CN111964928B - Unilateral exhaust smoke temperature rise test method for treating blockage of air preheater - Google Patents
Unilateral exhaust smoke temperature rise test method for treating blockage of air preheater Download PDFInfo
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- CN111964928B CN111964928B CN202010591183.4A CN202010591183A CN111964928B CN 111964928 B CN111964928 B CN 111964928B CN 202010591183 A CN202010591183 A CN 202010591183A CN 111964928 B CN111964928 B CN 111964928B
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Abstract
The invention discloses a single-side exhaust gas temperature rise test method for treating air preheater blockage, which belongs to the coal-fired power generation industry and mainly comprises test basic conditions and requirements, test operation and requirements, test risk points and control measures, test effect evaluation and the like, wherein the test basic conditions and requirements comprise preparation before test and test working condition requirements, the test operation and requirements comprise an air feeder outlet connection door adjusting method of opening, an air feeder outlet connection door adjusting method of closing and a common operation point and requirement of the two adjusting methods, the test risk points and the control measures comprise air preheater tripping and low-temperature corrosion, the method is characterized in that the vibration of a draught fan and the temperature of a bearing are high, the temperature of flue gas at an inlet of a desulfurization system is high, a blower surges and stalls, and the evaluation of the test effect comprises 3 evaluation indexes of the flue gas side differential pressure drop of an air preheater at a heating side, the flue gas side differential pressure drop speed of the air preheater at a target temperature and the amplification of test power consumption. The invention can ensure the safe and economic operation of the unit.
Description
Technical Field
The invention relates to a unilateral exhaust gas temperature rise test method for treating air preheater blockage, belonging to the coal-fired power generation industry.
Background
The air preheater is the important component of coal fired power plant boiler equipment, can effectively improve boiler operation economy, but when air preheater took place to block up, can lead to boiler wind cigarette system resistance to increase, increases and send/draught fan power consumption, under the extreme condition, can influence the unit load carrying capacity and lead to equipment problems such as draught fan stall. In recent years, national thermal power units are transformed into ultra-low emission, large coal-fired units in service are gradually transformed into and use flue gas denitration devices, most of the flue gas denitration devices adopt SCR denitration processes, sticky ammonium bisulfate is easily generated in the denitration process, and the ammonium bisulfate and fly ash jointly act to adhere to heat exchange elements of an air preheater, so that the air preheater is easily blocked.
For preventing and treating the blockage problem of the ammonium bisulfate type of the coal-fired unit, the first solution is to adjust the unit operation, develop the denitration system and the air preheater for overhaul and maintenance after the unit is shut down, analyze the main reason of the blockage of the ammonium bisulfate type of the air preheater and perform technical transformation when necessary. The methods of maintenance, repair, technical transformation and the like all need the shutdown of the unit, and the problem of blockage of the air preheater in the running unit cannot be solved in time; the method for regulating the thermal state operation of the unit mainly comprises the fuel characteristics and blending mode and boiler NOxThe method mainly aims at preventing and delaying the blockage of the air preheater and has an insignificant treatment effect on the problem that the air preheater is obviously blocked by ammonium bisulfate. At present, some power plants develop a temperature rise method for treating the blockage problem of the air preheater according to the principle that the adhesion is weakened after ammonium bisulfate is converted into a gaseous state after the temperature is increased, but the treatment effect is difficult to ensure due to the lack of effective guidance of a test method, requirements, a flow and the like. In literature data, two papers of high-pressure water washing and temperature-raising gasified ammonium bisulfate solution air preheater ash blocking effect analysis published by the morning monarch and research and application of temperature-raising technology to air preheater blocking treatment published by the plum-hong dynasty are mainly introduced simply according to the principle, case and caution items of temperature-raising air preheater blocking treatment, and partial operation parameter selection also has problems, and comprehensive system exposition is not carried out on test preparation, working condition requirements, operation process, key parameter selection, danger point control and effect evaluation. Therefore, a single-side exhaust gas temperature rise test research for treating air preheater blockage should be developed, a scientific air preheater blockage treatment test method is provided, and a feasible solution is provided for treating the problem of blockage of an ammonium bisulfate type of an air preheater in a transport unitSo as to ensure the safe and economic operation of the unit.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a unilateral exhaust gas temperature rise test method for treating air preheater blockage.
The low-temperature economizer is suitable for a thermal power generator set with a rotary air preheater, a low-temperature economizer and an electrostatic dust collector above 300MW grade, the low-temperature economizer is arranged between the rotary air preheater and the electrostatic dust collector or between the electrostatic dust collector and an induced draft fan, and the blockage of the air preheater is mainly caused by ammonium bisulfate generated in the denitration process.
