JP2567690B2 - Fluid bed boiler fuel supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to coffee grounds, tangerine grounds, beer grounds, tea grounds,
The present invention relates to a fuel supply device for a fluidized bed boiler when burning a high water content residue for waste containing high water content such as sludge or coal.

[Prior Art] Conventionally, various methods for burning solid fuel such as coal and waste in a fluidized bed are known.

In other words, when supplying fine particles and lump fuel such as coal to the inside of the fluidized bed, a fuel supply pipe is arranged from the side wall of the fluidized bed toward the center of the fluidized bed above the fluidized interface of the fluidized heat medium in the fluidized bed. A method in which the tip of the fuel supply pipe is directed to the fluid interface, and the fine particles transported by pneumatic transportation are dispersed and supplied downward on the fluid interface.A spreader is attached to the side wall of the fluid interface above the fluid interface. A method for supplying solid fuel supplied from the tip of a fuel supply pipe disposed in the upper region of the spreader to the upper portion of the spreader so as to disperse and supply the solid fuel on the flow interface by utilizing the peripheral speed difference of the blades of the spreader There is a method in which the fuel supply pipe and its tip are immersed and disposed while the fluidized heat medium forming the fluidized bed is floating, and the fine particles transported by pneumatic transportation are supplied into the fluidized bed.

When supplying sludge etc. into the fluidized bed,
A method of providing a rotary valve on the outer side wall of the fluidized bed, inserting the fluidized bed side wall under the transport side end of the rotary valve and arranging the chute at an arbitrary inclination angle and supplying the chute from the tip to the upper part of the fluid interface, There is a method in which a screw feeder is inserted substantially at right angles to the side wall of the fluidized bed, and the tip end on the conveying side of the screw feeder is supplied to the upper part of the fluid interface.

Furthermore, when supplying highly water-containing waste such as beer cake or coffee cake to the inside of the fluidized bed, the fuel supply pipe is extended from the side wall into the floating heat medium of the fluidized bed using the above-described screw feeder supply method and a high-pressure pump. Or arrange it,
Alternatively, there is a method of arranging and supplying above the flow interface.

[Problems to be Solved by the Invention] However, when the waste and the solid fuel are to be supplied by the above-described supply method, the supply pipe of the waste and the solid fuel is immersed in the floating heat medium of the fluidized bed and disposed. When the wastewater or solid fuel is supplied from the upper part of the flow interface, the wastewater or the solid fuel is supplied from the upper part of the flow interface, and the wastewater or Until a part of the solid fuel reaches the flow interface, it is swept away by the air flow and is entrained downstream, so that there is a disadvantage that unburned matter increases and combustion efficiency decreases.

[Means for Solving the Problem] In order to solve such a problem, the present invention includes a primary combustion chamber having a primary combustion bed having a fluidized heat medium and a primary combustion space. An air chamber having an auxiliary combustion burner and an air inlet for combustion is provided in the lower stage of the combustion chamber,
At least one or more stages of another combustion bed having a fluidized heat medium and another combustion chamber are provided in the upper stage of the primary combustion chamber, and further, between the primary combustion bed and the air chamber and in the upper stage combustion chamber. In the multi-stage fluidized bed boiler, in which partition plates and water cooling tubes are alternately arranged in the horizontal direction at right angles to the longitudinal direction of the water cooling tubes between the lower combustion spaces, and then connected, the water cooling tubes of the outer tubes through which circulating water flows , A fuel supply pipe of an inner pipe for supplying fuel is provided in a double pipe shape, the double pipe is provided in a partition plate between the primary combustion chamber and the air chamber, and a substantially central portion of a bottom plane of the primary combustion chamber. The fuel drive pipe is arranged so that its tip end portion is directed toward the primary combustion chamber from the middle of the pipe.

