Opening and closing integrated double-effect heat pump system for flue gas waste heat recovery

Abstract

According to the opening and closing integrated double-effect heat pump system for flue gas waste heat recovery, on one hand, the temperature of a solution entering an open type absorber is reduced through a closed type evaporation absorber, and heat supply network return water is provided for a heat user after sequentially passing through a water heat exchanger, an absorber A and a condenser C; on one hand, the heat in the heat pump system is fully absorbed, and meanwhile, the heat of the second solution is further absorbed through the water heat exchanger, so that the exhaust gas temperature can be obviously reduced, and the flue gas waste heat recovery efficiency is improved; and steam generated by heating and concentration is used as an external heat source of the regenerator G to perform regeneration and concentration on the second solution, so that double-effect utilization is realized, and the utilization efficiency of a high-temperature heat source is improved.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas waste heat recovery, and in particular to an integrated open and close double-effect heat pump system for flue gas waste heat recovery. Background Art

[0002] Boiler exhaust contains a large amount of heat. Recovering this heat can significantly improve the comprehensive utilization efficiency of energy. Open heat pump is an effective measure to achieve flue gas waste heat recovery (CN112378116A). However, the temperature of the solution circulation in the open heat pump is relatively high, resulting in low utilization efficiency of high-grade heat sources, high exhaust temperature, and low system energy efficiency.

[0003] The open heat pump utilizes the hygroscopicity of the solution to recover the sensible heat and latent heat in the flue gas. Since it does not have an evaporator in the traditional sense of a heat pump, when it is used for flue gas waste heat recovery, the temperature of the solution as a cold source is relatively high, resulting in a relatively high exhaust temperature and a low flue gas waste heat recovery efficiency.

[0004] In order to obtain a low-temperature cold source, there is an open-closed integrated heat pump device (CN112361650A), which divides the absorption process into two stages. The high-pressure stage is an open absorber, and the concentrated solution is in direct contact with the flue gas to recover the latent heat and sensible heat in the flue gas. The low-pressure stage is a closed absorber, and a low-temperature cold source can be produced by a low-pressure evaporator corresponding to the low-pressure absorber. This technical solution combines an open absorber and a closed absorber, but on the one hand, the circulating working fluid in the device is the same solution. The solution is in direct contact with the flue gas in the open absorber for heat and mass transfer, which will dissolve a large amount of impurities, causing solution contamination, and significantly affecting its absorption performance in the closed absorber. Secondly, the circulating solution will be entrained by the flue gas and cause losses, so a low-priced solution type is generally selected, and the hygroscopic performance is often relatively poor, which also limits the absorption pressure of the closed absorber and the temperature of the cold source. In addition, in this technical solution, the flue gas first exchanges heat with the low-temperature cold source produced by the evaporator, and then transfers heat and mass with the concentrated solution. Therefore, the exhaust temperature is limited by the temperature of the concentrated solution entering the open absorber and is still relatively high. In addition, the high-temperature heat source of this technical solution only concentrates the solution once in the generator, and the utilization efficiency of the high-grade driving heat source is low.

[0005] In summary, the existing technical solutions have low utilization efficiency of high-grade heat sources, and the flue gas waste heat recovery efficiency of the split absorber is low. Summary of the invention

[0006] The purpose of the present invention is to provide an integrated open and close double-effect heat pump system for flue gas waste heat recovery, so as to solve the problems of low utilization efficiency of high-grade heat sources, high exhaust temperature and low energy efficiency of recovering flue gas waste heat in the open type.

[0007] The present invention provides an integrated open and close double-effect heat pump system for flue gas waste heat recovery, comprising a generator, a first heat exchanger, a regeneration condenser, an evaporative absorber, a second heat exchanger, a water heat exchanger and an open absorber, wherein the regeneration condenser comprises a connected regenerator G and a condenser C, and the evaporative absorber comprises a connected evaporator E and an absorber A;

[0008] The first solution circulates between the generator, the first heat exchanger and the absorber A. The high-temperature concentrated solution flowing out of the generator exchanges heat with the dilute solution flowing out of the absorber A in the first heat exchanger. The concentrated solution cooled by heat exchange enters the absorber A and flows out after absorbing the refrigerant vapor. The dilute solution heated by heat exchange flows back to the generator.

