An anti-clogging method for an air preheater

Abstract

The present invention discloses a method for preventing blockage of an air preheater. Step S100: Obtain the differential pressure before and after the flue gas side of the air preheater; Step S200: When the differential pressure is greater than a first preset value and lasts for at least a first preset time, control the unit to perform soot blowing with a low-frequency and high-intensity acoustic soot blower. After the unit performs soot blowing with the low-frequency and high-intensity acoustic soot blower for a first preset number of times, detect the differential pressure. If the differential pressure is greater than a second preset value and lasts for at least a second preset time, it is determined that the air preheater has blockage substances mainly composed of ammonium bisulfate, and a pyrolysis operation is performed, wherein the second preset value is greater than the first preset value. The present invention can reduce the frequency of pyrolyzing ammonium bisulfate, improve the service life of each component of the unit and the stability of the unit operation, and provide maintenance suggestions for the frequent accumulation of ammonium bisulfate.

Description

Technical Field

[0001] The present invention relates to the technical field of air preheaters, and specifically to a method for preventing blockage of an air preheater. Background Art

[0002] With the increase in the operation time of the SCR reactor and the increase in the post-injection ammonia amount after ultra-low emissions, different degrees of blockage, corrosion, and increased resistance have occurred in the equipment and pipelines downstream of the SCR. Among them, the problem of ash accumulation and blockage in the air preheater is particularly serious. The substances blocking the air preheater are mainly flue gas dust, ammonium bisulfate, ammonium sulfate, etc. Based on the fact that ammonium bisulfate can pyrolyze at a certain temperature, when the differential pressure of the air preheater reaches a set value, the unit will be controlled to perform the pyrolysis operation of ammonium bisulfate, thereby solving the problem of air preheater blockage. However, frequent pyrolysis operations will, on the one hand, affect the normal operation of the unit, and on the other hand, since the pyrolysis process of ammonium bisulfate requires precise control of temperature and concentration, improper operation may cause equipment damage or affect the equipment life.

[0003] Based on this, how to avoid frequent pyrolysis of ammonium bisulfate on the premise of preventing the blockage of the air preheater, thereby improving the life of the unit components and the stability of the unit power supply, is a difficult problem that urgently needs to be solved for the current blockage of the air preheater. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preventing blockage of an air preheater to solve the problems raised in the above background art.

[0005] On the one hand, the present invention provides a method for preventing blockage of an air preheater, including the following steps:

[0006] Step S100, obtaining the differential pressure before and after the flue gas side of the air preheater;

[0007] Step S200, when the differential pressure is greater than the first preset value and lasts for at least the first preset duration, control the unit to perform soot blowing with a low-frequency and high-intensity acoustic soot blower; after the unit performs soot blowing with a low-frequency and high-intensity acoustic soot blower for the first preset number of times, detect the differential pressure. If the differential pressure is greater than the second preset value and lasts for at least the second preset duration, it is determined that the air preheater is blocked by ammonium bisulfate, and a pyrolysis operation is performed, where the second preset value is greater than the first preset value.

[0008] Optionally, the control for the unit to perform the pyrolysis operation is to raise the outlet temperature of the air preheater to T1 and maintain it for the third preset duration, and raise the average temperature at the inlet of the corresponding electrostatic precipitator of the air preheater to T2 and maintain it for the fourth preset duration.

[0009] Optionally, T1 is 160°C, the third preset duration is 4h, T2 is 160°C, and the fourth preset duration is 20h.

[0010] Optionally, the first preset number is 3.

[0011] Optionally, it further includes: counting the number of pyrolysis operations. If the number of pyrolysis operations exceeds the second preset number, a prompt message is sent to the user. The content of the prompt message includes replacing the catalyst of the selective catalytic reduction (SCR) reactor and modifying the ammonia injection grid.

[0012] Optionally, modifying the ammonia injection grid includes: performing a simulation calculation on the resistance from the denitrification ammonia injection pipe to the injection holes of the selective catalytic reduction (SCR) reactor, and adjusting the number of openings of each ammonia injection pipe according to the calculation results.

[0013] Optionally, the method of sending a prompt message to the user includes: sending a prompt message to the user through an intelligent terminal.

