JP2007255839A - Low-water cut off control method for direct fired absorption refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-water cut off control method for a direct fired absorption refrigerating machine capable of controlling a degree of combustion of a direct fired heating means in accompany with fluctuation of a liquid level of absorbent in a regenerator, and preventing no-water burning. <P>SOLUTION: A normal operation is continued when a liquid level H detected by a liquid level detecting means is higher than a reference level L, and when the liquid level becomes lower than the reference level L at a certain point, and the low level is detected continuously three times, a signal is output to a fuel control valve from a controller to start closing motion. When high level more than the reference level L is detected three times at a time of the lapse of 60 seconds thereafter, the normal operation is recovered, but if not at the lapse of 60 seconds, combustion is stopped. When the high level is detected three times during seeing how it's going after the lapse of 60 seconds from the stop of combustion, the normal operation is recovered, but when the low level is continuously detected three times, abnormality stop is performed after the lapse of 60 seconds. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air-blowing prevention control method for a direct-fire absorption refrigerator.

  In general, an absorption refrigerator includes a regenerator, a condenser, an evaporator, and an absorber as basic components, and water vapor is generated by heating the thin absorption liquid returned from the absorber with the regenerator. The water vapor is sent to the condenser to be condensed and then evaporated by the evaporator, the refrigerant liquid returning from the load side is cooled by the latent heat accompanying the evaporation, and the load side is cooled by the refrigerant liquid. A cycle in which the concentrated absorbent is sent from the regenerator to the absorber, the water vapor evaporated in the evaporator is absorbed by the absorbent, and the thinned absorbent is returned from the absorber to the regenerator. Is repeated.

  In the regenerator, direct-fired heating means for burning fuel such as fuel gas or oil with a burner is usually used. In the regenerator, water vapor is generated by heating and boiling the low-concentration absorbent returned from the absorber as described above, but the liquid level of the absorbent in the regenerator varies during heating. In particular, if the liquid level is lower than the reference level, not only will there be a risk of emptying, but there is also a risk of crystallization due to excessive concentration of the absorbent. For this reason, it is required to control the degree of combustion of the direct fire type heating means with the fluctuation of the liquid level.

  Conventionally, for example, Patent Document 1 discloses a method of controlling the liquid level of an absorbing liquid in a regenerator. However, in the case of this Patent Document 1, a magnetostrictive liquid level gauge is installed in a liquid level detection box which is a double effect type absorption refrigerator and can be communicated with the inside of the high temperature regenerator. The level of the absorbing liquid in the high-temperature regenerator is measured by a meter, a control signal corresponding to the level of the liquid level is output from the control device to the absorbing liquid pump, and the number of revolutions of the absorbing liquid pump is controlled, The liquid level of the absorbing liquid of the high temperature regenerator is controlled.

Further, in Patent Document 2, there is a danger that the temperature of the high-temperature regenerator suddenly rises when the amount of the absorbing liquid in the high-temperature regenerator becomes too small. Therefore, the combustion refrigerator is stopped and the absorption refrigerator is immediately stopped. A liquid level control method is disclosed. However, in the case of this Patent Document 2, the control device calculates and calculates the moving average value of the liquid level based on the on / off signal output from the liquid level detecting means, and the frequency of the commercial power source is calculated based on this moving average value. It is converted by the frequency converter and the rotation of the absorbing liquid pump is controlled.
JP-A-6-201211 Japanese Patent Application Laid-Open No. 8-42934

  In Patent Document 1, by measuring the liquid level of the absorbing liquid in the high-temperature regenerator, the rotational speed of the absorbing liquid pump is controlled, and the pump life is extended by reducing the number of on / off times of the absorbing liquid pump. The main purpose is to change the liquid level of the absorbing liquid in the regenerator, and not to control the direct heating type heating means of the regenerator in accordance with the fluctuation of the liquid level. In Patent Document 2, it is possible to control the number of revolutions of the absorbent pump while using the liquid level detecting means for outputting an on / off signal, to reduce the number of on / off times of the absorbent pump and extend the life of the apparatus. The main purpose is to reduce the surface disturbance and improve the controllability, and it does not control the direct heating type heating means of the regenerator in accordance with the fluctuation of the liquid level.

