Energy-saving condensing device for liquid formaldehyde production

Abstract

This invention relates to the field of liquid formaldehyde production technology, and more particularly to an energy-saving condensation device for liquid formaldehyde production. The technical solution includes: a condenser with a first end cap and a second end cap at both ends, the first end cap having a medium inlet and a medium outlet. The condenser interior is axially divided into at least two interconnected high-pressure chambers. The condenser contains at least one set of rotatable condenser tubes, each with a driving structure for rotating under the action of a heat exchange medium. The condenser also includes a gas distribution-scraping assembly in contact with the surface of the condenser tubes. This assembly includes a gas distribution pipe and fins distributed axially along its axis, used to distribute the gas to be condensed onto the surface of the condenser tubes and scrape off surface condensate as the condenser tubes rotate, while simultaneously spraying airflow to blow the scraped condensate towards the inner wall of the condenser. This invention increases the heat transfer temperature difference through the high-pressure chamber structure, enhances heat exchange and scrapes off liquid through self-driven rotating condenser tubes, and achieves efficient condensation in conjunction with airflow purging.

Description

Technical Field

[0001] This invention relates to the field of liquid formaldehyde production technology, and specifically to an energy-saving condensation device for liquid formaldehyde production. Background Technology

[0002] Formaldehyde is an important organic chemical raw material, widely used in the synthesis of resins, adhesives, coatings, and pharmaceuticals. Industrially, formaldehyde is mainly produced through the oxidation or dehydrogenation of methanol. The reaction product gas contains formaldehyde, water vapor, unreacted methanol, and other non-condensable gases. After exiting the waste heat boiler and before entering the absorption tower, the reaction gas remains at a relatively high temperature and carries a large amount of water vapor and formaldehyde vapor. To recover this portion of formaldehyde and produce a dilute formaldehyde solution, a condensation process is typically required before absorption to partially liquefy and separate the condensable components in the gas.

[0003] Existing formaldehyde condensation devices generally employ shell-and-tube or coil-type heat exchangers, structurally consisting of a shell, heat exchange tubes, and end caps. The cooling medium flows inside the tubes, while the gas to be condensed flows outside, condensing water vapor and formaldehyde through heat exchange with the tube walls. These devices present the following problems in actual operation.

[0004] First, condensation efficiency is limited by temperature difference. After the gas to be condensed enters the casing, the flow cross-section is large, the flow velocity decreases, and the gas pressure remains basically the same as when it entered, so the gas temperature cannot actively increase. With a fixed cooling medium temperature, the heat transfer temperature difference between the gas and liquid phases is limited, resulting in weak condensation driving force and incomplete condensation, leaving a significant amount of formaldehyde entrained in the exhaust gas.

[0005] Second, the condensate is not drained in a timely manner. The condensate forms a liquid film on the outer wall of the heat exchange tube, and as the film thickens, it gradually coalesces into droplets, which then fall due to gravity. The liquid film covering the tube wall increases the thermal resistance, reducing the subsequent condensation rate. The droplets have a long droplet path, and some are re-entrained by the airflow, either re-evaporating or entering subsequent equipment, affecting the formaldehyde recovery rate. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an energy-saving condensation device for liquid formaldehyde production, solving the problems mentioned in the background art.

[0007] The solution of the present invention to the above-mentioned technical problems is as follows:

[0008] This invention provides an energy-saving condensation device for liquid formaldehyde production, comprising a condenser, wherein a first end cap and a second end cap are respectively provided at both ends of the condenser, and the first end cap is provided with a medium inlet and a medium outlet.

[0009] The condenser is internally divided into at least two interconnected high-pressure chambers along the axial direction.

[0010] The condenser is provided with at least one set of rotatable condenser tubes, and the condenser tubes are provided with a driving structure inside, which is used to drive the condenser tubes to rotate under the action of the heat exchange medium flowing through them.

[0011] The condenser is also equipped with a gas distribution-scraping assembly that contacts the surface of the condenser tube. The gas distribution-scraping assembly includes a gas distribution pipe and fins distributed along the axial direction of the gas distribution pipe. It is used to distribute the gas to be condensed to the surface of the condenser tube, and scrape off the condensate on its surface when the condenser tube rotates. At the same time, it sprays out airflow to blow the scraped condensate toward the inner wall of the condenser.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Furthermore, the first end cap has a first partition inside, and the medium inlet and the medium outlet are located on both sides of the first partition.