[0014] Optionally, the second preset number is 2.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. After the unit performs the low-frequency and high-intensity acoustic soot blower soot blowing for the first preset number of times, the differential pressure is detected. If the differential pressure is greater than the second preset value and lasts for at least the second preset duration, it is determined that there is a blockage mainly composed of ammonium bisulfate in the air preheater, and a pyrolysis operation is performed. Among them, the second preset value is greater than the first preset value. On the one hand, it can confirm that the blockage in the air preheater is mainly caused by ammonium bisulfate, and on the other hand, it can reduce the frequency of ammonium bisulfate pyrolysis operations, improve the service life of the generator set, and ensure the stability of the power supply unit.

[0017] 2. By counting the number of pyrolysis operations, if the number of pyrolysis operations exceeds the second preset number, a prompt message is sent to the user. The content of the prompt message includes replacing the catalyst of the selective catalytic reduction (SCR) reactor and modifying the ammonia injection grid. It can give the user the cause of the failure of frequent generation of ammonium bisulfate in the air preheater and provide a fault handling solution for the user, improving the user experience.

[0018] 3. Through specific pyrolysis operations, the ammonium bisulfate blockage in the air preheater is eliminated. Description of the Drawings

[0019] Figure 1 It is a flowchart of a method for preventing blockage of an air preheater according to the present invention;

[0020] Figure 2 It is a flowchart of the ammonium bisulfate pyrolysis operation of an air preheater according to the present invention. Detailed Embodiments

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Figure 1 is a flowchart of a method for preventing blockage of an air preheater according to an embodiment of the present invention. As Figure 1 shown, the embodiment of the present invention provides a method for preventing blockage of an air preheater.

[0023] The method for preventing blockage of the air preheater includes the following steps:

[0024] Step S100, obtaining the differential pressure before and after the flue gas side of the air preheater;

[0025] Step S200, when the differential pressure is greater than the first preset value and lasts for at least the first preset time, controlling the unit to perform soot blowing with a low-frequency and high-intensity acoustic soot blower; after the unit performs soot blowing with the low-frequency and high-intensity acoustic soot blower for the first preset number of times, detecting the differential pressure, if the differential pressure is greater than the second preset value and lasts for at least the second preset time, determining that ammonium bisulfate blockage occurs in the air preheater, and performing a pyrolysis operation, where the second preset value is greater than the first preset value.

[0026] In this embodiment, each unit is equipped with two air preheaters, and each unit is retrofitted with a selective catalytic reduction (SCR) reactor. Pressure sensors or differential pressure sensors are respectively arranged on the flue gas paths at the inlet and outlet of the air preheater. The differential pressure across the flue gas side of the air preheater refers to the pressure difference between the flue gas paths at the inlet and outlet of the air preheater, which is a key indicator for judging the operation condition of the air preheater. A low-frequency and high-intensity acoustic soot blower is installed at the inlet of the flue gas side of the air preheater. When the differential pressure is greater than the first preset value and lasts for at least the first preset duration, it indicates that there is a blockage problem in the air preheater. Then, the low-frequency and high-intensity acoustic soot blower is controlled to operate, and the loose scale on the surface of the air preheater is removed by means of acoustic vibration. In this case, the loose scale on the surface of the air preheater generally consists mainly of ammonium sulfate and dust, and the amount of ammonium bisulfate is relatively small. When the injected ammonia fails to participate fully in the selective catalytic reduction (SCR) reaction, the escaped ammonia easily reacts with SO3 in the flue gas to form ammonium sulfate and ammonium bisulfate. The generation amount of ammonium bisulfate is proportional to the contents of ammonia and SO3 in the flue gas. Ammonium sulfate is a dry powdery solid without corrosiveness and is easily removed by soot blowing, while ammonium bisulfate has strong viscosity and will accumulate on the surface of objects in a liquid form. The operating temperature at the cold end of the air preheater of a power plant generator set is generally lower than the dew point of ammonium bisulfate, which easily causes the deposition of ammonium bisulfate and the adhesion of fly ash. When the SCR ammonia injection is uneven or the catalyst is severely deactivated, the corrosion risk of ammonium bisulfate in the downstream air preheater increases. That is to say, when the blockage in the air preheater is mainly composed of ammonium sulfate, the blockage in the air preheater is relatively easy to remove. Then, the loose blockage mainly composed of ammonium sulfate can be relatively easily removed by the low-frequency and high-intensity acoustic soot blower, reducing the differential pressure across the air preheater inlet and outlet and alleviating the blockage situation. When the SCR ammonia injection is uneven, the catalyst is severely deactivated, or the operation time is long, the blockage in the air preheater is mainly composed of ammonium bisulfate and its adhered fly ash. Due to the strong viscosity of ammonium bisulfate, the blockage cannot be well removed only by the low-frequency and high-intensity acoustic soot blower, and the differential pressure across the air preheater inlet and outlet cannot be reduced, and the blockage situation cannot be alleviated. At this time, an ammonium bisulfate pyrolysis operation needs to be performed to remove the blockage mainly composed of ammonium bisulfate. If the blockage in the air preheater is directly removed by pyrolysis without using the acoustic vibration method when the air preheater is blocked, the pyrolysis operation will be frequently performed. The pyrolysis of ammonium bisulfate requires operations such as adjusting the unit load, fan speed, and temperature rise. If not careful, it will affect the service life of related components such as the air preheater, induced draft fan, and components in the desulfurization absorption tower. Based on this, in order to reduce the frequency of ammonium bisulfate pyrolysis operations, improve the service life of the generator set, and ensure the stability of the power supply unit, in the case of determining that the air preheater is blocked, the low-frequency and high-intensity acoustic soot blower is first operated for the first preset number of times; after the low-frequency and high-intensity acoustic soot blower of the unit is operated for the first preset number of times, if there is still a blockage situation and the blockage situation becomes more serious, it indicates that the current blockage is mainly composed of ammonium bisulfate, and a pyrolysis operation needs to be performed.The low-frequency high-intensity acoustic soot blower runs for 1 hour or a set duration each time, and the specific duration is set according to experience. The blockages in the air preheater are removed through acoustic vibration and soot blowing methods.

