JP3427285B2 - Absorption chiller / heater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid level control of equipment provided in an absorption chiller / heater, and particularly to absorption suitable for measuring the temperature near the liquid level of a solution to detect the position of the liquid level. The present invention relates to a liquid level control method for a chiller / heater.

[0002]

2. Description of the Related Art An example of a conventional absorption chiller-heater will be described with reference to FIG. A high temperature regenerator 11 that heats a dilute solution (solution) with a heating source 11a to separate it into a refrigerant vapor and an intermediate concentrated solution (solution), and a refrigerant vapor coil 12a with one end connected to the gas phase part of the high temperature regenerator 11 The low-temperature regenerator 12 and the condenser 4 that is connected to the low-temperature regenerator 12 and is connected to the other end of the refrigerant vapor coil 12a and has the cooling water coil 4a installed therein.
Is connected to the condenser 4 by the liquid refrigerant pipe 4b, and the evaporation coil 2a
2 and an absorber 2 in which the cooling water coil 1a is provided, which is in communication with the evaporator 2 through an evaporative refrigerant vapor passage, and a solution whose suction side is connected to the bottom of the absorber 1 by a dilute solution suction pipe 5a. The circulation pump 5, a low temperature solution heat exchanger 13 connected to the discharge side of the solution circulation pump 5, and a low temperature solution heat exchanger 13
High temperature solution heat exchanger 14 connected to the diluted solution inlet of the high temperature regenerator 11, and an intermediate concentrated solution pipe connecting the liquid phase part of the high temperature regenerator 11 and the heating fluid inlet of the high temperature solution heat exchanger 14. 11b, an intermediate concentrated solution pipe 14b connecting the heating fluid outlet side of the high temperature solution heat exchanger 14 and the heating fluid outlet side of the low temperature solution heat exchanger 13, a bottom portion of the low temperature regenerator 12, and the low temperature solution heat exchanger 13 Concentrated liquid pipe 12b connecting the heating fluid inlet side of the low temperature solution, the concentrated solution pipe 13b connecting the heating fluid outlet side of the low temperature solution heat exchanger 13 and the upper part of the absorber 1, and the outlet side of the cooling water coil 1a and cooling. It is composed of a cooling water pipe 1b connecting the inlet side of the water coil 4a. The outlet side of the cooling water coil 4a is connected to a cooling tower (not shown), and the inlet side of the cooling water coil 2a is connected to the cooling tower via a cooling water pump (not shown).

The operation of the absorption chiller-heater having the above-described structure during the normal cooling operation will be described. The dilute solution in the high temperature regenerator 11 is heated by the heating source 11a to be in a gas-liquid two-phase flow state and separated into a refrigerant vapor and an intermediate concentrated solution, and the refrigerant vapor passes through the refrigerant vapor coil 12a installed in the low temperature regenerator 12. After that, the intermediate concentrated solution flows into the condenser 4, and the intermediate concentrated solution flows into the heating fluid side of the high temperature solution heat exchanger 14 through the intermediate concentrated solution pipe 11b. The intermediate concentrated solution that has flowed into the high temperature solution heat exchanger 14 passes through the high temperature solution heat exchanger 14 while heating the dilute solution, flows into the absorber 1 through the intermediate concentrated solution pipe 14b, and is placed on the cooling water coil 1a. It is scattered.
The refrigerant vapor flowing in the refrigerant vapor coil 12a heats the surrounding intermediate concentrated solution to evaporate the refrigerant to generate a secondary refrigerant vapor, which itself is cooled and condensed to become a gas-liquid two-phase condenser 4 Flow into. The secondary refrigerant vapor generated in the low temperature regenerator 12 also flows into the condenser 4, and is cooled and condensed with the inflowing refrigerant into the cooling water flowing in the cooling water coil 4a to become a liquid refrigerant.

