Method and system for determining vapor pressure or composition of hydrocarbon liquids

摘要

The bubble point pressure, vapor pressure and liquid composition of hydrocarbon liquid flow streams is determined by causing the liquid flow stream to flow through a system having a plurality of eductors at selected various total pressure differentials across the eductors and measuring the pressure at the minimum pressure point or suction port of the eductors to obtain a reading of the vapor pressure. The system may comprise an array of three or more eductors arranged in parallel having flow regulating valves for controlling the flow rate and pressure drop across the eductors, respectively. The system may also comprise one eductor connected to a plurality of flow lines, each having flow control and/or shutoff valves arranged to provide for selective control of the flow rate and the resultant total pressure drop. Comparative data may be obtained for determining the liquid composition at a particular temperature based on the vapor pressure characteristics of known ranges of liquid compositions expected from the fluid stream being measured.