US2389488A - Method of agitation of pickling baths - Google Patents

Description

Nov. 20, 1945. w. H. DAILEY, JR 2,389,438

1 METHOD OF AGITATglON OF'PICKLING BAilHS Filed Nov. 24, 1942 2 sheets-sheet 2 INVENTOR MLL/AMAMA/L EKJQ,

Patented Nov. 20, 1945 2,389,488 METHOD or AGITATION F momma BATES William H. Dailey, In, Library, Pa.

Application November 24, 1942, Serial No. 466,813 1 Claim. Cl. 261-121) This invention relates to an improved method of, and means for effecting agitation of a liquid bath by means of the energy of steam preferably at high pressure.

The invention relates more particularly to a pickling bath in which the steam adds heat to the bath to keep it at the desired temperature and also agitates the bath. Heretofore, submerged jets of high pressure steam alone or submerged jets of air alonehave been used for agitating a bath. Also high pressure steam has been used to inspirate air through submerged jets, but in these prior practices there has been no definite intimate and controlled mixing of high pressure steam and a non-condensable gas before introduction thereof into the bath. By forming a homogeneous mixture of non-condensable gas and steam, the partial pressure of the steam in the mixture is decreased, this decreasing the comdensation temperature so that more of the energy of the steam is utilized in the form of energy of motion which produces increased agitation of the liquid bath. If superheated steam is used, it is apparent that more energy will be available for agitation. It is possible to increase the proportion of non-condensable gas until the condensation temperature of the steam is below that of the temperature of the bath, in which case none of the energy of the steam would be transferred to the bath in the form of heat. Since it is necessary to add heat to the pickling bath by means of the steam, this condition is not desired.

One of the objects of the present invention is to provide an improved method and means for agitating a liquid bath by using a mixture of steam and a, non-condensable gas which are intimately mixed under controlled conditions of temperature, pressure and relative amounts, before being conducted to the liquid bath.

Another object is to so control the relative amounts of steam and non-condensable gas supplied to a pickling bath, that the steam will add the desired amount of heat to the bath and agitate the bath as desired.

One selected embodiment is shown in the accompanying drawings, and described in the following specification, for purposes of illustrations, and is not necessarily to be construed in a limiting'sense, as various features and arrangement of parts have been shown in more or less diagrammatical form for purposes of explanation and illustration of the method.

flu the drawings:

Figure 1 is diagrammatic view showing a liquid bath, and a single duct, having at its lower end a submerged nozzle at the bottom bath and di-[ rected so as to eject a stream of mixed gases substantially parallel with the bottom of the bath receptacle to induce agitation and circulation of the liquid. At the upper end of the duct is shown a plurality of ducts, one for steam, and the other for air, the direction of flow of the gases being indicated by the different arrows;

Figure 21s a, diagrammatic view showing a general arrangement of the ducts for the air and steam line supplies, indicating an arrangement of the various control instruments, gages, control valve, and expansion nozzle, and also an elevation view of the tank or receptacle containing the liquid bath and indicating one arrangement of the supply line and nozzles therein for injecting the mixture of gases within the liquid bath, and represents generally side elevation of Figure 3 with the right side of the tank removed;

Figure 3 is a section taken on the line, and looking in the direction of the arrows IIIU.I of Figure 2;

Figure 4 is a fragment in section showing one form of steam line'orifice and a means of securing the same in position at the end of a steam or other line where expansion may occur; and

Figure 5 is a fragment in section, indicating one form in which a series of nozzles with an orifice in eachnozzle may be positioned in the wall of a duct delivering the gas to the liquid bath.

In the drawings showing one selected embodiment and relative arrangement of partsin more or less diagrammatic form to illustrate the method, a tank or liquid receptacle l is shown containing a liquid bath 2 which may be, for example,

a suitable pickling liquid. A single conduit or supply pipe conducts a gaseous mixture including steam and a non-condensable gas such as air, to the liquid bath where the mixture of gases is injected into the liquid bath in such a manner as to utilize most effectively the energy of the steam, in the form of kinetic energy of motion to efiect agitation of the liquid bath to facilitate the pickling operation.

