A cleaning system for reducing solid blockage of a production device in an oxamide production process and a cleaning method thereof

Abstract

The present application relates to the technical field of coal chemical industry, and particularly relates to a cleaning system for reducing solid blockage of a production device in an oxamide production process and a cleaning method thereof. The system comprises a cleaning main pipe, a cleaning solvent pipeline, a branch pipe device, a backflow main pipe and a backflow device. The inlet end of the cleaning main pipe is in communication with the cleaning solvent pipeline. The branch pipe device comprises a plurality of first branches arranged in parallel, and each first branch is provided with a corresponding to-be-cleaned device. The inlet end of each first branch is in communication with the cleaning main pipe. The backflow main pipe is used for collecting cleaning backflow liquid flowing out of each first branch. The backflow device comprises at least one separation tank, and the separation tank is in communication with the backflow main pipe and the cleaning main pipe. The separation tank is used for separating the solvent in the cleaning backflow liquid, and the solvent is returned to the cleaning main pipe. The cleaning system of the present application reduces the problem of pipeline or device blockage in the oxamide slurry conveying process.

Description

Technical Field

[0001] This invention relates to the field of coal chemical technology, and in particular to a cleaning system and method for reducing solid blockage in oxalamide production equipment. Background Technology

[0002] Oxalide is a high-performance slow-release nitrogen fertilizer with a nitrogen content of 31.8%. It appears as white crystals or powder, is non-hygroscopic, non-toxic, and easy to store. Oxalide has extremely low solubility in water (approximately 0.016%), and gradually releases ammoniacal nitrogen and organic carbon during hydrolysis or biological decomposition. Its nitrogen fertilizer utilization rate can reach 65%–80%, and compared with fast-acting fertilizers such as ammonium bicarbonate, ammonium sulfate, and urea, it has significant advantages such as a longer fertilizer effect period and less pollution.

[0003] Currently, the most promising method for industrial preparation of oxalamide is the oxalate ester method, which utilizes the ammonolysis reaction of dimethyl oxalate and ammonia to generate oxalamide. In recent years, with the development of C1 chemical engineering, the technology of synthesizing dimethyl oxalate from coal gasification CO to produce ethylene glycol has achieved breakthroughs and large-scale application, significantly reducing the cost of dimethyl oxalate. Therefore, the ammonolysis synthesis of oxalamide using dimethyl oxalate has excellent industrial prospects. In the liquid-phase ammonolysis process, a methanol solution of liquid ammonia and a methanol solution of dimethyl oxalate are typically mixed and subjected to ammonolysis. After the reaction, an oxalamide slurry (i.e., a suspension containing the solid phase product of oxalamide) is obtained. This slurry then undergoes post-processing steps such as flash evaporation, filtration, washing, and drying to finally form the crystalline oxalamide product.

[0004] In the aforementioned process, oxamide slurry needs to be sequentially transported from the ammonolysis reactor to multiple post-processing devices, including a flash evaporator, a filtration unit, a washing unit, and a drying unit. Oxaamide is sparingly soluble in water, slightly soluble in alcohols and ethers, and is a stable crystalline powder at room temperature. During pipeline transport, the oxamide solid particles in the slurry tend to gradually deposit on the inner walls of the pipelines and equipment surfaces. If the pipelines or equipment are not thoroughly cleaned after each production run, the residual oxamide slurry will accumulate on the walls over time, gradually thickening and solidifying into hard oxamide crystal deposits. Once this solidification occurs, it gradually reduces the flow cross-section of the pipeline, eventually causing complete blockage of the equipment or pipeline, forcing the production process to halt.

[0005] To address the aforementioned blockage problem, existing technologies typically employ solvent forward or backflushing, which involves introducing cleaning solvents into the blocked pipes in an attempt to dissolve or flush away the deposits. However, because oxalamide is poorly soluble in common solvents (poorly soluble in water, slightly soluble in alcohols and ethers), the solidified oxalamide crystal layer is difficult to remove effectively by simple solvent flushing, rendering the flushing process largely ineffective. Once a blockage occurs, the only recourse is often to halt production, disassemble the pipes or equipment, and clear the blockage using mechanical methods (such as scraping or hammering). This approach not only severely disrupts normal production and reduces efficiency but also involves working in high-temperature, high-pressure, or toxic environments, posing significant safety hazards.

[0006] Therefore, there is an urgent need to provide a cleaning device for reducing solid blockage of pipes or equipment during the oxamide production process. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a cleaning system and cleaning method for reducing solid blockage in oxalamide production equipment, which solves the technical problems in the prior art where solid particles deposit during oxalamide slurry transportation cause blockage in pipes and equipment, conventional solvent flushing is ineffective in removing deposits, and blockage requires production shutdown for mechanical unblocking, which affects production efficiency and poses safety hazards.

[0008] To achieve the above and other related objectives, the present invention is obtained through the following technical solution.

