A lye condensation assembly for an indigo production line and method thereof

Abstract

This invention discloses an alkali condensation assembly and method for an indigo production line, mainly relating to indigo production. It includes a triple-effect evaporator, a preheating pot connected to the triple-effect evaporator, and a heat exchange evaporator connected to the preheating pot via pipeline. The bottom of the heat exchange evaporator is located inside the furnace body. The heat exchange evaporator includes a heating section at the bottom, a heat exchange section in the middle, and a feeding section at the top. The top of the feeding section has an overflow outlet. The beneficial effects of this invention are: it concentrates the diluted alkali solution in the indigo production line by using different heat exchange media to progressively concentrate the alkali solution; the heat exchange evaporator uses the flue gas generated during combustion in the burner to further concentrate the alkali solution; and by utilizing the membrane evaporation principle, the heat exchange evaporator achieves higher evaporation efficiency when concentrating the alkali solution, and the evaporated steam in the solution is recovered and reused.

Description

Technical Field

[0001] This invention relates to the field of indigo production, specifically to an alkaline condensation assembly and method for an indigo production line. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] The indigo production line requires a large amount of alkali solution. From an environmental perspective, it's necessary to recycle the low-concentration alkali solution generated after use. This is achieved by evaporating and concentrating the alkali solution before recycling. Current concentration methods involve heating the bottom of a steamer with a burner to evaporate excess water from the alkali solution inside. However, because the heat exchange area of ​​the steamer is only at the bottom, the overall evaporation efficiency is low, resulting in significant energy waste. Furthermore, the existing steamer in the production line is open, causing environmental pollution and heat loss when heating the alkali solution. Traditional heating methods also have limitations. Since the alkali solution's precipitation temperature is 190 degrees Celsius, crystallization occurs after precipitation and settles at the bottom of the heating container, affecting heating efficiency. Therefore, direct heating methods are constrained by these limitations.

[0004] Therefore, to further improve the efficiency and environmental friendliness of alkali concentration in the production line, the flue gas generated during combustion is utilized. This allows the alkali solution to be heated by the flue gas after entering the tubes. However, two problems have arisen that need to be addressed: First, due to the hardness of the water in the alkali solution, long-term heating and condensation will cause scale to form inside the heat exchange tubes. Excessive scale buildup will affect heat exchange efficiency, reducing the overall heat exchange efficiency of the production line by 20%. Therefore, the scale layer inside the heat exchange tubes needs to be cleaned. However, the existing heat exchange equipment has limited internal space and is enclosed, and many internal components are corroded by chemical reagents, limiting cleaning methods. Second, because the flue gas heats the tubes in a dedicated space, prolonged heating will generate a large amount of soot within this space. This soot will adhere to the surface of the heat exchange tubes, affecting heat exchange, and will also accumulate in the independent space, affecting the flow of the flue gas. This will cause uneven heating of the heat exchange tubes, and long-term accumulation will significantly impact heat exchange efficiency. Therefore, these problems urgently need to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide an alkali condensation assembly and method for an indigo production line. It can concentrate the diluted alkali solution in the indigo production line by using different heat exchange media to concentrate the alkali solution in stages. The heat exchange evaporation device uses the flue gas generated during combustion of the burner to concentrate the alkali solution a second time. By utilizing the membrane evaporation principle, the heat exchange evaporation device has higher evaporation efficiency when concentrating the alkali solution. In addition, the vapor evaporated in the solution can be recovered and reused during the entire concentration process.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] An alkaline condensation assembly for an indigo production line includes a triple-effect evaporator, a preheating pot connected to the triple-effect evaporator, and a heat exchange evaporator connected to the preheating pot via a pipeline.

[0008] The bottom of the heat exchange evaporation device is located inside the furnace body. The heat exchange evaporation device includes a heating part located at the bottom of the heat exchange evaporation device, a heat exchange part located in the middle of the heat exchange evaporation device, and a feeding part located at the top of the heat exchange evaporation device. The top of the feeding part is provided with an overflow port.

[0009] The feeding section is connected to the preheating pot via a pipeline. A burner is installed at the bottom of the heating section for heating. A discharge pipe is inserted into the bottom of the heating section. The heat exchange section includes an air inlet at the bottom and an air outlet at the top. Multiple heat exchange tubes are installed within the heat exchange section, and multiple semi-circular grooves are arranged in an array on each heat exchange tube. The bottom of each heat exchange tube communicates with the heating section, and the top of each heat exchange tube communicates with the feeding section. Alkali solution flows inside the heat exchange tubes. Multiple baffles are staggered within the heat exchange section. A descaling section is provided on the outer wall of the heat exchange tubes, and the descaling section operates symmetrically with respect to the baffles. In a mirror configuration, the descaling unit includes a negative pressure adsorption component and multiple descaling components connected to the negative pressure adsorption component. Each descaling component has multiple flow channel cavities. The negative pressure airflow generated by the negative pressure adsorption component draws in soot through the flow channel cavities. At the same time, air flows at high speed through the narrow flow channel cavities. The negative pressure airflow will generate vibrations by friction at the intake port and wall surface of the flow channel cavities, causing the descaling components at different positions to resonate on the heat exchange tube. Multiple semi-circular grooves on the heat exchange tube destroy the complete surface of the scale adhesion, making it easier to destroy the bonding layer formed by the scale on the inner wall of the heat exchange tube, thereby descaling multiple positions on the heat exchange tube.

