A multi-mode compatible delivery process for urea products

Abstract

This application discloses a multi-mode compatible conveying process for urea products, belonging to the field of urea product production technology. It includes using a booster compressor in an air separation unit to deliver compressed air to a pneumatic conveying device. An R=8D elbow is used at the bend in the conveying pipeline, and an auxiliary blowing valve is installed before the elbow to reduce conveying resistance. After the pneumatic conveying device stops, the auxiliary blowing main valve opens to a preset value to ensure the entire conveying system is under positive pressure, preventing air from entering the system. A pipeline vibrator is installed in the feed pipe of the pneumatic conveying device. Based on the main blowing pipeline, the conveying silo pump has two compressed air streams led out from the pressure reducing valve of the main blowing pipe. One stream is connected to the upper middle part of the silo pump, and the other is connected to the top of the silo pump. Through the blowing of these two auxiliary air streams in different directions, urea dust adhering to the walls is removed. This process does not change the original main structure of the packaging or the pipeline layout, has low construction costs, and can recover the investment within the first year of operation, making it suitable for promotion and application on existing equipment.

Description

Technical Field

[0001] This application belongs to the field of urea product manufacturing technology, specifically, it relates to a multi-mode compatible conveying process for urea products. Background Technology

[0002] The supporting packaging facilities for urea plants include small bag lines, ton bag lines, and bulk loading lines. As these facilities age and their packaging capacity declines, the urea granulation system will frequently shut down due to packaging line malfunctions or excessive material storage in the silos.

[0003] However, building a new packaging line is not feasible due to insufficient space, and replacing the current packaging equipment would require long-term production shutdowns due to high investment and construction time. Therefore, it is necessary to build a new pneumatic conveying device that can deliver directly to users near the urea plant via a high-angle belt, enabling flexible production adjustments, reducing the load on the packaging line, and decreasing the failure rate of the small package packaging line and the labor intensity of workers.

[0004] Pneumatic conveying systems are currently one of the fastest-growing and most practical devices for conveying solid particles or powders. They enable closed-loop conveying, reducing dust pollution and the risk of leakage. Compared to belt conveyors, they do not use motors and are more energy-efficient. However, this device has not been applied to urea products, mainly due to the unique physicochemical properties of urea. Urea is corrosive, readily absorbs moisture and clumps, and contains approximately 2% powder, which easily adheres to the inner walls of equipment and pipelines. After absorbing moisture, it sticks to the pipeline, causing blockages and forcing the conveyor system to stop. This particular conveying pipeline is approximately 500 meters long, and pipeline resistance is also a significant factor in blockage.

[0005] To address the above issues, a pneumatic conveying technology suitable for urea products needs to be designed, and it must be compatible, stable, and safe for use with packaging lines and bulk lines. Summary of the Invention

[0006] To address the aforementioned problems and technical deficiencies, this application adopts the following technical solution: a multi-mode compatible delivery process for urea products, comprising the following steps: Compressed air is delivered to the pneumatic conveying device via a booster compressor in an air separation unit. Use an R=8D elbow at the bend in the conveying pipeline and install a blow-off valve before the elbow to reduce conveying resistance; After the pneumatic conveying device stops, the main purging valve opens to a preset value to ensure that the entire conveying system is under positive pressure and to prevent air from entering the system. A pipe vibrator is installed in the feed pipe of the pneumatic conveying device to prevent the feed pipe from clogging and reduce the amount of urea product remaining before the first pneumatic valve. Based on the main blowing pipeline, the conveying silo pump has two compressed air lines leading out from the pressure reducing valve of the main blowing pipeline. One line is connected to the upper middle part of the silo pump, and the other line is connected to the top of the silo pump. The urea dust adhering to the wall is removed by blowing through the two auxiliary lines of air in different directions. The original bulk material discharge chute was equipped with a manual folding valve to switch between bulk material and pneumatic conveying systems; a pneumatic main discharge valve was then installed behind it, and a filter was installed after the pneumatic main discharge valve.

[0007] Preferably, the pressure of the compressed air is 0.6-0.8 MPaG, and the compressed air has been filtered through a molecular sieve to adsorb moisture, with a dew point below -20℃. The pressure at the top of the delivery chamber pump is set to be ≤ 125 kPaG of the main blowing air pressure as a predictive indicator for pipe blockage. If the predictive indicator is exceeded, a warning is issued. The feed rate of the silo pump is controlled between 300-900 kg per cycle, and adjusted according to the amount of compound fertilizer used.

[0008] Preferably, the blowing pressure of the blowing valve is ≥ 0.3 MPaG of the main blowing pipeline; According to the principles of pipeline installation, the pipeline gradually rises before the highest point and gradually decreases after the highest point.

[0009] Furthermore, some elbows of the pneumatic conveying device are connected to detachable elbows using flanges at the front and rear.

[0010] Furthermore, the pneumatic conveying device is equipped with a pressure interlock inside the silo pump. If the pressure exceeds the set threshold, the interlock will stop the machine and check for pipeline blockage.

[0011] Preferably, the pipe vibrator is installed near the main pipe at the first pneumatic valve of the pneumatic conveying feed pipe, and vibrates once every 5 seconds during each feeding.

