Blending combustion system for preparing coal water slurry from caprolactam waste liquid
By designing a caprolactam waste liquid to water-coal slurry co-firing system, the problems of high cost and pollution in traditional treatment processes have been solved, realizing the resource utilization of waste liquid and an environmentally friendly treatment method.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2026-03-06
AI Technical Summary
Traditional caprolactam wastewater treatment processes consume a large amount of energy and manpower, generate pollutants, put significant pressure on environmental governance, and rely on multiple auxiliary devices for operation.
A caprolactam waste liquid co-firing system for water production is designed. Through multiple storage tank components and a waste liquid concentration device, the system realizes the recycling treatment and pH adjustment of the waste liquid, and directly uses the waste liquid for co-firing of water production coal, reducing the dependence on concentration and alkali purification devices.
It significantly reduced the operating costs of the caprolactam unit, reduced pollutant emissions, realized the resource utilization of waste liquid, and reduced environmental pollution pressure.
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Figure CN223976059U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of chemical technology, and in particular to a caprolactam waste liquid-to-coal slurry co-firing system. Background Technology
[0002] Caprolactam, an important organic chemical raw material, is mainly used to produce polyamide chips, which are further processed into nylon fibers, engineering plastics, plastic films, and other products. In the caprolactam production process, the benzene extraction and ion exchange processes generate various waste liquids, including benzene extraction residue, ion exchange tower regeneration wastewater, and high-COD and ammonia nitrogen wastewater from the plant's drainage ditch.
[0003] The traditional caprolactam wastewater treatment process involves discharging the wastewater into a dilute wastewater storage tank, pressurizing it with a transfer pump, and then sending it to a wastewater concentration unit for triple-effect evaporation and concentration. The evaporated and condensed liquid is then sent to a wastewater treatment plant for further processing, while the concentrated liquid is sent to an alkali refining unit for incineration in the alkali furnace. This process relies on the coordinated operation of the wastewater concentration unit, the alkali refining unit, and the wastewater treatment unit. The operation consumes significant amounts of energy, including steam, electricity, and natural gas, and requires substantial labor costs, significantly increasing the overall operating cost of the caprolactam plant.
[0004] Furthermore, the waste liquid concentration and alkali refining units generate waste gas and wastewater during operation. The pollutants in the waste gas will pollute the atmospheric environment, and the harmful substances in the wastewater, if discharged directly without effective treatment, will pollute the soil, water bodies, and other ecological environments, increasing the pressure on environmental governance. Summary of the Invention
[0005] The purpose of this application is to provide a caprolactam waste liquid to coal-water slurry co-firing system, including a first storage tank assembly, a second storage tank assembly, a third storage tank assembly, and a waste liquid concentration device;
[0006] Each of the aforementioned tank assemblies includes a tank, a circulation return pipeline, a transfer pump, a neutralization pipeline, and a monitoring instrument. The tank has a first inlet, a second inlet, and an outlet. The outlet is connected to one end of the circulation return pipeline, and the other end of the circulation return pipeline is connected to the second inlet via the transfer pump. The outlet of the neutralization pipeline is connected to the inlet of the transfer pump for adjusting the pH of the waste liquid. The monitoring instrument is installed on the circulation return pipeline for online monitoring of the pH of the waste liquid.
[0007] In this configuration, the first inlet of the first storage tank assembly is connected to the waste liquid pipeline, the inlet of the waste liquid concentration device is connected to the downstream section of the circulation return pipeline of the first storage tank assembly, the first inlet of the second storage tank assembly is connected to the downstream section of the circulation return pipeline of the first storage tank assembly and the outlet of the waste liquid concentration device, respectively, and the first inlet of the third storage tank assembly is connected to the downstream section of the circulation return pipeline of the second storage tank assembly.
[0008] As an optional embodiment, the system includes two first storage tank assemblies, a first connecting pipeline is provided between the two first storage tank assemblies, and a first switching valve group is provided on the first connecting pipeline.
[0009] As an optional embodiment, the downstream sections of the circulation return pipelines of the two first storage tank assemblies are respectively connected to the inlet of the waste liquid concentration device and the first inlet of the second storage tank assembly via a second connecting pipeline, and a second switching valve group is provided on the second connecting pipeline.
[0010] As an optional embodiment, the outlet of the waste liquid concentration device is connected to the wastewater treatment device through a first heat exchanger.
[0011] As an optional embodiment, the system further includes a second heat exchanger located between the downstream section of the circulation return line of the second tank assembly and the first inlet of the tank of the third tank assembly.
[0012] As an optional embodiment, the pipeline between the inlet of the circulation return pipeline and the inlet of the delivery pump is the upstream section, the pipeline between the outlet of the delivery pump and the outlet of the circulation return pipeline is the downstream section, and one end of the neutralization pipeline is connected to the upstream section.
[0013] As an optional embodiment, the inlet of the monitor is connected to the downstream section, and the outlet of the monitor is connected to the upstream section.
[0014] As an optional embodiment, the material transported in the neutralization pipelines of the first and second storage tank assemblies is liquid alkali, and the material transported in the neutralization pipeline of the third storage tank assembly is liquid alkali or sulfuric acid.
