A steam pressure differential and hydrothermal combined recovery device

Abstract

This utility model relates to the field of energy-saving and environmental protection technology, specifically to a vapor pressure difference-based hydrothermal combined recovery device, aiming to solve the problems of latent heat of vaporization and water waste, as well as pollutant emissions in high-moisture flue gas. The device includes a primary heat exchanger, a booster fan, an absorption tower, and a desorber. Based on the principle of vapor pressure difference of the liquid absorbent, the flue gas, after pre-heating in the primary heat exchanger, is sent to the absorption tower by the booster fan, where it directly contacts the absorbent sprayed by the spray pipes to recover the latent heat of water vapor. The slurry that has absorbed water enters the desorber, undergoes heat exchange and desorption in a fourth-stage heat exchanger, and the water vapor is condensed into recovered water in a third-stage heat exchanger. A vacuum pump extracts the non-condensable gas. This device has high heat transfer efficiency, high volumetric efficiency, and uniform heat exchange. It can remove condensable particulate matter and is suitable for high-moisture flue gas from natural gas, biomass combustion, and wet desulfurization processes, with broad application prospects.

Description

Technical Field

[0001] This utility model relates to the field of energy conservation and environmental protection technology, and more specifically, to a vapor pressure differential hydrothermal combined recovery device. Background Technology

[0002] Coal accounts for over 70% of primary energy consumption, and its flue gas produces a large amount of pollutants, including sulfur dioxide, nitrogen oxides, and particulate matter. From a clean energy perspective, natural gas has become a major alternative to coal. In recent years, urban energy in my country has shifted from coal to natural gas, especially for winter heating in northern regions, where natural gas will gradually replace coal-fired boilers. With proper combustion control, particularly the use of low-NOx burners, natural gas does not produce pollutants similar to those generated by coal combustion.

[0003] Natural gas is primarily composed of methane, which, upon combustion, forms water and carbon dioxide. Unlike coal-fired flue gas, which has a low water content, natural gas combustion produces a large amount of water vapor. The release of this water vapor into the atmosphere may result in wasted latent heat of vaporization, water resources, and potential environmental problems related to condensable particulate matter. Therefore, to address these issues, this paper proposes a technical approach and compatible process equipment for recovering the latent heat of vaporization of water vapor from natural gas combustion flue gas and for replacing boiler feedwater with water recovery.

[0004] The main processes for recovering water vapor from flue gas can be categorized into two types based on heat exchange methods: direct contact and indirect heat exchange. Patent (Publication No. CN205402669U) proposes a heat pipe evaporator absorption heat pump flue gas waste heat recovery system that utilizes a heat pump to recover the latent heat of vaporization of water vapor in natural gas combustion flue gas. This device is an improved indirect contact heat exchange method, where the flue gas and working fluid do not come into contact. For small and medium-sized gas-fired boilers, installation space is limited, and the patent (Publication No. CN205402669U) heat pipe evaporator absorption heat pump flue gas waste heat recovery system is relatively large and unsuitable. Furthermore, the system is complex and costly. Direct contact heat exchange offers advantages such as high heat exchange efficiency, small equipment size, system simplicity, and lower investment. Therefore, this technology adopts a direct contact heat exchange method, using a solution absorbent to directly absorb water vapor from natural gas flue gas. A large amount of latent heat of vaporization is recovered during the conversion of gaseous water into liquid water. Patent (publication number CN102287957B) discloses an open absorption heat pump, proposing a heat pump for absorbing large amounts of low-pressure water vapor waste heat in industrial enterprises. This device has the following problems when used for waste heat recovery from gas flue gas: the working quality of the high-temperature heat source of the generator is too high, resulting in wasted useful work; the structure of the absorber, generator and condenser does not consider the process of mixing and separation during the direct contact between flue gas and working medium.