[0014] The beneficial effects of adopting the above-mentioned further solutions are:

[0015] The first baffle plate forcibly separates the medium inlet and the medium outlet. After the cooling medium enters the first end cover, it cannot flow out directly through a short circuit. It must enter the condenser tube along a predetermined path, ensuring that all the medium participates in the heat exchange cycle, avoiding medium cross-flow between the inlet and outlet, and improving the medium utilization rate and heat exchange order.

[0016] Furthermore, the condenser is internally divided into a first cavity, a second cavity, and a third cavity by a support plate. The first cavity, the second cavity, and the third cavity are all high-pressure cavities, and each cavity is connected by the gas distribution pipe.

[0017] The beneficial effects of adopting the above-mentioned further solutions are:

[0018] The condenser is internally divided into multiple high-pressure chambers connected in series. Gas must pass through each chamber sequentially, lengthening the flow path and increasing the residence time of the gas in each chamber. Due to the limited flow cross-section, each chamber experiences a pressure build-up effect, causing the gas pressure to rise in each chamber, and the gas temperature to increase accordingly, leading to a greater temperature difference between the gas and the condenser tubes. This multi-chamber series structure allows the condensation process to proceed in stages, resulting in a more uniform distribution of the condensation load across each chamber and higher overall condensation efficiency.

[0019] Furthermore, the top of the condenser is provided with a steam inlet and a circulation interface. The circulation interface is located at a position corresponding to the third cavity and is in communication with the third cavity. The circulation interface is connected to the steam inlet through a connecting pipe and a control valve, and is used to reintroduce the uncondensed gas in the third cavity into the steam inlet.

[0020] The beneficial effects of adopting the above-mentioned further solutions are:

[0021] Uncondensed gas mainly collects in the third cavity at the end. By directly placing the circulation interface at this location, uncondensed gas can be extracted nearby, reducing gas transport distance. After returning to the steam inlet, the uncondensed gas mixes with the newly entering gas to be condensed, regaining the opportunity for condensation. Formaldehyde is then captured again, reducing material loss in the exhaust gas and improving the overall formaldehyde recovery rate. The control valve can adjust the circulation volume according to operating conditions to adapt to different load conditions.

[0022] Furthermore, a drain pipe is provided on the inner wall of the bottom end of the condenser, and drain ports are provided at the bottom ends of the first cavity, the second cavity and the third cavity, and the drain ports are connected to the drain pipe; the condenser is provided with a liquid outlet below the circulation interface, and the drain pipe is connected to the liquid outlet.

[0023] The beneficial effects of adopting the above-mentioned further solutions are:

[0024] Each high-pressure chamber has an independent drain port at its bottom, allowing condensate generated in each chamber to be discharged promptly and locally, preventing liquid accumulation and occupancy of effective condensation space. Multiple drain ports converge into a single drain pipe, with centralized output through a single outlet interface. This results in a simple pipeline layout, smooth drainage, high condensate collection efficiency, and easy connection to subsequent processes.

[0025] Furthermore, the condenser tubes are movably installed inside the condenser via the support plate, and the gas distribution pipes are installed between the condenser tubes via the support plate.

[0026] The beneficial effects of adopting the above-mentioned further solutions are:

[0027] The support plate simultaneously serves as a baffle, condenser tube bearing housing, and gas distributor support, exhibiting high structural integration and reducing the need for independent support components. The movable installation of the condenser tube allows for free rotation, providing a structural basis for self-driven rotation. The gas distributor and condenser tube are positioned via the same support plate, ensuring precise relative positioning between them, stable contact gap between the fins and the condenser tube surface, and reliable scraping performance.

[0028] Furthermore, the condenser tube includes a heat exchange tube, and a driving structure is provided inside the heat exchange tube. The driving structure is a spiral auger fixedly arranged along the inner wall of the heat exchange tube.