[0009] The heat exchange pipeline inside the generator is connected to the high-temperature heat source. The steam generated during the heating and concentration process of the first solution enters the regenerator G as the heat source of the regenerator G. The steam condenses into water after releasing heat and enters the evaporator E to absorb heat and evaporate as refrigerant water. The generated low-pressure steam enters the absorber A, and the heat is absorbed by the first solution.

[0010] The second solution circulates among the regenerator G, the second heat exchanger, the water heat exchanger, the evaporator E and the open absorber. The dilute solution flowing out of the open absorber passes through the first heat exchange side of the second heat exchanger and then enters the regenerator G to be heated and concentrated. The concentrated solution passes through the second heat exchange side of the second heat exchanger and the first heat exchange side of the water heat exchanger in sequence, and exchanges heat with the dilute solution and the return water of the heat network respectively. After heat exchange and cooling, it enters the evaporator E, and after cooling in the evaporator E, it enters the open absorber;

[0011] The steam generated by the heating of the second solution in the regenerator G enters the condenser C and condenses. A first drainage pipeline is provided at the bottom of the condenser C, and the condensed water flows out of the condenser C through the first drainage pipeline;

[0012] The return water from the heating network passes through the water heat exchanger, the absorber A and the condenser C in sequence, and is provided to heat users after being heated.

[0013] Furthermore, the open absorber includes a first spray space and a second spray space separated from each other, the top of the second spray space is connected to the first spray space through a flue gas duct, and the second solution outlet end of the water heat exchanger is divided into two paths, one path is connected to the heat exchange tube of the evaporator E, and the other path is connected to the second spray space.

[0014] Furthermore, a rainproof cap is provided at the top of the flue gas duct.

[0015] Furthermore, the drainage pipeline at the bottom end of the condenser C is connected to the evaporator E.

[0016] Furthermore, a second drainage pipeline is provided at the bottom end of the evaporator E.

[0017] Furthermore, it also includes a condensate heat exchanger, and the steam condensate flowing out of the regenerator G enters the first heat exchange side of the condensate heat exchanger, exchanges heat with the hot network water for cooling, and then enters the evaporator E; the hot network return water is divided into two paths after heat exchange in the absorber A, one path enters the hot network water supply pipeline after passing through the condenser C, and the other path enters the hot network water supply pipeline after heat exchange and heating through the second heat exchange side of the condensate heat exchanger.

[0018] Furthermore, the circulation of the first solution is a closed cycle.

[0019] Furthermore, a heat exchange coil is provided inside the generator, and a heat source medium for heating the first solution circulates in the heat exchange coil.

[0020] Furthermore, the smoke duct is arranged at a central position of the top of the second spray space.

[0021] Furthermore, partitions are provided inside the regeneration condenser and the evaporative absorber, and channels for steam to pass through are provided at the tops of the partitions.

[0022] The beneficial effects of the technical solution are as follows: on the one hand, the system reduces the temperature of the solution entering the open absorber through a closed evaporative absorber, and provides heat to heat users after passing through a water heat exchanger, absorber A and condenser C in a heat network return water sequence. While fully absorbing the heat in the heat pump system, the water heat exchanger further absorbs the heat of the second solution, thereby significantly reducing the exhaust gas temperature and improving the flue gas waste heat recovery efficiency. On the other hand, the high-temperature heat source is used as an external heat source of the generator to heat and concentrate the first solution, and the steam generated by the heating and concentration is used as an external heat source of the regenerator G to regenerate and concentrate the second solution, thereby achieving double-effect utilization and improving the utilization efficiency of the high-temperature heat source. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a system structure diagram of Example 1 of the present invention.

[0025] Figure 2 This is a system structure diagram of Example 2 of the present invention.

[0026] Figure 3 This is a system structure diagram of Example 3 of the present invention.

[0027] Figure 4 This is a system structure diagram of Example 4 of the present invention.

[0028] Explanation of the reference numerals: 1 - generator, 2 - first heat exchanger, 3 - regeneration condenser, 4 - evaporative absorber, 5 - second heat exchanger, 6 - water heat exchanger, 7 - open absorber, 8 - second solution, 9 - first solution. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Example 1

[0033] like Figure 1As shown, the present invention includes a generator 1, a first heat exchanger 2, a regeneration condenser 3, an evaporative absorber 4, a second heat exchanger 5, a water heat exchanger 6 and an open absorber 7. The regeneration condenser 3 includes a regenerator G and a condenser C connected at the top, and the evaporative absorber 4 includes an evaporator E and an absorber A connected at the top. Partitions are provided inside the regeneration condenser 3 and the evaporative absorber 4, and channels for steam to pass through are provided at the tops of the partitions.

