JP2001201203A - Controller and controlling method for refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the controller for a refrigerating machine, in which mechanical lifetime can be prolonged by stabilizing the temperature of chilled water to reduce the operation of a control valve. SOLUTION: The controller for refrigerating machine comprises an operating section, generating an opening command signal S4 of a control valve 71 through operation by the chilled water temperature of a refrigerating machine having the control valve 71 or a set chilled water temperature, a comparison section 201 outputting an open/ close command signal S6 of the control valve, based on the comparison data with an actual opening thereof or the opening of the control valve indicated by the opening command signal, a section 202 for opening/closing the control valve, in response to the open/close command signal, and a refrigerating machine settled state deciding section 203 outputting a refrigerating machine settled signal S5, when it is deemed that the refrigerating machine has settled. Chilled water temperature of the refrigerating machine varies, depending on the opening of the control valve and the comparing section makes a decision whether the comparison data belongs to a dead band. The open/close command signal is delivered, if it belongs to a dead band, otherwise the open/close command signal is not delivered but the dead band is altered by the refrigerating machine signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus and a control method for a refrigerator, and more particularly to, for example, stabilization of chilled water temperature and reduction of operation of a control valve to extend mechanical life. The present invention relates to a control device and a control method for a refrigerator.

[0002]

2. Description of the Related Art In a refrigerator, an operation unit (control valve and the like) is subjected to PID calculation control according to a cooling load. When the cooling load is stable, in the current PID calculation control, the operation unit may operate more than necessary, and conversely, the load may fluctuate. Further, the number of operations of the operation unit is increased, and as a result, the consumption of the operation unit is accelerated.

In an absorption refrigerator, the chilled water temperature has been delayed in response to a change in the opening of the heat source control valve (a change in the flow rate of the heat source).
Therefore, in the conventional PID operation control, the control valve operates (opens and closes) due to a time lag even though the system is stable, and the opening degree becomes unstable (in the direction opposite to the stable direction of the system). As a result of the operation, the fluctuation of the chilled water outlet temperature and the consumption of the control valve operation section become severe.

In a centrifugal chiller, the temperature of the chilled water quickly responds to a change in the opening of the control valve. Therefore, the conventional PI
In the D operation control, when the system is stabilized, the operation (opening / closing operation) of the control valve becomes frequent, so that the chilled water outlet temperature fluctuates due to the instability of the opening and the control valve operating section is greatly consumed.

[0005]

SUMMARY OF THE INVENTION There is a need for a refrigerator control apparatus and method that can stabilize cold water temperature and reduce the operation of control valves to extend mechanical life. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device and a control method for a refrigerator, which can reduce the operation of a control valve and extend the mechanical life.

[0006] As for the control device of the absorption refrigerator,
The following technique is disclosed in JP-A-7-190540. A heating amount control function for controlling the heating amount of the generator based on the evaporator outlet side temperature of the cold water taken out via the heat transfer tube inside the evaporator; and the cold water returning to the heat transfer tube after finishing the cooling operation. A flow rate control function for controlling the flow rate of the cold water based on the evaporator inlet side temperature.

In Japanese Utility Model Publication No. 5-10186,
The technology related to the capacity control device of a refrigerator according to the application of the present applicant is disclosed as follows. Chilled water inlet temperature detecting means of the refrigerator, chilled water outlet temperature detecting means, means for calculating the temperature difference between the chilled water inlet temperatures from the detected temperatures of the two detecting means, and setting of the chilled water outlet or inlet temperature corresponding to the temperature difference. A means for calculating a correction value of the value, and a control means for controlling a capacity control mechanism of the refrigerator from an output value of the calculation means and the temperature of the chilled water outlet or the inlet, and a capacity control device for the refrigerator. is there.

[0008]

Means for solving the problem are described as follows. The technical matters corresponding to the claims in the expression are appended with parentheses (), numbers, symbols, and the like. The numbers, symbols, etc. clarify the correspondence / correspondence between the technical matter corresponding to the claim and the technical matter of at least one of the plural forms of implementation. It is not to show that technical matters are limited to technical matters of the embodiment.

The control device for a refrigerator according to the present invention comprises a control valve (7
An operation command signal (S4) indicating the degree of opening of the control valve (71) as a result of the calculation based on the refrigerator having (1) and the cold water temperature of the refrigerator and the set cold water temperature. Is compared with the actual opening of the control valve (71) and the opening of the control valve (71) indicated by the opening command signal (S4), and a comparison showing the result of the comparison is performed. Based on the data, a comparison unit (201) that outputs an open / close command signal (S6) for the control valve (71), and an open / close operation of the control valve (71) in response to the open / close command signal (S6). A valve opening / closing operation section (202) to be performed, and determining a stable state of the refrigerator. When the determination result indicates that the refrigerator is in a stable state, a refrigerator stable signal (S5).
And a refrigerator stable state determination unit (203) that outputs the following.
The comparison unit (201) changes according to the opening of the control valve (71), and determines whether the comparison data belongs to the dead zone (301). ), The switching command signal (S6) is output, and when it is determined that it belongs to the dead zone (301), the switching command signal (S6) is not output, and the refrigeration is not performed. The dead zone (301) is changed based on the machine stability signal (S5).

In the refrigerator control apparatus according to the present invention, the dead zone (301) includes an opening dead zone (302) for opening the control valve (71) and a closing direction for closing the control valve (71). The comparison unit (201) changes only the opening direction dead zone (302) when changing the dead zone (301).

In the refrigerator control apparatus according to the present invention, the refrigerator stability signal (S5) includes level data indicating the degree of stability of the refrigerator, and the comparing unit (201)
Based on the level data, when the degree of stabilization of the refrigerator is determined to be high, the dead zone (301) is largely changed compared to when it is determined that the degree of stability of the refrigerator is low. .

In the control apparatus for a refrigerator according to the present invention, when the refrigerator is an absorption refrigerator, the refrigerator stable state judging section (203) determines the temperature of the cold water of the absorption refrigerator, the temperature of the cooling water, The stable state of the refrigerator is determined based on at least one of the pressure of the high-pressure regenerator, the temperature of the high-pressure regenerator, and the solution concentration.

