Liquid caustic soda heat exchange system for reducing generation of acid-making wastewater

Abstract

The utility model belongs to the technical field of wastewater treatment in sintering production, and particularly relates to a liquid caustic soda heat exchange system for reducing acid-making wastewater. The liquid caustic soda heat exchange system is mainly improved on the basis of an existing liquid caustic soda supply system, the first disc type heat exchanger and the second disc type heat exchanger are arranged in the liquid caustic soda ground tank and the liquid caustic soda storage tank respectively, steam of a steam pipe network is introduced into the disc type heat exchangers to conduct heat exchange heating with stored liquid caustic soda, and the liquid caustic soda is prevented from being crystallized at the low temperature. In addition, the liquid caustic soda heat exchange system is provided with a condensation overflow valve, a manual regulating valve, a temperature transmitter, a liquid level transmitter, a pressure gauge, a flow meter and the like, so that the temperature and the liquid level of the liquid caustic soda and the pressure of the system are monitored and controlled in real time. Therefore, according to the improvement scheme provided by the utility model, the continuous and stable operation of the liquid caustic soda supply system can be effectively guaranteed, the discharge amount and the discharge frequency of the wastewater can be reduced, and the operation efficiency and the safety of the system are also improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater treatment in sintering production, and specifically relates to a liquid alkali heat exchange system for reducing the generation of acid-making wastewater. Background Art

[0002] During the sintering production process, flue gas usually needs to be adsorbed and treated by the desulfurization and denitrification system before it can be discharged. The acid production system attached to the desulfurization and denitrification system will inevitably produce acidic wastewater. In order to meet national emission standards, these acidic wastewaters need to be discharged into the waste acid pool and neutralized with liquid alkali. The neutralized wastewater is then transported to the downstream sewage treatment plant through a pumping system for deep treatment.

[0003] However, in the actual production process, the downstream sewage treatment plant may be temporarily shut down due to maintenance or other reasons, resulting in nowhere to discharge wastewater, which will seriously affect the continuity of sintering production. To solve this problem, our company is considering increasing the concentration of purchased liquid alkali from the original 25% to 42%, in order to ensure the stability of sintering production by reducing the amount of wastewater generated and the frequency of discharge. According to the chemical reaction equation H2SO4 + 2NaOH = Na2SO4 + 2H2O, it can be calculated that when treating the same volume of acidic wastewater, using 42% liquid alkali can significantly reduce the amount of liquid alkali required compared to 25% liquid alkali. For example, to treat 1014m³ of acidic sewage, if 42% liquid alkali is used, only 196.9 tons are needed, while using 25% liquid alkali requires 330.8 tons. This not only helps to reduce the cost of wastewater treatment, but also reduces the frequency of wastewater discharge to a certain extent, thereby ensuring that sintering production can remain continuous and stable in the face of emergencies such as shutdown of downstream sewage treatment plants.

[0004] Due to the increase in the concentration of liquid caustic soda, the liquid caustic soda will crystallize at 12°C, which brings new challenges to the original liquid caustic soda supply system and affects the treatment efficiency of acidic wastewater. If this problem cannot be effectively solved, the original liquid caustic soda supply system may also be curbed due to the temperature drop in winter, resulting in the sintering production being curbed.

[0005] In summary, how to ensure the stable operation of the caustic soda supply system while increasing the concentration of caustic soda has become a technical problem that needs to be solved urgently in this project transformation. This is not only related to the continuity and stability of sintering production, but also directly affects the environmental protection standards and economic benefits of the enterprise. Utility Model Content

[0006] In response to the challenges faced by enterprises in wastewater discharge during emergencies such as the shutdown of downstream sewage treatment plants, we increased the concentration of the externally purchased liquid caustic soda from the original 25% to 42%. By reducing the amount of wastewater generated and the discharge frequency, we thereby reduced the impact of wastewater discharge on sintering production. At the same time, heat pipe heat exchangers need to be added to the liquid caustic soda storage tank and the ground tank, and the steam from the steam pipe network is used to keep the entire tank evenly heated, preventing the liquid caustic soda from crystallizing and ensuring the stable operation of the liquid caustic soda supply system. Based on the implementation of the above transformation project, the present utility model provides a liquid caustic soda heat exchange system for reducing the generation of acid-making wastewater.

