Supplying homogenous mixtures of different gases in very different proportions, for use in calibrating analyzers or testing exhaust catalysts, involves using static mixer

摘要

The mixing chamber comprises a pipe connected to the main gas supply line, so that the gas flows along the pipe, and connected to the other gas supply lines via injectors, where the secondary gas flow is introduced into the main gas flow, and then into a static mixer in the extension to the pipe. An Independent claim is included for a device for synthesizing gaseous mixtures as above, with at least two gas supply lines, a flow regulator on each line, at least one computer-driven automatic controller to control the flow regulators and a mixing chamber into which the supply lines open. The injector is a jet injector producing an azimuthal flow effect at the periphery. The axis of the injector is at 90 deg with the axis of the pipe, an ejection end coaxial with the pipe and an azimuthal component of between 15 and 90. The static mixer has a first section forming a convergent part and then a divergent part; a second section with at least two contractions in the pipe, each obtained by radial crushing of the pipe in one direction, and out of phase with each other by 10 and 45 deg . A third section similar to the first comprises a convergence part and then a divergent part. The first and second sections of the mixer have a length of the order of an initial diameter, and each in pair of convergent then divergent parts the two parts have the same length at least a third of the initial diameter. The mixer does not have any elements protruding from the walls. The mixing chamber is surrounded by an external pipe with the injectors in the gap between the external pipe and the mixing chamber. The gases being mixed which have a risk of flammability are supplied in a different line.