JPH0587759B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a fluidized bed in which municipal waste, industrial waste, coal, and other combustible materials are combusted in a fluidized bed, and at the same time, their thermal energy is recovered. The present invention relates to a device for recovering heat.

[Problems to be solved by conventional technology and invention]

In order to solve various problems in heat recovery from the fluidized bed in conventional fluidized bed boilers, the fluidized bed is divided into a heat recovery section and a combustion section, and the fluidized medium is circulated from the combustion section through the heat recovery section. By doing so, a device was proposed that was compact overall, had a high tolerance for combustible materials, had a large turndown ratio, and was easy to maintain.
Patent applications have been filed in JP-A No. 187001 and JP-A-62-272089.

By the way, normally, when only a part of the fluidized medium bed is made into a fluidized bed, as shown in Figure 5, the fluidized bed becomes wider as it approaches the bed surface than directly above the diffuser that blows the fluidizing gas. formed into a range.

However, as shown in FIGS. 6 to 8, the heat recovery section 32 and combustion section 33 of the conventional fluidized bed heat recovery apparatus are
Since the lower ends of the partition walls 34 between the two are located directly above the combustion section diffuser 31, the combustion section 3
The fluidization of the fluidized medium in No. 3 also reaches the heat recovery section 32, and a part of the fluidized gas in the combustion section 33 enters the heat recovery section 32, adversely affecting the control of the heat recovery section 32. In other words, it becomes difficult to control the significant reduction in the amount of heat recovered by stopping the supply of fluidizing gas from the heat recovery section diffuser 35 to the heat recovery section 32, which is a feature of the fluidized bed heat recovery device.

Furthermore, when the cross-sectional shape of the partition wall 34 is increased, a phenomenon in which the fluidized medium accumulates on the partition wall 34 is observed unless the heat recovery section air diffuser 35 is made special. This is particularly noticeable when the bed height of the fluidized medium layer in the heat recovery section 32 and the combustion section 33 is high, and when the fluidized medium accumulates, the combustion section 33
Since the movement of the fluidized medium from the heat recovery section 32 to the heat recovery section 32 is significantly hindered, a sufficient amount of heat recovery cannot be obtained. In addition, in the accumulation of fluidized media, the combustion materials contained inside burn in a non-flowing state, generating high temperatures and forming strong clinker, which may cause damage to the equipment. wake up

As described above, with conventional partition walls, some of the fluidizing gas used to fluidize the combustion section leaks into the heat recovery section, making it impossible to accurately control the amount of heat recovery. In some cases, the fluidizing medium accumulates and becomes an obstruction, which obstructs the circulation and flow of the fluidic medium, or prevents a sufficient fluidizing effect from being obtained.

The present invention is an improvement of the partition wall in such a fluidized bed heat recovery device as a result of various studies and prototype production.It is possible to easily completely burn and recover heat even from combustible materials including lumps, and to reduce the amount of combustion and heat. It is an object of the present invention to provide a fluidized bed heat recovery device in which the recovery amount can be easily adjusted.

[Means for solving problems]

The present invention provides, as a means for solving the problems related to the partition walls of the conventional fluidized bed heat recovery apparatus,
The fluidized bed, in which the fluidized medium is fluidized by fluidizing gas blown upward from the bottom, is divided into a heat recovery section whose upper and lower parts are communicated with each other by a partition wall, and a combustion section which supplies the combustion section. The flow rate of fluidizing gas blown per unit area from the combustion section aeration device of the heat recovery section at least in the vicinity of the partition wall is larger than the flow rate of fluidization gas blown per unit area from the heat recovery section aeration device of the heat recovery section. A fluidized bed heat recovery system in which the fluidized medium in the combustion section is made to flow into the heat recovery section over the partition wall, and the fluidized medium in the heat recovery section is returned to the combustion section from the lower part of the partition wall. In the apparatus, a lower end of the partition wall is located closer to the heat recovery section than directly above the combustion section diffuser, and an upper end of the partition wall is located directly above the combustion section diffuser or closer to the combustion section than directly above the combustion section diffuser. The present invention provides a partition wall in a fluidized bed heat recovery device, characterized in that:

