JPH0141083Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is installed in the low-temperature gas area after being cooled by a gas cooling device in the flow path for discharging combustion gas generated in a waste incinerator, and is designed to exchange heat with the combustion gas. Therefore, the present invention relates to a hot water generator for a garbage incinerator that recovers hot water.

In order to recover heat from the combustion gas generated in the incinerator and use it for hot water supply and space heating, garbage incineration equipment is equipped with a hot water generator that generates hot water by bringing it into contact with the combustion gas and exchanging heat. It is known that this hot water generator is installed in a high temperature gas region near the outlet of an incinerator, and in a low temperature gas region after a gas cooling device. When garbage is completely combusted, the combustion gas generated in the incinerator is at a high temperature of over 800℃ near the exit of the furnace, and recovering hot water by directly exchanging heat with this high temperature gas is High-temperature corrosion may occur in the heat exchanger components, or premature deterioration of these components due to differences in thermal expansion of the components of the hot water generator.
In addition to causing damage, there are disadvantages such as a reduction in heat exchange efficiency due to so-called dust troubles caused by soot contained in the combustion gas. On the other hand, even when installed in a low-temperature gas region, the combustion gas is cooled and condensed on the surface of the heat exchange member in contact with the combustion gas, and this condensed water reacts with sulfides, chlorides, etc. contained in the gas. This has the disadvantage that sulfuric acid and hydrochloric acid are produced, and these effects cause low-temperature corrosion, accelerating deterioration and damage to heat exchange members.

The present invention was made in order to improve the drawbacks of the prior art described above, and aims to provide a hot water generator that is installed in the low-temperature gas area of a waste incinerator, has good low-temperature corrosion resistance, and has a long life. This is the purpose.

In order to achieve the above-mentioned object, the hot water generator for a waste incinerator according to the present invention includes a hot water generator for a waste incinerator in a low-temperature gas region of the flow path for discharging the combustion gas generated in the waste incinerator.
The outer tube of a double-pipe heat transfer tube consisting of an inner tube and an outer tube is made of impermeable graphite, and the outer tube is placed in contact with combustion gas, and one side of the inner tube and outer tube is A cold water supply inlet and a hot water outlet are respectively formed on the fixed side of the inner tube, and a communication path is provided on the other side of the inner tube to flow water from the inner tube side to the outer tube side. Its feature is that it has a configuration that forms.

Hereinafter, an embodiment of the present invention will be described based on the drawings. First, in FIG. 1, reference numeral 1 indicates an incinerator equipped with a hopper 1a for charging garbage, and the incinerator 1 has a stoker for combustion inside. This makes it possible to completely burn the garbage thrown in from the hopper 1a. Combustion gas generated in this incinerator 1 is introduced into a gas processing section 2, and while being induced by an induced fan 3 installed on the downstream side, the gas processing section 2 performs cooling, removal of harmful gases, dust removal, etc. After being treated, it is released into the atmosphere from a chimney 4. For this purpose, the gas processing unit 2 includes a gas cooling device 5 that cools the high-temperature combustion gas generated in the incinerator 1 using cooling water, and an air preheater that preheats the combustion air supplied to the incinerator 1. 6 and
A harmful gas removal device 7 that removes harmful gases contained in combustion gas by filling with slaked lime or the like, and an electrostatic precipitator 8 that separates soot, smoke, etc. in the combustion gas;
It is composed of a hot water generator 9.

As mentioned above, the hot water generator 9 is installed in the low-temperature gas area downstream of the gas cooling device 5, and moreover downstream of the electrostatic precipitator 8, so that the hot water generator 9 is installed at a low temperature of about 250°C to 350°C to prevent dust troubles. Hot water is generated by exchanging heat with combustion gas, which is free from the risk of generating hot water, and can be used for hot water supply, space heating, etc. Its specific configuration is shown in Figures 2 and 3. It's getting old. The drawing shows the installation of two hot water generators of the same construction, one hot water generator being used for hot water supply and the other hot water generator for space heating.

In the flue 10 through which combustion gas flows, a plurality of heat transfer tubes 11 for exchanging heat with the combustion gas are installed to pass through the flue 10, and each heat transfer tube 11 is a double tube. The inner tube 11a is inserted into the outer tube 11b and kept in a non-contact state with the combustion gas, and only the outer tube 11b is configured to come into contact with the combustion gas. The inner tube 11a and the outer tube 11b of each heat transfer tube 11 are suspended with their upper ends fixed to support plates 13 and 14 attached to flanges 12a and 12b formed on the upper casing 12 of the hot water generator 9, respectively. lowered, inner tube 1
The lower end of the outer tube 1a is a free end, and the lower end of the outer tube 11b is fixed to the steady rest plate 15, so that it can expand and contract in the axial direction but can prevent swinging.

