US2673797A - Method of preventing clogging of the hydrogen inlet to a reducing zone in the reduction of ferrous chloride vapor by hydrogen - Google Patents

Description

March 30, 1954 P. WHITEHOUSE ETAL 2,673,797

METHOD OF PREVENTING CLOGGING OF THE HYDROGEN INLET TO A REDUCING ZONE IN THE REDUCTION Olj FERROUS CHLORIDE VAPOR BY HYDROGEN Filed Jan. 17, 1952 IN VEN TORS frw'qf J. WkJe/muse BY Edward 12 find/6r EM JOB'WAW Patented Mar. 30, 1954 METHOD OF PREVENTING CLOGGING OF THE HYDROGEN INLET TO A REDUCING ZONE IN THE REDUCTION OF FERROUS CHLORIDE VAPOR BY HYDROGEN Irving P. Whitehouse, South Euclid, and Edward A. Beidler, Columbus, Ohio, assignors, by direct and mesne assignments, to Republic Steel Corporation, Cleveland, Ohio, a corporation of New Jersey Application January 17, 1952,. Serial N0. 266,828

5 Claims.

The present invention relates to a method of preventing clogging of the hydrogen inlet to a reducing zone in the reduction of ferrous chloride vapor by hydrogen and, more particularly, such clogging incident to the accumulation of an adherent. deposit at and adjacent to the hydrogen inlet into such a reducing zone. This clogging tends, in a period of time, to restrict and eventually to plug this inlet completely. It has been found, in practice, when reducing ferrous chloride vapor in a reducing zone with hydrogen, which is separately introduced into this zone, that a collar of adherent material builds up around the end of this inlet, which collar is gradually lengthened; and the aperture therethrough is gradually constricted until the hydrogen inlet is eventually plugged. This collar appears to be composed of a more or less sintered body of metallic iron with some solid ferrous chloride therein. If the operation were to be carried on only for a relatively short time and then the inlet mechanically cleaned in some suitable manner, the difficulty which thisinvention seeks to overcome would not be of serious nature. This, however, is difficult to accomplish during the continued operation of theapparatus and without disassembly thereof. In the normal operation of the general process of substantially continuously reducing ferrous chloride vapor with hydrogen in 'asubstantially closed reduction zone, as set forth, for example; in the copending application of Crowley et' al., Serial No. 214,632, filed March 8, 1951, and entitled Process of Reducing Ferrous Chloride inthe Gaseous Phase With Hydrogen to Produce Metallic Iron, the need for the method ofjthe present invention is apparent, as this process cannot be carried out continuously without, in some.

way overcoming the difficulty of plugging the hydrogen inlet. The; present invention presents a preferred method of accomplishing. this result.

Another undesired effect of the operation of the process of the Crowley ,et' all application, when the method herein described is not utilized therewith, is that the collar, which is formed as aforesaid, around the hydrogen inlet, often does not grow in a direction parallel to the desired direction of the hydrogen stream, and, therefore tends to deflect the hydrogen stream, so that the'desired impingement of the stream with the stream of ferrous chloride vapor no longer occurs at the predeterminedpoint in the reduction zone spaced from" both nozzles and from the walls of thereduction *zone. For example, if

the point of impingement :of: these streams were 2. changed by deflecting the hydrogen stream so that this point were too close to a wall or the chamber, the resulting solid material, princi pally metallic iron" in powdered form, would tend to collect on the walls of the chamber of the reducing zone and adhere thereto in a manner interfering progressively with the desired operations. The presentv invention, therefore, has as one of its objects, the prevention of these undesired operations.

Summarizing the present invention, therefore,

, inlet hydrogen should not be over about 1000 F. It may be almost any amount cooler than that, although normally it is never introduced below room temperature due to practical difiiculties of cooling the hydrogen. In practice it is preferred to cool the hydrogen with availablecooling water from any" available source of water at whatever low temperature can be obtained for the hydrogen by such cooling. For example,

temperatures around 160 F. have been easily obtained for the incoming hydrogen and have been found to be eminently satisfactory in operation. As the temperature of the hydrogen or hydrogen-containing gas rises, some difliculties' are met with along the lines above outlined, so

that when the temperature of the incoming hy-' drogen is raised to about 800 F. one may expect to encounter some difficulties Whenthe temperature of the incoming hydrogen reaches over about 1000 F., the difficulties are so pronounced that continuous operations above about this temperature are considered undesirable and are not included in the purview of the present invention.

