JPH031594B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger, and in particular, a heat exchanger in which a heat medium is enclosed in separate sealed containers having an evaporating section disposed in a high-temperature flow path and a condensing section disposed in a low-temperature flow path. , relates to a type of heat exchanger that transports heat as the heat medium moves.

Conventionally, when preheating fuel (mainly gas fuel) and combustion air using the heat retained in combustion exhaust gas in boiler equipment, etc., non-leak type was generally used in the fuel preheating section because it would be dangerous if there was a fuel leak. A plate type heat exchanger or a heat medium circulation type heat exchanger using pump power was used, while a rotary regeneration type heat exchanger was used in the air preheating section. However, this method of using different heat exchangers for the fuel preheating section and the air preheating section requires a large installation space and is also disadvantageous in terms of cost.

In order to eliminate these drawbacks, the use of a heat exchanger consisting of a separate heat pipe is being considered. 1 and 2 are diagrams for explaining this heat exchanger. FIG. 1 is an explanatory diagram showing a heat receiving pattern, and FIG. 2 is a schematic diagram of the structure of the heat exchanger.

First, the schematic structure of the heat exchanger will be explained using FIG. 2. The high-temperature exhaust gas 1 is guided by the exhaust gas duct 2 and flows from left to right toward the page as shown by the arrow. The combustion air 3 is guided by the air duct 4 and flows from right to left toward the page as shown by the arrow. Further, the fuel gas 5 flows from right to left toward the plane of the paper as shown by the arrows guided by the fuel gas duct 6. In practice, the air duct 4 as well as the fuel gas duct 6 are arranged above the exhaust gas duct 2.

Separate heat pipes are individually arranged from the exhaust gas duct 2 to the air duct 4 and from the exhaust gas duct 2 to the fuel gas duct 6. That is, a large number of evaporator tube groups 7 are arranged at predetermined intervals in the exhaust gas duct 2 along the fluid flow direction, and an upper header 8 and a lower header 9 are connected above and below, respectively. A large number of first condensing tube groups 10 are arranged at predetermined intervals in the air duct 4 along the fluid flow direction, and an upper header 11 and a lower header 12 are connected above and below, respectively. A large number of second condensing tube groups 13 are arranged at predetermined intervals in the fuel gas duct 6 along the fluid flow direction, and an upper header 14 and a lower header 15 are connected above and below, respectively.

The evaporator tube group 7, the first condenser tube group 10, and the second condenser tube group 13 are composed of heat transfer tubes arranged in a direction perpendicular to the plane of the drawing.

Each upper header 1 of the first condensing tube group 10
1 and the upper header 8 on the upstream side of the evaporator tube group 7
The peaks are connected by a first upper connecting pipe 16, and the first
Each lower header 12 of the condensing tube group 10 and the lower header 9 on the upstream side of the evaporating tube group 7 are connected by a first lower connecting tube 17, respectively.

Each upper header 1 of the second condensing tube group 13
4 and the remaining downstream upper header 8 of the evaporator tube group 7 are connected by a second upper connecting tube 18, and each lower header 15 of the second condenser tube group 13 and the remaining downstream upper header 8 of the evaporator tube group 7 are connected. The remaining downstream lower headers 9 are connected through second lower connecting pipes 19, respectively. In this way, the first condensing tube group 10 is located at a position facing the upstream side of the evaporator tube group 7, and the second condensing tube group 13 is located at a position facing the downstream side of the evaporating tube group 7.
They are placed separately.

As shown in the figure, one evaporator tube group 7, one condensing tube group 10 (13) corresponding to it, an upper connecting tube 16 (18), and a lower connecting tube 17 (1
9), an individual closed-loop airtight container whose inside is in a reduced pressure state is formed, and a heat medium (not shown) made of water, alcohol, etc. is sealed therein.

