JPH1089863A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a countermeasure for the contamination of a heat transfer surface unnecessary by a method wherein the heat exchange between low boiling point medium vapor and atmospheric water is effected in a direct contact type heat exchanger to condense it and obtain low boiling point medium liquid while the same liquid is evaporated by an indirect contact heat exchanger to obtain the low boiling point medium vapor and return the same into the direct contact type heat exchanger again to constitute a closed cycle. SOLUTION: Atmospheric water enters into the upper part of a direct contact type heat exchanger from an atmospheric water flow passage 1 through a discharging pipe 2b, then, descends the inside of the heat exchanger and is discharged from the lower part of the heat exchanger. On the other hand, low boiling point medium vapor enters the heat exchanger 4 from a pipeline 20 through the lower part thereof, then, is cooled and condensed through heat exchange while ascending above the environmental water. The level of the condensed low boiling point medium liquid rises and the same liquid enters an indirect contact type heat exchanger 7 through a pipeline 17. Here, the same liquid deprives heat of refrigerant in a heat pump 6 and is evaporated, then, the same liquid becomes low boiling point medium vapor. The same vapor enters again the heat exchanger 4 from the lower part thereof through a pipeline 20 and, thus, a closed cycle is constituted. The environmental water is brought into direct contact with the low boiling point medium in the heat exchanger 4 in such a manner whereby a countermeasure for the contamination of a heat transfer surface becomes unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a district heating / cooling system which uses the heat of sewage (treated water or untreated water), river water, seawater, and other water existing in a city and its suburbs (hereinafter referred to as environmental water). The present invention relates to a heat exchanging device to be used for heat exchange.

[0002]

2. Description of the Related Art In recent years, the heat of environmental water has been
Or, it is beginning to be used for district cooling and heating. In these applications, in order to extract the heat (hot or cold) from environmental water, a heat exchanger having a solid heat transfer surface such as a shell and tube type heat exchanger has conventionally been used. Heat exchange with the refrigerant of the heat pump or the fresh water as an intermediate heat medium.

Further, techniques for recovering the retained heat from environmental water such as sewage are disclosed in JP-A-07-159059 (referred to as technique 1) and JP-A-52-118146 (referred to as technique 2). Technology 1 is a technology in which environmental water such as sewage and a high specific gravity water-insoluble liquid intermediate heat medium are brought into direct contact with each other without passing through a solid-wall heat transfer surface to perform heat exchange. The boiling point medium is brought into direct contact with the low heat source medium to evaporate and generate power.

[0004]

In a heat exchanger having a solid heat transfer surface such as a shell and tube type heat exchanger, the flow path surrounded by the heat transfer surface is narrow. It is necessary to install a strainer before flowing into the environment to remove solids (garbage) present in general environmental water.
Furthermore, small dust, liquid contaminants, dissolved components, and the like that have passed through the strainer flow into the heat exchanger, and scale and slime adhere to and accumulate on the heat transfer surface, reducing heat transfer performance. (For example, a sponge ball circulation device, a brush cleaning device, etc.) and the like are required.

[0005] Since these problems are caused by the presence of a solid heat transfer surface in the heat exchanger, the technique 1 proposes a direct contact heat exchanger as a solution to the problem. This method uses the sensible heat of a high specific gravity water-insoluble liquid heat medium.However, the specific heat is generally smaller than that of water, and the flow rate of the heat medium must be increased to recover the required amount of heat. There is a problem that it does not.

On the other hand, in the technology 2, power is generated using a direct contact heat exchanger and a low boiling point medium. However, it is conceivable to apply this technology to recovering heat from environmental water. The technology uses environmental water only as a heat source, and cannot be used for district heating / cooling or the like which uses environmental water as a heat source at one time and as a cold source at other times.

[0007] The present invention is based on the object of the present invention that "special measures against dust, scale and slime are unnecessary, the flow rate of the medium can be reduced, the heat exchange efficiency can be improved, and environmental water can be used as both a heat source and a cold source. It is an object of the present invention to provide a heat exchange device.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a direct contact heat exchanger having respective inlet and outlet pipes for environmental water, a low boiling medium vapor and a low boiling medium liquid; Environmental water supply means for supplying environmental water from the water flow path to the direct contact heat exchanger; environmental water return means for returning environmental water from the direct contact heat exchanger to the environmental waterway; Pump, an indirect contact heat exchanger for exchanging heat between the refrigerant of the heat pump and the low-boiling medium, and circulating the low-boiling medium from a liquid outlet pipe of the low-boiling medium of the direct contact heat exchanger. First flow path means for supplying a low-boiling medium vapor inlet pipe of the direct-contact heat exchanger via a pump and the indirect-contact heat exchanger; and a low-boiling medium of the direct-contact heat exchanger. Indirect contact from the low-boiling medium vapor outlet pipe Via exchanger and a circulation pump solved by the second flow path means and heat exchange device comprising a supply to the inlet pipe of the liquid low boiling point medium of the direct contact heat exchanger.