[0009] The first aspect of this invention is to provide a cleaning system for reducing solid blockage in oxalamide production equipment. The system includes a main cleaning pipe, cleaning solvent lines, branch pipes, a return main pipe, and a return device. The inlet end of the main cleaning pipe is connected to the cleaning solvent lines. The branch pipes include multiple parallel first branches, each corresponding to a device to be cleaned, and the inlet end of each first branch is connected to the main cleaning pipe. The return main pipe collects the cleaning return liquid flowing from each first branch. The return device includes at least one separation tank, which is connected to both the return main pipe and the main cleaning pipe. The separation tank separates the solvent from the cleaning return liquid, and the solvent is returned to the main cleaning pipe.

[0010] The present invention constructs a cleaning device by setting up a separation tank, a transfer pump, a cleaning main pipe, and a return main pipe.

[0011] In some embodiments of the present invention, the equipment to be cleaned is selected from one or more of vertical storage tanks, horizontal storage tanks, reactors, heat exchangers, flash tanks, distillation columns, washing columns, or solid-liquid separators. In practical applications, the equipment to be cleaned covers all equipment that the oxamide slurry passes through in the production process. For example, the equipment to be cleaned includes, but is not limited to: reaction equipment used to generate oxamide slurry in the ammonolysis reaction section, flash separation equipment in the flash separation section, solid-liquid separation equipment in the solid-liquid separation section, and distillation separation equipment in the distillation separation section containing oxamide solvent. In other words, any contact equipment where solid blockage may occur during the flow of oxamide slurry between different sections can be used as the equipment to be cleaned in the present invention.

[0012] In some embodiments of the present invention, the system further includes a slurry main pipe and slurry branches corresponding to each of the separation tanks, wherein the slurry separated by the separation tanks flows into the slurry main pipe via the slurry branches for subsequent production;

[0013] In some embodiments of the present invention, a return manifold is provided between the first branch and the return main pipe, and the return manifold is used to collect the cleaning return liquid flowing out of each first branch.

[0014] In some embodiments of the present invention, a return pump is installed on the return manifold. Non-pipeline equipment to be cleaned is characterized by its large volume, and when the outlet pipe resistance is high, material accumulation can easily occur within the equipment. This application installs a return pump on the outlet branch pipe of the equipment to be cleaned to reduce the outlet resistance of the equipment during cleaning and avoid liquid accumulation.

[0015] In some embodiments of the present invention, the first branch includes an inlet branch pipe and an outlet branch pipe. One end of the inlet branch pipe is connected to the main cleaning pipe, and the other end is connected to the inlet of the equipment to be cleaned; one end of the outlet branch pipe is connected to the outlet of the equipment to be cleaned, and the other end is connected to the return main pipe. Both the inlet and outlet branch pipes are equipped with shut-off valves, which are automatic control valves used to open and close the corresponding pipes, thereby facilitating automatic control of the cleaning process. Furthermore, the piping of the cleaning device can use the same specifications and layout as the piping of public utility pipelines, which not only makes the overall appearance neat and uniform but also effectively reduces errors during piping connections.

[0016] In some embodiments of the present invention, a nozzle is connected to the end of the inlet branch pipe. The nozzle is disposed inside the non-pipeline equipment to be cleaned. By providing the nozzle, the interior of the non-pipeline equipment to be cleaned can be cleaned without dead angles, thereby effectively avoiding the occurrence of blockage problems, and can be used as a pre-cleaning process before equipment maintenance. The nozzle can be a pressure nozzle or a spin-type nozzle, and the number of nozzles can be selected according to the volume of the non-pipeline equipment to be cleaned.

[0017] In some embodiments of the present invention, the branch pipe device further includes a second branch that is connected to each separation tank. The inlet end of each second branch is connected to the main cleaning pipe, and the outlet end is located inside the separation tank for conveying cleaning solvent to the separation tank.

[0018] In some embodiments of the present invention, the outlet end of the second branch is connected to a nozzle for cleaning the separation tank.

[0019] In some embodiments of the present invention, the branch pipe device further includes a third branch, on which a pipe to be cleaned is provided, and the third branch is connected to the return main pipe;

[0020] In some embodiments of the present invention, a cleaning branch is provided between the main cleaning pipe and each of the separation tanks;

[0021] In some embodiments of the present invention, a reflux branch is provided between the reflux main and each of the separation tanks;

[0022] In some embodiments of the present invention, the separation tank includes an upper end cap, a cylinder and a lower end cap that are arranged sequentially from top to bottom and integrally formed;

[0023] The separator is a vertical tank. Elliptical heads are preferred for both the upper and lower end caps due to their high pressure resistance and ease of processing. Most importantly, they facilitate the separation of oxalamide solids from the cleaning solvent. While flat-bottomed end caps are easier to process, they are generally not pressure-resistant and hinder effective separation of oxalamide from the cleaning solvent. The clear liquid outlet, connected to the cleaning branch, is located at the top of the separator, the slurry outlet is below the clear liquid outlet, and the drain outlet is at the bottom of the separator. Due to the settling effect of oxalamide, a very small amount of cleaning solvent containing oxalamide can be drawn from the clear liquid outlet and fed into the main cleaning pipe for cleaning the equipment. When the amount of oxalamide in the separator is too high, the bottom agitator can be activated to disperse the settled and solidified oxalamide into a slurry in the cleaning solvent. This slurry is then output from the slurry outlet to the slurry branch, and subsequently to the main slurry pipe for further processing.

