Heat exchanger system capable of inputting heat source in stages

Abstract

The invention provides a heat exchanger system capable of inputting a heat source in stages, a plurality of heat exchanger shells are of a series connection structure, in two adjacent heat exchangers, a mixed fluid outlet pipe of an upstream heat exchanger is a cold source inlet pipe of a downstream heat exchanger, steam enters a heat exchange pipe in stages from a steam inlet of each heat exchanger, and the cold source inlet pipe is a cold source inlet pipe of the downstream heat exchanger. Steam outlet holes for steam injection are formed in the heat exchange pipe, and steam is ejected from the steam outlet holes to exchange heat with liquid in the pipe shell. Through the arrangement of the multiple heat exchangers and the shell pass series connection structure of the heat exchangers, steam of the tube pass is input in a staged mode, fluid in the shell pass is mixed in a staged mode, and therefore the mixing uniformity of the two kinds of fluid is improved, and the mixing heat exchange effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of heat exchangers, and particularly relates to a heat exchanger system with direct mixing heat exchange through a staged input heat source. Background Technology A heat exchanger is an energy-saving device that facilitates heat transfer between two or more fluids at different temperatures. It transfers heat from a higher-temperature fluid to a lower-temperature fluid, bringing the fluid temperature to the specified parameters to meet process requirements. It is also one of the key devices for improving energy efficiency. The heat exchanger industry involves nearly 30 sectors, including HVAC, pressure vessels, wastewater treatment equipment, chemicals, and petroleum, forming interconnected industrial chains.

[0002] Vapor-liquid mixing heat exchangers, as a common type of heat exchanger, are now widely used in systems for heating domestic and industrial hot water, as well as in hot water heating and thermal deaeration. Vapor-liquid mixing heaters can directly mix waste heat steam from the production processes of steel plants, chemical plants, and thermal power plants with water to heat it. This hot water can meet the requirements of some industrial processes such as printing and dyeing, food processing, building HVAC, and daily residential use. The application of vapor-liquid mixing heaters effectively utilizes waste heat from industrial processes, reduces the consumption of fossil fuels by heat energy users, lowers production and operating costs, and correspondingly reduces emissions of greenhouse gases such as carbon dioxide. It is an effective way to rationally utilize energy and reduce environmental pollution.

[0003] In the prior art, CN101144616A discloses a dynamically adjustable variable-speed pressurized heat exchanger, which mainly consists of a front two-way valve, a steam nozzle, a middle three-way valve, an adjustable core, a middle two-way valve, a diffuser, and a rear two-way valve. The steam nozzle is coaxially arranged inside the middle three-way valve. An adjustable core is arranged between the middle three-way valve and the middle two-way valve. This adjustable core can move axially back and forth horizontally. The center of the adjustable core has an axially penetrating mixing chamber, which is composed of a conical curve section and a horizontal straight section. The conical curve section is the flow rate adjustment section, and the horizontal straight section is the pressure adjustment section. The diffuser is nested between the middle two-way valve and the rear two-way valve. This invention achieves dynamic adjustment when the steam-water parameters change without stopping the system operation. It also keeps the steam-water mixing mass ratio and pressure ratio in the heat exchanger at the optimal state, effectively reducing equipment operating noise and operating costs, and improving its heat exchange efficiency and operational safety.

[0004] CN200996796Y discloses a vapor-liquid mixing steam generator for treating acidic wastewater in furfural process wastewater treatment. This steam generator consists of multiple layers of sieve plates evenly distributed from bottom to top within the shell, a water distributor located in the center of the shell corresponding to the wastewater inlet, and a vapor-liquid separator at the top, connected to the water distributor via a drain pipe. It fully utilizes steam discharged from the next-stage steam heating device for heating. It has advantages such as simple structure, reasonable design, stable performance, convenient use, economic practicality, and suitability for widespread application.

