A spiral on-line automatic cleaning type reboiler

Abstract

The present application relates to a kind of spiral online automatic cleaning type reboiler, including reboiler, circulating pump and intelligent numerical control cabinet;The tube pass input end of reboiler is connected with the output end of circulating pump, the input end of circulating pump is connected with the first position of separation tower, and the tube pass output end of reboiler is connected with the second position of reboiler;The tube pass of reboiler includes multiple heating tubes, steel wire cleaning spiral is arranged in each described heating tube;Intelligent numerical control cabinet is connected with the communication of control circulating pump, and the working frequency of circulating pump is controlled to target threshold value based on preset program by intelligent numerical control cabinet, steel wire cleaning spiral outputs enough fluid momentum, drives steel wire cleaning spiral to rotate fully in heating tube.Compared with prior art, the present application has the advantages of convenient disassembly and replacement, high cleaning efficiency, long online period, no leakage and safety risk caused by movement or bearing, can maintain process condition without switching, relatively low cost and many other advantages, and has achieved application performance and significant advantages in industrial application.

Description

Technical Field

[0001] This invention relates to a reboiler, and more particularly to a spiral online automatic cleaning reboiler. Background Technology

[0002] In my country's petroleum, chemical, rubber, plastics, chemical fiber, and food industries, reboilers are crucial equipment in process systems. They revaporize the liquid material at the bottom of distillation and rectification columns, enabling heat and mass transfer between the vapor and liquid phases. With increasing operating time, scale buildup easily occurs, leading to reduced heat exchange efficiency, increased fluid resistance, decreased production efficiency, increased production costs, and even safety hazards. Therefore, reboiler cleaning has become an essential issue. Common descaling methods include mechanical descaling (such as high-pressure water jets), alkaline washing (boiling), and acid washing. These methods all require shutdown, making descaling time-consuming, labor-intensive, and causing economic losses to the plant. Furthermore, the abnormal process conditions during start-up and shutdown for descaling can easily generate waste gas and liquid, posing a significant safety risk and making it a challenge for process industries requiring long-term stable and efficient production. Moreover, the scale inside the reboiler heating tubes is mostly carbonized coke, with a complex chemical composition, making it difficult to acid wash like calcium and magnesium scale, and high-pressure water jet cleaning is also challenging.

[0003] The existing technologies are as follows: an online cleaning method for a steam reboiler in a desulfurization system (Wang Chunye, Liu Zhiping, et al., Ansteel Co., Ltd., applied for in 2022) involves heating and steaming the steam reboiler; and a high-efficiency descaling reboiler, which is a traditional descaling method. (CN202123073231.X Hubei Yili Petrochemical Equipment) uses in-situ circulating cleaning fluid; a reboiler coking material convection cleaning auxiliary device (Ding Jinbo, Henan Lvwo Environmental Protection Engineering Co., Ltd. CN202123374184.2) allows for size replacement by disassembling brushes, nozzles, connecting plates, and electric telescopic rods to perform shutdown cleaning of reboilers of different diameters. This technology is expensive, has many moving parts, a high failure rate, and is cumbersome to disassemble and assemble; a horizontal reboiler non-stop descaling device (Wang Xiaoyong, Anhui Ante Food Co., Ltd. CN201610791020.4) uses high-pressure water jet descaling; this technology is complex, expensive, difficult to operate and maintain, and has low reliability. The patent application with application number 201520248409.5 discloses a reboiler that can achieve efficient descaling. It uses ultrasound to achieve online descaling of the reboiler. However, the ultrasonic device requires a large investment and has many special requirements for the reboiler structure. The cleaning effect will also vary with the medium, which may have unpredictable effects on the composition and quality of the material. Although it has some effect in engineering applications, it mostly cannot meet the basic cleaning requirements. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a spiral online automatic cleaning reboiler. This technology has many advantages, such as convenient disassembly and replacement, high cleaning efficiency, long online cycle, no leakage and safety risks caused by movement or bearings, maintenance of process conditions without switching, and relatively low cost. It has achieved a major breakthrough in industrial applications.