[0015] As an optional embodiment, the downstream section of the circulation return pipeline of the third storage tank assembly is connected to a hydrogen production and ammonia synthesis unit to utilize the treated waste liquid to produce coal-water slurry.
[0016] As an optional embodiment, the concentrations of the dilute waste liquid stored in the two tanks of the first tank assembly are different.
[0017] The beneficial effects of the embodiments of this application are as follows:
[0018] The structure of this application is reasonably designed, and the caprolactam waste liquid can be directly used for co-firing of coal-water slurry, so that the waste liquid concentration unit and the alkali refining unit do not need to be operated, saving a lot of steam, electricity, natural gas and labor costs, and significantly reducing the operating cost of caprolactam unit.
[0019] This application effectively neutralizes sulfuric acid and sodium hydroxide in the waste liquid through multiple pH adjustments and temperature controls, reducing the corrosiveness of the waste liquid, ensuring no ammonia release of ammonium sulfate in the waste liquid, stabilizing the water quality of coal-to-hydrogen production, and reducing corrosion of equipment and pipelines in the coal-to-hydrogen ammonia synthesis unit. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of this application;
[0021] Figure 2 This is a schematic diagram of the structure of one of the tank components according to an embodiment of this application;
[0022] Figure 3 This is a schematic diagram of the structure of the second connecting pipeline and the second switching valve group according to an embodiment of this application.
[0023] in,
[0024] 1. First storage tank assembly; 11. Storage tank; 12. Circulation return pipeline; 121. Upstream section; 122. Downstream section; 13. Transfer pump; 14. Neutralization pipeline; 15. Monitoring instrument; 16. First connecting pipeline; 17. First switching valve group; 2. Second storage tank assembly; 3. Third storage tank assembly; 4. Waste liquid concentration device; 5. Second connecting pipeline; 51. First pipeline section; 52. Second pipeline section; 53. Third pipeline section; 54. Fourth pipeline section; 6. Second switching valve group; 7. First heat exchanger; 8. Wastewater treatment device; 9. Second heat exchanger; 10. Hydrogen production and ammonia synthesis device. Detailed Implementation
[0025] Various embodiments and features of this application are described herein with reference to the accompanying drawings.
[0026] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this application will be apparent to those skilled in the art.
[0027] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.
[0028] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.
[0029] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application.
[0030] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.
[0031] Specific embodiments of this application are described thereafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that could obscure the application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in a variety of substantially any suitable detailed structures.
[0032] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.
[0033] This application provides an embodiment of a caprolactam wastewater-to-coal slurry co-firing system, such as... Figure 1 and Figure 2 As shown, it includes a first storage tank assembly 1, a second storage tank assembly 2, a third storage tank assembly 3, and a waste liquid concentration device 4.
[0034] Each of the aforementioned tank assemblies includes a tank 11, a circulation return pipeline 12, a transfer pump 13, a neutralization pipeline 14, and a monitoring instrument 15. The tank 11 has a first inlet, a second inlet, and an outlet. The outlet is connected to one end of the circulation return pipeline 12, and the other end of the circulation return pipeline 12 is connected to the second inlet via the transfer pump 13. The outlet of the neutralization pipeline 14 is connected to the inlet of the transfer pump 13 and is used to adjust the pH of the waste liquid. The monitoring instrument 15 is installed on the circulation return pipeline 12 and is used to monitor the pH of the waste liquid online.
[0035] In this configuration, the first inlet of the storage tank 11 of the first storage tank assembly 1 is connected to the waste liquid pipeline; the inlet of the waste liquid concentration device 4 is connected to the downstream section 122 of the circulation return pipeline 12 of the first storage tank assembly 1; the first inlet of the storage tank 11 of the second storage tank assembly 2 is connected to the downstream section 122 of the circulation return pipeline 12 of the first storage tank assembly 1 and the outlet of the waste liquid concentration device 4, respectively; and the first inlet of the storage tank 11 of the third storage tank assembly 3 is connected to the downstream section 122 of the circulation return pipeline 12 of the second storage tank assembly 2.
[0036] In this embodiment, the waste liquid concentration device 4 is used to concentrate caprolactam waste liquid, removing some of the water in the waste liquid through evaporation and other methods, thereby increasing the concentration of useful components in the waste liquid.
[0037] The first storage tank assembly 1, the second storage tank assembly 2, and the third storage tank assembly 3 are used to store and treat waste liquid. Each storage tank assembly includes components such as a storage tank 11, a circulation return pipeline 12, a transfer pump 13, a neutralization pipeline 14, and a monitoring instrument 15, so as to realize the functions of storing, circulating, adjusting pH and monitoring waste liquid.
[0038] During use, caprolactam waste liquid enters storage tank 11 of the first storage tank assembly 1 through the waste liquid pipeline. After being pressurized by the transfer pump 13, the waste liquid returns to storage tank 11 through the second inlet, forming a cycle. During this process, the neutralization pipeline 14 adds a substance for adjusting pH (such as liquid alkali) to the inlet of the transfer pump 13. The monitoring instrument 15 monitors the pH of the waste liquid on the circulating return pipeline 12 in real time to ensure that the pH of the waste liquid is within a suitable range for subsequent treatment.