In the refrigerator control apparatus of the present invention, when the refrigerator is a centrifugal chiller, the refrigerator stable state determination unit (203) determines the temperature of the chilled water of the centrifugal chiller,
The stable state of the refrigerator is determined based on at least one of the temperature of the cooling water and the pressure of the evaporator.

In the control device for a refrigerator according to the present invention, when changing the dead zone (301), the comparing section (201) changes the first dead zone as the dead zone (301) to change the second dead zone. After the generation, when it is determined that the comparison data does not belong to the second dead zone, the third dead zone is generated by changing the second dead zone.

In the control device for a refrigerator according to the present invention, the third dead zone is the first dead zone.

In the control apparatus for a refrigerator according to the present invention, the chilled water temperature of the refrigerator is a temperature of the chilled water when the chilled water is discharged from the refrigerator.

In the control apparatus for a refrigerator according to the present invention, the temperature of the cold water of the refrigerator is a temperature of the cold water when the cold water enters the refrigerator.

The method for controlling a refrigerator according to the present invention is a method for controlling a refrigerator that controls a control object (temperature of cold water) of the refrigerator. (A) An operation object (7) that changes the control object
(B) calculating based on the actual value and the set value of the control target, and an operation amount command signal indicating an operation amount (opening) of the operation target (71) as a result of the calculation. (S4) is generated, and (c) the operation target (7
1) The actual operation amount (opening degree) and the operation amount command signal (S
Operation amount (opening) of the operation target (71) shown in 4)
And (d) judging whether or not the comparison data indicating the result of the comparison belongs to the dead zone (301), and (e) judging from the result of the judgment that the dead zone (301)
When it is determined that they do not belong to the operation command signal (S
6), and when it is determined that the signal belongs to the dead zone (301), the operation command signal (S6) is not output. (F) In response to the operation command signal (S6), (G) determining the stable state of the refrigerator; and (h) determining that the refrigerator is in a stable state as a result of the determination. Changing the dead zone (301).

In the method for controlling a refrigerator according to the present invention, the control target is a flow rate of a heating source of the refrigerator, and the operation target is a flow control valve (71) for determining a flow rate of the heating source. The operation amount of the object is determined by the flow control valve (7
It corresponds to the opening degree of 1).

In the present invention, in addition to the above-described PID calculation control, the stable state of the refrigerator is determined, and the dead zone of the control valve is automatically changed based on the determination result. By such control, the cold water temperature is stabilized, and at the same time, the operation of the control valve is reduced, and the mechanical life is extended.

In the present invention, the determination of the stable state of the refrigerator is performed as follows. When the refrigerator is an absorption refrigerator, the stability of the refrigerator is determined based on at least one of the temperature of the cold water, the temperature of the cooling water, the pressure of the high-pressure regenerator, the temperature of the high-pressure regenerator, and the solution concentration. A determination of the state is made. Specifically, the temperature, pressure, and concentration range are obtained at X minute intervals / X minutes, that is, the above-mentioned cold water temperature, cooling water temperature, high pressure regenerator pressure, high pressure regenerator temperature, and solution concentration Each average value is calculated, and the deviation between the calculated average value and the set value is ±
If t (t is a predetermined value), it is determined that the absorption refrigerator is in a stable state.

In determining the stability condition of the absorption refrigerator,
It is desirable that the determination be made based on two factors of the temperature of the chilled water and the temperature of the chilled water. Here, each element of the pressure of the high-pressure regenerator other than the temperature of the cooling water, the temperature of the high-pressure regenerator, and the concentration of the solution indicates the state inside the absorption refrigerator, whereas the temperature of the cooling water is Therefore, it is indispensable as a judgment element. For each of the above factors, the temperature of the chilled water and the temperature of the chilled water are weighted first, the solution concentration is weighted second, and the pressure of the high pressure regenerator and the temperature of the high pressure regenerator are weighted third. Is desirable.

On the other hand, when the refrigerator is a centrifugal refrigerator, the stable state of the refrigerator is determined based on at least one of the temperature of the chilled water, the temperature of the chilled water, and the pressure of the evaporator. Will be Specifically, the temperature range and the pressure range are determined at X minute intervals / X minutes, that is, the average values of the above-described cold water temperature, cold water temperature, and evaporator pressure are calculated. If the deviation between the calculated average value and the set value is within ± t (t is a predetermined value), it is determined that the turbo refrigerator is in a stable state.

In determining the stability condition of the centrifugal chiller, it is desirable that the temperature be determined based on two factors, that is, the temperature of the chilled water and the temperature of the chilled water. In that case,
Preferably, the temperature of the chilled water is weighted first and the temperature of the chilled water is weighted second. In addition, since the temperature of the cooling water is reflected on the pressure of the condenser, the temperature of the cooling water can be substituted for the determination factor of the pressure of the condenser. Further, the stable state of the turbo refrigerator can be determined based on each element of the pressure of the intermediate unit and the electric current of the electric motor in addition to or instead of the above elements.

As described above, when it is determined that a refrigerator (absorption refrigerator, turbo refrigerator) is in a stable state, the dead zone of the control valve is automatically changed. Here, for example, if the dead zone in the current opening direction (safety direction) is (opening command value of control valve (%)-actual opening (%)) and 3%, 10%
Spread out.

In the dead zone, the operation of the control valve is stabilized, leading to stabilization of the cold water temperature. Change over the changed dead zone (here, control valve opening command value (%)-actual opening (%)
Is greater than 10%) as before (a control valve opening command is output). As described above, when a change exceeding the dead zone after the change occurs (here, the opening command value (%)-actual opening (%) of the control valve is 10%).
), The automatic change is canceled (here, the dead zone is returned from 10% to 3%). The change of the dead zone is performed only in the opening direction of the control valve. As a result of the determination, the higher the degree of stabilization of the refrigerator, the larger the value of the dead zone is changed.

In the present invention, the opening direction of the operation unit (safety direction)
Operation is slowed down, the operation of the operation unit is stabilized, and the operation frequency of the operation unit is reduced. Specifically, the dead band (dead zone) in the opening direction is enlarged, and the timing at which the opening signal (valve opening command) is output is delayed. In addition, since it is dangerous to slow down the operation of the control valve in the closing direction, the control is performed as in the related art.

