CN110793246A

CN110793246A - Hot gas defrosting system and hot gas defrosting method

Info

Publication number: CN110793246A
Application number: CN201911203698.6A
Authority: CN
Inventors: 杨红波; 龚千; 曾庆龙
Original assignee: GUANGZHOU BINGQUAN REFRIGERATION EQUIPMENT Co Ltd
Current assignee: GUANGZHOU BINGQUAN REFRIGERATION EQUIPMENT Co Ltd
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2020-02-14

Abstract

The invention discloses a hot gas defrosting system and a hot gas defrosting method, wherein a pilot-operated control valve has a certain pressure reduction effect on hot gas, so that the overhigh pressure of the hot gas is avoided; and moreover, the return pipe is arranged, so that products formed after heat release and defrosting of hot gas flow away from the return pipe or the return branch pipe respectively at different defrosting stages, and the influence on other evaporation devices is reduced. The system pressure fluctuation caused by defrosting is reduced by controlling a plurality of system pressures, so that the influence on the refrigerating capacity of the system is avoided; can defrost each evaporation device independently without causing great influence on other evaporation devices, avoid causing great temperature fluctuation of the cold storage, and be beneficial to the refrigeration of food.

Description

Hot gas defrosting system and hot gas defrosting method

Technical Field

The invention relates to the field of refrigeration systems, in particular to a hot gas defrosting system and a hot gas defrosting method.

Background

The existing defrosting technologies generally comprise manual defrosting, electric heating defrosting, water defrosting and hot air defrosting. The manual frost sweeping is to sweep the frost on the air cooler or the calandria by taking a special broom by people, the electric heating defrosting is generally used on the air cooler, and the defrosting purpose is achieved by heating the heating wire on the air cooler fin and the heating wire of the water pan. If the heating wire is required to be defrosted, the other air coolers are refrigerating, so the heating wire is generally required to have higher power and consume more energy. The water defrosting is generally applied to an air cooler, a spraying device is arranged on the air cooler, and a water pipe is connected to the outside of the air cooler to introduce water to melt the frost. The hot air defrosting is to utilize the high-pressure high-temperature gas of the system exhaust pipe to defrost. Among them, hot air defrosting is the most commonly used method.

The heat supply amount for hot gas defrosting is large, but because the traditional hot gas defrosting system supplies heat from the exhaust pipe and enters the air cooler for defrosting, the air returns to the low-pressure system from the return air pipe directly after defrosting, and the pressure of the low-pressure system is increased; if the ice is removed separately, other normally refrigerated air coolers can be affected, so the hot gas defrosting system is generally used for defrosting simultaneously or is used for a small system more frequently. Because the defrosting simultaneously, all air-coolers stop, then the defrosting is unified, because thermal entering can produce the influence to whole storehouse to lead to the storehouse temperature to rise, influence cold-stored effect.

Disclosure of Invention

In view of the above, the present invention is directed to at least solve one of the above problems to a certain extent, so on one hand, a hot gas defrosting system is provided to solve the problem that defrosting of a single air cooler affects the cooling effect of other air coolers; on the other hand, a hot gas defrosting method is provided, which can solve the problem that the pressure of a low-pressure system is increased because hot gas returns to the low-pressure system from a return pipe directly after defrosting.

The technical scheme of the invention on one hand is realized as follows:

a hot gas defrosting system comprises a plurality of evaporation devices which are used in parallel, and the system comprises a liquid supply main pipe and a gas return main pipe, wherein a plurality of liquid supply branch pipes are branched from the liquid supply main pipe and connected with the plurality of evaporation devices; each evaporation device is connected with an air return branch pipe, and all the air return branch pipes converge to the air return main pipe; a liquid supply electromagnetic valve and a first check valve are arranged on the liquid supply branch pipe; the air return branch pipe is provided with a normally open pneumatic electromagnetic valve, and the pneumatic electromagnetic valve is connected in parallel with a bypass electromagnetic valve of which the drift diameter is smaller than that of the pneumatic electromagnetic valve;

the system also comprises a hot gas main pipe, wherein a pilot control valve is arranged on the hot gas main pipe, a plurality of hot gas branch pipes corresponding to the plurality of air return branch pipes are branched from the hot gas main pipe, one end of each hot gas branch pipe is connected to the hot gas main pipe, the other end of each hot gas branch pipe is connected to the air return branch pipe between the pneumatic electromagnetic valve and the evaporation device, and a hot gas electromagnetic valve and a second check valve are arranged on each hot gas branch pipe; a control pipe is branched from the hot gas branch pipe and connected to the pneumatic electromagnetic valve, and an electromagnetic control valve is arranged on the control pipe; the device comprises a return pipe, one end of the return pipe is connected to an air return branch pipe behind the pneumatic solenoid valve, the other end of the return pipe is connected to a liquid supply branch pipe between the first check valve and the evaporation device, and an overflow valve is arranged on the return pipe.