[0007] To achieve the above object, the present utility model adopts the following technical solutions: A liquid caustic soda heat exchange system for reducing the generation of acid-making wastewater, comprising a liquid caustic soda ground tank and a liquid caustic soda storage tank, and the two are connected through a first pipeline. A lift pump is provided on the first pipeline, and the lift pump pumps the liquid caustic soda from the liquid caustic soda ground tank to the liquid caustic soda storage tank. A truck unloading pump is provided at the inlet of the liquid caustic soda ground tank through a second pipeline, and the truck unloading pump is used to pump the externally purchased liquid caustic soda from the tank truck into the liquid caustic soda ground tank, thereby forming a liquid caustic soda supply system. A first plate heat exchanger is provided in the liquid caustic soda ground tank, and a second plate heat exchanger is provided in the liquid caustic soda storage tank. The outlet of the first plate heat exchanger is connected to the inlet of the second plate heat exchanger through a third pipeline. The inlet of the first plate heat exchanger is connected to the steam supply main pipe of the steam pipe network through a fourth pipeline. An electric control valve is provided on the fourth pipeline. The outlet of the second plate heat exchanger is connected to the inlet of a recovery tank through a fifth pipeline. The outlet of the recovery tank is connected to a circulation pipeline through a seventh pipeline and is externally connected to the circulation water tank of the acid-making system or the steam supply main pipe of the heating system. A circulation pump is provided on the seventh pipeline, and the circulation pump pumps the steam heat-exchanged in the recovery tank to the acid-making system or the heating system for repeated use, thereby forming a liquid caustic soda heat exchange circulation system.

[0008] As a further supplementary description of the above technical solution, a condensate overflow valve is provided on the fifth pipeline, and manual shut-off valves are respectively provided on the fifth pipeline on both sides of the condensate overflow valve. The condensate overflow valve is connected to the circulation pipeline through a sixth pipeline. The condensate overflow valve automatically discharges the condensate generated in the fifth pipeline to the circulation pipeline through the sixth pipeline for recycling, thereby ensuring the safety of the steam pipeline.

[0009] As a further supplementary description of the above technical solution, a manual regulating valve is provided on the fifth pipeline through a bypass pipeline. The manual regulating valve manually adjusts its opening degree according to the amount of heat-exchanged steam used to ensure the steam flow rate in the fifth pipeline and reduce the generation of condensate water.

[0010] As a further supplementary description of the above technical solution, a first temperature transmitter and a second temperature transmitter are respectively arranged on the liquid caustic soda ground tank and the liquid caustic soda storage tank, and the signal output ends of both are connected to the DCS control system through signal lines and form a temperature interlock control with the electric control valve, that is, when the temperature of any detection point of the first temperature transmitter and the second temperature transmitter is lower than 18 °C, the electric control valve is automatically opened.

[0011] As a further supplementary description of the above technical solution, a first liquid level transmitter and a second liquid level transmitter are respectively arranged on the liquid caustic soda ground tank and the liquid caustic soda storage tank. The first liquid level transmitter forms a liquid level interlock control with the unloading pump through the DCS control system, and the second liquid level transmitter forms a liquid level interlock control with the lifting pump through the DCS control system, so as to ensure the normal operation of the liquid caustic soda supply system.

[0012] As a further supplementary description of the above technical solution, a check valve is arranged at the outlet of the lifting pump, and the check valve prevents the liquid caustic soda from flowing back to damage the lifting pump equipment when the liquid level interlock fails.

[0013] As a further supplementary description of the above technical solution, a first pressure gauge and a flow meter are respectively arranged on the fourth pipeline, and a second pressure gauge is arranged on the seventh pipeline. The first pressure gauge, the flow meter and the second pressure gauge are jointly used to ensure the stable and safe operation of the liquid caustic soda heat exchange circulation system.

[0014] The remarkable technical effects of the present utility model are mainly reflected in the following aspects through the transformation and optimization of the liquid caustic soda supply system:

[0015] 1. By adding a plate heat exchanger inside the liquid caustic soda ground tank and the liquid caustic soda storage tank and using the steam of the steam pipe network for heat exchange and heating, the present utility model effectively prevents the low-temperature crystallization of liquid caustic soda, thus ensuring the continuity and stability of sintering production. The transformed system can recover and reuse the steam after heat exchange, significantly reducing the discharge amount and discharge frequency of wastewater, which helps the enterprise to save energy, reduce emissions and recycle resources.

[0016] 2. By adding a condensate overflow valve and a manual regulating valve, the present utility model solves the problem of condensate water generated during the steam heat exchange process, ensuring the safety of the steam pipeline and the stable operation of the heat exchange circulation system. At the same time, the design of the check valve effectively avoids the damage of the liquid caustic soda flowing back to the lifting pump equipment when the liquid level interlock fails, improving the safety of the system.