By carrying out test research on the treatment of air preheater blockage by a single-side temperature rise method on a plurality of large coal-fired units, the invention refines and optimizes test preparation, working condition requirements, operation process and key parameter selection, summarizes test dangerous points and control measures, simultaneously provides test effect evaluation indexes and a calculation method, and forms a set of complete air preheater blockage treatment test method.
The technical scheme adopted by the invention for solving the problems is as follows: a single-side exhaust gas temperature rise test method for treating air preheater blockage is characterized by mainly comprising test basic conditions and requirements, test operation and requirements, test risk points and control measures, test effect evaluation and the like, wherein the test basic conditions and requirements comprise preparation before test and test working condition requirements, the test operation and requirements comprise an air feeder outlet connection door adjusting method of opening, an air feeder outlet connection door adjusting method of closing and two adjusting methods common operation and requirements, the test risk points and the control measures comprise air preheater tripping and low-temperature corrosion, the method is characterized in that the vibration of a draught fan and the temperature of a bearing are high, the temperature of flue gas at an inlet of a desulfurization system is high, a blower surges and stalls, and the evaluation of the test effect comprises 3 evaluation indexes of the flue gas side differential pressure drop of an air preheater at a heating side, the flue gas side differential pressure drop speed of the air preheater at a target temperature and the amplification of test power consumption.
In the preparation work before the test, firstly, the coal feeding of the boiler is organized, the deviation of the received base calorific value of the test coal type and the design coal type is not more than 5 percent, and the difference value of the received base sulfur content of the test coal type and the design coal type is not more than + 0.2; ensuring that the oil gun of the boiler is normally put into operation; if the boiler is provided with the plasma ignition device, the arc discharge test of the plasma ignition device is normal; the method comprises the following steps of keeping a boiler fire-fighting water system, a primary air fan, an air feeder, an induced draft fan, a pulverizing system, a denitration system, a low-temperature economizer, a heater (if equipped), an electrostatic precipitator and a desulfurization system to operate well and keep parameters normal; a tool configuration handle required by the air preheater manual barring gear; completing soot blowing of the boiler body and the tail flue; lifting an air preheater sector plate arrangement (if equipped) into position; and keeping the normal spraying system of the accident at the inlet of the absorption tower.
The test condition requires that: the automatic power generation control of the unit is removed, the load of the unit is kept stable, and the unit can be adjusted in a range of 75-85% of rated load by combining the output allowance of the air feeder and whether the temperature of the outlet flue gas of the air preheater at the temperature rising side can reach the target temperature condition, wherein the adjustment range is +/-10% of rated load; continuously shaking the electric fields of the electrostatic dust collectors I, II and III; the main fuel trip protection action with low total air volume is removed; tripping of a heating side fan is removed, protection of a heating side draught fan is combined with tripping, and tripping of a cooling side air preheater and contact door closing tripping of the cooling side fan are achieved; in the test process, the cold ends of the air preheaters at two sides adopt a continuous soot blowing mode, and soot blowing steam parameters are improved under the condition that the design values of the soot blowing steam parameters are not exceeded.
For the method for adjusting the connection door at the outlet of the air feeder, the output of the air feeders on two sides is adjusted to be consistent, the primary air fans on two sides and the connection door at the outlet of the air feeder are started, and the opening degree of the secondary air baffle at the outlet of the air preheater on two sides is fully opened; recording the starting time of the test, controlling the temperature rise rate of the flue gas at the outlet of the air preheater at the temperature rise side to be less than or equal to 0.5-2 ℃/min, and controlling the target temperature to be 200-; slowly reducing the opening degree of a secondary air baffle at the outlet of the air preheater at the heating side, manually operating on the spot, gradually and slowly reducing the opening degree to 0 by each secondary air baffle actuating mechanism at the outlet of the air preheater at the heating side, stopping adjusting the opening degree of the baffles when the flue gas at the outlet of the air preheater at the heating side reaches the target temperature, and controlling the minimum baffle opening degree to be 10% when the last baffle actuating mechanism is operated; in the process of adjusting the opening of a secondary air baffle at the outlet of the air preheater at the heating side, the total air quantity of the boiler is kept unchanged by slowly adjusting the output of a fan at the cooling side; if the target temperature of the flue gas at the outlet of the air preheater at the temperature rising side cannot be reached after the operation of the secondary air baffle at the outlet of the air preheater at the temperature rising side is finished, the output of the air blower at the temperature rising side is slowly reduced, the output of the air blower at the temperature reducing side is slowly increased, and the total air volume of the boiler is also kept unchanged in the process; when the temperature of the flue gas at the outlet of the air preheater at the temperature rising side rises to 170 ℃, stopping rising the temperature, comprehensively checking the running condition of the air-smoke system, and keeping the running condition for more than 180 min. In the process, if the temperature of the flue gas at the outlet of the air preheater at the temperature rising side is found to be in an upward slow trend and exceeds 170 ℃, the opening degree of the secondary air damper at the outlet of the air preheater at the temperature rising side can be slowly increased.