[0005] Therefore, in order to address the above-mentioned shortcomings, this patent addresses the issue of different process units and separation processes for multi-component gases such as CO2 / N2 / O2 / H2O in flue gas such as natural gas, which have different partial pressures in the working medium (lithium bromide, calcium chloride, lithium chloride, etc.), to achieve efficient heat exchange without affecting the heat exchange effect of the core equipment. Utility Model Content

[0006] To address the shortcomings of existing technologies, this invention aims to address the high water content flue gas formed after natural gas combustion. It establishes a direct adsorption heat exchange process using a liquid absorbent, based on the principle of vapor pressure difference formed by the liquid absorbent. This process involves the condensation of water vapor into water, the evaporation of water vapor into water vapor, and the secondary condensation of water vapor, thus constructing a vapor pressure difference hydrothermal combined recovery device.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A vapor pressure differential hydrothermal combined recovery device includes a primary heat exchanger, a booster fan, an absorption tower, spray pipes, a demister, a circulating pump A, a secondary heat exchanger, a level gauge A, a desorber, a tertiary heat exchanger, a level gauge B, a circulating pump B, a quaternary heat exchanger, and an extraction pump. The hot end outlet of the primary heat exchanger is connected to the inlet of the booster fan, and the outlet of the booster fan is connected to the inlet of the absorption tower. The spray pipes and the demister are both located inside the absorption tower. The inlet of the circulating pump A is connected to the bottom of the absorption tower, and the outlet is connected to the top of the absorption tower. A secondary heat exchanger is connected in series in the loop between the circulating pump A and the absorption tower. The level gauge A is connected to the bottom of the absorption tower. The bottom of the absorption tower is connected to the inlet of the desorber. The inlet of the circulating pump B is connected to the bottom of the desorber, and the outlet is connected to the top of the desorber. A quaternary heat exchanger is connected in series in the loop between the circulating pump B and the desorber. The tertiary heat exchanger is connected to the steam outlet of the desorber. The level gauge B is connected to the bottom of the desorber. The extraction pump is connected to the tail end of the desorber.

[0008] Furthermore, the primary heat exchanger is a shell-and-tube heat exchanger, and its internal baffles number no less than three stages.

[0009] Furthermore, the bottom of the absorption tower is square or circular, preferably circular.

[0010] Furthermore, the bottom of the absorption tower is provided with a gas distribution device, which is a multi-layer distribution plate or a swirl plate.

[0011] Furthermore, the spray pipe is a perforated spray pipe or a nozzle-type spray pipe, and the nozzle of the nozzle-type spray pipe is a rotating nozzle.

[0012] Furthermore, the demister has a ridge-type or swirl-plate type structure, preferably a swirl-plate type.

[0013] Furthermore, the secondary heat exchanger can be installed externally or internally, with internal installation being preferred.

[0014] Furthermore, the secondary heat exchanger is a serpentine heat exchange tube, and the porosity of the serpentine heat exchange tube arrangement is less than 30%.

[0015] Furthermore, the secondary heat exchanger is a plate heat exchanger, and the plate heat exchanger is made of polytetrafluoroethylene.

[0016] Furthermore, the bottom of the analyzer is a circulating slurry spraying section, and the top is a condensation section, with the two sections connected by a single-tube array.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This utility model has high heat and mass transfer efficiency. It adopts a liquid absorbent to directly contact the flue gas with the liquid, resulting in high heat exchange efficiency. The gas and liquid are in dispersed contact. The spray forms particles or droplets that come into intense contact with a large number of gas molecules. During the collision process, water vapor is captured to form liquid water molecules, and at the same time, the heat released is absorbed by the solution.

[0018] 2. This utility model has a high volume ratio. Due to the high heat and mass transfer efficiency and high gas-liquid reaction rate, the reactor volume is significantly reduced and the load per unit reactor is significantly increased.

[0019] 3. This utility model adopts a uniform spraying method. The key to gas-liquid contact lies in the uniformity of the circulating slurry spraying. The array-type, layered, multi-level partitioned arrangement method ensures that the liquid spraying speed, spraying angle, and liquid particle size are suitable for the gas-liquid reaction process.

[0020] 4. This utility model can remove multiple pollutants. During the cooling and dehydration and latent heat recovery process, the gas-liquid contact efficiency is high. During the process of liquid capturing water vapor molecules, it can also absorb potential pollutants in the flue gas, such as condensable particulate matter.

[0021] 5. This invention achieves high circulation ratio spraying. By setting a high circulation ratio in the unit reactor, it promotes contact between high-throughput liquid and flue gas, which can significantly reduce the reactor volume and increase heat exchange efficiency.

