Coal bunker coal level precision control method during shutdown of coal-fired boiler

Abstract

The present application relates to a kind of coal bunker coal level precision control method during coal-fired boiler outage, comprising: unit plan is resolved before a day to each coal bunker coal level control;Actual calorific value of current coal into furnace and the actual coal storage capacity of each coal bunker are calculated;Set the outage sequence of coal mill and the load node of outage;The theoretical coal requirement of each coal bunker corresponding to pulverizing system is calculated;The theoretical bunker capacity of each coal bunker is calculated, and the corresponding weight of coal is added to the corresponding coal bunker;After the coal bunker is burned empty, the corresponding pulverizing system is stopped;Generator unit is resolved;After the coal bunker corresponding to the last coal mill is burned empty and purged, boiler main fuel is tripped.The beneficial effects of the present application are: the present application can accurately calculate the coal requirement of different pulverizing system, and finally through the reasonable control of the coal bunker amount and the coal amount of each coal feeder, the shutdown resolution time can be accurately matched, and the problem of coal bunker burning empty in advance or delaying is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation, and more specifically, to a method for precise control of coal bunker levels during the shutdown of a coal-fired boiler. Background Technology

[0002] Currently, coal-fired power remains the primary source of energy for society. However, coal-fired power units frequently require scheduled maintenance and shutdowns each year based on factors such as societal electricity demand and equipment health to ensure their continuous and stable operation and provide society with safe, stable, and reliable energy.

[0003] Coal used in coal-fired power plants is often highly moist due to factors such as weather and coal quality, especially in power plants with open-air coal storage. During unit shutdowns or maintenance, if coal accumulates in the coal feeder's bunker for a long period and is subject to high humidity, it can easily become caking. This can cause the coal feeder to stop feeding coal or even fail to feed coal when the unit restarts, leading to significant fluctuations in parameters such as superheat, main steam and reheat steam temperatures, and furnace negative pressure. In severe cases, this can cause boiler tripping, threatening the safe and stable operation of the unit. Furthermore, caking in the coal feeder's bunker requires manual clearing, wasting considerable manpower and resources. In addition, if the coal has been stored for more than 7 days, there is a risk of spontaneous combustion due to oxidation.

[0004] For the reasons mentioned above, when a coal-fired power unit is shut down for more than 7 days, it is necessary to deplete the coal in the coal bunkers of each feeder during the planned shutdown of the unit. However, in reality, due to various reasons such as changes in coal quality, inaccurate estimation of the amount of coal in the feeders, and inaccurate prediction of the amount of coal required for unit shutdown, a large amount of coal remains in the coal bunkers after the planned shutdown of the power unit. This necessitates maintaining boiler operation after the shutdown, wasting coal and prolonging boiler downtime. The current conventional method is to use a 3D material imager to display the coal in the coal bunkers using 3D imaging on software, and then calculate the amount of coal in the corresponding bunker. However, because 3D material imagers are expensive, this method not only drastically increases costs, but also only displays the amount of coal in the corresponding bunker. It cannot directly provide suggestions for replenishing the bunkers based on the unit's shutdown load curve and the current amount of coal in the bunkers, thus failing to achieve precise control of the coal level in the bunkers, meaning that the planned shutdown time of the unit cannot be synchronized with the depletion of the coal in the bunkers. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for precise control of coal bunker levels during coal-fired boiler shutdowns, comprising:

[0006] S1. The day before the planned disconnection of the unit, the coal level in each coal bunker will be controlled at the first target coal level and the second target coal level, respectively; the first target coal level shall be lower than the second target coal level.

[0007] S2. Calculate the actual calorific value of the coal currently being fed into the furnace;

[0008] S3. Calculate the actual coal inventory in each coal bunker.

[0009] S4. Set the shutdown sequence and shutdown load nodes of the coal mill;

[0010] S5. Calculate the theoretical coal demand of each coal bunker for each pulverizing system based on the shutdown load curve.

[0011] S6. Calculate the theoretical capacity of each coal bunker and add the corresponding weight of coal to the corresponding coal bunker according to the theoretical capacity recommendation.

[0012] S7. Stop the corresponding pulverizing system after the coal bunker is emptied.

[0013] S8. Once the unit load drops below the first target load and there is no risk of exceeding environmental protection standards, the generator unit is disconnected from the grid.