The liquid refrigerant generated in the condenser 4 flows into the evaporator 2 via the liquid refrigerant pipe 4b, is sprayed on the evaporation coil 2a installed in the evaporator 2, and flows in the evaporation coil 2a. Of the heat is evaporated to become refrigerant vapor again, and then flows into the absorber 1 through the evaporated refrigerant vapor passage. The heat medium that has been deprived of heat and cooled is guided to the cooling load, is cooled, and then returns to the evaporation coil 2a again. The intermediate concentrated solution obtained by evaporating the refrigerant as the secondary refrigerant vapor in the low temperature regenerator 12 becomes a concentrated solution (solution), and flows into the heating fluid inlet side of the low temperature solution heat exchanger 13 via the concentrated solution pipe 12b. The concentrated solution flowing into the low temperature solution heat exchanger 13 passes through the low temperature solution heat exchanger 13 while heating the dilute solution, and then flows into the absorber 1 via the concentrated solution pipe 13b. The concentrated solution that has flowed into the absorber 1 is sprayed onto the cooling water coil 1a and absorbs the refrigerant vapor that flows from the evaporator 2 to become a dilute solution. Absorption heat generated when the concentrated solution absorbs the refrigerant vapor is transferred to the cooling water flowing in the cooling water coil 46 and is carried to the cooling tower.

The dilute solution produced in the absorber 1 is sucked into the solution circulation pump 5 through the dilute solution suction pipe 1c, pressurized and flows into the low temperature solution heat exchanger 13. The dilute solution flowing into the low temperature solution heat exchanger 13 passes through the low temperature solution heat exchanger 14 while being heated by the concentrated solution flowing on the heating fluid side, and then flows into the high temperature solution heat exchanger 14. The diluted solution flowing into the high temperature solution heat exchanger 14 passes through the high temperature solution heat exchanger 14 while being heated by the intermediate concentrated solution flowing on the heating fluid side, and then flows into the high temperature regenerator 11. The dilute solution flowing into the high temperature regenerator 11 repeats the above cycle again. The cooling water from which the absorption heat of heat is taken out by the cooling water coil 1a and the condensation heat of which is taken out by the cooling water coil 4a flows into the cooling tower, and releases the absorbed heat and condensation heat carried into the atmosphere. During normal operation, the cycle described above is repeated.

Next, the liquid level control will be described. As disclosed in Japanese Examined Patent Publication No. 61-48062, for example, the solution circulating pump 5 is turned on / off or proportionally controlled by a float type level switch 20 so that the liquid level of the solution in the absorber 1 can be maintained. Alternatively, there is a ball tap method in which the control valve 19 restricts the conduit on the outlet side according to the position of the float, which changes with the height of the liquid surface on the suction side, to control the liquid supply amount. Further, a float type level switch and a control valve or a ball tap system are used so as to hold the liquid surfaces of the high temperature regenerator 11 and the low temperature regenerator 12, but both are mechanically controlled so that the liquid level is waving. Therefore, the control accuracy is low, the cost is structurally high, and the shape of the float or the ball is large, so that it requires a large space for mounting and the equipment becomes large. Further, since the movement of the float or the ball cannot be confirmed from the outside, the reliability is low, and there has been a drawback that the float or the ball is apt to crack.

[0007]

In the conventional liquid level control method for an absorption chiller / heater, the solution circulating pump is started / stopped or proportionally controlled by a float type level switch so as to maintain the liquid level of the solution. However, a ball tap method is used in which the liquid feed amount is controlled by the position of the float that changes with the liquid level height, but in both cases, the control accuracy is low and the cost is high. Further, since the shape of the float or the ball is large and a space is required for mounting, the size of the device becomes large, and the float or the ball is apt to be cracked.

An object of the present invention is to provide a liquid level control method for an absorption chiller-heater, which is capable of maintaining the liquid level of a solution in a device with high accuracy and performing highly reliable control.

[0009]

In order to achieve the above object, each device including a high temperature regenerator, a low temperature regenerator, a condenser, an evaporator and an absorber is connected to each device for circulating a solution. In the liquid level control method for an absorption chiller-heater in which the liquid level of the stored solution is controlled by a control valve, there are two parts, namely, a part that should be in the gas phase and a part that should be in the liquid phase of each device.
A temperature sensor is provided at one position, and the temperature of the part that should be the liquid phase of each device and the temperature of the part that should be the gas phase of each device are measured using the temperature sensor, and the liquid phase of each device should be used. the position of the liquid surface of each device is controlled by detecting by comparing the measured temperature and the measured temperature of the site which should be gas phase portion, the measured temperature of the site should be liquid phase
A measurement of the part that is above the set temperature or should be in the gas phase
If the measured temperature of the part that should be in the liquid phase is higher than the measured temperature
Temperature sensor that measures the temperature of the part that should be in the liquid phase
It is determined that there is a liquid surface at the position of
Area where the temperature is lower than the set temperature and should be in the liquid phase
Is equal to the measured temperature of the part that should be in the gas phase
When, a temperature sensor that measures the temperature of the part that should be in the liquid phase
The absorption chiller-heater is configured to determine that there is no liquid level at the location .

