JPS6148064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-lithium bromide absorption type water chiller/heater that is frequently used for air conditioning, etc., and in particular recovers heat from the exhaust gas of a boiler installed in a high-temperature regenerator to provide cooling,
The present invention relates to an absorption type water chiller/heater suitable for improving heat utilization efficiency in heating.

As shown in Figure 1, this type of conventional water cooler/hot water machine has the following features:
Evaporator 1, absorber 2, condenser 3, high temperature regenerator 4,
It consists of a low temperature regenerator 5, a low temperature heat exchanger 6, a high temperature heat exchanger 7, a circulation pump 8, a solution spray ejector pump 9, a refrigerant spray pump 10, and a boiler 11 that heats the high temperature regenerator 4.

When the cooling operation is started, the valve 14 is closed. A mixed solution of water and lithium bromide (hereinafter abbreviated as solution) in the high-temperature regenerator 4 is heated by the combustion gas of the boiler 11 to generate refrigerant vapor (water vapor). The generated refrigerant vapor is led to the low-temperature regenerator 5, heats the solution in the low-temperature regenerator 5, condenses and liquefies itself, and is supplied to the condenser 3 via the outlet header 16. The solution in the low temperature regenerator 5 is heated by the refrigerant vapor generated in the high temperature regenerator 4 to generate refrigerant vapor. The refrigerant vapor is led to the condenser 3, cooled by the cooling water 13 flowing in the heat transfer tube, condensed and liquefied, and then heated to the low temperature regenerator 5 and sent to the evaporator 1 together with the condensed and liquefied refrigerant through the valve 25. Supplied. The liquid refrigerant supplied to the evaporator 1 is sprayed onto the heat exchanger tube group by the refrigerant spray pump 10, and the cold water 1 flowing inside the heat exchanger tubes is
The cold water 12 is cooled by exchanging heat with the cold water 12 to evaporate and vaporize, and the latent heat of evaporation at that time is taken away from the cold water 12, thereby providing a refrigeration effect. Refrigerant vapor evaporated in the evaporator 1 is guided to the absorber 2. On the other hand, the high temperature regenerator 4 generates refrigerant vapor and concentrates the solution (hereinafter referred to as
After passing through a high temperature heat exchanger 7 and a low temperature heat exchanger 6, respectively, the concentrated solution (referred to as a concentrated solution) and the concentrated solution in the low temperature regenerator 5 are sucked into a solution ejector spray pump 9 driven by a high pressure solution of a circulation pump 8. It is pressurized and spread over the heat transfer tube group of the absorber 2, cooled by the cooling water 13 flowing inside the heat transfer tubes, and is diluted by absorbing the refrigerant vapor evaporated in the evaporator 1 to become a dilute solution. . The dilute solution in the absorber 2 is circulated through the circulation pump 8.
The water is sucked and pressurized, preheated by a low temperature heat exchanger 6, and supplied to a low temperature regenerator 5, and a portion is preheated by a high temperature heat exchanger and supplied to a high temperature regenerator 4, respectively. The cooling cycle was configured as explained above.

Next, heating operation will be explained. During heating, it is common to indirectly heat the hot water 13 flowing through the absorber 2 and condenser 3 with refrigerant vapor generated from a solution heated by a boiler 11 disposed in the high-temperature regenerator 4. For example, open valve 14 and open valve 2.
When closing 0, 21, 22, 23, 24, 25,
The refrigerant vapor generated in the high temperature regenerator 4 is transferred to the low temperature regenerator 5.
The solution inside is heated, and it condenses and liquefies itself and returns to valve 1.
4 and returns to the high temperature regenerator 4. The refrigerant vapor generated by being heated by the refrigerant vapor of the high-temperature regenerator 4 in the low-temperature regenerator 5 is converted into hot water 1 flowing through the heat transfer tube of the condenser 3.
3 is heated, it condenses and liquefies itself, and is returned to the low-temperature regenerator 5 via a bypass channel (not shown, closed during cooling). The heating cycle was configured as described above.

In the above-mentioned direct-heating double-effect absorption type water chiller/heater, the solution in the high temperature regenerator 4 is approximately 140 to 170°C.
The combustion exhaust gas discharged from the boiler 11 was dumped into the atmosphere at a high temperature of 140 to 170°C or higher, and was not utilized in any way, resulting in insufficient efficiency.

