Abstract: A variable limit is utilized to prevent a position controller which requires a velocity set point signal from overdriving a stuck control valve. Control based on a comparison of the actual position to desired position is utilized unless the valve is stuck. If the valve is stuck, the variable limit controls the velocity set point provided to the position controller until such time as the valve becomes unstuck.

Abstract: A control system for a fluid catalytic cracking unit is provided in which either the wet gas compressor or the air blower is selected for base loading. After the device selected for base loading has been base loaded, load is shifted to the device which was not base loaded. The feed flow rate is forced to continue to increase until both the wet gas compressor and the air blower are loaded so as to substantially maximize the production of the desired product.

Abstract: In accordance with a preferred embodiment of this invention, a linear stitching design having improved definition is embossed onto the surface of a hot, thermoplastic sheet. During embossing the sheet is placed over a special anvil formed of an elastomer strip arranged in the pattern of the stitching and inlaid in a rigid support member. The support member confines the elastomeric anvil member such that during the embossing operation the anvil promotes more uniform distribution of pressure on the sheet and forces it into full contact with the embossing die.