A simulated control method for reducing the burning loss rate of dry quenching coke oven

Abstract

The application discloses a simulation regulation method for reducing the burning loss rate of a dry quenching coke oven, and utilizes an improved simulation device for the burning loss rate of the dry quenching coke oven and a circulating gas optimization method of the dry quenching coke oven, so that a coking enterprise can carry out the burning loss rate analysis of the dry quenching coke oven under different working conditions with a lower cost and a shorter period, efficiently and accurately determines the regulation scheme of the circulating gas composition in the dry quenching coke oven, and effectively reduces the burning loss rate of the dry quenching coke oven. The simulation regulation method is simple, convenient to operate, low in cost, short in period, and suitable for popularization and application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coking, and particularly relates to a simulation control method and device for reducing the burning loss rate of a dry quenching coke oven. BACKGROUND

[0002] Due to the process characteristics of the dry quenching coke technology, there is a burning loss phenomenon of coke in the dry quenching process, and the burned coke accounts for a large part of the cost, which seriously affects the operation benefit of the dry quenching coke, and the burning loss of coke is not conducive to the reduction of CO2 emission. Therefore, the burning loss rate of the dry quenching coke is concerned by many coking enterprises, and the pursuit of a lower dry quenching coke burning loss rate has great significance for the enterprises to reduce the production cost of the dry quenching coke, improve the yield and efficiency of the dry quenching coke, and realize energy saving, consumption reduction and emission reduction of the coking industry.

[0003] At present, the existing analysis and research on the dry quenching coke burning loss rate are mostly based on data statistics and theoretical calculation in a certain period, and a series of optimization control schemes are adopted after analysis, in which the optimization control of the circulating gas composition is one of the most commonly used means for coking enterprises to reduce the dry quenching coke burning loss rate. After adopting these optimization control schemes, the implementation effect is generally tested through data statistics and theoretical calculation of carbon balance, oxygen balance and ash balance for more than one week, which is difficult to quickly and directly reflect the implementation effect, resulting in a long optimization debugging period and high cost of the circulating gas composition of the dry quenching coke, which is not conducive to the reduction of the operation cost of the enterprise.

[0004] Therefore, it is of great economic, environmental and application significance to further explore a low-cost and high-efficiency simulation method for the dry quenching coke burning loss rate, and to realize effective analysis of the dry quenching coke burning loss rate under different working conditions, so as to reasonably control the circulating gas composition of the dry quenching coke, reduce the dry quenching coke burning loss rate and production cost. SUMMARY

[0005] The main purpose of the present application is to provide an experimental method for reducing the dry quenching coke burning loss rate, which utilizes an improved simulation control method for the dry quenching coke burning loss rate, so as to facilitate the coking enterprises to carry out analysis of the dry quenching coke burning loss rate under different working conditions at a lower cost, thereby reasonably controlling the circulating gas composition of the dry quenching coke and reducing the dry quenching coke burning loss rate. The simulation control method is simple, convenient to operate, low in cost, short in period, and suitable for popularization and application.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A simulation control method for reducing the dry quenching coke burning loss rate, comprising the following steps:

[0008] 1) Take the coke of dry quenching coke oven ≥25mm in proportion, crush and mix uniformly, remove flaky coke and strip-shaped coke, and prepare coke blocks with a particle size of 15-20mm; the prepared coke is divided into several groups, dried and ready for use, and several groups of coke samples are obtained;

[0009] 2) Stack the coke samples in the reactor and put them into the heating furnace, and the weight of the coke samples is recorded as m1;

[0010] 3) After detecting the airtightness, connect the power supply, heat the heating furnace to 920-950℃ in a protective atmosphere, and after a period of constant temperature stabilization, start the air blower and pass the dry quenching coke oven circulating gas according to the air-material ratio set for the dry quenching coke oven;

[0011] 4) Programmed cooling to reduce the temperature of the heating furnace to below 150℃, stop heating, cut off the circulating gas, and cool to room temperature, then take out the coke and weigh it, recorded as m2;

[0012] 5) Calculate the coke burn-off rate X, wherein

[0013] 6) According to the obtained coke burn-off rate X, the coke burn-off rate in the dry quenching coke oven is characterized, and compared with the design value of the burn-off rate:

