WO2022002084A1

WO2022002084A1 - Mixing device for gas flows with different flow rates and physical properties in a pipe

Info

Publication number: WO2022002084A1
Application number: PCT/CN2021/103307
Authority: WO
Inventors: Yang Wang
Original assignee: Ceres Intellectual Property Company Limited; Weichai Power Co., Ltd.
Priority date: 2020-06-30
Filing date: 2021-06-29
Publication date: 2022-01-06

Abstract

The invention discloses a mixing device for gas flows with different flow rates and physical properties in a pipe. The device comprises a T-type mixing pipe structure, the T-type mixing pipe structure comprises a first pipe 1 and a second pipe 2, the first pipe is used for circulation of a fluid with a high flow rate, the second pipe is used for circulation of a fluid with a low flow rate, the second pipe penetrates the first pipe and extends to the inside of the first pipe to form a pipe extension portion, and the pipe extension portion is provided with an opening 3 on the incident flow side of the second pipe, and a number of first jet orifices 4 are provided on the wall surfaces of the pipe extension portion corresponding to the two sides of the opening. The mixing device achieves pre-mixing by means of the pipe extension portion, and the p re-mixed fluid passes the first jet orifices to increase the speed of the pre-mixed fluid. Further, the first jet orifices are located on the wall surfaces on the two sides of the opening, so the collision of the ejected fluid with the outer pipe wall will change the streamline, and promote downstream turbulent disturbance and re-mixing, thereby greatly improving the mixing effect of a gas flow with a high flow rate and a gas flow with a low flow rate.

Description

MIXING DEVICE FOR GAS FLOWS WITH DIFFERENT FLOW RATES AND PHYSICAL PROPERTIES IN A PIPE

TECHNICAL FIELD

The present invention relates to the technical field of mixing gas flows in a pipe, particularly to a mixing device for gas flows with different flow rates and physical properties in a pipe.

BACKGROUND ART

In the BOP (balance of plant) system of a fuel cell, in order to ensure the optimal fluid intake temperature of related thermal components, it is sometimes necessary to use a fluid at low temperature in a bypass pipe to mix and cool a fluid at slightly higher temperature. In this case, the flow rate of the low-temperature fluid is lower than that of the high-temperature fluid. At present, the main method of mixing a low-temperature fluid with a high-temperature fluid is direct connection of a tee pipe, but due to the low kinetic energy of the gas with a low flow rate, the gas will flow along the proximal wall surface on the downstream of the tee junction, resulting in a poor mixing effect.

How to solve the problem of a poor mixing effect of gas flows with different flow rates and physical properties in a pipe has become a technical problem t to be solved.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a mixing device for gas flows with different flow rates and physical properties in a pipe, to address the problem of a poor mixing effect of a high-temperature gas flow and a low-temperature gas flow.

The present invention provides a mixing device for gas flows with different flow rates and physical properties in a pipe. The device comprises a T-type mixing pipe structure. The T-type mixing pipe structure comprises a first pipe and a second pipe. The first pipe is used for circulation of a fluid with a high flow rate, the second pipe is used for circulation of a fluid with a low flow rate. The second pipe penetrates the first pipe and extends to the inside of the first pipe to form a pipe extension portion, and the pipe extension portion is provided with an opening on the incident flow side of the second pipe, and a number of first jet orifices are provided on the wall surfaces of the pipe extension portion corresponding to the two sides of the opening.

The extension end of the pipe extension portion can be provided with a cover plate. The cover plate can be an arc plate aligned and evenly spaced from an arc surface of the inner wall of the first pipe. A number of evenly distributed second jet orifices can also be arranged on the arc plate.

Alternatively, the cover plate can be a closed cover plate.

The pipe extension portion can extend to 1/3 to 1/2 of the diameter of the first pipe.

The distribution of the number and/or size of the first jet orifices can increase from bottom to top on the wall surface of the pipe extension portion.

The opening is a rectangular opening. The layout area of the rectangular opening can located in an arc-shaped area more than 30 degrees from the bottom of the intersection of the first pipe and the second pipe.

The first jet orifices can be through holes that are tapered with a diameter gradually reducing from the inside of the second pipe to the outside of the second pipe.

The invention also provides an SOFC system comprising the mixing device.

