Circulating fluidized bed boiler bunker high temperature circulating ash adjacent furnace heating system and method

Abstract

The present application relates to a kind of circulating fluidized bed boiler bunker type high temperature circulating ash adjacent furnace heating system, including at least two circulating fluidized bed boilers, each two circulating fluidized bed boilers are equipped with a buffer bin, and the hearth of each circulating fluidized bed boiler is connected by first feed pipe and second feed pipe;The end of the discharge pipeline of each buffer bin is divided into two branches and is connected to first feed pipe and second feed pipe respectively;The buffer bin, first feed pipe and second feed pipe are connected to compressed air storage tank by compressed air pipeline, and the compressed air storage tank is connected to air compressor.The heating method using the system is also included.The present application uses high temperature bed material in the circulating fluidized bed boiler that has been operated to heat the circulating fluidized bed boiler that is about to start, rapidly increases the bed material temperature in the boiler to be started, and improves the boiler start-up speed;The buffer bin is used to store high temperature bed material when the boiler is running, so that the boiler load can be quickly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of heating of circulating fluidized bed boilers, and particularly relates to a high-temperature circulating ash adjacent furnace heating system and method for a circulating fluidized bed boiler. BACKGROUND

[0002] A circulating fluidized bed boiler blows up coal particles, biomass and other fuels and bed materials from the bottom of the furnace by fluidizing air, so that the particles are in a fluidized state and burn. The flue gas carrying part of the fine particles leaves the furnace and enters the gas-solid separator, the separator captures the particles in the fly ash, and returns to the furnace through the return material device, forming a solid particle circulation. There is a large amount of inert solid particle bed material in the furnace, mainly composed of ash left over after coal combustion, which does not participate in the combustion reaction. Because the high-temperature bed material has strong heat storage capacity, it increases the residence time of the fuel in the furnace, and has high combustion efficiency, so the circulating fluidized bed boiler has the characteristics of wide fuel application range; the circulating fluidized bed boiler can stably burn at a relatively low combustion temperature (800-900℃), and the generation of nitrogen oxides is lower than that of a pulverized coal boiler; by adding limestone in the furnace, sulfur dioxide can be removed during the combustion process, greatly reducing the desulfurization cost. Based on the above advantages, the circulating fluidized bed boiler is the best choice for large-scale clean use of high-sulfur and high-ash coal, gangue, washed medium coal, coal slime and biomass fuels. In recent years, the circulating fluidized bed boiler has been developing towards large-scale and high-parameter.

[0003] However, the circulating fluidized bed boiler has a large amount of bed material in the furnace, and the thermal inertia is large, which also has certain problems compared with other forms of boilers:

[0004] 1. Long start-up time and high energy consumption. Because there are hundreds of tons of inert solid particle bed material in the boiler, during the start-up process of the boiler, the bed material in the furnace needs to be heated to a certain temperature first to ensure stable combustion of the fuel in the furnace, so the start-up time of the boiler is relatively long and the energy consumption is relatively high;

[0005] 2. Slow load regulation. During the operation of the boiler, due to the large amount of solid particles in the furnace, the furnace temperature is relatively stable, and during the load regulation process, the furnace temperature and the heat transfer coefficient change relatively slowly, resulting in relatively slow load change.

[0006] With the implementation of the carbon peak and carbon neutral strategies, wind power, solar power and other new energy technologies are becoming the main power generation technologies, and the peak shaving flexibility of traditional coal-fired power plants is being further improved, so it is urgent to improve the load regulation rate of circulating fluidized bed units. SUMMARY

[0007] The application provides a circulating fluidized bed boiler storage bin type high-temperature circulating ash adjacent furnace heating system and method to solve the technical problems of slow start and slow load regulation in the prior art.

[0008] The application comprises the following technical scheme: a circulating fluidized bed boiler storage bin type high-temperature circulating ash adjacent furnace heating system comprises at least two circulating fluidized bed boilers, each of which is provided with a buffer bin, and the hearths of each circulating fluidized bed boiler are connected through a first material conveying main pipe and a second material conveying main pipe; the end of the material outlet pipeline of each buffer bin is divided into two branches and connected to the first material conveying main pipe and the second material conveying main pipe respectively; the buffer bin, the first material conveying main pipe and the second material conveying main pipe are connected to a compressed air storage tank through a compressed air pipeline, and the compressed air storage tank is connected to an air compressor.

[0009] Through the arrangement of the ash conveying pipeline and the compressed air system, the bed material particles in the hearths of the two circulating fluidized bed boilers can be exchanged with each other; under the premise that one circulating fluidized bed boiler is in normal operation, the system can rapidly heat the solid particles in the other circulating fluidized bed boiler, so that the function of rapid start and rapid load regulation is realized.

