range is. The more frequently the workers adjust the ventilation rate, the more helpful it is to speed up the cooling rate of the oxidation furnace and the materials in the furnace to shorten the cooling time. When N is equal to 1, workers must adjust the ventilation rate once for each production inspection. When N is 2, workers adjust the ventilation rate once every two production inspections. When N is 3, workers adjust the ventilation rate once every three production inspections. When N is 4, workers adjust the ventilation rate once every four production inspections.

[0101] In fact, if we perform step F and solve for Q 安全 , then for T max For any fixed amplitude interval within the following temperature range, the algorithm in step C can be used to calculate the fixed amplitude interval within the preset time. Gas intake , but not limited to obtaining the first fixed amplitude interval, the second fixed amplitude interval, the third fixed amplitude interval, the fourth fixed amplitude interval, etc. within the preset time length Gas intake Even if the two fixed amplitude intervals have overlapping parts, the algorithm in step C can still be used to calculate the two fixed amplitude intervals within the preset time. Gas intake For example, the algorithm of step C can be used to respectively calculate the three fixed amplitude intervals (600, 700), (580, 680), and (560, 660) within the preset time. Gas intake .

[0102] For any adjustment range (Ti, Ti + 20·N):

[0103] If N=1, the multiple fixed amplitude intervals associated with (Ti, Ti+20·N) are arranged in descending order: (Ti, Ti+100), (Ti-20, Ti+80), (Ti-40, Ti+60), (Ti-60, Ti+40);

[0104] If N=2, the multiple fixed amplitude intervals associated with (Ti, Ti+20·N) are arranged in descending order: (Ti, Ti+100), (Ti-20, Ti+80), (Ti-40, Ti+60);

[0105] If N=3, the multiple fixed amplitude intervals associated with (Ti, Ti+20·N) are arranged in descending order and include: (Ti, Ti+100), (Ti-20, Ti+80).

[0106] Assume N=3, and want to determine the regulated ventilation flow rate in the regulation interval (600, 660) , then according to step E, first determine the three fixed amplitude intervals (600, 700), (580, 680), (560, 660) associated with the adjustment interval (600, 660), and then calculate the three fixed amplitude intervals (600, 700), (580, 680), (560, 660) in the preset time. Gas intake , if the three fixed amplitude intervals (600, 700), (580, 680), and (560, 660) are calculated by step C, they are each within the preset time Gas intake If x, y, and z are respectively, then the regulated ventilation flow in the regulation interval (600, 660) =min{x, y, z}, i.e. the regulated ventilation flow in the final regulation interval (600, 660) Gas flow in three fixed amplitude intervals (600, 700), (580, 680), (560, 660) The smallest of them is produced;

[0107] Assume N=1, and determine the regulated ventilation flow rate in the regulation interval (600, 620) , then according to step E, first determine the five fixed amplitude intervals (600, 700), (580, 680), (560, 660), (540, 640), (520, 620) associated with the adjustment interval (600, 620), and then calculate the five fixed amplitude intervals (600, 700), (580, 680), (560, 660) in the preset time. Gas intake , if the five fixed amplitude intervals (600, 700), (580, 680), (560, 660), (540, 640), and (520, 620) are calculated by step C, they are each within the preset time length Gas intake If they are i, j, u, v, and w respectively, then the regulated ventilation flow in the regulation interval (600, 620) , =min{i, j, u, v, w}, i.e., the regulated ventilation flow rate in the final regulation interval (600, 620) Gas flow rate in five fixed amplitude intervals (600, 700), (580, 680), (560, 660), (540, 640), (520, 620) The smallest one among them is produced.

[0108] The above only illustrates the regulation of ventilation flow in the regulation intervals (600, 660) and (600, 620). For any one of the adjustment intervals determined by step D, the regulated ventilation flow rate of the adjustment interval is The formation method of is applicable to step E, which will not be repeated here.

[0109] For N=2 and N=4, the regulated ventilation flow in the regulation interval The generation of is still applicable to step E, and reference may be made to the cases of N=1 and N=3, which will not be repeated here.

