JPH0649128B2 - Low dew point dehumidifier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a low dew point dehumidifier for dehumidifying moisture in gas by cooling the gas to dehumidify it, and in particular to degassing city gas in cold regions. The present invention relates to a low dew point dehumidifying device useful as a wetting device.

[Prior art]

The dew point temperature of the gas in dehumidifying the city gas is set according to the outside air temperature of the four seasons and the conditions such as direct pressure feeding of the gas into the city and press fitting to fill the spherical holder. In a general warm area, the dew point temperature is 0 ℃ or higher, so dehumidification by condensation is all that is required, but in cold areas, it is 20 ℃ and -20 ℃.
Since it changes between ° C, two patterns are required: dehumidification by condensation and dehumidification by frost formation. Furthermore, in the case of the above-mentioned pressure feeding, since the underground temperature becomes higher than the outside air temperature in the cold region in winter, it is not necessary to lower the dew point too much, but in the case of the press-fitting, the spherical tank is exposed to the outside air and becomes low temperature.
It is necessary to obtain a gas with a low dew point.

By the way, as an apparatus capable of dehumidifying water contained in city gas to a dew point of 0 ° C. or lower, for example, Japanese Patent Laid-Open No. 54-63
The one disclosed in Japanese Patent Publication No. 540 is known. In this dehumidifying device, as shown in FIG.
And is pre-cooled to a dew point near 0 ° C. by exchanging heat with ice or frost (hereinafter, simply referred to as frost) attached to the heat transfer tube 32a, then passes through the communication passage 33, and the drain separator 34. Through the other heat exchanger 35, and is cooled by the heat transfer tube 34a to which the refrigerant having the target dew point or less is supplied, and the moisture in the gas is removed by frosting on the surface of the heat transfer tube 35a. The dehumidified gas is sent out through the four-way switching valve 31.
Further, in the one heat exchanger 32, the heat transfer tube 32
The frost adhering to the surface of a is melted by the heat of the gas, falls into the water reservoir 32b below the heat exchanger, and is discharged to the outside. The refrigerant is supplied to the heat transfer pipe 32a or 35a to be frosted via the electromagnetic valves 36 and 37. Thus, when the defrosting of the surface of the heat transfer tube 32a in the one heat exchanger 32 is completed and the amount of frost on the surface of the heat transfer tube 35 of the other heat exchanger 35 increases, the four-way switching valve 31 and the solenoid valve 36. , 37 are switched, the above steps are performed in the opposite heat exchangers, and the defrosting precooling step and the frosting / dehumidifying step are alternately performed in the pair of heat exchangers 32, 35. The heat of condensation in the refrigerator that supplies the refrigerant is discharged to the outside of the system by cooling water.

However, in the above configuration, the dehumidified gas is -2.
Since the gas is close to 0 ° C, low temperature materials must be used for the downstream pipe and the spherical holder. In order to avoid this, a gas-gas heat exchanger 38 is provided in the gas outlet pipe to exchange heat with the gas entering the dehumidifying device and reheat, or to reheat by another heat source. Can be considered. However, the former causes a problem that the dehumidified gas has a low temperature, so that the moisture in the incoming gas is frozen and the heat exchanger is more likely to be clogged, and the latter causes another heat source. There is a problem that extra energy is required to supply more heat.

Further, as shown in FIG. 4, a pair of heat exchangers 41, 42
And the gas is supplied alternately to these heat exchangers by the three-way switching valve 43, and the heat exchanger 41 (or 4
2) Refrigerant or cold brine, defrost-side heat exchanger 42
Even in the dehumidifying device configured to supply hot refrigerant, hot brine, hot water, etc. to (or 41), it is necessary to similarly configure the downstream side with a low temperature material when obtaining a gas having a dew point of 0 ° C. or less. . Further, when the dew point is 0 ° C. or higher, the heat exchanger simply dehumidifies the dew condensation. Therefore, in this case, the drain separator 44 having a built-in demister can prevent the dew condensation water from scattering. It is arranged in the pipe 45. However, at the time of defrosting and dehumidifying, there is a possibility that the demister may be clogged with a slight amount of frost, and the gas outlet pipe 45 is branched so as to bypass the drain separation device 44 to be the three-way switching valve 46. Need to switch.

On the other hand, as a solution to the above problem,
No. 103119 and No. 58-48324,
Disclosed is a configuration in which a refrigerant of a refrigerator is directly supplied to heat a low temperature gas after dehumidification, and thereafter, the incoming gas is cooled and dehumidified by the refrigerant having a low temperature. .

However, in the above configuration, since the refrigerant of the refrigerator is directly supplied, the refrigeration cycle of the refrigerator is directly affected and the operation tends to become unstable. Therefore, liquid return of the refrigerant may occur, and this liquid return causes liquid compression in the compressor, which may damage the compressor. Further, in the above configuration, the gas passes through the two-stage heat exchanger for pre-cooling and dehumidifying for dehumidification, so that there is a problem that the pressure loss becomes large.

