Trunnion ball valve with controlled ball-seat engagement and disengagement

Abstract

A trunnion ball valve provides a reliable seal when closed, while minimizing or eliminating frictional resistance during rotation of the ball. A pressurization chamber behind the upstream valve seat can be interconnected by one or more pressurization valves with either the upstream or the downstream process fluid. The interconnection can be via a single 3-way valve. When the valve is closed and the ball is fixed in orientation, the pressurization chamber is automatically connected to the upstream process fluid, thereby pressing the seat against the ball and ensuring a reliable seal. While the ball is being rotated, the pressurization chamber is automatically connected to the downstream process fluid, thereby substantially eliminating valve seat friction. Connection to the downstream process fluid can include connection to a small space in front of the upstream seat. An electronic controller can control both valve stem rotation and the pressurization valves.

Claims

1. A trunnion ball valve, comprising: a valve housing having a top, a bottom, a valve inlet, and a valve outlet; a valve stem extending through the top of the valve housing; a ball within a body cavity of the valve housing that is fixed on an upper end thereof to the valve stem and is translationally fixed at a lower end thereof to the bottom of the housing via a lower trunnion, such that the ball is able to rotate with the valve stem but is otherwise fixed in location, the ball being penetrated by at least one central passage; an upstream valve seat that is laterally displaceable within the valve housing inlet so as to be pressed against the ball or displaced away from the ball; a pressurization chamber that abuts an upstream facing surface of the upstream valve seat; a small space that abuts a downstream-facing surface of the upstream valve seat, the small space being in fluid communication with process fluid downstream of the valve outlet; at least one pressurization valve, wherein the at least one pressurization valve can be transitioned between a pressurizing state and a depressurizing state, the at least one pressurization valve being configured to place the pressurization chamber in fluid communication with process fluid upstream of the valve inlet when the at least one pressurization valve is/are in the pressurizing state, and to place the pressurization chamber in fluid communication with process fluid downstream of the valve inlet, thereby substantially equalizing pressures at the upstream facing and downstream facing surfaces of the upstream valve seat, when the at least one pressurization valve is/are in the depressurizing state, the pressurization chamber being otherwise isolated from the process fluid both upstream and downstream of the trunnion ball valve.

2. The trunnion ball valve of claim 1, wherein the at least one pressurization valve is a single valve.

3. The trunnion ball valve of claim 2, wherein the single valve is a 3-way valve.

4. The trunnion ball valve of claim 1, wherein when the at least one pressurization valve is/are in the depressurizing state, the pressurization chamber is in fluid communication with the small space that abuts the downstream-facing surface of the upstream valve seat.

5. The trunnion ball valve of claim 4, wherein the upstream facing surface of the upstream valve seat is smaller in area than the downstream-facing surface of the upstream valve seat, such that when the at least one pressurization valve is/are in the depressurizing state, there is a net pressing of the upstream valve seat away from the ball.

6. The trunnion ball valve of claim 1, wherein the at least one pressurization valve is/are configured to be automatically transitioned to the depressurized state while the ball is being rotated, and to the pressurizing state when the trunnion ball valve is closed and the ball is fixed in orientation.

7. The trunnion ball valve of claim 6, wherein the at least one pressurization valve is/are configured to be automatically transitioned to the depressurizing state before the ball is rotated, and to the pressurizing state after the trunnion ball valve is closed and the ball is fixed in orientation.

8. The trunnion ball valve of claim 6, further comprising an electronic valve controller that is configured to place the at least one pressurization valve in the depressurizing state when the ball and the valve stem are being rotated, and to place the at least one pressurizing valve in the pressurizing state when the trunnion ball valve is closed and the ball is fixed in orientation.

9. The trunnion ball valve of claim 8, wherein the electronic controller is configured to control rotation of the valve stem as well as reconfiguration of the at least one pressurization valve.

10. The trunnion ball valve of claim 1 wherein the ball is fixed in lateral position at an upper end thereof to the top of the housing via an upper trunnion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a sectional view of a trunnion ball valve of the prior art;

(2) FIG. 1B is a close-up sectional view of the trunnion ball valve of FIG. 1A;

(3) FIG. 2A is a sectional view of a trunnion ball valve in an embodiment of the present invention, shown as configured when the valve is closed and the orientation of the ball is fixed;

(4) FIG. 2B is a sectional view of the trunnion ball valve of FIG. 2A, shown as configured when the ball is about to be rotated; and

(5) FIG. 3 is a sectional view of a trunnion ball valve similar to the valve of FIGS. 2A and 2B, but in which the downstream fluid bypass interconnects the small space with a fluid flow region that is downstream of the valve.

DETAILED DESCRIPTION

(6) The present invention is a trunnion ball valve that provides a high-quality seal when the ball is fixed in orientation and the valve is closed, while minimizing valve seat friction while the ball is being rotated. With reference to FIGS. 2A and 2B, this is accomplished by actively controlling the pressure of the upstream seat 201 against the ball 100, such that the pressure is high when the ball 100 is fixed in orientation and the valve is partially or fully closed, while the pressure of the upstream seat 201 against the ball 100 is greatly reduced or eliminated when the ball 100 is being rotated.

