CN203478218U - Compact type circulating fluidized bed boiler capable of cleanly combusting high-sodium coal - Google Patents

Abstract

A compact circulating fluidized bed boiler capable of cleanly burning high-sodium coal, comprising a furnace, the furnace is divided into a lower furnace dense-phase zone and an upper furnace dilute-phase zone, the furnace dilute-phase zone is connected through a separator inlet flue The flue gas outlet of the cyclone separator arranged in front of the boiler furnace, the dust outlet of the cyclone separator is connected to the feeder through the standpipe, and the feeder is connected to the dense-phase area of the furnace through the feeder pipe, and the high-temperature flue gas generated by the combustion of the furnace passes through the The furnace panel heating surface in the dilute phase zone of the furnace cools rapidly, and the molten fly ash is effectively condensed, thereby effectively reducing the ash deposition on the tail convection heating surface; at the same time, the layout of the furnace panel heating surface The ash device can effectively clean up the accumulated ash and greatly improve the boiler operation cycle. The utility model has the characteristics of compact structure, convenient modular design and enlargement, and rationally utilizes the steel frame structure of the boiler. It is suitable for large-scale Take advantage of technology.

Description

A compact circulating fluidized bed boiler that burns high-sodium coal cleanly

technical field

The utility model belongs to the technical field of clean coal combustion utilization, in particular to a compact circulating fluidized bed boiler which can cleanly burn high-sodium coal. the

Background technique

my country is a country rich in coal resources, with a proven reserve of 1,099.7 billion tons and a predicted total coal resource of more than 5 trillion tons. However, most of my country's coal resources are located in the western regions, where precipitation is low, and they belong to arid, semi-arid and desertified regions , the ecological environment is fragile, and the economy is underdeveloped. If coal resources are simply transported abroad, the transportation volume is large and the distance is long, which is the main bottleneck for the large-scale utilization of coal resources in the west, and the use of coal resources in the west for power generation and delivery is the best way to solve the current utilization bottleneck problem . the

Xinjiang has the most abundant coal reserves in the western region. Xinjiang coal has high moisture and volatile content, low ash and calorific value, high sodium and potassium content in coal ash, and low ash melting point. During the combustion process, its coal The ash is highly contaminating and belongs to the strong ash-depositing and slagging type ash, which belongs to the category of high-sodium coal. In the process of burning high-sodium coal, it was found that a considerable number of boiler furnaces, superheaters and reheater areas would form a large area of highly cohesive ash in a short period of time, accompanied by severe high-temperature corrosion, and eventually This caused a large area of the boiler to explode, which directly affected the reliability, safety and economy of the boiler operation. the

In the existing technical means, it is generally delayed by increasing the cross-sectional area of the furnace, optimizing combustion and air distribution, increasing the frequency of soot blowing, using additives, blending coal and blending combustion, etc., but it is still difficult to cure it. The burning of high-sodium coal at home and abroad is a big problem, so high-sodium coal is only used in a few power plants in the United States, Australia and my country. During the process of co-firing, pulverized coal boilers are prone to slagging in the burner area of the furnace and contamination and clogging of high-temperature superheaters and high-temperature reheaters; circulating fluidized bed boilers are prone to coking on the bed surface and staining Dirt clogging problem. Although overall the operating cycle of circulating fluidized bed boilers burning high-sodium coal is longer than that of pulverized coal boilers, and the blending ratio of circulating fluidized bed boilers is higher than that of pulverized coal boilers (generally 40% to 50%), However, due to the high price of the blended coal, the economy of unit operation has been significantly affected. the

Therefore, in order to realize the large-scale utilization of coal resources in my country, it is urgent to find a method to directly burn high-sodium coal. the

Contents of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the purpose of this utility model is to provide a compact circulating fluidized bed boiler that can cleanly burn high-sodium coal, which can cleanly and efficiently burn high-sodium coal and avoid ash accumulation and slagging. the

In order to achieve the above object, the technical solution adopted by the utility model is:

A compact circulating fluidized bed boiler that can cleanly burn high-sodium coal, including a furnace, the furnace is divided into a lower furnace dense-phase zone 1 and an upper furnace dilute-phase zone 2, and the furnace dilute-phase zone 2 passes through the separator inlet The flue 3 is connected to the flue gas outlet of the cyclone separator 4 arranged in front of the boiler furnace, and the dust outlet of the cyclone separator 4 is connected to the feeder 6 through the standpipe 5, and the feeder 6 is connected to the dense phase of the furnace through the feeder pipe 7 District 1. the

In the dilute-phase zone 2 of the furnace, there are multiple screen-type heating surfaces A arranged in the furnace. the

