JPH061155B2 - Cross-flow heat exchanger - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gas-gas used as an air preheater for preheating combustion air supplied to a combustion chamber such as a boiler with high-temperature exhaust gas. The present invention relates to a cross-flow heat exchanger for a vehicle.

(Prior Art and Problems Thereof) This type of gas-gas cross-flow heat exchanger is a partition plate in which a high temperature exhaust gas passage and a combustion air passage are juxtaposed at appropriate intervals. Are formed so as to be adjacent to each other through and through so that the flow passage directions are orthogonal to each other, but like the tube heat exchanger used as a similar air preheater, Dust contained in the exhaust gas adheres to the side surface. If this attached dust is not removed regularly, the heat exchange efficiency will drop significantly, but in the past, the boiler must be periodically stopped to remove this attached dust, and the heat exchanger must be disassembled. did not become. Therefore, not only the operating efficiency of the boiler is lowered, but also a considerable labor cost is required.

(Means for Solving Problems) The present invention is directed to preheating combustion air supplied to a combustion chamber such as a boiler with high-temperature exhaust gas discharged from the combustion chamber. The present invention relates to an AC heat exchanger.

(Prior Art and Problems Thereof) In this type of cross-flow heat exchanger, a high temperature exhaust gas flow path and a combustion air flow path are mutually provided through partition plates arranged at appropriate intervals. It is formed so as to be adjacent to each other and the flow channel directions are orthogonal to each other, but like the tube type heat exchanger used as a similar air preheater, the inner surface of the high temperature exhaust gas flow channel, that is, the above-mentioned Dust contained in the exhaust gas adheres to the surface of the partition plate facing the high temperature exhaust gas flow path. If this adhered dust is not removed regularly, the heat exchange efficiency will drop significantly, but for the conventional work to remove this adhered dust, the boiler operation must be suspended temporarily and the heat exchanger must be disassembled. did not become. Therefore, not only the operating efficiency of the boiler is lowered, but also a considerable labor cost is required.

In a heat exchanger in which a high-temperature fluid passage and a low-temperature fluid passage are separated by a heat transfer plate (partition plate), the fluid introduced into one of the fluid passages is directly transferred in order to improve the heat exchange efficiency. Japanese Patent Publication No. 56-41917 proposes a method of ejecting a fluid onto the surface of the heat transfer plate by injecting the heat transfer plate from a small hole of an injection plate that partitions the fluid flow path without contacting the surface of the heat plate. Is disclosed by.

By using such a heat exchanger in a state in which high temperature exhaust gas is introduced into the fluid flow path containing the injection plate, the surface of the heat transfer plate (partition plate) facing the high temperature exhaust gas flow path The effect of preventing the dust contained in the high-temperature exhaust gas from adhering is expected. However, since the high-temperature exhaust gas containing dust itself is injected from the small holes, it is clear that the small holes are actually clogged and cannot be used practically.

Moreover, since the high-temperature exhaust gas discharged from the boiler is usually not at high pressure, it is possible to improve the heat exchange efficiency by injecting the high-temperature exhaust gas onto the heat transfer plate surface, but the heat transfer plate surface The necessary and sufficient automatic cleaning action can not be expected.

Not only that, since the hot exhaust gas flow path is divided by the injection plate, it is quite possible that the division space on the fluid introduction side of the injection plate becomes a dust separation chamber and dust accumulates inside. However, in order to clean it, it is necessary to stop the operation of the boiler and disassemble and clean the heat exchanger, and it is impossible to achieve the intended purpose. Of course, since the high temperature exhaust gas itself is used to clean the surface of the heat transfer plate, it is not possible to carry out the cleaning work by utilizing the downtime during which the boiler is not in operation.

(Means for Solving Problems) The present invention proposes a cross-flow heat exchanger capable of solving the above-mentioned conventional problems, which is characterized by a high-temperature exhaust gas passage. At least one of the pair of partition plates to be formed is equipped with a nozzle that discharges pressure air toward the surface of the other partition plate facing the high temperature exhaust gas flow path in an appropriate arrangement, and the partition plate to which the nozzle is attached is attached. A pressure air supply pipe connected to each of the nozzles is disposed in the adjacent combustion air flow passage, and pressure air can be introduced into the pressure air supply pipe from the outside of the combustion air flow passage. In point.