[0039] The waste liquid concentration device 4 is connected to the downstream section 122 of the circulation return pipeline 12 of the first storage tank assembly 1, and receives the pre-treated waste liquid. The waste liquid is concentrated through evaporation and other methods to reduce its volume and increase the concentration of certain components, thus reducing the burden on subsequent treatment. The concentrated waste liquid is then discharged to the second storage tank assembly 2.
[0040] The first inlet of tank 11 in the second storage tank assembly 2 is connected to both the downstream section 122 of the circulation return pipeline 12 of the first storage tank assembly 1 and the outlet of the waste liquid concentration device 4. This allows it to receive both unconcentrated and concentrated waste liquid. It also includes the circulation return pipeline 12, a transfer pump 13, a neutralization pipeline 14, and a monitoring instrument 15 to further treat the incoming waste liquid, adjust its pH, and monitor it. The treated waste liquid is then transported to the third storage tank assembly 3 via the downstream section 122 of the circulation return pipeline 12.
[0041] The third storage tank assembly 3 receives waste liquid from the downstream section 122 of the circulation return pipeline 12 from the second storage tank assembly 2 and processes it again. Here, the neutralization pipeline 14 will precisely adjust the pH of the waste liquid by supplying liquid alkali or sulfuric acid according to the final pH requirements, ensuring that the waste liquid sent out finally meets the requirements for water-coal slurry production, and then is transported to the subsequent hydrogen production and ammonia synthesis unit 10, etc., for the production and co-firing of water-coal slurry.
[0042] This application utilizes the coordinated operation of multiple storage tank components and a waste liquid concentration device 4 to recycle caprolactam waste liquid, effectively adjusting and concentrating the acidity and alkalinity of the waste liquid. Ultimately, the treated waste liquid can be used for co-firing of water and coal, achieving the goals of resource recycling and environmental pollution reduction.
[0043] In one embodiment, such as Figure 1 As shown, the system includes two first storage tank assemblies 1, a first connecting pipeline 16 is provided between the two first storage tank assemblies 1, and a first switching valve group 17 is provided on the first connecting pipeline 16.
[0044] In this embodiment, the first connecting pipeline 16 is a pipe connecting the two first storage tank assemblies 1 to their respective storage tanks 11, allowing waste liquid to flow between the two tank assemblies. Through this pipeline, the waste liquid in the two storage tanks 11 can be mixed and blended, which helps to balance the composition and properties of waste liquid from different sources and improves the stability of subsequent treatment.
[0045] The first switching valve group 17 is a valve group installed on the first connecting pipeline 16. By controlling the opening and closing of the valve, the waste liquid between the two first storage tank components 1 can be switched or the two storage tank components can be isolated.
[0046] During caprolactam production, various wastewaters and waste liquids are generated, such as benzene extraction residue from the stripping tower, ion exchange regeneration wastewater, and high-COD and ammonia nitrogen wastewater from the plant's drainage ditch. Two of these first storage tank components 1 are connected in parallel at the waste liquid concentration device 4, serving together as buffer tanks for the waste liquid and wastewater.
[0047] The two first storage tank assemblies 1 can be used alternately and cyclically. For example, when one of the storage tanks 11 is being maintained or its internal waste liquid is being treated, the other storage tank 11 can continue to receive and store the waste liquid, ensuring the continuity and stability of waste liquid treatment throughout the entire production process, thereby stabilizing the quality of the water sent out and providing more reliable raw material conditions for the subsequent coal-water slurry preparation and co-firing process.
[0048] Alternatively, one first storage tank assembly 1 stores dilute waste liquid with a lower concentration, and the other first storage tank assembly 1 stores dilute waste liquid with a slightly higher concentration. When the amount of waste liquid to be treated is large, the waste liquid in both storage tanks 11 can be used at the same time.
[0049] This application sets up two first storage tank assemblies 1 and equips them with a first connecting pipeline 16 and a first switching valve group 17, which increases the flexibility and operability of the system, facilitates different treatments or maintenance of the two first storage tank assemblies 1, and improves the reliability and adaptability of the system.
[0050] In another embodiment, the concentrations of the dilute waste liquid stored in the tanks 11 of the two first tank assemblies 1 are different.
[0051] When the caprolactam unit generates wastewater or waste liquid, the waste liquid distribution between the two storage tanks 11 can be adjusted according to the water quality (e.g., the acidity, alkalinity, composition, etc. of the wastewater) or process requirements (e.g., the requirements of subsequent treatment processes for the waste liquid). The waste liquid can be classified and stored in one of the first storage tank components 1 or the other first storage tank component 1 using the first connecting pipeline 16 and the first switching valve group 17.
[0052] The two first storage tank assemblies 1 store dilute waste liquid of different concentrations respectively. This allows for flexible selection of waste liquid of different concentrations according to the needs of subsequent treatment processes, or mixing of waste liquids of different concentrations to achieve the best treatment effect.
[0053] Specifically, when the acidity or alkalinity of the waste liquid in the two storage tanks 11 differs significantly, the opening and closing of the first connecting pipeline 16 can be controlled by the first switching valve group 17 to mix the waste liquid in the two storage tanks 11, thereby adjusting the acidity or alkalinity and achieving a better treatment effect.
