Novel plate heat exchanger of solid oxide fuel cell combined heat and power generation system

Abstract

A novel plate heat exchanger of a solid oxide fuel cell combined heat and power generation system comprises a heat exchange shell used as a pressure container and a plate bundle which is fixedly assembled in the heat exchange shell and is of a cuboid structure, and the plate bundle is formed by alternately stacking a plurality of first corrugated plates and second corrugated plates front and back. The adjacent first corrugated plates and second corrugated plates are welded through spacing elements, cold fluid channels and hot fluid channels which are alternately arranged are correspondingly formed between the first corrugated plates and the second corrugated plates, and the corrugations of the first corrugated plates and the corrugations of the second corrugated plates are semi-elliptical corrugations. Sine-shaped flow guide inserts are welded to an inlet and an outlet of the hot fluid channel. The novel heat exchanger is favorable for reducing pressure loss, meets the low-pressure-drop working requirement of the novel heat exchanger, can be applied to the high-temperature working condition of an SOFC (Solid Oxide Fuel Cell) combined heat and power generation system, can enhance the turbulence effect, is favorable for reducing flowing dead zones and improves the heat exchange efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of heat exchangers, specifically, to a novel plate heat exchanger for a solid oxide fuel cell combined heat and power generation system. Background Art

[0002] As a key component in the thermal management subsystem of a solid oxide fuel cell (SOFC), the heat exchanger is mainly used to ensure the long-term stable operation of the SOFC, and to recover and utilize waste heat as well as process the unburned anode exhaust gas. Currently, plate heat exchangers are mostly used as heat exchange equipment in SOFC combined heat and power generation systems. The plate heat exchanger is combined with a micro gas turbine system to improve the power generation efficiency of the entire SOFC combined heat and power generation system. A plate heat exchanger is a common high-efficiency and energy-saving heat exchange device. Compared with shell-and-tube heat exchangers and plate-and-shell heat exchangers, it has many advantages such as a compact structure, high heat transfer efficiency, and a large heat exchange area. Inside the plate heat exchanger, multiple groups of metal plates are stacked in parallel to form a sealed and compact fluid channel. The cold and hot fluids flow in the odd and even channels respectively. Heat exchange is carried out through the plate by relying on the temperature difference on both sides. Most of the plates of the plate heat exchanger are corrugated plates. Currently, there are three common forms of corrugated plates, namely inclined corrugations, herringbone corrugations, and double herringbone corrugations. The combination method of each type of plate is to combine the plates after flipping them 180°, and the corrugations between the plates will form point contacts.

[0003] The heat exchanger in the SOFC combined heat and power generation system needs to meet the requirements of adapting to high-temperature working conditions, and also needs to meet the design requirements of high compactness, strong heat exchange capacity, and low pressure drop. However, the plate structure inside the existing plate heat exchangers used for solid oxide fuel cell combined heat and power generation is relatively single, with a large pressure loss, many flow dead zones, and still a relatively low heat exchange efficiency. Summary of the Invention

[0004] The purpose of the utility model is to address the deficiencies of the prior art, and thus provide a novel plate heat exchanger for a solid oxide fuel cell combined heat and power generation system. The utility model helps to reduce the pressure loss, meet the working requirements of low pressure drop, can be applied to the high-temperature working conditions of the SOFC combined heat and power generation system, and at the same time can enhance the turbulent flow effect, help to reduce the flow dead zones, and improve the heat exchange efficiency.

[0005] To achieve the above purpose, the technical solution adopted by the utility model is: a novel plate heat exchanger for a solid oxide fuel cell combined heat and power generation system, including a heat exchange shell used as a pressure vessel and a plate bundle with a cuboid structure fixedly assembled inside the heat exchange shell. A cold fluid inlet and a hot fluid outlet are arranged at the top of the heat exchange shell at intervals left and right. A hot fluid inlet and a cold fluid outlet are arranged at the bottom of the heat exchange shell at intervals left and right. The cold fluid inlet and the hot fluid inlet are vertically corresponding, and the hot fluid outlet and the cold fluid outlet are vertically corresponding;