The temperatures of the hydrogen-containing gas as aforesaid are relatively cool in respect to the average temperatures existing within the reducing zone, which should'be maintained by suitable means sufficiently high so that the vapor pressure of' ferrous chloride will be substantial. For this purpose, the average temperatures in the reducing zone should be at least about 1250 F. Preferably, however, the average temperatures in the reducing zone-will be such that" fera rous chloride'present will be maintained substantially all in vapor form- 1. 6., about 1800 F. to about 2000 F;

As: generally suggested above; the present invention is an improvement upon the general process disclosed in Crowley et al. application, Serial No. 214,632. -As a result, a detailed description of the basic process will not be repeated here. For the purpose of the present invention, the basic process may be said to be one in which ferrous chloride vapor is supplied from-a suitable source thereof into a reducing zone, usually, but not necessarily admixed with some one or more relatively inert carrier gases. Hydrogen is separately supplied to this zone. This hydrogen also may or may not be admixed with some one or more inert gases. When inert gases are spoken of in this respect, what is meant in any gas or gases which are either inert per se, such as nitrogen, or which are inert insofar as the process or processes contemplated and possible are concerned, so that any amount of such inert gas which may be present will not in any way interfere with the reactionwhich is to take place.

-It has been found that ferrous chloride and hydrogen under the conditions present in the reducing zone as herein described will react to gether very rapidly, according to the equation:

It has further been found that this equation will not proceed normally to 100% completion, but rather will proceed toward some intermediate equilibrium. The numerical value of this equilibrium will depend upon the average temperature in the reaction zone. However, up to that equilibrium the reaction occurs very rapidly under the conditions presently contemplated. This reaction introduces the difficulties discussed above and which are overcome by following the teachings-of the present invention.

- It has been found that the reaction set forth above is somewhat. exothermic in character. In addition to the heat available from the reaction, it is usually desired, in accordance with the present invention, that the necessary heat required to maintain desired average temperatures in this zone be introduced primarily as sensible heat in the ferrous chloride vapor and/or any inert gas introduced therewith. Thus there is no need for the hydrogen-containing gas to be introduced at a high temperature. It is sometimes desirable to supply some heat externally tolthe .walls of the reaction chamber.

For thepurpose of the present application, it has beenfound that. this hydrogen-containing gas should preferably be-introduced ata relatively low temperature in respect to the average temperature in the reducing zone, so that reaction does. not occur until the hydrogen-containing gashas cleared its entrance. port by an appreciable distance... By 'maintaining the hydrogen ata low-temperature as. it enters the reactor, the equilibriumfor the reaction by which iron is produced is. such that no appreciable deposit will form.

The first feature of the present invention to be discussed in detail is the temperature for the introduction of .the hydrogen-containing gas. Due to the fact that the temperature desired is that of hydrogen as it actually enters into the reducing zone, and as it is practically impossible to determine this temperature per se in an accurate manner by any available means due to e3;- ter-nal influences of an uncontrollable nature, it has been customary in carrying on the process of th e=presentinvention to introduce hydrogen through a 4" O. D. tube of good heat conducting material; as copper, and: having a bare uniniii! sulated portion extending about A" into the reducing chamber or zone. A thermocouple is used for sensing an index temperature, with its junction point in the hydrogen stream inside of this tube and at a point about /8" from the exit end thereof. In one apparatus used the tube extended substantially vertically down into the reaction chamber and the thermocouple was suspended by its connecting wires in the tube as described. The index temperature as measured by this thermocouple is reasonably characteristic of the temperature of the hydrogen and is believed to be some function thereof, although the exact function is not known.