[0005] CN201016582Y provides a duplex steam-driven energy-saving heat exchanger, relating to a heat exchange device. It adopts a multi-stage duplex structure, adding a secondary steam annular nozzle to the existing technology, which together with the primary mixing chamber forms an annular nozzle, i.e., an O-shaped nozzle and an annular nozzle; a secondary mixing chamber and a tertiary mixing chamber are added after the primary mixing chamber, forming three mixing chambers and a diffuser chamber. This invention further increases the head and flow rate, reduces vibration and noise, and has advantages such as high head, low vibration, low noise, stable operating performance, strong adaptability to changing operating conditions, and wider applicability.

[0006] CN202119285U describes a direct-mixing steam-water heat exchanger, comprising an outer cylinder mounted on a support frame. The outer cylinder has a water inlet pipe at its bottom and an air inlet pipe at its top. An upper baffle and a lower baffle are fixedly installed inside the outer cylinder. The cavity at the top of the upper baffle is the air inlet area, and the cavity below the lower baffle is the water inlet area. An extended inner cylinder is mounted on the lower baffle. A water outlet connecting the water inlet area and the inner cylinder's inner cavity is located in the middle of the lower baffle. A water passage is provided between the top of the inner cylinder and the upper baffle. A baffle is installed between the upper baffle and the air inlet pipe. Multiple air vents extending from the top surface of the upper baffle and close to the lower baffle are mounted on the upper baffle. A water outlet pipe is connected to the lower middle part of the outer cylinder. This invention has a simple structure, can fully utilize the heat of steam, and has the advantages of high thermal efficiency and low cost.

[0007] In existing technologies, both steam and liquid are input for heat exchange in a single process, which results in significant heat exchange imbalance. The two fluids are prone to uneven mixing, leading to poor heat exchange performance.

[0008] To address the aforementioned problems, this invention improves the heat exchanger by introducing steam into the heat exchanger system in stages, achieving multi-stage mixing and making the two fluids mix more evenly, thereby improving the heat exchange effect. Summary of the Invention

[0009] This invention provides a heat exchanger system with a phased input heat source, thereby solving the aforementioned technical problems.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows: A heat exchanger system with a staged heat source input includes multiple heat exchangers. Each heat exchanger includes a shell, a header, a tube sheet, and heat exchange tubes disposed within the shell. A first tube sheet is disposed at one end of the shell, and the other end is connected to the header. A second tube sheet is disposed between the header and the shell. A first end and a second section of the heat exchange tubes are respectively connected to the first tube sheet and the second tube sheet, wherein the first end is a closed end, and the second end passes through the second tube sheet and communicates with the header. A steam inlet is disposed on the header. A liquid inlet pipe and a mixed fluid outlet pipe are respectively disposed on the shell. The system is characterized in that the multiple heat exchanger shells are connected in series, wherein in two adjacent heat exchangers, the liquid outlet pipe of the upstream heat exchanger is the liquid inlet pipe of the downstream heat exchanger. Steam enters the heat exchange tubes in stages from the steam inlet of each heat exchanger. Steam jet outlets are disposed on the heat exchange tubes, and steam is ejected from the outlets to exchange heat with the liquid inside the tube shells.

[0011] As an improvement, the steam flow rate of each steam inlet can be controlled independently, and the control system can control the amount of steam input at each stage by controlling the steam flow rate of each steam inlet.

[0012] As an improvement, the steam input of different heat exchangers is gradually increased along the direction of liquid flow inside the shell.

[0013] As an improvement, the rate of increase in steam input for different heat exchangers gradually increases along the direction of liquid flow within the shell.

[0014] As an improvement, a connecting valve is installed on the liquid outlet pipe of the upstream heat exchanger, which can control the rate at which the mixed fluid flows into the next heat exchanger.

[0015] As an improvement, the opening degree of different connecting valves is different along the direction of liquid flow inside the shell, and the opening degree of different connecting valves gradually increases along the direction of liquid flow inside the shell.

