Method for adjusting combustion of wall type tangentially fired boiler with double-in double-out steel ball mill

Abstract

The application discloses a wall type tangential boiler combustion adjustment test method of double-inlet and double-outlet steel ball mill, which comprises the following steps: setting a constraint index, testing whether the constraint index exceeds an alarm value, and if so, performing differentiated adjustment of air distribution; testing the primary air speed in the primary air pipe at the outlet of each coal mill, testing whether the primary air speed deviation at the outlet of the same coal mill is within an allowable range, and if not, performing adjustment; sampling and analyzing the coal powder in the primary air pipe at the outlet of each coal mill, testing whether the coal powder fineness and the coal powder quantity distribution on the single side are within the design range and the allowable range, and if not, performing adjustment. In the application, the boiler is subjected to combustion adjustment, the effect is remarkable, the uniformity of the furnace combustion is obviously improved, the wall temperature of each level of the heating surface of the boiler is within a safe range, the left and right side steam temperatures at the outlet of the boiler reach the design value, and the combination of the coal mills is more flexible during low load.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal-fired thermal power generating units, and particularly relates to a wall type tangentially fired boiler combustion adjustment test method configured with double-inlet and double-outlet steel ball mills. BACKGROUND

[0002] By the end of 2021, China has realized more than 1 billion kilowatts of ultra-low emission coal-fired power generating units, about 1 billion kilowatts of coal-fired power plant boilers, and about 1 billion kilowatts of circulating fluidized bed boilers in power plants. From the classification of combustion organization form, coal-fired boilers mainly include tangential combustion, front and back wall opposite combustion, and W-type combustion. Among them, tangential combustion can be further divided into angle type tangential combustion and wall type tangential combustion.

[0003] After the supercritical boiler designed by wall type tangential combustion is put into operation, there is a common problem of large deviation of boiler steam temperature outlet left and right sides. The main reason is that the wall type tangential boiler has a large imaginary tangential diameter and inherent residual rotation, and the unevenness of wind and powder combustion in the furnace is easy to have a large impact on the boiler outlet steam temperature. The unevenness of combustion in the furnace will be more prominent at low load, which seriously affects the flexibility of the coal mill combination and the economic and safe operation of the unit. However, at present, there is a lack of an effective adjustment method on site.

[0004] The above information disclosed in the background section is only used to strengthen the understanding of the background of the present disclosure, so it can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] In order to solve the technical problems existing in the prior art, the purpose of the present application is to provide a wall type tangential boiler combustion adjustment test method configured with double-inlet and double-outlet steel ball mills.

[0006] In order to achieve the above-mentioned purpose and achieve the above-mentioned technical effect, the technical solution adopted by the present application is as follows:

[0007] The wall type tangential boiler combustion adjustment test method configured with double-inlet and double-outlet steel ball mills comprises the following steps:

[0008] Setting a constraint index, checking whether the constraint index exceeds an alarm value, and if it exceeds the alarm value, performing differentiated adjustment of air distribution;

[0009] Testing the primary air speed in the primary air pipe outlet of each coal mill, checking whether the primary air speed deviation of the same coal mill outlet is within the allowable range, and if it is not within the allowable range, adjusting it;

[0010] Sampling and analyzing the coal powder in the primary air pipe outlet of each coal mill, detecting whether the unilateral pipe coal powder fineness and coal powder quantity distribution are within the design range and the allowable range, and if they are not within the design range and the allowable range, adjusting them.

[0011] Further, the constraint indexes include the highest wall temperature points of the front and back walls of the water wall, the highest wall temperature points of the left and right walls of the water wall, the highest wall temperature points of the screen superheater, the highest wall temperature points of the last-stage superheater, and the highest wall temperature points of the last-stage reheater; and then the target indexes are set, i.e., the steam temperature at the outlet of the superheater and the steam temperature at the outlet of the reheater.

[0012] Further, if the wall temperature of the water wall, the screen superheater, the last-stage superheater, the last-stage reheater is high and the steam temperature at the outlet of the boiler is large, the opening degrees of the burnout air dampers are adjusted one by one, and the opening degrees are set to change from 20%, 40%, 60%, 80% and 100% one by one, so as to seek a suitable opening degree of the damper.