[0014] S9. After the coal bunker corresponding to the last coal mill is emptied and purged, the boiler main fuel trips (MFT).

[0015] As a preferred embodiment, in S1, when there are six coal mills, the coal bunker corresponding to the first coal mill is emptied in advance, and the coal level in the coal bunkers corresponding to the second and third coal mills is controlled at the first target coal level, while the coal level in the coal bunkers corresponding to the fourth, fifth, and sixth coal mills is controlled at the second target coal level; the first coal mill is the first coal mill that is shut down during the unit shutdown process.

[0016] As a preferred option, in S2, the formula for calculating the actual calorific value of the coal fed into the furnace is:

[0017]

[0018] In the formula, P is the unit load (MW); ΔH is the heat consumption of the turbine under the current load (kJ / kW·h); K is the correction coefficient for the turbine heat consumption due to unit vacuum under the current load; η gl Boiler efficiency, %; η gd Pipeline efficiency, %; C is the current coal quantity of the unit, t / h; Q js The calorific value of the coal fed into the furnace is calculated in kcal / kg.

[0019] As a preferred option, in S3, the formula for calculating the mass of coal stored in the coal bunker is:

[0020] m=ρV

[0021] In the formula, ρ is the density of the coal, V is the actual volume of the coal calculated according to the algorithm corresponding to the coal position h in the coal bunker, and m is the mass of the coal stored in the coal bunker.

[0022] As a preferred embodiment, in S4, when there are six coal mills, the first to sixth coal mills are defined according to the order of shutdown, and the load nodes of the second to sixth coal mills that are shut down are respectively designated as the second to sixth loads.

[0023] As a preferred option, in S5, the formula for calculating the theoretical coal requirement of the coal bunker is:

[0024] C = f(P)

[0025]

[0026] In the formula, C is the coal quantity corresponding to the current load, t / h; f() is the coal quantity function expression corresponding to different loads of the unit; P is the current load of the unit, MW; C tatal Let f(P) be the total amount of coal required by the unit for this load segment from time 0 to time t; f(P) is the amount of coal corresponding to the unit load of P at time t, in t / h.

[0027] As a preferred option, in S5, the theoretical coal demand calculated for each coal mill needs to be multiplied by a correction factor K. c K c =Q jh / Q js In the formula Q jh To verify the calorific value of coal, the unit is kcal / kg, Q js The calorific value of the coal fed into the furnace, calculated in step S2 above, is expressed in kcal / kg.

[0028] As a preferred option, in S6, when the theoretical coal demand is greater than the actual coal storage, the recommended coal quantity needs to be added to this coal bunker. When the theoretical coal demand is less than the actual coal storage, the coal quantity distribution of the coal feeder is adjusted by adding a positive bias to the corresponding coal feeder coal quantity instruction, so as to consume the excess coal quantity in advance.

[0029] As a preferred option, S8 specifies the planned disconnection time for the generating units, controlling the disconnection time to be within 10 minutes before the hour.

[0030] The beneficial effects of this invention are as follows: By utilizing the characteristics of the DCS coal level and coal bunker structure, and employing scientific calculation methods, this invention accurately calculates the remaining coal quantity in the coal bunker. Combined with the shutdown load curve, it dynamically calculates the total coal quantity required before shutdown. During shutdown, based on the number of pulverizing systems required to operate under the current load and the required operating time of each pulverizing system, the coal requirement of different pulverizing systems can be accurately calculated. Finally, by rationally controlling the filling amount of each coal bunker and the coal quantity of each coal feeder, the shutdown and disconnection time can be precisely matched, effectively avoiding the problem of the coal bunker burning out prematurely or delayed, thus improving the safety and economy of the unit. Attached Figure Description

[0031] Figure 1A flowchart of a method for precise control of coal bunker level during coal-fired boiler shutdown provided by the present invention;

[0032] Figure 2 This is a graph showing the relationship between load and coal consumption for the first and second phase units in this invention.

