CN114413275A - Method for treating blockage of air preheater and reducing flue pressure - Google Patents

Abstract

The invention relates to the technical field of flue gas conveying, and discloses a method for treating blockage of an air preheater and reducing flue pressure, which comprises the following steps: high-temperature flue gas is extracted from the outlet side of a denitration reactor at the tail of the boiler to a flue gas cavity of a flue gas heat exchanger, and cold secondary air is extracted from an outlet electric baffle of a blower to an air cavity of the flue gas heat exchanger; the high-temperature flue gas and the cold secondary air exchange heat in the flue gas heat exchanger to respectively obtain low-temperature flue gas and hot secondary air, the low-temperature flue gas is conveyed to the electric dust removal device, and meanwhile the hot secondary air is conveyed to the hot secondary air box. The method of the invention realizes the communication of the air ducts and the flues at the two sides of the boiler, improves the load carrying capacity of the single fan of the boiler during operation, and the temperature of the flue gas at the outlet of the flue gas heat exchanger is easy to control, and the problems of ammonium bisulfate blockage and the like can not occur.

Description

A method for dealing with blockage of air preheater and reducing flue pressure

technical field

The invention relates to the technical field of flue gas conveying, and more particularly to a method for dealing with blockage of an air preheater and reducing flue pressure.

Background technique

In order to make the fuel burn normally in the furnace, the air supply system of the current coal-fired boiler fume system must supply the air required for fuel combustion into the furnace, and use the air supply fan to overcome the flow generated by the air duct, air preheater and burner. resistance and provide the oxygen needed for the fuel to burn. The secondary air process is as follows: the air passes through the filter screen and the muffler, vertically enters the two axial-flow blowers for pressure, then enters the air preheater through the secondary air electric baffle at the inlet of the air preheater, and then enters the two air preheaters through the secondary air duct. The hot secondary air is preheated in the secondary air silo of the Junker-type three-silo air preheater, and then sent to the boiler hot secondary air box through the electric baffle of the outlet of the air preheater to enter the furnace to support combustion. In the flue gas system of the boiler, the high temperature flue gas from the flue at the tail of the furnace is extracted after removing NOx through the denitrification reactor, and then enters the flue gas cavity of the two Junker-type three-silo air preheaters through the electric baffle of the flue gas at the inlet of the air preheater. The primary air and secondary air are heated, and then enter the electrostatic precipitator to remove the dust in the flue gas. After being boosted by the induced draft fan, it enters the desulfurization device to remove the SO ₂ in the flue gas, and then is discharged to the atmosphere through the chimney.

The flue gas discharged from the coal-fired boiler needs to go through denitration, desulfurization and dust removal equipment before it can be discharged to the atmosphere. During the denitration process of the boiler flue gas, due to the excessive escape of ammonia, a large amount of ammonium hydrogen sulfate is accumulated at the cold end of the air preheater, which is easy to cause air preheater. The air preheater is blocked, the heat exchange efficiency of the air preheater is low, the exhaust gas temperature is high, the negative pressure of the furnace fluctuates greatly, the current of the induced draft fan is large, there is the risk of the fan stall and the boiler facing fire, and the boiler efficiency is low; in addition, it will also lead to the inlet of the induced draft fan. The flue pressure at high load exceeds the low limit, causing the boiler flue to deform or rupture, and the boiler load has to be reduced.

At present, reducing the differential pressure of the air preheater is mainly carried out by the following methods: first, strengthening steam soot blowing, that is, increasing the steam pressure of soot blowing and increasing the frequency of steam soot blowing, but the problem of large differential pressure of the air preheater still cannot be improved; Second, since the air and smoke system of medium and large coal-fired boilers basically adopts a double-column arrangement and a balanced ventilation method, the outlet temperature of the single-side air preheater is increased to above 160 ℃ to melt ammonium bisulfate (the melting point of ammonium bisulfate is 147 ℃) to reduce the air The differential pressure of the preheater, specifically taking the increase of the outlet temperature of the A air preheater as an example, increases the output of the A induced draft fan and reduces the output of the A blower, so that a large amount of flue gas heats a small amount of cold air to increase the flue gas temperature at the air preheater outlet, but This method has drawbacks in the practical application of thermal power plants, that is, when adjusting the supply air volume and flue gas volume of the boiler A side to increase the outlet temperature of the A side air preheater to melt ammonium hydrogen sulfate, the B side air preheater outlet temperature is due to the boiler supply air. The large amount and the small amount of flue gas caused the flue gas temperature at the outlet of the B air preheater to drop below 80 °C, which aggravated the accumulation and blockage of ammonium hydrogen sulfate in the air preheater on the B side, and further increased the differential pressure of the air preheater. Therefore, using this method to reduce the differential pressure of the air preheater is not ideal. Third, the air preheater is flushed with high-pressure water online to clear the blockage of the air preheater. The high-pressure water causes damage to the heat exchange elements of the air preheater, and the cold shock causes the rotor of the air preheater to deform and cause wear and jam. The incoming water raises the dew point of the flue gas.

