A vertical tube-shell heat exchanger for electronic grade nitric acid preparation and processing

Abstract

This invention relates to a vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid, comprising a vertical shell, a heat exchange tube bundle, an upper tube box, and a lower tube box, correspondingly forming a tube-side flow channel for cooling water flow and a shell-side flow channel for nitric acid vapor flow. The shell-side flow channel is equipped with continuous spiral baffles, forming a spiral heat exchange channel. A gas-liquid separation module is integrated on the outer periphery of the lower tube box, with a spiral guide plate within its swirling separation chamber forming a spiral separation channel. The heat exchange channel and the separation channel are tangentially connected. A pre-collection tube penetrating the baffles is provided on the inner wall of the shell. A Venturi tube downstream of the liquid phase outlet provides negative pressure suction power to the pre-collection tube via an ejector pipe. This invention optimizes the shell-side flow field, improves condensation heat exchange efficiency, and reduces liquid film thermal resistance by real-time condensate removal. Simultaneously, it utilizes the kinetic energy of the heat exchange swirling flow to achieve gas-liquid separation, reducing energy consumption and footprint. It significantly reduces the load on the separated liquid phase, avoids flooding and droplet entrainment, and meets the high-purity production requirements of electronic-grade nitric acid.

Description

Technical Field

[0001] This invention relates to the field of fluid heat exchange equipment, specifically to a vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid. Background Technology

[0002] Electronic-grade nitric acid is an indispensable core wet electronic chemical in the high-end electronics manufacturing field. It is widely used in key processes such as wafer cleaning and etching, silicon wafer texturing, and display panel thin-film etching. Its purity and cleanliness directly determine the photoelectric conversion efficiency of photovoltaic cells and the process yield of semiconductor chips. In the industrial distillation purification of high-purity nitric acid, the condensation and liquefaction of the nitric acid-water azeotropic vapor produced at the top of the distillation column is the core link between distillation purification and subsequent aeration and impurity removal processes. The heat exchange efficiency and gas-liquid separation effect of the condensation process directly determine the product yield, purity index, and continuous operation stability of the production line.

[0003] Currently, vertical shell-and-tube condensers are commonly used in the industry for the condensation process of nitric acid azeotropic vapor. Due to the highly corrosive and easily decomposed nature of nitric acid, the industry standard design features cooling water flowing through the tubes and nitric acid azeotropic vapor flowing through the shell. This layout significantly reduces the number of sealing points for highly corrosive media, lowering the risk of leakage. Simultaneously, the cooling water side of the tubes facilitates scaling, cleaning, and routine maintenance, making it the mainstream equipment type suitable for high-purity nitric acid production.

[0004] However, in practical industrial applications, existing vertical shell-and-tube condensers still have the following technical problems: Firstly, existing shell-side heat exchangers often use arc-shaped baffles to guide steam flow, which can easily lead to uneven distribution of the shell-side flow field, resulting in flow dead zones, steam deflection, and short-circuiting problems, making it impossible to achieve uniform and sufficient contact between steam and heat exchange tube bundles. At the same time, the liquid nitric acid formed by steam condensation can easily form a continuous thick liquid film on the outer wall of the heat exchange tube bundle, generating a large additional thermal resistance and significantly reducing condensation heat transfer efficiency.

[0005] Secondly, in the existing technology, the condensed gas-liquid mixture needs to be transported to an independent gas-liquid separation device through an intermediate pipe, which results in the complete loss of the swirling kinetic energy formed by the steam during the condensation process. The gas-liquid separation requires an additional swirling structure, which not only increases the energy consumption and floor space of the equipment, but also easily causes flow field disturbances and pressure fluctuations.

[0006] Third, all the liquid phase of the condensate enters the separation zone along with the gas phase. The excessive liquid load in the separation zone can easily lead to flooding and excessive droplet entrainment, which cannot meet the stringent control requirements of electronic-grade nitric acid for metal ions and particulate matter.

[0007] The purpose of this invention is to design a vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid, addressing the problems existing in the prior art. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid, which can effectively solve at least one of the problems existing in the prior art.

[0009] This invention provides a vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid, comprising a vertical shell, wherein a plurality of heat exchange tube bundles extending axially are formed within the vertical shell, and a closed shell-side flow channel is formed between the outer side of the heat exchange tube bundles and the inner side of the vertical shell, wherein an upper tube box and a lower tube box are respectively sealed and fixed at both ends of the vertical shell along the axial direction, the upper tube box, the heat exchange tube bundles, and the lower tube box are sequentially connected to form a tube-side flow channel for cooling water flow, an air inlet pipe communicating with the shell-side flow channel is provided at the top of the vertical shell, and a continuous spiral baffle extending axially is provided within the shell-side flow channel to divide the shell-side flow channel into a continuous spiral heat exchange channel; The lower tube box is provided with a gas-liquid separation module on its outer periphery. The gas-liquid separation module includes a cyclone separation chamber coaxially sleeved on the outer periphery of the lower tube box, a non-condensable gas buffer chamber connected to the cyclone separation chamber, and a liquid phase collection tank at the bottom of the cyclone separation chamber. The bottom of the cyclone separation chamber is provided with a plurality of liquid collection pipes connected to the liquid phase collection tank. The non-condensable gas buffer chamber is connected to a non-condensable gas outlet pipe. The bottom of the liquid phase collection tank is connected to a liquid phase outlet pipe. The cyclone separation chamber is provided with a continuous spiral guide plate extending along its axial direction to divide the cyclone separation chamber into a continuous spiral separation channel. The bottom of the shell-side channel is provided with a tangential feed port, and the top inlet of the separation channel is tangentially connected to the bottom outlet of the heat exchange channel through the tangential feed port. At least one pre-collection pipe is arranged circumferentially on the inner wall of the vertical shell. The pre-collection pipe passes through the surface of the baffle plate axially and extends to the liquid phase collection tank at its bottom. Liquid collection holes are opened at the intersection of the pre-collection pipe and the surface of the baffle plate. The downstream of the liquid phase outlet pipe is connected to a Venturi tube, and the throat section of the Venturi tube is connected to the lower side wall of the pre-collection tube through an ejector pipe, which is used to provide negative pressure suction power to the pre-collection tube through the flow of the liquid phase.