Further, the mounting position of the temperature sensor for measuring the temperature of the portion which should be in the liquid phase is the lower limit liquid level level where the idle operation of the solution circulation pump can be prevented, and the temperature of the portion which should be in the gas phase is set. The mounting position of the temperature sensor to measure is
The upper limit liquid surface level position is set so that the mixture of the solution with the refrigerant can be prevented.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, an intermediate concentrated solution (solution) obtained by heating a dilute solution (solution) such as an aqueous solution of lithium bromide with a burner 15 and separating it from the refrigerant vapor is stored in the high temperature regenerator 11, and the intermediate concentrated solution is stored. The concentrated solution (solution) generated by reheating with the refrigerant vapor is stored in the low-temperature regenerator 12, the refrigerant vapor is condensed into the liquid refrigerant by the condenser 4, the liquid refrigerant is evaporated by the evaporator 2, and the vapor is evaporated. The dilute solution produced by absorbing the refrigerant into the concentrated solution is stored in the absorber 1 and circulated to the high temperature regenerator 11 by the solution circulation pump 5, and the respective devices 1, 1
A liquid level control method for an absorption chiller-heater in which the liquid levels of the respective solutions stored in the liquid tanks 1 and 12 are controlled by control valves V _{1 to} V ₃ , and the temperatures t _{1 to} t in the vicinity of the respective liquid levels are used. ₆ is measured by the temperature sensors 21 to 26, and the measured temperatures t _{1 to} t ₆ and the set temperatures T _{1 to} T ₆ are compared to detect and control the positions of the respective liquid surfaces. The temperature near the liquid surface is measured by the temperature sensor 2 provided in the liquid phase portion.
The measured temperatures t ₁ , t ₃ , t _{5 of 1} , 23, 25 may be used.

Further, the temperature near the liquid surface is measured by the temperature sensors 21, 23, 25 provided in the liquid phase portion below the liquid surface t ₁ , t ₃ , t ₅ , and the gas phase above the liquid surface. Temperature sensors 22, 24, and 26 provided in the section, measured temperatures t ₂ , t ₄ ,
a t _6, may detect the position of each of the liquid surface from the measured temperature difference between the liquid phase and the gas phase portion, opening of the control valve V _1, V _2, V ₃ by a not-shown controller The liquid level shall be controlled by adjusting the degree.

The positions of the respective liquid surfaces are determined by, for example, the set temperature T ₁ of the liquid phase part of the high temperature regenerator 11 among the respective devices and the temperature sensors 23 of the low temperature regenerator and the absorber.
Set temperature relationship T ₃ , T ₅ with the temperature measured at 25
Is stored in advance, the temperature of the liquid phase portion measured by each device is compared with the set temperature, and it is detected by the presence or absence of the liquid surface.

That is, in this embodiment, the temperature sensor detects the position of the liquid surface. FIG. 2 shows a cycle on the Dühring diagram (pressure-temperature diagram). Even at the same pressure, a remarkable temperature difference can be obtained between the liquid phase part containing the solution and the gas phase part containing the refrigerant vapor. Therefore, this liquid temperature or the temperature difference between the liquid phase part and the gas phase part is calculated by a controller (not shown), and the liquid level position is detected by determining the presence or absence of the liquid level from the temperature difference, and the controller controls the control valve. The liquid level is controlled by adjusting the opening degree of. In order to correctly grasp the liquid surface when the liquid temperature is changing, such as when the liquid temperature is rising or falling, temperature sensors are provided at two positions, one that should be the gas phase and the other that should be the liquid phase. The presence or absence of the liquid surface can be detected by the temperature difference. For example, liquid level height of absorber 1 shown in FIG. 1 (presence or absence of liquid)
Temperature sensor 2 which should measure the liquidus temperature to detect
5 and the temperature sensor 26 in the vapor phase part are used.