[0027] The blockages in the air preheater usually include ammonium sulfate, dust, and ammonium bisulfate, etc. The occurrence of ammonium sulfate or dust blockage means that the blockage of the air preheater is mainly caused by ammonium sulfate or dust. The occurrence of ammonium bisulfate blockage means that the blockage of the air preheater is mainly caused by ammonium bisulfate and the adhered dust. Of course, it can be distinguished by the proportion of ammonium sulfate or ammonium bisulfate in the total of ammonium sulfate and ammonium bisulfate in the air preheater blockage. For example, ammonium sulfate blockage means that the proportion of ammonium sulfate in the total of ammonium sulfate and ammonium bisulfate in the air preheater blockage is 70%. Ammonium bisulfate blockage means that the proportion of ammonium bisulfate in the total of ammonium sulfate and ammonium bisulfate in the air preheater blockage is 40%. This is because ammonium bisulfate will adhere to the dust. Although the proportion of ammonium bisulfate is relatively low, serious blockage will still occur. Therefore, when the actual proportion of ammonium bisulfate is relatively low, the total blockage amount after ammonium bisulfate adheres to the dust is relatively high, and blockage will also occur. Of course, the specific proportion can also be set according to the actual situation. For example, ammonium sulfate blockage means that the proportion of ammonium sulfate in the total of ammonium sulfate and ammonium bisulfate in the air preheater blockage is 65% or other ratios. Ammonium bisulfate blockage means that the proportion of ammonium bisulfate in the total of ammonium sulfate and ammonium bisulfate in the air preheater blockage is 35% or other ratios. Dust blockage means that dust accounts for the main proportion in the air preheater blockage, such as 70%. Dust and ammonium sulfate blockage means that ammonium sulfate and dust account for the main proportion in the air preheater blockage, such as 70%. The above proportion values can be specifically set according to experience and will not be elaborated here.

[0028] Blockage mainly caused by ammonium sulfate or dust can be removed through acoustic vibration and soot blowing. However, for ammonium bisulfate blockage, due to the strong adhesion of ammonium bisulfate, the effect of removing it solely through acoustic vibration and soot blowing is poor. Therefore, pyrolysis operation of ammonium bisulfate is required to achieve removal.

[0029] Furthermore, when the control unit performs pyrolysis operation, it raises the outlet temperature of the air preheater to T1 and maintains it for the third preset duration, and raises the average temperature at the inlet of the corresponding electrostatic precipitator of the air preheater to T2 and maintains it for the fourth preset duration.

[0030] Since the melting point of ammonium bisulfate is 147°C, when the outlet temperature of the air preheater is higher than 147°C, ammonium bisulfate starts to turn into liquid and is easily removed. T1 is a value greater than 147°C, preferably 160°C, and the third preset duration is preferably 4 hours. T2 is a value greater than 147°C, preferably 160°C, and the fourth preset duration is preferably 20 hours.

