Clamp-On Application for High Pressure Ethylene in EVA (Ethylene Vinyl Acetate) Production
Summary
Jiangsu Sierbang Petrochemical Co. Ltd in China produces Ethylene Vinyl Acetate (EVA), a copolymer resin valued for its lightweight and excellent foamability. The process is part of a polyethylene plant and requires high-pressure ethylene from reciprocating compressors, with the flow rate on this line needing to be accurately measured to keep the EVA produced within specification — too low a flow rate leads to an incomplete reaction. With pressure inside the pipeline reaching up to 200 MPa, flow meters that require cutting the pipe were not a safe option. Uncertain that a clamp-on solution could deliver the required accuracy at such pressure, the customer requested a field demonstration from the Panametrics team.
| Fluid | Ethylene gas |
|---|---|
| Pipe | 121 mm x 35 mm (4¾” x 1.38″), Carbon Steel |
| Process Temperature | 20 °C (68 °F) |
| Process Pressure | 195 MPa (28,282 psi) |
| Fluid Sound Speed | 1,679 m/s |
Benefits:
- Low maintenance
- No pressure drop
- No interruption to operations
- Safe measurement
- Long-term stability and drift-free characteristics
Challenge
The application was for a DN100 (4″) line with a 35 mm wall thickness — the first time a Panametrics clamp-on flow meter had been used on such a thick 4″ gas line. There was concern that signal strength and SNR would be too weak, as the acoustic signal dissipates further outside a thicker pipe wall, risking measurement loss. The Panametrics team nonetheless carried out the demonstration to prove the quality of the technology under these extreme conditions.
Solution
After reviewing the site-specific process parameters, Panametrics confirmed its meter and transducer recommendation. At these working conditions, ethylene is in a supercritical state with a sound speed approaching 1,700 m/s — so Panametrics recommended its TransPort PT900 with CRS 401 transducers for the demonstration, a liquid meter design, fitted only with a CFG clamping fixture (intended for gas measurement) to ensure accurate transducer positioning. On-site installation went smoothly and testing was highly successful: the flowmeter displayed a sound speed of 1,679 m/s, matching the theoretical sound speed of ethylene at 20°C and 200 MPa. Impressed with the result, Jiangsu Sierbang Petrochemical has since adopted Panametrics’ clamp-on flowmeter technology, and several other customers are now requesting demonstrations of the same solution on thick-walled high-pressure gas lines.
Clamp-On Ultrasonic Flow Meter Panametrics TransPort PT900
Panametrics TransPort PT900Source: Panametrics Application Note PANA103AN (panametrics.com) — © Panametrics LLC. Localized and prepared in cooperation with INTECH CONTROL, official Panametrics representative for Slovakia and Hungary.