A system and method for controlling thermal deviation of heating surfaces of boiler furnace and tail flue

Abstract

The present application discloses a system and method for controlling thermal deviation of a boiler furnace and a heating surface of a tail flue, comprising: an economizer, wherein the economizer comprises an inlet side and an outlet side, wherein the inlet side is connected to a water supply pipe, and the outlet side is connected to a downcomer distribution header, wherein the downcomer distribution header is connected to a plurality of lower water-cooled wall loops through a plurality of water supply pipes; wherein the lower water-cooled wall loop comprises a lower water-cooled wall lower header, a lower water-cooled wall tube screen and a lower water-cooled wall outlet header connected in sequence, wherein the lower water-cooled wall lower header comprises a plurality of the lower water-cooled wall loops, and the lower water-cooled wall lower headers correspond to the water supply pipes one by one; a water spray pipe is connected to the water supply pipe on the inlet side of the economizer, and a plurality of water spray branches are provided at the end of the water spray pipe to adjust the wall temperature of each lower water-cooled wall loop; the present application can completely solve the problem of thermal deviation of the water-cooled wall and the problem of thermal deviation of the heating surface of the tail flue.

Description

Technical Field

[0001] The present application belongs to the technical field of boilers in thermal power plants, and in particular relates to a system and method for controlling thermal deviations of heating surfaces of a boiler furnace and a tail flue. Background Art

[0002] In order to make full use of my country's large amount of anthracite in the field of thermal power generation, W-shaped flame boilers that can adapt to anthracite have been put into operation on a large scale, solving the problem of anthracite combustion in power station boilers and promoting great progress in the thermal power generation industry. In recent years, with the adjustment of the national energy structure, national energy-saving and consumption-reduction policies have been introduced one after another, and the requirements for energy conservation and emission reduction have continued to deepen. W-flame units are also developing in the direction of large capacity and high parameters, with parameters gradually increasing from subcritical to supercritical and ultra-supercritical, and the furnace cross-sectional dimensions are also increasing accordingly. At medium and low loads or when the mill is started and stopped, due to the partial operation of the burner and the change of heat load in a short period of time during the start-up and shutdown of the mill, the heat load distribution along the width of the lower furnace is uneven, the heat load of the area where the burner is put into operation is high, and the heat load of the area where the burner is exited is low, which is prone to a sharp rise in the wall temperature of the water-cooled wall of the lower furnace in a local or large area, or even overheating.

[0003] Since the thermal deviation of the water-cooled wall is a prominent problem in the running unit and has a great impact, in order to ensure the long-term safe and stable operation of the W boiler, the thermal deviation of the water-cooled wall should be solved first. However, it is difficult to completely solve the thermal deviation of the water-cooled wall with the existing technology, so it is also impossible to solve the thermal deviation of the heating surface of the tail flue. Summary of the invention

[0004] In view of the above problems, the embodiment of the present application provides a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue, so as to completely solve the problem of thermal deviation of the water-cooled wall and the problem of thermal deviation of the heating surface of the tail flue. The technical solution is as follows:

[0005] The first aspect of the present application provides a system for controlling thermal deviations of the heating surfaces of a boiler furnace and a rear flue, comprising: an economizer, wherein the economizer comprises an inlet side and an outlet side, wherein the inlet side is connected to a water supply pipe, and the outlet side is connected to a downcomer distribution header, and the downcomer distribution header is connected to a plurality of lower water-cooled wall circuits through a plurality of water supply pipes; wherein the lower water-cooled wall circuit comprises a lower water-cooled wall header, a lower water-cooled wall tube panel and a lower water-cooled wall outlet header connected in sequence, wherein the lower water-cooled wall header comprises a plurality of lower water-cooled wall circuits, and the lower water-cooled wall headers correspond one-to-one to the water supply pipes; a water spray pipe is connected to the water supply pipe on the inlet side of the economizer, and a plurality of water spray branches are provided at the end of the water spray pipe, and the water spray branches are connected one-to-one to the water supply pipes to adjust the wall temperature of each lower water-cooled wall circuit.

[0006] For example, in the thermal deviation control system of the boiler furnace and the tail flue heating surface provided in one embodiment, a high-pressure check valve is provided on each of the water supply pipes, and the connection point between the water spray branch pipe and the water supply pipe is located downstream of the high-pressure check valve to prevent the water flow in the water supply pipe from flowing back to the economizer through the water spray branch pipe.