[0054] For example, one first storage tank assembly 1 stores dilute waste liquid with a lower concentration, and another first storage tank assembly 1 stores dilute waste liquid with a slightly higher concentration. When there are specific requirements for the concentration of the treated waste liquid, the two types of waste liquid can be mixed in a certain proportion before treatment.
[0055] This application increases the system's ability and flexibility to treat waste liquids of different concentrations, enabling it to better adapt to caprolactam waste liquids of different concentrations generated in actual production, and improving the overall treatment efficiency and adaptability of the system.
[0056] In one embodiment, such as Figure 1 and Figure 3 As shown, the downstream sections 122 of the circulation return pipelines 12 of the two first storage tank assemblies 1 are connected to the inlet of the waste liquid concentration device 4 and the first inlet of the second storage tank assembly 2 respectively through the second connecting pipeline 5. The second connecting pipeline 5 is equipped with a second switching valve group 6.
[0057] In this embodiment, the second connecting pipeline 5 is a pipeline connecting the downstream section 122 of the circulation return pipeline 12 of the two first storage tank assemblies 1 to the inlet of the waste liquid concentration device 4 and the first inlet of the second storage tank assembly 2. The second switching valve group 6 is a valve group installed on the second connecting pipeline 5, used to control the flow direction and flow rate of waste liquid between the two first storage tank assemblies 1, the waste liquid concentration device 4 and the second storage tank assembly 2.
[0058] The second connecting pipeline 5 includes a first pipeline segment 51, a second pipeline segment 52, a third pipeline segment 53, and a fourth pipeline segment 54. The second switching valve group 6 includes a first valve, a second valve, a third valve, and a fourth valve. The first valve is installed on the first pipeline segment 51, the second valve is installed on the second pipeline segment 52, the third valve is installed on the third pipeline segment 53, and the fourth valve is installed on the fourth pipeline segment 54.
[0059] Assume that the two first storage tank assemblies 1 are first storage tank assembly A and first storage tank assembly B, respectively. The two ends of the first pipeline segment 51 are the downstream section 122 of the first storage tank assembly A and the inlet of the waste liquid concentration device 4, respectively. The two ends of the second pipeline segment 52 are connected to the downstream section 122 of the first storage tank assembly B and the first pipeline segment 51, respectively. The two ends of the third pipeline segment 53 are connected to the first inlet of the first pipeline segment 51 and the first inlet of the storage tank 11 of the second storage tank assembly 2, respectively. The two ends of the fourth pipeline segment 54 are connected to the second pipeline segment 52 and the third pipeline segment 53, respectively.
[0060] The waste liquid recycled from the first storage tank assembly 1 has two flow options. When the waste liquid needs to be concentrated, it can be controlled by the second switching valve group 6 to introduce the waste liquid into the waste liquid concentration device 4, where it will be concentrated before entering the subsequent process. If the waste liquid does not need to be concentrated or needs to directly enter the next processing stage, the valve can be switched to allow the waste liquid to flow into the second storage tank assembly 2 for further processing.
[0061] When the hydrogen production and ammonia synthesis unit 10 is operating normally, if the waste liquid treatment in the first storage tank assembly 1 meets the requirements for subsequent coal-water slurry production, the valve leading to the waste liquid concentration device 4 can be closed, allowing the waste liquid to flow directly to the second storage tank assembly 2, thereby improving treatment efficiency. However, when the hydrogen production and ammonia synthesis unit 10 malfunctions or is under maintenance, and the coal-water slurry cannot normally consume the waste liquid, or when the composition, pH, or other indicators of the waste liquid in the first storage tank assembly 1 are abnormal, the valve leading to the waste liquid concentration device 4 can be opened to send the waste liquid to that device for treatment, ensuring the stable operation of the entire system.
[0062] Through the second switching valve group 6, the waste liquid in the downstream section 122 of the circulation return pipeline 12 of the two first storage tank components 1 can be selected to be transported to the waste liquid concentration device 4 for concentration, or directly transported to the second storage tank component 2, or simultaneously transported to both, and the flow direction and distribution of the waste liquid can be flexibly adjusted according to actual needs.
[0063] This application allows for flexible adjustment of waste liquid flow and treatment methods based on different production conditions and waste liquid characteristics. For example, when the incoming liquid volume suddenly increases, or when the composition of the waste liquid fluctuates significantly at a certain moment, a portion of the waste liquid can be promptly introduced into the waste liquid concentration device 4 for concentration and volume reduction. Conversely, when the system operates smoothly and the waste liquid quality is stable, the process can be simplified, allowing the waste liquid to quickly enter subsequent treatment stages, thereby ensuring the efficient and stable operation of the caprolactam waste liquid treatment process.
[0064] The structural design of this application is reasonable, which further improves the flexibility and adjustability of the system. It can reasonably allocate the flow direction of waste liquid according to different working conditions and needs, and ensure the stable operation of the system.
[0065] In one embodiment, such as Figure 1 As shown, the outlet of the waste liquid concentration device 4 is connected to the wastewater treatment device 8 through the first heat exchanger 7.
[0066] In this embodiment, the first heat exchanger 7 is a device for exchanging heat with the gas discharged from the outlet of the waste liquid concentration device 4. It cools or heats the gas by transferring heat with other media.