[Operation] A water cooling pipe that fluidizes a heat transfer medium such as sand in the lower primary combustion chamber by the air supplied from the lower air chamber and causes circulating water to flow through the outer pipe to the partition plate of the primary combustion chamber. In addition, the high water content residue is supplied from the double-tube fuel supply pipe of the fuel supply pipe for flowing the fuel to the inner pipe, and the auxiliary combustion source by the auxiliary combustion burner, the combustion air and the fluidization pipe are supplied from the air chamber. When air is supplied, the high water content residue in the primary combustion bed is about 70-70% at the same time as drying at 800-900 ° C.
After being burned, about 30% of unburned residue remains,
The remainder is burned while flowing with a fluidized heat medium such as sand in at least one upper-stage secondary combustion chamber or the like immediately above the primary combustion chamber, completely burned up to this point, and finally the fluidized bed top exhaust gas outlet. Is discharged from

On the other hand, the circulating water sent from the circulation pump is sent to the waste heat boiler after separately passing through water cooling pipes arranged in the partition plates of the primary combustion chamber and the secondary combustion chamber, and from the circulation pump. It is divided into routes for directly sending water to the waste heat boiler, and finally, heat exchange with combustion exhaust gas is effectively performed in the waste heat boiler.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. The drawings each show an embodiment of the present invention, and FIG. 1 is a schematic sectional view showing the overall configuration of a fluidized-bed boiler.
FIG. 2 is a partially enlarged perspective view of a gas distribution plate showing a state of disposing a fuel supply pipe in a double-tube shape when the protective end of the fuel supply pipe is not detachably attached, and FIG. A partially enlarged perspective view of a gas distribution plate showing a disposition state of a fuel supply pipe of a double tubular shape in the case of having a removable protective cover at a tip end portion,
FIG. 4 is a partially detailed vertical sectional view of a double-piped fuel supply pipe showing IV-IV cutting in FIG. 2 when a wear-resistant cast steel protective cover is not attached to the tip of the fuel supply pipe, and FIG. Fig. 3 V to Fig. 3 when a wear-resistant cast steel protective cover is attached to the tip of the pipe
FIG. 3 is a partially detailed vertical sectional view of a double-piped fuel supply pipe showing V-cutting.

The configuration of this apparatus will be described with reference to FIGS. 1, 2, 3, 4, and 5.

The apparatus shown in FIG. 1 includes a fluidized bed boiler 1, a lowermost air chamber 2, an upper primary combustion chamber 3, an upper secondary combustion chamber 4, air introduction pipes 5, 5a, partition plates 6, 6a, a fuel supply pipe 7, fluid heat mediums 8, 9, an auxiliary combustion burner 10, a combustion / fluidization air inlet 11, castables 12, 12a, and water cooling pipes 13, 13a, 13b.

That is, in this embodiment, a two-stage bed is provided as a multi-stage bed.

Here, the case of burning the high water content residue will be described.

A burner 10 for auxiliary combustion, which is directed to the horizontal direction, is provided on the side of the air chamber 2, and burns heavy oil or gas fuel to the primary combustion chamber 3 via a fuel supply pipe 7. High water content residue 30 supplied to the primary combustion bed 20
It is possible to help the drying and combustion of the primary combustion chamber 3 and maintain the desired temperature in the primary combustion chamber 3. Reference numeral 11 denotes an inlet for air for combustion and fluidization, which is heated by a heat exchanger (not shown) using the exhaust gas discharged from the outlet 35 at the top of the fluidized bed, so that an appropriate amount of air can be supplied into the air chamber 2. I made it.