[0031] Figure 2 It is a flow chart of the thermal decomposition of ammonium bisulfate in an air preheater according to an embodiment of the present invention.

[0032] The thermal decomposition operation includes:

[0033] Step S301, exit the following interlock protections:

[0034] The interlock that the induced draft fan on the corresponding side trips when the outlet temperature of the air preheater reaches 185°C,

[0035] The interlock that the inlet and outlet air and flue gas dampers of the air preheater are closed interlockingly when the air preheater stops operating,

[0036] The interlock that the forced draft fan, induced draft fan, and primary air fan trip interlockingly when the air preheater stops operating,

[0037] The main fuel trip (MFT) interlock of the boiler when the inlet flue gas temperature of the absorption tower reaches 155°C;

[0038] Step S302, turn the air and flue gas dampers at the inlet and outlet of the air preheater to "small hand", that is, the commissioning position;

[0039] Step S303, turn the connection dampers of the primary air, forced draft air, and induced draft air in the boiler air and flue gas system to "forbidden operation", and keep the connection dampers in the open state;

[0040] Step S304, gradually and slowly close the first and second air dampers at the outlet of the air preheater. When the exhaust gas temperature is below 150°C, control the temperature rise rate not to exceed 3°C / min, and when it is above 150°C, the temperature rise rate is less than 1°C / min. Slowly close the second and second air dampers at the outlet of the air preheater according to the outlet temperature of the air preheater. When closing the second and second air dampers at the outlet of the air preheater, open the secondary air damper in time to control the outlet pressure of the forced draft fan not to exceed 2.7 KPa to prevent the fan from surging;

[0041] Step S305, continuously soot-blow the air preheater during the heating process of the air preheater;

[0042] Step S306, stop heating when the current fluctuation of the air preheater exceeds 10 A or the current reaches 60 A, and continue heating when the current fluctuation is less than 5 A and the current is less than 50 A;

[0043] Step S307, when the exhaust gas temperature of the air preheater reaches 160°C, monitor the change in the differential pressure of the air preheater. After the differential pressure drops, the flue gas volume will increase and the exhaust gas temperature will slowly rise by itself. Slowly open a certain opening of the secondary air damper at the outlet of the air preheater on this side to increase the secondary air volume to control the continuous rise of the exhaust gas temperature;

[0044] Step S308, monitor the flue gas temperature at the inlet of the dust collector corresponding to the air preheater and the original flue gas temperature at the inlet of the desulfurization. Start the emergency spray when the temperature reaches 150°C.

[0045] Step S309: When the differential pressure no longer decreases within 15 minutes, the pyrolysis of ammonium bisulfate in the air preheater is completed.

[0046] Specifically, there are 2 sets of connections between the SCR reactor of the boiler and the fan system, which are referred to as the A side and the B side for convenience of description. On the A side, the flue gas output of the boiler is connected to the A side SCR reactor, and the output of the A side SCR reactor is connected to the A side air preheater. The A side air preheater can be divided into 3 parts, including the A side primary air side, the heating side flue gas side, and the A side secondary air side. The A side induced draft fan is connected to the A side flue gas side of the A side air preheater to take away the flue gas and the heat of the air preheater, and the A side forced draft fan is connected to the A side secondary air side of the A side air preheater to cool the A side air preheater and increase the oxygen content of the boiler. This invention mainly focuses on the pyrolysis of ammonium bisulfate in one of the air preheaters.

[0047] Specifically, the on-line temperature rise pyrolysis for a certain #3 unit is as follows:

[0048] I. Operating mode before pyrolysis

[0049] The #3 unit is in coordinated control mode, with a heat load of 530 MW, C, D, E, and F coal mills in operation, six large fans in operation, and the denitration system and desulfurization system operating normally.

[0050] II. Pyrolysis operation process

[0051] On February 9, 2024, at 10:00, with the heat load of the #3 unit at 530 MW, the on-line temperature rise pyrolysis plan for the 3B air preheater was started, and the preparation work was as follows:

[0052] 1. Withdraw the following interlock protections:

[0053] When the outlet temperature of the 3B air preheater ≥ 185 °C, the 3B induced draft fan trips;

[0054] When the 3B air preheater stops operating, the 3B forced draft fan, 3B induced draft fan, and 3B primary air fan trip;

[0055] When the inlet flue gas temperature of the No. 3 desulfurization absorption tower ≥ 155 °C, the FGD trips and triggers MFT.