For the method for adjusting the connection door for closing the outlets of the blowers, the output of the blowers on the two sides is adjusted to be consistent, the connection doors for the outlets of the blowers on the two sides are slowly closed, and the wind pressure, the current and the pressure of a secondary air box at the outlets of the blowers on the two sides are kept stable; recording the starting time of the test, slowly reducing the output of the temperature-rise side air blower, and controlling the temperature rise rate of the flue gas temperature at the outlet of the air preheater at the temperature rise side to be less than or equal to 0.5-2 ℃/min and the target temperature of the flue gas at the outlet of the air preheater to be 200-; slowly increasing the output of a cooling side air blower, controlling the temperature drop rate of the flue gas at the outlet of the cooling side air preheater to be less than or equal to 0.5-2 ℃/min, and controlling the current of the cooling side air blower to be less than 90% of the rated current; if the opening of the heating side air blower is slowly reduced to 10%, stopping adjusting the opening of the blades of the heating side air blower, slowly closing the secondary air baffle plates at the outlet of the heating side air preheater on site, gradually and slowly reducing the opening of each secondary air baffle plate execution mechanism at the outlet of the heating side air preheater to 0, stopping adjusting the opening of the baffle plates when the flue gas at the outlet of the heating side air preheater reaches the target temperature, and controlling the minimum opening to be 10% when the last baffle plate execution mechanism is operated; in the process of adjusting the opening of a secondary air baffle at the outlet of the air preheater at the heating side, the total air quantity of the boiler is kept unchanged by slowly adjusting the output of a fan at the cooling side; when the temperature of the flue gas at the outlet of the air preheater at the temperature rising side rises to 170 ℃, stopping rising the temperature, comprehensively checking the running condition of the air-smoke system, and keeping the running condition for more than 180 min. In the process, if the temperature of the flue gas at the outlet of the air preheater at the temperature rising side is found to be in an upward slow trend and exceeds 170 ℃, the opening degree of the blades of the fan at the temperature rising side can be slowly reduced.
The common operation point and requirement of the adjusting method of the communication door for opening the outlet of the blower and the adjusting method of the communication door for closing the outlet of the blower are as follows: adjusting the running mode of the low-temperature economizer, opening a water side water inlet manual door of the low-temperature economizer at the temperature rise side, slowly adjusting a water side water inlet adjusting door of the low-temperature economizer at the temperature rise side, and controlling the temperature of flue gas at the outlet of the low-temperature economizer at the temperature rise side to be not higher than 150 ℃; controlling the temperature of the flue gas at the outlet of the air preheater at the cooling side not to be lower than 80 ℃; when the temperature of the flue gas at the outlet of the air preheater at the temperature rise side reaches 200-; and after the temperature rise is finished, operating in a reverse way according to the respective temperature rise processes of two regulation methods according to the temperature reduction rate of less than or equal to 0.5-2 ℃/min, gradually reducing the temperature of the flue gas at the outlet of the air preheater at the temperature rise side to be normal, and finishing the test.
The test risk points and control measures comprise: (1) the method comprises the following steps that (1) the air preheater is tripped and corroded at low temperature, current and local friction sound of the air preheater are monitored in the temperature rising process, when the current fluctuates to 50% of rated current, the temperature is raised temporarily, and after the current is stabilized for 10min, if the fluctuation amplitude of the current exceeds +/-2A, cooling treatment is carried out to prevent the air preheater from being jammed and tripped; the temperature of the flue gas at the outlet of the air preheater at the cooling side is controlled to be not lower than 80 ℃, if the condition can not be met in the operation process of the two regulation methods, the test is stopped, and the next test can increase the rated load by 10 percent on the load of the test. (2) The vibration of the induced draft fan and the temperature of the bearing are high, if the vibration of the X axis or the Y axis of the induced draft fan exceeds a half of the alarm value, the detection is required immediately, and the test can be stopped; the temperature of the bearing of the induced draft fan and the bearing of the motor is closely monitored, if a certain measuring point reaches an alarm value, the standby cooling fan is immediately started, and the test can be stopped. (3) The inlet flue gas temperature of the desulfurization system is high, the inlet flue gas temperature of the desulfurization tower is controlled by controlling the outlet flue gas temperature of the low-temperature economizer at the temperature rising side, the temperature parameters of the outlet flue gas of the low-temperature economizer, the inlet and the outlet of the electrostatic precipitator and the inlet flue gas temperature parameter at the tower collecting inlet of the desulfurization tower are monitored, if the temperature measuring point is found to exceed 150 ℃, the water inlet adjusting door of the low-temperature economizer at the temperature rising side is adjusted in time, and