According to the present invention, cold water at a more stable temperature can be supplied. In addition, the operation amount of the operation unit is stabilized, and the life of the device is extended.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a control device for a refrigerator according to the present invention will be described with reference to the accompanying drawings.

The first embodiment will be described. In the first embodiment, the control device for a refrigerator according to the present invention is applied to an absorption refrigerator. First, the absorption refrigerator will be described.

The absorption refrigerator is a refrigerator using water as a refrigerant, a lithium bromide solution as an absorbent, and steam or fuel (gas or oil) as an energy source. This absorption refrigerator is mainly composed of an evaporator, an absorber, a regenerator, and a condenser. The interiors of the evaporator and the absorber are maintained in a high vacuum (absolute pressure is 6 to 7 mmHg).

In the evaporator, the refrigerant (water) sent by the refrigerant pump is sprayed toward an evaporator tube through which cold water (12 ° C.) flows, so that the refrigerant is heated to become refrigerant vapor. That is, since the evaporator is a high vacuum container, water (refrigerant) boils at 4 to 6 ° C. and evaporates, so that cold water at 12 ° C. can be used as the heat source water.

Then, the temperature of the cold water is reduced (to 7 ° C.) by the latent heat of evaporation given to the refrigerant (water), and then the cold water leaves the evaporator. The cold water whose temperature has dropped (to 7 ° C.) is sent to a building cooling device or the like (cooling load) and used for cooling. The cold water used for cooling rises in temperature, reaches a temperature of 12 ° C., and flows into the evaporator tube of the evaporator again.

In the absorber, the refrigerant vapor generated in the evaporator is absorbed by the lithium bromide solution. The lithium bromide solution (hereinafter referred to as “lithium bromide dilute solution”) that has absorbed water and has become less concentrated is collected at the bottom of the absorber. In this absorber, the latent heat of condensation when the refrigerant vapor is absorbed by the lithium bromide solution and changes from gas (water vapor) to liquid (water), and when the concentration of the lithium bromide solution becomes thin due to the absorption of moisture. Since heat of dilution is generated, these heats are removed by cooling water (circulated in a different system from the above “cold water”). Note that the lithium bromide solution is a substance that is rich in hygroscopicity and suitable for absorbing the refrigerant vapor, since the water vapor partial pressure is lower than the saturated vapor of water.

In the regenerator, the dilute lithium bromide solution sent from the absorber is heated. For this reason, a part of the refrigerant in the lithium bromide dilute solution is evaporated and vaporized, and the solution becomes a concentrated lithium bromide solution (hereinafter, referred to as a “lithium bromide concentrated solution”). The lithium bromide concentrated solution whose concentration has been raised to the original state is sent to the absorber and absorbs the refrigerant vapor again.
On the other hand, the evaporated refrigerant vapor is sent to the condenser.

In the actual machine, a double-effect absorption refrigerator in which regenerators are arranged in two stages is employed for the purpose of increasing heat efficiency and reducing heating energy. In this double-effect absorption refrigerator, a high-pressure regenerator that heats a dilute solution of lithium bromide with supplied steam and a high-temperature refrigerant vapor generated by the high-pressure regenerator are used as a regenerator. A low-pressure regenerator for heating the dilute solution.

In the condenser, the refrigerant vapor sent from the regenerator is cooled by cooling water and condensed and liquefied. The condensed water is supplied again to the evaporator as a refrigerant (water).

As described above, in the absorption refrigerator, the refrigerant (water)
Changes (phase change) with water-steam-water,
The lithium bromide solution changes (concentration solution-dilute solution-concentration solution) (change in concentration). In the process of the above-described phase change (refrigerant) and concentration change (lithium bromide solution), the absorption refrigerator produces cold water by the latent heat of evaporation of water, and absorbs water vapor by the absorption capacity of the lithium bromide solution. Is repeatedly performed in a high vacuum closed system.

In the steam absorption refrigerator, the amount of steam flowing through the high-pressure regenerator is increased to increase the amount of heating, and the concentration of the lithium bromide solution is increased, so that the temperature of the cold water flowing out of the evaporator is increased. Can be lowered. Conversely, by reducing the amount of steam flowing through the high-pressure regenerator to reduce the amount of heating and decreasing the concentration of the lithium bromide solution, the temperature of cold water exiting the evaporator can be increased. Thus, by adjusting the concentration of the lithium bromide solution, the temperature of the cold water is controlled, and the temperature of the cold water flowing out of the evaporator is set to the set temperature (7 ° C.).

Here, the overall configuration of the steam absorption refrigerator
The operation will be described with reference to FIG. 2 together with the operation during the cooling operation. During the cooling operation, the valve V9 is closed (shown in black in the figure), and the valves V1 to V8 are open (shown in white in the figure).

As shown in FIG. 2, the evaporator 10 and the absorber 2
0 is configured in the same shell (high vacuum vessel).

An evaporator tube 11 is arranged in the evaporator 10. Cold water W1 is supplied to the evaporator tube 11 through a cold water inlet line L1, and the cold water W1 flowing through the evaporator tube 11 is sent out through a cold water outlet line L2. The refrigerant (water) R pumped by the refrigerant pump P1 via the refrigerant line L11 is:
Sprayed toward the evaporator tube 11. The sprayed refrigerant R takes the latent heat of vaporization from the cold water W1 flowing in the evaporator tube 11, evaporates and vaporizes, and becomes refrigerant vapor r. This refrigerant vapor r flows into the absorber 20 side.

The cold water W1 is supplied to the evaporator 1 at a temperature of 12 ° C.
0, cooled by the evaporator tube 11, and sent out from the evaporator 10 at a temperature of 7 ° C. Cold water outlet line L2
The cold water W1 of 7 ° C. coming out of the chiller is used for cooling a building or for a process in a factory. The temperature of the cold water W1 used for cooling under a cooling load such as a building cooling condition rises to 12 ° C., and flows into the evaporator 10 again.

In the absorber 20, an absorber tube 21 is arranged. Cooling water W2 is supplied to the absorber tube 21 via cooling water lines L3 and L4. Then, the lithium bromide concentrated solution Y1 pumped by the concentrated solution pump P2 through the solution line L21 is sprayed toward the absorber tube 21. For this reason, the sprayed lithium bromide concentrated solution Y1 absorbs the refrigerant vapor r flowing into the absorber 20, and its concentration becomes thin. The diluted lithium bromide solution Y3 having a reduced concentration is collected at the bottom of the absorber 20. The heat generated in the absorber 20 is cooled by the cooling water W2 flowing in the absorber tube 21.