[0024] In some embodiments of the present invention, the reflux device includes 2-5 separation tanks. Preferably, there are 2 separation tanks, specifically a first separation tank and a second separation tank, which are connected in parallel and serve as backups for each other. When the cleaning solvent from the first separation tank is used to clean the equipment to be cleaned, the cleaning solvent is returned to the second separation tank after cleaning. Alternatively, the cleaning solvent from the second separation tank can be used to clean the equipment to be cleaned, and the cleaning solvent is returned to the first separation tank after cleaning. When the first separation tank is in the cleaning state, the second separation tank can be in the slurry extraction state; when the second separation tank is in the cleaning state, the first separation tank can also be in the slurry extraction state. This backup design ensures that the cleaning device can always meet the cleaning needs of the production equipment, preventing insufficient processing capacity of the cleaning device from causing inability to clean normally and further affecting normal production.

[0025] In some embodiments of the present invention, the second branch is connected to the upper end cap;

[0026] In some embodiments of the present invention, the cleaning branch is disposed on the side of the cylinder;

[0027] In some embodiments of the present invention, the slurry branch is disposed on the lower end cap;

[0028] In some embodiments of the present invention, the return branch is connected to the upper end cap;

[0029] In some embodiments of the present invention, a drain pipe is connected to the bottom of the lower head; the waste liquid separated by the separation tank is output through the drain pipe; during the initial operation phase after the device is installed, the entire system needs to be water-washed to remove welding residues (such as welding slag), machining debris (such as iron filings), and other solid impurities. At this time, the wastewater generated during washing is directly discharged through the drain port at the bottom of the device and does not enter the subsequent separation or recycling process. On the other hand, when the device needs to be shut down for maintenance, all the residual oxalamide slurry in each separation tank must be discharged through the drain port before cleaning water can be introduced into the device for subsequent cleaning operations. That is, under shutdown and maintenance conditions, the drain port simultaneously serves the functions of discharging slurry and wastewater; however, it should be noted that the drain port is closed during normal production and is only opened for pre-start cleaning and shutdown maintenance.

[0030] In some embodiments of the present invention, a bottom agitator is provided at the bottom of the lower end cap.

[0031] In some embodiments of the present invention, a delivery pump is provided on the main cleaning pipe.

[0032] In some embodiments of the present invention, a shut-off valve is provided on the cleaning solvent pipeline; and / or, a shut-off valve is provided on the cleaning branch; and / or, a shut-off valve is provided on the slurry branch; and / or, a shut-off valve is provided on the first branch; and / or, a shut-off valve is provided on the second branch; and / or, a shut-off valve is provided on the third branch; and / or, a shut-off valve is provided on the return branch; and / or, a slurry pump is provided on the slurry main pipe.

[0033] In some embodiments of the present invention, a first blind flange is provided at the end of the cleaning main pipe away from the delivery pump; a second blind flange is provided at the end of the return main pipe away from the separator. During workshop maintenance, the first and second blind flanges can be removed to clean the dead zones of the cleaning main pipe and the return main pipe, reducing the amount of solids retained in the cleaning main pipe or the return main pipe.

[0034] In this embodiment, all connecting pipelines of the devices are equipped with shut-off valves that automatically control the flow of the pipelines. By developing a corresponding automatic control program, the switching and operation of the above five working states can be automatically realized. The automatic control program is common knowledge in the art and is operated using conventional methods in the field.

[0035] A second aspect of the present invention is to provide a cleaning method for reducing solid blockage in oxalamide production equipment, the method comprising the following steps:

[0036] (1) The cleaning solvent is sequentially transported to the separation tank via the cleaning solvent pipeline, the main cleaning pipeline, and the second branch; the cleaning solvent in the separation tank is output to the main cleaning pipeline via the cleaning branch, and distributed to the first branch and / or the third branch by the main cleaning pipeline, so that the cleaning solvent flows through the equipment to be cleaned on the first branch and / or the pipeline to be cleaned on the third branch for cleaning, to obtain the cleaning return liquid, and the cleaning return liquid is returned to the separation tank via the return main pipeline;

[0037] (2) The solution in the separation tank is separated to obtain solvent and sediment;

[0038] (3) The solvent is fed back to the cleaning manifold for subsequent cleaning operations; the sediment is stirred and mixed into a slurry and transported to the slurry manifold for subsequent production processes.