[0017] 3. The intelligent control system for liquid caustic soda temperature and liquid level designed based on the DCS control system of the present utility model can automatically adjust the steam flow rate and liquid caustic soda transportation through real-time detection and interlock control by temperature transmitters and liquid level transmitters, ensuring that the liquid caustic soda is within an appropriate temperature and liquid level range. It realizes the automatic and intelligent management of the liquid caustic soda supply system, improving the operation efficiency and safety of the system.

[0018] 4. The pressure gauges and flow meters set on the key pipelines of the present utility model can monitor the pressure and steam flow rate of the system in real time, providing an important basis for system control and fault troubleshooting. At the same time, it significantly improves the operation efficiency, safety, stability and environmental protection performance of the liquid caustic soda supply system, providing strong support for the sustainable development of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of the liquid caustic soda heat exchange system in the present utility model.

[0020] In the figure: the liquid caustic soda ground tank is 1, the liquid caustic soda storage tank is 2, the first pipeline is 3, the lift pump is 4, the second pipeline is 5, the unloading pump is 6, the first plate heat exchanger is 7, the second plate heat exchanger is 8, the third pipeline is 9, the fourth pipeline is 10, the electric control valve is 11, the fifth pipeline is 12, the condensate overflow valve is 13, the sixth pipeline is 14, the circulation pipeline is 15, the recovery tank is 16, the seventh pipeline is 17, the circulation pump is 18, the bypass pipeline is 19, the manual control valve is 20, the manual shut-off valve is 21, the first temperature transmitter is 22, the second temperature transmitter is 23, the first liquid level transmitter is 24, the second liquid level transmitter is 25, the check valve is 26, the first pressure gauge is 27, the flow meter is 28, and the second pressure gauge is 29. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to further elaborate on the technical solution of the present utility model, the following will further illustrate the present utility model through embodiments in combination with the attached Figure 1 , according to the implementation process of on-site transformation.

[0022] As shown in the attached Figure 1 , the existing liquid caustic soda supply system includes a liquid caustic soda ground tank 1 and a liquid caustic soda storage tank 2, and the two are connected through a first pipeline 3. A lift pump 4 is provided on the first pipeline 3, and the lift pump 4 pumps the liquid caustic soda from the liquid caustic soda ground tank 1 to the liquid caustic soda storage tank 2. An unloading pump 6 is provided through a second pipeline 5 at the inlet of the liquid caustic soda ground tank 1, and the unloading pump 6 pumps the externally purchased liquid caustic soda from the tank truck into the liquid caustic soda ground tank 1 for subsequent use in neutralizing waste acid in the waste acid tank. Embodiment 1

[0023] As shown in the attached Figure 1As shown in the figure, a liquid caustic soda heat exchange system for reducing the generation of acid-making wastewater is transformed based on the existing liquid caustic soda supply system as follows: A first plate heat exchanger 7 is provided in the liquid caustic soda underground tank 1, and a second plate heat exchanger 8 is provided in the liquid caustic soda storage tank 2. The outlet of the first plate heat exchanger 7 is connected to the inlet of the second plate heat exchanger 8 through a third pipeline 9. The inlet of the first plate heat exchanger 7 is connected to the steam supply main pipe of the steam network through a fourth pipeline 10. An electric control valve 11 is provided on the fourth pipeline 10. The outlet of the second plate heat exchanger 8 is connected to the inlet of the recovery tank 16 through a fifth pipeline 12. The outlet of the recovery tank 16 is connected to the circulation pipeline 15 through a seventh pipeline 17 and is externally connected to the circulation water tank of the acid-making system or the steam supply main pipe of the heating system. A circulation pump 18 is provided on the seventh pipeline 17. The circulation pump 18 pumps the heat-exchanged steam in the recovery tank 16 to the acid-making system or the heating system for repeated use, thereby forming a liquid caustic soda heat exchange circulation system.

[0024] In this embodiment, we transformed the liquid caustic soda underground tank and the liquid caustic soda storage tank, that is, added plate heat exchangers inside both of them. By introducing the steam of the steam network into the plate heat exchangers to exchange heat and heat the stored liquid caustic soda, the crystallization phenomenon of liquid caustic soda at low temperature is prevented. The transformed liquid caustic soda supply system can not only ensure the normal operation of the original system, but also reduce the discharge amount and discharge frequency of wastewater, further ensuring the continuity and stability of sintering production. Embodiment Two

