When pumping gas becomes possible!
Last year, Eastman contacted Egger with regards to one of its pumps which plagued them for years because it is in a high temperature (240°C) / low pressure (<1 bar or ~10 psig) service that contains water, which in turn, produces over 10% entrained gas by volume as water vapor. Fortunately, one of the rotating equipment specialists from Eastman was aware of Egger’s capabilities with multiphase liquids (liquids, solids and gas).
The first pump installed on this service many years ago was a horizontal ANSI type and was very problematic with various mechanical seal issues and excessive thermal growth causing misalignment. It was then replaced by an API vertical in-line style pump, which also had several initial design issues with erratic, periodic vapor locking which was proving to be a challenge to solve. The gas load was simply too high for the closed style impeller and casing to handle.
Egger and Eastman worked together to optimize the system’s overall design, including suction pressure, flow, head, gas concentration, gas composition, and piping sections / arrangement. The final solution from Egger was an API OH2 style pump, using Egger’s special semi-open impeller, suitable for three-phase liquids’ services (liquid, solids, and gas). This special pump hydraulic design allows, in certain working conditions, up to 25% entrained gas by volume in the liquid without any impact on the pump’s performance.
The complete case study and engineering were managed within a month, and the pump delivered from Switzerland to the US job site within three months. Since its installation in the plant, the pump is performing flawlessly with no off/class, lost production or maintenance costs.