An object of the present invention is to provide a heat exchanger in the flue gas flow path of the boiler 11 provided in the high-temperature regenerator 4 and recover heat to the low-temperature regenerator 5 using the high-temperature liquid refrigerant of the low-temperature regenerator 5. In addition to improving the heat utilization efficiency of air conditioning and heating, we aim to eliminate the problems caused by the heat exchanger arrangement, such as retention of surfactant, refrigerant vapor leakage to the condenser, and heat loss due to high temperature of refrigerant liquid effluent from the condenser. An object of the present invention is to provide an absorption type water chiller/heater that is capable of preventing an increase in water.

A heat exchanger is disposed in the flue gas flow path of the boiler 11 provided in the high-temperature regenerator 4 to supply part or all of the condensed liquid refrigerant of the low-temperature regenerator 5, and the generated refrigerant vapor is transferred to the low-temperature regenerator 5. In addition to being used for heating, the surplus liquid refrigerant is supplied to the condenser 3 during cooling and to the high-temperature regenerator 4 during heating to (i) maintain an appropriate level of liquid refrigerant in the heat exchanger;
The outflow amount of the liquid refrigerant accompanying the refrigerant vapor is reduced so that the liquid refrigerant does not inhibit the concentration of the solution in the high temperature regenerator 4 during cooling.

(ii) To prevent the refrigerant in the heat exchanger from becoming a solution (causing an increase in the boiling point) due to a small amount of solution contained in the liquid refrigerant flowing into the heat exchanger remaining without evaporating, supplying liquid refrigerant in an amount greater than the amount of evaporation. This was prevented by draining the refrigerant again as a liquid refrigerant.

(iii) In the same way as in (ii), the refrigerant in the heat exchanger becomes a surfactant due to a small amount of surfactant (for example, n-octyl alcohol) contained in the liquid refrigerant flowing into the heat exchanger remaining without evaporating. This was prevented.

It is characterized by Furthermore, when the heat exchanger and the condenser 3 are connected as described above, the refrigerant vapor generated in the heat exchanger flows into the condenser 3 together with the liquid refrigerant, resulting in heat loss (refrigerant vapor is mixed with the liquid refrigerant). It was found that the enthalpy was larger by about 500 kcal/Kg compared to the case of , and the heat loss was also larger. Therefore, in order to prevent refrigerant vapor from flowing out, a control valve (for example, a float valve) that opens and closes depending on the refrigerant liquid level in the heat exchanger is disposed in the refrigerant conduit connecting the heat exchanger and the condenser 3. shall be. Furthermore, the liquid refrigerant in the heat exchanger is transferred to a duct connecting the heat exchanger and the heating section of the low-temperature regenerator 5 and a heating pipe 5 of the low-temperature regenerator 5.
It was found that the temperature was higher than the temperature of the liquid refrigerant supplied to the heat exchanger by the flow pressure loss of a. If the liquid refrigerant in the heat exchanger is supplied as it is to the condenser 3, heat loss will be large. Therefore, absorber 2
Embodiments of the present invention will be described below with reference to the drawings. do. In FIGS. 2 to 6, the same or equivalent parts are given the same reference numerals as those shown in FIG. 1, and their explanation will be omitted. Figures 2 and 3
In the figure, 30 is a heat exchanger disposed in the exhaust path 37 of the combustion exhaust gas G generated by the boiler 11.
The heat exchanger 30 includes a lower header 31, an upper header 32 that also serves as a gas separator, and headers 31, 32.
It consists of a large number of heat transfer tubes connected to the heat transfer tubes and a large number of fins installed in the heat transfer tubes. Lower header 31 and liquid refrigerant outlet header 1 of low temperature regenerator 5
6 are connected by a refrigerant liquid conduit 33. The upper header 32 is connected at its lower part to the gas phase portion of the high temperature regenerator 4 via a valve 34, and is also connected to the condenser 3 via a liquid refrigerant conduit 35 via a partition plate 38. Further, a steam pipe 17 connecting the inlet steam header 18 of the high temperature regenerator 4 and the low temperature regenerator 5 is connected to the top of the upper header 32 by a steam duct 36.

Next, the operation and effects of this embodiment having the above-described configuration will be explained.

