Grate furnace incineration control method based on heat balance heat value back calculation and layered coordinated decision

Abstract

The application discloses a grate furnace incineration control method based on heat balance heat value back calculation and layered coordination decision. The grate furnace incineration control method comprises the following steps: obtaining heat income item data and heat expenditure item data of a grate furnace incineration system for several days, calculating an average low heat value, and obtaining a heat value reference value of an incineration day according to the average low heat value for several days; determining reference motion parameters of a pusher and each stage of grate and reference air volume of each stage of grate according to the heat value reference value and a steam flow setting value; generating motion correction amounts of the pusher and each stage of grate according to incineration temperature and steam flow variation, incineration temperature variation rate, garbage layer thickness deviation and upper part temperature deviation of a burnout grate; generating air volume correction amounts of the pusher and each stage of grate according to incineration temperature and steam flow variation, garbage layer thickness, upper part temperature of the burnout grate and left and right side deviation of the garbage layer thickness; and obtaining target execution instructions according to the motion correction amounts and the air volume correction amounts.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for municipal solid waste incinerators, and more specifically, to a grate furnace incineration control method based on heat balance calorific value back-calculation and hierarchical coordination decision-making. Background Technology

[0002] In municipal solid waste incineration power generation, the operating status of the grate furnace is significantly affected by changes in the moisture content, calorific value, particle size, and composition of the waste entering the furnace. The uncertainty in waste composition leads to fluctuations in operating indicators such as incineration temperature, steam output, flue gas oxygen content, and slag loss on ignition. Existing automatic combustion control systems typically rely on preset parameters and single-point adjustment logic, making it difficult to promptly correct baseline parameters when operating conditions change significantly.

[0003] Original technical materials indicate that there is a coupling relationship between the feeder, drying grate, combustion grate, burnout grate, and primary air volume at each stage. Furthermore, incineration temperature, steam flow rate, waste bed thickness, and the temperature at the top of the burnout grate each correspond to different local correction logics. If adjustments are made solely based on individual point logics, multiple logics may operate simultaneously and contradict each other. Summary of the Invention

[0004] (a) The technical problem to be solved by the present invention To address the challenges of directly obtaining the calorific value of waste fed into grate furnaces during operation, the difficulty in establishing timely control benchmarks for the day of incineration, and the tendency for multiple local correction logics to deviate from each other when operating in parallel, a grate furnace incineration control method based on heat balance calorific value back-calculation and hierarchical coordinated decision-making is proposed.

[0005] (II) The technical solution adopted in this invention A grate furnace combustion control method based on heat balance calorific value back-calculation and hierarchical coordination decision-making, the grate furnace combustion control method comprising: Obtain heat income and heat expenditure data for several days from the grate furnace incineration system. Calculate the average lower heating value based on the daily heat income and heat expenditure data. Obtain the baseline calorific value for the incineration day based on the average lower heating value for several days. The reference motion parameters of the pusher and each stage of the grate, as well as the reference air volume of each stage of the grate, are determined based on the aforementioned calorific value reference value and steam flow rate set value. Based on the changes in incineration temperature and steam flow rate, the rate of change in incineration temperature, the deviation in waste material layer thickness, and the temperature deviation at the top of the burnt-out grate, motion correction amounts are generated for the pusher and each stage of the grate; based on the changes in incineration temperature and steam flow rate, waste material layer thickness, the temperature at the top of the burnt-out grate, and the left-right difference in waste material layer thickness, air volume correction amounts are generated for the pusher and each stage of the grate. The target execution command is obtained based on the motion correction amount and the air volume correction amount.

[0006] Optionally, methods for calculating the average lower heating value based on daily heat income and heat expenditure data include: The waste combustion heat item is calculated based on the heat balance relationship between the heat input item data and the heat output item data. The average lower heating value is calculated based on the waste combustion heat term and the total waste feed rate per unit time.

[0007] Optionally, the motion correction amount includes at least one of the following: position and / or speed correction amount of the pusher, period correction amount of the drying grate, period correction amount of the combustion grate, and period correction amount of the burnout grate.

[0008] Optionally, the air volume correction amount includes at least one of the following: primary air volume correction amount, combustion section primary air volume correction amount, combustion section primary air volume correction amount, and left and right side air volume balance correction amount.