"Action": Since a direct contact heat exchanger for bringing environmental water into direct contact with a low-boiling medium is used, there is no need to take measures against contamination of the heat transfer surface, and heat transfer accompanied by a phase change of the low-boiling medium. Therefore, it is possible to reduce the flow rate of the low-boiling-point medium and improve the heat exchange efficiency (environmental water: between the low-boiling-point media and low-boiling-point medium: between the refrigerants of the heat pump) as compared with the case of using the medium of the technology 1.

Further, since the first flow path means and the second flow path means are provided, the environmental water can be used as either a hot or cold heat source.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of the device of the present invention. Reference numeral 1 denotes a flow path of environmental water, which includes sewage (including untreated water), rivers, lake water, seawater, and the like. 2a is an environmental water intake pipe, 2 is a pump, 2b is a discharge pipe connected to the environmental water inlet pipe 4a of the direct contact heat exchanger 4, and these constitute environmental water supply means. 3a is a return pipe connected to the environmental water outlet pipe 4b of the direct contact heat exchanger 4, 3 is a separator for separating and recovering a low-boiling medium contained in a trace amount of environmental water, and 3b is a separator for a small amount of a low-boiling medium. These drain pipes discharge the environmental water after the drain to the downstream of the environmental water flow path 1, and these constitute environmental water return means. The separator 3 can be omitted even if a small amount of a low-boiling-point medium is mixed in environmental water, if there is no problem in terms of stability and influence on the environment.

The direct contact heat exchanger 4 includes an environmental water inlet pipe 4a, a low-boiling medium vapor outlet pipe 4f and a low-boiling medium liquid outlet pipe 4e at the upper part, and an environmental water outlet pipe 4b and a low-boiling medium medium at the lower part. Has a vapor inlet pipe 4c and a liquid inlet pipe 4d for a low-boiling medium, and performs heat exchange by bringing environmental water and a low-boiling medium (liquid or vapor) into direct contact. Although not shown in the figure, a plurality of distribution pipes or a plurality of outlet pipes having a large number of blowout holes are provided at the bottom of the direct contact heat exchanger 4 so that the vapor or liquid of the low boiling point medium is easily diffused into the environmental water in the vessel. A distribution box having a number of outlets is provided, to which a vapor or liquid inlet pipe of a low-boiling medium is connected.

Reference numeral 10 denotes a low-boiling medium liquid outlet pipe 4d and a first
Is disposed between the first three-way valve 11 and the circulation pump 5, and 13 is disposed between the circulation pump 5 and the second three-way valve 14. Installed plumbing,
A pipe 15 is disposed between the second three-way valve 14 and the third three-way valve 16; a pipe 17 is disposed between the third three-way valve 16 and the indirect contact heat exchanger 7; Reference numeral 18 denotes a pipe disposed between the heat exchanger 7 and the fourth three-way valve 19, and reference numeral 20 denotes a pipe disposed between the fourth three-way valve 19 and the inlet pipe 4c of the low-boiling medium of the direct contact heat exchanger 4. Provided pipes, and these constitute first passage means for the low-temperature boiling medium. The circulation pump 5 is a pump that circulates a low-boiling medium in the system. However, a particularly high head is not required, and it is sufficient that a margin is added to the pressure loss caused by the flow in the circulation system.

Reference numeral 23 denotes a pipe disposed between the outlet pipe 4f of the low-boiling-point medium vapor of the direct contact heat exchanger 4 and the fourth three-way valve 19, and reference numeral 21 denotes a third three-way valve 16 and the first three-way valve 19. A pipe 22 disposed between the three-way valve 11 and a pipe 22 disposed between the second three-way valve 14 and the inlet pipe 4d of the liquid of the low boiling point medium of the direct contact heat exchanger 4. 23, pipe 18 and pipe 17 (these are also used for the first flow path means), pipe 2
1, the pipe 12 and the pipe 13 (these are also used for the first flow path means) and the pipe 22 constitute the second flow path means.

The apparatus of the present invention can use environmental water as a cold heat source at the time of cooling demand or a hot heat source at the time of heating demand by the above configuration. In the figure, a double line indicates a flow path used for both cooling and heating demands, a solid line indicates a flow path used for cooling demand, and a broken line indicates a flow path used for heating demand. In addition,
Various control valves such as a flow control valve, a buffer tank of a low boiling point medium, and the like are used, but are omitted in the figure.

Next, the operation of the apparatus of the present invention will be described. The case where environmental water is used as a cold heat source will be described below with reference to FIG.

The environmental water directly enters the upper part of the contact heat exchanger 4 from the environmental water flow path 1 via the water intake pipe 2a, the pump 2 and the discharge pipe 2b, descends inside the vessel, returns from the lower part to the return pipe 3a, and separates. The water is discharged downstream of the environmental water flow path 1 via the vessel 3 and the discharge pipe 3b. On the other hand, the steam of the low-boiling-point medium enters the contact heat exchanger 4 directly from below through the pipe 20, and is cooled and condensed by exchanging heat therewith while rising in the environmental water. Since the specific gravity of the liquid of the low-boiling medium (for example, n-butane) is smaller than that of water, the condensed low-boiling medium liquid continues to rise further and rises above the level of the environmental water. This low-boiling-point medium liquid is indirectly transmitted through the pipe 10, the first three-way valve 11, the pipe 12, the circulation pump 5, the pipe 13, the second three-way valve 14, the pipe 15, the third three-way valve 16, and the pipe 17. Enter the contact heat exchanger 7. In the indirect contact heat exchanger 7, the refrigerant of the heat pump 6 is deprived of heat and vaporized to be a low-boiling medium vapor. The low-boiling-point medium vapor passes through the pipe 18, the fourth three-way valve 19, and the pipe 20, and returns from the lower portion to the direct contact heat exchanger 4 again.
to go into. With such a closed cycle, environmental water can be used as a cold heat source. That is, the heat possessed by the environmental water can be used for district cooling and the like.

