JP3345610B2 - Cycle control method for absorption chiller / chiller / heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cycle control method in an absorption refrigerator and a chiller / heater, and more particularly, to an upper limit heating calorie in a regenerator or a heat concentration in a regenerator. The present invention relates to a cycle control method during a cooling operation in which the heating heat of the regenerator is controlled so as not to exceed the upper limit temperature of the absorbent.

[Conventional technology]

An absorption refrigerator or an absorption chiller / heater can take out cold water by changing the concentration of the absorption liquid circulating in the machine. For example, the structure of a double-effect absorption refrigerator includes an evaporator, an absorber, a low-temperature regenerator, and a condenser formed inside a main body, and a high-temperature regenerator outside the main body.

In the evaporator, the refrigerant liquid flowing down to the outer surface of the evaporator tube under high vacuum loses latent heat of evaporation and cools the cold water flowing in the evaporator tube. In the absorber, the refrigerant vapor generated in the evaporator is cooled by cooling water flowing in the absorber tube, so that the absorber vapor is absorbed and the inside of the body is kept at a high vacuum. In the low-temperature regenerator, the absorption liquid is heated and concentrated by the latent heat of the refrigerant vapor separated and evaporated in the high-temperature regenerator, and the refrigerant is separated and evaporated. In the high-temperature regenerator, the absorption liquid is heated in a vacuum and a part of the refrigerant is separated by evaporation. In the condenser, the refrigerant vapor evaporated in the regenerator is cooled and condensed by cooling water flowing in the condenser tube. The cooling water flowing in the absorber tube and the cooling water flowing in the condenser tube may be independent, but generally, the cooling water supplied to the absorber tube is After exiting the pipe, the cooling water that has been introduced into the condenser pipe and has performed a cooling function is discharged from the condenser pipe.

In such operations of the absorption refrigerator and the chiller / heater, not only the cooling operation but also the heating operation can be performed. In each case, the absorbent is heated by burning gas or oil or introducing high-temperature steam in each regenerator. And
In controlling the chilled water temperature, generally, the amount of heating heat in the high-temperature regenerator is proportionally controlled based on the chilled water outlet temperature or
PID control.

However, the cooling capacity of the absorption refrigerator or the absorption chiller / heater is affected by the temperature of the cold water supplied to or taken out of the evaporator and the temperature of the cooling water flowing from the absorber to the condenser. According to the above control, for example, when the temperature of the cooling water is higher than the control set value, for example, the temperature of the cooling water is low, the heating heat amount in the high-temperature regenerator becomes the maximum,
The absorption liquid inside is heated and concentrated to increase the concentration of the absorption liquid. However, since the temperature of the cooling water is low, the absorbent having a high concentration is cooled and the absorbent crystallizes at the outlet of the low-temperature heat exchanger.

In addition, even though the temperature of the cooling water is low, the fact that the temperature of the cooling water becomes higher than the control set value is not normal as the operation state of the absorption refrigerator. This is due to a small amount of air entering the vacuum vessel, and it is necessary to repair the absorption refrigerator. However, if the above control is maintained until repair, the absorption liquid crystallizes at the outlet of the low-temperature heat exchanger and the like, and the operation of the absorption refrigerator becomes impossible.

[Problems to be solved by the invention]

Conventionally, the following method has been adopted to prevent the above-mentioned adverse effects. One of them is disclosed in, for example, JP-A-2-75865.
As described in Japanese Patent Application Laid-Open Publication No. H10-260, there is a method of restricting the amount of heating heat in a high-temperature regenerator based on the temperature of cooling water. This absorption in the proper cooling operation state of the refrigerator, chiller, between the amount of heat at the inlet temperature t _c and the high-temperature regenerator of the coolant flowing through the condenser from the absorber Q ^*, Q ₀
Paying attention to the relationship of ^* = F ₀ (t _c ), the objective is achieved by controlling the amount of heating heat.

However, the operation state of the absorption refrigerator or the absorption chiller / heater is not affected only by the cooling water temperature, but the cooling water temperature, the high temperature regeneration temperature, that is, the temperature of the absorption liquid heated and concentrated in the high temperature regenerator, and further, It is also affected by the amount of heating heat in the high-temperature regenerator. Therefore, if the amount of heating heat in the high-temperature regenerator is adjusted only by the cooling water temperature as in this method, depending on the operating conditions,
The heating amount may be too limited, or the absorbing solution may be crystallized.