During cooling operation, the gate valve 34 is set to a closed state, and the gate valves 38, 21, 22, 23, 24, and 25 are set to an open state. The liquid refrigerant condensed and liquefied in the heating pipe 5a of the low-temperature regenerator 5 is introduced into the heat exchanger 30 via the outlet header 16 and the conduit 33, where it exchanges heat with the combustion exhaust gas of the boiler 11 and becomes a refrigerant at 86°C to 96°C. Generates steam. This refrigerant vapor is transferred to an eliminator (not shown).
The refrigerant vapor generated in the high-temperature regenerator 4 is guided through the inlet header 18 of the low-temperature regenerator 5 to the heating tube 5a, where it is condensed and liquefied, and the latent heat is radiated at that time. As a result, the solution in the low temperature regenerator 5 is heated to generate refrigerant vapor and concentrate the solution. The liquefied refrigerant passes through the outlet header 16 and the conduit 33 again to the heat exchanger 30.
will be introduced in The liquid refrigerant in the heat exchanger 30 is discharged to the condenser 3 via the conduit 35 and the gate valve 38 in an amount equal to the amount of refrigerant vapor generated in the high temperature regenerator 4 .
Therefore, it was possible to prevent the heat exchanger 30 from overflowing with liquid refrigerant and the liquid refrigerant flowing into the high-temperature regenerator 4 via the steam duct 36 and the steam pipe 17, thereby inhibiting the solution concentration action. The refrigerant vapor generated in the high-temperature regenerator 4 contains the vapor of a surfactant (for example, n-octyl alcohol) that has the effect of promoting heat transfer in the absorber 2 and fine solution mist. The surfactant is generally a higher alcohol type having a higher boiling point than the refrigerant (water). In the heat exchanger 30, refrigerant vapor is generated at a lower temperature than in the high-temperature regenerator 4, so the surfactant remains;
It is discharged together with the liquid refrigerant into the condenser 3 via a conduit 35. Therefore, the concentration of the surfactant and the concentration of the solution in the heat exchanger 30 are extremely low, and these impurities hardly cause an increase in the boiling point. Therefore, while the pressure level of the heat exchanger 30 is almost the same as that of the high-temperature regenerator 4, the temperature level of the heated medium is 60 to 70 degrees Celsius lower, allowing sufficient heat exchange with the exhaust gas of the boiler 11. temperature level. As described above, the heat of the exhaust gas from the boiler 11 is recovered into the solution of the low-temperature regenerator 5 and used for concentrating the solution and generating refrigerant, thus contributing to an increase in the refrigerating capacity of the absorption type water chiller/heater.

Usually, the solution temperatures in the low temperature regenerator 5 and high temperature regenerator 4 are 80 to 90°C and 130 to 160°C, respectively.
The exhaust gas temperature of the boiler 11 is approximately 200°C. The boiling point of the refrigerant in the heat exchanger 30 is 86 to 96°C, which is higher than the solution temperature in the low temperature regenerator 5.
It is easy to make the exhaust gas temperature level after heat exchange about 100℃. From now on, approximately boiler 1
Approximately 5% of the heat input of 1 can be recovered, and as a result, the refrigerating capacity can be increased by 70 to 80% of the recovered heat. In other words, the coefficient of performance based on heat input is approximately 4%.
It is possible to improve energy efficiency and achieve the effect of saving energy.

During heating operation, the gate valve 34 is set to an open state, and the gate valves 38, 21, 22, 23, 24, and 25 are set to a closed state. The liquid refrigerant condensed and liquefied in the heating pipe 5a of the low-temperature regenerator 5 is introduced into the heat exchanger 30 via the outlet header 16 and the conduit 33, where it exchanges heat with the combustion exhaust gas of the boiler 11 to generate refrigerant vapor. Further, the remaining liquid refrigerant is passed through the valve 34 to the high temperature regenerator 4.
is returned to the gas phase. This refrigerant vapor is led to the steam duct 36 and steam pipe 17 through an eliminator (not shown), and is led to the heating pipe 5a through the inlet header 18 of the low temperature regenerator together with the refrigerant vapor generated in the high temperature regenerator 4, where it is condensed. The solution in the low temperature regenerator 5 is heated by the radiation of latent heat during liquefaction, and refrigerant vapor is generated. The refrigerant vapor generated in the low-temperature regenerator 5 is guided to the condenser 3, heats the hot water 13 flowing in the heat transfer tube, condenses and liquefies it, and is returned to the low-temperature regenerator 5 again. As described above, the heat of the exhaust gas from the boiler 11 is recovered into hot water.

