Cold trap heat exchange equipment for cooling dried tail gas

Abstract

The utility model discloses cold trap heat exchange equipment for cooling drying tail gas, which comprises a shell with a vertical structure, a cooling medium is arranged in the shell, a tail gas inlet is arranged on the shell, an air inlet extension pipe which is downwards inserted into the cooling medium in the shell is connected onto the tail gas inlet, and a heat exchange component which is immersed into the cooling medium is arranged in the shell. A cold source inlet and a cold source outlet which are communicated with the heat exchange assembly are formed outside the shell, a cold source medium is introduced into the heat exchange assembly, a demister is arranged above a cooling medium in the shell, a gap is formed between the demister and the liquid level of the cooling medium, and a tail gas outlet is formed in the top of the shell. According to the utility model, a direct heat exchange mode is adopted, double effects of a shell-and-tube heat exchanger and a washing tower are achieved, a cold source medium and tail gas respectively pass through a tube pass and a shell pass, and the tail gas exchanges heat with the cold source medium in a cooling medium of the shell through the heat exchange assembly. The tail gas passes through the shell pass, the heat exchange assembly cannot be blocked, and the equipment is simple in overall structure, small in occupied area, low in investment and low in energy consumption.

Description

Technical Field

[0001] The utility model relates to a cold trap heat exchange device for drying tail gas cooling, belonging to the technical field of chemical separation equipment. Background Art

[0002] Existing cooling equipment for drying exhaust gas typically utilizes a partitioned shell-and-tube heat exchanger, where exhaust gas flows through the tube side and cooling water flows through the shell side. Due to impurities in the exhaust gas, this partitioned shell-and-tube heat exchanger typically becomes severely clogged after approximately six months of operation, necessitating cleaning. This process is not only cumbersome but also disrupts the entire drying process. Furthermore, drying exhaust gas typically has a high moisture content and latent heat, requiring a significant heat exchange capacity. Using a partitioned heat exchanger requires a large heat exchange area and cooling circulating water, resulting in significant floor space and investment costs.

[0003] In addition, the prior art also uses a washing tower to directly cool the exhaust gas. This equipment consumes a large amount of process water. The process water is in direct contact with the exhaust gas and has a certain washing effect, but it also contaminates the incoming process water and produces more wastewater. The wastewater needs to be treated secondary, and process water resources are wasted. Utility Model Content

[0004] The purpose of the utility model is to provide a cold trap heat exchange device for drying exhaust gas cooling, which is used to solve the technical problems of the existing cooling equipment in that it occupies a large area, has high investment costs and wastes water resources.

[0005] The utility model adopts the following technical solution: a cold trap heat exchange device for drying exhaust gas cooling, which includes a shell with a vertical structure, a cooling medium is installed in the shell, an exhaust gas inlet is provided on the shell, the exhaust gas inlet is connected to an air intake extension pipe inserted downward into the cooling medium in the shell, a heat exchange component immersed in the cooling medium is provided in the shell, a cold source inlet and a cold source outlet connected to the heat exchange component are provided outside the shell, the heat exchange component is used to pass the cold source medium, a demister is provided above the cooling medium in the shell, there is a gap between the demister and the liquid level of the cooling medium, and an exhaust gas outlet is provided at the top of the shell.

[0006] The exhaust gas inlet is arranged on the top of the shell, and the air intake extension pipe is inserted into the cooling medium from top to bottom.

[0007] The depth of the air intake extension pipe inserted into the cooling medium is 50-300 mm.

[0008] A water supply inlet is provided on the top of the shell. A nozzle is provided on one end of the water supply inlet located inside the shell. The nozzle is located above the demister.

[0009] The shell is provided with a spray water replenishing port for replenishing water in the shell, and the spray water replenishing port is connected to the outer wall of the shell obliquely downward.

[0010] An overflow port is provided on the shell at the liquid level of the cooling medium, and the overflow port is located between the bottom surface of the demister and the bottom end of the air inlet extension pipe; a sewage outlet is provided at the bottom of the shell.

[0011] A partition is provided in the shell at a position below the liquid level and above the lower end of the air inlet extension pipe. Air holes are evenly distributed on the partition, and the position of the partition is lower than the overflow port.

[0012] The heat exchange component adopts a heat exchange tube, and both ends of the heat exchange tube are connected to the cold source inlet and the cold source outlet through a pipe box respectively.