[0009] Optionally, the target execution command is obtained based on the motion correction amount and the airflow correction amount, including: When multiple correction quantities act simultaneously within the same control cycle, priority selection or cancellation is performed on correction quantities that act on the same execution object and have opposite directions, and correction quantities with the same direction are synthesized and limited.

[0010] Optionally, the target execution command is obtained based on the motion correction amount and the airflow correction amount, including: When multiple correction amounts act simultaneously within the same control cycle, first determine the total primary air volume correction amount, then allocate the air volume for the combustion section and the burnout section, and add the left and right side air volume balance correction amount on the basis of the segmented air volume.

[0011] Optionally, the grate furnace combustion control method further includes; Adjust the hydraulic actuators of the pusher, grate, and primary air regulating baffle according to the target execution command.

[0012] Optionally, the heat input items include at least the sensible heat of waste, the heat of waste combustion, the sensible heat of leaked air, the sensible heat of boiler feedwater, the sensible heat of primary air, the sensible heat of secondary air, the heat of natural gas combustion, and the sensible heat of natural gas combustion air; the heat output items include at least the sensible heat carried out by slag, the heat loss due to non-combustion, the heat carried out by boiler fly ash, the heat carried out by flue gas, the heat carried out by fly ash in flue gas, the heat loss due to boiler wastewater, the heat loss due to ammonia solution evaporation, the heat loss due to leachate evaporation, heat dissipation, and the heat carried out by steam.

[0013] (III) Beneficial Effects The present invention discloses a grate furnace combustion control method based on heat balance calorific value back-calculation and hierarchical coordination decision-making, which has the following technical advantages compared with existing methods: 1. By performing heat balance accounting on heat income and heat expenditure items according to statistical periods, and further forming the calorific value benchmark value on the day of incineration, a corresponding relationship is established between the control benchmark on the day of incineration and the recent changes in operating calorific value.

[0014] 2. By uniformly determining the reference motion parameters of the pusher and each level of grate, as well as the reference air volume of each level of grate, based on the calorific value reference value, the calculation source of grate motion and air distribution reference is unified.

[0015] 3. By incorporating multiple local adjustment logics into a higher-level decision-making logic for judgment and coordination, and by combining the left and right side difference ratio to correct the air volume balance of the combustion section and the burnout section, the possibility of multiple single-point logics acting in parallel and deviating from each other is reduced. Attached Figure Description

[0016] Figure 1 This is a flowchart of the main steps of a grate furnace combustion control method based on thermal balance calorific value back-calorific value calculation and hierarchical coordination decision-making, according to one or more embodiments.

[0017] Figure 2 This is a flowchart for determining the calorific value baseline for the day of incineration according to one or more embodiments.

[0018] Figure 3 This is a flowchart for determining the reference motion parameters and reference air volume of each grate according to one or more embodiments.

[0019] Figure 4 A flowchart illustrating how to coordinate multiple control corrections and output target execution instructions based on a higher-level decision logic of one or more embodiments. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] Before describing the various embodiments of this application in detail, the technical concept of this application is first briefly described: Existing automatic combustion control systems typically rely on preset parameters and single-point adjustment logic, making it difficult to correct the reference parameters in a timely manner when operating conditions change significantly. Therefore, the grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordination decision-making provided in this application has the key improvement of performing heat balance accounting on heat input and heat output items according to statistical periods, and further forming a reference value for the calorific value on the day of combustion. This establishes a correspondence between the control reference for the day and recent changes in operating calorific value. By uniformly determining the reference motion parameters of the pusher, each level of grate, and the reference air volume of each level of grate using the aforementioned calorific value reference, the calculation source for grate motion and air distribution references is unified. Finally, the target execution command is obtained by comprehensively coordinating the motion correction and air volume correction, reducing the possibility of mutual deviation when multiple single-point logics operate in parallel. The specific principles of the grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordination decision-making in this application are described below with reference to more embodiments.

