CN101029783A - Sodium sulfocyanate-ammonia diffusion absorbing refrigerator - Google Patents

Abstract

A sodium thiocyanate-ammonia diffusion absorption refrigeration device belongs to the refrigeration technology industry and is applied to fishing boats, cold storages, refrigerated trucks and all occasions requiring refrigeration. Some of the existing devices can only produce temperatures above zero degrees, and the scope of use is limited; some require rectification devices, and the cooling capacity is generally small, so it is difficult to be used in occasions that require a large cooling capacity. The present invention includes generator (1), condenser (3), absorber (5), evaporator (7), pump (8) and solution heat exchanger (9), which are interconnected to form a complete circulation loop. Wherein the solution is separated in the gas-liquid separator (2), heated in the liquid heat exchanger (9), the bottom of the diffusion tank (6) forms a closed loop through the pump (8) and the evaporator (7), and the diffusion tank (6) ) are communicated with the upper and lower ends of the absorber (5) respectively, so that the ammonia solution can absorb and discharge ammonia smoothly under the diffusion of hydrogen. The whole device has a compact structure, can meet the demands of different cooling capacities, and has good application prospects.

Description

Sodium Thiocyanate-Ammonia Diffusion Absorption Refrigeration Plant

Technical field:

It belongs to the refrigeration technology industry and is used in ocean-going fishing boats, cargo ships and all occasions that require refrigeration. It can be used in fishing boat ice machines, car air conditioners, cold stores, refrigerated trucks and military.

Background technique:

Artificial refrigeration was born more than 100 years ago, thermal energy refrigeration is mainly absorption refrigeration. At present, there are three common absorption refrigeration methods: lithium bromide water absorption type, ammonia water absorption type, and ammonia hydrogen water absorption and diffusion type.

Lithium bromide absorption refrigeration system is one of the most studied ones, but because it can only produce temperatures above zero, the scope of use is often limited to air conditioners, and it is highly corrosive.

Ammonia water absorption refrigeration is the originator of artificial refrigeration. In the field of artificial refrigeration, there is ammonia water absorption refrigeration before compression refrigeration. However, since the working medium of this system is water and ammonia, the water evaporates during heating, and the ammonia also evaporates, reducing the Thermal efficiency requires a rectification device at the same time, which increases equipment investment and energy consumption, and also limits the improvement of refrigeration efficiency. In addition, it also needs a booster pump, which consumes a lot of power, so it is not suitable for the current situation of energy saving and refrigeration.

Ammonia-hydrogen water diffusion absorption refrigeration adds diffusing agent-hydrogen on the basis of the ammonia water system. Its basic flow is shown in Figure 2. The concentrated solution entering the generator 1 is heated, and the gaseous state enters the rectifier 10, and the liquid state Return to generator 1. The gaseous ammonia coming out of the rectifier 10 is condensed by the condenser 3 , cooled again by the gas heat exchanger 11 , and enters the evaporator 7 . In the evaporator 7, due to the influence of hydrogen, rapid evaporation and refrigeration of ammonia are facilitated. The ammonia-hydrogen-water mixed gas from the evaporator 7 enters the absorber 5 after being heated by the gas heat exchanger 11 . The dilute solution coming out of the generator 1 also enters the absorber 5 after being cooled by the solution heat exchanger 9, and after the dilute ammonia solution absorbs ammonia gas in the absorber 5, after being preheated by the solution heat exchanger 9, it flows into the generator 1 again. . This constitutes a cycle. The working fluid of this system still uses ammonia and water, so a rectification device must be installed. At the same time, due to the use of a siphon pump for circulation, the cooling capacity is generally small, and the cooling efficiency (COP) is generally 0.4 to 0.5, which is difficult to meet the cooling capacity demand. big occasion.

Invention content:

The purpose of this invention is to provide a kind of novel diffusion-absorption refrigeration device, and it uses sodium thiocyanate-ammonia as refrigeration working medium pair, can produce the temperature below zero and save rectifying device simultaneously, it has lower The temperature of the heat source can meet the requirements of the drive system and achieve a high cooling efficiency (COP). In addition to being used in air-conditioning systems, it can also be used in cold storage and ice-making equipment. get applied. For places with geothermal sources and waste heat sources, the heat can be directly used to achieve the purpose of refrigeration.

