WO2018132114A1

WO2018132114A1 - Integrated flow control and flow measurement apparatus

Info

Publication number: WO2018132114A1
Application number: PCT/US2017/013678
Authority: WO
Inventors: Paul L. RILEY
Original assignee: Fmc Technologies, Inc.
Priority date: 2017-01-16
Filing date: 2017-01-16
Publication date: 2018-07-19

Abstract

An integrated flow control and flow measurement apparatus includes a body; a flow bore which extends through the body; a closure member which is positioned in the body and is movable between an open position in which a fluid is allowed to flow through the flow bore and a closed position in which the fluid is prevented from flowing through the flow bore; and a flow sensor which is operatively connected to the flow bore. When the closure member is in the open position, the flow sensor is operable to generate a signal from which a flow rate of the fluid through the flow bore is determinable.

Description

INTEGRATED FLOW CONTROL AND FLOW MEASUREMENT APPARATUS The present disclosure is directed to a flow control apparatus, such as a gate valve, and more particularly, to a flow control apparatus which includes a flow sensor to enable the flow control device to measure the flow rate of a fluid flowing through the device, thereby eliminating the need for a separate flow meter.

BACKGROUND OF THE INVENTION

Gate valves are used extensively in the hydrocarbon production industry to control the flow of fluids through various production and processing equipment. Likewise, flow meters are often used in the hydrocarbon production industry to measure the flow rate of the produced fluid through the same equipment. For example, subsea Christmas trees typically include a number of gate valves for controlling the flow of production fluid through the production bore and a flow meter for measuring the flow rate of the production fluid through the production bore. In a typical configuration, a gate valve referred to as a production wing valve and a flow meter form part of a production flow loop which is connected to the production outlet of the Christmas tree. In this configuration, the gate valve and flow meter comprise respective body forgings which are connected together by a flow loop weldment. Although this arrangement is satisfactory, the separate body forgings and flow loop weldment add to the overall cost and weight of the Christmas tree.

SUMMARY OF THE INVENTION

The present disclosure provides an integrated flow control and flow measurement apparatus which comprises a body; a flow bore which extends through the body; a closure member which is positioned in the body, the closure member being movable between an open position in which a fluid is allowed to flow through the flow bore and a closed position in which the fluid is prevented from flowing through the flow bore; and a flow sensor which is operatively connected to the flow bore; wherein when the closure member is in the open position, the flow sensor is operable to generate a signal from which a flow rate of the fluid through the flow bore is determinable.

In accordance with one aspect, the closure member may comprise a gate which is slidably positioned between two seats. Each seat comprises a seat bore which is aligned with the flow bore, and the gate comprises a through bore which when the gate is in the open position is aligned with the seat bores. In this embodiment, the flow bore may comprise a first diameter and the through bore may comprise a second diameter which is less than the first diameter. Further, each seat bore may comprise a first end which is located proximate the flow bore and a second end which is located proximate the gate, and the first end may comprise a third diameter which is approximately equal to the first diameter and the second end may comprise a fourth diameter which is approximately equal to the second diameter. Moreover, each seat bore may converge linearly from the third diameter to the fourth diameter.

In accordance with another aspect, the flow sensor may comprise a differential pressure transducer which is operatively connected to the flow bore via a first pressure port which is connected to the flow bore on an upstream side of the gate and a second pressure port which is connected to the through bore. In this embodiment, the second pressure port may comprise a first section which extends through the body and is connected to the differential pressure transducer and a second section which extends through the gate and is connected to the through bore, in which event the first section is connected to the second section when the gate is in the open position.

In accordance with a further aspect, the flow sensor may comprise a differential pressure transducer which is operatively connected to the flow bore via a first pressure port that is connected to one of the flow bore on an upstream side of the gate or the seat bore on the upstream side of the gate, and a second pressure port that is connected to one of the through bore, the seat bore on a downstream side of the gate, or the through bore on a downstream side of the gate. For example, the second pressure port may be connected to the through bore and comprise a first section which extends through the body and is connected to the differential pressure transducer; and a second section which extends through the gate and is connected to the through bore; wherein the first section is connected to the second section when the gate is in the open position. Furthermore, each seat bore may comprise a first end which is located proximate the flow bore and a second end which is located proximate the gate, and the first end may comprise a third diameter which is approximately equal to the first diameter and the second end may comprise a fourth diameter which is approximately equal to the second diameter. Also, each seat bore may converge linearly from the third diameter to the fourth diameter.