[0033] Figure 3 This is a schematic diagram of the coal bunker structure dimensions in an example of the present invention;

[0034] Figure 4 This is a planned curve of the unit shutdown load in an example of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0036] Example 1:

[0037] Embodiment 1 of this application provides a method for precise control of coal bunker coal level during coal-fired boiler shutdown. Its main purpose is to ensure that the planned disconnection time of the unit during boiler shutdown is basically synchronized with the emptying of the coal bunker coal level. Figure 1 As shown, it includes:

[0038] S1. One day before the planned disconnection of the unit, the coal level of each coal bunker will be controlled at the first target coal level and the second target coal level respectively; the first target coal level shall be lower than the second target coal level.

[0039] In S1, to achieve precise control of coal bunker levels, it is necessary to estimate the total coal consumption based on the load plan curve for the next day and pre-control the coal level in advance. Specifically, when there are six coal mills, the coal bunker corresponding to the first coal mill is emptied in advance, and the coal levels of the coal bunkers corresponding to the second and third coal mills are controlled at the first target coal level, while the coal levels of the coal bunkers corresponding to the fourth, fifth, and sixth coal mills are controlled at the second target coal level. The first coal mill is the first coal mill that is shut down during the unit shutdown process, and this description applies to the other coal mills.

[0040] S2. Calculate the actual calorific value of the coal currently being fed into the furnace.

[0041] In S2, it is necessary to accurately determine the calorific value of the coal currently fed into the furnace for subsequent adjustments to the coal demand. Specifically, based on the law of conservation of energy, the turbine heat consumption after a major overhaul cycle is considered a fixed quantity, while heat consumption, load, and vacuum are considered variables. Therefore, the calorific value of the coal currently fed into the furnace (hereinafter referred to as calculated calorific value, Q) can be calculated using the main parameters of the unit under different vacuum and load conditions, as well as relevant data such as turbine heat consumption.js The specific calculation formula is as follows:

[0042]

[0043] In the formula, P is the unit load (MW); ΔH is the heat consumption of the turbine under the current load (kJ / kW·h); K is the correction coefficient for the turbine heat consumption due to unit vacuum under the current load; η gl Boiler efficiency, %; η gd Pipeline efficiency, %; C is the current coal quantity of the unit, t / h; Q js The calorific value of the coal fed into the furnace is calculated in kcal / kg.

[0044] S3. Calculate the actual coal inventory in each coal bunker.

[0045] In S3, it is necessary to accurately calculate the actual coal storage volume of each coal bunker corresponding to each pulverizing system for coal allocation. Specifically, the mass of coal stored in the bunker is calculated by multiplying the coal density by the volume of coal stored in the bunker. The volume of coal stored in the bunker is calculated using the DCS coal level based on the height of the coal stored in the bunker and the structural dimensions of the bunker itself. The formula for calculating the mass of coal stored in the bunker is as follows:

[0046] m=ρV

[0047] In the formula, ρ is the density of the coal, V is the actual volume of the coal calculated according to the algorithm corresponding to the coal position h in the coal bunker, and m is the mass of the coal stored in the coal bunker.

[0048] S4. Set the shutdown sequence and shutdown load nodes for the coal mill.

[0049] To determine the shutdown time or load nodes for each coal mill, the shutdown sequence of each coal mill needs to be pre-set in S4. Based on the order of shutdown, these can be defined as the first coal mill, the second coal mill, the third coal mill, the fourth coal mill, the fifth coal mill, and the sixth coal mill. The load nodes for the shutdown of the second to sixth coal mills are the second load, the third load, the fourth load, the fifth load, and the sixth load, respectively.

[0050] S5. Calculate the theoretical coal demand of each pulverizing system based on the shutdown load curve.

[0051] In S5, to accurately calculate the theoretical coal requirement of each pulverizing system's corresponding coal bunker, it is first necessary to calculate the total coal requirement for each pulverizer's operating load segment, and then distribute it evenly among the coal bunkers based on the number of operating pulverizers. The total coal requirement for each load segment can be calculated using the load-coal quantity relationship curve used for coal type verification. The specific calculation formula is as follows:

[0052] C = f(P)

[0053] In the formula, C is the amount of coal corresponding to the current load, t / h; f() is the function expression of the amount of coal corresponding to different loads of the unit; P is the load of the current unit, MW.