One of the factors contributing towards this end is, not alone the conditions for effectively controlling the conditions u'nder which the steam and the air are mixed together, but include also the number, and the relative disposition of the injecting nozzles, together with the relative direction to which they deliver the mixed gaseous stream to the liquid-in the tanks. This latter element, of the direction of the stream of mixed gases, also has an important relation with respect is t pa ticular part of the tank with relation to the bpttom and sides of the tank, which latter parts in turn have relation to the particular character and direction of the currents and circulation of the liquid bath which are set up and induced in effecting agitation of the liquid.

As shown in Figures 2 and 3, the mixture of gases conveyed in the pipe 3 includes air as the preferable non-condensabie gaseous constituent which is supplied by the pipe 4. Suitable controlled devices well known in the art, may be employed in the air line and may include a. suitable control valve It, a flow meter ll such for example as a rotameter of the Fischer and Porter type, and a pressure gage iii. A check valve I! may also be supplied in the air line I which conducts the air, as the non-condensable gaseous constituent, to the main gaseous supply line 3 at the point where the steam supply line or conduit 5 connects with said main supply line 3. The

main air supply line is indicated by the reference character 4A directed to a pipe line or conduit which conducts the air in the direction indicated by the arrow to the rotameter l4.

The steam supply may be obtained from a suitable source at a suitable temperature and pressure, and may be in suitable degree of superheat as desired, in order to more effectively utilize the energy of the steam as kinetic energy of motion to induce agitation, without necessarily changing or lowering the sensible heat of the steam, and if the sensible heat is lowered, to more effectively utilize the steam energy for purposes of agitation of the liquid bath, before the temperature of the steam has been reduced to a point of condensation. Suitable control instruments and devices may be provided for the steam line in order to control the pressure temperature and relative amounts by volume or weight of the steam' which is mixed with the non-condensable gas such as the air, to obtain the gaseous mixture of the 40 desired pressure and temperature.

As shown in F1 ure 2, a suitable temperature controller I8 is provided and may utilize aconventional form of thermocouple I9 which may be disposed in the liquid bath 2 in order to reflect and control the temperature thereof, which temperature control mechanism 18, which may be of a conventional and well known type, may in turn actuate a, valve control mechanism 20 to control the supply of steam. The steam valve control mechanism 20 may be of the solenoid type.

Suitable flow limiting orifices 2|-2|A may be provided in the steam line between the portion 5 and 5A thereof. As shown, the said orifices are disposed imparallel disposed branches 22-22A of the steam line, the steam orifice 2| being disposed in the branch 22 in which the automatic control element 20 is disposed, and the orifice 2 IA is in the branch 22A in which a manually controlled valve 23 may be disposed. Such an arco rangement provides a means for effecting a flexible and wide range of steam control to suit various conditions which may be met.

Other accessories desirable for use include, a

vacuum release valve 24 to prevent liquid in the bath from backing up through the pipe system when steam and air are turned off, and a safety valve 25 to limit the pressure in the system to a predetermined safe value; Each of these valves may be of a conventional type well known in the art. If desired,a control valve 26 maybe provided in the main pipe line 3 for controlling the amounts of the mixed gases conducted to the liquid bath through the single pipe or conduit 3.

Referring to Figure it is noted that @1 6 1 0 18 I2 is one of a series of nozzles disposed in the pipe line I l which conducts the mixed gases from the main pipe line 3, to the elector nozzle l2 shown preferably as disposed near the bottom of the liquid bath, so that the pressure existent in the liquid bath at the point of discharge of the mixed gaseous stream, is at. a pressure greater than the atmospheric pressure at the surface of the liquid bath, the increase of such pressure representing the increase due to the hydrostatic head due to the distance which the nozzles are, below the surfaces of the liquid bath. It is noted that the nozzles l2 discharging the gaseous mixture from the pipe ll, eject the gaseous stream in a direction substantially parallel with the bottom of the tank or receptacle l although it may have a slight angular disposition, either up or down. Of course, throughout this zone, that is a zone substantially parallel with and immediately above the bottom Of the tank, the pressure would be at a common and higher pressure, than at any point thereabove and nearer the surface of the liquid bath. The significance of this feature is, that the boiling point would behigher throughout this zone at increased pressure,

