JPS59122871A - Method of preventing crystallization of absorption refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing crystallization of a solution in an absorption refrigerator. In this specification, "
The term "absorption refrigerator" also includes a so-called heat pump in a narrow sense, which pumps up heat from a low-temperature section and supplies it to a high-temperature section.

In an absorption refrigerator, for example, if the cooling water temperature changes unexpectedly, or if the condensation temperature changes significantly, there is a risk that the solution will crystallize.

To give an example of a large change in cooling water temperature, when used as a heat pump in the narrow sense, the cooling water temperature at startup is significantly different from the cooling water temperature during steady operation. For this reason, even if the same heat source temperature, for example the same steam temperature, is used, the amount of heat transfer in the generator will be significantly different, and at startup, a large amount of refrigerant will be released from the generator, and the solution at the generator outlet will have a very high concentration of crystals. There is a danger.

For example, in the example shown in Figure 1, in a LiBr-820 absorption heat pump designed with a condensation temperature of 80°C and a generator outlet solution temperature of about 140°C, the cycle A is shown in steady operation, and the generator outlet solution temperature is about 140°C. balances at a concentration of 63%. Even after startup, the chilled water temperature remains low for a while (especially when a heat storage tank is used or when there is a large amount of cooled water, i.e. hot water, it takes a long time), and the condensing temperature rises only to about 40℃. If not, when the heat source is the same and the steam pressure is constant, if the generator outlet temperature becomes 120°C or higher,
The cycle is as shown in B, and the solution concentration at the generator outlet is 7.
It exceeds 0% and reaches about 73%, reaching the crystal line K and crystallizing before returning to the absorber.

To give an example of a large change in condensing temperature, if the cooling water system is dirty and a large amount of scale is expected to adhere, the refrigerator is designed to produce the specified capacity even with scale attached. . In such cases, there is a large change in condensing temperature before and after scale adhesion, and at the beginning of installation or immediately after scale removal, the condensing temperature is low and a large amount of refrigerant is generated, increasing the solution concentration and causing the risk of crystal formation.

Also, if the temperature of the heating source for the generator changes drastically,
During intense heating, a large amount of refrigerant is generated, which increases the concentration of the solution and poses a danger of crystal formation.

The present invention eliminates the above-mentioned drawbacks of the conventional method, and
The object of the present invention is to provide a method for preventing crystallization in an absorption refrigerator, which can prevent a solution from being overconcentrated due to overload at the time of installation, and can eliminate the risk of crystallization.

The present invention provides a heat source heat amount control valve that has an absorber, a generator, a condenser, an evaporator solution heat exchanger, and a solution path and a refrigerant path that connect these devices, and that controls the heat source heat amount for heating in the generator. In a method for preventing crystallization in an absorption refrigerator having
A method for preventing crystallization in an absorption refrigerator, characterized in that the concentration of the solution at the generator outlet is detected directly or indirectly, and when the detected value exceeds a set value, the opening degree of the heat source heat amount control valve is limited. be.

An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, an absorber A, a generator G, a condenser C2, an evaporator E, a solution heat exchanger It is equipped with pipe 1.2.3.4.5, spray pipe 6, and over pipe 7 as a solution path, and pipe 8.9, spray pipe 10, and pipe 11 as a refrigerant path to connect the above-mentioned equipment. to form a refrigeration cycle.

12 is a heating tube, and 13 is a heat source heat amount control valve.

The cooling water system includes a cooling water pump 14, piping 15, cooling water pipe 16, piping 17, cooling water pipe 18, and piping 19, and is configured to cool the absorber A and the condenser C. There is also a method of cooling with air instead of cooling water. In this case, a cooling fan is used instead of the cooling water pump 14. 20
is a cold water pipe which leads cold water to the evaporator E through pipes 21 and 22.

23 is a temperature detector that detects the cold water outlet temperature, 24 is a temperature detector that detects the outlet temperature of the cooling water of the condenser C, and 26 is a temperature detector ζ 25 that detects the condensation temperature in the condenser C.
is a controller that operates the heat source heat amount control valve 13 in response to signals from the temperature detectors 23, 24, and 26.

The operation of this control mechanism will be explained. For example, when performing a cooling cycle, the temperature sensor 23
The temperature of the cold water is controlled by adjusting the opening degree of the heat source heat amount control valve 13 via the controller 25 based on the signal of the cold water outlet temperature. During heating or heat pump operation, the temperature of hot water is controlled by a signal of the hot water outlet temperature from the temperature detector 24.

As mentioned above, when the cooling water temperature is low or the heat transfer coefficient of the cooling water pipe 18 is high, as described above, and an overload occurs at startup or at the beginning of installation, the amount of refrigerant condensed in the condenser C increases and the solution Concentration increases.

At this time, the concentration of the solution at the outlet of the generator G is directly or indirectly detected, and if there is a risk of crystal formation, the heat source heat amount control valve 13 is operated in the direction of closing to reduce the amount of heating.

