Vertical double-floating-head finned tube kerosene heat exchanger

Abstract

The application discloses a vertical double-floating-head finned tube kerosene heat exchange device, and solves the technical problems of low heat exchange efficiency, poor heat exchange stability and poor economy of an existing liquid nitrogen cold bath type spiral tube heat exchanger. The heat exchange device comprises a supporting unit, a lower floating head, a first heat exchange unit, a second heat exchange unit, an upper floating head and a connecting pipe. The first heat exchange unit is vertically installed on the supporting unit, and the lower floating head is installed at the bottom of the first heat exchange unit. The second heat exchange unit is installed on the top of the first heat exchange unit through a connecting ring, and the first heat exchange unit, the connecting ring and the second heat exchange unit surround a gas collecting cavity, and the upper floating head is installed at the top of the second heat exchange unit. A plurality of first heat exchange pipes are uniformly distributed in the first heat exchange unit, and finned tubes are sleeved on part of the first heat exchange pipes. A plurality of second heat exchange pipes are uniformly distributed in the second heat exchange unit, and finned tubes are sleeved on part of the second heat exchange pipes. The connecting pipe is used for connecting the first heat exchange unit and the second heat exchange unit. The heat exchange device has high heat exchange efficiency and liquid nitrogen utilization rate.

Description

TECHNICAL FIELD

[0001] The present application relates to a kerosene heat exchange device, in particular to a vertical double-floating-head finned tube kerosene heat exchange device. BACKGROUND

[0002] With the rapid development of civil aerospace launch technology, new civil launch rockets using kerosene as propellant have become the mainstream product. Due to the influence of the environmental temperature of the launch site, there is a difference between the initial temperature of the kerosene propellant and its optimal working temperature in the rocket engine, which needs to be adjusted by heat exchange, which makes the test system and launch system of the rocket engine need to have reliable and rapid kerosene supercooling capacity.

[0003] The kerosene heat exchanger used in the existing test system and launch system is a liquid nitrogen cold bath type spiral tube kerosene heat exchanger. The heat exchanger is to pass kerosene into the spiral tube to exchange heat with the saturated liquid nitrogen in the shell (outside the spiral tube), and to cool the kerosene to the required temperature by multiple cycles. However, such heat exchanger has the following defects:

[0004] (1) Low heat exchange efficiency: during the flow of kerosene in the spiral tube, it is easy to freeze and block. Usually, a large flow multiple (at least 2-4 times) cycle heat exchange process is required to make the kerosene reach the required temperature without freezing, which leads to low heat exchange efficiency. In addition, the heat exchange system pipeline of such heat exchanger is complex, the pipeline arrangement is more complicated, and the heat exchange process operation is complex, which seriously affects the kerosene thermal boundary condition test and the launch efficiency of the launch site.

[0005] (2) Poor heat exchange stability: since the liquid nitrogen cold bath type spiral tube heat exchanger is kerosene flowing in the spiral tube, the kerosene flow resistance of the entire heat exchange system is mainly concentrated in the heat exchanger. In the late stage of system circulation, with the decrease of kerosene temperature, the viscosity of kerosene rises sharply, which seriously limits the flow of circulating pump, affects the maximum heat exchange capacity of the heat exchanger, and leads to poor heat exchange stability and large heat exchange power fluctuation, which ultimately makes it difficult to quantitatively control the heat exchange process.

[0006] (3) Poor economy: when using the vaporization heat absorption of saturated liquid nitrogen to quickly cool the kerosene in the spiral tube, in addition to the utilization of the latent heat of vaporization of saturated liquid nitrogen, the vaporized liquid nitrogen vapor is directly exhausted, so that half of the cold energy is wasted in the process of changing the normal pressure saturated liquid nitrogen into-60℃ cold nitrogen gas. The utilization rate of liquid nitrogen is low, and the economy is poor. SUMMARY

[0007] The present application aims to solve the technical problems of low heat exchange efficiency, poor heat exchange stability and poor economy of the existing liquid nitrogen cold bath type spiral tube kerosene heat exchanger, and provides a vertical double-floating-head finned tube kerosene heat exchange device.

[0008] To achieve the above object, the technical solution provided by the present application is as follows:

[0009] The vertical double-floating-head finned tube kerosene heat exchange device has the special features that it comprises a supporting unit, a lower floating head, a first heat exchange unit, a second heat exchange unit, an upper floating head and a connecting pipe.

[0010] The first heat exchange unit is vertically installed on the supporting unit; the lower floating head is installed at the bottom of the first heat exchange unit and is provided with a first inlet for introducing liquid nitrogen.

[0011] The second heat exchange unit is coaxially installed on the top of the first heat exchange unit through a connecting ring and surrounds a gas collection cavity together with the first heat exchange unit and the connecting ring; the upper floating head is installed at the top of the second heat exchange unit and is provided with a first outlet for discharging nitrogen gas.

[0012] A plurality of first heat exchange tubes are uniformly distributed in the first heat exchange unit, both ends of each first heat exchange tube are communicated with the lower floating head and the gas collection cavity respectively, and part of the first heat exchange tubes are sleeved with finned tubes; a plurality of second heat exchange tubes are uniformly distributed in the second heat exchange unit, both ends of each second heat exchange tube are communicated with the upper floating head and the gas collection cavity respectively, and part of the second heat exchange tubes are sleeved with finned tubes.

[0013] The second heat exchange unit is provided with a second inlet and a second outlet along the radial direction, which are respectively used for the first introduction and discharge of the kerosene to be heat exchanged; the first heat exchange unit is provided with a third inlet and a third outlet along the radial direction, which are respectively used for the second introduction and discharge of the kerosene to be heat exchanged; both ends of the connecting pipe are connected with the second outlet and the third inlet, so as to communicate the first heat exchange unit and the second heat exchange unit.

[0014] Further, the first heat exchange unit comprises a first shell, a first flange tube plate, a first tube plate, a first baffle assembly and a lower head.

