WO2019168513A1

WO2019168513A1 - Flow measurement in a multi-phase flow

Info

Publication number: WO2019168513A1
Application number: PCT/US2018/020135
Authority: WO
Inventors: Sebastien BOISVERT
Original assignee: Siemens AG; Siemens Corp
Current assignee: Siemens AG; Siemens Corp
Priority date: 2018-02-28
Filing date: 2018-02-28
Publication date: 2019-09-06
Anticipated expiration: 2020-08-28

Abstract

A method for measuring a fluid in a flow line containing two or more phases includes operating a flow meter and a flow control valve located downstream of the flow meter on the flow line. The flow control valve is operated so as to move the flow control valve toward a closed position until the fluid accumulates upstream of the flow meter. The position of the flow control valve is then modulated until a level of the accumulated fluid upstream of the flow meter is stable. The flow meter is operated to measure flow of the fluid in the flow line while the level of the accumulated fluid upstream of the flow meter is stable.

Description

FLOW MEASUREMENT IN A MULTI-PHASE FLOW

BACKGROUND

[0001] 1. Field

[0002] Disclosed embodiments are generally related to a method, apparatus and system for measuring a fluid in a multi-phase flow.

[0003] 2. Description of the Related Art

[0004] Gas turbine engines generate combustion products in combustors. The combustion products are transmitted downstream in the gas turbine engine to rows of rotating turbine blades coupled to a turbine rotor. As the combustion products expand through the turbine section, the combustion products cause the blade assemblies and the turbine rotor to rotate.

[0005] The gas turbine engine may use a lubrication sub-system that provides oil to some rotating components of the gas turbine engine so it can operate without fail. The lubrication sub-system interfaces with the gas turbine engine. Oil is used as a lubricant in order to take heat away from the rotating components and to reduce friction. Most significantly sized combustion engines require a lubrication system.

[0006] The oil used in the lubrication sub-system may be delivered to gas turbine bearing chambers. Some of the oil that enters into the gas turbine bearing chamber can escape through bearing chamber vents. Some of the oil exits through drains and returns to the lubrication sub-system. In some designs, the vented oil may be directed through a separator/mist eliminator, condense and may also return to the lubrication sub-system such that very little or no oil vapour actually escapes into the ambient. Knowing the amount of oil that exits through the vents and through the drain is difficult to determine and usually involves testing that can interrupt the operation of the gas turbine engine.

SUMMARY

[0007] Briefly described, aspects of the present disclosure relate to measurement of a fluid in a multi-phase flow involving two or more phases.

[0008] A first aspect of the present invention is directed to a method for measuring a fluid in a flow line containing two or more phases. The method involves operating a flow control valve located downstream of a flow meter on the flow line, which comprises: moving the flow control valve toward a closed position such that the fluid accumulates upstream of the flow meter, and modulating a position of the flow control valve until a level of the accumulated fluid upstream of the flow meter is stable. The method then involves measuring flow of the fluid in the flow line by the flow meter while the level of the accumulated fluid upstream of the flow meter is stable.

[0009] A second aspect of the present invention is directed to an apparatus for measuring a fluid in a flow line containing two or more phases. The apparatus comprises a flow meter for measuring flow of the fluid in the flow line, a flow control valve located downstream of the flow meter on the flow line, and control means for controlling a position of the flow control valve. The control means is configured for moving the flow control valve toward a closed position such that the fluid accumulates upstream of the flow meter, and modulating a position of the flow control valve until a level of the accumulated fluid upstream of the flow meter is stable. The flow meter is operable for measuring flow of the fluid in the flow line while the level of the accumulated fluid upstream of the flow meter is stable.