It is recognized that the index temperatures recorded by the thermocouple used under these circumstances will be affected by radiation from any source to which the thermocouple is exposed in use, including some of the walls of the chamher-defining. the reducing zone, the walls of-the end portion of the hydrogen inlet tube and also some of the solid particles of iron in the reducing zone. The indicated temperature will be influenced by convection heat transfer from the hydrogen flowing into the reducing zone. However, it has been found in practice that the temperature as measured by this thermocouple is fairly indicative of the temperature of the hy drogen to the extent that when the temperature measured by this thermocouple is within a cer-v tain range, or at least below 1000" F. as herein provided, the operations may be carried on in accordance with the present invention. I

In order that the hydrogen be admitted to the reducing zone at a temperature, measured as hereinabove set forth, which will be within the desired range in accordance with the present in: vention, it has been found necessary to limit the heating up of hydrogen during its passage through thewalls of the reducing zone or chamber. .In some cases, hydrogen may be available substantially at room-temperature. As such, it is initially at a temperature which is sufiiciently cool to be effective in accordance with the present invention. In fact, the present invention contemplates the use of hydrogen at temperatures substantially above room temperature as herein specifically set forth. On the other hand, it has been found that if some means were'not used to limit the heatin up of hydrogen during its passage through the walls of the reducing'zone, the hydrogen will be heatedto such a high temperature that the desired results in accordance with the present invention will not be attained. This will be evident from examples hereinafter given.

One way of preventing this undesired heats mg up of the hydrogen is by the provision of suitable insulation. Another, and in .many, re-I spects an analogousway, is by preventing the transfer of heat to the hydrogerl during its passage through the walls by providing an inter-. vening circulation of a cooling fluid in an annular space surroundingthe hydrogen inlet, so as to conduct away heat which would otherwise be transmitted to the hydrogen to heat it up to an undesired extent. For this purpose, then, such a circulation of cooling fluid may be utilized in accordance with the present invention as hereinafter more particularly described in connection with the drawings forming a part of this application.

From a broad point of view, the desired temperature for the hydrogen-containing gas, measmedias-described, is-any temperature not over about 1000? F. There is no critical ilower limit to this temperature. The high temperaturezlimit of about 1000 F: is. chosenasnathat at whichxthe difficulties above set. forth become so great that the continuous operation of the process ceases to be possible by reason'of these. diiiiculties.

From a more specific point of view, apreferred range of temperature'for the hydrogen-containing gas, measured as aforesaid, is from. about 300 F. to about 400 F. The preferred limits are chosen as thoseat which thehydrogen may be available, for example, by cooling with available cold water andwithout introducing excess cost for refrigeration. There is nothing critical about these limits.

In some operations. such as those set forth, for example, in the copending application of Crowley, Serial No. 2243770, filed May 5, 1951, and entitled Integrated Cyclic Process for Producing Metallic Iron FIOZII'II'OILOXidQ Containing Material, hydrogen available in a gaseous mixture at a temperature substantially above the desired temperature. This application discloses an overall cycle in which reduction of ferrous chloride vapor with hydrogen is but one phase. The other phases of this disclosure have no bearing upon the present application. However, wh n the reduction process is used as one phase of this overall cycle, or. some other similar cycle, then the hydrogen available is at a temperature substantially greater than that at which it is desired to be introduced into the reducing zone, according to the present invention. Under these circumstances, it is usually necessaryto cool the hydrogen by the use of any availab e cooling fluid. such as. cooling water. Usually such cooling water is, available at about room temperature. Any temperature to which the hydrogen may be cooled by the use of such cooling water and anv available cooling means such as conventional heat interchangers, may be used in this connection. It has been found, for example, that with water at a temperature of about 48 F., hydrogen supplied at room temperature may be prevented from heating up to a temperature over about160 F. The. operation, under these circumstances, is quite satisfactory.

While the process of the present invention may be carried out in a number of different types of apparatus, which in detail form no part of this invention, there is illustrated in the accompanying drawings, in. a diagrammatic manner, an apparatus in which the process may be. carried.out..

