Integrated Coal Gasification Combined Cycle (IGCC)
Particulars and Results of Demonstration Testing (Overview)
IGCC demonstration tests were conducted over a period of about 3 years and 7 months, starting with ignition of the gasifier in September 2007, and continuing up to March 2011. The test was conducted according to the schedule shown below. In general, all of the initial targets were achieved.
Further tests are planned for the next two years, from fiscal 2011 through the end of fiscal 2012, to (a) respond to new issues that have arisen, and to (b) aim at continuing maturation of IGCC technology, focusing on reliability, economic feasibility, and coal-type adaptability. Our underlying plan is to tie these efforts into the smooth commercialization of these systems.
Demonstration Test Schedule
Verification Items and Particulars of Demonstration Testing
| Item | Goal |
|---|---|
| 1) System Safety and Stability |
Demonstrate safe shutdown when plant malfunctions, and safe handling of coal gas. |
| 2) Reliability | Run continuously for at least 2000 hours (equivalent to 3 summer months) to confirm reliability. |
| 3) Coal Type Flexibility |
Collect data while running coal types outside of the design specs. Data is to be used to support future commercial design. |
| 4) High Efficiency | Achieve targeted thermal efficiency, to show that system delivers the high efficiency that is said to be IGCC’s greatest advantage. |
| 5) Durability | Run for long period, then conduct overhaul inspection to demonstrate durability. |
| 6) Economy | Use operational performance as a basis for comprehensive evaluation of costs (construction costs, operating costs, maintenance costs etc.), and evaluate economic feasibility. |
1) System Safety and Stability
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Safe shutdown when plant malfunctions. |
・Simulated a malfunction and tested interlocks to confirm safe plant shutdown. |
Confirmed that system is stable.Objective accomplished |
| ・Safe handling of coal gas. | ・Ran various trials and adjustments, and confirmed that gas handling is always safe and that there are no operational errors. ・Confirmed system stability by demonstrating stable continuous operation at rated load (250 MW). |
2) Reliability of the Facility
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Run continuously for 2000 hours. (Equivalent to 3 months of summer.) | ・Confirmed stable operation over 2039 consecutive hours. | Achieved continuous-run target. Going forward, will also check durability over mid-to-long-term continuous operation.Objective accomplished |
3) Coal Type Flexibility
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Collect data while running on coal types outside of the design specs. | ・Operated plant on three different types of sub-bituminous coal, and collected operational data. ・In some cases, coal characteristics caused blockage in heat-transfer piping in the heat exchanger (SGC) downstream of the gasifier. |
Analyzed operation when using three coal types outside the range of the design specs, collecting data to be used to support future design of commercial-level facilities. In some cases, blockage occurred in the SGC heat-transfer piping downstream of the gasifier. Results made it clear that various countermeasures would be needed to prevent problems caused by different coal types. Objective accomplished |
4) High Efficiency
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Targeted thermal efficiency (Achieve LHV 42% LHV at sending end) | ・Achieved 42.9% LHV at sending end. | Demonstrated high efficiency.Objective accomplished |
5) Durability
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Run for long period, then do overhaul inspection to evaluate durability. | ・Ran 5000 hours in one year. •After running 5000 hours, conducted overhaul inspection. Confirmed that there were no critical device faults. |
Confirmed that the tested equipment has an appropriate IGCC design. Going forward, will also check durability over mid-to-long-term continuous operation.Objective accomplished |
6) Economy
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Evaluate economic feasibility based on operational performance. | ・While it seems that gasified-coal systems will have higher construction and repair costs. relative to pulverized-coal systems, we expect that they will also deliver better thermal efficiency and low fuel costs. | Based on the results, it seems quite possible that gasified coal may deliver power-generating costs equal to or lower than those for pulverized coal. Yet, it will be required to enhance precision of these systems for lower repair costs.Objective accomplished |
See more detailed test results here.
