JPS6324201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fluidized beds, and more particularly to a fluidized bed heat exchanger provided with a baffle arrangement for separating entrained particulate bed material from exhaust air and gaseous combustion products. Regarding.

The use of fluidized beds has been recognized as an attractive means of heat generation. In this type of device, air is passed through a bed of particulate matter consisting of a mixture of inert materials and fossil fuels such as coal to fluidize the bed and facilitate combustion of the fuel. The use of fluidized bed equipment as steam generators, boilers, vaporizers, etc. has an attractive combined effect of high heat release, improved heat transfer to surfaces within the bed, and miniaturization of the equipment. can get.

In a fluidized bed reaction process, unreacted or partially reacted particles are always entrained in the air and combustion products flowing upward from the bed escape into the area immediately above the bed, commonly referred to as the "freeboard space."
To reduce heat loss and maintain high inlet temperatures, devices of this type often must be designed to limit the height of the freeboard space to less than an optimum value.

However, limiting the height of the freeboard space as described above has disadvantages. For example, the residence time of the gas in the freeboard space is reduced, resulting in less than optimal combustion efficiency. In addition, the height of the freeboard space can be restricted by maintaining the temperature of the freeboard space at the operating temperature of the floor, at a temperature above the operating temperature, or at a temperature near the operating temperature. contradicts the design goal of promoting positive responses. Furthermore, there is a poor distribution of the gaseous combustion products and the combustion products become too rich in carbon monoxide and hydrocarbons, resulting in incomplete combustion.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fluidized bed heat exchanger with a relatively low freeboard space height and which eliminates the above-mentioned disadvantages.

Another object of the present invention is to provide a fluidized bed heat exchanger configured to increase the residence time of bed particles in the freeboard space when compared to a similar bed of the same size.

Yet another object of the invention is to provide a fluidized bed heat exchanger configured to increase the turbulence of air and gaseous combustion products to improve reaction efficiency and better gas-solid contact. It is to be.

Another object of the invention is a baffle device disposed within the freeboard space above the fluidized bed, which impinges and entrains air and particulate matter entrained in the gaseous combustion products. To provide a baffle plate device configured to remove particulate matter and cause it to fall to the floor by gravity.

Yet another object of the present invention is to inject the heat absorbing medium downward toward the floor from a location close to the baffle plate, thereby promoting a more complete reaction and controlling the entire floor surface. An object of the present invention is to provide a fluidized bed heat exchanger.

Still another object of the present invention is to provide a fluidized bed heat exchanger configured to inject a sufficient amount of additional air downwardly toward the bed from close to the baffle arrangement as described above to complete the combustion process. The goal is to provide the following.

Yet another object of the invention is to provide a fluidized bed heat exchanger with means in the freeboard section for flowing air and combustion products towards the baffle arrangement described above.

In order to achieve the above and other objects, a heat exchanger according to the invention has a grate supported within a housing and receiving a bed consisting at least in part of combustible particulate matter. Air flows through the grid and the bed of particulate matter, fluidizing the particulate matter and promoting combustion of the combustible material. The baffle device is located above the floor and collides with the particulate matter accompanying the air and gaseous combustion products to remove the particulate matter from the air and gaseous combustion products and cause it to fall by gravity. and return it to the floor. A series of tube sections are provided within the housing to direct air and gaseous combustion products toward the baffle device, and a heat absorbing medium is injected proximate the baffle device downwardly toward the floor. .

The foregoing brief description of the invention, as well as further objects, features and advantages of the invention, will be explained below with reference to the accompanying drawings, of a presently preferred but non-illustrative embodiment of the invention. We believe that you can fully understand by reading the detailed explanation.

In FIG. 1 of the drawings, which shows a fluidized bed steam generator having the features of the invention, the reference numeral 10 designates the entire enclosure consisting of a front wall 12, a rear wall 14 and two side walls designated 16. shows. The upper part of the enclosure 10, which has been omitted for illustration purposes, comprises a convection area, a roof section, and an outlet for discharging the mixture of air and combustion gases from the enclosure 10 in the conventional manner.