[0015] The first shell is vertically installed on the supporting unit and has a cylindrical structure, a plurality of first heat exchange tubes are uniformly distributed in the cylindrical structure along the axial direction; the first flange tube plate and the first tube plate are respectively used for fixing both ends of each first heat exchange tube; one end of the first flange tube plate is coaxially connected with the connecting ring, and the other end is connected with the top of the first shell; the lower head is installed at the bottom of the first shell and is provided with a lower sealing opening; the first tube plate and the lower floating head are coaxially connected and both have a radial gap with the inner wall of the first shell; the lower floating head has an axial gap with the lower head, the first inlet is coaxial with the lower sealing opening and is smaller than the diameter of the lower sealing opening; the third inlet is located at the first shell close to the first flange tube plate, and the third outlet is located at the first shell close to the first tube plate.

[0016] The first baffle assembly comprises a plurality of first baffle plates arranged in parallel and at equal intervals; each of the first baffle plates is a perforated circular plate structure, is installed on the inner wall of the first shell in the radial direction, and is adapted to the inner diameter of the first shell; one notch is arranged on each side edge of each first baffle plate, and the notches on adjacent two first baffle plates are arranged symmetrically in the horizontal direction, and the plurality of first baffle plates divide the inner cavity of the first shell into S-shaped channels.

[0017] The first heat exchange tube of the sleeved finned tube is located in the middle of the first shell and vertically penetrates each first baffle plate, and a heat insulation sleeve is sleeved between the first heat exchange tube and the corresponding finned tube; the first heat exchange tube without the sleeved finned tube is arranged close to the inner wall of the first shell, vertically penetrates the corresponding first baffle plate, and is located in the axial space where the notch of the first baffle plate is located, and the heat insulation sleeve and the light sleeve are sleeved on the first heat exchange tube from inside to outside.

[0018] Further, the second heat exchange unit comprises a second shell, a second flange tube plate, a second tube plate, a second baffle assembly and an upper head;

[0019] The second shell is a cylindrical structure, and a plurality of second heat exchange tubes are uniformly distributed in the cylindrical structure in the axial direction; the second flange tube plate and the second tube plate are used for fixing two ends of each second heat exchange tube respectively; one end of the second flange tube plate is coaxially connected with the connecting ring, and the other end is connected with the bottom of the second shell; the upper head is installed on the top of the second shell, and the upper head is provided with an upper sealing opening; the second tube plate and the upper head are coaxially connected and both leave a radial gap with the inner wall of the second shell; an axial gap is left between the upper head and the upper head, the first outlet is coaxial with the upper sealing opening and smaller than the caliber of the upper sealing opening; the second inlet is located close to the second tube plate of the second shell, and the second outlet is located close to the second flange tube plate of the second shell;

[0020] The second baffle assembly comprises a plurality of second baffle plates arranged in parallel and at equal intervals; each of the second baffle plates is a perforated circular plate structure, is installed on the inner wall of the second shell in the radial direction, and is adapted to the inner diameter of the second shell; one notch is arranged on each side edge of each second baffle plate, and the notches on adjacent two second baffle plates are arranged symmetrically in the horizontal direction, and the plurality of second baffle plates divide the inner cavity of the second shell into S-shaped channels;

[0021] The second heat exchange tube of the sleeved finned tube is located in the middle of the second shell and vertically penetrates each second baffle plate; the second heat exchange tube without the sleeved finned tube is arranged close to the inner wall of the second shell, vertically penetrates the corresponding second baffle plate, and is located in the axial space where the notch of the second baffle plate is located, and the light sleeve is sleeved on the second heat exchange tube.

[0022] Further, the first shell is provided with a first observation window close to the lower head;

[0023] The second shell is provided with a second observation window near the second flange tube plate.

[0024] Further, the upper floating head and the lower floating head are respectively provided with bellows compensators connected with the upper head and the lower head.

[0025] Further, the connecting ring is provided with overflow ports in the radial direction.

[0026] Further, the heat insulation sleeve on the first heat exchange pipe is gap-fitted with the corresponding finned tube, and the fitted gap is 0.1mm-0.4mm.

[0027] The second heat exchange pipe is gap-fitted with the corresponding finned tube, and the fitted gap is 0.1mm-0.4mm.

[0028] The first baffle plate and the second baffle plate are gap-fitted with the two end portions of the corresponding finned tube in the radial direction, and the fitted gap is 0.1mm-0.2mm.

[0029] Further, the first tube plate is provided with a heat insulation layer away from one end of the lower floating head.

[0030] Further, the first shell is provided with a temperature adjusting device near the third outlet, and a temperature sensor connected with the temperature adjusting device; the temperature adjusting device is used for adjusting the outflow temperature of kerosene, and the temperature sensor is used for monitoring the outflow temperature.

[0031] Further, the finned tube is a spiral finned tube or a ring-shaped finned tube, and is a sectional structure.

[0032] The material of the heat insulation sleeve and the heat insulation layer is polytetrafluoroethylene.

[0033] The first heat exchange pipe, the second heat exchange pipe and the light sleeve are stainless steel pipes.

[0034] The present application has the following beneficial effects:

[0035] 1、The present application divides the heat exchange region into a first heat exchange unit and a second heat exchange unit, wherein the first heat exchange unit is vertically installed on the support unit, the second heat exchange unit is coaxially installed on the top of the first heat exchange unit through the connecting ring, and the lower floating head and the upper floating head are respectively installed on the ends of the first heat exchange unit and the second heat exchange unit away from each other.

[0036] 2. The first heat exchange unit of the present invention is a liquid nitrogen heat exchange zone, and the second heat exchange unit is a nitrogen heat exchange zone. Combining the liquid nitrogen / nitrogen heat exchange coefficient and kerosene heat exchange coefficient of different zones, compared with the traditional liquid nitrogen cold bath type spiral tube kerosene heat exchanger which only utilizes the cooling capacity of liquid nitrogen, the present invention makes great use of the cooling capacity of cold nitrogen, thereby improving the utilization rate of liquid nitrogen.