The screen-type heating surface A in the furnace is arranged on the front and rear walls or the left and right side walls, and the distance between the screens is between 200 and 1000 mm. the

The clean flue gas after dust removal by the cyclone separator 4 enters the connecting cooling flue 9 from the central cylinder 8 of the separator, and the connecting cooling flue 9 is connected to the longitudinal tail flue 10, and the bottom of the tail flue 10 is provided with a tail flue outlet 13 And the ash hopper 11 of band ash hopper ash outlet 12. the

The connecting cooling flue 9 is provided with a multi-stage panel flue gas cooling and heating surface C, and the multi-stage panel flue gas cooling and heating surface C is a convection heating surface, and the stages are arranged in series. the

A rear flue heating surface B is arranged in the tail flue 10 . the

The inlet flue 3 of the separator, the connecting cooling flue 9 and the tail flue 10 are all provided with soot blowers 16, and the soot blowers 16 are arranged between different heating surfaces or in different areas of the same heating surface along the flue gas flow direction Between, the soot-blowing medium is steam, air, gas or water, and soot-cleaning holes are set around the sootblower 16 for supplementary soot-cleaning by manpower or machinery. the

The feeder 6 is provided with a circulating ash discharge port 15 for periodically or continuously discharging the recycled ash in the feeder 6 . the

The return pipe 7 is connected to the material addition pipe 14, and the coal, desulfurizer and supplementary bed material required for combustion can be mixed with the circulating ash in the return pipe 7 through the material addition pipe 14 and sent to the furnace dense phase zone 1 or separately It is sent to the dense-phase zone 1 of the furnace. Part of the ash is carried away by the flue gas, and part of it is regularly or continuously discharged from the slag outlet 17 provided in the furnace dense phase zone 1 and the circulating ash discharge system 15 provided in the feeder 6 . The condensed and solidified gaseous alkali metals and their compounds in the fly ash, bottom slag and bed material can also be replaced and enriched and discharged through the slag outlet 17 and the circulating ash discharge system 15 . the

The desulfurizing agent used in the utility model includes limestone, slaked lime, carbide slag or substances that can act as desulfurizing agents. The supplementary bed materials used include sand, slag, recycled ash and other inert supplementary substances that can be used as bed materials, and these substances can be supplemented periodically or continuously. the

A denitrification reducing agent injection port 18 for regular or continuous addition of denitrification agent is provided in the inlet flue 3 of the separator. In order to reduce the NOx emission concentration, the substance of the denitrification agent can be regularly or continuously injected through the denitrification reducing agent injection port. Denitration agents include urea aqueous solution, ammonia water, liquid ammonia or substances that can act as denitration agents. the

The gas flow velocity in the dense-phase zone 1 and the dilute-phase zone 2 of the furnace is 3-5m/s, and the temperature is controlled between 600-850°C. the

Compared with the prior art, the beneficial effects of the utility model are:

1. Because the cyclone separator is placed in front, the structure is compact, the steel frame structure is used efficiently, and the boiler occupies less space. Even if the furnace volume is increased, the overall volume of the boiler will not increase. the

2. The separator is placed in front, extending the length of the connecting cooling flue, which is convenient for arranging multi-stage screen flue gas cooling heating surfaces and fully cooling the flue gas. the

3. Taking advantage of the low combustion temperature of the circulating fluidized bed boiler, the release of alkali metals and their compounds is reduced. the

4. High-density soot blower makes dust accumulation easy to clean and avoids deposition. the

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the utility model. the

FIG. 2 is a top view of FIG. 1 . the

Fig. 3 is a structural schematic diagram of an application example of connecting the cooling flue arranged on the side of the furnace of the utility model. the

FIG. 4 is a top view of FIG. 3 . the

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described. However, those skilled in the art understand that the protection scope of the present invention is not limited to the content of the following embodiments, and any improvements and changes made on the basis of the present invention are within the protection scope of the present invention. the

Example 1:

Referring to Fig. 1 and Fig. 2, the boiler includes a furnace dense-phase zone 1 and a furnace dilute-phase zone 2. In the furnace dilute-phase zone 2, there are 8 screen-type heating surfaces A in the furnace (4 panels on the left and right side walls). The furnace dilute phase zone 2 is connected with the cyclone separator 4 through the separator inlet flue 3, and there are 2 cyclone separators 4, which are compactly arranged on the front side of the boiler. The flue gas after dedusting by the cyclone separator 4 enters the connecting cooling flue 9 from the separator central cylinder 8. The connecting cooling flue 9 is equipped with a two-stage flue gas cooling heating surface C is a convective heating surface, through which the heating surface can be reduced The flue gas temperature is connected to the cooling flue 9 which is arranged on the upper part of the boiler furnace. A tail flue heating surface B is arranged in the tail flue 10 , and the cooled flue gas is finally discharged from the tail flue outlet 13 . the

