JP2000241032A - Refrigeration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sustain a normal refrigeration cycle even upon generation of a fluctuation factor for disturbing the refrigeration cycle. SOLUTION: A refrigeration cycle liquefies refrigerant from a compressor 1 by water cooling it through a condenser 2 and evaporates the liquefied refrigerant through heat exchange with a thermal load in an evaporator 4 before returning it back to the compressor 1. A regulator 10 regulates an expansion valve 3 based on the refrigerant temperature at the outlet of the evaporator 4 to control the quantity of refrigerant being supplied from the condenser 2 to the evaporator 4. An auto-controller monitors operating conditions of the refrigeration cycle and performs appropriate control for altering the set value of the regulator upon occurrence of a factor having adverse effect on the refrigeration cycle and compensating for the adverse effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system for cooling air, which is a heat load in a gas waste treatment system of a nuclear power plant, for example.

[0002]

2. Description of the Related Art For example, in a gas waste treatment system of a nuclear power plant, a refrigeration system is used to cool air, which is a heat load. FIG. 6 shows a conventional refrigeration system in that case.

[0003] The refrigerant compressed by the compressor 1 is supplied to the condenser 2 through a compressor outlet line 18 and cooled and condensed by water supplied from a water inlet line 14. The refrigerant condensed in the condenser 2 is adjusted by the electric expansion valve 3 and sent to the evaporator 4 through the refrigerant inlet pipe 5. In the evaporator 4, air flows in from the air inlet line 12, exchanges heat with the refrigerant, and flows out from the air outlet line 16. Then, the refrigerant evaporates due to heat exchange with air, and the refrigerant return pipe 6
Through the compressor 1.

The compressor outlet line 18 of such a refrigeration cycle is provided with a hot gas bypass line 7 having a capacity control valve 8 so that the refrigerant bypasses the condenser 2 and the expansion valve 3. That is, a hot gas bypass line through which the refrigerant passes from the outlet of the compressor 1 to the outlet of the expansion valve 3 is provided, and the refrigerant compressed by the compressor 1 is directly supplied to the evaporator 4.
To supply. The amount of the refrigerant supplied directly to the evaporator 4 is adjusted by a capacity control valve 8. This enables control by compressor capacity in the refrigeration cycle.

[0005] The amount of the refrigerant condensed in the condenser 2 is controlled by a controller 10. In the controller 10, the temperature detector 9 provided at the outlet of the evaporator 4 in the refrigerant return pipe 6
The motor-operated expansion valve 3 is adjusted via the signal converter 11 so that the temperature T1 of the refrigerant gas detected in the step (1) becomes a preset temperature set in the controller 10. That is, the controller 10
Then, the increase or decrease in the amount of refrigerant corresponding to the change in the degree of superheat of the refrigerant gas evaporated by the evaporator 4 is sent to the signal converter 11 by an electric signal, converted into the number of pulses by the signal converter 11, and opened to the expansion valve 3. Instruct the degree adjustment.

Various setting values set in the controller 10 are set as shown in FIG. First, provisional setting is performed in a no-load state (S1). If the temporary setting is stable, the set value at the time of rated load is determined (S2). If the value is stable, the set values at the minimum load and the intermediate load are confirmed (S3). If it is not stable, it is reset. If it is stable, it is confirmed whether the cooling water temperature is stable at MAX and MIN (S4). Resets, and if it is stable, adopts the set value.

[0007]

However, in such control by the controller 10, there is no problem if the heat load does not fluctuate much. There is a problem that the refrigeration cycle is not repaired due to the influence. Moreover, once disturbances under different conditions overlap, the refrigeration cycle, which has been no problem, repeats a vicious cycle of further disturbance.

[0008] This is because the controller 10 uses PID control (P: proportional, I: integral, D: derivative) to set a common set for the entire heat load range (from no load to rated load). This is because a method of determining and controlling is adopted. If this refrigeration cycle is disturbed, the balance will be lost, and the outlet temperature of the evaporator 4 will not be cooled, and the PID constant of the controller 10 must be changed each time. A lot of time was spent responding to it.
As described above, since the conventional control value (PID or the like) of the refrigerant amount is a single-point value, there is a problem that the control value cannot be changed even if a factor that disturbs the refrigeration cycle occurs.

It is an object of the present invention to provide a refrigeration apparatus that can maintain a normal refrigeration cycle even when a change factor that disturbs the refrigeration cycle occurs.

[0010]

According to a first aspect of the present invention, there is provided a refrigeration apparatus wherein a refrigerant from a compressor is water-cooled and liquefied by a condenser and the liquefied refrigerant is exchanged with a heat load by an evaporator to evaporate. A refrigeration cycle for returning to the compressor, a controller for controlling the amount of refrigerant supplied from the condenser to the evaporator based on the refrigerant temperature at the outlet of the evaporator, and An automatic controller for changing a set value of the controller is provided.

