JP2976037B2 - Direct fire high temperature regenerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-fired high-temperature regenerator (hereinafter, referred to as a high-temperature regenerator) used in an absorption refrigerator or an absorption heat pump.

[0002]

2. Description of the Related Art As a high-temperature regenerator used in an absorption refrigerator or absorption heat pump of lithium bromide-water system or the like, a technology of forming heat transfer fins on a heat transfer surface on a heated side (liquid contact side) is used. Have been proposed in JP-B-46-43069 and JP-B-53-26858.

However, in the high-temperature regenerator in which the heat transfer fins are formed on the liquid contact side, the heat transfer area is increased, but the shape is not such that boiling is promoted, so that the heat transfer coefficient on the liquid contact side does not increase. There was an inconvenience.

In order to solve the above-mentioned drawbacks of the prior art, a fine artificial cavity is formed on the heat transfer surface on the liquid contact side to improve the heat transfer coefficient on the liquid contact side, prevent the film from boiling, and remove the rare absorbing liquid. Japanese Patent Application No. Hei 3-10352 proposes a high-temperature regenerator that solves the decomposition due to overheating (generation of non-condensable gas) and the corrosion due to overheating of the heat transfer surface, and at the same time reduces the size of the apparatus by improving the heat transfer coefficient.
No. 8

However, in the high-temperature regenerator disclosed in Japanese Patent Application No. 3-103528, it has been found that the boiling promoting surface in which the fine cavities are formed deteriorates with time, and the heat transfer performance decreases. That is, during operation, the dilute absorbing liquid or foreign matter (such as rust) may enter the fine cavity on the boiling promoting surface, or the dilute absorbing liquid may enter the cavity when the apparatus is temporarily stopped, and may rarely be restarted. The heat transfer performance on the liquid contact side decreases as the operation time elapses, for example, because the absorbing liquid is not discharged from the cavity. In particular, there is a problem that the heat transfer performance is liable to be deteriorated in a device that frequently starts and stops repeatedly. If the device is operated with reduced heat transfer performance, the temperature of the heat transfer surface rises abnormally, premature corrosion occurs, and the generation of hydrogen increases due to the action with the iron plate, resulting in non-condensation The gas caused a decrease in capacity.

[0006]

Therefore, the development of a high-temperature regenerator capable of quickly recovering from the performance deterioration of the boiling promoting surface formed on the heat transfer surface on the liquid contact side has been strongly expected.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has a built-in furnace tube and a rare absorbing liquid between the furnace tube and the inner wall of the regenerator body. In the direct-fired high-temperature regenerator that separates refrigerant vapor from the rare absorbing liquid by heating the heat absorption side, the liquid-contacting heat transfer surface of the rear tube sheet of the furnace tube is formed as a porous heat transfer surface, A direct-fired high-temperature regenerator characterized in that a discharge port for a rare absorbing liquid or refrigerant is provided in the vicinity thereof, and a valve that is opened when discharging the rare absorbing liquid or refrigerant from the discharge port, A bubble detection unit that counts the number of bubbles that are heated and boiled by the liquid on the porous heat transfer surface, and a valve control unit that opens the valve when the count in the bubble detection unit decreases below a predetermined threshold value. A direct-fired high-temperature regenerator characterized by having That.

[0008]

The rare absorbing liquid sent from the absorber to the high-temperature regenerator and flowing near the porous heat transfer surface of the furnace tube has already been considerably concentrated by heating and is approaching the concentration of the intermediate liquid. When the rare absorbing liquid or the refrigerant is discharged and supplied here, the concentration of the absorbing liquid sharply drops in this portion, and the boiling point is lowered, so that intense boiling occurs. Therefore, when the heat transfer coefficient of the porous heat transfer surface is reduced due to dirt or the like, when the rare absorbing liquid or the refrigerant is discharged, the boiling which occurs vigorously removes the dirt etc. of the porous heat transfer surface, and the heat transfer performance is promptly improved. Will be recovered. The discharge of the rare absorbing liquid or the refrigerant is efficiently reactivated by observing the state of generation of bubbles by the bubble detection means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The high-temperature regenerator 1 shown in FIG. 1 has a built-in furnace tube 11, and an artificial porous heat transfer surface A having a fine cavity in the surface on the liquid contact side of a rear tube sheet 12 of the furnace tube 11. Is formed. Then, a boiling accelerator supply pipe 14 having a valve 13 has a discharge port directed toward the lower part of the porous heat transfer surface A so that the rare heat absorbing liquid or the refrigerant can be appropriately supplied to the porous heat transfer surface A. It is plumbed to open.

