HENRY GOMES Metering Consultant SGS Kuwait

Transcription

1

2

3 HENRY GOMES Metering Consultant SGS Kuwait Born on Aruba (Carribean) in 1963 School and College in the Netherlands Resident in Romania - Bucharest Mechanical Engineer (3 years) at Stork Instrument Engineer (7 years) at MW Kellogg Metering Engineer (17 years) at Polar Systems / Imtech Systems Metering Consultant at SGS Kuwait

4 Liquid Ultra-Sonic Flow Measurement Commissioning and Troubleshooting Sharing experience regarding commissioning and trouble shooting of Ultra-sonic Flow measurement in condensate service. There will be two examples, troubleshooting of an Ultra-Sonic flow measurement with homogeneous fluid and one with non-homogeneous fluid.

5 Commissioning Tasks Commissioning is the process by which an equipment, facility, or plant (which is installed, or is complete or near completion) is tested to verify if it functions according to its design objectives or specifications. After mechanical completion to check all aspects of the installation and make sure that the installation phase has been finished. Check all fiscal parameters in the system (calibration certificate) Introducing hydro-carbon in to the meter runs Verify whether the signals received from the field are corresponding with the expectations, and solve any problem related to this. Internal tests Performance test(s) with beneficiary Hand-over to beneficiary

6 Components and Equipment Gas-Condensate-Water Separator Ultra-Sonic Flow Meter Run Control Valve for Condensate Control Valve in Water Outlet

7

8 3-Path Ultra-Sonic Flowmeter Electronic Housing Pipe Spool Transducer pairs (FTTB): Path 2 (measuring positive direction) Path 1 (measuring negative direction) Path 3 (measuring positive direction) The horizontal path s are placed above each other, to determine the flow profile in the spool.

9 Principle of Ultra-Sonic Flow Measurement There are three basic measurements: TBA: Time between transmit and receive from sensor A to sensor B TAB: Time between transmit and receive from sensor B to sensor A LAB: Length between sensor A and sensor B Ultra-sound is used to determine the time, TBA and TAB The length between the two sensors is determined in the factory, using high pressure purified nitrogen, from which the VOS is physically known.

10 Velocity of Sound Velocity of sound is a measurement of each sensor pair, which is available for review. For our application (separator of wet gas) the following ranges are applicable: VOS Lower than 500 m/s: VOS Between m/s: VOS Higher than 1400 m/s: Gas Condensate Water Note: These VOS ranges depends highly on the temperature of the fluid, and this needs to be verified in each system. The fluid needs to be homogeneous.

11 Powering the Ultra-Sonic Flow Meter Powering of the flow meter was done with the control valve at 10% open position to have a flow inside the line. On the display of Ultra-Sonic Flow Meter was indicated: 0 Bms (which means zero valid path s) VOS 1000 m/s Flow m3/hr (no measured flow rate)

12 Troubleshooting the Ultra-Sonic Flow Meter with homogeneous fluid The flow meter has a communication port, RS485, with MODBUS communication, and with the service application from the manufacturer or custom build SCADA, the measurement of each individual path can be monitored and logged. Here is an example of the manufacturer application. Each individual path has no VoS and also no Velocity of Fluid. First thought is that there is a problem with the power supply.

13 The next morning It was decided to close the control valve and continue the next day. The result was 3 valid path s, but a high velocity of sound, which was indicating water inside the flow meter. The negative flow indication was created from flow meter specific parameters inside the flowmeter.

14 Ultra-sonic flow meter did not measure condensate After opening of the control valve there was water flow, until condensate was introduced in the meter run, and the measurement became invalid again. This whole situation was repeatable: Water: All 3 paths s are valid, with a VOS of ~1430 m/s, measuring flow rate Condensate: No valid path s, VOS blocked at 1000 m/s, no flow rate. It was time to ask support from the manufacturer. Screenshots were send by to the manufacturer.

15 Condensate Velocity of Sound and Firmware Communication with manufacturer: Line density of the condensate: 703 kg/m3 (VOS 990 m/s) Design conditions density min. 750 kg/m3 (VOS 1050 m/s) After calibration the package was not installed for 1.5 years, and during this time a new reservoir was introduced with a lighter condensate than design. The firmware in the ultra-sonic flow meter had one specific feature: VOS filter on minimum 1000 m/s to reduce the noise at low flow rate, which blocked the measurement of condensate. With this firmware it is not possible to measure the condensate of 703 kg/m3 with a VOS of 990 m/s.

16 Firmware replacement To replace the firmware only one possibility: Service engineer from manufacturer. This seems impossible at that time and location, and it was decided to send back the electronic board to the manufacturer. The VOS filter was removed, and after the problem was solved, and measurements all measurements were valid.

17 Trouble shooting flow dropouts There was a claim from the beneficiary about flow dropouts during normal operation. Next slides shall show: Charts with GVFR, VOS path 1, VOS path 2 and VOS path 3

18 Chart 1 Flow Dropouts

19 Chart 2 Flow Dropouts

20 Flow dropouts Diagnose The following possibilities were to be investigated: Power supply stability Earthing Gas in Condensate (flashing) which could happen after a pressure drop (Flow conditioner!!) Water in Condensate All of the above possibilities were investigated at site. The water in condensate investigation is explained in the following slides.

21 Closing Water Control Valve To test whether the water slug is the problem, the water control valve on the separator is closed to 0%. This will build-up water to overflow into the condensate section and entering into the meter run.

22 Water in Condensate Close Water Control Valve

23 Water in Condensate Invalid Meas. on Path

24 Water/Condensate is an inhomogeneous fluid The water in condensate is an inhomogeneous fluid which makes the ultra-sonic path measurement invalid. To restore the situation the water control valve on the separator is opened.

25 Water in Condensate Valid Meas. on Path

26 Investigation It was observed that the behaviour of the flow meter, with flow dropouts, was similar to the ones claimed by the beneficiary. Subsequently, the functionality of the level controller on the separator was investigated. It seemed that the interface level measurement on the water/condensate side was malfunctioning, and the operators were controlling the water draining manually. Taking more care with the water draining solved the problem.

27 Summarized Commissioning means dealing with the problems related to the process, the design and the operation of a metering system. In many cases it s about finding the prove that the problem is not related with the metering skid but with the process. The ultra-sonic flow meter is an advanced measurement, and gives more information than a conventional turbine flow meter. This information is considered very useful when it comes to commissioning. In this presentation there were examples where mainly the Velocity of Sound used to find the source of a problem, but there are many more parameters which are being measured by the ultra-sonic flow meter and which can be used for troubleshooting or fine-tuning. The challenge in commissioning will always be to understand the process and these parameters, and find the correlation between them.

28 Questions..