JPH01203801A - Fluidized bed boiler with vertical heat transfer tubes and fluidized bed hot water boiler using the boiler - Google Patents

Abstract

PURPOSE:To enable easy maintenance of a combustion temperature at a specified value through variation of the height of a fluid medium, by a method wherein a plurality of heat transfer pipes are vertically arranged in a combustion chamber provided at its lower part with a gas dispersion plate and at its upper part with a combustion gas exhaust port. CONSTITUTION:A plurality of vertical heat transfer pipes 11 are disposed in a combustion chamber 10 of a boiler drum body 10 in a manner to be approximately uniformly arranged on the surface in cross section of the combustion chamber 20. The upper and the lower part of each of the heat transfer pipes are securely mounted in a manner to extend through a partition wall 22, by which the combustion chamber 20 is partitioned, and gas dispersion plate 21. The lower and the upper end of the vertical heat transfer pipe 11 are opened in a feed water collecting chamber 23, positioned below the gas dispersion plate 21, and an upper collection chamber 24, respectively, positioned above the partition wall 22. Through variation of the height of a fluidized bed 12 in response to the fluctuation in a load of a fluidized bed boiler, the contact area if the vertical heat transfer pipe 11 making contact with a fluidized bed 12 is proportionally changed. This constitution enables reliable and easy maintenance of floor temperature (combustion temperature) at a specified value or maintenance of the width of a fluctuation in temperature at a very low value.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a fluidized bed boiler with vertical heat transfer tubes that uses solid fuel such as coal. A fluidized bed boiler with vertical heat exchanger tubes that enables stable boiler operation by easily maintaining a constant combustion temperature even when solid fuels with different calorific values are used, and the use of this boiler to produce hot water extremely efficiently. The present invention relates to a fluidized bed hot water boiler that can be obtained.

[Conventional technology]

Conventionally, in a fluidized bed boiler, a fluidized medium such as sand is fluidized with gas such as air supplied from a gas distribution plate at the bottom, and a solid fuel such as coal is supplied to this fluidized medium to form a fluidized bed. It is known that fluidized combustion is performed and the combustion heat is absorbed by heat transfer tubes arranged horizontally in multiple stages in the fluidized bed. (For example, Japanese Patent Publication No. 61-37523) By bringing the fluidized medium into contact with the heat transfer tube to absorb heat in this way, a high heat transfer coefficient can be obtained, making it suitable for use as a boiler.

[Problem to be solved by the invention]

However, in conventional fluidized bed boilers in which heat exchanger tubes are arranged horizontally, the installation height of the heat exchanger tubes is fixed, and once installed at the set height, it cannot be changed. When changing the load or using fuels with different calorific values, a constant combustion temperature can be maintained by changing the thickness of the fluidized bed and changing the heat transfer area, i.e., maintaining a constant fluidized bed temperature. Even if you try to do so, the heat exchanger tubes are arranged horizontally, so even if you install multiple stages of heat exchanger tubes, there is a limit to the number of stages where the fluid medium and the heat exchanger tubes come into contact, and there is a limit to the adjustment of the contact area of the heat exchanger tubes. As a result, it was difficult to keep the temperature of the fluidized bed constant. If the temperature of the fluidized bed is not kept constant, not only will the combustion efficiency deteriorate;
For example, if the combustion temperature becomes too high, problems such as solidification and agglomeration (clinker formation) of fluidized media such as sand due to melting of combustion ash occur, making normal operation impossible.

Furthermore, in the case of conventional horizontal heat exchanger tubes, proper circulation could not be achieved unless the fluid inside the heat exchanger tubes was forced to circulate using a pump or the like.

