Combined evaporator

Abstract

The utility model discloses a combined evaporator which comprises an evaporator barrel, an evaporator mixed gas inlet is formed in the side wall of a lower diameter expanding section, an evaporator condensate outlet is formed in the circumference of the lower portion of the lower diameter expanding section, and an evaporator mixed gas outlet is formed in the side wall of an upper diameter expanding section. The middle part of the upper tube box is fixedly connected to the center of the upper end sealing cover of the cylinder, and an expansion joint is arranged on the circumferential wall of the middle-lower part; the upper tube plate is connected to the lower port of the upper tube box; the lower tube plate is connected below a condensate outlet of the evaporator; the heat exchange tube is connected between the upper tube plate and the lower tube plate; the upper end of the oil inlet distribution pipe is connected below the central area of the lower pipe plate and is connected with a mixed liquid inlet of the evaporator; the upper tube plate center eduction tube is connected above the center area of the upper tube plate; the flash-tank is connected to the lower part of the evaporator cylinder, a flash-tank mixed liquid outlet is formed in the center of a lower sealing head, and a flash-tank gas outlet is formed in the side wall of the upper part of the lower sealing head. The equipment can improve the overall evaporation efficiency, avoid scaling of the pipe wall and reduce the equipment investment.

Description

Technical Field

[0001] The utility model relates to a falling film evaporator in the sections of zero-discharge evaporation of wastewater, DC hot air energy-saving water circulation heat exchange, and mixed oil evaporation in a vegetable oil extraction workshop, and particularly relates to a combined evaporator, belonging to the technical field of evaporation and concentration equipment. Background Technique

[0002] In the vegetable oil extraction production process, a large number of technical operation units of liquid-liquid separation are involved. The evaporator is the core equipment for evaporating and concentrating the mixed liquid. Reasonably selecting the evaporation device is of great significance for improving the production efficiency of evaporating and concentrating the mixed liquid, reducing production costs, and improving the economic benefits of enterprises.

[0003] According to the different flow modes of the material in the tube, it is divided into rising film type, falling film type, forced circulation type, etc. Among them, the falling film evaporator is the most widely used and is commonly used in the fields of chemical industry, pharmacy, food, etc. Its working principle is that the mixed liquid is evenly distributed from the top to the inner wall of the tube through a nozzle or a liquid distributor to form a thin liquid film. Under the heating action of the heating medium outside the tube, the low-boiling components in the liquid film are evaporated. The liquid film continuously forms and flows downwards from top to bottom under the action of gravity and secondary steam, greatly improving the convective heat transfer coefficient and significantly enhancing the evaporation efficiency.

[0004] The rising film type is also called the climbing film type. It operates based on the principle of a siphon pump. According to the lifting force of the steam bubbles generated during the boiling process, the liquid and steam flow upward in parallel. At the same time, the amount of generated steam increases, forming a flowing film on the tube wall. It is generally used for evaporating materials with relatively low concentrations. Due to the relatively high requirement for the gas velocity of the secondary steam, when the inlet concentration of the material is unstable or too high, the generated secondary steam is less, and the gas velocity is not sufficient to push the liquid upward, resulting in a sharp decline in the heat transfer efficiency. Subsequently, the amount of secondary steam becomes less, and so on in a vicious cycle, leading to a very poor evaporation effect.

[0005] At present, most of the evaporation processes of mixed oil (vegetable oil plus solvent hexane) in vegetable oil extraction still use the rising film evaporators from one or two decades ago. With the improvement of the extraction efficiency in the previous stage and the requirements of energy conservation and consumption reduction, the concentration of the mixed oil at the evaporator inlet has increased significantly compared with before. As a result, the secondary steam generated by the vaporization of the mixed oil is less, and the gas velocity is too low to push the mixed oil to form a film adhering to the wall, resulting in low evaporation heat transfer efficiency or even pure liquid-phase heat exchange without evaporation. This leads to a long residence time of the mixed oil in the tube, coking and scaling on the inner wall of the tube, deepening of the oil color, high phospholipid content, easy foaming, poor separation of oil and solvent in the flash evaporator, and a series of chain problems caused by the entrainment of oil foam in the solvent into the subsequent solvent condensation and recovery system. At the same time, the production steam consumption is high.

