JP2668093B2 - Control method of absorption chiller / heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption chiller / heater,
In particular, melting depends on the heat input required for the high-temperature regenerator.
The present invention relates to a method for controlling an absorption chiller / heater for appropriately controlling a liquid circulation amount .

2. Description of the Related Art In a conventional method of controlling an absorption chiller / heater of this type, a circulation amount of a solution is adjusted to an appropriate amount according to a heat input amount required for a high-temperature regenerator. The control is performed by changing the frequency of the inverter that drives the solution pump based on the solution temperature of the high temperature regenerator or the cold water outlet temperature of the evaporator. Care was taken not to cause problems in the solution cycle such as an increase in the solution concentration due to the above.

On the other hand, in the above-described conventional method for controlling an absorption chiller / heater, the refrigerant is prevented from freezing or crystallizing due to a change in the temperature of the cooling water and a change in load. Therefore, the concentration of the solution was adjusted. Therefore, as shown in FIG. 2, even when the solution temperature of the same high temperature regenerator (high temperature regenerator temperature) is different, the saturation pressure varies depending on the solution concentration, so that the solution circulation amount is controlled using only the high temperature regenerator temperature as a parameter. If the solution concentration is other than the set value, mixing of the solution into the refrigerant in the separator due to excessive flow or refrigerant vapor bleeding in the separator due to insufficient flow causes a solution circulation amount. There was a problem that it could not be controlled properly. The present invention has been made in view of such circumstances, and an absorption chiller / heater that can optimally control a solution circulation amount without mixing a solution into a refrigerant in a separator and evacuating a refrigerant vapor. It aims at providing the control method of.

The present invention is directed to a high temperature regenerator for heating a dilute solution in which a refrigerant is absorbed in a solution, a separator for separating refrigerant vapor from the high temperature regenerator and an intermediate concentrated solution, and an intermediate After lowering the temperature of the concentrated solution, a low-temperature regenerator that heats with the refrigerant vapor from the separator, a condenser that condenses the refrigerant from the low-temperature regenerator, an evaporator that evaporates the liquid refrigerant from the condenser, and an evaporator and absorber for absorbing the evaporated refrigerant in the concentrated solution from the low-temperature regenerator, a solution pump for delivering the diluted solution in the absorber to the high temperature regenerator side, a solution circulation amount of heat input and the solution pump for Atsushi Ko regenerators Control means for controlling,
The control means inputs the cold water outlet temperature of the evaporator and outputs the cold water outlet temperature.
Control the amount of heat input based on the temperature
Inverter frequency relationship is used as a parameter of absorber outlet temperature
And memorize each set value in advance.
Enter the high temperature regenerator temperature and absorber outlet temperature
Temperature difference between the outlet temperature of the absorber and the set value of the outlet temperature of the absorber
If the solution concentration differs,
The inverter frequency with the deviation.
The solution pump is controlled according to the solution concentration .

In the method for controlling the absorption chiller-heater having the above-mentioned structure, the solution temperature at the outlet of the absorber (absorber outlet temperature), the cold water outlet temperature of the evaporator , and the solution temperature of the high temperature regenerator (high temperature regenerator temperature) are various. It is detected by a sensor. These temperature data are input to the control circuit that constitutes the control means, the control circuit calculates the heat input amount of the high temperature regenerator based on the cold water outlet temperature of the evaporator, and the gas supplied to the burner that heats the high temperature regenerator. The flow rate is controlled. In the control circuit, there is a temperature difference between the absorber outlet temperature and the absorber outlet temperature set value.
If the solution concentration is different, the inverter
Calculate the deviation from the frequency setting value and use the deviation to
The solution inverter frequency control signal for the solution pump is outputted from the control circuit in accordance with the solution concentration by correcting the data frequency
The circulation amount is corrected . Thus, incorporation into solutions refrigerant in the separator and prevents loss refrigerant vapor, it is possible to optimally control the solution circulation amount of the absorption cold and hot water machine, hot
Corrosion of heat transfer tubes such as heat exchangers is prevented, and load
The operating efficiency is improved accordingly .