In the present invention, contact heat transfer between a fluid medium with a high heat transfer coefficient and a heat exchanger tube can be used as is, natural circulation can be easily obtained by using vertical heat exchanger tubes, and even when changing the boiler load or different The aim is to obtain a fluidized bed boiler that can easily maintain a constant combustion temperature by changing the height of the fluidized medium even when using fuel with a high calorific value.
Another object of the present invention is to obtain a fluidized bed hot water boiler that can easily produce hot water with high efficiency using the boiler.

[Means to solve the problem]

In order to achieve the above object, the fluidized bed boiler of the present invention has a plurality of heat transfer tubes arranged vertically inside a combustion chamber having a gas distribution plate at the bottom and a combustion gas discharge port at the top. It was established as follows.

Furthermore, a plurality of heat transfer tubes are arranged vertically inside the combustion chamber, which has a gas distribution plate at the bottom and a combustion gas exhaust outlet at the top, and a water supply passage is formed around the combustion chamber to form a boiler body. The outer wall of the combustion chamber is formed as a heat transfer surface, and the inlet and outlet of the water supply of the vertical heat exchanger tube are opened to the water supply passage of the boiler body at the lower and upper parts of the combustion chamber, respectively. A fluidized bed hot water boiler is constructed by providing a water supply inlet and a hot water outlet at the lower and upper parts of the boiler, respectively.

[Effect]

In a fluidized bed boiler with vertical heat transfer tubes configured as described above, a plurality of heat transfer tubes are installed vertically inside the combustion chamber, so by adjusting the height of the fluidized medium, the The contact area with high heat transfer efficiency between the medium and the heat transfer tube can be changed in proportion to the height of the fluidized medium, and changes in the amount of heat transfer can be reliably and easily adjusted, so the combustion temperature, that is, the temperature of the fluidized bed can be kept constant. It is easy to maintain stable operation. Note that if a plurality of vertical heat exchanger tubes are suitably arranged so as to be approximately evenly distributed over the cross section of the combustion chamber, the temperature can be maintained constant even better.

When changing the boiler load, the amount of fuel commensurate with the load is supplied, and the height of the fluidized medium (fluidized bed) is changed by introducing the amount of air necessary for the fuel from the gas distribution plate, and the combustion temperature is maintained at a constant level. is maintained.

In addition, when using fuels with different calorific values, the required amount of fuel and the amount of air required for combustion are introduced from the gas distribution plate to fluidize the fluidized medium and burn it, as described above.
Even in this case, the height of the fluidized medium is determined according to the calorific value of the fuel, and the combustion temperature is maintained at a constant level.

In the fluidized bed hot water boiler of the present invention, hot water is created by the contact between the vertical heat transfer tubes in the combustion chamber and the fluidized medium, and the contact between the heat transfer tubes and the combustion gas in the freeboard section, and further between the combustion chamber and the boiler. The feed water flowing through the passage between the cylinder and the shell is heated by absorbing the heat retained by the fluidized medium in the combustion chamber and the heat retained by the combustion gases in the freeboard section through the walls of the combustion chamber. Since the effective heat transfer area with the water supply is increased in this way, a compact hot water boiler can be obtained. In addition, since vertical heat exchanger tubes have no resistance to the heating and rising of hot water, they facilitate natural circulation and are advantageous in terms of safety. Even when changing the amount of hot water or using fuel with a different calorific value, a constant combustion temperature can be maintained and stable operation can be performed, as in the case of the fluidized bed boiler.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a schematic longitudinal sectional view showing the overall configuration of a fluidized bed boiler having vertical heat exchanger tubes according to an embodiment of the present invention, and FIG.
The figure is a sectional view taken along the line ■ to ■ in FIG. It is a sectional view taken along the line ■ to ■.

First, a fluidized bed boiler having vertical heat exchanger tubes according to the present invention will be explained based on FIGS.
As shown in the figure, a plurality of vertical heat exchanger tubes 11 are connected to a combustion chamber 20.
The upper and lower parts of the combustion chamber 20 are fixed to each other by passing through the partition wall 22 and the gas distribution plate 21 that define the combustion chamber 20, respectively.