[0037] 3. The vertical structure of this invention, combined with the innovative design of liquid nitrogen inside the pipe and kerosene outside the pipe, the partitioning of the first heat exchange unit and the second heat exchange unit, and the staggered arrangement of the notches on the first baffle and the second baffle assembly, all work together to achieve low flow resistance performance of the heat exchange device, thereby improving heat exchange efficiency and heat exchange stability.

[0038] 4. Compared with the traditional liquid nitrogen cold bath type spiral tube kerosene heat exchanger, the present invention can reduce the size of the heat exchanger while maintaining the same heat exchange capacity.

[0039] 5. The present invention also includes a first observation window and a second observation window, which can improve the visualization of the heat exchange device and realize real-time monitoring of the kerosene heat exchange process.

[0040] 6. The present invention has an overflow port on the connecting ring along the radial direction, which can discharge excess liquid nitrogen to ensure that the medium entering the second heat exchange unit to exchange heat with kerosene is pure nitrogen gas, thereby ensuring that the kerosene will not freeze and realizing the safe operation of the heat exchange device.

[0041] 7. The present invention has a heat insulation layer on the first tube sheet to ensure the outlet temperature of kerosene.

[0042] 8. The present invention also provides a temperature regulating device and a temperature sensor near the third outlet of the first shell, which are used to realize real-time monitoring of the kerosene outlet temperature and ensure the accuracy of the kerosene heat exchange temperature.

[0043] 9. The finned tube of the present invention is a spiral finned tube or an annular finned tube, and has a segmented structure. This design not only improves the installation efficiency and accuracy of the finned tube, but also effectively reduces the flow resistance of kerosene and improves the heat exchange efficiency. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0045] Figure 2 for Figure 1 AA section view;

[0046] Figure 3 for Figure 1 BB cross-sectional view;

[0047] Figure 4 for Figure 1 CC section view;

[0048] Figure 5 Structure diagram of the first flange tube plate in the embodiment of the present application;

[0049] Figure 6 Structure diagram of the first tube plate in the embodiment of the present application;

[0050] Figure 7 Structure diagram of the heat insulation layer in the embodiment of the present application;

[0051] Figure 8 Structure diagram of the first baffle in the embodiment of the present application;

[0052] Figure 9 Structure diagram of the first heat exchange tube of the sleeved finned tube in the embodiment of the present application;

[0053] Figure 10 Structure diagram of the second heat exchange tube of the sleeved finned tube in the embodiment of the present application;

[0054] Figure 11 Structure diagram of the connection between the upper head and the upper floating head in the embodiment of the present application.

[0055] The reference signs are as follows:

[0056] 1 - support unit, 2 - lower floating head, 21 - first inlet, 3 - first heat exchange unit, 31 - first heat exchange tube, 32 - third inlet, 33 - third outlet, 34 - first shell, 341 - first observation window, 35 - first flange tube plate, 36 - first tube plate, 361 - heat insulation layer, 37 - first baffle, 38 - lower head, 381 - lower sealing opening, 39 - corrugated tube compensator, 4 - second heat exchange unit, 41 - second heat exchange tube, 42 - second inlet, 43 - second outlet, 44 - second shell, 441 - second observation window, 45 - second flange tube plate, 46 - second tube plate, 47 - second baffle, 48 - upper head, 481 - upper sealing opening, 5 - upper floating head, 51 - first outlet, 6 - connecting pipe, 7 - connecting ring, 8 - finned tube, 9 - heat insulation sleeve. DETAILED DESCRIPTION

[0057] To make the purpose, advantages and features of the present application clearer, the following further describes the present application in combination with the drawings and specific embodiments. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0058] As shown in Figure 1 the present embodiment provides a vertical double floating head finned tube kerosene heat exchange device, which comprises a support unit 1, a lower floating head 2, a first heat exchange unit 3, a second heat exchange unit 4, an upper floating head 5 and a connecting pipe 6.

[0059] The first heat exchange unit 3 is vertically installed on the support unit 1; the lower floating head 2 is installed at the bottom of the first heat exchange unit 3, and a first inlet 21 is arranged on the upper surface of the lower floating head 2 for introducing liquid nitrogen; the second heat exchange unit 4 is coaxially installed on the top of the first heat exchange unit 3 through the connecting ring 7, and the first heat exchange unit 3, the connecting ring 7 and the second heat exchange unit 4 form a gas collection cavity; the upper floating head 5 is installed on the top of the second heat exchange unit 4, and a first outlet 51 is arranged on the upper surface of the upper floating head 5 for discharging nitrogen gas.

[0060] A plurality of first heat exchange tubes 31 are uniformly distributed in the first heat exchange unit 3, and the two ends of each first heat exchange tube 31 are respectively communicated with the lower floating head 2 and the gas collection cavity; and the finned tube 8 is sleeved on part of the first heat exchange tubes 31. A plurality of second heat exchange tubes 41 are uniformly distributed in the second heat exchange unit 4, and the two ends of each second heat exchange tube 41 are respectively communicated with the upper floating head 5 and the gas collection cavity; and the finned tube 8 is sleeved on part of the second heat exchange tubes 41.

[0061] The second heat exchange unit 4 is provided with a second inlet 42 and a second outlet 43 along the radial direction, which are respectively used for the first introduction and discharge of the kerosene to be heat exchanged; the first heat exchange unit 3 is provided with a third inlet 32 and a third outlet 33 along the radial direction, which are respectively used for the second introduction and discharge of the kerosene to be heat exchanged. The two ends of the connecting pipe 6 are respectively connected with the second outlet 43 and the third inlet 32, so as to communicate the first heat exchange unit 3 and the second heat exchange unit 4.