(Example) First, an example of the internal structure of the cross-flow heat exchanger used in the present invention will be described with reference to FIGS. 1 to 7.

In FIGS. 1 and 2, 1 is a rectangular plate in which four corners 2 are each cut out in an arc shape, and a pair of parallel two side edges 3a, 3b are oblique to one side. It has side edges 4a and 4b which are bent in parallel with each other and extend parallel to the plate surface, and the remaining pair of two parallel side edges 5a and 5b are bent obliquely to the other side and are parallel to the plate surface. It has side edge portions 6a, 6b extending to.
In addition, a bent plate portion 7 that is bent to one side is formed on a side edge of each of the arc-shaped corner portions 2. Furthermore, each corner 2
In the square flat plate portion surrounded by, each side 3a, 3
A protruding portion 8 protruding to one side and a protruding portion 9 protruding to the other side are formed at the same height as the bending height of b, 5a, 5b, respectively, at vertically and horizontally symmetrical positions.

When a plurality of rectangular plates 1 as described above are formed by press working, the side edges 4a and 4b are folded back from the rectangular plates 1 to one side in a U-shaped cross section as shown in FIG. A square partition plate 12 which is a mating side edge portion 10 and which is formed by cutting the side edge portions 6a and 6b into a width capable of being fitted to the engagement side edge portion 10 to form an engaged side edge portion 11, As shown in FIG. 4, the side edge portions 6a, 6b are folded back to the other side in a U-shaped cross section to form an engaging side edge portion 13, and the side edge portions 4a, 4b
4b is a square partition plate 15 which is cut into a width that can be fitted to the engaging side edge portion 13 and is used as the engaged side edge portion 14, and a plurality of them are manufactured.

Next, as shown in FIG. 5, both engaged side edge portions 14 of the partition plate 15 turned upside down on both engaging side edge portions 10 of the partition plate 12 are slidably fitted in the side edge length direction. Then, the both engaged side edge portions 13 of the partition plate 15 are provided with the both engaged side edge portions 11 of the next partition plate 12 in the side edge length direction, that is, the previous partition plate 1
A plurality of partition plates are arranged so that the partition plates 12 and 15 are slidably fitted in a direction orthogonal to the sliding fitting direction, and the partition plate 15 turned upside down is slidably fitted as described above. 1
2, 15 are alternately laminated. As a result, FIG. 6 and FIG.
As shown in the drawing, between the adjacent partition plates 12 and 15 connected by the engagement of the engaging side edge portion 10 and the engaged side edge portion 14, both partition plates 12 and 15 are provided at each corner portion 2. The adjacent partition plates 15 and 12 in which the bent plate portions 7 are adjacent to each other and the projecting portions 8 are in contact with each other and are connected by the engagement of the engaging side edge portion 13 and the engaged side edge portion 11 In between,
The corner portions 2 are opened and the bent portions 9 are in contact with each other.

As described above, the plurality of partition plates 12 and 15 are laminated and integrated to form the partition plate laminating unit 16. However, as shown in FIG. 7, the bent plate portions 7 of the corner portions 2 face inward at both ends. Therefore, the partition plates 12 and 15 are arranged so that the protruding portion 9 faces outward. Further, on the partition plate 15 located at one end, instead of the engaging side edge portion 13 having a U-shaped cross section that protrudes outward, a flat side edge portion 17 that is the same as the engaged side edge portion 14 is formed. I am using a board. In the partition plate stacking unit 16 configured as above, the adjacent partition plates 1 in which the protruding portions 9 are in contact with each other.
Flow passages 18 and 19 penetrating in a direction orthogonal to each other are formed between the Nos. 2 and 15 and between the adjacent partition plates 12 and 15 at which the protruding portions 8 face each other.