[0013] Further, if the wall temperature of the water wall, the screen superheater, the last-stage superheater, the last-stage reheater is high and the steam temperature at the outlet of the boiler is large, the opening degrees of the burnout air dampers are adjusted one by one, and the opening degrees are set to change from 20%, 40%, 60%, 80% and 100% one by one, so as to seek a suitable opening degree of the damper.

[0014] Further, if the deviation of the primary air speed exceeds the allowable range, the adjustable orifice at the outlet of the coal mill is adjusted to reduce the deviation value, and the principle of adjustment is that the adjustable orifice at the outlet of the primary air pipe with the lowest speed is first opened, and then the adjustable orifice at the outlet of the primary air pipe with the highest speed is closed, so as to keep the deviation of the speed of each primary air pipe within 10% as much as possible.

[0015] Further, if the one-side tube coal fineness is not within the design range, the one-side coal fineness of each coal mill is adjusted by adjusting the one-side folding baffle of the coal mill, and when the coal fineness reaches the requirement, if the output of the coal mill cannot meet the requirement, steel balls are appropriately added.

[0016] Further, according to the deviation of the coal fineness in the one-side primary air pipe at the outlet of the coal mill, the one-side coal fineness distributor at the outlet of the coal mill is adjusted one by one, so as to reduce the deviation of the coal fineness in the primary air pipe at the outlet of the coal mill, and keep the deviation of the coal fineness within 10% as much as possible; after the one-side coal fineness distributor is adjusted, the primary air speed at the outlet of the coal mill is measured again, so as to keep the deviation of the speed of each primary air pipe within 10% as much as possible.

[0017] Compared with the prior art, the method has the beneficial effects that:

[0018] The method for adjusting the combustion of the wall-type tangential boiler with the double-inlet and double-outlet steel ball mill is disclosed, the boiler is adjusted in combustion, the effect is remarkable, the uniformity of the furnace combustion is obviously improved, the wall temperature of each stage of the heating surface of the boiler is within the safety range, the left and right steam temperatures at the outlet of the boiler reach the design values, and the combination of the coal mills is more flexible during low load. DETAILED DESCRIPTION

[0019] The present application will be described in detail below so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly defined.

[0020] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0021] In order to solve the problem of large deviation of left and right boiler outlet steam temperature of wall type tangentially fired boiler, the application discloses a wall type tangentially fired boiler combustion adjustment test method with double-inlet and double-outlet steel ball mill, first sets the following constraint indexes: the highest point of water wall front and back wall temperature, the highest point of water wall left and right wall temperature, the highest point of screen superheater wall temperature, the highest point of last stage superheater wall temperature, the highest point of last stage reheater wall temperature; then sets the target indexes: superheater outlet steam temperature, reheater outlet steam temperature. In order to make the constraint indexes not exceed the alarm value, the target indexes are within the design value allowable change range (±5℃). The method specifically comprises the following steps:

[0022] (1) In the running habit operation condition, the boiler heating surface wall temperature and the boiler outlet steam temperature deviation are understood.

[0023] (2) The primary air speed in the primary air pipe at the outlet of each coal mill is tested, and whether the primary air speed deviation of the four powder pipes at the outlet of the same coal mill is within the allowable range (deviation 10%) is tested.

[0024] (3) The coal powder in the primary air pipe at the outlet of the four powder pipes of the coal mill is sampled, and the coal powder fineness on one side (1 / 3 powder pipe or 2 / 4 powder pipe) is analyzed and tested, and whether the coal powder fineness R200 and R90 is within the design range is tested.

[0025] (4) The coal powder sample at the outlet of the coal mill is weighed, and whether the distribution of the coal powder amount (1 / 3 powder pipe or 2 / 4 powder pipe) of the primary air pipe on one side at the outlet of the same coal mill is within the allowable range (deviation 10%) is tested.