In the refrigeration apparatus according to the first aspect of the present invention, the auto controller monitors the operation state of the refrigeration cycle,
In response to the occurrence of factors that adversely affect the refrigeration cycle,
Appropriate control is performed to change the set value of the controller and compensate for the adverse effect.

[0012] In a refrigeration apparatus according to a second aspect of the present invention, in the first aspect of the invention, the auto controller changes a set value of the controller based on a change in cooling water temperature at the inlet of the condenser. It is characterized by having done.

[0013] In the refrigeration apparatus according to the second aspect of the present invention, in addition to the operation of the first aspect of the present invention, the controller controls the operation according to the change of the cooling water temperature at the inlet of the condenser by changing the set value by the automatic controller. Control is performed by a pattern.

According to a third aspect of the present invention, in the refrigeration apparatus according to the first aspect of the present invention, the automatic controller changes a set value of the controller based on a load change at an inlet of the evaporator. It is characterized by.

In the refrigeration apparatus according to the third aspect of the present invention, in addition to the operation of the first aspect of the present invention, the controller changes the set value by the automatic controller so that the controller has an operation control pattern corresponding to the load change at the inlet of the evaporator. Perform control.

According to a fourth aspect of the present invention, in the refrigeration apparatus according to the first aspect of the present invention, the auto controller changes a set value of the controller based on a change in refrigerant pressure at an outlet of the compressor. It is characterized by the following.

In the refrigeration apparatus according to a fourth aspect of the present invention, in addition to the operation of the first aspect, the controller controls the operation control pattern corresponding to the change in the refrigerant pressure at the outlet of the compressor by changing the set value by the automatic controller. Control with.

According to a fifth aspect of the present invention, in the refrigeration apparatus according to the first aspect of the present invention, the auto controller changes a set value of the controller based on a temperature change at an outlet of the evaporator. It is characterized by.

In the refrigerating apparatus according to the fifth aspect of the present invention, in addition to the operation of the first aspect of the present invention, the controller changes the set value by the automatic controller so that the controller has an operation control pattern corresponding to the temperature change at the outlet of the evaporator. Perform control.

According to a sixth aspect of the present invention, in the refrigeration apparatus according to any one of the first to sixth aspects, the set value of the controller changed by the auto controller is:
A control constant of the controller, an upper limit value and a lower limit value of the operation amount, and a set value of the control amount are characterized.

In the refrigeration apparatus according to the sixth aspect of the present invention, in addition to the operation of any one of the first to sixth aspects, the auto-controller includes a control constant of the controller as a set value of the controller. Change any of the upper and lower limits of the manipulated variable and the set value of the control variable.

[0022]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a refrigeration apparatus according to an embodiment of the present invention. An auto controller 20 for changing the set value of the controller 10 according to the operation state of the refrigeration cycle is additionally provided to the conventional refrigeration apparatus shown in FIG.

In the embodiment of the present invention, a factor which adversely affects the refrigeration cycle of the refrigeration system when the heat load greatly fluctuates is selected in advance. As the factors, the refrigerant pressure P of the compressor outlet line 18, the cooling water temperature T2 of the water inlet line 14, the enthalpy H of the air inlet line 12 of the evaporator 4, and the air temperature T3 of the air outlet line 16 are selected in advance. This factor has been extracted from experience.

The set values of the controller 10 corresponding to the factors (control constants of the controller, upper limit value, lower limit value of the operation amount,
The control value (set value of the control amount) is programmed in the auto controller 20 in advance, and the set value is changed according to occurrence of the factor during operation.

In FIG. 1, the refrigerant compressed by the compressor 1 is supplied to the condenser 2 through a compressor outlet line 18 and cooled and condensed by water supplied from a water inlet line 14. The refrigerant pressure P in the compressor outlet line 18 is detected by a pressure switch 19, and the coolant temperature T2 in the water inlet line 14 is detected by a temperature detector 15. And
These are input to the auto-controller 20 as factors that adversely affect the refrigeration cycle of the refrigeration apparatus when the heat load greatly changes.

The refrigerant condensed in the condenser 2 is regulated by an electric expansion valve 3 and passes through a refrigerant inlet pipe 5 to an evaporator 4.
Sent to In the evaporator 4, air flows in from the air inlet line 12, exchanges heat with the refrigerant, and flows out from the air outlet line 16. Then, the refrigerant evaporates by heat exchange with air and returns to the compressor 1 through the refrigerant return pipe 6.

