Decomposition furnace outlet temperature compensation control method and system during alternative fuel change

Abstract

The invention relates to a decomposing furnace outlet temperature compensation control method and system during alternative fuel change, and the control method comprises the steps: carrying out the real-time adjustment of the coal feeding amount according to the main adjustment amount of the coal fuel, and calculating the main adjustment amount of the coal fuel according to the deviation between the actual value and the target value of the decomposing furnace temperature; additional coal feeding amount adjustment is carried out in the auxiliary coal fuel adjustment time according to the auxiliary coal fuel adjustment amount, and the auxiliary coal fuel adjustment amount is the adjustment amount of the coal fuel needed for compensating the variable amount of heat generated by combustion of the alternative fuel due to the change of the alternative fuel; and the auxiliary adjustment time of the coal fuel is calculated according to the time from the change of the alternative fuel and the coal feeding of the decomposing furnace to the change of the temperature of the decomposing furnace. The control system adopts the control method to control the coal feeding amount and the coal feeding time of the coal feeding system of the decomposing furnace. When alternative fuel changes, the coal feeding amount can be compensated and adjusted in advance to the maximum extent, fluctuation of the outlet temperature of the decomposing furnace is effectively reduced or even eliminated, and the influence on downstream working conditions is reduced.

Description

Technical Field

[0001] The invention relates to a decomposition furnace outlet temperature compensation control method and system when alternative fuels change, belonging to the technical field of industrial automatic control. Background Art

[0002] In the context of carbon reduction, industrial production enterprises have been committed to reducing the use of coal fuel. With the gradual increase in energy costs, making full use of various alternative fuels to replace part of the coal fuel has become a new technology, especially in cement production enterprises. During cement production, the stability of the outlet temperature of the decomposition furnace is an important guarantee for the decomposition of limestone in the raw material. The outlet temperature of the decomposition furnace is guaranteed by the heat released by the combustion of coal fuel (coal powder). After using alternative fuels (such as garbage), the alternative fuel can provide part of the heat, thereby reducing the use of coal fuel. However, the supply of alternative fuels is generally not stable, and its calorific value and moisture content are also unstable. Therefore, the heat provided is also unstable, which often causes the outlet temperature of the decomposition furnace to fluctuate greatly, affecting the cement production process. This requires that when the outlet temperature of the decomposition furnace fluctuates, the coal feeding amount needs to be adjusted to minimize the fluctuation of the outlet temperature of the decomposition furnace. The traditional control method for adjusting the coal feeding amount is: when the amount of alternative fuel added (feeding amount), the moisture content or calorific value changes, the coal feeding amount of the decomposition furnace is adjusted according to the change of the outlet temperature of the decomposition furnace, that is, assuming that the raw meal feeding amount does not change, and the change of the alternative fuel is not considered, the coal feeding amount is calculated and adjusted only according to the deviation between the actual value of the decomposition furnace temperature and the target value of the decomposition furnace temperature, and the change of the raw meal feeding amount and the change of the alternative fuel are treated as interference. The controller used in this control method is relatively simple and the requirements for the site are not high, which is suitable for promotion and application. However, this control method is relatively delayed in time, the adjustment is not timely and the adjustment time is long, the outlet temperature of the decomposition furnace will fluctuate greatly, which will also affect the working condition of the rotary kiln and the quality of the clinker. Summary of the invention

[0003] In order to overcome the above-mentioned defects of the prior art, the present invention provides a decomposition furnace outlet temperature compensation control method and system when the alternative fuel changes, which can adjust the coal feeding amount in advance to the maximum extent when the alternative fuel changes, thereby reducing the fluctuation of the decomposition furnace outlet temperature.

[0004] The technical solution for the present invention to achieve the above object is: a decomposition furnace outlet temperature compensation control method when the alternative fuel changes, which adjusts the coal feeding amount in real time according to the main adjustment amount of the coal fuel. The main adjustment amount of the coal fuel is calculated based on the deviation between the actual value and the target value of the decomposition furnace temperature. Additionally, the coal fuel feeding amount is adjusted according to the secondary adjustment amount of the coal fuel during the secondary adjustment time of the coal fuel. The secondary adjustment amount of the coal fuel is the adjustment amount of the coal fuel required to compensate for the change in the heat generated by the combustion of the alternative fuel caused by the change in the alternative fuel. The secondary adjustment time of the coal fuel is calculated based on the time required for the decomposition furnace temperature to change after the alternative fuel changes and the time required for the decomposition furnace temperature to change after the coal fuel feeding amount in the decomposition furnace changes.

