Background - Aquisition and Restart

In August 2003, CES acquired an idle 5.5 MW_e biomass plant from The AES Corporation. The power plant (Fig 1) is located in Kern County, CA, approximately 18 miles north of Bakersfield at the Kimberlina Road exit. Due to air quality restrictions, the facility had been out of service since 1986 but was maintained in very good mechanical condition.

Figure 1 - Kimberlina Power Plant (KPP), Sept. 03

Initially this plant was used as a demonstration facility for CES' 20 MW_th gas generator operating on natural gas and pure oxygen (Fig 2). Subsequently, the facility has been used to demonstrate the gas generator on various alternative fuels including gas mixtures that simulate syngas derived from coal- and bio-mass gasification, glycerin (a by product of bio-diesel), and MSAR™ (Multiphase Superfine Atomized Residue, Quadrise Canada Corp.) a stabilized emulsion of heavy petroleum refining residuum in water.

Figure 2 - Gas Generator at Kimberlina Test Facility

During the first 18 months, CES upgraded the plant's existing subsystems to support electrical power generation with the CES gas generator. Major upgrades and improvements to plant subsystems included a natural gas compressor, oxygen supply system, feed water pump, and a new condenser for the steam turbine. All major systems were commissioned by late February 2005.

Natural Gas System

A new high-pressure natural gas system was installed and commissioned in early Sept 04. It included a natural gas metering station and gas compressor skid (Fig 3) with ancillary pressure regulating/relief valves and a filter.

Figure 3 - Natural Gas Compressor Skid

Oxygen System

Installation of an oxygen supply system began in Aug 04, and following extended testing, was commissioned in Nov 04. Figure 4 shows the oxygen supply system (cryogenic storage tank, cryo-pump, vaporizer, accumulators, and controller), in operation during a 10,000-sec gas generator test in December 2004.

The 11,000 gallon oxygen system receives liquid oxygen by truck, pumps the liquid to high pressure, vaporizes it, and supplies gaseous oxygen under high pressure to the CES gas generator. The oxygen system is surrounded by security fencing, cameras, and a fire detection system.

Figure 4 - Oxygen Supply System

Feed Water System

A new feed water system was installed to deliver high pressure, de-ionized water to the gas generator. The system included a high-pressure feed water pump (Fig 5), pressure regulating controls, and de-mineralized feed water tank, with associated piping and valves. The feed water system was commissioned Aug 04.

Figure 5 - Feed Water Pump

Condenser and CO₂ Extraction System

A new condenser (Fig 6), a liquid ring vacuum pump-(RVP, Fig 7) and connecting piping were installed in Jan 05. The new stainless steel condenser and LRVP condense the steam and remove non-condensable gas (primarily CO₂) from the turbine exhaust. The condensate is polished with ion exchange resins and recycled to the gas generator, permitting sustained generation and export of electrical power to the grid. The nearly pure CO₂ captured from the turbine exhaust was vented to the atmosphere during the plant demonstrations.

Figure 6 - New Condenser

Figure 7 - Vacuum Pump

Condensate System

The condensate system was rebuilt to include a new stainless steel (SS) condensate pump, all new SS piping and re-circulation lines, a condensate cooler, and a SS filter (Fig 8). Feed water (recycled condensate) polishers (Fig 9) were installed to remove contaminants.

Figure 8 - Condensate Pump, Cooler and Filter

Figure 9 - Condensate Polishers

Package Boiler

A package boiler (Fig 10) was added to provide a preheating capability for the existing steam lines and turbo-generator. This small boiler unit preheats these plant components to prevent the condensation of acid condensate upon startup. It was commissioned in Dec 04.

Figure 10 - Package Boiler

Safety and Security Systems

Plant safety and security systems were added to provide upgraded plant protection. These systems included natural gas and oxygen detectors for the gas generator, an IR/UV fire detector for the gas generator, video monitoring and recording systems to view the natural gas compressor skid, the oxygen supply system, the gas generator system, and the entrance gate. Fencing was also added to restrict access to the oxygen supply and gas generator systems to authorized personnel.

Turbo-Generator

An existing 5.5 megawatt Elliott steam turbine (Fig 11) is driven by the CES gas generator (Fig 2) to generate electrical power. During the build-out of the new plant subsystems, the turbo-generator was inspected and serviced. In late June 2004, it was tested using a portable steam boiler and electrical load. The turbo-generator was brought to synchronous speed using drive gases from the CES gas generator in late Dec. 2004. In late Feb. 2005, it was synchronized with the electrical grid using the CES gas generator and exported minimal power to the grid. Substantial power began flowing to the grid on Mar. 15, 2005.

Figure 11 - Existing Turbo-Generator

Gas Generator Durability Demonstration

Durability testing of CES' 20 MW_th oxy-fuel gas generator (GG) operating on natural gas was initiated following the reconfiguration of the Kimberlina Power Plant and commissioning of the new subsystems (Fig 12). The durability tests were performed over a 13-month period from late Feb. 05 to late Mar. 06. Over the course of those tests, the GG was started ~300 times and accumulated 1,333 hours of operating time. The duration of the individual test runs ranged from less than 1 minute to 105 hours. Power levels ranged from ~ 4 to 17 MW_th during 1,333 hours of GG operation. Power was exported to the electrical grid at power levels from 0.5 to 2.7 MW_e during 141 runs encompassing 1,243 hours of GG operation.

