JP2000320920A - Ammonia absorption refrigerator - Google Patents

Abstract

(57) [Object] To provide an ammonia absorption refrigerator capable of preventing moisture from remaining in a heat transfer tube of an evaporator even when a refrigeration load is small. A direct expansion type evaporator (1) for introducing and evaporating an ammonia solution into a heat transfer tube (1a), an absorber (2) for absorbing ammonia vapor, and a regenerating unit (4) for heating and regenerating the absorbing solution by a combustor (3). And a condenser 5 for condensing ammonia vapor,
Fuel is supplied to the combustor 3 in an ammonia absorption refrigerator having an expansion valve 15 on the way and a refrigerant liquid transfer pipe 16 for transferring the ammonia liquid from the condenser 5 to the heat transfer pipe 1a of the evaporator 1. A valve opening detector 23 for detecting the valve opening of the fuel supply valve 21 is provided, and the valve opening detected by the detector is input, and the valve opening is compared with the set opening. A controller 24 is provided which outputs a control signal for temporarily increasing the valve opening of the expansion valve 15 when the valve opening smaller than the set opening continues for a set time or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ammonia absorption refrigerator having a direct expansion type evaporator.

[0002]

2. Description of the Related Art In general, in an ammonia absorption refrigerator, an ammonia solution having a concentration of 99.8% (water content: 0.2%) is transferred to an evaporator to be evaporated. ,
During operation, it gradually accumulates, the concentration of the ammonia liquid in the evaporator decreases, and the refrigeration capacity decreases.

In order to prevent this decrease in the refrigerating capacity, usually, the ammonia liquid stored at the bottom of the evaporator is taken out, and the heat of the high-temperature ammonia liquid transferred from the condenser to the evaporator is used. In addition, a refrigerant regenerator that regenerates a refrigerant by evaporating water in an ammonia liquid has been provided.

[0004]

By the way, as the evaporator of the above-mentioned ammonia absorption refrigerator, the ammonia liquid is decompressed by an expansion valve, guided to a heat transfer tube arranged in the evaporator, and evaporated. In the case of using an expansion type, the heat transfer tube arranged in the evaporator is provided in a meandering shape, that is, the outlet portion of the heat transfer tube and the absorber side are:
Since the connection is made by the refrigerant vapor transfer pipe, the ammonia liquid cannot be directly taken out from the bottom of the evaporator and guided to the refrigerant regenerator as in the conventional case.

Therefore, an ammonia solution containing a large amount of water is accumulated in the heat transfer tube of the evaporator, and when the refrigeration load is large, a large amount of ammonia flows, so that the moisture is accumulated in the evaporator. However, when the load is low and the refrigeration load is small, the water accumulated in the heat transfer tubes cannot be taken away, so that not only the refrigeration performance is reduced but also the operation becomes impossible. There was a problem that a case might arise.

Accordingly, an object of the present invention is to provide an ammonia absorption refrigerator capable of preventing moisture from remaining in a heat transfer tube of an evaporator even when a refrigeration load is small.

[0007]

In order to solve the above-mentioned problems, an ammonia absorption refrigerator according to the present invention comprises a direct expansion type evaporator for guiding an ammonia solution into a heat transfer tube and evaporating the ammonia solution, and converting ammonia vapor into an absorption solution. An absorber for absorbing, a regenerating part for heating and regenerating the absorbing liquid that has absorbed the ammonia vapor, a condenser for condensing the ammonia vapor heated and evaporated in the regenerating part, and the condenser having an expansion valve in the middle and the condenser A refrigerant liquid transfer pipe for transferring the ammonia liquid obtained in the above to a heat transfer pipe in the evaporator, and a refrigerant vapor transfer pipe for transferring the ammonia vapor evaporated in the heat transfer pipe in the evaporator to the absorber. A state quantity detecting means for detecting a state quantity in a refrigeration cycle, and a state quantity detected by the state quantity detecting means, and a large refrigeration load based on the duration. And control means for outputting a control signal for temporarily increasing the valve opening of the expansion valve when the refrigeration load is small, and in the ammonia absorption refrigerator, As the detecting means, a valve opening detector that detects the valve opening of the fuel supply valve to the combustor in the regeneration unit is used, and by the control means,
The valve opening is input, the valve opening is compared with the set opening, and if the valve opening smaller than the set opening continues for a set time or more, the valve opening of the expansion valve is temporarily set. The ammonia absorption refrigerator further includes a valve for detecting a valve opening degree of an expansion valve provided in the middle of the refrigerant liquid transfer pipe as a state quantity detection unit. Using an opening detector and controlling means,
The valve opening is input, the valve opening is compared with the set opening, and when the valve opening smaller than the set opening continues for the set time, the valve opening of the expansion valve is temporarily increased. This is configured to output a control signal to be executed.