[0013] The heat exchange tube is a spiral coil, and the position of the cold source outlet is higher than the cold source inlet; the cooling medium is water, and the cold source medium is chilled water.

[0014] The shell includes a vertically arranged cylinder and an upper head connected to the upper end of the cylinder, and the upper head and the cylinder are connected via a flange.

[0015] There are two demisters, which are spaced apart in an upper and lower position. The demisters are wire mesh, ridge, tube or baffle demisters.

[0016] The beneficial effects of the present invention are as follows: during operation, the cold source medium is first introduced into the cold source inlet and then discharged from the cold source outlet to form a cycle. At the same time, the front-end dried exhaust gas enters the shell from the exhaust gas inlet through the extended pipe orifice. Before operation, a certain amount of process water is introduced into the shell as a cooling medium to submerge the heat exchange component. The dried exhaust gas enters below the liquid level of the shell and directly exchanges heat with the liquid in the shell. The exhaust gas after condensation and heat exchange passes through the demister and is discharged from the exhaust gas outlet.

[0017] This utility model adopts a direct heat exchange method, combining the dual functions of a shell and tube heat exchanger and a scrubber. The cooling medium and exhaust gas flow through the tube side and shell side respectively. The exhaust gas exchanges heat with the cooling medium through the heat exchange component in the cooling medium of the shell. The exhaust gas flows through the shell side, which will not clog the heat exchange component, so there is no need to clean the heat exchange component frequently. The heat exchange component itself can adopt heat exchange tubes such as spiral wound tubes or spiral coils, and the tube diameter can be smaller (for example, φ4, φ6, φ8, φ10, φ12, etc.), which has a wider range of options, is easier to process, has a compact structure and requires a smaller area. The overall equipment is simple, occupies a small area, has low investment, low energy consumption, has great economic and environmental benefits, and has high application value.

[0018] Furthermore, the present invention features a water inlet at the top of the device and a nozzle installed on the inlet. This inlet is used to spray the exhaust gas, effectively removing the latent heat of vaporization from the exhaust gas. Due to the principles of water vapor partial pressure mass transfer and convective heat transfer, the water spraying process effectively increases the contact area between the liquid water droplets and the water vapor, enhancing the heat exchange effect and increasing the heat transfer coefficient by more than 10 times. This reduces the heat exchange area required by the cold trap. As the exhaust gas enters the cold trap heat exchanger, the water vapor in the exhaust gas enters the liquid water. Since the water temperature is low and the saturated pressure of the water vapor is high, the water vapor migrates into the liquid water, transforming from a gaseous state to a liquid state, where it is condensed and absorbed. The dew point and moisture content of the condensed exhaust gas are lowered, allowing it to be discharged from the exhaust outlet under negative pressure. The nozzle design not only removes the latent heat of water vapor from the exhaust gas to the greatest extent possible while replenishing water but also provides a flushing effect on the demister. The condensed liquid water is then condensed by the chilled water in the heat exchanger assembly, maintaining the thermal balance of the cold trap.

[0019] Furthermore, the condensed water and the spray water are eventually discharged from the overflow port, thus maintaining the water balance of the cold trap equipment. The overflow port and drain port are designed on the shell, which simplifies the liquid level control and eliminates the need for a liquid level meter and material level control.

[0020] Furthermore, a partition is provided below the liquid level and between the upper end of the air inlet extension tube, which can increase the contact time between the gas in the air inlet extension tube and the liquid in the shell, making the heat exchange more sufficient; at the same time, the gas is discharged from the air holes on the partition after heat exchange.

[0021] Furthermore, setting up two demisters can effectively reduce the entrainment of dust particles and liquid foam in the exhaust gas and improve the relative dryness of the exhaust gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a cold trap heat exchange device for drying exhaust gas cooling according to an embodiment of the present invention.