[0034] The first solution 9 circulates between the generator 1, the first heat exchanger 2 and the absorber A, which is a closed cycle. The high-temperature concentrated solution flowing out of the generator 1 is cooled by the first heat exchange side of the first heat exchanger 2, and then enters the absorber A to absorb the low-pressure steam generated in the evaporator E. After that, the dilute solution is heated by the second heat exchange side of the first heat exchanger 2 and returns to the generator 1 for spraying, completing the closed cycle of the first solution.

[0035] The second solution 8 circulates among the regeneration condenser 3, the second heat exchanger 5, the water heat exchanger 6, the evaporator E, and the open absorber 7. In the open absorber 7, the second solution 8 transfers heat and mass with the flue gas, and the dilute solution flowing out of the open absorber 7 is heated by the first heat exchange side of the second heat exchanger 5, enters the regenerator G, is heated and concentrated, flows out, enters the second heat exchange side of the second heat exchanger 5 to cool down, enters the water heat exchanger 6, exchanges heat with the return water of the heat network to cool down, and then enters the evaporator E, flows out after further cooling down, and returns to the open absorber 7, completing the circulation of the second solution.

[0036] The second solution 8 is heated and concentrated in the regenerator G, the generated steam enters the condenser C for condensation, and the condensed water flows out of the condenser C.

[0037] The high-temperature heat source enters the generator 1, heats and concentrates the first solution 9, and then flows out. The steam generated during the concentration of the first solution 9 enters the regenerator G, serving as the heat source of the regenerator G. The steam condenses after releasing heat and flows out of the regenerator G and enters the evaporator E, where it absorbs heat and evaporates as refrigerant water. The generated low-pressure steam enters the absorber A and is absorbed by the first solution 9.

[0038] The return water from the heating network passes through the water heat exchanger 6, absorber A and condenser C in sequence, and is provided to heat users as supply water after being heated.

[0039] In the above technical solution, the first solution and the second solution may be the same solution or different solutions.

[0040] On the one hand, the system reduces the temperature of the solution entering the open absorber 7 through the closed evaporative absorber 4, and provides the heat to the heat user after passing through the water heat exchanger 6, the absorber A and the condenser C in the order of setting the return water of the heat network. While fully absorbing the heat in the heat pump system, the heat of the second solution is further absorbed by the water heat exchanger, thereby significantly reducing the exhaust gas temperature and improving the flue gas waste heat recovery efficiency. On the other hand, the high-temperature heat source serves as the external heat source of the generator 1 to heat and concentrate the first solution 9, and the heated and concentrated steam serves as the external heat source of the regenerator G to regenerate and concentrate the second solution 8, realizing double-effect utilization and improving the utilization efficiency of the high-temperature heat source.

[0041] Example 2

[0042] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the open absorber includes a first spray space and a second spray space separated from each other, and the top of the second spray space is connected to the first spray space through a flue gas pipe, and the flue gas pipe is arranged at the center of the top of the second spray space. The solution flowing out of the water heat exchanger 6 is divided into two paths, one path directly enters the second spray space of the start absorber 7, and directly contacts the flue gas for heat and mass transfer, and the other path enters the evaporator E for cooling. After cooling, the solution flowing out enters the first spray space part of the open absorber 7, and directly contacts the flue gas for heat and mass transfer. The segmented design of the open absorber 7 is adapted to different solution temperatures, so that the flue gas can be cooled more effectively and the waste heat recovery effect can be improved.

[0043] Example 3

[0044] like Figure 3 As shown, the difference between this embodiment and embodiment 1 is that the condensed water flowing out of the condenser C also enters the evaporator E as refrigerant water, and a second drainage pipeline is provided at the bottom end of the evaporator E. Part of the refrigerant water in the evaporator E will flow out through the second drainage pipeline to achieve water balance of the entire system. In this solution, the drainage temperature of the system is lower, and thus the overall energy efficiency is higher.