The cross-flow heat exchanger 20 shown in FIGS. 8 to 11 is one in which the partition plate laminated unit 16 assembled as described above is housed in a rectangular casing 21, and one flow path 18 is A high temperature exhaust gas flow path connecting the exhaust gas inflow port 22 and the exhaust gas outflow port 23 formed on both parallel sides of the casing 21 is formed, and the other flow path 19 is
It is a combustion air flow path that connects a combustion air inflow port 24 and a combustion air outflow port 25, which are formed on both parallel sides of the casing 21. 26 is each partition plate 1
2, 15 are sealing materials continuous in the stacking direction, and are installed in the sealing material holding spaces 27 formed at the four corners of the casing 21 so as to face the four corners of the partition plate stacking unit 16, and each partition The plates 12 and 15 are pressed by the sealing material retainer 28 so as to come into pressure contact with the bent plate portions 7 of the respective arc-shaped corner portions 2.

In the cross-flow heat exchanger 20 as described above, a tip discharge port is opened to the high temperature exhaust gas passage 18 side in each partition plate 12 and 15 at a position avoiding the respective bent portions 8 and 9. As described above, a plurality of pressure air discharge nozzles 29 are attached, and the plurality of nozzles 29 attached to one partition plate 12, 15 are divided into a plurality of groups in the flow direction of the high temperature exhaust gas flow passage 18. Multiple nozzles 29 belonging to the same section
Is connected to a pressure air supply pipe 30 arranged adjacent to the combustion air flow path 19 side of each partition plate 12, 15. Each pressure air supply pipe 30 is divided into a plurality of groups in the flow direction of the high temperature exhaust gas flow passage 18, belongs to the same division, and is arranged in parallel in the stacking direction of the partition plates 12 and 15. Are connected to common branch pipes 31a to 31e, and the respective branch pipes 31a to 31e are connected to the main pipe 32 via opening / closing solenoid valves 32a to 32e, respectively.

The cross-flow heat exchanger 20 configured as described above includes the first
As shown in FIG.
So that high temperature exhaust gas from the furnace 34 flows through the exhaust gas duct 36 from the furnace 34 to the electric machine dust collector 35, the combustion air outlet 25 and the combustion air intake port of the furnace 34. And are connected by a duct 37. The air compressor 38 and the main pipe 33 are connected to each other so that pressurized air can be supplied to each nozzle 29.

The hot exhaust gas discharged from the furnace 34 through the duct 36 flows through the hot exhaust gas passage 18 in the heat exchanger 20 while the combustion air passage 19 is adjacent to the hot exhaust gas passage 18.
Heat is exchanged with the room temperature combustion air flowing through the partition plates 12 and 15. As a result, the preheated combustion air is introduced into the furnace 34, and one exhaust gas is cooled. The cooled exhaust gas is discharged to the atmosphere from the flue 39 after the dust contained in the electric machine dust collector 35 is removed.

On the other hand, the compressed air supplied from the air compressor 38 is introduced from the main pipe 33 into the branch pipes 31a to 31e by the opening of each of the opening / closing solenoid valves 32a to 32e, and the branch pipes 31a to 31e.
It is discharged from the nozzle e into the high temperature exhaust gas passage 18 via the pressure air supply pipe 30 arranged in the combustion air passage 19. That is, each nozzle 29 discharges pressure air from one inner side surface of each high-temperature exhaust gas flow path 18 to the other inner side surface, but the pressure air discharged from each nozzle 29 is discharged in the discharge direction side. Partition plate 12,
Nozzles 29 having a wide diffusion injection angle are used so that the injection can be performed inside all of the protruding portions 8 formed on the high temperature exhaust gas flow path 18 and recessed when viewed from the high temperature exhaust gas flow path 18 side.
It is preferable to consider the arrangement of 9.

However, due to the discharge of the compressed air from each nozzle 29, the inner surface of the high temperature exhaust gas passage 18, that is, the partition plates 12, 15
Dust that has adhered to or is about to adhere to the surface of the high temperature exhaust gas flow path 18 side is blown away by the pressurized air. The dust blown off is introduced from the heat exchanger 20 to the electrostatic precipitator 35 through the duct 36 together with other dust originally contained in the high-temperature exhaust gas, and is separated and removed from the exhaust gas there.

