The gas/liquid separation test facility was designed and constructed in the Process System Engineering (PSE) Flow Laboratory at Cranfield University, as shown in Figure 4-1. The test facility is a fully instrumented facility which includes an Inline Separator (I-SEP), a Pipe Separator (Pipe-SEP), a High Separator (Hi-SEP) and a Jet Pump (J- PUMP) test loop. In the present study, the test loop only including the Pipe-SEP and Hi-SEP was used.
Figure 4-2 shows a schematic representation of the apparatus used in the experiment. The apparatus consists of sections for fluid supply, metering, testing, control, and data- acquisition.
4.2.1 Fluid Supply
Water is stored in a tank of 3.5 m3capacity, as shown in Figure 4-3. Water is pumped to the test section by a multistage pump, which has a maximum capacity of 36 m3/hr. Water from the pump is controlled by a by-pass line, where part of the water is recycled back to the tank. After passing through the metering system, the water flow is taken to the mixing point, where it is combined with gas flow and passed to the test section.
Figure 4-3 Water tank Figure 4-4 Air supply
Air is supplied from a Screw Engineering Compressor (SEC), as shown in Figure 4-4. The compressor has a maximum air flow rate of 280 m3/hr Free Air Delivery (FAD) @ 7 bara. An air receiver with 2.5m3 volume is connected after the compressor to reduce the pressure fluctuation from the compressor. From the receiver, air flow goes to the gas meter for metering, and then the gas goes to the mixing point. After mixing, the water and air flow through a 25 m long pipeline (50 mm in diameter) to the testing section. The 25 m long inlet pipeline allows the inlet flow fully developed.
4.2.2 Instrumentation
The flow meters are installed on single-phase flow lines before mixing point and after separation. Water flow is metered by a Promag 50 electromagnetic flowmeter (Endress+Hauser). The electromagnetic flowmeter has a HART output that can be connected to the Data Acquisition System (DAS) via a BNC connection. Gas flows are metered by V-cone flowmeters (McCrometer) and vortex meters. The differential pressure transmitter measures the differential pressure signal. At the gas metering point, temperature and pressure are measured to calculate the actual volumetric flow rate of the gas that enters the test section. All data from the instrumentation of the test facility is recorded by the DAS. Details of the instrumentation for the test loop have been given in Table 4-1.
Table 4-1 Test loop fluids instrumentation
Tag Description Details Range
FM01-G Inlet gas flowmeter Vortex meter 0.02 to 0.2 N-m3/s FM05-G Outlet gas flowmeter (high) V-Cone meter 0.02 to 0.2 N-m3/s FM06-G Outlet gas flowmeter (low) V-Cone meter 0.005 to 0.05 N-m3/s FM02-L Inlet liquid flowmeter MagFlow meter 0 to 10 l/s
FM03-L Outlet liquid flowmeter (low) MagFlow meter 0 to 4.9 l/s FM04-L Outlet liquid flowmeter (high) MagFlow meter 0 to 12.5 l/s PT01 Inlet gas pressure sensor Druck (PMP1400) 0 to 6 bara PT04 Pipe-SEP inlet pressure sensor Druck (PMP1400) 0 to 6 bara PT05 FM05-G pressure sensor Druck (PMP1400) 0 to 4 bara PT06 FM06-G pressure sensor Druck (PMP1400) 0 to 4 bara
PT10 Hi-SEP pressure Druck (PMP1400) 0 to 6 bara
PT11 Pipe-SEP pressure Druck (PMP1400) 0 to 6 bara TT01 Inlet gas temperature sensor RS thermocouple -200 to 800°C TT02 Mixture temperature sensor RS thermocouple -200 to 800°C DP04 Hi-SEP differential pressure
sensor
Druck (PMP4110) -70 to 70 mbara DP07 Pipe-SEP differential pressure
sensor
4.2.3 Test Section
The test section consists of three separators that are made of Plexiglas, namely the Pipe- SEP, Hi-SEP, and Under Flow Knock-out Vessel (UF KOV). The Pipe-SEP is a vertically installed pipe with 150mm in diameter and 1600 mm in height, The Pipe-SEP is mounted with a 50 mm tangential inlet, as shown in Figure 4-5. The upper part of the Pipe-SEP extends approximately 900 mm. There is an FER and gas ASB near the top. The ‘L’-shaped gas out section is fitted inside the separation chamber and is connected through a horizontal pipe to the upper inlet of the Hi-SEP, as shown in Figure 4-2. The lower part of the Pipe-SEP is 700 mm high. The ‘L’-shaped liquid out section, which is coupled to a liquid ASB, can discharge the liquid to the lower inlet of the Hi-SEP or to the UF KOV. In the experiments from this PhD work, the liquid was discharged to the UF KOV for further separation and measurement.
Figure 4-5 Schematic of the Pipe-SEP
The Hi-SEP is geometrical similar to the Pipe-SEP, and is a 2400 mm tall separator with an inner diameter of 204 mm. The Hi-SEP can either be connected with the Pipe- SEP in series through its dual tangential inlet to improve separation performance, or can be used for enhancing measurement. In the experiments from this PhD work, only the
Pipe-SEP was tested, while the Hi-SEP was used to capture and measure the LCO in the gas outflow of the Pipe-SEP.
The UF KOV is a vertical gravity separator, with 500 mm inner diameter and 2400 mm high. The function of UF KOV is to knock out the gas bubble that trapped in the liquid outflow of the Pipe-SEP. This enables the GCU to be measured accurately using the single phase meter.
4.2.4 Control System
The control system is consist of 1) a control valve on the Hi-SEP liquid outlet to maintain the liquid level; 2) a backpressure valve on the Hi-SEP gas outlet to maintain a steady operating pressure; 3) a pressure relief device; 4) a control logic worked under a Labview interface.
The liquid control valve (LCV) is located in the Hi-SEP liquid out section and the gas control valve (GCV) at Hi-SEP gas out section, as shown in Figure 4-6 and Figure 4-7, respectively. The design of the control system is discussed in section 4.3.
Figure 4-6 Liquid control valve Figure 4-7 Gas control valve
4.2.5 Data-Acquisition System
Data from the compact gas/liquid separator facility is acquired by a dedicated PC-based Data Acquisition System (DAS). This system includes a series of built-in signal conditioning units, which collect and transfer experiment data to computer with the (SCB-68) parallel port multiplexer. The gathering of information and displaying based on a real time principle is achieved by the ‘Virtual Instrument’ Version 7 (Labview) and
DAS hardware under Windows XP-Professional operating system for control and operation purpose.