  In view of this, the present invention provides a direct-fired absorption refrigerator that controls the degree of combustion of the direct-fired heating means in accordance with fluctuations in the liquid level of the absorbing liquid in the regenerator, and can prevent air-burning. An object of the present invention is to provide a method for preventing air blow of a direct-fire absorption refrigerator.

  In order to achieve the above object, an air-fire prevention control method for a direct-fire absorption refrigerator according to claim 1 of the present invention is an absorption refrigerator including a regenerator, a condenser, an evaporator, and an absorber. The regenerator includes a direct fire heating means, a liquid level detection unit communicating with the regenerator, and a liquid level detection unit provided in the liquid level detection unit, wherein the liquid level detection unit is lower than a reference level. The fuel control valve of the direct fire heating means is started to close when the level is detected, and the liquid level higher than the reference level is not recovered until a certain time has elapsed since the level lower than the reference level was detected. The combustion of the direct fire heating means is stopped at the time, and when the liquid level higher than the reference level is not recovered by the lapse of a fixed time after the combustion is stopped, an abnormal stop is performed.

  According to a second aspect of the present invention, in the method for preventing idling of an open flame absorption refrigerator according to the first aspect, when the liquid level detecting means detects a liquid level lower than a reference level, The present invention is characterized in that a low liquid level is detected a plurality of times in succession.

  According to a third aspect of the present invention, in the control method for preventing idling of the direct-fired absorption refrigerator according to the first aspect, the time when the reference level or higher is not recovered until a predetermined time elapses after the combustion is stopped. It is a time when a lower liquid level is detected a plurality of times in succession.

  According to a fourth aspect of the present invention, in the control method for preventing idling of the direct-fired absorption refrigerator according to the first aspect, the liquid level higher than the reference level is detected until a predetermined time elapses after the liquid level lower than the reference level is detected. When the liquid level is detected a plurality of times continuously, the normal operation is resumed.

  According to a fifth aspect of the present invention, in the method for preventing idling of the direct-fired absorption refrigerator according to the first aspect, the liquid level equal to or higher than the reference level is continuously applied a plurality of times until a predetermined time elapses after the combustion is stopped. When detected, it returns to normal operation.

  According to the first aspect of the invention, in the regenerator, when the liquid level detecting means detects a low level lower than the reference level of the absorbing liquid, the closing operation of the fuel control valve of the direct fire heating means is started. It is possible to prevent excessive combustion over time and to suppress crystallization of the absorbing liquid. Further, when the liquid level higher than the reference level cannot be recovered by the lapse of a certain time from the detection of the low level, the combustion of the direct fire heating means is stopped, so that it is possible to prevent the emptying. Further, when the liquid level higher than the reference level cannot be recovered by a certain time after the combustion is stopped, the abnormal stop is performed, so that the number of abnormal stops can be reduced as compared with the conventional case.

  According to the second aspect of the present invention, when the liquid level detecting means continuously detects a low level lower than the reference level of the absorbing liquid a plurality of times, the closing operation of the fuel control valve of the direct fire heating means is started. Therefore, the certainty with respect to the start of control can be improved. It is possible to eliminate the start of control when the liquid level detecting means detects a low level temporarily or intermittently, thereby suppressing frequent switching of the fuel control valve.

  According to the third aspect of the invention, when the liquid level detecting means continuously detects a low level lower than the reference level of the absorbing liquid a plurality of times, the abnormal stop is made. Therefore, the certainty against the abnormal stop can be improved. An abnormal stop when the liquid level detecting means detects a low level temporarily or intermittently due to an instability factor can be eliminated, thereby reducing the number of times of maintenance.