SUMMARY OF THE INVENTION

The invention aims to solve the problems that the air preheater is blocked by ammonium hydrogen sulfate and the flue gas pressure exceeds the limit and cannot carry the rated load.

One object of the present invention is to provide a method for dealing with the blockage of the air preheater and reducing the pressure of the flue, by adding a flue gas heat exchanger to deal with the blockage of the air preheater and reducing the pressure of the flue, comprising the following steps:

(1) Extract the high-temperature flue gas from the outlet side of the denitration reactor at the tail of the boiler to the flue gas cavity of the flue gas heat exchanger, and at the same time extract the cold secondary air from the electric baffle at the outlet of the blower to the air cavity of the flue gas heat exchanger ;

(2) The high temperature flue gas and the cold secondary air are exchanged in the flue gas heat exchanger to obtain low temperature flue gas and hot secondary air respectively. The low temperature flue gas is sent to the electrostatic precipitator, and the hot secondary air is sent to the heat secondary air box;

By adjusting the volume of cold secondary air from the outlet of the blower to the air cavity of the flue gas heat exchanger and the volume of flue gas from the outlet of the high temperature flue gas denitrification reactor to the flue gas cavity of the flue gas heat exchanger, the blockage of the air preheater and the reduction of flue pressure.

Preferably, the air volume of the cold secondary air from the outlet of the blower to the air cavity of the flue gas heat exchanger is adjusted through the secondary air temperature adjusting baffle;

The amount of flue gas from the outlet of the high temperature flue gas denitration reactor to the flue gas chamber of the flue gas heat exchanger is adjusted by the flue pressure regulating baffle.

Preferably, the method for dealing with the blockage of the air preheater and reducing the pressure of the flue specifically includes the following steps:

(1) The flue gas on the A and B sides of the boiler tail respectively removes NOx through the denitration reactors on both sides. The denitrified flue gas is extracted through the pneumatic adjustment baffle to extract the high temperature flue gas, and then sent to the flue pressure adjustment baffle. The flue gas cavity of the flue gas heat exchanger conducts heat exchange, and the low-temperature flue gas after heat exchange passes through the pneumatic adjustment baffles to the electrostatic precipitators on both sides respectively;

(2) Extract the cold secondary air from the electric baffles at the outlet of the blower on both sides, and send the cold secondary air into the air cavity of the flue gas heat exchanger after passing through the pneumatic adjustment baffles on both sides for heat exchange. The secondary air returns to the hot secondary air box after passing through the secondary air temperature adjustment baffle and the secondary air pneumatic adjustment baffle.

Another object of the present invention is to provide a system for dealing with blockage of an air preheater and reducing flue pressure, including:

Flue gas heat exchanger, including flue gas cavity and air cavity;

The inlet of the flue gas cavity of the flue gas heat exchanger is communicated with the denitration reactor, and the outlet is communicated with the electrostatic precipitator; the inlet of the air cavity of the flue gas heat exchanger is communicated with the blower, and the outlet is communicated with the hot secondary air box;

Between the denitration reactor and the flue gas cavity of the flue gas heat exchanger, a flue gas pressure regulating baffle plate for controlling the flow of flue gas is arranged; the air between the hot secondary air box and the flue gas heat exchanger A secondary air temperature adjustment baffle for controlling the air volume is arranged between the cavities.

Preferably, the blower is provided with an electric baffle near the outlet, and a pneumatic adjustment baffle is arranged between the electric baffle of the blower and the air cavity of the flue gas heat exchanger to adjust the flue gas exchange. The air volume of the heater air cavity;

An electric baffle is arranged at the outlet of the electrostatic precipitator, and a pneumatic adjustment baffle is arranged between the electrostatic precipitator and the flue gas heat exchanger to adjust the flow rate of the flue gas at the outlet of the flue of the boiler.

Preferably, the flue gas heat exchanger is a shell and tube type flue gas heat exchanger.