[0005] The objective of this invention can be achieved through the following technical solutions: This invention provides a spiral online automatic cleaning reboiler, including a reboiler, a circulating pump, and an intelligent CNC cabinet; The tube-side input end of the reboiler is connected to the output end of the circulating pump, the input end of the circulating pump is connected to the first position of the separation tower, and the tube-side output end of the reboiler is connected to the second position of the reboiler. The reboiler tube side includes multiple heating tubes, and each heating tube is equipped with a steel wire cleaning spiral. The intelligent CNC cabinet is communicatively connected to the control circulation pump. Based on a preset program, the intelligent CNC cabinet controls the working frequency of the circulation pump to the target threshold, outputting sufficient fluid momentum toward the steel wire cleaning spiral, driving the steel wire cleaning spiral to rotate fully in the heating tube, thereby achieving self-cleaning of the heating tube.

[0006] Furthermore, the tube side of the reboiler also includes a cleaning head located at the inlet end of the heating tube, with the end of the steel wire cleaning spiral confined to the cleaning head, so that the steel wire cleaning spiral can only rotate axially.

[0007] Furthermore, the cleaning head includes a fixed pipe section placed inside the inlet end of the heating tube, and the fixed pipe section is provided with a backstop wing, which is anchored to the heating tube.

[0008] Furthermore, the axial height H2 of the fixed pipe section is 1.2 to 2.0 times the inner diameter of the heating pipe.

[0009] Furthermore, the cleaning head also includes a bow-back frame placed outside the heating tube. The bow-back frame is connected to the fixed tube section. The cross-section of the bow-back frame is semi-circular. The axial height H1 of the bow-back frame is 1.0 to 2.0 times the inner diameter of the heating tube.

[0010] Furthermore, the cleaning head also includes an end face bearing connected to the bow frame, the end of the steel wire cleaning spiral is movably inserted into the inner wall of the end face bearing, and the hook of the steel wire cleaning spiral extends out of the inner wall of the end face bearing in the form of a right-angle bend.

[0011] Furthermore, the inner wall of the end face bearing is provided with 1 to 3 vibration reduction grooves parallel to the axial direction. The width and depth of the vibration reduction grooves are both less than 0.85 times the diameter of the steel wire cleaning spiral.

[0012] Furthermore, the tube side of the reboiler also includes a cleaning machine tailstock located at the outlet end of the heating tube, and the tail end of the steel wire cleaning spiral is movably limited within the inner cavity of the cleaning machine tailstock.

[0013] Furthermore, the tail end of the steel wire cleaning spiral is provided with an elliptical ring, and the inner cavity of the cleaning machine tail frame is provided with a vibration deceleration slot.

[0014] Furthermore, the intelligent CNC cabinet controls the rotation frequency of the circulating pump based on the temperature difference ΔT between the two ends of the tube, and divides multiple temperature ranges based on the size of the temperature difference ΔT to correspond to different working rotation frequencies, so that the temperature range increases proportionally to the working rotation frequency of the circulating pump.

[0015] The intelligent numerical control concept of this invention patent is as follows: The radial vibration intensity of the wire cleaning auger is basically proportional to the momentum (the product of velocity and density) of the fluid inside the heating tube. Therefore, for simplicity, the following description will use the concept of the velocity equivalent to water density, i.e., the water equivalent velocity. The radial vibration intensity of the wire cleaning auger determines the strength level of the automatic cleaning capability.

[0016] The working medium in reboilers is mostly less dense than water, and the design value for the water equivalent flow rate of the heating tubes is generally not high. Therefore, the circulating fluid inside the heating tubes can only drive the steel wire cleaning spiral to vibrate in the radial direction for continuous cleaning and scale prevention, but cannot drive the steel wire cleaning spiral to rotate continuously. As a result, the intensity of automatic cleaning is not high enough, and there is a problem of very uneven circumferential cleaning.