[0026] (5) If the primary air speed deviation exceeds the allowable range (deviation 10%), the adjustable contraction hole at the outlet of the coal mill is adjusted to reduce the deviation value, and the principle of adjustment is to preferentially open the adjustable contraction hole of the pipe with the lowest air speed, and then close the adjustable contraction hole of the pipe with the highest air speed. The primary air speed deviation of each pipe is kept within 10%, and preferably within 5%.

[0027] (6) According to the deviation of the pulverized coal quantity in the single-sided primary air pipe at the outlet of the coal mill (No. 1 / 3 or No. 2 / 4 pulverized coal pipe), adjust the single-sided pulverized coal distributor of the coal mill one by one, reduce the deviation of the pulverized coal quantity in the primary air pipe at the outlet of the coal mill, and try to keep the deviation of the single-sided pulverized coal quantity (No. 1 / 3 or No. 2 / 4 pulverized coal pipe) within 10%.

[0028] (7) After adjusting the single-sided pulverized coal distributor, considering that the change of the pulverized coal quantity distribution will affect the primary air speed, the primary air speed at the outlet of the coal mill needs to be measured again, and try to keep the deviation of the air speed of each primary air pipe within 10%, preferably within 5%.

[0029] (8) Adjust the fineness of the pulverized coal to keep it within the design range, and adjust the single-sided deflection baffle of the coal mill to achieve the adjustment of the single-sided pulverized coal fineness of each coal mill.

[0030] (9) When analyzing the fineness of the pulverized coal, mix the pulverized coal samples from the single-sided outlet (No. 1 / 3 or No. 2 / 4 pulverized coal pipe) of the coal mill and analyze them, which facilitates the differential adjustment of the deflection door baffle of the corresponding single side.

[0031] (10) When the fineness of the pulverized coal meets the requirements, if the output of the coal mill does not meet the requirements, appropriate steel balls can be added according to the site conditions.

[0032] (11) After completing the above adjustment steps of the coal mill, the following adjustment of the secondary air damper opening of the boiler is performed.

[0033] (12) Considering the wall type tangential combustion boiler, which is prone to residual rotation, in general, the burnout air horizontal swing angle is adjusted to the maximum position of the reverse cut first, and the residual rotation of the flue gas at the outlet of the furnace is eliminated as much as possible.

[0034] (13) If the wall temperature of the water wall, the screen-type superheater, the final-stage superheater, and the final-stage reheater is too high, and the outlet steam temperature of the boiler deviates too much, the burnout air damper opening needs to be adjusted one by one, starting from No. 1, No. 2, No. 3, and No. 4, respectively, and changing from 20%, 40%, 60%, 80%, and 100% respectively, and then performing differential adjustment to find the appropriate damper opening.

[0035] (14) The auxiliary air damper preferably adopts equal air distribution or positive pagoda air distribution, and the fuel air adopts the same opening control as the adjacent auxiliary air, which is convenient for operation.

[0036] (15) If the water-cooled wall, screen superheater, last-stage superheater, last-stage reheater still has high wall temperature and large deviation of boiler outlet steam temperature, refer to the adjustment method of the overfire air damper opening degree, adjust from No. 1 corner, No. 2 corner, No. 3 corner and No. 4 corner in turn, and change each corner opening degree from 20%, 40%, 60%, 80% and 100% respectively, adjust the auxiliary air damper opening degree (FF / EF / ) respectively, combine and adjust differently, and seek the appropriate opening degree.

[0037] (16) Test and verify the boiler heating surface wall temperature and steam temperature under high, medium and low load conditions respectively, and check the universality of the air distribution mode law.

[0038] (17) Test and verify the boiler heating surface wall temperature and steam temperature for different coal grinding combinations respectively, and check the flexibility of different grinding combinations and the universality of the air distribution mode law.

[0039] (18) Obtain the optimized condition recommended operation mode through the above different load and different grinding combination verification, and test the wall temperature of each stage heating surface and the boiler outlet steam temperature under the optimized condition.