[0005] Preferably, the change in the alternative fuel includes changes in the feeding amount, water content, and / or calorific value of the alternative fuel.

[0006] Preferably, the calculation method of the secondary adjustment amount of the coal fuel is as follows:

[0007] ΔC = ((ΔW3 × Δq3) - ΔH3 × ΔW3 × q4) / q2

[0008] Where, ΔC is the secondary adjustment amount of the coal fuel, with the unit of t / h; ΔW3 is the change amount of the alternative fuel feeding amount, with the unit of t / h; Δq3 is the change amount of the calorific value of the alternative fuel, with the unit of j / kg; ΔH3 is the change amount of the water content ratio in the alternative fuel, with the unit of %; q4 is the sensible heat and latent heat of the water in the alternative fuel, with the unit of j / kg; q2 is the calorific value of the coal fuel, with the unit of j / kg.

[0009] Preferably, the calculation method of the secondary adjustment time of the coal fuel is as follows:

[0010] (1) When T2 < T1, immediately adjust the coal feeding (perform additional coal feeding amount adjustment);

[0011] (2) When T2 > T1, delay the coal feeding adjustment by T2 - T1 time (perform additional coal feeding amount adjustment);

[0012] Where, T1 is the time required for the decomposition furnace temperature to change after the coal fuel feeding amount in the decomposition furnace changes; T2 is the time required for the decomposition furnace temperature to change after the alternative fuel changes.

[0013] Preferably, the calculation method of T1 is: keep the raw material feeding amount and alternative fuel feeding amount in the decomposition furnace unchanged, increase the coal feeding amount and record the moment T when the coal feeding amount is increased 10 , observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the rising temperature, record the moment T when the temperature of the decomposition furnace starts to maintain the rising temperature after rising 11 , T1 = T 11 - T 10; T2 is calculated as follows: keep the raw material feed and coal feed of the calciner unchanged, increase the feed of the alternative fuel and record the time T when the feed of the alternative fuel is increased 20 Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the temperature after the rise, record the time T when the temperature of the decomposition furnace rises and starts to maintain the temperature after the rise. 21 , T2=T 21 -T 20 .

[0014] Furthermore, T1 and T2 are calculated multiple times (for example, 3-4 times each), and the average values ​​are taken as the time required for the change of coal feeding to the decomposition furnace to the change of the decomposition furnace temperature and the time required for the change of the alternative fuel to the change of the decomposition furnace temperature.

[0015] The decomposition furnace outlet temperature compensation control system includes:

[0016] An input module, used to input information on the change in the amount of alternative fuel feed, the change in the calorific value of the alternative fuel, the change in the moisture content of the alternative fuel, and the sensible heat and latent heat of the moisture content of the alternative fuel;

[0017] An analysis module, for calculating the coal fuel auxiliary adjustment amount and the coal fuel auxiliary adjustment time based on the information input by the input module by using any of the alternative fuel change-related decomposition furnace outlet temperature compensation control methods disclosed in the present invention;

[0018] The output module is used to output the calculation results of the analysis module to the coal feeding system.

[0019] Preferably, the decomposition furnace outlet temperature compensation control system further comprises a temperature controller, and the temperature controller is used to calculate the main adjustment amount of coal fuel according to the deviation between the actual value and the target value of the decomposition furnace temperature.

[0020] The beneficial effects of the present invention are as follows: the present invention can compensate and adjust the coal feeding amount in advance (feedforward control) to the maximum extent when the alternative fuel changes, and the adjustment amount conforms to the thermodynamic equilibrium mechanism, effectively reducing or even eliminating the fluctuation of the outlet temperature of the decomposition furnace, reducing the impact on the downstream working conditions, and ensuring the stability of the clinker quality; since the alternative fuel usually contains a relatively high amount of water and the change in the water content is relatively large when the alternative fuel changes, the change in the amount of heat consumed by the water in the combustion process due to the change in the water content of the alternative fuel is fully considered, and it is used as an important factor in calculating the additional coal feeding amount when the alternative fuel changes, which can effectively reduce or even eliminate the temperature fluctuation of the decomposition furnace. In addition to the influence of the change of moisture content on the outlet temperature of the decomposition furnace when the alternative fuel changes, the accuracy of the compensation control of the outlet temperature of the decomposition furnace is improved, and the stability of the outlet temperature of the decomposition furnace is ensured; the coal fuel auxiliary adjustment time is calculated by the time required for the change of the alternative fuel to the change of the decomposition furnace temperature and the time required for the change of the decomposition furnace coal feeding to the change of the decomposition furnace temperature, so that when the alternative fuel changes, the adjustment time of the additional coal feeding amount is more accurate, avoiding the large fluctuation of the outlet temperature of the decomposition furnace caused by the change of coal feeding amount due to the different time required for different fuels (referring to coal fuel and alternative fuel) to change the decomposition furnace temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the control method of the present invention. DETAILED DESCRIPTION