[0017] To this end, the intelligent CNC cabinet is specially designed with a periodic acceleration frequency wave curve. By digitally controlling the frequency of the current peak period of the circulating pump motor, the circulation speed of the heating tube is increased to a level sufficient to drive the steel wire cleaning spiral to rotate reliably and continuously, thereby achieving periodic, high-intensity, and circumferentially uniform automatic cleaning.

[0018] To prevent wear on the heating element that might be induced by the continuous rotation of the wire cleaning spiral, the neck of the hook head of the wire cleaning spiral is subjected to vibration reduction grooves within the cleaning head, similar to a speed reducer. The elliptical ring at the tail end of the wire cleaning spiral is subjected to vibration reduction slots within the cleaning machine tail frame, also similar to a speed reducer. Under the combined vibration reduction action at both ends, the wire cleaning spiral can vibrate more intensely in the radial direction while reliably and slowly rotating continuously for uniform cleaning, thus completely eliminating the minimum PV value conditions necessary for mechanical wear.

[0019] The intelligent CNC cabinet is designed with several different accelerated flow frequency wave curves.

[0020] First, there are reboilers designed for different water equivalent flow rates. For reboilers designed for medium water equivalent flow rates, the peak flow rate generally only needs to be increased by 10%; for reboilers designed for low water equivalent flow rates, the peak flow rate generally needs to be increased by 20% to meet the requirements.

[0021] Secondly, reboilers with different fouling rates require different levels of automatic cleaning intensity. This is mainly achieved by adjusting the peak interval and lengthening the peak segment. Intensification can also be achieved by increasing the velocity difference between the peaks and troughs.

[0022] The automatic switching between different cleaning intensities is achieved by the intelligent CNC cabinet using temperature sensor signals from the reboiler heating chamber, based on calculations according to the fundamental equation of heat transfer. The technical principle is the fundamental equation of heat transfer: Q = K × ΔT × A, where Q represents the heating power of the reboiler, K represents the overall heat transfer coefficient, ΔT represents the temperature difference, and A represents the heat transfer area. Therefore, if the initial automatic cleaning intensity level is insufficient during operation, the dirt thickness will slowly increase, and the overall heat transfer coefficient K will decrease accordingly. The temperature difference ΔT, formed by the data sent by the temperature sensor series, will inevitably increase. When the increase in ΔT reaches a certain predetermined value (generally 10% in design), the intelligent CNC cabinet will automatically increase the automatic cleaning intensity to a higher level and continue operation.

[0023] Compared with the prior art, the present invention has the following technical advantages: This invention proposes a safe, reliable, and controllable new technology. Compared with some existing technologies, this technology has many advantages, such as convenient disassembly and replacement, high cleaning efficiency, long online cycle, no leakage or safety risks caused by movement or bearings, maintenance of process conditions without switching, and relatively low cost. It has already achieved significant advantages in industrial applications.

[0024] In this technical solution, the fouling inside the reboiler heating tubes is continuously and automatically cleaned during normal production operation by utilizing the flow energy of the heating fluid itself through the radial vibration of a CNC automatic cleaning spiral within the heating tubes. A periodic CNC-controlled wave crest is superimposed to accelerate the flow, resulting in more intense vibration cleaning by the cleaning spiral while maintaining slow rotation, achieving effective circumferential uniform cleaning and reliably preventing wear. The intensity level of this uniform, effective, and enhanced automatic cleaning can be easily digitally designed and adjusted in real-time during operation according to different process conditions and the actual needs of different equipment fouling levels. Because this automatic cleaning requires no external power source, its structure is very simple and reliable. It not only provides continuous automatic cleaning and scale prevention, but the spiral also has a certain convective heat transfer enhancement function, ensuring the reboiler always operates stably and efficiently. Attached Figure Description

[0025] Figure 1 This is a general diagram of an intelligent spiral online automatic cleaning reboiler according to the present invention patent.

[0026] Figure 2 This is a diagram of the assembly structure of the cleaning spiral inside the heating tube.

[0027] Figure 3 This is an example of the accelerated flow frequency wave curve of a reboiler with a flow rate in water equivalent.

[0028] Figure 4 This is an example of a high-frequency wave curve for a low-flow-rate reboiler with water equivalent.