[0006] In the wastewater zero-discharge evaporation and DC hot air energy-saving water circulation heat exchange section of the vegetable oil extraction workshop, a falling film evaporator is used to evaporate water. There are also cases where falling film evaporation is used in addition to rising film evaporation for the evaporation of miscella. These falling film evaporators still follow the traditional structural form. The material enters from the upper tube box of the evaporator, and after being distributed by the distributor, it flows downward in a thin film along the inner wall of the tube bundle. The volatile components are heated and vaporized, and finally the vapor-liquid mixture leaves the heating tube and undergoes vapor-liquid separation inside the flash tank or external flash tank at the lower part. In these falling film evaporation operations, the inlet temperature of the material is generally lower than the boiling point under its operating pressure, and it cannot evaporate immediately when it enters the evaporator. The material is heated as a pure liquid for a long distance inside the tube without the promotion of vapor velocity. The low vapor velocity results in poor heat transfer efficiency, affecting the overall evaporation efficiency and prone to fouling.

[0007] Generally, the structure of the evaporator is relatively fixed and is widely used in various industries. Its structural performance can still meet the requirements. However, with the current trend of large-scale and large-size development, the required evaporator area and specifications are getting larger and larger, resulting in increasing weight and volume. Higher requirements are put forward for the operation stability of the equipment, reducing temperature difference stress through thermal expansion compensation, and the welding reliability of the tube bundle.

[0008] There is a temperature difference between the shell-side fluid and the tube-side fluid of the evaporator. When an expansion joint is set on the shell-side cylinder, due to the large diameter of the cylinder, the required expansion joint is also large. The influence of the upper load and seismic force also needs to be considered. Especially for large evaporators, the self-weight load also has a significant impact on the stiffness and stability of the expansion joint. If the thickness of the expansion joint is increased, the rigidity of the expansion joint will also increase, which in turn affects its thermal stress compensation ability. The expansion joint set on the shell-side cylinder is restricted by the external atmospheric phase pipe, which will also cause inconsistent overall expansion, uneven stress on the expansion joint, affecting the service life of the expansion joint. For large evaporators, it will also cause the upper part of the evaporator to be non-vertical, affecting the material distribution and the film-forming effect of the material inside the tube.

[0009] The flash tank of the existing evaporator has a simple structure. It only relies on volume amplification or an external flash tank for vapor-liquid separation by the gravity density difference of the vapor and liquid, without a rotating centrifugal structure like a cyclone separator. In this way, either the flash tank is designed to be very large, resulting in uneconomical equipment cost and large floor area for equipment layout, or the vapor-liquid separation is not complete, and the secondary steam evaporated carries material droplets into the subsequent condensation and recovery system, leading to a series of chain problems.

[0010] As a traditional and mature liquid-liquid evaporation and separation equipment, there are many public literatures, papers, patents and other materials in the industry. However, although there are some partial improvements for the above pain points, there is no good systematic overall solution.

[0011] For example, the Chinese utility model patent with the publication number CN 205925025U discloses a first evaporator for the oil leaching process, which uses existing evaporators and separators in the prior art. The main technical problem solved is to heat the mixed oil by using the waste heat of the solvent-steam mixed gas, that is, the problem of energy reuse. However, it does not involve the improvement of the evaporator and the separator to improve the energy utilization efficiency.

[0012] The Chinese utility model patent with the publication number CN 202450067U discloses an oil evaporator for the evaporation of mixed oil. The main device adopted in this technical solution is still a combined structure of an evaporator + a separator. The main technical problems solved are that the solvent consumption of the evaporator is large, the solvent recovery rate is low, and the residual solvent in the leached crude oil is high. However, it does not consider that when the inlet temperature of the material is lower than the boiling point under its operating pressure, the material cannot be immediately evaporated, resulting in a series of problems such as a decrease in evaporation efficiency, a high residual solvent in the leached crude oil, a low solvent recovery rate, and easy scaling in the tube side. Utility Model Content

[0013] The purpose of this part is to outline some aspects of the embodiments of the present utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part as well as in the abstract and the title of the specification of this application, but such simplifications or omissions shall not be used to limit the scope of the present utility model.

[0014] In view of the above and / or problems existing in the prior art, the present utility model is proposed.