For example, as shown in FIG. 3, the step of controlling the position of the liquid surface of the high temperature regenerator includes a step 101 of storing in the controller the set temperature T ₁ of the liquid phase portion of the high temperature regenerator during normal operation. , a step 102 of inputting the measured temperature _{t 2} of the measuring temperature _{t 1} and the gas phase of the liquid phase to the controller, comparing each temperature Request _{t 1} ≧ _{T 1} or _t 1> _{t 2} in operation, etc. Step 103, and if YES at step 103, it is determined that the liquid level exists at the position of the temperature sensor in the liquid phase portion.
04, if step 103 is NO, step 105 for obtaining t ₁ <T ₁ and t ₁ = t ₂ ;
If YES, step 106 is judged that there is no liquid level at the position of the temperature sensor in the liquid phase part, and step 10 where the opening of the control valve V ₁ is controlled by the judgment signal of step 106.
7, the flow rate of the solution is controlled and the liquid surface is held at a predetermined position.

The device is originally provided with a temperature sensor 20 for controlling and maintaining the device. First, the temperature relationship between the temperature T ₀ and T ₁ or T ₃ or T ₅ is input to the control system. By doing so, the temperature sensor for detecting the liquid level is sufficient at only one point in the liquid phase part or the gas phase part. The mounting position of the temperature sensor for measuring the liquid phase temperature is, for example, the position of the lower limit liquid level that can prevent the idle operation of the solution circulation pump, and the mounting position of the temperature sensor of the gas phase is to the refrigerant of the solution. It is necessary to consider such as setting the upper limit liquid level position that can prevent the contamination of the liquid.By installing multiple temperature sensors in the vertical direction at the liquid phase part or the gas phase part, the position of the liquid level level can be accurately measured. It is also possible to detect.

According to the present embodiment, since the temperature sensor detects the position of the liquid surface, the structure is simplified, and the reliability is high and the cost is low. Further, the control accuracy can be increased at a low cost by increasing the number of detected temperatures or by providing a control delay in terms of electric control. Then, it is possible to prevent the solution circulation pump from idling and to retain the solution for preventing the high-temperature regenerator and the low-temperature regenerator from being idle, or to prevent the solution from being mixed with the refrigerant due to the rise in the liquid level.

[0018]

According to the present invention, since the liquid level of the solution stored in each device is detected and controlled by the measured temperature, the structure is simplified, the control accuracy is improved, and the idling of the solution circulation pump is prevented. Also, it becomes possible to retain the solution for preventing emptying of the high temperature regenerator and the low temperature regenerator, or prevent the solution from being mixed with the refrigerant due to the rise of the liquid level.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a pressure-temperature diagram of the example shown in FIG.

FIG. 3 is a flowchart showing control steps of the embodiment shown in FIG.

FIG. 4 is a diagram showing a conventional technique.

[Explanation of symbols]

1 absorber 2 evaporator 4 condenser 5 solution circulation pump 11 high-temperature regenerator 12 low temperature generator 15 burners 20-26 Temperature sensor V ₁ ~V ₃ control valve

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F25B 15/00 306

Claims (2)

(57) [Claims] 1. A control valve connects the respective devices including a high-temperature regenerator, a low-temperature regenerator, a condenser, an evaporator and an absorber and circulates the solution to the liquid level of the solution stored in the respective devices. In an absorption chiller-heater to be controlled, temperature sensors are provided at two positions of a device that should be a gas phase and a liquid phase of each device, and the temperature sensor is used to indicate the liquid phase of each device. The temperature of the part to be in the vapor phase and the temperature of the part to be in the vapor phase are measured, and the measured temperature of the part to be in the liquid phase and the measured temperature of the part to be in the gas phase are compared with each other. controlled by detecting the position of the liquid surface of the device, which should be the liquid phase
If the measured temperature of the part is above the set temperature, or before
It is the liquid phase rather than the measured temperature of the part that should be in the vapor phase
When the temperature measured at the desired part is high, the part that should be in the liquid phase
Liquid level is found at the position of the temperature sensor that measures the temperature
And the measured temperature of the part that should be in the liquid phase is the set temperature.
And the measured temperature of the part that should be in the liquid phase below
When the measured temperature of the part to be in the gas phase is equal,
Of the temperature sensor that measures the temperature of the part that should be the liquid phase
An absorption chiller-heater characterized by determining that there is no liquid level at a position . 2. The mounting position of the temperature sensor for measuring the temperature of the portion that should be in the liquid phase is the lower limit liquid level level that can prevent the idle operation of the solution circulation pump, and the position of the portion that should be in the gas phase should be set. mounting position of the temperature sensor for measuring the temperature, the absorption chiller heater according to claim 1, characterized in that the anti-upper-limit liquid level position of the contamination of the coolant solution.