Waste heat recovery system for a molecular distillation apparatus

Abstract

The application provides a waste heat recovery system for a molecular distillation device, which is connected with a heat recovery port of a heat generation source, and comprises a heat recovery assembly, a heat exchange tank, a preheating feed pipe and a plurality of preheating feed branch pipes arranged at the outlet of the preheating feed pipe; the heat exchange tank is internally provided with a heat conduction member, the heat conduction member comprises a heat preservation chamber, the heat preservation chamber is internally provided with a heat transfer medium, the heat conduction member is rotationally arranged in the heat exchange tank, and the heat conduction member is internally provided with a reciprocating feeding structure; the reciprocating feeding structure in the heat conduction member can realize the reciprocating circulation of the heat transfer medium, the heat transfer medium is guided to the required position through the feeding effect, the heat transfer medium in the heat conduction member can realize the tumbling movement through the rotation of the heat conduction member, the heat transfer medium can effectively absorb heat at all positions, and the performance of the heat transfer medium in absorbing heat is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of distillation waste heat recovery equipment, and particularly relates to a waste heat recovery system for molecular distillation equipment. BACKGROUND

[0002] Molecular distillation (also known as short path distillation) is a relatively new liquid-liquid separation technology, which can solve a large number of problems that cannot be solved by conventional distillation technology. A complete molecular distillation equipment mainly includes a molecular evaporator, a degassing system, a feeding system, a heating system, a cooling vacuum system and a control system. The molecular distillation equipment is connected with a feeding pipe and a heavy component buffer tank. The feeding pipe is connected with the feeding system of the molecular distillation equipment, and is used for feeding the molecular distillation equipment. The heavy component buffer tank is used for outputting and buffering the heavy component in the molecular distillation equipment.

[0003] With the increasingly prominent problem of energy shortage, the development of molecular distillation energy-saving technology is imminent. At present, the existing molecular distillation energy-saving technology mostly focuses on the heating method of the molecular distillation equipment and how to improve the heating efficiency of the molecular distillation equipment, but the heat brought out by the heavy component in the molecular distillation process is not fully recovered and utilized, resulting in energy waste.

[0004] In the prior art, although there are some schemes for recovering waste heat, such as the design of winding the feeding pipe on the outer surface of the heavy component buffer tank, so that the heat in the heavy component of the molecular distillation equipment can preheat the feed of the molecular distillation equipment. However, these design schemes have the problems of low heat transfer efficiency and unsatisfactory heat energy collection and reuse.

[0005] Chinese patent CN212789822U discloses a short path molecular distillation equipment, a waste heat recovery pipe is fixedly sleeved on the outer surface of the main body shell, and the waste heat recovery pipe is used for absorbing the heat dissipated to the outside, thereby improving the utilization rate of energy. However, this design can only recover the surface dissipated heat, and cannot recover a large amount of waste heat in the heavy component.

[0006] Chinese patent CN107789853A discloses a distillation system with high-efficiency waste heat recovery, which realizes waste heat recovery of the distillation device by setting a waste heat recovery device, a preheating pipe and a fixing rod and the like components. However, the system has a complex structure, a large number of gas pipelines and limited actual efficiency.

[0007] In summary, the traditional heat exchange equipment mainly has the following problems: since the heat transfer medium of the traditional heat exchanger is mostly in a static or simple flow state, it cannot fully contact with the waste heat, the local thermal resistance is large, the waste heat recovery efficiency is low, a large amount of available heat is not utilized, and the heat exchange is insufficient.

[0008] Therefore, it is urgent to develop a new type of waste heat recovery system for molecular distillation equipment, which can efficiently recover and utilize the waste heat generated in the molecular distillation process, and significantly improve the energy utilization efficiency. SUMMARY

[0009] Therefore, the present application provides a waste heat recovery system for molecular distillation equipment, which can realize the reciprocating circulation of the heat transfer medium through the reciprocating feeding structure in the heat conduction member, so as to realize the efficient and complete absorption of the waste heat by the heat transfer medium, and solve the problem of low waste heat recovery efficiency caused by the static or simple flow state of the heat transfer medium in the traditional heat exchanger, which cannot fully contact with the waste heat, resulting in large amount of available heat not being utilized and insufficient heat exchange.

