JP2008286441A - Absorption refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorption refrigerator capable of surely detecting local corrosion. <P>SOLUTION: In this absorption refrigerator comprising at least devices of a regenerator, a condenser, an evaporator, an absorber, a heat exchanger and a pump, using the water or dilute lithium bromide as a refrigerant, and using lithium bromide aqueous solution including an inhibitor composed of oxygen acid salt and alkaline metal hydroxide as an absorbing solution, the purpose can be achieved by disposing a corrosion detecting means 14 detecting corrosion of component materials of inner walls of the device. The corrosion detecting means 14 is disposed in a state of being dipped in the absorbing solution in one or more devices of at least the regenerator, the absorber and the heat exchanger, and composed of at least a pair of electrodes 15, 16 composed of metal same as the component material of the inner walls of the devices, a current measuring means 19 for measuring electric current flowing between the pair of electrodes 15, 16, and a warning means 20 providing warning when the electric current measured by the current measuring means 19 is over a specific value determined in advance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention mainly relates to an absorption refrigerator suitable for use in building air conditioning.

  In recent years, absorption refrigerators that use water as a refrigerant and an aqueous lithium bromide solution as an absorbent have been restricted from using chlorofluorocarbons that cause ozone layer destruction. It has become mainstream. And since the aqueous solution of lithium bromide used as an absorption liquid for absorption refrigerators has been highly corrosive, a corrosion inhibitor comprising an oxyacid salt and an alkali metal hydroxide called an inhibitor in the aqueous solution of lithium bromide. Corrosion of the carbon steel (steel member) by forming an oxide film on the surface (wall surface) of the carbon steel (steel member) constituting the inner wall of the absorption refrigerator As well as suppressing the generation of non-condensable gases such as hydrogen gas along with the corrosion of the carbon steel (steel member).

  By the way, the inhibitor acts as an oxidant and forms an oxide film on the surface (wall surface) of the carbon steel (steel member) constituting the inner wall of the absorption refrigerator. As a result, it is reduced and the oxidation action, that is, the ability to form an oxide film disappears. Therefore, when the soundness of the oxide film is not maintained in the absorbing liquid, the oxide film is locally destroyed, and corrosion starts.

  However, when the inhibitor is sufficiently mixed (added) in the lithium bromide aqueous solution, the broken oxide film is repaired, so that the carbon steel (steel) that forms the inner wall of the absorption refrigerator Corrosion of the component) is suppressed, but in the state where the amount of the inhibitor in the aqueous solution of lithium bromide is insufficient, the damaged oxide film is not sufficiently repaired, and the local corrosion proceeds. This leads to a dangerous state in which through holes are formed in the carbon steel (steel member) constituting the equipment inner wall of the refrigerator.

Therefore, by placing a chemically inert measuring electrode in the high-temperature regenerator, measuring the natural potential of this measuring electrode, and calculating the concentration of the inhibitor of the absorbing solution based on the value of this natural potential, An absorption refrigerator has been proposed in which the corrosion of carbon steel (steel member) constituting the inner wall of the absorption refrigerator is suppressed by controlling the concentration of the inhibitor (for example, patent document) 1).
JP-A-11-248301

  However, in the absorption refrigerator described in JP-A-11-248301, the carbon steel (steel member) constituting the inner wall of the absorption refrigerator is managed by controlling the concentration of the inhibitor in the absorption liquid. Even if the progress of the corrosion can be suppressed, there is a problem that it cannot be confirmed whether or not the degree of the corrosion is a local corrosion.

  The present invention has been made from the above-described prior art, and an object of the present invention is to provide an absorption refrigerator that can accurately detect local corrosion occurring on the inner wall of the absorption refrigerator.

  In order to achieve the above object, the present invention comprises at least a regenerator, a condenser, an evaporator, an absorber, a heat exchanger, and a pump, and water or a diluted lithium bromide aqueous solution as a refrigerant, and an oxygen acid In an absorption refrigerator using an aqueous solution of lithium bromide mixed with an inhibitor containing a salt and an alkali metal hydroxide as an absorbing solution, a corrosion detecting means is provided for detecting corrosion of the constituent material of the inner wall of the device, and this corrosion detection is provided. And at least a pair of electrodes made of the same metal as the constituent material of the inner wall of the device, wherein the means is immersed in an absorbing liquid in at least one of the regenerator, the absorber and the heat exchanger. Current measuring means for measuring the current flowing between the pair of electrodes, and an alarm is generated when the current measured by the current measuring means exceeds a predetermined value. It is characterized in that the alarm means is configured to be encompassed that.

