Test G-16 was conducted on January 20 to 24, 1981, with 58.2 hr of coal feed, 60.5 hr of char feed, and 69.7 hr of char burner firing. During the fuel gas reduction test, it was observed that the plant pressures and temperatures were slightly less steady than during operation with excess fuel gas. The gasifier pressure oscillated plus or minus five psi compared to a normal fluctuation of plus or minus two psi; while the Stage I temperature varied plus or minus 50/sup 0/F compared to plus or minus 20/sup 0/F. Fuel gas was returned to normal flow due to problems with gas washer control and instabilities in char feed. Slag removal from the gasifier was much better during Test G-16 (90%) due to use of the slag breaker, slag agitator, and installation of the grating over both lockhopper legs. Favorable results were obtained during the first test using flocculant addition to the coal fines stream feeding the centrifuge, to aid in solids removal. Installation of the vortex breaker and the drilling of the holes in the lower baffle, to prevent interference with the level control instrumentation, did not improve operation of the gas washer. Test G-16A was conducted on February 23 to March 1, 1981, with 122.0 hr of coal feed, 120.2 hr of char feed, and 133.2 hr of char burner firing. The gasifier was able to be operated stably at an oxygen to fuel gas ratio of two to one in Stage I for a 24-hr period. Testing of the Aurburn flow monitor indicated that this instrument was able to give immediate and consistent responses to changes in char feed valve setting. It will be necessary to make some revisions in the sensor, however, before the monitor can be used to determine flow rate. The modified Kamyr valve successfully controlled char feed through the B leg, with good control occurring between twenty to sixty percent valve position.