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of a method for controlling an absorption chiller / heater according to the present invention. In the figure, an absorption chiller / heater according to the present invention comprises a high-temperature regenerator 1, a separator 2,
Low-temperature regenerator 5, condenser 7, evaporator 11, absorber 1
3, a solution pump 14, a cooling / heating switching valve 15, temperature sensors 21, 22, 23, an inverter 24, and a control circuit 25, which form a circulation system. In addition, 16 is a flow control valve, 17 is an orifice, which is provided at the outlet of the refrigerant circuit 20. Also 18
Is a burner. The high temperature regenerator 1 heats the introduced dilute solution. The separator 2 separates the high temperature steam that is heated by the high temperature regenerator 1 and boiled from the intermediate concentrated solution. The low-temperature regenerator 5 is separated by the separator 2 and cooled by heat exchange with the dilute solution in the high-temperature heat exchanger 3, and then the introduced intermediate concentrated solution is taken into the refrigerant circuit 20 from the separator 2. It is heated and concentrated by high-temperature steam, and at the same time, refrigerant vapor is generated. The condenser 7 takes in the refrigerant vapor generated by heating the intermediate concentrated solution from the low-temperature regenerator 5 and the liquid refrigerant deprived of heat by the intermediate concentrated solution and condensed into the cooling water flowing through the cooling water coil 6. Cool with water and condense. After the refrigerant condensed in the condenser 7 is retained in the lower liquid receiving portion 8, the evaporator 11 transmits the cold water heat transfer coil 1 through the dispersion pipe 9.
Sprinkle over 0 to evaporate. The absorber 13 absorbs the refrigerant vapor evaporated by the evaporator 11 by lowering the temperature of the concentrated solution flowing from the low-temperature regenerator 5 by the low-temperature heat exchanger, introducing the concentrated solution and dispersing it on the cooling water coil 6. , A diluted solution. The solution pump 14 sends the diluted solution in the absorber 13 to the high temperature regenerator via the low temperature heat exchanger 12 and the high temperature heat exchanger 3. The cooling / heating switching valve 15 switches between heating and cooling. The temperature sensors 21, 22, 23 detect the cold water outlet temperature of the evaporator 11, the high temperature regenerator temperature, and the absorber outlet temperature, respectively. The inverter 24 is connected to the solution pump 1
Adjust the amount of power supplied to No.4. The control circuit 25 captures the detection outputs of the temperature sensors 21, 22, and 23 and controls the amount of heat input to the high-temperature regenerator 1 and the amount of solution circulation of the solution pump based on these detection outputs. The operation of the method for controlling the absorption chiller / heater having the above configuration will be described below. The normal operation of the absorption chiller-heater is not directly related to the present invention, and thus its description is omitted. FIG. 2 shows the relationship of the saturation pressure P with respect to the solution temperature t (or the high temperature regenerator temperature th) using the solution concentration D as a parameter.
Shows the relationship between the high-temperature regenerator temperature th and the inverter frequency f. As shown in FIG. 2, even if the solution temperature ti in the high temperature regenerator 1 is the same, the concentration D (D1 <D0 <D
Since the saturation pressure differs depending on 2), if the solution circulation amount is controlled by using only the high temperature regenerator temperature as a parameter as in the conventional apparatus, if the solution concentration deviates from the set value (D0), the flow rate becomes too high in the separator. There is a possibility that mixing of the solution into the refrigerant or an insufficient flow rate may cause inappropriateness such as refrigerant vapor escape in the separator. In the embodiment of the present invention, the heat input amount of gas or the like to the high temperature regenerator 1 is controlled by the cold water outlet temperature of the evaporator 11, and the solution circulation amount of the solution pump 14 is an inverter based on the high temperature regenerator temperature and the absorber outlet temperature. By correcting the frequency of 24, a solution circulation amount suitable for the load amount is obtained. The solution concentration of the absorption chiller / heater is adjusted to keep the saturation pressure in the absorber 13 constant and to prevent the refrigerant from freezing and the solution from crystallizing. Assuming that the set value of the temperature is t0, the During diagram shown in FIG.
= D0. Next, referring to FIG. 3, the inverter frequency f with respect to the preset high temperature regenerator temperature th is obtained (f = F (th)). f is a function of th, and when the solution temperature ta at the outlet of the absorber 13 is different from t0, a deviation Δf with respect to a preset inverter frequency f0 is obtained, and this inverter frequency f (f = f0 + Δf) is calculated. As a result, a solution circulation amount suitable for the set solution concentration is obtained. Next, the operation of the control circuit will be described with reference to FIG. First coolant outlet temperature tc more evaporator 11 to the respective temperature sensors 21, 22, 23, the high-temperature regenerator temperature th, the absorber outlet temperature ta is detected and received by the control circuit 25 (step 30). Next, the absorber outlet temperature ta is ta =
It is determined whether or not t0, and if ta = t0, the inverter frequency f is calculated (steps 31, 3).
2). The obtained inverter frequency becomes f = f0, and a control signal for setting the inverter frequency f to f = f0 is output from the control circuit 25 to the inverter 24. As a result, the solution pump 14 is driven to rotate at a predetermined number of revolutions, and the amount of solution circulation from the absorber 13 to the high temperature regenerator 1 is controlled to a target value, that is, a predetermined value. Step 3
1, if it is determined that ta ≠ t0, the absorber 1
A deviation Δt between the outlet temperature ta and the set temperature t0 of Step 3 is calculated (Step 34). Further, the inverter frequency f is calculated in consideration of the deviation Δt, and the control circuit 25 outputs a control signal for setting the inverter frequency f to f = f0 + Δf (steps 35 and 36). Steps 34-3
6, when the solution concentration D is lower than the set value D0, for example, when operating at D = D1 (FIG. 2), that is, when the solution temperature ta at the outlet of the absorber 13 is a temperature t2 lower than the set value t0. (Fig. 3) shows the high temperature regenerator temperature t
Since the saturation pressure P for i becomes P1 higher than the set value P0, when the inverter 24 is operated at the set frequency f0 and the solution pump 14 is operated, the escape of the refrigerant vapor is likely to occur. This is because the saturation pressure is higher than the flow rate of the solution flowing into the high-temperature regenerator 1. Step 3 in this case
5, the deviation Δt of the absorber outlet temperature ta from the set temperature t0.
The inverter frequency f is calculated based on the above, and the inverter frequency f is added with the correction value Δf according to the deviation Δt, and f
= F2 (f2 = f0 + Δf). As a result, escape of the refrigerant vapor can be prevented. Conversely, when the solution concentration D is higher than the set value D0, for example, when operating at D = D2 (FIG. 2), the saturation pressure P with respect to the high temperature regenerator temperature ti becomes P2 lower than the set value P0, and therefore the set frequency is set. f
When the inverter 24 is operated at 0 and the solution pump 14 is operated, the solution easily flows, and the possibility that the solution mixes with the refrigerant in the separator 2 increases. However, in this embodiment, the correction value Δf corresponding to the deviation Δt is subtracted from the inverter frequency f in step 35, and f = f1 (f1 = f0−Δf).
Becomes As a result, similarly to the above, it is possible to prevent the refrigerant from being mixed into the solution.