The primary combustion chamber 3 is composed of a primary combustion bed 20 containing a fluidized heat transfer medium 8 made of, for example, general sand having an average particle size of about 0.6 mm, and a primary combustion space 21 above the primary combustion bed 20. 2
And the primary combustion chamber 3 immediately above the air chamber 2
A horizontal partition plate 6 is provided vertically penetrating through a number of air introduction pipes 5, and a castable portion is provided at an upper portion (primary combustion chamber side) and a lower portion (air chamber side) of the partition plate 6.
At 12, a water cooling pipe 13 provided in the partition plate 6 is embedded, and the secondary combustion chamber 4 is also castable 12a at the upper and lower portions of the partition plate 6a as in the primary combustion chamber 3. Further, instead of the water-cooling pipe 13 which should be disposed in the substantially central portion of the bottom surface of the partition plate of the primary combustion chamber 3, the outer pipe is used as the water-cooling pipe 13 for circulating water, and the inner pipe is used for the fuel supply pipe 7. In order to be able to supply the fuel, the water cooling pipe 13 and the fuel supply pipe 7 are arranged in a double pipe structure, and the tip portion 16 of the fuel supply pipe 7 is the axial center portion of the fluidized bed in the primary combustion bed 20. It has been installed facing upward so that fuel can be supplied smoothly. Further, on the upstream side of the fuel supply pipe 7,
For example, installing a high-pressure pump (not shown)
Was able to be continuously and stably supplied. Here, the high water content residue 30 sent into the fluidized bed mixes with the fluidized heat medium 8. Then, it is dried and burned in a fluidized state by the action of the air supplied from the air chamber 2. here,
Reference numeral 32 denotes a cap provided on the top of each air introduction pipe 5.

The reason why sand is used as the fluidized heat medium 8 in the primary combustion chamber 3 is as follows.
Since sand has a certain large heat capacity, the temperature of the combustion bed 20 can be easily maintained even when the high water content residue 30 is put in the combustion bed 20, and its stirring effect in the fluidized state. This is because the residue 30 is evenly dispersed and the ash generated by burning is scraped off to improve the effect of contact with oxygen, which has the effect of improving combustion.

An appropriate number of temperature detectors 31 are provided in the primary combustion space 21 and the primary combustion bed 20 of the primary combustion chamber 3 to measure the detected temperature and supply auxiliary fuel to be supplied by the measured signal. Appropriate control is performed so that the temperature and the combustion state in the primary combustion chamber 3 can always be maintained in desired states.

Between the primary combustion chamber 3 and the secondary combustion chamber 4 immediately above the primary combustion chamber 3, a partition plate having a large number of vertically extending air introduction pipes 5a and a water cooling pipe 13a therein. 6a is provided. However, in the air introduction pipe 5a, not only the lower combustion gas rises and passes, but also a part of the residue being burned in the primary combustion chamber 3 is introduced into the secondary combustion chamber 4.

In the upper secondary combustion chamber 4, 33 is each air introduction pipe
5a is a cap provided on the upper part, 22 is a fluid heating medium 9 such as sand.
Is the secondary combustion space above.

The circulating water introduced via a circulating pump (not shown) is branched into two directions from the middle of the circulating water pipe, and one of the water channels is from the water cooling pipe 13 arranged on the partition plate 6 of the primary combustion chamber 3 to the primary The circulating water heated while passing through the water cooling pipe 13b arranged in the fluidized bed of the combustion chamber 3, and on the other hand, while passing through the water cooling chamber 13a arranged in the partition plate 6a of the secondary combustion chamber 4. Finally, the circulated water is sent to a waste heat boiler (not shown) provided on the downstream side of the secondary combustion chamber 4.

On the other hand, the combustion gas discharged from the fluidized bed top outlet 35 for effective utilization of the heat of the waste gas by the combustion of the residue 30 in the primary combustion chamber 3 and the secondary combustion chamber 4 is sent to the waste heat boiler, In the waste heat boiler, steam is generated by performing heat exchange between exhaust gas and circulating water, and the steam is, for example, 10 kg.
It is configured to be recovered as saturated steam at a low pressure of / cm ² .

 Next, the operation of the embodiment of the present invention will be described.

In the primary combustion chamber 3 and the secondary combustion chamber 4, fluidized heat mediums 8 and 9 such as general sand are put, respectively. Next, the lower auxiliary burner 10 is ignited, and the combustion and fluidizing air inlet
Air for combustion and air fluidization is supplied from 11, and the fluidized heat mediums 8 and 9 are respectively fluidized to form a primary combustion bed 20 and a secondary combustion bed 22.