A bed of particulate matter, generally indicated by the reference numeral 18, is disposed inside the enclosure 10 (in this case the boiler 10) and includes a grid 20 with horizontally extending holes in the lower part of the enclosure 10. It's on top. floor 1
8 may consist of separate particles of an inert material and a fuel material such as bituminous coal. Lattice 2
Immediately below 0 is an air-filled chamber 22, and an air inlet 24 is provided through the rear wall 14 of the boiler to communicate with the chamber 22 and to distribute air to the chamber 22 from an external air source (not shown). ing. It will be appreciated that, in accordance with conventional practice, the distribution of air to the chamber 22 may be controlled by a control device (not shown) such as a wind door.

A floor ignition burner 26 is mounted through the front wall 12 and above the grate 20 to provide initial ignition of the floor 18 at the beginning of combustion.

For easy understanding, multiple feeders can be placed on one wall.
provided in one or more of 2, 14 or 16,
For example, a particulate fuel material such as coal is surrounded by a body 10.
It is also possible to supply fuel material continuously to the bed 18 by introducing it into the upper area of the bed 18. A drainage device may also be provided to remove spent particulate matter from the bed. Since these constituent members are not constituent elements of the present invention, they are not shown in the drawings and will not be described in detail.

As best seen in FIGS. 1 and 2, each wall 12, 14 and 16 is formed by a plurality of vertically extending spaced apart tubes 28 and diametrically extending along the length of each tube. It has continuous fins 30 extending from opposite locations.
The fins 30 of adjacent tubes 28 are connected together,
The resulting wall structure is airtight. Although not shown in the drawings, suitable headers, downcomers, etc. may be provided to direct water from an external source to walls 12, 14 and 16.
The water can be introduced into the lower part of the fluidized bed and flowed upward through the walls to convert the water into steam by the heat provided by the fluidized bed.

Also provided above the bed 18 of the enclosure 10 is a group of tube rows 32, one of which is illustrated in FIG. 1, to provide additional heat to the water from the fluidized bed. . Each tube has a rear wall 1 on the outside of the housing.
4 extends meanderingly from an inlet header 34 located adjacent to housing 10 to an outlet header (not shown) also located outside housing 10. The remaining tubes 32 in the tube row are tubes 32 shown perpendicular to the drawing.
extends parallel to. These tubes 32 are
It is provided to provide additional heat to the water flowing through the pipe to achieve the purpose of superheating, reheating, etc.

A plurality of spaced apart parallel chevron-shaped pieces 36 form the surrounding body 1.
It extends horizontally just above the floor 18 inside the 0. The chevron-shaped piece 36 extends across the width of the housing in the middle of the side wall 16 and is supported at its relative ends to the side wall 16 by ears, support beams, or surrounding wall attachments, etc., in conventional manner. has been done. The chevrons 36 are disposed with their apexes upward, and a distributor or distribution pipe 38 is nested within each chevron 36 and extends the entire length of the chevron. As shown in FIG. 2, a plurality of pipes 38 extend in spaced apart parallel relationship between two headers 40 and 42 (see FIG. 2) to absorb heat from an external source into the pipes 38. Dispense the media. As shown in FIG. 1, a plurality of holes or discharge openings are formed in the lower portion of the pipe 38 so that the heat absorbing medium is directed outwardly and downwardly toward the floor.
It is discharged towards 8th. Examples of heat absorbing media injected from the distributor 38 may include air, liquid, flue gas or reflux dust or reflux material, as well as receptors such as fresh limestone. In this way, detectable heat inside the freeboard space can be absorbed and, at the same time, CO ₂ can be removed from the mixture of air and gaseous combustion products by means of the receptor, while the enclosure 10 It is possible to avoid overloading the capacity of the combined outlet. Also, when air is used as the heat absorbing medium, sufficient air can be injected to completely burn out the particulate fuel material in the bed.

