8. Subtask 8 : Development of Hydrogen-Combustion Turbine

8.2 Development of Combustion Control Technology

8.2.1 R&D Goals

8.2.1.1 Background

Since 1993, the authors have conducted investigations on basic structure of hydrogen-oxygen combustor, combustion tests using small burners, and investigation and analysis of cooling and dilution structures of combustor wall. Since 1995, they have begun the combustion tests using model combustors, and investigated the combustion mechanism and basic structure more concretely. Moreover, in 1996, in order to evaluate each kind of combustors, the basic designs of the combustors are done for the evaluation test. And the high-pressure combustion test facility for evaluation tests (test facility for evaluation of combustor) is designed, and a part of it is produced.

8.2.1.2 Objects

8.2.2 Results in Fiscal Year 1997

1. Development of hydrogen-oxygen combustion

1. Based on the achievements in FY1997, the combustor is designed and produced for the evaluationtest. Oxygen and steam are mixed at the burner, swirled and injected. Flame is held due to thecirculation flow caused by the swirling. Hydrogen is injected from the multi-holes injector. (Fig. 8-2-1)

2. The combustion test is performed as the preliminaries of the evaluation test at the atmospheric pressure. The results are as follows.
   1. The possibility of smooth ignition is confirmed.
   2. Even though the wall temperatures of the combustor are high at some parts, it is estimated that the distribution of wall temperatures can be improved by the additional processing of cooling holes (Fig. 8-2-2).
   3. Both concentrations of residual hydrogen and oxygen are less than 1% near the stoichiometric ratio (Fig. 8-2-3).

3. The continuously analyzing system for residual hydrogen and oxygen is remodeled in orderto improve the response. The response time is reduced to about half of the previous time (about 90s)

4. The test conditions, procedure, measuring items are discussed among CRIEPI and 3 contract companies.

1. The burner structure and the diluting steam hole are modified in the model combustor. Itscombustion test is performed at the pressures between 1 and 2ata. The following results are as follows.
   1. The smooth ignition is possible.
   2. The maximum wall temperature of the combustor is maintained under the allowable temperature of the material (Fig. 8-2-4).
   3. Both concentrations of residual hydrogen and oxygen are less than 1% near the stoichiometric ratio (Fig. 8-2-5).

2. Based on the previous achievements, the combustor is designed and produced for the evaluation test. In this combustor hydrogen and oxygen are combusted near the burner, and diluted with steam after combustion. Hydrogen is injected from the ring nozzles, and flame is held due to the circulation flow caused by swirling oxygen and steam (Fig. 8-2-6).

3. The combustion test facility at the atmospheric pressure is remodeled in order to conduct the preliminaries of the evaluation test.

(Combustion mechanism: supplying hydrogen from the stabilization hole and combusting it after premixing oxygen with steam)

1. Based on the previous achievements, the combustor is designed and produced for the evaluation test. In this combustor, oxygen is mixed with the steam supplying for the combustor, and a part of it is also supplied from the primary stabilization hole. Hydrogen is injected from the multi-holes injector, and flame is held due to the circulation flow caused by the collision flow from the stabilization hole (Fig. 8-2-7).

2. The combustion test is performed as the preliminary test of the combustor for the evaluation test at the atmospheric pressure. The results are as follows.
   1. The possibility of smooth ignition is confirmed.
   2. It is confirmed that the rational oxygen distribution to the primary stabilization hole is about 20% of the whole oxygen supply in order to minimize residual concentrations of hydrogen and oxygen near the stoichiometric ratio (Fig.8-2- 8).

2. Test facility for evaluation of combustor

(2) The trial operation and adjustment of the facility are conducted

3. Examination of evaluation test results

(2) In the development committee for combustion control technology, the evaluation method is examined in order to determine the optimal combustor for hydrogen-combustion turbine.

8.2.3 Reseach plan for fiscal year 1998