[0039] In some embodiments of the present invention, in step (2), the separation process is a static operation.

[0040] In some embodiments of the present invention, a separation tank cleaning step is also included. In the separation tank cleaning step, the operation of step (1) is paused, and the cleaning solvent flows into the separation tank in sequence through the cleaning main pipe and the second branch to rinse the separation tank. The reflux liquid after rinsing is reused.

[0041] As described above, the cleaning system and method for reducing solid blockage in the oxalamide production process of the present invention have the following beneficial effects:

[0042] This application, by setting up multiple parallel first branches, enables the simultaneous cleaning of multiple pieces of equipment, significantly shortening the overall cleaning time and improving the operating efficiency of the production unit. Simultaneously, by using a return main pipe to collect the cleaning return liquid, and then separating the solvent in a separator before supplying it back to the cleaning main pipe, a closed-loop recycling of the cleaning solvent is achieved. This reduces the amount of fresh solvent needed, lowers cleaning costs, and reduces waste liquid discharge, meeting environmental protection requirements. Furthermore, the system has a simple structure and a reasonable pipeline layout, facilitating installation and maintenance. Attached Figure Description

[0043] Figure 1 The diagram shows a cleaning system for reducing solid blockage in the oxalamide production process of this invention.

[0044] Component designation explanation

[0045] 1. Cleaning solvent pipeline; 2. Cleaning main pipe; 21. Transfer pump; 3. Branch pipe assembly; 31. First branch; 32. Second branch; 33. Third branch; 34. Return manifold; 35. Return pump; 4. Return main pipe; 41. Return branch; 5. Separator; 51. Upper head; 52. Cylinder; 53. Lower head; 54. Drainage pipeline; 55. Bottom agitator; 56. Cleaning branch; 57. Slurry branch; 6. Slurry main pipe; 61. Slurry pump; 7. Nozzle; 8. Equipment to be cleaned; 81. Vertical storage tank; 82. Horizontal storage tank; 83. Reactor; 9. Pipeline to be cleaned. Detailed Implementation

[0046] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, equipment, and materials similar to or equivalent to those described, used, and materials in the embodiments of this invention may be used to implement this invention.

[0047] This invention provides a cleaning system for reducing solid blockage in oxalamide production equipment, such as... Figure 1 As shown, the system includes a cleaning solvent pipeline 1, a cleaning main pipeline 2, branch pipelines 3, a return main pipeline 4, a return device, and a slurry main pipeline 6. The inlet end of the cleaning main pipeline 2 is connected to the cleaning solvent pipeline 1. The branch pipelines 3 include multiple parallel first branches 31 and multiple parallel second branches 32. Each first branch 31 is equipped with a corresponding device 8 to be cleaned, and the inlet end of each first branch 31 is connected to the cleaning main pipeline 2. The return main pipeline 4 is used to collect the cleaning return liquid flowing out of each first branch 31. The return device includes at least one separation tank 5, which is connected to the return main pipeline 4, the cleaning main pipeline 2, and the slurry main pipeline 6. The cleaning solvent in the cleaning solvent pipeline 1 flows into the cleaning main pipeline 2, then flows from the cleaning main pipeline 2 to the second branch 32, and then enters a separation tank 5 for filling. When the equipment 8 to be cleaned needs to be cleaned, the cleaning solvent in the separation tank 5 is fed into the cleaning main pipe 2, and then distributed to each of the first branch pipes 31. The cleaning solvent flows through the equipment 8 to be cleaned on each of the first branch pipes 31, cleaning it. After cleaning, the resulting cleaning return liquid flows through each of the first branch pipes 31 into the return main pipe 4, which then transports the cleaning return liquid to another separation tank 5. The separation tank 5 separates the cleaning return liquid into cleaning solvent and sediment. The separated cleaning solvent is returned to the cleaning main pipe 2 for recycling, and the separated sediment is stirred and mixed into a slurry, which is then output through the slurry main pipe 6 for subsequent production processes.

[0048] A shut-off valve is provided on the cleaning solvent pipeline 1 to control the connection of the cleaning solvent pipeline 1;

[0049] The main cleaning pipe 2 is equipped with a delivery pump 21 and a shut-off valve. The delivery pump 21 is used to deliver the cleaning solvent on the main cleaning pipe 2 to the branch pipe device 3, and the shut-off valve is used to control the connection of the main cleaning pipe 2.

[0050] The first branch line 31 includes an inlet branch pipe and an outlet branch pipe. One end of the inlet branch pipe is connected to the main cleaning pipe 2, and the other end is connected to the inlet of the equipment 8 to be cleaned; one end of the outlet branch pipe is connected to the outlet of the equipment 8 to be cleaned, and the other end is connected to the return main pipe 4. Both the inlet branch pipe and the outlet branch pipe are equipped with shut-off valves, which are automatic control valves used to open and close the corresponding pipelines, thereby facilitating automatic control of the cleaning process.

