CN209782607U - Slag discharge and air distribution system of circulating fluidized bed boiler - Google Patents

Abstract

The utility model discloses a slag discharge and air distribution system of a circulating fluidized bed boiler, which comprises an air chamber arranged at the bottom of a hearth, wherein the air chamber is at least divided into two air chambers, the upper part of the air chamber is provided with an air distribution plate, the air distribution plate is provided with holes, and each hole is provided with an air pipe and an air cap; the side wall of the hearth corresponding to one of the air chambers is provided with a slag discharge pipe, the upper opening of the slag discharge pipe is flush with the top surface of the air distribution pipe, and the lower opening is led out of the hearth through the air chamber and is provided with a valve. The selective air distribution system in the circulating fluidized bed furnace can achieve the purpose that the boiler discharges more coarse particles and retains fine particles in the furnace during slag discharge.

Description

Slag discharge and air distribution system of circulating fluidized bed boiler

Technical Field

The utility model relates to a circulating fluidized bed boiler technique, concretely relates to air distribution design of selective row's sediment in the circulating fluidized bed stove.

background

Circulating Fluidized Bed (CFB) boilers have been developed in China for 20 years, and the CFB boilers have a wide application range to fuel and can burn low-volatile and high-ash-content low-quality coal. The low-temperature combustion technology has the advantages of low combustion temperature, large load regulation range and low operation and manufacturing cost, can meet the environmental protection requirements of nitrogen oxides and sulfur oxides, is widely accepted in the world at present, and is recognized as one of the most feasible coal clean combustion technologies all over the world.

Coal gangue, stone coal and the like are main inferior fuels for CFB boiler combustion and utilization. The CFB boiler has strict requirements on the grain diameter of the coal to be fed, the average grain diameter of the coal to be fed is usually 0.8-1 mm, but the hardness of the coal gangue is high, the Mohs hardness of the coal gangue is 3-7, and the coal gangue is 2-3 times that of high-quality coal which is usually used for burning. Therefore, the secondary wear and the crushing of the boiler after combustion are not easy, the formed fine particles are few, the proportion of the fine particles in the bed is reduced, the concentration of a dilute phase region is reduced, in order to maintain the normal load of the boiler, the power plant generally needs to increase the fluidization air quantity to enable more particles to enter the dilute phase region, the ideal particle size distribution and the particle concentration distribution in the boiler do not exist, a reasonable temperature field in the bed is damaged, and the safety of a unit is seriously influenced. Meanwhile, the increase of the fluidization air volume can make coarser particles enter the upper part of the hearth and then aggravate the abrasion of the heating surface, and the increase of the proportion of the coarse particles can make the bed temperature rise and be not beneficial to the emission of nitrogen oxides. Therefore, the reasonable method for recovering the fine particles in the ash residues to return to the hearth or reducing the discharge of the fine particles in the furnace is a main idea for solving the contradiction between the abrasion of the heating surface of the hearth and the load of the boiler.

the currently used slag discharging devices, such as a conical valve and an L-shaped valve, are drainage devices of slag in a bed and have no slag discharging and sorting capability, and fine ash in bottom slag is collected and sorted by a slag cooler, so that a large amount of physical heat loss of the ash is caused. If the primary screening of the particles can be realized in the discharging process of the bed materials, the output of the slag cooler can be effectively reduced, the heat loss of slag discharge is reduced, and the boiler efficiency is improved. The particles in the fluidized bed have wide particle size distribution, different particles in the bed have different fluidization states under the same apparent velocity, fine particles are in a fluidization state and coarse particles are in a fixed bed state under the lower apparent velocity, the coarse particles are gradually precipitated at the bottom of the bed layer, and the fine particles gradually float on the upper surface of the bed layer, so that segregation and stratification phenomena occur. At high wind speeds, fine particles with terminal velocity less than the superficial velocity will be entrained out of the bed and coarse particles with terminal velocity greater than the superficial velocity will remain in the bed.

Present CFB boiler is moving towards high-efficient, supercritical, energy-conserving direction development trend, has proposed higher requirement to the stable operation of the cold sediment ware of CFB boiler and the fluidization in the bed, and the CFB boiler based on flow state reconstruction especially needs higher circulation volume and more excellent bed material particle size distribution, to the defect of current CFB boiler slagging system, the utility model provides an adopt interior row's of stove sediment to select separately the system.

disclosure of Invention

The utility model provides a wind system is arranged to stove of selective sediment of circulating fluidized bed boiler, it can't effectual realization selective sediment problem at the sediment in-process to be dedicated to solving current circulating fluidized bed boiler sediment system.

