Deep water collection and heat collection process equipment

Abstract

The invention discloses deep water collection and heat collection process equipment which comprises a flue gas desulfurization tower, a flue gas water collection and heat collection tower, a condensation circulating water pump, a lithium bromide or lithium chloride absorption heat pump system, a slurry heat exchanger and a desulfurization slurry circulating pump, a buffer tank, a mass and heat transfer strengthening layer, a spraying layer and a demisting layer are further mounted in the flue gas water and heat collecting tower from bottom to top; the lithium bromide or lithium chloride absorption heat pump system is a conventional lithium bromide or lithium chloride absorption heat pump process system and comprises a condenser, a generator, an evaporator, an absorber, a corresponding pump and a corresponding pipeline system. According to the deep water collection and heat collection process equipment, the absorption heat pump system is coupled with the desulfurization tower and the flue gas water collection and heat collection tower, an external cold source is not needed, and heat recovery and recycling of water in flue gas can be achieved at the same time.

Description

Technical Field

[0001] This invention belongs to the field of flue gas heat energy utilization technology, specifically a deep water and heat recovery process and equipment. It is suitable for boiler systems employing wet flue gas desulfurization, particularly lignite-fired units, cogeneration boilers, biomass boilers, and other systems. It is also particularly suitable for boiler systems with heating functions, enabling deep recovery of water and heat from the flue gas, and secondary removal of pollutants such as sulfur dioxide. Background Technology

[0002] Currently, coal-fired power plant boilers or heating boilers burn large amounts of fossil fuels such as coal during operation. A significant amount of low-grade heat is discharged with the flue gas, which is not utilized. Due to problems such as acid dew point, corrosion, and scaling caused by SO2, SO3, H2O, and particulate matter in the flue gas, heat cannot be exchanged using conventional heat exchangers. To remove pollutants from the flue gas, wet desulfurization methods such as limestone-gypsum desulfurization are generally used, consuming a large amount of process water. The water evaporation during the flue gas cooling process is closely related to the flue gas volume and the inlet and outlet flue gas temperatures. Taking a 600MW unit as an example, its actual full-load water consumption of the limestone-gypsum wet desulfurization unit is 125t / h, with the water evaporation in the absorption tower accounting for the largest proportion and being the main water-consuming link of the desulfurization system, accounting for more than 90% of the total water consumption.

[0003] The wet flue gas desulfurization process results in a significant waste of water and energy. After wet desulfurization, the desulfurization slurry absorbs a large amount of heat, and the flue gas also contains a large amount of low-grade latent heat. By using an absorption heat pump system coupled with the desulfurization tower and the newly added flue gas water and heat recovery tower, the heat in the slurry and flue gas can be deeply recovered, and the water in the flue gas can also be recovered, achieving deep water and heat recovery. Summary of the Invention

[0004] The purpose of this invention is to provide a deep water and heat recovery process device to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a deep water and heat recovery process equipment, including a flue gas desulfurization tower, a flue gas water and heat recovery tower, a condensate circulating water pump, a lithium bromide or lithium chloride absorption heat pump system, a slurry heat exchanger, and a desulfurization slurry circulating pump. The flue gas water collection and heat collection tower is also equipped with a buffer tank, a mass and heat transfer enhancement layer, a spray layer and a demisting layer from bottom to top. The lithium bromide or lithium chloride absorption heat pump system is configured as a conventional lithium bromide or lithium chloride absorption heat pump process system, including a condenser, generator, evaporator, absorber, and corresponding pump and piping system. After receiving the raw flue gas, the flue gas desulfurization tower is sprayed and cooled by the desulfurization device until it is saturated. Part of the heat in the raw flue gas is released into the slurry, and part of the water in the slurry is vaporized into water vapor and released into the clean flue gas. The saturated flue gas is condensed and heated by the flue gas water collection and heat recovery tower to recover heat and cool and condense the water in the flue gas, thus realizing the recovery of heat and water. The absorption tower, flue gas water collection and heat recovery tower and heat utilization system are effectively integrated by the lithium bromide or lithium chloride absorption heat pump system. The generated cooling capacity is set to recover water in the flue gas. The heat recovered in the slurry and condensation tower is utilized by the heat utilization system. The cooling of the desulfurization slurry is achieved by the slurry heat exchanger to realize indirect heat exchange between the desulfurization slurry and the working fluid of the absorption heat pump. The relevant circulation system consists of the desulfurization slurry circulation pump, the flue gas desulfurization tower and the slurry heat exchanger and the corresponding valves and pipelines. Since the flue gas water collection and heat recovery tower has a secondary removal function for pollutants such as SO2, an alkaline solution pipeline is used to adjust the pH value of the circulating water in the flue gas water collection and heat recovery tower. The circulating water completes the cooling and condensation process of the flue gas in the flue gas water collection and heat recovery tower, realizing water recovery. The recovered water is discharged and reused by the external drainage pump.