[0010] As a further improvement, a number of air guide holes are provided on the wall surface of the separation channel near the non-condensable gas buffer chamber. The air guide holes are distributed sequentially along the spiral path of the separation channel. The swirling separation chamber is connected to the non-condensable gas buffer chamber through the air guide holes. A liquid return hole is provided through the bottom of the outer wall surface where the air guide holes are located.

[0011] As a further improvement, the air guide hole is located on the upper side of the separation channel relative to the guide plate surface, and the air guide hole penetrates the outer wall of the swirling separation chamber tangentially along the separation channel.

[0012] As a further improvement, the surface of the guide plate extends radially inward toward the swirling separation chamber along the outer wall of the separation channel near the non-condensable gas buffer chamber and slopes downward, forming a guide gap between the inner side of the guide plate surface and the inner wall of the swirling separation chamber.

[0013] As a further improvement, several of the liquid collecting pipes are evenly arranged circumferentially along the bottom of the cyclone separation chamber, and the bottom of the liquid collecting pipes extends below the lowest designed liquid level of the liquid phase collection tank.

[0014] As a further improvement, the outer edge of the baffle plate is provided with a continuous liquid collection groove along the entire spiral path, the pre-collection pipe passes longitudinally through the liquid collection groove, and the liquid collection hole is located within the coverage area of ​​the liquid collection groove.

[0015] As a further improvement, the liquid collecting holes are evenly arranged along the circumference of the pre-collecting tube and their bottoms are flush with the bottom of the liquid collecting groove. The liquid collecting groove is symmetrically provided with inclined guide surfaces on both sides of the radial side of the shell-side flow channel. The two guide surfaces are arranged along the spiral path of the baffle plate throughout. The bottom width of the liquid collecting groove is adapted to the outer diameter of the pre-collecting tube so that the bottom of the liquid collecting hole is connected to the bottom of the guide surface at the corresponding position.

[0016] As a further improvement, the ejector conduit includes a main ejector pipe, an annular branch pipe, and ejector unit pipes. The annular branch pipe is coaxially arranged around the outer periphery of the liquid phase collection tank. The annular branch pipe is connected to the throat section of the Venturi tube through the main ejector pipe. The number of ejector unit pipes is the same as that of the pre-collection pipes. The inner annular side of the annular branch pipe is connected to the lower sidewall of the pre-collection pipe through the ejector unit pipes. The main ejector pipe is equipped with a one-way valve. The conduction direction of the one-way valve is from the pre-collection pipe to the throat section of the Venturi tube.

[0017] As a further improvement, the pitch of the guide plate decreases linearly in the downward direction along its axial direction, with the ratio of its first pitch to the inner diameter of the shell-side flow channel being 1.2:1, and the ratio of its last pitch to the inner diameter of the shell-side flow channel being 0.6:1.

[0018] As a further improvement, the top of the shell-side flow channel is provided with an annular flow equalization shroud that is circumferentially distributed around its inner side. The inner side of the annular flow equalization shroud forms a flow equalization cavity that communicates with the intake pipe. The side wall of the flow equalization cavity near the central axis of the shell-side flow channel is provided with a plurality of flow equalization holes that communicate with the shell-side flow channel. The plurality of flow equalization holes are evenly distributed circumferentially along the side wall of the flow equalization cavity.

[0019] Therefore, the present invention provides the following effects and / or advantages: Existing vertical shell-and-tube condensers for electronic-grade nitric acid preparation often use arc-shaped baffles to guide the azeotropic vapor flow of nitric acid in the shell side. This easily leads to uneven flow field distribution in the shell side, resulting in flow dead zones, vapor flow deviation, and short-circuiting problems. It is impossible to achieve uniform and sufficient contact between the vapor and the heat exchange tube bundle, which significantly reduces the condensation heat transfer efficiency. At the same time, the liquid nitric acid formed by vapor condensation tends to form a continuous thick liquid film on the outer wall of the heat exchange tube bundle, generating a large additional thermal resistance, further weakening the condensation heat transfer effect. This makes it unsuitable for the high-efficiency heat exchange requirements of high-purity nitric acid distillation production. To address this, the present invention incorporates a continuous spiral baffle within the shell-side flow channel, dividing the flow channel into a continuous spiral heat exchange channel. This guides the nitric acid azeotropic vapor to maintain uniform and sufficient contact with the heat exchange tube bundle along the entire spiral path, completely eliminating flow dead zones, vapor deviation, and short-circuiting issues, significantly improving the uniformity of the shell-side flow field and heat exchange stability. Simultaneously, a pre-collection pipe axially penetrates the baffle on the inner wall of the vertical shell, working in conjunction with the liquid collection holes on the baffle to collect liquid nitric acid condensed on the outer wall of the heat exchange tube bundle in real time. Through a negative pressure suction structure linked to the venturi tube downstream of the liquid phase outlet pipe, the collected liquid phase of the condensate is rapidly extracted from the heat exchange area, fundamentally preventing the formation of a continuous thick liquid film on the outer wall of the heat exchange tube bundle, significantly reducing the additional thermal resistance on the condensation side, and significantly improving condensation heat transfer efficiency and nitric acid product yield.