As another solution, for example, as described in JP-B-58-57668, the temperature of a rare absorbent from an absorber in which a highly concentrated absorbent is directly cooled by a low-temperature heat exchanger is used. Then, there is a method in which the refrigerant liquid regenerated in the condenser is released into the absorption liquid of the absorber via a refrigerant solenoid valve or the like so that the concentration is not abnormally increased. In this case, the concentration of the absorbing solution can be limited to prevent lithium bromide crystals in the absorbing solution at the outlet of the mixed concentrated solution at the low-temperature heat exchanger, but the regenerated refrigerant liquid is used as it is. Because of returning to the side, there is a problem that a loss of heating heat occurs.

The present invention has been made in view of the above-described problems, and its object is to limit the amount of heating heat in a regenerator too much, do not crystallize an absorbing liquid, and to generate a regenerated refrigerant liquid. An object of the present invention is to provide a cycle control method during a cooling operation in an absorption refrigerator or a chiller / heater which does not cause a loss of heating heat by returning to the absorption liquid as it is. In addition, the present invention is based on the problem that the absorption chiller which is in abnormal operation cannot be cooled if the absorption chiller in the abnormal operation is stopped. If it is desired to continue the operation, the absorption liquid is controlled so as not to crystallize at the outlet of the low-temperature heat exchanger during the provisional operation.

[Means for solving the problem]

INDUSTRIAL APPLICABILITY The present invention is applied to a cycle control method during a cooling operation in an absorption refrigerator / chiller / heater.

And has as its features, the temperature t _hg of the absorbing liquid which is heated and concentrated in the regenerator, the inlet temperature or outlet temperature of the chilled water in the evaporator t _r, the inlet temperature or outlet temperature of the cooling water flowing to the condenser from the absorber the t _c was respectively measured, and the difference thereof between the inlet temperature or outlet temperature t _c of the cooling water flowing from the temperature t _hg and absorber heat concentrated absorption liquid to the condenser in the regenerator based on, while calculating the cold water inlet temperature or outlet temperature t _r limit amount of heat than the difference between the Q ^* at an inlet temperature or outlet temperature t _c of the cooling water flowing to the condenser evaporator from the absorber, the fact in the regenerator the amount of heat Q measured or calculated, the case of [i] limit amount of heat Q ^* ≧ actual amount of heat Q, based on the cold water temperature t _r control the amount of heating in the regenerator, [ii] an upper limit amount of heat Q ^* In the case of the actual heating heat amount Q, control is performed so as to reduce the actual heating amount in the regenerator until the upper limit heating heat amount Q ^* is reached.

Moreover, with setting the upper limit amount of heat Q ^* previously in the regenerator, the inlet temperature or outlet temperature of the chilled water in the evaporator t _r, and the inlet temperature of the cooling water flowing to the condenser from the absorber or the outlet temperature t _c It was measured, the upper limit amount of heat Q ^*, than the difference between the cold water inlet temperature or outlet temperature t _r of the inlet temperature or outlet temperature t _c of the cooling water flowing to the condenser evaporator from the absorber, the regenerator (T _hg −t _c ) ^* between the temperature of the absorbing liquid to be heated and concentrated and the inlet or outlet temperature of the cooling water flowing from the absorber to the condenser, while the absorption heated and concentrated in the regenerator The difference between the actual temperature of the liquid and the actual temperature of the inlet or outlet of the cooling water flowing from the absorber to the condenser (t
_hg -t _c) calculates, in the case of [i] ^{_{(t hg -t c) * ≧}} (t hg -t c), based on the cold water temperature _{(t r)} to control the amount of heating in the regenerator , [ii] (t _hg -t _c) ^* <for (t _hg -t _c), the inlet of the cooling water flowing from the temperature t _hg and absorber of the absorption liquid which has been heated and concentrated in the regenerator to the condenser as the difference between the temperature or outlet temperature _{t c} does not exceed (t _hg -t _c) ^*,
The actual amount of heating in the regenerator can also be controlled.

