WO1996035495A1

WO1996035495A1 - Vortex air separator for hydronic heating system

Info

Publication number: WO1996035495A1
Application number: PCT/US1995/006049
Authority: WO
Inventors: Bruce W. Knoop; Richard J. Genga, Jr.; Ian Gilley; Troy K. Centazzo
Original assignee: Taco, Inc.
Priority date: 1995-05-12
Filing date: 1995-05-12
Publication date: 1996-11-14

Abstract

A vortex air separator (14) is provided for removing air bubbles entrained in water circulating through a hydronic heating system. The air separator (14) includes a separation element (26) having a surface which is adapted to reduce the velocity and change the direction of water passing over the surface with a minimal pressure drop. In a preferred embodiment, the element (26) includes a spirally wound screen (26). Preferably, the spiral forms two or more complete turns.

Description

- 1 -

VORTEX AIR SEPARATOR FOR HYDRONIC HEATING SYSTEM Background of the Invention The invention relates to vortex air separators for hydronic heating systems.

Any air bubbles entrained in water circulating through a hydronic heating circuit are preferably removed, as excessive air can collect in registers, and thereby block heat transfer or render ineffective the circulator pumps intended to circulate heated water.

It is known to remove air by passing circulating water through an air separator. Various designs are known for air separators. Some operate on a vortex principle, in which heavier water tends to move under inertial forces toward the periphery of the vortex chamber, leaving lighter air bubbles in the center, where they escape through a special valve that opens in the presence of air.

It is also known to place a conical screen in the vortex chamber to foster the aggregation of small air bubbles into large bubbles, which are more likely to migrate toward the center of the vortex, e.g., as shown in Black ore et al. U.S. Patent No. 3,151,961.

Summary of the Invention The invention features a vortex air separator for removing air bubbles entrained in a fluid, e.g., water, circulating through a hydronic heating system. It has been found that separation of the air bubbles from the fluid can be improved, and pressure drop minimized, by including in the air separator a separation element which has a surface which is shaped to reduce the velocity and change the direction of fluid passing over the surface, and which includes a plurality of apertures to allow fluid to pass through the element. Typically, the pressure drop of fluid passing through preferred separators of the invention is less than about 0.4 psi at 10 gpm.

Thus, in one aspect, the invention features a vortex air separator for removing air bubbles entrained in a fluid circulating through a hydronic heating system that includes an inlet for receiving the fluid, a chamber in fluid communication with the inlet, the inlet being positioned relative to the chamber so that fluid enters the chamber tangentially, creating a vortex in the fluid, a separation element, disposed in the chamber, which has a surface that is shaped to reduce the velocity and change the direction of fluid passing over the surface, and which includes a plurality of apertures to allow fluid to pass through the element, thus minimizing pressure drop, and an outlet in fluid communication with the chamber and downstream of the vortex.

In a preferred embodiment, the element includes a screen that is spirally wound about a central longitudinal axis, and which defines a passage for fluid flow from the outside of the spiral to the central longitudinal axis. The passage may have a constant width (the turns of the spiral being egually spaced from the central longitudinal axis) or may increase or decrease in width as it approaches the axis. Preferably the spiral forms two or more complete turns. The spiral may have walls which are substantially parallel to the central longitudinal axis, or may be frustroconical, i.e., the walls may taper towards the axis at one end of the length of the spiral. The spirally wound screen can also include areas of different mesh size. Instead of a mesh screen, the spriral can be a spiral wall having a plurality of apertures, sufficient in number and size to produce the desired minimal pressure drop. The spirally wound screen can include bristles protruding from its surface, preferably extending towards the central longitudinal axis. The element can include, instead of a single spirally wound screen, a plurality of nested spirally wound screens.

In another embodiment, the element could include a central elongated member, positioned centrally in the chamber and substantially perpendicular to the direction of tangential flow into the chamber, and having a plurality of bristles extending radially therefrom. Preferably, bristles cover a major portion of the surface of the elongated member.