As a further alternative of the hot gas defrosting system, the liquid supply branch pipe is also provided with a first service valve, a first filter and a manual regulating valve.

As a further alternative of the hot gas defrosting system, a stop valve is arranged on the hot gas branch pipe, and hot gas on the hot gas main pipe passes through the stop valve and then enters the control pipe.

As a further alternative of the hot gas defrosting system, a second service valve and a second filter are provided on the control pipe.

As a further alternative of the hot gas defrosting system, a liquid supply main pipe and an air return main pipe of the system are connected with a low-pressure circulating barrel, the low-pressure circulating barrel is sequentially connected with a compressor, an oil separator, a condenser and a liquid storage device through pipelines, and the liquid storage device is connected with the low-pressure circulating barrel to form circulation; the oil separator conveys hot gas obtained from the compressor to the condenser and the hot gas main pipe respectively.

The hot gas defrosting system has the beneficial effects that: the pilot control valve has a certain pressure reduction effect on hot gas, so that the overhigh pressure of the hot gas is avoided; and moreover, the return pipe is arranged, so that products formed after heat release and defrosting of hot gas flow away from the return pipe or the return branch pipe respectively at different defrosting stages, and the influence on other evaporation devices is reduced.

The technical scheme of the other aspect of the invention is realized as follows:

a hot gas defrosting method is applied to any one of the hot gas defrosting systems, and the evaporation device needing defrosting is operated according to the following steps:

step 1), closing the liquid supply electromagnetic valve, and enabling the evaporation device to continue to operate so as to evacuate refrigerants in the evaporation device;

step 2), opening the pilot-operated control valve, the hot gas electromagnetic valve and the electromagnetic control valve, introducing part of hot gas into the control pipe to close the pneumatic electromagnetic valve, and defrosting the evaporation device by part of hot gas; the defrosted hot gas flows back to the main return pipe from the return pipe, so that the overflow valve controls the pressure of the evaporation device;

step 3), when the evaporation device reaches the set temperature, closing the pilot-operated control valve, the hot gas electromagnetic valve and the electromagnetic control valve, keeping the closing state of the liquid supply electromagnetic valve and the pneumatic electromagnetic valve, and opening the bypass electromagnetic valve; releasing the pressure in the evaporation device through the bypass electromagnetic valve until the pressure in the evaporation device is reduced to be within the pressure range of a low-pressure system;

and 4) finishing defrosting.

As a further alternative of the hot gas defrosting method, after defrosting is completed, the liquid supply electromagnetic valve and the pneumatic electromagnetic valve are opened again, and the bypass electromagnetic valve is closed, so that the evaporation device continues to refrigerate.

As a further alternative of the hot gas defrosting method, in the step 1), the evaporation device is operated for 120-600 seconds.

As a further alternative of the hot gas defrosting method, in the step 3), a liquid supply main pipe and a gas return main pipe of the system are connected to a low-pressure circulating barrel, when the pressure difference between the pressure in the evaporation device and the pressure in the low-pressure circulating barrel is lower than 1.25bar, the liquid supply electromagnetic valve and the pneumatic electromagnetic valve are opened again, the bypass electromagnetic valve is closed, and the evaporation device continues to refrigerate.

The hot gas defrosting method has the beneficial effects that: the system pressure fluctuation caused by defrosting is reduced by controlling a plurality of system pressures, so that the influence on the refrigerating capacity of the system is avoided; can defrost each evaporation device independently without causing great influence on other evaporation devices, avoid causing great temperature fluctuation of the cold storage, and be beneficial to the refrigeration of food.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic view of the overall structure of a hot gas defrosting system according to the present invention;

FIG. 2 is a schematic view of a cooling operation of the hot gas defrost system;

FIG. 3 is one of the schematic diagrams illustrating the defrosting operation of the hot gas defrosting system;

fig. 4 is a second schematic view illustrating the defrosting operation of the hot gas defrosting system.