[0062] The heat exchange device of the embodiment adopts the structure of the shell-and-tube finned tube heat exchanger, changes the heat exchange mode that the kerosene flows in the tube and the liquid nitrogen evaporates and cools in the saturated state outside the tube in the past kerosene supercooling process, and adopts the mode that the liquid nitrogen exchanges heat in the tube and the kerosene exchanges heat in the shell. In order to ensure that the cold energy of the liquid nitrogen can be fully absorbed by the kerosene, according to the flow state of the liquid nitrogen in the tube, the heat exchange region is divided into the first heat exchange unit 3 and the second heat exchange unit 4 in the embodiment, wherein the kerosene to be heat exchanged in the first heat exchange unit 3 exchanges heat with the liquid nitrogen in the saturated state, and the kerosene in the second heat exchange unit 4 exchanges heat with the nitrogen gas in the saturated state. Through heat exchange calculation by setting reasonable heat exchange temperature and heat exchange allowance, the heat exchange area of the first heat exchange unit 3 and the second heat exchange unit 4 and the length of the corresponding heat exchange tube can be obtained, and then the effective cold energy of the liquid nitrogen can be fully absorbed by the kerosene.

[0063] Since the liquid nitrogen phase change heat exchange is involved, the first heat exchange unit 3 and the second heat exchange unit 4 adopt the vertical arrangement mode; the liquid nitrogen enters the inner cavity of the lower floating head 2 from the first inlet 21 at the bottom of the first heat exchange unit 3, then flows upwards in the first heat exchange tube 31, forms low-temperature nitrogen gas after absorbing heat, and gathers in the gas collection cavity, so as to ensure that there is no liquid nitrogen when entering the second heat exchange tube 41 of the second heat exchange unit 4, and the icing of the kerosene is avoided.

[0064] In combination with Figure 1 ,Figures 4 to 8 As shown, the first heat exchange unit 3 of the embodiment comprises a first shell 34, a first flange tube plate 35, a first tube plate 36, a first baffle assembly and a lower head 38. The first shell 34 is vertically installed on the support unit 1 and has a cylindrical structure, and a plurality of first heat exchange tubes 31 are uniformly distributed in the cylindrical structure along the axial direction. The first flange tube plate 35 and the first tube plate 36 are respectively located at two ends of the first shell 34 and are fixedly connected with both ends of each first heat exchange tube 31 by welding. One end of the first flange tube plate 35 is coaxially connected with the connecting ring 7, and the other end is connected with the top of the first shell 34. The lower head 38 is installed at the bottom of the first shell 34, and the lower head 38 is provided with a lower sealing port 381. The first tube plate 36 and the lower head 2 are coaxially connected and both have a radial gap with the inner wall of the first shell 34; the lower head 2 and the lower head 38 have an axial gap, and the first inlet 21 is located in the lower sealing port 381 and is coaxial with the lower sealing port 381 and smaller than the caliber of the lower sealing port 381. The radial gap and the axial gap can ensure the floating connection between the lower head 2 and the first shell 34. The third inlet 32 is located near the first flange tube plate 35 of the first shell 34, and the third outlet 33 is located near the first tube plate 36 of the first shell 34.

[0065] The first baffle assembly of the embodiment comprises a plurality of first baffle plates 37 arranged in parallel and at equal intervals, wherein each first baffle plate 37 is a perforated circular plate structure, which is installed on the inner wall of the first shell 34 along the radial direction and is matched with the inner diameter of the first shell 34. One side edge of each first baffle plate 37 is provided with a notch (i.e. a notch is cut on each perforated circular plate structure), and the notches on the adjacent two first baffle plates 37 are symmetrically arranged in the horizontal direction. The plurality of first baffle plates 37 divide the inner cavity of the first shell 34 into S-shaped channels to provide a flow path for the oil to be heat exchanged.

[0066] In combination with Figure 4 and Figure 9 As shown, the finned tube 8 is sleeved on part of the first heat exchange tube 31, and the finned tube 8 is not sleeved on part of the first heat exchange tube 31. Among them: the first heat exchange tube 31 sleeved with the finned tube 8 is located in the middle of the first shell 34 and vertically penetrates through the corresponding hole of each first baffle plate 37, and the first heat exchange tube 31 sleeved with the finned tube 8 and the corresponding finned tube 8 are further sleeved with a heat insulation sleeve 9, and the heat insulation sleeve 9 is selected from a polytetrafluoroethylene sleeve. The first heat exchange tube 31 which is not sleeved with the finned tube 8 is arranged close to the inner wall of the first shell 34, vertically penetrates through the corresponding first baffle plate 37, and is located in the axial space of the notch of the first baffle plate 37. The first heat exchange tube 31 which is not sleeved with the finned tube 8 is sequentially sleeved with the heat insulation sleeve 9 and the light sleeve from inside to outside.

[0067] In this embodiment, the total number of first heat exchange tubes 31 is 559. The specific number can be adjusted according to the actual situation. The interior of each first heat exchange tube 31 is generally a mixture of liquid nitrogen and nitrogen gas.

[0068] Combination Figures 1 to 3 As shown, the second heat exchange unit 4 in this embodiment includes a second shell 44, a second flange tube sheet 45, a second tube sheet 46, a second baffle assembly, and an upper end cap 48. The second heat exchange unit 4 has the same basic structure as the first heat exchange unit 3, and its overall height can be specifically set according to the heat exchange requirements of kerosene.