New verification items and their contents
1) Reliability
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Confirm the mid-to-long term durability of the IGCC facilities including countermeasures implemented during the past testing. | ・Countermeasures to initial stage troubles were worked well in 2011. ・Additional two countermeasures to mid-and-long term troubles were implemented. |
・Countermeasures to initial troubles were identified as effective and durable. ・Countermeasures to latest troubles were also established and effectiveness was checked.Objective accomplished |
| ・Durability of countermeasures was confirmed in 2012. ・Two countermeasures against troubles caused by long-term effects are implemented and their effectiveness was checked in the end of fiscal 2012. |
2) Coal Type Flexibility
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Establish the measures against the troubles accompanied by use of some coal types. | ・Another types of bituminous, Columbian Russian and Indonesian coals were in use and operational data were collected in 2011. ・Some coal type brought about clogging in SGC heat exchanger piping facility. |
・5 types of coal except for designed coal were applied and operational parameters adjustment was performed, which realized optimal operation in each coal type. ・Countermeasures with design and proper operation against clogging in Heat exchanger piping facility were confirmed to be effective.Objective accomplished |
| ・Another types of sub-bituminous (USA)and bituminous(Canada) coals were tested in 2012. ・Countermeasures against SGC clogging such as design improvement in SGC heat exchanger pipe facility design and operation were confirmed to be effective. |
3) Economy
| Verification Items (Overview) |
Results of Demonstration Testing (Overview) |
Evaluation |
|---|---|---|
| ・Increase in samples of maintenance and inspection results for analyzing the maintenance cost which should be compatible with conventional pulverized coal fired generation. | ・Design improvement in SGC Heat exchanger was developed in 2011. ・Prolongation of inspection period was studied. |
・It was confirmed that design improvement in SGC Heat exchanger brought about no problem and was effective measure to reduce the SGC volume. ・Appropriate period and contents for maintenance inspection were more precisely identified.Objective accomplished |
| ・Design improvement in SGC Heat exchange was partially installed and no trouble was observed in 2012. ・Prolongation of inspection period was studied. |
History of IGCC Research and Development Work
Pilot plant test
1.Overview of the Nakoso Pilot Plant Test
The Engineering Research Association for Integrated Coal Gasification Combined Cycle Power Systems (IGC Association) was founded in fiscal 1986 by a partnership among nine power companies, the Electric Power Development Co., and the Central Research Institute of Electric Power Industry, leading to the launch of the government-subsidized Nakoso Pilot Plant Project. Although gasification test began in June 1991, sustained gasifier operations were not achieved in the first attempts due to frequent slagging (i.e., adhesion and accumulation of melted coal ash) clogging the gasifier. In response, thorough modifications of the gasifier were implemented in fiscal 1994. Steady progress thereafter eventually allowed sustained operations for a period of 789 hours. Test ended in success in February fiscal 1996.
Nakoso Pilot Plant
Principal Specifications
- Scale：
- coal 200 t/day (equivalent to 25,000 kW in electric power output)
- Type：
- Gasifier–entrained bed air-blown gasification
- Organizational relationship：
- Government → NEDO → IGC Association
- Location：
- Site of the Nakoso Power Station of Joban Joint Power Company
Record of Pilot Plant Operations
(cumulative hours)
2.Record of Pilot Plant Operations
3.Results of Pilot Plant Operations Test
| System Verification | Confirmed the validity of basic technologies for an integrated air-blown gasification system consisting of a gasifier, gas cleanup system, and gas turbine. Identified various critical conditions (e.g., fuel calorific value) for an IGCC system. Identified phenomena (e.g., slagging) unique to coal gasifiers otherwise not possible with essential technologies test. |
|---|---|
| Scale up Data Acquisition |
I dentified appropriate scale up methods for the gasifier and gas cleanup system. (Implementation of scale up calls for preliminary verification of as many factors as possible.) |
| Thermal Efficiency |
