JPH0646125B2 - Control method for double-effect absorption refrigerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control method for a double-effect absorption refrigerator, and more specifically, to the opening degree of an opening adjustment valve provided at a steam drain outlet of a low temperature regenerator. The present invention relates to a method for controlling an absorption refrigerating machine that can prevent condensation of exhaust gas on the heat collecting surface by adjusting the above.

[Conventional technology]

Some absorption chillers capable of obtaining cold water or hot water by exchanging heat generated during repeated evaporation and condensation of an aqueous solution of lithium bromide have a high temperature regenerator equipped with a heating device. .

In such an absorption refrigerator, a large amount of vapor and a high concentration of absorption liquid are obtained from the rare absorption liquid of lithium bromide, so that the performance of the absorption refrigerator can be improved.

By the way, the burnup in the heating device is designed to be controlled according to the obtained cold water or hot water,
When the load is high, the heating in the high temperature regenerator is strengthened, and the temperature of the exhaust gas discharged through the high temperature regenerator becomes high.

On the other hand, when the load is low, the burnup in the heating device is weakened, so the temperature of the exhaust gas flowing through the high temperature regenerator is also lowered. This is not a problem if the fuel used in the heating device contains a small amount of sulfur, but if it contains a significant amount of sulfur, the exhaust gas accompanied by sulfurous acid gas and unburned gas will become hot. It will pass through the regenerator.

It is well known that the dew point temperature of fuel gas varies depending on the amount of sulfur contained in the fuel. For example, in the case of fuel containing 1% by weight of sulfur, dew condensation occurs at about 140 ° C. The dew point temperature will also be low.

[Problems to be Solved by the Invention]

As described above, if a fuel having a high sulfur content is used, dew condensation is likely to occur on the heat collecting surface of the high temperature regenerator and the heat collecting surface of the high temperature regenerator when the temperature of the exhaust gas is lowered due to a low load.

When sulfurous acid gas dissolves in the dew, it turns into dilute sulfuric acid, and there is a problem that a high temperature regenerator made of iron-based metal is corroded in a short time.

In addition, the unburned carbon content adheres to the dew condensation and the exhaust gas passage is narrowed, the performance of the blower for heating is inevitably deteriorated, and there is also a problem that the combustion abnormality is induced and the generation of unburned carbon rapidly increases. .

In order to avoid such a situation, conventionally, as a heating fuel in the high temperature regenerator, high-quality heavy oil or kerosene having a low sulfur content, or city gas is used. However, there is a problem that the fuel cost increases, and improvement thereof is desired.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to use a fuel having a large amount of components such as a sulfur content that lowers the dew point of exhaust gas in a heating device, to prevent corrosion or uncorrosion due to dew condensation in a high temperature regenerator. It is an object of the present invention to provide a method for controlling a double-effect absorption refrigerating machine which can avoid the adhesion of fuel carbon content and operate with an inexpensive fuel.

[Means for Solving the Problems]

INDUSTRIAL APPLICABILITY The present invention is applied to an absorption refrigerator including an absorption heat pump having a high temperature regenerator equipped with a heating device in addition to an absorber, a condenser, an evaporator and a low temperature regenerator.

The feature is that, with reference to FIG. 1, the fact that the heat collecting surface of the high temperature regenerator 7 and the temperature of the exhaust gas fell undesirably due to the low load during cooling was attached to the high temperature regenerator 7. When the temperature sensor 12 or the temperature sensor 12 attached to the high temperature regenerator 7 or the pressure sensor provided in the gas-liquid separator 17 into which the absorption liquid is introduced from the high temperature regenerator 7, detects the absorption liquid to the high temperature regenerator 7. The opening adjustment valve provided in the steam drain outlet for sending the refrigerant vapor introduced from the high temperature regenerator 7 or the gas-liquid separator 17 from the heat transfer tube of the low temperature regenerator 3 to the condenser 5 in the low temperature regenerator 3. By narrowing the opening of 19, the temperature in the high temperature regenerator 7 is increased to raise the temperature of the absorbing liquid and the heat collecting surface in the high temperature regenerator 7, and the exhaust gas temperature is raised to increase the heat collecting surface of the high temperature regenerator 7. Condensation of combustion exhaust gas in It is that you have to be able to stop.