In the drawings:

Figure 1 is a view, principally in elevation, but i with parts broken away and in vertical section,

of an apparatus in which. the process of. the

presentinvention may be carried out; and

Fig. 2 is anenlarged detailed view of a portion of the construction shown in Fig. 1, the view being upper. portion of the zone i i and a relatively lower temperature in the lower portion thereof. This type of arrangement for a reducing zone for conducting the reaction in question is dis.-

.closed in. greater detail. in the Crowley et. al. application, Serial No. 214,632, aforesaid.

There isshown a-pipe or conduit-Illeading into the zone II for thezintroductionof ferrous chloride vapor. This vapor maybe generatedin any suitable equipment or produced in any desired manner and supplied in a predetermined directionas'indicated by the arrow [3. The particular means shown is intended to be purely diagrammatic rather than structural as it is immaterial from the point of view of the present application What structural means are used for the introduction of'the. ferrous chloridevapor into the reducing zone.

Means, hereshown as a duct or tube l4, may be 'used for supplying hydrogen or a hydrogencontaining gas to the reducing zone I I. In a preferred form of the invention, the hydrogen-containing gas is introduced in a a direction indicated by the arrow I5, so that itwill intersect the stream of ferrous chloride vapor at a pointl6 centrally of the reducing zone as'shown. In-a practical embodiment of the invention, the tube [4 may be of some good heat conducting material, such as copper, the tube extending as shown at l1 into the reducing zone I about 4 inch.

As above set forth,- means are provided for ascertaining and indicating and/or recording an index temperature, which will be characteristic of the temperature of the hydrogen-containing gas per se. For this purpose, a thermocouple l3 may be'used positioned inside of the pro ecting end portion I! of the tube l4-and about inch from the exitend of thistube- Wires Hand 20 leading to the thermocouple-junction l8 may be passed from the junction through the tube I4 and thence outside the apparatus in a suitable way to any appropriate'temperature sensing instrument (not shown) for. indicating and/or recording such temperatures, such as are conventionally used withthermocouples.

In. order that thehydrogen-containing gas being supplied tothereducingzone H be either positively'cooled or be prevented. from heating up to an undesired extent dueto the heat. picked up'by thetube Mfrom the Wall of the container Ill, or from materials within the reducing zone, a cooling means maybe provided: for the tube I 41 inrthe form ofa jacket 2! through which a cooling fluid may. be passed-between an inlet 22 and: an outlet 23;. The cooling fluid will thus prevent undesired heating of the tube Mand prevent the building up of. too high a temperature in1the-incoming hydrogen-containing gas passed therethrough; or, if a relatively hot gas issupplied to thetube: M, the temperature-controlling fluid passed through the jacket 2| may, in fact servepositively to reduce the temperature thereof.

The reducing zone i I may be-provided'with a suitable outlet'sduct- M for the.- products of the reactioninthereducingzone, which-may be conveyed'thereby'to any desired point at'which they may. besegregated and/or utilized.

Considering how the theories underlying the process of the present invention, it is' believed that the action, which occurscausing adherent deposits of some solid material to build up around thehydrogen-containing gas inlet, is a premature reaction between hydrogen and ferrous chloride, resulting in the production of iron powder immediately adjacent to the inlet. It is believed that this iron powder in its nascent state which. it. is initially produced. is very sticky and. will adhere; to. adj acent. relatively, hot. sunfaces. Thisgradual.buildirigbp oi iron...powder my I of an adherent character serves to build a ring and eventually a tube-like structure probably consisting principally of iron powder. There may be, however, some solid ferrous chloride admixed with or occluded in this body of iron in practice. As the building up of an annular body or tube of this material progresses, the remaining opening through which the hydrogen-containing gas passes is progresively constricted, until it is altogether stopped or plugged up.