[0012] Preferably, the terminal silo is equipped with an observation window so that any abnormalities such as material conveying pipe blockage or false alarms from the rotary level gauge can be resolved immediately to avoid accidents.

[0013] Furthermore, a pneumatic valve is installed on one bulk branch after the filter, and two pneumatic valves are installed on the other branch leading to the pneumatic conveying system. The main discharge valve and the bulk pneumatic valve are controlled separately on the sixth floor of the packaging building, isolated from the pneumatic valves of the pneumatic conveying system, to avoid material spillage caused by misoperation during the switching process.

[0014] Furthermore, the compressed air inlet and outlet pipes and material inlet and outlet pipes connected to the silo pump are equipped with flexible connections, and the upper feed pipe is forcibly fixed to the building wall to prevent the pipe from sagging.

[0015] Furthermore, a dedicated calibration platform is installed outside the silo pump to hold the calibration weights. The system is set to delay the feeding process by 5-10 seconds before opening the air inlet valve to begin conveying, and the weight measured in this static state is used as the scale measurement data.

[0016] Compared to existing technologies, the beneficial effects of this application are as follows: (1) This application, through modifications such as the flexible connection method of the pipeline, the setting of a dedicated metering platform, and the modification of the logic program, successfully passed the mandatory metering certification of the integrated metering scale of the silo pump and the scale, and realized the accurate metering of materials between companies; (2) The products conveyed by the pneumatic conveying device in this application reduce the urea packaging and storage links, relieve the pressure of urea packaging manpower shortage and urea inventory, reduce abnormal situations such as reduction and shutdown of urea unit caused by packaging problems, and enable the urea unit to operate safely, stably and efficiently. (3) This application only requires changing the original bulk feed pipeline and adding a pneumatic conveying device to be arranged in the open air outside the factory. It does not change the original main structure of the packaging and pipeline layout. The construction cost is low and the investment can be recovered in the same year. It is conducive to the promotion and application on the existing equipment. Attached Figure Description

[0017] In the attached diagram: Figure 1 This is a schematic diagram of the method steps in an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments. Generally, the components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0019] Example like Figure 1 As shown, a multi-mode compatible delivery process for urea products includes the following steps: Compressed air is delivered to the pneumatic conveying device via a booster compressor in an air separation unit. The compressed air pressure is 0.6-0.8 MPaG. The compressed air has been filtered through a molecular sieve to adsorb moisture, and the dew point is below -20℃. The pressure at the top of the delivery chamber pump is set to be ≤ 125 kPaG of the main blowing air pressure as a predictive indicator for pipe blockage. If the predictive indicator is exceeded, a warning will be issued. The feed rate of the silo pump is controlled between 300-900 kg per cycle, and adjusted according to the amount of compound fertilizer used.

[0020] Use an R=8D elbow at the bend in the conveying pipeline and install a blow-off valve before the elbow to reduce conveying resistance; The boosting pressure of the boosting valve is ≥ 0.3 MPaG of the main blow-up pipeline; According to the principles of pipeline installation, the pipeline gradually rises before the highest point and gradually decreases after the highest point.

[0021] The pneumatic conveying device uses flanges to connect the front and rear of some elbows, making them detachable.

[0022] After the pneumatic conveying device stops, the main purging valve opens to the preset value to ensure that the entire conveying system is under positive pressure, preventing air from entering the system and causing the powder adhering inside to stick to the wall. The pneumatic conveying device is equipped with a pressure interlock inside the silo pump. If the pressure exceeds the set threshold, the interlock will stop the machine and check for pipeline blockage.

[0023] A pipe vibrator is installed in the feed pipe of the pneumatic conveying device to prevent the feed pipe from clogging and reduce the amount of urea product remaining before the first pneumatic valve. The pipeline vibrator is installed near the main pipe at the first pneumatic valve of the pneumatic conveying feed pipe, and vibrates once every 5 seconds during each feeding.

[0024] Based on the main blowing pipeline, the conveying silo pump has two compressed air lines leading out from the pressure reducing valve of the main blowing pipeline. One line is connected to the upper middle part of the silo pump, and the other line is connected to the top of the silo pump. The urea dust adhering to the wall is removed by blowing through the two auxiliary lines of air in different directions. It can also solve the problem of unidirectional flow of the main air in the silo pump, which causes the material in the upper part to be suspended. When the main air is stopped, a certain amount of urea is left in the silo pump and cannot be sent out, resulting in inaccurate metering. The air intake of the two auxiliary lines just balances the pressure difference between the upper and lower parts, so that the urea is smoothly sent out of the silo pump and the metering is accurate.

[0025] The terminal silo is equipped with an observation window. When abnormal situations such as material conveying pipe blockage or false alarms from the rotary level gauge occur, they can be resolved immediately to avoid accidents.

[0026] The original bulk material discharge chute was equipped with a manual folding valve to switch between bulk material and pneumatic conveying systems; a pneumatic main discharge valve was then installed behind it, and a filter was installed after the pneumatic main discharge valve.