Representatives of two major insurers of power plant equipment toured the Kimberlina plant and reviewed the operating records of the GG system (number of starts, operating hours, shutdown circumstances, maintenance experience, and inspection results). Based on the tour and inspection, the insurers declared that the GG system is insurable, an independent verification that the GG system poses no unusual risk in a power plant.

Figure 12 - Kimberlina Power Plant, Jan. 06

Details of this demonstration program are publicly available in a report to the California Energy Commission (Clean Energy Systems, Inc., 2006, Durability and Reliability Demonstration of a Near-Zero-Emission, Gas-Fired Power Plant, California Energy Commission, Publication CEC 500-2006-074).

Gas Generator Demonstration on Alternate Fuels

The Kimberlina Power Plant continues to be used to perform demonstrations of CES' high-pressure oxy-fuel power generation technology using natural gas for interested parties. However, increasing emphasis is being focused on test demonstrations with alternative fossil- and bio-derived fuels.

Exploratory tests have been performed with the 20 MW_th GG (4-in. ID unit) in which glycerin (a by-product of bio-diesel production) has been co-fired with natural gas. These exploratory tests indicate that CES' technology can be used to effectively dispose of this low-value bio-fuel by-product with complete CO₂ capture. If the captured CO₂ were sequestered, the generated power would represent a "negative-carbon-balance" power cycle, i.e., a net removal of CO₂ from the atmosphere.

In September 2005, the DOE awarded CES a contract to evaluate and develop a coal-based oxy-syngas combustor for zero-emissions power systems. As part of Phase 1 of the project, CES modified the Kimberlina Power Plant for operation on simulated coal-derived syngas. The two major tasks were: (1) the installation of a blending station to provide up to 5 MW_t of simulated syngas and (2) the fabrication of an oxygen/syngas/water injector and its installation in the Kimberlina combustor (Fig 13). The simulated syngas, which comprised mixtures of CO, H₂, CO₂, N₂, and CH₄, represented clean syngas produced in a pressurized O₂-blown gasifier operating on a high-sulfur eastern U.S. bituminous coal. Gases were supplied by tube trailers and a liquid CO₂ Dewar (Fig 14).

Figure 13 - Installed Syngas Injector

Figure 14 - Kimberlina Power Plant, July 06

CES also conducted combustion tests with simulated hydrogen-depleted syngas. The latter fuel represents unshifted syngas from which most of the hydrogen is removed for sale as a by-product. This option may be particularly attractive if the co-production of hydrogen is desired, while still providing a fuel source for zero-emission onsite power generation. In these tests, which were completed in September 2006, the 20 MW_th GG (4-in. ID unit) was successfully operated on both simulated syngas and hydrogen-depleted syngas at power levels of up to 4.7 MW_t, and pressures of up to 335 psia (23 bar). The duration of each test was approximately 2 hours, which was limited by the capacities of the CO and H₂ tube trailers.

These successful tests and the well demonstrated use of natural gas indicates that CES' high-pressure oxy-fuel technology can also be readily applied to other gas mixtures such as biomass-derived syngas, landfill gas, bio-digester gases, refinery off-gases, a variety of low-heating-value gaseous fuels, and hydrogen-rich fuels.

In late 2006, exploratory tests were conducted in the 20 MW_th GG (4-in. ID unit) on MSAR™ (Multiphase Superfine Atomized Residue, Quadrise Canada Corp.), a stabilized emulsion of heavy petroleum refining residuum in water. Based on the early encouraging test results of co-firing MSAR™ with natural gas, more extensive testing was undertaken in 2007 to minimize natural gas usage, to more fully characterize the combustion products, and to define cleanup issues posed to zero-emissions combustion systems by the sulfur, ash, and heavy metals in MSAR™.

A mobile MSAR™ Manufacturing Unit (MMU) was installed at the Kimberlina Power Plant to support extended-duration testing (Fig 15). Other additions to the facility include a caustic scrubber system to remove SO_x from the CO₂ exhaust stream (Fig 16) and a condensate cleanup system that includes a reverse osmosis unit (Fig 17), filters (Fig 18), and polishers (Fig 19).

Facility Enhancement for Large-Scale Testing

CES has designed and is fabricating a 12-in. (30-cm) ID gas generator system nominally rated at 170 MW_th on natural gas fuel (Fig 20). A J79 gas turbine is also being modified to operate directly on the drive gases produced by the 12-in. gas generator. The modified turbine is depicted in Figure 21. These components will be installed and tested at the Kimberlina facility starting early in 2008 at power levels up to 80 MW_th.

Figure 20 - CES' 170 MW Gas Generator

Figure 21 - CES' Modified J79 Gas Turbine

To accommodate testing at increased power levels, the facility's supply and support systems are being enhanced. The upgrades to the natural gas supply system include the addition of a natural gas booster compressor, high-pressure accumulators, flow controls, and supply line to provide increased flow capability. The oxygen supply system upgrades are similar to those for natural gas except a booster compressor is not needed. The upgraded water supply system includes additional water storage and a new feedwater pump (Fig 22).

Figure 22 - Feedwater Pump

Initial tests will involve only the gas generator. The drive gases will be pressure-regulated, attemperated, and vented to the stack. In subsequent tests the gas generator will drive the modified J79 gas turbine (Fig 23) that will be loaded by an air dynamometer via a gear box. In the latter case, the exhaust gases from the gas turbine will also be pressure-regulated, attemperated, and vented to the stack.

Figure 23 - Gas Generator and Modified J79 Gas Turbine