[0006] The tube bundle is composed of a number of first corrugated plates and second corrugated plates stacked alternately before and after. The adjacent first corrugated plates and second corrugated plates are welded through spacer elements. Alternately arranged cold fluid channels and hot fluid channels are formed between each first corrugated plate and second corrugated plate. The inlet of the cold fluid channel is located at the upper end of the tube bundle, and the outlet of the cold fluid channel is located at the lower end of the tube bundle. The inlet of the hot fluid channel is located on the left side of the tube bundle, and the outlet of the hot fluid channel is located on the right side of the tube bundle. The tube bundle is arranged obliquely to the left in the heat exchange housing. The right side edge of the upper end of the tube bundle is sealed and welded to the middle of the inner top surface of the heat exchange housing and is located between the cold fluid inlet and the hot fluid outlet. The left side edge of the upper end of the tube bundle is sealed and welded to the upper side part of the inner left wall of the heat exchange housing. The left side edge of the lower end of the tube bundle is sealed and welded to the middle of the inner bottom surface of the heat exchange housing and is located between the hot fluid inlet and the cold fluid outlet. The right side edge of the lower end of the tube bundle is sealed and welded to the lower side part of the inner right wall of the heat exchange housing. The cold fluid inlet corresponds to the upper end of the tube bundle vertically and is communicated with the inlet of the cold fluid channel. The cold fluid outlet corresponds to the lower end of the tube bundle vertically and is communicated with the outlet of the cold fluid channel. The hot fluid inlet corresponds to the left side of the tube bundle vertically and is communicated with the inlet of the hot fluid channel. The hot fluid outlet corresponds to the right side of the tube bundle vertically and is communicated with the outlet of the hot fluid channel;

[0007] The corrugations of both the first corrugated plate and the second corrugated plate are semi-elliptical corrugations. Sinusoidal flow guide inserts are welded at both the inlet and outlet of the hot fluid channel.

[0008] Based on the above, the first corrugated plate and the second corrugated plate are made of Inconel 617 alloy.

[0009] Based on the above, a number of parallel and equally spaced first corrugated grooves are uniformly distributed on the first corrugated plate and are arranged obliquely from the upper left to the lower right. The length of the first corrugated grooves gradually decreases from the middle of the first corrugated plate to both sides. A first corrugated protrusion is provided between two adjacent first corrugated grooves in the middle area. The first corrugated protrusion is parallel to the first corrugated grooves. The length of the first corrugated protrusion gradually decreases from the middle of the first corrugated plate to both sides. The maximum length of the first corrugated protrusion is less than the maximum length of the first corrugated grooves. The cross-sections of both the first corrugated protrusion and the first corrugated grooves are semi-elliptical.

[0010] Based on the above, a number of second corrugated protrusions that are parallel, equally spaced, and inclined from the lower left to the upper right are evenly distributed on the second corrugated sheet. The length of the second corrugated protrusions gradually decreases from the middle of the second corrugated sheet to both sides. A second corrugated groove is provided between two adjacent second corrugated protrusions in the middle region. The second corrugated protrusions are parallel to the second corrugated grooves. The length of the second corrugated grooves gradually decreases from the middle of the second corrugated sheet to both sides. The maximum length of the second corrugated grooves is less than the maximum length of the second corrugated protrusions. The cross-sections of both the second corrugated protrusions and the second corrugated grooves are semi-elliptical.

[0011] The utility model has substantial features and progress compared with the prior art. Specifically, the utility model has the following advantages:

[0012] (1) The corrugations of the first corrugated sheet and the second corrugated sheet are both semi-elliptical corrugations. The wave peaks and wave valleys of this semi-elliptical corrugation cross-section form are relatively smooth compared with the traditional sine-shaped corrugations. When the fluid flows through here, the flow resistance can be effectively reduced, meeting the low-pressure drop use requirements of SOFC cogeneration. In addition, the manufacturing of the semi-elliptical corrugations is relatively simple compared with the traditional sine-shaped corrugations and is easy to manufacture and produce during reprocessing; in order to enable the hot fluid to enter the hot fluid channel more evenly and flow more fully, sine-shaped flow guide inserts are welded at both the inlet and outlet of the hot fluid channel;

[0013] (2) The first corrugated sheet and the second corrugated sheet are made of Inconel 617 alloy. The Inconel 617 alloy has good high-temperature performance and corrosion resistance and can be applied to the high-temperature working conditions of the SOFC cogeneration system.