In the figure: 10. an evaporation device; 20. a main liquid supply pipe; 21. a branch liquid supply pipe; 211. a first service valve; 212. a first filter; 213. a liquid supply solenoid valve; 214. a first check valve; 215. a manual regulating valve; 30. a main air return pipe; 31. a return air branch pipe; 311. a pneumatic solenoid valve; 312. a bypass solenoid valve; 32. a return pipe; 321. an overflow valve; 40. a hot gas main pipe; 41. a hot gas manifold; 411. a stop valve; 412. a hot gas solenoid valve; 413. a second check valve; 42. a control tube; 421. a second service valve; 422. a second filter; 423. an electromagnetic control valve; 43. a pilot operated control valve; 50. a low pressure recycle bin; 60. a compressor; 70. an oil separator; 80. a condenser; 90. a reservoir.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Referring to fig. 1-4, a hot gas defrosting system is shown, which comprises a plurality of evaporation devices 10 used in parallel, the system comprises a main liquid supply pipe 20 and a main return pipe 30, a plurality of branch liquid supply pipes 21 are branched from the main liquid supply pipe 20 and connected with the plurality of evaporation devices 10; each evaporation device 10 is connected with an air return branch pipe 31, and all the air return branch pipes 31 converge on the air return main pipe 30; a liquid supply electromagnetic valve 213 and a first check valve 214 are arranged on the liquid supply branch pipe 21; a normally open pneumatic electromagnetic valve 311 is arranged on the air return branch pipe 31, and a bypass electromagnetic valve 312 with a drift diameter smaller than that of the pneumatic electromagnetic valve 311 is connected in parallel on the pneumatic electromagnetic valve 311;

the system also comprises a hot gas main pipe 40, wherein a pilot control valve 43 is arranged on the hot gas main pipe 40, a plurality of hot gas branch pipes 41 corresponding to the plurality of air return branch pipes 31 are branched from the hot gas main pipe 40, one end of each hot gas branch pipe 41 is connected to the hot gas main pipe 40, the other end of each hot gas branch pipe 41 is connected to the air return branch pipe 31 between the pneumatic electromagnetic valve 311 and the evaporation device 10, and a hot gas electromagnetic valve 412 and a second check valve 413 are arranged on each hot gas branch pipe 41; a control pipe 42 is branched from the hot gas branch pipe 41 and connected to the pneumatic solenoid valve 311, and an electromagnetic control valve 423 is arranged on the control pipe 42; the return pipe 32 is provided with one end connected to the return branch pipe 31 behind the pneumatic solenoid valve 311, the other end connected to the liquid supply branch pipe 21 between the first check valve 214 and the evaporation device 10, and the return pipe 32 is provided with an overflow valve 321.

In the above solution, a relatively conventional system for providing a refrigerant may be used, and referring to fig. 1, a main liquid supply pipe 20 and a main gas return pipe 30 of the system are connected to a low-pressure circulation barrel 50, the low-pressure circulation barrel 50 is sequentially connected to a compressor 60, an oil separator 70, a condenser 80 and a reservoir 90 through pipes, and the reservoir 90 is connected to the low-pressure circulation barrel 50 again to form a circulation; the oil separator 70 delivers hot gas obtained from the compressor 60 to the condenser 80 and the hot gas main 40, respectively.

In practical applications, the evaporation device 10 in the refrigerator is generally an air cooler, so the working principle of the hot gas defrosting system will be described below by using the air cooler.

In the above solution, in order to facilitate functions of maintenance and refrigerant filtration, the liquid supply branch pipe 21 is further provided with a first maintenance valve 211, a first filter 212 and a manual regulating valve 215; a second maintenance valve 421 and a second filter 422 are arranged on the control pipe 42; the first service valve 211 and the second service valve 421 are ball valves. For convenience of control and safety assurance, the hot gas branch pipe 41 is provided with a stop valve 411, and hot gas on the hot gas main pipe 40 passes through the stop valve 411 and then enters the control pipe 42. In addition, the pilot type control valve 43 is composed of a main valve and a pilot valve.