[0010] To solve the above technical problems, the present application provides a waste heat recovery system for molecular distillation equipment, which is connected to the heat recovery port of the heat source, and includes a heat recovery assembly, the inlet of which is connected to the heat recovery port of the heat source for recovering waste heat.

[0011] The heat exchanger tank also has a plurality of preheating feed branch pipes connected to the side wall thereof, and the preheating feed branch pipes are respectively connected to the inlets of the preheating devices.

[0012] The heat exchanger tank has a heat conduction member arranged therein, and the heat conduction member includes an insulation chamber, and the heat transfer medium is arranged in the insulation chamber.

[0013] The side wall of the heat exchanger tank is a hollow structure, the heat conduction member is rotatably arranged in the heat exchanger tank, the heat conduction member has a reciprocating feeding structure arranged therein, and the reciprocating feeding structure can reciprocally feed the heat transfer medium along the axial direction of the heat conduction member.

[0014] The reciprocating feeding structure comprises a rotating rod connected with an external driving member, and the outer side of the rotating rod is provided with two groups of helical feeding blades with opposite helical directions, the reciprocating feeding operation of the heat conducting medium in the heat conducting member can be realized by the positive and reverse rotation of the output shaft of the driving member, the heat conducting medium can fully and completely absorb the excess heat, and the heat absorption and heat conduction efficiency of the heat conducting medium are improved.

[0015] The heat conducting medium is one or more of sand, quartz stone particles, metal particles or phase change material, the heat conducting medium can be used to realize the efficient absorption of waste heat, and the waste heat can be stored and released, thereby realizing the efficient utilization and recovery of waste heat.

[0016] The heat generating source comprises one or more of a heavy component buffer tank, a distillation tank, a condensation tank, a cooling medium circulation system and a vacuum system; the preheating device comprises one or more of a raw material tank, a distillation tank preheating area, a heat conducting oil tank and a cooling medium storage tank, the heat generated by the heat generating source can be recovered and guided to the preheating device through the communication of the heat exchange tank between the heat generating source and the preheating device, the heat can be efficiently recovered and utilized, the distillation efficiency of the molecular distillation tank is greatly improved, and the energy consumption is saved.

[0017] The preheating feed main pipe and the preheating feed branch pipe are provided with on-off control valves and temperature sensors, and a controller is further arranged, the controller can control the opening and closing of the on-off control valves according to the temperature sensor signals, the temperature monitored by the temperature sensor can be received and processed by the controller, and the opening and closing operation of the on-off control valve can be adjusted in time.

[0018] The hollow side wall of the heat exchange tank is filled with one or more mixed inert gases of argon, nitrogen or helium, the heat preservation performance of the heat exchange tank can be greatly improved by the design of the hollow side wall of the heat exchange tank and the inert gas filled therein, unnecessary heat loss and waste are avoided, and the heat in the heat exchange tank can be well stored and continuously discharged.

[0019] The driving member is a servo motor or a stepping motor, which can drive the rotating rod to rotate in positive and reverse directions.

[0020] One end of the rotating rod penetrates through the side wall of the heat exchange tank, and a rotating sealing element is arranged at the position combined with the side wall of the heat exchange tank, the rotating sealing element can realize the sealing performance of the contact position of the rotating rod and the heat exchange tank without affecting the rotation of the rotating rod.

[0021] The outer sides of the preheating feed main pipe and the preheating feed branch pipe are wrapped with thermal insulation layers, and the application can realize heat preservation of the waste heat circulating in the pipeline through the effect of the thermal insulation layers wrapped outside the preheating feed main pipe and the preheating feed branch pipe, avoids unnecessary dissipation, and greatly improves the waste heat recovery efficiency.

[0022] Compared with the prior art, the application has at least one of the following beneficial technical effects:

[0023] 1. Improve waste heat recovery efficiency and heat exchange efficiency: the application can realize reciprocating conveying of the heat transfer medium by using the reciprocating conveying structure and the high-efficiency heat transfer medium in combination, greatly improve the heat absorption capacity of the heat transfer medium, significantly improve the waste heat recovery efficiency and the heat exchange uniformity, and solve the problem of insufficient heat exchange of the traditional system.

[0024] 2. Improve heat preservation performance and reduce unnecessary dissipation of heat in recovered waste heat: the application adopts the double heat preservation design of the inert gas filled hollow wall and the external thermal insulation layer, effectively reduces the heat loss in the waste heat recovery process, and improves the system thermal efficiency.