[0029] The beneficial effects of adopting the above-mentioned further solutions are:

[0030] The spiral auger is directly integrated into the heat exchange tubes, occupying no external space. As the cooling medium flows through the heat exchange tubes, it travels along the spiral path of the auger, significantly extending the flow path and increasing the heat exchange time. Simultaneously, the thrust exerted by the medium on the spiral surface of the auger is converted into the rotational driving force for the condenser tubes; the faster the medium flow rate, the higher the condenser tube rotation speed, achieving self-driven rotation without external power. The auger also continuously disturbs the medium inside the tubes, disrupting the thermal boundary layer and increasing the convective heat transfer coefficient within the tubes.

[0031] Furthermore, the air distribution pipe includes a conduit, on which a through hole is formed at a position corresponding to the first cavity; the fins are distributed axially along the conduit and extend radially, and an air passage is provided inside the fins, which communicate with the interior of the conduit through the through hole.

[0032] The beneficial effects of adopting the above-mentioned further solutions are:

[0033] The gas to be condensed first enters the duct, and then is distributed to the air passages of each fin through the through-holes. The through-holes are located corresponding to the first cavity, so the gas is guided into the gas distribution pipe from the moment it enters the condenser, ensuring a stable gas supply to each fin's air passage. The air passages are built into the fins, and the gas is transported radially within the fins. The path is short and the resistance is low, providing sufficient airflow pressure and flow rate for the terminal nozzles.

[0034] Furthermore, the end of the fin contacts the surface of the condenser tube, and an air cut and a purge port communicating with the air passage are provided on the contact surface; the air jet direction of the air cut is towards the surface of the condenser tube, for blowing the surface of the condenser tube with airflow; the air jet direction of the purge port is towards the inner wall of the condenser, for blowing the scraped condensate from the gap between the fin and the condenser tube towards the inner wall of the condenser.

[0035] The beneficial effects of adopting the above-mentioned further solutions are:

[0036] The finned end integrates both mechanical scraping and airflow purging for liquid drainage. As the condenser tubes rotate, the fins directly scrape away the condensate film, while the air vents simultaneously spray airflow to purge any remaining droplets from the condenser tube surface. This simultaneous action ensures continuous cleaning of the condenser wall, reducing condensation thermal resistance. The purging port provides directional airflow, blowing the scraped-off droplets from the gap between the fins and condenser tubes towards the inner wall of the casing, preventing liquid from stagnating or splashing between the condenser tubes. The condensate flows orderly down the inner wall and is smoothly discharged. Both the air vents and the purging port are supplied by a unified air distribution pipe, eliminating the need for an external air source.

[0037] Furthermore, the second end cap is provided with a reflux chamber, and the reflux chamber is provided with a second baffle for guiding the medium flow.

[0038] The beneficial effects of adopting the above-mentioned further solutions are:

[0039] After heat exchange, the cooling medium enters the second end cover. The second baffle forms a flow path within the return chamber, guiding the medium to flow out from the medium outlet in an orderly manner. The residence time of the medium in the return chamber is controlled, resulting in smooth flow at the outlet and preventing eddies or pressure fluctuations at the outlet, which is beneficial to the stable operation of the entire cooling medium circulation system.

[0040] Therefore, the energy-saving condensation device for liquid formaldehyde production provided by this invention has the following beneficial effects:

[0041] This device directly increases the heat transfer temperature difference through its high-pressure chamber design. The condenser's interior is divided into multiple interconnected high-pressure chambers by a support plate, reducing the gas flow cross-section and creating pressure buildup within each chamber. This increased pressure raises the gas's saturation temperature, widening the temperature difference between the gas and the cooling medium inside the condenser tubes. The heat transfer temperature difference is the fundamental driving force of the condensation process; the greater the temperature difference, the faster the condensation rate, and the greater the amount of gas transformed into liquid per unit time. Furthermore, the self-rotation of the condenser tubes enhances heat transfer. A spiral auger is installed inside the condenser tubes; the cooling medium exerts a force on the auger as it flows, driving the condenser tubes to rotate. This rotation causes radial disturbance of the medium inside the tubes, disrupting the original laminar boundary and increasing the convective heat transfer coefficient between the medium and the tube wall. The rotation also makes the contact between the outer surface of the tubes and the gas more uniform, preventing localized overheating of the wall surface. The combination of a large temperature difference and a high heat transfer coefficient significantly improves the condensation capacity of this device.