[0025] During the actual operation of the above embodiment, the steam heat exchange process is easily affected by factors such as cold or flow rate, and condensate water is generated in the pipeline, which poses a potential risk to the stable and safe operation of the entire liquid caustic soda heat exchange circulation system. In response to this, as shown in the appendix Figure 1 As shown in the figure, we take the following two improvement measures: First, a condensate overflow valve 13 is provided on the fifth pipeline 12. Manual shut-off valves 21 are respectively provided on the fifth pipeline 12 on both sides of the condensate overflow valve 13. The condensate overflow valve 13 is connected to the circulation pipeline 15 through a sixth pipeline 14. The condensate overflow valve 13 automatically discharges the condensate water generated in the fifth pipeline 12 to the circulation pipeline 15 through the sixth pipeline 14 for recycling, thereby ensuring the safety of the steam pipeline. Second, a manual regulating valve 20 is provided on the fifth pipeline 12 through a bypass pipeline 19. The manual regulating valve 20 manually adjusts its opening degree according to the usage amount of the heat exchange steam to ensure the steam flow rate in the fifth pipeline 12 and further reduce the generation of condensate water. Embodiment Three

[0026] To ensure the stable operation of the liquid caustic soda supply system, as shown in the appendix Figure 1As shown, we designed an intelligent control system for the temperature and liquid level of liquid caustic soda based on the existing DCS control system, thereby realizing the automated and intelligent management of the liquid caustic soda supply system and further improving the operation efficiency and safety of the system.

[0027] I. Temperature Detection and Control

[0028] We installed a first temperature transmitter 22 and a second temperature transmitter 23 on the liquid caustic soda ground tank 1 and the liquid caustic soda storage tank 2 respectively. These two temperature transmitters can detect the temperature of the liquid caustic soda in their respective tanks in real time and transmit the detected temperature signals to the DCS control system through signal lines.

[0029] Since the DCS control system has built-in temperature interlock control logic. When the temperature detected by the first temperature transmitter 22 or the second temperature transmitter 23 is lower than the set threshold (18°C in this example), the system will automatically trigger the opening operation of the electric control valve 11 to adjust the steam flow rate, thereby increasing the temperature of the liquid caustic soda to ensure that the liquid caustic soda is within an appropriate range and prevent it from crystallizing.

[0030] II. Liquid Level Detection and Control

[0031] We also installed a first liquid level transmitter 24 and a second liquid level transmitter 25 on the liquid caustic soda ground tank 1 and the liquid caustic soda storage tank 2 respectively. These two liquid level transmitters can detect the liquid level of the liquid caustic soda in their respective tanks in real time and transmit the detected liquid level signals to the DCS control system.

[0032] The DCS control system also has built-in liquid level interlock control logic. For the liquid caustic soda ground tank 1, when the liquid level detected by the first liquid level transmitter 24 reaches a certain set capacity, the system will automatically stop the unloading pump 6 to complete the unloading of the liquid caustic soda. For the liquid caustic soda storage tank 2, when the liquid level detected by the second liquid level transmitter 25 is lower than another set value, the system will automatically start the lifting pump 4 to transport the liquid caustic soda from the ground tank 1 to the storage tank 2 to ensure the continuous operation of the liquid caustic soda supply system. Example 4

[0033] To enhance the monitoring and control capabilities of the liquid caustic soda heat exchange circulation system, we especially set pressure gauges and flow meters on the key pipelines. As shown in the appendix Figure 1 Specifically, we installed a first pressure gauge 27 and a flow meter 28 on the fourth pipeline 10. The first pressure gauge 27 is used to monitor the pressure in the fourth pipeline 10 in real time to ensure that it fluctuates within the set safe range and avoid system failures or safety hazards caused by too high or too low pressure. At the same time, the flow meter 28 is used to measure and record the steam flow rate in the fourth pipeline 10, which is crucial for controlling the steam flow velocity and ensuring the heat exchange efficiency.

[0034] In addition, we also installed a second pressure gauge 29 on the seventh pipeline 17. The function of the second pressure gauge 29 is similar to that of the first pressure gauge 27, and it is also used to monitor the pressure inside the pipeline in real time, but it targets the specific area of the seventh pipeline 17. Such a setting can more comprehensively cover the entire liquid caustic soda heat exchange circulation system, improving the stability and safety of the system. At the same time, a check valve 26 is installed at the outlet of the lift pump 4 to prevent the liquid caustic soda from flowing back and damaging equipment such as the lift pump when the liquid level interlock fails.

[0035] In summary, through the coordinated operation of the first pressure gauge 27, the flow meter 28, and the second pressure gauge 29, it is possible to achieve comprehensive monitoring and control of the liquid caustic soda heat exchange circulation system, ensuring the stable and safe operation of the system.