[0025] 3. Intelligent temperature control, greatly improve heat recovery and utilization efficiency: the application can realize accurate control of the temperature in the waste heat recovery system through precise cooperation of the temperature sensor and the controller, and ensure process stability.

[0026] 4. Stably and uniformly realize heat recovery and conduction: the application can realize reciprocating movement of the heat transfer medium through the design of the rotating rod and the two groups of spiral conveying blades with opposite directions, realize uniform, stable and comprehensive recovery and storage of waste heat for the heat transfer medium, and also avoid the problems of medium sintering and caking, prolonging the service life of the system.

[0027] 5. The application can realize tumbling movement of the heat transfer medium inside the heat conducting part through the rotating setting of the heat conducting part, facilitate effective heat absorption operation of each part of the heat transfer medium, and improve the heat absorption performance of the heat transfer medium.

[0028] 6. The application can realize effective blocking of heat loss through the thermal insulation layer arranged outside the preheating feed main pipe and the preheating feed branch pipe, further improve the waste heat utilization efficiency, and reduce unnecessary heat loss. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a structural schematic view of the molecular distillation equipment and the waste heat recovery system of the application;

[0030] Figure 2 It is a front view of the molecular distillation equipment and the waste heat recovery system of the application;

[0031] Figure 3 This is a schematic diagram of a portion of the waste heat recovery system for the molecular distillation equipment of the present invention;

[0032] Figure 4 This is a front view of a portion of the waste heat recovery system for the molecular distillation apparatus of the present invention;

[0033] Figure 5 For the present invention Figure 4 Sectional view at point AA;

[0034] Figure 6 This is a schematic diagram of the reciprocating conveying structure in a portion of the waste heat recovery system for the molecular distillation equipment of the present invention.

[0035] Figure 7 This is a system schematic diagram of the molecular distillation equipment and waste heat recovery system of the present invention.

[0036] Explanation of reference numerals in the attached drawings: 100, heat source; 200, heat recovery assembly; 300, heat exchange tank; 310, heat-conducting component; 311, insulation chamber; 312, heat transfer medium; 320, reciprocating conveying structure; 321, driving component; 322, rotating rod; 323, spiral conveying blade; 324, rotating seal; 400, preheating feed main pipe; 500, preheating feed branch pipe; 600, insulation layer. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figures 1-7 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0038] like Figures 1-7 As shown: This embodiment provides a waste heat recovery system for a molecular distillation apparatus. The waste heat recovery system is connected to the heat recovery port of the heat generation source 100. The waste heat recovery system includes a heat recovery component 200, the inlet of which is connected to the heat recovery port of the heat generation source 100 for recovering waste heat.

[0039] It also includes a heat exchange tank 300, whose inlet is connected to the outlet of the heat recovery component 200, and a preheating feed main pipe 400 is provided at its outlet; the heat exchange tank 300 is also provided with several preheating feed branch pipes 500 connected to its side wall, and the preheating feed branch pipes 500 are respectively connected to the inlet of the device to be preheated.

[0040] According to one embodiment of the present invention, such as Figure 1 ,Figure 4 and Figure 5 As shown in the drawings, the inside of the heat exchange tank 300 is provided with a heat conduction piece 310, the heat conduction piece 310 comprises a heat preservation chamber 311, the inside of the heat preservation chamber 311 is provided with a heat transfer medium 312,

[0041] Specifically, one embodiment of the heat conduction piece 310 is that the heat conduction piece 310 comprises a sealed heat preservation cavity, which is filled with a composite heat transfer medium 312, the heat transfer medium 312 is a mixture of expanded graphite and a composite phase change material, the composite phase change material is a granular spherical body or a granular regular shape formed by mixing paraffin, stearic acid and nano aluminum powder, and the phase change temperature interval can be adjusted to 50-120℃; the inner wall of the heat preservation cavity is sprayed with a graphene heat conduction coating.

[0042] Another embodiment of the heat conduction piece 310 is that the heat conduction piece 310 adopts an oxygen-free copper-graphene composite material, and since the thermal conductivity of the material is above 420W / (m·K), the heat can be quickly transferred. The inside of the heat conduction piece 310 is a sealed heat preservation cavity, which is filled with a composite heat transfer medium 312 composed of expanded graphite, paraffin-stearic acid composite phase change material and carbon nanotubes: the expanded graphite provides a porous network structure to enhance the heat conductivity of the medium; the paraffin-stearic acid composite phase change material realizes heat storage and buffering through phase change latent heat; and the added carbon nanotubes further improve the heat transfer coefficient. The graphene coating sprayed on the inner wall of the heat preservation cavity forms an efficient heat conduction path to ensure uniform distribution of heat.