Preferably, there are at least two of the denitration reactor, the electrostatic precipitator, and the blower, which are used for coordinating the transportation of flue gas generated by multiple flue outlets at the tail of the boiler.

Preferably, the denitration reactor includes a first denitration reactor and a second denitration reactor;

The inlet of the first denitration reactor is communicated with the flue outlet on the A side of the boiler tail, and the inlet of the second denitration reactor is communicated with the flue outlet on the B side of the boiler tail;

The outlet pipes of the first denitration reactor and the second denitration reactor are collected into the same pipe and then communicated to the flue gas cavity of the flue gas heat exchanger.

Preferably, the electrostatic precipitator includes a first electrostatic precipitator and a second electrostatic precipitator;

The inlet of the first electrostatic precipitator is communicated with the outlet of the flue gas cavity of the flue gas heat exchanger, and is used to transport the flue gas at the A-side flue outlet of the boiler tail; the inlet of the second electrostatic precipitator is connected to the The outlet of the flue gas chamber of the flue gas heat exchanger is communicated, and is used to transport the flue gas from the outlet of the flue on the B side of the boiler tail.

Preferably, the flue gas passing through the flue gas cavity of the flue gas heat exchanger is output from the same pipeline and then divided into the first electrostatic precipitator and the second electrostatic precipitator through different pipelines.

Preferably, the blower includes a first blower and a second blower; generally, the air from the blower in the boiler system is called secondary air;

The air supply ducts of the first blower and the second blower are all collected into the same duct and then communicated to the air cavity of the flue gas heat exchanger.

Preferably, the system further includes:

The first air preheater is provided with a secondary air silo and a flue gas silo, the inlet of the flue gas silo of the first air preheater is connected to the first denitration reactor, and the outlet is connected to the first electrostatic precipitator, so The inlet of the secondary air silo of the first air preheater is connected to the first blower, and the outlet is connected to the hot secondary air box;

The second air preheater is provided with a secondary air silo and a flue gas silo; the inlet of the flue gas silo of the second air preheater is connected to the second denitration reactor, and the outlet is connected to the second electrostatic precipitator, so The inlet of the secondary air silo of the second air preheater is connected to the second blower, and the outlet is connected to the hot secondary air box.

Preferably, the system further includes:

a first induced draft fan, communicated with the outlet of the first electrostatic precipitator, and used for conveying the flue gas at the A-side flue outlet of the boiler tail;

The second induced draft fan is communicated with the outlet of the second electrostatic precipitator, and is used for conveying the flue gas at the B-side flue outlet at the tail of the boiler.

Preferably, the first blower and the second blower are provided with electric baffles near the outlet; and a pneumatic adjustment block is arranged between the electric baffle of the first blower and the air cavity of the flue gas heat exchanger a plate for adjusting the air volume of the first blower entering the air cavity of the flue gas heat exchanger; a pneumatic adjustment baffle is arranged between the electric baffle of the second blower and the air cavity of the flue gas heat exchanger is used to adjust the air volume of the second blower entering the air cavity of the flue gas heat exchanger.

Preferably, an electric baffle is arranged at the outlet of the first electrostatic precipitator and the second electrostatic precipitator; a pneumatic adjustment baffle is arranged between the first electrostatic precipitator and the flue gas heat exchanger. The plate is used to adjust the flow rate of the flue gas at the A-side flue outlet at the boiler tail; a pneumatic adjustment baffle is arranged between the second electrostatic precipitator and the flue gas heat exchanger, which is used to adjust the B-side flue at the boiler tail The flow of flue gas at the outlet.

Preferably, a pneumatic adjustment baffle is arranged between the first denitration reactor, the second denitration reactor and the flue pressure adjustment baffle for extracting high temperature flue gas to the flue gas for heat exchange in the device.

Preferably, a pressure gauge is provided near the inlet side of the first electrostatic precipitator for measuring the pressure of the flue on the A side of the boiler tail, and a pressure gauge is provided near the inlet side of the second electrostatic precipitator for measuring the boiler pressure Tail B side flue pressure.

Preferably, a temperature measuring device is provided near the outlet side of the air cavity of the flue gas heat exchanger for measuring the secondary air temperature at the outlet of the flue gas heat exchanger.

Preferably, an electric baffle is provided between the first denitration reactor and the flue gas silo of the first air preheater, which is used to isolate the flue gas from the A-side flue outlet of the boiler tail from entering the first air preheater A flue gas silo; an electric baffle is arranged between the hot secondary air box and the secondary air silo of the first air preheater, which is used to isolate the hot secondary air from flowing backward into the secondary air of the first air preheater warehouse.