In this case, to prevent hunting, the width Δ
Two layers with ξ are preferred. Within this range of Δξ, the controller 25 operates the valve in the closing direction according to the input signal, but it will be safer if it does not operate the valve in the opening direction.

The preferred location for detecting the concentration of the solution is near the outlet of the generator C. There is a method of estimating the cycle concentration from the liquid level height in the evaporator E, but this method only estimates the average concentration. Considering the avoidance of crystals, local concentrations in areas with high concentrations are required, and the generator outlet satisfies this condition and is even more preferable because it shows the current concentration.

The concentration detection method is as follows: (1) Determine the concentration using the specific gravity and temperature using a hydrometer (
Generator outlet system) (2) Calculate the concentration from the saturation pressure (or the dew point relative to the saturation pressure, i.e. the saturation temperature relative to the pressure) and the solution temperature (
generator outlet).

etc., but (2) will be explained.

The generated outlet solution has approximately equilibrium pressure and solution temperature. Therefore, the concentration can be determined from this relationship. The dew point and condensing temperature are almost the same.

In the case of LiBr-820 system, the solution concentration is ξ=0.60
In the range of ~0.70 (LiBr/LiBr+H20), T: solution temperature °C, W: dew point. In the range of T=20~170℃, the error is ±o, oo
It is about s.

In addition, as a simple method for determining the concentration, the solution temperature T and dew point (
The table below can be considered based on the difference from the condensation temperature) W, ΔT=T−W.

That is, a simple method may be used in which the temperature difference ΔT is detected and, based on this, the opening degree of the heat source heat amount control valve 13 is limited so that the 8T or 1 concentration does not exceed a predetermined set value.

The following method is used to determine the set value as the limit of permissible concentration.

(1) A fixed value (for example, 66%) is used as the setting value.

(2) As shown in Fig. 3, based on the outlet temperature t of the solution on the heating side of the solution heat exchanger 1. - Use Δξ as the set value ξ1, compare it with the directly or indirectly determined concentration ξ, and control so that ξ ≦ ξ0.

As Δξ, for example, about 0.5 to IIIt% is used.

Instead of the crystal line, use ゛ for the line with 9 margins,
The setting value may be determined using the margin Δξ'' as ξ1 = ξ..−Δξ゛.

(3) In the case of double effect, for series 70-, the solution temperature T (G
) and the condensation temperature T(C) to indirectly determine ξ and use it as the detected value. Know ξ. Find the set value ξ1 from −Δξ.

(4) In the case of a double-effect branch flow, as shown in Figure 5, ξ is indirectly determined from T (G) and T (C) at the outlet of the high temperature generator and used as the detected value. The outlet temperature t of the solution heat exchanger is ξ. Know ξ. Find the set value ξ from −Δξ.

Furthermore, for the low-temperature side, the outlet temperature of the low-temperature heat exchanger t゛ to ξ. Knowing ゛, ξ. -Δξ゛ may be used to determine the set value ξ1゛The present invention suppresses the increase in solution concentration due to overload at startup or at the beginning of installation, and prevents crystallization in absorption refrigerators that are safe and free from the risk of crystallization. This method can be provided and has extremely great practical effects.

[Brief explanation of drawings]

FIG. 1 is a cycle diagram of an absorption refrigerator, FIG. 2 is a flow diagram of an embodiment of the present invention, and FIGS. 3, 4, and 5 are diagrams showing a method for determining set values. A...Absorber, G...Generator, C...Condenser, E...Evaporator, X...Solution heat exchanger, SP...Solution pump, RP
・・Refrigerant pump, 1.2.3.4.5・・Piping, 6・・
Spray pipe, 7... Over 7C1-pipe, 8.9... Piping, 10... Spray pipe, 11... Piping, 12... Heating pipe, 13... Heat source heat amount control valve, 14... Cooling water pump,
15...Piping, 16...Cooling water pipe, 17...Piping, 18
・・Cooling water pipe, 19.・Piping, 20.・Cold water pipe, 21.
22...Piping, 23.24...Temperature detector, 25...Controller, 26...Temperature detector. Patent applicant Minoru Sen 1) Patent attorney representing Ebara Corporation

Claims (1)

[Claims] 1. An absorber, a generator, a condenser, an evaporator solution heat exchanger, a solution path connecting these devices, and a refrigerant path, and a heat source heat amount for heating in the generator 1''. In a method for preventing crystallization of an absorption refrigerator having a heat source heat amount control valve that controls A method for preventing crystallization in an absorption refrigerator, characterized by limiting the opening degree. 2. The indirect detection of the concentration of the solution at the outlet of the generator determines the concentration based on the temperature at the outlet of the generator and the condensation temperature of the condenser. 3. The method of claim 1, wherein the indirect detection of the generator outlet solution concentration is based on the difference between the generator outlet temperature and the condensing temperature of the condenser. The method according to claim 1, which is carried out by determining the concentration.4. The method according to claim 1, wherein the set value is determined by detecting the outlet temperature of the solution on the heating side of the solution heat exchanger. The method described in section.