According to the present invention, the heat input to the high temperature regenerator is controlled based on the cold water outlet temperature of the evaporator, and the heat absorption is controlled.
The temperature difference between the collector outlet temperature and the absorber outlet temperature set value
Inverter frequency was corrected to simplify temperature measurement.
With simple control means, the amount of solution circulation can be adjusted according to changes in solution concentration.
Continuous control enables improved control of solution circulation volume
To together, omission mixed and refrigerant vapor of the solution into the refrigerant in the separator can be securely prevented, heat transfer, such as a high temperature heat exchanger
Prevents pipe corrosion and increases operating efficiency depending on load
Has the effect of being done .

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of an embodiment of an absorption chiller / heater according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a high-temperature regenerator temperature and a saturation pressure.

FIG. 3 is a characteristic diagram showing a relationship between a high-temperature regenerator temperature and an inverter frequency.

FIG. 4 is a flowchart showing an operation content of a control circuit in FIG. 1;

[Explanation of symbols]

 1 High Temperature Regenerator 2 Separator 5 Low Temperature Regenerator 7 Condenser 11 Evaporator 13 Absorber 14 Solution Pump 24 Inverter 25 Control Circuit

Claims (1)

(57) [Claims] 1. A high temperature regenerator for heating a dilute solution in which a refrigerant has been absorbed in a solution, a separator for separating a refrigerant vapor from the high temperature regenerator and an intermediate concentrated solution, and after cooling the intermediate concentrated solution. A low-temperature regenerator that heats with the refrigerant vapor from the separator, a condenser that condenses the refrigerant from the low-temperature regenerator, an evaporator that evaporates the liquid refrigerant from the condenser, and an evaporator that evaporates. and absorber for absorbing refrigerant into the concentrated solution from the low-temperature regenerator, a solution pump for delivering the diluted solution in the absorber to the high temperature regenerator side, a solution circulating heat input and the solution pump to said Atsushi Ko regenerator Control means for controlling the amount of chilled water at the outlet of the evaporator.
Control the heat input based on the chilled water outlet temperature.
The relationship between the inverter frequency and the temperature of the hot regenerator is absorbed.
The outlet temperature is stored as a parameter and stored in advance
Each set value is stored, and the high temperature regenerator temperature and the suction
Input the outlet temperature of the collector, the outlet temperature of the absorber and the absorber
Solution concentration differs due to temperature difference with outlet temperature setting
In this case, find the deviation from the inverter frequency set value,
The inverter frequency is corrected by the deviation to bring the solution concentration to the above.
A method for controlling an absorption chiller / heater, comprising controlling the solution pump in response to the request .