Abstract: One embodiment of the present application is a gas turbine engine with a compressor that includes a variable geometry mechanism to vary working fluid flow area. A desired state of this mechanism is selected different than a current state to change the amount of flow area. The mechanism has a hysteresis band corresponding to a difference between increasing the flow area to reach the desired state and decreasing the flow area to reach the desired state. To control operation of the mechanism within this hysteresis band, a determination is made whether the desired state corresponds to a greater flow area or a lesser flow area relative to the current state.

Abstract: A process for preventing deposits when venting steam containing entrained polymer from high pressure reactors used for preparing nylon from dicarboxylic acid and diamine. The hot steam generated during condensation polymerization of the reactants is vented through a pressure-control valve at a rate which maintains a desired pressure in the reactor. Deposit of polymer in the valve or vent pipe after release of pressure is prevented by injecting water into the low pressure side of the valve or into the subsequent vent pipe. At least sufficient water is used to saturate the vented steam and to wet the walls of the vent pipe.