The Challenge: Change of scope...
Work started on this project based on dust removal scope of work, on a 24” x 27km gas pipeline from Point of Ayr to Connah’s Quay Power Station. The scope of work changed from dust removal to liquid removal, due to concerns of high levels of liquid in the pipeline.
After 3.5 months of preparation, beginning in winter 2010, the site setup was finally ready in early spring 2011. Two dual redundancy gas filtration systems were tied-in to the gas receiving end at Connah’s Quay Power Station, which is one of the largest Combined Cycle Gas Turbine (CCGT) in the UK, at 1420MW capacity.
A lot of preparation/pre-engineering works were required, due to concerns regarding potentially large quantities of dust, which could foul the downstream process, leading to a shutdown of the power plant; which did actually happen in summer of 2000, during an ILI campaign.
Just as work was about to begin in early spring of 2011, the client stopped the project, due to concerns of high levels of liquid in the pipeline, estimated at about 30m3. The scope of work changed from dust removal to liquid removal, and work started almost immediately, in order to have the ILI campaign completed by year-end.
After 6 months, the design of the temporary liquid handling system was approved, with a lot of process safety features (pressure relief, flow control using orifice plates, temporary silenced vent system, temporary liquid storage, etc) in place, based on requirements from the client.
Our HP 2-phase separator was tied-in to the pig receiver and the downstream process, in order to be able to contain all the liquids/sludge (consisting mainly of condensates & MEG), while the clean/dry gas flowed to the downstream process.
All the tie-in pipework were measured-up by the project lead and fabricated using a client-approved local fabrication company, in order to ensure mechanical compliance.
A total of 4 pig runs were performed by the ILI contractor, which brought out about 9m3 of liquids. The 1st pig run brought out the majority of the liquids, at 7.5m3, and the subsequent run brought out another 1.5m3. Runs # 3 & 4 were relatively liquid-free, indicating that all the pipeline liquids were successfully removed.
The entire project took 3 weeks to complete, and was completed in mid-Dec 2011, to the satisfaction of all partied involved.