[0016] As an improvement, the opening degree of different connecting valves is different along the direction of liquid flow inside the shell, and the magnitude of the increase in the opening degree of different connecting valves gradually increases along the direction of liquid flow inside the shell.

[0017] As an improvement, the liquid inlet pipe is positioned closer to the header.

[0018] As an improvement, the heat exchange tube is divided into two sections. The first section is from the second tube sheet to position A, and the second section is from position A to the first tube sheet. The first section does not have a steam outlet, while the second section does.

[0019] As an improvement, the distance from position A to the first tube sheet is 15-50% of the length of the heat exchange tube.

[0020] Compared with the prior art, the present invention has the following advantages: This invention improves the mixing uniformity of the two fluids and thus enhances the mixing heat exchange effect by setting up multiple heat exchangers with a shell-side series structure, allowing the steam in the tube side to be input in stages and the fluid in the shell side to be mixed in stages. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the heat exchanger system of the present invention; Figure 2 This is a schematic diagram of the structure of a single heat exchanger of the present invention; Figure 3 This is a schematic diagram of the improved cross-sectional structure of the heat exchange tube of the present invention. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this article, unless otherwise specified, when formulas are involved, " / " represents division, and "×" and "*" represent multiplication. The left and right references in this invention are relative positions and are not required to be set horizontally.

[0023] Figure 1 A heat exchanger system with a staged heat source input is disclosed. For example... Figure 1 As shown, the heat exchanger system with a phased input heat source includes multiple heat exchangers 1. Each heat exchanger includes a shell 11, a header 12, tube sheets 13-14, and heat exchange tubes 15 disposed within the shell 11. A first tube sheet 13 is disposed at one end of the shell, and the other end is connected to the header 12. A second tube sheet 14 is disposed between the header 12 and the shell 11. The first end 151 and the second end 152 of the heat exchange tube 15 are respectively connected to the first tube sheet 13 and the second tube sheet 14, wherein the first end 151 is a closed end, and the second end 152 penetrates the first tube sheet 13 and the second tube sheet 14. The tube sheet is connected to the header 12, which is equipped with a steam inlet 16. The shell 11 is equipped with a cold source inlet pipe 17 and a mixed fluid outlet pipe 18. The shells of the multiple heat exchangers 1 are connected in series. In two adjacent heat exchangers 1, the mixed fluid outlet pipe of the upstream heat exchanger is the cold source inlet pipe 17 of the downstream heat exchanger. Steam enters the heat exchange tubes in stages from the steam inlet of each heat exchanger. The heat exchange tubes are equipped with steam injection outlet holes 19, from which steam is ejected to exchange heat with the cold source inside the tube shell. The cold source is a liquid.

[0024] This invention improves the mixing uniformity of the two fluids and thus enhances the mixing heat exchange effect by setting up multiple heat exchangers with a shell-side series structure, allowing the steam in the tube side to be input in stages and the fluid in the shell side to be mixed in stages.

[0025] As an improvement, the steam flow rate at each steam inlet can be controlled independently. The control system can control the steam input at each stage by controlling the steam flow rate at each steam inlet. This setting allows for free control of the steam input at each stage, thereby enabling temperature control at each stage. For example, if the temperature increases at a certain stage, the steam input can be increased; if the temperature decreases at a certain stage, the steam input can be reduced or stopped.

[0026] As an improvement, the steam input to different heat exchangers gradually increases along the flow direction of the fluid within the shell, from upstream to downstream. Because the upstream heat exchanger has the lowest cold source temperature and the best heat exchange effect with the steam, controlling the amount of steam upstream ensures that the heat exchange capacity of each heat exchanger is essentially the same, avoiding heat exchange concentration upstream. This achieves uniform heat exchange throughout the fluid flow within the shell, creating a counter-current-like heat exchange effect and thus improving heat exchange efficiency.

