JPS6311583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-exhaust heat recovery device for a direct-fired absorption refrigerator.

Figure 1 shows a conventional dual-effect absorption refrigerator.
1 is a low-temperature regenerator, 2 is a condenser, 3 is an evaporator, 4 is an absorber, 5 is a refrigerant such as water, 6 is a solution such as lithium bromide aqueous solution (LiBr), and 7 is a high-temperature regenerator heated by combustion gas. , 8 is a first heat exchanger, 9 is a second heat exchanger, 10 is a refrigerant spray pump, 11 is a solution spray pump, and 12 is a solution circulation pump. The solution from the circulation pump 12 is applied to the low temperature regenerator 1 through the heated side of the first heat exchanger 8 and to the high temperature regenerator 7 through the heated side of the second heat exchanger 9, and is heated in the high temperature regenerator 7. The generated refrigerant vapor is guided to a group of heating tubes in the low-temperature regenerator 1, heats the solution introduced into the low-temperature regenerator 1,
After the refrigerant contained in the solution is evaporated, it flows into the refrigerant reservoir of the condenser 2. The refrigerant vapor in this inflowing refrigerant and the refrigerant vapor generated in the low-temperature regenerator 1 are cooled and liquefied in the cooling water pipe group of the condenser 2, and then guided to the evaporator 3, where they are expanded under reduced pressure and vaporized.
The latent heat of vaporization during this vaporization is taken away from the cold water pipe group in the evaporator 3 to cool the water passing into the cold water pipe group.
On the other hand, the refrigerant vapor vaporized in the evaporator 3 flows into the absorber 4, where it is absorbed into a concentrated solution. Thereafter, the refrigeration cycle is performed by repeating the above actions. A group of hot water heating tubes 13 is provided inside the high-temperature regenerator 7, and heat is exchanged between the refrigerant vapor generated in the high-temperature regenerator 7 and the water flowing through the tube group 13 during winter, thereby heating the water. The water is then used as hot water for heating purposes.

In the above-mentioned direct-fired absorption refrigerator, about 85% of the heat of the combustion gas is transferred to the solution in the high-temperature regenerator 7 to generate refrigerant vapor, and the remaining about 15% of the heat becomes exhaust gas and is transferred to the chimney ( (not shown) is released into the atmosphere. In addition, the exhaust gas contains a large amount of water vapor generated by the combustion of hydrogen in the fuel, and the latent heat of condensation of this water vapor is approximately 10% of the total combustion calorific value of the fuel.
Equivalent to.

Therefore, it is conceivable that if the heat contained in these exhaust gases is recovered, the heat exchange coefficient of a direct-fired absorption refrigerator can be dramatically improved.

Conventionally, the following devices have been considered as heat recovery devices for these exhaust gases.

(1) Heat is exchanged between the exhaust gas and the air supplied for combustion, and the heat of the exhaust gas is recovered by heating the condensed air.

(2) A heat exchanger is installed in the exhaust gas passage, and water is passed through the tube group of the heat exchanger only during heating, and the water heated by absorbing the heat of the exhaust gas is transferred to the cold water tube group of the evaporator. The refrigerant in the evaporator is heated to evaporate and absorbed into the solution in the absorber 4, forming a solution circulation cycle similar to the refrigeration cycle described above, and water is passed through the tube group of the absorber 4 and condenser 2. and get hot water. The refrigerator works as a so-called heat pump to recover waste heat.

etc. are possible.

However, in method (1), the supply air temperature for combustion increases, which increases the combustion temperature and reduces NoX in the exhaust gas.
The number of components increases, which is not preferable. Although the method (2) has the advantage of recovering even the latent heat of condensation of the water vapor contained in the exhaust gas components during heating, it has a complicated configuration and the heat recovery of the exhaust gas becomes zero in the summer. Furthermore, in the summer, the exhaust gas is passed by bypassing the exhaust gas heat exchanger used in the winter, so the back pressure of the exhaust gas changes, and the combustion conditions change between winter and summer, so there are drawbacks such as the need for adjustment when switching between cooling and heating. have

The present invention was invented in view of the above, and an object of the present invention is to effectively utilize exhaust gas and improve the thermal efficiency of an absorption refrigerator.

