Fiscal 2007 Status of Demonstration Test

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Integrated Coal Gasification Combined Cycle (IGCC)

The firing of the gasifier on September 20, 2007, marked the completion of IGCC demonstration plant construction and the start of demonstration test.

Coal gas was first introduced into the gas turbine in early December 2007. A plant load of 50% was achieved toward the end of the same month. Test progressed steadily until the plant achieved a load of 75% in early January 2008 and, ultimately, 100% (250 MW) on March 7 of the same year. (See the photo below.)

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The status of individual systems and equipment during fiscal 2007 is given below:

(1) Gasification system

[September] After the firing of the gasifier on September 20, the temperature and pressure of the gasifier were raised while burning kerosene fuel to confirm safety with kerosene gas before introducing coal into the gasifier. (The gasifer temperature must be raised to a certain point with kerosene to activate gasification of coal.)
[October] Test also included the switch from kerosene to coal for the gasifier. This confirmed that the operating conditions of the gasifier and the mode of slag discharge were consistent with design.
[November] Tests confirmed that the gasifier could be controlled as designed.
[December through March] The tests performed during these months involved varying the pressure of the coal gas to confirm satisfactory controllability.The gasifier and the gas turbine were also operated under coordinated control to confirm operational stability.

(2) Gas cleanup system

[September] Combusted gas originated from the kerosene in the gasifier was supplied through the gas clean up system.
[October] Feeding of coal gas began in the middle of the month. Amine regeneration (amine being the chemical solvent used in the gas cleanup process) began toward the end of the month.
[November] The operation of the off-gas incinerator used to burn the sulfur components recovered from coal gas was studied to confirm combustion status. The sulfur recovery system was then adjusted. The results were positive.
[December through March] The stability of coal gas system operations was confirmed under various load conditions.

(3) Combined Cycle Power Generation System

[September] General interlock test was performed by operating the gas turbine at 25% load (kerosene-fired).
[October] The operating parameter of the system was adjusted during the on-load operation.
[November]

In mid-month, the turbine was abruptly stopped to test various operational aspects. A good result was obtained during the test.

Toward the end of the month, the fuel gas pipe was purged to confirm various aspects of this procedure. (Purging involved displacing air inside the fuel pipe with nitrogen before introducing coal gas into the gas turbine.)

[December through March]

Tests to confirm problem-free fuel switching (kerosene ←→coal gas) for the gas turbine were combined with tests of combustion under various load conditions.
Remarkable results were obtained. Tests for the steam turbine also confirmed that load change and switching fuels in the gas turbine had no significant effects on dominant steam temperature and caused no problems.

General interlock test performed for coal gas-firing confirmed that individual systems could be shut down safely.

Integrated coal gasification combined cycle(IGCC)

Clean Coal Power R&D Co., Ltd. conducted IGCC demonstration test from 2007 to the end of fiscal 2012.Joban Joint Power Co., Ltd.. took over the demonstration plant as Nakoso power station unit No. 10 for commercial operation from fiscal 2013.
Air blown type IGCC system is adopted for unit No. 10.

In 2013, commercial operation of unit No.10 had started from June 28th and it stopped December 8th.
The operation time was 3,917 hours. It broke the world record for continuous operation time(3,287 hours) of IGCC which was set by Bugghenum power station in Netherland.

Schematic of IGCC

An IGCC system is designed to achieve higher efficiency than conventional coal-fired power generation systems through the gasification of coal coupled with a combined cycle (CC) process.

Specifications of No.10 unit

Capacity 250 MW gross
Coal Consumption approx. 1,700 metric t/day
System Gasifier Air-blown & Dry Feed
Gas Treatment Wet (MDEA) + Gypsum Recovery
Gas Turbine 1200 deg C-class (50Hz)
Efficiency
(Target Values)
Gross 48% (LHV) 46% (HHV)
Net 42% (LHV) 40.5% (HHV)

A number of IGCC projects are currently being pursued worldwide.