Compared with known devices, the mixing device according to the invention comprises a T-type mixing pipe structure. The T-type mixing pipe structure comprises a first pipe and a second pipe. The first pipe is used for circulation of a fluid with a high flow rate and the second pipe is used for circulation of a fluid with a low flow rate. The second pipe penetrates the first pipe and extends to the inside of the first pipe to form a pipe extension portion which is provided with an opening on the incident flow side of the second pipe, and a number of first jet orifices are provided on the wall surfaces of the pipe extension portion corresponding to the two sides of the opening. In use, a fluid with a low flow rate in the second pipe enters the pipe extension portion. Meanwhile, as the incident flow side of the second pipe is provided with an opening, the fluid with a high flow rate in the first pipe will also partially enter the pipe extension portion. The fluid with a high flow rate in the first pipe will generate a turbulent effect on the fluid with a low flow rate in the pipe extension portion, and the two fluids will be pre-mixed inside the pipe extension portion. After that, the pre-mixed fluid will pass through the first jet orifices arranged on the wall surfaces of the pipe extension portion corresponding to the two sides of the opening to produce a jet to the fluid in the first pipe, so that the pre-mixed fluid and the fluid in the first pipe are mixed again on the downstream side. In this process, the first jet orifices will increase the speed of the pre-mixed fluid in the pipe extension portion. Furthermore, as the first jet orifices are located on the wall surfaces on both sides of the opening, the collision between the fluid ejected from the first jet orifices and the outer pipe wall will change the streamline and promote downstream turbulent disturbance and re-mixing, which greatly improves the mixing effect of a gas flow with a high flow rate and a gas flow with a low flow rate. In addition, the mixing device has a simple structure. Under the engineering conditions with a limited installation space, it does not increase an external space, and only a pipe with a low flow rate needs to penetrate and extend into a pipe with a high flow rate, thereby making full use of the kinetic energy of the gas with a high flow rate to improve the mixing effect.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front cross-sectional structural schematic view of a T-type mixing pipe structure.

Fig. 2 is a structural schematic view of Fig. 1 in direction A.

Fig. 3 is a structural schematic view of Fig. 1 in direction B.

Fig. 4 is an axial perspective structural schematic view of a T-type mixing pipe structure.

Fig. 5 is a CFD-simulated temperature distribution diagram of the T-type cross section of a T-type mixing pipe structure provided by an embodiment of the present invention;.

Fig. 6 is a CFD-simulated temperature distribution diagram of the T-type cross section of a conventional tee pipe structure.

Fig. 7 is a CFD-simulated temperature distribution diagram of a downstream pipe cross section of a T-type mixing pipe structure provided by an embodiment of the present invention after mixing.

Fig. 8 is a CFD-simulated temperature distribution diagram of a downstream pipe cross section of a conventional tee pipe structure after mixing.

In Fig. 1 to Fig. 8, the following reference numerals are used: first pipe 1, second pipe 2, opening 3, first jet orifice 4, cover plate 5.

DETAILED DESCRIPTION

The object of the present invention is to provide a mixing device for gas flows with different flow rates and physical properties in a pipe, to solve the problem of a poor mixing effect of a high-temperature gas flow and a low-temperature gas flow.

Embodiments of the present invention will be further illustrated in conjunction with the accompanying drawings.

As shown in Fig. 1 to Fig. 8, an embodiment of the present invention provides a mixing device for gas flows with different flow rates and physical properties in a pipe. The device comprises a T-type mixing pipe structure. The T-type mixing pipe structure comprises a first pipe 1 and a second pipe 2. The first pipe 1 is used for circulation of a fluid with a high flow rate and the second pipe 2 is used for circulation of a fluid with a low flow rate. The second pipe 2 penetrates the first pipe 1 and extends to the inside of the first pipe 1 to form a pipe extension portion, and the pipe extension portion is provided with an opening 3 on the incident flow side of the second pipe 2, and a number of first jet orifices 4 are provided on the wall surfaces of the pipe extension portion corresponding to the two sides of the opening 3.