[0014] When the difference between the burn-off rate and the design value is ≤0.2%, the existing circulating gas composition is maintained unchanged;

[0015] When the difference between the burn-off rate and the design value is >0.2%, under the premise that the air-material ratio remains unchanged, by adjusting the opening degree of the air guide valve, under the premise of ensuring that the combustible components CO≤6% and H2≤3% in the circulating gas, a number of optimization schemes of dry quenching coke circulating gas composition are set;

[0016] 7) According to the set dry quenching coke circulating gas composition optimization scheme, repeat steps 1)-5) to determine the coke burn-off rate X corresponding to different optimization schemes;

[0017] 8) Select the optimization scheme with the lowest coke burn-off rate X to control and optimize the dry quenching coke circulating gas composition in production to reduce the dry quenching coke burn-off rate.

[0018] In the above scheme, the coke is sampled according to the provisions of GB / T 1997-2008 "Sampling and Preparation of Coke".

[0019] In the above scheme, the mass of each group of coke samples is not less than 600g.

[0020] Further, the mass of the coke sample in step 2) is 450-550g.

[0021] In the above scheme, the coke sample in step 2) is evenly stacked in the reactor in a manner of high in the middle and low on both sides.

[0022] In the above scheme, the protective atmosphere in step 3) can be nitrogen or argon, etc.

[0023] In the above scheme, the main gases in the dry quenching coke oven circulating gas include O2, CO, CO2 and H2 (the rest is nitrogen).

[0024] In the above scheme, the heating rate in step 3) is 7-15 ℃ / min.

[0025] In the above scheme, the constant temperature stabilization time in step 3) is 5-10 min.

[0026] In the above scheme, the programmed cooling step includes: ≥920 ℃ for 10-15 min, 920-800 ℃ for 15-20 min, 800-700 ℃ for 18-22 min, 700-600 ℃ for 18-22 min, 600-500 ℃ for 18-22 min, 500-400 ℃ for 18-22 min, 400-300 ℃ for 23-27 min, 300-150 ℃ for 18-25 min.

[0027] In the above scheme, the air-to-biomass ratio used in step 3) is 1300-1500 m 3 / t.

[0028] In the above scheme, the air guide valve opening in step 6) is 0-100%.

[0029] In the above scheme, the burnout rate design value is usually set to 0.9-1.0%.

[0030] In the above scheme, the determination method of the optimization scheme includes:

[0031] Under the premise of ensuring that the combustible components CO≤6% and H2≤3% in the circulating gas, a plurality of air introduction valve control schemes are set according to the rule of gradually reducing the air introduction valve opening by 1-2% each time, and the average values of O2, CO, CO2 and H2 gas contents in the circulating gas within 1-2 h (after the air introduction valve opening is controlled) are measured respectively.

[0032] In the above scheme, the air introduction valve control scheme is set for more than 2 groups, preferably more than 3 groups.

[0033] In the above scheme, the optimization scheme with the lowest coke burn-off rate X is determined by regulating the dry quenching coke oven circulating gas (the rest is nitrogen) with the average values of the measured O2, CO, CO2 and H2 gas contents, according to the determined air introduction valve regulation scheme and the regulated dry quenching coke oven circulating gas, repeating steps 1) to 5), calculating the coke burn-off rate X corresponding to different optimization schemes, and selecting the optimization scheme with the lowest coke burn-off rate X.

[0034] In the above scheme, when the circulating gas composition CO>6%, H2>3%, the opening of the air introduction valve is gradually increased by 1-2% each time, and the circulating gas is regulated to the condition of CO≤6%, H2≤3%; then the regulation is carried out according to the determination method of the above optimization scheme and the determination method of the optimization scheme with the lowest coke burn-off rate X.

[0035] In the above scheme, the heating furnace used in step 2) includes a blower, a support, a sieve, a heating furnace, a gas outlet, a gas inlet, a temperature control thermocouple and a temperature control cabinet.

[0036] Compared with the prior art, the present application has the following advantages:

[0037] 1) The simulation method of the dry quenching coke oven burn-off rate used in the present application is beneficial to the analysis of the dry quenching coke oven burn-off rate under different working conditions at a lower cost, and can simulate the influence of the change of the circulating gas composition of the dry quenching coke oven on the burn-off rate, which is helpful to reasonably control the circulating gas composition of the dry quenching coke oven.