When operating with relatively pure hydrogen introduced at substantially the same temperature as that inside the reducing zone, this complete plugging occurred in a very few minutes as set forth in an example hereinafter given. If, however, the hydrogen-containing gas be introduced at relatively lower temperature than that in the reducing zone, in accordance with the present invention, it is believed that this lower temperature serves sufficiently to delay the reaction between hydrogen and ferrous chloride, so that the reaction does not occur immediately adjacent to the hydrogen inlet opening and so that the iron powder produced will be liberated at a portion of the reducing zone spaced substantially away from this opening and from the walls of the reducing zone, and hence the iron will not adhere thereto as an adherent deposit as aforesaid. Also the relatively cool hydrogen flowing into the reaction chamber tends to keep the temperature of the hydrogen inlet passage relatively cool, and thus prevents the means forming this passage from providing heated surfaces to which iron powder formed in the chamber will easily adhere. It may further be that due to the production of the iron powder in suspension in the central portion, for example, of the reducing zone, that other iron particles tend to build up on the particles of iron initially produced, resulting in what is equivalent to crystal growth. These larger crystals, grown in this way, may then be relatively non-adherent in character. Due to their greater weight, these larger crystals may fall freely toward the bottom of the chamber or reducing zone and/or carried out with the exhaust gases passing therefrom.

While these theories have been set forth herein as the best theories presently known, it is pointed out that the present invention does not specifically rely upon the accuracy of any portion of the theories so expressed, but rather depends upon the performance of specific and definite method steps, which have been particularly taught herein, and which will produce the results desired in accordance with the present invention irrespective of the theories by which those results may be explained.

It hasalso been found in independent experiments for the reduction of solid ferrous chloride with'hydrogen, that this reaction will not occur to any substantial extent at temperatures of about 700 F. and below. For this reason, then. it is believed that if the index temperature determined as aforesaid and the hydrogen temperature per se be kept at about 700 F. or below, there will be little or no tendency for the reaction to occur immediately adjacent to the nozzle or inlet opening for the hydrogen-containing gas, even if ferrous chloride were present in solid form (as it would be at this temperature) at that point in the reaction zone. Under such circumstances, it is believed that adherent solid deposits could not reasonably form. For this reason, therefore, a particularly preferred temperature, or temperature range, is when the index temperature is not over 700 F. and the hydrogen temperature per se probably somewhat less.

On the other hand, it is normally preferred in the operation of the present process to operate with the index and hydrogen-containing gas temperatures as low as can reasonably be attained and maintained using relatively inexpensive methods for cooling or for preventing the undesired heating up of the hydrogen-containing gas. ihese methods in the ordinary practice of the process will involve the use of available water, such as tap water, for cooling the hydrogen-containing gas inlet passage, 1. e., for passing through the cooling jacket 2| shown in the drawings. As set forth in the examples hereinafter given, index temperatures as low as F. have been attained in the practice of the present process, and were found to be desirable in use.

The process or method of the present invention is further illustrated in several examples, which follow.

Example I This example illustrates the difiiculties that have been encountered in attempting to reduce FeClz vapor by means of hydrogen where no provisions are made for preventing the hydrogen from heating up to the temperatures maintained in the reduction chamber when it is introduced therein and/or wherein the hydrogen was introduced at too high a temperature.

In an attempt to reduce FeClz vapor by hydrogen, the FeCh vapor was supplied by flash vaporization, at the rate of 10 liters per minute, into a chamber to which hydrogen was separately introduced as aforesaid. No provision was made for insulating or cooling the pipe through which the hydrogen was introduced and, in fact, the hydrogen was preheated to about the same temperature that was maintained in the reducing zone (1830 F.). It was found after only two minutes of operation in this manner that the hydrogen inlet became completely plugged with a growth of what appeared to be a mixture of metallic iron containing some solid ferrous chloride. This growth completely blocked the hydrogen inlet and prevented any further introduction of hydrogen into the reduction zone, thus making it impossible to carry on the desired reaction in a continuous manner.

Example II This example illustrates the operation of the process when provisions are made for preventing the hydrogen initially supplied at room temperature from heating up to the temperature of the reducing zone before it is introduced thereto.

