GB1423732A - Pressure control apparatus and method - Google Patents

Abstract

1423732 Automatic control of pressure TEXACO DEVELOPMENT CORP 25 Jan 1973 3768/73 Heading G3R In a catalytic reforming unit for producing hydrogen, the pressure in a separator 1 is maintained at a substantially minimum pressure to provide economical operation. Gas drawn from the separator is split into two streams, one through a feed pre-treater reactor 20 and product separator 30, and the other through an absorber 10, the hydrogen outputs of the two streams being combined at 34. The pressure at 34 is measured by a transducer 50 and the signal PH is summed in 52 with a minimum differential pressure signal P 1 from a source 58 to produce a signal PA from which is subtracted at 53 a signal representing pressure Pp in separator 1, the output being fed to a comparator 61. Similarly, a signal PR representing the input pressure to reactor 20 is summed at 63 with a further minimum differential pressure signal P 2 from source 58, and a signal representing the output pressure PD of a compressor 7 is subtracted in 67, and this output is fed to comparator 61. The greater of the outputs from 53,67 passes to an integrator 71 via a switch 60 or 60A, and is added at 72 to a pre-set signal V3 from source 58, the resultant signal E 12 controlling the set point in a pressure controller 38 and thus the pressure in separator 1. In an alternative embodiment, (Fig. 2 (not shown), the signals are converted to digital signals and fed into a computer to produce an error signal is converted to analogue set point signal for controller 38.