Preceding IGCC

Project name
Operating
company
(Country)
Gasifier
(Blown type)
GT Gross Output
(MW)
Commercial
Operation
month-year
Consecutive
Operation
(hours)*
Remark
Buggenum
Nuon(Vattenfall)
(Netherland)
Shell
(O2)
Siemens
V94.2
284 Jan-94 3,287  
Wabash River
Wabash Valley
Power
(USA(Indiana))
E-Gas
(Dow)
(O2)
GE
7FA
296 Aug-95 1,848  
Polk Power
Tampa Electric
(USA(Florida))
GE
(Texaco)
(O2)
GE
7FA
315 Jul-96 1,673  
Puertollano
ELCOGAS
(Spain)
Prenflo
(O2)
Siemens
V94.3
318 Nov-97 954  
IGCC demonstration
plant CCP
(Japan(Fukushima))
MHI
(Air)
MHI
701DA
250 Jul-13 3,917 Commercial operation a unit No.10 began in April,2013

*using only syngas

Year-by-Year Demo Test Status

Results of Demonstration Testing (Detailed)

1) IGCC System Stability: “Coal Gasification Adjustment Testing”

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
・Stable shutdown when plant malfunctions.

Test the interlocks to confirm safe plant shutdown.

Test period: FY 2007
Status: Completed.

  • ・Interlock testing confirmed stable shutdown when system malfunctions were simulated.
  • <Test Items (Excerpt)>
  • ・ Comprehensive test of interlock performance when oil ignites
  • ・Comprehensive test of interlock performance when coal gas ignites.
Confirmed that
system is stable.Objective accomplished
・Safe handling of coal gas.

Check and adjust plant operating status, and confirm that coal gas is handled safely and that operation is stable under rated load.


Test period: FY 2007
Status: Completed.

  • ・Ran various trials and adjustments, and confirmed that coal 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).
  • <Test Items (Excerpt)>
  • Gasifier
  • ・Switched the fuel (kerosene → coal)
  • ・Confirmed stable operating control of gasifier.
  • ・Ran using cooperative control of gasifier and gas turbine.
  • Gas cleanup system
  • ・Checked operation with oil gas and coal gas.
  • ・Checked operation of off-gas combustion furnace.
  • ・Checked sulfur-recovery equipment regulation.
  • Combined cycle power generation system
  • ・Fast stopping of turbine.
  • ・Checked purging of fuel-gas piping.
  • ・Switched the fuel in the gas turbine (kerosene → coal gas).
  • ・Regulation of gas-turbine combustion.
  • ・Checked running condition of steam turbine.

2) Reliability of the facility: “2000-hours sustained operation”

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
・Running continuously for 2000 hours (equivalent to 3 months of summer).

Run continuously for 2000 hours.


Test period: FY 2008
Status: Completed.

  • ・Ran for 2000 consecutive hours, from 6/10/08 to 9/17/08.
  • ・Operation was stopped to repair damaged ASU valve during run, but was restarted immediately after repair and run for 2039 consecutive hours; plant then shut down as planned to perform inspection.
Achieved continuous-run target. Going forward, will also check durability over mid-to-long-term continuous operation.Objective accomplished

3) Coal Type Acceptability: Change to Other Coal Type / Change to Out-of-Spec Coal Type

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
・Collecting data while running on coal types outside of the design specs.

Check operation when using sub-bituminous coal (North American, Indonesian A).


Test period: FY 2008
Status: Completed.

  • ・Ran at partial load; confirmed that adjustments in running parameters were sufficient to enable single-fuel firing of two coal types (North American and Indonesian A), and collected plant data while operation was in progress.
  • ・In some cases, coal characteristics caused blockage in heat-transfer piping 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 design of commercial-level facilities.

In some cases, SGC heat-transfer piping downstream of the gasifier became clogged.

Results made it clear that various countermeasures would be required to prevent problems caused by different coal types.

Objective accomplished

Check operation when using sub-bituminous coal (North American).


Test period: FY 2009
Status: Completed.

  • ・Changed and readjusted the operating parameters, then checked operation using North American sub-bituminous.
  • ・In some cases, coal characteristics caused blockage in heat-transfer piping downstream of the gasifier.

Run plant with the purpose of enabling use of mainstream coal types beyond those covered by the design specs, and of sub-bituminous types capable of single-fuel firing.


Test period: FY 2010
Status: Completed

  • ・Changed and readjusted the operating parameters, then checked operation using Indonesian B sub-bituminous.

4) High Efficiency: “Operations Optimization Test”

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
  • ・Achieving targeted thermal efficiency (LHV 42% at sending end).

Verify efficiency; investigate whether reasonable to anticipate efficiency enhancements sufficient for commercial use.


Test period: FY 2008
Status: Completed.

