Decomposition furnace outlet temperature compensation control method and system when alternative fuel changes

Abstract

The present application relates to a method and system for compensating the outlet temperature of a decomposition furnace when the substitute fuel changes, the control method is to adjust 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 according to the deviation between the actual value and the target value of the decomposition furnace temperature, and the additional coal feeding amount is adjusted at the auxiliary adjustment time of the coal fuel according to the auxiliary adjustment amount of the coal fuel, the auxiliary adjustment amount of the coal fuel is the adjustment amount of the coal fuel required to compensate the change of the heat generated by the combustion of the substitute fuel due to the change of the substitute fuel, and the auxiliary adjustment time of the coal fuel is calculated according to the time required from the change of the substitute fuel and the coal feeding of the decomposition furnace to the change of the decomposition furnace temperature. The control system controls the coal feeding amount and the coal feeding time of the coal feeding system of the decomposition furnace by using the control method. The present application can compensate and adjust the coal feeding amount in advance to the maximum extent when the substitute fuel changes, effectively reduce or even eliminate the fluctuation of the outlet temperature of the decomposition furnace, and reduce the influence on the downstream working condition.

Description

Technical Field

[0001] This invention relates to a method and system for compensating and controlling the outlet temperature of a decomposition furnace when alternative fuels change, and belongs to the field of industrial automatic control technology. Background Technology

[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 widely used in cement production enterprises. In cement production, a stable outlet temperature of the decomposition furnace is an important guarantee for the decomposition of limestone in the raw materials. The outlet temperature of the decomposition furnace is maintained by the heat released by the combustion of coal fuel (pulverized coal). After using alternative fuels (such as waste), the alternative fuels can provide some heat, thereby reducing the amount of coal fuel used. However, the supply of alternative fuels is generally not very stable, and their calorific value and moisture content are also unstable. Therefore, the heat provided is also unstable, often causing large fluctuations in the outlet temperature of the decomposition furnace, which affects the cement production process. This requires that when the outlet temperature of the decomposition furnace fluctuates, the coal feed rate needs to be adjusted to minimize the fluctuations in the outlet temperature of the decomposition furnace. The traditional method for controlling coal feed rate adjustment is as follows: when the amount of alternative fuel added (feed rate), its moisture content, or calorific value changes, the coal feed rate of the decomposer is adjusted according to the change in the decomposer outlet temperature. That is, it assumes that the raw meal feed rate does not change and does not consider changes in alternative fuel. It only calculates and adjusts the coal feed rate based on the deviation between the actual value and the target value of the decomposer temperature, treating changes in both raw meal feed rate and alternative fuel as disturbances. This control method uses a relatively simple controller and has low requirements for the site, making it suitable for widespread application. However, this control method is relatively slow in terms of time, with untimely and long adjustment times. The outlet temperature of the decomposer will fluctuate significantly, which will also affect the operating conditions of the rotary kiln and the quality of clinker. Summary of the Invention

[0003] To overcome the above-mentioned defects of the prior art, the present invention provides a method and system for compensating and controlling the outlet temperature of the decomposer when the alternative fuel changes. This method can adjust the coal feed rate in advance to the maximum extent when the alternative fuel changes, thereby reducing the fluctuation of the outlet temperature of the decomposer.

[0004] The technical solution of this invention to achieve the above objective is: a method for compensating for the temperature at the outlet of the decomposer when the alternative fuel changes. This method involves real-time adjustment of the coal feed rate based on the main adjustment amount of the coal fuel. The main adjustment amount is calculated based on the deviation between the actual and target values ​​of the decomposer temperature. Additionally, the method adjusts the coal feed rate based on the secondary adjustment amount of the coal fuel during the secondary adjustment time. The secondary adjustment amount of the coal fuel is the amount of coal fuel adjustment required to compensate for the change in heat generated by the combustion of the alternative fuel due to the change in the alternative fuel. The secondary adjustment time of the coal fuel is calculated based on the time required for the temperature of the decomposer to change from the change in the alternative fuel to the change in the temperature of the decomposer, and the time required for the temperature of the decomposer to change from the change in the coal feed rate.

[0005] Preferably, the changes in alternative fuels include changes in the amount of alternative fuel fed, its moisture content, and / or its calorific value.