[0051] A nozzle is connected to the end of the inlet branch pipe. The nozzle is located inside the non-pipeline cleaning equipment 8.

[0052] The equipment 8 to be cleaned can be a vertical storage tank 81, a horizontal storage tank 82, or a reactor 83, and each of the equipment 8 to be cleaned is respectively installed on the corresponding first branch 31. To control the on / off state of each first branch 31, a shut-off valve is installed on each first branch 31. A return manifold 34 is installed between the first branch 31 and the return main 4. The inlet end of the return manifold 34 is connected to the outlet end of each first branch 31, and the outlet end of the return manifold 34 is connected to the return main 4, for collecting the cleaning return liquid flowing out of each first branch 31. A return pump 35 is installed on the return manifold 34 for pumping the cleaning return liquid in the return manifold 34 to the return main 4. After the equipment 8 to be cleaned is cleaned, the resulting cleaning return liquid is sequentially transported to the separation tank 5 through the return manifold 34 and the return main 4 for subsequent stirring and separation operations. After the cleaning device 8 has completed cleaning, the feeding and discharging of the cleaning device 8 are controlled by the shut-off valves corresponding to each of the cleaning devices 8.

[0053] Separation tank 5 and transfer pump 21 are either independently located in a compartment or integrated with the hot water supply system. The main cleaning pipe 2 and return main pipe 4 can be mounted on pipe racks, resulting in a more aesthetically pleasing piping layout for the entire production system. The cleaning piping configuration for the equipment to be cleaned 8 is identical to that for utilities, achieving a staggered and orderly arrangement.

[0054] When pipe cleaning is required, the branch pipe device 3 further includes a third branch 33. A pipe 9 to be cleaned is installed on the third branch 33. The inlet end of the third branch 33 is connected to the main cleaning pipe 2, and the outlet end of the third branch 33 is connected to the return main pipe 4. A shut-off valve is installed on the third branch 33 to control its on / off state. During cleaning, the cleaning solvent in the main cleaning pipe 2 enters the third branch 33 through its inlet end, flows through the pipe 9 to be cleaned, and carries the oxalamide generated during cleaning to form a cleaning return liquid, which flows into the return main pipe 4 from the outlet end of the third branch 33. After the pipe 9 to be cleaned is cleaned, the shut-off valve on the third branch 33 controls the feeding and discharging of the pipe 9.

[0055] A slurry pump 61 is installed on the slurry main pipe 6. The slurry pump 61 is used to transport the slurry output from the separation tank 5 to the subsequent production process through the slurry main pipe 6.

[0056] The reflux device includes 2 to 5 separation tanks 5. Preferably, the reflux device includes 2 separation tanks 5, specifically a first separation tank 5a and a second separation tank 5b. The first separation tank 5a and the second separation tank 5b are arranged in parallel and serve as backups for each other.

[0057] Specifically, when the cleaning solvent in the first separation tank 5a is used to clean the equipment 8 to be cleaned, the resulting reflux liquid is returned to the second separation tank 5b; when the cleaning solvent in the second separation tank 5b is used to clean the equipment 8 to be cleaned, the resulting reflux liquid is returned to the first separation tank 5a. While the first separation tank 5a is in cleaning operation mode, the second separation tank 5b can simultaneously perform slurry extraction operation; conversely, while the second separation tank 5b is in cleaning operation mode, the first separation tank 5a can also simultaneously perform slurry extraction operation. This mutually redundant configuration ensures that the cleaning device can continuously meet the cleaning needs of the production unit, effectively avoiding the problem of insufficient cleaning capacity leading to inability to clean normally, thus affecting the production process. The cleaning solvent can flow bidirectionally between the first separation tank 5a and the second separation tank 5b. Specifically, when the cleaning solvent level in the first separator 5a is high (i.e., the filling volume is large), the cleaning solvent flows from the first separator 5a through the cleaning main pipe 2 and the second branch pipe 32, and then flows back into the second separator 5b; conversely, when the cleaning solvent level in the second separator 5b is high, the cleaning solvent flows from the second separator 5b through the cleaning main pipe 2 and the second branch pipe 32, and then flows back into the first separator 5a. For ease of explanation, subsequent embodiments will be described using the case where the first separator 5a contains a large amount of cleaning solvent as an example.

[0058] The separation tank 5 includes an upper end cap 51, a cylinder 52, and a lower end cap 53, arranged sequentially from top to bottom and integrally formed. A reflux branch 41 is provided between the separation tank 5 and the reflux main pipe 4. One end of the reflux branch 41 is connected to the outlet end of the reflux main pipe 4, and the other end is connected to the upper end cap 51 of the separation tank 5, for conveying the cleaning reflux liquid in the reflux main pipe 4 to the separation tank 5. A shut-off valve is provided on the reflux branch 41 to control its opening and closing. After cleaning, the cleaning reflux liquid generated flows through the reflux main pipe 4 to the reflux branch 41, and then flows into the separation tank 5 through the reflux branch 41 for subsequent static separation operations.