The porous heat transfer surface A is formed by spraying, for example, a nickel-chromium alloy having an average particle diameter of 35 μm on the surface of a base material of iron to an average thickness of 30 μm to form a cavity. Is approximately 5%.

Numeral 15 denotes a bubble detecting means (for example, a void sensor) which is attached near the upper portion of the porous heat transfer surface A as shown in FIG. The number can be counted. When the number of bubbles counted by the bubble detecting means 15 becomes smaller than a predetermined threshold value, the valve 13 is opened according to an instruction from the valve control device 16 and the boiling accelerator supply pipe 1 is opened.
4 can discharge a rare absorbing liquid or a refrigerant.
The observation of the boiling state by the bubble detecting means 15 may be performed at all times, or may be performed periodically (for example, every 100 hours). The bubble detecting means 15 can also be attached to the vicinity of the lower portion of the porous heat transfer surface A to observe the deterioration of the porous heat transfer surface A in more detail.

The high-temperature regenerator 1 according to the present invention has a smoke tube 17, a burner 18 and the like, similarly to the conventional high-temperature regenerator, and is connected to other equipment by piping, for example, as shown in FIG. Is done. Here, 3 is a low-temperature regenerator, 4 is a condenser, 5 is an evaporator, 6 is an absorber, 7 is a high-temperature heat exchanger, 8
Is a low-temperature heat exchanger, P1 is a diluent pump, and P2 is a refrigerant pump. In this case, the boiling accelerator supply pipe 14 dilutes the dilute absorbent from the absorber 6 to the high-temperature regenerator 1 by the diluent pump P1. It is formed so as to branch off from the middle of the liquid pipe 61.

On the porous heat transfer surface A, the dilute absorbing liquid contaminated by use for a long period of time enters the fine cavity, or when the operation of the apparatus is temporarily stopped, the dilute absorbing liquid enters the cavity, and the porous heat transfer surface A is restarted. At this time, since the rare absorbing liquid is not discharged from the cavity and the heat transfer performance decreases with the elapse of the operation time, the boiling of the rare absorbing liquid on the porous heat transfer surface A decreases and the refrigerant evaporates. The efficiency of separation and concentration decreases.

The deterioration of the porous heat transfer surface A can be detected by counting the number of generated air bubbles by the air bubble detecting means 15, so that when the number of air bubbles falls below a predetermined number, the valve control device is activated. The valve 13 is opened according to the instruction of 16 and the diluted absorbing liquid is discharged and supplied from the boiling accelerator supply pipe 14.

Normally, a furnace tube 1 having a porous heat transfer surface A formed thereon
The diluted absorption liquid near the rear tube sheet 12 is heated and concentrated from the time it is sent, and approaches the concentration of the intermediate liquid. Therefore, when a dilute absorbing solution having a low concentration is supplied to a place where the concentration is high, the concentration of the absorbing solution sharply decreases, and the boiling point drops so that boiling occurs violently. For this reason, even if the heat transfer coefficient is lowered due to dirt on the porous heat transfer surface A, the dilute absorbing solution is vigorously stirred, so that the liquid or the dirt that has entered the cavity of the porous heat transfer surface A is not removed. The heat transfer performance that has been expelled and lost is quickly restored. Further, the boiling performance in the initial stage of operation can be enhanced by the same method as described above.

Accordingly, in the high-temperature regenerator 1 of the present invention, when fuel such as gas is supplied from the burner 18 and burned, the rear tube sheet 12 of the furnace tube 11 ignited by the flame has a porous heat transfer surface A. Since the heat is always efficiently radiated to the rare absorbing solution via the circulating fluid, it does not become overheated. In addition, the heat of the combustion gas is efficiently radiated to the rare absorbing solution through the porous heat transfer surface A to the rare absorbing solution, and the temperature of the gas flowing into the smoke tube 17 is sufficiently low. The environment is also eased.
For this reason, the life of the device is greatly extended as compared with the conventional device.

In the high temperature regenerator 1 of the absorption refrigerator illustrated in FIG. 4, a boiling accelerator supply pipe 14 is provided to branch off from a discharge side of a refrigerant pump P2 of a refrigerant liquid pipe 51. Also in this case, the opening and closing of the valve 13 supplies the refrigerant to the bottom of the porous heat transfer surface A in accordance with the degree of deterioration of the porous heat transfer surface A observed by the bubble detecting means 15.