  Furthermore, the present invention is characterized in that the current measuring means comprises at least a zero shunt ammeter that detects an absolute value of a current flowing between the pair of electrodes.

  Furthermore, the present invention is characterized in that the material of the pair of electrodes is any one of carbon steel, copper, cupronickel, stainless steel, and brazing material according to the constituent material of the inner wall of the device.

  According to the present invention, a pair of electrodes that are installed so as to be immersed in the absorbent in the device and are made of the same metal as the constituent material of the device inner wall, and a current measuring unit that measures a current flowing between the pair of electrodes, The corrosion detection means comprising at least an alarm means for issuing an alarm when the current measured by the current measurement means exceeds a preset predetermined value is generated on the inner wall of the absorption chiller device. It is possible to obtain an absorption refrigerator capable of accurately detecting local corrosion and preventing the occurrence of a dangerous state in which a through hole is formed in the inner wall of the device.

  Hereinafter, an embodiment of an absorption refrigerator according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an explanatory view of a main part configuration of an absorption refrigerator according to an embodiment of the present invention. FIG. 2 is a diagram showing experimental results regarding the corrosion current of the absorption refrigerator according to the embodiment of the present invention.

  A hermetic vacuum type absorption refrigerator 1 according to an embodiment of the present invention shown in FIG. 1 is a double-effect absorption refrigerator, and includes a regenerator 2 composed of a high temperature regenerator 2B and a low temperature regenerator 2A, a condensing unit. And at least a pump 7 including an evaporator 3, an evaporator 4, an absorber 5, a heat exchanger 6, and a first pump 7A and a second pump 7B.

  In the absorption refrigerator 1, a refrigerant X1 made of water and an absorption liquid Y1 made of a lithium bromide aqueous solution are enclosed. In the absorbent Y1 made of an aqueous lithium bromide solution, an inhibitor (a corrosion inhibitor) made of an oxyacid salt, an alkali metal hydroxide, or the like is mixed (added). The interior of the absorption chiller 1 is normally set to operate at atmospheric pressure or lower.

  As shown in FIG. 1, the evaporator 4 has a large number of evaporation pipes 8, and these evaporation pipes 8 are connected with a chilled water feed pipe 9 and a chilled water return pipe 9 </ b> A. By spraying the refrigerant X1 on the outer periphery of the tubular body 8 with the watering nozzle 10, it has a function of removing heat from the cold water W1 flowing in the evaporation tubular body 8 by heat of vaporization. The refrigerant X1 is sent to the watering nozzle 10 by the second pump 7B. The inside of the evaporator 4 is kept in a vacuum.

  The absorber 5 absorbs the vapor of the refrigerant X1 generated in the evaporator 4. At this time, the generated heat is cooled by the cooling water W <b> 2 flowing through the numerous absorption tubes 11 of the absorber 5. A cooling water feed pipe 12 and a cooling water return pipe 12 </ b> A are connected to the absorption pipe body 11.

  A part of the absorbing liquid (low-temperature dilute solution) Y1 having a reduced lithium bromide concentration by absorbing the vapor of the refrigerant X1 by the absorber 5 is sent to the high-temperature regenerator 2B by the first pump 7A, and the gas burner It is heated and concentrated by a heating source such as steam. The high-temperature refrigerant vapor X2 generated by heating is introduced into the heating pipe of the low-temperature regenerator 2A, and the absorption liquid Y1 with a low lithium bromide concentration is heated to heat the absorption liquid (high-temperature lithium bromide concentration). Concentrated solution) Y2. The absorbing liquid Y2 having a high lithium bromide concentration is returned to the evaporator 4 via the heat exchanger 6.