[0067] The gas generated during the waste liquid concentration process of the waste liquid concentration device 4 is discharged from the gas outlet and enters the first heat exchanger 7. In the first heat exchanger 7, it exchanges heat with the relevant medium in the wastewater treatment device 8 to realize energy recovery or pretreatment of the gas, and then enters the wastewater treatment device 8.
[0068] Before the gas is discharged into the wastewater treatment device 8, it undergoes preliminary treatment in the first heat exchanger 7. Through heat exchange, the temperature of the gas is adjusted, and some volatile harmful substances or components that may affect the subsequent wastewater treatment effect may undergo physical or chemical changes during the temperature change process, becoming easier to be removed by the wastewater treatment device 8, thereby improving the treatment efficiency and effect of the wastewater treatment device 8.
[0069] If untreated high-temperature gas enters the wastewater treatment device 8 directly, it may adversely affect the activity of microorganisms and the treatment process within the device, impacting the stability of wastewater treatment and ensuring compliance with discharge standards. The first heat exchanger 7 regulates the temperature and composition of the gas entering the wastewater treatment device 8, making it more suitable for its operational requirements and ensuring stable operation.
[0070] This application realizes energy recovery and utilization, reduces energy waste, and at the same time pre-treats the gas entering the sewage treatment device 8, which is beneficial to improving the treatment effect and stability of the sewage treatment device 8.
[0071] In one embodiment, such as Figure 1As shown, the system also includes a second heat exchanger 9, which is located between the downstream section 122 of the circulation return pipeline 12 of the second storage tank assembly 2 and the first liquid inlet of the storage tank 11 of the third storage tank assembly 3.
[0072] In this embodiment, since the temperature of the caprolactam waste liquid affects the subsequent treatment effect, especially before entering the third storage tank assembly 3, a suitable temperature is crucial. The second heat exchanger 9 can regulate the temperature of the waste liquid flowing out of the downstream section 122 of the circulation return pipeline 12 of the second storage tank assembly 2.
[0073] If the waste liquid temperature is too high, it may adversely affect the equipment and reactions within the third storage tank assembly 3, such as accelerating equipment corrosion and affecting the chemical reaction balance; if the temperature is too low, it may cause certain substances to crystallize and precipitate, clogging pipes or affecting the reaction rate of subsequent processes. The second heat exchanger 9 can adjust the waste liquid temperature to a suitable range for the third storage tank assembly 3 to handle.
[0074] Specifically, the temperature of waste liquids from different sources varies significantly. For example, the temperature of ion exchange regeneration wastewater and wastewater from the plant's drainage ditch may differ. After a series of treatments, the second heat exchanger 9 can unify the temperature of the waste liquids before they enter the third storage tank assembly 3. Stable temperature conditions help ensure the stable operation of the treatment process within the third storage tank assembly 3, avoiding problems such as unstable treatment effects and equipment failures caused by temperature fluctuations, thereby ensuring the stable operation of the entire caprolactam waste liquid treatment system.
[0075] Furthermore, a suitable temperature facilitates more efficient subsequent operations such as pH adjustment and component mixing within the third storage tank assembly 3. This is because a suitable temperature allows for a more complete neutralization reaction, better ensuring no ammonia release from the ammonium sulfate in the waste liquid, reducing the corrosiveness of the waste liquid, providing higher-quality raw materials for the subsequent production of coal-water slurry, and improving the overall treatment efficiency of the coal-water slurry co-firing process.
[0076] In one embodiment, such as Figure 2 As shown, the pipeline between the inlet of the circulation return pipeline 12 and the inlet of the delivery pump 13 is the upstream section 121, and the pipeline between the outlet of the delivery pump 13 and the outlet of the circulation return pipeline 12 is the downstream section 122. One end of the neutralization pipeline 14 is connected to the upstream section 121.
[0077] In this embodiment, the pipeline between the inlet of the recirculation pipeline 12 and the inlet of the transfer pump 13 is defined as the upstream section 121. This section is mainly responsible for transporting the waste liquid from the storage tank 11 to the transfer pump 13, and is the starting point for waste liquid recycling. Simultaneously, one end of the neutralization pipeline 14 is connected to the upstream section 121, allowing the addition of a pH-adjusting substance (such as liquid alkali, sulfuric acid, etc.) through the neutralization pipeline 14 before the waste liquid enters the transfer pump 13. This connection method enables timely pH adjustment of the waste liquid, preparing it for subsequent treatment. For example, when the waste liquid is detected to be highly acidic, an appropriate amount of liquid alkali can be added to the upstream section 121 through the neutralization pipeline 14 to initially adjust the pH value of the waste liquid, ensuring the stable operation of subsequent treatment processes.
[0078] The pipeline between the outlet of the transfer pump 13 and the outlet of the circulation return pipeline 12 is the downstream section 122. The waste liquid, pressurized by the transfer pump 13, flows in the downstream section 122, completing the interaction with other equipment or devices. For example, the inlet of the monitoring instrument 15 is connected to the downstream section 122 to monitor the pH of the waste liquid in real time, provide feedback on the adjustment effect, and accurately control the amount of substances added to the neutralization pipeline 14 to ensure that the pH of the waste liquid meets the process requirements.