An electric baffle is arranged between the second denitration reactor and the flue gas bin of the second air preheater, which is used to isolate the flue gas from the B side flue outlet of the boiler tail from entering the flue gas bin of the second air preheater. An electric baffle is arranged between the hot secondary air box and the secondary air silo of the second air preheater, which is used to isolate the hot secondary air from flowing backward into the secondary air silo of the second air preheater.

The present invention provides a method for dealing with blockage of an air preheater and reducing flue pressure. Compared with the prior art, its beneficial effects are:

The invention solves the phenomenon that the flue gas temperature at the outlet of the air preheater on the other side is too low when the unit online increases the outlet temperature of the air preheater on one side and reduces the differential pressure, and can reduce the amount of flue gas flowing through the air preheater to reduce the negative pressure of the tail flue. to solve the problem that the unit cannot carry the rated load due to the high differential pressure of the air preheater or the blockage of the flue due to the accumulation of ash in the flue;

The system of the invention realizes the connection of the air ducts and flue ducts on both sides of the boiler, improves the load-bearing capacity of a single blower of the boiler during operation, and the flue gas temperature at the outlet of the flue gas heat exchanger is easy to control, and the blockage of ammonium hydrogen sulfate will not occur. It has a good application prospect for coal-fired boilers.

Description of drawings

FIG. 1 is a schematic flow chart of the system of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

A system for dealing with clogging of an air preheater and reducing flue pressure, comprising:

Flue gas heat exchanger, including flue gas cavity and air cavity;

The inlet of the flue gas cavity of the flue gas heat exchanger is communicated with the denitration reactor, and the outlet is communicated with the electrostatic precipitator; the inlet of the air cavity of the flue gas heat exchanger is communicated with the blower, and the outlet is communicated with the hot secondary air box;

Between the denitration reactor and the flue gas cavity of the flue gas heat exchanger, a flue gas pressure regulating baffle plate for controlling the flow of flue gas is arranged; the air between the hot secondary air box and the flue gas heat exchanger A secondary air temperature adjustment baffle for controlling the air volume is arranged between the cavities.

Preferably, the blower is provided with an electric baffle near the outlet, and a pneumatic adjustment baffle is arranged between the electric baffle of the blower and the air cavity of the flue gas heat exchanger to adjust the flue gas exchange. The air volume of the heater air cavity;

An electric baffle is arranged at the outlet of the electrostatic precipitator, and a pneumatic adjustment baffle is arranged between the electrostatic precipitator and the flue gas heat exchanger to adjust the flow rate of the flue gas at the outlet of the flue of the boiler.

In order to further optimize the above technical solution, the flue gas heat exchanger is a shell and tube type flue gas heat exchanger.

As shown in FIG. 1 , in some embodiments of the present invention, there are two denitration reactors, two electrostatic precipitators, and two blowers, which are used to convey the smoke generated by the multiple flue outlets at the tail of the boiler. gas.

Wherein, the denitration reactor includes a first denitration reactor and a second denitration reactor;

The inlet of the first denitration reactor is communicated with the flue outlet on the A side of the boiler tail, and the inlet of the second denitration reactor is communicated with the flue outlet on the B side of the boiler tail;

The outlet pipes of the first denitration reactor and the second denitration reactor are collected into the same pipe and then communicated to the flue gas cavity of the flue gas heat exchanger.

In some embodiments of the present invention, the electrostatic precipitator includes a first electrostatic precipitator and a second electrostatic precipitator;

The inlet of the first electrostatic precipitator is communicated with the outlet of the flue gas cavity of the flue gas heat exchanger, and is used to transport the flue gas at the A-side flue outlet of the boiler tail; the inlet of the second electrostatic precipitator is connected to the The outlet of the flue gas chamber of the flue gas heat exchanger is communicated, and is used to transport the flue gas from the outlet of the flue on the B side of the boiler tail.

In some embodiments of the present invention, the flue gas passing through the flue gas chamber of the flue gas heat exchanger is output from the same pipeline and then split to the first electrostatic precipitator and the second electrostatic precipitator through different pipelines.

In some embodiments of the present invention, the blower includes a first blower and a second blower;

The air supply ducts of the first blower and the second blower are all collected into the same duct and then communicated to the air cavity of the flue gas heat exchanger.