[0069] The second shell 44 is a cylindrical structure, with multiple second heat exchange tubes 41 evenly distributed axially within the cylindrical structure. The second flange tube sheet 45 and the second tube sheet 46 are located at opposite ends of the second shell 44, respectively, and are fixedly connected to both ends of each second heat exchange tube 41 by welding. One end of the second flange tube sheet 45 is coaxially connected to the connecting ring 7, and the other end is connected to the bottom of the second shell 44. An upper end cap 48 is installed on the top of the second shell 44, and an upper sealing opening 481 is provided on the upper end cap 48. The second tube sheet 46 and the upper floating head 5 are coaxially connected, and both have radial gaps between them and the inner wall of the second shell 44. An axial gap is provided between the upper floating head 5 and the upper end cap 48. The first outlet 51 is located within the upper sealing opening 481, is coaxial with the upper sealing opening 481, and is smaller than the diameter of the upper sealing opening 481. These radial and axial gaps ensure a floating connection between the upper floating head 5 and the second shell 44. The second inlet 42 is located in the second shell 44 near the second tube sheet 46, and the second outlet 43 is located in the second shell 44 near the second flange tube sheet 45.

[0070] The second baffle assembly includes multiple second baffle plates 47 arranged parallel to each other and at equal intervals. Each second baffle plate 47 is a porous circular plate structure, which is radially mounted on the inner wall of the second housing 44 and adapted to the inner diameter of the second housing 44. Each second baffle plate 47 has a notch on one side edge, and the notches on two adjacent second baffle plates 47 are symmetrically arranged in the horizontal direction. The multiple second baffle plates 47 divide the inner cavity of the second housing 44 into S-shaped channels, similar to the S-shaped channels in the first housing 34.

[0071] Similarly, as Figure 10 As shown, in this embodiment, some of the second heat exchange tubes 41 are fitted with finned tubes 8, while others are not fitted with finned tubes 8. Specifically, the second heat exchange tubes 41 fitted with finned tubes 8 are located in the middle of the second housing 44 and pass vertically through each second baffle 47. The second heat exchange tubes 41 without finned tubes 8 are located near the inner wall of the second housing 44, pass vertically through the corresponding second baffle 47, and are located within the axial space of the notch in the second baffle 47. These unfitted second heat exchange tubes 41 are fitted with a smooth sleeve.

[0072] In this embodiment, the total number of second heat exchange pipes 41 is 547, and the specific number is adjusted according to the actual situation. The inside of each second heat exchange pipe 41 is generally filled with cold nitrogen gas.

[0073] As can be seen from the structure of the first heat exchange unit 3 and the second heat exchange unit 4, considering the icing problem, this embodiment is provided with finned tube 8 with a special heat resistance heat exchange surface structure. In the heat exchange process, liquid nitrogen or cold nitrogen gas flows in the first heat exchange pipe 31 or the second heat exchange pipe 41, and kerosene flows in the radial direction of the finned tube 8. In order to prevent icing caused by the contact between kerosene and liquid nitrogen or cold nitrogen gas during heat exchange, and to maximize heat exchange, the first heat exchange pipe 31 is coated with a heat insulation sleeve 9, and a composite heat exchange surface structure composed of spiral finned tube or annular finned tube is adopted. The thickness of the heat insulation sleeve 9 is reasonably set according to the requirements, so that the outer surface temperature of the finned tube 8 is higher than the icing temperature of kerosene; at the same time, the heat exchange is strengthened by expanding the heating surface of the finned tube 8 to achieve the purpose of kerosene supercooling optimization.

[0074] As shown in Figure 1 , the embodiment is further provided with a heat insulation layer 361 at the end of the first tube plate 36 away from the lower floating head 2. The heat insulation layer 361 is designed to insulate the kerosene outlet end, and the material of the heat insulation layer 361 is polytetrafluoroethylene, so as to achieve the insulation effect.

[0075] The first heat exchange pipe 31, the second heat exchange pipe 41 and the light sleeve are all made of stainless steel pipe. The finned tube 8 is a spiral finned tube or an annular finned tube. In order to facilitate assembly, the finned tube 8 is designed in a segmented structure. When assembling the first heat exchange unit 3 and the second heat exchange unit 4, the length of each group of finned tubes 8 is the same as the distance between the adjacent two first baffle plates 37 or second baffle plates 47, so that the finned tube 8 can be assembled in combination with the corresponding first baffle plate 37 or second baffle plate 47.

[0076] For the assembly of the finned tube 8 and the heat insulation sleeve 9 in the first heat exchange unit 3, and the assembly of the finned tube 8 and the second heat exchange pipe 41 in the second heat exchange unit, the finned tube 8 can be assembled with the corresponding baffle plate and the first tube plate 36 or the second tube plate 46, and then fixed on the corresponding heat insulation sleeve 9 or the second heat exchange pipe 41 by spot welding. In order to ensure the coaxiality of the finned tube 8 and the corresponding first heat exchange pipe 31 and second heat exchange pipe 41, the two ends of each finned tube 8 are processed into a stepped form, and the stepped head is inserted into the corresponding tube plate or baffle plate.

[0077] The length of the finned tube 8 is obtained according to the existing heat transfer calculation formula for finned tube, and the thickness of the heat insulation sleeve 9 can be calculated by heat balance. The specific method is as follows: the heat exchange coefficient of the kerosene side in the adverse heat exchange condition is h k , and the outer diameter d aThe wall temperature T of the finned tube 8 is obtained by multiplying the value of the average temperature of the saturated liquid nitrogen T w When the wall temperature T w =-75℃, the iteration is stopped, and then:

[0078]

[0079]

[0080] wherein T gn is the average temperature of the saturated liquid nitrogen, and is the original quantity in the design process; represents the temperature difference between the inside and outside of the finned tube 8; d1, d2, d a , and d b are the inner diameter of the first heat exchange tube 31, the outer diameter of the first heat exchange tube 31, the outer diameter of the heat insulation sleeve 9, and the outer diameter of the base tube of the finned tube 8, respectively, wherein the sizes of d1 and d2 should meet the requirements of GB / T 17395-2008 “Seamless Steel Tubes-Dimensions, Tolerances, Mass and Allowable Deviations” and are fixed values. a d b are input iteration quantities, in mm, and d a , and d b should meet the requirements of QB / T 4877-2015 “Polytetrafluoroethylene Pipes” and HG / T 3181-2009 “High Frequency Welded Spiral Finned Tube” regarding the inner and outer diameters of the polytetrafluoroethylene pipes and the base tube of the finned tube. g is the thermal conductivity of the first heat exchange tube 31; λ z is the thermal conductivity of the heat insulation sleeve 9. The remaining parameters including n, A p , η c , A f , h k , h N , and A N (the number of the first heat exchange tube 31, the base tube area (m 2 ) of the finned tube 8 with a length of 1 m, the fin efficiency, the fin area (m 2 ) of the finned tube 8 with a length of 1 m, the heat exchange coefficient of kerosene (W / m 2 / ℃), the heat exchange coefficient of liquid nitrogen (W / m 2 / ℃), and the heat exchange area of liquid nitrogen) can be calculated according to the basic principles of heat transfer under the given working conditions and the given structure.