The present disclosure is also directed to an integrated gate valve and flow measurement apparatus which comprises a valve body; a flow bore which extends through the valve body; first and second spaced apart seats which are positioned in the valve body across the flow bore, each seat comprising a corresponding seat bore which is aligned with the flow bore; a gate which is positioned between the seats, the gate comprising a through bore and being movable between an open position in which the through bore is aligned with the seat bores and fluid is allowed to flow through the flow bore and a closed position in which the through bore is offset from the seat bores and fluid is prevented from flowing through the flow bore; and a flow sensor which is operatively connected to the flow bore; wherein when the gate is in the open position, the flow sensor is operable to generate a signal from which a flow rate of the fluid through the flow bore is determinable.

In accordance with one embodiment, the flow bore may comprise a first diameter and the through bore may comprise a second diameter which is less than the first diameter. Also, each seat bore may comprise a first end which is located proximate the flow bore and a second end which is located proximate the gate, and the first end may comprise a third diameter which is approximately equal to the first diameter and the second end may comprise a fourth diameter which is approximately equal to the second diameter. Further, each seat bore may converge linearly from the third diameter to the fourth diameter.

In accordance with another embodiment, the flow sensor may comprise a differential pressure transducer which is operatively connected to the flow bore through a first pressure port which is connected to the flow bore on an upstream side of the gate and a second pressure port which is connected to the through bore. The second pressure port may comprises a first section which extends through the body and is connected to the differential pressure transducer, and a second section which extends through the gate and is connected to the through bore, in which event the first section is connected to the second section when the gate is in the open position.

In accordance with yet another embodiment, the flow sensor may comprise a differential pressure transducer which is operatively connected to the flow bore via a first pressure port which is connected to one of the flow bore on an upstream side of the gate or the seat bore on the upstream side of the gate, and a second pressure port which is connected to one of the through bore, the seat bore on a downstream side of the gate, or the through bore on a

downstream side of the gate. The second pressure port may be connected to the through bore and comprise a first section which extends through the body and is connected to the differential pressure transducer; and a second section which extends through the gate and is connected to the through bore; wherein the first section is connected to the second section when the gate is in the open position. Further, each seat bore may comprise a first end which is located proximate the flow bore and a second end which is located proximate the gate, and the first end may comprise a third diameter which is approximately equal to the first diameter and the second end may comprise a fourth diameter which is approximately equal to the second diameter.

Thus, the integrated flow control and flow measurement apparatus combines the capabilities of a flow control device and a flow measurement device into a single component. In the field of subsea production and processing equipment, for example, this design can reduce the cost, weight and complexity of the equipment by reducing the number of body forgings required and the associated pipe work necessary to connect the body forgings together.

These and other objects and advantages will be made apparent from the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers are used to denote similar components in the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross sectional view of an example of a prior art gate valve;

Figure 2 is a cross sectional view of an example of a prior art flow meter;

Figure 3 is a simplified representation of a prior art subsea Christmas tree;

Figure 4 is a cross sectional view of one embodiment of the integrated flow control and flow measurement apparatus of the present disclosure; and

Figure 5 is a simplified representation of a subsea Christmas tree which comprises the integrated flow control and flow measurement apparatus shown in Figure 4. DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the integrated flow control and flow measurement apparatus of the present disclosure comprises a body, a flow bore which extends through the body, a closure member which is positioned in the body and is movable between an open position in which a fluid is allowed to flow through the flow bore and a closed position in which the fluid is prevented from flowing through the flow bore, and a flow sensor which is operatively connected to the flow bore. In this embodiment, when the closure member is in the open position, the flow sensor is operable to generate a signal from which a flow rate of the fluid through the flow bore can be determined. The closure member may comprise any device which is capable of controlling the flow of fluid through the flow bore, including but not limited to a gate, a ball, a plug, a flapper, or a choke insert. Accordingly, the integrated flow control and flow measurement apparatus may comprise as the flow control component any number of existing valves, including, for example, a gate valve, a ball valve, a plug valve, a flapper valve, or a choke, in which case the valve body will define the body of the apparatus.