In some embodiments of the present invention, the system further includes:

The first air preheater is provided with a secondary air silo and a flue gas silo, the inlet of the flue gas silo of the first air preheater is connected to the first denitration reactor, and the outlet is connected to the first electrostatic precipitator, so The inlet of the secondary air silo of the first air preheater is connected to the first blower, and the outlet is connected to the hot secondary air box;

The second air preheater is provided with a secondary air silo and a flue gas silo; the inlet of the flue gas silo of the second air preheater is connected to the second denitration reactor, and the outlet is connected to the second electrostatic precipitator, so The inlet of the secondary air silo of the second air preheater is connected to the second blower, and the outlet is connected to the hot secondary air box.

In some embodiments of the present invention, the system further includes:

a first induced draft fan, communicated with the outlet of the first electrostatic precipitator, and used for conveying the flue gas at the A-side flue outlet of the boiler tail;

The second induced draft fan is communicated with the outlet of the second electrostatic precipitator, and is used for conveying the flue gas at the B-side flue outlet at the tail of the boiler.

In some embodiments of the present invention, the first blower and the second blower are provided with electric baffles 1 and 3 near the outlet to isolate the blower; the electric baffle 1 of the first blower is different from the A pneumatic adjustment baffle 9 is arranged between the air chambers of the flue gas heat exchanger, which is used to adjust the air volume of the first blower entering the air chamber of the flue gas heat exchanger; the electric baffle 3 of the second blower is connected to the A pneumatic adjustment baffle 12 is arranged between the air chambers of the flue gas heat exchanger to adjust the air volume of the second blower entering the air chamber of the flue gas heat exchanger.

In some embodiments of the present invention, electric baffles 6 and 8 are provided at the exits of the first electrostatic precipitator and the second electrostatic precipitator; the first electrostatic precipitator is exchanged with the flue gas. A pneumatic adjustment baffle 14 is arranged between the heaters, which is used to adjust the flow rate of the flue gas at the A-side flue outlet at the tail of the boiler; a pneumatic adjustment baffle 16 is arranged between the second electrostatic precipitator and the flue gas heat exchanger. , which is used to adjust the flow of flue gas at the B-side flue outlet at the tail of the boiler.

In some embodiments of the present invention, pneumatic adjustment baffles 13 and 15 are provided between the first denitration reactor, the second denitration reactor and the flue pressure adjustment baffle 17 for extraction High temperature flue gas into the flue gas heat exchanger.

In some embodiments of the present invention, a pressure gauge is provided near the inlet side of the first electrostatic precipitator, which is used to measure the flue pressure on the A side of the boiler tail, and a pressure gauge is provided near the inlet side of the second electrostatic precipitator. The table is used to measure the flue pressure on the B side of the boiler tail.

In some embodiments of the present invention, a temperature measuring device is provided near the outlet side of the air cavity of the flue gas heat exchanger, for measuring the temperature of the secondary air at the outlet of the flue gas heat exchanger.

In some embodiments of the present invention, an electric baffle 5 is provided between the first denitration reactor and the flue gas bin of the first air preheater, which is used to isolate the entry of flue gas from the A-side flue outlet at the tail of the boiler. The first air preheater flue gas silo; an electric baffle 2 is arranged between the hot secondary air box and the secondary air silo of the first air preheater, which is used to isolate the hot secondary air from flowing back into the The first air preheater and the secondary air chamber.

An electric baffle 7 is arranged between the second denitration reactor and the flue gas silo of the second air preheater, which is used to isolate the flue gas from the B side flue outlet of the boiler tail from entering the second air preheater flue gas There is an electric baffle 4 between the hot secondary air box and the secondary air chamber of the second air preheater, which is used to isolate the hot secondary air from backflow into the secondary air chamber of the second air preheater .

Based on the system for treating the blockage of the air preheater and reducing the pressure of the flue provided by the above-mentioned embodiments of the present invention, the method for treating the blockage of the air preheater and reducing the pressure of the flue includes the following steps:

(1) The flue gas on the A and B sides of the boiler tail respectively removes NOx through the denitration reactors on both sides. The denitrified flue gas is extracted through the pneumatic adjustment baffle to extract the high temperature flue gas, and then sent to the flue pressure adjustment baffle. The flue gas cavity of the flue gas heat exchanger conducts heat exchange, and the low-temperature flue gas after heat exchange passes through the pneumatic adjustment baffles to the electrostatic precipitators on both sides respectively;

(2) Extract the cold secondary air from the electric baffles at the outlet of the blower on both sides, and send the cold secondary air into the air cavity of the flue gas heat exchanger after passing through the pneumatic adjustment baffles on both sides for heat exchange. The secondary air returns to the hot secondary air box after passing through the secondary air temperature adjustment baffle and the secondary air pneumatic adjustment baffle.