[0043] The application can realize the centralized and efficient recovery operation of the excess heat generated by the heat generation source 100 through the heat exchange tank 300 in the waste heat recovery system, has a simple structure, can fully and efficiently collect the waste heat of each part in the distillation process of the molecular distillation equipment, greatly improves the efficiency of the molecular distillation, and avoids unnecessary heat loss.

[0044] According to one embodiment of the application, as Figure 4 and Figure 5As shown, the side wall of the heat exchange tank 300 is a hollow three-layer composite structure, the inner layer is a nickel-based superalloy, the middle layer is an aluminum silicate fiber insulation layer 600, and the outer layer is a 304 stainless steel protective layer; The tank body side wall is provided with a hollow interlayer, which is filled with a mixed heat preservation body of argon gas with a purity of 99.99% and nanometer aerogel. The low thermal conductivity of argon gas and the high thermal resistance characteristics of nanometer aerogel work together to greatly reduce the heat loss rate of the tank body. The heat conducting part 310 is rotatably arranged in the heat exchange tank 300. The heat conducting part 310 is provided with a reciprocating feeding structure 320 inside. The reciprocating feeding structure 320 can reciprocally convey the heat transfer medium 312 along the axial direction of the heat conducting part 310. The present application can realize the reciprocating circulation of the heat transfer medium 312 through the reciprocating feeding structure 320 in the heat conducting part 310, so as to realize the efficient and complete absorption of the waste heat by the heat transfer medium 312, and guide it to the required position through the conveying effect. At the same time, through the rotating arrangement of the heat conducting part 310, the tumbling movement of the heat transfer medium 312 in the heat conducting part 310 can be realized, so as to realize the effective heat absorption of all parts of the heat transfer medium 312, and improve the performance of the heat transfer medium 312 to absorb heat more fully and efficiently.

[0045] According to one embodiment of the present application, as Figure 6 As shown, the reciprocating feeding structure 320 includes a rotating rod 322 in transmission connection with an external driving member 321. The outer side of the rotating rod 322 is provided with two groups of spiral feeding blades 323 with opposite spiral directions. The material of the rotating rod 322 is silicon nitride ceramic material, which has the characteristics of high temperature resistance and low friction. The two groups of opposite spiral blades arranged symmetrically on the outer side of the rotating rod 322 realize forward and reverse rotation alternately under the driving of the servo motor. Specifically, when the rotating rod 322 rotates forward, one group of blades pushes the heat transfer medium 312 to the inside of the tank body; when it reverses, the other group of blades pushes the medium to the outside. The disturbance holes on the surface of the blades make the medium form strong reciprocating disturbance and tumbling movement, avoiding the formation of local thermal resistance. The servo motor realizes stepless speed regulation through a precision reducer, and can dynamically adjust the disturbance strength according to the waste heat load. The present application can realize efficient and portable reciprocating conveying of the heat conducting medium in the heat conducting part 310 through the forward and reverse rotation of the output shaft of the driving member 321, so as to facilitate the heat conducting medium to fully and completely absorb the excess heat, and further improve the efficiency of heat absorption and heat conduction of the heat conducting medium.

[0046] Specifically, the phase change temperature range of the heat transfer medium 312 is 50-120℃, and the heat transfer medium 312 is one or more of sand, quartz stone particles, metal particles or phase change materials. The present application can realize the efficient absorption of waste heat by the heat transfer medium 312, and store and release it, so as to realize the efficient utilization and recovery of waste heat.

[0047] According to one embodiment of the present application, as Figure 1 andFigure 7 As shown, the heat generating source 100 includes one or more of a heavy component buffer tank, a distillation tank, a condensation tank, a cooling medium circulation system and a vacuum system; the device to be preheated includes one or more of a raw material tank, a distillation tank preheating area, a heat conducting oil tank and a cooling medium storage tank. The application can realize the recycling of the waste heat generated by the heat generating source 100 and the guided use of the waste heat in the device to be preheated through the communication between the heat generating source 100 and the device to be preheated through the heat exchange tank 300, realize the efficient recycling and utilization of heat, greatly improve the distillation efficiency of the molecular distillation tank and save energy consumption.

