초록 ▼

The present invention provides a method and apparatus for generating refrigeration in a process operating at sub-ambient temperatures in which the refrigeration is generated by a turboexpander. The turboexpander is coupled to a generator controlled so that its speed is maintained at a setpoint throu

The present invention provides a method and apparatus for generating refrigeration in a process operating at sub-ambient temperatures in which the refrigeration is generated by a turboexpander. The turboexpander is coupled to a generator controlled so that its speed is maintained at a setpoint through electromagnetic braking and its power output is maintained at line matching voltage and frequency. The speed control of the generator therefore, also controls the speed of the turboexpander. The setpoint is calculated to be equal to a product of an operational efficiency parameter, U/Co, and a square root of twice the enthalpy drop in the flow passing through the turboexpander divided by a product of pi and a diameter of an impeller employed within the turboexpander.

대표청구항 ▼

We claim: 1. A method of generating refrigeration in a process operating at sub-ambient temperatures, said method comprising:compressing a process stream utilized within the process to produce a compressed process stream;expanding the compressed process stream within a turboexpander having an impell

We claim: 1. A method of generating refrigeration in a process operating at sub-ambient temperatures, said method comprising:compressing a process stream utilized within the process to produce a compressed process stream;expanding the compressed process stream within a turboexpander having an impeller that is driven by the process stream with performance of work, thereby producing an exhaust stream;the turboexpander designed to operate at an operational efficiency parameter equal to optimal value of U/Co;introducing the exhaust stream into the process to impart the refrigeration into the process;generating electrical power with a generator having a rotor coupled to the impeller so that the generator is driven by the work of expansion;controlling speed of the rotor of the generator and therefore, the turboexpander through electromagnetic braking of the rotor such that the speed is maintained at a setpoint and electrical current output of the generator increases as the speed of the rotor decreases and decreases as the speed of the rotor increases;controlling voltage and frequency of the electrical power generated by the generator as to be maintained at line matching levels and the electrical power generated by the generator may be introduced into a local electrical power grid at the line matching levels; andcontinually determining the setpoint of the speed of the rotor and therefore, the turboexpander by setting the setpoint equal to the product of the operational efficiency parameter and a square root of twice the difference between enthalpies of the compressed process stream upon entry into the turboexpander and the exhaust stream upon discharge from the turboexpander, divided by a product of pi and a diameter of the impeller.