Next, the inside of the upper casing 12 is divided into two parts, a cold water chamber 16 and a hot water chamber 17, by the support plates 13 and 14.
The cold water chamber 16 has a water supply pipe 1.
8 is connected, and a cold water intake port 19 formed at the upper end of the inner pipe 11a is open. On the other hand, a hot water supply pipe 20 is connected to the hot water chamber 17, and a hot water outlet 21 formed at the upper end of the outer pipe 11b is open. Further, the lower ends of the inner tube 11a and the outer tube 11b are covered with lids 22 and 23, and a buffer band 24 made of an elastic material such as rubber is fitted near the lower end of the inner tube 11a. At the same time, a plurality of communication passages 25 are formed in the upper part of the inner pipe 11a and the outer pipe 11b to communicate between the inner pipe 11a and the outer pipe 11b. 25 and the inner tube 11a and the outer tube 11
A flow path is formed that allows hot water to flow from the hot water outlet 21 into the hot water chamber 17 via the annular path between the hot water outlet 21 and the hot water chamber 17.

Furthermore, an outer tube 11b is provided on the upper surface of the steady rest plate 15.
A conical recess 26 is formed to guide condensed water adhering to the outer surface of the recess 26, and a through hole 27 is formed in the center of the recess 26 to allow the condensed water in the recess 26 to flow out. A drain pipe 29 is connected to the lower casing 28 of the hot water generator 9 to discharge condensed water flowing down through the through hole 27 to the outside.

Here, the inner tube 11a of the heat transfer tube 11 is kept in a non-contact state with the combustion gas and there is no risk of low-temperature corrosion, so it is formed of a metal material such as steel or aluminum material with good thermal conductivity. Since the outer tube 11b is in direct contact with combustion gas and there is a risk of condensation water adhering to its outer surface, it needs to be made of a material with good low temperature corrosion resistance and good thermal conductivity. . For this reason, in the present invention, impermeable graphite is used as the material for the outer tube 11b. This impermeable graphite is suitably used, for example, by baking a mixture of coke and pitch to graphitize it, impregnating it with a heat-resistant synthetic resin, and then thermosetting it. Further, since the support plate 14 and the steady rest plate 15 are also exposed to combustion gas and there is a risk of condensation water adhering to them, they are made of the same impermeable graphite as the outer tube 11b.

The combustion gas generated by incinerating garbage in the incinerator 1 is heated to a temperature of 250°C to The cooled water is cooled to about 350 degrees Celsius and is guided into the flue 10 in a clean state free of harmful gases, soot, etc., and then heated to the hot water generator 9.
It comes into contact with the heat exchanger tube 11 of. Therefore, when water is supplied from the water supply pipe 18 to the cold water chamber 16,
This water flows down inside the inner pipe 11a from the cold water intake port 19, and passes through the communication path 25 between the inner pipe 11a and the outer pipe 11b.
and rises toward the hot water outlet 21. While flowing through this annular passage, the water exchanges heat with the combustion gas through the outer pipe 11b and is heated to become hot water, and this hot water is passed from the hot water outlet 21 through the hot water chamber 17 to the hot water pipe. It flows towards 20. In this case, since the outer tube 11b is made of a material with good thermal conductivity, the heat transfer efficiency between the gas and water via the outer tube 11b is good.

Here, since the water flowing through the heat transfer tube 11 is always in a lower temperature state than the combustion gas, the combustion gas is cooled around the outer tube 11b due to this temperature difference, and the water therein is transferred to the outside of the outer tube 11b. Condensation will form on the surface. Furthermore, the combustion gas contains a large amount of sulfides, chlorides, etc., and these react with dew condensation to produce sulfuric acid, hydrochloric acid, etc. in considerably high concentrations. However, since the outer tube 11b is made of graphite, it does not suffer from problems such as corrosion or deterioration unlike metals. Also,
In addition to the outer tube 11b, the support plate 14 and the steady rest plate 15, to which there is a risk of condensation water adhering, are also made of the same members as described above, so there is no risk of low-temperature corrosion occurring therein.