The dilute lithium bromide solution Y3 collected at the bottom of the absorber 20 is pumped by a regenerator pump P3, and is supplied with valves V2 and V3, a low-temperature heat exchanger 30, and a solution line L2.
2, heat recovery unit 70, high-temperature heat exchanger 31, solution line L2
3 and is supplied to the high-pressure regenerator 40.

The high pressure regenerator 40 has a steam line L31
Are disposed in a state of penetrating the steam line L3.
A steam flow control valve 71 is interposed on one of the steam inlets, which is upstream of the high-pressure regenerator 40. The steam flow control valve 71 adjusts the amount of steam flowing through the steam line L31.

This high-pressure regenerator 40 has a steam line L31
The high-temperature steam flows through this, thereby heating the lithium bromide dilute solution Y3. The lithium bromide dilute solution Y3 supplied to the high-pressure regenerator 40 is heated, and a part of the refrigerant evaporates and evaporates to become a medium concentration lithium bromide solution Y2. The solution Y2 in lithium bromide is supplied to the solution line L2
4. It is supplied to the low-pressure regenerator 50 through the high-temperature heat exchanger 31 and the solution line L25.

On the other hand, the refrigerant vapor r evaporated in the high-pressure regenerator 40 is supplied to the low-pressure regenerator tube 51 of the low-pressure regenerator 50 via the refrigerant line L12.
13 to the condenser 60. Note that the low-pressure regenerator 50 and the condenser 60 are configured in the same shell.

In the low-pressure regenerator 50, a solution Y2 in lithium bromide is supplied via a solution line L25, and a dilute lithium bromide solution Y3 branched from the solution line L22 via a solution line L26 is supplied to the low-pressure regenerator 50. Tube 51
Sprayed towards. In the low-temperature regenerator 50, the solutions Y2 and Y3 are heated by the low-pressure regenerator tube 51, a part of the refrigerant evaporates, the concentration of the solution further increases, and the high-concentration lithium bromide concentrated solution Y1 is converted to a low-pressure regenerator. Collected at the bottom of 50. This concentrated lithium bromide solution Y1 is supplied to the absorber 20 again by the concentrated solution pump P2.

The condenser 60 has cooling water lines L3, L5
A condenser tube 61 to which the cooling water W2 is supplied is disposed. In the condenser 60, the refrigerant is evaporated in the high-pressure regenerator 40 and the refrigerant line L12, the low-pressure regenerator tube 51
The refrigerant vapor r supplied through the refrigerant line L13 and the refrigerant vapor r evaporated by the low-pressure regenerator 50 and flowing into the condenser 60 side are cooled and condensed by the condenser tube 61 and the refrigerant ( Water) R. This refrigerant R is sent to the evaporator 10 via the refrigerant line L14 due to gravity and a pressure difference. The refrigerant R collected at the bottom of the evaporator 10 is again sprayed toward the evaporator tube 11 via the refrigerant line L11 by the refrigerant pump P1.

In the absorption refrigerator using steam as a heating source, the cold water W1 flowing out of the evaporator 10 has the above structure.
In order to maintain the temperature at the set temperature (7 ° C.), a cold water temperature control mechanism is employed.

Next, the chilled water temperature control mechanism will be described with reference to FIGS. The cold water temperature control mechanism,
The high-pressure regenerator 4 is controlled by controlling the valve opening of the steam flow control valve 71.
The steam flow supplied to 0 is adjusted, whereby the temperature is controlled so that the current chilled water outlet temperature becomes the set chilled water outlet temperature.

As shown in FIG. 3, the chilled water temperature control mechanism includes a first PID calculator (chilled water outlet temperature controller) 102
And a second PID calculation unit (steam flow controller) 104;
A comparison unit 201, a valve opening / closing operation unit 202, a refrigerator stable state determination unit 203, and an actual opening degree measurement unit 204 are provided.

As shown in FIG. 2, a chilled water outlet temperature sensor 101 is arranged on the chilled water outlet line L2. The chilled water outlet temperature sensor 101 outputs a chilled water outlet temperature signal S1 indicating the chilled water outlet temperature of the chilled water W1 cooled by the evaporator 10.
Is output. The chilled water outlet temperature controller (first PID calculation unit) 102 calculates a deviation of the chilled water outlet temperature signal S1 from the set chilled water outlet temperature so that the value of the chilled water outlet temperature signal S1 becomes the set chilled water outlet temperature (7 ° C.). PID calculation control
A steam flow set value signal S2 indicating the steam flow is output.

On the other hand, a steam flow sensor 103 is disposed upstream of the steam flow control valve 71 in the steam line L31. The steam flow sensor 103 outputs a steam flow signal S3 indicating the steam flow supplied to the high-pressure regenerator 40 via the steam line L31. The steam flow controller (second PID calculation unit) 104 sets the value of the steam flow rate signal S3 to be equal to the value of the steam flow rate set value signal S2.
The deviation of the steam flow rate signal S3 from the steam flow rate set value signal S2 is subjected to PID operation control, and a steam flow rate operation signal S4 is output. Here, the steam flow control signal S4 indicates, for example, a command to set the opening of the steam flow control valve 71 to 80%.

The comparison unit 201 (not shown in FIG. 2) outputs the opening command value (here, the opening command value) included in the steam flow rate operation signal S4.
80%) and the current actual opening (%) of the steam flow control valve 71 output from the actual opening measuring unit 204, and the difference between them (opening command value−actual opening (%)). Is calculated. The comparison unit 201 has data indicating the dead zone 301 as shown in FIG. In FIG. 4, a range where the difference is ± 3% is set as the dead zone 301.

In the following, it is assumed that the actual opening of the steam flow control valve 71 is 65%. The comparison unit 201 calculates the difference as + 15%, and then the difference falls within the dead zone 301. Judge whether they belong.
As a result of the above-described determination, the comparing unit 201 determines that it does not belong to the unit and outputs the valve opening command S6 because + 15% ≧ + 3% (see FIG. 4). Here, the comparison unit 201
The opening command S6 of the valve output from the steam flow control valve 71
Is digitally opened (as a binary signal). The valve opening / closing operation unit 202 digitally opens the steam flow control valve 71 in response to the input of the valve opening command S6 output from the comparison unit 201.