[0023] In the figure: 1-upper head, 2-flange, 3-demister, 4-shell, 5-heat exchange component, 6-inlet extension pipe, 7-nozzle, 8-pipe box, 9-partition, N1-exhaust gas inlet, N2-exhaust gas outlet, N3-cold source inlet, N4-cold source outlet, N5-water inlet, N6-overflow, N7-drain outlet, N8-spray water inlet. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1As shown, a cold trap heat exchange device for drying exhaust gas cooling according to an embodiment of the present invention includes a shell 4 of a vertical structure, wherein a cooling medium is contained in the shell 4, an exhaust gas inlet N1 is provided on the shell 4, and an air intake extension pipe 6 is connected to the exhaust gas inlet N1 and is downwardly inserted into the cooling medium in the shell 4, a heat exchange component 5 immersed in the cooling medium is provided in the shell 4, a cold source inlet N3 and a cold source outlet N4 connected to the heat exchange component 5 are provided outside the shell 4, and the heat exchange component 5 is used to pass the cold source medium, a demister 3 is provided above the cooling medium in the shell 4, and there is a gap between the demister 3 and the liquid level of the cooling medium, and an exhaust gas outlet N2 is provided at the top of the shell 4.

[0026] The exhaust inlet is located at the top of the housing, and the intake extension pipe is inserted into the cooling medium from top to bottom. The depth of the intake extension pipe inserted into the cooling medium is 50-300mm. The bottom end of the intake extension pipe 6 is higher than the heat exchange component 5.

[0027] The housing 4 is provided with a water replenishment inlet N5 at the top. A nozzle 7 is located on one end of the inlet N5, located within the housing 4. The nozzle 7 is positioned above the demister 3. The nozzle 7 is a solid cone nozzle made of stainless steel, polytetrafluoroethylene, or polypropylene. The housing 4 is also provided with a spray water replenishment port N8 for replenishing water within the housing 4. The spray water replenishment port N8 is positioned diagonally downward on the outer wall of the housing 4 and is located between the bottom end of the air inlet extension pipe 6 and the heat exchange assembly 5. A sewage outlet is provided at the bottom of the housing.

[0028] The shell 4 includes a vertically arranged cylinder and an upper head 1 connected to the upper end of the cylinder, and the upper head 1 and the cylinder are connected by a flange 2. The exhaust gas inlet N1, the exhaust gas outlet N2 and the water supply inlet N5 are all arranged on the upper head 1, and the shell 4 can be opened through the flange 2 to inspect and repair the heat exchange component 5 inside the shell 4. An overflow port N6 is provided on the shell 1 at the liquid level of the cooling medium. The overflow port N6 is located between the bottom surface of the demister 3 and the bottom end of the air inlet extension pipe 6; a sewage outlet N7 is provided at the bottom of the shell 1. A partition 9 is provided in the shell 4 below the liquid level and above the lower end of the air inlet extension pipe 6. Air holes are evenly distributed on the partition 9, and the partition 9 is located lower than the overflow port N6.

[0029] The heat exchange assembly 5 utilizes heat exchange tubes, each connected to the cold source inlet N3 and outlet N4 via a pipe box 8. The heat exchange tube inlet and outlet communicate with the pipe box 8, which inlet and outlet connect to the first cold source inlet N3 and outlet N4, respectively. The pipe box 8 and the pipe connections are removable. The heat exchange tubes can be single or multiple, and are spirally coiled, with the cold source outlet positioned higher than the cold source inlet. The cooling medium is water, and the cold source medium is chilled water.

[0030] There are two demisters 3, which are spaced apart from each other. The demisters 3 are wire mesh, ridge, tube or baffle demisters. The demisters can also be single-layer or multi-layer structures.

[0031] The diameter ratio of the first water supply inlet N5 to the first cold source inlet N3 is 0.25 to 0.8. During operation, the water supply flow rate is about 0.05 to 0.5 of the cold source flow rate. The cold source water uses ordinary cooling cycle or chilled water, and the water supply uses process water.

[0032] The following is a specific operating example of the present invention: the tail gas mass flow rate at the outlet of the front-end drying equipment is 125kg / h (including 30kg / h of water vapor and the rest of nitrogen, with a dust particle concentration of 10PPm), the tail gas temperature is 295°C, and is connected to the tail gas inlet through a pipeline;