[0027] As an improvement, the rate of increase in steam input to different heat exchangers gradually increases along the direction of liquid flow within the shell. This variation in rate further ensures uniform heat transfer throughout the fluid flow within the shell, achieving a counter-current-like heat transfer effect and thus improving heat transfer efficiency.

[0028] As an improvement, a connecting valve is installed on the liquid outlet pipe of the upstream heat exchanger. This valve allows control over the rate at which the mixed fluid flows into the next heat exchanger. The valve also controls the mixing time of the heat exchange fluids within the heat exchanger, thereby dynamically adjusting the heat exchange efficiency.

[0029] As an improvement, the opening degrees of different connecting valves vary along the direction of liquid flow within the shell, gradually decreasing as the liquid flows. Because the upstream heat exchanger has the lowest cold source temperature and the best heat exchange effect with steam, by controlling the upstream valve opening to be larger and the downstream valve opening to be smaller, the heat exchange capacity of each heat exchanger can be controlled to be basically the same, avoiding heat exchange concentrated in the upstream. This achieves uniform heat exchange throughout the fluid flow within the shell, realizing a counter-current heat exchange effect and thus promoting improved heat exchange efficiency.

[0030] As an improvement, the opening degrees of different connecting valves vary along the direction of liquid flow within the casing, and the rate at which the opening degrees of different connecting valves gradually decrease increases along the same direction of liquid flow. This variation in magnitude further ensures uniform heat transfer throughout the fluid flow within the casing, achieving a counter-current-like heat transfer effect, thereby promoting improved heat transfer efficiency.

[0031] As an improvement, the cold source inlet pipe is positioned close to the header. This location allows the cold source and steam to be on the same side, enabling the two fluids to mix directly and quickly.

[0032] The mixing fluid outlet pipe is located near the first tube sheet. This allows for a longer fluid flow path within the shell side, resulting in more uniform heat exchange and mixing.

[0033] As an improvement, the heat exchange tube is divided into two sections. The first section is from the second tube sheet to position A, and the second section is from position A to the first tube sheet. The first section does not have a steam outlet, while the second section does.

[0034] Because the second tube sheet is the steam inlet, and the steam has a certain pressure and temperature, direct injection would generate significant noise. This invention addresses this by not providing steam outlets from the second tube sheet to position A, and instead employing indirect heat exchange via a partitioned heat exchange tube at the location of highest steam temperature and pressure. This reduces the steam pressure and temperature, allowing it to cool and depressurize before entering the heat exchange tube for injection, thus reducing steam injection noise. Furthermore, as the steam flows, its temperature decreases, and the heat exchange capacity between the steam and liquid diminishes, resulting in a gradual decrease in heat exchange efficiency along the steam's direction of movement. This application employs a combination of indirect and direct heat exchange, utilizing indirect heat exchange at high steam temperatures and direct heat exchange at low steam temperatures. Since direct heat exchange is more efficient than indirect heat exchange, this approach ensures relatively uniform heat exchange throughout the entire heat exchange tube direction, avoiding localized uneven heat exchange.

[0035] As an improvement, the distance from position A to the first tube sheet is 15-50% of the total length of the heat exchange tubes. This distance is also an optimization result, which can reduce noise while ensuring optimal heat exchange efficiency.

[0036] As an improvement, position A varies within different heat exchangers, and the distance from position A to the second tube sheet increases along the flow direction of the fluid within the shell. Because the upstream heat exchanger has the lowest cold source temperature and the best heat exchange effect with the steam, the steam temperature and pressure decrease rapidly. As the fluid flows, the heat exchange efficiency between the steam and the cold source gradually decreases. Therefore, it is necessary to increase the heat exchange area without steam outlets to reduce the steam temperature and pressure, thereby reducing noise.

[0037] As an improvement, the distance from position A within the heat exchanger to the second tube sheet increases progressively along the flow direction of the fluid inside the shell. This arrangement can further reduce the temperature and pressure of the steam, and further reduce noise.