[0048] The preheating feed main pipe 400 and the preheating feed branch pipe 500 are both provided with on-off control valves and temperature sensors, and further include a controller which can control the opening and closing of the on-off control valves according to the temperature sensor signals, wherein the controller is selected from the Siemens S7-1200 series controller, the temperature sensor is selected from the Siemens QAE2120.010 temperature sensor, and the on-off control valve is selected from the Aska EF8320G174 on-off control valve. The application can realize the receiving and processing of the temperature monitored by the temperature sensor through the controller, and can timely adjust the opening and closing operation of the on-off control valve.

[0049] The hollow side wall of the heat exchange tank 300 is filled with one or more mixed inert gases such as argon, nitrogen or helium. The design of the hollow side wall of the heat exchange tank 300 in cooperation with the inert gas filled therein can greatly increase the heat preservation performance of the heat exchange tank 300, avoid unnecessary heat loss and waste, and realize good heat storage and continuous discharge operation in the heat exchange tank 300.

[0050] According to one embodiment of the application, as shown in Figure 1 、 Figure 2 、 Figure 4 and Figure 5 The driving member 321 is a servo motor or a stepping motor, which can drive the rotating rod 322 to rotate in forward and reverse directions. The driving member 321 is a Delta ASD-A2-0421-M type servo motor, which drives the rotating rod 322 through a precision reducer to realize stepless speed regulation and forward and reverse switching.

[0051] One end of the rotating rod 322 penetrates through the side wall of the heat exchange tank 300, and the position combined with the side wall of the heat exchange tank 300 is provided with a rotating seal 324, which adopts a bellows mechanical seal assembly, a polytetrafluoroethylene-metal bellows composite structure cooperates with a silicon carbide wear-resistant ring, so that zero leakage can be realized in the pressure range of -0.1MPa to 0.6MPa, and the sealing requirement of high-frequency forward and reverse rotation of the rotating rod 322 can be met, and the rotating seal 324 can realize the sealing performance of the contact part of the rotating rod 322 and the heat exchange tank 300 without affecting the rotation of the rotating rod 322.

[0052] The outer sides of the preheating feed main pipe 400 and the preheating feed branch pipe 500 are wrapped with a heat preservation layer 600, the preheating feed main pipe 400 and the preheating feed branch pipe 500 are responsible for accurately distributing the recovered heat to each device to be preheated, and adopt a three-layer composite pipe design, specifically, the inner layer is a PTFE corrosion-resistant layer to resist material corrosion, the middle layer is a red copper heat-conducting layer to strengthen heat transfer, and the outer layer is a polyurethane foaming heat preservation layer 600 to reduce heat loss along the way. The externally wrapped heat preservation layer 600 is a high-reflectivity aluminum foil for further reducing radiation heat dissipation. The preheating feed main pipe 400 is connected to different devices to be preheated through a plurality of preheating feed branch pipes 500, wherein high-temperature waste heat is preferentially supplied to a distillation feed preheater, then to a heat conducting oil tank, medium-temperature waste heat is supplied to a raw material pretreatment tank, then to a distillation tank, and low-temperature waste heat is supplied to a raw material tank, so as to realize step-by-step matching utilization of heat. The preheating feed main pipe 400 and the preheating feed branch pipe 500 can realize heat preservation of the waste heat flowing in the pipeline by the effect of the heat preservation layer 600 wrapped outside, avoid unnecessary dissipation, and greatly improve the efficiency of waste heat recovery.

[0053] The use method of the present application is as follows:

[0054] First of all, it needs to be clear that the waste heat recovery system involved in the present application is mainly used for the centralized recovery and reuse of excess heat in the working process of molecular distillation equipment, and the working principle and use method thereof are described in detail taking the waste heat recovery in the distillation process of chemical products as an example.

[0055] The working principle is as follows:

[0056] The working principle of the waste heat recovery system of the molecular distillation equipment of the present application is based on the whole process design of "waste heat collection - high-efficiency heat exchange - intelligent control - step-by-step utilization", and the specific steps are as follows:

[0057] Waste heat collection stage: the waste heat generated by the heavy component buffer tank, distillation tank and other heat sources 100 of the molecular distillation equipment is discharged through the heat recovery port and enters the heat recovery assembly 200; the heat recovery assembly 200 separates the waste heat from the exhaust gas through the tube-shell heat exchange structure, and delivers the waste heat to the heat exchange tank 300 through the pipeline.