[0007] For example, in the thermal deviation control system of the boiler furnace and the tail flue heating surface provided in one embodiment, a high-pressure regulating valve is provided on each of the water spray branches to adjust the water spray volume of the water spray branch.

[0008] For example, in the thermal deviation control system of the boiler furnace and tail flue heating surface provided in one embodiment, after the water flows into the lower header of the lower water-cooled wall, it enters the lower water-cooled wall outlet header through the lower water-cooled wall tube panel, and then enters the upper water-cooled wall inlet header through the intermediate mixing header, and then enters the upper water-cooled wall outlet header through the upper furnace water-cooled wall tube panel, and then enters the upper water-cooled wall outlet header through the water-cooled wall outlet mixing header, and finally enters the steam-water separator inlet pipe.

[0009] For example, in a system for controlling thermal deviation of the boiler furnace and the rear flue heating surface provided in one embodiment, two spaced-apart steam-water separators are provided on one side of the water-cooled wall outlet mixing header, which are a first steam-water separator and a second steam-water separator, and the steam-water separator inlet pipes include a first group of steam-water separator inlet pipes corresponding to the first steam-water separator and a second group of steam-water separator inlet pipes corresponding to the second steam-water separator, wherein a portion of the first group of steam-water separator inlet pipes is connected to the first steam-water separator, and another portion is connected to the second steam-water separator; a portion of the second group of steam-water separator inlet pipes is connected to the second steam-water separator, and another portion is connected to the first steam-water separator, so as to realize a partial cross-arrangement of the steam-water separator inlet pipes.

[0010] For example, in the thermal deviation control system of the boiler furnace and the tail flue heating surface provided in one embodiment, the first group of steam-water separator inlet pipes includes two groups, which are respectively located on both sides of the first steam-water separator, wherein a group of the first group of steam-water separator inlet pipes away from the second steam-water separator is connected to the first steam-water separator, and a group of the first group of steam-water separator inlet pipes close to the second steam-water separator is connected to the second steam-water separator; the second group of steam-water separator inlet pipes includes two groups, which are respectively located on both sides of the second steam-water separator, wherein a group of the second group of steam-water separator inlet pipes away from the first steam-water separator is connected to the second steam-water separator, and a group of the second group of steam-water separator inlet pipes close to the first steam-water separator is connected to the first steam-water separator.

[0011] For example, in the thermal deviation control system of the boiler furnace and the tail flue heating surface provided in one embodiment, the first group of steam-water separator inlet pipes includes six pipes, three pipes in each group, which are respectively located on both sides of the first steam-water separator, wherein the three pipes of the first group of steam-water separator inlet pipes away from the second steam-water separator are connected to the first steam-water separator, and the three pipes of the first group of steam-water separator inlet pipes close to the second steam-water separator are connected to the second steam-water separator; the second group of steam-water separator inlet pipes includes six pipes, three pipes in each group, which are respectively located on both sides of the second steam-water separator, wherein the three pipes of the second group of steam-water separator inlet pipes away from the first steam-water separator are connected to the second steam-water separator, and the three pipes of the second group of steam-water separator inlet pipes close to the first steam-water separator are connected to the first steam-water separator.

[0012] A second aspect of the present application provides a method for controlling a thermal deviation of a boiler furnace and a rear flue heating surface, comprising the following steps: measuring the maximum wall temperature and the average wall temperature at the outlet of each lower water-cooled wall circuit; comparing the maximum wall temperature at the outlet of each lower water-cooled wall circuit with a preset wall temperature alarm value; if the maximum wall temperature at the outlet of the lower water-cooled wall circuit exceeds the preset wall temperature alarm value, opening a high-pressure regulating valve on a water spray branch pipe of the lower water-cooled wall circuit until the maximum wall temperature at the outlet of the lower water-cooled wall circuit is lower than the wall temperature alarm value; if the maximum wall temperature at the outlet of the lower water-cooled wall circuit does not exceed the preset wall temperature alarm value, continuing to compare the average wall temperature at the outlet of the lower water-cooled wall circuit with a preset wall temperature lower limit value; if the average wall temperature at the outlet of the lower water-cooled wall circuit is lower than the preset wall temperature lower limit value, closing a high-pressure regulating valve on a water spray branch pipe of the lower water-cooled wall circuit until the maximum wall temperature at the outlet of each lower water-cooled wall circuit is between the preset wall temperature lower limit value and the wall temperature alarm value.