  According to the fourth aspect of the present invention, the closing operation of the fuel control valve of the direct fire heating means is started, and a high level that is equal to or higher than the reference level is continued until a certain time has elapsed since the low level detection of the liquid level detecting means. Thus, when it can be detected a plurality of times, the normal operation is resumed, so that the timing for returning to the normal operation can be advanced and the number of combustion stops can be reduced.

  According to the fifth aspect of the present invention, when a high level equal to or higher than the reference level can be continuously detected a plurality of times until a certain time has elapsed after the combustion is stopped, the normal operation is resumed. The number of abnormal stops can be reduced.

Next, embodiments of the present invention will be described with reference to the accompanying drawings, but the illustration of the overall configuration of the absorption refrigerator will be omitted.
FIG. 1 shows a schematic cross-sectional view of an essential part of an absorption refrigerator. Reference numeral 1 denotes a regenerator (a high-temperature regenerator in a double effect type), which is directly connected to a lower combustion heating chamber 1a surrounded by a double wall. A fire heating means 2 is provided, and an upper space chamber 1b is provided with a liquid level detection unit 3 having a part of the side wall as a partition, and a liquid level detection unit 4 is attached to the liquid level detection unit 3. ing.

  The liquid level detection unit 3 is composed of a box-shaped container, and a communication part 3a is provided in a partition wall near the bottom of the liquid level detection unit 3 so as to communicate with the heated absorbing liquid 5 in the regenerator 1, and Is provided with a communication portion 3b and communicates with the water vapor in the space 1b. As a result, the heated absorption liquid 5 in the regenerator 1 and the detected absorption liquid 6 in the liquid level detection unit 3 are at substantially the same liquid level and almost the same temperature, and the gas is generated in the combustion heating chamber 1a. Alternatively, when the heated absorbent 5 in the regenerator 1 is heated and boiled by burning a fuel such as oil and the water as the refrigerant is evaporated and separated, the detected absorbent 6 in the liquid level detector 3 is almost foamed. There is nothing.

  The liquid level detecting means 4 is constituted by, for example, a magnetostrictive liquid level gauge fixed and suspended on the top plate portion of the liquid level detecting unit 3, and the outline thereof will be described. A reference magnet 4b and a float magnet 4c disposed along the magnetostrictive line 4a are provided. By measuring the distance between the reference magnet 4b and the float magnet 4c, the level of the float magnet 4c, that is, the liquid to be detected is detected. The liquid level H of 6 can be detected with high accuracy. As described above, the detected absorbing liquid 6 of the liquid level detecting unit 3 hardly bubbles, so that the vertical movement of the float magnet 4c of the liquid level detecting means 4 is stabilized, and the liquid level H of the detected absorbing liquid 6 is set. It can be detected accurately. Further, the liquid level H detected by the liquid level detection unit 3 can be regarded as being equivalent to the substantial liquid level of the heated absorbent liquid 5 that boiled and bubbles in the regenerator 1. The liquid level detecting means 4 is not limited to the magnetostrictive liquid level gauge, and other conventional liquid level detectors may be used.

  The liquid level H measured by the liquid level detecting means 4 is converted into a signal and input to the control device 7, where the control device 7 performs a comparison operation with a reference level L registered in advance in the CPU. When it is determined as follows, an output signal is output from the control device 7 and the combustion control described below is executed. In FIG. 1, 8 is a fuel control valve for controlling the fuel supply to the direct fire heating means 2, and 9 is a temperature sensor provided in the liquid level detection unit 3, both of which are connected to the control device 7. It is connected.

  FIG. 2 shows one aspect of the method for controlling the air-blowing prevention of the direct-fire absorption refrigerator according to the present invention. The liquid level H in the liquid level detection unit 3 is measured by the liquid level detection means 4 at a certain period (for example, 5 seconds but not limited thereto). The normal operation is continued while the liquid level H in the liquid level detection unit 3 is maintained higher than the reference level L. For example, when the liquid level H becomes lower than the reference level L when the point P elapses, and the low level is detected a plurality of times (for example, three times but not limited thereto), the fuel from the control device 7 is detected. A signal is output to the control valve 8 to start the closing operation of the fuel control valve 8. The closing operation of the fuel control valve 8 is performed relatively slowly, whereby the combustion of the direct fire heating means 2 gradually becomes a low combustion state. The reason for detecting the low level multiple times in succession is that the high level above the reference level L may be recovered in a very short time after the low level is first detected. . As a result, it is possible to reliably perform the determination at a low level and to avoid frequent closing operation for the fuel control valve 8.