The flow sensor may comprise the mechanical and/or electrical operating components of any of a variety of existing fluid flow meters, such as a differential pressure flow meter, an ultrasonic flow meter, an electromagnetic flow meter, a thermal flow meter, a vortex flow meter, a turbine flow meter, or a multiphase flow meter, for example. Furthermore, the phrase "operatively connected to the flow bore" should be interpreted to mean that the operating components of the flow sensor are connected to the flow bore in such a manner as to enable the flow sensor to detect the conditions from which the flow rate can be determined. For example, in an ultrasonic flow meter, the main operating components of the flow sensor, namely, the ultrasonic transducers, are mounted around the outside of the flow bore. In contrast, in a thermal flow meter, the temperature sensor components of the flow sensor protrude into the flow bore. Persons of ordinary skill in the art will readily understand how the operating components of other types of flow sensors are operatively connected to the flow bore.

In more specific embodiment, the present disclosure is directed to an integrated gate valve and flow meter apparatus. Such an integrated apparatus has application in a variety of industries which employ separate gate valves and flow meters to control and measure fluid flow through an apparatus. One industry in which the integrated gate valve and flow meter of the present disclosure is particularly useful is the subsea hydrocarbon production industry. By eliminating the need for both a gate valve and a separate flow meter, the integrated apparatus can reduce the overall weight and cost of the subsea apparatus.

In the following, the integrated flow control and flow measurement apparatus of the present disclosure will be described in the context of an integrated gate valve and differential pressure flow meter apparatus . However, persons of ordinary skill in the art will be able to apply these teachings to create other types of integrated flow control and flow measurement apparatuses based on other types of closure devices and flow meters. Therefore, the present disclosure should not be limited to the embodiment of the integrated gate valve and differential pressure flow meter apparatus described below.

As background for the embodiment of the integrated gate valve and differential pressure flow meter apparatus described below, examples of a prior art gate valve and a prior art differential pressure flow meter will first be provided.

An example of a prior art gate valve is shown in Figure 1. The gate valve of this example, which is indicated generally by reference number 10, includes a valve body 12 comprising opposite first and second ends 14, 16, a flow bore 18 which extends longitudinally through the valve body between the first and second ends, a gate cavity 20 which extends transversely through the valve body across the flow bore, first and second seats 22, 24 which are each positioned at least partially in a corresponding seat pocket that is formed at the intersection of the flow bore and the gate cavity, and a gate 26 which is slidably positioned between the seats. Each seat 22, 24 includes an axial seat bore 28, 30 which is aligned with and comprises approximately the same diameter as the flow bore 18, and the gate includes a through bore 32 which likewise comprises approximately the same diameter as the flow bore 18. The gate 26 is connected to a stem 34 which in turn is connected to an actuator 36. The actuator 36, which may comprise any suitable manual or electrically or hydraulically operated device, functions to move the gate 26 between an open position in which the through bore 32 is aligned with the seat bores 28, 30 and fluid is allowed to flow through the flow bore 18, and a closed position in which the through bore is offset from the seat bores and fluid is therefore blocked from flowing through the flow bore. An example of a prior art differential pressure flow meter is depicted in Figure 2. The flow meter of this example, generally 38, includes a flow meter body 40 comprising opposite first and second ends 42, 44, a flow bore 46 which extends longitudinally through the body between the first and second ends, first and second pressure ports 48, 50 which extend through the body to the flow bore, and a differential pressure transducer 52 which is mounted to body. In this example, the flow sensor comprises the differential pressure transducer 52, and this transducer is operatively connected to the flow bore 46 through the first and second pressure ports 48, 50. The transducer 52 comprises first and second transducer ports 54, 56 which are each connected to a corresponding pressure port 48, 50. In the particular example shown in Figure 2, the transducer ports 54, 56 are connected to the pressure ports 48, 50 through a connecting flange 58. The connecting flange 58 is bolted or otherwise secured to the body 40 and comprises a pair of conduit bores 60, 62 which each extend between a corresponding transducer port 54, 56 and a corresponding pressure port 48, 50. The flow bore 46 includes a first bore section 64 located proximate the first end 42 of the body 40, a second bore section 66 located proximate the second end 44 of the body, a reduced diameter orifice 68 positioned between the first and second bore sections, and first and second conical sections 70, 72 which connect the first and second bore sections to the orifice, respectively. The first pressure port 48 is connected to the first bore section 64 and the second pressure port 50 is connected to the orifice 68. As is well understood by persons skilled in the art, as fluid flows through the flow bore 46, the differential pressure transducer 52 measures the difference in pressure between the first bore section 48 and the orifice 50 and generates a signal which is used to determine the velocity of the fluid.