The heat medium in each evaporator tube group 7 becomes vapor due to the heat retained in the high-temperature exhaust gas 1, which passes through the upper header 8, the first upper connecting tube 16, and the upper header 11 to the first condensing tube group 11 and the upper Header 8, 2nd
The upper connecting pipe 18 passes through the upper header 14 to the second
and the condensing tube group 13. Then, the heat medium vapor is condensed while being deprived of heat by combustion air 3 or fuel gas 5 (combustion air 3 or fuel gas 5
is preheated by the heat removed), and the condensate of the heating medium passes through the lower header 12, the first lower connecting pipe 17, the lower header 9, or the lower header 1.
5. It is returned to each evaporator tube group 7 through the second lower connecting pipe 19 and the lower header 9. By repeating the cycle of evaporation and condensation of the heat medium in this manner, the heat retained in the high-temperature exhaust gas 1 is recovered, and the combustion air 3 and fuel gas 5 are preheated using the heat.

Figure 1 is a diagram showing the heat acceptance pattern of this heat exchanger. In the figure, A shows the air preheating zone, B shows the fuel preheating zone, straight line C shows the temperature drop of exhaust gas, and straight line D shows the temperature drop of combustion air. Temperature rise, straight line E shows the temperature rise of the fuel gas.

This heat reception will be specifically explained using figures. For example, 220000m ³ N/h of exhaust gas from 260℃
Collect heat up to 110℃ and use that heat to generate 112,000m ³ N/h
of combustion air from 20℃ to 165℃, and 120,000m ³ N/h of fuel gas from 20℃ to 165℃.
When raising the temperature to 165℃, the final preheating of the fuel gas will be performed by recovering heat from the point where the heat retained in the exhaust gas is approximately 191℃, and the temperature difference ΔT will be approximately 29℃ (191℃).
-162=29).

In order to preheat to the desired temperature with such a small temperature difference, it is necessary to increase the heat transfer area by increasing the heat transfer tubes in each of the evaporator tube group and condensation tube group, and as a result, the heat transfer area is increased. This is undesirable because it increases the size and cost of the exchanger.

An object of the present invention is to eliminate such drawbacks of the prior art and to provide an efficient heat exchanger that can be made smaller and lower in cost.

To achieve this objective, the present invention includes a large number of evaporation tube groups arranged along the fluid flow direction in a high temperature flow path through which a high temperature fluid flows, and a first constant temperature flow path through which a first low temperature fluid flows. a large number of first condensing tube groups arranged along the fluid flow direction; a large number of second condensing pipe groups arranged along the fluid flow direction in a second low temperature flow path through which a second low temperature fluid flows; and the evaporation tube. a first upper connecting pipe that connects some of the upper headers of the group to the upper header of the first condensing tube group; and a lower header of some of the evaporator tube groups to the lower header of the first condensing tube group. a first lower connecting pipe connecting the other upper header of the evaporator tube group to the upper header of the second condensing tube group; a second lower connecting tube group connecting the lower header of the second condensing tube group with the lower header of the second condensing tube group; a heat exchanger for performing heat exchange between the high-temperature fluid and a first low-temperature fluid and a second low-temperature fluid, comprising: a heat exchanger formed between the high-temperature flow path and the first low-temperature flow path; At least one of the first closed loop type airtight container and the second closed loop type airtight container formed between the high temperature flow path and the second low temperature flow path is connected to the other airtight container. It is characterized in that it is arranged on the upstream side and the downstream side in the fluid flow direction, respectively.

Next, examples of the present invention will be described. 3 and 4 are for explaining the heat exchanger according to the first embodiment, FIG. 3 is an explanatory diagram showing a heat receiving pattern, and FIG. 4 is a schematic configuration diagram of the heat exchanger. It is.

First, the schematic structure of the heat exchanger will be explained using FIG. 4. For one exhaust gas duct 2 through which high-temperature exhaust gas 1 (heating medium) flows, there are an air duct 4 through which combustion air 3 (heated medium) flows and a fuel gas duct 6 through which fuel gas 5 (heated medium) flows. is set up.

The exhaust gas duct 2 includes a large number of evaporator tube groups 7,
The air duct 4 has a large number of first condensing pipe groups 10, and the fuel gas duct 6 has a large number of second condensing pipe groups 13.
Each of them is arranged along the fluid flow direction.

Some of the evaporator tube group 7 are headers 8, 9, 1
1, 12 through the first upper and lower connecting pipes 16, 17
A first closed-loop hermetic container on the combustion air side is formed individually by the above, and the remaining evaporator tube group 7 is connected to a second closed-loop container via headers 8, 9, 14, and 15.
The upper and lower connecting pipes 18 and 19 individually form a second closed loop type airtight container on the fuel gas side, and as shown in the figure, the first closed loop type airtight container and the second closed loop type airtight container are connected to each other. The closed containers are arranged alternately one by one along the fluid flow direction.