  The liquid level H becomes higher than the reference level L within a certain period of time (for example, 60 seconds, but is not limited thereto), for example, when the point Q has elapsed, and continuously several times (for example, 3 When a high level is detected (but not limited to this), a signal is output from the control device 7 to the fuel control valve 8 to switch to the opening operation, thereby returning to the normal operation. The normal operation is continued while the liquid level H in the liquid level detector 3 is maintained higher than the reference level L. The reason why the high level detection is continuously performed a plurality of times is that the low level may be dropped in a very short time after the first high level detection. As a result, it is possible to reliably determine the high level and to avoid frequent opening operation operations on the fuel control valve 8.

  Thereafter, for example, when the liquid level H becomes lower than the reference level L when the point R elapses, and the low level is continuously detected a plurality of times (for example, three times but not limited thereto), the control device 7 Then, the signal is output again to the fuel control valve 8 to start the closing operation of the fuel control valve 8. As described above, the closing operation of the fuel control valve 8 is performed relatively slowly, whereby the combustion of the direct fire heating means 2 gradually becomes a low combustion state. If the liquid level H remains at a low level below the reference level L until a low combustion state elapses for a certain time (for example, 60 seconds but is not limited thereto), a signal is sent from the control device 7 to the fuel control valve 8. The output is completely closed, and the direct fire heating means 2 stops combustion. Thereby, while being able to prevent the excessive combustion of the to-be-heated absorption liquid 6 in the regenerator 1, it can prevent idling.

  In the present embodiment, the fuel supply control for the direct fire heating means 2 is performed by the fuel control valve 8. However, as shown in FIG. 1, a shutoff valve 10 is provided on the fuel supply pipe slightly upstream from the fuel control valve 8. The shutoff valve 10 is preferably connected to the control device 7 so that the shutoff valve 10 opens and closes the fuel supply pipe. Thereby, in the case of the said combustion stop, safety | security can be improved by closing the cutoff valve 10 rapidly.

  Furthermore, the state of the liquid level H after a certain period of time (for example, 60 seconds but not limited thereto) after the combustion stop is observed, and the liquid level H remains at a low level below the reference level L until the certain period of time elapses. In addition, when a low level is detected a plurality of times (for example, three times, but not limited thereto) continuously, a signal is output from the control device 7 to the driving device 11 when the predetermined time has elapsed, and is turned off. Thus, the absorption refrigerator is stopped abnormally. In this abnormal stop, in addition to the liquid level abnormality in the regenerator 1, there is a possibility that some troubles such as an absorption liquid pump in other places in the absorption refrigerator occur, so maintenance is necessary. It becomes.

  Conventionally, as shown by a broken line in FIG. 2, even if the liquid level H is lower than the reference level L at the point P, the fuel control valve 8 remains open and the low combustion state does not occur. Although it has recovered, the level of the liquid level is observed during a certain period of time (for example, 60 seconds but not limited thereto) after detecting that it has again become lower than the reference level L when the point R has elapsed. When H did not recover to the reference level L or higher, the abnormal stop was made when the predetermined time passed. For this reason, when a certain time has elapsed since the low level was detected, an abnormal stop was immediately made and the operation of the absorption refrigerator was stopped urgently. Thereby, the emergency stop of an absorption refrigerator may occur frequently, and the situation where the frequency | count of maintenance increases has been caused.