Then, the high-pressure pump is driven into the primary combustion bed 20 to supply the high water content residue 30 through the fuel supply pipe 7 into the primary combustion bed 20 and burn it. Here, high water content residue 30
Means, for example, those containing more than 60% moisture,
For example, the usual water content in the residue 30 is about 60 to 70% for coffee meal, about 70 to 90% for tangerine meal, beer meal, and oolong tea meal, and about 70 to 80% for sludge.

The primary combustion bed 20 is dried by the action of the auxiliary burner 10 and the combustion heat of the residue 30 itself, and then burned. In order to simultaneously dry and burn the residue 30 in the primary combustion bed 20,
The temperature here is kept at about 800-900%.

In the apparatus of the present invention, in the primary combustion bed 20, the high water content residue 30 dries and then burns, for example, by about 60%, and also burns in the primary combustion space 21 by, for example, about 10%. The small residue 30 which is not completely burned in 3 and has, for example, about 30% of unburned matter is sent into the upper secondary combustion chamber 4. Then, the remaining combustion of the residue 30 is continuously performed in the secondary combustion bed 22 and the secondary combustion space 23 of the secondary combustion chamber 4, where it is completely burned. If the residue 30 is to be burned close to 100%, the discharge flow rate of the waste gas after the combustion is, for example, one-fourth of the case of the present invention.
, The area of the fluidized bed 2 needs to be increased accordingly, and the entire apparatus needs to be enlarged. In addition, it is necessary to find a special fluidized heat medium that fluidizes at a low flow rate.

When the high water content residue 30 is dried in the primary combustion chamber 3 and burned by only about 70% using the compact apparatus as in the present invention, a large amount of unburned matter is generated and the combustion efficiency is reduced. In the present invention, the remaining combustion is subsequently performed in the secondary combustion chamber 3 to complete combustion, so that the combustion efficiency is very good. In addition, since this device is completely burned in the secondary combustion chamber,
There is very little generation of ash, and the amount of residue 30 is close to the amount of ash contained as a component.

After the residue 30 is completely burned up to the secondary combustion chamber 4, the combustion exhaust gas is discharged from the fluidized bed top outlet 35 and reaches the waste heat boiler. On the other hand, the circulating water delivered by the circulation pump is the partition plate 6 of the primary combustion chamber 3 and the secondary combustion chamber 4.
And 6a are cooled and preheated by exchanging heat with combustion exhaust gas in water cooling tubes 13, 13a and 13b arranged in the primary combustion bed 20,
Finally, it is supplied to a waste heat boiler. In this way, in the waste heat boiler, heat exchange is performed between the combustion exhaust gas discharged from the fluidized bed top outlet 35 and the saturated water of steam fed through each water cooling pipe, and can be effectively recovered as low-pressure steam. .

In the above embodiment, the case where the combustion chamber having the combustion bed and the combustion space is provided in two stages of primary, secondary and secondary is described. A multi-stage combustion device provided with a fluidized bed for burning the residue 30 in three or more stages is provided.

Further, in the embodiment of the present invention, it was described that after the high water content residue 30 is dried, it is subjected to a combustion treatment, but the coal is crushed into an appropriate particle size range and sieved to form a certain state movement. It is also applicable to the case of burning in the state of being made to burn, and in this case, the auxiliary combustion burner 10 is used to raise the temperature of the combustion bed at the start up to the specified value, and the combustion bed starts feeding the fuel such as coal It will stop when the temperature is reached. After that, a stable combustion state can be maintained continuously due to the self-sustaining property of coal.

Similar to the high water content residue 30 described above, solid fuel such as coal is pulverized into an appropriate size in advance and used as a fuel through a fuel supply pipe 7 arranged in a partition plate 6 of the primary combustion chamber 1 When the air is supplied to the interior of the next combustion bed 20 by pneumatic transportation, the fuel supply pipe 7 and the water cooling pipe 13 are concentrically provided as shown in FIG. However, it can also be used as the fuel supply pipe 7 in combination with the wear-resistant cast steel protective cover 15 having a hole of an appropriate radius. Also, with respect to the protective cover 15 of the fuel supply pipe 7 shown in FIG. 2, it is easy to replace only the protective cover 15 when it is necessary to replace it due to deterioration that occurs when it is exposed to high temperature for a long time. Is possible.