[0010] Further, the buffer bin and the hearth of the corresponding circulating fluidized bed boiler are connected through a feeding pipeline, the interface position of the feeding pipeline and the hearth is higher than the lower contraction section of the hearth, and a feeding plug-in door is arranged on the feeding pipeline.

[0011] Further, the interface position of the feeding pipeline and the buffer bin is slightly lower than the interface position of the feeding pipeline and the hearth, so that the material can flow smoothly, and the feeding pipeline is inclined from the side of the hearth to the side of the buffer bin.

[0012] Further, the bottom of the buffer bin is connected to the material outlet pipeline, a material outlet plug-in door is arranged on the material outlet pipeline close to the outlet of the buffer bin, and the lower part of the buffer bin is in a contraction shape, so that the bed material can flow out.

[0013] Further, one control material plug-in door is arranged on each branch of the material outlet pipeline close to the first material conveying main pipe or the second material conveying main pipe.

[0014] Further, the first material conveying main pipe and the second material conveying main pipe are arranged at the bottom of the hearth of the circulating fluidized bed boiler, and the connection points of the first material conveying main pipe and the second material conveying main pipe and the hearth are lower than the bottom end of the buffer bin.

[0015] Further, a material conveying plug-in door is arranged near the connection points of the first material conveying main pipe and the second material conveying main pipe and each hearth.

[0016] Further, the compressed air tank is connected with several compressed air pipes, and a total valve is arranged on each compressed air pipe; each compressed air pipe has three branches, and is connected to the buffer bin, the first material conveying main pipe and the second material conveying main pipe; and an air valve is arranged on each branch.

[0017] Further, according to the need of material conveying, the compressed air pipe can be provided with more branches, and is connected to multiple positions of the buffer bin, the first material conveying main pipe and the second material conveying main pipe.

[0018] Further, when the number n of the circulating fluidized bed boilers is greater than 2, the first material conveying main pipe and the second material conveying main pipe each have n branches, and each branch is connected to the hearth of one circulating fluidized bed boiler.

[0019] The circulating fluidized bed boiler storage type high-temperature circulating ash hearth heating method uses the above heating system, and comprises the following steps: firstly, high-temperature material in the hearth of a normally running circulating fluidized bed boiler is transported under the action of compressed air, sequentially passes through the feeding pipe matched with the boiler, the buffer bin, the discharging pipe, enters the hearth of a circulating fluidized bed boiler to be started through the first material conveying main pipe, and the solid particle bed material in the hearth is rapidly heated; then low-temperature material in the hearth of the circulating fluidized bed boiler to be started sequentially passes through the feeding pipe matched with the boiler, the buffer bin, the discharging pipe, enters the hearth of the normally running circulating fluidized bed boiler through the second material conveying main pipe; at this time, the coal supply amount of the normally running circulating fluidized bed boiler is increased, the temperature in the hearth is kept unchanged, and other boilers are started at the same time.

[0020] After the boiler is normally running, when any circulating fluidized bed boiler in the system needs to rapidly increase the load, the operation steps are the same as those of the auxiliary boiler rapid starting; when any circulating fluidized bed boiler in the system needs to rapidly decrease the load, the circulating ash is sent into the matched buffer bin, and then the boiler load decreasing speed can be increased.

[0021] The present application has the advantages and positive effects that:

[0022] 1. The present application uses the high-temperature bed material in the running circulating fluidized bed boiler to heat the circulating fluidized bed boiler to be started, can rapidly increase the bed material temperature in the hearth of the boiler to be started, makes the bed material reach the ignition condition, and then increases the boiler starting speed. Assuming that the bed material flow is 500 kg / s, the bed material temperature can reach 600 DEG C in 10 minutes, meets the combustion condition, and the starting time of the original equipment can be reduced by 80%.

[0023] 2. For boilers that provide high-temperature bed material, appropriately increasing the amount of coal and returning the cold bed material from the adjacent boiler can ensure that the boiler output is not reduced. The bed material in the boiler to be started is equivalent to absorbing the heat of the coal in the adjacent boiler to raise its temperature. Compared with the traditional air duct burner burning oil or natural gas to raise the bed material temperature, tens of thousands of yuan can be saved in one start-up.

[0024] 3. This invention utilizes a buffer silo to store high-temperature bed material during boiler operation, which can effectively reduce the radiation effect of gas-solid two-phase flow convection in the furnace, allowing the boiler load to drop rapidly. The rapid start-up and rapid load reduction of the boiler are beneficial to grid regulation. Against the backdrop of the continuous increase in wind and solar power generation, it can improve the flexibility of thermal power, which is of great significance for achieving the strategic goals of carbon peaking and carbon neutrality.

