Water-in-oil emulsifier and oil-burner boiler system incorporating such emulsifier

In an improved oil-burning heat-producing system which has a rated maximum firing rate and which includes a firebox, means supplying fuel-oil under pressure, means supplying admix water under pressure, an emulsifier for emulsifying said water into said oil in the form of small droplets, an atomizing burner adapted to atomize said water-in-oil emulsion into tiny globules in air and to project such atomized emulsion into said firebox, whereby water globules which contain one or more droplets become still more finely atomized by the rapid vaporization of said droplets, the improvement wherein:

• said emulsifier has an approximately cylindrical oil-flow throat of diameter D centimeters, carrying said oil in a given flow direction therethrough, and a multiplicity n of water-injection holes in said throat, each of smaller diameter d centimeters, extending approximately radially to said throat, said throat being located between smoothly converging and smoothly diverging generally conical flow surfaces which are substantially symmetrical relative to said throat;
• means in communication with said smoothly converging flow surface for imparting swirling movement to the oil flow in a direction at an angle to said given flow direction before said flowing fuel oil reaches said throat;
• and
• said throat is dimensioned and has a surface configuration such that even at maximum firing rate the oil-flow rate Q.sub.o (in cm.sup.3 /sec) through the throat is so reated to D (in cm) and to the oil's kinematic viscosity (in stokes) that the oil-flow Reynold's number Re.sub.0 is substantially less than 1200.

In an improved mixer for a passive emulsifier of the type which produces a two-liquid emulsion in the form of a first percentage mP of a first liquid dispersed in a second percentage dP of a second liquid by injecting said first liquid into a flow channel through which said second liquid is flowing, the improvement wherein:

• said mixer has a substantially-straight flow channel of generally round cross-section shape, said flow channel being substantially straight over a given length which is greater than about half the diameter of said round cross-sectional shape and said flow channel having a substantially constant cross-sectional area B over said length thereof, through which said second liquid flows;
• said mixer includes means adjacent said substantially-straight flow channel for imparting angular swirling movement to said second liquid prior to said second liquid reaching said substantially-straight flow channel, said angular movement being in a direction at an angle to the direction of flow through said substantially-straight flow channel;
• said flow channel being located between converging and diverging surfaces of said mixer;
• balanced injection-means is provided in said mixer, including one or more injection-openings through an inner wall surface thereof for injecting said first liquid into said substantially straight flow channel in at least six centripetal directions, to provide a substantially balanced inflow, the total injection area A of said balanced-injection-means, measured at the interior surface of said flow channel and parallel to such surface, being smaller than B;
• the ratio A/B of said channel areas in said mixer is larger than the ratio mF/dF of the desired emulsion, whereby the mean flow velocity of said second liquid in said flow channel is larger than the centripetal components of the injected velocities;
• and said mixer being connected to a combustion device on the downstream side thereof.

In an improved heat-producing system intended to be used at varying firing rates, and including a firebox;

• an atomizing oil burner for atomizing fuel oil by means of a gaseous atomizing medium and igniting it and projecting it into said firebox;
• means for supplying fuel oil, atomizing medium, primary combustion air, secondary combustion air, and admix water;
• a ganged-modulating-control arrangement for varying several flow rates together to conveniently and efficiently modulate the firing-rate (including appropriately varying at least the flow of fuel oil, primary and secondary air, and admix water) over a range of flows from a high flow rate (corresponding to the highest firing rate used) down to some substantially lower flow rate;
• and an emulsifier for admixing said water into said oil in the form of tiny droplets to thereby improve combustion, the improvement wherein said emulsifier comprises:
• a substantially round cylindrical throat, D cm in diameter, and .pi.D.sup.2 in cross-sectional area carrying said oil, said throat being substantially straight over a given length in the oil flow direction which is greater than about half the diameter (D) of said round throat, said throat haviing a substantially constant cross-sectional area B over said length thereof;
• means adjacent said throat for imparting swirling angular movement to said oil flow prior to said oil flow reaching said throat, said angular movement being in a direction at an angle to the oil flow direction through said throat;
• said emulsifier including a converging portion between said swirl imparting means and said throat;
• and
• balanced water-injection means, for injecting said water into said throat in six or more evenly distributed centripetal directions so as to provide a substantially balanced inward flow, said injection means including one or more injection openings through the inner surface of said throat.

Improved method of making a uniformly fine water-in-oil emulsion for use as a clean-burning and efficiently-burning fuel in an oil-burning system, by establishing and maintaining a substantially cylindrical oil flow, constrained by a substantially cylindrical internal constraining surface of diameter D in an emulsifier body, and simultaneously injecting a multiplicity of water streams of a smaller diameter d approximately radially into said oil flow;

• the improvement wherein:
• said internal constraining surface is oil-wettable;
• converging the flow of oil into said constraining cylindrical surface;
• and
• providing a swirl-imparting means upstream of said constraining substantially cylindrical internal surface of diameter D for imparting a swirl to the oil flow prior to said injection of water.