[0045] Example 4

[0046] like Figure 4 As shown, the difference between this embodiment and embodiment 1 is that: a condensate heat exchanger 10 is added, and the steam condensate flowing out of the regenerator G enters the first heat exchange side of the condensate heat exchanger 10, exchanges heat with the hot network water and cools down before entering the evaporator E; the hot network return water then passes through the water heat exchanger 6 and the absorber A in sequence and is divided into two paths, one path enters the second heat exchange side of the condensate heat exchanger 10 to absorb heat and heat up, and the other path enters the condenser C to absorb heat and heat up, and the hot network water flowing out of the condensate heat exchanger 10 and the hot network water flowing out of the condenser C are reunited and provided to heat users as supply water.

[0047] This technical solution directly recovers the heat of the steam condensate flowing out of the regenerator G by setting up a condensate heat exchanger 10, which can avoid flash evaporation caused by this part of the steam condensate directly entering the evaporator E, and reduce the heat exchange area required for the evaporative absorber 4.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated open and close double-effect heat pump system for flue gas waste heat recovery, characterized in that: It includes a generator, a first heat exchanger, a regeneration condenser, an evaporative absorber, a second heat exchanger, a water heat exchanger and an open absorber, wherein the regeneration condenser includes a regenerator G and a condenser C connected, and the evaporative absorber includes an evaporator E and an absorber A connected; The first solution circulates between the generator, the first heat exchanger and the absorber A. The high-temperature concentrated solution flowing out of the generator exchanges heat with the dilute solution flowing out of the absorber A in the first heat exchanger. The concentrated solution cooled by heat exchange enters the absorber A and flows out after absorbing the refrigerant vapor. The dilute solution heated by heat exchange flows back to the generator. The heat exchange pipeline inside the generator is connected to the high-temperature heat source. The steam generated during the heating and concentration process of the first solution enters the regenerator G as the heat source of the regenerator G. The steam condenses into water after releasing heat and enters the evaporator E to absorb heat and evaporate as refrigerant water. The generated low-pressure steam enters the absorber A, and the heat is absorbed by the first solution. The second solution circulates among the regenerator G, the second heat exchanger, the water heat exchanger, the evaporator E and the open absorber. The dilute solution flowing out of the open absorber passes through the first heat exchange side of the second heat exchanger and then enters the regenerator G to be heated and concentrated. The concentrated solution passes through the second heat exchange side of the second heat exchanger and the first heat exchange side of the water heat exchanger in sequence, and exchanges heat with the dilute solution and the return water of the heat network respectively. After heat exchange and cooling, it enters the evaporator E, and after cooling in the evaporator E, it enters the open absorber; The steam generated by the heating of the second solution in the regenerator G enters the condenser C and condenses. A first drainage pipeline is provided at the bottom of the condenser C, and the condensed water flows out of the condenser C through the first drainage pipeline; The return water from the heating network passes through the water heat exchanger, the absorber A and the condenser C in sequence, and is provided to heat users after being heated.

2. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to claim 1 is characterized in that: The open absorber includes a first spray space and a second spray space separated from each other. The top of the second spray space is connected to the first spray space through a flue gas duct. The second solution outlet end of the water heat exchanger is divided into two paths, one of which is connected to the heat exchange tube of the evaporator E, and the other is connected to the second spray space.

3. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to claim 2 is characterized in that: A rainproof cap is provided on the top of the flue gas duct.

4. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to claim 1 is characterized in that: The drainage pipeline at the bottom end of the condenser C is connected to the evaporator E.

5. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to claim 4 is characterized in that: The bottom end of the evaporator E is provided with a second drainage pipeline.

6. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to claim 1 is characterized in that: It also includes a condensate heat exchanger. The steam condensate flowing out of the regenerator G enters the first heat exchange side of the condensate heat exchanger, exchanges heat with the hot network water for cooling, and then enters the evaporator E; the hot network return water is divided into two paths after heat exchange in the absorber A, one path enters the hot network water supply pipeline after passing through the condenser C, and the other path enters the hot network water supply pipeline after heat exchange and heating through the second heat exchange side of the condensate heat exchanger.

7. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to any one of claims 1 to 6, characterized in that: The circulation of the first solution is a closed cycle.

8. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to any one of claims 1 to 6, characterized in that: A heat exchange coil is provided inside the generator, and a heat source medium for heating the first solution circulates in the heat exchange coil.

9. The on-off integrated double-effect heat pump system for flue gas waste heat recovery according to any one of claims 1 to 6, characterized in that: The regeneration condenser and the evaporative absorber are both provided with passages for steam to pass through.

Images