JPH0198864A - Method of controlling quantity of absorbing solution circulated in absorption refrigerator - Google Patents

Abstract

PURPOSE: To shorten a time required for control while simplifying a control process in an absorption refrigerating machine by a method wherein a load signal is detected to adjust the travel of a control valve of a heating means based on the load signal and the resulting travel signal is detected to control the number of revolutions of an absorbing liquid pump based on the signal. CONSTITUTION: A load of an absorption refrigerating machine is detected to adjust the travel of a control valve 32 of a heating means 7 based on the load signal to decrease or increase the supply quantity of a fuel while the travel of the control valve 32 is detected. Moreover, the number of revolutions of absorbing liquid pumps 13 and 14 is increased or decreased based on the resulting travel signal so that the delivery quantities of the absorbing liquid pumps 13 and 14 are controlled to be optimal to a set load. This control requires no feedback from an object to be controlled to allow quick determination of the supply of energy and the delivery quantities of the absorber pumps 13 and 14 thereby achieving a higher astringent rate and a shorter control time.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the circulation amount of absorption liquid in an absorption refrigerator, and more specifically, a method for controlling the circulation amount of absorption liquid circulating in the internal and external channels of an absorption refrigerator. This invention relates to a control method realized with a simple configuration.

[Prior art]

In an absorption refrigerator, cold water is obtained by giving and receiving heat generated during repeated evaporation and condensation of a lithium bromide aqueous solution.A large amount of steam and high concentration absorption liquid are produced from a dilute lithium bromide absorption liquid. As a result, the performance of the absorption refrigerator can be improved.

As an example, there is a multiple effect absorption refrigerator described in Japanese Patent Publication No. 53-30534. In this type of absorption refrigerating machine, as shown in FIG. It absorbs the refrigerant vapor that is present, becomes a dilute absorption liquid, and is pumped from the bottom into the pipe 22 by the dilute absorption liquid pump 13.
After being heated in the first heat exchanger 6, it is sent to the low-temperature regenerator 4.

By being further heated in the low-temperature regenerator 4, the refrigerant evaporates and the absorption liquid is concentrated to an intermediate concentration absorption liquid. After that, it is sent to the high temperature regenerator 5. The intermediate concentration absorption liquid is further heated in the high-temperature regenerator 5 to evaporate the refrigerant and concentrate it to a high concentration, thereby enhancing its ability to absorb refrigerant vapor. Then, the concentrated absorption liquid is sent from the high-temperature regenerator 5 to the low-pressure near-vacuum absorber 2 using the pressure difference and positional difference. The concentrated absorption liquid absorbs the refrigerant vapor from the evaporator 1 and becomes a dilute absorption liquid.Meanwhile, in the evaporator 1, the refrigerant condensed in the condenser 3 evaporates and removes the heat of evaporation from the cold water to cool the cold water. do.

Not only in such absorption refrigerators but also in those without a high-temperature regenerator, the dilute absorption liquid pump 13 and the like are driven by an induction motor and a constant rotation speed is maintained, so that the absorption refrigerator can be operated at partial load. It is also retained and the excess amount of absorption liquid is circulated. Recently, there has been a demand for energy-saving operation even under partial loads, and it is desired to increase or decrease the discharge amount of the pump described above in accordance with the load. An example of means for making this possible is pump control using the cascade regulator 41 and inverter 30 as described in FIG. 6 above.

On the outlet side of the evaporator tube 1a of the evaporator 1, the temperature of the cold water is detected by a temperature detector 31, and the temperature signal is sent via a regulator 40 to a control valve 32 and a cascade regulator 41 that control the amount of fuel to be supplied. is input.

In response to the input signal, the control valve 32 changes the opening degree to increase or decrease the amount of fuel supplied, and furthermore, a signal from the cascade regulator 41 is input to the inverters 30A and 30B, and the absorption liquid pump 13 and the intermediate concentration absorption liquid pump 14 are inputted. The power frequencies supplied to the motors are both changed. therefore,
The rotational speed of both pumps 13, 14 is driven in proportion to the frequency, and the discharge amount thereof is reduced, for example. And heating source 7
Flowmeters 43 to 45 measure the fuel gas amount, heavy oil amount, and discharge amount in the pipes 22 and 24, and the measured signals are fed back to the cascade controller 41, which provides the optimal fuel supply commensurate with the load at that time. Amount and absorption liquid iJi
! It is considered to be the r-ring quantity. As a result, energy consumption can be kept to a minimum, and power consumption and heating energy can be reduced.