Generally, the low-pressure circulation barrel 50 in the hot gas defrosting system provides refrigerant for the air coolers used in parallel, and the refrigerant is evaporated and gasified in the air coolers and then returns to the low-pressure circulation barrel 50; in an initial state, the air cooler is in a cooling mode, referring to fig. 2, the refrigerant in the low-pressure circulation barrel 50 enters the liquid supply main pipe 20 and then enters the liquid supply branch pipe 21, and after the refrigerant is evaporated and gasified in the air cooler, the refrigerant enters the air return branch pipe 31 and then enters the air return main pipe 30, and finally returns to the low-pressure circulation barrel 50. In the above process, the pilot control valve 43 is closed, the hot air electromagnetic valve 412 is closed, and the electromagnetic control valve 423 is closed, so that hot air does not enter the air cooler for defrosting; while the liquid supply solenoid valve 213 is open, the pneumatic solenoid valve 311 is open, and the bypass solenoid valve 312 is closed, the refrigerant flows through the pneumatic solenoid valve 311 in the return branch 31.

After the air coolers are used for a period of time, some of the air coolers need to be defrosted, and the defrosting method is operated according to the following steps:

step 1), closing the liquid supply electromagnetic valve 213 corresponding to the air cooler needing defrosting, and continuously operating the evaporation device 10 to evacuate the refrigerant in the air cooler;

in the step, the continuous supply of the refrigerant to the air cooler needing defrosting is stopped, namely the air cooler is withdrawn from the refrigeration mode, and the refrigerant in the air cooler is consumed; the refrigeration effect is prevented from being reduced due to the fact that the refrigerant absorbs part of heat of hot gas when the hot gas is defrosted.

Step 2), opening the pilot control valve 43, the hot gas electromagnetic valve 412 and the electromagnetic control valve 423, introducing part of hot gas into the control pipe 42 to close the pneumatic electromagnetic valve 311, and defrosting the evaporation device 10 by part of hot gas;

referring to fig. 3, after the pilot-operated control valve 43, the hot air solenoid valve 412 and the electromagnetic control valve 423 are opened, hot air enters the hot air main pipe 40 and enters the hot air branch pipe 41 corresponding to the air cooler to be defrosted; and part of hot gas is separated to enter the control pipe 42, because the pneumatic electromagnetic valve 311 connected with the control pipe 42 is a normally open type electromagnetic valve, after the hot gas is introduced, the pneumatic electromagnetic valve 311 is closed, the air return branch pipe 31 is disconnected, and the system is protected from the impact of the hot gas during defrosting; the hot air in the hot air branch pipe 41 enters the air cooler to release heat and condense, and the first check valve 214 is arranged in the liquid supply branch pipe 21, so the hot air can only flow away through the return pipe 32 after releasing heat and condensing, the return pipe 32 is provided with the overflow valve 321, the overflow valve 321 can be opened when the pressure in the air cooler reaches a certain value, on one hand, the hot air can be ensured to have sufficient heat exchange time in the air cooler, on the other hand, the throttle valve has a certain throttling function, and as the liquid temperature and the pressure formed by the condensation of the hot air during defrosting are higher, if the hot air is directly discharged into the low-pressure circulating barrel 50 from the air return branch pipe 31 without throttling and controlling, the temperature fluctuation of the low-pressure circulating barrel 50 can.

Step 3), when the air cooler reaches the set temperature, closing the pilot control valve 43, the hot gas electromagnetic valve 412 and the electromagnetic control valve 423, keeping the closing state of the liquid supply electromagnetic valve 213 and the pneumatic electromagnetic valve 311, and opening the bypass electromagnetic valve 312; releasing the pressure in the evaporator 10 through the bypass solenoid valve 312 until the pressure in the evaporator 10 is reduced to a pressure range of a low pressure system;

referring to fig. 4, after step 2), if the air cooler reaches a certain temperature, it represents that the frost has been melted; however, although the frost is completely melted into water, the frost cannot be completely exited from the defrosting mode to enter the cooling mode, on one hand, the water melted by the frost is easily condensed into the frost again, on the other hand, if the pneumatic solenoid valve 311 is directly opened, the pressure difference between the air cooler and the low-pressure circulation barrel 50 is large, the high-pressure and high-temperature liquid formed by condensing the hot gas enters the air return branch pipe 31 through the pneumatic solenoid valve 311 and enters the low-pressure circulation barrel 50, when a large amount of liquid enters the low-pressure circulation barrel 50, the balance between the liquid supply and the air suction in the low-pressure circulation barrel 50 is broken, and the liquid suddenly increases, so that the liquid is brought back to the compressor 60.