[0040] Example 1

[0041] A supercritical 600MW unit is configured with a wall type tangential combustion boiler, which is matched with 6 double-in double-out coal mills, and 4 pulverized coal pipes at the outlet of a single coal mill correspond to a layer of burners. Since being put into operation, the problem of large deviation of boiler outlet left and right side steam temperature often occurs, and the coal mill combination mode is not flexible during low load, which seriously affects the safe and economic operation of the power plant unit. Therefore, the wall type tangential combustion boiler is subjected to combustion adjustment by using the wall type tangential combustion boiler combustion adjustment test method provided by the present application, and the adjustment steps include:

[0042] (1) Test the coal pulverizing system

[0043] The test results of the primary air speed at the outlet of the coal mill are shown in Table 1, the test results of the coal powder amount distribution in the primary air pipe at the outlet of the coal mill are shown in Table 2, and the test results of the coal powder fineness in the primary air pipe at the outlet of the coal mill are shown in Table 3.

[0044] Table 1

[0045]

[0046]

[0047] Table 2

[0048]

[0049]

[0050] Table 3

[0051]

[0052] From the results of the coal mill bottoming test, it can be seen that:

[0053] The wind speed deviation between the six coal mill outlet four powder pipes is large, and the adjustable orifice on the coal mill powder pipe needs to be adjusted to make the wind speed deviation between each powder pipe within a reasonable range. The coal fineness R 90 of the mill is designed to be 22.5%, and under the condition of capacity wind opening 40%, there is coal fineness R 90 greater than 22.5% in A and D mills, which needs to be adjusted. The coal powder distribution greater than 10% needs to be adjusted according to the subsequent measurement.

[0054] The test results after adjustment are as follows:

[0055] Table 4 is the test results of the primary air speed at the outlet of the coal mill after adjustment.

[0056] Table 4

[0057]

[0058]

[0059] Table 5 is the test results of the coal powder distribution in the primary air pipe at the outlet of the coal mill after adjustment.

[0060] Table 5

[0061]

[0062] Table 6 is the results of coal fineness in the primary air pipe at the outlet of the coal mill after adjustment.

[0063] Table 6

[0064]

[0065]

[0066] Table 7 is the opening comparison table before and after the adjustment of the coal mill.

[0067] Table 7

[0068]

[0069] By adjusting the adjustable orifice of the coal mill, adjusting the baffle of the turning door and adjusting the coal powder distributor, the deviation of the air velocity between the six coal mills is controlled within ±10%, ensuring the uniformity of the overall primary air velocity. The deviation of the powder quantity between the two powder pipes on one side of the coal mill is controlled within ±10%, ensuring the uniformity of the coal powder distribution. Through the differential adjustment test of the baffle of the turning door on one side of the coal mill, the coal powder fineness R 90 of the coal mill is about 22.8%, and the coal powder fineness R 200 of the coal mill decreases.

[0070] Check and cut the overfire air to the fully reverse position, and then conduct special adjustment on the secondary air distribution opening.

[0071] From the equal air distribution, the optimal air distribution mode at 100%, 75% and 50% load is obtained through differential adjustment of the air distribution.

[0072] Table 8 is the optimal air distribution mode at 100% load.

[0073] Table 8

[0074]

[0075] Table 9 is the optimal air distribution mode at 75% load.

[0076] Table 9

[0077]

[0078]

[0079] Table 10 is the optimal air distribution mode at 50% load.

[0080] Table 10

[0081]

[0082] Through the above special adjustment of the coal mill and special adjustment of the air distribution, the problem of large deviation of the steam temperature on the left and right sides of the boiler outlet is solved, and the problem of inflexible combination of the coal mill is solved.

[0083] Due to the limitation of the deviation of the main reheat steam temperature on both sides, before adjustment, the boiler mill combination mode is relatively single. At medium load, there is only one or two conventional mill combination (stop A mill, run BCDEF mill; or stop D mill, ABCEF mill), and at low load, there is only one mill combination (stop AD mill, run BCEF mill), which seriously limits the flexibility of the unit operation and seriously affects the safe and economic operation of the unit.

