【正文】 Rotary Equipment Drivers and Equipment Couplings Fixedspeed couplings Rigid couplings Flexible coupling Variablespeed couplings Hydraulic couplings Magic couplings ? 29 1. Rotary Equipment Drivers and Equipment Belts are used to connect two parallel shafts. ? A pulley is mounted on the end of each shaft. ? The size of the pulleys allow the driver and driven equipment to operate at different speeds. ? Belts fit in the grooves of the pulley. ? Belts e in a variety of shapes and sizes and are made of durable material designed to withstand operating conditions. ? 30 1. Rotary Equipment Drivers and Equipment Belts are used to connect two parallel shafts. ? Belt drives require less space than fixedspeed or variablespeed couplings. ? A belt drive can make speedtotorque or torquetospeed conversions. ? Process technicians frequently inspect belts during rounds to ensure that safety guards are in place, that belt tension is correct, and that the belts are still mounted on the pulleys. ? Flopping, squealing, or smoking belts indicate wear, tension, or drivenequipment problems. ? 31 1. Rotary Equipment Gearboxes and Power Transmission ? Often used between the driver and the driven equipment. ? The drive gear meshes with a larger or smaller gear, the driven gear. ? As the drive gear rotates, the interlocked gears in the box turn, transmitting power to the driven equipment. ? Small gear size is associated with speed. Large gear size is associated with torque. ? 32 1. Rotary Equipment Gearboxes and Power Transmission ? Power transmission in rotating equipment is classified as speedtotorque conversion or torquetospeed conversion. ? Speedtotorque conversion is acplished with a small drive gear with a large driven gear. ? Torquetospeed conversion uses a large drive gear with a small driven gear. ? 33 1. Rotary Equipment Electric motors The process industry uses electric motors to operate pumps, generators, pressors, fans, blowers and other equipment. Electric motors are either direct current (DC) or alternating current (AC). The operation of an electric motor is based on three principles: ? Electric current creates a magic field。 ? Current direction determines the magic poles. ? 34 1. Rotary Equipment Electric motors Electric motor consists of: Stationary mag (stator) Moving conduct (rotor) Permanent magic field is formed by the lines of force between the poles of the mag. When electricity passes through the conductor in a DC motor, it bees an electromag and generates another magic field. ? The twin fields increase in intensity and push against the conductor. 35 1. Rotary Equipment Electric motors The rotor in an AC motor is a slotted iron core. Copper bars are fitted into the slots. Two thick rings hold the bars in place. Alternating current flows into the stator, producing a rotating magic field. The stator artificially creates an electric current in the rotor, which generates the second magic field. When the two fields interact, the rotor turns. ? 36 2. Stationary Equipment Piping and storage tanks Gate globe, and ball valves Filters Heat exchangers Cooling towers furnaces Boilers Reactors Distillation columns ? 37 2. Stationary Equipment 38 Chapter 2. Valves Valve─ a device to direct and control the fluids by starting, stopping, and throttling (restricting) flow to make processing possible. Valves─are designed to withstand pressure, temperature, and flow and can be found in homes and industry across the world. 39 Chapter 2. Valves The mon valves found in the manufacturing environment are: Gate valve Ball valve Check valve Butterfly valve Plug valve Needle valve Threeway valve Diagragm valve Relief valve Safety valve Angle valve Multiport valve ? globe valve 40 Chapter 2. Valves Process operators classify valves by: Classification of valve Flowcontrol element function Operating condition ? Gate valve ? Globe valve ? Needle valve ? Check valv