[0013] For example, in a method for controlling thermal deviation of the boiler furnace and tail flue heating surface provided in one embodiment, the adjustment amount of the high-pressure regulating valve each time it is opened or closed is a fixed value, which is 5% of the maximum flow of the high-pressure regulating valve.

[0014] For example, in a method for controlling thermal deviation of the boiler furnace and tail flue heating surface provided in one embodiment, the minimum time interval between two adjacent adjustments of the high-pressure regulating valve on each lower water-cooled wall circuit is 20 seconds.

[0015] The beneficial effect brought about by the system and method for controlling thermal deviation of the heating surface of the boiler furnace and the rear flue of the present application is that the present application introduces the low-temperature feed water before the economizer into the inlet of each lower water-cooled wall header through a water spray pipe and a water spray branch pipe, and utilizes the characteristic that the feed water temperature in the water spray pipe is slightly lower than the water temperature at the economizer outlet to cool down the circuit with high wall temperature in the lower water-cooled wall circuit, thereby solving the problem of overheating and thermal deviation of the lower water-cooled wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the steam-water flow in the boiler water wall;

[0018] Figure 2 yes Figure 1 A magnified view of part I;

[0019] Figure 3 yes Figure 1 A magnified view of Part II;

[0020] Figure 4 It is a logic diagram of the method for controlling thermal deviation of the boiler furnace and the tail flue heating surface of the present application.

[0021] Figure numerals: 1-downcomer distribution header, 2-economizer, 3-lower water-cooled wall tube panel, 4-lower water-cooled wall lower header, 5-water-cooled wall intermediate mixing header, 6-high-pressure check valve, 7-high-pressure regulating valve, 8-upper furnace, 9-lower furnace, 10-steam-water separator inlet pipe, 11-water supply pipe, 12-water spray pipe, 13-lower water-cooled wall outlet header, 14-upper water-cooled wall inlet header, 15-upper water-cooled wall outlet header, 16-water-cooled wall outlet mixing header, 17-steam-water separator, 18-low-temperature reheater, 19-low-temperature superheater, 20-upper furnace water-cooled wall tube panel, 21-inlet side, 22-outlet side-, 23-water supply pipe, 24-water spray branch pipe, 25-first steam-water separator, 26-second steam-water separator, 27-first group of steam-water separator inlet pipes, 28-second group of steam-water separator inlet pipes. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] When the W boiler is in medium or low load or when the mill is started and stopped, the heat load changes in a short period of time due to the partial operation of the burner and the start-up and shutdown of the mill, resulting in uneven heat load distribution along the width direction of the lower furnace. The heat load of the area where the burner is put into operation is high, and the heat load of the area where the burner is exited is low. It is easy to cause the wall temperature of the water-cooled wall of the lower furnace to rise sharply in a local or large area, or even overheat. The thermal deviation of the water-cooled wall of the lower furnace is alleviated through the middle mixing header of the water-cooled wall, but there is still a large deviation in the steam temperature of the water-cooled wall at the left and right upper furnace outlets. The steam temperature deviation may be aggravated after passing through the upper furnace. At present, the spatial arrangement position of the outlet pipe of the upper furnace water-cooled wall outlet header of the main W boiler is corresponding to the inlet pipe of the steam-water separator, that is, the steam on the left side of the water-cooled wall outlet header enters the steam-water separator on the left, and the steam on the right side of the water-cooled wall outlet header enters the steam-water separator on the right. The thermal deviation caused by the uneven heat absorption of the lower furnace still exists at the upper water-cooled wall and the steam-water separator outlet. The thermal deviation at the outlet of the steam-water separator causes thermal deviations in the ceiling pipe and the front and rear walls, and even further amplifies the thermal deviation. Thermal deviation is often accompanied by thermal stress. Excessive thermal deviation can cause cracks in water-wall fins, water-wall tubes, ceiling tubes, front and rear walls, and side wall corners due to thermal stress, and even lead to unplanned unit shutdown. In actual operation, the problem of cracks in the tail rear wall is more prominent.