[Problem that the invention seeks to solve]

In the above-described cascade control method, the fuel flow rate and discharge amount are fed back to the cascade regulator 41 and undergoes a complicated process. Therefore, although accurate control is possible, there is a problem in that the feedback control time becomes long. Furthermore, there is a problem that the number of control devices increases and the cost becomes high.

The present invention was made to solve the above-mentioned problems.
The purpose is to provide a method for controlling the circulation amount of absorption liquid in an absorption refrigerator that simplifies the control process, shortens the time required for control, and enables inexpensive and highly accurate control.

[Structure of the invention]

The features of the absorption liquid circulation amount control method in an absorption refrigerator of the present invention will be explained with reference to FIG. Absorber 2, regenerator 4
, 5, an absorption refrigerator which has a condenser 3 and an evaporator 1, and which circulates the absorption liquid by an absorption liquid pump 13. The opening degree of the control valve 32 of the heating means 7 is adjusted based on the load signal, the opening degree signal is detected, and the rotation speed of the absorption liquid pump 13, 14 is controlled based on it. It is.

[For production]

The load of the absorption refrigerator is detected, and the opening degree of the control valve 32 of the heating means 7 is adjusted based on the load signal, and the amount of fuel to be supplied is increased or decreased, and the opening degree of the control valve 32 is detected. Furthermore, since the rotational speed of the absorption liquid pump 13.14 is increased or decreased based on the opening degree signal, the discharge amount of the absorption liquid pump 13.14 is controlled to be optimal for the set load.

This control has no feedback from the controlled object, and the energy supply according to the load signal and the absorber pumps 13, 1
The discharge amount of No. 4 is quickly determined. As a result, the convergence speed is accelerated and the control time is shortened.

〔Effect of the invention〕

The absorption liquid circulation amount control method in an absorption refrigerator of the present invention is as follows:
The opening degree of the control valve of the heating means is adjusted based on the detected load signal, and the rotation speed of the absorption liquid pump is controlled based on the detected opening signal, so feedback operation is omitted. It is possible to simplify the control process and shorten the time required for control. In addition, with the simplification of the control process, the number of expensive parts can be omitted, making it possible to realize inexpensive control with high precision.

〔Example〕

The present invention will be explained in detail below based on examples thereof.

FIG. 1 shows a system diagram and a control system diagram of an absorption refrigerator that is an embodiment of the present invention, in which an evaporator 1 and an absorber 2 are installed in the lower low pressure chamber, and a condenser 3 is installed in the upper high pressure chamber. and a low-temperature regenerator 4 are formed, each of which is equipped with a group of tubes through which the required fluid flows. 5 is a high temperature regenerator, 6 is a first heat exchanger provided in the dilute absorption liquid supply pipe 21 from the absorber 2 to the low temperature regenerator 4, 8 is a second heat exchanger, 12 is a refrigerant pump, and 13 is a rare 14 is an intermediate concentration absorption liquid pump, 15 is a refrigerant liquid reservoir, and 16 is a dilute absorption liquid reservoir.

In this figure, the refrigerant vapor that is evaporated by the cooling effect in the evaporator 1 is absorbed by the absorption liquid in the absorber 2, and the absorption liquid decreases in concentration and loses its absorbing power, and is stored in the diluted absorption liquid reservoir 16 at the bottom. . This diluted absorption liquid is transferred to the pipe line 22 by the diluted absorption liquid pump 13.
, the dilute absorption liquid is sent to the low temperature regenerator 4 via the first heat exchanger 6 and the dilute absorption liquid supply line 21, and the sent dilute absorption liquid is transferred to the low temperature regenerator 4 where the refrigerant vapor generated in the high temperature regenerator 5 is It is heated by the introduced heating tube 4a. When the dilute absorption liquid is heated in the low temperature regenerator 4 and the refrigerant is evaporated and separated, the concentration of the dilute absorption liquid increases, while the evaporated refrigerant is transferred to the condenser pipe 3 in the condenser 3.
It is condensed by the cooling water in a.