[0022] Specifically, such as Figure 1 As shown, the grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordination decision-making in this embodiment includes the following steps: Step S10: Obtain heat income and heat expenditure data for several days from the grate furnace incineration system; calculate the average lower heating value based on the daily heat income and heat expenditure data; and obtain the calorific value benchmark value for the incineration day based on the average lower heating value for several days. Step S20: Determine the reference motion parameters of the pusher and each stage of the grate, as well as the reference air volume of each stage of the grate, based on the calorific value reference value and the steam flow rate set value. Step S30: Based on the changes in incineration temperature and steam flow rate, the rate of change in incineration temperature, the deviation in waste material layer thickness, and the temperature deviation at the top of the burnt-out grate, generate motion correction amounts for the pusher and each stage of the grate respectively; based on the changes in incineration temperature and steam flow rate, waste material layer thickness, the temperature at the top of the burnt-out grate, and the left-right difference in waste material layer thickness, generate airflow correction amounts for the pusher and each stage of the grate respectively. Step S40: Obtain the target execution command based on the motion correction amount and the air volume correction amount.

[0023] In one or more embodiments, the heat input items include at least the sensible heat of waste, the heat of waste combustion, the sensible heat of leaked air, the sensible heat of boiler feedwater, the sensible heat of primary air, the sensible heat of secondary air, the heat of natural gas combustion, and the sensible heat of natural gas combustion air; the heat output items include at least the sensible heat carried out by slag, the heat loss due to non-combustion, the heat carried out by boiler fly ash, the heat carried out by flue gas, the heat carried out by fly ash in flue gas, the heat loss due to boiler wastewater, the heat loss due to ammonia solution evaporation, the heat loss due to leachate evaporation, heat dissipation, and the heat carried out by steam.

[0024] For example, such as Figure 2 As shown, the method for calculating the average lower heating value based on daily heat income and heat expenditure data includes: calculating the waste combustion calorific value based on the heat balance relationship between the heat income and heat expenditure data; and calculating the average lower heating value based on the waste combustion calorific value and the total waste input per unit time. For example, heat income and heat expenditure data are collected for 10 consecutive days.

[0025] For example, the heat balance calculation satisfies: , In the formula, For heat input item number, For heat expenditure item number, to These are the heat income items, to These are heat expenditure items, The calorific value of waste combustion satisfies the following: , In the formula, The average lower heating value of the waste fed into the furnace during the statistical period. This refers to the cumulative amount of waste fed into the furnace during the statistical period; when to When expressed as heat flow per unit time, This represents the total amount of waste fed per unit time.

[0026] Among them, the average lower heating value By incinerating the heat of waste Substituting the unknown term into the heat balance calculation formula, we obtain the result through inverse calculation, namely: , .

[0027] Subsequently, a weighted average of the lower calorific value over a statistical period of more than 10 consecutive days was calculated to obtain the baseline calorific value for the day of incineration. .

[0028] In one or more embodiments, such as Figure 3 As shown, the baseline calorific value for the day of incineration was obtained. Then, based on the steam flow rate set value The corresponding heat demand and the baseline calorific value on the day of incineration Determine the reference motion parameters for the pusher, drying grate, combustion grate, and burnout grate.

[0029] For example, firstly based on the enthalpy difference between steam and feedwater and the baseline calorific value on the day of incineration Determine waste demand : , In the formula, To meet the demand for waste, Set the steam flow rate. The difference in enthalpy between steam and feedwater. This is the baseline calorific value for the day of incineration. Enthalpy difference between steam and feedwater. satisfy: , In the formula, For the enthalpy of superheated steam, For boiler feedwater enthalpy, This represents the enthalpy difference between steam and feedwater.

[0030] Then set the value according to the proportion of waste. Convert waste demand into required waste volume : , In the formula, For the required waste volume, To meet the demand for waste, Set a value for the weight of waste.

[0031] Subsequently, based on the relationship between volume and speed, the required waste volume is converted into the reference motion parameters of the pusher, drying grate, combustion grate, and burnout grate.

[0032] In one or more embodiments, for the primary air reference air volume, the total reference air volume of the grate is determined based on the heat demand corresponding to the steam flow rate setpoint, the calorific value reference value of the combustion day, the fuel air distribution relationship and the excess air coefficient, and the reference air volume of the drying grate, the combustion grate and the burnout grate are determined according to the air volume distribution ratio.

[0033] For example, the set value for the waste bed thickness is determined by the waste demand, grate area parameters, and relevant empirical coefficients; the measured value for the waste bed thickness is determined by the waste bed differential pressure, the primary air differential pressure of the first section of the combustion grate, and relevant empirical coefficients. The set value for the waste bed thickness is used to correct the reference motion parameters of the pusher, drying grate, and combustion grate; the measured value for the waste bed thickness reflects the actual state of the bed in the combustion section.