[0025] 4. During the heat exchange process of the water-cooled walls and convective heating surfaces inside the furnace, the particles participating in the circulation have a significant impact on the heat transfer coefficient. The interface between the discharge pipe and the furnace in this invention is higher than the lower contraction section of the furnace, which can collect smaller solid particles carried by the gas to the upper part of the furnace that participate in the circulation. Meanwhile, larger particles that cannot participate in the circulation at the bottom of the furnace cannot enter the adjacent furnace conveying system, thus allowing for faster load adjustment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0027] In the diagram, 1-First circulating fluidized bed boiler; 10-First furnace; 11-First feed pipe; 12-First buffer silo; 13-First discharge pipe; 14-First compressed air pipe; 15-First main valve; 101-First feed gate; 102-First discharge gate; 103-First conveying gate; 104-Second conveying gate; 105-First material control gate; 106-Second material control gate;

[0028] 2-Second circulating fluidized bed boiler; 20-Second furnace; 21-Second feed pipe; 22-Second buffer silo; 23-Second discharge pipe; 24-Second compressed air pipe; 25-Second main valve; 201-Second feed gate; 202-Second discharge gate; 203-Third conveying gate; 204-Fourth conveying gate; 205-Third material control gate; 206-Fourth material control gate;

[0029] 3-Air compressor; 4-Compressed air storage tank; 5-First conveying header; 6-Second conveying header. Detailed Implementation

[0030] To further disclose the invention's content, features, and effects, the following examples are provided and described in detail with reference to the accompanying drawings.

[0031] Embodiment: refer to the attached drawings Figure 1 A high-temperature circulating ash adjacent-furnace heating system for a circulating fluidized bed boiler storage bin, comprising a first circulating fluidized bed boiler 1 and a second circulating fluidized bed boiler 2; the first furnace 10 and the second furnace 20 of the two circulating fluidized bed boilers are connected through a first material conveying main pipe 5 and a second material conveying main pipe 6; the first circulating fluidized bed boiler 1 is provided with a first buffer bin 12, and the first discharge pipe 13 of the first buffer bin 12 is divided into two branches at the end, which are respectively connected to the first material conveying main pipe 5 and the second material conveying main pipe 6; the second circulating fluidized bed boiler 2 is provided with a second buffer bin 22, and the second discharge pipe 23 of the second buffer bin 22 is divided into two branches at the end, which are respectively connected to the first material conveying main pipe 5 and the second material conveying main pipe 6.

[0032] The first material conveying main pipe 5 and the second material conveying main pipe 6 are arranged at the bottom of the first furnace 10 and the second furnace 20, and the connection points of the first material conveying main pipe 5 and the second material conveying main pipe 6 with the first furnace 10 and the second furnace 20 are lower than the bottom end of the first buffer bin 12 and the second buffer bin 22. Near the connection points of the first material conveying main pipe 5 and the second material conveying main pipe 6 with the first furnace 10, first material conveying plug doors 103 and second material conveying plug doors 104 are respectively arranged; near the connection points of the first material conveying main pipe 5 and the second material conveying main pipe 6 with the second furnace 20, third material conveying plug doors 203 and fourth material conveying plug doors 204 are respectively arranged.

[0033] The first buffer bin 12 is connected with the first furnace 10 of the first circulating fluidized bed boiler 1 through a first feeding pipe 11, and the interface position of the first feeding pipe 11 with the first furnace 10 is higher than the lower contraction section of the first furnace 10; a first feeding plug door 101 is arranged on the first feeding pipe 11. The interface position of the first feeding pipe 11 with the first buffer bin 12 is slightly lower than the interface position of the first feeding pipe 11 with the first furnace 10, so as to ensure that the material flows smoothly; the first feeding pipe 11 is inclined from the side of the first furnace 10 to the side of the first buffer bin 12. The bottom of the first buffer bin 12 is connected with the first discharge pipe 13; a first discharge plug door 102 is arranged on the first discharge pipe 13 near the outlet of the first buffer bin 12. The two branches of the first discharge pipe 13 are provided with a first material control plug door 105 near the first material conveying main pipe 5 and a second material control plug door 106 near the second material conveying main pipe 6.