As mentioned above, since the outer tube 11b is made of graphite, there is a risk that it will melt at a temperature of about 200°C, but since water flows inside the outer tube 11b, this water will cause the outer tube to melt. The tube wall of the tube 11b is constantly cooled and is never heated to the extent that it melts even in the combustion gas at 250° C. to 350° C.

Furthermore, graphite is more fragile than metals, and when impact force, bending force, strain force, etc. are applied to it, it easily cracks or breaks. but,
Since the upper end of the outer tube 11b is fixed to the support plate 14 and the lower end is fixed to the steady plate 15, the flue 1
There is no risk of the outer tubes 11b swinging unnecessarily due to the influence of the flow of combustion gas in the inner tube, and collisions do not occur between the outer tubes 11b or between the outer tubes 11b and other members. Moreover, since the buffer band 24 is fitted to the lower end of the inner tube 11a, the inner tube 11a
Even if the outer tube 1a swings and collides with the outer tube 11b, the outer tube 11
No impact would occur to the extent that it would damage b.

Furthermore, when operating the garbage incinerator, the outer pipe 11b
thermally expands, but since the steady rest plate 15 fixed to the lower end of the outer tube 11b is not fixedly supported, it is possible to allow the outer tube 11b to expand and contract, and due to the influence of this thermal expansion, the outer tube 11b No bending or straining forces are applied to the Moreover, the inner tube 1 of the heat exchanger tube 11
The water in the passage between 1a and the outer tube 11b will be heated as it rises, so a temperature difference will occur between the upper and lower parts, and if this temperature difference is significant, the water in the outer tube 11b will be heated. Although this may cause cracks, etc., the water flowing down inside the inner pipe 11a exchanges heat with the water on the outer pipe 11b side, which is already in a heated state, through the inner pipe 11a, so it passes through the communication path 25. At this point, the outer tube 11b is preheated to some extent, and the temperature difference between the upper and lower parts of the outer tube 11b is minimal.
That damage is prevented. Furthermore, supplying water in a preheated state to the outer tube 11b reduces the temperature difference between the combustion gas and the outer tube 11b, which is advantageous in reducing condensed water in the outer tube 11b. .

In addition, although the above-mentioned Example showed the thing which arrange|positions two hot water generators 9, it is not limited to that number. Further, the heat exchanger tubes 11 may be provided not only in the vertical direction but also in the horizontal direction. Furthermore, although it has been explained that the hot water generator 9 is installed downstream of the electrostatic precipitator 8, this is to prevent dust troubles from occurring due to the influence of soot and smoke in the combustion gas, and there is a risk that such problems may occur. If there is no such device, it may be installed anywhere in the low-temperature gas region downstream of the gas cooling device 5. Furthermore, the flue 10 in which the hot water generator 9 is installed may form a main flow path for combustion gas, or may be a flow path bypassing the main flow path. If the flue 10 is formed as a bypass flow path and a damper is attached to the inlet and outlet of the flue 10 to control the amount of inflow and outflow of combustion gas, the temperature of the generated hot water can be controlled.

As detailed above, in the hot water generator for waste incineration equipment according to the present invention, since the outer tube of the heat exchanger tube that comes into direct contact with combustion gas is made of impermeable graphite, there is no risk of low-temperature corrosion. is fixedly supported on one side, and a cold water inlet and a hot water outlet are respectively provided in the inner pipe and the outer pipe on this fixed side,
In addition, since a communication path is formed on the other side of the inner tube between it and the outer tube, no bending or straining force due to heat is applied to the outer tube made of graphite, and cracks and damage can be prevented. It will be done.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the waste incinerator, FIG. 2 is a sectional view of a hot water generator, and FIG. 3 is an enlarged view of the main parts of FIG. 2. 1: Incinerator, 2: Gas processing section, 9: Hot water generator, 10: Flue, 11: Heat exchanger tube, 11a: Inner tube,
11b: outer pipe, 13, 14: support plate, 15: steady rest plate, 16: cold water chamber, 17: hot water chamber, 19: cold water intake, 21: hot water outlet, 25: communication path.

Claims (1)

[Scope of utility model registration request] The outer tube of a double tube type heat transfer tube consisting of an inner tube and an outer tube is formed of impermeable graphite in the low temperature gas area of the flow path for discharging combustion gas generated in a garbage incinerator. is placed in contact with combustion gas, one side of the inner tube and the outer tube is fixedly supported, and a cold water supply port and a hot water outlet are respectively formed on the fixed side, and the other side of the inner tube is fixedly supported. A hot water generator for a waste incinerator, characterized in that a communication path is formed for flowing water from the inner tube toward the outer tube.