[0042] This device integrates a dual drainage mechanism of mechanical scraping and airflow purging. The fins extending from the air distribution pipe are pressed against the surface of the condenser tubes. As the condenser tubes rotate, the newly condensed liquid film is immediately scraped off by the fins. If the liquid film is not removed promptly, it increases thermal resistance and hinders subsequent condensation. Mechanical scraping solves this problem at its source. The scraped droplets are then quickly removed by the following airflow. Two types of nozzles are located at the ends of the fins. The airflow from the air cut-off nozzles blows directly onto the surface of the condenser tubes, dispersing the residual liquid film and disrupting the gas film boundary layer, thus cleaning the wall and aiding heat transfer. The airflow from the purging nozzles blows obliquely out from the gap between the fins and the condenser tubes, pushing the accumulated droplets towards the inner wall of the condenser shell. The droplets flow down the inner wall and are smoothly discharged through the drain port and drain pipe. The combined work of scraping and purging achieves immediate removal and collection of condensate, significantly shortening the droplet residence time and avoiding losses caused by secondary entrainment or re-evaporation of liquid. The condenser tubes of this device require no external power drive. The power required for rotation comes entirely from the kinetic energy of the cooling medium itself; the force generated when the medium flows through the auger is directly converted into the mechanical energy of the condenser tubes' rotation. This design eliminates the need for an external motor or transmission mechanism, simplifying the equipment configuration and reducing additional power consumption. During operation, the only energy consumption component is the regular power consumption of the medium transfer pump; the condensation process itself does not generate new energy consumption, resulting in significant energy savings.

[0043] This device features a recirculation interface at the top of the third cavity of the condenser. Some gas that fails to condense completely in the initial stage, primarily non-condensable gases containing formaldehyde, accumulates in the final third cavity. The recirculation interface, via a conduit and control valve, reintroduces this gas into the steam inlet, allowing it to mix with the newly entering gas to be condensed before re-entering the condensation process. This recirculation and recondensation system effectively increases the capture opportunity of formaldehyde, reduces material loss with the exhaust gas, and improves the overall formaldehyde recovery rate. Attached Figure Description

[0044] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0045] In the attached diagram:

[0046] Figure 1 This is a schematic diagram of the main appearance of the present invention;

[0047] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0048] Figure 3 This is a schematic diagram of the air distribution pipe structure of the present invention;

[0049] Figure 4 This is a schematic diagram of the condenser tube structure of the present invention;

[0050] Figure 5 This is a bottom-view half-section structural diagram of the air distribution pipe of the present invention;

[0051] Figure 6 This is a schematic diagram of the main half-section structure of the air distribution pipe of the present invention;

[0052] Figure 7 This is a schematic cross-sectional view of the condenser tube of the present invention.

[0053] The attached diagram lists the components represented by each number as follows:

[0054] 1. First end cap; 101. Medium inlet; 102. Medium outlet; 103. First baffle; 2. Condenser; 201. Steam inlet; 202. Circulation interface; 203. Liquid outlet interface; 204. First cavity; 205. Second cavity; 206. Third cavity; 207. Gas distribution pipe; 208. Support plate; 209. Drain pipe; 210. Condenser tube; 211. Drain port; 212. Through hole; 213. Fin plate; 214. Screwdriver; 215. Heat exchange tube; 216. Air cut-out; 217. Purge port; 218. Gas passage; 219. Conduit; 3. Second end cap; 301. Second baffle; 302. Reflux chamber. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Please see Figures 1 to 7 As shown, the embodiments provided by the present invention are as follows:

[0057] Example 1

[0058] An energy-saving condensing device for liquid formaldehyde production includes a condenser 2, with a first end cap 1 and a second end cap 3 at both ends of the condenser 2. The first end cap 1 has a medium inlet 101 and a medium outlet 102.

[0059] The condenser 2 is internally divided into at least two interconnected high-pressure chambers along the axial direction;

[0060] The condenser 2 is provided with at least one set of rotatable condenser tubes 210. The condenser tubes 210 are provided with a driving structure inside, which is used to drive the condenser tubes 210 to rotate under the action of the heat exchange medium flowing through them.