[0110] The final ventilation flow determined by step J This is the ventilation rate that workers need to achieve when adjusting the external air source to change the ventilation rate during production inspections. For example, the ventilation flow rate in the adjustment interval (600, 660) After step J determines that it is z, then the worker needs to 炉 When the temperature is between 600℃ and 660℃, adjust the ventilation rate of the external gas source into the furnace so that the gas flow rate at the furnace inlet reaches z. 出气 It can be measured in real time by a temperature measuring device, and the outlet temperature T 出气 and furnace temperature T 炉 The functional relationship between 出气 (T 炉 ) is known, then the real-time furnace temperature T 炉 According to the real-time outlet temperature T 出气 and T 出气 (T 炉 ) is determined by its inverse function.

[0111] Preferably, for determining the real-time furnace temperature T 炉 T 出气 (T 炉 )T 出气 (T 炉 )'s third formula T 出气 = shall prevail.

[0112] Specifically, step J is used to determine the final ventilation flow rate of each adjustment interval. The first calculation formula is , the second calculation formula is =σ×( +V 补偿 ), 0.2≤σ≤0.6, in the second calculation formula, V 补偿 Indicates the compensation ventilation flow required for each adjustment interval. In practice, the first calculation formula can be used to calculate To determine the final ventilation flow in each regulation interval , you can also use the second calculation formula for the purpose of safety and efficiency =σ×( +V 补偿 ) to determine the final ventilation flow in each adjustment interval If the first calculation formula is used to determine the final ventilation flow , then the oxidation furnace and the material in the furnace will change from the starting and ending temperature T max Drop to target temperature T min The time taken is about 750 minutes, which is a significant reduction compared to the existing technology which takes 1740 minutes. If the second calculation formula is used to determine the final ventilation flow , and without considering the scaling factor σ (the default scaling factor σ is 1), the oxidation furnace and the material in the furnace are max Down to T min The time taken is about 180 minutes. In order to prevent dust explosion and furnace cracking, and V 补偿 The sum of the two numbers multiplied by the scaling factor σ gives the final ventilation flow .

[0113] Through the second calculation formula =σ×( +V 补偿 ) Determine the final ventilation flow The essence is to adjust the ventilation flow by using an external gas source On the basis of introducing air into the furnace at a ventilation rate, the rate at which air is introduced into the furnace from an external air source is further increased, that is, the amount of air introduced into the furnace per unit time is increased. The increased amount of air introduced per unit time is intended to compensate for the amount of air required for heat convection. Heat convection, heat conduction and heat radiation are three ways to achieve heat exchange between objects and are well known in the art. As long as an external air source introduces air into the furnace, the air will inevitably undergo three heat exchange modes of heat convection, heat conduction and heat radiation at the same time. The reason why the final ventilation flow rate is determined by the second calculation formula The final cooling time (180 minutes) obtained is less than the final ventilation flow determined by the first calculation formula The final cooling time (750 minutes) is obtained because: as the oxidation furnace and the materials in the furnace continue to cool down, the ability of the oxidation furnace and the materials to dissipate heat to the outside through heat conduction and heat radiation gradually decreases. Therefore, in the middle and late stages of the oxidation furnace and the materials cooling down, it is necessary to increase the amount of air introduced into the furnace per unit time to compensate for the reduction in heat conduction and heat radiation caused by the temperature drop. This is also safe. The lower the temperature of the furnace body and the material, the lower the risk of dust explosion and furnace cracking. When the temperature drops, it is permissible to moderately increase the amount of air introduced into the furnace per unit time. The final ventilation flow rate determined by the first calculation formula is When air is introduced into the furnace, the air undergoes convection, conduction, and radiation simultaneously, but not all of the air is used for convection. This means that the air used for conduction and radiation reduces the air used for convection, resulting in the air used for convection being far below the critical amount that triggers dust explosions and furnace cracking. Explosion and cracking accidents are not related to heat conduction and radiation, so insufficient air is used for convection. 补偿 To compensate a certain amount of air for each adjustment interval so that the compensated air can perform thermal convection, thereby making up for the shortage of air used for thermal convection. The compensated air makes the air used for thermal convection closer to but not exceeding the critical amount that triggers dust explosion and furnace cracking.