The lower and upper ends of the vertical heat transfer tubes 11 are opened into a water supply collecting chamber 23 located below the gas distribution plate 21 and an upper collecting chamber 24 located above the partition wall 22, respectively. Reference numerals 23a and 24a are a water supply port and a steam outlet, respectively, and reference numeral 25 is a supply port for solid fuel such as coal.

An air chamber 30 having an air intake port 30a on the side through the water supply collection chamber 23 is disposed in the lower part of the fuel chamber 20, and a plurality of distributors (
An air jet nozzle) 31 is provided to pass through the water supply collection chamber 23 and the gas distribution plate 21, and air as combustion air that also serves as fluidization is sent to the distributor 3.
1 is supplied into the combustion chamber 20 from the upper side.

This distributor 31 is also arranged substantially evenly with respect to the cross section of the combustion chamber 20.

A combustion waste gas chamber 40 is disposed in the upper part of the combustion chamber 20 via the upper collecting chamber 24, and a large number of combustion chambers 20 and combustion waste gas chambers 40 are provided passing through the upper collecting chamber 24. It is connected by a waste gas pipe 40a, and the combustion chamber 20
After flowing into the waste gas pipe 40a from the waste mountain port 26 and introduced into the combustion waste gas chamber 40, the combustion gas flows into the waste gas outlet 4.
1, and is sent to the next process (not shown), such as a waste gas processing device such as a waste heat boiler or a waste gas dust collector.

In the fluidized bed boiler configured in this way, the fluidized medium such as sand is fluidized by the combustion air supplied from the air chamber 30 through the distributor 31 into the combustion chamber 20, and the fluidized bed 12 in the combustion chamber 20 is fluidized. When, for example, coal as a fuel is introduced into this bed from the combustion supply port 25, it is vigorously mixed and burned in the fluidized bed 12, and the vertical heat exchanger tubes 11 in contact with the fluidized bed I2 are The freeboard section 13 above the fluidized bed 12 absorbs the heat of the combustion exhaust gas to produce hot water or steam, which is taken out from the steam outlet 24a. At this time,
The temperature (combustion temperature) of the fluidized bed 12 is, for example, 900 to 950.
Maintained at a constant temperature of °C. The combustion waste gas passes through the freeboard portion 13 of the combustion chamber 20, is sent from the upper waste gas pipe 40a to the combustion waste gas chamber 40, and is further sent from the waste pipe port 41 to the next process waste gas processing device.

Therefore, by changing the height of the fluidized bed 12 in response to changes in boiler load, vertical heat exchanger tubes 1 to the fluidized bed 12 can be
1 contact area is changed proportionally.

For example, when the boiler load is increased, the amount of coal supply and the amount of combustion air are correspondingly increased, and the height of the fluidized bed 12 increases from the level A to the level B in FIG. .

In this way, by changing the height of the fluidized bed 12 in response to load fluctuations in the fluidized bed boiler, the contact area of the vertical heat transfer tubes 11 in contact with the fluidized bed 12 changes proportionally. temperature) reliably and easily, or
It becomes possible to keep the temperature fluctuation range extremely small. That is, the bed temperature is maintained at 900 to 950°C even when the load is changed from level A to level B.

As a result, the temperature of the fluidized bed decreases, resulting in poor combustion efficiency.
This prevents troubles such as inoperability or the temperature of the fluidized bed rising too much and causing combustion ash to melt.
The boiler can be operated stably.

Note that the vertical heat exchanger tube 11 is connected to the combustion chamber 20 as shown in FIG.
The fluidized bed 1
If heat is absorbed evenly from 2, it is possible to maintain the fluidized bed temperature more stably and uniformly, and the temperature of the fluidized bed becomes high in some parts, causing coal ash to melt and causing the fluidized medium to melt. It does not stick and inhibit its fluidization, thereby interfering with stable operation.