[0034] Adjust the left and right air volume balance of the same group of combustion grates according to the difference ratio of the thickness of the waste material layer on the left and right sides, and adjust the left and right air volume balance of the same group of combustion grates according to the temperature difference ratio of the upper left and right sides of the burnt-out grate.

[0035] In one or more embodiments, after obtaining the baseline motion parameters, control correction quantities for the grate motion are generated according to different feedback quantities. The motion correction quantities for the grate motion refer to the set of correction quantities acting on the pusher and each stage of the grate hydraulic actuators, including at least one of the pusher position and / or speed correction quantities, drying grate cycle correction quantities, combustion grate cycle correction quantities, and burnout grate cycle correction quantities. The motion correction quantities include at least one of the pusher position and / or speed correction quantities, drying grate cycle correction quantities, combustion grate cycle correction quantities, and burnout grate cycle correction quantities. The specific correction logic includes at least: 1. Generate motion corrections for the position and / or speed of the pusher, the drying grate cycle, the combustion grate cycle, and / or the burnout grate cycle based on changes in combustion temperature and steam flow.

[0036] 2. Generate motion corrections for the feeder position or speed, drying grate cycle, combustion grate cycle, and / or burnout grate cycle based on the rate of change of combustion temperature.

[0037] 3. Generate motion corrections for the pusher position or speed, drying grate cycle, and / or combustion grate cycle based on the deviation in waste material layer thickness.

[0038] 4. Generate the motion correction amount for the burnout grate cycle based on the temperature deviation at the top of the burnout grate.

[0039] In one or more embodiments, after obtaining the reference air volume for each grate level, control correction quantities for primary air are generated based on different feedback quantities. The control correction quantity for primary air refers to the set of correction quantities acting on the primary air regulating damper, including at least one of the following: total primary air correction quantity, primary air volume correction quantity for the combustion zone, primary air volume correction quantity for the burnout zone, and left / right side air volume balance correction quantity. The specific correction logic includes at least: 1. Generate the primary air total volume correction amount based on the changes in combustion temperature and steam flow rate.

[0040] 2. Generate the primary air volume correction amount for the combustion section based on the thickness of the waste material layer.

[0041] 3. Generate the primary air volume correction amount for the combustion section based on the temperature of the combustion section.

[0042] 4. Generate the anti-eccentric burning air supply correction amount based on the ratio of the thickness difference between the left and right sides of the waste material layer and the ratio of the temperature difference between the left and right sides of the upper part of the burnt grate.

[0043] In addition, the air volume balance on the left and right sides of the same group of combustion grates is adjusted according to the difference ratio of the thickness of the waste material layer on the left and right sides; the air volume balance on the left and right sides of the same group of burnt-out grates is adjusted according to the temperature difference ratio of the upper left and right sides of the burnt-out grate. Among them, the correction amount for the air volume balance on the left and right sides of the same group of combustion grates and the correction amount for the air volume balance on the left and right sides of the same group of burnt-out grates are both control correction amounts for primary air.

[0044] When multiple control corrections act simultaneously within the same control cycle, a higher-level decision logic judges and coordinates the outputs of these multiple single-point logics to obtain the target execution command. Judgment and coordination include: prioritizing or canceling control corrections acting on the same execution target but in opposite directions; synthesizing and limiting control corrections in the same direction; for primary air control corrections, first determining the total primary air correction amount, then allocating air volume to the combustion and burnout sections, and superimposing left and right side air volume balance corrections on top of the segmented air volumes. The target execution command is output to the pusher hydraulic actuator, the grate hydraulic actuator, and the primary air regulating baffle to control the grate furnace operation.

[0045] In this embodiment, the target execution command may include at least one of the following: pusher position or speed command, drying grate cycle command, combustion grate cycle command, burnout grate cycle command, and primary air regulating damper opening command.

[0046] Compared with existing technologies, the grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordinated decision-making has at least the following advantages: 1. By performing heat balance accounting on heat income and heat expenditure items according to statistical periods, and further forming the calorific value benchmark value on the day of incineration, a corresponding relationship is established between the control benchmark on the day of incineration and the recent changes in operating calorific value.