[0058] High-efficiency heat exchange stage:

[0059] After the waste heat enters the heat exchange tank 300, it comes into contact with the heat-conducting part 310 arranged in rotation; the oxygen-free copper-graphene material or graphene coating of the heat-conducting part 310 quickly conducts heat to the internal heat transfer medium 312.

[0060] The controller starts the servo motor of the ASD-A2-0421-M, driving the silicon nitride ceramic rotating shaft 322 to run alternately in forward and reverse directions: when rotating forward, a group of spiral feed blades 323 pushes the heat transfer medium 312 to the inside of the tank, and when rotating in reverse, another group of blades pushes the medium to the outside; the turbulence holes on the surface of the blades intensify the disturbance of the medium, making the medium roll over in reciprocating motion and fully contact with heat, avoiding local thermal resistance; the porous network structure of expanded graphite and the high thermal conductivity of carbon nanotubes further improve the heat absorption efficiency of the medium, and the paraffin-stearic acid composite phase change material realizes heat storage and buffering through the latent heat of phase change.

[0061] Heat preservation and loss prevention stage:

[0062] The hollow three-layer side wall of the heat exchange tank 300 cooperates with the argon and nano aerogel mixed heat preservation body in the interlayer through the synergistic effect of nickel-based high-temperature alloy temperature resistance, aluminum silicate fiber heat preservation, and 304 stainless steel protection, effectively blocking the loss of heat to the outside of the tank.

[0063] The bellows mechanical seal assembly at the junction of the rotating shaft 322 and the tank wall realizes zero leakage within a certain pressure range, while meeting the sealing needs of the high-frequency forward and reverse rotation of the rotating shaft 322; the three-layer composite structure of the preheating delivery pipeline and the outer aluminum foil heat preservation layer 600 reduce heat loss during the delivery process.

[0064] Intelligent control stage:

[0065] The temperature sensors on the preheating feed main pipe 400 and branch pipes detect the waste heat temperature in real time and transmit the signal to the controller; the controller controls the opening and closing of the switch control valve according to the preset temperature requirement of the device to be preheated, realizing accurate heat supply.

[0066] When the temperature sensor detects a change in waste heat load, the controller adjusts the speed of the servo motor to change the disturbance intensity of the heat transfer medium 312, ensuring that the heat exchange efficiency matches the waste heat load.

[0067] The controller divides the waste heat according to the temperature detected by the temperature sensor: when the temperature is between 50-120℃, the waste heat flows and is distributed as follows: the high-temperature waste heat of 100-120℃ is preferentially supplied to the distillation feed preheater and the heat conducting oil tank, the medium-temperature waste heat of 70-100℃ is supplied to the raw material pretreatment tank and the distillation tank, and the low-temperature waste heat of 50-70℃ is supplied to the raw material tank, so as to realize the reasonable matching of waste heat of different grades and maximize the energy utilization efficiency.

[0068] The use method is as follows:

[0069] The system is installed as follows:

[0070] The inlet of the heat recovery assembly 200 is sealed and connected to the heat recovery port of the heavy component buffer tank, the distillation tank and other heat sources 100 of the molecular distillation equipment through flanges to ensure that the interface is leakproof.

[0071] The outlet of the heat recovery assembly 200 is connected to the inlet of the heat exchange tank 300 by a pipeline, and the pipeline adopts the same three-layer composite structure as the preheating conveying pipeline, and is wrapped with an aluminum foil heat preservation layer 600 on the outside.

[0072] A heat conducting member 310 is installed inside the heat exchange tank 300, one end of the rotating rod 322 of the heat conducting member 310 penetrates the side wall of the heat exchange tank 300, a corrugated pipe mechanical seal assembly is installed at the penetration position, and the rotating rod 322 is connected to the precision reducer output shaft of the TIDA ASD-A2-0421-M servo motor.

[0073] The preheating feed main pipe 400 is connected to the outlet of the heat exchange tank 300, one end of each preheating feed branch pipe 500 is connected to the preheating feed main pipe 400, and the other end is respectively connected to the inlet of the raw material tank, the distillation feed preheater and other preheating devices.