In another aspect, the invention features a method of removing air bubbles entrained in water circulating through a hydronic heating system using an air separator of the invention. Brief Description of the Drawings

Fig. 1 shows a vortex air separator according to one aspect of the invention. Fig. 1A is a somewhat schematic partial cross-sectional side view of the vortex air separator of Fig. 1 in use in a hydronic system. Fig. IB is a somewhat schematic cross-sectional top view of the vortex air separator, illustrating schematically the direction of tangential flow into the separator and the fluid vortex in the separator. Fig. 1C is an exploded view of the vortex air separator of Fig. 1. Fig. 2 is a top view of the spiral screen component of the vortex air separator of Fig. 1.

Fig. 3 is a side cross-sectional view of an alternative screen configuration.

Fig. 4 is a top view of yet another alternative screen configuration.

Figs. 5 and 5A are a top view and a perspective view, respectively, of a spiral screen having bristles extending from its surface. Fig. 6 and 6A are a top view and a perspective view, respectively, of a separation element according to another embodiment of the invention.

Description of the Preferred Embodiments A vortex separator according to one aspect of the invention is shown in Fig. 1, and shown, in partial cross section, in use in a hydronic circulating system in Fig. 1A. As shown in Fig. 1A, vortex separator 10 includes a housing 11 having a tangential inlet 12, through which water or other fluid from the hydronic heating system flows into the separator, a chamber 14 for containing the fluid, the tangential inlet and chamber being shaped and relatively disposed so that a vortex is created in the fluid as it enters the chamber, and an outlet 16 through which the fluid flows out of the chamber and back into the hydronic system.

Disposed within chamber 14 is a spirally wound screen member 26. In the embodiment shown in Figs. IB and 2, the spiral screen includes two full turns (see Fig. 2) , and the walls of the spiral are substantially parallel to the central longitudinal axis of the spiral.

In one preferred embodiment, suitable for use in a chamber having an inlet diameter of approximately 1 inch, a spiral having two turns has an unrolled length of from about 10 to 12 inches, most preferably about 11 inches, and a diameter of from about 3 to 4 inches, most preferably about 3.5 inches. These dimensions are not critical, and will vary depending upon the inlet diameter, volume of the chamber, and the process parameters in a given application, e.g., flow rate and the fluid used. Typically, the overall size of the spiral will increase proportionally with increasing inlet diameter. Generally, the tighter the spiral is wound, the better the separation, but also the higher the pressure drop. Thus, the desired tightness of the spiral in a particular application can be determined empirically based on the pressure drop which is acceptable in that application. It is also preferred, as indicated by arrows A and B in Fig. 2, that the radius of curvature of the spiral increase from the inside (Arrow A, approximately 0.63) to the outside (Arrow B, approximately 3.00) of the spiral. The actual radii of curvature are not critical, and will vary as described above. However, in most cases the increase in radius of curvature from the inside to the outside is preferred, as it allows the spacing between the spiral walls to remain constant, which has been found to optimize pressure drop. In a separator having the above dimensions, the screen preferably has a mesh size of about 10 mesh, and is constructed of stainless steel #304 wire having a diameter of 0.025". The smaller the mesh size, the better the air removal will be, but also the higher the pressure drop may be. Again, the preferred mesh size and wire gauge for a given application can be determined empirically based on the pressure drop which is acceptable in that application, and as a general rule mesh size and wire gauge will tend to increase proportional to the inlet diameter.

As shown in detail in Fig. IB, the separator further includes a self-venting air vent 17, e.g., a vent commercially available from Taco, Inc. under the tradename "HY-VENT", a cap 18, an o-ring 19 sealing the interface between the cap and housing, a pierced washer 20, and an aperture 22, sealed by a plug 24, at the bottom of chamber 14. With the exception of the pierced washer, these components are conventionally used in vortex separators and their function is well known. Pierced washer 20 serves as a support structure for the spiral screen, and includes a solid central area 25 and a plurality of radially arranged apertures 27. The solid central portion keeps air bubbles, which are drawn to the center of the vortex, from exiting with fluid passing to the outlet. (The fluid instead drains through the apertures 27 which are placed towards the outside of the vortex, where very few bubbles will be able to settle.