[0059] A slurry branch line 57 is connected between the separator 5 and the slurry main pipe 6. One end of the slurry branch line 57 is connected to the lower end cap 53 of the separator 5, and the other end is connected to the slurry main pipe 6. This branch line 57 is used to transport the slurry separated from the separator 5 to the slurry main pipe 6. A shut-off valve is installed on the slurry branch line 57 to control its opening and closing. After separation, the separated slurry flows through the lower end cap 53 into the slurry branch line 57, and then into the slurry main pipe 6 for subsequent production processes.

[0060] A cleaning branch line 56 is connected between the separation tank 5 and the cleaning main pipe 2. One end of the cleaning branch line 56 is connected to the cylinder 52 of the separation tank 5, and the other end is connected to the cleaning main pipe 2. This branch line 56 is used to return the cleaning solvent separated from the separation tank 5 to the cleaning main pipe 2 for recycling in subsequent cleaning operations. A shut-off valve is installed on the cleaning branch line 56 to control its opening and closing. After separation, the separated cleaning solvent flows into the cleaning branch line 56 through the cylinder 52, and then back to the cleaning main pipe 2 for subsequent cleaning operations.

[0061] The lower end cap 53 of the separator 5 is also equipped with a drain pipe 54. One end of the drain pipe 54 is connected to the lower end cap 53, and the other end is connected to the drain system for discharging the waste liquid deposited at the bottom of the separator 5. A drain valve is installed on the drain pipe 54 to control its opening and closing. During draining, the waste liquid deposited at the bottom of the separator 5 flows through the lower end cap 53 into the drain pipe 54, and is then discharged through the drain pipe 54. The drain pipe 54 is only used when it is necessary to completely drain the material from the separator 5 and is generally kept closed.

[0062] The separation tank 5 is also equipped with a bottom stirrer 55. The bottom stirrer 55 is installed on the side of the lower end cap 53 of the separation tank 5, and includes a drive motor and a stirring shaft connected to the drive motor. The stirring shaft extends into the separation tank 5, and a shaft seal structure is provided between the stirring shaft and the wall of the lower end cap 53. A stirring paddle is installed at the end of the stirring shaft. The bottom stirrer 55 is used to stir the sediment and cleaning solvent in the separation tank 5 to form a slurry, facilitating the removal of the sediment from the separation tank 5. During the separation process, the bottom stirrer 55 is activated to stir the materials in the separation tank 5, ensuring thorough mixing of the cleaning solvent on the upper layer and the oxalamide sediment on the lower layer, forming a slurry. At this time, the slurry pump 61 is turned on, and the slurry is transported through the slurry branch pipe 57, the slurry main pipe 6, and the slurry pump 61 to the subsequent solid-liquid separation process. The bottom stirrer 55 and the slurry pump 61 are only activated to transport the slurry when the amount of oxalamide sediment in the separation tank 5 is large; otherwise, they are in standby mode.

[0063] When the separation tank 5 needs to be cleaned, the inlet end of the second branch 32 is connected to the main cleaning pipe 2, and the outlet end of the second branch 32 extends into the interior of the separation tank 5 to transport the cleaning solvent in the main cleaning pipe 2 into the separation tank 5. A shut-off valve is installed on the second branch 32 to control its opening and closing. A nozzle 7 is also installed at the outlet end of the second branch 32, located inside the separation tank 5, to spray the cleaning solvent onto the inner wall and internal components of the separation tank 5 in a jet form. The nozzle 7 is either pressure-type or spin-type, facilitating cleaning of the inner wall of the separation tank 5. During cleaning, the cleaning solvent in the main cleaning pipe 2 enters the second branch 32 through its inlet end and is transported to the nozzle 7 through its outlet end. The nozzle 7 then sprays the solvent onto the inner wall and internal components of the separation tank 5 for cleaning. The resulting cleaning reflux liquid undergoes further processing within the separation tank 5.

[0064] The end of the cleaning main pipe 2 away from the transfer pump 21 is provided with a first blind flange; the end of the return main pipe 4 away from the separation tank 5 is provided with a second blind flange. During workshop maintenance, the first and second blind flanges can be removed to clean the dead zones of the cleaning main pipe 2 and the return main pipe 4, reducing the amount of solids retained in the cleaning main pipe 2 or the return main pipe 4.

[0065] The following examples all employ a cleaning system designed to reduce solid blockage in the oxalamide production process.

[0066] Before cleaning in the following embodiments, the initial state of the system is as follows: all bottom agitators, delivery pumps, slurry pumps, reflux pumps, and all shut-off valves are in the closed state.