[0054] Next, extract the load curve from the start to the end of the load segment based on the load plan curve, substitute it into the coal quantity calculation formula, and perform integral and cumulative calculation, as shown below:

[0055]

[0056] C tatal f(p) represents the total amount of coal required by the unit for this load segment from time 0 to time t; f(p) represents the amount of coal required at time t when the unit load is P, in t / h.

[0057] Finally, by combining the determined shutdown sequence of each coal mill, the load nodes of the coal mill shutdown, and the shutdown load curves identified in S4 above, the amount of coal required from each load node to the previous node can be calculated. For example, the total amount of coal required from the current moment to the second load is C1, and so on, the amount of coal required from the fifth load to the sixth load is C5. Thus, the amount of coal required from the current moment to the planned disconnection of the second, third, fourth, fifth, and sixth coal mills can be calculated as T1 / T2 / T3 / T4 / T5. The specific algorithm is as follows:

[0058] T1 = C1 / 5;

[0059] T2 = C1 / 5 + C2 / 4;

[0060] T3 = C1 / 5 + C2 / 4 + C3 / 3;

[0061] T4 = C1 / 5 + C2 / 4 + C3 / 3 + C4 / 2;

[0062] T5=C1 / 5+C2 / 4+C3 / 3+C4 / 2+C5;

[0063] In the formula, T1 / T2 / T3 / T4 / T5 represent the theoretical coal requirements of the second, third, fourth, fifth, and sixth shut-down coal mills, respectively. Since the calorific value of coal deviates from the design conditions during actual operation, the theoretical coal requirements calculated for each of the above coal mills need to be multiplied by a correction factor K to reduce the deviation in theoretical coal requirements caused by this calorific value variation. c K c =Q jh / Q js In the formula Q jh To verify the calorific value of coal, the unit is kcal / kg, Q jsThe calorific value of the coal fed into the furnace, calculated in step S2 above, is expressed in kcal / kg. The calculated coal quantity required for each pulverizer is then multiplied by the calorific value correction factor K. c This refers to the total amount of coal required for each coal mill to be disconnected.

[0064] S6. Calculate the theoretical capacity of each coal bunker and add the corresponding weight of coal to the corresponding coal bunker according to the theoretical capacity recommendation.

[0065] The S6 system enables precise control of the coal level in each coal bunker, ensuring that the bunker emptying time is largely consistent with the planned unit disconnection time. Specifically, the theoretical capacity of each coal bunker equals its theoretical coal requirement minus its actual coal inventory. When the theoretical coal requirement exceeds the actual coal inventory, simply add the recommended amount of coal to the bunker. When the theoretical coal requirement is less than the actual coal inventory, a positive bias can be added to the corresponding coal feeder command to adjust the coal feeder distribution, thus consuming the excess coal in advance. When the remaining coal level matches the required coal level, precise bunker burning is achieved.

[0066] S7. After the coal bunker is emptied, shut down the corresponding pulverizing system.

[0067] S8. Once the unit load drops below the first target load and there is no risk of exceeding environmental protection standards, the generator unit is disconnected.

[0068] To ensure full-load denitrification during shutdown, S8 specifies the planned disconnection time for the unit, controlling the disconnection time to be within 10 minutes before the hour.

[0069] S9. After the coal bunker corresponding to the last coal mill is emptied and purged, the boiler undergoes a MFT (Main Fuel Trip).

[0070] Example 2:

[0071] Based on Example 1, Example 2 of this application provides a more specific method for precise control of coal bunker levels during coal-fired boiler shutdown, including:

[0072] S1. One day before the planned disconnection of the unit, the coal level of each coal bunker will be controlled at the first target coal level and the second target coal level respectively; the first target coal level shall be lower than the second target coal level.

[0073] S2. Calculate the actual calorific value of the coal currently being fed into the furnace.

[0074] In S2, the calculation formula is as follows:

[0075]

[0076] Specifically, the unit load is P = 500MW, the turbine heat consumption is ΔH = 7895kJ / kWh, the vacuum correction factor is K = 1.02, and the boiler efficiency is η. gl=0.937, Pipeline efficiency η gd Substituting 0.99 and coal quantity C = 221 t / h into the formula for calculating the calorific value of the coal fed into the furnace, we can obtain the calculated calorific value Q of the coal currently fed into the furnace. js = 4691 kcal / kg.

[0077] S3. Calculate the actual coal inventory in each coal bunker.

