JPS59200165A - Controller for absorption heat pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention utilizes the heat generated when an absorption liquid absorbs a refrigerant to heat a heated fluid that is higher in temperature than a heat source fluid supplied to an evaporator. In other words, the generator and condenser operate at a lower temperature and lower pressure than the evaporator and absorber. Controls the amount of absorbed liquid circulating in the absorption heat pump (hereinafter referred to as the absorber for heat pumps) that extracts the energy from the absorber. related to a device for

(b) Prior Art Conventionally, in a heat pump dedicated absorber, as disclosed in Japanese Patent Application Laid-Open No. 58-31262, for example,
The flow rate of the absorbent flowing down from the absorber to the generator via the solution heat exchanger is small compared to the flow rate of the absorbent sent from the generator to the absorber by the solution pump, and the liquid level in the absorber's solution reservoir rises too much. In order to prevent the absorption liquid from overflowing from the absorber side to the evaporator side in case of Means for returning the absorption liquid to the generator are known.

However, in a heat pump dedicated absorber, for example, a lithium bromide aqueous solution is used as the absorption liquid, water is used as the refrigerant, and
When a heated fluid of about 130° C. is extracted using a heat source fluid of about 5° C., it is necessary to operate while maintaining the pressure difference between the absorber and the generator at about 400 mmHg during steady state.

Therefore, such conventional means maintain a liquid seal in the absorbent return pipe compared to single-effect absorption refrigerators, which are normally operated with a pressure difference of about 50*mHg between the absorber and the generator. This has the disadvantage that the liquid column for the heat pump must be thicker (compared to the -type dynamic absorption chiller), and the height of the absorber for heat pumps is higher than that of the absorber for heat pumps. Since the pressure difference between the absorber and the generator is large during steady operation, it takes a long time to reach steady operation from the start of operation ρ.Moreover, with conventional means, it takes a long time from the start of operation to the transition to steady operation. During this period, most of the absorption liquid sent to the absorber by the solution pump is returned to the solution reservoir of the generator through the absorption liquid return pipe, and then sent to the absorber by the solution pump again, and the circulation of the absorption liquid is repeated. , the absorption liquid is hardly concentrated, and the startup performance is poor.

(c) Purpose of the Invention The present invention has a seventh object to provide a control device that makes it possible to downsize a heat pump dedicated absorber, stabilize its operating performance, and improve its startup performance.

B) Structure of the Invention The present invention is a heat pump-dedicated absorber, in which a part of the absorption liquid sent from the generator to the absorber by a solution pump is introduced and driven by an ejector from the absorber ρ\ via a solution heat exchanger. The ejector is configured to suck the absorbent liquid flowing down to the generator, to promote the flow of the absorbent liquid from the absorber to the generator, and to facilitate the circulation of the absorbent liquid between the absorber and the generator. The system is configured to adjust the suction force of the ejector by controlling the flow rate of the absorption liquid introduced into the absorber with a control valve, and the amount of absorption liquid circulated between the absorber and the generator is controlled to stabilize operational performance. This makes it possible to improve performance during startup.

(E) The drawings of the embodiments show the control of the absorber exclusively for heat pumps of the present invention.
1” is a schematic configuration diagram showing an embodiment of the control device.
) is an upper shell consisting of an evaporator (2) and an absorber (3); (4)
is a lower shell consisting of a generator (5) and a condenser (6), (7) is a solution heat exchanger, these are a concentrated liquid pipe (9) with a solution pump (8), a tank liquid flow down pipe α0) , first refrigerant pump Ql)
Y refrigerant liquid return pipe (121, second refrigerant pump (13)
They are connected by a refrigerant liquid pipe α4) having a refrigerant and absorption liquid circulation path.

α9 is the heat supply for the evaporator (2), (161 is the generator (5)
heater.

αη is the heated device for the absorber (3), Ht-i condenser (6)
A heat supply pipe (α), a heating pipe (201), a heated pipe (2υ), and a cooling pipe C2 are connected to these, respectively. 211 allows heat source fluids such as waste steam and waste hot water discharged from chemical processes and other equipment to flow through the pipes to be heated (211). (The second part is operated by circulating a cooling fluid such as cooling water or cooling air, and the absorption liquid in the absorber (3) is exposed to heat generated when it absorbs the vaporized refrigerant from the evaporator (2). The heated fluid is heated to a temperature higher than the temperature of the heat source fluid supplied to the evaporator (2) and then taken out.