As a result of operating the valve opening / closing operation unit 202 as described above, the actual opening of the steam flow control valve 71 is increased, and the actual opening measured by the actual opening measuring unit 204 is 84%. explain. The comparison unit 201 calculates the difference
It is calculated as 4%, and since -4% ≤-3%, the valve closing command S6 is output. The valve closing command S6 indicates a command to digitally close the steam flow control valve 71, and the valve opening / closing operation unit 202 responds to the input of the valve closing command S6 output from the comparing unit 201. , The operation of digitally closing the steam flow control valve 71 is performed.

When the actual opening measured by the actual opening measuring unit 204 is in the range of 77% to 83%, the comparing unit 201 determines that the difference is ± 3%, that is, the dead zone 30.
1, and neither the above-mentioned valve opening command S6 nor the valve closing command S6 is output. At this time, the valve opening / closing operation unit 202 does not perform the opening / closing operation of the steam flow control valve 71.

As described above, the opening of the steam flow control valve 71 is adjusted in accordance with the value of the steam flow control signal S4, and as a result, the steam flow supplied to the high-pressure regenerator 40 is adjusted. You. By adjusting the steam flow rate in this manner, temperature control can be performed so that the current chilled water outlet temperature becomes the set chilled water outlet temperature.

In this temperature control, since the chilled water generation capacity and the concentration of the lithium bromide solution in the high-pressure regenerator 40 are in a proportional relation, the chilled water outlet temperature is controlled by controlling the flow rate of steam supplied to the high-pressure regenerator 40. It is based on the principle that it can be controlled.

In the first embodiment, in addition to the above PID calculation control, the refrigerator stable state determining unit 203 determines the stable state of the refrigerator, and based on the determination result, the comparison unit 2
01, the dead zone 301 of the control valve 71 is automatically changed. By such control, the cold water temperature is stabilized, and at the same time, the operation of the control valve 71 is reduced, and the mechanical life is extended.

The stable state determination section 203 of the refrigerator performs the determination of the stable state of the refrigerator as described below. When the refrigerator is an absorption refrigerator as in the first embodiment,
The stable state of the refrigerator is determined based on at least one of the temperature of the cold water, the temperature of the cooling water, the pressure of the high-pressure regenerator, the temperature of the high-pressure regenerator, and the solution concentration.
Specifically, the temperature, pressure, and concentration range are obtained at X minute intervals / X minutes, that is, the above-mentioned cold water temperature, cooling water temperature, high pressure regenerator pressure, high pressure regenerator temperature, and solution concentration Each average value is calculated, and the deviation between the calculated average value and each set value is ± t (t
Is within a predetermined value), it is determined that the absorption refrigerator is in a stable state.

Further, each range in which the deviation between the calculated average value and the set value is within ± t is divided into a plurality of stages according to the value of the deviation. Accordingly, even if the deviation between the respective average values and the respective set values is within ± t, and therefore, it is determined that the refrigerator is in a stable state, the stability is described in more detail. Can be determined up to the degree. The degree of stability is determined based on whether each deviation between the respective average values and the respective set values belongs to any of the plurality of stages. If each deviation belongs to a stage close to zero, the stability is determined to be high.

In determining the stability condition of the absorption refrigerator in the refrigerator stable state determination section 203, the above-mentioned components (the temperature of the cold water, the temperature of the cooling water, the pressure of the high-pressure regenerator, the temperature of the high-pressure regenerator, Concentration), it is desirable that the determination be made based on two factors: the temperature of the cooling water and the temperature of the cooling water. Here, each element of the pressure of the high-pressure regenerator other than the temperature of the cooling water, the temperature of the high-pressure regenerator, and the concentration of the solution indicates the state inside the absorption refrigerator, whereas the temperature of the cooling water is Therefore, it is indispensable as a judgment element. For each of the above factors, the temperature of the chilled water and the temperature of the chilled water are weighted first, the solution concentration is weighted second, and the pressure of the high pressure regenerator and the temperature of the high pressure regenerator are weighted third. Is desirable.

If it is determined that the refrigerator is in a stable state as a result of the determination by the refrigerator stable state determination unit 203, a signal indicating the stability (refrigerator stability state signal).
S5 is output to the comparison unit 201. As a result of the determination by the refrigerator stable state determination unit 203, if the refrigerator is not determined to be currently in the stable state, the refrigerator stability state signal S <b> 5 is not output to the comparison unit 201.

The comparing section 201 changes the value of the dead zone 301 in FIG. 4 based on the input refrigerator stability state signal S5. As shown in FIG. 4, the dead zone 301 includes a dead zone 302 in the opening direction and a dead zone 303 in the closing direction. In this case, based on the refrigerator stability state signal S5, the comparing unit 201 changes only the value of the dead zone 302 in the opening direction to increase (for example, + 3% to + 10%).

The comparison unit 201 receives the refrigerator stability state signal S
Even when 5 is input, the dead zone 303 in the closing direction is not changed. In the present embodiment, the closing direction of the steam flow control valve 71 (the direction in which the steam flow (heating source) supplied to the high-pressure regenerator 40 is reduced to lower the temperature) corresponds to the danger direction, and therefore, is sensitive without increasing the dead zone. This is because it is required that the steam flow rate be reduced promptly upon reaction.

The comparison unit 201 generates a refrigerator stability state signal S
5, when the value of the dead zone 302 in the opening direction is increased, the higher the stabilization degree of the refrigerator indicated by the refrigerator stability state signal S5, the larger the value of the dead zone 302 in the opening direction. change.

As described above, when it is determined that the refrigerator is in a stable state, the dead zone 302 in the opening direction of the control valve 71 is automatically changed (for example, the dead zone 302 in the opening direction is +1).
0%). In the dead zone 301, the operation of the control valve 71 is stabilized, leading to stabilization of the cold water temperature.