[0047] 2. By uniformly determining the reference motion parameters of the pusher, each level of grate, and the reference air volume of each level of grate based on the aforementioned calorific value reference, the calculation source of grate motion and air distribution reference is unified.

[0048] 3. By incorporating multiple local adjustment logics into a higher-level decision-making logic for judgment and coordination, and by combining the left and right side difference ratio to correct the air volume balance of the combustion section and the burnout section, the possibility of multiple single-point logics acting in parallel and deviating from each other is reduced.

[0049] The specific embodiments of the present invention have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that modifications and improvements can be made to these embodiments without departing from the principles and spirit of the present invention as defined by the claims and their equivalents, and such modifications and improvements should also be within the protection scope of the present invention.

Claims

1. A grate furnace combustion control method based on heat balance calorific value back-calculation and hierarchical coordinated decision-making, characterized in that, The grate furnace combustion control method includes: Obtain heat income and heat expenditure data for several days from the grate furnace incineration system. Calculate the average lower heating value based on the daily heat income and heat expenditure data. Obtain the baseline calorific value for the incineration day based on the average lower heating value for several days. The reference motion parameters of the pusher and each stage of the grate, as well as the reference air volume of each stage of the grate, are determined based on the aforementioned calorific value reference value and steam flow rate set value. Based on the changes in incineration temperature and steam flow rate, the rate of change in incineration temperature, the deviation in waste material layer thickness, and the temperature deviation at the top of the burnt-out grate, motion correction amounts are generated for the pusher and each stage of the grate; based on the changes in incineration temperature and steam flow rate, waste material layer thickness, the temperature at the top of the burnt-out grate, and the left-right difference in waste material layer thickness, air volume correction amounts are generated for the pusher and each stage of the grate. The target execution command is obtained based on the motion correction amount and the air volume correction amount.

2. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordination decision-making according to claim 1, characterized in that, Methods for calculating the average lower heating value based on daily heat income and heat expenditure data include: The waste combustion heat item is calculated based on the heat balance relationship between the heat input item data and the heat output item data. The average lower heating value is calculated based on the waste combustion heat term and the total waste feed rate per unit time.

3. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordinated decision-making according to claim 1, characterized in that, The motion correction includes at least one of the following: position and / or speed correction of the pusher, period correction of the drying grate, period correction of the combustion grate, and period correction of the burnout grate.

4. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordinated decision-making according to claim 1, characterized in that, The air volume correction includes at least one of the following: primary air volume correction, combustion section primary air volume correction, burnout section primary air volume correction, and left and right side air volume balance correction.

5. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordinated decision-making according to claim 3, characterized in that, The target execution command is obtained based on the motion correction amount and the airflow correction amount, including: When multiple correction quantities act simultaneously within the same control cycle, priority selection or cancellation is performed on correction quantities that act on the same execution object and have opposite directions, and correction quantities with the same direction are synthesized and limited.

6. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordinated decision-making according to claim 3, characterized in that, The target execution command is obtained based on the motion correction amount and the airflow correction amount, including: When multiple correction amounts act simultaneously within the same control cycle, first determine the total primary air volume correction amount, then allocate the air volume for the combustion section and the burnout section, and add the left and right side air volume balance correction amount on the basis of the segmented air volume.

7. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordination decision-making according to claim 5, characterized in that, The grate furnace combustion control method also includes; Adjust the hydraulic actuators of the pusher, grate, and primary air regulating baffle according to the target execution command.

8. The grate furnace combustion control method based on heat balance calorific value back-calorific value calculation and hierarchical coordination decision-making according to claim 1, characterized in that, The heat input items include at least the sensible heat of waste, the heat of waste combustion, the sensible heat of leaked air, the sensible heat of boiler feedwater, the sensible heat of primary air, the sensible heat of secondary air, the heat of natural gas combustion, and the sensible heat of natural gas combustion air; the heat output items include at least the sensible heat carried out by slag, the heat loss due to non-combustion, the heat carried out by boiler fly ash, the heat carried out by flue gas, the heat carried out by fly ash in flue gas, the heat loss of boiler wastewater, the heat loss due to ammonia solution evaporation, the heat loss due to leachate evaporation, heat dissipation, and the heat carried out by steam.

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