[0061] The condenser 2 is also equipped with a gas distribution and scraping assembly that contacts the surface of the condenser tube 210. The gas distribution and scraping assembly includes a gas distribution pipe 207 and fins 213 distributed along the axial direction of the gas distribution pipe 207. It is used to distribute the gas to be condensed to the surface of the condenser tube 210 and scrape off the condensate on its surface when the condenser tube 210 rotates. At the same time, the gas flow is sprayed to blow the scraped condensate toward the inner wall of the condenser 2.

[0062] Example 2

[0063] To prevent short circuits at the media inlet and outlet and to guide the orderly flow of the media, for example, such as Figures 1 to 7 As shown, the present invention also includes:

[0064] The first end cover 1 is provided with a first partition 103 inside. The medium inlet 101 and the medium outlet 102 are located on both sides of the first partition 103. The first partition 103 forcibly separates the medium inlet 101 and the medium outlet 102. After the cooling medium enters the first end cover 1, it cannot flow out directly through a short circuit. It must enter the condenser tube 210 along a predetermined path, which ensures that all media participate in the heat exchange cycle, avoids media cross-flow between the inlet and outlet, and improves the media utilization rate and heat exchange order.

[0065] The second end cap 3 is provided with a return flow chamber 302, and a second baffle 301 is provided in the return flow chamber 302 to guide the medium flow. After the cooling medium completes heat exchange, it enters the second end cap 3. The second baffle 301 forms a flow deflection path in the return flow chamber 302, guiding the medium to flow out from the medium outlet 102 in an orderly manner. The residence time of the medium in the return flow chamber 302 is controlled, the outlet flow is stable, and eddies or pressure fluctuations at the outlet are avoided, which is conducive to the stable operation of the entire cooling medium circulation system.

[0066] Example 3

[0067] To increase the heat transfer temperature difference through a multi-cavity structure, achieve the recycling of uncondensed gas, promptly discharge condensate, and provide a supporting foundation for the self-driven rotation of the condenser tube 210, for example, such as Figures 1 to 7 As shown, the present invention also includes:

[0068] The condenser 2 is internally divided into a first cavity 204, a second cavity 205, and a third cavity 206 by a support plate 208. All three cavities are high-pressure chambers and are connected by a gas distribution pipe 207, thus dividing the condenser 2 into multiple high-pressure chambers connected in series. Gas must pass through each chamber sequentially, lengthening the flow path and increasing the residence time of the gas in each chamber. Due to the limited flow cross-section, each chamber experiences a pressure build-up effect, causing the gas pressure to increase sequentially, leading to a rise in gas temperature and a widening temperature difference with the condenser tube 210. This multi-chamber series structure allows the condensation process to proceed in stages, resulting in a more uniform distribution of the condensation load across the chambers and higher overall condensation efficiency.

[0069] The condenser 2 has a steam inlet 201 and a circulation interface 202 at its top. The circulation interface 202 is located at the position corresponding to and connected to the third cavity 206. The circulation interface 202 is connected to the steam inlet 201 via a connecting pipe and a control valve, and is used to reintroduce uncondensed gas from the third cavity 206 into the steam inlet 201. The uncondensed gas mainly collects in the third cavity 206 at the end. By directly placing the circulation interface 202 at this position, uncondensed gas can be extracted nearby, reducing the gas transport distance. After returning to the steam inlet 201, the uncondensed gas mixes with newly entering gas to be condensed, regaining a chance to condense. Formaldehyde is captured again, reducing material loss in the exhaust gas and improving the overall formaldehyde recovery rate. The control valve can adjust the circulation volume according to the operating conditions to adapt to different load conditions.

[0070] A drain pipe 209 is provided on the inner wall of the bottom of the condenser 2. Drain ports 211 are provided at the bottom of the first cavity 204, the second cavity 205, and the third cavity 206, and these ports are connected to the drain pipe 209. A liquid outlet 203 is located below the circulation interface 202 in the condenser 2, and the drain pipe 209 is connected to the liquid outlet 203. Each high-pressure chamber has an independent drain port 211 at its bottom, allowing the condensate generated in each chamber to be discharged promptly and nearby, preventing liquid accumulation and congestion of effective condensation space. Multiple drain ports 211 converge into the drain pipe 209 and are centrally output through a single liquid outlet 203. This results in a simple pipeline layout, smooth drainage, high condensate collection efficiency, and easy connection to subsequent processes.