[0056] 2. Turn the secondary air damper and inlet flue gas damper at the outlet of the 3B air preheater to "small hand" (commissioning position).

[0057] 3. Turn the connection dampers of the primary air, forced draft, and induced draft fans in the air and flue gas system of the #3 boiler to "forbidden operation", and keep the connection dampers open.

[0058] 4. Turn the secondary air damper, inlet and outlet flue gas dampers, and inlet and outlet primary air dampers at the outlet of the 3B air preheater to "forbidden operation".

[0059] 5. Gradually fully open the hot air recirculation of the two forced draft fans.

[0060] 6. Try to put into operation the accident spray of #3 absorber tower normally.

[0061] At 11:00, gradually manually close the secondary air damper A at the outlet of 3B air preheater on-site, with a range of 10% each time until it is fully closed. Observe that there is no obvious change in the flue gas temperature at the outlets of 3A and 3B air preheaters, the air pressure at the outlet of the forced draft fan, and the pressure in the secondary air box. Then gradually manually close 3B on-site;

[0062] For the secondary air damper B at the outlet of the air preheater, with a range of 10% each time, pause when it is closed to 50%. Observe that there is still no obvious change in the flue gas temperature at the outlets of 3A and 3B air preheaters, the air pressure at the outlet of the forced draft fan, and the pressure in the secondary air box.

[0063] At 11:00, during the heating-up process of 3B air preheater, contact the soot blower operator in advance to increase the set value of the air preheater soot blowing pressure to 2.2 MPa, and put into continuous soot blowing for 3B air preheater (shield the soot blowing gun of 3A air preheater).

[0064] At 11:30, continue to manually close the secondary air damper B at the outlet of 3B air preheater on-site, with a range of 5% each time. During the process of the opening of the secondary air damper B at the outlet of 3B air preheater decreasing from 40% to 30%, the air pressure at the outlet of the forced draft fan rises from 1.9 KPa to 2.6 KPa, the secondary air flow on the B side at the outlet of 3B air preheater decreases from 950 t / h to 770 t / h, and the secondary air flow on the A side at the outlet of 3A air preheater rises from 1000 t / h to 1200 t / h. Due to the obvious parameter changes, slow down the operation range of the secondary air damper B at the outlet of 3B air preheater, with an operation range of 3% each time.

[0065] At 12:00, the secondary air damper B at the outlet of 3B air preheater is closed to about 14%, and the flue gas temperature at the outlet of 3B air preheater rises to 150 °C. The flue gas temperature at the outlet of 3A air preheater drops to 92 °C. The temperature at the inlet of the electrostatic precipitator on the B side rises to about 140 °C. The original flue gas temperature of #3 desulfurization absorber tower rises to about 110 °C.

[0066] At 12:30, the secondary air damper B at the outlet of 3B air preheater is closed to about 12%, and the flue gas temperature at the outlet of 3B air preheater rises to 160 °C. The flue gas temperature at the outlet of 3A air preheater drops to 92 °C. The temperature at the inlet of the electrostatic precipitator on the B side rises to about 150 °C. The original flue gas temperature of #3 desulfurization absorber tower rises to about 120 °C.

[0067] At 13:00, the secondary air damper B at the outlet of 3B air preheater is closed to about 10%, and the flue gas temperature at the outlet of 3B air preheater rises to 168 °C. The flue gas temperature at the outlet of 3A air preheater drops to 85 °C.

[0068] The inlet temperature of the electrostatic precipitator on the B side rises to about 155°C. The original flue gas temperature of the #3 desulfurization absorption tower rises to about 127°C.

[0069] At 17:30, the #3 unit is ready to increase the load. Arrange personnel to wait on-site in advance to prepare to open the secondary air damper B at the outlet of the 3B air preheater to control the exhaust gas temperature at the outlet of the 3B air preheater.

[0070] At 18:10, the thermal load of the #3 unit is increased to 630 MW. Slowly open the secondary air damper B at the outlet of the 3B air preheater to about 18%, and control the exhaust gas temperature at the outlet of the 3B air preheater to stabilize at about 167°C. The inlet temperature of the electrostatic precipitator on the B side is about 155°C. The original flue gas temperature of the #3 desulfurization absorption tower is about 127°C.

