JPS60218507A - Fluidized bed furnace - Google Patents

Abstract

1. A fluidised bed furnace comprising a combustion chamber having walls and a floor made up of wall tube which are welded to one another in gas-tight manner and convey a heat transfer medium, and the floor has air openings, means for supplying fuel, additives and air being provided and a post-combustion chamber being formed in the combustion chamber above the fluidised bed, characterised in that at least one static mixer (30) is disposed in the post-combustion chamber (19) and comprises vertical panels (31, 32; 37, 38) distributed over the entire cross-section of the post-combustion chamber (19) and leaving intersecting ducts between them, the flue gas flow rising from the fluidised bed (18) being divided into a number of repeatedly intersecting sub-flows in the ducts.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention has a combustion chamber in which the walls and base of the combustion chamber are made of wall tubes that are airtight and welded together to carry a heat exchange medium, and the base The present invention relates to a fluidized bed furnace having an after-combustion chamber formed within the combustion chamber above the fluidized bed, having air passage holes and devices provided for supplying fuel, additives and air.

Depending on the type of fuel used in the fluidized bed and the amount of air injected, fine unburned fuel particles may be discharged from the fluidized bed during operation of the furnace with consequent losses reducing efficiency. .

In one conventional fluidized bed furnace, these unburned fuel particles were separated from the smoke gas in a filter located in a cyclone and/or in a cold zone of the smoke gas and recycled into the fluidized bed. However, the equipment required for this purpose is expensive and it is completely impossible to stop the discharge. Fuel particles with a diameter of up to about 0.5 mm are most frequently recycled, and these particles become highly abrasive, especially in the recirculator and at heat exchange surfaces, resulting in erosion.

Other fluidized bed furnaces require recirculation of unburned fuel particles as they are discharged from the fluidized bed and are combusted by at least one afterburner for liquid and/or gaseous ignitable fuels. He is known for not doing so. However, this solution requires a relatively expensive afterburner and requires the use of a corresponding amount of additional fuel.

C.1 The problem that the invention seeks to solve: Therefore, to the extent that recirculating fuel particles are no longer necessary and the efficiency of the fluidized bed reactor is increased, it is possible to easily and cheaply produce smoke without any additional energy supply. It is an object of the invention to reduce the content of unburned fuel particles in the gas.

21 Means for Solving Problems According to the invention, for this purpose at least one static mixer is provided in the after-combustion chamber. Static mixer devices are known for dividing the gas flow into sub-streams which repeatedly intersect with each other and are thus intimately mixed. These mixer devices have low pressure losses to ensure good homogeneity of the gas flow through these devices. It is known that these properties are maintained even if the soot stream contains solid particles without interfering with the mixer device during operation. The mixer device is made of ceramic materials and/or heat-resistant steel and is made of approximately 900
It can be designed without difficulty for temperatures up to ℃. The mixing and homogeneity of the smoke gases produced by the mixer device ensures that the smoke does not have any appreciable disturbance to the smoke stream, eliminates the cold zone and distributes the oxygen evenly, leaving no residue in the after-combustion chamber. Promotes combustion of combustion fuel particles. There is therefore no need for an additional combustible fuel supply. A static mixer device has no moving parts and is therefore virtually hassle-free.

It is also known that the provision of static mixer devices in post-combustion chambers with large cross-sections in which the smoke gases move relatively slowly and the density of unburned fuel particles is very low can result in minor corrosion.

This occurs even if the after-combustion chamber is somewhat restricted relative to the fluidized bed. If the static mixer device wears out due to corrosion and/or erosion, it can be easily and quickly replaced.

Another advantage of the invention is the simple construction of the fluidized bed reactor. The design of the static mixer element according to claim 2 gives a very good efficiency, which efficiency is further improved by the device according to claim 6.

Claim 4 relates to a preferred embodiment of the invention.

Significant improvements to the combustion in the area of static mixer devices are achieved by the device according to claims 5 to 9,
It is up to each individual case to decide which stage is most appropriate.

The invention will be described with reference to an embodiment and its drawings.

E. Examples and operations The fluidized bed furnace 1 shown in FIG. 1 has a combustion chamber 2 with a rectangular cross section. The combustion chamber 2 is surrounded by four vertical walls 3', 3' and is bounded at the bottom by a base 4. Combustion chamber wall 3′, 3″
The combustion chamber base 4 has a wall tube 5 and a wall 3' which are welded together to make the combustion chamber airtight.