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

[0007]

[0008] in, This refers to the coal fuel by-product adjustment quantity, expressed in t / h. The change in the amount of alternative fuel feed is expressed in t / h. The change in calorific value of the alternative fuel is expressed in J / kg. The change in the moisture content of alternative fuels is expressed in % (%). The sensible and latent heat of water in alternative fuels are expressed in J / kg. This represents the calorific value of coal fuel, expressed in J / kg.

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

[0010] when Immediately adjust the coal feed (make additional coal feed adjustments).

[0011] when When, delay Time-adjusted coal feeding (adjusting the additional coal feeding amount);

[0012] in, The time required for a change in the coal feed to the decomposer to lead to a change in the decomposer temperature; The time required for a change in fuel type to occur, leading to a change in the temperature of the decomposition furnace.

[0013] Preferred, The calculation method is as follows: keeping the raw material feed rate and alternative fuel feed rate of the decomposer constant, increase the coal feed rate and record the time of the increase. Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the increased temperature, record the moment when the temperature of the decomposition furnace begins to rise and maintain the increased temperature. , ; The calculation method is as follows: keeping the raw material feed rate and coal feed rate of the decomposition furnace constant, increase the feed rate of alternative fuel and record the time when the feed rate of alternative fuel is increased. Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the increased temperature, record the moment when the temperature of the decomposition furnace begins to rise and maintain the increased temperature. , .

[0014] Furthermore, calculate multiple times separately. and (For example, calculate 3-4 times for each), and take the average value as the time required for the temperature of the decomposer to change from a change in the coal feed to a change in the temperature of the decomposer, and the time required for the temperature of the decomposer to change from a change in the alternative fuel.

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

[0016] The input module is used to input the changes in the feed amount of alternative fuel, the changes in the calorific value of alternative fuel, the changes in the moisture content of alternative fuel, and the sensible and latent heat information of the moisture content of alternative fuel.

[0017] The analysis module is used to calculate the coal fuel auxiliary adjustment amount and coal fuel auxiliary adjustment time based on the information input by the input module, using the decomposition furnace outlet temperature compensation control method disclosed in this invention for any alternative fuel change.

[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 includes a temperature controller, which is used to calculate the main adjustment amount of coal fuel based on the deviation between the actual value and the target value of the decomposition furnace temperature.

[0020] The beneficial effects of this invention are as follows: This invention can maximize the advance compensation adjustment of the coal feed rate (feedforward control) when the alternative fuel changes, and the adjustment amount conforms to the thermodynamic balance mechanism, effectively reducing or even eliminating fluctuations in the decomposer outlet temperature, reducing the impact on downstream operating conditions, and ensuring stable clinker quality. Since alternative fuels typically contain high moisture content, and the moisture content changes significantly when the alternative fuel changes, this invention fully considers the change in heat consumed by moisture during combustion due to changes in the moisture content of the alternative fuel, and uses this as an important factor in calculating the additional coal feed rate when the alternative fuel changes, effectively reducing or even eliminating... In addition to improving the accuracy of the decomposition furnace outlet temperature compensation control by adjusting the moisture content of the alternative fuel, ensuring the stability of the decomposition furnace outlet temperature; by calculating the adjustment time of the auxiliary coal feed amount by measuring the time required for the decomposition furnace temperature to change after a change in the alternative fuel, the adjustment time of the auxiliary coal feed amount is made more accurate when the alternative fuel changes, avoiding large fluctuations in the decomposition furnace outlet temperature caused by changes in coal feed amount due to different times required for changes in different fuels (referring to coal fuel and alternative fuel). Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the control method of the present invention. Detailed Implementation

[0022] See Figure 1 This invention discloses a method for compensating for the temperature at the decomposer outlet when the alternative fuel changes. The method involves real-time adjustment of the coal feed rate based on a primary coal fuel adjustment, calculated according to the deviation between the actual and target temperatures of the decomposer. Additional coal feed rate adjustments are also made based on a secondary coal fuel adjustment during the secondary adjustment time. The secondary coal fuel adjustment is calculated by determining the change in heat generated by the combustion of the alternative fuel (a substitute for coal, such as waste) when the alternative fuel changes. The required coal feed adjustment to compensate for this heat change is then calculated and used as the secondary coal fuel adjustment. The secondary coal fuel adjustment time is calculated based on the time required for the decomposer temperature to change after the alternative fuel change and the time required for the decomposer temperature to change after the coal feed change.