A plurality of vertical pipes, only one of which is shown with reference numeral 44 in FIG.
2 and these vertical pipes can be provided with small holes to allow additional heat absorption medium to be released into the enclosure 10.

The tube 46 is located directly below the chevron 36 and above the top surface of the floor 18. The tube 46 is curved so that a plurality of spaced tube sections 46a are formed. As shown in FIG.
The ends of the tubes 2 extending outwardly from the corresponding side walls 16 can be connected to a source of cooling fluid, which includes the tubes 2 forming the walls 12, 14 and 16.
The cooling fluid source supplying water to 8 and tubes 32 may be the same. As can be seen in FIGS. 1 and 3, the pipe section 46a is connected to the chevron 36 and the distribution pipe 3.
8, which directs air and gases from the bed 18 to the chevrons and distribution pipes for reasons explained in more detail below.

In operation, air is introduced into chamber 22 through inlet 24 and flows upwardly through grate 20 and into the bed, loosening particulate matter in bed 18 and fluidizing the bed. The ignition burner 26 ignites the particulate fuel material until the bed 18 is heated to a predetermined temperature and combustion of the particulate fuel material is maintained, and then the ignition burner is turned off and the amount of fuel necessary to maintain the predetermined bed temperature is ignited. Add new particulate fuel material.

As shown in FIG. 3, the mixture of air and gaseous combustion products flowing upwardly from bed 18 flows into pipe section
6a are arranged in a staggered relationship to the chevrons 36 so that the flow follows a tortuous path. With the aid of tube section 46a, the mixture flows towards the angle piece 36 and distribution pipe 38, where it impinges on the angle piece and the distribution pipe, and the particulate matter entrained in the mixture is separated and the particulate matter falls back to the floor due to gravity. This not only lengthens the reaction time of the entrained particles, but also increases the turbulence within the freeboard, promoting a more complete reaction and creating uneven combustion gases and air. The products are forcibly mixed, making the product uniform.

Distribution pipe 38 distributes heat absorbing media from manifolds 40 and 42 to bed 18 to promote more complete reaction and control bed temperature. That is, peak temperatures are reduced or limited and the inherent violent effects of the fireball zone are alleviated. The heat absorbing medium from the distribution pipe 38 also serves to force the entrained particulate matter downwardly and back into the bed.

Pipes 44 are used to inject additional heat absorbing media into the freeboard area or directly onto the floor to provide cooling and reduce the potential entrainment of the air and gas mixture flowing upward in the freeboard area. It can blow away some fine dust.

It should be noted that the chevron 36, distribution pipe 38 and tube section 46a act as a heat dissipation screen above the bed to retain sufficient reaction heat to make the reaction more complete in the freeboard area. That's true.

Cooling fluid is supplied to tube 46 from the same source as the fluid passing through walls 12, 14 and 16.
It may also be introduced into the tubes and flowed through tube sections 46a to keep these tube sections cool and to aid in temperature control of the freeboard zone.

As a result of the above-described arrangement, it is possible to limit the height of the freeboard to reduce heat losses and maintain a high inlet temperature to the gas turbine generator, while eliminating the disadvantages mentioned above.

Another embodiment of a fluidized bed heat exchanger according to the invention is shown in FIG. 4, in which identical parts have been given the same reference numerals. In the embodiment of FIG. 4, the rear wall 1
4 is higher than the front wall 12 and a gas exhaust opening 50 is formed in the upper part of the rear wall. As shown, the enclosure 10 is provided with a roof 52 that slopes upwardly from the front wall 12 to the rear wall 14. With this arrangement, the mixture of air and gaseous combustion products is
As shown by the arrow in the figure, it flows upward and to the right. Angled piece 36, gas distributor 38
(Thus, headers 40 and 42) and tube 46 are
It is arranged adjacent to the discharge port 50 at the upper right corner of the housing, and is arranged in a plane inclined at a certain angle with respect to the horizontal direction. As a result of this arrangement, air and gases flowing upward from the floor 18 are
It passes over each member in the same manner as in the previous embodiment. Accordingly, the embodiment of FIG. 4 provides the same benefits and features disclosed in the embodiment of FIGS. 1-3.