It consists of a tube extending vertically in the area of 3' and horizontally in the area of the base 4. The wall tubes 5 of the two opposing walls 3' are
Each cooling water supply pipe 12 extends from a horizontal cooling water distributor 13 to the bottom. At the top, the tubes 5 of the two walls 3' each lead into a horizontal ladder 14 to which a discharge tube 15 is connected.

The other two combustion chamber walls 3# are bent at 90° to each other at their bottom ends and are interconnected in a hermetically sealed manner so that each tube 5 of one wall 3' is connected to the other wall 3''. The top end of the tube 5 in one combustion chamber wall 3'' is connected to a horizontal cooling water distributor 13'.
and the horizontal header 14 alternately. The same thing is done at the top end of the tube 5 in the other combustion chamber wall 3'', so that
Adjacent tubes of the two walls 3' have cooling water flowing through them in opposite directions, which leads to the associated distributor via the supply tube 12'. The combustion chamber 2 is bounded by a pyramidal combustion chamber roof 11 from the top central end which branches off the discharge duct 10 at the top end. Combustion chamber walls 3', 3'', combustion chamber base 4
The combustion chamber roof 11 is welded together with the button so as to be airtight.

An air reservoir 90 is arranged between the combustion chamber base 4 and the inverted pyramid-shaped hopper 9, and a primary air supply pipe 8 with a valve 8' is arranged to regulate the air flow connected to the reservoir 90. . An empty pipe 1 having a valve 17 at the tip of the eave of the hopper 9
6 are connected. The reservoir 90 is connected to the combustion chamber 2 through a passage hole 91 in the interior of the combustion bed 4. A cover plate 92 provided over each passage hole 91 is welded to two adjacent tube 5% and spans the hole 91.

The combustion chamber 2 is divided into two sections, namely a bottom section occupied by a fluidized bed 18 and an upper section forming an after-combustion chamber 19 .

Two inclined discharge pipes 7 extend through each of the two combustion chamber walls 3' in the after-combustion chamber and terminate just above the fluidized bed 18.

Flag-shaped heating surface tubes 25 are arranged in the area of the fluidized bed 18 and extend through the two combustion chamber walls 3' and radiate from the rudder 27 to the horizontal heating surface distributor 26 and the horizontal heating surface above it. The heating surface pipe 25 extends parallel to the combustion chamber wall 3''. The heating surface distributor 26 and the header 27 are located outside the combustion chamber 2 and are connected to the water supply pipe 28 and the discharge pipe 29. A secondary air supply pipe 20 is located at the same level, and somewhat below it, a plurality of slanted secondary air supply pipes 21 extend into the after-combustion chamber 19. The pipes 20 and 21 Connected to horizontal secondary air distributors 22 extending through the chamber wall 3' and extending parallel to the combustion chamber wall 3', a secondary air injection pipe 23 is led to each distributor 22. All pipes 7.20 .2
1 and 25 extend through the associated combustion chamber wall 3' or 3' in the area of the welded web 6 in a gas-tight manner.

Six static mixer devices 30 are arranged in the horizontal secondary air supply pipe 20 and extend over the entire cross section of the after-combustion chamber 19 up to the combustion chamber walls 3', 3'. The mixer device is fixed by its own weight. An example of the structure of each mixer device 3o is shown in FIG. The stationary mixer device consists of a plurality of vertical surface elements 31 which extend at angles parallel to each other and have guide elements 32 welded at right angles to the surface elements 31. The surface elements are arranged one after the other in such a way that the guide elements 32 intersect each other. The flow of smoke gases rising from the fluidized bed 18 is divided in the mixer device into a number of sub-streams that intersect each other at angles of approximately 90°. Since the three mixer devices are stacked on top of each other as shown in FIG. 1, the vertical surface elements 31 of one mixer device have a non-zero angle with the vertical surface elements of the adjacent mixer device. In Figure 1' this angle is 45°. This ensures effective mixing of smoke in all directions.

The fluidized bed furnace shown in FIG. 1 operates as follows.