Sodium thiocyanate-ammonia solution has high solubility, low vapor pressure, high thermal conductivity, low viscosity and specific heat, and has no corrosion to steel, so it is an ideal absorption refrigerant pair. Sodium thiocyanate-ammonia is used in the diffusion absorption refrigeration system. Since the boiling points of ammonia and sodium thiocyanate differ greatly, the gas phase of the solution can be considered to be 100% ammonia, and the rectification device can be dispensed with. Moreover, theoretical analysis shows that the performance of the sodium thiocyanate-ammonia diffusion absorption system is better than that of the traditional ammonia-hydrogen water system.

The sodium thiocyanate-ammonia diffusion-absorption refrigeration device includes a generator 1, a condenser 3, an absorber 5, an evaporator 7, a pump 8 and a solution heat exchanger 9, as shown in Figure 1, one end of the generator 1 is connected to the gas-liquid The separator 2 is connected, the other end of the generator 1 is connected to the solution heat exchanger 9, the top of the gas-liquid separator 2 is connected to the diffusion tank 6 through the condenser 3, and the bottom of the gas-liquid separator 2 is connected to the pump 8 through the solution heat exchanger 9 , the bottom of the diffusion tank 6 forms a closed loop through the pump 8 and the evaporator 7, and the upper and lower ends of the diffusion tank 6 communicate with the absorber 5 respectively, one end of the absorber 5 forms a circulating loop with the cooler 4, and the absorber 5 simultaneously Connect with solution heat exchanger 9 through pump 8.

The process flow of this device is: after being heated and boiled in the generator 1, the concentrated ammonia solution with a large amount of ammonia gas is separated in the gas-liquid separator 2, wherein a large amount of ammonia gas evaporates and enters the condenser 3 to condense, and the concentrated ammonia solution after separation The ammonia solution becomes dilute ammonia solution and flows out from the bottom of the gas-liquid separator 2, and is mixed with the concentrated ammonia solution coming from the bottom of the absorber 5 through the solution heat exchanger 9. The mixed solution is divided into two parts after passing through the magnetic pump 8: one part is condensed by the cooler 4 and then sent to the absorber 5, where it absorbs ammonia gas after being sprayed and atomized to become a concentrated ammonia solution; the other part passes through the solution heater 9 re-enters generator 1 after being heated;

The ammonia evaporated from the gas-liquid separator 2 becomes ammonia liquid after being condensed by the condenser 3. The ammonia liquid enters the top of the diffusion tank 6 and is sprayed down. A part of it is diffused under the action of hydrogen, and the other part of the ammonia liquid is not diffused. It enters the evaporator 7 through the solution pump 8 for heat exchange, and then is sent back to the diffusion tank 6 for spraying and diffusion. Absorbed the hydrogen of a large amount of ammonia like this and just becomes hydrogen-ammonia mixed gas, then hydrogen-ammonia mixed gas enters absorber 5 and flows up and exchanges with the dilute ammonia solution that sprays down. Ammonia is absorbed by the dilute ammonia solution, and the hydrogen ammonia solution becomes hydrogen and returns to the diffusion tank 6 to absorb ammonia. In this way, the system completes a cycle.

Compared with the current lithium bromide, ammonia hydrogen water and ammonia water refrigeration systems, the advantages of this system are as follows:

(1) Since only the refrigerant ammonia evaporates in the evaporation stage, the thiocyanate does not evaporate to improve the refrigeration efficiency (COP).

(2) A lower heat source temperature can meet the requirements of the drive system. Generally, the heat source temperature is 90-110°C. In this case, the evaporation (refrigeration) temperature can reach -30°C.

(3) Compared with similar devices, the cooling efficiency (COP) can reach up to 0.7, which is a big step in the "energy saving" advocated today.

(4) In this system, the pump 8 adopts a magnetic pump, which greatly reduces the energy consumption of the auxiliary delivery pump and expands the refrigeration capacity of the system. It is suitable for various large, medium and small refrigeration system applications.

Description of drawings

Fig. 1 overall flowchart of sodium thiocyanate-ammonia diffusion absorption refrigeration system;

In the figure 1. Generator, 2. Gas-liquid separator, 3. Condenser, 4. Cooler, 5. Absorber, 6. Diffusion tank, 7. Evaporator, 8. Pump, 9. Solution heat exchanger;

Fig. 2 flow chart of ammonia hydrogen water diffusion absorption refrigeration system;

In the figure 1. Generator, 3. Condenser, 5. Absorber, 7. Evaporator, 9. Solution heat exchanger, 10. Rectifier, 11. Heat exchanger.