According to each of the above constructions, when the refrigeration load is smaller than the set load in accordance with the refrigeration load in the absorption refrigerator, for example, the valve opening of the fuel supply valve or the refrigerant liquid in the regeneration section is evaporated. If the state of the valve opening of the expansion valve provided in the middle of the refrigerant liquid transfer pipe to be supplied to the device continues for a set time or less than the set opening, by the controller,
Temporarily, the expansion valve is widely opened, and the ammonia liquid from the condenser is supplied into the heat transfer tube of the evaporator at one time, so that the flow of the expanded large amount of ammonia vapor causes
The ammonia solution containing water accumulated in the heat transfer tube is discharged vigorously.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ammonia absorption refrigerator according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the ammonia absorption refrigerator has a heat transfer tube 1a for introducing an ammonia liquid as a refrigerant liquid, evaporates the ammonia liquid in the heat transfer tube 1a, and cools the fluid to be cooled (for example, , Air, gas, etc.), an absorber 2 for absorbing ammonia vapor, which is a refrigerant vapor evaporated by the evaporator 1, to an aqueous ammonia solution as an absorbing liquid, and a combustor (for example, a combustion burner). A) a regeneration unit 4 which comprises a heating regenerator 4a provided with 3 and a rectification column 4b and guides an aqueous ammonia solution which has absorbed ammonia vapor in the absorber 2 to perform heating regeneration, and an ammonia regenerated by the regeneration unit 4 A condenser 5 for condensing the vapor, and a first refrigerant vapor transfer pipe 11 for transporting the ammonia vapor in the heat transfer pipe 1a of the evaporator 1 to the absorber 2.
And an absorption liquid transfer pipe 13 having a liquid transfer pump 12 on the way and transferring the ammonia aqueous solution having absorbed the ammonia vapor by the absorber 2 to the regeneration unit 4, and exiting from the rectification column 4 b side of the regeneration unit 4. A second refrigerant vapor transfer pipe 14 for transporting ammonia vapor to the condenser 5, and an expansion valve 15 whose valve opening is controlled by a drive unit 15 a on the way, and the ammonia liquid condensed in the condenser 5 is supplied to the evaporator 1. And a reflux pipe having a reflux pump 17 in the middle thereof and refluxing a part of the ammonia liquid flowing through the refrigerant liquid transfer pipe 16 to the rectification column 4b of the regeneration unit 4. 18, provided between the first refrigerant vapor transfer pipe 11 and the refrigerant liquid transfer pipe 16, in order to improve the thermal efficiency by giving the heat of the ammonia liquid from the condenser 5 to the ammonia vapor from the evaporator 1. The subcooler 19 in the middle, the drive unit 2
A fuel supply valve 21 having a fuel supply valve 21 whose valve opening is controlled by 1a and a fuel supply pipe 22 for supplying fuel to the combustor 3 provided in the heating regenerator 4a of the regenerating section 4 are provided.

The ammonia absorption refrigerator detects the amount of fuel supply over time to determine the magnitude of the refrigeration load. When the refrigeration load is small, the expansion valve 1
5 is temporarily opened widely so that a large amount of ammonia solution flows into the heat transfer tube 1a at a time. That is, a valve opening detector (state quantity detecting means) 23 for detecting the valve opening (state quantity) of the fuel supply valve 21 is provided, and the valve opening detected by the valve opening detector 23 is inputted. A controller (control means) 24 for outputting a control signal of the valve opening degree to the drive section 15a of the expansion valve 15 is provided.