Moreover, by employing the vertical heat exchanger tubes 11, there is no resistance to the heating and rising of the supplied water, so that the flow can be carried out smoothly.

On the other hand, even when changing to a fuel with a different calorific value, the contact area of the vertical heat transfer tubes 11 with the fluidized bed 12 can be easily changed and adjusted, so the height of the fluidized bed can be kept constant by adjusting the height of the fluidized bed to match the calorific value of the fuel. The boiler can be operated while maintaining the combustion temperature.

Therefore, various solid fuels can be used in the boiler of the present invention. For example, waste fuels such as coal, oil coke, and waste plastics, or solid fuels made by mixing these can be used.

Next, FIG. 3 shows an embodiment of the fluidized bed hot water boiler of the present invention.
This will be explained based on FIG. Note that the same parts as in FIGS. 1 and 2, or parts corresponding thereto, are designated by the same reference numerals.
The explanation will be omitted.

Reference numeral 50 indicates a body of a hot water boiler, and a combustion chamber 20 surrounded by a combustion chamber furnace wall 20a, an upper partition wall 22, and a lower gas distribution plate 21 is located in the center of the boiler body.
An air chamber 30 for supplying combustion air is arranged at the bottom,
A combustion waste gas chamber 40 is arranged in the upper part. A water supply passage defined by the boiler body 50, an upper partition wall 51, and a lower partition wall 52 is formed around the combustion chamber between the boiler body 50 and the combustion chamber 20, and this water supply passage is connected to the lower passage 6.
1, a vertical passage 62, and an upper passage 63.

The outer wall of the combustion chamber furnace wall 20a is in direct contact with the water supply and is formed as a heat transfer surface. Note that it is more effective if the partition wall 22 and the gas distribution plate 21 are formed as a heat transfer surface to the water supply. Inside the combustion chamber 20, a plurality of vertical heat exchanger tubes 11 are arranged so as to be distributed almost uniformly with respect to the cross section, and the upper ends thereof open to an upper passage 63 for water supply. The lower end opens into a lower passage 61 for water supply. A plurality of distributors 31 are disposed on the gas distribution plate 21 at the lower part of the combustion chamber 20, and the distributors 31 pass through the lower passage 61 of the water supply, have their lower ends open to the air chamber 30, and are connected to the lower partition wall 52. installed on. Combustion air that also serves as fluidization is supplied into the combustion chamber 20 from the upper side of the combustion chamber 20 of the distributor 31 .

A supply port 50a for supplying water to the hot water boiler is provided at the bottom of the boiler body 50, and an outlet 50b for taking out heated water (hot water) is provided at the top.

A waste gas pipe 40a is provided between the partition wall 22 at the top of the combustion chamber 20 and the combustion waste gas chamber 40. 41 is a waste gas outlet.

In the fluidized bed boiler configured in this way, when water is supplied into the boiler barrel from the supply port 50a, the vertical passage 6
2. It passes through the lower passage 61 and the upper passage 63, and is supplied from the lower passage 61 into the vertical heat exchanger tube 11 provided inside the combustion chamber 20, passes therethrough, and is discharged to the upper passage 63.

On the other hand, combustion air is supplied to the air chamber 30 from the air intake port 30a, further supplied into the combustion chamber 20 from the upper side opening of the distributor 31 of the gas distribution plate 21, and coal etc. taken in from the fuel supply port 25. It is used to fluidize fuel and a fluid medium such as sand, and to burn coal.

Therefore, the vertical heat exchanger tubes 11 in contact with the fluidized bed 12 absorb heat from the fluidized bed 12 through their contact surfaces with a high heat transfer coefficient to heat the feed water passing through the heat exchanger tubes 11, and the fluidized bed 12 imparts heat through the combustion chamber furnace wall 20a to the feed water passing through the vertical passage 62 around the combustion chamber 20. moreover,
In the freeboard section 13 located above the fluidized bed section 12, the combustion waste gas transfers heat to the feed water in the vertical heat transfer tubes 11 in the combustion chamber 20 and the feed water flowing through the vertical passage 62 via the combustion chamber furnace wall 20a. After giving , it is discharged into the combustion waste gas chamber 40 via the waste gas pipe 40a, and is further sent from the waste gas outlet 41 to the waste gas treatment device in the subsequent process.

