초록 ▼

After the pumping station set points for a desired pipeline operation are calculated, they are used by process controllers at the individual pumping stations to control operations at the station. Measured values of the station\s performance are compared with the set points. If these values differ en

After the pumping station set points for a desired pipeline operation are calculated, they are used by process controllers at the individual pumping stations to control operations at the station. Measured values of the station\s performance are compared with the set points. If these values differ enough as to require a change in the speed of the compressors, the speed of the compressors then operating is then slowly changed (or ramped) so as to bring the pipeline into operation at the set points that were calculated. Ramping is performed so that the operating efficiency of the compressors is always maintained at approximately a predetermined level. If it is found that a change is required in the number of compressors being used, this is brought to the attention of the operator of the pipeline who must then decide to let the controller effect the change. At frequent intervals, each compressor is checked for surge and stonewall conditions. In the event a surge condition is detected, the compressor\s bypass valve is opened and the compressor is idled. After a suitable time delay, a test is made to determine if there is any speed at which the compressor can be operated for existing flow and compression ratios which will be on the compressor efficiency curve then being used. If so, the compressor is then loaded back on-line and ramped to the correct speed. If not, the operator is requested to permit operation of the compressor at a different efficiency level. If stonewall is present, it is necessary to put additional compressor units on line.

대표청구항 ▼

In a pipeline for the transmission of gas, said pipeline having at least one pumping station where at least one centrifugal or axial compressor is used to pump gas through said pipeline, a method of changing the speed of said compressor from an initial value to a final value, said method comprising

In a pipeline for the transmission of gas, said pipeline having at least one pumping station where at least one centrifugal or axial compressor is used to pump gas through said pipeline, a method of changing the speed of said compressor from an initial value to a final value, said method comprising the steps of: a. measuring operating parameters of said pumping station and said compressor; b. calculating from the measured operating parameters the volumetric inlet flow at base conditions; c. comparing the volumetric inlet flow at base conditions and the head with set point values for said volumetric inlet flow and head; d. if a set point deviation exists, determining an incremental change in the speed of said compressor such that the operating efficiency of said compressor at said incremented speed approximately conforms to a predetermined operating curve extending between said initial value and said final value along which the operating efficiency of said compressor is approximately constant, e. incrementing the speed of said compressor in accordance with the increment determined by step (d), and f. repeating steps (a) through (e) until the speed of said compressor reaches the desired final value, whereby the operating speed of the compressor is caused to change along a predetermined efficiency curve.