[0010] The heat exchange section is also provided with a fixing component for fixing multiple heat exchange tubes. The fixing component includes a fixing plate and multiple spacer tubes. The fixing plate is divided into upper and lower parts. The fixing plate is used for both ends of multiple heat exchange tubes, and both ends of the heat exchange tubes are exposed on the fixing plate. Multiple baffles are arranged on the spacer tubes.

[0011] The feeding section is provided with a first and a second feeding pipe distributed vertically, and the inlet of the second feeding pipe is provided with a guide pipe; a diversion component is provided below the inlet of the first feeding pipe located at the upper part, the diversion component includes a diversion trough, a first grid plate and a second grid plate located below the diversion trough; the diversion trough includes a water storage tank and multiple drain outlets, and the bottom of the water storage tank is provided with a drain hole; both the first grid plate and the second grid plate are provided with multiple water passage holes, the density of water passage holes in the second grid plate is greater than the density of water passage holes in the first grid plate, and the second grid plate is connected to the guide pipe.

[0012] The overflow port of the feed section is connected to a recycling component, which receives the steam overflowing from the overflow port, processes the steam into condensate, and thus maintains a negative pressure state inside the heat exchange evaporator. The recycling component includes a heat exchange element, a shell-and-tube heat exchanger connected to the heat exchange element, and a recovery tank connected to the shell-and-tube heat exchanger. The descaling component includes a shell, a connection port on the shell, and multiple suction ports on the shell, with gaps between the suction ports.

[0013] The furnace body is equipped with a receiving tank connected to the discharge pipeline and a burner that heats the bottom of the receiving tank.

[0014] The triple-effect evaporator includes three evaporators, each comprising a heat exchanger and an evaporation tower. Air is introduced into the heat exchanger of the first-effect evaporator to heat the alkaline solution in the evaporation tower. The steam generated after the first evaporation, along with external steam, enters the second-effect heat exchanger. The alkaline solution after the first evaporation is then pumped into the evaporation tower of the second-effect evaporator. The steam generated after the second evaporation, along with external steam, enters the third-effect heat exchanger. The alkaline solution after the second evaporation is then pumped into the evaporation tower of the third-effect evaporator. The alkaline solution in the third-effect evaporation tower is then pumped into the preheating pot after evaporation.

[0015] A method for using an alkaline condensation assembly for an indigo production line, S1, a low-concentration alkaline solution is initially evaporated by a triple-effect evaporator. After the alkaline solution is initially evaporated by the triple-effect evaporator, it is pumped into a preheating pot by a pump body, and then pumped into a heat exchange evaporation device from the preheating pot.

[0016] S2, the heat exchange evaporation device performs secondary evaporation on the alkaline solution after primary evaporation. The alkaline solution is diverted from the feed pipe according to the flow rate and enters the heat exchange evaporation device. Then it flows into the upper fixed plate. When the liquid level on the upper fixed plate is higher than the distance from the heat exchange tube to the upper fixed plate, the alkaline solution slowly flows into the heat exchange tube.

[0017] S3. Simultaneously, the burner heats the bottom of the heating section. The flue gas generated by the burner enters the heat exchange section through the inlet. The heat of the flue gas heats the alkaline solution in the heat exchange tube, causing the water in the alkaline solution inside the heat exchange tube to evaporate. The solution then enters the heating section through the heat exchange tube. The alkaline solution collected at the bottom of the heat exchange tube is then pumped into the receiving tank through the discharge pipe. The burner heats and concentrates the bottom of the receiving tank until the alkaline solution is anhydrous.

[0018] S4, the water in the alkaline solution inside the heat exchange tube evaporates and overflows from the overflow port into the heat exchange element of the recycling component, becoming condensate. At the same time, the heat exchange evaporation device is under negative pressure. The shell and tube heat exchanger performs secondary recovery of the steam entering the heat exchange element and enters the recovery tank.

[0019] S5. When descaling or cleaning of soot in the heat exchange section is required, turn on the negative pressure adsorption component. The negative pressure airflow generated by the adsorption component will draw the soot into the flow channel. At the same time, the air flows through the narrow flow channel cavity at high speed. The negative pressure airflow will generate vibration by friction on the flow channel cavity wall, so that it resonates with the heat exchange tube while drawing in the soot, drawing the soot into the negative pressure adsorption component. At the same time, the scale on the inner wall of the heat exchange tube is peeled off by vibration.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This device can concentrate the diluted alkaline solution in the indigo production line. It uses different heat exchange media to concentrate the alkaline solution step by step. The heat exchange evaporation device uses the flue gas generated during combustion of the burner to concentrate the alkaline solution a second time. By using the membrane evaporation principle, the heat exchange evaporation device has a higher evaporation efficiency when concentrating the alkaline solution. In addition, the vapor evaporated in the solution can be recovered and reused throughout the concentration process. Attached Figure Description

[0022] Appendix Figure 1 This is a flowchart of the two-stage evaporation process of the present invention.