[0079] In addition, the downstream section 122 will also transport the waste liquid to subsequent treatment units, such as the waste liquid concentration device 4 and other storage tanks 11, so that the waste liquid can be continuously circulated and treated in the system until the expected treatment standard is reached.
[0080] Through the coordinated operation of upstream section 121, downstream section 122, and neutralization pipeline 14, a complete wastewater treatment cycle is formed. Upstream section 121 provides an inlet for wastewater regulation and transportation, downstream section 122 is responsible for transporting the treated wastewater to subsequent stages and providing feedback monitoring information, and neutralization pipeline 14 regulates the pH of the wastewater at key locations. Together, they ensure the stable and efficient operation of the entire caprolactam wastewater-to-coal slurry co-firing process system, achieving effective wastewater treatment and resource recovery.
[0081] This application clarifies the functions of different parts in the circulating return pipeline 12. By reasonably setting the upstream section 121 and the downstream section 122, and connecting the neutralization pipeline 14 and the monitoring instrument 15 at the corresponding positions, the effective adjustment and real-time monitoring of the acidity and alkalinity of the waste liquid are realized.
[0082] In one embodiment, such as Figure 1 and Figure 2 As shown, the inlet of the monitor 15 is connected to the downstream section 122, and the outlet of the monitor 15 is connected to the upstream section 121.
[0083] In this embodiment, the inlet of the monitor 15 is connected to the downstream section 122, enabling it to acquire waste liquid samples that have been pressurized and preliminarily mixed by the transfer pump 13. Because the waste liquid in the downstream section 122 has undergone certain treatment and is flowing towards subsequent stages, sampling and monitoring at this location allows for real-time monitoring of the current pH level of the waste liquid.
[0084] For example, when liquid alkali or sulfuric acid is added to the waste liquid, the change in pH can be detected in the downstream section 122 by the monitoring instrument 15, so as to determine whether the adjustment effect has achieved the expected result.
[0085] The outlet of the monitor 15 is connected to the upstream section 121, allowing the detected waste liquid to return to the circulation system. If the monitor 15 detects that the pH of the waste liquid does not meet the set standard, the control system will adjust the amount of liquid alkali or sulfuric acid added to the neutralization pipeline 14 based on the detection results. The detected waste liquid flows back to the upstream section 121, where it can mix again with newly entering waste liquid and continue to participate in subsequent regulation and treatment processes, forming a dynamic regulation feedback closed loop.
[0086] For example, if the waste liquid is detected to be too acidic, the system increases the amount of liquid alkali added. The waste liquid after detection is returned to the upstream section 121 and mixed with the new waste liquid. This helps to adjust the pH more accurately and ensure that the pH of the waste liquid remains stable within a suitable range throughout the entire treatment process, thus ensuring the stable operation of the subsequent coal-water slurry production and co-firing process.
[0087] This application ensures real-time and accurate monitoring of the acidity and alkalinity of the waste liquid, and realizes the return of the waste liquid after testing, avoiding waste liquid and environmental pollution, while also helping to maintain the balance of waste liquid within the system.
[0088] In one embodiment, such as Figure 1 As shown, the material transported in the neutralization pipeline 14 of the first storage tank assembly 1 and the second storage tank assembly 2 is liquid alkali, and the material transported in the neutralization pipeline 14 of the third storage tank assembly 3 is liquid alkali or sulfuric acid.
[0089] In this embodiment, liquid alkali is transported through the neutralization pipeline 14 of the first storage tank assembly 1 and the second storage tank assembly 2 to adjust the pH of the waste liquid to a suitable range. The neutralization pipeline 14 of the third storage tank assembly 3 can transport liquid alkali or sulfuric acid as needed to further precisely adjust the pH of the waste liquid to meet the requirements of subsequent processes such as the production of coal-water slurry.
[0090] The caprolactam waste liquid has a complex composition. The first storage tank assembly 1 receives various waste liquids from the unit, such as benzene extraction residue and ion exchange regeneration wastewater. Most of these waste liquids are acidic because they contain acidic substances such as sulfuric acid. Liquid alkali can neutralize these acidic substances. The first storage tank assembly 1 adds liquid alkali to the waste liquid through neutralization pipeline 14 to initially adjust the pH of the waste liquid, reduce its acidity, and mitigate corrosion to the equipment. For example, if the waste liquid contains sulfuric acid, the hydroxide ions in the liquid alkali will react with the hydrogen ions in the sulfuric acid to produce water, thereby increasing the pH value of the waste liquid.
[0091] The second storage tank assembly 2 receives waste liquid from the first storage tank assembly 1 or the waste liquid concentration device 4, and continues to use liquid alkali to adjust the pH value, further stabilizing the pH value of the waste liquid, ensuring that the pH value of the waste liquid entering the third storage tank assembly 3 is within a suitable range, in preparation for subsequent treatment.
[0092] The primary objective of the third storage tank assembly 3 is to precisely adjust the pH of the wastewater to meet the requirements of the gasification process in the hydrogen production and ammonia synthesis unit 10, i.e., ultimately controlling the pH of the wastewater sent to the hydrogen production and ammonia synthesis unit 10 to 5. If the wastewater is still acidic after the first two stages of adjustment, liquid alkali needs to be added for neutralization; if the wastewater is alkaline, sulfuric acid is added for adjustment.