[0015] The purpose of the present utility model is to provide a combined evaporator, which can solve the problem that since the inlet temperature of the material is generally lower than the boiling point under its operating pressure, the material cannot be immediately evaporated when entering the evaporator, and the material is heated as a pure liquid for a long distance in the tube without the promotion of steam velocity, resulting in a very poor heat transfer effect due to low steam velocity. Thus, the overall evaporation efficiency can be improved, the scaling of the tube wall can be avoided, and the equipment investment can be reduced.

[0016] To solve the above technical problems, a combined evaporator of the present utility model includes:

[0017] An evaporator cylinder, which is in a vertical cylindrical shape. The side wall of the lower enlarged diameter section is provided with an evaporator mixed gas inlet, the circumference below the lower enlarged diameter section is provided with an evaporator condensate outlet, and the side wall of the upper enlarged diameter section is provided with an evaporator mixed gas outlet;

[0018] An upper tube sheet, which is fixedly connected to the center of the upper end cover of the evaporator cylinder, and an expansion joint is provided on the circumferential wall inside the evaporator cylinder;

[0019] An upper tube plate, which is connected to the lower port of the upper tube sheet;

[0020] Lower tube sheet, connected to the cross-section of the evaporator cylinder body below the outlet of the evaporator condensate;

[0021] Heat exchange tubes, evenly connected between the upper tube sheet and the lower tube sheet;

[0022] Oil inlet distribution pipe, with the upper end connected below the central area of the lower tube sheet, and the center of the lower end sealing plate connected to the evaporator mixed liquid inlet extending outside the evaporator cylinder body;

[0023] Upper tube sheet central outlet pipe, matching the oil inlet distribution pipe and connected above the central area of the upper tube sheet;

[0024] Flash evaporator, connected to the lower part of the evaporator cylinder body and provided with a lower head at the lower end, with a flash evaporator mixed liquid outlet at the center of the lower head and a flash evaporator gas outlet on the upper side wall.

[0025] As an improvement of the present utility model, the upper part of the flash evaporator is connected to the lower part of the evaporator cylinder body through a flash evaporator tapered section that is narrow at the top and wide at the bottom, and the flash evaporator gas outlet is connected to the side wall of the flash evaporator tapered section.

[0026] As a further improvement of the present utility model, a gas-liquid separation cyclone cylinder is connected to the lower part of the evaporator cylinder body, and the lower end of the gas-liquid separation cyclone cylinder is open and extends to the middle part of the inner cavity of the flash evaporator.

[0027] As a further improvement of the present utility model, two tangentially outward swirling cyclone exhaust ports are symmetrically connected to the circumference of the middle and lower parts of the gas-liquid separation cyclone cylinder.

[0028] As a further improvement of the present utility model, the lower part of the evaporator cylinder body is connected to the upper end of the gas-liquid separation cyclone cylinder through a tapered section.

[0029] As a further improvement of the present utility model, a distributor is provided in the lower part of the inner cavity of the upper tube box. The upper end of the distributor is open, and a plurality of liquid distribution holes are evenly distributed on the bottom plate of the distributor. The upper end of the upper tube sheet central outlet pipe passes through the center of the bottom plate of the distributor and the upper port is inserted into the oil collecting tank, and a plurality of overflow ports are evenly provided on the lower circumference of the oil collecting tank.

[0030] As a further improvement of the present utility model, the top of the upper tube sheet central outlet pipe is closed, and a plurality of distribution branch pipes extending radially outward are evenly connected to the upper circumference of the upper tube sheet central outlet pipe, and nozzles are respectively provided below the ends of each distribution branch pipe.

[0031] As a further improvement of the present utility model, an evaporator air extraction port is connected to the upper side wall of the evaporator cylinder body.

[0032] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. For materials with low viscosity and not easy to scale, or materials with high viscosity and easy to scale, the high flow rate of the mixed liquid can be maintained in the heat exchange tubes, which helps to reduce the thermal resistance on the tube side, improve the heat transfer efficiency, and at the same time reduce the residence time of the mixed liquid in the heat exchange tubes to prevent scaling on the inner wall of the heat exchange tubes.