[0014] (3) The combination of the first corrugated protrusions and the first corrugated grooves on the first corrugated sheet and the combination of the second corrugated protrusions and the second corrugated grooves on the second corrugated sheet enable the cold fluid channel and the hot fluid channel to form a flow guide heat exchange area in the left and right regions inside the plate bundle, and form a main heat exchange area in the middle region inside the plate bundle, which can enhance the turbulence effect, help reduce the flow dead zone, and improve the heat exchange efficiency. Description of the Drawings

[0015] Figure 1 It is a schematic structural view of the utility model, and only half of the plate bundle is shown.

[0016] Figure 2 It is a schematic structural view of several first corrugated sheets and second corrugated sheets of the utility model stacked alternately.

[0017] Figure 3 It is a front view of the first corrugated sheet of the utility model.

[0018] Figure 4 It is an axonometric view of the first corrugated sheet of the utility model.

[0019] Figure 5 It is the front view of the second corrugated plate of the present utility model.

[0020] Figure 6 It is the axonometric view of the second corrugated plate of the present utility model.

[0021] Figure 7 It is Figure 2 The partial enlarged view at position A in

[0022] Figure 8 It is Figure 2 The partial enlarged view at position B in

[0023] Figure 9 It is Figure 3 The sectional view taken along the C-C direction in

[0024] Figure 10 It is Figure 5 The sectional view taken along the D-D direction in

[0025] In the figure: 1. Heat exchange shell; 2. Tube bundle; 3. Cold fluid inlet; 4. Cold fluid outlet; 5. Hot fluid inlet; 6. Hot fluid outlet; 7. First corrugated plate; 8. Second corrugated plate; 9. Flow guiding heat exchange area; 10. Main heat exchange area; 11. First corrugated groove; 12. First corrugated protrusion; 13. Second corrugated protrusion; 14. Second corrugated groove; 15. Spacer element; 16. Cold fluid channel; 17. Hot fluid channel; 18. Sinusoidal flow guiding insert. Specific embodiments

[0026] The technical solution of the present utility model will be further described in detail below through specific embodiments.

[0027] As Figures 1 to 10 shown, a novel plate heat exchanger for a solid oxide fuel cell cogeneration system includes a heat exchange shell 1 serving as a pressure vessel and a tube bundle 2 with a cuboid structure fixedly assembled inside the heat exchange shell 1. A cold fluid inlet 3 and a hot fluid outlet 6 are arranged at intervals on the top of the heat exchange shell 1, and a hot fluid inlet 5 and a cold fluid outlet 4 are arranged at intervals on the bottom of the heat exchange shell 1. The cold fluid inlet 3 and the hot fluid inlet 5 are vertically corresponding, and the hot fluid outlet 6 and the cold fluid outlet 4 are vertically corresponding;

[0028] The tube bundle 2 is composed of a plurality of first corrugated plates 7 and second corrugated plates 8 stacked alternately back and forth, and adjacent first corrugated plates 7 and second corrugated plates 8 are welded through spacer elements 15;