[0010] A third aspect of the present invention is directed to a system for measuring flow of a fluid. The system comprises a chamber pressurized by a pressurizing medium. A fluid feed line supplies a fluid to the chamber. One or more vents are connected to the chamber for venting a first portion of the fluid from the chamber. A drain line is connected to the chamber for draining a second portion of the fluid from the chamber. The drain line contains a multi-phase flow comprising a first phase defined by the fluid and a second phase defined by the pressurizing medium. The system comprises a first flow meter for measuring flow of the fluid at the fluid feed line and a second flow meter for measuring flow of the fluid in the drain line. The system further comprises a flow control valve located downstream of the second flow meter on the drain line and control means for controlling a position of the flow control valve. The control means is configured for moving the flow control valve toward a closed position such that the fluid accumulates upstream of the second flow meter, and for modulating a position of the flow control valve until a level of the accumulated fluid upstream of the second flow meter is stable. The second flow meter is operable for measuring flow of the fluid in the drain line while the level of the accumulated fluid upstream of the second flow meter is stable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention is shown in more detail by help of figures. The figures show specific configurations and do not limit the scope of the invention.

[0012] FIG. 1 shows a diagram depicting a system for measuring fluid flow according to an aspect of the present invention; and

[0013] FIG. 2 is a flow chart depicting a method for measuring fluid flow according to an aspect of the present invention.

DETAILED DESCRIPTION

[0014] To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods.

[0015] The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present disclosure.

[0016] The inventor recognized that determining fluid flow in in the drain line of the bearing chamber of a gas turbine engine has presented problems in the past. A method such as a“bucket test” has proven problematic in determining fluid in the system for systems that are pressurized. The bucket test diverts the fluid, oil, into a volume associated with the lubrication system over a period of time and then measures the amount of oil. This can provide a measurement of the oil but interferes with the operation of the gas turbine engine.

[0017] Eising a flow meter within the lubrication system associated with the gas turbine engine can provide an indication of the amount of oil in the system; however this measurement may not be accurate. This is in part due to the two-phase nature of the fluid and air moving through the drain line. This creates a situation that is not ideal for accurate measurement by the flow meter. In general, flow meters provide better, i.e. more accurate results, when only a single-phase fluid moves past the flow meter.

[0018] The inventor has developed techniques for determining the flow of fluids in situations where multiple phases had previously presented a problem. One such technique is disclosed in the International Application No. PCT/US2017/021241, filed on March 3, 2017, by the present Applicant, titled“FLUID FLOW MEASUREMENT IN GAS TURBINE ENGINES”, which is herein incorporated by reference in its entirety. The above disclosure teaches the use of an electrically driven positive displacement pump to provide motive force to the fluid.

[0019] Embodiments of the present disclosure may be applicable in a pressurized system where the motive force to the fluid may be provided by the process pressure upstream, whereby the fluid may progress downstream to a lower pressure zone without the extra energy required for pumping. In such an application, it may be possible to obviate the need for a pumping arrangement and the associated control mechanism. The embodiments disclosed herein may be directed to such an application.

[0020] It should be understood that while the present invention is discussed and described within the context of a gas turbine engine, aspects of the present invention can be employed in different scenarios that involve multi-phase flow (involving two or more phases). Examples of these systems may be sewage systems, boiler systems, steam circuits, water cooling in nuclear reactors, petrol refineries, water production/treatment plants, as well as potential implementation within the food industry.

[0021] Referring to FIG. 1, an example of a system 100 for measuring fluid flow is illustrated. In the illustrated example, the system 100 is part of a lubrication system of a gas turbine engine. The system 100 includes a pressurized chamber 12, which, in this example, is a gas turbine bearing chamber. A fluid feed line 8 delivers a fluid, which in this example is a lubricating fluid, to the gas turbine bearing chamber 12. In the embodiment disclosed herein, the fluid delivered to the gas turbine bearing chamber 12 is oil. In other embodiments, the fluid may include, for example, steam or water. A pressurizing medium, such as pressurized air, may also be supplied the gas turbine bearing chamber 12 in order to seal the chamber 12. The chamber 12 may be provided with one or more vents 11 for venting a portion of the fluid and air from the chamber 12. A drain line 14 may be connected to the chamber 12 for draining the remaining portion of the fluid and air from the chamber 12. The drain line therefore contains a multi-phase flow (in this case, a two-phase flow) comprising a first phase defined by the fluid and a second phase defined by the pressurizing medium, i.e., air.