Thus, in the embodiment of the present invention, solid fuel such as high water content residue 30 or coal is fed from the fuel supply pipe 7 arranged in the partition plate 6 of the primary combustion chamber 3 into the fluidized bed being fluidized. By directly supplying the fuel, the residence time of the fuel in the bed becomes longer, and the fuel is sufficiently dried and combusted correspondingly, and the combustion efficiency is improved. In addition, since the fuel supply section has a double tubular shape, the circulating water flows through the outer pipe and has a saturation temperature, so the enthalpy of the fuel flowing in the inner pipe in parallel flow increases with the circulating water. The combustion efficiency in the combustion bed is improved accordingly.

[Effects of the Invention] As described above in detail, in the present invention, the fuel supply pipe is provided in the partition plate of the primary combustion chamber, and the tip thereof is provided in the primary combustion bed. The solid fuel such as high water content residue or coal is dried and burned in the fluidized bed sufficiently by making full use of the characteristics of the fluidized bed, that is, the complete mixed bed and the uniform temperature of the fluidized bed.
The loss of unburned components discharged from the top of the fluidized bed along with the combustion gas was small and very economical operation was possible.

In addition, by making the fuel supply line a double tube,
The fuel flowing in the inner tube is heated by the circulating water flowing in the outer tube and having a saturated temperature, which increases the enthalpy of the fuel and improves the combustion efficiency in the combustion bed accordingly. To be done.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the overall structure of a fluidized bed boiler, and FIG. 2 is a double tubular fuel supply pipe arrangement in the case where the tip of the fuel supply pipe does not have a removable protective cover. FIG. 3 is an enlarged perspective view of a part of the gas distribution plate showing the situation, and FIG. 3 is a part of the gas distribution plate showing the disposition state of the fuel supply pipe in the form of a double pipe when a removable protective cover is provided at the tip of the fuel supply pipe. FIG. 4 is an enlarged perspective view and FIG. 4 is a partially detailed vertical cross-sectional view of a double-piped fuel supply pipe showing IV-IV cutting in FIG. 2 when a wear-resistant cast steel protective cover is not attached to the tip of the fuel supply pipe. The figure shows the third case where a wear-resistant cast steel protective cover is attached to the tip of the fuel supply pipe.
Fig. 5 is a partially detailed vertical cross-sectional view of a double-piped fuel supply pipe, showing the cross section of Figs. 1 ... Fluidized bed boiler, 2 ... Air chamber, 3 ... Primary combustion chamber, 4 ... Secondary combustion chamber, 5,5a ... Air introduction pipe, 6,6a
...... Partition plate, 7 …… Fuel supply pipe, 8, 9 …… Fluid heat medium, 1
0 …… Burner for auxiliary combustion, 11 …… Air inlet for combustion and fluidization, 13, 13a, 13b …… Water cooling pipe, 15 …… Protective cover, 30 ……
High water content residue.

Claims (1)

(57) [Claims] 1. An air chamber provided with a primary combustion chamber having a primary combustion bed having a fluidized heat medium and a primary combustion space, and an auxiliary combustion burner and an air inlet for combustion provided in a lower stage of the primary combustion chamber. And at least one other combustion chamber including a combustion space and another combustion bed having a fluidized heat medium in the upper stage of the primary combustion chamber, and between the primary combustion bed and the air chamber, and In a multi-stage fluidized bed boiler, in which partition plates and water cooling pipes are alternately arranged in the horizontal direction perpendicular to the longitudinal direction of the water cooling pipes between the upper combustion chamber and the lower combustion space, and then connected to each other, A water cooling pipe and a fuel supply pipe, which is an inner pipe for supplying fuel, are provided in a double pipe shape, the double pipe is provided in a partition plate between the primary combustion chamber and the air chamber, and the bottom portion of the primary combustion chamber is provided. The fuel is supplied from the middle of the pipe by arranging it toward the approximate center of the plane. The fuel supply apparatus for a fluidized bed boiler, characterized in that the tip is disposed toward the primary combustion chamber.