BALANCED TRIM REGULATOR

Abstract

A balanced trim pressure regulator includes a valve body having a fluid inlet and a fluid outlet connected by a fluid passageway. An orifice is disposed between the fluid inlet and the fluid outlet. A valve seat is disposed within the fluid passageway. A movable valve plug is disposed within the fluid passageway, the movable valve plug interacting with the valve seat to selectively open or close the fluid passageway. A cage is disposed in the fluid passageway, the cage surrounding the valve plug, and the cage including at least one a balancing passage that fluidly connects the fluid passageway with a balancing chamber.

Claims

1. A balanced trim pressure regulator, comprising: a valve body having a fluid inlet and a fluid outlet connected by a fluid passageway, and an orifice being disposed between the fluid inlet and the fluid outlet; a valve seat disposed within the fluid passageway; a movable valve plug, the valve plug being disposed within the fluid passageway, the valve plug interacting with the valve seat to selectively open or close the fluid passageway; and a cage disposed in the fluid passageway, the cage surrounding the valve plug, the cage including at least one balancing passage that fluidly connects the fluid passageway with a balancing chamber.

2. The balanced trim pressure regulator of claim 1, wherein the cage includes a first opening and a second opening, the first opening and the second being connected by the balancing passage.

3. The balanced trim pressure regulator of claim 2, wherein the first opening includes a chamfered surface.

4. The balanced trim pressure regulator of claim 2, wherein the cage includes a plurality of balance passages distributed circumferentially about the cage.

5. The balanced trim pressure regulator of claim 1, wherein the cage is formed by additive manufacturing techniques.

6. The balanced trim pressure regulator of claim 1, wherein the valve plug has a diameter that is too small to accommodate a balance passage.

7. The balanced trim regulator of claim 1, wherein the balance passage is located outside of a diameter of a plug seal.

8. A balanced trim assembly, comprising: a valve seat; a valve plug, the valve plug being movable relative to the valve seat, the valve plug interacting with the valve seat to selectively open or close the valve seat; and a cage disposed in the fluid passageway, the cage surrounding the valve plug, the cage including at least one balancing passage that fluidly connects the fluid passageway with a balancing chamber.

9. The balanced trim assembly of claim 8, wherein the cage includes a first opening and a second opening, the first opening and the second being connected by the balancing passage.

10. The balanced trim assembly of claim 9, wherein the first opening includes a chamfered surface.

11. The balanced trim assembly of claim 9, wherein the cage includes a plurality of balance passages distributed circumferentially about the cage.

12. The balanced trim assembly of claim 8, wherein the cage is formed by additive manufacturing techniques.

13. The balanced trim assembly of claim 8, wherein the valve plug has a diameter that is too small to accommodate a balance passage.

14. The balanced trim assembly of claim 8, wherein the balance passage is located outside of a diameter of a plug seal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a cross-sectional view of a prior art balanced regulator;

[0026] FIG. 2 is a cross-sectional view of another prior art balanced regulator;

[0027] FIG. 3 is a cross-sectional view of a balanced trim regulator constructed in accordance with the teachings of the disclosure; and

[0028] FIG. 4 is a cross-sectional view of a cage of the balanced trim regulator of FIG. 3, taken along line A-A in FIG. 3.

[0029] While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention.

DETAILED DESCRIPTION

[0030] Referring now to the drawings and with specific reference to FIGS. 3 and 4, a balanced port pressure regulator is generally referred to by reference numeral 210. The balanced port pressure regulator 210 includes a valve body 220 having a fluid inlet 222 and a fluid outlet 224 connected by a fluid passageway 226. The fluid passageway 226 includes a throat or orifice 228 (i.e., the narrowest part of the passageway 226) leading from the fluid inlet 222 to the fluid outlet 224, and a valve seat 230 disposed in the orifice 228. In the embodiment of FIG. 3, the valve seat 230 forms the orifice 228, which is the narrowest part of the fluid passageway 226 in the valve body 220.

[0031] A bonnet 232 houses a load spring (not shown) that is connected to a valve stem (not shown). The valve stem is operatively attached to a valve plug 238. The valve plug 238 interacts with the valve seat 230 to control fluid flow through the valve body 220 from the inlet 222 to the outlet 224. In the embodiment of FIG. 3, the valve plug 238 is located downstream of the valve seat 230. In other embodiments, the valve plug 238 may be located upstream of the valve seat 230.