[0033] 2. The expansion joint is arranged in the tube side, which can not only offset the thermal deformation caused by the temperature difference stress generated by the temperature difference between the tube side and the shell side fluid, but also avoid the influence of the equipment self-weight, upper load, seismic force, and pipeline additional load. Furthermore, the complex design calculation for setting the expansion joint on the shell due to the upper load and seismic force is eliminated, and at the same time, the operation stability of the equipment is improved.

[0034] 3. To ensure complete separation of the mixed liquid and gas after evaporation and prevent entrainment. A gas-liquid separation cyclone is arranged in the flash evaporator at the lower part of the equipment. The structure of the cyclone is similar to that of a cyclone separator. The evaporated mixed liquid and gas are thrown out of the outer wall obliquely downward along the tangential direction of the inner wall, and splash around. The liquid falls to the lower part of the equipment due to its own weight and is discharged from the bottom outlet, while the gas is sucked into the subsequent condenser from the gas outlet of the flash evaporator. The flow channel forms a certain angle with the axis to ensure the spiral downward movement of the internal fluid. The flow channel gradually contracts to ensure the accelerated movement of the fluid. The above structure is simple and compact, with remarkable gas-liquid separation effect. There is no need for an external flash evaporator, saving the equipment floor space. At the same time, by virtue of the density difference between the liquid and the gas and the centrifugal separation structure, the size of the flash evaporator can be effectively reduced, and the equipment cost can be lowered. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. The drawings are only provided for reference and explanation, and are not used to limit the present utility model. Among them:

[0036] Figure 1 is the front view of the first embodiment of the combined evaporator of the present utility model;

[0037] Figure 2 is Figure 1 the enlarged view of the central part of the upper tube sheet;

[0038] Figure 3 is Figure 1 the enlarged sectional view along A-A in ;

[0039] Figure 4 is Figure 1 the enlarged sectional view along B-B in ;

[0040] Figure 5 is Figure 1 the three-dimensional view of the gas-liquid separation cyclone tube;

[0041] Figure 6 is the front view of the second embodiment of the combined evaporator of the present invention;

[0042] Figure 7 is Figure 6 the enlarged sectional view along C-C in;

[0043] In the figure: 1. upper tube sheet; 1a. sight glass; 1b. expansion joint; 1c. upper tube plate; 2. oil collecting tank; 3. distributor; 4. central outlet pipe of the upper tube plate; 5. distribution branch pipe; 6. nozzle; 7. evaporator cylinder; 7a. evaporator mixed gas inlet; 7b. evaporator mixed gas outlet; 7c. evaporator condensate outlet; 7d. evaporator air extraction port; 8. heat exchange tube; 9. baffle plate; 10. tie rod; 11. lower tube plate; 12. evaporator mixed liquid inlet; 13. oil inlet distribution pipe; 14. gas-liquid separation cyclone tube; 14a. cyclone exhaust port; 15. flash tank; 15a. flash tank mixed liquid outlet; 15b. flash tank gas outlet; 15c. manhole; 16. skirt support. Specific embodiments

[0044] In the following description of the present invention, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating that the device must have a specific orientation.

[0045] In order to make the technical means, creative features, achieved purposes and effects realized by the present invention easy to understand, the present invention will be further described below with reference to specific drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. Embodiment

[0047] For materials with low viscosity and not easy to scale, the following scheme is adopted:

[0048] Such as Figures 1 to 5As shown in the figure, the combined evaporator of the present utility model includes an evaporator cylinder body 7 located in the upper part and a flash evaporator 15 connected to the lower part of the evaporator cylinder body 7. The evaporator cylinder body 7 is in the shape of a vertical cylinder. An evaporator mixed gas inlet 7a is provided on the side wall of the lower enlarged diameter section, an evaporator condensate outlet 7c is provided on the circumference below the lower enlarged diameter section, and an evaporator mixed gas outlet 7b is provided on the side wall of the upper enlarged diameter section. An evaporator air extraction port 7d is also connected to the upper side wall of the evaporator cylinder body 7, which is convenient for extracting non-condensable gas during startup and operation.

[0049] The center of the upper end cover of the evaporator cylinder body 7 is embedded with an upper tube sheet 1. The middle part of the upper tube sheet 1 is fixedly connected to the upper end cover. A sight glass 1a is provided at the center of the top of the upper tube sheet 1, which is convenient for observing the liquid distribution state in the upper tube sheet 1. An expansion joint 1b is provided on the circumferential wall of the upper tube sheet 1 located inside the evaporator cylinder body 7, and an upper tube plate 1c is provided at the lower port of the upper tube sheet 1.

