A flue gas cooling system and a sulfuric acid production device comprising the same

Abstract

The utility model relates to a kind of flue gas cooling system and the sulphuric acid production device comprising the flue gas cooling system, belong to flue gas cooling technical field, the flue gas cooling system of the utility model includes quench tower, quench tower circulating pump and heat exchanger assembly;Quench tower is filler tower, and heat exchanger assembly includes heat exchanger and the circulating cooling assembly connected with heat exchanger;The import of quench tower circulating pump is connected with cooling liquid outlet, and the outlet of quench tower circulating pump is communicated to the cooling liquid inlet of quench tower by heat exchanger;The utility model sulphuric acid production device introduces flue gas cooling system to reduce the temperature of sulfur dioxide flue gas, to reduce the water amount of sulfur dioxide flue gas into dry circulating acid, not only can ensure dry acid and absorption acid acid concentration, avoid or reduce the equipment corrosion caused by dry circulating acid and absorption circulating acid acid concentration lower, while the moisture into dry acid reduces, can substantially increase dilute acid amount, can produce more dilution heat, effectively improve the heat production in sulphuric acid production process.

Description

Technical Field

[0001] This utility model belongs to the field of flue gas cooling technology, specifically, it relates to a flue gas cooling system. Background Technology

[0002] 98% sulfuric acid (industrially abbreviated as 98 acid) has better stability compared to other concentrations of sulfuric acid, making it the main type of industrial sulfuric acid product. There are two main production processes for 98 acid: one is from smelting flue gas, and the other is from sulfur. Regardless of the method, the sulfur dioxide flue gas must first be dried in a drying tower to remove moisture, then heated in a heat exchanger. Under the catalytic action of a vanadium catalyst, the sulfur dioxide is oxidized to sulfur trioxide, which is then absorbed by sulfuric acid to produce 98 acid. The production process of 98 acid generates a large amount of heat. To achieve heat recovery, 98 acid production plants are usually equipped with heat recovery devices. Increasing the amount of heat generated during sulfuric acid production or improving the low-temperature heat recovery rate can effectively improve the economic efficiency of sulfuric acid production.

[0003] In the sulfuric acid production process, drying acid is needed to dry sulfur dioxide flue gas, while concentrated sulfuric acid is needed to absorb sulfur trioxide. The concentration of the drying acid decreases after absorbing moisture from the sulfur dioxide flue gas, while the concentration of the absorption acid in the absorption tower increases after absorbing sulfur trioxide. To maintain the concentration balance between the drying acid and the absorption acid, the drying acid and the absorption acid are connected in series in the production unit. At the same time, in order to maintain the concentration of the absorption acid, diluent acid needs to be added. The diluent acid is generated by adding water to the sulfuric acid. The sulfuric acid dilution process generates a large amount of heat of dilution, which is one of the main heat sources for low-temperature heat energy recovery.

[0004] Inside the drying tower, the process of absorbing moisture from sulfur dioxide flue gas with drying acid reduces the concentration of the drying acid. This reduction in concentration causes severe corrosion to the drying tower. If corrosion holes appear in the drying tower body, sulfur dioxide flue gas will overflow, posing a significant safety hazard. Summary of the Invention

[0005] In response to the problems raised in the background art, the first objective of this utility model is to provide a flue gas cooling system that can effectively reduce the temperature of flue gas. The second objective of this utility model is to provide a sulfuric acid production apparatus that includes the above-mentioned flue gas cooling system. The sulfuric acid production apparatus can effectively reduce the temperature of sulfur dioxide flue gas in the sulfuric acid production apparatus, thereby reducing the amount of water carried into the drying tower by the sulfur dioxide flue gas. This not only maintains the acid concentration of the dried acid and completely eliminates the risk of equipment corrosion, but also increases the amount of diluent used, thereby generating more dilution heat and effectively improving the low-temperature heat in the sulfuric acid production process.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution: The flue gas cooling system includes a quench tower, a quench tower circulating pump, and a heat exchanger assembly. The quench tower is a packed tower with a flue gas inlet and a coolant outlet at the bottom, a coolant inlet at the top, and a cooled flue gas outlet at the top. The heat exchanger assembly includes a heat exchanger and a circulating cooling component connected to the heat exchanger. The inlet of the quench tower circulating pump is connected to the coolant outlet, and the outlet of the quench tower circulating pump is connected to the coolant inlet of the quench tower via the heat exchanger.

