JPH0419293Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention supplies coal, which is a solid fuel, onto a fluidized bed formed of relatively large particles such as gravel, and also supplies sand as a heat transfer object. This invention relates to a device for preventing clogging of a cyclone in a circulating fluidized bed boiler that improves thermal efficiency by circulating fine particles such as.

[Prior art]

As a boiler that can burn solid fuel efficiently while meeting exhaust gas emission standards,
Circulating fluidized bed boilers have been proposed in which a recirculating bed of fine particles of ash and limestone is placed above a fluidized bed, or dense bed, formed of relatively large particles such as gravel.

As shown in FIG. 2, this circulating fluidized bed boiler includes a tower-shaped combustor 1 which is a combustor, and an external heat exchanger 2 provided adjacent to the combustor 1.
A cyclone 4 on the external heat exchanger 2 and having a fluid supply port connected to the top of the combustor 1 via a connecting duct 3 communicates the external heat exchanger 2 and the lower part of the combustor 1. It is composed of a hot recycle pipe 5 and a cold recycle pipe 6.

The combustor 1 is composed of a lower dense bed area A and an upper freeboard area B having a large diameter. The dense bed area A
A dense bed 8 is formed in which a dense bed material 7 made of gravel is accommodated.

Further, this dense bed 8 is filled with coal 9 as a solid fuel and crushed limestone which is supplied for the purpose of capturing sulfur content and becomes part of the freeboard material.

The coal 9 is supplied into the dense bed 8 from a fuel supply pipe 10 provided at the upper part of the dense bed area A, and the limestone is supplied into the dense bed 8 from the lower part of the dense bed area A. In addition, a supply pipe 12 is provided at the bottom of the dense bed area A.
A fluidizing air system is provided consisting of, etc.
Fluidizing air a for fluidizing the dense bed 8
is supplied into the combustor 1. This fluidizing air a is used as fuel, but its main role is to be sent over the entire area of the dense bed 8 by means of a dispersion plate, etc., and to fluidize the dense bed material 7 as a whole.

A combustion air system composed of a supply pipe 13 and the like is provided at a location corresponding to the upper edge portion of the dense bed area A, and the combustion air b is supplied to the flow adjustment section 14.
is supplied into the combustor 1 while the supply amount is automatically adjusted.

On the other hand, the freeboard region B forms a freeboard 15 in which carbon, ash, or finely divided limestone generated by combustion in the lower stage floats and circulates. Secondary air is supplied to this freeboard 15 by a secondary air system 16 to achieve more complete combustion.

The gas G containing the freeboard material R made of carbon, ash, finely divided limestone, etc. generated in the dense bed area A and the freeboard area B is supplied to the cyclone 4 via the connecting duct 3, where the gas G is and the freeboard material R are separated, and the gas G is supplied to a boiler (not shown) and used as an energy source for steam generation.

On the other hand, the freeboard material R collected by the cyclone 4 falls under its own weight from the dipleg 17 provided at the lower part to the hot well 18 of the external heat exchanger 2. A fluidized air supply pipe 19 is provided at the bottom of this external heat exchanger 2, and fluidizes the freeboard material R.

The freeboard material R supplied into the hot well 18 overflows from the upper end of the partition wall 20 and moves into the heat exchange section 22 containing the heat transfer tubes 21 to recover heat and generate steam S. . In the heat exchange section 22, the ash contained in the freeboard material R floats to the upper layer of the fluidized freeboard material R, and passes through the gas vent pipe 23 provided at the top of the heat exchange section 22. It is discharged to the outside.

The lower part of the hot well 18 and the lower part of the combustor 1 are the hot recycling pipe 5, and the heat exchange part 22
The lower part of the combustor 1 is connected to the lower part of the combustor 1 by a cold recycle pipe 6. The freeboard material R supplied into the hot well 18 via the cyclone 4 is sent to the hot recycle pipe 5, and the freeboard material R whose temperature has been lowered by heat exchange in the heat exchange section 22 is sent to the cold recycle pipe 6. It flows back into the dense bed area A of the combustor 1. Note that one end of the gas vent pipe 23 is connected to the top of the external heat exchanger 2, and the other end is connected to the large diameter part forming the freeboard area B of the combustor 1, so that the gas inside the external heat exchanger 2 is returned to the freeboard area B of the combustor 1.

By the way, in such a circulating fluidized bed boiler, the freeboard material R adheres and accumulates inside the cyclone 4, specifically inside the dipleg 17 which is a discharge pipe of the collected material of the cyclone 4. If this condition occurs, there is a possibility that the freeboard material R may be prevented from flowing into the external heat exchanger 2. When such a situation occurs, the operation of the boiler must be stopped, and in the worst case, the temperature inside the combustor 1 cannot be adjusted, resulting in a breakage accident.

[Purpose of invention]

The present invention was made in order to solve the above-mentioned problem of poor flow of freeboard material R in the day preg 17, and its purpose is to improve the flow rate of the cyclone outlet of a circulation boiler. The purpose is to prevent clogging and enable continuous operation of the boiler.