[0022] See also Figure 1 The present invention discloses a method for compensating the outlet temperature of a decomposition furnace when the alternative fuel changes. The method comprises: adjusting the coal feeding amount in real time according to the main adjustment amount of the coal fuel, which is calculated according to the deviation between the actual value of the decomposition furnace temperature and the target value, and adjusting the additional coal feeding amount at the coal fuel secondary adjustment time according to the secondary adjustment amount of the coal fuel. The secondary adjustment amount of the coal fuel is calculated in such a way that when the alternative fuel (the alternative fuel of the coal fuel, such as garbage) changes, the change in the heat generated by the combustion of the alternative fuel due to the change in the alternative fuel is calculated, and the coal feeding adjustment amount required to compensate for the change in the heat is calculated according to the change in the heat, as the secondary adjustment amount of the coal fuel. The secondary adjustment time of the coal fuel is calculated according to the time required from the change in the alternative fuel to the change in the decomposition furnace temperature and the time required from the change in the coal feeding of the decomposition furnace to the change in the decomposition furnace temperature.

[0023] Changes in alternative fuels typically include changes in the feed rate of the alternative fuel (adjusting the size of the alternative fuel feed rate), the moisture content (e.g. replacing different batches of the same alternative fuel) and / or the calorific value (e.g. replacing different batches of the same alternative fuel).

[0024] When the decomposition furnace uses both coal fuel and alternative fuel as fuel, the total heat required for the decomposition furnace to decompose the raw meal is provided by the total calorific value of the coal fuel combustion and the total calorific value of the alternative fuel combustion. The total calorific value of the coal fuel combustion depends on the coal feed amount and its corresponding calorific value, and the total calorific value of the alternative fuel combustion depends on the total feed amount of the alternative fuel and its calorific value. The moisture contained in the alternative fuel consumes heat during the combustion process, and its content has a negative effect on the total heat. That is to say, the higher the moisture content of the alternative fuel, the higher the heat consumed by the moisture, and the smaller the heat used to decompose the raw meal, that is,

[0025] C=C2+C3 (1)

[0026] C2=q2×W2 (2)

[0027] C3=q3×W3-H3×C4 (3)

[0028] Among them, C is the total heat required for decomposing raw materials per hour, in kj / h; C2 is the heat generated by the combustion of coal fuel per hour, in kj / h; C3 is the heat generated by the combustion of alternative fuel per hour, in kj / h; q2 is the calorific value of coal fuel, in j / kg; W2 is the current feed rate of coal fuel, in t / h; q3 is the calorific value of alternative fuel, in j / kg; W3 is the feed rate of alternative fuel, in t / h; H3 is the proportion of moisture contained in the alternative fuel, in %; C4 is the heat consumed by heating each kg of water from room temperature to 880℃ per hour, in kj / h.

[0029] When the alternative fuel changes, the total calorific value of the alternative fuel combustion will change. In order to ensure that the total heat required for decomposing raw materials remains unchanged, the total calorific value of the coal fuel combustion needs to be adjusted accordingly. Since the calorific value of the coal fuel is usually unchanged, it is preferred to adjust the total calorific value of the coal fuel combustion by adjusting the feed amount of the coal fuel (the coal fuel auxiliary adjustment amount). The calculation method is as follows:

[0030] ΔF=ΔQ6 / q2 (4)

[0031] ΔQ6=ΔQ4-ΔQ5 (5)

[0032] ΔQ4=ΔW3×Δq3 (6)

[0033] ΔQ5=ΔH3×ΔW3×q4(7)

[0034] Substituting formula (5), formula (6) and formula (7) into formula (4), we get:

[0035] ΔF=((ΔW3×Δq3)-ΔH3×ΔW3×q4) / q2 (8)