A case where environmental water is used as a heat source will be described below with reference to FIG. Intake and discharge of the environmental water into and from the direct contact heat exchanger 4 are the same as those in the above-mentioned "when used as a cold heat source", and therefore description thereof is omitted. The low-boiling-point medium liquid enters the contact heat exchanger 4 directly from below via the pipe 22, and is heated by exchanging heat therewith while rising in the environmental water, and becomes steam to exit above the liquid level of the environmental water.
This low-boiling medium vapor is supplied to the pipe 23, the fourth three-way valve 19,
It enters the indirect contact heat exchanger 7 via the pipe 18. In the indirect contact heat exchanger 7, heat is applied to the refrigerant of the heat pump 6, and the refrigerant is condensed to become a liquid. The low-boiling-point medium liquid is supplied to the pipe 17, the third three-way valve 16, the pipe 21, the first three-way valve 1
1, the pipe 12, the circulation pump 5, the pipe 13, the second three-way valve 14, and the pipe 22 again enter the contact heat exchanger 4 directly from below. With such a closed cycle, environmental water can be used as a heat source. That is, the retained heat of the environmental water can be used for district heating and the like.

As the low boiling point medium used in the present heat exchange apparatus, at a relatively high ambient water temperature in summer (for example, about 25 ° C.) requiring a cold heat source, the medium condenses at a modestly high pressure. It is desirable to vaporize at atmospheric pressure or higher at a necessary relatively low environmental water temperature in winter (for example, about 15 ° C.).

As the low-boiling medium that satisfies these conditions, various media can be considered according to the conditions of environmental water and the like.
As an example, considering n-butane, the vapor pressure at 25 ° C. is 1.6 kg / cm ² G, and the vapor pressure at 15 ° C. is 0.8 kg / cm ² G. Therefore, a heat exchange device that satisfies the above conditions and uses the same can be realized without having particularly high pressure resistance.

Since a direct contact heat exchanger is used,
Although it is inevitable that water is mixed in the low boiling point medium,
A small amount is not a problem. However, if it is expected to increase with the passage of time, the removal device may be installed. As the device, for example, a pipe 1
A buffer tank is provided in the flow path of the low-boiling medium liquid such as 3,
The water that accumulates at the bottom due to the specific gravity difference may be discharged out of the system by using a self-powered valve similar to a steam trap.

[0022]

According to the present invention, since a direct contact heat exchanger for bringing environmental water into direct contact with a low-boiling medium is used, it is not necessary to take measures against contamination on the heat transfer surface, and the phase change of the low-boiling medium is eliminated. Therefore, it is possible to reduce the flow rate of the medium and improve the heat exchange efficiency. Further, since the first flow path means and the second flow path means are provided in the circulation system of the low boiling point medium, environmental water can be used as a cold heat source or a warm heat source.

[Brief description of the drawings]

FIG. 1 is a system diagram of the device of the present invention.

FIG. 2 is a system diagram in a case where environmental water is used as a cold heat source in the apparatus of the present invention.

FIG. 3 is a system diagram in the case where environmental water is used as a heat source in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Environmental water flow path 2 Pump 3 Separator 4 Direct contact heat exchanger 5 Circulation pump 6 Heat pump 7 Indirect contact heat exchanger 11 First three-way valve 14 Second three-way valve 16 Third three-way valve 19th 4 three-way valve

Claims (1)

[Claims] 1. A direct contact heat exchanger having an inlet pipe and an outlet pipe for environmental water, low-boiling-point medium vapor and low-boiling-point medium liquid, and direct contacting of environmental water from a flow path of environmental water. Environmental water supply means for supplying to the type heat exchanger, environmental water return means for returning environmental water from the direct contact type heat exchanger to the environmental waterway, a heat pump for recovering retained heat of environmental water, and a refrigerant for the heat pump. An indirect contact heat exchanger that performs heat exchange with the low-boiling medium, and a low-boiling medium from the liquid outlet pipe of the low-boiling medium of the direct-contact heat exchanger through a circulation pump and the indirect-contact heat exchanger. First flow path means for supplying a low-boiling medium vapor inlet pipe of the direct contact heat exchanger; and a low-boiling medium vapor outlet pipe of the direct contact heat exchanger for indirectly supplying the low-boiling medium vapor to the direct contact heat exchanger. Directly via contact heat exchanger and circulation pump A second flow passage means for supplying a low-boiling-point medium liquid to an inlet pipe of the contact heat exchanger.