[0036] The above shows and describes the main features and advantages of the present invention. For those skilled in the art, it is obvious that the specific implementation of the present invention is not limited to the details of the above exemplary embodiments. Moreover, without departing from the spirit or basic features of the present invention, the creative ideas and design concepts of the present invention can be implemented in other specific forms, and should be equally within the protection scope disclosed in the technical solution of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0037] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. The narrative way of this specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater, comprising a liquid alkali tank (1) and a liquid alkali storage tank (2), the two being connected via a first pipeline (3), a lifting pump (4) being arranged on the first pipeline (3), the lifting pump (4) pumping the liquid alkali from the liquid alkali tank (1) to the liquid alkali storage tank (2), a truck unloading pump (6) being arranged at the inlet of the liquid alkali tank (1) via a second pipeline (5), the truck unloading pump (6) being used to pump purchased liquid alkali from a tank truck into the liquid alkali tank (1), thereby forming a liquid alkali supply system, characterized in that: A first disc heat exchanger (7) is arranged in the liquid alkali tank (1), and a second disc heat exchanger (8) is arranged in the liquid alkali storage tank (2). The outlet of the first disc heat exchanger (7) and the inlet of the second disc heat exchanger (8) are connected via a third pipeline (9). The inlet of the first disc heat exchanger (7) is connected to a steam supply main pipe of a steam network via a fourth pipeline (10). An electric control valve (11) is arranged on the fourth pipeline (10). The second disc heat exchanger (8) is connected to a steam supply main pipe of a steam network via a third pipeline (9). ) is connected to the inlet of a recovery tank (16) via a fifth pipeline (12); the outlet of the recovery tank (16) is connected to the circulation pipeline (15) via a seventh pipeline (17) and is externally connected to a circulation water tank of an acid-making system or a steam supply main pipe of a heating system; a circulation pump (18) is provided on the seventh pipeline (17); the circulation pump (18) pumps the steam after heat exchange in the recovery tank (16) to the acid-making system or the heating system for reuse, thereby forming a liquid alkali heat exchange circulation system.

2. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater according to claim 1, characterized in that: A condensation overflow valve (13) is provided on the fifth pipeline (12), and manual shut-off valves (21) are provided on the fifth pipeline (12) located on both sides of the condensation overflow valve (13), respectively. The condensation overflow valve (13) is connected to the circulation pipeline (15) via a sixth pipeline (14), and the condensation overflow valve (13) automatically discharges condensed water generated in the fifth pipeline (12) into the circulation pipeline (15) via the sixth pipeline (14) for recycling, thereby ensuring the safety of the steam pipeline.

3. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater according to claim 2, characterized in that: A manual regulating valve (20) is provided on the fifth pipeline (12) via a bypass pipeline (19); the opening and closing degree of the manual regulating valve (20) is manually adjusted according to the change in the amount of heat exchange steam used, thereby ensuring the flow rate of steam in the fifth pipeline (12) and reducing the generation of condensed water.

4. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater according to claim 3, characterized in that: A first temperature transmitter (22) and a second temperature transmitter (23) are respectively provided on the liquid alkali tank (1) and the liquid alkali storage tank (2), and signal output ends of the two are connected to a DCS control system via a signal line, and form a temperature interlocking control with the electric control valve (11), that is, when the temperature of any detection point of the first temperature transmitter (22) and the second temperature transmitter (23) is lower than 18°C, the electric control valve (11) is automatically opened.

5. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater according to claim 3, characterized in that: A first liquid level transmitter (24) and a second liquid level transmitter (25) are respectively arranged on the liquid alkali ground tank (1) and the liquid alkali storage tank (2); the first liquid level transmitter (24) forms a liquid level interlocking control with the unloading pump (6) through a DCS control system, and the second liquid level transmitter (25) forms a liquid level interlocking control with the lifting pump (4) through a DCS control system, thereby ensuring the normal operation of the liquid alkali supply system.

6. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater according to claim 5, characterized in that: A check valve (26) is provided at the outlet of the lift pump (4), and the check valve (26) prevents the backflow of liquid alkali and damage to the lift pump (4) equipment when a liquid level interlocking failure occurs.

7. A liquid alkali heat exchange system for reducing the generation of acid-making wastewater according to any one of claims 1 to 6, characterized in that: A first pressure gauge (27) and a flow meter (28) are respectively provided on the fourth pipeline (10), and a second pressure gauge (29) is provided on the seventh pipeline (17); the first pressure gauge (27), the flow meter (28) and the second pressure gauge (29) are used together to ensure the smooth and safe operation of the liquid alkali heat exchange circulation system.

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