[0023] Appendix Figure 2 This is a flow chart of the triple-effect evaporator in this invention.

[0024] Appendix Figure 3 This is a view of the heat exchange evaporation device in this invention.

[0025] Appendix Figure 4 This is a view of the heat exchange section in this invention.

[0026] Appendix Figure 5 This is a cross-sectional view of the heat exchange section in this invention.

[0027] Appendix Figure 6 This is a view of the feeding section in this invention.

[0028] Appendix Figure 7 This is an enlarged view of the second feed pipe in this invention.

[0029] Appendix Figure 8 This is a view of the flow divider in this invention.

[0030] Appendix Figure 9 This is a view of a single heat exchange tube and descaling assembly in this invention.

[0031] Appendix Figure 10 This is an enlarged view of the descaling component in this invention.

[0032] Appendix Figure 11 This is a cross-sectional view of the descaling component in this invention.

[0033] The labels shown in the attached diagram:

[0034] 1. Triple-effect evaporator; 2. Preheating pot; 3. Heat exchange evaporator; 4. Furnace body; 5. Heating section; 6. Heat exchange section; 7. Feed section; 8. Overflow outlet; 9. Burner; 10. Discharge pipe; 11. Air inlet; 12. Air outlet; 13. Heat exchange tube; 14. Baffle plate; 15. Descaling assembly; 16. Flow channel cavity; 17. Semi-circular groove; 18. Fixing plate; 19. Spacing tube; 20. Guide pipe; 21. First feed pipe; 22. Second feed pipe; 23. 24. Flow guide pipe; 25. Diversion channel; 26. First grid plate; 27. Second grid plate; 28. Water storage tank; 29. ​​Drain outlet; 30. Drain hole; 31. Water passage hole; 32. Heat exchanger; 33. Shell and tube heat exchanger; 34. Recovery tank; 35. Shell; 36. Connection port; 37. Suction port; 38. Evaporation tower; 39. First-effect evaporator; 40. Second-effect evaporator; 41. Third-effect evaporator; 42. Receiving tank; 43. Steam; 44. Unconcentrated alkali solution; 45. Flow channel cavity. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0036] This invention describes an alkali condensation assembly and method for an indigo production line. First, the process flow of the production line is described. Since the indigo production line requires a large amount of alkali solution, and as mentioned in the background art, the precipitation temperature of the alkali solution is 190 degrees Celsius, when heated using traditional methods, the alkali solution crystallizes and settles at the bottom of the heating container, affecting heating. Therefore, the existing direct heating method is limited by this. Therefore, in order to change the alkali solution from a low concentration to anhydrous (molten) alkali solution, it is necessary to gradually increase the concentration of the alkali solution through heat exchange evaporation.

[0037] As shown in the attached diagram of the instruction manual. Figure 2 As shown, the triple-effect evaporator 1 includes three evaporators, each including a shell-and-tube heat exchanger 32 and an evaporation tower 37. Air is introduced into the shell-and-tube heat exchanger 32 of the first-effect evaporator 38 to heat the alkaline solution in the evaporation tower 37. The steam 42 generated after the first evaporation, together with external steam 42, enters the second-effect heat exchanger. The alkaline solution after the first evaporation is pumped into the evaporation tower 37 of the second-effect evaporator 39. The steam 42 generated after the second evaporation, together with external steam 42, enters the third-effect heat exchanger. The alkaline solution after the second evaporation is pumped into the evaporation tower 37 of the third-effect evaporator 40. The alkaline solution in the third-effect evaporation tower 37 is then pumped into the preheating pot 2 after evaporation. The low-concentration alkali solution produced in the production line is initially evaporated by three evaporators. The first-effect evaporator 38 initially evaporates the unconcentrated alkali solution 43, and the water vapor 42 evaporated from the alkali solution is recycled to the second-effect evaporator 39. At the same time, the cooled steam 42 can also be used as circulating water, which saves energy and can also recycle water. After the alkali solution is initially evaporated by the third-effect evaporator 40, it is pumped into the preheating pot 2. The preheating pot 2 preheats the alkali solution to prevent the ambient temperature from being too low and affecting the evaporation efficiency of the next process.

[0038] As shown in the attached diagram of the instruction manual. Figure 1 As shown, the bottom of the heat exchange evaporation device 3 is set inside the furnace body 4. The heat exchange evaporation device includes a heating part 5 located at the bottom of the heat exchange evaporation device, a heat exchange part 6 in the middle of the heat exchange evaporation device, and a feeding part 7 at the top of the heat exchange evaporation device. The top of the feeding part 7 is provided with an overflow port 8.