the opening degree of a fan blade of a temperature rising side blower is increased or the opening degree of a secondary air baffle plate at the outlet of an air preheater at the temperature rising side is increased; when the temperature of the smoke at the outlet of the low-temperature economizer on the heating side is controlled to be not higher than 150 ℃, if the water inlet adjusting door on the water side of the low-temperature economizer on the heating side is fully opened, the temperature cannot be further controlled, and the test is terminated. (4) When the surge and stall of the air feeder are realized, when the connection door adjusting method of the air feeder outlet is adopted, because the opening degree of the secondary air baffle at the outlet of the air preheater at the temperature rising side is gradually reduced, the air pressure at the outlet of the air feeder at the side is gradually increased, the problem of surge of the air feeder is noticed, the current parameter of the air feeder is observed, and if the current fluctuation exceeds +/-2A, the test is stopped immediately; when the method of closing the outlet of the blower and connecting the door is adopted, the current of the blower at the cooling side is less than 90% of rated current, the problem of stalling of the blower is noticed, and the current parameter of the blower is observed, if the current fluctuation exceeds +/-2A, the test is immediately stopped; when the method of closing the outlet connection door of the blower is adopted, the current of the blower at the cooling side reaches 90% of rated current, the total air quantity of the boiler cannot be maintained along with the further reduction of the output of the blower at the heating side or the further reduction of the opening degree of a secondary air baffle at the outlet of the air preheater, the test should be stopped in time, and the rated load can be reduced by 10% in the test load at the next time.
In the test effect evaluation, the temperature rise side air preheater flue gas side differential pressure drop can be calculated according to (1):
Δp＝Δp1-Δp2 (1)
in the formula:
Δp1-differential pressure, Pa, at the flue gas side of the air preheater at the temperature rise side at the start of the test;
Δp2-the differential pressure, Pa, at the flue gas side of the air preheater at the temperature rise side at the end of the test;
the differential pressure reduction speed of the smoke side of the heating side air preheater at the target temperature can be calculated according to (2):
in the formula:
dpm-the flue gas side of the air preheater is heated up at a certain time point at the target temperatureDifferential pressure change, Pa;
dtmtime change at a certain time point at the target temperature for 10 min;
the increase of the test power consumption can be calculated according to (3):
ΔW＝Wb,1-2+Wi,1-2-(Pb,1+Pi,1)*(ts+tc+tj) (3)
in the formula:
Wb,1-2the total power consumption of the blowers at two sides from the beginning of the test to the end of the test is kW.h;
Wi,1-2the total power consumption of the induced draft fans at two sides from the beginning of the test to the end of the test is kW.h;
Pb,1the total power of blowers at two sides is kW when the test is started;
Pi,1the total power of the induced draft fans at the two sides is kW when the test is started;
ts-the time period from the start of the test to the rise to the target temperature, h;
tc-at the target temperature for a time period, h;
tj-the time period, h, from the beginning of the temperature decrease of the target temperature to the end of the test.
Compared with the prior art, the invention has the following advantages and effects:
1) the invention provides a set of scientific air preheater blockage treatment test method, which is used for refining and optimizing test preparation, working condition requirements, operation processes and key parameter selection, summarizing test dangerous points and control measures, and simultaneously comprises test effect evaluation indexes and a calculation method; (2) the test method can solve the problem of blockage of the air preheater of the running unit, adopts a non-stop treatment mode, and provides a perfect solution for online treatment of the blockage of the air preheater; (3) through developing this type of experiment, can effectively administer air heater ammonium bisulfate type jam problem, improve unit safe and economic operation level.
Drawings
FIG. 1 is a flow chart of an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.
Examples are given.
A certain coal-fired power generation enterprise #3 unit (330MW) is provided with a subcritical natural circulation boiler which is produced by introducing the technology of American CE company and has the model number of SG 1025/17.53-M842. A single-hearth four-corner tangential combustion mode is adopted, a warehouse type steel ball milling powder system is matched, five-layer combustors are adopted, a partition flue baffle plate is used for adjusting the temperature of reheated steam, the temperature of the superheated steam is controlled through primary and secondary water spraying, balanced ventilation is achieved, an all-steel structure is adopted, a semi-open island type arrangement mode is adopted, solid-state mechanical deslagging is achieved, and a gram type three-bin rotary air preheater is adopted. The tail flue of the unit is divided into an A side and a B side, a rotary air preheater, a low-temperature economizer and an electrostatic dust collector are installed, the low-temperature economizer is installed between the rotary air preheater and the electrostatic dust collector, and after the unit is transformed by ultralow emission, the air preheater is blocked by ammonium bisulfate due to large ammonia injection amount or poor ammonia injection uniformity in the denitration process.
