When a coal-fired power plant was experiencing startup problems with a boiler-feed pump, the plant wanted to fix the issue during an overhaul. A John Crane 48VBF seal upgrade improved the boiler feed pump startup and saved the plant more than US$20,000 by eliminating the need for a separate cooling system.
A 30-year-old, coal-fired power plant in Colorado, USA stopped using a startup boiler feed pump (BFP) in the late 1990s; the plant was experiencing numerous BFP failures and low reliability because the pump was oversized. Improper minimum flow caused large flow transients and spraying water from leaking packing. Poor steam quality and volume forced ‘slingshot’ starts. BFP pumps and turbines were damaged during the slingshot startup process. The plant wanted to fix the BFP issue during overhaul of the startup BFP and generators.
Bypassing proper BFP startup put undue loads on the main BFP turbines and pumps and the out-of-service BFP jeopardized safe and successful plant startups. Plant concerns and improvement goals were discussed with a John Crane Pump Repair Alliance Partner. A John Crane 48VBF, single-cartridge, stationary head O-ring pusher seal was put into the pump service provider’s overhaul recommendation. Power plant engineers considered another seal, but were convinced 48VBF was the right solution. In May 2017, the plant had its first successful BFP startup in two decades.
Boiler feedwater pumps provide the required flow and pressure for on-site and utility-scale power generating facilities around the world. The plant uses the BFP to pump 325°F feedwater that can flash into steam, potentially causing personal injury. The original BFP was supplied with outdated packing technology that constantly leaked and sprayed water and constant BFP maintenance interventions caused unsafe working conditions. The plant had a longtime, trusted relationship with a John Crane Pump Repair Alliance Partner and John Crane was able to demonstrate the benefits of the 48VBF. The seal was chosen for BFP upgrade because of the technology that was best suited to meet the plant’s performance goal.
John Crane and the pump repair partner determined the improper packing used was a safety hazard. Due to John Crane’s close relationship with the pump repair partner, the customer trusted their suggestion to incorporate the 48VBF seal into the retrofit design. The 48VBF pusher seal used on the startup BFP eliminated the need for a cooler support system, reducing costs from additional water consumption.
The 48VBF greatly reduced the water usage needed with the packing. Commissioned in May 2017, the BFP upgrade took place during a planned outage that included overhauling the boiler feeder generators.
There have been many beneficial results: the power plant can now seal hot water above the atmospheric boiling point while minimizing BFP leakage, mean time between repairs (MTBR) has been extended and outages have been avoided. Now, the plant is saving more than US$20,000 by eliminating the need for a separate cooling system, at the same time addressing worker safety concerns from feedwater flashing into steam.
Following the first successful BPS startup in 20 years, a plant manager said, “I’ve never seen this pump not spray water everywhere!” The power plant has committed to more 48VBF upgrades in the future. •
John Crane is a global leader in rotating equipment solutions, supplying engineered technologies and services to process industries. The company designs and manufactures a variety of products including mechanical seals and systems, couplings, filtration systems and predictive digital monitoring technologies.
John Crane customer service is accessed through a global network of more than 200 sales and service facilities in over 50 countries. Fiscal year 2017 revenue was more than US$1.1 billion.
John Crane is part of Smiths Group.
This application story was first published in the March 2018 issue of World Pumps magazine. Sign up for your FREE subscription to World Pumps here