Using a device similar to that shown in the accompanying drawings, hydrogen initially at room temperature was introduced into the reducing zone H through the tube l4. Ferrous chloride vapor was supplied through the pipe I 2. The temperature of the reducing zone H was measured at 1920 F.; and the index temperature measured by the thermocouple l8 was 160 F. In this example, the tube 14 was made of copper having inch outside diameter and 1%; inch inside diameter. The hydrogen initially supplied at room temperature flowed through pipe [4 at a velocity of 30.8 feet per second. Cooling water at an initial temperature of 48 F. was passed into the inlet pipe 22 and through the cooling jacket 2| at the rate of 0.02 cubic feet per second, and passed out through the outlet 23 at a tem perature of about 67 F. This considerable rise in temperature proved that a considerable amount Example 'III This. example, which describes an experimental run made overa-period of about-seven hours, illustratesthe effect of varying hydrogen inlet temperatures, as indicated by the respective index temperatures, on the rate of formation of adherent material on and adjacent to the hydrogen inlet. As the index temperatures increase, the tendency for adherent material to form at the exit end of the hydrogen tube increases. A- though no sharp line of demarcation exists at temperatures above about 1000" R, such higher temperatures appear to be less favorable for continuous operation because of the greatly increased tendency for adherent deposits to form under such conditions.

In this test a ferrous chloride reduction apparatus having essentially the same construction as that shown in the drawings was operated by introducing ferrous chloride vapor through the pipe 2 at the rate of about 9.1 grams per minute. Hydrogen was introduced through the pipe [4 at the rate of about 1.4 liters per minute, measured at 70 F. and at atmospheric pressure. The hydrogen tube E4 was of copper and had an inside diameter of inch. The temperature in the reducing zone was maintained throughout the run at about 1900" F. to 2000 F. In order to vary the temperature at which the hydrogen entered the reducing zone H, the rate of cooling water through the jacket 2| was decreased gradually, so that the hydrogen temperature, as indicated by the index temperature, could be controlled and was raised in a step-wise manner.

The condition of the end portion ll of the hydrogen tube M was continuously observed through a sight glass.

For the first two hours of the run, the rate of cooling water was so regulated as to maintain the index temperature, as indicated by the thermocouple I8, between about 320 F. and 340 F. During this period, the reduction reaction proceeded as desired; and powdered iron was collected from the reaction products emerging from the reducing zone through the outlet duct 24.

During the next 40 minutes, the rate of introduction of cooling water was decreased, so that the index temperature rose to about 410 F. The exit end portion I! of the hydrogen tube still appeared to be clean and unobstructed.

During the next hour, the index temperature was gradually raised to about 760 F. and held there for about 5 minutes. At this point, a slight growth was observed to form at the exit end of the tube. This material appeared to be light in color and rather fern-like and feathery in consistency. It was not troublesome, in that it did not appear to block off hydrogen; and pieces of it fell or sloughed off from time to time.

The index temperature was then raised to 800 F. and maintained at that value for about onehalf hour. During this time the light, fern-like deposit continued to form on the inlet tube; but

n? was not adherent in nature and pieces of it fell or. sloughed off from timeto time.

'The index temperature was then raised to about 910 'F. and held there for about one-half hour. The fern lilre deposit aforesaid formed somewhat more rapidly under theseconditions, but still did not appear to block the fiow or" hydrogen.

The index temperatur was then raised, by

adjusting the rate of flow of cooling water, until it was about 970 F. It was held at this temperature for about ten minutes, during which tlllISthE growth'increased to a length of about twoinehesand width of jinch. Still the hy-v drogen flowdid nota'ppearlto be restricted and after aboutten minutes, apiece of the growth about 4 inch long fell off. I

The index temperature was "then gradually raised .during the course of about an hour and twenty minutes to about 1100 F. During this time the growth increased by about and appeared to be somewhat adherent in character; although it still did not completely block ofi the flow of hydrogen. The index temperature was maintained at about 1100 F. for an additional 15 minutes, but during this time other operational difiiculties became so great that the run was discontinued.

From these observations, it is concluded that at index temperatures (determined as aforesaid) above about 1000 F., formation of adherent deposits at the exit end of the hydrogen tube are formed so rapidly that it is believed desirable for the purposes of the present invention, to keep the index temperature from exceeding about this value for the index temperature. Although it might be possible to operate for a time with index temperatures above 1000 F., such high temperatures are deemed to be undesirable for long continuous operations of the type to which the present process is well adapted.