[0022] Typically, it is difficult to determine the amount of fluid (oil in this instance) that is vented through the vents 11 during operation. Embodiments of the present invention enable an accurate determination of the amount of fluid that is drained, which, in turn, facilitates determination of the amount of fluid that is vented during the operation of the gas turbine engine. By being able to accurately determine the amount of fluid drained and vented, an overall oil distribution in the system may be obtained, which can lead, for example, to improved pressure loss predictions for the gas turbine engine installation.

[0023] As part of the measuring system 100, a first flow meter 10 is located upstream of the gas turbine bearing chamber 12 on the fluid feed line 8. The flow meter 10 measures the flow of fluid that passes through the fluid feed line 8. The measured inlet fluid flow by the flow meter 10 may used eventually to ascertain how much fluid is vented through the vents 11 versus that which is passed through the drain line 14.

[0024] The fluid leaves the gas turbine bearing chamber 12 through the drain line 14 and vents 11. In the illustrated embodiment, movement of the fluid through the drain line 14 is driven by a difference in process pressure as the fluid moves downstream from the pressurized chamber 12 toward a lower pressure zone. The amount of fluid in the drain line 14 may be measured by a second flow meter 28 located downstream of the chamber 12 on the drain line 14. The flow meter 28, may include, for example, a Coriolis type of flow meter, among other types. At least a portion of the drain line 14 upstream of the flow meter 28 may be oriented vertical or sloping (i.e. not completely horizontal).

[0025] As stated above, the flow through the drain line 14 includes a mixture of the fluid (in this example, oil) and the pressurizing medium (in this example, air), which may lead of inaccuracies in the measurement of the fluid in the drain line 14 by the flow meter 28. The inventor has devised a method and apparatus to locally transition the multi-phase flow in the flow line 14, comprising the fluid and the pressurizing medium, into an essentially single-phase flow containing the fluid only, to facilitate accurate measurement of the fluid in the flow line 14 by the flow meter 28. As described hereinafter, the above is achieved by measuring the flow of the fluid in the flow line 14 by the flow meter 28 after ensuring a steady level of accumulated fluid upstream of the flow meter 28. The measurement of the fluid in the flow line 14 by the second flow meter 28 may be subtracted from the value obtained from the measurement of the fluid flow by the first flow meter 10 located upstream of the chamber 12, to determine an amount of fluid exiting the chamber 12 through the vents 11.

[0026] In the present embodiment, a flow control valve 32 is located downstream of the flow meter 28 on the flow line 14, which forms the drain line of the example system 100. The flow control valve 32 may include, for example and without limitation, a profiled ball valve, among other types, which is operable to adjust the flow in the flow line 14. In particular, the position of the flow control valve 32 may be controlled so as to effect an accumulation of the fluid upstream of the flow meter 28. The flow control valve 32 may be provided with control means 50, such as a programmable logic controller, for controlling a position of the flow control valve 32 to thereby adjust a cross-sectional area of the flow through the flow control valve 32. In some embodiments, a relief valve 34 may be connected to the flow control valve 32. The relief valve 34 may operate as a safety mechanism for the control valve 32 and can be used to prevent excessive pressure build up if required.

[0027] As an optional feature, a holding volume 16 may be upstream of the flow meter 28, preferably on a vertical or sloping part of the drain line 14. The holding volume 16 may receive the fluid as it accumulates upstream of the flow meter 28 when the flow control valve 32 is operated. Furthermore, having the holding volume 16 can provide additional reaction time should the fluid accumulation upstream of the flow meter 28 become uncontrolled and begin backing up into the gas turbine bearing chamber 12, which might cause potential damage to the gas turbine engine. The accumulation of the fluid upstream of the flow meter 28 may be determined by measuring a static head of the fluid at an inlet of the flow meter 28. In particular, the level of the accumulated fluid may be measured by measuring a differential pressure across the holding volume 16. To this end, a differential pressure transducer 22 may be provided, comprising a high-pressure side 22a for measuring the fluid head pressure at the bottom of the holding volume 16, and a low-pressure side 22b for measuring a reference pressure at the top of the holding volume 16. The differential between the measurements at 22a and 22b yields a static head of the fluid. Under regular operation, the differential pressure measured by the transducer 22 is essentially zero. A positive differential pressure measured by the transducer 22 indicates that fluid has accumulated upstream of the flow meter 28.