Detailed ways:

In the device of the present invention, after the concentrated ammonia solution is heated and boiled by the generator 1, it is separated in the gas-liquid separator 2, wherein a large amount of ammonia evaporates and enters the condenser 3 to condense, and the separated concentrated ammonia solution becomes a dilute ammonia solution Flow out from the bottom of the gas-liquid separator 2, pass through the solution heat exchanger 9 and mix with the concentrated ammonia solution coming from the bottom of the absorber 5. The mixed solution is divided into two parts after passing through the magnetic pump 8: one part is condensed by the cooler 4 and then sent to the absorber 5, where it absorbs ammonia gas after being sprayed and atomized to become a concentrated ammonia solution; the other part passes through the solution heater 9 re-enters generator 1 after being heated.

The ammonia evaporated from the gas-liquid separator 2 becomes ammonia liquid after being condensed by the condenser 3. The ammonia liquid enters the top of the diffusion tank 6 and is sprayed down. A part of it is diffused under the action of hydrogen, and the other part of the ammonia liquid is not diffused. It enters the evaporator 7 through the solution pump 8 for heat exchange, and then is sent back to the diffusion tank 6 for spraying and diffusion. Absorbed the hydrogen of a large amount of ammonia like this and just become hydrogen-ammonia mixed gas, then hydrogen-ammonia mixed gas enters absorber 5 and flows up and exchanges with the dilute ammonia solution that sprays down. Ammonia is absorbed by the dilute ammonia solution, and the hydrogen ammonia solution becomes hydrogen and returns to the diffusion tank 6 to absorb ammonia. In this way, the system completes a cycle.

In the present invention, the diffusion tank 6 is added between the evaporator 7 and the absorber 5. Here, the diffusion tank has three functions: 1) provide enough ammonia liquid for the solution pump to allow the system to run well; 2) The function of storing ammonia liquid; 3) Provide a good place for the diffusion of ammonia. From the perspective of heat transfer, what the refrigerant takes away in the evaporator 7 is the sensible heat of the ammonia liquid, while in the diffusion tank 6, a part of the ammonia diffuses in it, and its latent heat is transferred to the ammonia liquid in the lower part of the diffusion tank 6 , and then the cooled ammonia liquid exchanges heat with the refrigerant in the form of sensible heat.

In the present invention, the generator 1 is connected with the solution heat exchanger 9 and the gas-liquid separator 2 respectively. This design allows the concentrated ammonia solution to be heated in the solution heat exchanger 9 and separated in the gas-liquid separator 2, and the heating and separation are carried out in two containers. Its benefit is that ammonia absorbs heat while evaporating. , The source of these heats is an external heat source, but in order to increase the absorption capacity of the sodium thiocyanate solution, it is necessary to reduce the temperature of the sodium thiocyanate solution coming out from the solution heat exchanger 9 as much as possible. Carrying out heating and separation in two containers has solved this problem very well. While the ammonia gas is evaporating, it absorbs the heat of the solution and reduces the temperature of the sodium thiocyanate solution, thereby improving the refrigeration efficiency (COP).

Claims (2)

1. A sodium thiocyanate-ammonia diffusion-absorption refrigeration device, comprising a generator (1), a condenser (3), an absorber (5), an evaporator (7), a pump (8) and a solution heat exchanger (9), characterized in that: one end of the generator (1) is connected to the gas-liquid separator (2), the other end of the generator (1) is connected to the solution heat exchanger (9), and the top of the gas-liquid separator (2) passes through The condenser (3) is connected to the diffusion tank (6), the bottom of the gas-liquid separator (2) is connected to the pump (8) through the solution heat exchanger (9), and the bottom of the diffusion tank (6) is connected to the evaporator through the pump (8) (7) form a closed loop, and the diffusion tank (6) communicates with the upper and lower ends of the absorber (5) respectively, one end of the absorber (5) forms a loop with the cooler (4), and the absorber (5) simultaneously It is connected with the solution heat exchanger (9) through the pump (8) again. 2. The refrigeration device according to claim 1, characterized in that the pump (8) is a magnetic pump.

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