The dilute absorption liquid with increased concentration becomes an intermediate concentration absorption liquid, which flows through the pipes 23 and 24 by the intermediate concentration absorption liquid pump 14, and is further heated in the second heat exchanger 8, and then passes through the pipes. 25
is introduced into the high temperature regenerator 5. At this time, the fuel supplied from the outside is burned in the heating means 7 provided in the high-temperature regenerator 5, and the exhaust gas is discharged from the exhaust stack 9, and the intermediate concentration absorption liquid is heated. The refrigerant evaporates and the absorption liquid becomes highly concentrated as the pressure increases.
It becomes a concentrated absorption liquid and increases absorption capacity. As mentioned above, the refrigerant vapor evaporated in the high-temperature regenerator 5 is used for heating in the low-temperature regenerator 4, and is condensed into a refrigerant liquid that is guided to the condenser 3, where it is cooled with cooling water and further raised to a temperature. The refrigerant drops and returns to the evaporator 1 through the pipe 26 together with the above-mentioned refrigerant liquid, where it evaporates to provide a cooling effect.

On the other hand, the concentrated absorption liquid concentrated in the high-temperature regenerator 5 is directed to the low-pressure absorber 2, which is close to vacuum, by using the pressure difference and positional difference between the pipe line 27, the second heat exchanger 8, and the pipe line 27, the second heat exchanger 8, 28, the first heat exchanger 6, and the conduit 29, during which it radiates heat in the heat exchangers 8 and 6, is dispersed from the dispersion device, and returns to the absorber 2 to perform an absorption action. In addition, the evaporator tube l of the evaporator 1
A liquid to be cooled, that is, cold water, is flowing inside a.
The heating of the high-temperature regenerator 5 is adjusted based on a signal from a temperature detector 31, which will be described later, and the cooling of the cold water is adjusted.

Cooling water 33 is in the absorber tube 2a of the absorber 2 as shown by the arrow.
The lower the temperature of the absorption liquid that is flowed and the absorption liquid that is sprinkled on the tube surface of the absorber 2, the greater its absorption capacity, so that the absorption liquid is cooled and absorbs the cooling vapor generated in the evaporator 1. Also, condenser 3
Cooling water is also flowed into the condenser pipe 3a to cool the cooling steam from the low-temperature regenerator 4 and the refrigerant drain. By the way, since the pressure at the bottom of the absorber 2 of an absorption refrigerator is extremely low, non-condensable gas tends to accumulate, so non-condensable gas can be discharged to the outside from the bottom of the absorber 2 using a bleed device. It has become. 34 is a bleed pump for discharging the air.

A temperature detector 31 is attached to the outlet side of the evaporator tube 1a of the evaporator 1 of such an absorption refrigerator to detect the temperature of cold water for detecting the load of the absorption refrigerator. on the other hand,
A regulator 40 constituting a control device is provided, and a load signal detected by the temperature detector 31 is input to the regulator 40. Note that if a dial type regulator is used as the regulator 40, the settings can be changed for each refrigerator. This outputs a signal that changes the opening degree of the control valve 32 based on the load signal detected by the temperature sensor 31. By adjusting the opening degree, the amount of fuel gas and heavy oil supplied from the outside to the heating means 7 is increased or decreased.

A potentiometer 46 is attached near the control valve 32 to detect its opening degree. On the other hand, an inverter 3 is used to change the rotation speed of the absorption liquid pump 13 and the intermediate concentration absorption liquid pump 14.
0 is set.

Based on the opening signal of the control valve 32, the inverter 30 increases or decreases the power frequency supplied to the induction motor that drives the pump. Therefore, the rotational speed of each pump 13, 14 is changed, and the discharge amount is reduced, for example, in accordance with the load at that time.

With the control system having such a configuration, the optimal amount of fuel to be supplied and the amount of discharge can be quickly achieved compared to the feedback control shown in FIG. Its configuration will be explained with reference to FIG. A temperature signal detected by the temperature detector 31 is processed by the regulator 30, and the opening degree of the control valve 32 is calculated.