The present invention was developed by focusing on the fact that the temperature of the solution supplied to the low-temperature regenerator during cooling is close to the hot water temperature during heating. The solution is preheated using exhaust gas, and during heating, the hot water for heating is directly preheated using exhaust gas, which improves thermal efficiency throughout the year.

An embodiment of the present invention will be described below based on FIG. In the figure, reference numeral 1 denotes a low-temperature regenerator, which is heated by a group of heating tubes to evaporate the refrigerant in the solution inside the regenerator. 2 is a condenser, and the refrigerant vapor is cooled and liquefied through a group of cooling water pipes. 3 is an evaporator which removes latent heat of vaporization when the refrigerant liquid is vaporized from the cold water pipe group to cool the water passing through the pipe group. 4 is an absorber, which absorbs frozen vapor into a concentrated solution and converts it into a dilute solution. 5 is a refrigerant, and water is mainly used.
6 is used as a solution, mainly a lithium bromide aqueous solution (LiBr). 7 is a combustion gas heating type high pressure regenerator heated by a group of heating tubes to be described later;
Evaporate the refrigerant in the solution inside the vessel. The refrigerant vapor obtained here is higher in temperature and pressure than the refrigerant vapor generated in the low-temperature regenerator 1. 8 is a first heat exchanger that exchanges heat between the low-temperature dilute solution supplied from the absorber 4 to the low-temperature regenerator 1 and the high-temperature concentrated solution returned from the low-temperature regenerator 1 to the absorber 4. Increase the temperature. 9 is a second heat exchanger that exchanges heat between the low-temperature dilute solution supplied from the absorber 4 to the high-temperature regenerator 7 and the high-temperature concentrated solution returned to the absorber 4 from the high-temperature regenerator 7; Increase the temperature of the solution. 10 is a refrigerant spray pump to help vaporize the refrigerant liquid. 11 is a solution spray pump to help the refrigerant vapor be absorbed into the solution. 12 is a solution circulation pump that sucks the dilute solution from the absorber 4 and supplies it to the low-temperature regenerator 1 and the high-temperature regenerator 7. Reference numeral 13 denotes a group of hot water heating tubes for heating provided inside the high-temperature regenerator 7, and heats water passing through the tube group by heat exchange with refrigerant vapor in the high-temperature regenerator 7. 14
15 is a shell housing a low-temperature regenerator 1, a condenser 3, an evaporator 3, and an absorber 4; 15 is a solution circulation pump 12;
A liquid supply pipe 16 that supplies the dilute solution discharged from the second heat exchanger 9 to the high-temperature regenerator 7 through the heated side of the second heat exchanger 9;
1 is a liquid supply pipe that supplies the dilute solution discharged from the solution circulation pump 12 to the low-temperature regenerator 1 through the heated side of the first heat exchanger 8, and 17 and 18 are furnace cylinders provided inside the high-temperature regenerator 7. The furnace tube 17 and the smoke tube 18 constitute a solution heating tube group. 19 is a return pipe for returning the concentrated solution from the high temperature regenerator 7 to the absorber 4 through the heating side of the second heat exchanger 9;
21 is a return pipe that returns the concentrated solution from the low-temperature regenerator 1 to the absorber 4 through the heating side of the first heat exchanger 8; An overflow pipe for returning the solution to the absorber 4, 22 a refrigerant reservoir, 23 a refrigerant spray pipe, 2
4 is a tube that guides the refrigerant liquid discharged from the refrigerant spray pump 10 to the refrigerant spray pipe 23; 25 is a solution spray tube; 26 is a tube that guides the solution discharged from the solution spray pump 11 to the solution spray tube 25;
7 is a refrigerant pipe that guides the refrigerant vapor generated in the high-temperature regenerator 7 to the heating tube group of the low-temperature regenerator 1, and 28 is a refrigerant pipe that guides the refrigerant (liquid and vapor) in the heating tube group of the low-temperature regenerator 1 to the condenser 2.
The refrigerant conduit leading to the reservoir is shown. Reference numeral 30 denotes an exhaust heat recovery device, in which an exhaust heat introduction pipe 31 connected to the smoke pipe 18 is connected to the bottom of the exhaust heat recovery device 30, and the inside of the recovery device 30 is partitioned into two chambers 33 and 34 by a partition wall 32. , opening/closing dampers 35 and 36 are provided at the bottom of both chambers, respectively.
A liquid supply preheating pipe 37 connected in parallel to the liquid supply chamber 15 is arranged in the first chamber 33, and a hot water preheating pipe 38 formed in a part of the inlet side piping of the hot water heating pipe 13 is arranged in the second chamber 34. are placed. 39 and 40 are the first
An intake damper is provided on the lower wall of the chamber and the second chamber, and reference numeral 41 indicates a drain pipe at the bottom of the exhaust heat recovery device 30.