[0039] As shown in the attached diagram of the instruction manual. Figure 1 and Figure 3 As shown, the furnace body 4 has a discharge pipe 10 inserted into the bottom of the heating part 5, and a receiving tank 41 inside the furnace body 4. The receiving tank 41 is connected to the discharge pipe 10, and a burner 9 is provided at the bottom of the receiving tank 41 for heating.

[0040] The heating section 5 stores the alkaline solution after evaporation through the membrane in the heat exchange section 6. However, the heat exchange section 6 cannot completely evaporate the water in the alkaline solution, so a burner 9 is installed at the bottom of the heating section 5 for heating, allowing the water in the alkaline solution in the heating section 5 to evaporate as much as possible. Then, it is pumped into the receiving tank 41 through the discharge pipe 10. At this time, the concentration of the alkaline solution inside the receiving tank 41 is very high, but a small amount of water still remains. Therefore, a burner 9 is installed at the bottom of the receiving tank 41 for heating, concentrating the alkaline solution to an anhydrous state. At the same time, as the water in the alkaline solution gradually overflows, the precipitation temperature of the alkaline solution, which is initially 190 degrees Celsius, gradually changes to a solidification temperature of 500 degrees Celsius as the concentration increases. Therefore, it is also necessary to heat the receiving tank 41 to make its temperature higher than the solidification temperature, so that the alkaline solution in the receiving tank 41 remains in a molten state, which also facilitates the transportation of the alkaline solution. The flue gas generated by the burner 9 can also be transported to the heat exchange section 6 for heating. The specific structure of the heat exchange section 6 is as follows:

[0041] As shown in the attached diagram of the instruction manual. Figure 3 — Figure 5 As shown, the heat exchange section 6 includes an air inlet 11 at the bottom of the heat exchange section 6 and an air outlet 12 at the top of the heat exchange section 6. The heat exchange section 6 is provided with a plurality of heat exchange tubes 13, and a plurality of semi-circular grooves 17 are arranged in an array on the heat exchange tubes 13. The bottom of the heat exchange tubes 13 is connected to the heating section 5, and the top of the heat exchange tubes 13 is connected to the feeding section 7. Alkali solution flows inside the heat exchange tubes 13. A plurality of baffles 14 are staggered inside the heat exchange section 6. The air inlet 11 is used to recover the flue gas generated during the combustion of the burner 9. Since the flue gas also has heat when the burner 9 is burning, in order to make full use of energy, the flue gas generated by the burner 9 is introduced into the air inlet 11 of the heat exchange section 6. The heat of the flue gas heats the alkaline solution in the heat exchange tube 13. In order to make the flue gas stay in the heat exchange section 6 for a long time and flow in an orderly manner, and further improve the heat exchange efficiency, the flow direction of the flue gas is controlled by multiple staggered baffles 14, which flow upward according to the flow channel direction of the baffles 14.

[0042] As shown in the attached diagram of the instruction manual. Figure 3 — Figure 5 As shown, for fixing the heat exchange tubes 13, the heat exchange section 6 is also provided with fixing components for fixing multiple heat exchange tubes 13. The fixing components include a fixing plate 18 and multiple spacer tubes 19. The fixing plate 18 is divided into upper and lower parts. The fixing plate 18 is used for both ends of multiple heat exchange tubes 13, and both ends of the heat exchange tubes 13 are exposed on the fixing plate 18. The heat exchange tubes 13 are welded to the fixing plate 18. Multiple baffles 14 are arranged on the spacer tubes 19.

[0043] The connection between the fixed plate 18 and the heat exchange tube 13 is shown in the attached diagram of the instruction manual. Figure 4As shown, the heat exchange tube 13 protrudes a distance from the upper fixed plate 18. The alkaline solution flows into the upper fixed plate 18 through the inlet pipe (described below). When the liquid level on the upper fixed plate 18 is higher than the distance protruding from the heat exchange tube 13, the alkaline solution slowly flows into the heat exchange tube 13. Due to the relatively long length of the heat exchange tube 13, after flowing into multiple heat exchange tubes 13, the low-concentration alkaline solution inside the heat exchange tubes 13 is heated by flue gas, forming a falling film evaporation in the heat exchange tubes 13. Steam 42 overflows from the feed section 7 and is recovered. After evaporation, the high-concentration alkaline solution has a density greater than water and flows into the heating section 5 by its own weight. The falling film evaporation principle utilizes the formation of a thin film of liquid on the tube wall, completing the heat transfer process through evaporation and condensation. The heating section 5 is equipped with a discharge pipe 10, which leads directly to the bottom of the heating section 5. High-concentration alkaline solution flowing from the heat exchange tube 13 to the bottom of the heating section 5 is collected and discharged through the discharge pipe 10. Specifically, after the high-concentration alkaline solution enters the heat exchange tube 13, a thin film forms on the tube wall. At this time, the liquid temperature rises due to the heating of the heat exchange tube 13 by the flue gas, thus generating steam. The steam rises inside the pipe and comes into contact with the external cooling medium, causing the steam to condense into liquid and release a large amount of heat. Through continuous circulation, the high-concentration alkaline solution completes the evaporation process inside the heat exchange tube 13, ultimately achieving concentration. Throughout the process, the formation of the alkaline film and the alternation of evaporation and condensation continuously ensure full utilization of heat and improve heat transfer efficiency.