The principles of heat transport and the like are the same as those of the prior art described above, so their explanation will be omitted.

Figure 3 is a diagram showing the heat acceptance pattern of this heat exchanger, in which the straight line C represents the temperature drop of the exhaust gas, and the straight line D represents the temperature drop of the exhaust gas.
shows the temperature rise of the combustion air, and the straight line E shows the temperature rise of the fuel gas. As is clear from this figure, it is possible to maintain a large overall temperature difference, increasing the efficiency of heat exchange, and achieving the same result even if the heat transfer area is reduced by approximately 20% compared to the conventional method shown in Figure 2. heat recovery effect can be obtained.

FIG. 5 is a diagram for explaining a second embodiment of the present invention, which differs from the previous embodiment in that it has a first closed loop type airtight container on the combustion air side and a second closed loop type airtight container on the fuel gas side. and are arranged alternately in sets along the fluid flow direction.

In the above embodiment, the case of a separate heat pipe type heat exchanger was explained, but the present invention can also be applied to a heat medium circulation type heat exchanger using pump power or the like.

Furthermore, in the above embodiment, a case was explained in which a plurality of low temperature fluid flow paths are provided for one high temperature fluid flow path and heat exchange is performed between them. The present invention is also applicable to the case where channels are provided and heat exchange is performed between them.

The present invention has the above-mentioned configuration, and can make a large temperature difference between the high temperature side and the low temperature side.
The heat exchange efficiency is increased, the heat transfer area is reduced, and a compact heat exchanger can be provided.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a heat receiving pattern in a conventional heat exchanger, FIG. 2 is a schematic configuration diagram of a conventional heat exchanger, and FIG. 3 is a heat exchanger according to a first embodiment of the present invention. FIG. 4 is a schematic diagram of the heat exchanger, and FIG. 5 is a schematic diagram of the heat exchanger according to the second embodiment of the present invention. 1...High temperature exhaust gas, 2...Exhaust gas duct, 3...
... Combustion air, 4 ... Air duct, 5 ... Fuel gas, 6 ... Fuel gas tact, 7 ... Evaporation tube group, 8
...Upper header, 9...Lower header, 10...
...First condensing tube group, 11... Upper header, 12...
...Lower header, 13...Second condensing tube group, 14...
...Top header, 15...Bottom header, 16...
...First upper connecting pipe, 17... First lower connecting pipe, 1
8...Second upper connecting pipe, 19...Second lower connecting pipe.

Claims (1)

[Claims] 1. A large number of evaporation tube groups arranged along the fluid flow direction in a high temperature flow path through which a high temperature fluid flows, and a large number of evaporation tube groups arranged along the fluid flow direction in a first low temperature flow path through which a first low temperature fluid flows. A large number of first condensing tube groups arranged, a large number of second condensing tube groups arranged along the fluid flow direction in a second low temperature flow path through which a second low temperature fluid flows, and a plurality of second condensing tube groups arranged along the fluid flow direction. A first upper connecting pipe connects some of the upper headers to the upper header of the first condensing tube group;
a first lower connecting pipe connecting the lower header of the condensing tube group; a second upper connecting pipe connecting the other upper header of the evaporator tube group and the upper header of the second condensing tube group; A second lower connecting tube group connecting the other lower header of the tube group and the lower header of the second condensing tube group, and each closed loop type airtight container formed by these upper and lower connecting tubes is sealed respectively. A heat exchanger that performs heat exchange between the high-temperature fluid and a first low-temperature fluid and a second low-temperature fluid; at least one of a first closed loop type airtight container formed across the high temperature flow path and a second closed loop type airtight container formed across the high temperature flow path and the second low temperature flow path; are respectively arranged on the upstream side and the downstream side of the other sealed container in the fluid flow direction. 2. The heat exchanger according to claim 1, wherein the first closed-loop sealed container and the second closed-loop sealed container are alternately arranged one by one along the fluid flow direction. . 3. The heat exchanger according to claim 1, wherein a plurality of the first closed-loop sealed containers and the second closed-loop sealed containers are arranged alternately along the fluid flow direction.