(Operation)

In the proper cooling operation state of the absorption chiller-chiller, temperature t _r of the cold water inlet or outlet of the evaporator,
A certain function that is formulated between the inlet or outlet temperature t _{c of} the cooling water flowing from the absorber to the condenser, the temperature t _{hg of the} absorption liquid heated and concentrated in the regenerator, and the heat quantity Q ^* heated in the regenerator. You can find relationships. Therefore, cold water inlet temperature or outlet temperature t _r, the inlet temperature or outlet temperature t _c of the cooling _water, the temperature t _hg of the absorbing liquid which is heated and concentrated in the regenerator
From the appropriate heating heat in the regenerator (upper limit heating heat)
Calculate Q ^* . Then, by measuring the actual amount of heat Q in the regenerator, if the upper limit amount of heat Q ^* is not less than the actual amount of heat Q is the actual amount of heat in the regenerator based on the cold water temperature t _r proportional control or While PID control is performed, if the upper limit heating heat quantity Q ^* is smaller than the actual heating heat quantity,
The actual heating amount in the regenerator is reduced to the upper limit heating heat amount Q ^* to prevent operation in an abnormal state.

In the second invention, the upper limit value, for example, a multiple of 1 or less of the rated value is input to the appropriate heating heat amount Q ^* . From the cold water inlet temperature or outlet temperature t _r and the absorber in the evaporator and the inlet temperature or outlet temperature t _c of the cooling water flowing to the condenser, condensed from the absorber and the temperature of the absorption liquid is heated and concentrated in the regenerator Difference (t _hg −t _c ) ^* from the inlet or outlet temperature of the cooling water flowing to the vessel. Then, the temperature t _{hg of the} absorbing solution heated and concentrated by the regenerator and the inlet or outlet temperature t _{c of} the cooling water flowing from the absorber to the condenser are measured, and (t _hg −t _c ) ^* is the actual value. (T _hg −t
In the case of _c) above, while the proportional control or PID control the actual amount of heat in the regenerator based on the cold water temperature _{t r, (t hg -t c} ) * the actual (t _hg -t _c) If less than the actual (t _hg -t _c) has been calculated (t _hg
-T _c ) ^* Reduce the actual heating of the regenerator until below to prevent abnormal operation.

〔The invention's effect〕

According to the present invention, when the upper limit heating heat amount is smaller than the actual heating heat amount in the regenerator, the actual heating amount can be reduced to an appropriate heating heat amount, and operation in an abnormal state can be prevented. Therefore, too much restriction on the amount of heating,
The absorption liquid does not crystallize at the outlet of the low-temperature heat exchanger, and a loss of heating heat may be caused in a case where the regenerated refrigerant is returned to the absorption liquid as it is. Absent.

Also in the second invention, crystallization in an abnormal state can be prevented. This is suitable especially when it is necessary to lower the upper limit of the heating amount of heat in the regenerator beforehand, such as during low-load operation.

〔Example〕

Hereinafter, the cycle control method in the absorption refrigerator / chiller / heater of the present invention will be described in detail.

In a double effect absorption refrigerator or absorption chiller / heater, cold water can be taken out from an evaporator tube arranged in the evaporator due to a change in the concentration of the circulating absorption liquid. For this reason, the inside of the main body, which is in a vacuum state,
Evaporator, absorber, low temperature regenerator and condenser are provided,
Outside the main body, there are provided a high-temperature regenerator connected to the absorber and the low-temperature regenerator, and a high-temperature heat exchanger and a low-temperature heat exchanger for exchanging heat of the absorbent.

Then, the temperature sensor is arranged in the outlet of the arranged evaporator tubes in the evaporator, thereby making it possible to measure the outlet temperature t _r of the cold water. Also, of the absorber tube and condenser tubes arranged continuous to the condenser from the absorber, the temperature sensor is arranged in the outlet of the condenser tube, it is possible to measure the outlet temperature t _c of the cooling water it can. Further, a temperature sensor disposed in a flow path exiting from the high temperature regenerator high temperature regenerator or in a heated concentrated absorption liquid, so that the temperature t _hg of heated concentrated absorbent solution in the high-temperature regenerator is measured Has become. There are two types of high-temperature regenerators: a type that burns gas or oil and a type that supplies high-temperature steam. The heating source of the high-temperature regenerator is a calorimeter or a flow meter for gas, oil, or steam, and a control valve that supplies them. An opening meter or the like is provided, and the actual heating heat amount Q in the high-temperature regenerator can be measured or calculated.