  When the refrigerant vapor X2 led into the heating pipe of the low-temperature regenerator 2B is led to the condenser 3, it is cooled by the cooling water W2 flowing through the cooling water pipe 13 of the condenser 3 to become the refrigerant X1, and the evaporator Return to 4.

  The first pump 7A serves as a driving source for circulating the absorbing liquid Y1 having a reduced lithium bromide concentration. The first pump 7 </ b> A has an inlet side connected to the bottom of the absorber 5 and an outlet side connected to a heat exchange pipe 6 </ b> A in the heat exchanger 6. The heat exchanger 6 is connected to the high temperature regenerator 2 </ b> B by the first pipe 21 and to the low temperature regenerator 2 </ b> A by the second pipe 22.

  The second pump 7B serves as a drive source for circulating the refrigerant X1 made of water. The second pump 7B is connected to the refrigerant return pipe 23 from the condenser 3 and the evaporator 4 on the inlet side, and to the sprinkling pipe 24 on the outlet side. The low temperature regenerator 2 </ b> A and the heat exchanger 6 are connected by a third pipe 25. The absorber 5 and the heat exchanger 6 are connected by a fourth pipe 26. The high temperature regenerator 2B is provided with a fifth pipe 27 that guides the high-temperature refrigerant vapor X2 generated in the high temperature regenerator 2B into the heating pipe of the low temperature regenerator 2A. The low temperature regenerator 2AB and the condenser 3 are provided with a sixth pipe 28 that guides the refrigerant vapor X2 introduced into the heating pipe of the low temperature regenerator 2A to the condenser 3.

  According to the absorption refrigeration machine 1 of the above embodiment, as shown in FIG. 1, the refrigerant X1 is converted into the sprinkling pipe 24 -the evaporator 4 -the refrigerant return pipe 23 -the second pump 7B by driving the second pump 7B. -It is designed to circulate through the watering pipe 24. Further, by driving the first pump 7A, a part of the absorbing liquid Y1 made of the lithium bromide aqueous solution is converted into a heat exchange pipe 6A-high temperature regenerator 2A-first pipe 21-heat exchanger 6-fourth pipe 26-. The absorber 5-the first pump 7A-the heat exchange pipe 6A circulates, and the remaining part of the absorbent Y1 made of the lithium bromide aqueous solution is the heat exchange pipe 6A-the third pipe 25-the low temperature regenerator 2B. The second pipe 22, the heat exchanger 6, the fourth pipe 26, the absorber 5, the first pump 7 </ b> A, and the heat exchange pipe 6 </ b> A are circulated. Further, the high-temperature refrigerant vapor X2 generated in the high-temperature regenerator 2B moves through the fifth pipe 27—the heating pipe of the low-temperature regenerator 2A—the sixth pipe 28 and reaches the condenser 3, where the refrigerant X1 The refrigerant X1 returns to the evaporator 4 via the refrigerant return pipe 23, the second pump 7B, and the watering pipe 24.

  Further, the absorption refrigerator 1 of the above embodiment is provided with corrosion detection means 14 for detecting corrosion of the constituent material of the equipment inner wall of the absorption refrigerator 1. As shown in FIG. 1, the corrosion detecting means 14 is installed so as to be immersed in the absorbing liquid Y1 in the high temperature regenerator 2B, and a pair of electrodes 15 made of the same metal as the constituent material of the inner wall of the high temperature regenerator 2B. 16, current measuring means 19 for measuring a current flowing between the pair of electrodes 15 and 16, and a current measured by the current measuring means 19 is a predetermined value (current calculated from an allowable value of corrosion rate). And a warning means 20 that issues a warning when the value or the inhibitor concentration allowable value) is exceeded. In the corrosion detection means 14 shown in FIG. 1, the pair of electrodes 15 and 16 are installed in the high temperature regenerator 2B where the temperature and concentration of the lithium bromide aqueous solution are the highest. You may make it install a pair of electrodes 15 and 16 in (low part) and each upper part.