Specifically, the application mode of the system for dealing with the blockage of the air preheater and reducing the flue pressure of the present invention will be described in detail below in conjunction with the specific operating conditions.

First, the present invention solves the problem that the outlet temperature of the air preheater on the other side is too low when the unit online increases the outlet temperature of the air preheater on one side and reduces the differential pressure.

Taking the temperature of the single-side air preheater to melt ammonium hydrogen sulfate to reduce the differential pressure of the first air preheater as an example, appropriately reduce the output of the first blower, increase the output of the first induced draft fan, increase the smoke temperature at the outlet of the first air preheater, and at the same time increase the output of the first air preheater. The output of the second air blower reduces the output of the second induced draft fan, and the flue gas temperature at the outlet of the second air preheater decreases. During the adjustment process, the flue gas temperature at the outlet of the second air preheater is controlled not to be lower than the dew point of the flue gas. At this time, the second denitration reactor is opened until the smoke The pneumatic adjustment baffle 15 of the flue gas cavity of the gas heat exchanger and the pneumatic adjustment baffles 14 and 16 on both sides of the flue gas cavity of the flue gas heat exchanger to the inlet of the electrostatic precipitator, and then open the outlet of the first blower and the flue gas heat exchanger The pneumatic adjustment baffle 9 between the air chambers and the pneumatic adjustment baffle 10 from the air chamber of the flue gas heat exchanger to the hot secondary air box, adjust the flue pressure adjustment baffle 17 to control the smoke temperature at the outlet of the second air preheater not lower than The dew point of the flue gas is adjusted, and the secondary air temperature adjustment baffle 11 continues to increase the temperature of the cold end of the first air preheater.

After the differential pressure of the first air preheater returns to normal, adjust the output balance of the fans on both sides, and open the pneumatic adjustment baffle 13 from the first denitration reactor of the boiler to the flue gas heat exchanger and the outlet of the second blower to the flue gas heat exchanger. Pneumatically adjust the baffle 12, adjust the flue pressure adjustment baffle 17 and the secondary air temperature adjustment baffle 11 to control the outlet flue gas temperature of the flue gas heat exchanger to be greater than 160 ℃ to melt ammonium hydrogen sulfate and be taken away by the flue gas. After the differential pressure of the heat exchanger is normal, close the above-opened valve to exit the flue gas heat exchanger.

Second, the invention can reduce the amount of flue gas flowing through the air preheater to reduce the negative pressure of the tail flue, so as to solve the problem that the flue pressure of the unit cannot be rated due to high differential pressure of the air preheater or clogging of the flue. load problem.

When the flue pressure exceeds the low limit under high load, open the pneumatic adjustment baffles 13 and 15 between the first denitration reactor, the second denitration reactor and the flue gas cavity of the flue gas heat exchanger and the flue gas heat exchanger to the electrostatic precipitator The pneumatic adjustment baffles 14 and 16 on both sides of the inlet of the device, and then turn on the pneumatic adjustment baffles 9 and 12 between the outlet of the first blower and the second blower and the air cavity of the flue gas heat exchanger and the flue gas heat exchanger to the second heat exchanger. The pneumatic adjustment baffle 10 between the secondary air boxes, the flue gas pressure adjustment baffle 17 and the secondary air temperature adjustment baffle 11 are adjusted to control the flue gas heat exchanger outlet flue gas temperature, and the flue gas heat exchanger has good flue gas flow performance The advantage of the air preheater is to reduce the flue gas volume of the first air preheater and the second air preheater, the resistance of the air preheater becomes smaller, the negative pressure of the flue at the inlet of the induced draft fan is improved, the deformation and tearing of the flue is avoided, and the primary fan is reduced. , the power consumption of the blower and the induced draft fan, improve the efficiency of the boiler, and at the same time improve the load capacity of the unit.

Third, the system of the present invention realizes the connection of the air ducts and flue ducts on both sides of the boiler, and improves the load capacity when a single fan of the unit fails.