By the way, in an appropriate cooling operation state of the absorption refrigerator / cooler / heater, the temperature t _{hg of the} absorption liquid heated and concentrated in the high-temperature regenerator and the inlet or outlet temperature t of the cooling water flowing from the absorber to the condenser. the difference between _c (t _hg -t _c), the difference between the cold water inlet temperature or outlet temperature t _r of the inlet temperature or outlet temperature t _c of the cooling water flowing to the condenser from the absorber evaporator (t _c - t _r) and the upper limit amount of heat ^{Q *} a certain relationship between the. This relationship can be formulated as follows.

^{_{Q * = F 1 (t hg}} -t c, t c -t r) ...... (1) where, for example, cold water outlet temperature _{t r,} the outlet temperature _{t c} of the cooling water, is heated and concentrated in the high-temperature regenerator The temperature _{thg of the} absorbing solution is measured by each temperature sensor, and an appropriate heating heat amount (upper limit heating heat amount) Q ^* in the high-temperature regenerator is calculated based on the equation (1). In addition, the actual heating heat Q in the high-temperature regenerator is measured by a calorimeter, or the flow rate is measured by a flow meter or an opening meter of a control valve, and the calorie is calculated.
In contrast, when the appropriate heating heat quantity Q ^* ≧ the actual heating heat quantity Q 2, normal control is performed. Its control, as described at the prior art, proportional control or PID (proportional-integral-derivative) the amount of heat by the cold water outlet temperature t _r may be controlled.

In the case of the appropriate heating heat amount Q ^* <the actual heating heat amount Q 2, the actual heating amount in the high-temperature regenerator is reduced to the appropriate heating heat amount Q ^* to prevent operation in an abnormal state. This enables optimal operation without waste.

Incidentally, data sampling is performed by each sensor or meter every few seconds, and by performing data processing each time, the heating amount is controlled, for example, every two minutes so as to satisfy a desired operating condition. In a high-temperature regenerator that burns gas or oil, the amount of combustion is adjusted, and in a type that supplies high-temperature steam,
Adjust the steam supply.

Note that t _r or the cold water inlet temperature in the evaporator, may be an inlet temperature of the cooling water flowing through t _c from the absorber to the condenser. Further, condensed t _r cold water inlet temperature in the evaporator, or the outlet temperature of the cooling water flowing through t _c to the condenser from the absorber, a t _r cold water outlet temperature in the evaporator, the t _c from the absorber It can also be the temperature of the inlet of cooling water flowing to the vessel.

By the way, the above equation (1) can be modified as follows. That is, (t _hg −t _c ) ^* = F ₂ (t _c −t _r , Q ^* ) (2)

In some cases, such as during low-load operation, it is necessary to lower the upper limit of the amount of heating heat in the high-temperature regenerator before operation. At that time, the upper limit value, for example, 0.8 times the rated value is input to the appropriate heating heat amount Q ^* in the above equation (2). Then, by measuring an outlet temperature t _c of the cooling water flowing from the cold water outlet temperature t _r and the absorber to the condenser in the evaporator, absorbing liquid that has been heated and concentrated in the high-temperature regenerator on the basis of the equation (2) the difference between the inlet temperature or outlet temperature of the cooling water flowing from the temperature and the absorber to the condenser (t _hg -t _c) ^* is calculated. In addition, the temperature t of the absorbing solution heated and concentrated by the high-temperature regenerator
The inlet temperature or outlet temperature t _c of the cooling water flowing to the condenser measured from _hg and absorber, In comparison, (t _hg -
In the case of _{^{t c) * ≧ t hg -t}} c is normal control, i.e., cold-water outlet temperature _{t r}
Control the amount of heating in the high-temperature regenerator by PI or PI
D control is sufficient.