In use, a fluid with a low flow rate in the second pipe enters the pipe extension portion. Meanwhile, because the incident flow side of the second pipe is provided with an opening, the fluid with a high flow rate in the first pipe will partially enter the pipe extension portion. The fluid with a high flow rate in the first pipe will the generate a turbulent effect on the fluid with a low flow rate in the pipe extension portion, and the two fluids will be pre-mixed inside the pipe extension portion. The pre-mixed fluid will then pass through the first jet orifices arranged on the wall surfaces of the pipe extension portion corresponding to the two sides of the opening to produce a jet into the fluid in the first pipe, so that the pre-mixed fluid and the fluid in the first pipe are mixed on the downstream side of the pipe extension portion. In this process, the first jet orifices will increase the speed of the pre-mixed fluid from the pipe extension portion. Furthermore, as the first jet orifices are located on the wall surfaces on both sides of the opening, the collision between the fluid ejected from the first jet orifices and the outer pipe wall will change the streamline and promote downstream turbulent disturbance and re-mixing, which greatly improves the mixing effect between the gas flow with a high flow rate and the gas flow with a low flow rate. In addition, the mixing device has a simple structure. Under the engineering conditions with limited installation space, for example when used as part of an SOFC system and in fluid communication with an inlet of a cell stack, this does not increase the external space used, and only the pipe supplying the low flow rate gas needs to penetrate and extend into the pipe with the high flow rate gas, thereby making full use of the kinetic energy of the gas with a high flow rate to improve the mixing effect.

In some embodiments, the extension end of the pipe extension portion may also be provided with a cover plate 5. The provision of the cover plate 5 can cause the fluid entering the pipe extension portion from the first pipe to be fully mixed with the fluid in the pipe extension portion and helps enhance the jet strength of the first jet orifices. The provision of a cover plate at the extension end of the pipe extension portion is only a one example of an embodiment of the present invention, and the cover plate may be not provided in other embodiments.

In a further embodiment, the cover plate 5 is an arc plate, aligned and evenly spaced from the arc surface of the inner wall of the first pipe 1. The provision of the arc plate helps improve the distribution uniformity of the mixed fluid in the cross section of the first pipe after passing through the first jet orifices via the pipe extension portion and jetting. The arc plate is only a one example of an embodiment of the present invention, and a cover plate structure with another shape can also be used.

In a still further embodiment, a number of evenly distributed second jet orifices may also be arranged on the arc plate. The second jet orifices can enhance the jet ability of the fluid in the pipe extension portion to the wall of the first pipe, increase the collision area and improve the mixing effect. This is only one example of the embodiment of the present invention. In other embodiments, the cover plate 5 may also be designed in the form of a closed cover plate, according to the actual requirements.

In some embodiments, the pipe extension portion is generally designed to extend to 1/3 to 1/2 of the diameter of the first pipe 1. The design of the extension portion can effectively reduce the fluid pressure loss in the first pipe and ensure that the fluid mixing effect is improved under the condition of not significantly increasing the pressure during mixing.

In some embodiments, the first jet orifices 4 can be distributed with the number of orifices gradually increasing from bottom to top on the wall surface of the pipe extension portion. Such a structural form can prevent the lower fluid from flowing away without being fully mixed. This is only one example of the distribution gradually increasing from bottom to top. Other embodiments can comprise uniform distribution, a gradual increase of orifice diameter from bottom to top, etc., as well as combinations of these features.

One structural form of the opening 3 can be a rectangular opening, because it is more convenient to process a rectangular opening and is easier to determine the distribution positions of the first jet orifices. A rectangular opening is only one example, and an opening in another shape can used according to the actual requirements.

In a further embodiment, the layout area of the rectangular opening is located in an arc-shaped area more than 30 degrees from the bottom of the intersection of the first pipe 1 and the second pipe 2. Such layout can prevent the fluids pre-mixed in the pipe extension portion from flowing away directly at the bottom.

The first jet orifices 4 can be tapered through-holes with a diameter gradually reducing from the inside of the second pipe 2 to the outside of the second pipe 2. The design of the structural form of the tapered through-holes can enhance the jet effect of the jet orifices. The use of tapered through-holes is only one example of the present invention. Other forms of through-holes can also be used.

In order to illustrate the technical effects achieved by the present invention, the mixing effect of a conventional tee pipe structure and the mixing effect of an embodiment of the present invention are described below.

A conventional tee pipe structure and a T-type mixing pipe structure provided by the present invention were assembled to a real pipe structure respectively, and CFD simulated analysis was conducted.