[0084] After special adjustment, the combination operation mode of the low and medium load is more flexible, and 6 kinds of mill combination modes are realized under the medium load, i.e. 6 mills stop 1 mill; 3 kinds of mill combination modes are realized under the low load, i.e. operation of BCEF mill (stop AD mill), BCDF mill (stop AE mill) and BCDE mill (stop AF mill), and the flexibility of the mill combination of the unit operation is greatly improved.

[0085] For example, when the operator attempts to stop the F mill before the boiler combustion adjustment test is performed, the deviation of the outlet steam temperature of the last stage superheater of the boiler reaches 62℃, which seriously affects the safe operation of the unit and limits the flexibility of the mill combination. After the combustion adjustment, not only the F mill can be normally stopped, but also the deviation of the outlet steam temperature of the last stage superheater of the boiler is about 5℃.

[0086] The parts or structures not specifically described in the present application can adopt the prior art or existing products, which will not be described here.

[0087] The above description is only an embodiment of the present application, and does not limit the patent range of the present application, and any equivalent structure or equivalent process transformation using the content of the present application specification, or direct or indirect application in other related technical fields, are also included in the patent protection range of the present application.

Claims

1. A method for testing the combustion adjustment of a wall-fired tangentially fired boiler equipped with a double-in double-out ball mill, characterized in that, The method comprises the following steps: Setting a constraint index, checking whether the constraint index exceeds an alarm value, and if so, making differentiated adjustment of air distribution; Testing the primary air speed in the primary air pipe at the outlet of each coal mill, checking whether the primary air speed deviation at the outlet of the same coal mill is within the allowable range, and if not, making adjustment; Sampling and analyzing the coal powder in the primary air pipe at the outlet of each coal mill, checking whether the coal powder fineness and the coal powder quantity distribution on the single side are within the design range and the allowable range, and if not, making adjustment; The constraint index comprises the highest wall temperature of the front and rear water-cooled walls, the highest wall temperature of the left and right water-cooled walls, the highest wall temperature of the screen-type superheater, the highest wall temperature of the last-stage superheater, and the highest wall temperature of the last-stage reheater; then setting a target index: the superheater outlet steam temperature and the reheater outlet steam temperature; If the wall temperature of the water-cooled wall, the screen-type superheater, the last-stage superheater, and the last-stage reheater is too high and the boiler outlet steam temperature deviation is large, the burnout air door opening degree is adjusted one by one, the opening degree is set to change from 20%, 40%, 60%, 80%, and 100% one by one, and the appropriate air door opening degree is sought; If the wall temperature of the water-cooled wall, the screen-type superheater, the last-stage superheater, and the last-stage reheater is still too high and the boiler outlet steam temperature deviation is large, the burnout air door opening degree is adjusted one by one, the opening degree is set to change from 20%, 40%, 60%, 80%, and 100% one by one, the auxiliary air door opening degree is adjusted, the differentiated adjustment is realized, and the appropriate air door opening degree is sought; If the primary air speed deviation exceeds the allowable range, the adjustable contraction hole at the outlet of the coal mill is adjusted to reduce the deviation value, and the principle of adjustment is to first open the adjustable contraction hole of the primary air pipe with the lowest air speed and then close the adjustable contraction hole of the primary air pipe with the highest air speed, so that the air speed deviation of each primary air pipe is kept within 10%; If the coal powder fineness on the single side is not within the design range, the single-side deflection baffle of the coal mill is adjusted to adjust the coal powder fineness on the single side of each coal mill, and when the coal powder fineness on the single side meets the requirements, steel balls are appropriately added if the coal mill output does not meet the requirements; According to the coal powder quantity deviation in the single-side primary air pipe at the outlet of the coal mill, the single-side coal powder distributor at the outlet of the coal mill is adjusted one by one to reduce the coal powder quantity deviation in the primary air pipe at the outlet of the coal mill, and the single-side coal powder quantity deviation is kept within 10%; after the single-side coal powder distributor is adjusted, the change of the coal powder quantity distribution will affect the primary air speed, so the primary air speed at the outlet of the coal mill is measured again, and the air speed deviation of each primary air pipe is kept within 10%.

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