If the first induced draft fan fails and shuts down, the flue gas electric baffle 6 at the inlet of the first induced draft fan is closed, and the load capacity of the one-sided wind and smoke system is lower than 50% due to the influence of the differential pressure of the air preheater, and the flue gas heat exchange is adopted. The air and smoke duct can realize the bilateral operation of the air and smoke system. Open the flue gas chamber of the flue gas heat exchanger to the flue pneumatic adjustment baffles 14 and 16 on both sides of the inlet of the electrostatic precipitator. 5. The pneumatic adjustment baffles 14 and 16 of the flue on both sides of the inlet of the first air preheater and the electrostatic precipitator flow to the inlet pipe of the second electrostatic precipitator. The output of the supply fan and the primary fan on the A side is appropriately adjusted to a small value, and the load capacity of the boiler air and smoke system is only limited by the output of the second induced draft fan. Since the diversion of the first air preheater reduces the flue gas flow of the second air preheater, a single unit The load capacity of the fan operation is correspondingly improved.

In the same way, after the failure of the first blower, the cold secondary air at the outlet of the second blower is heated by the first air preheater through the pneumatic adjustment baffles 12 and 9, and the cold primary air on the A side is heated at the same time, and the air and smoke system is loaded. The capacity is only limited by the output of the second blower, and the load-carrying capacity of the boiler is improved.

In addition, if the first blower and the first induced draft fan are repaired at the same time, the load capacity of the fan will be limited due to the influence of the differential pressure of the air preheater. Adjust the operation mode of the primary fan, the primary fan on the A side supplies the primary air for cooling, the primary fan on the B side supplies the primary air for heating, and the cold secondary air from the outlet of the second blower enters the air cavity of the flue gas heat exchanger through the pneumatic adjustment baffle 12 for heating. Then it enters the hot secondary air box through the secondary air temperature adjustment baffle 11 and the pneumatic adjustment baffle 10 at the outlet of the flue gas heat exchanger. At the same time, the outlet of the first denitration reactor is opened to extract the high temperature flue gas through the flue gas pneumatic adjustment baffle 13. Then it is sent into the flue gas cavity of the flue gas heat exchanger through the pressure regulating baffle 17 of the tail flue, and the low-temperature flue gas passes through the pneumatic regulating baffle 16 to the inlet flue of the second electrostatic precipitator, and is put into the flue gas heat exchanger for operation. The secondary air on the B side is divided, and the load capacity of the boiler is improved, which depends on the output of the second blower and the second induced draft fan. At the same time, the flue gas on the A side of the boiler tail is circulated to avoid the failure of the first induced draft fan. The flue gas can not flow and the ash accumulation causes the flue collapse accident.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. As for the solutions disclosed in the examples, since they correspond to the methods disclosed in the examples, the descriptions are relatively simple, and the relevant parts can be referred to the description of the method section.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A method for treating air preheater blockage and reducing flue pressure is characterized in that a flue gas heat exchanger is added to treat air preheater blockage and reduce flue pressure, and comprises the following steps:

(1) high-temperature flue gas is extracted from the outlet side of a denitration reactor at the tail of the boiler to a flue gas cavity of a flue gas heat exchanger, and cold secondary air is extracted from an outlet electric baffle of a blower to an air cavity of the flue gas heat exchanger;

(2) the high-temperature flue gas and the cold secondary air exchange heat in a flue gas heat exchanger to respectively obtain low-temperature flue gas and hot secondary air, the low-temperature flue gas is conveyed to an electric dust removal device, and meanwhile the hot secondary air is conveyed to a hot secondary air box;

the blockage of the air preheater and the pressure of the flue are reduced by adjusting the air volume of cold secondary air from the outlet of the air feeder to the air cavity of the flue gas heat exchanger and the air volume of flue gas from the outlet of the high-temperature flue gas denitration reactor to the air cavity of the flue gas heat exchanger.

2. The method of claim 1 wherein the amount of cold overfire air from the blower outlet to the flue gas heat exchanger air chamber is adjusted by means of an overfire air temperature adjusting damper;

the flue gas volume from the outlet of the high-temperature flue gas denitration reactor to the flue gas cavity of the flue gas heat exchanger is adjusted by a flue pressure adjusting baffle plate.