[Action]

The pressure sensor 17 attached to the gas-liquid separator 8 or the temperature sensor 12 provided in the high temperature regenerator 7 to which the concentrated absorbent is supplied from the high temperature regenerator 7 and the refrigerant is separated from the concentrated absorbent as vapor.
When indirectly or directly detecting that the exhaust gas has reached the dew point temperature by, for example, the opening control valve 19 provided at the steam drain outlet for discharging the refrigerant vapor from the heat transfer tube of the low temperature regenerator 3 to the condenser 5. The opening is reduced. As a result, the amount of refrigerant vapor flowing out to the condenser 5 is reduced.

Since the burnup in the heating device 6 is maintained as long as the temperature at which cold water or hot water is taken out does not change, the high temperature regenerator 7 and the gas-liquid separator 8 are provided by narrowing the outlet of the refrigerant vapor.
The steam pressure inside rises. In response to this, the temperature of the absorbing liquid in the high temperature regenerator 7 is raised, the temperature of the heat collecting surface is also raised, and the exhaust gas temperature of the high temperature regenerator 7 is raised.

As a result, the temperature of the heat collecting surface of the high temperature regenerator 7 is maintained at the dew point temperature of the combustion exhaust gas or higher, and obstacles due to corrosion on the heat collecting surface of the high temperature regenerator 7 and an increase in the amount of unburned carbon adhering are avoided. It

〔Example〕

Below, the control method of the double-effect absorption chiller according to the present invention will be described in detail based on an embodiment of the double-effect absorption chiller-heater that performs absorption refrigeration.

FIG. 1 is an overall system diagram of an example of an absorption chiller-heater to which the control method of the present invention is applied. An absorber 2, an evaporator 5, a low-temperature regenerator 3 and a condenser 4 are formed in vacuum containers 1a and 1b, respectively. In addition to these, a high temperature regenerator 7 having a heating device 6 is provided.

Furthermore, a gas-liquid separator 8 that separates the vapor and the concentrated absorption liquid from the absorption liquid in the gas-liquid mixed state heated by the high temperature regenerator 7,
It is provided between the low temperature regenerator 3. In the high temperature regenerator 7, the heating device 6 burns the fuel, so that the exhaust gas is discharged from the exhaust pipe 9.

In addition to the above configuration, in order to prevent dew condensation in the high temperature regenerator 7, a temperature sensor 12 is attached to the high temperature regenerator 7, and the temperature of the exhaust gas or heat collecting surface is a dew point temperature based on the sulfur content of the fuel used. It has become possible to detect that it has become.

An opening adjustment valve 19 is attached to the steam drain outlet of the heat transfer tube of the low temperature regenerator 3 that leads the absorbing liquid to the high temperature regenerator 7. The vapor drain outlet is for sending the refrigerant vapor from the heat transfer tube of the low temperature regenerator 3 to the condenser 4 during the refrigerant operation, but it can be drained to the evaporator 5 (not shown) during the heating operation. It has become.

The refrigerant vapor supplied to the heat transfer tube of the low temperature regenerator 3 is separated from the concentrated absorbing liquid in the high temperature regenerator 7 or the gas-liquid separator 9. Therefore, when the opening of the opening adjustment valve 19 is reduced, the flow resistance of the drained refrigerant vapor increases, the vapor pressure in the gas-liquid separator 8 rises, and the pressure in the high temperature regenerator 7 also increases. become.

That is, the opening adjustment valve 19 is adapted to change the drain amount by the signal from the temperature sensor 12 described above. The decrease in exhaust gas temperature can also be detected indirectly. Since the pressure of the refrigerant vapor is proportional to the solution temperature, instead of the above temperature detection, a concentrated absorbent is supplied from the high temperature regenerator 7 to separate the refrigerant from the concentrated absorbent as vapor, or the vapor thereof. The outflow of the refrigerant vapor can be adjusted by a signal from the pressure sensor 17 provided in the pipe 16.

In the present embodiment, 25 in the figure is a rare absorbent 2 in the absorber 2.
A low temperature heat exchanger that heats 6 and a high temperature heat exchanger 27 that heats the absorbing liquid flowing through the pipe line 13.

The absorption liquid from the low-temperature regenerator 3 and the concentrated absorption liquid from the gas-liquid separator 8 are supplied to the heating side of each heat exchanger, and the absorption liquid after radiating heat in the heat exchangers 25 and 27 is absorbed by the absorber. It is supposed to be sprayed within 2. Reference numerals 28 and 29 are absorption liquid pumps, and 30 is a refrigerant pump.