[0028] Referring now to FIG. 2, with continued reference to FIG. 1, a method 200 for measurement of the flow line 14 is illustrated.

[0029] In step 202, when a measurement of the fluid flow in the flow line 14 is desired, the flow control valve 32 is operated so as to move the flow control valve 32 toward a closed position such that the fluid accumulates upstream of the flow meter 28. Before this operation, the accumulated fluid level upstream of the flow meter 28 is essentially zero. The actuation of the flow control valve 32 toward the closing position continues, preferably in a gradual manner, until fluid begins to accumulate upstream of the flow meter 28. The accumulation of fluid is indicated by a positive static head of the fluid at the inlet of the flow meter 28. In the example embodiment described herein, the accumulation of fluid may be indicated by the differential pressure transducer 22 which begins to register a value greater than zero (i.e. a positive value).

[0030] In step 204, when the accumulated fluid has reached a desired level, the position of the flow control valve is modulated until the level of the accumulated fluid upstream of the flow meter 28 is determined to be stable. By“stable” it is meant that the fluid level, as indicated by the differential pressure measurement upstream of the flow meter 28, has remained substantially constant for the duration of the measurement. The modulation may be implemented by the valve control means 50, which generates an actuation signal 51 to adjust or fine-tune the position of the flow control valve 32 in response to differential pressure measurement signals 52 received from the transducer 22, based on a feedback control loop. Controlling level fluctuations to the smallest amplitude possible around a constant mean value will result in optimal accuracy for the fluid flow measurement figure. When the differential pressure measured by the transducer 22 is positive and stable, it indicates that the fluid has accumulated upstream of the flow meter and the level is stable. [0031] In the illustrated example, the control means 50 comprises electronic control circuitry, for example, including a programmable logic controller, to control an opening or closing of the flow control valve 32. In other embodiments, the control means 50 may incorporate a sight glass on the vertical/ sloping piping section of the drain line 14 in combination with a manual handle on the flow control valve 32, controlled by a human operator. A further example of a control means 50 may incorporate a float, lever and needle valve system (modulating air pressure) in the vicinity of holding volume 16 in combination with air actuator on the flow control valve 32.

[0032] When the level of the accumulated fluid upstream of the flow meter 28 (as indicated by the differential pressure) is stable, the flow in the drain line 14 locally transitions into a single-phase flow containing the fluid only. Accordingly, at step 206, the measurement of the fluid in the drain line 14 is performed by the flow meter 28 while the level of the accumulated fluid upstream of the flow meter 28 is stable. Ensuring a single-phase flow during the measurement increases the accuracy in the measurement of the fluid by the flow meter 28.

[0033] The measuring system 100 as illustrated herein is able to provide precise measurement of the fluid content within the drain line 14. Measuring the fluid flow precisely in the drain line 14 may be used to determine the amount of fluid that escapes through vents 11 in the gas turbine bearing chamber 12. This is accomplished by subtracting the amount of fluid measured by the flow meter 28 from the amount of fluid measured by the flow meter 10 as the fluid enters into the measuring system 100.

[0034] The illustrated measuring system 100 allows continuous adjustments to the process without interrupting tests as well as a smooth return to normal gas turbine operations. Furthermore, the use of the measuring system 100 can provide increased precision of a fluid digital model of the gas turbine engine. This can also provide improved pressure loss predictions for installations. Additionally, improved sizing of equipment used can occur based on the results of the tests performed.

[0035] While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.