Achieved initial target values for all systems. Identified need for further reductions in auxiliary power requirements to offset high power requirements relative to power generation based on pulverized coal. Tests and conceptual designs confirmed a potential efficiency (net) of over 43% over 1300°C-class advanced type gas turbines. |
| Economy | Identified a need for further reduction of construction costs because the overall cost (Price/MWh) estimated to be slightly higher than that of using a conventional pulverized coal power plant；the final goal of the development of IGCC is to meet the cost(Price/MWh)equivalent to that of a conventional pulverized coal power plant. |
| Environmental Compatibility |
Identified prospects for achieving values of 20 ppm, 20 ppm, 1 mg/m3N, or less at the stack outlet, respectively, for SOx, NOx, and dust, based on the results of operations test. |
| Coal Type Flexibility |
Confirmed the feasibility of operations with coal of Warkworth/Moura quality with the addition of a melting-point lowering agent (limestone) and oxygen enrichment, based on the results of operation test with three types of coal. |
| Operating Characteristics |
Identified the prospects of achieving a cold startup time of one day (approx.) and load-following capabilities on par with that of power generation using pulverized coal, based on results of operation test and conceptual design studies. |
| Reliability | Achieved a cumulative operating time of 4700 hours while encountering and resolving issues associated with the demonstration plant to verify the reliability of continuous operation. Acquired a body of knowledge on the durability of materials (i.e., several years or so) and other aspects of individual systems and equipment. |
ＦＳ
Feasibility Study
In fiscal 1997, comprehensive evaluations of individual types of IGCC (i.e., dry feed/slurry feed, oxygen-/air-blown gasification, dry/wet gas cleanup) were performed for factors such as reliability, thermal efficiency, environmental characteristics, economy, and other aspects, with a view to selecting the most promising demonstration plant configuration for development in Japan.
Based on the conclusions, a combination of a dry feed oxygen enrichment air-blown gasifier (tested at the Nakoso pilot plant) and a wet gas cleanup system was determined to be the best choice for a demonstration plant.
Based on the IGCC configuration selected based on these results, studies of systems and equipment specifications and of effects associated with changes in design parameters, trial designs of commercial plants, and other tasks were performed in fiscal 1998.
Major Items Studied
1)Factors related to the use of low-grade coals
2)Comparisons of various methods for supplying coal in powder form
3)Effects of CO2 selectivity of H2S absorbing solution on the IGCC system
4)Effects of the oxygen purity of air separation units on the IGCC system
5)Trial design of an IGCC commercial plant using a 1500℃ class gas turbine
Essential Technologies Research
Essential Technologies Research
During fiscal 1997 and fiscal 1998, research was performed on essential technologies for individual systems and equipment using a test facility in four areas: coal supply stabilization; scale up of the gasifier; improvements in the reliability of the gas cleanup system; and improvements in the reliability of the gas turbine system. The goal was to resolve issues remaining with the pilot plant.
1) Coal Supply Stabilization
The high-concentration transport of pulverized coal using nitrogen was tested to acquire a body of knowledge on ways to ensure a stable supply of coal and to find potential applications to demonstration plants.
2) Scale Up of the Gasifier
Forecasts for the possible scale up of the gasifier were made and pertinent evaluation tests performed using a 24 t/day gasifier test system. The test results obtained were more or less identical to the results of performance forecast simulations, suggesting a highly reliable demonstration plant was possible.
3) Improvements in the Reliability of the Gas Cleanup System
Coal gas contains carbonyl sulfide (COS). Test was performed to examine the performance and durability of the catalyst used to convert COS into hydrogen sulfide (H2). In addition, tests were performed to examine the performance of lime/gypsum methods in removing sulfur for high concentrations of SO2 and performance in removing trace impurities present in coal gas, among other aspects.
Tests of catalysts showed that certain materials might be suitable for the demonstration plant. While the results of desulfurization performance test indicated remarkably high desulfurization rates, test on the removal of impurities pointed to the likelihood of removing ammonium and other types of impurities.