3. The method of claim 1 for handling air preheater plugging and stack pressure reduction, comprising the steps of:

(1) flue gas at the side of the boiler tail A, B passes through denitration reactors at two sides respectively to remove NOx, the denitration treated flue gas passes through a pneumatic adjusting baffle to extract high-temperature flue gas, then passes through a flue pressure adjusting baffle to be sent into a flue gas cavity of a flue gas heat exchanger to exchange heat, and the low-temperature flue gas after heat exchange passes through the pneumatic adjusting baffle to be introduced into electric dust removal devices at two sides respectively;

(2) the cold secondary air is extracted from the outlet electric baffles of the air blowers on the two sides, the cold secondary air is sent into the air cavity of the flue gas heat exchanger for heat exchange through the pneumatic adjusting baffles on the two sides, and the heated secondary air returns to the hot secondary air box after passing through the secondary air temperature adjusting baffle and the secondary air pneumatic adjusting baffle.

4. A system for handling air preheater blockage and flue pressure reduction, comprising:

the smoke heat exchanger comprises a smoke cavity and an air cavity;

an inlet of a flue gas cavity of the flue gas heat exchanger is communicated with the denitration reactor, and an outlet of the flue gas cavity is communicated with the electric dust removal device; an inlet of an air cavity of the flue gas heat exchanger is communicated with the air feeder, and an outlet of the air cavity is communicated to the hot secondary air box;

a flue pressure adjusting baffle plate for controlling the flow of flue gas is arranged between the denitration reactor and the flue gas cavity of the flue gas heat exchanger; and a secondary air temperature adjusting baffle plate for controlling the air quantity is arranged between the hot secondary air box and the air cavity of the flue gas heat exchanger.

5. The system for handling air preheater blockage and flue pressure reduction as recited in claim 4 wherein said blower is provided with an electrically powered damper adjacent the outlet and a pneumatically adjustable damper is provided between said electrically powered damper of said blower and said flue gas heat exchanger air chamber for adjusting the air volume of said flue gas heat exchanger air chamber;

electric baffle is arranged at the outlet of the electric dust removal device, and a pneumatic adjusting baffle is arranged between the electric dust removal device and the flue gas heat exchanger and used for adjusting the flow of flue gas at the outlet of a tail flue of the boiler.

6. The system for treating air preheater blocking and flue pressure reduction of claim 4 or 5, wherein the denitration reactor, the electric dust removal device and the air feeder are provided with at least two air blowers for matching with flue gas generated by a plurality of flue outlets at the tail of the conveying boiler.

7. The system for treating air preheater blockage and flue pressure reduction of claim 6, wherein said denitration reactor comprises a first denitration reactor and a second denitration reactor;

the inlet of the first denitration reactor is communicated with the flue outlet at the A side of the tail part of the boiler, and the inlet of the second denitration reactor is communicated with the flue outlet at the B side of the tail part of the boiler;

and outlet pipelines of the first denitration reactor and the second denitration reactor are converged to the same pipeline and then communicated to a smoke gas cavity of the smoke gas heat exchanger.

8. The system for handling air preheater blockage and flue pressure reduction of claim 7, wherein the electrical dust removal device comprises a first electrical dust removal device and a second electrical dust removal device;

an inlet of the first electric dust removal device is communicated with an outlet of a flue gas cavity of the flue gas heat exchanger and is used for conveying flue gas at an outlet of a flue at the A side of the tail part of the boiler; an inlet of the second electric dust removal device is communicated with an outlet of a flue gas cavity of the flue gas heat exchanger and is used for conveying flue gas at an outlet of a flue at the side B of the tail part of the boiler;

and the flue gas passing through the flue gas cavity of the flue gas heat exchanger is output by the same pipeline and then is shunted to the first electric dust removal device and the second electric dust removal device through different pipelines.

9. The system for handling air preheater plugging and flue pressure reduction of claim 7, wherein said blower comprises a first blower and a second blower;

and air supply pipelines of the first air blower and the second air blower are converged to the same pipeline and then communicated to an air cavity of the flue gas heat exchanger.

10. The system for handling air preheater blockage and flue pressure reduction of claim 9, further comprising:

the second air preheater is provided with a second air bin and a flue gas bin, the inlet of the flue gas bin of the second air preheater is communicated with the second denitration reactor, and the outlet of the flue gas bin of the second air preheater is communicated to the second electric dust removal device;

the second air preheater is provided with a secondary air bin and a flue gas bin; an inlet of a flue gas bin of the second air preheater is communicated with the second denitration reactor, and an outlet of the flue gas bin is communicated with the second electric dust removal device;

the first induced draft fan is communicated with an outlet of the first electric dust removal device and is used for conveying flue gas at an outlet of a flue at the A side of the tail part of the boiler;

and the second induced draft fan is communicated with an outlet of the second electric dust removal device and is used for conveying flue gas at a flue outlet at the side B of the tail part of the boiler.

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