According to the independent monitoring firm that supervises the construction of the Kemper Project clean coal power plant, the facility might not make its scheduled start date in the third quarter of this year.
The Mississippi Public Service Commission was briefed by the independent monitors from engineering firm AECOM on recent progress with Kemper at an open “work session” meeting Thursday in Jackson.
Randall Hodges, who has led AECOM’s independent monitoring team of engineers and accountants employed by the PSC since 2011, said the plant’s construction is 99 percent complete and is in the final phase, startup and commissioning. That phase is 87 percent complete, as of March 13.
“Startup progress has averaged about 1 percent overall per month over the last several months,” Hodges said. “This progress will have to improve to meet the reported operational date of third quarter of this year. Mississippi Power is reporting the end of August as their projected commercial operation date. What we’re indicating here is if they continue to progress at 1 percent per month, that’ll take 13 more months to finish.”
Any delay, the company has said, could cost it up to $30 million per month for every month the plant’s in-service date is delayed.
The independent monitor panel also detailed problems that have bedeviled Kemper during the testing of the plant’s two gasifiers, which convert lignite coal mined on site into a natural gas-like substance called synthesis gas to be burned in the plant’s electricity-generating turbines. The valves on the mechanism that feeds coal into the coal preparation area before going into the gasifiers have not been able to work effectively at the rate required for full plant operation without stoppage. Also, there were vibration issues with the gasifiers and problems with the refractory coatings that keep the 1,800 degree temperatures from burning through the metal shell and causing a possible explosion.
The plant, billions over budget and years behind schedule, is designed to turn lignite coal into a natural gas-like substance called synthesis gas that is burned in the facility’s turbines to generate electricity. The plant’s gasifier, which converts lignite to synthesis gas, is scheduled to go online in the third quarter of this year. The plant has been generating electricity on natural gas since August 2014.
One of the operational problems with Kemper lies in the paddle wheel-like rotary valves that feed lignite into the preparation area before gasification. The two gasifier “trains” that turn lignite into synthesis gas need 200,000 pounds of coal per hour apiece to fuel the turbines. The rotary valves, which have rotating vanes that slow the amount of coal going into the treatment area, have been jammed by dirt, rocks and other debris. In testing, they’ve been able to sustain only 10,000 to 20,000 pounds per hour.
The company is installing new valves in an attempt to fix the problem, according to David Mann, the AECOM technology director for oil, gas and chemicals.
The venturi scrubber system is designed to remove coal fines — defined as coal particles usually less than one-sixteenth of an inch and rarely above one-eighth inch — from coal coming from the drying system. The scrubbers are allowing too much of the coal fines to get through, which can damage filters and contaminate recovered water which is supposed to be reused by other systems.
“If this [problems with the venturi scrubbers] was to occur during normal plant operations, it would mean there would be insufficient amounts of clean, recovered water for the other process units to use that source of water,” Mann said.
Downstream from the preparation system, Gasifier A had problems with the two-stage refractory coating that keeps the 1,800-degree temperatures in the gasifier from breaching the gasifier’s shell and causing a deadly explosion. During a cold circulation test with treated sand substituted for lignite and the burners heating the gasifier slowly up to 1,200 degrees, hot spots were found by temperature measurements on the outside of the gasifier, which indicated a breach with the gasifier. The gasifier was shut down and cracks were discovered in the outer, hard-faced refractory coating, which allowed the gas and sand to erode the softer, inner refractory layer in a phenomena called rat holing. After both gasifiers’ refractory coatings were retrofitted to fix the problem, Gasifier B had the same test performed without incident.
During testing, Gasifier A was found to vibrate more than a quarter of inch, which could cause damage to the system. Anchored steel cables were used as a temporary fix before large shock absorbers were added to both gasifiers, which squelched the vibration.
The company said it still plans to put Kemper in service in the third quarter of 2016.
“Mississippi Power appreciates the independent monitors’ review of the Kemper project and their presence onsite throughout construction,” said Mississippi Power spokesman Jeff Shepard. “As you heard today, monthly on-site meetings with the Public Utilities Staff as well as their respective IMs have been held — covering everything from schedule to cost changes. That full transparency will continue throughout the project, and we welcome the review.
“Mississippi Power believes in the Kemper project, and we are working hard to bring the full project online to provide safe, reliable energy for the benefit of our customers.”