In the operation process of the unit, the pressure difference of the flue gas side of the air preheater at the side A is large, the problem of obvious blockage is caused, and the blockage problem of the air preheater at the side A is solved by a single-side flue gas temperature rise test method.
The test load is selected to be 250MW, the unit load rate is 76%, the flue gas side differential pressure of the air preheater on the side A is 2500Pa, and the flue gas side differential pressure of the air preheater on the side B is 1500Pa before the test is started.
Firstly, preparing before a test, organizing the coal feeding of a boiler, wherein the deviation of the received base calorific value of the test coal type and the designed coal type is not more than 5 percent, the received base sulfur content difference value of the test coal type and the designed coal type is not more than +0.2, and the coal quality data of the test coal type and the designed coal type are shown in a table 1; ensuring that the operation of the boiler oil gun and the arc discharge test of the plasma ignition device are normal; the boiler fire-fighting water system, the primary air fan, the air feeder, the induced draft fan, the powder making system, the denitration system, the low-temperature economizer, the electrostatic dust collector and the desulfurization system are kept to run well and have normal parameters; a tool configuration handle required by the air preheater manual barring gear; completing soot blowing of the boiler body and the tail flue; lifting the air preheater sector plate device in place; and keeping the normal spraying system of the accident at the inlet of the absorption tower.
TABLE 1
The test condition requires that: the automatic power generation control of the unit is removed, the load of the unit is kept stable, the test load is 250MW, and the load rate of the unit is 76%; 4 sets of operation of the pulverizing system is maintained; continuously shaking the electric fields of the electrostatic dust collectors I, II and III; the main fuel trip protection action with low total air volume is removed; the protection of the induced draft fan at the A side is released, the induced draft fan at the A side is tripped, and the protection of the air preheater at the B side is tripped and contacts the door to close and trip the fan at the B side; in the test process, the cold ends of the air preheaters at two sides adopt a continuous soot blowing mode, and the soot blowing pressure is 1.5 MPa.
Selecting a method for adjusting the connection doors of the outlets of the blowers to be closed, firstly adjusting the output of the blowers on the two sides to be consistent, slowly closing the connection doors of the outlets of the blowers on the two sides, and keeping the air pressure, the current and the pressure of the secondary air box at the outlets of the blowers on the two sides stable; recording the starting time of the test, slowly reducing the output of the air blower at the side A, and controlling the temperature rise rate of the flue gas at the outlet of the air preheater at the side A to be less than or equal to 0.5-2 ℃/min and the target temperature of the flue gas at the outlet of the air preheater to be 200-; slowly increasing the output of a B-side fan, controlling the temperature drop rate of the flue gas at the outlet of the B-side air preheater to be less than or equal to 0.5-2 ℃/min, and controlling the current of the B-side fan to be less than 90% of the rated current; in the process of adjusting the opening of the secondary air baffle at the outlet of the air preheater at the side A, the total air quantity of the boiler is kept unchanged by slowly adjusting the output of the air blower at the side B; when the temperature of the flue gas at the outlet of the air preheater at the side A rises to 170 ℃, stopping heating, comprehensively checking the running condition of the air-smoke system, and keeping for 180 min.
Adjusting the operation mode of the low-temperature economizer, opening a water side water inlet manual door of the low-temperature economizer on the side A, slowly adjusting a water side water inlet adjusting door of the low-temperature economizer on the side A, and controlling the temperature of flue gas at the outlet of the low-temperature economizer on the side A to be not higher than 150 ℃; controlling the temperature of the flue gas at the outlet of the air preheater at the B side not to be lower than 80 ℃; when the temperature of the flue gas at the outlet of the air preheater at the side A reaches 200-; and after the temperature rise is finished, reversely operating according to the temperature rise process at the temperature reduction rate of less than or equal to 0.5-2 ℃/min, gradually reducing the temperature of the flue gas at the outlet of the air preheater at the side A to be normal, and then finishing the test.