[0006] As a preferred embodiment, the mass and heat transfer enhancement layer is configured as one or a combination of several of the following: a turbulent flow device, packing material, a porous sieve, and a porous gas distribution device.

[0007] As a preferred embodiment, the demisting layer is configured as one or a combination of a flat plate demister, a ridge demister, a cyclone demister, and a tube bundle dust collector.

[0008] Compared with the prior art, the technical effects and advantages of the present invention are as follows: This deep water and heat recovery process equipment adopts an absorption heat pump system coupled with a desulfurization tower and a flue gas water and heat recovery tower. It does not require an external cold source and can simultaneously realize heat recovery and water recovery and utilization in flue gas. This deep water and heat recovery process equipment uses a direct heat exchange tower for flue gas water and heat recovery. The equipment is simple and has high mass and heat transfer efficiency. The heat exchange between the desulfurization slurry and the heat pump working fluid adopts an indirect heat exchange, which reduces the scaling points in the system. Furthermore, the probability of scaling of the slurry in the equipment and system can be reduced by using the slurry to flow through the tube and increasing the flow rate. This enables the utilization of the thermal energy of the desulfurization slurry, which can be used for heating and other purposes. When used to heat air, it can also improve the efficiency of the boiler. This deep water and heat recovery process equipment improves SO2 absorption and flue gas desulfurization efficiency by lowering the temperature of the desulfurization slurry; the flue gas water and heat recovery tower can remove pollutants a second time, resulting in cleaner flue gas at the outlet. This advanced water and heat recovery process equipment produces high-quality water that can be directly used as makeup water for desulfurization systems, while also meeting the general process water requirements of other systems. Its low soluble salt content allows it to be further treated for more demanding applications such as boiler feedwater. Attached Figure Description

[0009] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the process of the present invention.

[0011] Explanation of reference numerals in the attached figures: In the picture: 1. Flue gas desulfurization tower; 2. Flue gas water collection and heat recovery tower; 3. Condensate circulating water pump; 4. Lithium bromide or lithium chloride absorption heat pump system; 5. Slurry heat exchanger; 6. Desulfurization slurry circulating pump; 7. Condenser 4-1; 8. Generator 4-2; 9. Evaporator 4-3; 10. Absorber 4-4; 11. Buffer tank 2a; 12. Mass and heat transfer enhancement layer 2b; 13. Spray layer 2c; 14. Demisting layer 2d. Raw flue gas (A), clean flue gas (B), alkaline solution (C), recovered water (D), heating medium (E), F. Detailed Implementation

[0012] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0013] Unless otherwise defined, the directions mentioned herein, such as up, down, left, right, front, back, inside, and outside, are based on the directions shown in the figures of this invention, and are explained here together.

[0014] The connection method can adopt existing methods such as bonding, welding, and bolting, depending on the actual needs. Techniques, methods and equipment known to those skilled in the art may not be discussed in detail. However, where appropriate, the techniques, methods and equipment should be regarded as part of the specification. The proportions of the components in the drawings are for reference only and can be adjusted to a certain extent according to the actual use.