The change beyond the changed dead zone (in the case where the opening command value (%)-actual opening (%) of the control valve 71 exceeds + 10% of the dead zone 302 in the opening direction) is the same as before. The comparison unit 201 outputs a valve opening command S6. Then, as described above, when a change that exceeds the dead zone after the change occurs (here, the opening command value (%)-actual opening (%) of the control valve 71 is equal to 10 of the dead zone 302 in the opening direction. %), The automatic change is canceled (here, the dead zone 302 in the opening direction is 10% to 3%).
Returned to).

In the first embodiment, the operation of the control valve 71 in the opening direction (safety direction) is slowed down, the operation of the control valve 71 is stabilized, and the operation frequency of the control valve 71 is reduced. Specifically, the dead band (dead zone) 302 in the opening direction is enlarged,
The timing at which the open signal (valve open command) is output is delayed. The operation of the control valve 71 in the closing direction (the high-pressure regenerator 40)
It is dangerous to decrease the steam flow (heating source) to be supplied to the heater to reduce the temperature, and therefore, the control is performed in the conventional manner.

According to the present invention, cold water at a more stable temperature can be supplied. Further, the operation amount of the control valve 71 is stabilized, and the life of the device is extended.

In FIG. 2 and FIG. 3, based on the steam flow rate set value (S2) calculated by the first PID calculation section 102 and the steam flow rate (S3), the second PID calculation section 10
4 shows an example in which the steam flow rate operation signal S4 is obtained. In the present embodiment, as shown in the control valve opening / closing command calculation unit 400 in FIG. Thus, the control valve opening (opening / closing command) signal S6 for operating the control valve 71 as described above can be output.

In FIGS. 2 and 3, the temperature of the chilled water to be temperature-controlled is defined as the chilled water outlet temperature at the chilled water outlet. Instead of the chilled water outlet temperature, the chilled water inlet temperature may be used, and both the chilled water outlet temperature and the chilled water inlet temperature may be controlled.

As described above, in the absorption refrigerator, the solution concentration is used as a condition for determining the stability of the refrigerator. Here, the solution concentration can be determined by the method disclosed in Japanese Patent Publication No. 36868/1990, which is a patent right of the present applicant, or Japanese Patent Application Laid-Open No. 58-160783, filed by the present applicant. Tokiko 2-36868
The following technology is disclosed in Japanese Unexamined Patent Application Publication No. 2000-163,873. A control system that detects the chilled water outlet temperature and controls the amount of heating source to the regenerator and a control system that detects the solution level in the regenerator and controls the amount of solution circulation from the absorber to the regenerator, The refrigerant temperature or the pressure inside the regenerator, the concentrated solution temperature at the outlet of the regenerator, and the concentrated solution temperature at the outlet of the solution heat exchanger are detected, and the crystal concentration margin of the solution is calculated from these, and the margin is a predetermined value. An absorption refrigerator control device provided with a control system for controlling the heating source amount control system so as to reduce the heating source amount by obtaining an appropriate value of the heating source amount as a function of the margin when the following conditions are satisfied. In addition, a control system that detects a chilled water outlet temperature and controls a heating source amount to the regenerator and a control system that detects a solution level in the regenerator and controls a solution circulation amount from the absorber to the regenerator are provided. The condensed refrigerant temperature or the pressure inside the regenerator, the concentrated solution temperature at the outlet of the regenerator, and the concentrated solution temperature at the outlet of the solution heat exchanger are detected, and the crystal concentration margin of the solution is calculated from these, and the margin is calculated. An absorption refrigerating machine control device provided with a control system for obtaining an appropriate value of the solution circulation amount as a function of the margin when the value falls below a predetermined value and increasing the solution circulation amount in the solution circulation amount control system. Japanese Patent Application Laid-Open No. 58-160783 discloses a control system for controlling a heating source amount control valve by detecting a heating source amount control element in a regenerator and calculating a crystal concentration margin until crystal precipitation of a solution by heating. There is disclosed an absorption refrigerator control device which includes a control system for controlling a source amount control valve and continuously controls the heating source amount control valve based on output signals of both control systems.

Next, a second embodiment will be described with reference to FIGS. In the second embodiment, the refrigerator control device of the present invention is applied to a turbo refrigerator. In addition,
In FIG. 6, components substantially the same as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

In the turbo refrigerator, as shown in FIG. 5, a turbo compressor 1, a condenser 2, a refrigerant flow controller 3 and an evaporator 4 are connected by a refrigerant pipe 7. 5, reference numeral 5 denotes a condenser heat transfer tube, 6 denotes an evaporator heat transfer tube, 8 denotes a prerotation vane for controlling the capacity, 9 denotes a motor for driving the prerotation vane, 10a denotes a chilled water temperature control device, and 11a denotes a chilled water outlet temperature. Reference numeral 12 denotes a refrigeration (bundle) load of an air conditioner or the like, 13 denotes a chilled water inlet of the chiller, 14 denotes a chilled water outlet of the chiller, and 15 denotes a compressor driving device (electric heater, turbine, or the like).

The refrigerant compressed by the turbo compressor 1 is sent to the condenser 2 and is cooled by the cooling water in the condenser heat transfer tube 5 to become a refrigerant liquid. Then, the evaporator 4 enters
The refrigerant liquid flowing into the evaporator cools the cold water (brine) flowing in the evaporator heat transfer tube 6, loses latent heat and evaporates,
The refrigerant is sucked into the turbo compressor 1, and the refrigeration cycle is repeated.

The refrigerator is generally controlled so that the chilled water outlet temperature becomes constant (the value set first). for that reason,
The temperature of the chilled water outlet side 14 is detected by the chilled water outlet temperature detecting device 11a, and necessary PID calculation control is performed by the chilled water temperature control device 10a so that this temperature becomes the initially set value.
A signal is sent to a drive motor (electric motor) 9 of the pre-rotation vane 8 for controlling the capacity to move the pre-rotation vane 8.

In the second embodiment, as shown in FIG. 6, in addition to the PID calculation control by the chilled water temperature controller 10a,
The stable state determination unit 203 of the refrigerator determines the stable state of the refrigerator, and automatically changes the dead zone 301 of the pre-rotation vane 8 in the comparison unit 201 based on the determination result. By such control, the cold water temperature is stabilized, and at the same time, the operation of the prerotation vane 8 is reduced, and the mechanical life is extended.

