FR2488815A1 - LIQUID SPRAYING DEVICE AND ITS APPLICATIONS - Google Patents

Abstract

DEVICE FOR SPRAYING A COMBUSTIBLE LIQUID OR NOT BY MEANS OF AN AUXILIARY GAS UNDER PRESSURE, CHARACTERIZED IN THAT LIQUID 11 AND GAS 12 ARE MIXED IN A SAME AXIAL ENCLOSURE 13, BY OPPOSITE ROTATIONAL MOVEMENTS, THE GAS MIXTURE LIQUID OBTAINED THEN DELIVERED THROUGH AN APPROPRIATE ORGAN.

Description

The subject of the present invention is a device for spraying a

  liquid combustible or not by means of a

  pressurized auxiliary gas comprising means for effecting

  kill the mixture of the two fluids by rotational movements

  opposite oppositions followed by a system allowing the relaxation of the

  mixing through at least one suitable organ.

  The invention extends to the applications of this provision.

  particularly when spraying heavy fuel oil or any combustible oil in low pressure drop burners

  and spraying any liquid for drying.

  In refinery burners, of the "induced air" type, generally used for spraying fuel oil is pressurized steam which, in a first step, is mixed with fuel oil in a mixing chamber, then, in

  a second step, the mixture is expanded through a nozzle.

  The orifices of this nozzle are appropriately drilled in the burner and the expansion through these orifices causes the fuel oil to be sprayed:

  - the number of orifices generally varies from 6 to 15.

  - Their diameter is chosen according to the desired fuel flow rates and so as to obtain the best quality of combustion. - generally, these orifices are geometrically arranged so that their axes are distributed over a cone whose opening angle is an important parameter for the shape

of flame.

  As can be seen in Figure 1 showing in section a conventional sprayer, the system performing the

  steam-fuel mixture is sketchy. In fact, fuel is intro-

  supplied by the axial pipe 1 and the vapor by the concentric pipe 2. The mixing takes place in the chamber 4 where the fuel enters through an orifice 5 of 2.5 cm in diameter and the steam

  by 3 holes, 3, 2.3 cm in diameter, the trigger and the spray

  They are made through the 6 holes, 6, 2.5 mm in

nozzle diameter 7.

  Under these conditions, the state of division of the two fluids into one another cannot be fine, which is detrimental to obtaining a fine spraying of the fuel after expansion.

in the nozzle.

  In addition, this type of sprayer must, in order to achieve a satisfactory spraying for combustion, operate under conditions such that the vapor flow rate / fuel flow rate is between 25% and 60%, depending on the fuel flow. FIG. 2 shows a curve giving the ratios in% of the mass flow rate of steam to that of fuel oil as a function of the fuel flow rates in kg / hour of a JOHN ZINK sprayer. This ratio is the determining factor in the operating cost of a sprayer and all development efforts tend to reduce it, while improving

  the efficiency of the steam-fuel mixer.

  Thus the company ESSO in its certificate

  of addition 74 29594 to patent 73 41639 of 22.11.73, has

  a sprayer in which the fuel oil vapor mixture is obtained with a static mixer, comprising a series

  of organs having the function of imposing on fluids

  multiple changes of direction and shear forces.

  For its part, the JOHN ZINK Company perfected the mixing system by profiling the mixing chamber and introducing the steam with a rotational movement, the

fuel being introduced axially.

  According to the invention, the mixture is further improved by introducing the two fluids into a

  mixing, the two fluids being driven by rotational movements

  opposing tion creating turbulent flow, conducive

to the mixture.

  In practice, FIG. 3 shows an embodiment of the invention: the fuel enters through a conduit

  cylindrical it and steam through a cylindrical conduit co-

  axial 12. These two fluids enter the mixing chamber 13 through orifices 14 and 15 drilled in the wall of

the mixing chamber.

  The mixing chamber 13 is screwed to the end of the fuel pipe 11, and is co-axial with it. Its widest diameter is equal to the diameter of the steam pipe, which seals the steam circuit. Inside, the mixing chamber 13 is of cylindrical or truncated conical shape, of length between 5 and 100 mm, the opening angle of the cone being less than 40 degrees and of

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  generally suitable for the burner and the desired form of flamine. The fuel orifices 14 are arranged so that their axis is perpendicular to the axis of the mixing chamber, but is not intersecting with it, so as to communicate

  fuel oil rotational movement in the mixing chamber.

  The steam orifices 15 are arranged in a similar manner,

  but in order to impart a rotational movement to the steam

  tion in the mixing chamber opposite to the rotational movement

tion of fuel.

  By way of nonlimiting example, the orifices 14 of fuel are two in number, with a diameter of 1.5 mm, in order to allow a fuel flow rate of up to 150 kg / h with fuel pressures not exceeding 8 bars, and ports 15

  are two in number, 2.0 mm in diameter.

  FIG. 4 represents the arrangement of the orifices 14 when looking at the mixing chamber from a point A situated on its axis, outside the narrowest side of the chamber; seen from point A, the direction of rotation of the fuel is opposite to that of the hands of a watch. Likewise, FIG. 5 shows the arrangement of the orifices 15 when looking at the mixing chamber of point A defined above. Seen from this point, the direction of rotation of the steam in the chamber

  of mixing is that of clockwise.

  The spraying device according to the invention, produced according to prototypes 4 and 5, was tested on a bench compared to the conventional devices EA7 and LS by JOHN ZINK, as can be seen in FIG. 6 in which the ratios in% are represented. from the mass flow of steam to that of fuel as a function of fuel flows in kg / hour. It can be seen that the sprayers according to the invention make it possible to obtain consumption of steam.

  - significantly lower and independent of fuel flow.

  In addition, observation of the flame reveals that the quality of combustion is better and the ratio of maximum fuel flow rate / minimum fuel flow rate is 4 to 5 while it is

  of 3 for the JOHN ZINK LS system.

  Finally, the maximum fuel oil pressures required are of the order of 8.1 bars while the ESSO device

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  requires a fuel pressure of 14 to 16 bars, which con-

  traitor to equip the refinery with an additional booster

  to hush up. The sprayer according to the invention has, as has been demonstrated, the advantages of being of a simple technological design, of allowing a significant saving of steam, of presenting a greater flexibility, of giving a better quality of combustion. and to be usable at fuel pressures compatible with the availability of

refinery.

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Claims (5)

  1 - Device for spraying a combustible liquid or not using an auxiliary gas under pressure, characterized in that the liquid and the gas are mixed in the same axial enclosure by opposite rotational movements, the gas-liquid mixture got then being relaxed through an appropriate organ.   2 - Device according to claim 1 characterized in that   the liquid is a fuel and the gas water vapor heated or not.   3 - Device according to claims 1 and 2, characterized in   that the rotational movement of the fluids in the axial enclosure is obtained by bringing said fluids into the enclosure by means of cylindrical channels in the wall of the enclosure, the axis of these channels and that of the enclosure n ' not being intersecting.   4 - Device according to claims 1 and 2 characterized in   that the mixing enclosure is of cylindrical or truncated conical shape, of appropriate length and opening angle.   - Device according to claims 1 and 2 characterized in   that the channels introducing the fuel into the mixing enclosure are cylindrical, of appropriate diameter and number, and the channels introducing the vapor are   also cylindrical, of appropriate diameter and number.   6 - Device according to claims 1 and 2 characterized in   that the member which produces the expansion of the fuel oil mixture is a nozzle provided with cylindrical orifices of appropriate number and diameter, the axes of these orifices being regularly distributed on a cone co-axial to the mixing chamber and the opening angle is suitable for the burner and the desired flame shape.