[0093] For example, when the pH value of the waste liquid is detected to be higher than 5, sulfuric acid is added through neutralization pipeline 14. The hydrogen ions in the sulfuric acid react with the hydroxide ions in the waste liquid to lower the pH value. When the pH value is lower than 5, liquid alkali is added to raise the pH value, thereby achieving precise control of the acidity and alkalinity of the waste liquid and ensuring the stable operation of the subsequent coal-water slurry production and gasification furnace combustion hydrogen production process.
[0094] Based on the characteristics of waste liquid in different storage tank components and the requirements of subsequent processes, this application selects a suitable neutralizing agent, which can more accurately adjust the pH of the waste liquid, improve the system's adaptability and flexibility in waste liquid treatment, and help improve the quality of coal-water slurry.
[0095] In one embodiment, such as Figure 1 As shown, the downstream section 122 of the circulation return pipeline 12 of the third storage tank assembly 3 is connected to the hydrogen production and ammonia synthesis unit 10 to utilize the treated waste liquid to produce coal-water slurry.
[0096] In this embodiment, the waste liquid generated during the caprolactam production process, after preliminary treatment in the first storage tank assembly 1 and the second storage tank assembly 2, and related treatment in the waste liquid concentration device 4, enters the third storage tank assembly 3. In the third storage tank assembly 3, the waste liquid undergoes further treatment, including more precise pH adjustment and other necessary treatment steps to ensure it meets the requirements of subsequent processes. After completing a series of treatments in the third storage tank assembly 3, the waste liquid is transported to the hydrogen production and ammonia synthesis unit 10 via the downstream section 122 of the circulation return pipeline 12.
[0097] The reason for transporting the treated waste liquid to the hydrogen production and ammonia synthesis unit 10 to produce coal-water slurry is that this waste liquid contains a certain amount of carbonaceous organic matter and other components. Mixing it with crushed coal powder to produce coal-water slurry can realize the resource utilization of the waste liquid, avoiding the complex and costly treatment processes in traditional treatment methods, such as evaporation and concentration in the waste liquid concentration unit 4 and incineration in the alkali refining unit, thus reducing treatment costs and environmental burden.
[0098] On the other hand, the carbonaceous organic matter in the waste liquid not only increases the calorific value of the gasifier during the combustion of the coal-water slurry, but also generates hydrogen, indirectly improving the overall calorific value of the coal-water slurry in the coal-to-hydrogen ammonia synthesis unit, reducing coal consumption in the hydrogen production process, and improving energy efficiency. In this way, the conversion from caprolactam waste liquid to hydrogen production feedstock is realized, optimizing the resource utilization process and improving the economic and environmental benefits of the entire production system.
[0099] This application realizes the resource utilization of caprolactam waste liquid, transforming the waste liquid that might otherwise need to be treated and discharged into valuable coal-water slurry for use in processes such as hydrogen production, reducing environmental pollution, and also lowering the raw material cost of the hydrogen production and ammonia synthesis unit 10.
[0100] In summary, the working process of this application is as follows:
[0101] The various waste liquids generated by the caprolactam unit are first discharged into two storage tanks 11 of the first storage tank assembly 1. These two storage tanks 11 are installed in parallel at the waste liquid concentration device 4, serving as buffer tanks for waste liquids and wastewater. Through the first connecting pipeline 16 and the first switching valve group 17, different waste liquids can be classified and stored in the corresponding storage tanks 11 according to their pH, composition, and other characteristics. For example, after sampling and analysis, highly acidic waste liquids and alkaline waste liquids can be stored separately for subsequent treatment.
[0102] The pH is adjusted initially via two first storage tank assemblies 11. Waste liquid in storage tank 11 flows to the circulation return pipeline 12. In the upstream section 121 of the circulation return pipeline 12, liquid alkali from the neutralization pipeline 14 is dispersed and mixed by the impeller of the transfer pump 13. Based on the detection results of the monitoring instrument 15, the pH of the waste liquid is adjusted initially. The purpose is to neutralize some of the sulfuric acid or sodium hydroxide, reducing the corrosiveness of the waste liquid while ensuring that no ammonia volatilizes. When the monitoring instrument 15 detects that the pH value of the waste liquid is low and acidic, liquid alkali is automatically added to raise the pH value.
[0103] A second connecting pipeline 5 and a second switching valve group 6 are provided between the downstream section 122 of the circulation return pipeline 12 of the two first storage tank assemblies 1 and the waste liquid concentration device 4 and the storage tank 11 of the second storage tank assembly 2. During normal operation of the hydrogen production and ammonia synthesis unit 10, the valve that allows waste liquid to flow to the waste liquid concentration device 4 is closed, and the diluted waste liquid is transported to the storage tank 11 of the second storage tank assembly 2. However, when the coal-to-hydrogen hydrogen synthesis and ammonia synthesis unit 10 malfunctions or is under maintenance, and the coal-water slurry cannot consume the wastewater generated by the caprolactam unit, or when certain indicators of the waste liquid are abnormal and require concentration treatment, the valve that allows waste liquid to flow to the waste liquid concentration device 4 is opened, and the waste liquid is sent to that device for treatment, ensuring stable operation of the unit.