[0020] In existing nitric acid condensation processes, the condensed gas-liquid mixture needs to be transported to a separate gas-liquid separation device via an intermediate pipe. This results in the complete loss of the swirling kinetic energy generated by the steam during condensation. The gas-liquid separation requires an additional swirling generator structure, which not only increases energy consumption and floor space but also easily causes flow field disturbances and pressure fluctuations, affecting the stability of continuous production line operation. To address this, this invention integrates a coaxial gas-liquid separation module on the outer periphery of the lower tube box. A tangential feed inlet connects the bottom outlet of the spiral heat exchange channel to the top inlet of the separation channel. This allows direct utilization of the spiral swirling kinetic energy generated during steam condensation, eliminating the need for an additional swirling power structure. This achieves efficient swirling separation of the gas-liquid mixture within the swirling separation chamber, avoiding the ineffective loss of swirling kinetic energy, reducing energy consumption, eliminating the need for a separate gas-liquid separation device and intermediate connecting pipes, significantly reducing the equipment floor space, and eliminating flow field disturbances and pressure fluctuations in the intermediate transport stage, ensuring the stability of continuous operation of the high-purity nitric acid production line.

[0021] In existing condenser structures, all the liquid phase of the condensate enters the gas-liquid separation zone along with the gas phase, resulting in excessive liquid load in the separation zone. This easily leads to flooding and excessive droplet entrainment, failing to meet the stringent control requirements of electronic-grade nitric acid and making it difficult to consistently produce high-purity products that meet the standards of high-end electronic manufacturing processes. To address this, this invention utilizes the linkage between a pre-collection tube and a venturi tube negative pressure suction structure to directly pump the majority of the condensate liquid phase to the liquid phase collection tank during heat exchange. This significantly reduces the liquid load of the gas-liquid mixture entering the cyclone separation chamber, fundamentally avoiding flooding and excessive droplet entrainment. Simultaneously, the spiral separation channel formed by continuous spiral guide plates within the cyclone separation chamber allows for deep cyclone separation of the remaining small amount of liquid phase and non-condensable gas, further intercepting trace droplets and particulate matter entrained in the gas phase, consistently meeting the ultra-high purity and cleanliness requirements of electronic-grade nitric acid.

[0022] Existing condensers mostly adopt a constant pitch spiral flow separation structure. During the flow of the gas-liquid mixture from top to bottom, the gas phase gradually condenses and its volume continuously decreases. A fixed pitch can easily lead to a decrease in the intensity of the swirling flow in the later stage, insufficient separation power, and problems such as the escape of fine droplets and incomplete separation. This cannot meet the high cleanliness separation requirements of electronic-grade nitric acid. At the same time, a constant pitch cannot adapt to changes in flow rate along the flow path, and the distribution of flow pressure drop is unreasonable, which can easily cause local eddy accumulation and affect the separation stability. To address this, the present invention features a linearly decreasing pitch of the spiral guide plate within the cyclone separation chamber along the axial downward direction. The initial large pitch ensures smooth entry of the gas-liquid mixture into the separation channel and reduces inlet flow resistance. The pitch gradually decreases in the middle and later sections, utilizing the narrowing of the flow channel to continuously enhance the centrifugal intensity of the airflow cyclone, progressively strengthening the centrifugal capture effect of fine droplets and solid particles, effectively preventing the escape of trace droplets. The gradually decreasing pitch can adapt to changes in the condensation reduction of the gas-liquid mixture along the process, maintaining a reasonable flow velocity and cyclone intensity throughout, evenly distributing the flow pressure drop, avoiding local eddies and flow field disturbances, and achieving ultimate gas-liquid separation accuracy under low flow resistance, precisely meeting the stringent control standards of electronic-grade nitric acid for low particulate matter and low metal ion content.

[0023] Existing condensers often use direct inlet gas to the shell side, which can easily lead to uneven steam distribution in the inlet area and excessively high local flow velocities that can impact the heat exchange tube bundles. Furthermore, during gas-liquid separation, the discharged non-condensable gas can easily carry trace amounts of condensate, resulting in product yield loss and increasing the risk of corrosion and leakage in the non-condensable gas discharge pipeline. To address this, this invention features an annular flow equalization hood at the top of the shell-side flow channel. Uniformly distributed circumferential flow equalization holes evenly distribute the nitric acid azeotropic vapor from the inlet pipe across the entire shell-side cross-section, preventing inlet steam deviation from impacting the heat exchange tube bundles and ensuring a uniform and stable flow field throughout the shell side. Tangential guide holes are sequentially arranged along the spiral path on the separation channel of the cyclone separation chamber, working in conjunction with bottom return holes to smoothly guide the separated non-condensable gas to the non-condensable gas buffer chamber. Simultaneously, the trace amounts of condensate entrained in the non-condensable gas are returned to the liquid phase collection tank through the return holes. This not only avoids product yield loss but also completely eliminates the risk of pipeline corrosion and leakage caused by liquid entrainment in the non-condensable gas.

