JPH04110503A - Pressurized fluidized-bed boiler - Google Patents

Abstract

PURPOSE:To obviate the need of providing a large container to store fluidized medium and attain a high load-changing speed by a method wherein heat transfer tubes mounted in a fluidized bed are divided into two or more vertical stages, and two or more air blow nozzles are provided under each stage of the heat transfer tubes. CONSTITUTION:A pressurized fluidized bed boiler 1 consists of a free board 2 and a fluidized bed 3. Heat transfer tubes 4a and 4b are stacked in two stages and air supply pipes 6a and 6b with fluidizing nozzles 5 are laid under the heat transfer tubes 4a and 4b. When the load is lowered, an air flow control valve 7b at the lower stage is throttled and an air flow control valve 7a at the upper stage is opened by an instruction of a controller 9, so that the heat absorption quantity of the lower stage heat transfer tubes 4b decreases. Therefore, the overall load control is done by adjusting the air supply rate of the lower stage air flow control valve 7b to change time heat absorption quantity of the lower stage heat transfer tubes 4b. When the load is increased, the lower stage air flow control valve 7b is opened and the upper stage air flow control valve 7a is regulated to control the load.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the structure of a fluidized bed section of a pressurized fluidized bed boiler, particularly to the arrangement of heat transfer tubes and air blowing nozzles.

[Prior Art] Since a pressurized fluidized bed boiler uses an air compressor to supply air, a large fluidized bed pressure loss can be achieved. Therefore, compared to a normal pressure fluidized bed boiler, a pressurized fluidized bed boiler allows the height of the fluidized bed to be increased, and the entire heat transfer surface can be placed within the fluidized bed with good heat transfer performance. however,
Fluidized bed boilers have a disadvantage in that they have a poor ability to follow changes in load because they contain a large amount of fluidized material with a large heat capacity.

As a countermeasure against this problem, there has conventionally been a fluidized bed boiler as shown in Fig. 3-1. That is, a container 11 for storing a fluid material is placed outside the boiler main body 1, and the fluid material is taken in and out between the container 11 and the boiler main body 1, and the fluidized bed section 3
change the layer height. As a result, the ratio of the areas of the heat exchanger tubes 4 arranged inside the fluidized bed and outside the fluidized bed changes.
This changes the amount of smoke generated in the boiler to quickly respond to load changes.

[Problems to be Solved by the Invention] The fluidized bed boiler shown in Figure 3, which attempts to improve the ability to follow changes in load, requires a large-capacity container for storing fluidized material and accessory equipment, which makes the overall This was one of the factors that increased costs.

An object of the present invention is to provide a pressurized fluidized bed boiler that can ensure a high rate of load change without requiring a large container for storing fluidized material.

Means for solving the problem: According to the present invention, in order to achieve the above object, a heat transfer tube arranged in a fluidized bed is divided into upper and lower stages in multiple stages, and
The present invention proposes a pressurized fluidized bed boiler characterized in that a plurality of nozzles for blowing out air are provided below the heating tubes of each stage.

For use in this invention: i. By blowing air out of any nozzle among the multiple stages of nozzles, any position can be fluidized. In other words, effective heat transfer can be performed by fluidizing only the area around the heat transfer tube above the position of the nozzle that blows out air, making it easy to generate steam commensurate with the heat transfer area. I can do it.

1 Embodiment] The 10th is a longitudinal sectional view showing an embodiment of the present invention. This embodiment is an example of a case where multiple devices are used.

The pressurized fluidized bed boiler main body 1 is composed of a freeboard section 2 and a fluidized bed section 3. Inside the fluidized bed section 3: Heat exchanger tube 4
Seven nozzles 5 for fluidization and air supply pipes 6a, 6b are arranged below the heat transfer tubes 4a, 4b, which are arranged in two stages, upper and lower. At the inlets of the air supply pipes 6a and 6b, air amount adjustment valves τa and 7b are provided, respectively, and an air amount adjustment valve 8 is installed to switch between these air amount adjustment valves 7a and 7b.

When the load changes, these air amount adjustment valves 787b,
8 is controlled by the control device 9 as follows.

1) At the time of load reduction, according to the command from the control device 9, the lower air amount adjustment valve 7b is first
is throttled and the upper air amount adjustment valve 7a is opened. This reduces the amount of heat absorbed by the lower heat exchanger tubes 4b. Therefore, the overall load adjustment is performed by changing the amount of heat absorption of the lower heat exchanger tubes 4b depending on the amount of air supplied by the lower air amount adjustment valve 7b.

2) When the load increases At this time, contrary to 1) above, the load is adjusted by opening the lower air regulating valve 7b and adjusting the upper air regulating valve 7a.

If further fine adjustment is required, the air supply pipes 6a, 6b can be further divided into groups, as shown in the plan view in FIG. 2, and the flow rate can be adjusted for each group using the air volume adjustment valve 10. You can also do it.

Further, in the above embodiment, the heat exchanger tube is divided into two stages, upper and lower, but it can also be divided into three or more stages, and air blowing nozzles can be provided below each stage.

[Effects of the Invention] According to the present invention, load control can be performed only within the fluidized bed, so there is no need to provide an external large-capacity fluid storage container or a fluid circulation system, and therefore costs can be significantly reduced. can be reduced to

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a plan view showing an embodiment in which fine adjustment is required for air supply. FIG. 3 is a longitudinal sectional view showing an example of a conventional fluidized bed boiler. l... Pressurized fluidized bed boiler main body 2... Freeboard section, 3. Fluidized bed section 4, 4a, 4b... Heat exchanger tube, 5... Air nozzle 6a,
6b... Air supply piping 7a, 7b, 8... Air amount adjustment valve 9... Control device, 10... Air fine adjustment control valve 11... Fluid material container

Claims (1)

[Claims] A pressurized fluidized bed boiler characterized in that heat transfer tubes arranged in the fluidized bed are divided into upper and lower stages, and a plurality of nozzles for blowing air are provided below the heat transfer tubes of each stage.