[0025] The existing technology has conducted in-depth research on the problem of thermal deviation. In summary, the research is mainly divided into two directions: the flue gas side and the steam side. The flue gas side mainly focuses on strengthening the monitoring of the furnace flue gas temperature, better guiding the operation to adjust the furnace flue gas temperature deviation, and achieving the purpose of alleviating the thermal deviation of the water-cooled wall; the steam side mainly focuses on strengthening the uniformity of the steam-water flow distribution, reducing the flow deviation, and achieving the purpose of alleviating the thermal deviation of the furnace water-cooled wall and the rear heating surface. According to the current solutions, both the steam side and the flue gas side have certain limitations in solving the thermal deviation of the water-cooled wall and the rear heating surface. First, there is a lag and adjustment uncertainty from flue gas temperature monitoring to combustion adjustment, and the adjustment effect is greatly affected by the level of the operating personnel; secondly, the throttling shrinkage holes usually arranged on the steam side are prone to scaling, wear and even falling off. When the coal quality changes, the heat load distribution in the furnace and the steam-water flow distribution have poor adaptability, and the above method.

[0026] In view of this, the first aspect of the present application provides a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue, such as Figure 1-2 As shown, it includes: an economizer 2, the economizer 2 includes an inlet side 21 and an outlet side 22, the inlet side 21 is connected to a water supply pipe 23, the outlet side 22 is connected to a downcomer distribution header 1, and the downcomer distribution header 1 is connected to several lower water-cooled wall circuits through several water supply pipes 11; wherein the lower water-cooled wall circuit includes a lower water-cooled wall lower header 4, a lower water-cooled wall tube panel 3 and a lower water-cooled wall outlet header 13 connected in sequence, the lower water-cooled wall lower header 4 includes several to form several lower water-cooled wall circuits, and the lower water-cooled wall lower header 4 corresponds to the water supply pipe 11 one by one; a water spray pipe 12 is connected to the water supply pipe 23 on the inlet side 21 of the economizer 2, and several water spray branches 24 are provided at the end of the water spray pipe 12, and the water spray branches are connected to the water supply pipe 11 one by one to adjust the wall temperature of each lower water-cooled wall circuit. According to the above embodiment, the present application introduces the low-temperature feed water before the economizer 2 into the inlet of each lower water-cooled wall header 4 through the water spray pipe 12 and the water spray branch pipe 24, and utilizes the characteristic that the feed water temperature in the water spray pipe 12 is slightly lower than the outlet water temperature of the economizer 2 to cool the circuit with high wall temperature in the lower water-cooled wall circuit, thereby solving the problem of overheating and thermal deviation of the lower water-cooled wall.

[0027] For example, in a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue provided in one embodiment, Figure 2 As shown, a high-pressure check valve 6 is provided on each of the water supply pipes 11, and the connection point between the water spray branch pipe 24 and the water supply pipe 11 is located downstream of the high-pressure check valve 6 to prevent the water flow in the water supply pipe 11 from flowing back to the economizer 2 through the water spray branch pipe 24.

[0028] For example, in a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue provided in one embodiment, Figure 2As shown, a high-pressure regulating valve 7 is provided on each of the water spraying branches 24 to adjust the water spraying amount of the water spraying branch 24, thereby cooling the circuit with a relatively high wall temperature in the lower water-cooled wall circuit.

[0029] For example, in a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue provided in one embodiment, Figure 1 As shown, after the water flows into the lower water-cooled wall lower header 4, it passes through the lower water-cooled wall tube panel 3 and enters the lower water-cooled wall outlet header 13, then passes through the intermediate mixing header 5 and enters the upper water-cooled wall inlet header 14, then passes through the upper furnace water-cooled wall tube panel 20 and enters the upper water-cooled wall outlet header 15, then passes through the water-cooled wall outlet mixing header 16 and enters the steam-water separator inlet pipe 10, and finally enters the steam-water separator 17.

[0030] For example, in a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue provided in one embodiment, Figure 3 As shown, two steam-water separators 17 are arranged at intervals on one side of the water-cooled wall outlet mixing header 16, which are a first steam-water separator 25 and a second steam-water separator 26 respectively. The steam-water separator inlet pipe 10 includes a first group of steam-water separator inlet pipes 27 corresponding to the first steam-water separator 25 and a second group of steam-water separator inlet pipes 28 corresponding to the second steam-water separator 26, wherein a portion of the first group of steam-water separator inlet pipes 27 is connected to the first steam-water separator 25, and another portion is connected to the second steam-water separator 26; a portion of the second group of steam-water separator inlet pipes 28 is connected to the second steam-water separator 26, and another portion is connected to the first steam-water separator 25, so as to realize a partial cross arrangement of the steam-water separator inlet pipes 10. According to the above embodiment, the present application cross-arranges part of the steam-water separator inlet pipes from the water-cooled wall outlet mixing header 16 to the inlet of the two spaced-apart steam-water separators 17, and cross-introduces part of the steam-water separator inlet pipes from the water-cooled wall outlet mixing header 16 to the steam-water separator inlet on the adjacent side, so that the steam with thermal deviation is fully mixed in the steam-water separator, thereby reducing the steam deviation at the outlets of the first steam-water separator 25 and the second steam-water separator 26 arranged at two intervals.