The operation of the exhaust heat recovery device having the above structure will be explained. During cooling, the dual-effect absorption refrigerator is operated, the damper 35 is opened and the damper 36 is closed, and the exhaust gas from the smoke pipe 18 is transferred to the waste heat introduction pipe 3.
1 to the first chamber 33 of the exhaust heat recovery device 30,
The liquid supply preheating pipe 37 placed in the same room is heated to preheat the dilute solution sent to the high temperature regenerator 7, and the heat in the exhaust gas is recovered to the dilute solution, reducing the thermal efficiency during cooling (cooling). It can be improved by about 10%. In this case, the intake damper 39 in the first chamber is closed, and the intake damper 40 in the second chamber 34, which is not in use, is opened to suck in air for cooling, thereby preventing the hot water in the hot water preheating pipe 37 from being overheated. . Next, during heating, the dual-effect absorption refrigerator is operated, and the damper 36 is opened and the damper 35 is closed, opposite to when cooling (cooling), and the exhaust gas is introduced into the second chamber and into the hot water heating pipe 13. The inflowing hot water is preheated through the hot water preheating pipe 38, and the heat in the exhaust gas is recovered into the hot water, improving thermal efficiency during heating. In this case, the intake damper 40 of the second chamber is closed and the intake damper 39 of the first chamber is opened.

As explained above, according to the present invention, the exhaust heat of the heating heat source of the high-temperature regenerator is recovered, and during cooling, the dilute solution to be sent to the high-temperature regenerator is preheated, thereby increasing the thermal efficiency during cooling. Furthermore, during heating, hot water for heating can be preheated to improve thermal efficiency during heating.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional dual-effect absorption refrigerating machine, and FIG. 2 is a system diagram of a dual-effect absorption refrigerating machine with an exhaust heat recovery device, showing an embodiment of the present invention. 1... Low temperature regenerator, 2... Condenser, 3... Evaporator, 4... Absorber, 5... Refrigerant (water), 6... Solution (lithium bromide aqueous solution), 7... High temperature regenerator, 13...Hot water heating tube group, 15...Liquid supply pipe,
17...furnace tube, 18...smoke pipe, 27...refrigerant pipe,
30...Exhaust heat recovery device, 31...Exhaust heat introduction pipe, 32
...Partition wall, 33...First room, 34...Second room,
35, 36...damper, 37...liquid preheating pipe, 3
8...Hot water preheating pipe, 39,40...Intake damper,
41...Drain pipe.

Claims (1)

[Scope of Claims] 1. A hot water heating pipe for heating provided in a direct-fired regenerator that heats a condenser, an evaporator, an absorber, and a solution to generate refrigerant vapor, and the exhaust gas from the heat source for the regenerator is introduced. This waste heat recovery device is divided into two chambers, each with an exhaust gas introduction damper at the bottom, and one chamber has a liquid supply preheating pipe installed in parallel with the liquid supply pipe. , Hot water preheating pipes are installed in other rooms, and during cooling, exhaust heat is recovered via the supply liquid preheating pipe.
A direct-fired absorption refrigerator that is characterized by recovering exhaust heat through hot water preheating pipes during heating. 2. The direct-fired absorption refrigerator according to claim 1, wherein intake dampers are provided in both compartments of the exhaust heat recovery device, and the opening and closing of the exhaust heat introduction damper and the intake damper are reversely operated.