[0050] A lower tube plate 11 is fixedly installed on the lower cross-section of the evaporator cylinder body 7, and the lower tube plate 11 is located below the evaporator condensate outlet 7c. A plurality of heat exchange tubes 8 are evenly connected between the upper tube plate 1c and the lower tube plate 11. A plurality of baffle plates 9 are provided along the elevation of the heat exchange tubes 8 to increase the flow length of the shell side, which is convenient for full heat exchange with the inside of the heat exchange tubes 8. The baffle plates 9 are fixed by a pull rod 10.

[0051] An oil inlet distribution pipe 13 is connected below the central area of the lower tube plate 11. The center of the lower end cover of the oil inlet distribution pipe 13 is connected with an evaporator mixed liquid inlet 12, and the evaporator mixed liquid inlet 12 extends outside the evaporator cylinder body 7.

[0052] A distributor 3 is provided in the lower part of the inner cavity of the upper tube sheet 1. The upper end of the distributor 3 is open, and a plurality of liquid distribution holes are evenly distributed on the bottom plate of the distributor. A central outlet pipe 4 of the upper tube plate matching the oil inlet distribution pipe 13 is connected above the central area of the upper tube plate 1c. The upper end of the central outlet pipe 4 of the upper tube plate passes through the center of the bottom plate of the distributor and the upper port is inserted into the oil collecting tank 2. A plurality of overflow ports are evenly provided on the circumference of the lower part of the oil collecting tank 2.

[0053] The mixed liquid enters the oil inlet distribution pipe 13 from the evaporator mixed liquid inlet 12 through a circulating pump, and then enters several central heat exchange tubes 8 from the oil inlet distribution pipe 13 and rises. Since the oil inlet distribution pipe 13 is located in a small area at the center of the lower tube plate 11 and has a small flow area, it can ensure a high flow rate of the mixed liquid in the central heat exchange tubes, which helps to reduce the thermal resistance on the tube side, improve the heat transfer efficiency, and at the same time reduce the residence time of the mixed liquid in the heat exchange tubes, preventing it from scaling on the inner wall of the heat exchange tubes.

[0054] During the rapid upward movement of the mixed liquid in the heat exchange tubes 8, it is continuously heated by the shell-side mixed steam (heat source) entering from the evaporator mixed gas inlet 7a, and the heat-exchanged mixed gas is discharged from the evaporator mixed gas outlet 7b at the upper part of the shell side.

[0055] The mixed liquid flowing upward along the central heat exchange tube enters the upper oil collecting tank 2 through the central outlet pipe 4 of the upper tube sheet, overflows from the peripheral notch of the oil collecting tank 2, evenly enters the distributor 3, and after secondary distribution by the distributor 3, is evenly distributed on the upper tube sheet 1c. Then the mixed liquid flows downward along the inner wall of the heat exchange tube 8 in the area outside the central outlet pipe 4 of the upper tube sheet to form falling film heat exchange.

[0056] When the mixed liquid reaches the upper oil collecting tank 2, due to the sudden increase in space, a large amount of gas will flash out. These gases enter the heat exchange tube 8 together with the mixed liquid and move downward, which helps the mixed liquid form a thin film inside the heat exchange tube 8 and also increases the velocity of the liquid, thereby increasing heat transfer. The evaporated mixed liquid is separated in the lower flash evaporator 15.

[0057] The upper part of the flash evaporator 15 is connected to the lower part of the evaporator cylinder 7 through a flash evaporator conical section that is narrow at the top and wide at the bottom. The side wall of the flash evaporator conical section is connected with a flash evaporator gas outlet 15b. The bottom of the flash evaporator 15 is supported on the ground by a skirt support 16.