[0015] Please see Figure 1 As shown, a deep water and heat recovery process equipment includes a flue gas desulfurization tower 1, a flue gas water and heat recovery tower 2, a condensate circulating water pump 3, a lithium bromide or lithium chloride absorption heat pump system 4, a slurry heat exchanger 5, and a desulfurization slurry circulating pump 6. The flue gas water collection and heat collection tower 2 is also equipped with a buffer tank 2a, a mass and heat transfer enhancement layer 2b, a spray layer 2c, and a demister layer 2d from bottom to top. The mass and heat transfer enhancement layer 2b is configured as one or a combination of turbulence generator, packing, porous sieve, and porous gas distribution device. The demister layer 2d is configured as one or a combination of flat plate demister, ridge demister, cyclone demister, and tube bundle dust collector. The lithium bromide or lithium chloride absorption heat pump system 4 is configured as a conventional lithium bromide or lithium chloride absorption heat pump process system, including condenser 4-1, generator 4-2, evaporator 4-3, absorber 4-4 and corresponding pump and piping system. After receiving the raw flue gas A, the flue gas A is sprayed and cooled by the desulfurization device and saturated. Part of the heat in the raw flue gas A is released into the slurry, and part of the water in the slurry is vaporized into water vapor and released into the clean flue gas. The saturated flue gas is condensed and heated by the flue gas water collection and heat recovery tower 2 to recover heat and cool and condense the water in the flue gas, thus realizing the recovery of heat and water. The absorption tower, flue gas water collection and heat recovery tower 2 and the heat use system are effectively integrated by the lithium bromide or lithium chloride absorption heat pump system 4. The cold energy prepared is set to recover the water in the flue gas. The heat recovered in the slurry and condensation tower is used by the heat use system. The desulfurization slurry is cooled and cooled by the slurry heat exchanger 5 to realize the indirect heat exchange between the desulfurization slurry and the working fluid of the absorption heat pump. The desulfurization slurry circulation pump 6, the flue gas desulfurization tower 1 and the slurry heat exchanger 5 and the corresponding valves and pipelines constitute the relevant circulation system. Since the flue gas water collection and heat recovery tower 2 has a secondary removal function for pollutants such as SO2, an alkaline solution pipeline is used to adjust the pH value of the circulating water in the flue gas water collection and heat recovery tower. The circulating water completes the cooling and condensation process of the flue gas in the flue gas water collection and heat recovery tower 2, realizing water recovery. The recovered water is discharged and reused by the external drainage pump.

[0016] After being desulfurized by flue gas desulfurization tower 1, the raw flue gas A enters flue gas water and heat recovery tower 2 through the top outlet. The flue gas and circulating cooling water undergo a strong gas-liquid mixing and mass and heat transfer process in the flue gas water and heat recovery tower 2, releasing water and heat from the flue gas. At the same time, some SO2, SO3 and particulate matter in the flue gas are collected, the pH value decreases, and the recovered water is discharged for reuse. The pH value can be adjusted by the alkaline solution pipeline system.

[0017] The cooling capacity in the flue gas heat recovery tower 2 comes from the absorption heat pump, while the heat is released to the lithium bromide or lithium chloride absorption heat pump system 4. The circulating water is powered by the condensate circulating water pump 3.

[0018] The desulfurization slurry from flue gas desulfurization tower 1 provides the heat source for a lithium bromide or lithium chloride absorption heat pump. A slurry heat exchanger 5 is used to exchange heat between the desulfurization slurry and the circulating working medium. The heat extracted from the slurry and the heat from the flue gas water recovery and heat recovery tower 2 are recycled by the heating medium.

[0019] A deep water and heat recovery process technology, equipment, and quantity: 1. Flue gas desulfurization tower; 2. Flue gas water collection and heat recovery tower; 3. One working and one standby condensate circulating water pump; 4. Lithium bromide or lithium chloride absorption heat pump system; 5. Slurry heat exchanger; 6. One working and one standby desulfurization slurry circulating pump. A deep water and heat recovery process technology equipment layout: The flue gas water collection and heat recovery tower is arranged near the location of flue gas desulfurization tower 1. If there is insufficient ground space, the flue gas water collection and heat recovery tower can be arranged above flue gas desulfurization tower 1 and connected by a gas lifting device. The heat pump system is optimized according to the layout of the flue gas desulfurization tower, flue gas water collection and heat recovery tower 2, and the heat-using area. The auxiliary heat exchangers, pumps, pipelines, etc. are optimized according to the towers and heat pumps.

