JPH07104069B2 - Operation control method for absorption refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a refrigerant vapor (steam) by heating a solution obtained by absorbing a refrigerant liquid (eg, water) with an absorbing liquid (eg, LiBr aqueous solution) by steam or gas. Is generated, the refrigerant vapor is sent to the condenser, heat or water is liquefied by heat exchange with water or air, the liquefied refrigerant and the absorbing liquid are mixed and heated again to repeat the cycle of cooling and cooling, The present invention relates to an operation control method of a so-called absorption refrigerator that performs freezing and the like.

[Prior Art] FIG. 3 shows a flow of a conventional double-effect absorption refrigerator, in which reference numeral 1 is a cooling water pipe, 2 is a cooling water pipe, 3, 4, and 5.
Is a solution pipe, 6 and 7 are refrigerant pipes, 8 is a lift pipe, 9 and 10 are overflow pipes, 11 is a vapor trap, 12 is a damper,
13 is a solution pump, 14 is a liquid level relay, 15 is a high temperature regenerator, 16
Is a separator, 17 is a low temperature regenerator, 18 is a condenser, 19 is an absorber,
20 is an evaporator, 21 is a high temperature heat exchanger, 22 is a low temperature heat exchanger, 23
Is a gas line, 24 is an air line, 25 is a temperature detector, and 26 is a control mechanism. In the operation control method of this refrigerator, the outlet temperature of the cold water pipe 2 is detected by the temperature detector 25, and the control mechanism is used.
At 26, the solution pump 13 is controlled by an inverter and the gas flow rate is controlled.

[Problems of the prior art] However, in this conventional example, when the solution balance of the refrigerator is considered by the separator 16, the amount of solution entering is determined by the solution pump 13, and the amount of solution exiting is separated by the separator 16 and the low temperature regenerator. Since it is determined by the pressure difference of 17 and the flow resistance of the pipe 4 and the high temperature heat exchanger 21, etc., even if the liquid level of the rated time separator 16 is designed to be constant,
When the conditions at the time of rating change and the pressure in the separator 16 fluctuates, the balance in the separator 16 is lost unless the solution pump 13 is controlled. Therefore, for example, when the pressure of the separator 16 is reduced and the amount of the solution leaving the separator 16 is reduced, the solution pump 13 may be controlled to reduce the total circulation amount according to the following equation. If it is not applied, the liquid level of the separator 16 rises and overflows from the overflow pipe 9 and the steam trap 11, and the efficiency of the refrigerator decreases.

Where Geo: solution circulation rate at rating Ge: arbitrary solution circulation rate ΔPo: pressure difference between separator 16 and low temperature regenerator 17 at rating ΔP: pressure difference between low temperature regenerator 17 of arbitrary separator 16 pressure difference ΔP is greatly affected by the pressure of the separator 16,
The pressure of 16 changes depending on cold water, cooling water temperature, flow rate, gas heat input, and refrigerating capacity. Therefore, the above-described control cannot provide sufficient optimum control, and the liquid level relay 14 must separately control the liquid level to start and stop the solution pump 13. However, the liquid level relay 14 is prone to failure, and this operation control is not desirable even in terms of airtightness.

Thus, in the conventional inverter control of the solution pump, (1) even if the solution pump 13 is inverter-controlled from the cold water outlet temperature, if the pressure of the separator 16 changes due to changes in external conditions, the solution in the separator 16 The flow rate is out of balance and another control is required by the liquid level relay 14 etc., and the followability is poor especially when there is a large load change.

(2) There is a limit to improvement in efficiency due to the drawback of (1).

There was a problem.

The present invention is proposed in view of these points, and it is an object of the present invention to propose an operation control method that can be expected to improve the followability to load fluctuations and the efficiency of an absorption refrigerator.

[Means for Solving Problems] The operation control method of the present invention proposed to achieve the above object is as follows.

a. Temperature detection means are installed at the inlet to the absorber and the outlet of the condenser, which are cooling water paths, b. Temperature detection means are installed at the inlet and outlet of the evaporator, which are cold water paths, c .Calculating the deviation from the rated value obtained in advance based on the detection signal of the temperature detected by each of the temperature detecting means, and based on this value, heat input to the generator and return from the absorber to the generator An operation control method for an absorption chiller that controls a solution flow rate.

If there is a change in the flow rate in the cooling water system channel or the cooling water system channel, this flow rate is also detected, and the deviation from the rated value calculated in advance based on this flow rate signal is calculated to enter the generator. Correct the heat and solution flow rate from the absorber back to the generator.

[Embodiment] FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 is a cooling water pipe (cooling water passage), 2 is a cold water pipe (cooling water passage), 3, 4, 5
Is a solution pipe, 6 and 7 are refrigerant pipes, 8 is a lift pipe, 9 is a solution pump, 10 is a refrigerant pump, 11 is a high temperature regenerator (generator),
12 is a separator, 13 is a low temperature regenerator, 14 is a condenser, 15 is an absorber, 16 is an evaporator, 17 is a high temperature heat exchanger, 18 is a low temperature heat exchanger, 19 is a calculation unit, 20 is a control unit, 21 is an air line, 22 is a gas line, 22a is a gas valve, 23 is a temperature detector attached to the inlet of the cold water pipe 2, 24 is a temperature detector attached to this outlet, and 25 is an inlet of the cooling water pipe 1. An attached temperature detector, 26 is a temperature detector attached to this outlet.