Claims

1. A method for measuring a fluid in a flow line containing two or more phases, comprising:

operating a flow control valve located downstream of a flow meter on the flow line, wherein operating the flow control valve comprises:

moving the flow control valve toward a closed position such that the fluid accumulates upstream of the flow meter,

modulating a position of the flow control valve until a level of the accumulated fluid upstream of the flow meter is stable; and

measuring flow of the fluid in the flow line by the flow meter while the level of the accumulated fluid upstream of the flow meter is stable.

2. The method according to claim 1, wherein an accumulation of the fluid upstream of the flow meter is determined by measuring a static head of the fluid at an inlet of the flow meter.

3. The method according to claim 1, wherein a holding volume is provided upstream of the flow meter, wherein the fluid accumulates in the holding volume when the flow control valve is operated.

4. The method according to claim 3, wherein the accumulation of the fluid is measured by measuring a differential pressure across the holding volume.

5. The method according to claim 1, wherein the flow line is a drain line for a pressurized gas turbine bearing chamber.

6. The method according to claim 5, wherein said fluid is a lubricating fluid for the gas turbine bearing chamber, and

wherein the drain line contains a multi-phase flow comprising a first phase defined by the lubricating fluid and a second phase defined by a pressurizing medium.

7. The method according to claim 6, further comprising determining a flow of the lubricating fluid that is vented from the gas turbine bearing chamber based on the measured flow of the lubricating fluid in the drain line by said flow meter.

8. The method according to claim 7, wherein determining the flow of the lubricating fluid that is vented from the gas turbine bearing chamber comprises: measuring a flow of the lubricating fluid entering the gas turbine bearing chamber, and

subtracting the measured flow of the fluid in the drain line from the measured flow of the fluid entering the gas turbine bearing chamber.

9. An apparatus for measuring a fluid in a flow line containing two or more phases, comprising:

a flow meter for measuring flow of the fluid in the flow line;

a flow control valve located downstream of the flow meter on the flow line; and

control means or controlling a position of the flow control valve,

the control means being configured for moving the flow control valve toward a closed position such that the fluid accumulates upstream of the flow meter, and modulating a position of the flow control valve until a level of the accumulated fluid upstream of the flow meter is stable; and

wherein the flow meter is operable for measuring flow of the fluid in the flow line while the level of the accumulated fluid upstream of the flow meter is stable.

10. The apparatus according to claim 9, further comprising a differential pressure transducer for measuring a static head of the fluid at an inlet of the flow meter to determine an accumulation of the fluid upstream of the flow meter.

11. The apparatus according to claim 9, further comprising a holding volume located upstream of the flow meter,

wherein the fluid accumulates in the holding volume when the flow control valve is operated, and wherein the differential pressure transducer is configured to measure a static head of the accumulated fluid by measuring a differential pressure across the holding volume.

12. A system for measuring flow of a fluid, comprising:

a chamber pressurized by a pressurizing medium;

a fluid feed line for supplying a fluid to the chamber;

one or more vents connected to the chamber for venting a first portion of the fluid from the chamber;

a drain line connected to the chamber for draining a second portion of the fluid from the chamber, wherein the drain line contains a multi-phase flow comprising a first phase defined by the fluid and a second phase defined by the pressurizing medium;

a first flow meter for measuring flow of the fluid at the fluid feed line;

a second flow meter for measuring flow of the fluid in the drain line;

a flow control valve located downstream of the second flow meter on the drain line; and

control means for controlling a position of the flow control valve,

the control means being configured for moving the flow control valve toward a closed position such that the fluid accumulates upstream of the second flow meter, and modulating a position of the flow control valve until a level of the accumulated fluid upstream of the second flow meter is stable; and

wherein the second flow meter is operable for measuring flow of the fluid in the drain line while the level of the accumulated fluid upstream of the second flow meter is stable.

13. The system according to claim 12, further comprising means for determining the second portion of the fluid that is vented from the chamber by subtracting the flow of the fluid measured by the second flow meter from the flow of the fluid measured by the first flow meter.

14. The system according to claim 12, wherein the chamber is gas turbine bearing chamber.

15. The system according to claim 14, wherein the fluid is a lubricating fluid for the gas turbine bearing chamber.