[0058] The lower part of the evaporator cylinder 7 is connected with a gas-liquid separation cyclone 14 through a tapered section to increase the flow velocity in the gas-liquid separation cyclone 14. The lower end of the gas-liquid separation cyclone 14 is open and extends to the middle part of the inner cavity of the flash evaporator 15. Two tangentially outward swirling cyclone exhaust ports 14a are symmetrically connected to the circumferences of the middle and lower parts of the gas-liquid separation cyclone 14. A part of the liquid directly falls from the lower port of the gas-liquid separation cyclone 14, and the other part of the liquid follows the airflow to rotate and accelerate and is discharged from the two cyclone exhaust ports 14a. The liquid falls on the inner wall of the flash evaporator 15 and flows downward. The lower end of the flash evaporator 15 is provided with a lower head, and the center of the lower head is provided with a flash evaporator mixed liquid outlet 15a. An anti-vortex baffle is provided at the inner port of the flash evaporator mixed liquid outlet 15a to prevent gas from being discharged from the flash evaporator mixed liquid outlet 15a; a conical sealing plate is provided at the top of the anti-vortex baffle to ensure that the mixed liquid can be completely discharged.

[0059] The gas flows upward along the outer circumference of the gas-liquid separation cyclone 14 and is discharged from the flash evaporator gas outlet 15b on the side wall of the flash evaporator conical section. A manhole 15c is provided on the lower circumferential wall of the flash evaporator 15 for easy access for maintenance. Embodiment

[0060] For materials with high viscosity and easy to scale, the following scheme is adopted:

[0061] Such as Figure 6 、 Figure 7As shown in the figure, the combined evaporator of the present utility model includes an evaporator cylinder body 7 located in the upper part and a flash tank 15 connected to the lower part of the evaporator cylinder body 7. The evaporator cylinder body 7 is in the shape of a vertical cylinder. An evaporator mixed gas inlet 7a is provided on the side wall of the lower enlarged diameter section, an evaporator condensate outlet 7c is provided on the circumference below the lower enlarged diameter section, and an evaporator mixed gas outlet 7b is provided on the side wall of the upper enlarged diameter section. An evaporator air extraction port 7d is also connected to the upper side wall of the evaporator cylinder body 7, which is convenient for extracting non-condensable gases during startup and operation.

[0062] In the center of the upper end cover of the evaporator cylinder body 7, a upper tube sheet 1 is embedded. The middle part of the upper tube sheet 1 is fixedly connected to the upper end cover. A sight glass 1a is provided at the center of the top of the upper tube sheet 1, which is convenient for observing the liquid distribution state in the upper tube sheet 1. An expansion joint 1b is provided on the circumferential wall of the upper tube sheet 1 located inside the evaporator cylinder body 7, and a upper tube plate 1c is provided at the lower port of the upper tube sheet 1.

[0063] A lower tube plate 11 is fixedly arranged on the lower cross-section of the evaporator cylinder body 7, and the lower tube plate 11 is located below the evaporator condensate outlet 7c. A plurality of heat exchange tubes 8 are evenly connected between the upper tube plate 1c and the lower tube plate 11, and a plurality of baffle plates 9 are arranged along the elevation of the heat exchange tubes 8.

[0064] A fuel inlet distribution pipe 13 is connected below the central area of the lower tube plate 11. The center of the lower end sealing plate of the fuel inlet distribution pipe 13 is connected with an evaporator mixed liquid inlet 12, and the evaporator mixed liquid inlet 12 extends outside the evaporator cylinder body 7.

[0065] Above the central area of the upper tube plate 1c, an upper tube plate central outlet pipe 4 matching the fuel inlet distribution pipe 13 is connected. The upper end of the upper tube plate central outlet pipe 4 passes through the center of the distributor bottom plate and is closed at the top. A plurality of distribution branch pipes extending radially outward are evenly connected to the upper circumference of the upper tube plate central outlet pipe 4, and nozzles are respectively arranged below the ends of each distribution branch pipe.

[0066] The mixed liquid enters the fuel inlet distribution pipe 13 from the evaporator mixed liquid inlet 12 through a circulation pump, and then enters several central heat exchange tubes from the fuel inlet distribution pipe 13 and rises. During the rapid upward movement of the mixed liquid in the heat exchange tubes, it is continuously heated by the shell-side mixed steam (heat source) entering from the evaporator mixed gas inlet 7a. The mixed liquid rising along the central heat exchange tubes enters 3 - 4 distribution branch pipes 5 through the upper tube plate central outlet pipe 4, and is evenly sprayed on the upper tube plate 1c through the nozzles 6. A distribution head is installed at the upper end of each heat exchange tube to ensure that the mixed liquid flows downward along the inner wall of the heat exchange tube. When the mixed liquid sprays out from the nozzle, a large amount of gas will flash due to the sudden increase in space. These gases and the mixed liquid enter the heat exchange tubes together and move downward, which helps the mixed liquid form a thin film inside the heat exchange tubes and also increases the velocity of the liquid, thereby increasing heat transfer. The evaporated mixed liquid is separated in the lower flash.