[0029] Corresponding cold fluid channels 16 and hot fluid channels 17 are alternately arranged between each first corrugated plate 7 and second corrugated plate 8. The inlet of the cold fluid channel 16 is located at the upper end of the plate bundle 2, and the outlet of the cold fluid channel 16 is located at the lower end of the plate bundle 2. The inlet of the hot fluid channel 17 is located on the left side of the plate bundle 2, and the outlet of the hot fluid channel 17 is located on the right side of the plate bundle 2. The plate bundle 2 is arranged obliquely to the left in the heat exchange housing 1. The upper right side of the upper end of the plate bundle 2 is sealed and welded to the middle of the inner top surface of the heat exchange housing 1 and is located between the cold fluid inlet 3 and the hot fluid outlet 6. The upper left side of the upper end of the plate bundle 2 is sealed and welded to the upper side of the inner left wall of the heat exchange housing 1. The lower left side of the lower end of the plate bundle 2 is sealed and welded to the middle of the inner bottom surface of the heat exchange housing 1 and is located between the hot fluid inlet 5 and the cold fluid outlet 4. The lower right side of the lower end of the plate bundle 2 is sealed and welded to the lower side of the inner right wall of the heat exchange housing 1. The cold fluid inlet 3 corresponds to the upper end of the plate bundle 2 up and down and is communicated with the inlet of the cold fluid channel 16. The cold fluid outlet 4 corresponds to the lower end of the plate bundle 2 up and down and is communicated with the outlet of the cold fluid channel 16. The hot fluid inlet 5 corresponds to the left side of the plate bundle 2 up and down and is communicated with the inlet of the hot fluid channel 17. The hot fluid outlet 6 corresponds to the right side of the plate bundle 2 up and down and is communicated with the outlet of the hot fluid channel 17;

[0030] The corrugations of the first corrugated plate 7 and the second corrugated plate 8 are both semi-elliptical corrugations, and sine-shaped flow guide inserts 18 are welded at both the inlet and the outlet of the hot fluid channel 17. The structure of the tube bundle 2 here is an improvement based on the stack disclosed in Chinese Patent CN201710133031.8. The difference is that the corrugated plates (serrated inserts) at the inlets and outlets of the cold fluid channel 16 are removed from the tube bundle 2 in this embodiment, and the corrugated plates (serrated inserts) at the inlets and outlets of the hot fluid channel 17 are replaced with sine-shaped flow guide inserts 18. This is because the inlets and outlets of the cold fluid channel 16 are respectively located at the short side edges of the upper and lower ends of the tube bundle 2, and the size of the tube bundle 2 itself is small, and the lengths of the inlets and outlets of the cold fluid channel 16 are even shorter. In order to achieve low pressure drop and smooth flow of the cold fluid, the inlets and outlets of the cold fluid channel 16 are designed without flow guide inserts. While the inlets and outlets of the hot fluid channel 17 are respectively located at the long side edges of the left and right sides of the tube bundle 2, and the lengths of the inlets and outlets of the hot fluid channel 17 are longer. In order to enable the hot fluid to enter the hot fluid channel 17 more evenly and flow more fully, sine-shaped flow guide inserts 18 are welded at the inlets and outlets of the hot fluid channel 17. The sine-shaped flow guide inserts 18 mainly play a role in guiding the flow. Compared with the serrated insert structure, the smooth curve of the sine-shaped flow guide inserts 18 can make the fluid flow more evenly. Due to the continuously fluctuating curve design of the sine-shaped flow guide inserts 18, after the hot fluid enters the tube bundle 2 from the inlet of the hot fluid channel 17, the hot fluid is more evenly distributed in the tube bundle 2. Especially in the case of a relatively high flow rate, a stable flow field can be maintained. In addition, compared with the serrated insert structure, the smooth curve of the sine wave of the sine-shaped flow guide inserts 18 distributes the stress of the material more evenly during the welding process. Since it has no sharp edges and corners, during the process of thermal expansion or contraction, stress concentration is not likely to occur at the welding points. This not only improves the stability of the processing process, but also reduces the fatigue cracks or structural damage caused by stress concentration during use, thereby extending the service life of the heat exchanger. Especially when applied to the high-temperature working conditions in the SOFC combined heat and power system, the service life of the serrated inserts is usually not as long as that of the sine-shaped flow guide inserts 18 structure.

[0031] The inner and outer partition elements in Chinese Patent CN201710133031.8 are the partition elements 15 in this embodiment.

[0032] The first corrugated plate 7 and the second corrugated plate 8 are made of Inconel 617 alloy. Inconel 617 alloy has good high-temperature performance and corrosion resistance, and can be applied to the high-temperature working conditions of the SOFC combined heat and power system.