[0022] In summary, the vapor pressure difference hydrothermal combined recovery device of this utility model has advantages such as high heat transfer efficiency, high volumetric efficiency, uniform heat exchange, and the ability to remove pollutants. In addition to its application in the field of natural gas combustion flue gas, this technology can also be applied to other high-humidity and high-water-content flue gas, such as high-water-content biomass combustion flue gas and wet desulfurization flue gas. Therefore, compared with other traditional technologies, this utility model has obvious advantages, broad application prospects, and strong technical extension applicability.

[0023] Of course, any product implementing this utility model does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0026] Figure 2 This is a partial structural schematic diagram of the present invention.

[0027] Figure 3 This is a partial structural diagram of the present invention.

[0028] Figure 4 This is another partial structural schematic diagram of the present invention.

[0029] In the diagram: 1. Primary heat exchanger; 2. Booster fan; 3. Absorption tower; 4. Spray pipe; 5. Demister; 6. Circulating pump A; 7. Secondary heat exchanger; 8. Level gauge A; 9. Desorber; 10. Tertiary heat exchanger; 11. Level gauge B; 12. Circulating pump B; 13. Quaternary heat exchanger; 14. Air pump. Detailed Implementation

[0030] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0031] Example 1: As Figures 1 to 4 As shown, this embodiment provides a vapor pressure differential hydrothermal combined recovery device, including a primary heat exchanger 1, a booster fan 2, an absorption tower 3, a spray pipe 4, a demister 5, a circulating pump A6, a secondary heat exchanger 7, a level gauge A8, a desorber 9, a tertiary heat exchanger 10, a level gauge B11, a circulating pump B12, a quaternary heat exchanger 13, and a vacuum pump 14.

[0032] The high-moisture flue gas first enters the primary heat exchanger 1 for preheating, and its hot end outlet is connected to the inlet of the booster fan 2; the outlet of the booster fan 2 is connected to the inlet of the absorption tower 3, and the flue gas is discharged after fully contacting the liquid absorbent in the absorption tower 3.

[0033] Spray pipe 4 is used to spray liquid absorbent, and demister 5 is used to remove liquid droplets entrained in flue gas. Both are located inside absorption tower 3. The inlet of circulating pump A6 is connected to the bottom of absorption tower 3, and the outlet is connected to the top of absorption tower 3, forming a circulating slurry loop. The circulating slurry first enters the secondary heat exchanger 7 for heat exchange in the loop, and then returns to absorption tower 3. The level gauge A8 is connected to the bottom of absorption tower 3 to monitor the slurry level inside the tower.

[0034] After absorbing moisture, the slurry enters the desorber 9 from the bottom of the absorption tower 3 for desorption. The circulating slurry in the desorber 9 is transported to the fourth-stage heat exchanger 13 by the circulating pump B12 for heat exchange, and then returns to the desorber 9. The water vapor generated during desorption exchanges heat with the third-stage heat exchanger 10 and condenses to form liquid water - that is, the moisture is recovered. The level gauge B11 is installed at the bottom of the desorber 9 to monitor the slurry level in the desorber 9. The air pump 14 is located at the tail of the desorber 9 and is used to extract the non-condensable gas generated during the desorption process.

[0035] In this embodiment, the primary heat exchanger 1 is a shell-and-tube heat exchanger with a built-in three-stage baffle plate to improve pre-heat exchange efficiency.

[0036] In this embodiment, the bottom of the absorption tower 3 is circular; the bottom of the absorption tower 3 is provided with a gas distribution device, which is a swirl plate type, to achieve uniform gas distribution of flue gas.

[0037] In this embodiment, the spray pipe 4 is a nozzle-type spray pipe 4, and the nozzle of the nozzle-type spray pipe 4 is a rotating nozzle to ensure that the absorbent is sprayed evenly.

[0038] In this embodiment, the demister 5 has a swirl plate structure, which improves the droplet removal effect.

[0039] In this embodiment, the secondary heat exchanger 7 is installed in a built-in manner; the secondary heat exchanger 7 is a serpentine heat exchange tube, and the arrangement gap of the serpentine heat exchange tube is 25%.

[0040] In this embodiment, the secondary heat exchanger 7 is a plate heat exchanger, and the material of the plate heat exchanger is polytetrafluoroethylene.

[0041] In this embodiment, the bottom of the resolver 9 is a circulating slurry spraying section, and the top is a condensation section, and the two sections are connected by a single-tube array.