A fan (not shown) passes through the secondary air supply pipe 8 to a reservoir 90.
Air is blown into the chamber, and the amount of air is determined by the position of the valve 8'. Valve 1T is closed hermetically so that a pressure in excess of atmospheric pressure is created in the reservoir. Air flows into the combustion chamber 2 through the passage holes 91 and the cover plate 92 provides good primary air distribution within the fluidized bed 18. The fluidized bed consists of granular coal and granular additives introduced via discharge pipe 7. - Under the action of next air, the coal and additives rotate in the combustion chamber 2 and, given the correct selection of air pressure and air flow, a fluidized bed is formed in a known manner and actually acts as a fluid. The fluidized bed 18 is then ignited, the coal burns, and the additives solidify sulfur compounds and other combustion products that pollute the environment.

The resulting smoke gas escapes upwards. As a result of the slight positive pressure of the fluidized bed 18 with respect to the after-combustion chamber 19, partially unburned coal particles with a maximum diameter of 0.5 mm are entrained in the smoke gases. After these moving coal particles, the combustion is started in the actual post-combustion chamber 19 of the next static mixer device 30, the coal particles and the air contained in the smoke gas are evenly distributed and well mixed with each other, Homogeneity of smoke gas temperature eliminates excessively cold zones where combustion of coal particles does not occur. The complete combustion of the ignited coal particles occurs after the injection pipe 23, the distributor 22, the inclined secondary air supply pipe 21 and the static mixer 30 - the air source via the horizontal secondary air supply pipe 20 in the combustion chamber 19. This is accomplished by secondary air for combustion introduced from (not shown). The static mixer device 30 thus actually produces a complete combustion of the unburned coal particles contained in the smoke gas, which is a practical solution without any need for additional equipment and/or additional energy consumption. This occurs inside the combustion chamber 2. After extending over the static mixer device 30 -
That part of the combustion chamber 19 ensures a suitable time interval during which the coal particles ignited in the static mixer device 30 are completely combusted before reaching the outlet of the combustion chamber 2.

The smoke gases, which do not contain incompletely burned coal particles, flow from the combustion chamber roof 11 into the discharge duct 10.

The heat generated in the fluidized bed as a result of the combustion is subsequently discharged in a known manner by water flowing into the wall tubes 5 and the heated surface tubes 25;
Water evaporates as much as possible. Since the water or steam flows in opposite directions in the adjacent wall tubes 5 forming the combustion chamber 2, a uniform temperature distribution is ensured and thermal stresses are avoided. In the other wall pipes 5 the normal flow direction is i.e. the cooling water supply pipe 12
It is always upward from the header and discharge pipe 15 via the cooling water distributor 13. Also, the water or steam is passed from the cooling water supply pipe 28 through the heating surface distributor 26 to the heating surface pipe 2
5 through the heating surface header 27 to the discharge tube 29 substantially upwardly in the heating surface tube 25 .

When the air supply is turned off, cover plate 92 prevents fluidized bed material from flowing into air reservoir 9o. Accessing the air reservoir 9o for cleaning and emptying it of any residue takes place via the space 16 with the valve 17 open.

The secondary air supply pipes 2o and 21 can be drilled inside the combustion chamber 2, which can improve the secondary air distribution in certain situations. The fluidized bed 18 can also be divided into different parts by partitions in a known manner to improve operation at partial loads. In this case, it is advantageous to inject secondary air into the parts of the fluidized bed corresponding to the respective working parts by means of valves placed outside the combustion chamber 2, without having to take into account static mixer devices, and this This is another effect of the present invention.

Instead of the mixer arrangement shown in FIG. 2, a mixer arrangement of the type shown in FIG. 3 is used in the combustion chamber 2. From FIG. 6, vertical panels 3T and 38 formed from inclined mixer tubes 35 are provided in the mixer apparatus, with the tubes rising from right to left in panel 37 and from left to right in panel 38. Panels 37 and 38 are parallel to each other and arranged alternately. A groove 36 in tube 35' connects the space between panels 37 and 38 to the interior of mixer tube 35. Most of the mixer tubes 35 in the panel are led to a distributor 39 at the bottom end.