[Object of the Invention]

The present invention has been made in consideration of the above conventional problems, and in the case of defrosting and dehumidification, it is possible to perform stable dehumidification processing by utilizing waste heat (condensation heat) of a refrigerator. At the same time, it is an object of the present invention to provide a low dew point dehumidifying device which can raise the temperature of the dehumidified gas to limit the range of use of the low temperature material and can cope with dew condensation dehumidification.

[Structure of Invention]

The low dew point dehumidifier of the present invention is provided with a pair of heat exchangers capable of alternately supplying the gas to be dehumidified, and provided with a refrigerator for cooling and dehumidifying these heat exchangers. A heat medium circulation line for selectively supplying the heat medium cooled by the evaporator of the machine or the heat medium heated by the condenser to one of the pair of heat exchangers is provided separately from the refrigerant circulation line of the refrigerator, Further, the gas outlet pipe connected to the heat exchanger is provided with a post heat exchanger capable of supplying the heat medium heated by the condenser of the refrigerator by a heat medium circulation line. Is. Here, the heat medium includes a refrigerant that has exchanged heat with the refrigerant in the evaporator of the refrigerator, cold brine, a hot refrigerant that has exchanged heat with the hot refrigerant in the condenser, hot brine, hot water, and the like.

In this way, the heat medium circulation line provided separately from the refrigerant circulation line of the refrigerator performs the dehumidification process of the gas and the heating of the gas after dehumidification, so the refrigeration cycle of the refrigerator has a direct influence. Stable dehumidification treatment is possible without being exposed. In addition, by arranging a post heat exchanger in the gas outlet pipe and heating the gas with the heat medium heated in the condenser of the refrigerator, the temperature of the gas downstream of the dehumidifying device is adjusted to the gas on the inlet side. The temperature can be adjusted to about temperature, the range of use of low-temperature materials can be extended from a pair of heat exchangers to a post-heat exchanger, and switching of the heat medium allows frost dehumidification at low dew points and general frost dehumidification. Condensation dehumidification can be easily performed.

Example 1 An example of the present invention will be described below with reference to FIG. First
The second heat exchangers 1 and 2 are arranged side by side, and the gas inlet pipes 3 are selectively connectable to the gas inlets 1a and 2a thereof via the three-way switching valve 4. The gas outlets 1b, 2b of each heat exchanger 1, 2 are connected to the gas outlet pipe 5. In addition, a heat medium inlet 1c communicating with the heat transfer tubes of the heat exchangers 1 and 2,
2 c is connected to two ports of the inlet four-way switching valve 6, and the heat medium outlets 1 d and 2 d are connected to two ports of the outlet four-way switching valve 7. The remaining two ports of the inlet four-way switching valve 6 are provided with a cold brine circulation line 8 from the refrigerator 10.
Is connected to the supply side line 8a of the hot brine circulation line 9 from the refrigerator. A discharge side line 8b of the cold brine circulation line 8 and a discharge side line 9b of the warm brine circulation line 9 are connected to the remaining two ports of the outlet four-way switching valve 7.
In this way, by switching the both four-way switching valves 6 and 7, cold brine and hot brine can be alternately supplied to the first and second heat exchangers 1 and 2, respectively.

The refrigerator 10 includes a compressor 11 such as a motor-driven screw compressor, a condenser 12, an expansion valve 13, and an evaporator 1.
4 and these devices as a refrigerant (for example, R22)
Are made to circulate. In the condenser 12, the warm brine is heated to about 30 ° C. by the heat of condensation of the refrigerant, and in the evaporator 14, the cold brine is cooled to about −25 ° C. by the heat of evaporation of the refrigerant. There is. The cold brine is pressure-fed by a pump 15 from a cold brine tank 16 arranged in the cold brine circulation line 8 and then returned to the cold brine tank 16 for circulation. The warm brine is pumped from the warm brine tank 18 arranged in the warm brine circulation line 9 by the pump 17, and the warm brine tank 18 via the spare cooler 19.
Is circulated back to.

A post heat exchanger 20 and a drain separator 21 are arranged in series in the gas outlet pipe 5. Rear heat exchanger 20
To the heat transfer pipe of the hot brine circulation line 9 is connected to the supply side line 9a, and the supply side line 9a is provided with a bypass line 22 for bypassing the rear heat exchanger 20. By opening and closing in a contradictory manner, the warm brine is transferred to the rear heat exchanger 20 or the bypass line 2
It is configured to pass through 2.

In the above configuration, the cold brine discharged from the evaporator 14 is sent to the first heat exchanger 1 through the cold brine circulation line 8, and the gas containing water is supplied from the gas inlet pipe 3 through the three-way switching valve 4 to the first heat exchanger 1. When the gas is sent to the heat exchanger 1, the gas is heat-exchanged with cold brine to be cooled, and the moisture in the gas is frosted on the surface of the heat transfer tube in the heat exchanger 1 to dehumidify the gas, for example. It is delivered to the gas outlet pipe 5 as a gas having a low dew point of about -15 to -20 ° C. Then, since the hot brine is passed through the post heat exchanger 20 arranged in the gas outlet pipe 5, the gas is heated and sent out. Therefore, the drain separator 21 will not be clogged with a small amount of frost accompanying the gas. The range of use of the low temperature material is from the heat exchangers 1 and 2 to the rear heat exchanger 20.
Only during the period.

