OCR Text |
Show Control System Operation Reliability The system parameters were measured using plant instrumentation and equipment supplied by EER. EER conducted exhaust gas, wood feed, and ash analyses. Evaluations of system operability were obtained by direct observation by EER and by discussions with operating personnel and representatives from Lamb-Cargate. Measurements were obtained over five test periods with the system operating at full load. Table 3 summarizes average performance measurements during the tests. Table 4 shows the average wood and ash compositions. These results show that the system was operating an average of 16 percent below rated capacity during the tests. However, this result was due to the control system specific to this installation and not due to limitations of the combustor. Heat load at this unit is usually controlled by kiln heat demand. For these tests, load was set manually. Since the unit is not equipped with an instantaneous measurement of load, heat output could not be determined until after the completion of each test. Following the test period, the unit operated for an extended period at 120 percent of rated load. Excess air varied from 12 to 28 percent with an average of 20 percent, which is similar to operating levels of such processes as pulverized coal burners. Operating parameter results showed stable combustion gas temperatures at the control points in the burner and a high combustion efficiency. The exhaust gas temperature is only slightly lower than the secondary combustion chamber temperature showing little heat loss in the combustor. An ash balance based on analysis of the fuel, bottom ash, and particulate samples showed 95 percent of the unburned wood leaving the system as bottom ash and only 5 percent leaving as particulate in the exhaust gas. Average exhaust gas emissions are shown in Table 5. Particulate measurements included determining solid particulate using EPA Method 5 and total particulate including both solid and condensible portions. Condensible particulate was found to be a significant portion of the total particulate. Particle size distribution was also measured using an Andersen in-stack cascade impactor. Size distribution data was needed to evaluate particulate 28-16 |