[0024] The existing condensate collection structure of the condenser is prone to problems such as liquid accumulation on the baffle plate and condensate backflow that re-contacts the heat exchange tube bundle, further aggravating the liquid film thermal resistance. At the same time, the negative pressure suction line is prone to condensate backflow, causing the suction of the pre-collection tube to fail and making it impossible to stably achieve rapid condensate discharge. In addition, the separated condensate is prone to gas phase intrusion, causing gas-liquid two-phase crossflow disturbance, affecting the stable discharge of condensate and product purity. To address this, the present invention features a continuous liquid collection groove along the spiral path on the outer edge of the baffle plate. Combined with inclined guide surfaces on both sides, this allows the condensate pre-collected on the baffle plate surface to flow into the collection groove. The condensate is then collected in real-time through a collection hole on the pre-collection pipe, flush with the bottom of the groove, completely preventing backflow of liquid from the baffle plate and further ensuring condensation heat exchange efficiency. A one-way valve is installed in the ejector pipe, strictly limiting the flow direction to the section from the pre-collection pipe to the venturi throat, completely avoiding suction failure caused by condensate backflow and ensuring long-term stable operation of the negative pressure suction drainage. Simultaneously, the collection pipe at the bottom of the cyclone separation chamber extends below the lowest designed liquid level of the liquid phase collection tank. A liquid seal structure prevents gas from entering the liquid phase collection tank, eliminating gas-liquid crossflow disturbances and ensuring stable condensate discharge and product purity.

[0025] In summary, this invention solves the core problems of uneven shell-side flow field, high condensate film thermal resistance, and low condensation heat transfer efficiency in existing condensers by constructing a spiral heat exchange channel with continuous spiral baffles and combining it with a negative pressure suction and drainage structure that links the pre-collection tube and the Venturi tube. Through the tangential connection and integrated design of the heat exchange channel and the swirl separation channel, it directly utilizes the swirl kinetic energy of the condensation process to achieve efficient gas-liquid separation, eliminating the need for independent separation equipment, reducing energy consumption and floor space, and eliminating flow field disturbances in the transportation process. Furthermore, the pre-collection and drainage of the condensate... The synergistic effect of deep cyclone separation significantly reduces the liquid load in the separation zone, avoiding flooding and droplet entrainment problems, and stably meeting the ultra-high purity and cleanliness requirements of electronic-grade nitric acid. At the same time, through the matching design of annular flow equalization hood, gradient pitch guide plate, liquid seal collection pipe and anti-backflow check valve, the heat exchange efficiency, separation effect, operational stability and long-term corrosion resistance of the equipment are taken into account. It is fully adapted to the stringent operating conditions of electronic-grade nitric acid distillation and purification production, effectively improving the yield, purity index of high-purity nitric acid products and the continuous operation stability of the production line.

[0026] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0027] It should be understood that the above summary and the following detailed description of the invention are exemplary and explanatory, and are intended to provide further explanation of the invention as claimed. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural diagram of Embodiment 1 of the present invention.

[0029] Figure 2 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention.

[0030] Figure 3 This is a schematic cross-sectional view of the overall structure of Embodiment 1 of the present invention.

[0031] Figure 4 for Figure 3 A magnified schematic diagram of a portion of region A in the middle.

[0032] Figure 5 for Figure 3 A magnified schematic diagram of a portion of region B.

[0033] Figure 6 This is a schematic cross-sectional view of the pre-collection tube in Embodiment 1 of the present invention.

[0034] Figure 7This is a partial cross-sectional view and three-dimensional structural diagram highlighting the annular flow equalization shroud in Embodiment 1 of the present invention.

[0035] Figure 8 This is a partial cross-sectional view of the annular flow equalization shroud in Embodiment 1 of the present invention.

[0036] Figure 9 This is a partial cross-sectional view of the lower extension segment in Embodiment 2 of the present invention.

[0037] In the picture: 100. Vertical shell; 110. Upper tube sheet; 120. Lower tube sheet; 121. Tangential feed inlet; 130. Air inlet pipe; 140. Annular flow equalization hood; 141. Flow equalization chamber; 142. Flow equalization orifice; 200. Heat exchanger tube bundle; 300. Shell-side flow channel; 400. Tube-side flow channel; 410. Upper head; 420. Upper tube box; 430. Annular cylinder wall; 440. Lower head; 450. Lower tube box; 460. Flange interface; 500. Baffle plate; 510. Heat exchanger flow channel; 520. Liquid collection groove; 521. Guide surface; 600. Gas-liquid separation module; 610 620. Cyclone separation chamber; 621. Non-condensable gas buffer chamber; 630. Non-condensable gas outlet pipe; 631. Liquid phase collection tank; 632. Liquid phase outlet pipe; 640. Lower extension section; 641. Guide plate; 642. Separation channel; 650. Guide gap; 660. Gas guide hole; 670. Liquid return hole; 700. Liquid collection pipe; 710. Liquid collection hole; 800. Venturi tube; 810. Gradient section; 820. Throat section; 830. Gradient expansion section; 900. Ejector line; 910. Main ejector pipe; 920. Annular branch pipe; 930. Ejector unit pipe. Detailed Implementation