[0036] Among them, ΔF is the secondary adjustment amount of coal fuel, with the unit of t / h; ΔQ6 is the change amount of the total calorific value of the alternative fuel combustion (or the comprehensive heat change amount of the alternative fuel combustion) when the alternative fuel changes per hour, with the unit of kj / h; ΔQ4 is the change amount of the heat that can be generated by complete combustion before and after the alternative fuel changes per hour, with the unit of kj / h; ΔQ5 is the change amount of the heat loss caused by the change in the water content in the alternative fuel when the alternative fuel changes per hour, with the unit of kj / h; ΔW3 is the change amount of the alternative fuel feeding amount, with the unit of t / h; Δq3 is the change amount of the calorific value of the alternative fuel, with the unit of j / kg; ΔH3 is the change amount of the water content ratio in the alternative fuel, with the unit of %; q4 is the sensible heat and latent heat of the water in the alternative fuel, with the unit of j / kg; q2 is the calorific value of the coal fuel, with the unit of j / kg.

[0037] Since the time required for the alternative fuel to change until the decomposition furnace temperature changes is usually different from the time required for the coal feeding in the decomposition furnace to change until the decomposition furnace temperature changes, in order to ensure that the outlet temperature of the decomposition furnace is basically stable and does not fluctuate greatly when the alternative fuel changes, it is necessary to calculate the adjustment time (the secondary adjustment time of the coal fuel) of the coal fuel (the additional coal feeding amount) for the change amount of the compensated heat (the change amount of the heat generated by the alternative fuel combustion caused by the change in the alternative fuel), so that the influence of adjusting the coal feeding amount on the outlet temperature of the decomposition furnace is basically the same as that assuming the alternative fuel does not change (using the original alternative fuel and keeping the feeding amount unchanged).

[0038] The calculation method of the secondary adjustment time of the coal fuel is preferably:

[0039] (1) When T2 < T1, immediately adjust the coal feeding (perform additional coal feeding amount adjustment);

[0040] (2) When T2 > T1, delay the coal feeding adjustment by T2 - T1 time (perform additional coal feeding amount adjustment);

[0041] Among them, T1 is the time required for the coal feeding in the decomposition furnace to change until the decomposition furnace temperature changes; T2 is the time required for the alternative fuel to change until the decomposition furnace temperature changes.

[0042] The specific calculation method of T1 is: Keep the raw material feeding amount and the alternative fuel feeding amount in the decomposition furnace unchanged, increase the coal feeding amount and record the moment T when the coal feeding amount is increased 10 , observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the rising temperature, record the moment T when the temperature of the decomposition furnace starts to maintain the rising temperature after rising 11 , T1 = T 11 -T 10The specific calculation method of T2 is: keep the raw material feeding amount and coal feeding amount of the calciner unchanged, increase the feeding amount of the alternative fuel and record the time T when the feeding amount of the alternative fuel is increased 20 Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the temperature after the rise, record the time T when the temperature of the decomposition furnace rises and starts to maintain the temperature after the rise. 21 , T2=T 21 -T 20 .

[0043] In order to make the calculation results of T1 and T2 more accurate (more in line with actual production conditions), T1 and T2 can be calculated multiple times (for example, 3-4 times each), and the average value can be taken as the time required for the change in the coal feed to the decomposition furnace to change the decomposition furnace temperature and the time required for the change in the alternative fuel to change the decomposition furnace temperature.

[0044] The present invention also discloses a decomposition furnace outlet temperature compensation control system, comprising:

[0045] An input module, used to input information on the change in the amount of alternative fuel feed, the change in the calorific value of the alternative fuel, the change in the moisture content of the alternative fuel, and the sensible heat and latent heat of the moisture content of the alternative fuel;

[0046] An analysis module, for calculating the coal fuel auxiliary adjustment amount and the coal fuel auxiliary adjustment time based on the information input by the input module by using any of the alternative fuel change-related decomposition furnace outlet temperature compensation control methods disclosed in the present invention;

[0047] The output module is used to output the calculation results of the analysis module to the coal feeding system (the coal feeding system of the decomposition furnace).

[0048] The decomposition furnace outlet temperature compensation control system preferably further includes a temperature controller, which is used to calculate the main adjustment amount of coal fuel according to the deviation between the actual value and the target value of the decomposition furnace temperature and output it to the coal feeding system. The coal feeding system of the decomposition furnace adjusts the coal feeding of the decomposition furnace according to the main adjustment amount of coal fuel, the auxiliary adjustment amount of coal fuel and the auxiliary adjustment time of coal fuel.