The distributor is arranged in an extension of the horizontal secondary air supply pipe 2o shown in FIG. In this variant, the secondary air is injected directly into the static mixer arrangement and mixed with the smoke gas, and the secondary air introduction via the inclined secondary air supply pipe 21 shown in FIG. 1 can be dispensed with in this case. can. When a plurality of mixer apparatuses configured in this manner are stacked on top of each other, the spring in one apparatus is connected to the panel 37 of the preceding apparatus.
．． 38 has an angle greater than or equal to 90°, which is preferred, which provides optimal mixing of secondary air and smoke gases in all directions. In the case of bottom mixer arrangements, it is usually sufficient for the secondary air to be introduced only via the distributor 39, and since the distributor 39 is omitted in the mixer arrangement above, these mixer arrangements It is formed by a panel consisting only of mixer tubes 35 that are open at both ends and lead into the combustion chamber 2.

The fluidized bed furnace described is of the static type, ie without any recirculation of the bed material inside the bed.

It can have shapes other than those shown, such as static mixer devices. For example, atmospheric pressure and pressurized fluidized bed furnaces are possible. It is also possible to use a combustion chamber with a cross section of varying height. The combustion chamber base can be constructed independently of the combustion chamber wall, or the combustion chamber wall can be perforated in a spiral instead of vertically. The combustion chamber base can be displaced vertically or can also have a closable hole through which the layer material is discharged via the hopper 9 and the empty tube 16.

The layer material is in the form of a fine powder, and the fuel is liquid instead of granular, and can also be injected into the upper fluidized bed, for example, by air acting at the same time as secondary air.

The static mixer device can extend to the top end of the combustion chamber. The device can also be suspended from the combustion chamber roof by cooled tubes or uncooled rods.

An additional heating surface is also provided on the static mixer device.

A plurality of static mixer devices can be arranged adjacent to each other in the after-combustion chamber with or without spacing. The static mixer device can be connected to the combustion chamber wall instead of actively by means of the secondary air supply pipe and/or its own weight.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the fluidized bed furnace of the present invention, FIG. 2 is a perspective detail view of a static mixer device, and FIG. 3 is a perspective detail view of another static mixer device. 1: fluidized bed furnace, 2: combustion chamber, 3', 3': combustion chamber wall, 4: base 5: wall tube, T: inclined discharge tube, 18: fluidized bed, 19: after-combustion chamber, 20. 21: Secondary air supply pipe, 30: Stationary mixer device, 91: Passage hole. Agent Akira Asamura

Claims (1)

[Scope of Claims] (i) A combustion chamber in which the walls and base of the combustion chamber are airtight and are welded together to carry a heat exchange medium, the base having air passage holes and a fuel In a fluidized bed furnace with a combustion chamber formed in the combustion chamber above the fluidized bed, with a device provided for supplying additives and air, at least one static mixer is formed in the combustion chamber above the fluidized bed. A fluidized bed furnace characterized by having the furnace in a combustion chamber. (2. In the fluidized bed furnace according to claim 1,
A fluidized bed furnace, characterized in that the static mixer device covers the entire cross section of the after-combustion chamber. (3) In the fluidized bed furnace according to claim 1 or 2, the height of the fluidized bed is at least half a meter, and the distance between the surface of the bed in a fluidized state and the mixer is at most three times the height. A fluidized bed furnace, characterized in that it has a fluidized bed furnace between the furnace and the apparatus. (4) A fluidized bed furnace according to any one of claims 1 to 6, wherein the fluidized bed is a stationary plate bed. (5) A fluidized bed furnace according to any one of claims 1 to 4, characterized in that the combustion chamber has a supply of secondary air for combustion. . (6) A fluidized bed furnace according to claim 5, characterized in that the secondary air supply is provided in the area of the fluidized bed. (7) In the fluidized bed furnace according to claim 5,
A fluidized bed furnace characterized in that the secondary air supply is provided between the fluidized bed and the static mixer device. (8) In the fluidized bed furnace according to claim 7,
At least a portion of the secondary air supply is directed to the fluidized bed,
A fluidized bed furnace characterized in that it is oriented at an angle of 5°. (9) A fluidized bed furnace according to claim 5, characterized in that the static mixer device is constructed as a secondary air supply. αQ A fluidized bed furnace according to any one of claims 7 to 9, characterized in that the static mixer device is guided by at least one pipe of the secondary air supply. Furnace.