As discussed above, gate valves and flow meters are commonly used in the hydrocarbon production industry to control and measure the flow of fluid through subsea production and processing apparatuses. One example of a subsea production apparatus which employs both a gate valve and a flow meter to control and measure the flow of a hydrocarbon production fluid is the prior art subsea Christmas tree shown in Figure 3. In this simplified representation, the Christmas tree, generally 74, is shown to comprise a vertical production bore 76, a lateral production outlet 78 which is connected to the production bore, and a production flow loop 80 which is connected to the production outlet. The production flow loop 80 includes a gate valve 82 and a flow meter 84 which are connected together via a flow loop weldment 86. The gate valve 82 controls the flow of production fluid through the production outlet 78, and the flow meter 84 measures the flow rate of the production fluid through the production flow loop 80 when the gate valve is open. The gate valve 82 and flow meter 84 may be similar to the gate valve 10 and flow meter 38 described above. As such, the gate valve 82 and flow meter 84 comprise respective bodies'! 2, 40 which are not only costly to produce, but also relatively heavy. In addition, the connections between these devices and the flow loop weldment 86 present potential leak paths for the production fluid.

Thus, in accordance with the present disclosure, the measurement features of a flow meter are incorporated into a gate valve to thereby eliminate the need for a separate flow meter body. The resulting integrated gate valve and flow meter apparatus is therefore able to both control and measure the flow of fluid through an apparatus to which the gate valve is connected.

One example of an integrated gate valve and flow meter apparatus is shown in Figure 4. Similar to the prior art gate valve 10 described above, the integrated gate valve and flow meter apparatus of this embodiment, which is indicated generally by reference number 100, includes a body 102 having opposite first and second ends 104, 106, a flow bore 108 which extends longitudinally through the body between the first and second ends, a gate cavity 1 10 which extends transversely through the body and intersects the flow bore, first and second seats 1 12, 1 14 which are each positioned at least partially in a corresponding seat pocket that is formed at the intersection of the flow bore and the gate cavity, and a gate 1 16 which is slidably positioned between the seats. Each seat 1 12, 1 14 comprises an axial seat bore 1 18, 120 which is aligned with the flow bore 108, and the gate 1 16 comprises a through bore 122 which is aligned with the seat bores when the gate is in an open position. As with the prior art gate valve 10 described above, the gate 1 16 is connected to a valve stem which in turn is connected to an actuator that functions to move the gate between the open position in which the through bore 122 is aligned with the seat bores 1 18, 120 and fluid is allowed to flow through the flow bore 108, and a closed position in which the through bore is offset from the seat bores and fluid is blocked from flowing through the flow bore. It should be noted that in Figure 4, the gate valve 100 is oriented such that the gate 1 16 moves transverse to the plane of the paper. In this orientation, the actuator would be positioned behind the body 102 and the valve stem would be positioned behind the gate 1 16.

Therefore, these components are not visible in Figure 4.

In the present embodiment, the integrated gate valve and flow meter apparatus 100 also includes a flow sensor in the form of a differential pressure transducer 124. Also, the seats 1 12, 1 14 and the gate 1 16 are configured to form a venturi tube which, in accordance with the operating principles of a differential pressure flow meter, will create a pressure difference in the flowing fluid that can be measured by the differential pressure transducer 1 18. As shown in Figure 4, the through bore 122 comprises a diameter which is smaller than the diameter of the flow bore 108. In addition, each seat bore 1 18, 120 comprises a first end 1 18a, 120a which is located proximate the flow bore 108 and a second end 1 18b, 120b which is located proximate the gate 1 16, and the diameter of the first end of each seat bore is approximately equal to the diameter of the flow bore while the diameter of the second end of each seat bore is approximately equal to the diameter of the through bore 122. When configured as such, the seat bores 1 18, 120 and the through bore 122 will form a venturi tube. As is understood by persons skilled in the art, as a result of this configuration the velocity of a fluid flowing through the flow bore 108 from the first end 104 to the second end 106 will be greater within and immediately downstream of the through bore 122 than upstream of the through bore. Consequently, the pressure of the fluid upstream of the through bore 122 will be greater than the pressure of the fluid within and immediately downstream of the through bore, and this pressure difference can be measured by the differential pressure transducer 124 to provide a basis for calculating the velocity of the fluid through the through bore 108. It should be noted that, although the seat bores 1 18, 120 are shown in Figure 4 to converge linearly from their respective first ends 1 18a, 120a to their respective second ends 1 18b, 120b, they could be configured to converge in a non-linear fashion.