[0081] The aerospace kerosene is a mixture, which has no certain freezing point and generally starts to freeze at -75℃ to -65℃. After the heat balance calculation by the above method, the heat transfer coefficient of the liquid nitrogen in the first heat exchange tube 31 is one order of magnitude higher than that of the kerosene outside the tube (the thermal resistance ratio is greater than 10:1) in the first heat exchange unit 3. If the icing problem is considered, the special heat exchange surface structure with thermal resistance is set to prevent the kerosene in the shell side from freezing and causing the blockage of the shell side flow during the heat exchange process with the liquid nitrogen. In the second heat exchange unit 4, the heat transfer coefficient of the nitrogen in the second heat exchange tube 41 is close to that of the kerosene outside the tube, and the thermal resistance ratio of the two is close to 1:1. Therefore, the heat insulation sleeve 9 is not set, and only the corresponding finned tube 8 is set.

[0082] The d of the second heat exchange unit 4 in the embodiment is a d2, that is, the second heat exchange unit 4 does not use the heat insulation sleeve 9, but directly uses the form of the second heat exchange tube 41 plus the finned tube 8. The connecting ring 7 is arranged between the first heat exchange unit 3 and the second heat exchange unit 4 to form a low-temperature nitrogen gas accumulation cavity, and the overflow port is arranged on the side wall at the top of the cavity. The height of the low-temperature nitrogen gas accumulation cavity (that is, the height of the connecting ring 7) is 100 mm.

[0083] The finned tube of the embodiment adopts the high-frequency resistance welded finned tube, and the tube material and the fin material are both 06Cr19Ni10 stainless steel. The specific processing technology should meet the requirements of HG / T3181-2009. In order to adapt to the assembly of the finned tube, the whole finned tube is cut according to the required length. The inner diameter tolerance of the finned tube 8 should meet DN22+φ0.3mm~+φ0.6mm (in the first heat exchange unit 3) and DN20+φ0.3mm~+φ0.6mm (in the second heat exchange unit 4) to ensure the normal assembly of the finned tube 8 and ensure that the surface contact thermal resistance is within a controllable range.

[0084] In addition, the solid particles and moisture in the heat exchange device are effectively controlled according to the requirements of GB150 and GB151. At the same time, the following excess material control methods can also be adopted:

[0085] (1) Excess material control before finned tube assembly

[0086] Before the assembly of the finned tube 8, all the finned tubes 8 are soaked in a mixed solution of 15% to 25% nitric acid and 1% to 5% hydrofluoric acid for 1 h by using the pickling process. After the pickling is completed, the finned tubes 8 are washed with deionized water for three times, and the single ratio is 0.1L deionized water for 0.1m finned tube 8. After the washing is completed, the finned tubes 8 are dried by placing them in an incubator for 0.5h.

[0087] (2) Excess material control during the assembly process of the finned tube 8

[0088] During the assembly process, the PM2.5 value of the on-site environment is ensured to be less than 35, and the on-site humidity is less than 20g / m3 , field isolation industry powder-free.

[0089] (3) Finned tube 8 assembly after the excess control

[0090] After the finned tube 8 assembly is completed, the assembled heat exchanger inner core is placed in a 1x1x3 square stainless steel tank, and industrial ethanol with a purity of 98% is injected. The outside of the 1x1x3 square stainless steel tank is uniformly arranged with more than 50 single 6kW ultrasonic generators, the ultrasonic frequency is 15Hz, and each ultrasonic generator is welded with the stainless steel tank. The heat exchanger inner core in this embodiment refers to: the first heat exchange tube 31 in the first heat exchange unit 3 + the heat insulation sleeve 9 + the finned tube 8 + the first baffle plate 37, the second heat exchange tube 41 in the second heat exchange unit 4 + the finned tube 8 + the second baffle plate 47.

[0091] (4) Solid particle excess control during the processing of the first shell 34 and the second shell 44

[0092] After the first shell 34 and the second shell 44 are processed, the inner wall of the shell is polished, and after polishing, the inner surface is wiped with a 98% industrial ethanol soaked cheesecloth, and after wiping, it is sealed with plastic film after natural air drying in a dust-free workshop for 5h.

[0093] The heat exchange device obtained by using the above scheme fully meets the process requirements; the heat exchange device has good excess control, and the heat exchange test verifies that the 100m 3 The kerosene after passing through the heat exchanger has an excess amount of less than 1g on the 400 mesh filter.

[0094] As shown in Figure 1 , the first observation window 341 is arranged near the lower head 38 of the first shell 34, and the second observation window 441 is arranged near the second flange tube plate 45 of the second shell 44. The first observation window 341 and the second observation window 441 are both quartz glass windows, which are used to observe the state of the kerosene to be heat exchanged in the first shell 34 and the second shell 44, and improve the visualization of the heat exchange device.