[0074] Temperature sensors and on-off control valves are installed on the preheating feed main pipe 400 and each branch pipe, and the temperature sensors, on-off control valves and servo motors are respectively electrically connected to the controller to complete the wiring of the electric control system.

[0075] The system debugging is as follows:

[0076] The sealing performance of each pipeline interface and rotating seal 324 is checked, 99.99% argon gas and nanometer aerogel mixture are filled into the hollow side wall interlayer of the heat exchange tank 300 to ensure the sealing of the interlayer.

[0077] Composite heat transfer medium 312 is filled into the sealed and heat-insulated cavity of the heat conducting member 310, and the corresponding heat conducting member 310 implementation is selected according to the waste heat temperature (high-temperature oxygen-free copper-graphene material, medium-temperature graphene coating cavity).

[0078] Start the controller, test the servo motor forward and reverse function and speed regulation range, observe the spiral conveying blade 323 driven by the heat transfer medium 312 reciprocating disturbance, to ensure that the medium is not stuck.

[0079] Calibration temperature sensor, set the temperature threshold of each preheating device, test controller according to temperature signal control switch control valve opening and closing response speed, to ensure accurate control.

[0080] The waste heat recovery operation in the molecular distillation process is as follows:

[0081] Start the molecular distillation equipment and the waste heat recovery system, and the heat recovery assembly 200 starts to collect the waste heat of the heat source 100 and introduces it into the heat exchange tank 300.

[0082] The controller automatically adjusts the servo motor speed according to the waste heat temperature detected by the temperature sensor, controls the disturbance intensity of the heat transfer medium 312, and controls the opening and closing of each switch control valve, so that the waste heat at different temperatures is supplied to the preheating device through the corresponding preheating feed branch pipe 500.

[0083] During operation, the controller monitors the temperature of each part, the running state of the servo motor and the medium disturbance in real time, records the waste heat recovery amount and energy saving data.

[0084] Maintenance:

[0085] Check the wear of the rotating seal 324 every week, and replace the polytetrafluoroethylene-metal corrugated pipe or silicon carbide wear ring in time if there is any sign of leakage.

[0086] Clean the heat transfer medium 312 in the heat conducting part 310 every month, check if there are any lumps, and if there are lumps, break or replace the medium to ensure the heat exchange efficiency.

[0087] Check the inert gas pressure of the heat exchange tank 300 side wall interlayer every quarter, and if the pressure is insufficient, supplement the corresponding inert gas; check the insulation layer 600 of the waste heat conveying pipeline, and if there is any damage, repair or replace it in time.

[0088] Maintain the servo motor, controller and other electrical components every year, clean the dust, check the contact condition of the wiring terminal, and ensure the stable operation of the electrical control system.

[0089] The process of molecular distillation is briefly described as follows:

[0090] The raw material first enters the stirring tank, is preliminarily mixed and homogenized, and is then pumped into the waste heat recovery system by a feeding pump. The raw material first passes through a low-temperature preheater, is preheated from room temperature to about 40 DEG C by using the low-temperature waste heat in the cooling water circuit, then enters a medium-temperature preheater, is heated to about 70 DEG C by using the medium-temperature waste heat of the condensing system and the vacuum system, and finally enters a high-temperature preheater, is heated to about 120 DEG C by using the high-temperature waste heat of the heavy component.

[0091] The raw material preheated in three stages enters a molecular distillation tank, forms a uniform film on the heating surface by a spiral scraper in the tank, and is distilled under high temperature and high vacuum. During the distillation process, the light component evaporates, enters the condensing system, is condensed into a liquid by a double-spiral condenser, and is collected into a distillate buffer tank; the heavy component flows down along the heating surface and is collected into a heavy component buffer tank.

[0092] The heavy component buffer tank is provided with a plate heat exchange element. After the high-temperature heavy component enters the buffer tank, part of the heat is transferred to the raw material by the heat exchange element, and the temperature of the heavy component is reduced from about 200 DEG C to about 150 DEG C, and then the heavy component is discharged from the system or enters the next processing procedure. This process recovers about 60% of the heat energy in the heavy component, and significantly improves the heat efficiency of the system.