[0104] Secondary pH adjustment and temperature control are performed through the second storage tank assembly 2. After the waste liquid enters the storage tank 11 of the second storage tank assembly 2, the pH of the waste liquid is adjusted again, that is, secondary pH adjustment, in order to further stabilize the pH value of the wastewater to be sent out.
[0105] Meanwhile, when the waste liquid temperature in the downstream section 122 of the circulation return pipeline 12 of the second storage tank assembly 2 is higher than 40°C, it is switched to the second heat exchanger 9 for cooling; when it is lower than 40°C, it is directly transported to the storage tank 11 of the third storage tank assembly 3 without cooling through the cross-line, thereby achieving effective control of the waste liquid temperature.
[0106] The final pH adjustment is performed via the third storage tank assembly 3. After the previous treatment, the wastewater enters the storage tank 11 of the third storage tank assembly 3 for three pH adjustments. Through dual-loop control of liquid alkali and sulfuric acid, acid or alkali is automatically added according to the set value of the monitoring instrument 15, ultimately ensuring that the pH of the wastewater sent to the hydrogen production and ammonia synthesis unit 10 is precisely controlled at 5 and the temperature at 40℃, so as to meet the requirements of subsequent processes.
[0107] After undergoing the aforementioned series of treatments, the waste liquid is transported to the gasification process of the hydrogen production and ammonia synthesis unit 10 via the downstream section 122 of the circulation return pipeline 12 of the third storage tank assembly 3. In the gasification process, the waste liquid is mixed with crushed coal powder in a certain proportion to form a coal-water slurry, which is then fed into the gasifier for combustion under high temperature and pressure. During this process, the combustion of carbonaceous organic matter in the waste liquid not only increases the calorific value of the gasifier but also produces hydrogen, achieving resource utilization of the waste liquid while reducing coal consumption in hydrogen production and ammonia synthesis.
[0108] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.
Claims
1. A system for blending water-coal slurry with caprolactam waste liquid, characterized in that, The system comprises a first storage tank assembly, a second storage tank assembly, a third storage tank assembly and a waste liquid concentration device. Each of the storage tank assemblies comprises a storage tank, a circulating return pipeline, a delivery pump, a neutralization pipeline and a monitoring instrument, the storage tank has a first liquid inlet, a second liquid inlet and a liquid outlet, the liquid outlet is connected to one end of the circulating return pipeline, the other end of the circulating return pipeline is connected to the second liquid inlet through the delivery pump, the liquid outlet of the neutralization pipeline is connected to the liquid inlet of the delivery pump for adjusting the pH value of the waste liquid, and the monitoring instrument is arranged on the circulating return pipeline for online monitoring of the pH value of the waste liquid. The first liquid inlet of the storage tank of the first storage tank assembly is connected to a waste liquid pipeline, the liquid inlet of the waste liquid concentration device is connected to the downstream section of the circulating return pipeline of the first storage tank assembly, the first liquid inlet of the storage tank of the second storage tank assembly is connected to the downstream section of the circulating return pipeline of the first storage tank assembly and the liquid outlet of the waste liquid concentration device respectively, and the first liquid inlet of the storage tank of the third storage tank assembly is connected to the downstream section of the circulating return pipeline of the second storage tank assembly.
2. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 1, wherein, The system comprises two first storage tank assemblies, a first communication pipeline is arranged between the two first storage tank assemblies, and a first switch valve group is arranged on the first communication pipeline.
3. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 2, wherein, The downstream sections of the circulating return pipelines of the two first storage tank assemblies are respectively connected to the liquid inlet of the waste liquid concentration device and the first liquid inlet of the second storage tank assembly through a second communication pipeline, and a second switch valve group is arranged on the second communication pipeline.
4. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 1, wherein, The gas outlet of the waste liquid concentration device is connected to a sewage treatment device through a first heat exchanger.
5. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 1, wherein, The system further comprises a second heat exchanger, which is arranged between the downstream section of the circulating return pipeline of the second storage tank assembly and the first liquid inlet of the storage tank of the third storage tank assembly.
6. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 1, wherein, The pipeline between the liquid inlet of the circulating return pipeline and the liquid inlet of the delivery pump is an upstream section, the pipeline between the liquid outlet of the delivery pump and the liquid outlet of the circulating return pipeline is a downstream section, and one end of the neutralization pipeline is connected to the upstream section.
7. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 6, wherein, The liquid inlet of the monitoring instrument is connected to the downstream section, and the liquid outlet of the monitoring instrument is connected to the upstream section.
8. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 1, wherein, The materials conveyed in the neutralization pipelines of the first storage tank assembly and the second storage tank assembly are liquid alkali, and the materials conveyed in the neutralization pipeline of the third storage tank assembly are liquid alkali or sulfuric acid.
9. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 1, wherein, The downstream section of the circulating return pipeline of the third storage tank assembly is connected to a hydrogen production and ammonia synthesis device, so as to use the treated waste liquid to prepare coal water slurry.
10. The system for blending and burning of water coal slurry from caprolactam waste liquid according to claim 2, wherein, The concentrations of the dilute waste liquid stored in the storage tanks of the two first storage tank assemblies are different.