[0067] Example

[0068] Example 1

[0069] This embodiment provides a cleaning method for reducing solid blockage in oxalamide production equipment, comprising the following steps:

[0070] (1) Start the delivery pump, and sequentially open the shut-off valves on the cleaning solvent pipeline, the main cleaning pipeline, and the second branch. The cleaning solvent is delivered to the main cleaning pipeline through the cleaning solvent pipeline, and then introduced into the second branch through the main cleaning pipeline. The cleaning solvent is then introduced into the first separation tank and the second separation tank through the corresponding second branch for filling. The filling volume of the cleaning solvent in the first separation tank is 70-80%, and the filling volume of the cleaning solvent in the second separation tank is 40-50%.

[0071] (2) When it is necessary to clean the equipment to be cleaned, open the shut-off valve on the cleaning branch corresponding to the first separation tank and the shut-off valve on the first branch of the equipment to be cleaned. The cleaning solvent is transported to the cleaning main pipe through the cleaning branch at a flow rate of 1-3 m / s. Then, it is introduced into the first branch of the equipment to be cleaned through the cleaning main pipe to clean the equipment. At the same time, open the shut-off valve on the return manifold and start the return pump. The cleaning return liquid formed after cleaning flows into the return main pipe through the return manifold and is then transported to the return branch through the return main pipe. Open the shut-off valve on the return branch so that the cleaning return liquid flows into the corresponding second separation tank through the return branch.

[0072] (3) When there is a large amount of oxamide solids deposited in the second separator, turn on the bottom agitator of the second separator to fully mix the oxamide deposited in the second separator with the supernatant into a slurry that can be transported by the slurry pump. Transport the slurry to the slurry branch, open the shut-off valve on the branch, and at the same time start the slurry pump installed on the slurry main pipe so that the slurry enters the slurry main pipe through the slurry branch for use in subsequent production processes.

[0073] Example 2

[0074] This embodiment provides a cleaning method for reducing solid blockage in oxalamide production equipment, comprising the following steps:

[0075] (1) When the second separation tank needs to be cleaned, start the delivery pump, and sequentially open the shut-off valve on the cleaning branch corresponding to the first separation tank and the shut-off valve on the second branch. The cleaning solvent is delivered to the cleaning main pipe through the cleaning branch and then introduced into the second branch through the cleaning main pipe to clean the second separation tank connected to the second branch.

[0076] (2) When there is a large amount of oxamide solid deposited in the second separator, turn on the bottom agitator of the second separator to fully mix the oxamide deposited in the second separator with the supernatant into a slurry that can be transported by the slurry pump. Transport the slurry to the slurry branch, open the shut-off valve on the branch, and start the slurry pump installed on the slurry main pipe at the same time so that the slurry enters the slurry main pipe through the slurry branch for use in subsequent production processes.

[0077] Example 3

[0078] This embodiment provides a cleaning method for reducing solid blockage in oxalamide production equipment, comprising the following steps:

[0079] (1) When it is necessary to clean the pipeline to be cleaned, open the shut-off valve on the cleaning branch corresponding to the second separation tank and the shut-off valve on the third branch of the pipeline to be cleaned. The cleaning solvent is transported to the cleaning main pipe through the cleaning branch, and then introduced into the third branch of the pipeline to be cleaned through the cleaning main pipe to clean the pipeline. After the cleaning is completed, the cleaning return liquid formed after cleaning flows into the return main pipe through the third branch, and then is transported to the return branch through the return main pipe. Open the shut-off valve on the return branch to allow the cleaning return liquid to flow into the corresponding first separation tank through the return branch.

[0080] (2) When there is a large amount of oxamide solid deposited in the first separation tank, turn on the bottom agitator of the first separation tank to fully mix the oxamide deposited in the first separation tank with the supernatant to form a slurry that can be transported by the slurry pump. Transport the slurry to the slurry branch, open the shut-off valve on the branch, and start the slurry pump installed on the slurry main pipe at the same time so that the slurry enters the slurry main pipe through the slurry branch for use in subsequent production processes.

[0081] Normal operating conditions of the equipment to be cleaned: Under normal production conditions, the corresponding shut-off valves are opened according to the production progress to control the feeding and discharging of each piece of equipment to be cleaned. Specifically, the corresponding shut-off valve is opened when feeding or discharging vertical storage tanks; the corresponding shut-off valve is opened when feeding or discharging horizontal storage tanks; the corresponding shut-off valve is opened when feeding and reacting reactors; and the corresponding shut-off valve is opened when conveying slurry.