[0038] To facilitate understanding by those skilled in the art, the structure of the present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0039] Example 1 refer to Figure 1-8 This embodiment discloses a vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid, including a vertical shell 100. The vertical shell 100 is a hollow cylindrical shell. An installation cavity (not shown in the figure) extending axially is formed inside the vertical shell 100. The upper and lower sides of the installation cavity are sealed and fixed by an upper tube sheet 110 and a lower tube sheet 120, respectively. A plurality of heat exchange tube bundles 200 extending axially along the vertical shell 100 are fixedly connected between the center of the upper tube sheet 110 and the lower tube sheet 120. The outer side of the heat exchange tube bundles 200 and the inner side of the vertical shell 100, as well as the upper tube sheet 110 and the lower tube sheet 120, form a closed shell-side flow channel 300.

[0040] The vertical shell 100 is sealed and fixed at both ends along the axial direction with an upper tube box 420 and a lower tube box 450 respectively: the upper end of the upper tube sheet 110 is directly and sealed to a hemispherical upper end cap 410, and the internal space of the upper end cap 410 and the upper end face of the upper tube sheet 110 enclose the upper tube box 420; the lower end of the lower tube sheet 120 extends downward along its axial direction to form an annular cylindrical wall 430, the outer diameter of the annular cylindrical wall 430 is smaller than the outer diameter of the vertical shell 100, and the radial coverage of the annular cylindrical wall 430 at least includes the vertical projection area of ​​all heat exchange tube bundles 200, and the internal space of the annular cylindrical wall 430 forms the lower tube box 450. The upper tube box 420, the tube channels of the heat exchange tube bundles 200, and the lower tube box 450 are connected in sequence to form a tube-side flow channel 400 for cooling water flow.

[0041] The upper end cap 410 and the lower end cap 440 are respectively provided with corresponding flange interfaces 460 for introducing and drawing out cooling water. In this embodiment, the cooling water is introduced into the tube flow channel 400 from the flange interface 460 of the lower end cap 440, and after heat exchange through the heat exchange tube bundle 200, it is drawn out from the flange interface 460 of the upper end cap 410 to realize counter-current heat exchange and enhance the condensation heat transfer effect.

[0042] The top of the vertical housing 100 is provided with an air inlet pipe 130 communicating with the shell-side flow channel 300. The top of the shell-side flow channel 300 is provided with an annular flow equalization shroud 140 circumferentially distributed around its inner side. The inner side of the annular flow equalization shroud 140 forms a flow equalization cavity 141 communicating with the air inlet pipe 130. The flow equalization cavity 141 has a plurality of flow equalization holes 142 communicating with the shell-side flow channel 300 on one side wall near the central axis of the shell-side flow channel 300. The plurality of flow equalization holes 142 are evenly distributed circumferentially along the side wall of the flow equalization cavity 141. The shell-side flow channel 300 is provided with a continuous spiral baffle 500 extending along its axial direction. The spiral baffle 500 divides the shell-side flow channel 300 into a continuous spiral heat exchange flow channel 510. Nitric acid azeotropic vapor enters the flow equalization chamber 141 through the inlet pipe 130 and then enters the heat exchange flow channel 510, where it completes heat exchange and condensation with the cooling water in the heat exchange tube bundle 200 along the spiral path.

[0043] An integrated gas-liquid separation module 600 is provided on the outer periphery of the lower tube box 450. The gas-liquid separation module 600 includes a cyclone separation chamber 610 coaxially sleeved on the outer periphery of the annular cylindrical wall 430, a non-condensable gas buffer chamber 620 coaxially sleeved on the outer periphery of the cyclone separation chamber 610, and a liquid phase collection tank 630 located at the bottom of the cyclone separation chamber 610 and the non-condensable gas buffer chamber 620. The axial extension distance of the cyclone separation chamber 610 and the non-condensable gas buffer chamber 620 along the vertical shell 100 is less than the axial extension length of the annular cylindrical wall 430. The liquid phase collection tank 630 is coaxially sleeved on the lower outer side of the annular cylindrical wall 430 and is located exactly at the common bottom of the cyclone separation chamber 610 and the non-condensable gas buffer chamber 620. The outer diameters of the non-condensable gas buffer chamber 620 and the liquid phase collection tank 630 are consistent and the same as the outer diameter of the vertical shell 100, so that the condenser as a whole forms a regular cylindrical structure. The lower end of the liquid phase collection tank 630 and the annular cylindrical wall 430 is sealed with another hemispherical lower end cap 440. The internal area of ​​the lower end cap 440 is only connected to the inside of the annular cylindrical wall 430 and is not connected to the liquid phase collection tank 630 or the cyclone separation chamber 610, thus ensuring complete isolation between the tube side flow channel 400 and the shell side and separation module.