  In the absorption refrigerator 1 of the above embodiment, the constituent material of the inner wall of the high-temperature regenerator 2B is carbon steel, and the pair of electrodes 15 and 16 are carbon steel electrodes. A current measuring means 19 for measuring a current flowing between the pair of electrodes 15 and 16 is connected to the pair of electrodes 15 and 16 of the corrosion detecting means 14 by lead wires 17 and 18. The current measuring means 19 is composed of a zero shunt ammeter so that the absolute value of the current flowing between the pair of electrodes 15 and 16 can be detected. The alarm means 20 includes a lamp, a buzzer, a patrol light, and the like.

  Furthermore, in the absorption refrigerator 1 of the above-described embodiment, a molybdenum / molybdenum oxide electrode (Mo / MoO 2) installed so as to be immersed in the absorbing liquid Y 1 in the absorber 5 and having a molybdenum oxide layer formed on the molybdenum surface. An oxide electrode composed of an electrode), and a so-called saturated calomel electrode (potassium chloride filled into a glass tube), which is placed so as to be opposed to the oxide electrode and immersed in the absorbing liquid Y1 in the absorber 5. Electrode), a reference electrode composed of a silver-silver chloride electrode, and a non-illustrated dissolved oxygen detecting means comprising a potential measuring device for measuring a potential difference generated between the oxide electrode and the reference electrode. Dissolved oxygen in the absorption liquid Y1 composed of an aqueous lithium solution (when the pressure in the absorption chiller is set to atmospheric pressure or lower, air enters the absorption liquid in the absorption chiller and enters the air. Since oxygen will blend into the absorption liquid, the dissolved but oxygen, that dissolved oxygen) it may be to detect.

  This dissolved oxygen detecting means measures a potential difference generated between the oxide electrode and the reference electrode due to a change in the natural potential of the oxide electrode with respect to the reference electrode in accordance with the dissolved oxygen concentration in the absorbing liquid Y1. When the measured potential difference exceeds a predetermined value (potential determined corresponding to the dissolved oxygen concentration), the alarm device is activated. When the dissolved oxygen concentration in the absorption liquid Y1 exceeds a predetermined value set in advance, an alarm is issued, so that the maintenance staff, manager or owner of the absorption refrigeration machine 1 can know without difficulty, and the absorption liquid Y1 Thus, various means for reducing the dissolved oxygen concentration can be smoothly applied to maintain the optimum corrosion suppression conditions in the absorption refrigerator 1. Therefore, the dissolved oxygen concentration in the absorbent Y1 in the absorber 5 is automatically monitored by the dissolved oxygen detecting means, so the dissolved oxygen concentration in the absorbent Y1 in the absorber 5 is set to a predetermined value. It is possible to prevent the progress of the corrosion of the carbon steel (steel member) constituting the absorption refrigerator 1 without being left for a long time in the state where it has been exceeded.

  According to the corrosion detection means 14 of the above embodiment, when both the pair of electrodes 15 and 16 are in the same state, no current (corrosion current) flows between the pair of electrodes 15 and 16, and the pair of electrodes 15. , 16, when corrosion occurs, a current (corrosion current) corresponding to the degree of progress of the corrosion flows between the pair of electrodes 15 and 16, so that the generation of the current (corrosion current) causes the absorption refrigerator 1 can be regarded as local corrosion occurring on the inner wall of the high-temperature regenerator 2 </ b> B that is the inner wall of the apparatus 1.

In the absorption refrigerator 1, an absorption liquid (hereinafter, this absorption liquid) is prepared by adding an inhibitor composed of Li ₂ MoO ₄ (lithium molybdenum tetraoxide) and LiNO ₃ (lithium nitric oxide) to an aqueous lithium bromide solution. As a test absorbing solution Z1), as shown in the range A of FIG. 2, while there is an inhibitor in the absorbing solution, a passive film is formed on the carbon steel, Corrosion current does not flow. In this state, when the inhibitor composed of Li ₂ MoO ₄ (lithium molybdenum tetroxide) and LiNO ₃ (lithium nitric oxide) is removed from the test absorbent Z1, the passive film is locally destroyed. Thus, as shown in the range B of FIG. 2, the corrosion current is generated and increases with time. Then, when a predetermined amount of an inhibitor composed of Li ₂ MoO ₄ (lithium molybdenum tetraoxide) and LiNO ₃ (lithium nitric oxide) is added to the test absorbent Z1, corrosion occurs as shown in the range C in FIG. It could be confirmed that the passive film was locally repaired and no current flowed.