[0114] The Boltzmann constant and other important parameters of the oxidation furnace are unknown, so the furnace body and material are directly calculated from the starting and ending temperature T max Drop to target temperature T min The heat loss through heat conduction and heat radiation during the process is almost impossible to calculate, but the temperature of the furnace body and the material inside the furnace from the starting and ending temperature T can be calculated. max Drop to target temperature T min The total heat dissipation during the process can also be calculated. Of course, the total heat dissipation of the furnace body and the materials in the furnace in any adjustment range can also be calculated. The total heat dissipation is the sum of the heat dissipated by the furnace body and the materials through heat convection, heat conduction and heat radiation. The mass and specific heat capacity of the furnace body and the materials in the furnace are known. The heat dissipation of the furnace body and the materials in the furnace in a certain temperature range can be calculated according to the formula Q = c·m·ΔT. Simply substitute the mass and specific heat capacity of the furnace body into the formula Q = c·m·ΔT to obtain the heat dissipation Q of the furnace body in a certain temperature range. 炉 , just substitute the mass of the material in the furnace and the specific heat capacity of the material into the formula Q = c·m·ΔT to obtain the heat dissipation Q of the material in the furnace within a temperature range. 材料 Therefore, the following steps can be used to avoid directly calculating the heat lost by the furnace body and materials due to heat conduction and heat radiation, thereby more quickly determining the required compensation ventilation flow V for each adjustment interval. 补偿 .

[0115] In this regard, the method for cooling the furnace body and the material in the furnace of the present invention further includes:

[0116] Step G: Calculate the heat dissipation Q of the furnace body in each adjustment interval (Ti, Ti + 20·N) 炉 And the heat dissipation Q of the material in the furnace 材料 sum Q 总 ;

[0117] Step H: Calculate the heat Q taken away by the air through convection heat transfer in each adjustment interval (Ti, Ti + 20·N) 热对流 ;

[0118] Step I: Calculate the required compensation ventilation flow V in each adjustment interval (Ti, Ti + 20·N) 补偿 , where V 补偿 = , where c 空气 is the specific heat capacity of the air entering the furnace, ρ 空气 is the density of the air entering the furnace.

[0119] Specifically, for any adjustment interval (Ti, Ti + 20·N), there is always Q 总 =Q 炉 +Q 材料 , , , c 炉 and m 炉 are the specific heat capacity and mass of the furnace body, c 材料 and m 材料 are the specific heat capacity and mass of the materials in the furnace respectively; the value set of N is {1, 2, 3, 4}. , m 空气 =V 通入 ·ρ 空气 ,ΔT=20·N,V 通入 = , where V 通入 is the volume of air undergoing convective heat transfer in each adjustment interval; is the ventilation flow V and furnace temperature T 炉 The functional relationship of ; is the derivative of the function g(s), g(s) is the furnace temperature T 炉 The function relationship between and time s is: ; is the inverse function of the function g(s), a=Ti+20·N, b=Ti, for The function value when the independent variable is a, for The function value when the independent variable is b.

[0120] Step G, step H and step I reveal that: if the compensation ventilation flow V required for each adjustment interval is to be calculated 补偿 , it is only necessary to calculate the heat dissipation Q of the furnace body in each adjustment range 炉 And the material Q in the furnace 材料 The sum of the heat dissipation Q 总 , and the heat Q taken away by the air in each adjustment range by convection heat exchange 热对流 , Q 热对流 The heat lost by heat conduction and heat radiation is not included, and the Q of each adjustment interval is 总 and Q热对流 The difference is taken as the numerator, As the denominator, calculate (Q 总 -Q 热对流 )and Business. Parameters in This is the preset duration in step C. The Q of each adjustment interval is 总 and Q 热对流 The difference is the sum of the heat lost by the furnace body and the materials in the furnace through heat conduction and heat radiation in each adjustment interval. Therefore, the compensation ventilation flow V required for each adjustment interval is calculated. 补偿 The key is to calculate the heat Q that the air takes away by convection in each adjustment interval. 热对流 .

[0121] The applicant collects the furnace temperature T 炉 and the ventilation flow rate V at the furnace inlet, and then establish the furnace temperature T 炉 The coordinate system with the ventilation flow V at the furnace entrance as the horizontal axis and the vertical axis is the collected furnace temperature T 炉 and ventilation flow V, and then the ventilation flow V and furnace temperature T are obtained by linear regression fitting. 炉 Functional relationship , , it can be noted that In addition, the applicant also recorded a series of furnace temperatures T that changed over time. 炉 Then establish a time s as the horizontal axis and furnace temperature T 炉 The vertical axis is the coordinate system, and the furnace temperature T 炉 Plot the points, and then use linear regression fitting to get the value of the furnace temperature T 炉 The functional relationship between g(s) and time s is: , we can further get the derivative function of g(s) and the inverse function of g(s) , we can get the first-order derivative of g(s) by , Reactor temperature T 炉 The time required for the temperature of the material in the furnace to drop by one degree Celsius. Figure 3~Figure 4 , Figure 3 Indicates the furnace temperature T 炉 , ventilation flow V at the furnace inlet and the functional relationship The fitted image of Figure 4 Indicates the furnace temperature T 炉 Changes over time and the fitted graph of the functional relationship g(s).