[0078] Specifically, to calculate the mass of coal stored in the coal bunker, it is necessary to first calculate the corresponding volume of coal. To minimize errors in the volume of the cone section and accurately calculate the total volume of the cone section, based on the structural characteristics of the coal bunker, the cone section is divided into regions. Small truncated cones of uniform size are divided into separate regions, resulting in a total of 4 regions (see...). Figure 3 Then, the volume of each region is calculated using the formula for the volume of a frustum. Once the volume is obtained, the amount of coal stored in the coal bunker can be calculated based on the bulk density of the coal.

[0079] Based on the aforementioned volume and zoning of the coal bunker, if the actual coal level in the bunker is h, then:

[0080] 1) When 0 < h ≤ h1, the volume of coal in the coal bunker is:

[0081]

[0082] In the formula, S1 is the area of ​​the lower base:

[0083] In the formula, S is the cross-sectional area of ​​the platform at height h:

[0084] 2) When h1 < h ≤ (h1 + h2), the volume of coal in the coal bunker is:

[0085]

[0086] In the formula, S2 is the area of ​​the lower base:

[0087] In the formula, S is the cross-sectional area of ​​the platform at height h:

[0088] 3) When (h1+h2)<h≤(h1+h2+h3), the volume of coal in the coal bunker is:

[0089]

[0090] In the formula, S3 is the area of ​​the lower base:

[0091] In the formula, S is the cross-sectional area of ​​the platform at height h:

[0092] 4) When (h1+h2+h3)<h≤(h1+h2+h3+h4), the volume of coal in the coal bunker is:

[0093]

[0094] In the formula, S4 is the area of ​​the lower base:

[0095] In the formula, S is the cross-sectional area of ​​the platform at height h:

[0096] The above algorithm can be used to calculate the volume of coal stored at different heights, and then, based on the bulk density of coal of 0.85 t / m³, the volume can be calculated. 3 Then the coal quality of each coal bunker can be calculated.

[0097] S4. Set the shutdown sequence and shutdown load nodes for the coal mill.

[0098] For example, the shutdown sequence of the coal mills should be based on the relevant requirements for coal mill shutdown during the actual shutdown of the front and rear wall opposed boilers. The pulverizing system can be shut down in the order of E—C—B—D—A—F during the shutdown period. To ensure that no coal mill is overloaded during the shutdown period, the method was improved. The load nodes for the shutdown of the second to sixth coal mills are respectively: second load 450MW, third load 350MW, fourth load 250MW, fifth load 100MW, and sixth load 0MW.

[0099] S5. Calculate the theoretical coal demand of each pulverizing system based on the shutdown load curve.

[0100] S6. Calculate the theoretical capacity of each coal bunker and add the corresponding weight of coal to the corresponding coal bunker according to the theoretical capacity recommendation.

[0101] Specifically, the total coal quantity required by the coal bunkers corresponding to each pulverizing system in S5 needs to be calculated based on the corresponding load range and the load-coal quantity curve. The load-coal quantity curve correspondence diagram is shown below. Figure 2 As shown, the load-coal-quantity curve is the load-coal-quantity curve corresponding to the Phase I unit.

[0102] In addition, the shutdown load planning curve is as follows: Figure 4 As shown, the calculated calorific value of the coal fed into the furnace, 4691 kcal / kg, obtained in S2 above, yields a calorific value correction factor Kc = 1.023. After summarizing the above results, the recommended replenishment amount for each coal bunker can be output, as shown in Table 1 below:

[0103] Table 1 shows the coal bunker replenishment recommendations calculated from the shutdown load curves in the embodiments.

[0104]

[0105] Coal bunkers A, B, C, D, E, and F will have their coal added by 222t, 202t, 106t, 109t, 0t, and 207t respectively, according to the recommended increase.

[0106] S7. After the coal bunker is emptied, shut down the corresponding pulverizing system.

[0107] S8. Once the unit load drops below the first target load and there is no risk of exceeding environmental protection standards, the generator unit is disconnected.

[0108] For example, the first load is 50MW, and the unit disconnection time is 23:56.

[0109] S9. After the coal bunker corresponding to the last coal mill is emptied and purged, the boiler undergoes a MFT (Main Fuel Trip).