[0032] A cage 254 surrounds the valve plug 238. In the embodiment of FIG. 3, the cage 254 is integrally formed with the valve seat 230. In other embodiments, the cage 254 and the valve seat 230 may be formed as separate components. The cage 254 characterizes fluid flow through the valve body 220. More specifically, the cage 254 may include a plurality of flow passages or openings 256. A plurality of balancing channels 255 are formed in a side wall of the cage 254, through which process fluid is allowed to flow to a balancing chamber 248. The cage 254 has a first opening 257 that terminates in the orifice 228 and a second opening 259 that terminates in the balancing chamber 248. In the embodiment illustrated in FIG. 3, the first opening 257 may alternatively be an open end or a plurality of balancing channels 255 that are circumferentially disposed about the cage 254, as illustrated in FIG. 4.

[0033] Fluid forces on the valve plug 238 are balanced by fluid moving through the balancing channels 255 from higher pressure regions to lower pressure regions.

[0034] The balancing channels 255 fluidly connect the passageway 226 in the orifice 228 to the balancing chamber 248.

[0035] In some embodiments, the valve seat 230, the valve stem, the valve plug 238, and the cage 154 may be formed as a balanced plug assembly.

[0036] In other embodiments, the first open end 257 may include a chamfered opening surface, or a surface that otherwise directs the opening away from the direction of fluid flow from the inlet 222, as illustrated in FIG. 3. In yet other embodiments, a plurality of openings 257 may be distributed circumferentially around the cage 254, as illustrated in FIG. 4. The balancing channels 255 may be generally oval in cross-sectional shape. In other embodiments, the balancing channels 255 may take on virtually any other cross-sectional shape, such as circle, square, triangle, slot, irregular, or any other shape. Particular shapes may be selected to aid in directing local fluid flow into the balancing channels 255 at different locations within the cage 254. In yet other embodiments, the cage 254 may include a combination of openings, chamfered openings, and circumferentially disposed openings.

[0037] When the valve plug 238 is in a closed position, contacting the valve seat 230, the first end 257 is generally located between the upstream most portion of the orifice 228 and the valve plug 238. By thus locating the first end 257, the first end 257 avoids the initial area of highest flow velocity between the valve plug 238 and the valve seat 230 when the valve plug 238 initially begins to open.

[0038] This highest flow velocity area is sometimes referred to as the curtain area. Because the average flow velocity in the curtain area is the highest, static pressure in this region is lowest in the passageway 226. The curtain area remains the area of highest flow velocity until the valve plug 238 opens sufficiently to make the curtain area larger than the orifice area. At this point, the orifice itself becomes the primary flow restriction and the flow velocity in the orifice becomes the highest flow velocity in the passageway 226. Because the first end 257 is located within the orifice 228, but not in the curtain area, the pressure transmitted through the cage 254 to the balance chamber 248 is also reduced, resulting in a substantial boost to the valve as the valve plug 238 approaches a fully open position, which is where prior art valves experience droop. This boost near the fully open position counteracts the droop, resulting in more constant outlet pressures as the valve plug 238 approaches the fully open position.

[0039] Any of the embodiments of balanced trim regulators or balanced plug assemblies disclosed herein may be used to advantageously combat regulator pressure droop at a point in the opening cycle where boost is needed most, near the fully open position of the valve plug because the orifice does not become the most restrictive point in the flow passageway until the valve plug nears a fully open position.

[0040] Additionally, the balanced trim regulators disclosed herein advantageously allow balanced regulators to be formed in regulators with small port sizes where the valve plug, or plug post, is too small to accommodate a balance passageway. The cages described herein may be formed by additive manufacturing techniques. The balance passageways may be integrally formed in the cage. Additionally, the balance passages in cage described herein advantageously pass outside of the diameter of the plug seal.

[0041] In other embodiments, the balance passageways could be formed in trim elements other than the cage or valve plug. In yet other embodiments, the cage could be formed in multiple pieces, the balance passageways extending though the multiple pieces. In yet other embodiments, the balance passages may include a lattice structure.

[0042] Although certain balanced trim regulators and balanced trim assemblies have been described herein in accordance with the teachings of the present disclosure, the scope of coverage of this patent is not limited thereto. On the contrary, while the invention has been shown and described in connection with various preferred embodiments, it is apparent that certain changes and modifications, in addition to those mentioned above, may be made. This patent covers all embodiments of the teachings of the disclosure that fairly fall within the scope of permissible equivalents. Accordingly, it is the intention to protect all variations and modifications that may occur to one of ordinary skill in the art.