[0071] At 23:45, the thermal load of the #3 unit is reduced to 530 MW. Slowly close the secondary air damper B at the outlet of the 3B air preheater to about 10%, and control the exhaust gas temperature at the outlet of the 3B air preheater to stabilize at 167°C. The exhaust gas temperature at the outlet of the 3A air preheater drops to 80°C.

[0072] On February 10, 2024, at 01:20, the thermal load of the #3 unit is reduced to 465 MW. The exhaust gas temperature at the outlet of the 3B air preheater finally stabilizes at 155°C. The exhaust gas temperature at the outlet of the 3A air preheater finally stabilizes at 77°C.

[0073] At 07:45, the thermal load of the #3 unit is increased to 820 MW. Slowly open the secondary air damper B at the outlet of the 3B air preheater to about 40%, and control the exhaust gas temperature at the outlet of the 3B air preheater to stabilize at about 165°C. The inlet temperature of the electrostatic precipitator on the B side is about 155°C. The original flue gas temperature of the #3 desulfurization absorption tower is about 127°C.

[0074] At 10:00, the pyrolysis work of the 3B air preheater ends. Slowly open the hot secondary air dampers A and B at the outlet of the 3B air preheater on-site. After the air and flue gas of the air preheater are balanced, contact the thermal engineering personnel to restore the interlocks and protections withdrawn during the online temperature-raising pyrolysis work of the 3B air preheater. Contact the soot blowing personnel to restore the soot blowing pressure setting value of the #3 boiler air preheater to 1.5 MPa.

[0075] On February 11, 2024, at 09:00, close the connection dampers of the induced draft fan, forced draft fan, and primary air fan of the #3 boiler flue gas system. Observe that the parameters of the #3 boiler flue gas system have no changes, and then reopen the connection dampers of the induced draft fan, forced draft fan, and primary air fan of the #3 boiler flue gas system.

[0076] V. Parameter changes before and after the pyrolysis of the 3B air preheater (#3 boiler thermal load 950 MW)

[0077]

[0078] Furthermore, the first preset number of times is 3.

[0079] Further, it further includes: counting the number of pyrolysis operations. If the number of pyrolysis operations exceeds a second preset number, a prompt message is sent to the user, and the content of the prompt message includes replacing the catalyst of the selective catalytic reduction (SCR) reactor and modifying the ammonia injection grid.

[0080] When the number of pyrolysis operations exceeds the second preset number, it indicates that ammonium bisulfate is the main cause of the air preheater blockage. The reason for the frequent excess of ammonium bisulfate is the ammonia slip. The reasons for the increase in ammonia slip are uneven flow field distribution, poor adjustment of the ammonia injection grid, and catalyst aging, etc. The second preset number is preferably 2.

[0081] Further, the modification of the ammonia injection grid includes: simulating and calculating the resistance from the denitrification ammonia injection pipe to the spray holes of the selective catalytic reduction (SCR) reactor, and adjusting the number of openings of each ammonia injection pipe according to the calculation results.

[0082] The simulation calculation can use FLunt software or CFD software. By simulating and emulating to determine the resistance from the SCR denitrification ammonia injection pipe to the spray holes, and then adjusting the number of openings of each ammonia injection pipe to reduce the resistance of the dilution air system and reduce the ammonia slip.

[0083] The method of "sending a prompt message to the user" includes: sending a prompt message to the user through an intelligent terminal, and the intelligent terminal includes a smart phone; for example, sending a prompt message to the APP on the smart phone.

[0084] By sending a prompt message to the user, the present invention enables the user to timely know the specific reasons for the air preheater blockage and the rectification methods, and improves the stability of the unit operation.