According to the invention, a bed 18 of particulate matter inside the housing and a discharge means ( A plurality of spaced apart baffle plate members (angular pieces 36) are disposed between the outlet and the outlet combined with the enclosure. The directing means (tube 46) includes one directing element;
This directing element has a staggered shape with respect to the baffle members as well as with respect to the injection means (distribution pipe 38) which injects the heat absorbing medium downwardly towards the floor from at least the vicinity of these baffle members. It has a plurality of sections (pipe sections 46a) arranged in a staggered manner. This configuration directs the mixture of air and gaseous combustion products to the chevron 36 and the distribution pipe 38;
By colliding with these particles, particulate matter entrained in the mixture is separated. These separated particulate matter fall onto the floor by gravity.
Therefore, the reaction time of the entrained particles becomes longer,
The turbulence in the freeboard area is increased, ensuring a more complete reaction and uniformity of the product. Yamagata piece 3
6. The distribution pipe 38 and tube 46 are connected to the bed 18 to maintain the required high heat of reaction in the freeboard zone to produce a more complete reaction.
Acts as a heat dissipation screen above. The heat absorbing medium is discharged through the distribution pipe 38, but only to reduce or limit the bed temperature from its peak value or to reduce the intensity of the action of the fireball zone. In this way, the discharge of the heat-absorbing medium from the distribution pipe 38 does not have the opposite effect on forming a heat-dissipating screen as described above, but only when a special need arises, i.e. more or less normally. used only under circumstances where

In the foregoing description, for illustrative purposes, both embodiments of the invention have been described in connection with a steam generator; however, within the scope of the technical idea of the invention, embodiments of the invention may We believe that it is readily apparent that other types of fluidized bed heat exchangers can be used.

Many modifications, changes, and substitutions are possible within the scope of the above disclosure, and in some cases, applications may be envisaged without employing some features of the invention while making use of the remaining features. Therefore, the claims should be interpreted broadly and should be interpreted in accordance with the technical spirit and scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a portion of a fluidized bed heat exchanger according to the invention. Figure 2 shows 2- in Figure 1.
FIG. 2 is a cross-sectional view taken along two lines. Figure 3 shows
FIG. 2 is an enlarged cross-sectional view of a portion of the configuration of FIG. 1; Fourth
The figure is a partial vertical sectional view showing another embodiment of the invention. 10... Enclosing body (boiler, housing), 1
8... Floor, 20... Lattice, 36... Chevron piece, 38
... distribution pipe, 46 ... pipe, 46a ... pipe section.

Claims (1)

[Claims] 1 a housing; supported within the housing;
grate means adapted to receive a bed of particulate matter, at least a portion of which is combustible, and introducing air through the grate means and the bed of particulate matter to fluidize the bed and to an air introduction means for promoting combustion of the gaseous substance; an evacuation means disposed in the upper part of the housing for evacuation of the air and gaseous combustion products from the housing; baffle means including spaced apart baffle members, the baffle members impinging on and dislodging entrained particulate matter in the air and gaseous combustion products. disposed between the bed of particulate matter and the evacuation means to remove the particulate matter from the air and the gaseous combustion products and cause the particulate matter to fall to the bed by the action of gravity; further comprising directing means disposed in the housing for directing the air and gaseous combustion products toward the baffle means, the directing means comprising:
at least one element having a plurality of compartments disposed in a staggered relationship with respect to the baffle member; injection means for injecting the heat absorbing medium downwardly towards the floor, the baffle means, the directing means and the injection means being arranged in the upper part of the floor to retain heat in the lower part of the floor; Fluidized bed heat exchangers that work together as a heat dissipation screen.