[Effect]

The fluidized bed heat recovery device used in the present invention consists of a fluidized bed in which a fluidized medium is fluidized by fluidizing gas blown upward from the bottom, and a heat recovery section in which the upper and lower parts are connected through a partition wall. The heat recovery section is divided into a combustion section that supplies combustible materials, and the flow rate of fluidized gas blown per unit area at least near the partition wall from the combustion section aeration device of the combustion section is determined by the heat recovery section aeration device of the heat recovery section. By setting the flow rate of the fluidizing gas to be larger than the flow rate per unit area of the combustion section, the fluidized medium in the combustion section is caused to flow into the heat recovery section over the partition wall, and the flow rate of the heat recovery section is increased from the lower part of the partition wall. This device is designed to return the medium to the combustion section (see Figure 3).

As the partition wall, as shown in FIG. The bed state of the heat recovery section 2 can be changed to the combustion section 3 by setting the position at a sufficient distance to avoid being affected by the fluidized bed of the combustion section 3, that is, extending to the region of the stationary bed in Fig. 5. It can be controlled without being influenced.

Moreover, if the partition wall 4 is set vertically,
Although accumulation of the fluidized medium is unlikely to occur, the fluidized bed in the combustion section 3 only moves up and down, making it difficult to obtain the effect of mixing in the horizontal direction. It is also tilted so that it is located on the combustion section 3 side. The slope of this partition wall 4 is preferably installed at an angle of 20 to 80 degrees with respect to the horizontal. In this case, reflection from the partition wall 4 promotes a lateral velocity component in the flow of the fluid medium, and combustion The effect of horizontally mixing the inside of the fluidized bed in section 3 is provided.

Furthermore, if the partition wall 4 is installed at an angle in this way, the volume of the heat recovery section 2 can be made larger than when the partition wall 4 is installed vertically, but as shown in FIG. It is also preferable that the upper end of 4 be slightly extended vertically upward.

Furthermore, in order to prevent the accumulation of the fluid medium, it is preferable that the partition wall 4 be made into a plate shape with a somewhat thinner thickness, but it is preferable that the thickness of the upper end of the partition wall 4 be at least 200 mm or less. preferable.

Reference numeral 5 in FIGS. 1 and 2 indicates a heat recovery section air diffuser.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

In the third illustrated example, fluidizing gas, such as fluidizing air 7, is blown upward from the bottom of the furnace 6.
A fluidized bed made of a fluidized medium is separated from a heat recovery section 2 and a combustion section by a partition wall 4, which will be described later. It is divided into 3. The blowing of the fluidized air 7 into the heat recovery section 2 and the combustion section 3 is performed independently, and the flow rate of the fluidized air blown per unit area in the combustion section 3 is expressed as the unit of the heat recovery section 2. The flow rate is set to be larger than the amount of fluidized air blown per area.

A combustion section diffuser is provided at the center bottom of the combustion section 3, and the combustion section diffuser is divided into an air chamber having an air blowing surface 9 formed on the top surface, and is divided into two air chambers 10-1 and 10-1 in the vicinity of the center. The amount of fluidized air blown in is made smaller than the amount of fluidized air blown from the air chambers 10-2 on both sides, and within the combustion section 3,
As shown by the arrow, it provides a strong stirring action as well as flow, and has a large tolerance to combustion materials.

In addition, the heat recovery section 2 is equipped with a group of 11 heat transfer tubes through which the heat-receiving fluid passes, and the combustion section 3 is equipped with a combustible material inlet 1.
2, and a noncombustible material discharge port 13 is provided at the lowest position of the blowing surface 9 of the combustion section 3.