[0038] 2) The present application can quickly and directly reflect the implementation effect of the optimization control scheme of the dry quenching coke circulating gas, without the need for data statistics and theoretical calculation within a certain period (usually more than one week), which is beneficial to reducing the optimization debugging period and cost of the circulating gas composition of the dry quenching coke, and can efficiently and accurately reduce the dry quenching coke burn-off rate. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The figure is a structure schematic view of the simulation experiment device of the dry quenching coke oven burn-off rate used in the embodiments of the present application.

[0040] In the figure, 1 is a blower, 2 is a support, 3 is a sieve, 4 is coke, 5 is a heating furnace, 6 is a gas outlet, 7 is a gas inlet, 8 is a temperature control thermocouple, and 9 is a temperature control cabinet. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] In the following embodiments, the simulation and control method for reducing the burn-off rate of dry quenching coke ovens includes the following steps:

[0043] 1. According to the sampling method specified in GB / T 1997-2008 "Sampling and Preparation of Coke Samples", take 20 kg of coke with a diameter of ≥25 mm from the dry quenching coke oven according to the proportion. Use a jaw crusher to crush and mix the coke, remove the flaky coke and strip coke, and prepare coke blocks with a diameter of 15-20 mm. Divide the prepared coke into several portions (each portion not less than 600 g), put them in a drying oven to dry for later use, and obtain multiple sets of coke samples.

[0044] 2. For each experiment, take 450-550g of coke sample, and pile it evenly in the reactor with the middle higher and the two sides lower. Place it in the heating furnace for the experiment. Record the weight of the coke as m1.

[0045] 3. After testing the airtightness, turn on the power supply and, under the protection of N2, heat the furnace to 920-950℃. After maintaining the temperature for 5-10 minutes, turn on the blower and introduce the dry quenching coke oven circulating gas according to the air-material ratio set by the dry quenching coke oven.

[0046] 4. Gradually reduce the furnace temperature to below 150℃ according to the cooling rate in Table 1, stop heating, cut off the circulating gas, cool to room temperature, take out the coke and weigh it, and record it as m2;

[0047] Table 1 Cooling rate control method

[0048]

[0049] 5. Calculate the coke burn-off rate using the formula.

[0050] 6. The coke burn-off rate X is used to characterize the coke burn-off rate in the dry quenching coke oven. When the difference between the obtained coke burn-off rate X and the design value is ≤0.2%, the existing circulating gas composition remains unchanged. When the difference between the obtained coke burn-off rate X and the design value is >0.2%, under the premise that the air-fuel ratio remains unchanged, by appropriately adjusting the opening of the air guide valve, and ensuring that the content of combustible components in the circulating gas does not exceed the standard (CO≤6%, H2≤3%), an optimization scheme for the composition of the dry quenching coke circulating gas is set. The specific determination method includes:

[0051] Under the premise of ensuring that the combustible components CO ≤ 6% and H2 ≤ 3% in the circulating gas, several groups (preferably more than 3 groups) of air inlet valve control schemes are set up according to the rule of gradually reducing the opening of the air inlet valve by 1 to 2% each time. At the same time, the average values ​​of O2, CO, CO2 and H2 gas contents in the circulating gas within 1 to 2 hours are measured respectively.

[0052] 7. Based on the optimized composition scheme of the dry quenching circulating gas, conduct a simulation experiment according to the above experimental steps (steps 1 to 6) and determine the coke burn-off rate X of the corresponding optimized scheme.

[0053] 8. Select the scheme with the lowest coke burn-off rate X, and control and optimize the composition of the dry quenching circulating gas in production to reduce the dry quenching burn-off rate.

[0054] The structural schematic diagram of the heating furnace used in the following embodiments is shown in [reference needed]. Figure 1 It includes: a blower 1, an air inlet 7, a support 2, a sieve 3, a heating furnace 5, an air outlet 6, a temperature control coupler 8, and a temperature control cabinet 9; wherein, coke 4 is placed on the sieve 3 above the support 2, and the regulated circulating gas is introduced by the blower 1 and the air inlet 7, and finally discharged from the air outlet 6; the temperature in the heating furnace 5 is controllably adjusted by the temperature control coupler 8 and the temperature control cabinet 9.