[0042] Example 2: Based on Example 1, this example integrates the secondary heat exchanger 7 and the quaternary heat exchanger 13 into the absorption tower 3 and the desorber 9, respectively, reducing external pipeline connections, further reducing the size of the device, and improving the system integration; the rest of the structure and working process are the same as in Example 1.

[0043] Example 3: Based on Example 1, this example removes the analyzer 9 and the associated circulating pump B12 and four-stage heat exchanger 13, and directly transports the water-absorbing circulating slurry to the membrane reactor for condensate recovery. It is suitable for scenarios where the water purity requirement is low and the system needs to be simplified; the rest of the structure and working process are the same as in Example 1.

[0044] Example 4: This example, based on Example 1, provides the working principle of a vapor pressure differential hydrothermal combined recovery device: High-moisture flue gas, such as natural gas combustion flue gas, is preheated by the first-stage heat exchanger 1 and then sent to the absorption tower 3 by the booster fan 2. The circulating pump A6 transports the absorbent slurry at the bottom of the absorption tower 3 to the second-stage heat exchanger 7 for heat exchange, and then sprays it evenly through the spray pipe 4, directly contacting the flue gas—water vapor condenses into liquid water and releases latent heat. The heat is carried away by the absorbent, and the flue gas is discharged after the liquid droplets are removed by the demister 5. The slurry that has absorbed moisture enters the desorber 9, and the circulating pump B12 transports it to the fourth-stage heat exchanger 13 for heat exchange and then returns it to the desorber 9 for spray desorption. The water vapor generated is condensed into recovered water by the third-stage heat exchanger 10, and the non-condensable gas is extracted by the extraction pump 14. The level gauges A8 and B11 monitor the slurry level in the absorption tower 3 and the desorber 9, respectively.

[0045] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. Any obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.

Claims

1. A vapor pressure differential hydrothermal combined recovery device, characterized in that, The system includes a primary heat exchanger (1), a booster fan (2), an absorption tower (3), a spray pipe (4), a demister (5), a circulating pump A (6), a secondary heat exchanger (7), a level gauge A (8), a desorber (9), a tertiary heat exchanger (10), a level gauge B (11), a circulating pump B (12), a quaternary heat exchanger (13), and a vacuum pump (14). The hot end outlet of the primary heat exchanger (1) is connected to the inlet of the booster fan (2), and the outlet of the booster fan (2) is connected to the inlet of the absorption tower (3). The spray pipe (4) and the demister (5) are both located inside the absorption tower (3). The inlet of the circulating pump A (6) is connected to the bottom of the absorption tower (3), and the outlet is connected to the absorption... A secondary heat exchanger (7) is connected in series in the loop between the top of the tower (3) and the circulation pump A (6) and the absorption tower (3); the level gauge A (8) is connected to the bottom of the absorption tower (3); the bottom of the absorption tower (3) is connected to the inlet of the analyzer (9); the inlet of the circulation pump B (12) is connected to the bottom of the analyzer (9), and the outlet is connected to the top of the analyzer (9), and a fourth-stage heat exchanger (13) is connected in series in the loop between the circulation pump B (12) and the analyzer (9); the third-stage heat exchanger (10) is connected to the steam outlet of the analyzer (9); the level gauge B (11) is connected to the bottom of the analyzer (9); and the vacuum pump (14) is connected to the tail of the analyzer (9).

2. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The primary heat exchanger (1) is a shell-and-tube heat exchanger, and its internal baffles number no less than three.

3. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The bottom of the absorption tower (3) is circular.

4. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The bottom of the absorption tower (3) is provided with a gas distribution device, which is a multi-layer distribution plate.

5. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The spray pipe (4) is a nozzle type spray pipe (4), and the nozzle of the nozzle type spray pipe (4) is a rotating nozzle.

6. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The demister (5) has a swirl plate structure.

7. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The secondary heat exchanger (7) is installed in a built-in manner.

8. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The secondary heat exchanger (7) is a serpentine heat exchange tube, and the porosity of the serpentine heat exchange tube arrangement is less than 30%.

9. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The secondary heat exchanger (7) is a plate heat exchanger, and the material of the plate heat exchanger is polytetrafluoroethylene.

10. The vapor pressure differential hydrothermal combined recovery device according to claim 1, characterized in that: The bottom of the analyzer (9) is a circulating slurry spraying part, and the top part is a condensation part, and the two parts are connected by a single tube array.

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