[0031] Furthermore, in order to ensure the mixing effect of steam with thermal deviation in the steam-water separator, no less than half of the pipes in the first group of steam-water separator inlet pipes 27 are connected to the first steam-water separator 25, and no less than half of the pipes in the second group of steam-water separator inlet pipes 28 are connected to the second steam-water separator 26.

[0032] Since the water-cooled wall outlet mixing header 16 is relatively long, the water and steam entering the water-cooled wall outlet mixing header 16 from different upper water-cooled wall outlet headers 15 are mixed for a short time in the water-cooled wall outlet mixing header 16, and enter the steam-water separator 17 through the steam-water separator introduction pipe 10 before they are completely mixed and heat exchanged, which easily causes thermal deviation between water and steam in the two steam-water separators, i.e., the first steam-water separator 25 and the second steam-water separator 26. In the present application, the steam-water separator introduction pipe 10 is partially cross-arranged, and the water and steam on different sides of the water-cooled wall outlet mixing header 16 enter the same steam-water separator. The steam with thermal deviation is fully mixed in the steam-water separator, and the steam deviation at the outlets of the first steam-water separator 25 and the second steam-water separator 26 arranged at intervals is reduced, so as to completely solve the problem of thermal deviation of steam temperature on both sides of the water-cooled wall outlet, so that the steam temperature at the water-cooled wall outlet is evenly distributed, and there is no thermal deviation in the steam temperature flowing through the ceiling pipe through the heating surface of the rear flue wall. This connection method can effectively eliminate the thermal deviation of the wall pipe, and also eliminate the thermal stress on both sides of the rear wall, solving the problem of stress deformation or leakage of the rear wall pipe, because the pipe without tensile stress will not be tensilely deformed or leaked.

[0033] For example, in a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue provided in one embodiment, Figure 3 As shown, the first group of steam-water separator inlet pipes 27 include two groups, which are respectively located on both sides of the first steam-water separator 25, wherein a group of the first group of steam-water separator inlet pipes 27 far away from the second steam-water separator 26 is connected to the first steam-water separator 25, and a group of the first group of steam-water separator inlet pipes 27 close to the second steam-water separator 26 is connected to the second steam-water separator 26; the second group of steam-water separator inlet pipes 28 include two groups, which are respectively located on both sides of the second steam-water separator 26, wherein a group of the second group of steam-water separator inlet pipes 28 far away from the first steam-water separator 25 is connected to the second steam-water separator 26, and a group of the second group of steam-water separator inlet pipes 28 close to the first steam-water separator 25 is connected to the first steam-water separator 25, so as to realize the partial cross arrangement of the steam-water separator inlet pipes 10.

[0034] For example, in a system for controlling thermal deviation of the heating surface of the boiler furnace and the tail flue provided in one embodiment, Figure 3As shown, the first group of steam-water separator inlet pipes 27 includes six pipes, three pipes in each group, which are respectively located on both sides of the first steam-water separator 25, wherein the three pipes of the first group of steam-water separator inlet pipes 27 far away from the second steam-water separator 26 are connected to the first steam-water separator 25, and the three pipes of the first group of steam-water separator inlet pipes 27 close to the second steam-water separator 26 are connected to the second steam-water separator 26; the second group of steam-water separator inlet pipes 28 includes six pipes, three pipes in each group, which are respectively located on both sides of the second steam-water separator 26, wherein the three pipes of the second group of steam-water separator inlet pipes 28 far away from the first steam-water separator 25 are connected to the second steam-water separator 26, and the three pipes of the second group of steam-water separator inlet pipes 28 close to the first steam-water separator 25 are connected to the first steam-water separator 25.