  On the other hand, in the present invention, when the low level is continuously detected a plurality of times as described above, the amount of fuel supplied to the direct fire heating means 2 is first gradually reduced to a low combustion state as a stage before the abnormal stop. If the liquid level H continues to be low after seeing the state for a certain period of time, the combustion is stopped only when the certain period of time has elapsed (not abnormal stop). In this case, by detecting the low level a plurality of times in succession to ensure the determination of the low level, it is possible to eliminate a combustion stop due to a temporary or intermittent liquid level drop. In addition, since the fuel supply amount starts to decrease at an early stage, the amount of combustion until the combustion is stopped is reduced, and the risk of emptying is reduced.

  In the present invention, when the state of the liquid level H continues to be low after a certain period of time has elapsed from the stop of the combustion, and the low level is detected a plurality of times continuously until the predetermined time elapses, the constant level is maintained. The abnormal stop was made only when the time had passed. As a result, the abnormal stop due to temporary or intermittent liquid level drop is eliminated, and the abnormal stop does not frequently occur as in the prior art, and the increase in the number of maintenance can be suppressed. Moreover, since the combustion is already stopped before the abnormal stop as described above, it is possible to prevent idling at an early stage.

  Further, in the present invention, when the liquid level H recovers to a high level of the reference level L or more during the low combustion state before the combustion stop, or during the state observation before the abnormal stop after the combustion stop. In the case where the liquid level H is restored to a high level that is equal to or higher than the reference level L, the possibility of returning to the normal operation on the way can be increased because all of the liquid levels H are restored to the normal operation. In addition, when returning to normal operation, the determination can be ensured by making the high level detection a plurality of times continuously, and the determination accuracy can be improved.

  The present invention can be applied as an air-blowing prevention control method for direct-fired absorption refrigerators, and is applicable not only to ordinary absorption refrigerators, but also to other, for example, double-effect or triple-effect absorption refrigerators, etc. It can be used widely.

It is a schematic sectional drawing which shows the principal part of the direct fire type absorption refrigerator to which this invention is applied. It is explanatory drawing which shows an example of embodiment of the air burning prevention control method of the direct-fired absorption refrigerator which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Regenerator 1a Combustion heating chamber 2 Direct fire heating means 3 Liquid level detection part 4 Liquid level detection means 5 Heated absorption liquid 6 Detected absorption liquid 7 Control apparatus 8 Fuel control valve 9 Temperature sensor 10 Shut-off valve 11 Drive apparatus

Claims (5)

  In an absorption refrigerator including a regenerator, a condenser, an evaporator, and an absorber, the regenerator includes a direct fire heating means, a liquid level detection unit communicating with the regenerator, and a liquid level provided in the liquid level detection unit Detecting means, and when the liquid level detecting means detects a liquid level lower than the reference level, the fuel control valve of the direct fire heating means is started to close, and the liquid level lower than the reference level is detected. When the liquid level higher than the reference level is not recovered by a certain time from the time, combustion of the direct fire heating means is stopped, and the liquid level higher than the reference level is reached by a certain time after the combustion is stopped. A control method for preventing air-blow in a direct-fired absorption refrigerator, characterized in that an abnormal stop is performed when the oil is not recovered.   The time when the liquid level detecting means detects a liquid level lower than the reference level is when the liquid level lower than the reference level is detected a plurality of times in succession. Control method for preventing air-blow in direct-fired absorption refrigerators.   The time when the reference level or higher is not recovered until a predetermined time elapses after the combustion is stopped is a time when a liquid level lower than the reference level is continuously detected a plurality of times. Control method for air-fired direct-fired absorption refrigerators.   2. The normal operation is resumed when a liquid level higher than the reference level is detected a plurality of times continuously after a certain time has elapsed from when the liquid level lower than the reference level is detected. The method for preventing air-blow of the direct-fired absorption refrigerator as described in 1.   2. The direct-fired absorption refrigerator according to claim 1, wherein when a liquid level equal to or higher than the reference level is detected a plurality of times continuously after a certain period of time has elapsed after the combustion is stopped, the direct-fired absorption refrigerator is returned to normal operation. Control method to prevent air blow.

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