Influence of various operating conditions on advanced PFBC with staged combustion

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20006743

Moersch, O; Nagel, H; Spliethoff, H; Hein, K R.G.

The development of PFBC towards advanced or second generation PFBC focuses on an increase of temperature at the gas turbine inlet to bring forth a substantial improvement of the turbine itself and the overall system performance. Most of such advanced systems described in literature include a carbonizer for partial conversion of coal producing a low calorific pressurized syngas and a PFBC burning the remaining char. After hot gas clean-up the syngas and the O{sub 2}-rich fuel gas from the PFBC are led to the combustion chamber of the gas turbine. In the proposed staged combustion concept (PFBC-SC), which also aims at raising the temperatures at the gas turbine inlet, coal is burned substoichiometrically in a pressurized fluidized bed producing a low calorific gas. After hot gas clean-up the gas undergoes post-combustion with pressurized air and enters the gas turbine at approximately 1,450 K. The advantages of PFBC-SC over APFBC as described above are the lower investment costs and the simpler process, because no separate gasifier including hot gas cleaning device is needed. At the IVD's 50 kWth PFBC test facility, experimental investigations were done into substoichiometrical combustion with regard to composition of the produced gas, carbon-conversion and afterburner temperature. The results of the experiments which were carried out at various temperatures (1,073--1,200 K), pressures (1--13 bar), air ratios (0.5--0.9) and with different coals were compared with chemical equilibrium calculations. In contrast to the operating pressure the heating value of the syngas ({ge}CO, H{sub 2}, CH{sub 4}) could be increased significantly with increasing temperatures. Due to the better gasification behavior of subbituminous coal compared with bituminous coal almost equilibrium conditions were achieved. At high pressures and temperatures (13 bar/1,173 K) the carbon conversion rate 97.5% at all air ratios.

• Research Organization: Univ. of Stuttgart (DE)
• OSTI ID: 20006743
• Report Number(s): CONF-990534--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
BITUMINOUS COAL
COAL GASIFICATION
COMBINED-CYCLE POWER PLANTS
FLUIDIZED-BED COMBUSTION
HOT GAS CLEANUP
LOW BTU GAS
OPERATION
PRESSURIZATION
STAGED COMBUSTION
SUBBITUMINOUS COAL