[0067] The rest is the same as or similar to that of the first embodiment, and will not be elaborated here.

[0068] The above are only the preferred and feasible embodiments of the present utility model, which show and describe the basic principles, main features and advantages of the present utility model. The patent protection scope of the present utility model is not limited thereby. Those skilled in the art should understand that the present utility model is not restricted by the above embodiments. Except for the above embodiments, without departing from the spirit and scope of the present utility model, the present utility model may have other implementation manners. The present utility model will also have various changes and improvements. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present utility model. The protection scope required by the present utility model is defined by the appended claims and their equivalents. The technical features not described in the present utility model can be realized by or adopted from the prior art, and will not be elaborated here.

Claims

1. A combined evaporator, characterized in that, Comprising: An evaporator cylinder body, which is in the shape of a vertical cylinder. An evaporator mixed gas inlet is provided on the side wall of the lower enlarged diameter section. An evaporator condensate outlet is provided on the circumference below the lower enlarged diameter section. An evaporator mixed gas outlet is provided on the side wall of the upper enlarged diameter section; An upper tube sheet box, centrally fixedly connected to the center of the upper end cover of the evaporator cylinder body. An expansion joint is provided on the circumferential wall inside the evaporator cylinder body; An upper tube sheet, connected to the lower port of the upper tube sheet box; A lower tube sheet, connected to the cross-section of the evaporator cylinder body below the evaporator condensate outlet; Heat exchange tubes, evenly connected between the upper tube sheet and the lower tube sheet; An oil inlet distribution pipe, with its upper end connected below the central area of the lower tube sheet, and the center of the lower end sealing plate connected to the evaporator mixed liquid inlet extending outside the evaporator cylinder body; An upper tube sheet center outlet pipe, matching the oil inlet distribution pipe and connected above the central area of the upper tube sheet; A flash evaporator, connected to the lower part of the evaporator cylinder body and provided with a lower head at the lower end. A flash evaporator mixed liquid outlet is provided at the center of the lower head. A flash evaporator gas outlet is provided on the upper side wall.

2. The combined evaporator according to claim 1, wherein: The upper part of the flash evaporator is connected to the lower part of the evaporator cylinder body through a flash evaporator tapered section that is narrow at the top and wide at the bottom. The flash evaporator gas outlet is connected to the side wall of the flash evaporator tapered section.

3. The combined evaporator according to claim 1 or 2, characterized in that: A gas-liquid separation cyclone is connected to the lower part of the evaporator cylinder body. The lower end of the gas-liquid separation cyclone is open and extends to the middle part of the inner cavity of the flash evaporator.

4. The combined evaporator according to claim 3, wherein: Two tangentially outward swirling cyclone exhaust ports are symmetrically connected to the circumference of the middle and lower parts of the gas-liquid separation cyclone.

5. The combined evaporator according to claim 3, characterized in that: The lower part of the evaporator cylinder body is connected to the upper end of the gas-liquid separation cyclone through a tapered section.

6. The combined evaporator according to claim 1, wherein: A distributor is provided in the lower part of the inner cavity of the upper tube sheet box. The upper end of the distributor is open, and a plurality of liquid distribution holes are evenly distributed on the bottom plate of the distributor. The upper end of the upper tube sheet center outlet pipe passes through the center of the bottom plate of the distributor and the upper port is inserted into the oil collecting tank. A plurality of overflow ports are evenly provided on the lower circumference of the oil collecting tank.

7. The combined evaporator according to claim 1, characterized in that: The top of the upper tube sheet center outlet pipe is closed. A plurality of radially outward extending distribution branch pipes are evenly connected to the upper circumference of the upper tube sheet center outlet pipe. Nozzles are respectively provided below the ends of each distribution branch pipe.

8. The combined evaporator according to claim 1, wherein: An evaporator air extraction port is connected to the upper side wall of the evaporator cylinder body.

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