CN102901093A - Double-way controllable material returning valve for circulating fluidized bed boiler - Google Patents

Abstract

The utility model relates to a dual-way controllable feed return valve for a circulating fluidized bed boiler, which belongs to a feed return device of a circulating fluidized bed boiler, and particularly relates to the design of a flow rate regulating device. The feeding pipe of the return valve is provided with a partition plate, which divides the lower part of the feeding pipe into two parts, each of which is connected with a moving packed bed, and after the moving packed bed is connected with the returning material bed respectively, the returning material bed Then there is a return pipe. An air distribution system is arranged under the moving packed bed and the return material bed. The return valve adopts a double-circuit design to realize single-point feeding and multi-point returning; The pressure of the feed pipe can be adjusted to adjust the proportion of the material in the upper part of the feed pipe when it enters the two sides of the lower partition, so as to realize the adjustment of the material flow rate of the two return points. The return valve allows materials to enter the furnace more evenly, greatly improving the return uniformity of hot materials in the bed section of the large-scale circulating fluidized bed boiler.

Description

A Two-way Controllable Return Valve for Circulating Fluidized Bed Boiler

technical field

The invention relates to a controllable device for a return valve of a circulating fluidized bed boiler, which belongs to the return device of a circulating fluidized bed boiler.

Background technique

Circulating fluidized bed boiler technology is a high-efficiency, low-pollution and clean combustion technology that has developed rapidly in the past ten years. Internationally, this technology has been widely used commercially in the fields of power station boilers, industrial boilers and waste treatment and utilization, and is developing towards large-scale circulating fluidized bed boilers with a scale of hundreds of thousands of kilowatts; domestic research and development in this area And applications are also gradually emerging, and hundreds of circulating fluidized bed boilers have been put into operation or are being manufactured. Therefore, it is of great significance to improve the efficiency of circulating fluidized bed boilers.

As a device for material return, the return valve is a very important part in the circulating fluidized bed boiler. The performance of the return valve directly affects the stability of the external circulation of the fluidized bed and the uniformity of material distribution in the furnace, thereby affecting the efficiency of the fluidized bed. The function of the return valve is mainly the return and sealing function, that is, the material returns to the furnace through the return valve, and at the same time, it is necessary to prevent the flue gas from the furnace from flowing back from the return valve to the cyclone separator and affect the efficiency of the separator.

At present, the main problem faced by my country's circulating fluidized bed technology is that with the enlargement of circulating fluidized bed boilers, the area of the furnace bed also increases accordingly. The deviation of the distribution. The inhomogeneity of temperature can be solved by adjusting the deviation of coal feeding, but the unevenness of material concentration diffusion caused by the deviation of circulation flow rate between various separators still lacks sufficient operation methods to adjust it.

At home and abroad, the single-way feeding valve device is mainly used, that is, each feeding valve has only one inlet and one outlet. This kind of single-way feeding device has fewer returning points, which is likely to cause uneven distribution of materials in the furnace, and is not suitable for use in a large boiler. Harbin Boiler Factory invented a pneumatic self-balancing dual-channel return device (patent number ZL 200620020679.1), which realizes the function of single-point feed and two-point return, and can distribute the external circulation material more evenly to a larger bed area. However, in actual operation, the pneumatic self-balancing return valve cannot realize the artificial control of the circulating material flow rate between the two return points, that is, it is impossible to artificially adjust the return amount of the two material points according to the actual working conditions, so it cannot Better solve the problem of uneven material distribution in the furnace.

Contents of the invention

In view of the above situation, the present invention provides a dual-channel controllable return valve device for circulating fluidized bed boilers, which can control the flow rate of materials between each return point while realizing single-point feeding and multi-point return. distribution, so as to optimize the material distribution performance and better solve the problem of uneven material distribution in the furnace.

Purpose and task of the present invention are achieved through the following technical solutions:

A two-way controllable return valve for a circulating fluidized bed boiler, the return valve includes a feed pipe, an air distribution device, and a moving packed bed symmetrically arranged on both sides of the lower part of the feed pipe, a baffle section, and a feed return valve. bed and return pipe; the moving packed bed and the return bed are connected through a baffle section, and are respectively connected with the air chamber of the air distribution device. The material pipe is divided into two parts, the lower part of the partition plate is connected with the air distribution plate, and the top of the partition plate is at least 0.2 meters higher than the upper edge of the air outlet of the return pipe.

In the above technical solution, the outer surface of the partition plate is provided with a refractory and wear-resistant material layer. The deflection section adopts a section of horizontal pipe or a heat-resistant partition.

Another technical feature of the present invention is that: each of the two moving packed beds is connected to a loose air chamber, and each of the two return beds is connected to a return air chamber.

The present invention has the following advantages and outstanding effects: the lower section of the feed pipe is divided into two parts by a partition plate, which are respectively connected to the moving packed bed, and the loose air volume under the two moving packed beds can be adjusted , can change the pressure of the feed pipes on both sides of the partition plate, so as to adjust the ratio of the material in the upper section of the feed pipe entering the two sides of the partition plate in the lower section, and realize the adjustment of the material flow rate of the two return points.

