OCR Text |
Show throat. During the 500-hour duration test, several erosion-resistant materials were evaluated. Nozzles constructed of 440 C stainless steel and hardened tool steel provided approximately 80 hours of operation before replacement was necessary (with total wear of about 0.03 inches). A steel nozzle cap with tungsten-carbide inserts exhibited no measurable wear over an initial period of 40 hours, but 0.0015-inch wear after 102 hours of operation. After the series of coal particle size tests and during the coal type tests, the total wear of the same tungsten-carbide inserted nozzle cap increased to 0.006 inches after 189 hours of operation. Another steel nozzle cap with tungsten-carbide inserts was also used and found to have 0.003-inches wear after 68.75 hours of operation during the coal type tests. Excessive wear in the progressing-cavity Moyno feed pump was noted during the earlier COM tests. Wear of the tool steel rotor and stator was characterized by a reduction in pumping capability. Improved performance was realized when a 3UNA-N stator and a 10-mil-undersized chromed-face tool steel rotor was used. Some abrasive marks were observed on the stator, but no wear was noted during and after the entire COM test series. Significant wear of the connecting rod and pins between the drive shaft and the pump rotor was noted after the 500-hour-duration test due to the exposure of the connecting rod and pins to the COM being pumped. The pump manufacturer has changed the connecting rod design to a sealed-gear, universal-joint design for new pumps. The Deming rotary COM transfer pump had operated without noticeable problems over 2j years, until its performance fell off sharply by the end of the COM program. Significant wear was found to occur on the idler gear and the idler gear shaft due to the exposure to COM; no wear was noted on the drive gear. Various piping sections, including a ball valve, a 90 elbow, a pipe tee, and "Y" section, were measured before and after the 500-hour-duration test. No evidence of wear was noted in any of the components upon completion of the test. 14-9 |