[0093] A heat conducting oil furnace provides the main heat required by the system, and the heat conducting oil circulates in a closed loop. An expansion tank provided in the system is used to adjust the volume change of the heat conducting oil, so that the system pressure is stable. A temperature sensor network monitors the temperature change of each key point of the system in real time, and transmits the data to an intelligent control system. The system automatically adjusts the opening degree of the valve group and the power of the pump group according to the data, so as to optimize the running state of the system.

[0094] The vacuum system is composed of an oil diffusion pump and a vacuum unit, and establishes and maintains the high vacuum environment required by the system. The exhaust heat of the vacuum system is recovered by an exhaust heat recovery device, and is used for preheating the inlet water.

[0095] The system is also provided with a nitrogen gas pipeline, which is used for purging before starting and cleaning before stopping, so as to ensure the safe operation of the system. Straight-through view mirrors are arranged at key positions, so as to facilitate the observation of the material state and flow condition. Special gaskets are used at all flange connections, so as to ensure the sealing performance of the system under high vacuum conditions.

[0096] The present application can realize the reciprocating circulation of the heat transfer medium 312 through the reciprocating feeding structure 320 in the heat conducting element 310, so as to realize the efficient and complete absorption and energy storage of the waste heat by the heat transfer medium 312, and solve the problems of the conventional heat exchanger, i.e. the heat transfer medium 312 is mostly in a static or simple flow state, cannot fully contact with the waste heat, the local thermal resistance is large, the waste heat recovery efficiency is low, a large amount of available heat is not utilized, and the heat exchange is insufficient.

[0097] In addition, it needs to be explained that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0098] The above is the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can also be made, which should be considered as the protection scope of the present application.

Claims

1. A waste heat recovery system for a molecular distillation apparatus, the waste heat recovery system being in communication with a heat generating source (100) at a heat recovery port, characterized in that: The waste heat recovery system comprises a heat recovery assembly (200) which is connected to a heat recovery port of a heat generating source (100) for recovering waste heat; The waste heat recovery system further comprises a heat exchange tank (300) which is connected to an outlet of the heat recovery assembly (200) and is provided with a preheating feed main pipe (400) at an outlet thereof; the heat exchange tank (300) is further provided with a plurality of preheating feed branch pipes (500) which are connected to inlets of devices to be preheated; The heat exchange tank (300) is internally provided with a heat conducting member (310) which comprises a heat preservation chamber (311) internally provided with a heat transfer medium (312); The heat exchange tank (300) has a hollow structure, and the heat conducting member (310) is rotatably arranged in the heat exchange tank (300); the heat conducting member (310) is internally provided with a reciprocating feed structure (320) for reciprocatingly feeding the heat transfer medium (312) in an axial direction of the heat conducting member (310); The reciprocating feed structure (320) comprises a rotating rod (322) which is drivingly connected to an external driving member (321); the rotating rod (322) is externally provided with two groups of helical feed blades (323) which have opposite helical directions; The heat transfer medium (312) is one or more of sand, quartz stone particles, metal particles or phase change materials; The hollow side wall of the heat exchange tank (300) is internally filled with one or more mixed inert gases of argon, nitrogen or helium.

2. The waste heat recovery system for a molecular distillation apparatus according to claim 1, characterized by: The heat generating source (100) comprises one or more of a heavy component buffer tank, a distillation tank, a condensation tank, a cooling medium circulation system and a vacuum system; the device to be preheated comprises one or more of a raw material tank, a distillation tank preheating area, a heat conducting oil tank and a cooling medium storage tank.

3. The waste heat recovery system for a molecular distillation apparatus according to claim 2, characterized by: The preheating feed main pipe (400) and the preheating feed branch pipes (500) are both provided with on-off control valves and temperature sensors, and further comprise a controller which can control the opening and closing of the on-off control valves according to signals of the temperature sensors.

4. The waste heat recovery system for a molecular distillation apparatus according to claim 1, characterized by: The driving member (321) is a servo motor or a stepping motor which can drive the rotating rod (322) to rotate in forward and reverse directions.

5. The waste heat recovery system for a molecular distillation apparatus according to claim 4, characterized by: One end of the rotating rod (322) penetrates through the side wall of the heat exchange tank (300), and a rotating sealing member (324) is arranged at a position where the rotating rod (322) is combined with the side wall of the heat exchange tank (300).

6. The waste heat recovery system for a molecular distillation apparatus as claimed in claim 1, wherein: The preheating feed main pipe (400) and the preheating feed branch pipes (500) are both wrapped with a heat preservation layer (600).

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