[0044] The cyclone separation chamber 610 is provided with a continuous spiral guide plate 640 extending along its axial direction. The spiral guide plate 640 divides the cyclone separation chamber 610 into a continuous spiral separation channel 641. The pitch of the guide plate 640 decreases linearly downward along its axial direction. Specifically, the ratio of its first pitch to the inner diameter of the shell-side channel 300 is 1.2:1, and the ratio of its last pitch to the inner diameter of the shell-side channel 300 is 0.6:1. The plate surface of the guide plate 640 is close to the outer wall of the non-condensable gas buffer chamber 620 along the separation channel 641, extends radially inward toward the cyclone separation chamber 610 and is inclined downward at an angle α. The design range of α is 3-5°, and in this embodiment, α is 4°. A flow guiding gap 642 is formed between the inner side of the plate surface of the guide plate 640 and the inner wall of the cyclone separation chamber 610, which is used to guide the gas-liquid mixture to flow stably along the spiral path and enhance the centrifugal separation effect. The bottom of the lower tube sheet 120 is provided with a tangential feed port 121. The top inlet of the separation channel 641 is tangentially connected to the bottom outlet of the heat exchange channel 510 through the tangential feed port 121, so that the gas-liquid mixture that has completed heat exchange in the heat exchange channel 510 enters the separation channel 641 tangentially, and the swirling kinetic energy generated during the heat exchange process is used to complete the swirling gas-liquid separation.

[0045] A plurality of air guide holes 650 are provided on the wall surface of the separation channel 641 near the non-condensable gas buffer chamber 620. The air guide holes 650 are distributed sequentially along the spiral path of the separation channel 641. The air guide holes 650 are located on the upper side of the separation channel 641 relative to the surface of the guide plate 640, that is, on the upper end of the side wall surface within a single lead area of ​​the separation channel 641. The air guide holes 650 penetrate the outer wall of the swirling separation chamber 610 tangentially along the separation channel 641. The swirling separation chamber 610 is connected to the non-condensable gas buffer chamber 620 through the air guide holes 650. A return liquid hole 660 is provided through the bottom of the outer wall surface where the air guide holes 650 are located. A non-condensable gas outlet pipe 621 is connected to the outside of the non-condensable gas buffer chamber 620 for discharging the separated non-condensable gas. The bottom of the cyclone separation chamber 610 is provided with several liquid collecting pipes 670 that communicate with the liquid collection tank 630. The top of the liquid collecting pipe 670 is provided with a funnel-shaped flare (not shown in the figure), and the flare is located below the bottom end face of the cyclone separation chamber 610. The several liquid collecting pipes 670 are evenly arranged circumferentially along the bottom of the cyclone separation chamber 610, and the bottom of the liquid collecting pipes 670 extends below the lowest designed liquid level of the liquid collection tank 630, forming a liquid seal structure to prevent gas phase from entering the liquid collection tank 630. The bottom of the liquid collection tank 630 is connected to a liquid outlet pipe 631 for discharging the finished product condensate.

[0046] The inner wall of the vertical shell 100 is circumferentially arranged with four pre-collection pipes 700. The four pre-collection pipes 700 are evenly distributed around the axial direction of the vertical shell 100 and avoid the locations of the non-condensable gas outlet pipe 621 and the liquid phase outlet pipe 631. In this embodiment, the inlet pipe 130, the non-condensable gas outlet pipe 621, and the liquid phase outlet pipe 631 are arranged in the same vertical plane to facilitate the avoidance and arrangement of the pre-collection pipes 700. The pre-collection pipes 700 penetrate all the plates of the baffle plate 500 along the same vertical line, with their upper ends extending to the bottom of the annular flow equalization hood 140 and their lower ends extending above the highest designed liquid level of the liquid phase collection tank 630.

[0047] The outer edge of the spiral baffle 500 is provided with a continuous liquid collecting groove 520 along the entire spiral path. The pre-collecting pipe 700 is longitudinally arranged through the liquid collecting groove 520. Liquid collecting holes 710 are provided at the intersections of the pre-collecting pipe 700 and the surface of the baffle 500, and the liquid collecting holes 710 are located within the coverage area of ​​the liquid collecting groove 520. The liquid collecting holes 710 are evenly distributed along the circumference of the pre-collecting pipe 700, and the bottom of the liquid collecting holes 710 is flush with the bottom of the liquid collecting groove 520. The liquid collecting groove 520 is located along the shell-side flow channel 30. The baffle plate 500 has symmetrical inclined guide surfaces 521 on both radial sides. The two guide surfaces 521 are arranged along the spiral path of the baffle plate 500. The bottom width of the liquid collection groove 520 is adapted to the outer diameter of the pre-collection pipe 700, so that the bottom of the liquid collection hole 710 is connected to the bottom of the guide surface 521 at the corresponding position. The condensate on the surface of the baffle plate 500 can be collected into the liquid collection groove 520 through the guide surface 521 and enter the pre-collection pipe 700 in real time through the liquid collection hole 710, thus completely avoiding the problem of liquid accumulation and condensate backflow on the baffle plate 500.

[0048] The downstream of the liquid phase outlet pipe 631 is connected to a Venturi tube 800. The Venturi tube 800 includes a converging section 810, a throat section 820, and a diverging section 830 connected in sequence. The outlet end of the liquid phase outlet pipe 631 is connected to the inlet of the converging section 810 of the Venturi tube 800, and the outlet of the diverging section 830 of the Venturi tube 800 is connected to the finished product conveying pipeline of the subsequent process. The throat section 820 of the Venturi tube 800 is connected to the lower side wall of the pre-collection pipe 700 through the ejector pipe 900, which is used to provide negative pressure suction power for the pre-collection pipe 700 through the liquid phase flow of the condensate.