[0007] Preferably, the circulating cooling component includes a refrigeration unit, a chilled water storage tank, and a chilled water circulating pump; the inlet of the chilled water circulating pump is connected to the chilled water storage tank via a pipe, and the outlet is connected to the refrigeration unit via a pipe; the chilled water inlet of the heat exchanger is connected to the refrigeration unit, and the chilled water outlet of the heat exchanger is connected to the chilled water storage tank.

[0008] Preferably, the refrigeration unit is equipped with a circulating water inlet pipe and a circulating water outlet pipe.

[0009] Preferably, the heat exchanger is a plate heat exchanger.

[0010] The sulfuric acid production unit includes the flue gas cooling system described above; the flue gas outlet of the sulfur dioxide gas cooling tower of the sulfuric acid production unit is connected to the flue gas inlet of the quench tower via a pipeline, and the cooling flue gas outlet of the quench tower is connected to the sulfur dioxide drying tower via a pipeline.

[0011] Preferably, the circulating water of the sulfuric acid production unit is connected to the refrigeration unit through a pipeline. The refrigeration unit is equipped with a circulating water return outlet pipe, which is connected to the circulating water cooling system of the sulfuric acid production unit.

[0012] The beneficial effects of this utility model are: The flue gas cooling system of this invention can effectively reduce the temperature in flue gas.

[0013] This utility model includes a sulfuric acid production device with a flue gas cooling system, which can effectively reduce the temperature of sulfur dioxide flue gas in sulfuric acid production, thereby reducing the water content in the sulfur dioxide flue gas. This not only maintains dry acid concentration and completely eliminates the risk of equipment corrosion, but also increases the amount of diluent added to balance the acid concentration, generating more dilution heat and effectively improving the low-temperature heat in the sulfuric acid production process.

[0014] This invention can be used not only for cooling sulfur dioxide flue gas in the sulfuric acid production process, but also for cooling flue gas in other devices. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the flue gas cooling system of this utility model; In the diagram, 1-quench tower, 2-quench tower circulation pump, 3-flue gas inlet, 4-coolant outlet, 5-coolant inlet, 6-heat exchanger, 7-refrigeration unit, 8-chilled water circulation pump, 9-chilled water storage tank, 10-cooling flue gas outlet. Detailed Implementation

[0016] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, so as to facilitate the understanding of those skilled in the art.

[0017] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "equipped with" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. Example 1

[0018] like Figure 1 As shown, the flue gas cooling system includes a quench tower 1, a quench tower circulation pump 2, and a heat exchanger assembly. The quench tower 1 is a packed tower with a flue gas inlet 3 and a coolant outlet 4 at the bottom, a coolant inlet 5 at the top, and a cooled flue gas outlet 10 at the top. The heat exchanger assembly includes a heat exchanger 6 and a circulating cooling component connected to the heat exchanger. The inlet of the quench tower circulation pump 2 is connected to the coolant outlet 4, and the outlet of the quench tower circulation pump 2 is connected to the coolant inlet 5 of the quench tower 1 via the heat exchanger 6. High-temperature flue gas enters the quench tower 1 through the flue gas inlet 3 and comes into countercurrent contact with the coolant supplied by the quench tower circulation pump 2 inside the quench tower 1. After the flue gas temperature is reduced, it is discharged from the cooled flue gas outlet 10. The coolant carries away the heat of the high-temperature flue gas, and under the heat exchange effect of the heat exchanger assembly, the temperature is maintained at a low level.