[0095] As shown in Figures 1 to 11 , the heat exchange device of the present embodiment adopts a floating head type compensation structure to meet the axial compensation of the heat exchange core. In order to simplify the structure of the heat exchange device for easy processing, the elliptical floating head is directly welded with the corresponding tube plate. At the same time, corrugated pipe compensators 39 connected with the upper head 48 and the lower head 38 are arranged on the upper floating head 5 and the lower floating head 2 respectively. The length of the corrugated pipe compensator 39 of the upper floating head 5 is preliminarily designed as 80mm, and the length of the corrugated pipe compensator 39 of the lower floating head 2 is preliminarily designed as 30mm, with an error of not more than 10%. The outlet pipe of the upper floating head 5 and the lower floating head 2 is welded after the overall assembly of the first shell 34 and the second shell 44 is completed.

[0096] As Figure 11 shown, the specific process sequence of the upper floating head 5 is as follows: the upper floating head 5 is welded with the second tube plate 46, then assembled with the second shell 44 (flange connection), the pipeline of the upper floating head 5 is welded with the pipeline of the second shell 44, and the flange joint is welded, the welding sequence is a→b→(assembly is completed)→c→d→e→f, wherein a, c, d and f are butt welds, and b is a reinforcing fillet weld.

[0097] The embodiment also adopts an assembly precision control scheme, in order to ensure that the components in the heat exchanger can be smoothly assembled without affecting the heat exchange performance of the heat exchanger, the following fit clearances are controlled respectively:

[0098] The heat insulation sleeve 9 on the first heat exchange tube 31 is in clearance fit with the corresponding finned tube 8, and the fit clearance is controlled to be 0.1mm~0.4mm.

[0099] The second heat exchange tube 41 is in clearance fit with the corresponding finned tube 8, and the fit clearance is controlled to be 0.1mm~0.4mm.

[0100] The first baffle plate 37 and the second baffle plate 47 are in clearance fit with the base tubes at both ends of the corresponding finned tube 8, and the fit clearance is controlled to be 0.1mm~0.2mm.

[0101] The fit clearance between the first baffle plate 37 and the second baffle plate 47 and the corresponding first shell 34 and the second shell 44 should meet the requirements of GB151.

[0102] In order to ensure the precision of the kerosene heat exchange, the embodiment is provided with a temperature adjusting device near the third outlet 33 of the first shell 34, and a temperature sensor connected with the temperature adjusting device; the temperature adjusting device is used to adjust the outflow temperature of the kerosene, and the temperature sensor is used to monitor the outflow temperature, so as to master the heat exchange condition of the kerosene according to the monitoring condition.

[0103] As shown in Table 1, the test data of the traditional liquid nitrogen cold bath type spiral tube heat exchanger and the embodiment are compared:

[0104] Table 1 Comparison of test data of traditional heat exchanger and heat exchange device of the embodiment

[0105]

[0106] As can be seen from the above table, compared with the traditional liquid nitrogen cold bath type spiral tube kerosene heat exchanger, the heat exchange power of the embodiment can be increased by about 2.5 times under the same heat exchange volume, the maximum heat exchange flow rate can be as high as 1200L / min, the flow resistance is greatly reduced, the liquid nitrogen utilization amount is obviously reduced, and the economy is improved.

[0107] The embodiment can not only solve the problem of kerosene icing in the traditional liquid nitrogen cold bath type spiral pipe heat exchanger, but also effectively reduce the flow resistance of the heat exchanger, the heat exchanger can reduce the temperature of aerospace kerosene to-25℃, and the heat exchange effect is better.

[0108] The embodiment can realize rapid and efficient cooling of kerosene, thereby meeting the demand of overcooled kerosene of launch site and test system, and has the ability to cool normal temperature kerosene to 5-10℃ below the required overcooled kerosene temperature of launch site or test system at one time.