[0049] The ejector conduit 900 includes a main ejector pipe 910, an annular branch pipe 920, and ejector unit pipes 930. The annular branch pipe 920 is coaxially arranged around the outer periphery of the liquid collection tank 630. The annular branch pipe 920 is connected to the throat section 820 of the Venturi tube 800 through the main ejector pipe 910. The number of ejector unit pipes 930 is the same as the number of pre-collection pipes 700. The inner annular side of the annular branch pipe 920 is connected to the lower end sidewall of each pre-collection pipe 700 through the ejector unit pipes 930. The main ejector pipe 910 is equipped with a one-way valve (not shown in the figure). The one-way valve is directed from the pre-collection pipe 700 to the throat section 820 of the Venturi tube 800, which can completely avoid the problem of pre-collection pipe 700 suction failure caused by condensate backflow and ensure long-term stable operation of negative pressure suction drainage.

[0050] The working process of this embodiment is as follows: The nitric acid azeotropic vapor produced at the top of the distillation column enters the shell-side flow channel 300 through the inlet pipe 130. After being evenly distributed by the annular flow equalization shroud 140, it enters the heat exchange flow channel 510 and flows along the path guided by the spiral baffle 500, completing countercurrent heat exchange with the cooling water in the heat exchange tube bundle 200. The vapor gradually condenses to form liquid nitric acid. During the condensation process, the condensate on the outer wall of the heat exchange tube bundle 200 is thrown towards the outer inner wall of the vertical shell 100 away from the center under the action of the centrifugal force of the vapor swirl and its own gravity, and converges through the guide surface 521 to... The liquid enters the pre-collection tube 700 through the collection hole 710 in the collection groove 520 of the baffle 500. When the condensate flows through the liquid phase outlet pipe 631, it is accelerated in the tapering section 810 of the venturi tube 800 and a negative pressure is formed in the throat section 820. The ejector pipe 900 provides a continuous negative pressure suction force to the pre-collection tube 700, which quickly draws the condensate in the pre-collection tube 700 away from the heat exchange area and sends it directly into the liquid phase collection tank 630. This avoids the formation of a continuous thick liquid film on the outer wall of the heat exchange tube bundle 200, reduces the additional thermal resistance, and improves the heat exchange efficiency.

[0051] The gas-liquid mixture, after heat exchange, enters tangentially into the separation channel 641 of the cyclone separation chamber 610 through the tangential feed inlet 121. Utilizing the swirling kinetic energy generated during the heat exchange process, and guided by the guide plates 640 with gradually decreasing pitch, the cyclone centrifugal separation effect is continuously enhanced. The liquid phase is thrown against the inner wall of the cyclone separation chamber 610 and flows into the liquid phase collection tank 630 through the liquid collection pipe 670. The separated non-condensable gas enters the non-condensable gas buffer chamber 620 through the gas guide hole 650 and is finally discharged through the non-condensable gas outlet pipe 621. The trace amount of condensate entrained in the non-condensable gas flows back to the liquid phase collection tank 630 through the liquid return hole 660, avoiding product yield loss. The synergistic design of pre-collection and drainage with cyclone separation significantly reduces the liquid load in the separation zone, fundamentally avoiding flooding and droplet entrainment problems, and ensuring the purity and cleanliness of electronic-grade nitric acid.

[0052] Example 2 refer to Figure 9 The difference between this embodiment and Embodiment 1 lies in the arrangement of the liquid phase outlet pipe 631 and the venturi tube 800: One end of the liquid phase outlet pipe 631 is sealed and connected to the bottom of the liquid phase collection tank 630. The other end of the liquid phase outlet pipe 631 extends out of the outer side of the gas-liquid separation module 600 and continues to extend downward to form a lower extension section 632. The lower extension section 632 then connects to the inlet of the tapered section 810 of the Venturi tube 800, so that the overall installation position of the Venturi tube 800 is lower than the lowest position of the liquid phase collection tank 630. A stable static pressure difference is formed between the liquid phase collection tank 630 and the Venturi tube 800, which further helps the smooth discharge of condensate. At the same time, it can enhance the negative pressure suction effect of the Venturi tube 800 and ensure the stability of the liquid discharge of the pre-collection pipe 700.