(7) Rather than implementing a complex and expensive external pressurized pneumatic fluid system, the present invention uses the process fluid itself as the control fluid for adjusting the pressure of the upstream seat 201 against the ball 100. This is accomplished by reducing or eliminating the exposure of the rear of the upstream seat 201 to the upstream process fluid 110, and instead providing a separate pressurization chamber 200 behind the upstream seat 201, where the pressurization chamber 200 is can be interconnected by one or more valves 208 either to the upstream process fluid 100 or to the body cavity, including the small downstream space 114 that is in front of the upstream seat 201. In the illustrated example, the interconnection of the pressurization chamber 200 to the upstream process fluid 110 or to the small space 114 is controlled by a single 3-way valve, and the pressurization chamber 200 is otherwise isolated from the upstream process fluid 110 and from the small space 114 the by a pair of O-rings 202, 204.

(8) According to the present invention, the upstream process fluid 110 is connected via an upstream fluid bypass 206 to one or more pressurization valves, which are represented in FIGS. 2A and 2B by a single three-way valve 208, which is also connected to a pressurization passage 212 that is in fluid communication with the pressurization chamber 200. When the trunnion ball valve is closed, as illustrated in FIG. 2A, the upstream fluid bypass 206 is connected by the three-way valve to the pressurization passage 212, so that the fluid pressure within the pressurization chamber 200 is substantially equal to the upstream process fluid pressure.

(9) The three-way valve 208 is also connected via a downstream fluid bypass 210 to a region that is at a lower pressure than the upstream fluid, such as to the small space 114 that is in front of the upstream valve seat 201, as shown in FIGS. 2A and 2B, and/or to another lower pressure location within the body cavity and/or to the process fluid channel 300 downstream of the valve, as is shown in FIG. 3. When the valve is closed, as shown in FIG. 2A, the three-way valve 208 isolates and shuts off the downstream fluid bypass 210. When rotation of the ball 100 is required, as is shown in FIG. 2B, the three-way valve is reconfigured to shut off and isolate the upstream fluid bypass 206 while connecting the downstream fluid bypass 210 with the pressurizing passage 212, thereby substantially equalizing the pressure within the pressurization chamber 200 with the downstream process fluid pressure, and reducing or eliminating the pressing force that is applied to the upstream seat 201.

(10) In the embodiment of FIGS. 2A and 2B, changing the state of the upstream valve seat pressure thereby requires only control of a single three-way valve 202 that is in fluid communication with the upstream process fluid 110 and with the small space 114 within the body cavity, or with some other region of the body cavity or the downstream process fluid.

(11) In the illustrated embodiment, the upstream valve seat 201 presents a larger surface to the small space 114 in front of the valve seat 201 as compared to the pressurization chamber 200 at the rear of the valve seat 201. As a result, equalization of the pressures within these two spaces results in a net pressing of the upstream valve seat 201 away from the ball 100.

(12) In some embodiments, the three-way valve is mechanically linked to a manually actuated mechanism 214 that drives the valve stem, such that the three-way valve is automatically transitioned to its pressure relief configuration before rotation of the valve stems commences, and is re-transitioned to its pressurizing configuration when the valve is fully closed and rotation of the valve stem has ceased.

(13) In other embodiments, the three-way valve 208 is mechanically, electrically, pneumatically, or hydraulically driven, and an electronic controller 214 controls both the valve stem rotation and the configuration of the three-way valve. Note that element 214 in FIGS. 2A and 2B can represent either a purely mechanical linkage or an electronic controller.

(14) FIG. 3 is a sectional view of a trunnion ball valve that is similar to the valve of FIGS. 2A and 2B, but in which the downstream fluid bypass 210 interconnects the 3-way valve 208 with a fluid flow region 300 that is downstream of the trunnion valve.

(15) It should be noted that, unless otherwise required by context, the term “three-way valve” is used herein to denote any single valve, any plurality of valves, or any other mechanism, that can be transitioned between at least two states so as to connect one or the other of two inlets to a common outlet.

(16) The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. Each and every page of this submission, and all contents thereon, however characterized, identified, or numbered, is considered a substantive part of this application for all purposes, irrespective of form or placement within the application. This specification is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure.

(17) Although the present application is shown in a limited number of forms, the scope of the invention is not limited to just these forms, but is amenable to various changes and modifications. The disclosure presented herein does not explicitly disclose all possible combinations of features that fall within the scope of the invention. The features disclosed herein for the various embodiments can generally be interchanged and combined into any combinations that are not self-contradictory without departing from the scope of the invention. In particular, the limitations presented in dependent claims below can be combined with their corresponding independent claims in any number and in any order without departing from the scope of this disclosure, unless the dependent claims are logically incompatible with each other.