4) Improvements in the Reliability of the Gas Turbine System
Evaluation-oriented studies were performed on the adhesive characteristics of deposits collecting on the blades of the gas turbine and the performance of anticorrosion coatings, clarifying the mechanism of deposit adhesion and allowing the establishment of effective coating methods for the blades in the gas turbine used in the demonstration plant.
Preliminary Verification Test
Preliminary Verification Test
To improve plant reliability, reliability verification test was performed from fiscal 1999 to fiscal 2001 on the gasifier, gas cleanup system, and gas turbine, in line with the design research underway, before full-scale design work for a demonstration plant.
1) Reliability Verification Test of the Gasifier Component Equipment
Gasification tests were performed using a 24 t/day coal gasifier test facility to investigate the potential for wear and other detrimental phenomena on various parts. No anomalies such as wear, burns, or malfunctions were noted, confirming the reliability of the materials and parts (specifications) being considered.
The test also involved varying oxygen concentrations and types of coal and using the types of coal regarded as candidates for use in the demonstration plant, leading to a good understanding of the gasification characteristics of individual coal types.
Additionally, high-temperature gas filter evaluation test identified the characteristics of differential pressure/dust collection based on filter types, providing data to support model selection.
Equipment (large-scale powder valve, high-pressure soot removal units) of a scale equivalent to that of the demonstration plant were also used to undertake operations test under conditions that simulated operating conditions at an actual plant, thereby verifying the reliability of the equipment in question.
2) Reliability Verification Test of the Gas Cleanup System Component Equipment
In connection with a wet gas cleanup process, the deposition and sublimation behavior of NH4Cl (ammonium chloride) resulting from the HCl and NH3 of coal gas was studied. The results clarified the associated characteristics of NH4Cl.
To understand the deterioration behavior of the solution (MDEA solution) used to absorb the H2S present in coal gas, absorption deterioration test was performed with simulated gas and basic test equipment. These results were used to assess the deterioration characteristics of the absorption solution.
In addition to the foregoing, the reliability of the equipment was verified by undertaking durability test of the diversion valve (of a scale equivalent to the demonstration plant) of the H2S incinerator, confirmation test of the performance for the removal of impurities present in coal gas using a wet gas cleanup all-inclusive system equipped with an actual coal gas generator, and test to determine ways to prevent the adhesion of ammonium chloride in the coal gas heat exchanger (GGH).
3) Reliability Verification Test of the Gas Turbine Component Equipment
With respect to the adhesive characteristics of the deposits, the results showed that the composition of the actual extraneous matter and that of matter identified using the condensation composition formula were nearly identical, confirming the validity of the formula.
With respect to the penetration of corrosive elements into coating materials, work was done to clarify the correlation with concentrations of corrosive elements and the temperature of the metal making up the blades.
Moreover, to acquire dependence data on the relationship of deposits pertaining to metal temperature/time and on that pertaining to pressure/temperature, test specimens and actual blades were exposure-tested while varying numerous parameters.
Design Research
Design Research
Work from fiscal 1999 to fiscal 2001 focused on research development leading up to the construction of a demonstration plant consisted primarily of tasks such as conceptual design and assessment studies of the safety and reliability of the IGCC system.
1) Conceptual Design
Work on plant conceptual design began to determine test conditions for preliminary verification test and to identify a plant model for the study assessing the safety and reliability of the IGCC system (discussed later).
In fiscal 1999, the rough boundary parameters for various demonstration plant components were determined through rudimentary equipment designs of the overall plant. In addition, issues and constraints expected to emerge in the demonstration plant were identified for individual systems and equipment, leading to possible solutions for such issues and constraints.
Work in fiscal 2000 analyzed the extent to which variations in parameters such as atmospheric temperature, gasification air ratio, and oxygen concentration affected the overall IGCC system to determine safety margins and other factors and to identify optimal system and equipment capacity.
Rudimentary equipment designs for the demonstration plant incorporated the results of this study.