On the other hand, the warm brine discharged from the condenser 12 is circulated and supplied to the second heat exchanger 2 through the warm brine circulation line 9,
Defrosting is performed by exchanging heat with the frost adhering to the surface of the heat transfer tube, and the dissolved water is discharged to the outside of the system by the drain wrap 52.

After a lapse of time, when the frost is sufficiently adhered to the first heat exchanger 1 and the defrosting of the second heat exchanger 2 is completed, the three-way switching valve 4 is switched to change the gas to the second heat exchange. It is sent to the vessel 2, and at the same time, the two four-way switching valves 6 and 7 are switched so that the first heat exchanger 1 defrosts and the second heat exchanger 2 dehumidifies the gas. By repeating the above operation, it is possible to continuously dehumidify the gas. The cooler 19 is used when the amount of heat of condensation of the refrigerator 10 cannot be covered by defrosting. Also, the brine tanks 16 and 1
The pipe 53 that connects the eight pipes is used to equalize the non-uniform return amount of the cold / warm brine to the brine tank caused by the switching of the cold / hot brine by overflow.

On the other hand, when a gas having a dew point of 0 ° C. or higher is obtained, dehumidification may be performed by dew condensation. In this case, when warm brine is passed through the post heat exchanger 20 to heat it, the condensed and condensed moisture evaporates again, and the gas having the target dew point cannot be obtained.
The solenoid valve 23 is closed and the solenoid valve 24 is opened so that the hot brine bypasses the post heat exchanger 20. Then, the drain cooling device 21 removes the water condensed from the gas cooled in the heat exchanger 1 or 2, and the gas having the target dew point is delivered.

Second Embodiment Another embodiment of the present invention will be described with reference to FIG. In the above-mentioned first embodiment, the post heat exchanger 20 and the drain separator 21 are arranged in series with the gas outlet pipe 5 to eliminate the need for gas switching. In this embodiment, the second
As shown in the figure, both of them are arranged in parallel in the gas outlet pipe 5, and when a gas having a dew point of 0 ° C. or less is sent out in cold weather by opening / closing the switching valves 25, 26, the gas passes through the post heat exchanger 20 and 0 ° C.
When the gas having the above dew point is delivered, the drain separation device 21
It is configured to pass through.

〔The invention's effect〕

As described above, the low dew point dehumidifier of the present invention is provided with a pair of heat exchangers capable of alternately supplying the gas to be dehumidified, and a refrigerator for cooling and dehumidifying these heat exchangers. And a heat medium circulation line for selectively supplying the heat medium cooled by the evaporator of the refrigerator or the heat medium heated by the condenser to one of the pair of heat exchangers. In addition to the above, the gas outlet pipe connected to the heat exchanger was provided with a post heat exchanger capable of supplying the heat medium heated by the condenser of the refrigerator by the heat medium circulation line. It is a composition.

As a result, the refrigeration cycle of the refrigerator is not directly affected, and stable dehumidification treatment is possible. Further, the gas can be heated by the heating medium obtained from the waste heat of the refrigerator, and the temperature of the gas downstream of the dehumidifier can be set to the gas temperature on the inlet side while obtaining the gas with a low dew point. it can. Therefore, the range of use of the low temperature material can be limited to a pair of heat exchangers to a rear heat exchanger, and the like.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an embodiment of the present invention, FIG. 2 is a structural explanatory view of a main part of another embodiment of the present invention, and FIGS. 3 and 4 are structural explanatory views of a conventional example. 1 and 2 are heat exchangers, 8 is a cold brine circulation line, 9 is a warm brine circulation line, 10 is a refrigerator, and 20 is a post heat exchanger.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiori Ohama 2-6-1 Nakajima, Takasago-shi, Hyogo (56) References: 53-105551 (JP, U) 57-103119 , U) Actual development Sho 58-48324 (JP, U)

Claims (1)

[Claims] 1. A pair of heat exchangers capable of alternately supplying a gas to be dehumidified are arranged in parallel, and a refrigerator for cooling and dehumidifying these heat exchangers is provided, and an evaporator of this refrigerator is used. A heat medium circulation line for selectively supplying the heat medium to be cooled or the heat medium heated by the condenser to one of the pair of heat exchangers is provided separately from the refrigerant circulation line of the refrigerator, and the heat exchanger is also provided. A low dew point dehumidification device, characterized in that a post heat exchanger capable of supplying the heat medium heated by the condenser of the refrigerator to the gas outlet pipe connected to the heat exchanger by the heat medium circulation line. .