[0055] Example 1

[0056] A simulation-based control method for reducing burn-off rate in dry quenching coke ovens is presented, targeting two 140t / h dry quenching systems in a coking company. Before control, the circulating gas composition included: H2 0.78%, O2 0.34%, CO 3.50%, CO2 14.99% (the remainder being nitrogen), and the circulating gas air-to-material ratio was 1430m³. 3 / t;

[0057] The specific implementation plan is as follows:

[0058] 1. According to the sampling method specified in GB / T 1997-2008 "Sampling and Preparation of Coke Samples", take 20 kg of coke with a diameter of ≥25 mm from the corresponding dry quenching coke oven, crush and mix it with a jaw crusher, remove the flaky coke and strip coke, and prepare coke blocks with a diameter of 15-20 mm.

[0059] 2. Divide the prepared coke sample into several portions, each not less than 600g, and dry them in a drying oven for later use.

[0060] 3. Weigh 500.3g of coke sample and stack it evenly in the reactor with the middle higher and the two sides lower. Place it in the heating furnace for the experiment. Record the weight of the coke as m1.

[0061] 4. After checking the airtightness, connect the power supply. Under N2 protection, slowly raise the furnace to 920℃, maintain the temperature for 5 minutes, then turn on the blower at 1430m. 3 / t of air-fuel ratio was introduced into the dry quenching coke oven circulating gas before the experiment (H2 is 0.78%, O2 is 0.34%, CO is 3.50%, CO2 is 14.99%).

[0062] 5. Gradually reduce the furnace temperature to 150℃ according to the cooling rate in Table 1, stop heating, cut off the circulating gas, cool to room temperature, take out the coke and weigh it to be 489.94g, and record it as m2;

[0063] 6. Calculate the coke burn-off rate under the above parameters using the formula. This differs significantly from the design value of 0.9% for dry quenching coke ovens (>0.2%).

[0064] 7. Under the premise of keeping the air-fuel ratio unchanged, and ensuring that the combustible components CO in the circulating gas are ≤6% and H2 ≤3%, reduce the opening of the air inlet valve (actual dry quenching system) by 1-2% each time, set up three optimization schemes, lower the CO2 content in the circulating gas and raise the CO content, and at the same time measure the average value of O2, CO, CO2 and H2 gas content in the circulating atmosphere of the dry quenching coke oven within 2 hours. The specific optimization control scheme is shown in Table 2.

[0065] 8. Based on the set optimization scheme for the dry quenching coke circulating gas composition, conduct simulation experiments according to the experimental steps described in 1 to 6 above, and determine the coke burn-off rate X of the corresponding scheme. The specific experimental results are shown in Table 2.

[0066] Table 2 Optimization scheme for circulating gas composition and coke burn-off rate

[0067]

[0068] 9. Based on the experimental results in Table 2, optimization scheme three was selected to control and optimize the composition of the circulating gas in actual production of dry quenching coke, thereby reducing the dry quenching coke burn-off rate. The results after implementation are shown in Table 3.

[0069] Table 3 Implementation Results

[0070]

[0071]

[0072] As can be seen from the implementation results in Table 3, after adopting the implementation scheme of the present invention, under the premise of stable coke quality, the monthly coke output increased by 1633t, the coking rate increased by 0.22%, effectively improving production efficiency and reducing production costs.

[0073] Example 2

[0074] A simulation control method for reducing the burn-off rate of a dry quenching coke oven is presented. This method is applied to a 140t / h dry quenching coke oven system at a coking company. Before control, the circulating gas composition included: H2 0.75%, O2 0.49%, CO 3.65%, CO2 13.57% (the remainder being nitrogen); the circulating gas air-to-material ratio was 1350 m³ / h. 3 / t;

[0075] The specific implementation plan is as follows:

[0076] 1. According to the sampling method specified in GB / T 1997-2008 "Sampling and Preparation of Coke Samples", take 20 kg of coke with a diameter of ≥25 mm from the corresponding dry quenching coke oven, crush and mix it with a jaw crusher, remove the flaky coke and strip coke, and prepare coke blocks with a diameter of 15-20 mm.

[0077] 2. Divide the prepared coke sample into several portions, each not less than 600g, and dry them in a drying oven for later use.