[0049] The actual value of the decomposition furnace temperature and the information required to be input by the input module can be collected using appropriate sensors according to the prior art.

[0050] Unless otherwise specified or one preferred or optional technical means is a further limitation of another technical means, all preferred and optional technical means disclosed in the present invention can be arbitrarily combined to form several different technical solutions.

Claims

1. A compensation control method for the outlet temperature of the decomposition furnace when the alternative fuel changes, which adjusts the coal feeding amount in real time according to the main adjustment amount of the coal fuel, wherein the main adjustment amount of the coal fuel is calculated according to the deviation between the actual value and the target value of the decomposition furnace temperature, Features The additional coal feeding amount is also adjusted during the coal fuel sub-adjustment time based on the coal fuel sub-adjustment amount. The coal fuel sub-adjustment amount is the adjustment amount of coal fuel required to compensate for the change in heat generated by the combustion of the alternative fuel caused by the change in the alternative fuel. The coal fuel sub-adjustment time is calculated based on the time required for the change in the alternative fuel to the change in the decomposition furnace temperature and the time required for the change in the decomposition furnace coal feeding to the change in the decomposition furnace temperature.

2. The method for compensating and controlling the outlet temperature of the decomposition furnace when the alternative fuel changes according to claim 1, Features The calculation method of the coal fuel auxiliary adjustment amount is: ΔC(ΔW 3 ×Δq 3 )-ΔH 3 ×ΔW 3 ×q 4 ) / q 2 Among them, ΔC is the auxiliary adjustment of coal fuel, the unit is t / h; ΔW 3 is the change in the amount of alternative fuel feed, in t / h; Δq 3 is the change in calorific value of the alternative fuel, in j / kg; ΔH 3 is the change in the water content of the alternative fuel, in %; q 4 is the sensible heat and latent heat of water in the alternative fuel, in J / kg; q 2 It is the calorific value of coal fuel, in j / kg.

3. The method for compensating and controlling the outlet temperature of the decomposition furnace when the alternative fuel changes according to claim 1, Features The calculation method of the coal fuel auxiliary adjustment time is: (1) When T 2 <T 1 When the coal is fed, adjust the coal feeding immediately; (2) When T 2 >T 1 When the delay T 2 -T 1 Time adjustment for feeding coal; Among them, T 1 The time required from the change of coal feeding to the change of temperature in the decomposition furnace; T 2 The time required for the change of alternative fuel to the change of decomposition furnace temperature.

4. The method for compensating and controlling the outlet temperature of the decomposition furnace when the alternative fuel changes according to claim 3, Features T 1 The calculation method is as follows: keep the raw material feed amount and alternative fuel feed amount of the calciner unchanged, increase the coal feed amount and record the time T when the coal feed amount is increased 10 Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the temperature after the rise, record the time T when the temperature of the decomposition furnace rises and starts to maintain the temperature after the rise. 11 , T 1 =T 11 -T 10 ; T 2 The calculation method is: keep the raw material feed rate and coal feed rate of the calciner unchanged, increase the feed rate of the alternative fuel and record the time T when the feed rate of the alternative fuel is increased 20 Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the temperature after the rise, record the time T when the temperature of the decomposition furnace rises and starts to maintain the temperature after the rise. 21 , T 2 =T 21 -T 20 .

5. The method for compensating and controlling the outlet temperature of the decomposition furnace when the alternative fuel changes as claimed in claim 4, Features Calculate T multiple times 1 and T 2 , take the average value as the time required for the decomposition furnace temperature to change when the coal feeding to the decomposition furnace changes and the time required for the decomposition furnace temperature to change when the alternative fuel changes.

6. Decomposition furnace outlet temperature compensation control system, Features include: An input module, used to input information on the change in the amount of alternative fuel feed, the change in the calorific value of the alternative fuel, the change in the moisture content of the alternative fuel, and the sensible heat and latent heat of the moisture content of the alternative fuel; An analysis module, for calculating the coal fuel sub-adjustment amount and the coal fuel sub-adjustment time based on the information input by the input module and using the decomposition furnace outlet temperature compensation control method when the alternative fuel changes according to any one of claims 1 to 5; The output module is used to output the calculation results of the analysis module to the coal feeding system.

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