[0019] The circulating cooling component is any component capable of exchanging heat with the coolant in the heat exchanger 6 to remove heat from the coolant and maintain its temperature. Optionally, the circulating cooling component includes a chiller unit 7, a chilled water storage tank 9, and a chilled water circulation pump 8. The inlet of the chilled water circulation pump 8 is connected to the chilled water storage tank 9 via a pipe, and the outlet is connected to the chiller unit 7 via a pipe. The chilled water inlet of the heat exchanger 6 is connected to the chiller unit 7, and the chilled water outlet of the heat exchanger 6 is connected to the chilled water storage tank 9. The chiller unit 7 provides chilled water to the heat exchanger 6 to remove heat from the coolant. After heat exchange, the chilled water returns to the chilled water storage tank 9 and is then pumped back into the chiller unit 7 by the chilled water circulation pump 8 for further cooling.

[0020] The refrigeration unit 7 described in this utility model is an existing purchased device. The working principle of the refrigeration unit 7 is based on the reverse Carnot cycle. The refrigerant circulates in the evaporator, compressor, condenser and throttling device to transfer heat from the low-temperature object to the high-temperature object, thereby achieving the purpose of refrigeration. The working process includes: (1) Evaporation and heat absorption: The liquid refrigerant boils and evaporates in the evaporator due to the pressure reduction, absorbing the heat of the surrounding objects being cooled (such as air, water, etc.), thereby reducing the temperature of the objects being cooled and achieving the refrigeration effect. In this process, the refrigerant changes from liquid to gas. (2) Compression and pressure increase: The low-temperature and low-pressure gaseous refrigerant from the evaporator is drawn into the compressor. The compressor does work on the refrigerant, increasing its pressure and temperature, turning it into a high-temperature and high-pressure gaseous refrigerant. (3) Condensation and heat release: The high-temperature and high-pressure gaseous refrigerant enters the condenser. In the condenser, the refrigerant exchanges heat with the cooling medium (such as air or water), transferring heat to the cooling medium, and then cooling and condensing into a liquid. In this way, the refrigerant releases heat at high temperature, realizing the transfer of heat from the low-temperature object to the high-temperature object. (4) Throttling and pressure reduction: The liquid refrigerant passes through a throttling device (such as an expansion valve, capillary tube, etc.). Due to the throttling effect, the pressure drops sharply, and the refrigerant becomes a low-temperature, low-pressure liquid. Then it re-enters the evaporator and starts a new cycle. Through such a cycle, the refrigeration unit continuously removes the heat from the object being cooled, maintaining its low-temperature state to meet various refrigeration needs, such as air conditioning systems for indoor cooling and cold storage for food preservation. Different types of refrigeration units (such as piston type, screw type, centrifugal type, absorption type, etc.) may differ in specific structure and working mode, but the basic refrigeration principle is similar.

[0021] As a preferred embodiment, the refrigeration unit 7 is equipped with a circulating water inlet pipe and a circulating water outlet pipe. The circulating water of the sulfuric acid production unit enters the refrigeration unit 7 through the circulating water inlet pipe, and after heat exchange, it is discharged through the circulating water outlet pipe and sent to the circulating water cooling system.

[0022] The cooling system of this embodiment is suitable for any flue gas that needs to be cooled. Example 2

[0023] This embodiment provides a sulfuric acid production apparatus, which is based on an existing sulfuric acid production apparatus and incorporates the flue gas cooling system from Embodiment 1, without making any substantial changes to the sulfuric acid production apparatus. Since the sulfuric acid production apparatus has a well-known structure, this embodiment will not elaborate on other structures of the sulfuric acid production apparatus, but will only describe the location of the flue gas cooling system, as follows: High-temperature sulfur dioxide flue gas (which also contains other impurities) is purified, dusted, cleaned, and cooled, and then connected to the flue gas inlet 3 of the quench tower 1 through a pipeline. After being cooled by the flue gas cooling system, it is transported to the sulfur dioxide drying tower through the cooling flue gas outlet 10 via a pipeline.