[0078] 3. In the experiment, 500.2g of coke sample was weighed and evenly piled in the reactor with the middle higher and the two sides lower. The sample was then placed in a heating furnace for the experiment. The weight of the coke was recorded as m1.

[0079] 4. After testing for airtightness, connect the power supply. Under N2 protection, slowly raise the furnace to 920℃, maintain the temperature for 5 minutes, then turn on the blower at 1350m. 3 / t of air-fuel ratio was introduced into the dry quenching coke oven circulating gas before the experiment (H2 is 0.75%, O2 is 0.49%, CO is 3.65%, CO2 is 13.57%).

[0080] 5. Gradually reduce the furnace temperature to 150℃ according to the cooling rate in Table 1, stop heating, cut off the circulating gas, cool to room temperature, take out the coke and weigh it as 492.25g, and record it as m2;

[0081] 6. Calculate the coke burn-off rate under the above parameters using the formula. There is a certain discrepancy (>0.2%) between this and the design value of 0.9% for dry quenching coke ovens;

[0082] 7. Under the premise of keeping the air-material ratio unchanged, and ensuring that the combustible components CO in the circulating gas are ≤6% and H2 ≤3%, the opening of the air inlet valve is gradually reduced by 1% each time, so that the CO2 content in the circulating gas is lowered and the CO content is raised. The specific optimization control scheme is shown in Table 4.

[0083] 8. Based on the set optimization scheme for the dry quenching circulating gas composition, conduct a simulation experiment according to the above experimental steps, and determine the coke burn-off rate X of the corresponding scheme. The experimental results are shown in Table 4.

[0084] Table 4 Optimization scheme for circulating gas composition and coke burn-off rate

[0085]

[0086]

[0087] 9. Based on the experimental results in Table 4, optimization scheme 2 was selected to control and optimize the composition of the dry quenching circulating gas in actual production, thereby reducing the dry quenching burn-off rate. The results after implementation are shown in Table 5.

[0088] Table 5 Implementation Results

[0089] Indicator Before implementation After implementation Improvement effect Coke production / t / month 87108 87390 282 Coking rate / % 75.64 75.74 0.1 M 40 / %]]> 88.85 88.86 0.01 M 10 / %]]> 5.92 5.95 0.03 CRI / % 20.52 20.73 0.21 CSR / % 69.43 69.04 -0.39

[0090] As can be seen from the implementation results in Table 5, after adopting the implementation scheme of the present invention, under the premise of stable coke quality, the monthly coke output increased by 282t, the coking rate increased by 0.1%, effectively improving production efficiency and reducing production costs.

[0091] Example 3

[0092] A simulation-based control method for reducing the burn-off rate of a dry quenching coke oven is presented. This method is applied to a 190t / h dry quenching system at a coking company. Before control, the circulating gas composition included: H2 1.70%, O2 0.69%, CO 5.70%, and CO2 10.01%; the circulating gas air-to-material ratio was 1490m³. 3 / t;

[0093] The specific implementation plan is as follows:

[0094] 1. According to the sampling method specified in GB / T 1997-2008 "Sampling and Preparation of Coke Samples", take 20 kg of coke with a diameter of ≥25 mm from the corresponding dry quenching coke oven, crush and mix it with a jaw crusher, remove the flaky coke and strip coke, and prepare coke blocks with a diameter of 15-20 mm.

[0095] 2. Divide the prepared coke sample into several portions, each not less than 600g, and dry them in a drying oven for later use.

[0096] 3. In the experiment, 500.4g of coke sample was weighed and evenly piled in the reactor in a manner with a higher center and lower sides. The sample was then placed in a heating furnace for the experiment. The weight of the coke was recorded as m1.

[0097] 4. After testing for airtightness, connect the power supply and, under N2 protection, slowly raise the furnace to 920℃. After maintaining this temperature for 5 minutes, turn on the blower and operate at 1490m... 3 / t of air-fuel ratio was introduced into the dry quenching coke oven circulating gas before the experiment (H2 is 1.70%, O2 is 0.69%, CO is 5.70%, CO2 is 10.01%).