[0038] As an improvement, the cold source is cold water, the steam is water vapor, and the final output mixed fluid is hot water.

[0039] As an improvement, the heat exchange tube has a triangular cross-section.

[0040] As an improvement, the tube wall is arc-shaped, the curvature of which is directed toward the center of the equilateral triangle, and steam outlet holes are formed on the tube wall to spray steam from inside the heat exchange tube to the outside.

[0041] The heat exchange tube of the present invention increases the heat exchange area by modifying the triangular tube into an inwardly curved shape; moreover, because of the inwardly curved tube wall, the fluid inside the tube flows more from the center of the tube to the apex of the tube, thereby increasing the pressure at the corner. Compared with other shapes, it reduces the flow dead zone and avoids uneven spraying caused by uneven fluid distribution at different positions, thereby making the overall sprayed fluid uniform.

[0042] This application improves the shape of the triangular tube wall by making it bend inward, which increases the flow area of ​​the external fluid and the mixing area and mixing time of the two fluids, thereby making the mixing more uniform and the heat exchange effect better.

[0043] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A heat exchanger system with a staged input heat source, the system comprising multiple heat exchangers, each heat exchanger comprising a shell, a header, a tube sheet, and heat exchange tubes disposed within the shell, wherein a first tube sheet is disposed at one end of the shell, and the other end is connected to the header, a second tube sheet is disposed between the header and the shell, a first end and a second end of the heat exchange tubes are respectively connected to the first tube sheet and the second tube sheet, wherein the first end is a closed end, and the second end passes through the second tube sheet and communicates with the header, a steam inlet is disposed on the header, and a cold source inlet pipe and a mixed fluid outlet pipe are respectively disposed on the shell; characterized in that... The multiple heat exchanger shells are connected in series. In two adjacent heat exchangers, the mixing fluid outlet pipe of the upstream heat exchanger is the cold source inlet pipe of the downstream heat exchanger. Steam enters the heat exchange tube in stages from the steam inlet of each heat exchanger. Steam jet outlet holes are provided on the heat exchange tubes. Steam is ejected from the outlet holes and exchanges heat with the liquid inside the tube shell.

2. The heat exchanger system as claimed in claim 1, characterized in that, The steam flow rate at each steam inlet can be controlled independently. The control system can control the steam input at each stage by controlling the steam flow rate at each steam inlet.

3. The heat exchanger system as claimed in claim 2, characterized in that, Along the direction of liquid flow inside the shell, the steam input gradually increases for different heat exchangers.

4. The heat exchanger system as claimed in claim 3, characterized in that, Along the direction of liquid flow inside the shell, the rate of increase in steam input gradually increases for different heat exchangers.

5. The heat exchanger system as claimed in claim 1, characterized in that, A connecting valve is installed on the liquid outlet pipe of the upstream heat exchanger, which can control the rate at which the mixed fluid flows into the next heat exchanger.

6. The heat exchanger system as claimed in claim 5, characterized in that, Along the direction of liquid flow within the casing, the opening degree of different connecting valves varies, and along the direction of liquid flow within the casing, the opening degree of different connecting valves gradually decreases.

7. The heat exchanger system of claim 6, characterized in that, Along the direction of liquid flow inside the casing, the opening degree of different connecting valves is different, and the rate at which the opening degree of different connecting valves gradually decreases along the direction of liquid flow inside the casing becomes increasingly larger.

8. The heat exchanger system as claimed in claim 1, characterized in that, The liquid inlet pipe is located near the header.

9. The heat exchanger system of claim 8, characterized in that, The heat exchange tube is divided into two sections. The first section is from the second tube sheet to position A, and the second section is from position A to the first tube sheet. The first section does not have a steam outlet, while the second section does.

10. The heat exchanger system of claim 9, characterized in that, The distance from position A to the first tube sheet is 15-50% of the length of the heat exchange tube.

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