In an alternative embodiment, the through bore 122 comprises a diameter which is less than the diameter of the flow bore 108 and the seat bores 1 18, 120 comprise a uniform diameter approximately equal to the diameter of the flow bore. In this embodiment, the gate 1 16 will function as an orifice plate. As is understood by persons skilled in the art, the orifice plate functions similar to a venturi tube to create a differential pressure in the fluid which can be measured by the differential pressure transducer 124.

The differential pressure transducer 124 is operatively connected to the flow bore 108 by first and second pressure ports 126, 128 which are formed in the body 102. In the embodiment shown in Figure 4, the first pressure port 126 is connected to a first bore section 108a which extends between the first end 104 of the body 102 and the gate cavity 1 10, and the second pressure port 128 is connected to the through bore 122. In this regard, the second pressure port 128 comprises a first port section 128a which extends through the body 102 and is connected to the differential pressure transducer 124, and a second port section 128b which extends through the gate 1 16 and is connected to the through bore 122. When as shown in Figure 4 the gate 1 16 is in the open position, the second port section 128b is aligned with the first port section 128a to thereby connect the through bore 122 to the differential pressure transducer 124. If as shown in Figure 4 the gate 1 16 is positioned between a pair of guide members 130, the second pressure port 128 will comprise a third port section 128c which extends through the guide member adjacent the first port section 128a to thereby connect the first port section to the second port section 128b.

The differential pressure transducer 124 comprises first and second transducer ports 132, 134 which are connected to the first and second pressure ports 126, 128, respectively. The transducer ports 132, 134 may be connected to the pressure ports 126, 128 by any suitable means, such as with respective conduit tubes and fittings (not shown). In the embodiment shown in Figure 4, for example, the transducer ports 132, 134 are connected to the pressure ports 126, 128 through a connecting flange 136 similar to the connecting flange 58 described above. The connecting flange 136 may be bolted or otherwise secured to the body 102 and comprises a pair of conduit bores 138, 140 which are each connected between a corresponding pressure port 126, 128 and a corresponding transducer port 132, 134.

In an alternative embodiment not shown in the drawings, instead of being connected to the first bore section 108a, the first pressure port 126 is connected to the first seat bore 1 18 through a corresponding hole in the first seat 1 12. In a further alternative embodiment, instead of being connected to the through bore 122, the second pressure port 128 is connected to the second seat bore 120 through a corresponding hole in the second seat 1 14. This embodiment eliminates the need for the gate 1 16 to be fully open for a flow measurement to be taken. Instead, the partially open gate 1 16 will form a constricted through bore 122 which will create the venturi effect that can be measured by the differential pressure transducer 124. In another alternative embodiment, the second pressure port 128 may be connected to a second bore section 108b which extends from the gate cavity 1 10 to the second end 106 of the body 102. This embodiment eliminates the need for the second pressure port 129 to extend through the gate 1 16 or the second seat 1 14.

Referring now to Figure 5, an example of a Christmas tree comprising an integrated flow control and flow measurement apparatus of the present disclosure is shown. The Christmas tree, generally 200, includes a vertical production bore 202 and a lateral production outlet 204 to which a production flow loop 206 is connected. In comparison to the prior art tree shown in Figure 3, however, the flow loop 206 comprises a single integrated flow control and flow measurement apparatus 208 instead of a separate gate valve and flow meter connected by a flow loop weldment. The integrated apparatus 208 functions to control the flow of production fluid through the production outlet 204 and can therefore serve as a conventional production wing valve. The integrated apparatus 208 also functions to measure the flow rate of the production fluid through the flow loop 206, thereby eliminating the need for a separate flow meter with its concomitant flow meter body and an associated flow loop weldment to connect the flow meter body to the gate valve. Therefore, the overall cost, weight and complexity of the tree 200 are substantially reduced.

It should be recognized that, while the present invention has been described in relation to the preferred embodiments thereof, those skilled in the art may develop a wide variation of structural and operational details without departing from the principles of the invention. Therefore, the appended claims are to be construed to cover all equivalents falling within the true scope and spirit of the invention.

Claims

What is Claimed is:

1 . An integrated flow control and flow measurement apparatus which comprises:

a body;

a flow bore which extends through the body;

a closure member which is positioned in the body, the closure member being movable between an open position in which a fluid is allowed to flow through the flow bore and a closed position in which the fluid is prevented from flowing through the flow bore; and

a flow sensor which is operatively connected to the flow bore; wherein when the closure member is in the open position, the flow sensor is operable to generate a signal from which a flow rate of the fluid through the flow bore is determinable.