Although it is possible to continuously discharge the pressurized air from all the nozzles 29, as described above, the opening / closing solenoid valves 32a to 32e are used.
When each is provided, the opening / closing solenoid valves 32a to 32e are sequentially switched to the open state for a certain period of time, so that the number of nozzles 29 communicating with the common branch pipes 31a to 31e is set as one group, and each group is provided. The pressure air can be discharged from the nozzle 29 for a certain period of time to reduce the required flow rate of the pressure air per unit time. Of course, the nozzle 2
The method of grouping 9 is not limited to the above embodiment.
For example, the nozzles 29 attached to the common partition plates 12 and 15 may be set as one group, and compressed air may be supplied to the nozzles 29 via the opening / closing solenoid valve for each group, or high temperature exhaust gas may be supplied. A direction orthogonal to the flow passage direction of the flow passage 18 (flow passage direction of the combustion air flow passage 19)
It is also possible to divide the nozzles 29 into a plurality of groups and supply the pressurized air to the nozzles 29 via the opening / closing solenoid valve for each group. Furthermore, it is possible to control so that the pressurized air is not discharged from all the nozzles 29 for a certain period of time.

The air compressor 38 compresses the ambient temperature air to compress the main pipe 3
Although it may be sent to No. 3, as a result of mixing the high temperature exhaust gas and the pressure air discharged from each nozzle 29,
The cooling effect of high temperature exhaust gas is enhanced. In other words, the preheating effect on the combustion air is reduced, but in order to avoid this, the preheated combustion air is taken out from the duct 37 as shown by the phantom line in FIG.
It is also possible to pressurize at 8 and supply to the nozzle 29.

Further, as in the embodiment, each pressure air supply pipe 30 has a plurality of nozzles 2 attached to the same partition plates 12 and 15.
9 is connected, the partition plates 12 and 15 can be stacked as shown in FIG. 5 with the nozzle 29 and the pressurized air supply pipe 30 attached to the partition plates 12 and 15. However, in some cases, as shown by the phantom lines in FIG. 9, the plurality of nozzles 2 attached to the partition plates 12 and 15 located on both sides of the combustion air flow path 19
9 can also be connected by a pressure air supply pipe 30 'diagonally traversing both partition plates 12,15. In any case, the pressure air supply pipes 30 for connecting the plurality of nozzles 29 are not arranged in a straight line but are arranged in a zigzag shape as shown in the drawing so that the partition plates 12 and 15 are accommodated in the thermal expansion storage. The change in the distance between the nozzles 29 can be absorbed without any trouble. Of course,
The pressure air supply pipe 30 is also preferably made of the same material as the partition plates 12 and 15.

As shown in FIG. 10, a recess 40 that is recessed when viewed from the side of the high temperature exhaust gas passage 18 is formed at the nozzle mounting position of the partition plates 12 and 15 so that the nozzle 29 fits in this recess 40. Each nozzle 29 can be attached to the partition plates 12 and 15.

(Operation and Effect of the Invention) As shown in the above embodiment, the cross-flow heat exchanger of the present invention has a high-temperature exhaust gas flowing in one flow passage divided by a partition plate and the other flow passage. The heat exchange is performed with the flowing combustion air to cool the high-temperature exhaust gas and preheat the combustion air.In the state where this heat exchange action is performed, the pressure air supply pipe By supplying pressure air from outside the flow path to each nozzle, the pressure air is discharged from each nozzle toward the inner surface of the high temperature exhaust gas flow path, that is, the surface of the partition plate facing the nozzle facing the high temperature exhaust gas flow path. Thus, the dust that adheres to or is about to adhere to the inner surface of the high temperature exhaust gas passage can be blown off.

Therefore, by supplying the pressure air to the pressure air supply pipe continuously or at appropriate time intervals, it is possible to prevent the dust from adhering to the inner surface of the high temperature exhaust gas passage and lowering the heat exchange efficiency. Moreover, since the dust removed by the discharge of the pressurized air is discharged to the outside of the device together with the exhaust gas, it can be separated and removed by an appropriate dust collecting means such as an electric dust collector in the next stage. Especially, according to the configuration of the present invention, the following operational effects can be obtained.

Compared to the case where hot exhaust gas itself is ejected onto the surface of a partition plate for heat exchange with combustion air to prevent dust contained in the exhaust gas from adhering to the surface of the partition plate for heat exchange. Effective for removal of adhered dust and prevention of adhered dust, the air can be blown away using pressure air that is sufficiently higher than the high temperature exhaust gas pressure, so the effect of removing adhered dust and preventing adherence of dust is extremely high. Is very large.