[0071] The condenser tubes 210 are movably installed inside the condenser 2 via support plates 208. Gas distribution pipes 207 are also installed between the condenser tubes 210 via the support plates 208. The support plates 208 simultaneously function as a baffle, a bearing housing for the condenser tubes 210, and a support for the gas distribution pipes 207, resulting in high structural integration and reducing the use of independent support components. The movable installation of the condenser tubes 210 allows them to rotate freely, providing a structural basis for self-driven rotation. The gas distribution pipes 207 and condenser tubes 210 are positioned via the same support plate 208, ensuring their relative positional accuracy. This results in a stable contact gap between the fins 213 and the surface of the condenser tubes 210, ensuring reliable scraping performance.

[0072] The condenser tube 210 includes a heat exchange tube 215, within which a driving structure is provided. This driving structure is a spiral auger 214 fixed axially along the inner wall of the heat exchange tube 215. The spiral auger 214 is directly integrated into the heat exchange tube 215, without occupying external space. When the cooling medium flows through the heat exchange tube 215, it advances along the spiral path of the auger 214, significantly extending the flow path and increasing the heat exchange time. Simultaneously, the thrust exerted by the medium on the spiral surface of the auger 214 is converted into a rotational driving force for the condenser tube 210. The faster the medium flow rate, the higher the rotational speed of the condenser tube 210, achieving self-driven rotation without external power. The auger 214 also continuously disturbs the medium inside the tube, disrupting the thermal boundary layer and increasing the convective heat transfer coefficient within the tube.

[0073] Example 4

[0074] To ensure the gas to be condensed is evenly distributed onto the surface of the condenser tube 210 and to coordinate scraping and directional purging of liquid as the condenser tube 210 rotates, for example, such as Figures 1 to 7 As shown, the present invention also includes:

[0075] The air distribution pipe 207 includes a conduit 219, on which a through hole 212 is formed at a position corresponding to the first cavity 204. Fins 213 are distributed axially along the conduit 219 and extend radially, each containing an air passage 218. The air passage 218 communicates with the interior of the conduit 219 through the through hole 212. The condensed gas first enters the conduit 219 and then is distributed to the air passages 218 of each fin 213 through the through hole 212. The through hole 212 is located corresponding to the first cavity 204, ensuring that gas is introduced into the air distribution pipe 207 from the moment it enters the condenser 2, thus guaranteeing a stable gas supply to the air passages 218 of each fin 213. The air passage 218 is built into the interior of the fin 213, allowing gas to be transported radially within the fin 213. This short path and low resistance provide sufficient airflow pressure and flow rate for the terminal nozzles.

[0076] The end of the fin 213 contacts the surface of the condenser tube 210, and an air cutout 216 and a purge port 217 communicating with the air passage 218 are provided on the contact surface. The air jet direction of the air cutout 216 is towards the surface of the condenser tube 210, used to purge the surface of the condenser tube 210 with airflow. The air jet direction of the purge port 217 is towards the inner wall of the condenser 2, used to blow the scraped condensate from the gap between the fin 213 and the condenser tube 210 towards the inner wall of the condenser 2. The end of the fin 213 integrates both mechanical scraping and airflow purging for liquid drainage. When the condenser tube 210 rotates, the fin 213 directly scrapes off the condensate film, and the air cutout 216 then sprays airflow to purge residual droplets on the surface of the condenser tube 210. The simultaneous action of the two achieves continuous cleaning of the condenser wall surface and reduces the condensation thermal resistance. The purge port 217 provides a directional airflow, blowing the scraped-off droplets from the gap between the fin 213 and the condenser tube 210 toward the inner wall of the housing, preventing liquid from accumulating or splashing between the condenser tubes 210. The condensate flows down the inner wall in an orderly manner and is discharged smoothly. The air jets from the air cut-out port 216 and the purge port 217 are both supplied by the air distribution pipe 207, requiring no additional air source.