The results of the CFD simulation are shown in Fig. 5 to Fig. 8. Compared with the conventional tee pipe structure, the T-type mixing pipe structure provided by the present invention has a better mixing effect. The comparison between the CFD-simulated temperature distribution on the T-type cross section of the T-type mixing pipe structure provided by the embodiment of the present invention as shown in Fig. 5 and the CFD-simulated temperature distribution on the T-type cross section of the conventional tee pipe as shown in Fig. 6 indicates that the mixing effect provided by the present invention is better. Further, the comparison between the CFD-simulated temperature distribution on the pipe downstream cross section of the embodiment of the present invention as shown in Fig. 7 and the CFD-simulated temperature distribution on the pipe downstream cross section of the conventional tee pipe as shown in Fig. 8 indicates that the fluids are mixed more completely and effectively in the embodiment of the present invention. The comparison reveals that the temperature and density gradient differences are even smaller on the cross section at the pipe downstream outlet of the T-type mixing pipe structure provided by the embodiment of the present invention and the mixing is more uniform.

Further, the conventional tee pipe structure and the T-type mixing pipe structure provided by an embodiment of the present invention are compared in terms of the pressure drop from the fluid inlet to the outlet of the T-type mixing device. The comparison data indicate that compared with the conventional tee pipe structure, the T-type mixing pipe structure provided by an embodiment of the present invention does not have a large change in pressure loss, and can ensure improvement of the mixing effect while keeping the increase of pipe pressure drop to a relatively small margin.

The embodiments of the mixing device provided by the present invention are described in a progressive manner, each embodiment focuses on the differences from other embodiments and the same or similar parts among the embodiments can be mutually referred to.

Terms such as “comprise, ” “include” and any other equivalent expressions cover non-exclusive inclusion so that an object or device comprising a series of factors not only includes these factors but also includes other factors not expressly listed, or also includes factors inherent with the object or device. Under the condition of no further limitations, the factors delimited by expression “comprise a…” do not exclude other same factors in the object or device including said factors.

Various changes and modifications can be made without departing from the principle of the present invention and these changes and modifications are within the scope of protection of the present invention.

Claims

A mixing device for gas flows with different flow rates and physical properties in a pipe comprising a T-type mixing pipe structure comprising a first pipe (1) and a second pipe (2) , wherein:

the first pipe (1) is used for circulation of a fluid with a high flow rate;

the second pipe (2) is used for circulation of a fluid with a low flow rate;

the second pipe (2) penetrates the first pipe (1) and extends to the inside the first pipe (1) to form a pipe extension portion,

wherein the pipe extension portion is provided with an opening (3) on the incident flow side of the second pipe (2) ; and

a number of first jet orifices (4) are provided on wall surfaces of the pipe extension portion corresponding to two sides of the opening (3) .
The mixing device according to claim 1, wherein an extension end of the pipe extension portion is provided with a cover plate (5) .
The mixing device according to claim 2, wherein the inner wall of the first pipe (1) has an arc surface; and wherein the cover plate (5) is an arc plate aligned and spaced from the arc surface of the inner wall of the first pipe (1) .
The mixing device according to claim 3, wherein a number of evenly distributed second jet orifices are also arranged on the arc plate.
The mixing device according to claim 2, wherein the cover plate (5) is a closed cover plate.
The mixing device according to any preceding claim, wherein the pipe extension portion extends to 1/3 to 1/2 of the diameter of the first pipe (1) .
The mixing device according to any preceding claim, wherein the first jet orifices (4) are distributed such that the number and/or size of the jet orifices increases from bottom to top on the wall surface of the pipe extension portion.
The mixing device according to any preceding claim, wherein the opening (3) is a rectangular opening.
The mixing device according to claim 8, wherein the layout area of the rectangular opening is located in an arc-shaped area more than 30 degrees from the bottom of the intersection of the first pipe (1) and the second pipe (2) .
The mixing device according to any preceding claim wherein the first jet orifices (4) are tapered through holes with a diameter gradually reducing from the inside of the second pipe (2) to the outside of the second pipe (2) .
An SOFC system comprising a cell stack having a stack inlet and a mixing device according to any preceding claim, wherein the mixing device is in fluid communication with the stack inlet.