Since the pressure air is supplied to each nozzle from the pressure air supply pipe, as described in the embodiment, the heat exchanger is controlled by installing an electromagnetic valve in the pressure air supply pipe to control the solenoid. It is also possible to divide the nozzles into groups and supply pressurized air to each group in sequence without supplying pressurized air from all the nozzles in the same time. It is possible to reduce the size of the air compressor that must be used together and to reduce the running cost.

Since the pressurized air supplied from outside the flow path is discharged from the nozzle instead of the hot exhaust gas, there is no possibility that the nozzle will be clogged with the dust contained in the hot exhaust gas, and the pressurized air supply pipe is Since it is installed not in the high temperature exhaust gas flow path but in the normal temperature combustion air flow path, there is no fear that dust will start to accumulate from the gap between the pressure air supply pipe and the partition plate. Is. Therefore, there is almost no need to disassemble and clean the heat exchanger.

Not only during the operation of the boiler but also when the boiler is at rest, it is possible to clean the inner surface of the hot exhaust gas passage as long as the pressurized air is supplied to the pressurized air supply pipe.

Since it is not necessary to partition the hot exhaust gas flow path or the combustion air flow path, it is sufficient to simply attach the nozzle and the pressure air supply pipe to the conventional partition plate, so the structure is simple and inexpensive to implement. In addition, there is no inconvenience that the heat exchanger becomes large in size and a space where dust is likely to be accumulated is formed especially in the high temperature exhaust gas passage.

[Brief description of drawings]

FIG. 1 is a perspective view showing a rectangular plate for forming a partition plate, FIG. 2 is a longitudinal side view thereof, FIGS. 3 and 4 are front views of the molded partition plate, and FIG. 5 is a partition plate. 6 is a perspective view showing a corner portion of the assembled partition plate laminated unit, FIG. 7 is a partially cutaway side view of the unit, and FIG. 8 uses the unit. Fig. 9 is a vertical sectional side view of the heat exchanger, Fig. 10 is a vertical sectional side view of the same heat exchanger, Fig. 10 is a sectional view showing the details of the nozzle mounting portion, and Fig. 11 is the usage state of the heat exchanger. It is a block diagram explaining. DESCRIPTION OF SYMBOLS 1 ... Rectangular plate, 2 ... Arc-shaped notch corner part, 3a, 3
b, 5a, 5b ... Obliquely bent sides, 7 ... Bent plate portion, 8, 9 ... Bent portion, 10, 13 ... Engaging side edge portion having U-shaped cross section, 11, 14 ... Engagement Mating side edge portion, 12, 15 ... Partition plate, 16 ... Partition plate lamination unit, 18 ... High temperature exhaust gas flow path, 19 ... Combustion air flow path, 20 ... Cross flow heat exchanger, 21 ... Casing, 26 ... Sealing material, 29 ... Pressure air discharge nozzle, 30, 30 '... Pressure air supply pipe, 31a
-31e ... Branch pipe, 32a-32e ... Open / close solenoid valve, 33
... Main pipe, 34 ... Furnace, 35 ... Electrostatic precipitator, 36 ... Exhaust gas duct, 37 ... Preheating combustion air duct, 38 ... Air compressor, 40 ... Recessed portion.

Claims (1)

[Claims] 1. A high-temperature exhaust gas flow path and a combustion air flow path are formed adjacent to each other through partition plates arranged in parallel at appropriate intervals, and the flow path directions are orthogonal to each other. In a cross-flow heat exchanger for preheating combustion air, at least one of a pair of partition plates forming the flow path of the high temperature exhaust gas, the surface of the other partition plate facing the high temperature exhaust gas flow path. Nozzles for discharging pressure air toward the nozzles are mounted in an appropriate arrangement, and a pressure air supply pipe connected to each of the nozzles is arranged in the flow path of the combustion air adjacent to the partition plate to which the nozzle is attached. A cross-flow heat exchanger configured so that pressure air can be introduced into the pressure air supply pipe from outside the flow path of combustion air.