The stable state determination section 203 for the refrigerator performs the determination of the stable state of the refrigerator as described below. When the refrigerator is a centrifugal refrigerator as in the second embodiment, the stable state of the refrigerator is determined based on at least one of the temperature of the cold water, the temperature of the cooling water, and the pressure of the evaporator. A determination is made. Specifically, the temperature range and the pressure range are determined at X minute intervals / X minutes, that is, the average values of the above-described cold water temperature, cold water temperature, and evaporator pressure are calculated. If the deviation between the calculated average value and the set value is within ± t (t is a predetermined value), it is determined that the turbo refrigerator is in a stable state.

Further, each range in which the deviation between the calculated average value and the set value is within ± t is divided into a plurality of stages according to the value of the deviation. Accordingly, even if the deviation between the respective average values and the respective set values is within ± t, and therefore, it is determined that the refrigerator is in a stable state, the stability is described in more detail. Can be determined up to the degree. The degree of stability is determined based on whether each deviation between the respective average values and the respective set values belongs to any of the plurality of stages. If each deviation belongs to a stage close to zero, the stability is determined to be high.

In determining the stability condition of the absorption chiller in the centrifugal chiller stability state determination unit 203, each of the above-described elements (cooling water temperature, cooling water temperature, and evaporator pressure) is used.
Among them, it is desirable that the judgment is made based on two factors of the temperature of the cold water and the temperature of the cold water. In that case, it is preferable that the temperature of the cold water is weighted first, and the temperature of the cooling water is weighted second. In addition, since the temperature of the cooling water is reflected on the pressure of the condenser, the temperature of the cooling water can be substituted for the determination factor of the pressure of the condenser. Further, the stable state of the turbo refrigerator can be determined based on each element of the pressure of the intermediate unit and the electric current of the electric motor in addition to or instead of the above elements.

As a result of the determination by the refrigerator stable state determination section 203, when it is determined that the refrigerator is currently in a stable state, a signal indicating the stability (refrigerator stability state signal).
S5 is output to the comparison unit 201. As a result of the determination by the refrigerator stable state determination unit 203, if the refrigerator is not determined to be currently in the stable state, the refrigerator stability state signal S <b> 5 is not output to the comparison unit 201.

The comparing section 201 changes the value of the dead zone 301 in FIG. 3 based on the refrigerator stability state signal S5 inputted. As shown in FIG. 3, the dead zone 301 includes a dead zone 302 in the opening direction and a dead zone 303 in the closing direction. In this case, based on the refrigerator stability state signal S5, the comparing unit 201 changes only the value of the dead zone 302 in the opening direction to increase (for example, + 3% to + 10%).

The comparison unit 201 generates a refrigerator stability state signal S
Even when 5 is input, the dead zone 303 in the closing direction is not changed. This is because, in the present embodiment, the closing direction of the pre-rotation vane 8 corresponds to the danger direction, so that it is required to react sensitively without increasing the dead zone.

The comparison unit 201 generates the refrigerator stability state signal S
5, when the value of the dead zone 302 in the opening direction is increased, the higher the stabilization degree of the refrigerator indicated by the refrigerator stability state signal S5, the larger the value of the dead zone 302 in the opening direction. change.

As described above, when it is determined that the refrigerator is in a stable state, the dead zone 302 in the opening direction of the pre-rotation vane 8 is automatically changed (for example, the dead zone 302 in the opening direction is changed to + 10%). ). In the dead zone 301, the operation of the pre-rotation vane 8 is stabilized, leading to stabilization of the cold water temperature.

The change beyond the changed dead zone (here, the case where the opening command value (%)-actual opening (%) of the pre-rotation vane 8 exceeds + 10% of the dead zone 302 in the opening direction) is as before. The comparison unit 201 outputs a valve opening command S6. Then, as described above, when a change that exceeds the dead zone after the change occurs (here, the opening command value (%) of the pre-rotation vane 8) −
When the actual opening degree (%) exceeds 10% of the dead zone 302 in the opening direction, the automatic change is canceled (here,
The dead zone 302 in the opening direction is returned from 10% to 3%).

In the second embodiment, the operation of the pre-rotation vane 8 in the opening direction (safety direction) is slowed, the operation of the pre-rotation vane 8 is stabilized, and the operation frequency of the pre-rotation vane 8 is reduced. In particular,
The dead band (dead zone) 302 in the opening direction is enlarged, and the timing at which the opening signal (valve opening command) is output is delayed.
In addition, since it is dangerous to slow down the operation of the pre-rotation vane 8 in the closing direction, the control is performed as in the related art.

According to the present invention, cold water at a more stable temperature can be supplied. Prerotation vane 8
Operation amount is also stable, and the life of the device is extended.

In this embodiment, as shown in the vane opening / closing command calculating section 500 in FIG. 6, the chilled water set temperature and the chilled water temperature, the condenser pressure, the evaporator pressure, the intermediate unit pressure,
And, based on the electric current of the electric motor, a control valve opening (opening / closing command) signal S6 for operating the prerotation vane 8 as described above can be output.

In FIGS. 5 and 6, the temperature of the chilled water to be temperature-controlled is defined as the chilled water outlet temperature at the chilled water outlet. Instead of the chilled water outlet temperature, the chilled water inlet temperature may be used, and both the chilled water outlet temperature and the chilled water inlet temperature may be controlled.

[0095]

According to the control device for a refrigerator of the present invention, the chilled water temperature is stabilized, and at the same time, the operation of the control valve is reduced, and the mechanical life is extended.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a part of a first embodiment of a control device for a refrigerator according to the present invention.

FIG. 2 is a diagram illustrating an overall configuration of an absorption refrigerator to which the first embodiment is applied;

FIG. 3 is a block diagram showing a part of the first embodiment shown in FIG. 2;

FIG. 4 is a graph for explaining a dead zone in the first embodiment.

FIG. 5 is a diagram showing an overall configuration of a centrifugal chiller to which a second embodiment of the refrigerator control device of the present invention is applied.