[0020] A process flow for a deep water and heat recovery technology: The raw flue gas A is desulfurized in flue gas desulfurization tower 1. The desulfurization slurry is cooled by a lithium bromide absorption heat pump through a slurry heat exchanger. The cooled desulfurization slurry is returned to flue gas desulfurization tower 1. The clean flue gas after desulfurization enters flue gas water collection and heat recovery tower 1. The flue gas is vigorously mixed with the cooled circulating water in flue gas water collection and heat recovery tower 1, resulting in strong mass and heat transfer, which cools down the flue gas and recovers some of the water in the flue gas. At the same time, the heat in the flue gas is released into the circulating water, and the temperature rises. During the spray cooling process, pollutants in the flue gas are removed for the second time. The water recovered from the cooling process is discharged externally for use as makeup water for desulfurization or other process water.

[0021] The circulating water is powered by the condensate circulating water pump 3 and is first sent to the evaporator 4-3 in the heat pump system. The heat recovered from the flue gas is transferred to the lithium bromide circulating medium of the heat pump system and finally to the heat-using medium. The cooled circulating water is returned to the flue gas water collection and heat recovery tower 2.

[0022] The heat source of the absorption heat pump is the circulating desulfurization slurry, and the heat is recovered from the flue gas water collection and heat recovery tower 2. The heat is then used for heating or air heating and other purposes.

[0023] It should be noted that, in this document, relational terms such as "one" and "two" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A deep water and heat recovery process equipment, characterized in that, It includes a flue gas desulfurization tower (1), a flue gas water collection and heat collection tower (2), a condensate circulating water pump (3), a lithium bromide or lithium chloride absorption heat pump system (4), a slurry heat exchanger (5), and a desulfurization slurry circulating pump (6). The flue gas water collection and heat collection tower (2) is also equipped with a buffer tank (2a), a mass transfer and heat transfer enhancement layer (2b), a spray layer (2c), and a demisting layer (2d) from bottom to top. The lithium bromide or lithium chloride absorption heat pump system (4) is configured as a conventional lithium bromide or lithium chloride absorption heat pump process system, including a condenser (4-1), a generator (4-2), an evaporator (4-3), an absorber (4-4), and corresponding pumps and piping systems. After the flue gas desulfurization tower (1) receives the raw flue gas (A), the raw flue gas (A) is sprayed and cooled by the desulfurization device and saturated. Part of the heat in the raw flue gas (A) is released into the slurry, and part of the water in the slurry is vaporized into water vapor and released into the clean flue gas. The saturated flue gas is condensed and heated by the flue gas water collection and heat recovery tower (2), and the heat is recovered and the water in the flue gas is cooled and condensed, so as to realize the recovery of heat and water. The absorption tower, flue gas water collection and heat recovery tower (2) and heat use system are effectively integrated by the lithium bromide or lithium chloride absorption heat pump system (4). The prepared cold energy is set to recover the water in the flue gas. The heat recovered in the slurry and condensation tower is used by the heat use system. The desulfurization slurry is cooled and cooled by the slurry heat exchanger (5) to realize the indirect heat exchange between the desulfurization slurry and the working fluid of the absorption heat pump. The desulfurization slurry circulation pump (6), flue gas desulfurization tower (1) and slurry heat exchanger (5) and corresponding valves, pipelines, etc. form a related circulation system. Since the flue gas water collection and heat recovery tower (2) has a secondary removal function for pollutants such as SO2, an alkaline solution pipeline is used to adjust the pH value of the circulating water in the flue gas water collection and heat recovery tower. The circulating water completes the cooling and condensation process of the flue gas in the flue gas water collection and heat recovery tower (2), realizing water recovery. The recovered water is discharged by the external drainage pump for use.

2. The deep water and heat recovery process equipment according to claim 1, characterized in that, The mass and heat transfer enhancement layer (2b) is configured as one or a combination of several of the following: turbulence generator, packing, porous sieve, and porous gas distribution device.

3. The deep water and heat recovery process equipment according to claim 1, characterized in that, The demisting layer (2d) is configured as one or a combination of a flat plate demister, a ridge demister, a cyclone demister, and a tube bundle dust collector.

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