[0033] A number of first corrugated grooves 11 that are parallel, equally spaced, and inclined from the upper left to the lower right are evenly distributed on the first corrugated plate 7. The length of the first corrugated grooves 11 gradually decreases from the middle of the first corrugated plate 7 to both sides. A first corrugated protrusion 12 is provided between two adjacent first corrugated grooves 11 in the middle region. The first corrugated protrusion 12 is parallel to the first corrugated grooves 11. The length of the first corrugated protrusion 12 gradually decreases from the middle of the first corrugated plate 7 to both sides. The maximum length of the first corrugated protrusion 12 is less than the maximum length of the first corrugated grooves 11. The cross-sections of both the first corrugated protrusion 12 and the first corrugated grooves 11 are semi-elliptical. The combination of the first corrugated grooves 11 and the first corrugated protrusion 12 can form a flow guiding and heat exchange area 9 on the left and right sides of the interior of the plate bundle 2 for the hot fluid channel 17 and the cold fluid channel 16 and the hot fluid channel 17, and form a main heat exchange area 10 in the middle region of the interior of the plate bundle 2. The flow guiding and heat exchange area 9 forms a velocity gradient in the Y direction, has a pressure dividing and flow dividing effect, can enhance the turbulent flow effect, helps to reduce the flow dead zone, and improves the heat exchange efficiency.

[0034] A number of second corrugated protrusions 13 that are parallel, equally spaced, and inclined are evenly distributed on the second corrugated plate 8. The length of the second corrugated protrusions 13 gradually decreases from the middle of the second corrugated plate 8 to both sides. A second corrugated groove 14 is provided between two adjacent second corrugated protrusions 13 in the main heat exchange area 10. The second corrugated protrusion 13 is parallel to the second corrugated groove 14. The length of the second corrugated groove 14 gradually decreases from the middle of the second corrugated plate 8 to both sides. The maximum length of the second corrugated groove 14 is less than the maximum length of the second corrugated protrusions 13. The cross-sections of both the second corrugated protrusion 13 and the second corrugated groove 14 are semi-elliptical. Similarly to the combination of the first corrugated grooves 11 and the first corrugated protrusion 12, the combination of the second corrugated groove 14 and the second corrugated protrusion 13 can form a flow guiding and heat exchange area 9 on the left and right sides of the interior of the plate bundle 2 for the cold fluid channel 16 and the hot fluid channel 17, and form a main heat exchange area 10 in the middle region of the interior of the plate bundle 2. The flow guiding and heat exchange area 9 forms a velocity gradient in the Y direction, has a pressure dividing and flow dividing effect, can enhance the turbulent flow effect, helps to reduce the flow dead zone, and improves the heat exchange efficiency.

[0035] The inclination angles of the first corrugated grooves 11 and the second corrugated protrusions 13 are opposite, further increasing the fluid turbulent flow effect.

[0036] The working principle of this embodiment is as follows: The cold fluid enters the heat exchange housing 1 from the cold fluid inlet 3. After flowing in through the inlet of the cold fluid passage 16, it enters the main heat exchange area 10 in the middle through the diversion heat exchange area 9 on the inlet side. Similarly, the hot fluid enters the heat exchange housing 1 from the hot fluid inlet 5. After flowing in through the inlet of the hot fluid passage 17, it enters the main heat exchange area 10 in the middle through the diversion heat exchange area 9 on the inlet side. Then, the cold fluid in the cold fluid passage 16 and the hot fluid in the hot fluid passage 17 perform enhanced heat exchange in the main heat exchange area 10. Finally, the cold fluid flows out of the cold fluid passage 16 through the diversion heat exchange area 9 on the outlet side and flows towards the cold fluid outlet 4, and the hot fluid flows out of the hot fluid passage 17 through the diversion heat exchange area 9 on the outlet side and flows towards the hot fluid outlet 6, completing the heat transfer.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered by the scope of the technical solutions claimed by the present invention.