The opening signal is output, and a desired amount of fuel is supplied to the heating means 7 via the control valve 32. Thereby, the intermediate concentration absorption liquid is heated in accordance with the load at that time in the high temperature regenerator 5. On the other hand, the opening degree of the control valve 32 is directly detected by the potentiometer 46 and converted into a current signal by the resistance current converter 47. The signal is subjected to lower limit and gain bias adjustment by an inverter adjuster 48. The output signal is input to the inverter 30 to change the power frequency.

The electric power changes the rotational speed of the induction motor, which changes the pump's discharge volume. In this way, the circulation amount of the absorption liquid is selected according to the opening degree of the control valve 32 at that time. The adjustment operation in the inverter regulator 48 will be briefly explained with reference to FIGS. 3 and 4. As shown in Figure 3,
In principle, the change in the amount of absorbed liquid circulating as the supplied fuel meter increases or decreases is proportional to the straight line A passing through the origin. by the way,
Depending on the refrigerator, the theoretical straight line A may be deviated from the theoretical straight line A to become a straight line B with less slope, and the slope may increase or decrease along a straight line with a different slope. On the other hand, if the absorption liquid circulation amount decreases to 20% or less, the control of the absorption liquid circulation (2) tends to become unstable. To avoid this, the amount of fuel supplied is reduced by 20%.
It is necessary to set the lower limit of the absorption liquid circulation amount so that the absorption liquid circulation amount is maintained at 20% even if the absorption liquid circulation amount decreases to below. Therefore, the inverter regulator 48 sets a lower limit value for the circulating amount and performs gain adjustment to change the slope such that an increase from the set value can be obtained. Therefore, the opening signal of the control valve 32 is controlled so that the absorption liquid circulation amount increases along the straight line B, for example.

On the other hand, since the discharge amount of a pump is generally proportional to the square of its rotational speed, the relationship between the power frequency and the circulation amount is as shown in FIG. 4. In this control, the frequency is changed to circulate IJj.
Since it is necessary to change the amount, it is desirable that the correlation between the two be able to maintain a linear relationship as much as possible. therefore,
When changing the frequency according to the load, the inverter articulator 48 needs to be adjusted so that a region with good linearity, such as region M, can be selected, and the inverter articulator 48 also has this function.

By performing such adjustment, the opening degree of the control valve 32 is adjusted based on the load signal, and the absorption liquid circulation amount of the diluted absorption liquid pump and the high concentration absorption liquid pump is adjusted based on the opening degree signal. is controlled. It does not employ feedback control and is extremely responsive. When the load decreases, the temperature of the cold water from the evaporator tube 1a decreases. The temperature is detected by the temperature detector 31, and control is performed according to the procedure described with reference to FIG. As a result, unlike the case of feedhack control, it is possible to simplify the control process and shorten the time required for control.

In addition, with the simplification of the control process, the number of expensive parts can be omitted, making it possible to realize inexpensive control with high precision.

The above has been described using an example of an absorption refrigerator having a high-temperature regenerator 5, but as shown in FIG. , can function similarly. of course,
Needless to say, the present invention can be applied to any type of absorption refrigerator as long as it has similar operations and functions.

[Brief explanation of the drawing]

Fig. 1 is a system diagram and control system diagram of an embodiment of the absorption refrigerator of the present invention, Fig. 2 is a block diagram realizing the control of the present invention, and Fig. 3 is a diagram showing the relationship between the amount of supplied fuel and the amount of circulating absorption liquid. 4 is a graph showing the relationship between frequency change amount and absorption liquid circulation amount, FIG. 5 is a system diagram and control system diagram in different embodiments, and FIG. 6 is a graph showing the relationship between the frequency change amount and the absorption liquid circulation amount. FIG. 2 is a system diagram and a control system diagram of an absorption refrigerator. 1--Evaporator, 2--Absorber, 3--Condenser, 4.5--Regenerator, 7--Heating means, 13.13A, 14--Absorption liquid pump, 32--Control valve.

Claims (1)

[Claims] (1) In an absorption refrigerator that has an absorber, a regenerator, a condenser, and an evaporator, and is designed to circulate the absorption liquid with an absorption liquid pump that sends out the absorption liquid, detecting a load signal,
The opening degree of the control valve of the heating means is adjusted based on the load signal, the opening degree signal is detected, and the rotation speed of the absorption liquid pump is controlled based on it. A method for controlling the circulation amount of absorption liquid in an absorption refrigerator.