By adjusting running parameters, able to confirm an LHV of 42.9% at the sending side, surpassing the goal of 42% LHV. Confirmed high efficiency.Objective accomplished

5) Durability : “Durability Confirmation Test”

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
  • ・Running for long period, followed by overhaul inspection.

Run for 5000 hours, then did overhaul inspection to evaluate durability.


Test period: FY 2009, FY 2010
Status: Completed.

  • ・Ran for 5000 hours in one year.
  • ・After confirming durability by running for 5000 hours, carried out inspection. Confirmed the absence of any critical device damage that would require large-scale remodeling. Confirmed the equipment used has an appropriate IGCC design.
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: “Assessment of Cost-Effectiveness”

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
  • ・Evaluating economic feasibility based on operational performance.

Used operational performance as a basis for comprehensive evaluation of costs (construction costs, operating costs, maintenance costs, etc.); and evaluated whether this approach would be economically feasible in a commercial environment.


Test period: FY 2010
Status: Completed.

  • ・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. But will need to enhance precision of these systems for lower repair costs.Objective accomplished

New verification items and their contents

1) Reliability

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
  • ・Confirm the mid-to-long term durability of the IGCC facilities including countermeasures implemented during the past testing.

These studies as follow conducted. ・Durability assessment on the countermeasures against the troubles in the past. .

  • ・Evaluation on time-related deterioration through the long time operation.
  • ・Maintenance methods for reduction of the troubles in mid and long term.

Test period: FY 2011
Status: Completed.

  • ・Countermeasures to initial stage troubles were working well and no deterioration or damage was identified in operation, maintenance and regular inspection except for SGC heat exchanger clogging and release of rust originated in HRSG from the stack.
  • ・Additional two countermeasures to mid-and-long term worn-out troubles were implemented.
・Countermeasures to initial stage troubles were basically effective in long-term perspective such as durability.
・Latest troubles were analyzed and effective countermeasures were established, which were inspected in the maintenance work afterward and no trouble was identified.
Objective accomplished

Confirm the mid-to-long term durability with further operation duration.


Test period: FY 2012
Status: Completed.

  • ・Countermeasures were working well and no deterioration or damage was identified in operation, maintenance and regular inspection except for one incident, the incident was caused by damage at frequently operated valve and improvement in material was introduced, which resulted in good performance in operation.
  • ・Additional two countermeasures to mid-and-long term worn-out troubles were implemented and inspected at the end of fiscal 2012 maintenance outage and no problem was identified.

2) Coal Type Flexibility

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
  • ・Establish the measures against the troubles accompanied by some coal types.

Other types of bituminous coal except for design coal, that is, Columbian, Russian and Indonesian coals are to be in use and operational data to be collected in 2011.


Test period: FY 2011
Status: Completed.

  • ・Other types of bituminous Columbian, Russian and Indonesian coal were in use stably through adapting the operational parameters.
  • ・Some coal types brought about clogging in SGC heat exchanger piping facility.
・5 types of coal except for design coal was identified as applicable by the original and optimal adjustment in each coal type.
・Countermeasures newly developed in the design and its operation against clogging in SGC heat exchanger facility was identified as effective.
Objective accomplished

Another types of bituminous coal(USA) and sub-bituminous coal (Canada) were tested in 2012.

Test period: FY 2012
Status: Completed.

  • ・Two types of coal were in use stably through adapting the operational parameters and minute adjustment
  • ・Issue of clogging in SGC heat exchanger piping facility was effectively solved by dint of application of design change in the facility along with proper sooth blower operation in SGC.

3) Economy

Verification Items
(Overview)
Demo Test Results of Demonstration
Testing
Evaluation
  • ・Increase in samples of maintenance and inspection results for analyzing the maintenance cost which should be compatible with conventional pulverized coal fired generation.

Study on the cost reduction methods at commercial stage reflecting the operation and maintenance results in 2011.

Test period: FY 2011
Status: Completed.

  • ・Design improvement in SGC heat exchanger was studied.
  • ・Prolongation of inspection periods was studied.
・The design improvement In SGC was confirmed to be effective to reduce the SGC volume.
・Inspection period in each IGCC part was more precisely identified through the experience on the maintenance work, operation and facility troubles.
Objective accomplished

Cost reduction measures were further conducted, reflecting the operation and maintenance experiences in 2012.

Test period: FY 2012
Status: Completed.

  • ・The design improvement in SGC was actually installed in some part and was confirmed that no shortcoming appears.
  • ・Prolongation of inspection periods was studied.

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