Description of drawings

Fig. 1 is a structural schematic diagram of a dual-way controllable return valve for a circulating fluidized bed boiler provided by the present invention. (i.e. top view).

Fig. 2 is a sectional view along line A-A of Fig. 1 .

In the figure: 1-feeding pipe; 2-partition plate; 3-returning pipe; 4-deflection section; 5-air distribution plate; 6-returning bed; 7-moving packed bed;

8-loose air chamber; 9-return material air chamber; 10-refractory and wear-resistant material layer; 11-loose air chamber pressure measurement point

12—low pressure measuring point; 13—high pressure measuring point; 14—upper edge of air outlet of return pipe.

Detailed ways

The structure, principle and specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

The two-way controllable return valve includes a feed pipe, an air distribution device, and a moving packed bed 7 symmetrically arranged on both sides of the lower part of the feed pipe, a baffle section 4, a return bed 6 and a return pipe 3; The moving packed bed 7 and the return material bed 6 are connected through the baffle section 4, and the moving packed bed and the return material bed are respectively connected with the air chamber of the air distribution device; The pipe is divided into two parts, and the lower part of the dividing plate is connected with the air distribution plate 5 . The top of the dividing plate will be higher than the upper edge 14 of the air outlet of the return pipe, generally at least 0.2 meters higher.

The diameter of the feed pipe in this embodiment is 1300 mm. The outer surface of the partition is lined with refractory and wear-resistant materials (such as phosphate bricks, silicon carbide materials, etc.), and the height of the partition is 1.5m higher than the upper edge of the air outlet of the return pipe.

The moving packed bed 7 and the return material bed 6 are connected by a baffle section 4 to increase the fluidity of the return material. The baffle section 4 can be a section of horizontal pipe, or a heat-resistant partition can be used to realize the baffle function. The upper edge of the baffle section is at least 300mm lower than the lower edge of the air outlet of the return pipe. When using horizontal pipes, it is recommended that the length of the horizontal pipes be less than 250mm, and when using heat-resistant partitions, it is recommended that the thickness of the partitions be 100mm. In this embodiment, the baffle section is a section of horizontal pipe, and the width of the baffle section is 200mm. The lower edge of the air outlet of the return valve return pipe is 350mm higher than the upper edge of the baffle section.

The air chamber of the air distribution device can be a square air chamber or a conical air chamber. The loose air chamber 8 and the return air chamber 9 used in this embodiment are all square air chambers with an area of 750*750mm.

In this example, the specific method for realizing the controllable material flow rate of the circulating fluidized bed is as follows: each of the two moving packed beds is connected to a loose air chamber 8 , and each of the two return beds is connected to a return air chamber 9 . The advantage of using a separate air chamber is that by adjusting the return air at the return point and loosening the air volume, the material flow at the return point can be controlled.

Two pressure measuring points 11 are set in the two loose air chambers. Since the resistance of the air distribution plate in the device is constant, the pressure of the pressure measuring points 11 in the air chamber actually reflects the material level height of the external circulation material in the moving packed bed. , arrange the pressure gradient low-level measurement point 12 and high-level pressure measurement point 13 in the moving packed bed, wherein the high-level pressure measurement point 13 is on the same horizontal line as the upper edge of the air outlet of the return pipe. The measurement of high and low pressure can be converted to obtain the material pressure gradient in the moving packed bed. According to the theory of viscous slip flow, the material pressure gradient directly reflects the material flow rate. By changing the loose air volume of the moving packed bed on one side, the height and pressure gradient of the material level of the sealing leg in the corresponding feed pipe will be changed, and then the ratio of the material in the upper section of the feed pipe entering the two sides of the lower partition plate will be adjusted. Realize the adjustment of the material flow rate of the two return points.

Claims (4)

1. A two-way controllable return valve for a circulating fluidized bed boiler, the return valve includes a feed pipe (1), an air distribution device, and a moving packed bed symmetrically arranged on both sides of the lower part of the feed pipe (7), baffle section (4), return material bed (6) and return material pipe (3); said moving packed bed (7) and return material bed (6) are connected through baffle section (4) , and are respectively connected with the air chamber of the air distribution device, which is characterized in that: a partition plate (2) is provided in the feed pipe to divide the feed pipe into two parts; the lower part of the partition plate is connected with the air distribution plate (5) , the top of the dividing plate is at least 0.2 meters higher than the upper edge (14) of the air outlet of the return pipe. 2. A dual-way controllable return valve for a circulating fluidized bed boiler as claimed in claim 1, characterized in that: the outer surface of the partition plate is provided with a refractory and wear-resistant material layer (10) . 3. A two-way controllable return valve for a circulating fluidized bed boiler according to claim 1, characterized in that: the baffle section adopts a section of horizontal pipe or a heat-resistant partition. 4. A two-way controllable return valve for circulating fluidized bed boilers according to claim 1, characterized in that: two moving packed beds are connected to a loose air chamber (8) respectively, and two The return material beds are respectively connected with a return material air chamber (9).

Images