[0077] Working principle:

[0078] Before operation begins, the cooling medium flows in through the medium inlet 101 on the first end cap 1. The interior of the first end cap 1 is divided by the first baffle 103, and the medium must pass through a baffle before flowing into the condenser tube 210. This structure ensures that the medium flows in an orderly manner along the designed route. After entering the heat exchange tube 215, the medium advances along the spiral auger 214 inside the tube, and the flow path is forcibly extended, thereby increasing the heat exchange time with the tube wall.

[0079] The gas to be condensed enters through the steam inlet 201 at the top of the condenser 2. The gas first enters the first cavity 204, separated by the support plate 208, and then sequentially enters the second cavity 205 and the third cavity 206 through the gas distribution pipe 207. These three cavities are all high-pressure chambers and are interconnected. Due to the restricted flow cross-section, the gas accumulates in each cavity, causing the pressure and temperature to rise. A larger temperature difference is created between the high-temperature gas and the cooling medium inside the condenser tube 210, thus significantly enhancing the condensation driving force and resulting in higher condensation efficiency.

[0080] The gas distribution pipe 207 is responsible for evenly distributing the gas to be condensed onto the surface of the condenser tube 210. The gas first enters the conduit 219 of the gas distribution pipe 207, and then enters the air passage 218 inside the fin 213 through the through hole 212 on the conduit 219. The gas in the air passage 218 is finally ejected from two openings at the end of the fin 213. One is the air cut-out 216, where the airflow blows directly onto the surface of the condenser tube 210, both to purge the condensate and to break the thermal boundary layer of the condenser wall, thus enhancing heat transfer. The other is the purge port 217, where the airflow is directed towards the inner wall of the condenser shell, responsible for quickly removing the scraped-off droplets.

[0081] During this process, the cooling medium flows within the heat exchange tube 215, continuously driving the auger 214. The auger 214, fixed within the tube wall, is propelled by the force of the fluid, causing the entire condenser tube 210 to rotate around its support plate 208. The faster the medium flow rate, the higher the rotational speed of the condenser tube 210. The rotation of the condenser tube 210 brings two direct benefits. First, the rotation of the heat exchange tube 215 itself generates secondary turbulence in the medium within the tube, further improving heat exchange efficiency. Second, the outer wall of the condenser tube 210 moves relative to the stationary fins 213, creating relative motion between the two.

[0082] The fins 213 are tightly attached to the outer surface of the condenser tube 210. When the condenser tube 210 rotates, the condensate film adhering to the tube wall is immediately scraped off by the fins 213. Before the freshly scraped droplets can re-adhere, the adjacent air vent 216 sprays air to blow them away from the tube wall. Subsequently, the directional airflow from the purge port 217 pushes these droplets from the gap between the fins 213 and the condenser tube 210 toward the inner wall of the condenser 2. The droplets flow down the inner wall, collect at the drain ports 211 at the bottom of each cavity, and are finally discharged from the outlet port 203 through the drain pipe 209, forming a dilute formaldehyde solution.

[0083] Uncondensed gas mainly accumulates in the third cavity 206 at the end. A circulation port 202 is located at the top of the third cavity 206, which is connected back to the steam inlet 201 via a conduit 219 and a control valve. Uncondensed gas is drawn out from the circulation port 202 and reintroduced into the condenser 2 inlet, mixing with newly entering gas and participating in the condensation cycle again. This arrangement improves the overall formaldehyde recovery rate.

[0084] After the medium completes the heat exchange, it flows out from the end of the condenser tube 210 and enters the reflux chamber 302 of the second end cover 3. The reflux chamber 302 is provided with a second baffle 301, and the medium flows back and forth in the chamber before being discharged from the medium outlet 102, carrying away the heat.

[0085] In summary, this device increases the heat transfer temperature difference by raising the gas temperature through a high-pressure chamber, enhances heat exchange between the inside and outside of the tube by driving the condenser tube 210 to rotate through the self-driven medium, removes condensate in a timely manner and accelerates collection through the scraping and purging combination structure of the fin plate 213, and improves recovery efficiency by circulating uncondensed gas. The entire process does not require external power to drive the rotating parts, achieving a balance between energy saving and high-efficiency condensation.