The enthalpy H of the air inlet line 12 of the evaporator 4 is detected by an enthalpy detector 13, and the air temperature T3 of the air outlet line 16 is detected by a temperature detector 17. Of the auto controller 2
Input to 0.

A hot gas bypass line 7 having a capacity control valve 8 is provided in the compressor outlet line 18 so that the refrigerant bypasses the condenser 2 and the expansion valve 3. That is, a hot gas bypass line through which the refrigerant passes from the outlet of the compressor 1 to the outlet of the expansion valve 3 is provided, and the refrigerant compressed by the compressor 1 is directly supplied to the evaporator 4. The amount of the refrigerant supplied directly to the evaporator 4 is adjusted by a capacity control valve 8. This enables control by compressor capacity in the refrigeration cycle.

Next, the amount of the refrigerant condensed in the condenser 2 is controlled by the controller 10. In the controller 10, the temperature detector 9 provided at the outlet of the evaporator 4 in the refrigerant return pipe 6
The motor-operated expansion valve 3 is adjusted via the signal converter 11 so that the temperature T1 of the refrigerant gas detected in the step (1) becomes a preset temperature set in the controller 10. That is, the controller 10
Then, the increase or decrease in the amount of refrigerant corresponding to the change in the degree of superheat of the refrigerant gas evaporated by the evaporator 4 is sent to the signal converter 11 by an electric signal, converted into the number of pulses by the signal converter 11, and opened to the expansion valve 3. Instruct the degree adjustment.

In a normal operating state, the controller 10 operates at a standard set value. That is, the controller 9 calculates the opening degree of the expansion valve 3 based on the refrigerant gas temperature T1 from the temperature detector 9, adjusts the valve opening degree of the expansion valve 3 via the signal converter 11, and controls the evaporator 4 Control the amount of supplied refrigerant.

On the other hand, the auto controller 20 constantly monitors the operation state of the refrigeration system.
This is performed by monitoring the air temperature T3 detected by the temperature detector 17 of the air outlet line 16 of FIG. That is, when the air temperature T3 detected by the temperature detector 17 of the air outlet line 16 of the evaporator 4 is increasing or decreasing, it is determined that the operation state is abnormal, and the auto controller 20 determines that the operation state is abnormal. Then, an appropriate set value is output to the adjuster 10, and the set value of the adjuster 10 is changed.

FIG. 2 shows a process amount input to the auto controller 20 as a factor that adversely affects the refrigeration cycle of the refrigeration system when the heat load greatly fluctuates, that is,
The enthalpy H of the air inlet line 12 of the evaporator 4 [see FIG.
(A) ", the cooling water temperature T2 of the water inlet line 14" FIG.
(B) ", the air temperature T3 of the air outlet line 16" FIG.
(C) ", the refrigerant pressure P in the compressor outlet line 18" FIG.
(D) is an explanatory view.

As shown in FIG. 2A, the enthalpy H of the inlet line 12 of the evaporator 4 is expressed as “R
1), "R2 when flow is lowest", "R3 at regular inspection"
In one state, the cause is out of the allowable range with the standard setting value. As shown in FIG. 2 (b), the cooling water temperature T2 of the water inlet line 14 is "maximum R4", "drop R5",
In the three states of "R6 at the time of regular inspection", this is a factor outside the allowable range with the standard set value. As shown in FIG.
The air temperature T3 of the air outlet line 16 is “abnormal rise R
7 ”,“ abnormal descent R8 ”,“ abnormal hunting R9 ”
In one state, the cause is out of the allowable range with the standard setting value. As shown in FIG. 2D, the compressor outlet line 1
The refrigerant pressure P of 8 is a factor outside the allowable range of the standard set value in the two states of “abnormal hunting R10” and “abnormal low pressure R11”. Therefore, in the case of these R1 to R11, it is necessary to consider these process amounts as fluctuation factors.

FIG. 3 is an explanatory diagram of set values of the controller 10 stored in the auto controller 20 in advance. Eleven combinations of various set values are created in advance corresponding to the fluctuation factors R1 to R11 shown in FIG.
0 is stored. “1” in FIG. 3 means that a standard setting value is adopted, and the other “2 to 12” means that different setting values are adopted.

Then, the auto controller 20 determines whether or not the outlet air temperature T3 of the evaporator 4 detected by the temperature detector 17 is increasing. If the air temperature T3 is increasing or decreasing, It is determined which of the fluctuation factors R1 to R11 the operating state of the refrigeration apparatus corresponds to, the fluctuation factors are specified, and a set value corresponding to the fluctuation factors is set in the controller 10.