Other embodiments are within the claims. For instance, the mesh size of the screen can be different in selected areas of the screen, if desired. Moreover, the walls of the spiral could be disposed at an angle relative to the longitudinal axis of the spiral, so that the spiral screen is substantially frustro-conical in shape, as shown in Fig. 3. Further, the element could comprises a plurality of nested spiral screens, as shown in Fig. 4. The spiral can also have more than two turns. The spiral can also include bristles 29 extending from its surface, as shown in Figs. 5 and 5A.

Additionally, the separator element can be something other than a spiral screen, provided that it reduces the velocity and changes the direction of the fluid while maintaining a pressure drop of less than about 0.4 psi at 10 gpm. For example, as shown in Figs. 6 and 6A, the separator element may comprise an elongated rod 31 having bristles 33 extending radially from its surface.

Claims

1. A vortex air separator for removing air bubbles entrained in a fluid circulating through a hydronic heating system comprising: an inlet for receiving the fluid, a chamber in fluid communication with the inlet, the inlet being positioned tangentially relative to the chamber to create a vortex in the fluid, a separation element, disposed in the chamber, which has a surface that is shaped to reduce the velocity and change the direction of fluid passing over the surface, and an outlet in fluid communication with the chamber and downstream of the vortex, said separation element being shaped and adapted to maintain the pressure drop between said inlet and said outlet at less than about 0.4 psi at 10 gp .

2. The vortex air separator of claim 1 wherein the element includes a spirally wound screen.

3. The vortex air separator of claim 2 wherein the spirally wound screen forms two or more complete turns.

4. The vortex air separator of claim 2 wherein the screen is formed of a metallic wire mesh.

5. The vortex air separator of claim 4 wherein the entire screen has substantially the same mesh size.

6. The vortex air separator of claim 2 wherein the screen has regions having different mesh sizes.

7. The vortex air separator of claim 6 wherein the mesh size of the screen decreases from the outside to the inside of the spiral.

8. The vortex air separator of claim 2 wherein the spirally wound screen is conical or semi-conical in shape.

9. The vortex air separator of claim 1 wherein the element includes a plurality of nested spirally wound screens.

10. The vortex air separator of claim 9 wherein the element includes two nested spirally wound screens.

11. The vortex air separator of claim 9 wherein at least two of the spirally wound screens have different mesh sizes.

12. The vortex air separator of claim 2 wherein said spirally wound screen includes a plurality of bristles extending from a portion of its surface.

13. The vortex air separator of claim 1 wherein said separator element includes an elongated element having a plurality of bristles extending radially from a portion of its outer surface.

14. A vortex air separator for removing air bubbles entrained in a fluid circulating through a hydronic heating system comprising: an inlet for receiving the fluid, a chamber in fluid communication with the inlet, said inlet positioned tangentially with respect to the chamber to created a vortex in the fluid, a spirally wound screen disposed in the chamber, and an outlet in fluid communication with the chamber and downstream of the vortex.

15. The vortex air separator of claim 14 wherein the spirally wound screen forms two or more complete turns.

16. The vortex air separator of claim 14 wherein the spirally wound screen comprises a metallic wire mesh.

17. The vortex air separator of claim 16 wherein the entire screen has substantially the same mesh size.

18. The vortex air separator of claim 14 wherein the screen has regions having different mesh sizes.

19. The vortex air separator of claim 18 wherein the mesh size of the screen decreases from the outside to the inside of the spiral.

20. The vortex air separator of claim 14 wherein the spirally wound screen is conical or semi-conical in shape.

21. The vortex air separator of claim 14 further including a second spirally wound screen, nested within the turns of said spirally wound screen.

22. The vortex air separator of claim 21 wherein the second spirally wound screen has a mesh size that is different from that of said spirally wound screen.