[0034] The second buffer bin 22 is connected with the second furnace 20 of the second circulating fluidized bed boiler 2 through a second feeding pipe 21, the interface position of the second feeding pipe 21 with the second furnace 20 is higher than the lower contraction section of the second furnace 20; a second feeding plug door 201 is arranged on the second feeding pipe 21. The interface position of the second feeding pipe 21 with the second buffer bin 22 is slightly lower than the interface position of the second feeding pipe 21 with the second furnace 20, so as to ensure that the material flows smoothly; the second feeding pipe 21 is inclined from the side of the second furnace 20 to the side of the second buffer bin 22. The bottom of the second buffer bin 22 is connected with a second discharging pipe 23; a second discharging plug door 202 is arranged on the second discharging pipe 23 close to the outlet of the second buffer bin 22. Two branches of the second discharging pipe 23 are provided with a third control plug door 205 close to the first material conveying main pipe 5 and a fourth control plug door 206 close to the second material conveying main pipe 6.

[0035] The lower part of the first buffer bin 12 and the second buffer bin 22 is in a contraction shape, facilitating the flow of the bed material. The first buffer bin 12, the second buffer bin 22, the first material conveying main pipe 5 and the second material conveying main pipe 6 are connected with a compressed air storage tank 4, and the compressed air storage tank 4 is connected with an air compressor 3. The compressed air storage tank 4 is connected with a first compressed air pipe 14 and a second compressed air pipe 24, and a first total valve 15 is arranged on the first compressed air pipe 14 and a second total valve 25 is arranged on the second compressed air pipe 24.

[0036] The first compressed air pipe 14 has three branches connected to the first buffer bin 12, the first material conveying main pipe 5 and the second material conveying main pipe 6 respectively, and a vent valve is arranged on each branch. The second compressed air pipe 24 has three branches connected to the second buffer bin 22, the first material conveying main pipe 5 and the second material conveying main pipe 6 respectively, and a vent valve is arranged on each branch.

[0037] The compressed air first enters the compressed air storage tank 4, and then is connected to the first buffer bin 12, the first material conveying main pipe 5 and the second material conveying main pipe 6 through the first compressed air pipe 14, and is connected to the second buffer bin 22, the first material conveying main pipe 5 and the second material conveying main pipe 6 through the second compressed air pipe 24, so as to loosen and convey the solid material particles, and make the conveying of the material more smooth. The public compressed air in the factory can also be directly connected to the compressed air storage tank 4. The first buffer bin 12, the second buffer bin 22, the first feeding pipe 11, the second feeding pipe 21, the first discharging pipe 13, the second discharging pipe 23, the first material conveying main pipe 5 and the second material conveying main pipe 6 need to be wrapped with heat preservation materials.

[0038] By setting the ash conveying pipeline and compressed air system, the bed material particles inside the first furnace 10 of the first circulating fluidized bed boiler 1 and the second furnace 20 of the second circulating fluidized bed boiler 2 can be exchanged with each other; the system can rapidly heat the solid particles in the other circulating fluidized bed boiler under the premise that one circulating fluidized bed boiler is in normal operation, so as to realize the functions of rapid start and rapid load adjustment.

[0039] Working principle:

[0040] When the system is not working, it is assumed that the first circulating fluidized bed boiler 1 is in normal operation and the second circulating fluidized bed boiler 2 is to be started, at this time, all the plug-in doors and valves are in the closed state, so as to ensure that the air pressure in the compressed air storage tank 4 is greater than 0.6Mpa.

[0041] Firstly, the high-temperature material in the first furnace 10 of the first circulating fluidized bed boiler 1 enters the second furnace 20 of the second circulating fluidized bed boiler 2 in sequence through the first feeding pipeline 11, the first buffer bin 12, the first discharging pipeline 13 and the first feeding main pipe 5. The first feeding plug-in door 101 on the first feeding pipeline 11, the first control plug-in door 105 on the branch connecting the first discharging pipeline 13 and the first feeding main pipe 5, and the third feeding plug-in door 203 on the first feeding main pipe 5 close to the second circulating fluidized bed boiler 2 are opened. The valves on the first compressed air pipeline 14 are opened. At this time, the high-temperature circulating material in the first circulating fluidized bed boiler 1 continuously enters the first buffer bin 12, and then enters the first discharging pipeline 13 and the first feeding main pipe 5 in sequence through the first buffer bin 12, and finally enters the second circulating fluidized bed boiler 2, so that the solid particle bed material in the second furnace 20 of the second circulating fluidized bed boiler 2 is rapidly heated.

[0042] At the same time, the second feeding plug-in door 201, the second discharging plug-in door 202, the fourth control plug-in door 206 and the second feeding plug-in door 104 are opened, and the valves on the second compressed air pipeline 25 are opened. The low-temperature material in the second furnace 20 of the second circulating fluidized bed boiler 2 enters the first furnace 10 of the first circulating fluidized bed boiler 1 in sequence through the second feeding pipeline 21, the second buffer bin 22, the second discharging pipeline 23 and the second feeding main pipe 6. At this time, the coal supply of the first circulating fluidized bed boiler 1 is appropriately increased, and the temperature in the first furnace 10 is kept unchanged.