[0033] External chilled water, volume flow rate 10m 3 / h, temperature 7℃, connected to the cold source inlet through a pipeline; external process water volume flow rate 1.5m 3 / h, the temperature is 25℃, and it is connected to the water supply inlet. During operation, chilled water is first introduced from the cold source inlet and then discharged from the cold source outlet to form a cycle. At the same time, the front-end drying exhaust gas enters the shell through the extension pipe from the exhaust gas inlet. Before operation, a certain amount of process water is introduced into the shell to submerge the heat exchange components. The drying exhaust gas enters below the liquid level of the shell and directly exchanges heat with the liquid in the shell. Part of the water vapor (carrying latent heat of vaporization) directly exchanges heat with the process water injected from the water supply inlet in a countercurrent manner, and is condensed into condensed water and enters the shell to mix with the process water. The amount of liquid increased in the shell is 1.5m3 of process water supply. 3 / h, 29.7kg / h of exhaust condensate produces a total of approximately 1529.7kg. After condensation and heat exchange, the exhaust gas passes through a two-stage demister and is discharged from the exhaust outlet, which is connected to an external induced draft fan. Condensate within the shell is continuously discharged through the overflow port. During operation, the internal pressure of the shell is controlled at -5kPa to -15kPa. After condensation, when the exhaust gas outlet temperature is approximately 30°C, water replenishment is stopped.

[0034] For 100m 3 / The project requires drying and cooling the exhaust gas to below 40°C at a dry-bulb temperature of 300°C and a dew point of 85°C. The required heat exchange capacity is Q = 45kW, of which 35kW is latent heat of vaporization and 5kW is sensible heat.

[0035] The heat exchange area required by the cold trap heat exchange equipment provided by the utility model is 2.5m 2 , the shell diameter is 500mm and the height is 2m. The area required for the partition wall shell and tube heat exchanger is 20m 2The equipment needs to be 650mm in diameter and 4.5m in length. The process water required for the washing tower is 7.5m 3 / h, while the process water required by the cold trap heat exchange equipment provided by the utility model is 1m 3 / h.

[0036] In summary, this cold trap heat exchanger combines the dual functions of a shell-and-tube heat exchanger and a scrubber, and its reliability has been proven in drying projects. Furthermore, the heat exchange components employed in this invention feature a compact overall heat exchange tube structure, a large heat exchange area per unit volume, and a high heat transfer coefficient, significantly reducing overall size, saving floor space and investment costs, and delivering significant economic and environmental benefits.

[0037] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. The scope of the present invention defined by the appended claims includes all equivalent substitutions and variations.

Claims

1. A cold trap heat exchange device for drying exhaust gas cooling, characterized by: It includes a vertical shell, in which a cooling medium is contained, an exhaust gas inlet is provided on the shell, the exhaust gas inlet is connected to an air intake extension pipe which is inserted downward into the cooling medium in the shell, a heat exchange component immersed in the cooling medium is provided in the shell, a cold source inlet and a cold source outlet which are connected to the heat exchange component are provided outside the shell, the heat exchange component is used to pass the cold source medium, a demister is provided above the cooling medium in the shell, a gap is provided between the demister and the liquid level of the cooling medium, and an exhaust gas outlet is provided at the top of the shell.

2. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: The exhaust gas inlet is arranged on the top of the shell, and the air intake extension pipe is inserted into the cooling medium from top to bottom.

3. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: The depth of the air intake extension pipe inserted into the cooling medium is 50-300 mm.

4. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: A water supply inlet is provided on the top of the shell. A nozzle is provided on one end of the water supply inlet located inside the shell. The nozzle is located above the demister.

5. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: The shell is provided with a spray water replenishing port for replenishing water in the shell, and the spray water replenishing port is connected to the outer wall of the shell obliquely downward.

6. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: An overflow port is provided on the shell at the liquid level of the cooling medium, and the overflow port is located between the bottom surface of the demister and the bottom end of the air inlet extension pipe; a sewage outlet is provided at the bottom of the shell.

7. The cold trap heat exchange equipment for drying tail gas cooling according to claim 6, characterized in that: A partition is provided in the shell at a position below the liquid level and above the lower end of the air inlet extension pipe. Air holes are evenly distributed on the partition, and the position of the partition is lower than the overflow port.

8. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: The heat exchange component adopts a heat exchange tube, and the two ends of the heat exchange tube are respectively connected to the cold source inlet and the cold source outlet through a pipe box; the heat exchange tube adopts a spiral coil, and the position of the cold source outlet end is higher than the cold source inlet end; the cooling medium is water, and the cold source medium is chilled water.

9. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: The shell includes a vertically arranged cylinder and an upper head connected to the upper end of the cylinder, and the upper head and the cylinder are connected via a flange.

10. The cold trap heat exchange equipment for drying exhaust gas cooling according to claim 1, characterized in that: There are two demisters, which are spaced apart in an upper and lower position. The demisters are wire mesh, ridge, tube or baffle demisters.

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