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

[0024] When the decomposer uses both coal and alternative fuels, the total heat required for decomposing the raw materials is provided by the combined calorific value of the coal and the alternative fuels. The total calorific value of the coal depends on the amount of coal fed and its calorific value, while the total calorific value of the alternative fuel depends on the total amount of alternative fuel fed and its calorific value. The moisture content of the alternative fuel consumes heat during combustion, and its content has a negative impact on the total calorific value. In other words, the higher the moisture content of the alternative fuel, the higher the heat consumed by the moisture, and the less heat is available for decomposing the raw materials.

[0025] (1)

[0026] (2)

[0027] (3)

[0028] in, This represents the total heat required to decompose raw materials per hour, expressed in kJ / h. This represents the heat generated per hour by coal combustion, expressed in kJ / h. The heat generated per hour by the combustion of alternative fuels is expressed in kJ / h. This represents the calorific value of coal fuel, expressed in J / kg. This represents the current coal fuel feed rate, expressed in t / h. The calorific value of the alternative fuel is expressed in J / kg. The feed rate for alternative fuels is expressed in t / h. The percentage of water content in alternative fuels, expressed in % . This represents the amount of heat consumed per kilogram of water per hour to heat it from room temperature to 880°C, expressed in kJ / h.

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

[0030] (4)

[0031] (5)

[0032] (6)

[0033] (7)

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

[0035] (8)

[0036] in, This refers to the coal fuel by-product adjustment quantity, expressed in t / h. This refers to the change in the total calorific value of the alternative fuel combustion per hour when the alternative fuel changes (or the overall calorific value change of the alternative fuel combustion), with the unit being kJ / h; The change in heat generated by complete combustion before and after a change in alternative fuel per hour, expressed in kJ / h. The change in heat loss per hour due to changes in moisture content when the alternative fuel changes, expressed in kJ / h. The change in the amount of alternative fuel feed is expressed in t / h. The change in calorific value of the alternative fuel is expressed in J / kg. The change in the moisture content of alternative fuels is expressed in % (%). The sensible and latent heat of water in alternative fuels are expressed in J / kg. This represents the calorific value of coal fuel, expressed in J / kg.

[0037] Since the time required for a change in alternative fuel to a change in the decomposer temperature is usually different from the time required for a change in the decomposer coal feed to a change in the decomposer temperature, in order to ensure that the decomposer outlet temperature remains basically stable and does not fluctuate significantly when the alternative fuel changes, it is necessary to calculate the adjustment time (the additional coal feed amount) of the coal fuel (the coal fuel auxiliary adjustment time) to compensate for the change in heat (the change in heat generated by the combustion of the alternative fuel due to the change in alternative fuel). This is to ensure that the effect of adjusting the coal feed amount on the decomposer outlet temperature is basically consistent with the assumption that the alternative fuel does not change (using the original alternative fuel and keeping the feed amount unchanged).

[0038] The preferred method for calculating the coal fuel adjustment time is as follows:

[0039] when Immediately adjust the coal feed (make additional coal feed adjustments).

[0040] when When, delay Time-adjusted coal feeding (adjusting the additional coal feeding amount);

[0041] in, The time required for a change in the coal feed to the decomposer to lead to a change in the decomposer temperature; The time required for a change in fuel type to occur, leading to a change in the temperature of the decomposition furnace.

[0042] The specific calculation method is as follows: keeping the raw material feed rate and alternative fuel feed rate of the decomposer constant, increase the coal feed rate and record the time of the coal feed rate increase. Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the increased temperature, record the moment when the temperature of the decomposition furnace begins to rise and maintain the increased temperature. , ; The calculation method is as follows: keep the raw material feed rate and coal feed rate of the decomposition furnace unchanged, increase the feed rate of alternative fuel, and record the time when the feed rate of alternative fuel is increased. Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the increased temperature, record the moment when the temperature of the decomposition furnace begins to rise and maintain the increased temperature. , .

[0043] In order to make and The calculation results are more accurate (more in line with actual production conditions) and can be calculated multiple times. and (For example, calculate 3-4 times for each), and take the average value as the time required for the temperature of the decomposer to change from a change in the coal feed to a change in the temperature of the decomposer, and the time required for the temperature of the decomposer to change from a change in the alternative fuel.

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

[0045] The input module is used to input the changes in the feed amount of alternative fuel, the changes in the calorific value of alternative fuel, the changes in the moisture content of alternative fuel, and the sensible and latent heat information of the moisture content of alternative fuel.