[0035] Specifically, the upper water-cooled wall outlet header 15 includes a water-cooled wall outlet header on the front wall, a water-cooled wall outlet header on the right wall, a water-cooled wall outlet header on the left wall and a water-cooled wall outlet header on the rear wall. The water-cooled wall outlet header on the front wall and the water-cooled wall outlet header on the right wall are connected to the first steam-water separator 25, and the water-cooled wall outlet header on the left wall and the water-cooled wall outlet header on the rear wall are connected to the second steam-water separator 26.

[0036] The second aspect of the present application provides a method for controlling the thermal deviation of the heating surface of the boiler furnace and the tail flue, such as Figure 4 As shown, the method comprises the following steps: numbering a plurality of lower water-cooled wall circuits as 1 to N, measuring the maximum wall temperature and the average wall temperature at the outlet of the N lower water-cooled wall circuits; comparing the maximum wall temperature at the outlet of each lower water-cooled wall circuit with a preset wall temperature alarm value, such as the maximum wall temperature and the average wall temperature at the outlet of the i-th lower water-cooled wall circuit, (1≤i≥N); if the maximum wall temperature at the outlet of the lower water-cooled wall circuit exceeds the preset wall temperature alarm value, opening the high-pressure regulating valve 7 on the water spray branch pipe 24 of the lower water-cooled wall circuit until the maximum wall temperature at the outlet of the i-th lower water-cooled wall circuit exceeds the preset wall temperature alarm value. The maximum wall temperature at the outlet of the lower water-cooled wall loop is lower than the wall temperature alarm value; if the maximum wall temperature at the outlet of the lower water-cooled wall loop does not exceed the preset wall temperature alarm value, then continue to compare the average wall temperature at the outlet of the lower water-cooled wall loop with the preset wall temperature lower limit value; if the average wall temperature at the outlet of the lower water-cooled wall loop is lower than the preset wall temperature lower limit value, then close the high-pressure regulating valve 7 on the water spray branch pipe 24 of the lower water-cooled wall loop; until the maximum wall temperature at the outlet of each lower water-cooled wall loop is between the preset wall temperature lower limit value and the wall temperature alarm value.

[0037] For example, in a method for controlling thermal deviation of the boiler furnace and tail flue heating surface provided in one embodiment, the adjustment amount of the high-pressure regulating valve 7 each time it is opened or closed is a fixed value, which is 5% of the maximum flow of the high-pressure regulating valve 7.

[0038] For example, in a method for controlling thermal deviation of the boiler furnace and the rear flue heating surface provided in one embodiment, the minimum time interval between two adjacent adjustments of the high-pressure regulating valve 7 on each lower water-cooled wall circuit is 20s, thereby preventing over-adjustment of the cooling water volume and frequent adjustment of the high-pressure regulating valve 7 due to wall temperature fluctuations, thereby improving the service life of the high-pressure regulating valve 7 and the safety of the water spray cooling system.