In the test effect evaluation, the differential pressure drop of the flue gas side of the air preheater at the A side is calculated as follows: Δ p ═ Δ p1-Δp2550 Pa; and (3) calculating the differential pressure drop speed of the smoke side of the A-side air preheater at the end of continuous operation at the target temperature:
and (3) calculating the amplification of the test power consumption: Δ W ═ Wb,1-2+Wi,1-2-(Pb,1+Pi,1)*(ts+tc+tj)＝2696kWh。
The test risk points and control measures comprise: (1) the method comprises the steps of tripping the air preheater and corroding at low temperature, monitoring current and local friction sound of the air preheater in the temperature rising process, temporarily raising the temperature when the current fluctuates to 50% of rated current, and cooling if the current fluctuation amplitude exceeds +/-2A after the current is stabilized for 10min so as to prevent the air preheater from tripping in a jamming mode. (2) The vibration of the induced draft fan and the temperature of the bearing are high, if the vibration of the X axis or the Y axis of the induced draft fan exceeds a half of the alarm value, the detection is required immediately, and the test can be stopped; the temperature of the bearing of the induced draft fan and the bearing of the motor is closely monitored, if a certain measuring point reaches an alarm value, the standby cooling fan is immediately started, and the test can be stopped. (3) The inlet flue gas temperature of the desulfurization system is high, the inlet flue gas temperature of the desulfurization tower is controlled by controlling the outlet flue gas temperature of the low-temperature economizer at the A side, the temperature parameters of the outlet flue gas of the low-temperature economizer, the inlet and the outlet of the electrostatic precipitator and the inlet flue gas temperature parameters of the tower collecting inlet of the desulfurization tower are monitored, if the temperature measuring point is found to exceed 150 ℃, the water inlet adjusting door at the water side of the low-temperature economizer at the A side is adjusted in time, the opening degree of a fan blade at the A side is increased or the opening degree of a secondary air baffle at the outlet of an air preheater at the A side is increased; when the temperature of the smoke at the outlet of the low-temperature coal economizer on the side A is controlled not to be higher than 150 ℃, if the water inlet adjusting door on the water side of the low-temperature coal economizer on the side A is fully opened, the temperature cannot be further controlled, and the test is terminated. (4) And (3) surging and stalling of the blower, wherein the current of the blower on the B side is less than 90% of rated current, the problem of stalling of the blower is noticed, and the current parameter of the blower is observed, and if the current fluctuation exceeds +/-2A, the test is immediately stopped.
Those not described in detail in this specification are well within the skill of the art.
Although the present invention has been described with reference to the above embodiments, it should be understood that the scope of the present invention is not limited thereto, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.
Claims (1)
1. A single-side exhaust gas temperature rise test method for treating air preheater blockage is characterized by mainly comprising test basic conditions and requirements, test operation and requirements, test risk points and control measures and test effect evaluation, wherein the test basic conditions and requirements comprise preparation before test and test working condition requirements, the test operation and requirements comprise an air blower outlet connection door adjusting method of opening an air blower, an air blower outlet connection door adjusting method of closing an air blower and common operation and requirements of the two adjusting methods, the test risk points and the control measures comprise tripping and low-temperature corrosion of the air preheater, the method comprises the following steps that the vibration of a draught fan and the temperature of a bearing are high, the temperature of flue gas at the inlet of a desulfurization system is high, a blower surges and stalls, and the test effect evaluation comprises 3 evaluation indexes of the flue gas side differential pressure drop of an air preheater at a heating side, the flue gas side differential pressure drop speed of the air preheater at a heating side at a target temperature and the test power consumption amplification;
preparation before the test: firstly, organizing the coal feeding of a boiler, wherein the deviation of the received base calorific value of a test coal type and a design coal type is not more than 5 percent, and the difference value of the received base sulfur content of the test coal type and the design coal type is not more than + 0.2; ensuring that the oil gun of the boiler is normally put into operation; the method comprises the following steps of keeping a boiler fire fighting water system, a primary air fan, an air feeder, an induced draft fan, a pulverizing system, a denitration system, a low-temperature economizer, a fan heater, an electrostatic dust collector and a desulfurization system to operate well and keep parameters normal; a tool configuration handle required by the air preheater manual barring gear; completing soot blowing of the boiler body and the tail flue; lifting the air preheater sector plate device in place; keeping the absorption tower inlet accident spraying system normal;
the test condition requires that: the automatic power generation control of the unit is removed, the load of the unit is kept stable, and the unit is adjusted in a 75-85% rated load range by combining the output allowance of the air feeder and whether the outlet flue gas temperature of the air preheater at the temperature rising side can reach the target temperature condition, wherein the adjustment range is +/-10% of the rated load; continuously shaking the electric fields of the electrostatic dust collectors I, II and III; the main fuel trip protection action with low total air volume is removed; tripping of a heating side fan is removed, protection of a heating side draught fan is combined with tripping, and tripping of a cooling side air preheater and contact door closing tripping of the cooling side fan are achieved; in the test process, the cold ends of the air preheaters at two sides adopt a continuous soot blowing mode, and soot blowing steam parameters are improved under the condition that the design values of the soot blowing steam parameters are not exceeded;