Claims

1. A novel plate heat exchanger for a solid oxide fuel cell combined heat and power generation system, comprising a heat exchange housing serving as a pressure vessel and a plate bundle with a cuboid structure fixedly assembled inside the heat exchange housing, characterized in that: The top of the heat exchange shell is provided with a cold fluid inlet and a hot fluid outlet spaced left and right. The bottom of the heat exchange shell is provided with a hot fluid inlet and a cold fluid outlet spaced left and right. The cold fluid inlet and the hot fluid inlet are vertically corresponding, and the hot fluid outlet and the cold fluid outlet are vertically corresponding. The plate bundle is composed of a number of first corrugated plates and second corrugated plates stacked alternately front and back. The adjacent first corrugated plates and second corrugated plates are welded through spacer elements. Alternately arranged cold fluid channels and hot fluid channels are formed between each first corrugated plate and second corrugated plate. The inlet of the cold fluid channel is located at the upper end of the plate bundle, and the outlet of the cold fluid channel is located at the lower end of the plate bundle. The inlet of the hot fluid channel is located on the left side of the plate bundle, and the outlet of the hot fluid channel is located on the right side of the plate bundle. The plate bundle is arranged obliquely to the left in the heat exchange shell. The right side of the upper end of the plate bundle is hermetically welded to the middle of the inner top surface of the heat exchange shell and is located between the cold fluid inlet and the hot fluid outlet. The left side of the upper end of the plate bundle is hermetically welded to the upper side of the inner left wall of the heat exchange shell. The left side of the lower end of the plate bundle is hermetically welded to the middle of the inner bottom surface of the heat exchange shell and is located between the hot fluid inlet and the cold fluid outlet. The right side of the lower end of the plate bundle is hermetically welded to the lower side of the inner right wall of the heat exchange shell. The cold fluid inlet is vertically corresponding to the upper end of the plate bundle and is communicated with the inlet of the cold fluid channel. The cold fluid outlet is vertically corresponding to the lower end of the plate bundle and is communicated with the outlet of the cold fluid channel. The hot fluid inlet is vertically corresponding to the left side of the plate bundle and is communicated with the inlet of the hot fluid channel. The hot fluid outlet is vertically corresponding to the right side of the plate bundle and is communicated with the outlet of the hot fluid channel. The corrugations of the first corrugated plates and the second corrugated plates are both semi-elliptical corrugations. Sinusoidal flow guide inserts are welded at both the inlet and the outlet of the hot fluid channel.

2. The novel plate heat exchanger of the solid oxide fuel cell cogeneration system according to claim 1, wherein: The first corrugated plates and the second corrugated plates are made of Inconel 617 alloy.

3. The novel plate heat exchanger of the solid oxide fuel cell cogeneration system according to claim 1, characterized in that: A number of parallel and equally spaced first corrugated grooves are uniformly distributed on the first corrugated plates, which are arranged obliquely from the upper left to the lower right. The length of the first corrugated grooves gradually decreases from the middle of the first corrugated plates to both sides. A first corrugated protrusion is arranged between two adjacent first corrugated grooves in the middle area. The first corrugated protrusion is parallel to the first corrugated grooves. The length of the first corrugated protrusion gradually decreases from the middle of the first corrugated plates to both sides. The maximum length of the first corrugated protrusion is less than the maximum length of the first corrugated grooves. The cross-sections of the first corrugated protrusion and the first corrugated grooves are both semi-elliptical.

4. The novel plate heat exchanger of the solid oxide fuel cell cogeneration system according to claim 1, characterized in that: A number of parallel and equally spaced second corrugated protrusions are uniformly distributed on the second corrugated plates, which are arranged obliquely from the lower left to the upper right. The length of the second corrugated protrusions gradually decreases from the middle of the second corrugated plates to both sides. A second corrugated groove is arranged between two adjacent second corrugated protrusions in the middle area. The second corrugated protrusion is parallel to the second corrugated grooves. The length of the second corrugated grooves gradually decreases from the middle of the second corrugated plates to both sides. The maximum length of the second corrugated grooves is less than the maximum length of the second corrugated protrusions. The cross-sections of the second corrugated protrusion and the second corrugated grooves are both semi-elliptical.

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