In the absorption chiller-heater having such a configuration, predetermined control is performed in the following operating states to prevent dew condensation on the heat collecting surface of the high temperature regenerator 7.

In the cooling cycle, when the load of the absorption chiller-heater is large, the burnup in the heating device 6 is high even if oil containing a large amount of sulfur is used as the fuel. Therefore, the exhaust gas is not condensed on the heat collecting surface of the high temperature regenerator 7.

On the other hand, when the load decreases, the burnup of the heating device 6 in the high temperature regenerator 7 decreases, and the heat collecting surface of the high temperature regenerator 7 and the temperature of the combustion exhaust gas also decrease. Whether the temperature sensor 12 provided in the high temperature regenerator 7 detects that the dew point temperature has been reached,
When the pressure sensor 17 detects that the pressure has dropped below a predetermined pressure, the opening degree of the opening degree adjustment valve 19 provided at the steam drain outlet of the low temperature regenerator 3 is reduced according to the detection signal.

As a result, it is supplied from the high temperature regenerator 7 and the gas-liquid separator 8,
The outflow of the refrigerant vapor to the condenser 5 after heating the absorbing liquid in the low-temperature regenerator 3 is partially regulated. Therefore, the pressure of the refrigerant vapor increases and the vapor pressure in the gas-liquid separator 8 increases. Thereby, the high temperature regenerator 7 or the gas-liquid separator 8
The temperature and the temperature of the solution are increased, and the solution temperature corresponding to the pressure is maintained at 140 ° C. on the heat collecting surface.
Condensation on the heat collecting surface is prevented.

If such control is appropriately performed when the load is reduced, dew condensation of exhaust gas flowing through the high-temperature regenerator 7 is avoided even if the fuel contains a large amount of sulfur, and even if an inexpensive fuel is used, Problems such as corrosion due to dew condensation can be prevented.

Note that the absorption chiller-heater is not limited to the illustrated example, and as long as it includes a high-temperature regenerator having a heating device that burns fuel, an absorption chiller including an absorption heat pump other than the example is also included in the present invention. The invention can be applied.

〔The invention's effect〕

As described in detail above, according to the present invention, the steam pressure or solution temperature of the high temperature regenerator is changed to the steam drain discharged from the steam drain outlet of the low temperature regenerator according to the exhaust gas temperature of the high temperature regenerator. Since the pressure is applied and the pressure or temperature is maintained above the set value, it is possible to prevent the exhaust gas of the heating device and the heat collecting surface of the high temperature regenerator from falling below the dew point temperature.

Therefore, the dew condensation of the exhaust gas flowing through the high temperature regenerator is avoided, and the effect of preventing the damage due to the corrosion of the heat collecting surface and the adhesion of unburned carbon content due to the dew condensation is exerted.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of a double-effect absorption chiller-heater to which the present invention is applied. 2 ... Absorber, 3 ... Low temperature regenerator, 4 ... Condenser, 5 ...
… Evaporator, 6 …… Heating device, 7 …… High temperature regenerator, 8 ……
Gas-liquid separator, 12 ... Temperature sensor, 17 ... Pressure sensor, 19 ... Opening adjustment valve.

Claims (1)

[Claims] 1. An absorption chiller including an absorption heat pump having a high temperature regenerator equipped with a heating device in addition to an absorber, a condenser, an evaporator, and a low temperature regenerator, wherein the high temperature regeneration is performed due to a low load during cooling. When a temperature sensor attached to the high-temperature regenerator or a pressure sensor provided in the gas-liquid separator into which the absorbing liquid is introduced from the high-temperature regenerator is detected when the heat collecting surface of the regenerator and the temperature of the exhaust gas have dropped undesirably. Provided in the vapor drain outlet part for sending the refrigerant vapor introduced from the high temperature regenerator or the gas-liquid separator in the low temperature regenerator for guiding the absorbing liquid to the high temperature regenerator from the heat transfer tube of the low temperature regenerator to the condenser By narrowing the opening of the opening adjustment valve, the pressure in the high temperature regenerator is increased to raise the temperature of the absorbing liquid and heat collecting surface in the high temperature regenerator, and the exhaust gas temperature is raised to increase the temperature of the high temperature regenerator. In terms of heat A method for controlling a double-effect absorption refrigerating machine, characterized in that dew condensation of combustion exhaust gas can be prevented.