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A cleaning system for reducing solid blockage in oxalamide production equipment, characterized in that, The system includes a cleaning main pipe (2), a cleaning solvent pipeline (1), a branch pipe device (3), a return main pipe (4), and a return device; the inlet end of the cleaning main pipe (2) is connected to the cleaning solvent pipeline (1); the branch pipe device (3) includes multiple parallel first branches (31), each first branch (31) is provided with a corresponding device to be cleaned (8), the inlet end of each first branch (31) is connected to the cleaning main pipe (2), and the return main pipe (4) is used to collect the cleaning return liquid flowing out of each first branch (31); the return device includes at least one separation tank (5), the separation tank (5) is connected to the return main pipe (4) and the cleaning main pipe (2) respectively; the separation tank (5) is used to separate the solvent in the cleaning return liquid, and the solvent is returned to the cleaning main pipe (2).

2. The cleaning system according to claim 1, characterized in that: It also includes one or more of the following features: A1) The equipment (8) to be cleaned is selected from one or more of the following: vertical storage tank (81), horizontal storage tank (82), reactor (83), heat exchanger, flash tank, distillation column, washing column or solid-liquid separator; A2) The system also includes a slurry main pipe (6) and slurry branches (57) corresponding to each of the separation tanks (5). The slurry separated from the separation tanks (5) flows into the slurry main pipe (6) through the slurry branches (57) for subsequent production. A3) A return manifold (34) is provided between the first branch (31) and the return main (4), and the return manifold (34) is used to collect the cleaning return liquid flowing out of each first branch (31); A4) The branch pipe device (3) further includes a second branch (32) corresponding to each separation tank (5), the inlet end of each second branch (32) is connected to the cleaning main pipe (2), and the outlet end is located in the separation tank (5) for conveying cleaning solvent to the separation tank (5); A5) The branch pipe device (3) further includes a third branch (33), on which a pipe (9) to be cleaned is provided, and the third branch (33) is connected to the return main pipe (4); A6) A cleaning branch (56) is provided between the main cleaning pipe (2) and each of the separation tanks (5); A7) A reflux branch (41) is provided between the reflux main (4) and each of the separation tanks (5); A8) The separation tank (5) includes an upper end cap (51), a cylinder (52) and a lower end cap (53) arranged sequentially from top to bottom and integrally formed. A9) The main cleaning pipe (2) is equipped with a delivery pump (21).

3. The cleaning system according to claim 2, characterized in that: It also includes one or more of the following features: In feature A8), the second branch (32) is connected to the upper end cap (51); In feature A8), the cleaning branch (56) is disposed on the side of the cylinder (52); In feature A8), the slurry branch (57) is located on the lower end cap (53). In feature A8), the return branch (41) is connected to the upper end cap (51); In feature A8), the bottom of the lower end cap (53) is connected to a sewage pipe (54); the waste liquid separated by the separation tank (5) is output through the sewage pipe (54); In feature A8), the bottom of the lower end cap (53) is provided with a bottom stirrer (55).

4. The cleaning system according to claim 2, characterized in that: In feature A3), a reflux pump (35) is provided on the reflux manifold (34).

5. The cleaning system according to claim 2, characterized in that: In feature A4), the outlet end of the second branch (32) is connected to a nozzle (7) for cleaning the separation tank (5).

6. The cleaning system according to claim 2, characterized in that: A shut-off valve is provided on the cleaning solvent pipeline (1); and / or, a shut-off valve is provided on the cleaning branch (56); and / or, a shut-off valve is provided on the slurry branch (57); and / or, a shut-off valve is provided on the first branch (31); and / or, a shut-off valve is provided on the second branch (32); and / or, a shut-off valve is provided on the third branch (33); and / or, a shut-off valve is provided on the return branch (41); and / or, a slurry pump (61) is provided on the slurry main pipe (6).

7. The cleaning system according to claim 2, characterized in that: The reflux device includes 2-5 separation tanks (5).

8. A cleaning method for reducing solid blockage in oxalamide production equipment, characterized in that: The method includes the following steps: (1) The cleaning solvent is sequentially transported to the separation tank via the cleaning solvent pipeline, the main cleaning pipeline, and the second branch; the cleaning solvent in the separation tank is output to the main cleaning pipeline via the cleaning branch, and distributed to the first branch and / or the third branch by the main cleaning pipeline, so that the cleaning solvent flows through the equipment to be cleaned on the first branch and / or the pipeline to be cleaned on the third branch for cleaning, to obtain the cleaning return liquid, and the cleaning return liquid is returned to the separation tank via the return main pipeline; (2) The solution in the separation tank is separated to obtain solvent and sediment; (3) The solvent is fed back to the cleaning manifold for subsequent cleaning operations; the sediment is stirred and mixed into a slurry and transported to the slurry manifold for subsequent production processes.

9. The cleaning method according to claim 8, characterized in that: In step (2), the separation process is a static operation.

10. The cleaning method according to claim 8, characterized in that: It also includes a separation tank cleaning step, in which the operation of step (1) is paused, and the cleaning solvent flows continuously into the separation tank through the main cleaning pipe and the second branch to rinse the separation tank. The reflux liquid after rinsing is reused.

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