Therefore, the pilot control valve 43, the hot air solenoid valve 412 and the electromagnetic control valve 423 are closed first, hot air is not supplied to the cold air blower, the electromagnetic control valve 423 is closed at the same time, the air pressure in the pneumatic solenoid valve 311 is maintained for a period of time, and the pneumatic solenoid valve 311 is still closed; the bypass electromagnetic valve 312 is opened, the compressor 60 pumps air through the bypass electromagnetic valve 312, the liquid condensed from the hot gas is gradually evaporated into gas in the air cooler and pumped away, and the pressure in the air cooler is gradually reduced and approaches to the pressure of the low-pressure circulating barrel 50; in this process, since the pressure in the air cooler does not reach the threshold of the overflow valve 321, the air does not flow away from the return pipe 32; in addition, the bypass solenoid valve 312 has a smaller diameter than the pneumatic solenoid valve 311, so that the pressure in the air cooler is slowly reduced, and the low-pressure system is not greatly affected.

And 4) finishing defrosting.

In the step, the pressure of the cold air blower in the step 3) is close to the pressure of the low-pressure circulating barrel 50, and the defrosting process is finished completely to finish defrosting; in general, after the defrosting operation is finished, the air cooler should be put into cooling operation again, so the liquid supply solenoid valve 213 and the pneumatic solenoid valve 311 are opened again, the bypass solenoid valve 312 is closed, and the air cooler continues to cool as shown in fig. 2.

Specifically, in the step 1), the air cooler is allowed to continue to operate for 120-600 seconds after the supply of the refrigerant is stopped according to the size of the evaporator in the air cooler;

specifically, in the step 3), when the pressure difference between the pressure in the air cooler and the pressure in the low-pressure circulation barrel 50 is less than 1.25 bar. Thus, the pressure in the defrosted air cooler does not have a great influence on the low-pressure circulating barrel 50, and the hot air is not diffused to other air coolers connected in parallel through the return main pipe 30 due to the excessive pressure.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A hot gas defrosting system, which comprises a plurality of evaporation devices used in parallel, is characterized in that,

the system comprises a liquid supply main pipe and an air return main pipe, wherein a plurality of liquid supply branch pipes are branched from the liquid supply main pipe and connected with a plurality of evaporation devices; each evaporation device is connected with an air return branch pipe, and all the air return branch pipes converge to the air return main pipe; a liquid supply electromagnetic valve and a first check valve are arranged on the liquid supply branch pipe; the air return branch pipe is provided with a normally open pneumatic electromagnetic valve, and the pneumatic electromagnetic valve is connected in parallel with a bypass electromagnetic valve of which the drift diameter is smaller than that of the pneumatic electromagnetic valve;

2. The hot gas defrosting system of claim 1 wherein the liquid supply manifold further comprises a first service valve, a first filter and a manual control valve.

3. The hot gas defrosting system of claim 1 wherein the hot gas branch pipe is provided with a stop valve, and hot gas in the hot gas main pipe passes through the stop valve and then enters the control pipe.

4. The hot gas defrosting system of claim 3 wherein the control tube is provided with a second service valve and a second filter.

5. The hot gas defrosting system according to any one of claims 1 to 4, wherein the main liquid supply pipe and the main gas return pipe of the system are connected to a low-pressure circulating barrel, the low-pressure circulating barrel is sequentially connected with a compressor, an oil separator, a condenser and an accumulator through pipelines, and the accumulator is connected with the low-pressure circulating barrel to form a circulation; the oil separator conveys hot gas obtained from the compressor to the condenser and the hot gas main pipe respectively.

6. A hot gas defrosting method of a hot gas defrosting system according to any one of claims 1 to 5, characterized in that the evaporation means to be defrosted is operated by the following steps:

and 4) finishing defrosting.

7. The hot gas defrosting method of claim 6 wherein after defrosting is completed, the liquid supply solenoid valve and the pneumatic solenoid valve are opened again, and the bypass solenoid valve is closed to continue cooling the evaporation device.

8. The hot gas defrosting method according to claim 6, wherein in the step 1), the evaporation device is operated for another 600 seconds.

9. The hot gas defrosting method according to claim 6 or 7, wherein in the step 3), the main liquid supply pipe and the main gas return pipe of the system are connected to a low-pressure circulating barrel, when the pressure difference between the pressure in the evaporation device and the pressure in the low-pressure circulating barrel is lower than 1.25bar, the main liquid supply valve and the pneumatic solenoid valve are opened again, the bypass solenoid valve is closed, and the evaporation device continues to refrigerate.