[0122] According to Q 热对流 =c空气 m 空气 ΔT, m 空气 =V 通入 ·ρ 空气 ,ΔT=20·N,V 通入 = The heat Q taken away by air through convection in each adjustment range can be obtained 热对流 , substitute a=Ti+20·N, b=Ti into V 通入 = After that, V 通入 The calculation expression can be written as V 通入 = . V 通入 The specific calculation process will not be described in detail.

[0123] Optionally, when executing step I, the preset time For 30 minutes, N = 1, calculate the required compensation ventilation flow V for each adjustment interval 补偿 and the regulated ventilation flow in each regulation interval Afterwards, according to =σ×( +V 补偿 ) Calculate the final ventilation flow in each adjustment interval When σ=0.4.

[0124] Whether using the first calculation formula Obtain the final ventilation flow , or use the second calculation formula Obtain the final ventilation flow , final ventilation flow They all have the same changing law, that is, as the furnace body and the material in the furnace cool down, the final ventilation flow rate in the latter adjustment interval Greater than the final ventilation flow of the previous adjustment interval , final ventilation flow As the furnace temperature T 炉 The temperature of the material in the furnace decreases and gradually increases, and the final ventilation flow rate of each adjustment interval Both can ensure the safety of the oxidation furnace and the materials in the furnace in the adjustment range, and neither exceeds the maximum ventilation flow limit allowed in the adjustment range.

[0125] The present invention adopts a ventilation flow rate step-by-step change method to introduce air into the furnace body according to the order of the adjustment interval. The ventilation flow rate specifically changes with the temperature T 炉As the furnace body and the material in the furnace cool down, the air intake rate in the latter adjustment interval is greater than the air adjustment rate in the previous adjustment interval, and the ventilation flow rate in each adjustment interval is closer to and does not exceed the ventilation flow upper limit of the adjustment interval. 炉 The temperature of the material in the furnace can be reduced from the right value of each adjustment interval to the left value of the adjustment interval more quickly, thereby significantly shortening the time it takes for the furnace body and the material in the furnace to change from the starting and ending temperature T max Reduce to target temperature T min The total time, and ensure that in each adjustment range there will be no 出气 The risk of dust explosion accidents caused by excessively high temperatures and rapid heating is reduced, the risk of furnace body cracking and silicon carbide cracking is reduced, the quality of silicon carbide products is improved, and the performance and service life of the furnace body are guaranteed.

[0126] The various technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the various technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present invention and are not intended to limit the present invention. Any appropriate changes and modifications to the above embodiments fall within the scope of the present invention as long as they are within the spirit of the present invention.