While there has been explained herein the principles of the present invention and the limits thereof as far as they are known, and while certain equivalents have been set forth herein, other equivalents will be apparent from the foregoing description to those skilled in the art. We do not wish to be limited, therefore, except by the scope of the appended claims, which are to be construed validly as broadly as the state of the prior art permits.

What is claimed is:

1. In the reduction of ferrous chloride with hydrogen in a reducing zone at a relatively high temperature to produce iron and gaseous hydrogen chloride, wherein gaseous ferrous chloride and a gas containing hydrogen are separately introduced into a reducing zone, the method of preventing the clogging of the inlet into said zone for the hydrogemcontaining gas by adherent solid deposits, which comprises the steps of introducing said hydrogen-containing gas into said zone at a temperature such that the index temperature (said index temperature being that which is sensed by a thermocouple located at a point inside of and about inch from the end of a tube of good heat conducting material, with said tube extending about A; inch into said reducing zone) is not over about 1000 F., and maintaining the average temperature of the materials in said reducing zone at least about 1250 F.

2. The method according to claim 1, wherein said index temperature is about 300 F. to about 400 F.

3. The method according to claim 1, wherein said index temperature is not over about 700 F.

4. The method according to claim 1, wherein the average temperature in the portion of said zone into which the ferrous chloride vapor and the hydrogen-containing gas are introduced is about 1800 F. to about 2000 F.

5. In the reduction of ferrous chloride with hydrogen in a reducing zone at a relatively high temperature to produce iron and gaseous hydrogen chloride, wherein gaseous ferrous chloride and a gas containing hydrogen are separately introduced into a reducing zone, the method of preventing the clogging of the inlet into said zone for the hydrogen-containing gas by adherent solid deposits, which comprises the steps of introducing said hydrogen-containing gas into said zone at a temperature such that the index temperature (said index temperature being that which is sensed by a thermocouple located at a point inside of and about inch from the end of a tube of good heat conducting material with said tube extending about inch into said reducing zone) is about 300 F. to about 400 F. and maintaining the average temperature in the portion of said zone into which the ferrous chloride vapor and the hydrogen-containing gas are introduced from about 1800 F. to about 2000 F.

IRVING P. WHITEHOUSE. EDWARD A. BEIDLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,418,148 Williams et a1 Apr. 1, 1947 2,596,072 Graham et a1. May 6, 1952

Claims (1)

1. THE REDUCTION OF FERROUS CHLORIDE WITH HYDROGEN IN A REDUCING ZONE AT A RELATIVELY HIGH TEMPERATURE TO PRODUCE IRON AND GASEOUS HYDROGEN CHLORIDE, WHEREIN GASEOUS FERROUS CHLORIDE AND A GAS CONTAINING HYDROGEN ARE SEPARATELY INTRODUCED INTO A REDUCING ZONE, THE METHOD OF PREVENTING THE CLOGGING OF THE INLET INTO SAID ZONE FOR THE HYDROGEN-CONTAINING GAS BY ADHERENT SOLID DEPOSTIS, WHICH COMPRISES THE STEPS OF INTRODUCING SAID HYDROGEN-CONTAINING GAS INTO SAID ZONE AT A TEMPERATURE SUCH THAT THE INDEX TEMPERATURE (SAID INDEX TEMPERATURE BEING THAT WHICH IS SENSED BY A THERMOCOUPLE LOCATED AT A POINT INSIDE OF AND ABOUT 1/8 INCH FROM THE END OF A TUBE OF GOOD HEAT CONDUCTING MATERIAL, WITH SAID TUBE EXTENDING ABOUT 1/4 INCH INTO SAID REDUCING ZONE) IS NOT OVER ABOUT 1000* F., AND MAINTAINING THE AVERAGE TEMPERATURE OF THE MATERIALS IN SAID REDUCING ZONE AT LEAST ABOUT 1250* F.

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