Back Pressure Regulator for Two-Phase Flow

Mixed Phase - Gas and Liquid - BiPhasic Flow

The unique design of the Equilibar® back pressure regulator gives it the ability to handle two-phase or mixed-phase flow streams while maintaining high precision. This can include gas/liquid processes, water/oil flow streams, or applications with gas, brine, and oil all together.

Common applications for two-phase flow include laboratory reactors for petrochemical catalyst research and fuel cell and fuel cell testing systems involving condensation.

Traditional back pressure regulators use a single annular valve seat, often very small. When slugs of liquid flood the valve throat, volumetric flow rate drops suddenly as the denser fluid is accelerated through orifice. This momentary reduction in volumetric flow disrupts the stability of the upstream process pressure.

The unique Equilibar technology uses a direct sealing diaphragm over multiple orifices to control the pressure drop (see how it works). The valve action is not provided by the movement of a tapered stem, but by the close proximity between the diaphragm and the orifice plate. The supple diaphragm can vary its proximity to the orifice nearly instantaneously to adjust to the varying valve coefficient (Cv) requirements of the various phases.

A further benefit is provided by Equilibar’s unique multiple orifice design. Even if one orifice is totally flooded by the denser liquid, volumetric flow control can still be maintained so long as some of the orifices are still predominantly in the gas phase.

Application Focus: Two-Phase Flow in Petrochemical Catalytic Reactor

schematic showing back pressure regulator used for two-phase catalytic reactor control

Laboratory reactors in the petrochemical sector, such as in catalyst research often have mixed phase outflow. In order to use a single phase back pressure regulator, it is necessary to install a liquid separator upstream of the back pressure regulator. However, depending on the pressure range and size requirements, this separator might be very expensive and meet ASME Boiler and Pressure Vessel code. The liquid outflow will likely require a level control system.

One issue that should be considered is that of fine mists and aerosols when two-phase flow is reduced from a high pressure. Depending on the surface tension and other fluid characteristics, the separations process can be made more difficult.

Where applicable, the use of the Equilibar back pressure regulator in mixed phase application can significantly reduce the cost and complexity of your laboratory reactor process.

Equilibar EB1HP1 can be used for mixed-phase laboratory applications
Equilibar back pressure regulators can simplify reactor pressure control by working with two-phase flow. 1/8″ EB1HP1, rated to 5000 psig, is shown above. See product details for all Equilibar back pressure regulators.

two phase flow

Download our product brochure for laboratory and research regulators.