[0027] A pneumatic valve is installed on one bulk branch line after the filter, and two pneumatic valves are installed on the other branch line to the pneumatic conveying system. The main discharge valve and the bulk pneumatic valve are controlled separately on the sixth floor of the packaging building, isolated from the pneumatic valves of the pneumatic conveying system, to avoid material spillage caused by misoperation during the switching process.

[0028] Flexible connections were installed in the compressed air inlet and outlet pipes and the material inlet and outlet pipes connected to the pump, and the upper feed pipe was forcibly fixed to the building wall to prevent the pipe from sagging.

[0029] A dedicated calibration platform is set up outside the silo pump to hold the weights. The system is set to delay for 5-10 seconds after feeding before opening the air inlet valve to start conveying. The weight at this static state is used as the scale measurement data.

[0030] By adding two specially designed auxiliary air lines to the process pipelines, fittings, vibrators, pipe connections, and main blowing pipeline of the silo pump, the possibility of urea granular dust sticking to the walls and clogging the pipes is reduced. At the same time, by setting valve settings on the feed pipelines of the bulk and pneumatic conveying devices, the newly installed urea pneumatic conveying devices can be put into operation and stopped at any time with the packaging line and the bulk line without interference, enabling flexible production.

[0031] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A multi-mode compatible conveying process for urea products, characterized in that, Includes the following steps: Compressed air is delivered to the pneumatic conveying device via a booster compressor in an air separation unit. Use an R=8D elbow at the bend in the conveying pipeline and install a blow-off valve before the elbow to reduce conveying resistance; After the pneumatic conveying device stops, the main purging valve opens to a preset value to ensure that the entire conveying system is under positive pressure and to prevent air from entering the system. A pipe vibrator is installed in the feed pipe of the pneumatic conveying device to prevent the feed pipe from clogging and reduce the amount of urea product remaining before the first pneumatic valve. Based on the main blowing pipeline, the conveying silo pump has two compressed air lines leading out from the pressure reducing valve of the main blowing pipeline. One line is connected to the upper middle part of the silo pump, and the other line is connected to the top of the silo pump. The urea dust adhering to the wall is removed by blowing through the two auxiliary lines of air in different directions. The original bulk material discharge chute was equipped with a manual folding valve to switch between bulk material and pneumatic conveying systems; a pneumatic main discharge valve was then installed behind it, and a filter was installed after the pneumatic main discharge valve.

2. The multi-mode compatible transportation process for urea products according to claim 1, characterized in that, The pressure of the compressed air is 0.6-0.8 MPaG. The compressed air has been filtered through a molecular sieve to adsorb moisture, and its dew point is below -20℃. The pressure at the top of the conveying chamber pump is set to be ≤ 125 kPaG of the main blowing air pressure as a predictive indicator for pipe blockage. If the predictive indicator is exceeded, a warning will be issued. The feed rate of the silo pump is controlled between 300-900 kg per cycle, and adjusted according to the amount of compound fertilizer used.

3. The multi-mode compatible transportation process for urea products according to claim 1, characterized in that, The blowing pressure of the blowing valve is ≥ 0.3 MPaG of the main blowing pipeline; According to the principles of pipeline installation, the pipeline gradually rises before the highest point and gradually decreases after the highest point.

4. The multi-mode compatible transportation process for urea products according to claim 3, characterized in that, The pneumatic conveying device uses flanges to connect the front and rear of some elbows, making them detachable.

5. A multi-mode compatible transportation process for urea products according to claim 4, characterized in that, The pneumatic conveying device is equipped with a pressure interlock inside the silo pump. If the pressure exceeds the set threshold, the interlock will stop the machine and check for pipeline blockage.

6. The multi-mode compatible transportation process for urea products according to claim 1, characterized in that, The pipeline vibrator is installed near the main pipe at the first pneumatic valve of the pneumatic conveying feed pipe, and vibrates once every 5 seconds during each feeding.

7. The multi-mode compatible transportation process for urea products according to claim 1, characterized in that, The terminal silo is equipped with an observation window. When abnormal situations such as material conveying pipe blockage or false alarms from the rotary level gauge occur, they can be resolved immediately to avoid accidents.

8. A multi-mode compatible conveying process for urea products according to claim 5, characterized in that, One pneumatic valve is installed on one bulk branch after the filter, and the other branch goes to the pneumatic conveying system, which is equipped with two feed pneumatic valves. The main discharge valve and the bulk pneumatic valve are controlled separately on the sixth floor of the packaging building, isolated from the pneumatic valves of the pneumatic conveying system, to avoid material spillage caused by misoperation during the switching process.

9. A multi-mode compatible conveying process for urea products according to claim 8, characterized in that, The compressed air inlet and outlet pipes and material inlet and outlet pipes connected to the silo pump are equipped with flexible connections, and the upper feed pipe is forcibly fixed to the building wall to prevent the pipe from sagging.

10. A multi-mode compatible conveying process for urea products according to claim 9, characterized in that, The pump is equipped with a dedicated platform for placing calibration weights. The system is set to delay the feeding process by 5-10 seconds before opening the air inlet valve to begin conveying. The weight measured in this static state is used as the scale's measurement data.

Images