In order to achieve the above purpose, the utility model discloses will adopt following technical scheme to realize:

An air distribution system for deslagging of a circulating fluidized bed boiler comprises an air chamber arranged at the bottom of a hearth, wherein the air chamber is at least divided into two air chambers, an air distribution plate is arranged at the upper part of the air chamber, holes are formed in the air distribution plate, and an air pipe and an air cap are arranged at each hole; the side wall of the hearth corresponding to one of the air chambers is provided with a slag discharge pipe, the upper opening of the slag discharge pipe is flush with the top surface of the air distribution pipe, and the lower opening is led out of the hearth through the air chamber and is provided with a valve.

Preferably, the air distribution plate adopts a horizontal mode or an inclined mode; when the slag discharging port is in an inclined mode, the air distribution plate is inclined towards the air chamber on one side of the slag discharging port.

Preferably, the angle of inclination is 10-20 degrees.

Preferably, the partial opening rate of the wind chamber near the slag discharge pipe on the wind distribution plate is larger than that of other areas. The average opening ratio of the air distribution plate was 1.5%, but the opening ratio near the slag discharge pipe opening was 2%.

Preferably, the plenum is divided into two, three, four or five plenums.

Preferably, the blast cap comprises a conventional blast cap and a directional blast cap, the directional blast cap is mainly arranged near the pipe orifice of the slag discharging pipe, and the conventional blast cap is adopted in other air distribution plate areas.

Preferably, the valve of the slag discharge pipe adopts a gate valve mode, and the slag discharge flow rate is controlled through an electric valve.

Preferably, the slag discharge pipe is provided with an expansion joint.

Compared with the prior art, the utility model, have following advantage and outstanding technical advantage:

1. The device has simple structure, and can be realized by only increasing the division of the air chamber when the boiler is designed.

2. the investment cost of the equipment is low and the performance is reliable. The method makes full use of the principle of fluidized bed fluidization theory without adding additional auxiliary machines.

Drawings

the accompanying drawings are included to provide a further understanding of embodiments of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention, but do not constitute a limitation of the invention.

FIG. 1 is a schematic view of a circulating fluidized bed boiler according to an embodiment (also referred to as abstract drawing);

FIG. 2 is a multi-plenum structure of a horizontal air distribution plate according to an embodiment;

FIG. 3 is a multi-chamber structure of an inclined wind distribution plate according to an embodiment;

FIG. 4 is a schematic view of a sorting grid;

FIG. 5 is a schematic view of a conventional hood;

FIG. 6 is a schematic view of a directional hood;

In the figure: 1-a left side air chamber; 2-air distribution plate; 3-blast cap; 4-hearth (4 in fig. 3 is coal feeding hole); 5-a cyclone separator; 6-right side wind chamber; 7-a slag discharge pipe; 8-a valve; 9-hood mouth; 10-a slag discharge port; 11-conventional hood; 12-directional hood.

Detailed Description

the following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings. It is to be understood that the description of the embodiments herein is for purposes of illustration and explanation only and is not intended to limit the invention.

In the description of the present invention, unless indicated to the contrary, the use of directional terms such as "upper" and "lower" is generally intended in the orientation shown in the drawings or in the orientation of the components relative to one another in the vertical, perpendicular, or gravitational direction.

The first embodiment is as follows:

Referring to fig. 1, fig. 1 is a schematic structural view of a circulating fluidized bed boiler according to a preferred embodiment of the present invention.

The circulating fluidized bed boiler furnace (equipped with cyclone separator 5), the bottom of furnace 4 has wind chambers, the wind chamber is located under the wind distribution plate, the wind chamber is divided into two parts from left to right, which are left wind chamber 1 and right wind chamber 6, the left and right division refers to from the front wall to the back wall of the boiler. The air chamber provides fluidized air for the bed and distributes air quantity through the openings of the upper air distribution plate; the upper edge of the air distribution plate 2 is provided with air holes, and the air distribution plate covers the upper part of the air chamber; the air distribution plate 2 of the present example is arranged in a horizontal manner. The arrangement of the two air chambers ensures that particles on the upper parts of the two air chambers in the bed can form circular flow in the deslagging process.

the air pipe and the air cap 3 are positioned at the upper part of the air distribution plate and are connected with the air chamber through the opening on the air distribution plate, and the air cap uniformly distributes the air in the air chamber, so that the particles in the bed are uniformly fluidized, and the coking in the bed is prevented in the combustion process; the slag discharging pipe 7 is connected with slag discharging holes on the air distribution plate and penetrates through the air chamber, and can discharge burned particles in the bed in time when slag discharging is needed; the valve 8 is arranged at the slag discharge port 10, and is opened to discharge slag when the slag needs to be discharged. The slag discharge pipe is provided with an expansion joint, so that the welding damage caused by the stress action during high-temperature slag discharge is prevented.