[0039] Although the embodiments of the present application have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A method for treating thermal deviation of heating surfaces of boiler furnace and tail flue, characterized in that: include: An economizer, the economizer comprising an inlet side and an outlet side, the inlet side being connected to a water supply pipe, the outlet side being connected to a downcomer distribution header, the downcomer distribution header being connected to a plurality of lower water-cooled wall circuits through a plurality of water supply pipes; wherein the lower water-cooled wall circuit comprises a lower water-cooled wall lower header, a lower water-cooled wall tube panel and a lower water-cooled wall outlet header connected in sequence, the lower water-cooled wall lower header comprises a plurality of lower water-cooled wall circuits, and the lower water-cooled wall lower headers correspond to the water supply pipes one by one; a water spray pipe is connected to the water supply pipe on the inlet side of the economizer, a plurality of water spray branches are provided at the end of the water spray pipe, the water spray branches are connected to the water supply pipe One-to-one connection is used to adjust the wall temperature of each lower water-cooled wall circuit. After the water flows into the lower header of the lower water-cooled wall, it passes through the lower water-cooled wall tube panel and enters the lower water-cooled wall outlet header, then passes through the intermediate mixing header and enters the upper water-cooled wall inlet header, then passes through the upper furnace water-cooled wall tube panel and enters the upper water-cooled wall outlet header, then passes through the water-cooled wall outlet mixing header and enters the steam-water separator inlet pipe, and finally enters the steam-water separator. Two steam-water separators arranged at intervals are provided on one side of the water-cooled wall outlet mixing header, which are the first steam-water separator and the second steam-water separator. The steam-water separator inlet pipe includes a first group of steam-water separator inlet pipes corresponding to the first steam-water separator. a portion of the first group of steam-water separator inlet pipes connected to the first steam-water separator, and another portion connected to the second steam-water separator; a portion of the second group of steam-water separator inlet pipes connected to the second steam-water separator, and another portion connected to the first steam-water separator, so as to realize a partial cross arrangement of the steam-water separator inlet pipes, measure the maximum wall temperature and the average wall temperature at the outlet of each lower water-cooled wall circuit; compare the maximum wall temperature at each outlet of the lower water-cooled wall circuit with a preset wall temperature alarm value; if the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the ..., the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature at the outlet of the lower water-cooled wall circuit is greater than the preset wall temperature alarm value, the maximum wall temperature If the high wall temperature exceeds the preset wall temperature alarm value, the high-pressure regulating valve on the water spray branch of the lower water-cooled wall circuit is opened until the maximum wall temperature at the outlet of the lower water-cooled wall circuit is lower than the wall temperature alarm value; if the maximum wall temperature at the outlet of the lower water-cooled wall circuit does not exceed the preset wall temperature alarm value, the average wall temperature at the outlet of the lower water-cooled wall circuit continues to be compared with the preset wall temperature lower limit value; if the average wall temperature at the outlet of the lower water-cooled wall circuit is lower than the preset wall temperature lower limit value, the high-pressure regulating valve on the water spray branch of the lower water-cooled wall circuit is closed; until the maximum wall temperature at the outlet of each lower water-cooled wall circuit is between the preset wall temperature lower limit value and the wall temperature alarm value.

2. The method for treating thermal deviation of heating surfaces of boiler furnace and tail flue according to claim 1 is characterized in that: A high-pressure check valve is provided on each of the water supply pipes, and the connection point between the water spray branch pipe and the water supply pipe is located downstream of the high-pressure check valve to prevent the water flow in the water supply pipe from flowing back to the economizer through the water spray branch pipe.

3. The method for treating thermal deviation of heating surfaces of boiler furnace and tail flue according to claim 2 is characterized in that: A high-pressure regulating valve is provided on each of the water spraying branches to adjust the water spraying amount of the water spraying branch.

4. The method for treating thermal deviation of heating surfaces of boiler furnace and tail flue according to claim 1, characterized in that: The first group of steam-water separator inlet pipes includes two groups, which are respectively located on both sides of the first steam-water separator, wherein a group of the first group of steam-water separator inlet pipes far away from the second steam-water separator is connected to the first steam-water separator, and a group of the first group of steam-water separator inlet pipes close to the second steam-water separator is connected to the second steam-water separator; the second group of steam-water separator inlet pipes includes two groups, which are respectively located on both sides of the second steam-water separator, wherein a group of the second group of steam-water separator inlet pipes far away from the first steam-water separator is connected to the second steam-water separator, and a group of the second group of steam-water separator inlet pipes close to the first steam-water separator is connected to the first steam-water separator.

5. The method for treating thermal deviation of heating surfaces of boiler furnace and tail flue according to claim 4 is characterized in that: The first group of steam-water separator inlet pipes includes six pipes, three pipes in each group, which are respectively located on both sides of the first steam-water separator, wherein the three pipes in the first group of steam-water separator inlet pipes far away from the second steam-water separator are connected to the first steam-water separator, and the three pipes in the first group of steam-water separator inlet pipes close to the second steam-water separator are connected to the second steam-water separator; the second group of steam-water separator inlet pipes includes six pipes, three pipes in each group, which are respectively located on both sides of the second steam-water separator, wherein the three pipes in the second group of steam-water separator inlet pipes far away from the first steam-water separator are connected to the second steam-water separator, and the three pipes in the second group of steam-water separator inlet pipes close to the first steam-water separator are connected to the first steam-water separator.

6. The method for treating thermal deviation of heating surfaces of boiler furnace and tail flue according to claim 1, characterized in that: The adjustment amount of the high-pressure regulating valve for opening or closing each time is a fixed value, and is 5% of the maximum flow of the high-pressure regulating valve.

7. The method for treating thermal deviation of heating surfaces of boiler furnace and tail flue according to claim 1, characterized in that: The minimum time interval between two adjacent adjustments of the high-pressure regulating valve on each lower water-cooled wall circuit is 20s.

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