Further, the absorption refrigeration machine of 30 tons to which the present invention is applied has a composition of 55 Wt% LiBr (lithium bromide), 0.17 Wt% LiOH (lithium hydroxide) and 0.03 Wt% LiNO ₃ (lithium nitric oxide). When the actual test operation of 10,000 hours operation at full load was performed with the absorption liquid formed in the above), the corrosion current was detected by the corrosion detection means 14 after 6700 hours, and the alarm exceeded the predetermined value after 8320 hours. It was confirmed that the means 20 was activated and an alarm was issued.

  According to the absorption refrigeration machine 1 of the above embodiment, when local corrosion occurs on the inner wall of the absorption refrigeration machine 1, the alarm means 20 automatically operates to indicate that the local corrosion has occurred, Since it can be notified to the manager or the owner, the countermeasure for preventing the local corrosion can be appropriately processed, and there is a danger that a through hole is formed in the inner wall of the absorption refrigerator 1. It is possible to prevent the state from being reached.

  In the above embodiment, the corrosion detection means 14 is installed only in the high temperature regenerator 2B. You may make it install so that 14 may be immersed. In the above embodiment, the refrigerant X1 is water, but a diluted lithium bromide aqueous solution may be the refrigerant X1. The material of the pair of electrodes 15 and 16 is not limited to carbon steel, and may be any of copper, cupronickel, stainless steel, and brazing material according to the constituent material of the inner wall of the absorption refrigerator 1. Good.

It is principal part structure explanatory drawing of the absorption refrigerator which concerns on one Embodiment of this invention. It is a figure which shows the experimental result regarding the corrosion current of the absorption refrigerator which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Absorption type refrigerator 2 Regenerator 2A Low temperature regenerator 2B High temperature regenerator 3 Condenser 4 Evaporator 5 Absorber 6 Heat exchanger 6A Heat exchange pipe 7 Pump 7A 1st pump 7B 2nd pump 8 Many evaporation pipes Body 9 Cold water feed pipe 9A Cold water return pipe 10 Sprinkling nozzle 11 Absorption pipe 12 Cooling water feed pipe 12A Cooling water return pipe 13 Cooling water pipe 14 Corrosion detection means 15, 16 Pair of electrodes 17, 18 Lead Line 19 Current measuring means 20 Alarm means 21 First pipe 22 Second pipe 23 Refrigerant return pipe 24 Sprinkling pipe 25 Third pipe 26 Fourth pipe 27 Fifth pipe 28 Sixth pipe X1 Refrigerant (water or dilute lithium bromide aqueous solution) )
X2 Refrigerant vapor Y1 Absorbing liquid with low lithium bromide concentration (low temperature dilute solution)
Y2 Absorption liquid with high lithium bromide concentration (high temperature concentrated solution)
W1 Cold water W2 Cooling water

Claims (3)

Equipped with at least regenerator, condenser, evaporator, absorber, heat exchanger and pump equipment, water or dilute lithium bromide aqueous solution as refrigerant, and mixed with inhibitors containing oxyacid salt and alkali metal hydroxide In an absorption refrigerator using an aqueous lithium bromide solution as an absorbent,
Corrosion detection means for detecting corrosion of the constituent material of the inner wall of the equipment is provided, and this corrosion detection means is immersed in an absorbing solution in at least one of the regenerator, absorber and heat exchanger. At least a pair of electrodes made of the same metal as the constituent material of the inner wall of the device, a current measuring means for measuring a current flowing between the pair of electrodes, and a current measured by the current measuring means is preset. An absorption refrigeration machine comprising a warning means for issuing a warning when a predetermined value is exceeded.   2. The absorption refrigerator according to claim 1, wherein the current measuring means comprises at least a zero shunt ammeter that detects an absolute value of a current flowing between the pair of electrodes.   The absorption refrigeration according to claim 1 or 2, wherein a material of the pair of electrodes is selected from the group consisting of carbon steel, copper, cupronickel, stainless steel, and brazing material according to the constituent material of the inner wall of the device. Machine.

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