In the above embodiment, the temperatures of the inlet and the outlet of the cooling water pipe 1 reaching the absorber 15 are constantly detected by the temperature detectors 25 and 26, and the temperatures of the inlet and the outlet of the cold water pipe 2 reaching the evaporator 16 are temperature detected. It is constantly detected by instruments 23 and 24. In the device in which the flow rates in the cooling water pipe 1 and the cold water pipe 2 vary, flow meters 28 and 29 are attached respectively.

Next, the operation and control method of the refrigerator of the above embodiment will be described.

In FIG. 1, the dilute lithium bromide solution in the high temperature regenerator 11 is heated to generate water vapor, which is blown out to the upper portion through the pumping pipe 8. At this time, the remaining concentrated lithium bromide solution that has generated steam in 11 simultaneously pushes up the pipe 8 by the principle of the hot bubble pump to reach the separator 12, separates it from steam and accumulates in the lower part. The high-pressure side steam separated at 12 further rises, reaches the low temperature regenerator 13 and the condenser 14 via the pipe 6, is cooled by the cooling water pipe 11, is condensed and flows to the lower part, and temporarily accumulates in the U-shaped pipe. on the other hand
The concentrated solution separated in 12 enters the high temperature heat exchanger 17 through the tube 4 and gives heat to the dilute solution flowing outside to rise in the tube,
It is sprayed from the small holes provided in the absorber 15, absorbs the water vapor in 15 and becomes a dilute solution and accumulates at the bottom.

In this way, the water vapor in 15 is absorbed and the pressure becomes low, so
The vapor pressure also decreases in the evaporator 16 connected to this, and U
The water accumulated in the character tube flows into 16 and evaporates, and the heat of vaporization is taken away. Since the absorbing action is lowered in the absorber 15 due to the temperature rise due to the absorbed heat, the cooling is performed through the cooling water pipe 1. The dilute solution accumulated at the bottom of the absorber 15 is the solution pump 9, the pipe 12,
It flows through the heat exchangers 17 and 18 to the high temperature regenerator 11, and the above circulation is repeated again.

When load fluctuations occur in such a situation, the temperatures at the respective inlets and outlets of the cooling water pipe 1 and the cooling water pipe 2 fluctuate. Therefore, this temperature signal is input to the calculation unit 19, and a rating previously determined by simulation or the like is input from this input. The deviation from the value is calculated, and the operating amounts of the gas valve 22a of the gas line 22 and the solution pump 9 are controlled by the output signal from the control unit 20 based on the calculated value.

Next, the concept of calculation in the calculation unit 19 will be shown.

Where Q _g ^* : Rated value of gas heat input G _e ^* : Rated value of solution flow rate C _{1 to} C ₈ : Constants Next, specific calculation examples will be shown. (However, cold water inlet temperature 13
(When changing from ℃ to 11 ℃) _{Q g = 80,000 × {1 +} 2.234 × (-0.154)} = 80,000 × 0.656 = 52,500 (kcal / h) G e = 900 × {1 + 2.190 × (-0.154)} = 900 × 0.663 = 600 (l / h) That is, when the cold water inlet temperature changes from 13 ℃ to 11 ℃ Gas heat input Q _g 80,000kcal / h → 52,500kcal / h Solution flow rate G _e 900l / h → 600l / h Gas heat input and control voltage, solution The relationship between the flow rate and the control voltage is first-order approximated.

V _Q = A · Q _g + B V _G = C · Q _g + D A, B, C, D are constants, and V _Q and V _G are control voltages.

[Effects of the Present Invention] As described above, the present invention detects the temperature at which cooling water enters and exits and the temperature at which cold water enters and exits, obtains a deviation from a preset rated value, and tends to eliminate this deviation. Since the heat input and the amount of solution were controlled, the followability to load fluctuation was improved very well.

FIG. 2A shows a control example according to the conventional example, and FIG. 2B shows a control example according to the present invention.

Further, since the followability is improved as described above, there is an effect that the efficiency can be improved especially in the refrigerator in which the load variation is large.

[Brief description of drawings]

FIG. 1 is an embodiment diagram of an absorption chiller according to the present invention, FIG. 2 is an explanatory view of a control example of a conventional example and the present invention example, and FIG. 3 is an explanatory diagram of a conventional absorption chiller. 1 ... Cooling water pipe, 2 ... Cold water pipe 3, 4, 5 ... Solution pipe, 6, 7 ... Refrigerant pipe 8 ... Pumping pipe, 9 ... Solution pump 10 ... Refrigerant pump, 11 ... High temperature Regenerator (generator) 12 …… Separator, 13 …… Low temperature regenerator 14 …… Condenser, 15 …… Absorber 16 …… Evaporator, 17 …… High temperature heat exchanger 18 …… Low temperature heat exchanger, 19 ... Calculation unit 20 ... Control unit, 21 ... Air line 22 ... Gas line 23,24,25,26 ... Temperature detector (temperature detection means) 28,29 ... Flowmeter (flow rate detection means)

Claims (2)

[Claims] Claims: 1. A temperature detecting means is attached to the inlet of the cooling water passage leading to the inside of the absorber and an outlet of the condenser, and b. Temperature detecting means is attached to the inlet and outlet of the evaporator in the cold water passage. C. Calculate the deviation from the rated value obtained in advance based on the temperature detection signal detected by each of the temperature detection means, and based on this value, input heat to the generator and from the absorber An operation control method for an absorption chiller, which controls a flow rate of a solution returned to the generator. 2. A flow rate detecting means is attached to each of the cooling water system passage and the cold water system passage, and a deviation from a rated value obtained in advance based on this flow rate signal is calculated together with the temperature to calculate heat input to the generator and from the absorber. The operation control method for an absorption chiller according to claim 1, wherein the flow rate of the solution returned to the generator is controlled.