[0110] For example, the last coal mill F coal bunker empties at 0:03 on the second day, and the time from the unit disconnection to the emptying of the coal bunker is 7 minutes. The amount of coal consumed after disconnection is only 4t.

[0111] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

Claims

1. A method for precise control of coal bunker level during coal-fired boiler shutdown, characterized in that, include: S1. One day before the planned disconnection of the unit, the coal level of each coal bunker will be controlled at the first target coal level and the second target coal level, respectively. The first target coal level is lower than the second target coal level; S2. Calculate the actual calorific value of the coal currently being fed into the furnace; S3. Calculate the actual coal inventory in each coal bunker. S4. Set the shutdown sequence and shutdown load nodes for the coal mills; In S3, the formula for calculating the mass of coal stored in the coal bunker is: In the formula For coal density, This refers to the actual volume of coal calculated based on the coal bunker level h using the corresponding algorithm. The quality of coal stored in the coal bunker; S5. Calculate the theoretical coal demand of each coal bunker for each pulverizing system based on the shutdown load curve. In S5, the formula for calculating the theoretical coal requirement of the coal bunker is: In the formula, The amount of coal corresponding to the current load, in tons per hour (t / h). () represents the coal quantity function expression for different loads of the unit; The load of the current generating unit is expressed in MW. This represents the total amount of coal required by the unit for this load segment from time 0 to time t. The amount of coal at time t when the unit load is P, in t / h; S6. Calculate the theoretical capacity of each coal bunker and add the corresponding weight of coal to the corresponding coal bunker according to the theoretical capacity recommendation. S7. Stop the corresponding pulverizing system after the coal bunker is emptied. S8. Once the unit load drops below the first target load and there is no risk of exceeding environmental protection standards, the generator unit is disconnected from the grid. S9. After the coal bunker corresponding to the last coal mill is emptied and purged, the boiler main fuel trips.

2. The method for precise control of coal bunker level during coal-fired boiler shutdown as described in claim 1, characterized in that, In S1, when there are six coal mills, the coal bunker corresponding to the first coal mill is emptied in advance, and the coal level of the coal bunkers corresponding to the second and third coal mills is controlled at the first target coal level, and the coal level of the coal bunkers corresponding to the fourth, fifth and sixth coal mills is controlled at the second target coal level; the first coal mill is the first coal mill that is shut down during the unit shutdown process.

3. The method for precise control of coal bunker level during coal-fired boiler shutdown as described in claim 2, characterized in that, In S2, the formula for calculating the actual calorific value of the coal fed into the furnace is: In the formula, Unit load, in MW; This represents the heat consumption of the steam turbine under current load, expressed in kJ / kW·h. This is the correction factor for the turbine heat consumption caused by the unit vacuum under the current load; For boiler efficiency, % For pipeline efficiency, % The current coal consumption of the unit is expressed in tons per hour (t / h). The unit for calculating the calorific value of the coal fed into the furnace is kcal / kg.

4. The method for precise control of coal bunker level during coal-fired boiler shutdown as described in claim 3, characterized in that, In S4, when there are six coal mills, the first to sixth coal mills are defined according to the order of shutdown, and the load nodes of the second to sixth coal mills that are shut down are respectively designated as the second to sixth loads.

5. The method for precise control of coal bunker level during coal-fired boiler shutdown as described in claim 4, characterized in that, In S5, the theoretical coal demand calculated for each coal mill needs to be multiplied by a correction factor K. c K c =Q jh / Q js In the formula Q jh To verify the calorific value of coal, the unit is kcal / kg, Q js This represents the calorific value of the coal fed into the furnace, calculated in S2, in kcal / kg.

6. The method for precise control of coal bunker level during coal-fired boiler shutdown as described in claim 4, characterized in that, In S6, when the theoretical coal demand is greater than the actual coal storage, the recommended coal quantity needs to be added to this coal bunker. When the theoretical coal demand is less than the actual coal storage, the coal quantity distribution of the coal feeder is adjusted by adding a positive bias to the corresponding coal feeder coal quantity command, so as to consume the excess coal quantity in advance.

7. The method for precise control of coal bunker level during coal-fired boiler shutdown as described in claim 5, characterized in that, S8 specifies the planned disconnection time for the generating units, controlling the disconnection time to be within 10 minutes before the hour.

Images