The temperature of the dense-phase zone 1 and the dilute-phase zone 2 of the furnace is controlled between 600 and 850°C, and the airflow velocity is 4.2m/s. The fine particles of ash and slag are carried away by the flue gas, and some of them are regularly discharged from the slag discharge port 17 provided in the furnace dense phase zone 1 and the circulating ash discharge port 15 provided in the feeder 6 . Due to the low combustion temperature, gaseous alkali metals and their compounds condensed and solidified in the fly ash, bottom slag and bed material can also be replaced and enriched and discharged through the slag discharge port 17 and the circulating ash discharge port 15 . the

Because the alkali metal and its oxide will form a layer of attachment on the heating surface, and then bonded to the heating surface, as the running time prolongs, it will gradually thicken until it is blocked. For this reason, a high-density soot blower 16 is installed in the inlet flue 3 of the separator, the connecting cooling flue 9, and the tail flue 10 to carry out enhanced soot blowing along the flow direction of the flue gas. The soot blowing medium is selected from steam and gas. The arrangement density of soot blowers is 1 set per meter. In addition, there are soot cleaning holes around the high-density sootblower 16, and in special cases, supplementary soot cleaning can be performed by manpower. The ash hopper 11 and the ash hopper ash outlet 12 provided at the bottom of the tail flue 10 can regularly discharge the accumulated ash in the tail flue. the

In order to reduce the concentration of NOX emissions, the boiler is also equipped with a denitrification reducing agent injection port 18, and continuously sprays urea aqueous solution as a denitrification agent during operation to perform flue gas denitrification. the

Example 2:

See Figure 3 and Figure 4, a small boiler for steam supply, mainly burning high-sodium coal. In the dilute-phase zone 2 of the furnace, there are 4 screen-type heating surfaces A (2 panels on the front and rear side walls), and 2 cyclone separators 4 are arranged in front of the furnace. The two connecting cooling flues 9 are arranged on the left and right sides of the furnace, the overall height of the boiler is relatively low, and each inner connecting cooling flue 9 is provided with a three-stage flue gas cooling heating surface C. the

Claims (9)

1. One kind can the high sodium coal of clean burning compact circulating fluidized bed boiler, comprise burner hearth, it is characterized in that, described burner hearth is divided into the burner hearth emulsion zone (1) of bottom and the burner hearth dilute-phase zone (2) on top, burner hearth dilute-phase zone (2) connects the exhanst gas outlet of the cyclone separator (4) being arranged in before Boiler Furnace by separator inlet flue (3), the dust-exhausting port of cyclone separator (4) connects material returning device (6) by standpipe (5), and material returning device (6) connects burner hearth emulsion zone (1) by feed back pipe (7).
2. 2. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 1, is characterized in that, is provided with the stove inner screen type heating surface (A) that multi-disc is arranged in described burner hearth dilute-phase zone (2).
3. 3. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 2, is characterized in that, described stove inner screen type heating surface (A) is arranged in front-back wall or left and right side wall, and the spacing between screen is between 200～1000mm.
4. 4. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 1, it is characterized in that, clean flue gas after described cyclone separator (4) dedusting is entered and is connected cooling stack (9) by central cylinder of separator (8), connect cooling stack (9) and connect back-end ductwork (10) longitudinally, back-end ductwork (10) bottom is provided with the ash bucket (11) of back-end ductwork outlet (13) and band ash bucket ash discharging hole (12).
5. 5. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 4, it is characterized in that, in described connection cooling stack (9), be provided with the cooling heating surface of multistage screen formula flue gas (C), the cooling heating surface of described multistage screen formula flue gas (C) is convection type heating surface, at different levels between series winding arrange.
6. 6. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 4, is characterized in that, is furnished with back-end ductwork heating surface (B) in described back-end ductwork (10).
7. 7. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 4, it is characterized in that, in described separator inlet flue (3), connection cooling stack (9) and back-end ductwork (10), be provided with soot blower (16), soot blower (16) is arranged between different heating surfaces or between the zones of different of identical heating surface along flow of flue gas direction, sootblowing dielectric is steam, air, combustion gas or water, soot blower (16) periphery arranges ash removing opening simultaneously, for manpower or machinery, supplements deashing.
8. 8. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 1, is characterized in that, described material returning device (6) is provided with circulating ash floss hole (15), for the circulating ash in regular or continuous blow-down material returning device (6).
9. 9. compact circulating fluidized bed boiler that can the high sodium coal of clean burning according to claim 1, is characterized in that, described feed back pipe (7) connects material adding tube (14).

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