opening an outlet communication door of a blower: firstly, adjusting the output of blowers on two sides to be consistent, opening primary blowers and blower outlet connecting doors on two sides, and fully opening secondary air baffles at the outlets of air preheaters on two sides; recording the starting time of the test, controlling the temperature rise rate of the flue gas at the outlet of the air preheater at the temperature rise side to be less than or equal to 0.5-2 ℃/min, and controlling the target temperature to be 200-; slowly reducing the opening degree of a secondary air baffle at the outlet of the air preheater at the heating side, manually operating on the spot, gradually and slowly reducing the opening degree to 0 by each secondary air baffle actuating mechanism at the outlet of the air preheater at the heating side, stopping adjusting the opening degree of the baffles when the flue gas at the outlet of the air preheater at the heating side reaches the target temperature, and controlling the minimum baffle opening degree to be 10% when the last baffle actuating mechanism is operated; in the process of adjusting the opening of a secondary air baffle at the outlet of the air preheater at the heating side, the total air quantity of the boiler is kept unchanged by slowly adjusting the output of a fan at the cooling side; if the target temperature of the flue gas at the outlet of the air preheater at the temperature rising side cannot be reached after the operation of the secondary air baffle at the outlet of the air preheater at the temperature rising side is finished, the output of the air blower at the temperature rising side is slowly reduced, the output of the air blower at the temperature reducing side is slowly increased, and the total air volume of the boiler is maintained unchanged in the process; when the temperature of the flue gas at the outlet of the air preheater at the temperature rising side rises to 170 ℃, stopping rising the temperature, comprehensively checking the running condition of the air-smoke system, and keeping the running condition for more than 180 min; in the process, if the temperature of the flue gas at the outlet of the air preheater at the temperature rising side is found to be in an upward slow trend and exceeds 170 ℃, the opening degree of a secondary air baffle at the outlet of the air preheater at the temperature rising side is slowly increased;
closing an outlet communication door of a blower: firstly, the output of the blowers on the two sides is adjusted to be consistent, the connection doors at the outlets of the blowers on the two sides are slowly closed, and the wind pressure, the current and the pressure of the secondary air box at the outlets of the blowers on the two sides are kept stable; recording the starting time of the test, slowly reducing the output of the temperature-rise side air blower, and controlling the temperature rise rate of the flue gas temperature at the outlet of the air preheater at the temperature rise side to be less than or equal to 0.5-2 ℃/min and the target temperature of the flue gas at the outlet of the air preheater to be 200-; slowly increasing the output of a cooling side air blower, controlling the temperature drop rate of the flue gas at the outlet of the cooling side air preheater to be less than or equal to 0.5-2 ℃/min, and controlling the current of the cooling side air blower to be less than 90% of the rated current; when the opening degree of the heating side air blower is slowly reduced to 10%, stopping adjusting the opening degree of blades of the heating side air blower, slowly closing a secondary air baffle plate at the outlet of the heating side air preheater on site, gradually and slowly reducing the opening degree of each secondary air baffle plate execution mechanism at the outlet of the heating side air preheater to 0, stopping adjusting the baffle opening degree when the flue gas at the outlet of the heating side air preheater reaches the target temperature, and controlling the minimum opening degree to be 10% when the last baffle plate execution mechanism is operated; in the process of adjusting the opening of a secondary air baffle at the outlet of the air preheater at the heating side, the total air quantity of the boiler is kept unchanged by slowly adjusting the output of a fan at the cooling side; when the temperature of the flue gas at the outlet of the air preheater at the temperature rising side rises to 170 ℃, stopping rising the temperature, comprehensively checking the running condition of the air-smoke system, and keeping the running condition for more than 180 min; in the process, if the temperature of the flue gas at the outlet of the air preheater at the temperature rising side is found to be in an upward slow trend and exceeds 170 ℃, the opening degree of the blades of the fan at the temperature rising side is slowly reduced;
the common operation point and requirement of the adjusting method of the connection door of the opening air feeder outlet and the adjusting method of the connection door of the closing air feeder outlet are as follows: adjusting the running mode of the low-temperature economizer, opening a water side water inlet manual door of the low-temperature economizer at the temperature rise side, slowly adjusting a water side water inlet adjusting door of the low-temperature economizer at the temperature rise side, and controlling the temperature of flue gas at the outlet of the low-temperature economizer at the temperature rise side to be not higher than 150 ℃; controlling the temperature of the flue gas at the outlet of the air preheater at the cooling side not to be lower than 80 ℃; the temperature of the flue gas at the outlet of the air preheater at the temperature-rising side reaches 200-; after the temperature rise is finished, according to the temperature reduction rate of less than or equal to 0.5-2 ℃/min, the operation is carried out reversely according to the respective temperature rise processes of two regulation methods, and after the temperature of the flue gas at the outlet of the air preheater at the temperature rise side is gradually reduced to be normal, the test is finished;