[0024] The temperature and moisture content of sulfur dioxide flue gas are correlated: as temperature decreases, the moisture content of the flue gas decreases. When the moisture content of the sulfur dioxide flue gas entering the drying tower decreases, the acid concentration in the drying tower used to dry the sulfur dioxide flue gas can be maintained at a higher temperature. This invention introduces a quench tower 1 between the sulfur dioxide gas cooling tower and the sulfur dioxide drying tower in the sulfuric acid production unit to cool the sulfur dioxide flue gas, thereby maintaining a higher acid concentration for drying. This reduces or avoids corrosion of the drying tower due to decreased acid concentration, effectively reducing or avoiding environmental pollution caused by corrosion-induced holes in the drying tower. After the implementation of this invention, no corrosion of the drying tower occurred, and during shutdown maintenance, inspection of the drying tower revealed no corrosion on the tower wall.

[0025] Simultaneously, because a high concentration of the drying acid can be maintained, the absorption acid connected in series with the drying acid can also maintain a high concentration, thereby increasing the amount of diluting acid used, generating more heat of dilution, and thus increasing the heat output of the sulfuric acid production unit, improving the economic efficiency of sulfuric acid production. This embodiment mainly introduces the flue gas cooling system described in Example 1 into the sulfuric acid production unit to cool the sulfur dioxide flue gas. Specifically, the flue gas cooling system is introduced between the sulfur dioxide gas cooling tower and the sulfur dioxide drying tower of the sulfuric acid production unit. The sulfuric acid production unit is a well-known and mature technology, and this embodiment will not elaborate on the sulfuric acid production unit.

[0026] This embodiment can be applied to both sulfuric acid production plants and smelting flue gas acid production plants.

[0027] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of this utility model.

Claims

1. A flue gas cooling system, characterized in that, The system includes a quench tower (1), a quench tower circulation pump (2), and a heat exchanger assembly. The quench tower (1) is a packed tower. The lower part of the quench tower (1) has a flue gas inlet (3) and a coolant outlet (4), the upper part has a coolant inlet (5), and the top has a cooling flue gas outlet (10). The heat exchanger assembly includes a heat exchanger (6) and a circulating cooling assembly connected to the heat exchanger. The inlet of the quench tower circulation pump (2) is connected to the coolant outlet (4), and the outlet of the quench tower circulation pump (2) is connected to the coolant inlet (5) of the quench tower (1) via the heat exchanger (6).

2. The flue gas cooling system according to claim 1, characterized in that, The circulating cooling component includes a refrigeration unit (7), a chilled water storage tank (9), and a chilled water circulation pump (8); the inlet of the chilled water circulation pump (8) is connected to the chilled water storage tank (9) through a pipe, and the outlet is connected to the refrigeration unit (7) through a pipe; the chilled water inlet of the heat exchanger (6) is connected to the refrigeration unit (7), and the chilled water outlet of the heat exchanger (6) is connected to the chilled water storage tank (9).

3. The flue gas cooling system according to claim 2, characterized in that, The refrigeration unit (7) is equipped with a circulating water inlet pipe and a circulating water outlet pipe.

4. The flue gas cooling system according to claim 1, characterized in that, The heat exchanger (6) is a plate heat exchanger.

5. A sulfuric acid production apparatus, characterized in that, The system includes a flue gas cooling system as described in any one of claims 1 to 4; the flue gas outlet of the sulfur dioxide gas cooling tower of the sulfuric acid production unit is connected to the flue gas inlet (3) of the quench tower (1) via a pipeline, and the cooling flue gas outlet (10) of the quench tower (1) is connected to the sulfur dioxide drying tower via a pipeline.

6. The sulfuric acid production apparatus according to claim 5, characterized in that, The circulating water of the sulfuric acid production unit is connected to the refrigeration unit (7) through a pipeline. The refrigeration unit is equipped with a circulating water return outlet pipe, which is connected to the circulating water cooling system of the sulfuric acid production unit.

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