[0098] 5. Gradually reduce the furnace temperature to 150℃ according to the cooling rate in Table 1, stop heating, cut off the circulating gas, cool to room temperature, take out the coke and weigh it to be 495.39g, and record it as m2;

[0099] The coke burn-off rate under the above parameters was calculated using the formula. The value is slightly higher than the design value of 0.9% for dry quenching coke ovens (difference ≤ 0.2%), therefore it is considered that the circulating gas composition control of the existing dry quenching coke ovens is appropriate and no adjustment is required.

[0100] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A simulation control method for reducing the burn-off rate of dry quenching coke ovens, characterized in that, Includes the following steps: 1) Take coke with a diameter of ≥25mm from the dry quenching coke oven, crush and mix it, remove the flaky coke and strip coke, and prepare coke blocks with a particle size of 15~20mm; reduce the size of the coke blocks, dry them for later use, and obtain several groups of coke samples. 2) The coke sample was piled in the reactor and then placed in the heating furnace. The mass of the coke sample was recorded as m1. 3) After testing the airtightness, turn on the power supply and heat the furnace to 920~950℃ under a protective atmosphere. After the temperature stabilizes for a period of time, turn on the blower and introduce the dry quenching coke oven circulating gas according to the air-material ratio set by the dry quenching coke oven. 4) Perform a programmed cooling process, reduce the furnace temperature to below 150℃, stop heating, cut off the circulating gas, cool to room temperature, remove the coke after reaction, weigh its mass, and record it as m2; 5) Calculate the coke burn-off rate X, where X = ; 6) The obtained coke burn-off rate X represents the burn-off rate of coke in the dry quenching coke oven, and is compared with the design value of the burn-off rate: When the difference between the burn-off rate and the design value is ≤0.2%, the existing circulating gas composition remains unchanged; When the difference between the burn-off rate and the design value is greater than 0.2%, under the premise that the air-material ratio remains unchanged, by adjusting the opening of the air guide valve, and on the premise that the combustible components CO ≤ 6% and H2 ≤ 3% in the circulating gas, more than two sets of optimization schemes for the composition of the dry quenching circulating gas are set. The method for determining the optimization scheme includes: under the premise of ensuring that the combustible components CO ≤ 6% and H2 ≤ 3% in the circulating gas, setting up several sets of air inlet valve control schemes by gradually reducing the opening of the air inlet valve by 1~2% each time, and at the same time measuring the average values ​​of O2, CO, CO2 and H2 gas contents in the circulating gas within 1~2 hours respectively. 7) Based on the set optimization scheme for the dry quenching circulating gas composition, repeat steps 1) to 6) and determine the coke burn-off rate X corresponding to different optimization schemes; 8) Select the optimization scheme with the lowest coke burn-off rate X, and control and optimize the composition of the dry quenching circulating gas in production to reduce the dry quenching burn-off rate; the method for determining the optimization scheme with the lowest X includes: adjusting the circulating gas according to the average values ​​of the measured O2, CO, CO2 and H2 gas contents, and repeating steps 1) to 6) based on the determined air inlet valve adjustment scheme and the adjusted circulating gas, calculating the coke burn-off rate X corresponding to different optimization schemes, and selecting the optimization scheme with the lowest coke burn-off rate X.

2. The control method according to claim 1, characterized in that, The main gases in the circulating gas of the dry quenching coke oven include O2, CO, CO2 and H2.

3. The control method according to claim 1, characterized in that, The heating rate mentioned in step 3) is 7~15℃ / min; The temperature stabilization time is 5~10 minutes.

4. The control method according to claim 1, characterized in that, The cooling times corresponding to different temperature ranges in the programmed cooling steps are as follows: ≥920℃ 10~15min, 920~800℃ 15~20min, 800~700℃ 18~22min, 700~600℃ 18~22min, 600~500℃ 18~22min, 500~400℃ 18~22min, 400~300℃ 23~27min, 300~150℃ 18~25min.

5. The control method according to claim 1, characterized in that, The air-to-material ratio used in step 3) is 1300~1500m. 3 / t; The opening degree of the air pilot valve mentioned in step 6) is 0~100%.

6. The control method according to claim 1, characterized in that, The designed burn-off rate is 0.9~1.0%.

7. The control method according to claim 1, characterized in that, Step 2) The heating furnace used includes a blower, support frame, sieve plate, heating furnace, air outlet, air inlet, temperature control thermocouple and temperature control cabinet.

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