[0046] The analysis module is used to calculate the coal fuel auxiliary adjustment amount and coal fuel auxiliary adjustment time based on the information input by the input module, using the decomposition furnace outlet temperature compensation control method disclosed in this invention for any alternative fuel change.

[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 decomposer outlet temperature compensation control system preferably also includes a temperature controller, which calculates the main coal fuel adjustment amount based on the deviation between the actual and target values ​​of the decomposer temperature and outputs it to the coal feeding system. The coal feeding system of the decomposer adjusts the coal feed of the decomposer based on the main coal fuel adjustment amount, the secondary coal fuel adjustment amount, and the secondary coal fuel adjustment time.

[0049] The actual temperature of the decomposition furnace and the information required by the input module can be collected using appropriate sensors based on existing technology.

[0050] Unless otherwise specified or further limited to one preferred or optional technical means being another, the preferred and optional technical means disclosed in this invention can be arbitrarily combined to form several different technical solutions.

Claims

1. A method for compensating for changes in the outlet temperature of a decomposer when alternative fuels change, wherein the coal feed rate is adjusted in real time based on the main adjustment amount of the coal fuel, and the main adjustment amount of the coal fuel is calculated based on the deviation between the actual value and the target value of the decomposer temperature, characterized in that... Additional coal feed adjustment is also made based on the coal fuel adjustment amount during the coal fuel adjustment time. The coal fuel adjustment amount is the amount of coal fuel required to compensate for changes in the heat generated by the combustion of alternative fuels due to changes in alternative fuels. The coal fuel adjustment time is calculated based on the time required for a change in alternative fuel to occur and for a change in the decomposer temperature to occur, as well as the time required for a change in the decomposer coal feed to occur and for a change in the decomposer temperature. The calculation method for the coal fuel adjustment amount is as follows: ， in, This refers to the coal fuel by-product adjustment quantity, expressed in t / h. The change in the amount of alternative fuel feed is expressed in t / h. The change in calorific value of the alternative fuel is expressed in J / kg. The change in the moisture content of alternative fuels is expressed in % (%). The sensible and latent heat of water in alternative fuels are expressed in J / kg. This represents the calorific value of coal fuel, expressed in J / kg.

2. The method for compensating and controlling the outlet temperature of the decomposer when the alternative fuel changes, as described in claim 1, is characterized in that... The calculation method for the coal fuel adjustment time is as follows: when If necessary, adjust the coal feeding immediately; when When, delay Adjust coal feeding time; in, The time required for a change in the coal feed to the decomposer to lead to a change in the decomposer temperature; The time required for a change in fuel type to occur, leading to a change in the temperature of the decomposition furnace.

3. The method for compensating and controlling the outlet temperature of the decomposer when the alternative fuel changes, as described in claim 2, is characterized in that... The calculation method is as follows: keeping the raw material feed rate and alternative fuel feed rate of the decomposer constant, increase the coal feed rate and record the time of the increase. Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the increased temperature, record the moment when the temperature of the decomposition furnace begins to rise and maintain the increased temperature. , ; The calculation method is as follows: keeping the raw material feed rate and coal feed rate of the decomposition furnace constant, increase the feed rate of alternative fuel and record the time when the feed rate of alternative fuel is increased. Observe the temperature change of the decomposition furnace. When the temperature of the decomposition furnace rises and can maintain the increased temperature, record the moment when the temperature of the decomposition furnace begins to rise and maintain the increased temperature. , .

4. The method for compensating and controlling the outlet temperature of the decomposer when the alternative fuel changes, as described in claim 3, is characterized in that... Calculate multiple times separately and The average value is taken as the time required for a change in the coal feed to lead to a change in the temperature of the decomposer, and the time required for a change in the temperature of the decomposer to lead to a change in the temperature of the decomposer, and the average value is taken as the average value.

5. A decomposition furnace outlet temperature compensation control system, characterized in that... include: The input module is used to input the changes in the feed amount of alternative fuel, the changes in the calorific value of alternative fuel, the changes in the moisture content of alternative fuel, and the sensible and latent heat information of the moisture content of alternative fuel. The analysis module is used to calculate the coal fuel auxiliary adjustment amount and coal fuel auxiliary adjustment time based on the information input by the input module, using the decomposer outlet temperature compensation control method for changes in alternative fuel as described in any one of claims 1-4. The output module is used to output the calculation results of the analysis module to the coal feeding system.

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