[Summary of the idea]

In order to achieve the above-mentioned object, the present invention includes a combustor having a fluidized bed, a cyclone connected to the combustor and whose lower part communicates with an external heat exchanger, and a cyclone that communicates the external heat exchanger with the combustor. In the circulating fluidized bed boiler,
A lower part of the cyclone is communicated with an external heat exchanger via a dipleg, and the dipleg is provided with an air supply port communicating with a detector and an air supply source, and the air supply source is activated by a signal from the detector. , the pressurized air is fed into the dipleg from the air supply port.

That is, the present invention includes a means for detecting data regarding the fluidity of freeboard material such as pressure or temperature within a tape leg, an air supply source operated by the means, and a compressed air supplied from the air supply source. It consists of means for injecting into the dipleg.

Based on the data regarding the fluidity of the circulating bed material, such as the pressure or temperature inside the dipleg, for example, if the pressure rises above a predetermined range, this means that the fluidity of the freeboard material has deteriorated. Compressed air is injected into the board material to promote fluidization and discharge.

The detector detects the pressure or temperature within the dipleg or the flow rate of the freeboard material.

Pressure can be detected by constantly blowing out a small amount of compressed air into the dipreg and detecting the blowout state based on the pressure, by using the pressure difference between two points, or by using a method that uses a pressure difference between two points. A means of forming a deformable portion and detecting the amount of deformation is adopted.

〔Example〕

An embodiment of the cyclone clogging prevention device for a circulating fluidized bed boiler according to the present invention will be described below with reference to FIG.

FIG. 1 is an enlarged view of the main parts of a circulating fluidized bed boiler, and in these figures, the same reference numerals as in FIG. 2 indicate the same names.

A dipleg 17 is provided between the cyclone 4 and the external heat exchanger 2, and the dipreg 17 is provided with a pressure detector 24 as a detector.
Since the inside of the cyclone 4 is normally operated under negative pressure, the pressure detector 24 is designed to issue a signal when it detects, for example, an abnormal pressure, for example, a pressure that is within a certain range from the normal pressure.

The dipleg 17 is further provided with an air supply port 25 to which pressurized air is supplied.

In the above configuration, the circulating fluidized bed boiler has a dipleg 17 provided at the lower part of the cyclone 4.
In order to prevent outside air from flowing into the chamber, the circulating bed material R is operated to a predetermined height ΔH.

In this state, when the circulating bed material R adheres and accumulates inside the dipleg 17, its internal pressure increases.
This pressure increase is detected by the pressure detector 24, thereby providing a sign of clogging.

Then, compressed air is supplied from the compressed air supply pipe 27 through the air supply port 25 into the dipleg 17 to peel off the deposited freeboard material R and remove the blockage.

Further, as the freeboard material R accumulates inside the dipreg 17, the temperature inside the dipreg 17 decreases, so that clogging can be detected by detecting this temperature.

Note that the means for determining whether the dipleg 17 is clogged is by detecting the increase in static pressure of the pressure detector 24, the pressure difference between the dense bed area A at the bottom of the combustor 1, and the appropriate part of the freeboard area B, and detecting the difference. This can be determined by the rise in pressure. In addition, by utilizing the temperature drop of the freeboard material R, the dipleg 17
It is also possible to know if there is a blockage.

If a blockage in the dipleg 17 is detected, the driver can blow out the blockage by flowing a large amount of compressed air into the dipreg 17 at his/her discretion.

[Effect of idea]

As is clear from the above explanation, the cyclone clogging prevention device for a circulating fluidized bed boiler according to the present invention detects the pressure or temperature inside the dipreg 17 and supplies pressurized air into the dipreg 17, which is extremely simple. This configuration has the effect of preventing clogging of the circulation bed material and deterioration of fluidity, and enabling efficient continuous operation of the circulation boiler.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of essential parts of an embodiment of a cyclone clogging prevention device for a circulating fluidized bed boiler according to the present invention. FIG. 2 is an explanatory diagram of a circulating fluidized bed boiler. 1... Combustor, 2... External heat exchanger, 3...
...Continuous duct, 4...Cyclone, 5...Hot recycling pipe, 6...Cold recycling pipe, 7
...Dense bed material, 8...Dense bed, 9...
...Coal, 10...Fuel supply pipe, 11, 12, 13
... Supply pipe, 14 ... Flow rate adjustment section, 15 ... Recirculation bed, 16 ... Secondary air system, 17 ... Dipreg, 18 ... Hot recycling, 19 ... Fluidizing air supply pipe, 20 ... Partition wall , 21...heat exchanger tube, 22
... Heat exchange section, 23 ... Gas vent pipe, 24 ... Pressure detector, 25 ... Air supply port, 27 ... Pipe line, 2
9...Opening/closing valve.

Claims (1)

[Scope of utility model registration request] A combustor having a fluidized bed, a cyclone communicating with the combustor and having a lower portion communicating with an external heat exchanger, and a circulating fluidized bed boiler configured to communicate the external heat exchanger with the combustor. The lower part communicates with an external heat exchanger via a dipleg, and the dipleg is provided with an air supply port communicating with a detector and an air supply source, and the air supply source is actuated by a signal from the detector, and the air supply source is activated by a signal from the detector. A cyclone clogging prevention device in a circulating fluidized bed boiler, characterized in that pressurized air is fed into the dipleg from a supply port.