[0029] In the diagram: 01 Separation Tower 02 Flow Meter 03 Circulation Pump 04 Intelligent CNC Cabinet 05 Circulation Inlet Pipe 06 Cleaning Machine Head 07 Steel Wire Cleaning Spiral 08 Heating Pipe 09 Reboiler 10 Heating Steam Inlet Pipe 11 Elliptical Ring 12 Cleaning Machine Tail Frame 13 Temperature Sensor 14 Circulation Outlet Pipe 15 Spiral Hook 16 End Face Bearing 17 Vibration Reduction Groove 18 Bow Back Frame 19 Flange 20 Anti-reverse Wing 21 Fixed Pipe Section 22 Assembly Adjustment Joint 23 Vibration Reduction Joint 24 Tail Frame Pipe. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0031] The spiral online automatic cleaning reboiler in this solution mainly consists of the reboiler (09), intelligent CNC cabinet (04), circulating pump (03), heating element (08), cleaning head (06), steel wire cleaning spiral (07), cleaning tail frame (12), and temperature sensor (13). See also... Figure 1 and 2 .

[0032] The automatic cleaning mechanism consists of an intelligent CNC cabinet 04, a circulating pump 03, a heating tube 08, a cleaning head 06, a steel wire cleaning spiral 07, and a cleaning tail frame 12.

[0033] The cleaning head 06, with the aid of the anti-reverse fin 20, securely installs the fixed pipe section 21 at the material inlet end of the heating pipe 08. The height H2 of the fixed pipe section 21 is 1.2 to 2.0 times the inner diameter of the heating pipe 08. The cross-section of the arched frame 18 is semi-circular, and its axial height H1 is 1.0 to 2.0 times the inner diameter of the heating pipe, facilitating installation and reducing inlet flow resistance. At the head is an end-face bearing 16 structure, with 1 to 3 vibration reduction grooves 17 designed on the inner wall. The width and depth of the vibration reduction grooves 17 are both less than 0.85 times the diameter of the steel wire in the steel wire cleaning spiral 07.

[0034] The steel wire cleaning spiral 07 is made of corrosion-resistant stainless steel wire, titanium wire, or alloy wire. The wire diameter is 1.0~2.0mm. The outer diameter of the steel wire cleaning spiral 07 differs from the inner diameter of the heating tube 08 by 4~7mm. The pitch of the steel wire cleaning spiral 07 is 0.8~1.5 times the inner diameter of the heating tube 08. The tail end of the steel wire cleaning spiral 07 has an elliptical ring structure, with its major axis parallel to the center line of the heating tube 08, but not on the same center line. This ensures that the elliptical ring 11 can contact the vibration deceleration slot 23 on the tail frame 12 of the cleaning machine when the steel wire cleaning spiral 07 rotates, thereby enhancing vibration cleaning, suppressing rotational speed, and preventing wear. When the steel wire cleaning spiral 07 is in operation, it is impacted by the fluid inside the heating tube 08, and its total length after elastic elongation is the same as the length of the heating tube 08.

[0035] During operation, the steel wire cleaning spiral 07 continuously vibrates and cleans in the radial direction. This vibration strongly agitates the boundary layer on the inner wall of the heating tube 08, enhances the convective heat transfer process inside the heating tube 08, effectively reduces the temperature of the inner wall of the heating tube 08, avoids excessively high wall temperature that accelerates carbonization, and significantly reduces the rate of scale formation, thus having a certain scale-inhibiting and scale-resistant effect.

[0036] The cleaning machine tailstock 12 is interference-fitted onto the outlet end of the heating tube 08. The cleaning machine tailstock 12 is designed with important vibration deceleration slots 23. Generally, one or two vibration deceleration slots 23 are designed. The width of the vibration deceleration slot is 1.0~2.0mm. The length needs to be relatively large, generally 20~30mm, to ensure that the steel wire cleaning spiral 07 can adapt to the axial position changes of the elliptical ring during elastic expansion and contraction.