[0085] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0086] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features indicated. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0087] Any process or method description represented in a flowchart or otherwise described herein can be understood to represent a module, segment, or portion of code including one or more executable instructions for implementing a customized logical function or process. The scope of the preferred embodiments of the present application includes additional implementations, where functions may be executed in a substantially simultaneous manner or in a reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0088] The logic and / or steps represented in a flowchart or otherwise described herein, for example, can be considered a sequenced list of executable instructions for implementing a logical function, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in connection with these instruction execution systems, apparatuses, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which a program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0089] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one of the following techniques known in the art or a combination thereof can be used: discrete logic circuits with logic gate circuits for implementing logic functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0090] Those of ordinary skill in the art can understand that all or part of the steps carried by the method of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0091] In addition, in each embodiment of the present application, each functional unit can be integrated in a processing module, or each unit can exist physically alone, or two or more units can be integrated in a module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0092] The above-mentioned storage medium can be a read-only memory, a magnetic disk, an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A method for preventing clogging of an air preheater, comprising the following steps: Step S100, obtaining the pressure difference before and after the flue gas side of the air preheater; Step S200, when the pressure difference is greater than the first preset value and lasts for at least the first preset time, the unit is controlled to perform soot blowing with a low-frequency and high-intensity soot blower; after the unit performs soot blowing with a low-frequency and high-intensity soot blower for the first preset number of times, the pressure difference is detected. If the pressure difference is greater than the second preset value and lasts for at least the second preset time, it is determined that the air preheater is blocked by ammonium bisulfate, and a pyrolysis operation is performed, wherein the second preset value is greater than the first preset value; the unit is controlled to perform a pyrolysis operation by raising the outlet temperature of the air preheater to T1 and maintaining it for a third preset time, and raising the average inlet temperature of the electric precipitator corresponding to the air preheater to T2 and maintaining it for a fourth preset time; the number of pyrolysis actions is counted, and if the number of pyrolysis actions exceeds the second preset number of times, the user sends a prompt message; Pyrolysis operation includes: exiting the following interlock protections: air preheater outlet temperature of 185℃ trips the corresponding side induced draft fan interlock, air preheater shutdown interlocks the air preheater inlet and outlet air smoke dampers interlock, air preheater shutdown interlocks the supply fan, induced draft fan, and primary fan interlock, absorption tower inlet smoke temperature of 155℃ boiler main fuel trips MFT interlock; air preheater outlet and inlet air smoke dampers are closed; boiler air smoke system primary air, supply air, induced draft fan communication dampers are closed, and the communication dampers are kept in the open state; Close the first and second air dampers at the air preheater outlet gradually and slowly. When the exhaust gas temperature is below 150℃, control the temperature rise to no more than 3℃ / min. When it is above 150℃, the temperature rise rate is less than 1℃ / min. Slowly close the second and second air dampers at the air preheater outlet according to the air preheater outlet temperature. When closing the second and second air dampers at the air preheater outlet, open the secondary air door in time to control the outlet pressure of the blower to no more than 2.7KPa to prevent the blower from surging. During the heating process of the air preheater, blow soot to the air preheater continuously. When the current fluctuation of the air preheater exceeds 10A or the current reaches 60A, the temperature rise stops, and the temperature rise continues when the current fluctuation is less than 5A and the current is less than 50A; When the exhaust gas temperature of the air preheater reaches 160℃, monitor the change of the differential pressure of the air preheater. When the differential pressure drops, the flue gas volume will increase, and the exhaust gas temperature will slowly increase automatically. Slowly open a secondary air door at the outlet of the air preheater to a certain opening, increase the secondary air volume, and control the exhaust gas temperature to continue to rise; Monitor the flue gas temperature at the dust collector inlet and the original flue gas temperature at the desulfurization inlet corresponding to the air preheater, and start the emergency spray when the temperature reaches 150°C; when the differential pressure no longer decreases within 15 minutes, the thermal decomposition of ammonium bisulfate in the air preheater is completed.

2. The anti-clogging method for an air preheater according to claim 1, characterized in that: T1 is 160° C., the third preset time is 4 hours, T2 is 160° C., and the fourth preset time is 20 hours.

3. The anti-clogging method for an air preheater according to claim 1, characterized in that: The first preset number is 3.

4. The anti-clogging method for an air preheater according to claim 1, characterized in that: The prompt information includes replacing the catalyst of the selective catalytic reduction SCR reactor and modifying the ammonia injection grid.

5. The anti-clogging method for an air preheater according to claim 4, characterized in that: The ammonia injection grid is modified, including: simulating and calculating the resistance from the deoxidized ammonia injection pipe to the injection hole of the selective catalytic reduction SCR reactor, and adjusting the number of openings of each ammonia injection pipe according to the calculation result.

6. The anti-clogging method for an air preheater according to claim 5, characterized in that: The method for sending prompt information to a user includes: sending prompt information to the user via a smart terminal.

7. The anti-clogging method for an air preheater according to claim 1, characterized in that: The second preset number is 2.

Images