[0044] It is particularly important to note that, regarding the factors influencing the formation of the aforementioned thin film, the flow rate of the alkali solution entering the heat exchange tube 13 needs to be controlled; the flow rate cannot be too fast. To control the flow rate of the alkali solution entering the heat exchange section 6, the heat exchange tube 13 is further improved: multiple semi-circular grooves 17 are arranged in an array on the heat exchange tube 13. The protrusion direction of the semi-circular grooves 17 can be either towards the inside or outside of the tube, but for ease of processing, a protrusion towards the inside of the tube is chosen. When the alkali solution flows slowly inside the heat exchange tube 13, because the tube wall is not a smooth surface, the semi-circular grooves 17 change the flow direction of the alkali solution as it flows through them, thus obstructing the flow and further slowing down the flow rate. However, for the decisive control of the flow rate inside the heat exchange tube 13, the feed section 7 still needs to control it. The specific structure is as follows:

[0045] As shown in the attached diagram of the instruction manual. Figure 6 — Figure 8As shown, the feeding section 7 is connected to the preheating pot 2 via a pipeline. The feeding section 7 is provided with a first and a second feeding pipeline 22 distributed vertically. For the two feeding pipelines, the first feeding pipeline 21 located at the top is used to enter the alkaline solution when the flow rate in the production line is too large. A diversion assembly is provided below the opening of the first feeding pipeline 21 located at the top. The diversion assembly includes a diversion trough 24, a first grid plate 25 located below the diversion trough 24, and a second grid plate 26. The diversion trough 24 includes a water storage tank 27 and multiple drain outlets 28. A drain hole 29 is provided at the bottom of the water storage tank 27. Both the first grid plate 25 and the second grid plate 26 are provided with multiple water passage holes 30. The density of the water passage holes 30 in the second grid plate 26 is greater than that in the first grid plate 25. The second grid plate 26 is connected to the guide pipe 23.

[0046] When the alkali solution flows into the water storage tank 27 from the first feed pipe 21, it flows downward through the drain hole 29 of the water storage tank 27. Since the flow velocity of the first feed pipe 21 is greater than the flow velocity of the drain hole 29, the alkali solution will accumulate inside the water storage tank 27. After the liquid level inside the water storage tank 27 rises, it continues to flow downward through the drain outlet 28, passing through the first grid plate 25 and the second grid plate 26. The first grid plate 25 and the second grid plate 26 impede the flow of the alkali solution step by step, so that the alkali solution is prevented from quickly entering the heat exchange tube 13 after flowing into the upper fixed plate 18.

[0047] A guide pipe 23 is provided at the inlet of the second feed pipe 22. The guide pipe 23 is half of a circular pipe. When the alkali solution flows downward through the second feed pipe 22, it can flow into the upper fixed plate 18. When the liquid level in the upper fixed plate 18 is higher than the distance from the heat exchange tube 13 to the upper fixed plate 18, the alkali solution slowly flows into the heat exchange tube 13. The heat exchange and evaporation process of the alkali solution by the heat exchange tube 13 has been described above. The evaporated water overflows from the overflow port 8 of the feed section 7. The overflow port 8 of the feed section 7 is connected to a recycling component. The specific structure is as follows:

[0048] As shown in the attached diagram of the instruction manual. Figure 1 As shown, the recycling component is used to receive the steam 42 overflowing from the overflow port 8. The recycling component includes a heat exchanger 31, a shell-and-tube heat exchanger 32 connected to the heat exchanger 31, and a recovery tank 33 connected to the shell-and-tube heat exchanger 32. After the steam 42 enters the interior of the heat exchanger 31 from the overflow port 8, it becomes condensate, thus creating a negative pressure. Since the interior of the heat exchange evaporator 3 is in a relatively sealed state, the temperature change of the condensate causes the interior of the heat exchange evaporator 3 to be in a negative pressure state. At the same time, the negative pressure state inside the heat exchange evaporator 3 will further affect the downward flow speed of the alkali solution, thereby further slowing down the downward flow speed of the alkali solution, making the alkali solution stay in the heat exchange tube 13 for a longer time, and making the heat exchange tube 13 heat the alkali solution for a longer time, thus improving the evaporation efficiency of the heat exchange evaporator 3.

[0049] However, simply condensing the overflowing steam 42 through the heat exchanger 31 can only reuse a portion of the water. This is because long-term use will cause the temperature of the heat exchanger 31 to become too high, and the water vapor will be in an exothermic state after condensation. Therefore, the heat exchanger 31 will generate secondary steam 42, which needs to be recovered through the shell-and-tube heat exchanger 32. The shell-and-tube heat exchanger 32 has the same structure as the heat exchange section 6 of the heat exchange evaporation device 3, but the shell-and-tube heat exchanger 32 is always filled with compressed air. After the water vapor enters the shell and tube, it is cooled by the compressed air and forms water, which then enters the recovery tank 33 to recover and reuse the water evaporated in the production line.