In the controller 24, the valve opening from the valve opening detector 23 is input, and the valve opening is smaller than a predetermined set opening and smaller than the set opening. Is detected, and when this duration exceeds a predetermined set time, a control signal is output to the drive unit 15a of the expansion valve 15 such that it is fully opened, for example, for about 2 to 3 seconds. Is done.

In the above configuration, in the operation state of the refrigeration cycle, the ammonia liquid decompressed by the expansion valve 15 is supplied to the heat transfer pipe 1a of the evaporator 1 via the refrigerant liquid transfer pipe 16 and evaporation is performed. The fluid to be cooled supplied into the evaporator 1 is cooled. By the way, when the cooling load is reduced, the opening degree of the fuel control valve 21 is reduced, and the amount of fuel supplied to the combustor 3 provided in the heating regenerator 4a is reduced.

At any time, the valve opening of the fuel supply valve 21 is detected by a valve opening detector 23 and inputted to a controller 24. Then, the controller 24 compares the input valve opening with a preset setting opening, and when the valve opening is smaller than the setting opening, the continuation time at the smaller valve opening is determined. Is detected. That is, the continuation time at the valve opening smaller than the set opening is detected.

If the continuation time exceeds a predetermined time, it is determined that the state of low refrigeration load has continued for a long time, and the drive unit 15a of the expansion valve 15 is supplied to the drive unit 15a of the expansion valve 15 for a period of time, for example, for about 2 to 3 seconds. , A control signal for fully opening the valve is output.
As described above, when the expansion valve 15 is fully opened, a large amount of ammonia solution is supplied into the heat transfer tube 1a at a time, so that the mixed (moisture-rich) ammonia solution stored in the heat transfer tube 1a vigorously. To blow out and swell from the heat transfer tube 1a into the first ammonia vapor transfer pipe 11, and to wipe out moisture accumulated in the heat transfer tube 1a and the first ammonia vapor transfer pipe 11 by the expanded large amount of ammonia vapor. Can be.

That is, when the refrigeration load is reduced,
Water that easily accumulates in the tube can be forcibly removed together with the ammonia solution. Next, an ammonia absorption refrigerator according to a second embodiment of the present invention will be described with reference to FIG. In the first embodiment, the magnitude of the refrigeration load is determined based on the opening degree of the fuel supply valve to the combustor provided in the heating regenerator of the regeneration unit. In the embodiment, the determination is made based on the valve opening of the expansion valve. In both embodiments,
The parts different from each other are the devices around the expansion valve. Therefore, in the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

That is, as shown in FIG. 2, a valve opening detector (state amount detecting means) 31 for detecting the valve opening (state amount) of the expansion valve 15 provided in the middle of the refrigerant liquid transfer pipe 16 is provided. At the same time, the valve opening detected by the valve opening detector 31 is input to the controller 32, and the continuation time when the valve opening is smaller than the set opening is similar to the first embodiment. The detected time is compared with the set time, and if the time exceeds the set time, 2
After about 3 seconds, the expansion valve 15 is fully opened, and the water remaining in the heat transfer pipe 1a and the first refrigerant vapor transfer pipe 11 is removed.

In the first embodiment, the fuel supply valve to the combustor is used to detect the magnitude of the refrigeration load on the refrigeration drive section (absorber, regeneration section, condenser, etc.). Is determined based on, for example, the temperature of a dilute ammonia aqueous solution having a low concentration at the outlet at the bottom of the rectifier or the outlet temperature of the fluid to be cooled in the evaporator. . For example, it is determined whether or not the state in which each of these temperatures exceeds a predetermined set temperature range continues.

In the second embodiment,
To detect the degree (large or small) of the refrigeration load on the evaporator side,
The determination is made based on the valve opening degree of the expansion valve. However, the setting temperature at the expansion valve (that is, the temperature at which the ammonia temperature in the evaporator becomes a predetermined temperature, for example, −30 ° C.) and the ammonia evaporator And the saturation pressure at the set temperature at the expansion valve (i.e., the temperature at which the ammonia temperature at the evaporator becomes a predetermined temperature, for example, -30C) and the evaporation at the evaporator. Based on the difference from the pressure, the determination may be made based on whether the gas flow rate of the ammonia vapor at the outlet of the evaporator is higher or lower than a predetermined set flow rate.