FIG. 6 is a block diagram showing a part of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbo compressor 2 Condenser 3 Refrigerant flow control device 4 Evaporator 5 Condenser heat transfer tube 6 Evaporator heat transfer tube 7 Refrigerant pipe 8 Prerotation vane for capacity control 9 Prerotation vane drive motor 10 Evaporator 10a Cold water temperature control Apparatus 11 Evaporator tube 11a Cold water outlet temperature detecting device 12 Refrigeration (bundle) load of air conditioner 13 Cold water inlet of refrigerator 14 Cold water outlet of refrigerator 15 Compressor drive device (electric heater, turbine, etc.) 20 Absorber 21 Absorption Heater tube 30 Low temperature heat exchanger 31 High temperature heat exchanger 40 High pressure regenerator 50 Low pressure regenerator 51 Low pressure regenerator tube 60 Condenser 61 Condenser tube 70 Heat recovery unit 71 Steam flow control valve 101 Cold water outlet temperature sensor 102 Cold water outlet temperature Controller (first PID calculation unit) 103 Steam flow sensor 104 Steam flow control Total (second PID calculation section) 201 Comparison section 202 Valve opening / closing operation section 203 Refrigerator stable state determination section 204 Actual opening degree measurement section 301 Dead zone 302 Dead zone in opening direction 303 Dead zone in closing direction 400 Control valve opening / closing command calculation section 500 Vane opening / closing command calculation unit L1 Cold water inlet line L2 Cold water outlet line L3 Cooling water line L4 Cooling water line L5 Cooling water line L11 Cooling line L12 Cooling line L13 Cooling line L14 Cooling line L21 Solution line L22 Solution line L23 Solution line L24 Solution line L25 solution line L26 solution line L31 vapor line P1 refrigerant pump P2 concentrated solution pump P3 regenerator pump R refrigerant (water) r refrigerant vapor S1 chilled water outlet temperature signal S2 vapor flow set value signal S3 vapor flow signal S4 vapor flow operation signal S5 refrigeration Stability status signal S6 Valve open / close command V1 valve V2 valve V3 valve V4 valve V5 valve V6 valve V7 valve V8 valve V9 valve W1 Cold water W2 Cooling water Y1 Lithium bromide concentrated solution Y2 Lithium bromide solution Y3 Lithium bromide Dilute solution

Claims (11)

[Claims] A refrigerator having a control valve; and calculating based on a chilled water temperature of the chiller and a set chilled water temperature, and, as a result of the calculation, an opening command signal indicating an opening of the control valve. An arithmetic unit to be generated, compares the actual opening of the control valve and the opening of the control valve indicated by the opening command signal, and opens and closes the control valve based on comparison data indicating a result of the comparison. A comparison unit that outputs a command signal; a valve opening / closing operation unit that opens / closes the control valve in response to the opening / closing command signal; and determines a stable state of the refrigerator. As a result of the determination, the refrigerator And a refrigerator stable state determination unit that outputs a refrigerator stability signal when it is determined that the refrigerator is in a stable state, wherein the chilled water temperature of the refrigerator is controlled by opening the control valve. The comparison unit changes according to the degree. It is determined whether or not belongs to the dead zone.As a result of the determination, when it is determined that it does not belong to the dead zone, the open / close command signal is output, and when it is determined that it belongs to the dead zone, the opening / closing is performed. A refrigerator control device that does not output a command signal and changes the dead zone based on the refrigerator stability signal. 2. The control device for a refrigerator according to claim 1, wherein the dead zone includes an opening dead zone in a direction in which the control valve is opened, and a closing dead zone in a direction in which the control valve is closed. Is a refrigerator control device that changes only the opening direction dead zone when changing the dead zone. 3. The refrigerator control device according to claim 1, wherein the refrigerator stability signal includes level data indicating a degree of stabilization of the refrigerator. A refrigerator control device that changes the dead zone greatly when it is determined that the degree of stabilization of the refrigerator is high based on data, as compared with when it is determined that the degree of stability of the refrigerator is low. 4. The control device for a refrigerator according to claim 1, wherein when the refrigerator is an absorption refrigerator, the refrigerator stable state determination unit determines a temperature of the cold water of the absorption refrigerator. A refrigerator control device for determining a stable state of the refrigerator based on at least one of a temperature, a cooling water temperature, a high-pressure regenerator pressure, a high-pressure regenerator temperature, and a solution concentration. 5. The control device for a refrigerator according to claim 1, wherein, when the refrigerator is a centrifugal chiller, the refrigerator stable state determination unit determines a temperature of the chilled water of the centrifugal chiller. A control device for a refrigerator that determines a stable state of the refrigerator based on at least one of a temperature, a temperature of cooling water, and a pressure of an evaporator. 6. The refrigerating machine control device according to claim 1, wherein the comparing section changes a first dead zone as the dead zone when changing the dead zone. And generating a third dead zone by changing the second dead zone when determining that the comparison data does not belong to the second dead zone. 7. The control device for a refrigerator according to claim 6, wherein the third dead zone is the first dead zone. 8. The refrigerator control device according to claim 1, wherein the chilled water temperature of the chiller is a temperature of the chilled water when the chilled water is discharged from the chiller. Control device. 9. The control device for a refrigerator according to claim 1, wherein the temperature of the cold water of the refrigerator is a temperature of the cold water when the cold water enters the refrigerator. apparatus. 10. A control method of a refrigerator for controlling a control target of a refrigerator, comprising: (a) providing an operation target for changing the control target; and (b) real value and setting of the control target. Calculating an operation amount command signal indicating an operation amount of the operation object as a result of the operation; and (c) calculating an actual operation amount of the operation object and the operation amount command signal indicated by the operation amount command signal. Comparing the operation amount of the operation target; (d) determining whether the comparison data indicating the result of the comparison belongs to a dead zone; and (e) determining that the comparison data does not belong to the dead zone as a result of the determination. When it is determined that the operation command signal is output, and when it is determined that the operation command signal belongs to the dead zone, the operation command signal is not output, and (f) in response to the operation command signal, Operating an operation target; And determining the steady state of the machine, (h) a result of the determination, when the refrigerator is determined to be in the stable state, the control method of the refrigerator and a changing said dead zone. 11. The method of controlling a refrigerator according to claim 10, wherein the control target is a flow rate of a heating source of the refrigerator, and the operation target is a flow control valve that determines the flow rate of the heating source. A method of controlling a refrigerator in which an operation amount of an operation target corresponds to an opening degree of the flow control valve.