The nozzles IS in the pipe I0, which receive the mixed gases from the main supply pipe 3, are preferably so disposed as to direct the ejected stream of mixed gases substantially upwardly adjacent the right hand side of the tank, as shown in Figure 3 particularly, where the location of the nozzles i are as indicated therein, namely, adjacent the right side of the tank and near the bottom thereof, and disposed at the opposite side of the tank-from that in relation to the nozzles I2, which are disposed as indicated, near the bottom of the liquid bath and adjacent the left wall as shown in Figure 3. It is to be noted that while the direction of the ejected stream of mixed gases, as indicated at IZA, is in a zone of substantially the same pressure, such a condition favors the maintenance of the steam in its noncondensable condition and thus favors a slow rate of condensation of the steam. On the other hand, the nozzle l3 directed upwardly, projects the stream of mixed gases I3A upwardly, so that the pressure is continually varying as the stream progresses upwardly throughout the liquid bath and approaches the surface thereof. As previously indicated such varying pressure would be due to the varying hydrostatic head due to the varying distances below the surface of the liquid bath. Through the control of conditions, relative the temperature of the bath, and the temperature and relative amounts of steam ejected into the liquid bath, the proportion of jet energy used for agitation of the bath may be varied throughout wide limits as previously indicated. With a jet submergence of 4 ft. approximately 12% by volume of non-condensable gas such as air is required to completely suppress condensation of the stream; in actual practice the percent of non-condensable gas would be lower than this to allow some heat into the bath. By adding sumclent non-condensable gas the condensation temperature may be lowered to or below the temperature of the bath so that no condensation takes place and a large contact surface between heat and bath is maintained, thus greatly increasing the amount of energy used to agitate the bath. Preferably, with reference to the relative quantities or amounts of the gases which may be employed,'a satisfactory relation has been found to be one in which, for example, the steam may vary from 88 to 99% by volume approximately, where the steam may be delivered from the steam header at 180 lbs. per square inch, and the non-condensable gas, such as air may be delivered from the air header at a pressure or 100 lbs. per square inch and the relative quantity or air by volume. may vary from 1 to 12%.

Under an assumed condition above referred to,

in which the tank might by 4 it. in depth, the

absolute pressure at the top surface of the liquid bath may be 141 6 lbs. per square inch with a or conduits to withstand the corrodin-g eifect from the acid pickling solution.

Figure 4 shows a means of mounting a steam orifice 41 at the end of a conduit 28. As shown, the orifice may be suitably recessed at one end to set within the aperture of disc 28, which disc may be retained on the end of the. conduit 28 by means of a shouldered annular flangejil threaded on the end of the conduit 28. It is, of course,

understood that other suitable means may be employed for positioning or mounting the orifice 21, either at the end or or within a pipe.

Figure 5 is a fragment showing a modified form of orifice, and secured in a diflerent relation, such for example, as in the side wall oi a pipe. The orifice 21A may be secured in the side wall of the pipe 28A in any suitable manner either by pressing or threading or by other well known means. A series of ejector orifices 21A may be distributed throughout thelength of the pipe 28A.

While one preferred form has been shown and described for purposes of illustrating the method, it is understood that various changes and modiflcations may be made within the knowledge of those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claim.

I claim:

The method of agitating apickling bath and controlling the temperature thereof which comprises forming a homogeneous mixture of steam and a gas non-condensable at the temperature 01 the bath, conducting said mixture to said bath, introducing it into said bath, and regulating the flow of both gas and steam to control the proportion of the non-condensable gas to the steam prior to entry of the mixture into the liquid bath to retard the rate of condensation otlthe steam in order to obtain the desired agitation and temperature of the bath.

WILIJAM H. BAILEY. JR.

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