[0050] The two problems affecting the heat exchange efficiency of the heat exchange evaporator 3 described in the background art are: 1. scale inside the heat exchange tube 13, and 2. soot accumulation in the flue gas inside the heat exchange section 6. These problems are solved by the descaling section.

[0051] As shown in the attached diagram of the instruction manual. Figure 9 — Figure 11 As shown, the descaling unit includes a negative pressure adsorption component and multiple descaling components 15 connected to the negative pressure adsorption component. Multiple descaling components 15 are vertically arranged on the outer wall of the heat exchange tube 13. Each descaling component 15 has multiple flow channel cavities 44. Each descaling component 15 includes a housing 34, a connection port 35 provided on the housing 34, and multiple suction ports 36 provided on the housing 34. The suction ports 36 have gaps.

[0052] The negative pressure adsorption component is a vacuum pump. The vacuum pump is connected to the connection port 35 of the descaling component 15 through a pipeline. Since there are many descaling components 15, an adapter is needed to connect multiple pipelines together so that the vacuum pump generates negative pressure airflow that flows through the suction port 36 of each descaling component 15, and the generated negative pressure airflow flows through each suction port 36 on the housing 34.

[0053] Regarding the placement of the descaling component 15, after flue gas is introduced into the heat exchange section 6, the flow direction of the flue gas will be controlled by the baffle plate 14. Therefore, most of the dust accumulates on the upper and lower surfaces of the baffle plate 14 and on the outer wall of the heat exchange tube 13. Therefore, when setting up the descaling component 15, it is mirrored with the baffle plate 14 as the symmetrical plane, so that the dust in the heat exchange section 6 can be sucked away as soon as possible by negative pressure.

[0054] Due to the hardness of water in alkaline solutions, scale will form on the inner wall of heat exchange tube 13. If it is not removed for a long time, it will affect the heat exchange effect. Therefore, it is also necessary to remove the scale. Since the internal space of heat exchange section 6 and heat exchange tube 13 is limited and closed, and many components in heat exchange section 6 are corroded by chemical reagents, many cleaning methods are limited. Only mechanical vibration descaling can be used. This is combined with the removal of soot. Using Bernoulli's principle, the faster the flow rate, the lower the pressure. So when air flows through the narrow flow channel cavity 44 at high speed, the negative pressure airflow is compressed. At the same time, the negative pressure airflow will continuously rub against the intake port 36 and the wall surface of the flow channel cavity 44 to generate vibration, so that while drawing in soot, it resonates with the heat exchange tube 13. As the flow rate of the negative pressure airflow increases, the vibration frequency and vibration amplitude will also increase. Another important factor for removing scale using the above method is that the heat exchange tube 13 has multiple semi-circular grooves 17 arranged in an array. These semi-circular grooves make the inner wall of the heat exchange tube 13 a discontinuous smooth surface. This not only obstructs the flow of alkaline solution but also breaks down the intact surface of scale when it adheres to the inner wall of the heat exchange tube 13, reducing the degree of scale adhesion. At the same time, when the descaling component 15 vibrates, the stress generated by the vibration is transmitted from multiple surfaces to the inner wall of the heat exchange tube 13, making it easier to break down the bonding layer of scale and thus making it easier to peel off the scale from the inner wall of the heat exchange tube 13.

[0055] Since the descaling component 15 is installed on the outer wall of the heat exchange tube 13, in order to reduce the impact of the descaling component 15 on the heat exchange efficiency of the heat exchange tube 13, the shell 34 of the corresponding descaling component 15 is made of aluminum. Aluminum has better thermal conductivity than iron and is lightweight.

[0056] For other components, the outer wall of the feed section 7 is provided with a manhole, which is used for manual entry into the device to replace components. The manhole is sealed on the outside.

[0057] S1, the low-concentration alkaline solution is initially evaporated by the triple-effect evaporator 40. After the alkaline solution is initially evaporated by the triple-effect evaporator 40, it is pumped into the preheating pot 2 by the pump body, and then pumped into the heat exchange evaporation device 3 by the preheating pot 2.

[0058] S2, the heat exchange evaporation device 3 performs secondary evaporation on the alkaline solution after primary evaporation. The alkaline solution is diverted from the feed pipe according to the flow rate and enters the heat exchange evaporation device 3. Then it flows into the upper fixed plate 18. When the liquid level in the upper fixed plate 18 is higher than the distance of the heat exchange tube 13 from the upper fixed plate 18, the alkaline solution slowly flows into the heat exchange tube 13.