[0037] The radial vibration intensity of the wire cleaning spiral 07 is basically proportional to the momentum (the product of velocity and density) of the fluid inside the heating tube 08. The radial vibration intensity of the wire cleaning spiral 07 determines the strength level of the automatic cleaning capability.

[0038] The working medium in reboiler 09 is mostly less dense than water, and the design value of the water equivalent circulation velocity in heating tube 08 is generally not high. Therefore, the circulating fluid in heating tube 08 can only drive the steel wire cleaning spiral 07 to vibrate in the radial direction for continuous cleaning and scale prevention, but cannot drive the steel wire cleaning spiral 07 to rotate continuously. As a result, the intensity of automatic cleaning is not high, and there is a problem of very uneven circumferential cleaning.

[0039] Therefore, in this technical solution, the intelligent CNC cabinet 04 is preloaded with a periodic acceleration frequency wave curve. Figure 3 , Figure 4 Control program. By digitally controlling the frequency of the peak period of the motor current of the circulating pump 03, the circulation speed of the heating tube 08 is increased to a level sufficient to drive the steel wire cleaning spiral 07 to rotate reliably and continuously, thereby achieving periodic, high-intensity, and circumferentially uniform automatic cleaning.

[0040] To prevent wear on the heating element 08 that might be induced by the continuous rotation of the steel wire cleaning spiral 07, the neck of the spiral hook 15 of the steel wire cleaning spiral 07 is subjected to vibration and deceleration by the vibration reduction groove 17 in the cleaning head 06, similar to the principle of a speed reducer. The elliptical ring 11 at the tail end of the steel wire cleaning spiral 07 is also subjected to vibration and deceleration by the vibration reduction slot 23 in the tail frame 12, similar to a speed reducer. Under the combined vibration and deceleration action at both ends, the steel wire cleaning spiral 07 can vibrate and clean more strongly in the radial direction, and can also reliably and slowly rotate continuously for uniform cleaning, thereby eliminating the minimum PV value condition necessary for mechanical wear.

[0041] When the wire cleaning spiral 07 rotates, the contact between the neck of the spiral hook 15 of the wire cleaning spiral 07 and the vibration deceleration groove 17 of the cleaning machine head 06, and the contact between the elliptical ring 11 at the tail end of the wire cleaning spiral 07 and the vibration deceleration slot 23 of the cleaning machine tail frame 12, together act as a deceleration plate, so that the wire cleaning spiral 07 can both strengthen vibration cleaning and firmly control its slow rotation, eliminating the PV value conditions that may cause mechanical wear.

[0042] The intelligent CNC cabinet 04 is designed with several automatic cleaning intensity levels and accelerated flow frequency wave curves. Based on the principle of heat transfer, the increase in dirt thickness, indirectly reflected by temperature sensor data, will inevitably lead to an increase in the heat transfer temperature difference ΔT. When the increase in ΔT reaches a certain predetermined value (generally 10% in the design), the intelligent CNC cabinet 04 will automatically increase the automatic cleaning intensity to a higher level for automatic cleaning.

[0043] First, there are reboilers 09 designed for different water equivalent flow rates. For reboilers 09 designed for medium water equivalent flow rates, the peak flow rate generally only needs to be increased by 10%; for reboilers 09 designed for low water equivalent flow rates, the peak flow rate generally needs to be increased by 20%. Second, reboilers 09 designed for different fouling rates require different levels of automatic cleaning intensity. This is mainly achieved by adjusting the peak interval time and the peak duration. Increasing the peak-to-trough flow rate difference can also enhance the cleaning effect.

[0044] The automatic cleaning intensity switching between different levels is achieved by the intelligent CNC cabinet 04 using signals from temperature sensors 13 within the reboiler 01 heating chamber, based on calculations using the fundamental equation of heat transfer. The technical principle is the fundamental equation of heat transfer: Q = K × ΔT × A, where Q represents the heating power of the reboiler 01, K represents the overall heat transfer coefficient, ΔT represents the temperature difference, and A represents the heating area of ​​the reboiler 01. Therefore, if the initial automatic cleaning intensity level is insufficient during operation, the dirt thickness will slowly increase, and the overall heat transfer coefficient K will decrease accordingly. Consequently, the temperature difference ΔT, formed by the data sent by the temperature sensors 13, will inevitably increase. When the increase in ΔT reaches a certain predetermined value (generally 10% in design), the intelligent CNC cabinet 04 will automatically increase the automatic cleaning intensity to a higher level and continue operation.