(T _hg -t _c) ^* <in the case of t _hg -t _c, the actual (t _hg -t _c) is appropriate (t _hg -t
_c ) ^* Reduce the actual heating of the high temperature regenerator until below to prevent operation in abnormal conditions. As a result, proper operation can be performed within a range in which restrictions are added without waste.

Incidentally, or the cold water inlet temperature t _r in the evaporator, may also be a like inlet temperature of the cooling water flowing through t _c from the absorber to the condenser are the same as those described above.

Incidentally, this control is applied to the cycle control when the absorption refrigerator or the absorption chiller / heater is operated in the cooling operation, and is not applied to the heating operation, and is not necessary.

Although the above description has been made with reference to the double-effect absorption refrigerator / chiller / heater, the present invention can also be applied to a single-effect absorption refrigerator / cooler / heater without a high-temperature regenerator. In that case, a temperature sensor is provided in the regenerator or in a flow path from the regenerator for the heat-concentrated absorbent, and the temperature of the heat-concentrated absorbent in the regenerator is measured. High-temperature steam or the like is supplied to the regenerator, but a flow meter or an opening meter of a control valve may be installed at a heating source of the regenerator to calculate an actual heating heat amount in the regenerator. Is
This is the same as in the case of the high-temperature regenerator described above.

Claims (2)

(57) [Claims] In a cycle control method during a cooling operation in an absorption refrigerator or a chiller / heater, a temperature ( _thg ) of an absorption liquid heated and concentrated in a regenerator,
The inlet temperature or outlet temperature (t _r ) of the chilled water in the evaporator and the inlet temperature or outlet temperature (t _c ) of the chilled water flowing from the absorber to the condenser are respectively measured. The difference between the temperature (t _hg ) of the heated and concentrated absorbent and the inlet or outlet temperature (t _c ) of the cooling water flowing from the absorber to the condenser, and the inlet of the cooling water flowing from the absorber to the condenser. The upper limit heating heat quantity (Q ^* ) is calculated from the difference between the temperature or the outlet temperature (t _c ) and the inlet or outlet temperature (t _r ) of the cold water in the evaporator, while the actual heating heat quantity (Q) in the regenerator is calculated. Measured or calculated, [i] When the upper limit heating heat quantity (Q ^* ) ≧ the actual heating heat quantity (Q), the heating quantity in the regenerator is controlled based on the cold water temperature ( _tr ), and [ii] the upper limit. Heating heat (Q ^* ) <Actual heating heat In the case of (Q), a cycle control method in an absorption refrigerator or a chiller / heater, wherein the actual heating amount in the regenerator is controlled so as to decrease to an upper limit heating heat amount (Q ^* ). 2. In a cycle control method during cooling operation of an absorption refrigerator or a chiller / heater, an upper limit heating heat quantity (Q ^* ) in a regenerator is set in advance, and an inlet temperature or an outlet of chilled water in an evaporator is set. temperature (t _r), and measures the inlet temperature or outlet temperature of the cooling water flowing to the condenser (t _c) from the absorber, and the upper limit amount of heat (Q ^*), flowing from the absorber to the condenser cooling From the difference between the inlet or outlet temperature of the water (t _c ) and the inlet or outlet temperature of the cold water in the evaporator ( _tr ), the temperature of the absorbent to be heated and concentrated in the regenerator and the flow from the absorber to the condenser while calculating the difference between the inlet temperature or outlet temperature of the cooling water (t _hg -t _c) ^* which, of the cooling water flowing from the actual temperature and the absorber of the absorption liquid which has been heated and concentrated in the regenerator to the condenser Entering Or calculate the actual difference between the temperature of the outlet (t _hg -t _c), a [i] (t _hg -t _c) ^* For ≧ (t _hg -t _c), cold water temperature _{(t r)} based on controlling the amount of heating in the regenerator, [ii] (t _hg -t _c) ^* <case of (t _hg -t _c), of the absorbing liquid which is heated and concentrated in the regenerator temperature (t _hg) and from the absorber so as not to exceed the difference between the inlet temperature or outlet temperature of the cooling water (t _c) flowing into the condenser a (t _hg -t _c) ^*, to control the actual amount of heat in the regenerator Cycle control method for absorption refrigerators and chiller / heaters, characterized by: