Abstract: An apparatus for repairing curved grinding surfaces in bowl mill coal pulverizers by welding hardfacing material onto the grinding ring surface. The inventive apparatus includes novel guide structure imparting an arcuate motion to the welding torch as it traverses the grinding surface. In a preferred form a welding torch is pivotally mounted about an axis at or near the center of curvature of the grinding surface, pivoted along the circumference of the curved grinding surface to effect welding repairs. The pivotal positioning and motion of the welding torch assures a constant distance and angle relative to the grinding surface, and thus a strong, primary, non-overlapping weld bond across the entire width of the ring. In a preferred form the apparatus employs dual, independently adjustable, simultaneously indexed torch heads.

Abstract: An improved classifier cage for bowl mill type coal pulverizers which have been converted from stationary throats to rotating throats with reversed flow direction. The direction of the classifier vanes is reversed such that the rotational flow direction of coal/air from the rotating throat is generally maintained as it passes through the classifier cage into a classifier cone, rather than being reversed in "U-turn" fashion. A further improvement is made in the geometry of the classifier vanes to create a better downward and tangential redirection of the flow into the classifier cone.

Abstract: An improved coal pulverizer classifying system in which the feedpipe and classifier cone are provided with extensions to protect coal flow into the pulverizer from the annular fine-lifting airflow from the pulverizer throat. The feedpipe and cone extensions replace traditional intermittent discharge structure, improving flow through the classifier system and reducing the disruptive effects of the discharge on the annular flow from the pulverizer throat. An adjustable classifier venturi is also provided to adjust the exit angle and exit velocity of the fines leaving the classifier cone by the combustion delivery chute.

Abstract: An inlet venturi for coal-side exhauster fan structure used to deliver pulverized coal to a combustion chamber. Generally, the inlet venturi has an axial length comparable to that of the exhauster fan inlet, resulting in a shallow, smooth transition angle from the venturi to whizzer ring or similar structure for guiding the coal flow into the center of the fan assembly. The inlet venturi includes a back plate or collar portion which prevents eddy effects and pressure drop between the venturi throat and the exhauster fan inlet, and further serves to accurately position the venturi in the exhauster fan inlet. The inventive inlet venturi structure additionally permits the removal of some or all of the "whizzer" structure commonly used on such fans, resulting in substantial savings in power needed to drive the fan.

Abstract: A self-cleaning coal bypass and debris separation grid assembly has a sizing/segregating grid for particulate material such as coal, and a debris bypass grid downstream to bypass the coal to a coal crusher and separate any debris which might damage the crusher. Clearing mechanisms are provided for both the sizing/segregating grid and the debris separating grid. The clearing mechanism for the debris separating grid is preferably a rotating clearing comb having arcuate fingers yieldably mounted to a rotating axle shaft. The arcuate fingers are preferably adjustably tensioned to the axle shaft.

Abstract: A vertically aimable tip for a pulverized coal nozzle used in the boiler areas of coal fired, steam generating facilities. The nozzle tip comprises box-like outer and inner housings which are pivotally mounted as a unit to the outlet end of a pulverized coal conduit. A box-like end housing having integral splitter plates is loosely mounted in the outer housing in conforming and contiguous abutting relationship to the inner housing to complete the pulverized coal flow path. An air flow path is defined by the spacing between the outer housing and the combination of the inner and end housings. The combination of the end housing and splitter plates is held in place by means by slots and locking keys or tabs to permit differential thermal expansion. The splitter plates are hardfaced and extend upstream into the interior of the inner housing.

Abstract: An air flow rate control device for a rotating or stationary vane throat in a bowl mill pulverizer. The air flow rate control device comprises an adjustable deflector mounted on the lower surfaces of the pitched vanes to provide varying air flow passage cross sections. In one embodiment the deflector comprises a flexible member whose shape can be varied using manual adjustment apparatus to alter the air flow passage cross-section.

Abstract: A self-cleaning size-segregating grid for a coal crusher has two parallel clearing combs made up of rigid steel fingers which rotate through the grid bars to clear jammed materials therefrom. The propeller-like fingers are preferably staggered in angular orientation on their respective shafts. The shafts are spaced so that the swept volumes of the fingers overlap. A surge detector senses drive motor current as an indication of stall or incipient stall and automatically reverses the direction of rotation of the clearing combs.

Abstract: An air flow rate control device for a rotating or stationary vane throat in a bowl mill pulverizer. The air flow rate control device comprises an adjustable deflector mounted on the lower surfaces of the pitched vanes to provide varying air flow passage cross sections.

Abstract: A rotating throat pulverizing mill has a soft steel vane wheel which rotates with the control bowl for classifying purposes. Wear-resistant vane liners slide onto the vanes to protect the upper surfaces thereof and are held in place, in part, by integral clips which underlie the vane plates and, in part, by wear-resistant cap plates which are welded to a flush upper flange of the vane wheel. Arcuate wear plates are also welded to the exposed surfaces of an air deflector outboard of and above the vane wheel. The vane wheel is preferably constructed in segments. A modified deflector assembly comprises a first portion having a base plate and spaced vertical ribs, which first portion is bolted to a lower deflector, and a box-like, wear-resistant cover assembly which seats on the ribs and is welded to the seat blocks by ways of access holes.