Claims

1. A method for cooling a furnace body and materials in the furnace, characterized in that: include: Step A Measure the outlet temperature T of the furnace 出气 and furnace temperature T 炉 , and get about T 出气 and T 炉 The functional relationship T 出气 (T 炉 ); Step B In T max Determine multiple fixed amplitude intervals within the following temperature range. The left value of any fixed amplitude interval is equal to , the rvalue is equal to , Among them, T max and T min The furnace temperature T 炉 The take-off and landing temperature and target temperature, n is the fixed amplitude interval from T max to T min Ordinal numbers in descending order; Step C according to Calculate the time of any fixed amplitude interval in the preset time Gas intake , Among them, Q 安全 is the furnace temperature T 炉 From T max The sum of the heat dissipation of the furnace body and the heat dissipation of the materials in the furnace after the temperature drops by 100°C in S0 minutes. S0 is the temperature of the furnace body and the materials in the furnace max Started to cool down and lost Q 安全 The minimum allowable time for heat, t = , Δt=100, c 空气 is the specific heat capacity of the air entering the furnace, m 空气 To take away Q 安全 The mass of air used for heat, T 进气 is the inlet temperature of the furnace; Step D In T max Multiple adjustment intervals are determined within the following temperature range. The left value of any adjustment interval is Ti, and the right value is Ti+20·N. The value set of N is {1, 2, 3, 4}; Step E In the case of multiple fixed amplitude intervals associated with any adjustment interval (Ti, Ti + 20·N) The minimum value is taken as the regulated ventilation flow in the regulation interval , wherein the multiple fixed amplitude intervals associated with the adjustment interval are arranged in descending order and include: (Ti, Ti + 100), (Ti-20, Ti+80), (Ti-40, Ti+60), ……、 (Ti+20·N-80, Ti+20·N+20), (Ti+20·N-100, Ti+20·N); Step G Calculate the heat dissipation Q of the furnace body in each adjustment range (Ti, Ti + 20·N) 炉 And the heat dissipation Q of the material in the furnace 材料 sum Q 总 ; Step H Calculate the heat Q taken away by the air through convection heat transfer in each adjustment interval (Ti, Ti + 20·N) 热对流 ; Step I Calculate the required compensation ventilation flow V in each adjustment interval (Ti, Ti + 20·N) 补偿 , where V 补偿 = , where c 空气 represents the specific heat capacity of the air entering the furnace, ρ 空气 is the density of the air entering the furnace; Step J Adjust the ventilation flow in each adjustment interval Substitute into the first calculation formula Or the second formula Calculate the final ventilation flow for each regulation interval , according to the final ventilation flow The air is introduced into the furnace through the furnace inlet and discharged from the furnace through the furnace outlet within a plurality of adjustment intervals according to the calculation results; The first calculation formula is , the second calculation formula is =σ×( +V 补偿 ), 0.2≤σ≤0.

6.

2. The method for cooling the furnace body and the material in the furnace according to claim 1, wherein: In step C, m 空气 = , ρ 空气 is the density of the air entering the furnace, X is the value of any fixed amplitude interval in step C within the preset time Gas intake , preset duration Not less than .

3. The method for cooling the furnace body and the material in the furnace according to claim 1, wherein: The method further includes Step F Under the ventilation condition of ventilation flow rate of 1.8m³ / h and taking 900℃ as the starting and ending temperature, =900℃=t+Δt, t=800℃, Δt=100℃ Calculate Q 安全 .

4. The method for cooling the furnace body and the material in the furnace according to claim 3, wherein: Functional relation T 出气 (T 炉 ) includes the third and fourth calculation formulas, The third calculation formula is T 出气 = , the fourth calculation formula is T 出气 =0.3915T 炉 -55.02; If Q obtained based on the third formula 安全 >Q obtained based on the fourth formula 安全 , and finally Q 安全 The value of Q is obtained based on the fourth calculation formula 安全 ; If Q obtained based on the third formula 安全 <Q obtained based on the fourth calculation formula 安全 , and finally Q 安全 The value of Q is obtained based on the third calculation formula 安全 .

5. The method for cooling the furnace body and the material in the furnace according to claim 3, wherein: In step F, m 空气 = , where ρ 空气 is the density of the air entering the furnace, V0 = 1.8m³ / h, S0 is the loss of Q by the furnace and the material 安全 The minimum allowable time for heat is S0 = 20 minutes.

6. The method for cooling the furnace body and the material in the furnace according to claim 1, wherein: Q 总 =Q 炉 +Q 材料 , , , where c 炉 and m 炉 are the specific heat capacity and mass of the furnace body, c 材料 and m 材料 are the specific heat capacity and mass of the material in the furnace, respectively.

7. The method for cooling the furnace body and the material in the furnace according to claim 1, wherein: ,m 空气 =V 通入 ·r 空气 , ΔT=20·N, V 通入 = , among which: V 通入 is the volume of air undergoing convective heat transfer in each adjustment interval; is the ventilation flow V and furnace temperature T 炉 The functional relationship of ; is the derivative of the function g(s), g(s) is the furnace temperature T 炉 The function relationship between and time s is: ; is the inverse function of the function g(s), a=Ti+20·N, b=Ti, for The function value when the independent variable is a, for The function value when the independent variable is b.

8. The method for cooling the furnace body and the material in the furnace according to claim 1, wherein: Take-off and landing temperature T max The value range is 700℃≤T max ≤1000℃, target temperature T min The value range is 15℃≤T min ≤35℃, preset time It is 30 minutes, N=1, σ=0.4.

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