FIG. 4 is a characteristic diagram showing an example of operating characteristics of the refrigeration system when the refrigeration cycle is disturbed. Now, it is assumed that a standard set value is set in the controller 10 and the expansion valve 3 is adjusted in that state. And during the operation, X
It is assumed that the air temperature T3 rises at a point. in this case,
The auto controller 20 reads detection signals of four detectors, that is, the enthalpy detector 13, the temperature detector 15, the pressure switch 19, and the temperature detector 17. Thereby, the enthalpy H of the air inlet line 12 of the evaporator 4,
Cooling water temperature T2 of water inlet line 14, air outlet line 1
6, the refrigerant pressure P in the compressor outlet line 18
Enter

The amount of the process is determined by the variation factor R.
It is determined whether or not the values correspond to 1 to R11, and a set value corresponding to the determined variation factor is output to the controller 10. Thereby, the controller 10 continues the control of the expansion valve 3 at the set value. If the increase in the air temperature T3 is not restored by this control, the auto controller 20 directly controls the air temperature T3 at the point Y.

FIG. 5 is a flowchart showing the above operation. The auto controller 20 constantly monitors the air temperature T3 from the temperature detector 17, and the air temperature T3
Rises to 8 ° C. (S1), the variation factors R1 to R11 are checked based on the above four process amounts (S2). In this case, when it is confirmed that the variation factor R1 is a large flow rate in the enthalpy detector 13 (S3), the corresponding set value is output to the controller 10 (S4, S5). Thereby, the controller 10 continues the control of the expansion valve 3 with the set value (S6). And
With this control, it is determined whether or not the rise in the air temperature T3 has been repaired (S7). If not, the auto controller 20 directly controls the air temperature T3 at the point Y (S8).

That is, if the factor cannot be cleared by the factor handling command, the set value for the temperature detector 17 is reset. This makes it possible to cover fluctuation factors that cannot be covered by the standard setting values.

[0040]

As described above, according to the present invention,
The instability factors of the refrigeration cycle during operation are ascertained during operation or during the test period, and appropriate controller setting values are prepared in advance for each factor. Can be.

Further, the setting value of the controller can be determined by performing a test for each condition and inputting the setting value, so that the time required for inputting the setting value is also small. Thus, the refrigeration cycle can easily cope with a change in the temperature of the cooling water or a change in other conditions relating to the operation of the refrigerator, and thus the operation can be continued in a stable state.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigeration apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a process amount as a variable factor in the auto controller according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of setting values of a controller stored in an auto controller in advance according to the embodiment of the present invention.

FIG. 4 is a characteristic diagram showing an example of operating characteristics when the refrigeration cycle of the refrigeration apparatus according to the embodiment of the present invention is disturbed.

FIG. 5 is a flowchart showing an operation when the refrigeration cycle is disturbed during operation of the refrigeration apparatus according to the embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional refrigeration apparatus.

FIG. 7 is an explanatory diagram of a method of setting a set value to a controller in a conventional refrigeration apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Expansion valve 4 Evaporator 5 Refrigerant inlet pipe 6 Refrigerant return pipe 7 Hot gas bypass line 8 Capacity control valve 9 Temperature detector 10 Controller 11 Signal converter 12 Air inlet line 13 Enthalpy detector 14 Water Inlet line 15, 17 Temperature detector 16 Air outlet line 18 Compressor outlet line 19 Pressure switch 20 Auto controller

Claims (6)

[Claims] 1. A refrigeration cycle in which a refrigerant from a compressor is water-cooled by a condenser and liquefied, and the liquefied refrigerant exchanges heat with a heat load in an evaporator to evaporate and return to the compressor, and an outlet of the evaporator. A controller that controls the amount of refrigerant supplied from the condenser to the evaporator based on the refrigerant temperature of the condenser, and an auto controller that changes a set value of the controller in accordance with an operation state of the refrigeration cycle. A refrigeration apparatus characterized by the above-mentioned. 2. The refrigerating apparatus according to claim 1, wherein the auto controller changes a set value of the controller based on a change in a cooling water temperature at an inlet of the condenser. 3. The refrigerating apparatus according to claim 1, wherein the auto controller changes a set value of the controller based on a load change at an inlet of the evaporator. 4. The refrigerating apparatus according to claim 1, wherein the auto controller changes a set value of the regulator based on a change in refrigerant pressure at an outlet of the compressor. 5. The refrigeration apparatus according to claim 1, wherein the auto controller changes a set value of the controller based on a temperature change at an outlet of the evaporator. 6. The controller according to claim 1, wherein the set value of the controller changed by the auto controller is a control constant of the controller, an upper limit value, a lower limit value of an operation amount, and a set value of a control amount. The refrigeration apparatus according to claim 6.