When the boiler is in operation, the air volume of the two air chambers is the same, the slag discharge pipe is closed, and the fluidization in the bed is uniform. When the bed pressure reaches a certain degree and slag needs to be discharged, firstly, the air volume distribution of the air chamber is controlled, the air volume of the air chamber is ensured to be larger than that of the left air chamber, when particles in the bed flow to a slag discharge pipe opening, the particles in the bed pass through the air chamber with large air volume, because very high fluidizing air can blow out fine particles with terminal speed smaller than fluidizing air speed of a large amount of particles from the lower part of the bed layer, large particles with terminal speed larger than fluidizing air speed can be gradually precipitated at the bottom of the bed layer, after the operation is stable for a period of time, a slag discharge valve on a slag discharge pipe is opened, large particles can be discharged with slag, and fine particles are left in the bed, so that the purpose of adjusting the particle size distribution in the bed by sorting.

example two:

In the embodiment, as shown in fig. 2, the air chamber is divided into four air chambers, the air volume of the divided air chamber can be controlled independently, and the division of the air chamber can adopt different forms, but the division principle is to ensure that the air distribution in the bed is uniform when the slag is not discharged, and the realization of non-uniform air distribution when the slag is discharged. The plenum may also be divided into a greater or different number of partitions.

Example three:

In this embodiment, as shown in fig. 3, the air distribution plate is arranged in an inclined manner, and the air distribution plate is inclined towards the air chamber on the side where the slag discharge port is arranged, and the inclination angle is designed to be different according to the difference of coal types, and is not greater than 15 degrees.

Example four:

In the embodiment, optionally, the conventional blast cap and the directional blast cap are arranged, the directional blast cap is mainly arranged near the pipe orifice of the slag discharge pipe, the conventional blast cap is adopted in other wind distribution plate areas, the blast cap outlet of the conventional blast cap 11 is provided with air holes, and the outlet of the directional blast cap 12 is intensively directed near the slag discharge port. The blast caps can be different in size, the main difference is as shown in fig. 5 and 6, the blast cap with a smaller aperture can be adopted at the slag discharge pipe opening so as to ensure higher wind speed, thus fine particles can be reduced to be carried and discharged by coarse particles, and the directional blast cap can be adopted to blow towards the slag discharge pipe opening in a directional mode to further screen the discharged particles.

the present invention has been described in detail with reference to fig. 1, but the present invention is not limited to the details of the above embodiments. Fig. 1 shows the embodiment of selective slag removal in the circulating fluidized bed boiler in the form of inclined air distribution plate, the design concept of high wind speed slag removal in the slag discharge pipe of other forms of circulating fluidized bed can be adopted equally, the technical scheme of the utility model is different in the size of the specific wind speed parameter, the type selection of the hood, the design parameter of the air chamber, but the core concept of the utility model is not violated. Technical idea in-range, can be according to actual design demand, it is right according to particular case the utility model discloses a technical implementation carries out multiple simple variant, these simple variants all belong to the utility model discloses a protection scope.

Claims (8)

1. The utility model provides a sediment air distribution system is arranged to circulating fluidized bed boiler, this system is including setting up the plenum in the furnace bottom, its characterized in that: the air chamber is at least divided into two air chambers, the upper part of the air chamber is provided with an air distribution plate, the air distribution plate is provided with openings, and each opening is provided with an air pipe and an air cap; the side wall of the hearth corresponding to one of the air chambers is provided with a slag discharge pipe, the upper opening of the slag discharge pipe is flush with the top surface of the air distribution pipe, and the lower opening is led out of the hearth through the air chamber and is provided with a valve.

2. the slagging and air distribution system of the circulating fluidized bed boiler according to claim 1, characterized in that: the air distribution plate adopts a horizontal mode or an inclined mode; when the slag discharging port is in an inclined mode, the air distribution plate is inclined towards the air chamber on one side of the slag discharging port.

3. The slagging and air distribution system of the circulating fluidized bed boiler according to claim 2, characterized in that: the inclination angle is 10-20 degrees.

4. the slagging and air distribution system of the circulating fluidized bed boiler according to claim 1, characterized in that: the average opening ratio of the air distribution plate was 1.5%, but the opening ratio near the slag discharge pipe opening was 2%.

5. The circulating fluidized bed boiler deslagging air distribution system according to any one of claims 1-4, characterized in that: the plenum is divided into two, three, four or five plenums.

6. The slagging and air distribution system of the circulating fluidized bed boiler according to claim 5, characterized in that: the blast cap comprises a conventional blast cap and a directional blast cap, the directional blast cap is mainly arranged near the pipe orifice of the slag discharge pipe, and the conventional blast cap is adopted in other blast plate areas.

7. The slagging and air distribution system of the circulating fluidized bed boiler according to claim 6, wherein: the valve of the slag discharge pipe adopts a gate valve mode, and the slag discharge flow rate is controlled by an electric valve.

8. The slagging and air distribution system of the circulating fluidized bed boiler according to claim 7, characterized in that: the slag discharge pipe is provided with an expansion joint.