[0086] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0087] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An energy-saving condensing device for liquid formaldehyde production, comprising a condenser (2), wherein a first end cap (1) and a second end cap (3) are respectively provided at both ends of the condenser (2), and the first end cap (1) is provided with a medium inlet (101) and a medium outlet (102), characterized in that: The condenser (2) is internally divided into at least two interconnected high-pressure chambers along the axial direction; The condenser (2) is provided with at least one set of rotatable condenser tubes (210), and the condenser tubes (210) are provided with a driving structure inside, which is used to drive the condenser tubes (210) to rotate under the action of the heat exchange medium flowing through them; The condenser (2) is also provided with a gas distribution-scraping assembly that contacts the surface of the condenser tube (210). The gas distribution-scraping assembly includes a gas distribution pipe (207) and fins (213) distributed along the axial direction of the gas distribution pipe (207). It is used to distribute the gas to be condensed to the surface of the condenser tube (210) and scrape off the condensate on its surface when the condenser tube (210) rotates. At the same time, the gas flow is sprayed to blow the scraped condensate toward the inner wall of the condenser (2).

2. The energy-saving condensing device for liquid formaldehyde production according to claim 1, characterized in that: The first end cap (1) has a first partition (103) inside, and the medium inlet (101) and the medium outlet (102) are located on both sides of the first partition (103).

3. The energy-saving condensing device for liquid formaldehyde production according to claim 1, characterized in that: The condenser (2) is divided into a first cavity (204), a second cavity (205) and a third cavity (206) by a support plate (208). The first cavity (204), the second cavity (205) and the third cavity (206) are all high-pressure cavities, and each cavity is connected by the gas distribution pipe (207).

4. The energy-saving condensing device for liquid formaldehyde production according to claim 3, characterized in that: The top of the condenser (2) is provided with a steam inlet (201) and a circulation interface (202). The circulation interface (202) is located at a position corresponding to the third cavity (206) and is connected to the third cavity (206). The circulation interface (202) is connected to the steam inlet (201) through a connecting pipe and a control valve, and is used to reintroduce the uncondensed gas in the third cavity (206) into the steam inlet (201).

5. The energy-saving condensing device for liquid formaldehyde production according to claim 4, characterized in that: The condenser (2) has a drain pipe (209) on the inner wall at the bottom end. The bottom ends of the first cavity (204), the second cavity (205) and the third cavity (206) are all provided with drain ports (211), and the drain ports (211) are connected to the drain pipe (209). The condenser (2) is provided with a liquid outlet (203) below the circulation interface (202), and the drain pipe (209) is connected to the liquid outlet (203).

6. The energy-saving condensing device for liquid formaldehyde production according to claim 5, characterized in that: The condenser tube (210) is movably installed in the condenser (2) via the support plate (208), and the gas distribution pipe (207) is installed between the condenser tubes (210) via the support plate (208).

7. An energy-saving condensing device for liquid formaldehyde production according to claim 6, characterized in that: The condenser tube (210) includes a heat exchange tube (215), and the heat exchange tube (215) is provided with a driving structure. The driving structure is a spiral auger (214) fixedly arranged along the inner wall of the heat exchange tube (215).

8. An energy-saving condensing device for liquid formaldehyde production according to claim 3, characterized in that: The air distribution pipe (207) includes a conduit (219), on which a through hole (212) is provided at a position corresponding to the first cavity (204); the fin plate (213) is distributed axially along the conduit (219) and extends radially, and an air passage (218) is provided inside it, which communicates with the inside of the conduit (219) through the through hole (212).

9. An energy-saving condensing device for liquid formaldehyde production according to claim 8, characterized in that: The end of the fin (213) contacts the surface of the condenser tube (210), and an air cut (216) and a purge port (217) communicating with the air passage (218) are provided on the contact surface; the air jet direction of the air cut (216) is towards the surface of the condenser tube (210), and is used to purge the surface of the condenser tube (210) with airflow; the air jet direction of the purge port (217) is towards the inner wall of the condenser (2), and is used to blow the scraped condensate from the gap between the fin (213) and the condenser tube (210) towards the inner wall of the condenser (2).

10. An energy-saving condensing device for liquid formaldehyde production according to claim 1, characterized in that: The second end cap (3) is provided with a reflux chamber (302), and the reflux chamber (302) is provided with a second baffle (301) for guiding the medium to flow.

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