[0045] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A spiral online automatic cleaning reboiler, characterized in that, Including a reboiler (09), a circulating pump (03), and an intelligent CNC cabinet (04); The tube side input end of the reboiler (09) is connected to the output end of the circulating pump (03), the input end of the circulating pump (03) is connected to the first position of the separation tower (01), and the tube side output end of the reboiler (09) is connected to the second position of the separation tower (01). The reboiler (09) includes multiple heating tubes (08) in its tube side, and each heating tube (08) is provided with a wire cleaning spiral (07). The intelligent CNC cabinet (04) controls the working frequency of the circulating pump (03) to the target threshold, outputs sufficient fluid momentum toward the wire cleaning spiral (07), drives the wire cleaning spiral (07) to rotate fully in the heating tube (08), and realizes the self-cleaning of the heating tube (08); The tube side of the reboiler (09) also includes a cleaning head (06) located at the inlet end of the heating tube (08) and a cleaning tail frame (12) located at the outlet end of the heating tube (08). The cleaning head (06) includes a fixed pipe section (21) placed inside the inlet end of the heating tube (08), and the fixed pipe section (21) is provided with a backstop wing (20), which is anchored to the heating tube (08); The cleaning head (06) also includes an end face bearing (16) connected to the fixed pipe section (21). The end of the steel wire cleaning spiral (07) is movably inserted into the inner wall of the end face bearing (16), and the hook of the steel wire cleaning spiral (07) extends out of the inner wall of the end face bearing (16) in the form of a right-angle bend. The inner wall of the end face bearing (16) is provided with 1 to 3 vibration reduction grooves (17) parallel to the axial direction. The width and depth of the vibration reduction grooves (17) are both less than 0.85 times the diameter of the steel wire of the steel wire cleaning spiral (07). The tail end of the steel wire cleaning spiral (07) is located within the inner cavity of the cleaning machine tail frame (12), and the inner cavity of the cleaning machine tail frame (12) is provided with a vibration deceleration slot (23). The tail end of the steel wire cleaning spiral (07) is provided with an elliptical ring (11). The major axis of the elliptical ring (11) is parallel to the center line of the heating tube (08) but not on the same center line, so as to ensure that the elliptical ring (11) can contact the vibration deceleration joint (23) on the tail frame (12) of the cleaning machine when the steel wire cleaning spiral (07) rotates. When the steel wire cleaning spiral (07) is working, it is impacted by the fluid inside the heating tube (08), and its total length after elastic elongation is the same as the length of the heating tube (08); The intelligent CNC cabinet (04) controls the rotation frequency of the circulating pump (03) based on the temperature difference ΔT between the two ends of the tube, and divides multiple temperature ranges based on the size of the temperature difference ΔT to correspond to different working rotation frequencies, so that the temperature range increases proportionally to the working rotation frequency of the circulating pump (03). The intelligent CNC cabinet (04) is preloaded with a periodic acceleration frequency wave curve control program. By digitally controlling the frequency of the motor current peak period of the circulating pump (03), the circulation speed of the heating tube (08) is increased to a level sufficient to drive the steel wire cleaning spiral (07) to rotate reliably and continuously.

2. The spiral online automatic cleaning reboiler according to claim 1, characterized in that, The axial height H2 of the fixed pipe section (21) is 1.2 to 2.0 times the inner diameter of the heating pipe (08).

3. The spiral online automatic cleaning reboiler according to claim 1, characterized in that, The cleaning head (06) also includes a bow frame (18) placed outside the heating tube (08). The bow frame (18) is connected to the fixed tube section (21). The cross section of the bow frame (18) is semi-circular. The axial height H1 of the bow frame (18) is 1.0 to 2.0 times the inner diameter of the heating tube (08).

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