The effect of heat recovery is different from that during cooling, and the effect is based on the entire amount of heat recovered, resulting in approximately 5% energy savings.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment and the embodiments described above are such that the outlet water chamber 16 of the low-temperature regenerator 5 and the heat exchanger 30 are connected via a gate valve 39, and the heat exchanger 3
0 and the steam pipe 17 via the gate valve 40, and the refrigerant flow path system of the conventional cycle, that is, the system that connects the condenser 3 and the outlet water chamber 16 via the gate valve 20. The difference is that the system connecting the gas phase part of the high temperature regenerator 4 and the outlet water chamber 16 remains. As described above, by closing the gate valves 40, 39, and 34, it becomes easy to disconnect the exhaust heat recovery heat exchanger 30 from the main cycle of the water cooler/heater. Therefore, there is an advantage that the heat recovery heat exchanger 30 can be easily installed in an existing water cooler/heater. In addition, non-condensable gas is
Since the water remains in the outlet water chamber 16, a bleed pipe 45 is provided.

Next, the operation will be explained. Gate valve 2 during cooling
0, 21, 22, 23, 24, 25, 38, 3
9 and 40 are set in the open state, and the gate valves 14 and 34 are set in the closed state. The condensed refrigerant of the low-temperature regenerator 5 is supplied from the outlet water chamber 16, and a portion passes through the gate valve 20 to the condenser 3.
The remainder is supplied to the heat exchanger 30 via the gate valve 39. The refrigerant vapor generated in the heat exchanger 30 is transferred to the gate valve 40, duct 36, steam pipe 17, and inlet water chamber 18.
The solution is then supplied to the low-temperature regenerator 5 together with the refrigerant vapor generated in the high-temperature regenerator 4 to heat the solution. Also,
The remaining liquid refrigerant is sent to the condenser 3 via the gate valve 38 and the conduit 35. Note that even if the liquid refrigerant outlet of the conduit 35 is attached to the lower header 31, the refrigerant liquid level of the heat exchanger 30 is maintained at an appropriately balanced position. A properly balanced position is a point where the pressure drop between the liquid head of the heat exchanger 30 and the duct 36, the steam pipe 17, and the heat transfer tube 5a is balanced with the liquid head of the refrigerant liquid conduit 33 and its flow pressure drop taken into account.

During heating, the gate valves 20, 21, 22, 23,
24, 25, 38 in the closed state, the gate valves 14, 3
4, 39, and 40 are set in the open state. A portion of the liquid refrigerant in the outlet water chamber 16 returns to the high temperature regenerator 4 via the gate valve 14. The remaining liquid refrigerant is transferred to the conduit 33 and the gate valve 3.
9 is introduced into the transthermal exchanger 30, where it exchanges heat with the exhaust gas of the boiler 11 to generate refrigerant vapor. The generated refrigerant vapor passes through the duct 36, the gate valve 40, the steam pipe 17, and the inlet duct 18, and then reaches the high temperature regenerator 4.
The solution is supplied to the low-temperature regenerator 5 together with the refrigerant vapor generated in the low-temperature regenerator 5, and the solution in the low-temperature regenerator 5 is heated. Also,
The remaining liquid refrigerant is returned to the high temperature regenerator 4 via the gate valve 34. As described above, the heat of the exhaust gas from the boiler 11 is recovered into the solution in the low temperature regenerator 5.

The effects are as described above.

However, a portion (about 1%) of the refrigerant vapor generated in the heat exchanger 30 is transferred to the condenser 3 via the conduit 35.
is discharged. The following methods can be used to prevent heat loss caused by this. This invention will be explained below using FIG. 5.

A float chamber 42 is connected to the heat exchanger 30 via a weir 43, and a conduit 35 is connected via a float valve 41.
It is connected to the condenser 3 via a gate valve 38. The float valve 41 is closed when the refrigerant liquid level in the float chamber 42 decreases, and refrigerant vapor is not discharged into the conduit 35, so there is no heat loss due to vapor outflow, and the effect of heat recovery can be further enhanced. Furthermore, while the liquid level in the heat exchanger 30 is undulating due to boiling of the refrigerant, the float chamber 42 is filled with the liquid refrigerant that overflows the weir 43, causing the float valve 41 to vibrate abnormally. float valve 41
This is advantageous in terms of durability.

By the way, as mentioned above, the temperature level of the liquid refrigerant in the heat exchanger 30 is about 2 to 3 degrees Celsius compared to the liquid refrigerant in the outlet water chamber 16 of the low-temperature regenerator 5 due to the pressure drop in the flow path and the refrigerant head. expensive. Therefore, the enthalpy of the liquid refrigerant supplied to the condenser 3 is large, and thermal efficiency cannot be sufficiently improved by heat recovery. Therefore, the 6th
The structure shown in the figure was used to further improve thermal efficiency.