In the high-temperature regenerator 1 of the absorption refrigerator shown in FIG. 5, the bubble detecting means 15 of the high-temperature regenerator 1 shown in FIG. 4 is a CCD camera, and an image taken by the CCD camera is recorded in the VTR 19. At the same time, image processing is performed by the computer 20, and the generation state of bubbles is compared with the initial state (void rate, number of generated bubbles). For example, when the capacity is reduced to 85% from the initial boiling state, the computer 20 issues an instruction. The valve 13 is opened to discharge and supply the refrigerant from the boiling accelerator supply pipe 14.

In the method of observing the state of generation of bubbles by using a CCD camera, the flow of bubbles can be analyzed based on the flowchart illustrated in FIG.

The non-contact observation method using the CCD camera from the observation window is superior to a method in which a void sensor or the like is installed inside in that there is no vacuum holding or deterioration of the sensor.

Since the vapor of the refrigerant may be discharged from the boiling accelerator supply pipe 14, the boiling accelerator supply pipe 14 may be branched from the refrigerant vapor pipe 31 and attached.

The opening and closing of the valve 13 may be simply performed periodically by a timer. The timing of opening and closing is
If it is determined on the basis of an experiment performed at the time of designing the high-temperature regenerator 1, there is an advantage that the configuration is simplified and the apparatus is inexpensive.

[0023]

As described above, the high-temperature regenerator according to the present invention discharges and supplies a rare absorbing liquid or a refrigerant to a porous boiling promoting surface having an artificial boiling nucleus formed by metal spraying or the like. Intense boiling can occur near the porous heat transfer surface. Therefore, it is possible to easily recover the boiling heat transfer coefficient on the liquid contact side by removing dirt attached to the porous heat transfer surface. Therefore, the apparatus can always be operated with good heat transfer performance, so that the size of the apparatus can be reduced, and the surface temperature of a furnace tube, a smoke tube, and the like is reduced, so that corrosion of members is reduced. In addition, since there is no decrease in the circulation force due to forced convection, there is no stagnation portion of the diluted absorbing liquid, and the life of the device is greatly extended because local overheating is avoided. In particular, if the boiling state is monitored by the bubble detecting means and the number of generated bubbles is reduced to a predetermined number and a rare absorbing liquid or a refrigerant is supplied, the deteriorated porous heat transfer surface can be efficiently reactivated. Is possible and high thermal efficiency.

[Brief description of the drawings]

FIG. 1 is a partially cutaway explanatory view of one embodiment.

FIG. 2 is an explanatory diagram of a high-temperature regenerator having bubble detecting means.

FIG. 3 is an explanatory diagram of a high-temperature regenerator for discharging a rare absorbing liquid.

FIG. 4 is an explanatory diagram of a high-temperature regenerator that discharges a refrigerant liquid.

FIG. 5 is an explanatory diagram of a high-temperature regenerator in which a bubble detection unit is a CCD camera.

FIG. 6 is a flowchart when performing flow analysis of bubbles.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 high temperature regenerator 11 furnace tube 12 furnace tube rear tube sheet 13 valve 14 boiling promoter supply pipe 15 bubble detection means 16 valve control device 17 smoke tube 18 burner 19 VTR 20 computer 3 low temperature regenerator 4 condenser 5 evaporator 6 absorber 7 High-temperature heat exchanger 8 Low-temperature heat exchanger P1 Rare liquid pump P2 Refrigerant pump A Porous heat transfer surface

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F25B 33/00 F25B 15/00 303

Claims (2)

(57) [Claims] 1. A direct-fired high-temperature regenerator having a built-in furnace tube for heating a rare absorbing solution between the furnace tube and the inner wall of a regenerator body to separate refrigerant vapor from the rare absorbing solution. A direct-fired high-temperature regenerator characterized in that the heat transfer surface on the liquid contact side of the tube sheet is formed as a porous heat transfer surface, and a discharge port for a rare absorbing liquid or a refrigerant is provided near the porous heat transfer surface. . 2. A valve which is opened when the rare absorbing liquid or the refrigerant is discharged from the discharge port, and a bubble detecting means for counting the number of bubbles which are heated by the rare absorbing liquid on the porous heat transfer surface and boil. 2. A direct-fired high-temperature regenerator according to claim 1, further comprising a valve control device for opening said valve when the count in said bubble detecting means decreases below a predetermined threshold value.