2) Assessment Study of the Safety and Reliability of the IGCC System
In fiscal 1999, using a failure mode and effect analysis (FMEA) approach–i.e., a method for assessing safety and reliability–we identified aberrant occurrences for individual systems and equipment. We performed follow-ups to analyze their frequency and potential effects on the IGCC system and to identify potential solutions. The results of the work led to a good understanding of the safety and reliability of the individual systems and equipment.
In fiscal 2000, another method for assessing safety and reliability, a hazard and operability analysis (HAZOP) that took an approach differing from FMEA, was used to project and assess potential causes of aberrant occurrences and the scope of their effects.
In addition, changes in the operating condition (dynamic characteristics) of the systems and equipment in response to normal changes in loads and at the startup/shutdown of the demonstration plant were forecast through simulations by studying methods for running and controlling the demonstration plant.
Demonstration facility Mechanisms and Specifications
Gasification system
The gasifier is a pressure vessel with internal pressure maintained at 3 MPa (approx.) and fitted with a gasifier chamber surrounded by a water-cooled membrane wall.
The gasifier chamber is divided into two sections: a combustor and a reductor.
Gasification occurs following the introduction of pulverized coal and air from the burner.
Pulverized coal in the combustor is burned at approx. 1800 ℃ to generate the heat needed for the gasification reaction in the reductor and to enable the discharge of coal ash as molten slag.
The reductor is equipped with functions that initiate gasification when pulverized coal is introduced to the high-temperature gas arriving from the combustor located underneath it. These functions also decrease the temperature of the gas through an endothermic reaction accompanying gasification, thereby preventing the adhesion of ash in the SGC heat exchanger located downstream.
The gasifier is divided into two sections and is described as having a two-stage entrained flow gasification configuration, with the combustor at the bottom and the reductor at the top. The configuration facilitates the melting of ash at the high temperatures made possible by the intensive introduction of air into the combustor and by a mechanism that allows use of the reductor exclusively for gasification reactions to allow smooth gasification.
Of the pulverized coal supplied to the gasifier, powder (char) containing fixed carbon is caught by the char recycling unit and reintroduced to the gasifier. The char recycling unit consists of a cyclone separator and a porous filter.
Gas cleanup system
The gas cleanup system removes sulfur compounds, nitrogen compounds and other materials from the gas. The cold gas cleanup system is cleaned using water and chemical solutions.
Sulfur compounds are removed using an amine solution. Here, since the composition of the sulfur compounds in the gas created in the gasifier is primarily H2S (hydrogen sulfide) and COS (carbonyl sulfide), COS is converted into H2S by catalytic reactions inside the COS converter to permit absorption by the amine solution. Upon conversion, the coal gas is dissolved in the amine solution to absorb the H2S.
In the regenerator, the amine solution releases the H2S absorbed when heated; burning the H2S results in SO2 (sulfur dioxide). Free of fly ash inside the SO2 absorber, the gypsum is of significantly higher purity than the gypsum recovered from power generation processes that use finely pulverized coal.
Trace elements such as halogen and ammonium are removed when the gas is cleaned with water.
Combined cycle power generation system
Combined cycle power generation system The combined cycle power generation system is configured as a single-shaft type, whereby the generator, steam turbine, and gas turbine are all configured on the same shaft. Coal gas is burned to drive the gas turbine. The waste heat resulting from the combustion is then collected from the gas turbine, using the heat recovery steam generator (HRSG) to generate steam, which is combined with steam from the gasifier to drive the steam turbine. The output ratio between the gas turbine and the steam turbine here is about 1:1, as opposed to the 2:1 for LNG combined cycle thermal generation, due to the availability of heat from the gasifier (the SGC heat exchanger) in addition to waste heat from the gas turbine, which makes it possible to provide more output to the steam turbine side than with LNG-fired power generation.
The air compressor outlet of the gas turbine is equipped with a bleeder line to supply the compressed air needed by the gasifier, helping cut auxiliary power. The dual mode combustion unit can be switched between light oil and coal gas.
To reduce NOx, a De−NOx unit is built into the heat recovery steam generator.