the test risk points and control measures comprise: (1) the method comprises the following steps that (1) the air preheater is tripped and corroded at low temperature, current and local friction sound of the air preheater are monitored in the temperature rising process, when the current fluctuates to 50% of rated current, the temperature is raised temporarily, and after the current is stabilized for 10min, if the fluctuation amplitude of the current exceeds +/-2A, cooling treatment is carried out to prevent the air preheater from being jammed and tripped; controlling the temperature of the flue gas at the outlet of the air preheater at the cooling side to be not lower than 80 ℃, if the condition can not be met in the operation process of the two regulation methods, stopping the test, and increasing the rated load by 10 percent on the load of the test in the next test; (2) the vibration of the induced draft fan and the temperature of the bearing are high, if the vibration of the X axis or the Y axis of the induced draft fan exceeds a half of the alarm value, the detection is carried out immediately, and the test is terminated; closely monitoring the temperature of a bearing of the induced draft fan and a bearing of the motor, if a certain measuring point reaches an alarm value, immediately starting a standby cooling fan, and terminating the test; (3) the inlet flue gas temperature of the desulfurization system is high, the inlet flue gas temperature of the desulfurization tower is controlled by controlling the outlet flue gas temperature of the low-temperature economizer at the temperature rising side, the temperature parameters of the outlet flue gas of the low-temperature economizer, the inlet and the outlet of the electrostatic precipitator and the inlet flue gas temperature parameter at the tower collecting inlet of the desulfurization tower are monitored, if the temperature measuring point is found to exceed 150 ℃, the water inlet adjusting door at the water side of the low-temperature economizer at the temperature rising side is adjusted in time, and the opening degree of a fan blade of a fan at the temperature rising side is increased or the opening degree of a secondary air baffle plate at the outlet of an air preheater at the temperature rising side is increased; when the temperature of the smoke at the outlet of the low-temperature economizer at the temperature rising side is controlled to be not higher than 150 ℃, if the water inlet adjusting door at the water side of the low-temperature economizer at the temperature rising side is fully opened and the temperature cannot be further controlled, the test is terminated; (4) when the air feeder surges and stalls, when a method of opening an outlet communication door of the air feeder is adopted, because the opening degree of a secondary air baffle at the outlet of an air preheater at a temperature rising side is gradually reduced, the air pressure at the outlet of the air feeder at the side is gradually increased, the problem of surge of the air feeder is noticed, current parameters of the air feeder are observed, and if current fluctuation exceeds +/-2A, the test is immediately stopped; when the method of closing the outlet of the blower and connecting the door is adopted, the current of the blower on the cooling side is less than 90% of rated current, the problem of stalling of the blower is noticed, the current parameter of the blower is observed, and if the current fluctuation exceeds +/-2A, the test is immediately stopped; when the method of closing the outlet connection door of the air feeder is adopted, the current of the air feeder at the cooling side reaches 90% of rated current, the total air quantity of the boiler cannot be maintained as the output of the air feeder at the heating side is further reduced or the opening of a secondary air baffle at the outlet of the air preheater is further reduced, the test is terminated in time, and the rated load of the next test is reduced by 10% of the load of the test;
in the test effect evaluation, the temperature rise side air preheater flue gas side difference pressure drop is calculated according to (1):
Δp＝Δp1-Δp2 (1)
in the formula:
Δp1-differential pressure, Pa, at the flue gas side of the air preheater at the temperature rise side at the start of the test;
Δp2-the differential pressure, Pa, at the flue gas side of the air preheater at the temperature rise side at the end of the test;
and (3) calculating the differential pressure reduction rate of the smoke side of the air preheater at the temperature rise side at the target temperature according to (2):
in the formula:
dpmthe differential pressure change of the flue gas side of the air preheater at a certain time point under the target temperature is Pa;
dtmtime change at a certain time point at the target temperature for 10 min;
the increase of the test power consumption is calculated according to (3):
ΔW＝Wb,1-2+Wi,1-2-(Pb,1+Pi,1)*(ts+tc+tj) (3)
in the formula:
Wb,1-2the total power consumption of the blowers at two sides from the beginning of the test to the end of the test is kW.h;
Wi,1-2the total power consumption of the induced draft fans at two sides from the beginning of the test to the end of the test is kW.h;
Pb,1the total power of blowers at two sides is kW when the test is started;
Pi,1the total power of the induced draft fans at the two sides is kW when the test is started;
ts-the time period from the start of the test to the rise to the target temperature, h;
tc-at the target temperature for a time period, h;
tj-the time period, h, from the beginning of the temperature decrease of the target temperature to the end of the test.
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