[0043] When the first circulating fluidized bed boiler 1 is in normal operation and the second circulating fluidized bed boiler 2 needs to rapidly increase the load, the working principle is the same as that of the auxiliary boiler rapid start.

[0044] When any one of the boilers needs to reduce load rapidly, all the plug doors and valves are in the closed state, the first feeding plug door 101 on the first feeding pipeline 11 or the second feeding plug door 201 on the second feeding pipeline 21 is opened, and the circulating ash is allowed to enter the first buffer bin 12 or the second buffer bin 22, so that the speed of reducing the load of the boiler can be improved.

[0045] Although the preferred embodiments of the present application are described above, the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative and are not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims. These all belong to the protection scope of the present application.

Claims

1. A circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system, comprising at least two circulating fluidized bed boilers, characterized in that: Each circulating fluidized bed boiler is equipped with a buffer silo. The furnaces of every two circulating fluidized bed boilers are connected via a first feed header and a second feed header. The discharge pipe of each buffer silo splits into two branches, one connected to the first feed header and the other to the second feed header. The buffer silo, the first feed header, and the second feed header are all connected to a compressed air storage tank via compressed air pipelines, and the compressed air storage tank is connected to an air compressor. The buffer silo is connected to the furnace of the corresponding circulating fluidized bed boiler via a feed pipe, and the interface between the feed pipe and the furnace is higher than the lower part of the furnace. The feed pipe is equipped with a feed gate; the high-temperature material in the furnace of the normally operating circulating fluidized bed boiler is transported by compressed air through the feed pipe, buffer silo, and discharge pipe of the boiler and enters the furnace of the circulating fluidized bed boiler to be started through the first feed header, so that the solid particle bed material in the furnace can be heated rapidly; then the low-temperature material in the furnace of the circulating fluidized bed boiler to be started enters the furnace of the normally operating circulating fluidized bed boiler through the feed pipe, buffer silo, and discharge pipe of the boiler and enters the furnace of the normally operating circulating fluidized bed boiler through the second feed header.

2. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 1, characterized in that: The interface between the feed pipe and the buffer silo is slightly lower than the interface between the feed pipe and the furnace; the feed pipe is inclined from the furnace side to the buffer silo side.

3. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 1, characterized in that: The bottom of the buffer hopper is connected to the discharge pipe; a discharge gate is provided on the discharge pipe near the outlet of the buffer hopper; the lower part of the buffer hopper is constricted.

4. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 3, characterized in that: Each of the two branches of the discharge pipe is equipped with a material control gate near the first or second main discharge pipe.

5. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 1, characterized in that: The first and second feed headers are located at the bottom of the furnace of the circulating fluidized bed boiler, and the connection points between the first and second feed headers and the furnace are lower than the bottom of the buffer silo.

6. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 5, characterized in that: Each of the first and second feed headers is equipped with a feed gate near the connection point with each furnace chamber.

7. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 1, characterized in that: The compressed air storage tank is connected to several compressed air pipelines, each of which is equipped with a main valve. Each compressed air pipeline has three branches, which are respectively connected to the buffer silo, the first conveying main pipe and the second conveying main pipe, and each branch is equipped with a vent valve.

8. The circulating fluidized bed boiler storage-type high-temperature circulating ash furnace heating system according to claim 1, characterized in that: When the number of circulating fluidized bed boilers n>2, the first and second feed headers each have n branches, and each branch is connected to the furnace of a circulating fluidized bed boiler.

9. A heating method for a high-temperature circulating ash furnace in a circulating fluidized bed boiler with a storage compartment, using the heating system as described in any one of claims 1-8, characterized in that... The process includes the following steps: First, the high-temperature material in the furnace of the normally operating circulating fluidized bed boiler is transported by compressed air through the feed pipe, buffer silo, and discharge pipe of the boiler and then through the first feed header into the furnace of the circulating fluidized bed boiler to be started, so that the solid particle bed material in the furnace can be heated rapidly. Then, the low-temperature material in the furnace of the circulating fluidized bed boiler to be started is transported through the feed pipe, buffer silo, and discharge pipe of the boiler and then through the second feed header into the furnace of the normally operating circulating fluidized bed boiler. At this time, the coal feed rate of the normally operating circulating fluidized bed boiler is increased to keep the temperature in its furnace constant.

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