The El Segundo Energy Center LLC unit of NRG Energy (NYSE: NRG) said in a brief Feb. 18 notice filed with the California Energy Commission that it is freezing two amendment applications for the latest phases of a gas-fired repowering at an existing plant.
“El Segundo Energy Center LLC (‘ESEC LLC’) submitted two Petitions to Amend (‘PTAs’) the El Segundo Energy Center (‘ESEC’) on April 23, 2013 and December 23, 2015,” said the notice. “This letter serves as notice that ESEC LLC hereby suspends the PTAs for confidential internal business reasons. Notwithstanding the suspension affected by this notice, ESEC LLC will inform the Commission within six months whether it intends to pursue modified amendments or to withdraw the respective PTAs in their entirety.”
Looking at the suspended PTAs:
December 2015 application
Under the December 2015 PTA, the company proposed to make modifications to specified equipment licensed under a July 2010 commission decision. This petition to modify entailed the replacement of thermal insulation on steam turbine (ST) casings and installation of weatherization enclosures (i.e., ST weatherization enclosures) over the ESEC steam turbines, located at 301 Vista Del Mar, El Segundo, California.
The proposed modifications consisted of the replacement of thermal insulation on ST casings and installation of ST weatherization enclosures on Units 6 and 8 at the ESEC site. The weatherization enclosures are proposed improvements suggested by Siemens, the ST manufacture designer. The weatherization enclosures are necessary due to operation and maintenance issues associated with the lengthy removal and replacement requirements of spray on thermal insulation on the ST casings. The originally installed spray on thermal insulation was designed to provide thermal insulation to the ST casing to help maintain consistent temperature across the ST rotor and prevent exposure of ancillary operational equipment and sensor systems to rain and corrosive marine environment.
The ESEC units consist of two 1×1 (one gas turbine generator (GTG) and one HRSG and ST generator (STG)) combined cycle power blocks. The STs were designed and installed with a spray on thermal insulation and hard shell (plaster-like) coating on the exterior of the ST casing that also encapsulated numerous valves, electric heating mats, and various sensors.
ESEC project online date was in August 2013. During 2014 the ST casing electric heater mats began to fail prematurely. The failed heater mats were scheduled to be replaced during the 2015 spring outage. During the outage the hard shell spray on thermal insulation was removed. The removal process of the thermal insulation coating damages the coating and requires the coating be reinstalled, a process that takes several days to accomplish. The thermal spray on coating also requires several days of “curing” before the ST could be placed back into service.
Due to the difficulty with the removal process of the thermal insulation, maintenance issue with the heater mat, and the long cure time for reinstallation of the thermal insulation a decision was made in consultation with Siemens to reinstall the heater mats directly on the ST casing; covering them with removable insulation pads. The heater elements and the removable insulation pads are not recommended for outdoor use. Rather than install the hard shell insulation again, ESEC planned to install the weather protection enclosures, which will improve future maintenance requirements and reduce the duration or eliminate potential outages associated with replacement/re-installation of the hard shell material.
April 2013 application
Chief among the changes proposed in this application is the replacement of two once-through-cooled boiler units, Units 3 and 4, with modern and efficient, dry-cooled, natural-gas-fired combustion gas turbine units. This change will eliminate the use of ocean water for once-through cooling at the facility. The proposed changes will also upgrade and improve the ESEC’s existing and approved site infrastructure, and provide fast start and dispatch flexibility capabilities to support southern California grid load balancing and renewable energy integration, and implement improvements to coastal access.
Specific changes proposed through this PTA included:
- Shutdown and demolition of Units 3 and 4;
- Removal and remediation of existing ESEC retention basins;
- Change in location for the permitted (but not yet constructed) administration building to a lower elevation;
- Construction of a new, combined administration, maintenance, and operations support building;
- Modifications to existing site access; and
- Improvements to beach access.
The following new major equipment would be installed under this amendment;
- One NRG fast start combined-cycle unit (CC Fast), rated at 325 MW (net), incorporating a General Electric 7FA.05 natural gas turbine;
- Two Rolls Royce Trent 60 DLE ISI, rated at 55 MW/unit net, consisting of advanced aeroderivative simple-cycle gas turbines; and
- One Cleaver Brooks 36 MMBtu/hr auxiliary boiler.