GB1270053A - Device for statically measuring the mean density of a liquid circulating through a system of conduits - Google Patents

Abstract

1,270,053. Apparatus for measuring density of flowing liquids. SOC GENERALE DE CONSTRUCTIONS ELECTRIQUES ET MECANIQUES (ALSTHOM). June 22, 1970 [June 27, 1969; Nov. 28, 1969; April 9, 1970], No.30236/70. Heading G1S. Liquid hydrocarbon tapped from a conduit 31 via a pressure reducing valve 33, enters a tube 44 or first column and overflows at its top 35 into a return pipe 37. A reference liquid within an inner tube or second column acts against a membrane 45 separating the liquids and balances the head of the liquid hydrocarbon in the outer tube. Should the density of the hydrocarbon alter, then the equilibrium or balance of the liquid columns is disturbed and the position of a deep float 46 alters because of the different pressure head acting on the membrane 45 and operates a lever 47 which controls an electric motor 38, which motor raises or lowers the movable tank 36 and the surface N' of the liquid hydrocarbon to rebalance the liquid columns. The movement of the tank 36 necessary to adjust is read off on a gauge 43 to indicate the density alteration. In Figs. 1-3 (not shown) the columns are separate instead of concentric and slightly different ways of equalizing the levels N and N' are described, the lifting and lowering of the tank being carried out by a piston servomotor (22) for example, or the lever mechanism operated by the float being used instead to control the opening of a valve (25) Fig. 4 (not shown) regulating admission of hydrocarbon into the top of the first column. In Fig. 6 the fluid to be measured flows via pipe 52 and valve 53 into an upper overflow 56 of a movable tank, the overflowing liquid returning via pipe 57. The base of the first liquid column 54 is however connected via a flexible pipe 66 to a second overflow 65 so that there is a circulation of liquid downwards in the column 54, up the conduit 66 and out of the overflow 65, this circulation being effected with a constant pressure loss which is independent of the variations in flow-rate and so on. A concentric reference liquid tube and diaphragm are provided as before, but the constant loss of pressure due to the downward flow in the column 54 must be allowed for and this is determined by closing the valve 67 to stop the circulation and measuring the static height of the column to find the difference between this static reading and the circulatory reading. The corrective term thus determined must be subtracted from the normal reading obtained from the difference of the levels N, N' as read from the gauge 63.