In FIG. 6, the difference from the embodiment shown in FIG. A heat exchanger 44 is provided to exchange heat with the solution. The action of the heat exchanger 44 is to recover the sensible heat of the high temperature liquid refrigerant discharged from the heat exchanger 30 into a solution, thereby reducing the thermal energy wasted from the condenser 3 to the cooling water 13. ,
This improves heat utilization efficiency during cooling operation.

Note that even if refrigerant vapor is mixed into the liquid refrigerant discharged from the heat exchanger 30 to the conduit 35, heat can be recovered to the solution.

As explained above, in the first invention, a heat exchanger is disposed in the combustion gas exhaust path of the boiler to supply a high temperature liquid refrigerant to the low temperature regenerator, so that the solution in the low temperature regenerator is heated to a high temperature. It is configured to recover heat based on the principle of siphon (heat is transferred by boiling and condensing the refrigerant), and the excess liquid refrigerant is returned to the condenser during cooling and to the high-temperature regenerator during heating. (1) Since the liquid refrigerant in the heat exchanger does not become a solution or a surfactant, the boiling point of the refrigerant does not increase;
The heat recovery temperature can be maintained almost constant.

(2) Heat can be recovered into the cycle during cooling and heating, so
The heat exchanger has a high usage efficiency, and the energy saving effect per invested capital is large.

Further, by using the second invention in combination, (3) during cooling, it is possible to prevent the refrigerant vapor generated in the heat exchanger 30 from blowing through to the condenser, so that the heat utilization efficiency is improved accordingly.

Furthermore, by using the third invention in combination, (4) during cooling, the sensible heat of the high temperature liquid refrigerant heated by the heat exchanger 30 is recovered into a solution and then sent to the condenser. , the heat utilization efficiency is improved by the sensible heat of the liquid refrigerant.

There is an effect.

It is also conceivable to exchange heat between the liquid refrigerant introduced from the liquid refrigerant outlet header 16 of the low-temperature regenerator 5 to the heat exchanger 30 and the liquid refrigerant discharged from the heat exchanger 30 to the condenser 3. This is the outlet water chamber 16
This is because the temperature of the liquid refrigerant introduced into the heat exchanger 30 from the heat exchanger 30 is lower than that of the liquid refrigerant discharged from the heat exchanger 30 to the condenser 3. Therefore, there is an effect of being able to reduce the reduction in efficiency due to refrigerant vapor being discharged to the condenser 3.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional absorption type water chiller/heater, Figure 2
The figure is a block diagram of one embodiment of the present invention, FIG. 3 is a partial detailed explanatory diagram of FIG. 2, and FIGS. 4, 5, and 6 are block diagrams of other embodiments of the present invention. 1... Evaporator, 5... Absorber, 3... Condenser,
4...High temperature regenerator, 5...Low temperature regenerator, 30...
Heat exchanger, 42...Float box, 41...
Float valve, 44... Heat exchanger for refrigerant sensible heat recovery,
45...Air bleed piping.

Claims (1)

[Claims] 1. A high-temperature regenerator with a boiler, a low-temperature regenerator with a heater, a condenser, an absorber, an evaporator, a high-temperature heat exchanger, a low-temperature heat exchanger, and a pump, all of which are operable. In the absorption type water chiller/heater that was contacted,
A heat exchanger is provided in the exhaust path of the combustion gas after leaving the high temperature regenerator, and a refrigerant liquid conduit is provided to connect the inlet side of the heat exchanger and the outlet side of the heating tube of the low temperature regenerator. It has a steam duct that connects the outlet side of the exchanger and the inlet side of the heating pipe of the low-temperature regenerator, a liquid refrigerant conduit that connects the heat exchanger and the condenser, and a liquid refrigerant conduit that connects the heat exchanger and the high-temperature regenerator. It is characterized by having a valve that selectively supplies the liquid refrigerant of the heat exchanger to the condenser through the liquid refrigerant conduit during cooling operation and to the high temperature regenerator through the conduit during heating operation. Absorption type water chiller/heater. 2. The absorber according to claim 1, wherein the liquid refrigerant conduit connecting the heat exchanger and the condenser has a control valve that opens and closes depending on the liquid refrigerant level in the heat exchanger. Type cold/hot water machine. 3. A heat exchanger for exchanging heat between the liquid refrigerant supplied from the heat exchanger to the condenser and the solution supplied from the absorber to the low-temperature regenerator or the high-temperature regenerator. The absorption type water chiller/heater according to item 1 or 2.