[0059] S3, at the same time, the burner 9 heats the bottom of the heating section 5. The flue gas generated by the burner 9 enters the heat exchange section 6 through the air inlet 11. The heat of the flue gas heats the alkaline solution in the heat exchange tube 13, causing the water in the alkaline solution inside the heat exchange tube 13 to evaporate. Then, the alkaline solution collected at the bottom of the heat exchange tube 13 enters the heating section 5 through the discharge pipe 10 and is pumped into the receiving tank 41 through the discharge pipe 10. The burner 9 heats and concentrates the bottom of the receiving tank 41 until the alkaline solution is anhydrous.

[0060] S4, the water in the alkaline solution inside the heat exchange tube 13 evaporates and overflows from the overflow port 8 into the heat exchange element 31 of the recycling component, becoming condensate. At the same time, the heat exchange evaporation device 3 is under negative pressure. The shell and tube heat exchanger 32 performs secondary recovery of the steam 42 entering the heat exchange element 31 and enters the recovery tank 33.

[0061] S5, when it is necessary to descale or remove soot from the heat exchange section 6, the negative pressure adsorption component is turned on. The negative pressure airflow generated by the adsorption component draws the soot into the flow channel. At the same time, the air flows at high speed through the narrow flow channel cavity 44. The negative pressure airflow will generate vibration by friction on the wall of the flow channel cavity 44, so that it resonates with the heat exchange tube 13 while drawing in the soot, drawing the soot into the negative pressure adsorption component. At the same time, the scale on the inner wall of the heat exchange tube 13 is peeled off by vibration.

[0062] In summary, this device can concentrate the diluted alkaline solution in the indigo production line. It concentrates the alkaline solution step by step by using different heat exchange media. The heat exchange evaporation device 3 uses the flue gas generated during combustion of the burner 9 to further concentrate the alkaline solution. By utilizing the membrane evaporation principle, the heat exchange evaporation device 3 achieves higher evaporation efficiency when concentrating the alkaline solution. Furthermore, the vapor 42 evaporated from the solution can be recovered and reused throughout the concentration process.

Claims

1. An alkaline condensation assembly for an indigo production line, characterized in that: It includes a triple-effect evaporator (1), a preheating pot (2) connected to the triple-effect evaporator (1), and a heat exchange evaporator (3) connected to the preheating pot (2) via a pipeline; The bottom of the heat exchange evaporation device (3) is located inside the furnace body (4). The heat exchange evaporation device (3) includes a heating part (5) at the bottom of the heat exchange evaporation device (3), a heat exchange part (6) in the middle of the heat exchange evaporation device (3), and a feeding part (7) at the top of the heat exchange evaporation device (3). The top of the feeding part (7) is provided with an overflow port (8). The feeding section (7) is connected to the preheating pot (2) through a pipeline. The bottom of the heating section (5) is equipped with a burner (9) for heating. The bottom of the heating section (5) is equipped with a discharge pipeline (10). The heat exchange section (6) includes an air inlet (11) at the bottom of the heat exchange section (6) and an air outlet (12) at the top of the heat exchange section (6). The heat exchange section (6) is equipped with multiple heat exchange tubes (13). Multiple semi-circular grooves (17) are arranged in an array on the heat exchange tubes (13). The bottom of the heat exchange tube (13) is connected to the heating section (5), and the top of the heat exchange tube (13) is connected to the feed section (7). Alkali solution flows inside the heat exchange tube (13). Multiple baffles (14) are staggered inside the heat exchange section (6). A descaling section is provided on the outer wall of the heat exchange tube (13), and the descaling section is mirrored with the baffles (14) as the symmetrical plane. The descaling section includes a negative pressure adsorption component and multiple descaling components (15) connected to the negative pressure adsorption component. The descaling components (15) are provided with multiple flow channel cavities (44). The negative pressure airflow generated by the negative pressure adsorption component draws the soot into the flow channel cavity (44). At the same time, the air flows through the narrow flow channel cavity (44) at high speed. The negative pressure airflow will generate vibration by friction at the intake port (36) and the wall surface of the flow channel cavity (44), causing the descaling components (15) at different positions to resonate on the heat exchange tube (13). The multiple semi-circular grooves (17) on the heat exchange tube (13) destroy the complete surface of the scale, thereby destroying the bonding layer formed by the scale on the inner wall of the heat exchange tube (13), thus descaling multiple positions of the heat exchange tube (13).

2. The alkaline condensation assembly for an indigo production line according to claim 1, characterized in that: The heat exchange section (6) is also provided with a fixing member for fixing multiple heat exchange tubes (13), the fixing member including a fixing plate (18) and multiple spacer tubes (19). The fixing plate (18) is divided into upper and lower parts. The fixing plate (18) is used for both ends of the multiple heat exchange tubes (13), and both ends of the heat exchange tubes (13) are exposed on the fixing plate (18). The multiple baffles (14) are arranged on the fixed distance tube (19).