Further, (23) is an ejector inserted in the tank liquid flow down pipe (10), and this ejector has a concentrated liquid branch pipe (24) installed on the solution pump (8) discharge side of the concentrated liquid pipe (9). The ejector (transfer) that occurs when the absorbent liquid is introduced from the generator (5) to the ejector (c) through this concentrated liquid branch pipe.
) from the absorber (3) to the solution heat exchanger (
The absorption liquid flowing down to the absorber (3) is sucked in and the absorption liquid flowing down from the solution reservoir (c) of the absorber (3) is promoted. In addition, (g) is a control valve provided in the concentrated liquid branch pipe, and the opening degree of this valve is determined by a liquid level detector (S) that detects the liquid level in the solution reservoir (c) of the absorber (3). ) is controlled via the controller (C)'& the amount of absorption liquid introduced from the generator (5) to the ejector (C) is adjusted.
While adjusting the suction force of the absorber, the flow rate of the absorbent from the solution reservoir of the absorber (3) is adjusted, and the concentrated liquid pipe (9) is passed from the generator (5) to the absorber (3). The flow rate of the absorption liquid is also adjusted, so that the amount of circulation of the absorption liquid between the absorber (3) and the generator (5) is controlled. In addition, (2
0 is the venturi nozzle of the ejector (c).

Next, an example of the operation of the control device for a heat pump dedicated absorber having such a configuration will be described.

(4) Operation at start-up At the start of operation, the internal temperatures of the upper shell (1) and lower shell (4) are both close to (and almost equal to) the outside air temperature, and the pressure inside both vessels is also almost the same. Since the flow rate of the absorbent flowing down from the absorber (3) to the generator (5) is significantly smaller than the flow rate of the absorbent sent from the generator (5) to the absorber (3) by the pump (8), the absorption Solution reservoir in container (3) □
The liquid level of □□ begins to rise and shortly after the start of operation, this liquid level reaches the upper limit set water level of the liquid level detector (S), and the flow rate control valve (V) is controlled to be fully open. That is, the absorption liquid discharged by the solution pump (8) is transferred to the ejector (23).
2 is introduced into the absorber (3) by the suction action of this ejector.
) to the generator (5), increasing the flow rate, while the flow rate of the absorbent from the generator (5) to the absorber (3) decreases, increasing the flow rate from the generator (5) to the absorber (3). The amount of absorption liquid in and out of the tank is controlled so that it is almost balanced. As a result, the absorption liquid flows from the absorber (3) side to the evaporator (2).
The absorption liquid introduced into the ejector (c) and the absorbed absorption liquid are both prevented from overflowing to the side.
In 5), the absorption liquid is heated and concentrated in the heater ae, and heat exchange of the absorption liquid in the solution heat exchanger (7) is also performed well, and the solution is sent to the absorber (3) by the solution pump (8). The concentration and temperature of the absorption liquid increase rapidly and ρ・, and the refrigerant absorption capacity of the absorber (3) is demonstrated in a short time, and the temperature and pressure inside the upper shell (1) decrease in a short time. The temperature and pressure are closer to the steady state, improving performance at start-up.

Note that as the pressure and temperature inside the upper shell (1) approach a steady state, the pressure difference between the upper shell (1) and the lower shell (4) increases, and the pressure difference in the absorber (3) increases. When the amount of outflow of the absorption liquid increases relative to the amount of inflow at , and the liquid level begins to drop, the flow control valve is controlled in the closing direction by the signal from the liquid level detector (S), and the suction force of the ejector (C) is weakened. At the same time, the flow rate of the concentrated absorption liquid sent to the absorber (3) is increased.Then, while improving the refrigerant absorption capacity of the absorber (3), the generator (5) and the absorber ( 3) The amount of absorption liquid circulated during the period is controlled and the operation is shifted to steady state.