Further, in this third illustrated example, the furnace wall is constituted by a membrane outer wall 14, and this membrane outer wall 1
The partition wall 4 is constituted by a wall that branches water pipes 17 from the upper and lower headers 15 and 16 of 4 and utilizes a part of the water pipes 17, and a heat recovery section air diffuser is installed in the heat recovery section 2 near the partition wall 4. The diffuser pipes 18 are arranged side by side so that there is no part where the movement of the fluid medium stops. Of course, the amount of flowing air blown from the diffuser pipe 18 is smaller than that of the air chamber 10-2 of the combustion section 3. The group of water tubes 17 in the third illustrated example is bent at two places, so that thermal expansion can be absorbed.
etc., so that it can sufficiently withstand the violent movement of the fluid medium. However, the water pipe 17 in the part of the upper part of the partition wall 4 through which the fluid medium passes is constantly exposed to abrasion and collisions by the fluid medium. It is preferable to attach a protector 19 to at least this part of the water pipes 17 to protect each water pipe 17 from abrasion, etc. In the part below the partition wall 4, the movement of the fluid medium is not so intense, so the protector 19 is attached to the water pipe 17 at least in this part.
9 is not necessarily required. The protector 19 is made of a material that is strong at high temperatures, such as heat-resistant steel, and should be installed in close contact with the water pipe 17.The protector 19 should be considered a consumable item and should be installed so that it can be replaced once every few years. .

In addition, it is preferable that the water pipes 17 group have a gap on the inlet side of the heat recovery section 2 (the upper part of the partition wall 4) to act as a screen against lumps. If the gap on the outlet side of the section 2 (lower communication section 8 of the partition wall 7) is made larger than the gap on the inlet side, the fluidized medium etc. in the heat recovery section 2 can be smoothly returned to the combustion section 3. can.

Further, the partition wall 4 is made of a wear-resistant refractory, and the lower end of the partition wall 4 is located closer to the heat recovery section 2 than directly above the flowing air blowing surface 9 of the combustion section 3, and the heat recovery section The position is such that it does not prevent the fluidized medium of No. 2 from flowing back into the combustion section 3. The partition wall 4 extends from here at an angle of 20 to 80 degrees toward the combustion section 3, and further rises vertically upward. Even if the thickness of the partition wall 4, including the membrane wall connecting the water pipes 17, is about 100 mm, it exhibits sufficient strength due to the cooling effect of the water pipes. In addition, if the upper end of the partition wall 4 is made into an inclined surface with an appropriate angle,
Deposition of the fluid medium on this surface can be prevented.

Furthermore, the material of the partition wall 4 is preferably made of ceramics that have properties such as heat resistance, thermal shock resistance, abrasion resistance, and mechanical shock resistance, and it is possible to select and use various types of ceramics as appropriate. However, silicon carbide is particularly advantageous because it can withstand long-term use.

Thus, the combustible material introduced into the combustion section 3 in the furnace 6 from the combustible material inlet 12 is transported by the fluidizing air 7 blown from the bottom air chamber through the blowing surface 9.
It burns and generates heat while forming a fluidized bed with the fluidized medium. At this time, the amount of fluidized air blown per unit area is increased to generate large bubbles in the fluidized bed in the combustion section 3 to create an intense fluidized state, while in the heat recovery section 2, the amount of fluidized air blown per unit area is increased. The fluidization state is made weak to the extent necessary to simply promote heat transfer or to the extent that the fluidization medium can move by the amount of the fluidization medium flowing into the upper part of the bed. At this time, since the lower end of the partition wall 4 is located closer to the heat recovery section 2 than the flowing air blowing surface 9, the flowing air in the combustion section 2 does not leak to the heat recovery section 2.

Therefore, the fluidized medium near the partition wall 4 in the combustion section 3 is blown upward by the fluidized air, and a part of it flows into the heat recovery section 2 through the upper part of the partition wall 4. The heat possessed by the fluidized medium that has flowed into the heat recovery section 2 is recovered by heat exchange with the heat transfer tube 11 group. Then, in the heat recovery section 2, the pressure in the lower part increases due to the fluidized medium that has flown in, and the fluidized medium in the lower part flows back to the combustion section 3 through the communication section 8 at the lower part of the partition wall 4 as shown by the arrow.

In this way, heat is effectively recovered from the fluidized bed, and the fluidized medium other than that flowing into the heat recovery section 2 is transported to the vicinity of the center of the combustion section 3. Since the medium is forcibly moved toward the center, stirring and mixing in the horizontal direction within the combustion section 3 is efficiently performed. Moreover, since the heat recovery section 2 can be made wide due to the shape of the partition wall 4, a sufficient heat transfer surface can be provided by the group of heat transfer tubes 11.

