Importance

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Abstract

A direct contact steam injection heater includes a Mach diffuser having a plurality of steam diffusion holes in lieu of a coaxial steam nozzle. High velocity steam (i.e. choked flow) flows radially through the plurality of steam diffusion holes into a high velocity axial flow of liquid through a combining tube within the heater. An adjustably positionable cover over the steam diffusion holes in the Mach diffuser modulates the amount of steam added to the liquid by exposing the proper number of steam diffusion holes. This modulation is done at constant steam pressure without the use of an external steam control device. The arrangement facilitates thorough mixing of steam and liquid within the combining region. It also discourages the generation of relatively large steam bubbles within the mixture, even when heating liquids that promote the generation of relatively large steam bubbles such as liquids without a significant number or nucleation points or without sufficient surface tension. Upon condensation of steam in the heater, relatively large steam bubbles tend to cause vibrations in the heater and adjacent plumbing. The invention substantially eliminates this source of vibrations.

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First Claim