In such a fluidized bed hot water boiler, even when changing the amount of hot water or using fuel with a different calorific value, combustion can be maintained by adjusting the height of the fluidized bed according to the case, as in the case of the fluidized bed boiler described above. Stable operation with a constant temperature of, for example, 900 to 950°C can be performed extremely reliably and easily. In the hot water boiler of the present invention, the water supply and the fluidized bed 1
Since the contact area with the combustion waste gas is effectively ensured in the parts 2 and 13 of the free board, the thermal efficiency is very high.

Therefore, the hot water boiler itself can be formed compactly. In addition, since the vertical heat exchanger tubes 11 have no resistance to the increase in temperature of the hot water, natural circulation is easy and it is advantageous in terms of safety. Further, as for the fuel, various solid fuels as described above can be used.

〔Effect of the invention〕

Since the present invention is configured as described above, it has the following effects.

In a fluidized bed boiler with vertical heat transfer tubes, by adjusting the height of the fluidized bed, the contact area between the heat transfer tubes and the fluidized bed can be adjusted much more reliably and easily than in boilers using conventional horizontal heat transfer tubes. Therefore, even when changing the boiler load or using fuel with a different calorific value, the combustion temperature (fluidized bed temperature) can be kept constant or its fluctuations can be kept within an extremely small range, resulting in a stable boiler. can drive.

In addition, in a fluidized bed hot water boiler, the effects of the fluidized bed boiler can be exhibited as is, stable operation is possible, and the contact area between the water supply and the combustion waste gas in the fluidized bed and freeboard section is reduced. It is possible to obtain a compact hot water boiler that is effectively secured and has good thermal efficiency. In addition, a wide variety of fuels can be used, there is no resistance to increases in the temperature of the feed water, natural circulation is easy and safe, and a versatile hot water boiler can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view showing the overall configuration of a fluidized bed boiler having vertical heat exchanger tubes according to an embodiment of the present invention, and FIG.
3 is a schematic longitudinal sectional view showing the overall configuration of a fluidized bed hot water boiler according to an embodiment of the present invention, and FIG. 4 is a sectional view taken along the line ■ to ■ in FIG. 3. FIG. 10...Boiler body, 11...-Vertical heat exchanger tube, 12.
- Fluidized bed (fluidized medium), 2 (L- Combustion chamber, 20 a- Combustion chamber furnace wall, 21 - Gas distribution plate, 30 - Air chamber, 4
0-...-Combustion waste gas chamber, 50-Hot water boiler body, 61
- lower passage, 62 - - vertical passage, 63 - upper passage. Patent applicant: Ube Industries, Ltd.

Claims (2)

[Claims] (1) A flow system with vertical heat transfer tubes, characterized in that a plurality of heat transfer tubes are vertically arranged inside a combustion chamber that has a gas distribution plate at the bottom and a combustion gas exhaust outlet at the top. floor boiler. (2) A plurality of heat transfer tubes are arranged vertically inside a combustion chamber that has a gas distribution plate at the bottom and a combustion gas exhaust outlet at the top, and a water supply passage is formed around the combustion chamber. A boiler body is arranged, the outer wall of the combustion chamber is formed as a heat transfer surface, and the inlet and outlet of the water supply of the vertical heat exchanger tube are opened to the water supply passage of the boiler body at the lower and upper parts of the combustion chamber, respectively, A fluidized bed hot water boiler characterized in that a water supply port and a hot water discharge port are provided at the bottom and top of the boiler body, respectively.