Specifications for the IGCC Demonstration Plant
| Capacity | 250 MW | |
|---|---|---|
| Coal Consumption | approx．1,700 t/day | |
| System | Gasifier | Air-blown & Dry Feed |
| Gas Treatment | Wet(MDEA) + Gypsum Recovery | |
| Gas Turbine | 1,200℃－class (50Hz) |
|
| Efficiency (Targer Value) |
Gross | 48%(LHV) 46%(HHV) |
| Net | 42%(LHV) 40.5%(HHV) | |
| Flue Gas Properties (Target Value) |
SOx/td> | 8 ppm (16%O2 basis) |
| NOx | 5 ppm (16%O2 basis) | |
| Dust Loading | 4 mg/mN3 (16%O2 basis) | |
Overview of the Demonstration Plant Project
IGCC development efforts are currently advancing under the auspices of the Ministry of Economy, Trade and Industry (METI) through the joint efforts of eleven corporate bodies, including nine power companies,* the Electric Power Development Co., and the Central Research Institute of Electric Power Industry.
During the period from fiscal 1986 to fiscal 1996, the Engineering Research Association for Integrated Coal Gasification Combined Cycle Power Systems (IGC Association) served as the principal entity. Based on a commission from the New Energy and Industrial Technology Development Organization (NEDO), it performed pilot plant test with coal processing volumes of 200 t/day (equivalent to 2.5 MWe ) in Nakoso, Fukushima Prefecture. The results achieved were material and significant.
Against the backdrop of results obtained from feasibility studies and essential technologies research from fiscal 1997 to fiscal 1998 and preliminary verification test and design research from fiscal 1999 to fiscal 2001, Clean Coal Power R&D Co., Ltd., was founded in fiscal 2001 with funds contributed by nine power companies and the Electric Power Development Co. and charged with the mission of developing air-blown IGCC technology. Project costs are subsidized by the government (the Agency for Natural Resources and Energy of Ministry of Economy, Trade and Industry,; until fiscal 2009) and by eleven corporate bodies (nine power companies, the Electric Power Development Co., and the Central Research Institute of Electric Power Industry).
Highlights of the schedule for the Demonstration Plant Project include a detailed design of a demonstration plant and environmental assessments performed from fiscal 2001 to fiscal 2004; the construction of a demonstration plant from fiscal 2004 to fiscal 2007; and demonstration test for the four years from September 2007 (initial firing of the gasifier) to the end of fiscal 2010.
This demonstration test comprised reliability verification as well as tests of the operability, durability, and cost-effectiveness of the IGCC technology and the initial objective/indices in each aspect were mostly achieved.
From fiscal 2012 to the end of fiscal 2013 for 2 years, the verification tests will be further implemented with the main focus on reliability, cost-effectiveness and coal type flexibility, for the solution of new challenges and the maturity of IGCC technology targeting at the smooth commercialization.
*Hokkaido Electric Power Co., Tohoku Electric Power Co., Tokyo Electric Power Co., Chubu Electric Power Co., Hokuriku Electric Power Co., Kansai Electric Power Co., Chugoku Electric Power Co., Shikoku Electric Power Co., Kyushu Electric Power Co.
New Possibilities for Coal
In efforts to address global warming, it is critical to introduce new sources energy like wind and solar power, in addition to nuclear and LNG-fired power generation. Equally important, especially for resource poor Japan, is introducing thermal power generation technologies that tap into coal, known for its abundant reserves and stable prices—thereby creating a menu of optimal energy sources and ultimately securing a stable energy supply.
This goal requires a healthy balance between ensuring reliable energy sources and addressing global warming issues, something that can be achieved through development of high-efficiency coal fired power generation technologies. Here, IGCC is expected to play a core role.
Additionally, the IGCC is expected to facilitate not just the use of coal inside Japan, but help reduce greenhouse gases significantly through dramatic improvements in efficiency for coal fired thermal power generation. The IGCC is also expected to enhance environmental performance in power generation to the same degree outside Japan.