[0019]

As described above, according to each configuration of the present invention,
Depending on the refrigeration load in the absorption refrigerator, that is, when the refrigeration load is smaller than the set load, for example, the valve opening of the fuel supply valve in the regeneration unit or in the middle of the refrigerant liquid transfer pipe that supplies the refrigerant liquid to the evaporator. When the valve opening of the expansion valve provided at the valve is smaller than the set opening for a set time or longer, the controller temporarily opens the expansion valve widely to prevent ammonia from the condenser from being opened. The liquid is supplied into the heat transfer tube of the evaporator at one time. Therefore, the ammonia solution mixed with water accumulated in the heat transfer tube is vigorously blown out from the heat transfer tube to the ammonia vapor transfer tube side, so that at least the water accumulated in the heat transfer tube can be wiped out.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an ammonia absorption refrigerator according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an ammonia absorption refrigerator according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 1a Heat transfer tube 2 Absorber 3 Combustor 4 Regeneration part 4a Heating regenerator 4b Rectification tower 5 Condenser 11 1st refrigerant vapor transfer pipe 15 Expansion valve 15a Driving part 16 Refrigerant liquid transfer pipe 21 Fuel supply valve 21a Drive Part 22 Fuel supply pipe 23 Valve opening detector 24 Controller 31 Valve opening detector 32 Controller

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takashi Onishi 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Yukio Hiranaka 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2 Inside Osaka Gas Co., Ltd. (72) Noboru Tsubakihara, Inventor 4-1-2 Hiranocho, Chuo-ku, Osaka City, Osaka Prefecture Inside Osaka Gas Co., Ltd. (72) Masaharu Furuji 1, 1-chome, Minamikohoku, Suminoe-ku, Osaka-shi, Osaka No. 7-89 Hitachi Zosen Corporation (72) Inventor Yu Fujita 1-89 7-89 Minami Kohoku, Suminoe-ku, Osaka City, Osaka Prefecture (72) Inventor Mitsuru Matsuda Minami Kohoku, Suminoe-ku, Osaka City, Osaka Prefecture 1-7-89 Hitachi Zosen Corporation F-term (reference) 3L093 DD08 EE12 GG00 HH04 JJ02 KK03 LL05

Claims (3)

[Claims] 1. A direct expansion type evaporator for introducing and evaporating an ammonia solution into a heat transfer tube, an absorber for absorbing ammonia vapor into an absorption solution, and a regeneration device for heating and regenerating the absorption solution having absorbed ammonia vapor. Unit, a condenser for condensing the ammonia vapor heated and evaporated in the regeneration unit, and a refrigerant liquid transfer having an expansion valve on the way and for transferring the ammonia liquid obtained in the condenser to a heat transfer tube in the evaporator. A state quantity detecting means for detecting a state quantity in a refrigeration cycle in an ammonia absorption refrigerator having a pipe and a refrigerant vapor transfer pipe for transferring ammonia vapor evaporated by a heat transfer pipe in the evaporator to an absorber; ,
A control signal for inputting the detected state quantity from the state quantity detecting means and determining the magnitude of the refrigeration load based on the duration thereof, and for temporarily increasing the valve opening of the expansion valve when the refrigeration load is small. And a control means for outputting a temperature. 2. A valve opening detector for detecting a valve opening of a fuel supply valve to a combustor in a regenerating section is used as state quantity detecting means, and the valve opening is inputted by a control means. The valve opening is compared with the set opening, and if the valve opening smaller than the set opening continues for a set time or longer, a control signal for temporarily increasing the valve opening of the expansion valve is output. The ammonia absorption refrigerator according to claim 1, wherein the refrigerator is configured as described above. 3. A valve opening detector for detecting a valve opening of an expansion valve provided in the middle of a refrigerant liquid transfer pipe is used as state quantity detecting means, and the valve opening is inputted by a control means. Then, the valve opening is compared with the set opening, and when the valve opening smaller than the set opening continues for a set time, a control signal for temporarily increasing the valve opening of the expansion valve is output. The ammonia absorption refrigerator according to claim 1, wherein the refrigerator is configured as described above.