2. The apparatus of claim 1 , wherein the closure member comprises a gate which is slidably positioned between two seats, each seat comprising a seat bore which is aligned with the flow bore, and the gate comprising a through bore which when the gate is in the open position is aligned with the seat bores.

3. The apparatus of claim 2, wherein the flow bore comprises a first diameter and the through bore comprises a second diameter which is less than the first diameter.

4. The apparatus of claim 3, wherein each seat bore comprises a first end which is located proximate the flow bore and a second end which is located proximate the gate, and wherein the first end comprises a third diameter which is approximately equal to the first diameter and the second end comprises a fourth diameter which is approximately equal to the second diameter.

5. The apparatus of claim 4, wherein each seat bore converges linearly from the third diameter to the fourth diameter.

6. The apparatus of claim 5, wherein the flow sensor comprises a differential pressure transducer which is operatively connected to the flow bore via a first pressure port which is connected to the flow bore on an upstream side of the gate and a second pressure port which is connected to the through bore.

7. The apparatus of claim 6, wherein the second pressure port comprises: a first section which extends through the body and is connected to the differential pressure transducer; and

a second section which extends through the gate and is connected to the through bore; and

wherein the first section is connected to the second section when the gate is in the open position.

8. The apparatus of claim 3, wherein the flow sensor comprises a differential pressure transducer which is operatively connected to the flow bore via a first pressure port which is connected to one of the flow bore on an upstream side of the gate or the seat bore on the upstream side of the gate, and a second pressure port which is connected to one of the through bore, the seat bore on a downstream side of the gate, or the through bore on a downstream side of the gate.

9. The apparatus of claim 8, wherein the second pressure port is connected to the through bore and comprises:

a first section which extends through the body and is connected to the differential pressure transducer; and

10. The apparatus of claim 9, wherein each seat bore comprises a first end which is located proximate the flow bore and a second end which is located proximate the gate, and wherein the first end comprises a third diameter which is approximately equal to the first diameter and the second end comprises a fourth diameter which is approximately equal to the second diameter.

1 1 . The apparatus of claim 10, wherein each seat bore converges linearly from the third diameter to the fourth diameter.

12. An integrated gate valve and flow measurement apparatus which comprises:

a valve body;

a flow bore which extends through the valve body; first and second spaced apart seats which are positioned in the valve body across the flow bore, each seat comprising a corresponding seat bore which is aligned with the flow bore;

a gate which is positioned between the seats, the gate comprising a through bore and being movable between an open position in which the through bore is aligned with the seat bores and fluid is allowed to flow through the flow bore and a closed position in which the through bore is offset from the seat bores and fluid is prevented from flowing through the flow bore; and

a flow sensor which is operatively connected to the flow bore;

wherein when the gate is in the open position, the flow sensor is operable to generate a signal from which a flow rate of the fluid through the flow bore is determinable.

13. The apparatus of claim 12, wherein the flow bore comprises a first diameter and the through bore comprises a second diameter which is less than the first diameter.

14. The apparatus of claim 13, wherein each seat bore comprises a first end which is located proximate the flow bore and a second end which is located proximate the gate, and wherein the first end comprises a third diameter which is approximately equal to the first diameter and the second end comprises a fourth diameter which is approximately equal to the second diameter.

15. The apparatus of claim 14, wherein each seat bore converges linearly from the third diameter to the fourth diameter.

16. The apparatus of claim 15, wherein the flow sensor comprises a differential pressure transducer which is operatively connected to the flow bore through a first pressure port which is connected to the flow bore on an upstream side of the gate and a second pressure port which is connected to the through bore.

17. The apparatus of claim 16, wherein the second pressure port comprises:

a second section which extends through the gate and is connected to the through bore; and wherein the first section is connected to the second section when the gate is in the open position.

18. The apparatus of claim 13, wherein the flow sensor comprises a differential pressure transducer which is operatively connected to the flow bore via a first pressure port which is connected to one of the flow bore on an upstream side of the gate or the seat bore on the upstream side of the gate, and a second pressure port which is connected to one of the through bore, the seat bore on a downstream side of the gate, or the through bore on a downstream side of the gate.

19. The apparatus of claim 18, wherein the second pressure port is connected to the through bore and comprises:

20. The apparatus of claim 19, wherein each seat bore comprises a first end which is located proximate the flow bore and a second end which is located proximate the gate, and wherein the first end comprises a third diameter which is approximately equal to the first diameter and the second end comprises a fourth diameter which is approximately equal to the second diameter.