3. The alkaline condensation assembly for an indigo production line according to claim 2, characterized in that: The feeding section (7) is provided with a first feeding pipe (21) and a second feeding pipe (22) distributed vertically. The inlet of the second feeding pipe (22) is provided with a guide pipe (23). A flow divider assembly is provided below the inlet of the first feed pipe (21) located at the top. The flow divider assembly includes a flow divider groove (24), a first grid plate (25) and a second grid plate (26) located below the flow divider groove (24). The diversion channel (24) includes a water storage tank (27) and multiple drain outlets (28). The bottom of the water storage tank (27) is provided with a drain hole (29). The first grid plate (25) and the second grid plate (26) are each provided with multiple water passage holes (30). The density of the water passage holes (30) of the second grid plate (26) is greater than the density of the water passage holes (30) of the first grid plate (25). The second grid plate (26) is connected to the guide pipe (23).

4. The alkaline condensation assembly for an indigo production line according to any one of claims 1-3, characterized in that: The overflow port (8) of the feed section (7) is connected to a recycling component. The recycling component is used to receive the steam (42) overflowing from the overflow port (8). After the steam (42) is turned into condensate, the heat exchange evaporation device (3) is in a negative pressure state. The recycling component includes a heat exchange element (31), a shell-and-tube heat exchanger (32) connected to the heat exchange element (31), and a recovery tank (33) connected to the shell-and-tube heat exchanger (32).

5. The alkaline condensation assembly for an indigo production line according to claim 4, characterized in that: The descaling component (15) includes a housing (34), a connection port (35) disposed on the housing (34), and a plurality of suction ports (36) disposed on the housing (34), wherein the suction ports (36) have gaps.

6. The alkaline condensation assembly for an indigo production line according to claim 1, characterized in that: The furnace body (4) is equipped with a receiving tank (41) inside. The receiving tank (41) is connected to the discharge pipe (10). A burner (9) is provided at the bottom of the receiving tank (41) for heating.

7. The alkaline condensation assembly for an indigo production line according to claim 1, characterized in that: The triple-effect evaporator (1) includes three evaporators, each including a shell-and-tube heat exchanger (32) and an evaporation tower (37). Steam (42) is introduced into the heat exchanger of the first-effect evaporator (38) to heat the alkali solution in the evaporation tower (37). The steam (42) generated after the first evaporation and the external steam (42) are introduced into the heat exchanger of the second-effect evaporator (39). The alkali solution after the first evaporation is pumped into the evaporation tower (37) of the second-effect evaporator (39). The steam (42) generated after the second evaporation and the external steam (42) are introduced into the heat exchanger of the triple-effect evaporator (40). The alkali solution after the second evaporation is pumped into the evaporation tower (37) of the triple-effect evaporator (40). The alkali solution in the triple-effect evaporation tower (37) is pumped into the preheating pot (2) after evaporation.

8. The method of using the alkaline condensation assembly for an indigo production line according to any one of claims 1-7, characterized in that: S1, the unconcentrated alkali solution is initially evaporated by the triple-effect evaporator (40). After the alkali solution is initially evaporated by the triple-effect evaporator (40), it is pumped into the preheating pot (2) by the pump body, and then pumped into the heat exchange evaporation device (3) by the preheating pot (2). S2, the heat exchange evaporation device (3) performs secondary evaporation on the alkaline solution after primary evaporation. The alkaline solution is diverted from the feed pipe according to the flow rate and enters the heat exchange evaporation device (3), and then flows into the upper fixed plate (18). When the liquid level of the upper fixed plate (18) is higher than the distance of the heat exchange tube (13) from the upper fixed plate (18), the alkaline solution slowly flows into the inner wall of the heat exchange tube (13). S3, at the same time, the burner (9) heats the bottom of the heating section (5), and the flue gas generated by the burner (9) enters the heat exchange section (6) through the air inlet (11). The heat of the flue gas heats the alkali solution in the heat exchange tube (13), causing the water in the alkali solution inside the heat exchange tube (13) to evaporate. Then, the alkali solution collected at the bottom of the heat exchange tube (13) is pumped into the receiving tank (41) through the discharge pipe (10). The burner (9) heats and concentrates the bottom of the receiving tank (41) until the alkali solution is anhydrous. S4, the water in the alkaline solution inside the heat exchange tube (13) evaporates and overflows from the overflow port (8) into the heat exchange element (31) of the recycling component, becoming condensate. At the same time, the heat exchange evaporation device (3) is under negative pressure. The shell and tube heat exchanger (32) performs secondary recovery of the steam (42) entering the heat exchange element (31) and enters the recovery tank (33). S5. When it is necessary to descale or remove soot from the heat exchange section (6), turn on the negative pressure adsorption component. The negative pressure airflow generated by the adsorption component will draw the soot into the flow channel. At the same time, the air flows at high speed through the narrow flow channel cavity (44). The negative pressure airflow will rub against the wall of the flow channel cavity (44) to generate vibration, so that it resonates with the heat exchange tube (13) while drawing in the soot, drawing the soot into the negative pressure adsorption component. At the same time, the scale on the inner wall of the heat exchange tube (13) is peeled off by vibration.

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