[0053] It should be noted that any reference signs placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0054] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0055] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid, comprising a vertical shell (100), wherein a plurality of heat exchange tube bundles (200) extending axially are formed within the vertical shell (100), a closed shell-side flow channel (300) is formed between the outer side of the heat exchange tube bundles (200) and the inner side of the vertical shell (100), and an upper tube box (420) and a lower tube box (450) are respectively sealed and fixed at both ends of the vertical shell (100) along the axial direction. The upper tube box (420), heat exchange tube bundle (200), and lower tube box (450) are sequentially connected to form a tube-side flow channel (400) for cooling water flow. The top of the vertical shell is provided with an air inlet pipe (130) communicating with the shell-side flow channel (300). A continuous spiral baffle (500) extending axially is provided within the shell-side flow channel (300) to divide it into continuous spiral heat exchange channels (510). The characteristic feature is that: A gas-liquid separation module (600) is provided on the outer periphery of the lower tube box (450). The gas-liquid separation module (600) includes a cyclone separation chamber (610) coaxially sleeved on the outer periphery of the lower tube box (450), a non-condensable gas buffer chamber (620) communicating with the cyclone separation chamber (610), and a liquid phase collection tank (630) provided at the bottom of the cyclone separation chamber (610). The bottom of the cyclone separation chamber (610) is provided with a plurality of liquid collection pipes (670) communicating with the liquid phase collection tank (630). The non-condensable gas buffer chamber (620) is connected to a non-condensable gas outlet pipe (621). The bottom of the liquid phase collection tank (630) is connected to a liquid phase outlet pipe (631). The cyclone separation chamber (610) is provided with a continuous spiral guide plate (640) extending along its axial direction to divide the cyclone separation chamber (610) into a continuous spiral separation channel (641). The bottom of the shell-side channel (300) is provided with a tangential feed port (121). The top inlet of the separation channel (641) is tangentially connected to the bottom outlet of the heat exchange channel (510) through the tangential feed port (121). The inner wall of the vertical shell (100) is provided with at least one pre-collection pipe (700) arranged circumferentially. The pre-collection pipe (700) penetrates the surface of the baffle plate (500) axially and its bottom extends into the liquid phase collection tank (630). Liquid collection holes (710) are provided at the intersection of the pre-collection pipe (700) and the surface of the baffle plate (500). The downstream of the liquid phase outlet pipe (631) is connected to a Venturi tube (800). The throat section (820) of the Venturi tube (800) is connected to the lower side wall of the pre-collection tube (700) through an ejector pipe (900) to provide negative pressure suction power to the pre-collection tube (700) through the flow of the liquid phase.

2. The vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: The separating channel (641) has several air guide holes (650) on its wall near the non-condensable gas buffer chamber (620). The air guide holes (650) are distributed sequentially along the spiral path of the separating channel (641). The swirling separation chamber (610) is connected to the non-condensable gas buffer chamber (620) through the air guide holes (650). A return liquid hole (660) is provided through the bottom of the outer wall where the air guide holes (650) are located.

3. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 2, characterized in that: The air guide hole (650) is located on the upper side of the guide plate (640) in the separation channel (641), and the air guide hole (650) penetrates the outer wall of the swirling separation chamber (610) tangentially along the separation channel (641).

4. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: The surface of the guide plate (640) extends radially inward and downward toward the swirling separation chamber (610) along the outer wall of the non-condensable gas buffer chamber (620) near the separation channel (641), and a guide gap (642) is formed between the inner side of the guide plate (640) and the inner wall of the swirling separation chamber (610).

5. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: Several of the liquid collecting pipes (670) are evenly arranged circumferentially along the bottom of the cyclone separation chamber (610), and the bottom of the liquid collecting pipes (670) extends below the lowest designed liquid level of the liquid phase collection tank (630).

6. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: The outer edge of the baffle plate (500) is provided with a continuous liquid collection groove (520) along the spiral path. The pre-collection pipe (700) passes through the liquid collection groove (520) longitudinally, and the liquid collection hole (710) is located within the coverage area of ​​the liquid collection groove (520).

7. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 6, characterized in that: The liquid collecting holes (710) are uniformly arranged along the circumference of the pre-collecting pipe (700) and their bottoms are flush with the bottoms of the liquid collecting grooves (520). The liquid collecting grooves (520) are symmetrically provided with inclined guide surfaces (521) on both sides of the radial side of the shell-side flow channel (300). The two guide surfaces (521) are arranged along the spiral path of the baffle plate (500) throughout. The bottom width of the liquid collecting grooves (520) is adapted to the outer diameter of the pre-collecting pipe (700) so that the bottom of the liquid collecting holes (710) is connected to the bottom of the guide surfaces (521) at the corresponding positions.

8. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: The ejector conduit (900) includes a main ejector pipe (910), an annular branch pipe (920), and ejector unit pipes (930). The annular branch pipe (920) is coaxially arranged around the outer periphery of the liquid phase collection tank (630). The annular branch pipe (920) is connected to the throat section (820) of the venturi tube (800) through the main ejector pipe (910). The number of ejector unit pipes (930) is the same as that of the pre-collection pipe (700). The annular inner side of the annular branch pipe (920) is connected to the lower end sidewall of the pre-collection pipe (700) through the ejector unit pipe (930). The main ejector pipe (910) is equipped with a one-way valve. The conduction direction of the one-way valve is from the pre-collection pipe (700) to the throat section (820) of the venturi tube (800).

9. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: The pitch of the guide plate (640) decreases linearly downwards along its axial direction. The ratio of the pitch of its first section to the inner diameter of the shell-side flow channel (300) is 1.2:1, and the ratio of the pitch of its last section to the inner diameter of the shell-side flow channel (300) is 0.6:

1.

10. A vertical shell-and-tube heat exchanger for the preparation and processing of electronic-grade nitric acid according to claim 1, characterized in that: The top of the shell-side flow channel (300) is provided with an annular flow equalization shroud (140) that is circumferentially distributed around its inner side. The inner side of the annular flow equalization shroud (140) forms a flow equalization cavity (141) that communicates with the air intake pipe (130). The flow equalization cavity (141) has a plurality of flow equalization holes (142) communicating with the shell-side flow channel (300) on one side wall near the central axis of the shell-side flow channel (300). The plurality of flow equalization holes (142) are evenly distributed circumferentially along the side wall of the flow equalization cavity (141).

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