Further, the fourth illustrated example shows another embodiment of the present invention, in which the inside of the furnace 6 is partitioned into one heat recovery section 2 and one combustion section 3 by a single partition wall 4. The operation is almost the same as that of the third illustrated example described above.

〔Effect of the invention〕

As described above, the present invention enables the flow of fluidized gas in the combustion section by specifying the positions of the upper and lower ends of the partition wall that partitions the heat recovery section and the combustion section of the fluidized bed heat recovery device as described above. It prevents heat from entering the heat recovery section, makes it easier to control the heat recovery section, effectively stirs the fluidized medium in the combustion section, and easily and completely burns even the combustible materials, including lumps, and minimizes the accumulation of fluidized media. This has very beneficial effects, such as making it possible to smoothly flow the fluidized medium and obtain a sufficient amount of heat recovery.

[Brief explanation of the drawing]

1 and 2 are diagrams explaining the shape of the partition wall of the present invention, Figures 3 and 4 are cross-sectional diagrams showing the embodiments of the invention, respectively, Figure 5 is a diagram explaining the state of the fluidized bed, and Figure 6 is a diagram explaining the state of the fluidized bed. Figures 1 to 8 are explanatory diagrams of the shape of conventional partition walls. DESCRIPTION OF SYMBOLS 1... Combustion part diffuser, 2... Heat recovery part, 3... Combustion part, 4... Partition wall, 5... Heat recovery part diffuser, 6...
Furnace, 7... Flowing air, 8... Communication section, 9... Blowing surface, 1
0-1...Air chamber, 10-2...Air chamber, 11...Heat transfer tube, 12...Combustible material inlet, 13...Incombustible material outlet,
14... Membrane outer wall, 15... Header, 16... Header, 17... Water pipe, 18... Diffuser pipe, 19... Protector, 31... Combustion section diffuser, 32... Heat recovery section,
33... Combustion section, 34... Partition wall, 35... Heat recovery section air diffuser.

Claims (1)

[Scope of Claims] 1. A fluidized bed in which a fluidized medium is fluidized by fluidizing gas blown upward from the bottom, a heat recovery part whose upper and lower parts are communicated through a partition wall, and a combustion part which supplies combustible materials. The flow rate of fluidizing gas per unit area from the combustion section diffuser of the combustion section at least in the vicinity of the partition wall is the flow rate per unit area from the heat recovery section diffuser of the heat recovery section. By setting the flow rate to be larger than the amount of gas blown into the combustion section, the fluidized medium in the combustion section is allowed to flow into the heat recovery section over the partition wall, and the fluidized medium in the heat recovery section is returned to the combustion section from the lower part of the partition wall. In the fluidized bed heat recovery device, the lower end of the partition wall is located closer to the heat recovery section than directly above the combustion section air diffuser, and the upper end of the partition wall is located directly above or directly above the combustion section air diffuser. A partition wall in a fluidized bed heat recovery device, characterized in that the partition wall is located closer to the combustion section. 2. The partition wall in the fluidized bed heat recovery apparatus according to claim 1, wherein the partition wall is inclined at an angle of 20 to 80 degrees with respect to the horizontal. 3. The partition wall in the fluidized bed heat recovery apparatus according to claim 1 or 2, wherein the upper end of the partition wall is extended vertically upward. 4 The thickness of at least the upper end of the partition wall is 200 mm.
A partition wall in a fluidized bed heat recovery apparatus according to any one of claims 1 to 3 below. 5. Fluidized bed heat recovery according to any one of claims 1 to 4, wherein the partition wall is constructed of a wall using a part of a group of tubes through which a heat receiving fluid is passed. Partition wall in equipment. 6. A patent claim in which a part of the tube group through which the heat-receiving fluid passes is extended to the upper and lower portions of the partition wall, and the gap between the tubes of the tube group is made larger on the lower side of the partition wall than on the upper side. The partition wall in the fluidized bed heat recovery device according to item 5. 7. A partition wall in a fluidized bed heat recovery apparatus according to any one of claims 1 to 4, wherein the material of the partition wall is ceramics.