[0109] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or part or all of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A vertical double-floating-head finned tube kerosene heat exchanger, characterized in that it comprises a support unit (1), a lower floating head (2), a first heat exchange unit (3), a second heat exchange unit (4), an upper floating head (5), and a connecting pipe (6); the first heat exchange unit (3) is vertically installed on the support unit (1); the lower floating head (2) is installed at the bottom of the first heat exchange unit (3) and is provided with a first inlet (21) for the introduction of liquid nitrogen; the second heat exchange unit (4) is coaxially installed on the top of the first heat exchange unit (3) through a connecting ring (7) and encloses a gas collection cavity with the first heat exchange unit (3) and the connecting ring (7); the upper floating head (5) is installed at the top of the second heat exchange unit (4) and is provided with a first outlet (51) for the discharge of nitrogen gas; a plurality of first heat exchange tubes (31) are uniformly distributed in the first heat exchange unit (3), both ends of each first heat exchange tube (31) are respectively communicated with the lower floating head (2) and the gas collection cavity, and some of the first heat exchange tubes (31) are sleeved with finned tubes (8); a plurality of second heat exchange tubes (41) are uniformly distributed in the second heat exchange unit (4), both ends of each second heat exchange tube (41) are respectively communicated with the upper floating head (5) and the gas collection cavity, and some of the second heat exchange tubes (41) are sleeved with finned tubes (8); a second inlet (42) and a second outlet (43) are provided on the second heat exchange unit (4) along the radial direction and are respectively used for the first introduction and discharge of the kerosene to be heat exchanged; a third inlet (32) and a third outlet (33) are provided on the first heat exchange unit (3) along the radial direction and are respectively used for the second introduction and discharge of the kerosene to be heat exchanged; both ends of the connecting pipe (6) are connected with the second outlet (43) and the third inlet (32), so as to connect the first heat exchange unit (3) and the second heat exchange unit (4). ​ ​ ​ ​ ​ The first heat exchange unit (3) includes a first shell (34), a first flange tube sheet (35), a first tube sheet (36), a first baffle assembly, and a lower end cap (38); the first shell (34) is vertically mounted on the support unit (1), and it is a cylindrical structure, with multiple first heat exchange tubes (31) evenly distributed axially within the cylindrical structure; the first flange tube sheet (35) and the first tube sheet (36) are respectively used to fix the two ends of each first heat exchange tube (31); one end of the first flange tube sheet (35) is coaxially connected to the connecting ring (7), and the other end is connected to the first shell (34). The top is connected; the lower end cap (38) is installed at the bottom of the first shell (34), and the lower end cap (38) is provided with a lower sealing port (381); the first tube sheet (36) and the lower floating head (2) are coaxially connected and both have radial gaps between them and the inner wall of the first shell (34); there is an axial gap between the lower floating head (2) and the lower end cap (38), the first inlet (21) is coaxial with the lower sealing port (381) and is smaller than the diameter of the lower sealing port (381); the third inlet (32) is located on the first shell (34) near the first flange tube sheet (35), and the third outlet (33) is located on the first shell (34). Located near the first tube sheet (36) in the first housing (34); the first baffle assembly includes a plurality of first baffle plates (37) arranged parallel to each other and at equal intervals; each first baffle plate (37) is a porous circular plate structure, which is installed radially on the inner wall of the first housing (34) and is adapted to the inner diameter of the first housing (34); each first baffle plate (37) has a notch on one side edge, and the notches on two adjacent first baffle plates (37) are symmetrically arranged in the horizontal direction, and the plurality of first baffle plates (37) divide the inner cavity of the first housing (34) into an S-shape. The first heat exchange tube (31) with the finned tube (8) is located in the middle of the first shell (34) and passes vertically through each first baffle (37), and the first heat exchange tube (31) and the corresponding finned tube (8) are fitted with a heat insulation sleeve (9); the first heat exchange tube (31) without the finned tube (8) is located close to the inner wall of the first shell (34), passes vertically through the corresponding first baffle (37), and is located in the axial space where the notch of the first baffle (37) is located, and the first heat exchange tube (31) is fitted with a heat insulation sleeve (9) and a bare sleeve from the inside to the outside. The second heat exchange unit (4) comprises a second shell (44), a second flange tube plate (45), a second tube plate (46), a second baffle assembly and an upper head (48). The second shell (44) is a cylindrical structure, and a plurality of second heat exchange tubes (41) are uniformly distributed in the cylindrical structure along the axial direction. The second flange tube plate (45) and the second tube plate (46) are respectively used for fixing two ends of each second heat exchange tube (41). One end of the second flange tube plate (45) is coaxially connected with the connecting ring (7), and the other end is connected with the bottom of the second shell (44). The upper head (48) is installed at the top of the second shell (44), and an upper sealing portion (481) is arranged on the upper head (48). The second tube plate (46) and the upper floating head (5) are coaxially connected and are both radially spaced from the inner wall of the second shell (44). An axial gap is left between the upper floating head (5) and the upper head (48), the first outlet (51) is coaxial with the upper sealing portion (481) and smaller than the diameter of the upper sealing portion (481). The second inlet (42) is located near the second tube plate (46) of the second shell (44), and the second outlet (43) is located near the second flange tube plate (45) of the second shell (44). The second baffle assembly comprises a plurality of second baffles (47) arranged in parallel and at equal intervals. Each second baffle (47) is a perforated circular plate structure, which is installed on the inner wall of the second shell (44) along the radial direction and is matched with the inner diameter of the second shell (44). One side edge of each second baffle (47) is provided with a notch, and the notches on adjacent two second baffles (47) are symmetrically arranged in the horizontal direction. The plurality of second baffles (47) divide the inner cavity of the second shell (44) into S-shaped channels. The second heat exchange tube (41) of the sleeve finned tube (8) is located in the middle of the second shell (44) and vertically penetrates each second baffle (47). The second heat exchange tube (41) of the non-sleeved finned tube (8) is arranged close to the inner wall of the second shell (44), vertically penetrates the corresponding second baffle (47) and is located in the axial space of the notch of the second baffle (47). A light sleeve pipe is sleeved on the second heat exchange tube (41).

2. The vertical double floating head finned tube kerosene heat exchange device according to claim 1, characterized in that: The first shell (34) is provided with a first observation window (341) near the lower head (38); The second shell (44) is provided with a second observation window (441) near the second flange tube plate (45).

3. The vertical double floating head finned tube kerosene heat exchange device according to claim 2, characterized in that: The upper floating head (5) and the lower floating head (2) are respectively provided with corrugated pipe compensators (39) connected with the upper head (48) and the lower head (38).

4. The vertical double floating head finned tube kerosene heat exchange device according to any one of claims 1 to 3, characterized in that: The connecting ring (7) is provided with an overflow port in the radial direction.

5. The vertical double floating head finned tube kerosene heat exchange device according to claim 4, characterized in that: The heat insulation sleeve (9) on the first heat exchange pipe (31) is gap-fitted with the corresponding finned pipe (8), and the fitted gap is 0.1mm-0.4mm; The second heat exchange pipe (41) is gap-fitted with the corresponding finned pipe (8), and the fitted gap is 0.1mm-0.4mm; The first baffle (37), the second baffle (47) and the two end portions of the corresponding finned pipe (8) are gap-fitted along the radial direction, and the fitted gap is 0.1mm-0.2mm.

6. The vertical double-floating-head finned pipe kerosene heat exchange device according to claim 5, characterized in that: The first tube plate (36) is provided with a heat insulation layer (361) at the end away from the lower floating head (2).

7. The vertical double-floating-head finned pipe kerosene heat exchange device according to claim 6, characterized in that: The first shell (34) is provided with a temperature adjusting device near the third outlet (33), and a temperature sensor connected with the temperature adjusting device; the temperature adjusting device is used for adjusting the outflow temperature of kerosene, and the temperature sensor is used for monitoring the outflow temperature.

8. The vertical double-floating-head finned pipe kerosene heat exchange device according to claim 7, characterized in that: The finned pipe (8) is a spiral finned pipe and has a sectional structure; The material of the heat insulation sleeve (9) and the heat insulation layer (361) is polytetrafluoroethylene; The first heat exchange pipe (31), the second heat exchange pipe (41) and the light sleeve are all stainless steel pipes.

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