(Bl Operation when the thermal energy of the cooling fluid or heat source fluid fluctuates When the thermal energy of the cooling fluid or heat source fluid fluctuates, the internal temperature and pressure of the upper shell (1) or lower shell (4) change, and the upper shell As a result of the fluctuation in the pressure difference between (1) and the lower shell (4), in conventional means, the absorption liquid flows down from the absorber (3) to the generator (5) via the solution heat exchanger (7). The flow rate of the solution pump (8) fluctuates and the circulation of absorption liquid between the absorber (3) and the generator (5) is unbalanced, and in extreme cases, the solution pump (8)
) Cavitation and overflow of absorption liquid to the evaporator (2) side occur, and the performance of the heat pump dedicated absorber cannot be maintained stably.

On the other hand, in the device of the present invention, when the pressure difference between the upper shell (1) and the lower shell (4) fluctuates and the liquid level in the absorber (3) starts to change, the liquid level detector ( The opening degree between the flow control valves is controlled by the signal S), and the suction force of the ejector (C) is adjusted to adjust the flow rate of the absorption liquid, and the flow rate of the absorption liquid sent to the absorber (3). Result regulated, absorber (3)
It becomes possible to maintain a good balance in the circulation of the absorption liquid between the generator (5) and the generator (5), resulting in improved stabilization of performance compared to conventional means.

In addition, in the apparatus of the present invention, the liquid level detector (S) may be provided in the generator (5) instead of being provided in the absorber (3).

Of course, it is better to provide a liquid level detector (81) in the absorber (3) because it will be easier to measure the amount of absorbed liquid sprayed onto the heated device (17) of the absorber (3) and the absorption from the solution reservoir □□□ of the absorber (3). Since the amount of liquid flow can be directly controlled, it has the advantage of good followability of performance control.

In addition, instead of the liquid level detector (S), temperature detectors for the heat source fluid and cooling fluid, and detectors for the internal temperature and internal pressure of the upper and lower cylinders (1) and (4) are used to control the flow rate control valve (G). It is also possible to control the opening degree of the opening, or it is also possible to control it manually.

Furthermore, although not shown, an orifice may be provided at the inlet of the ejector (c) of the tank liquid flow pipe 0 (+1), or an appropriate number of baffles may be provided in the flow part of the flowing absorption liquid of the solution heat exchanger (7). It goes without saying that the pressure difference between the upper shell (1) and the lower shell (4) during steady state is maintained by means such as providing for the upper shell (1) and the lower shell (4).

(f) Effects of the Invention As described above, the present invention provides an absorber exclusively for heat pumps in which the absorption liquid sent from the generator ρ to the absorber by the solution pump is diverted and introduced into the ejector. While adjusting the flow rate of the absorbed liquid introduced, the suction force of the ejector is adjusted to adjust the flow rate of the absorbed liquid from absorber β on the upper shell side to the generator on the lower shell side, and at the same time from the generator to the absorber. Since the flow rate of the absorption liquid is also adjusted, it is possible to control the circulation of the absorption liquid between the absorber and the generator in a well-balanced manner, which helps stabilize performance.
It has the effect of improving performance at startup, and does not require an absorbent return pipe to prevent absorbent from overflowing to the evaporator when the liquid level in the absorber's solution reservoir rises too much, unlike conventional methods. Therefore, it becomes possible to reduce the height of the heat pump dedicated absorber, which helps in downsizing.

[Brief explanation of the drawing]

The drawing is a schematic configuration explanatory diagram of a control device for an absorption heat pump according to the present invention. (2)...Evaporator, (3)...Absorber, (5)
... generator, (6) ... condenser, (7) ... solution heat exchanger, (8) ... solution pump, (9) ...
Concentrated liquid pipe, (IQ... Tank liquid flow down pipe, (C)... Ejector, G4) - Branch concentrated liquid pipe, (Q... Controller, (S)... Liquid level detector , Leap...flow control valve.

Claims (1)

[Claims] (1) Cooling fluid is passed through the condenser, heat source fluid is supplied to the evaporator and generator, and heated fluid having a temperature higher than the heat source fluid temperature is taken out from the absorber through the generator, condenser, and evaporator. In an absorption heat pump in which an absorber and a solution heat exchanger are connected via piping to form a circulation path for refrigerant and absorption liquid, an ejector is inserted in the path of the absorption liquid flowing from the absorber to the generator via the solution heat exchanger. , and an absorption liquid branch path with a flow rate control valve is provided on the discharge side of the solution pump that sends the absorption liquid from the generator to the absorber, and this branch path is connected to the ejector to control the circulation amount of the absorption liquid. A control device for an absorption heat pump characterized by: