USRE20828E

USRE20828E - Process and furnace for making

Info

Publication number: USRE20828E
Authority: US
Priority date: 1928-07-27
Publication date: 1938-08-16
Also published as: US2057393A

Description

Aug. 16, 193.8. E. R.VPIOWELL 20,828

PROCESS AND FURNACE FOR MAKING MINERAL WOOL Original Filed July 27, 1928 Fla. 50

INVENTOR. fpmmo 7?. Pan/[1L UNITED. STATES PATENT OFFICE PROCESS AND FURNACE FOR MAKING MINERAL WOOL Edward 3. Powell, Cleveland Heights, Ohio, assignor, by mesne assignments, to Johns-Manville Corporation, New York, N. Y., a corporation of New York Original No. 2,057,393, dated October 13, 1936,

Serial No. 295,675, July 27, 1928.

January 31,

Renewed March 3, 1938, Serial No. 193,639

7 Claims.

This invention relates to a furnace for the economical production of mineral fibre, commonly called rock wool. The terms mineral and mineral woo are employed hereinafter in a consists of a blast including air, preferably heated, and powdered fuel in the form of powdered coal. 'Coal is supplied under pressure through pipe i9 and with some air. Air supplied through furnace, if the distance between the two be not generic sense as is customary in the art to denote pipe 20, is carried to the blower 2i through the 5 respectively rock, slag and other conventional pipe 22 connected at 23 to the chamber l2, which raw materials, and the fibres made therefrom. chamber has an open face at its opposite end so The chief object of this invention is to produce that air will be drawn through the chamber takeconomically, with a minimum of waste and at ing heat from the refractory wall. The air a relatively rapid rate, a molten stream of mineral passed through the blower to the discharge assists 1o material suitable for blasting into mineral wool. in the discharge of the powdered fuel, such as A feature of the invention consists in the uticoal. The hot air and the fuel burn completely lization of relatively powdered fuel whereby an and the flames and the gases pass forward intensification in action is obtained, and relathrough the combustion chamber and upwardly tively fine raw material falls in countercurrent through the stack 25 suitably insulated as at 26, 15 relation to the flame so that the raw material is and pass from said stack to the smoke pipe 21 surrounded on all sides by the flame. and thence to the chimney. To assist in the pro- Another feature of the invention is to provide duction of the steam employed in the blast II, a large bath or pool of melted material so the a water Jacket 28 is included in the stack convarious ingredients will have the opportunity of struction.' 20 mixing and reacting and from which two or more Positioned at the top of the stack is a. hopper streams of nearly equal size may be drawn. 30 having a control discharge in the form of :1

Another feature of the invention is that, by measuring device such as a measuring screw 3i varying the diilerent blast pressures and since at the outlet 32 therefrom. The material in the as there is a slight difference in viscosity between hopper 30 consists of the mineral to be melted, the several streams, the material or wool formed and, preferably, such mineral is in the form of from each combination can be regulated to either pieces of relatively small size, that is, it is crushed produce a substantially uniform material or as to about one-half inch or smaller. The crushed preferably desired, a material having coarse as, mineral is introduced into the combustion chamwell as fine fiber, and the two types of material her by a gas and material flow arrangement, such 30 when intermingled produce final material of good that it enters the combustion chamber at submechanical strength as well as good insulating stantially the melting point and in a melting value and to a degree not obtainable with a single condition. nozzle furnace. Means for securing this operation consists in 5 The full nature of the invention will be underalternate baiiles 33 arranged to cause the depart- 35 stood from the accompanying drawing and the ing gases to take a sinuous path and the entering following description and claims. material to take a similar coincidental but re- In the drawing Fig. 1 is a vertical section of verse path. The cold material is intimately conone embodiment of a furnace including the intacted by the colder portion of the gases, and, '40 vention. Fig. 2 is an end view of the spout or as the crushed mineral approaches the combus- 40 discharge end of the furnace. tion chamber, its temperature rises as also does In the drawing, l0 indicates a combustion the temperature of the stack, by reason of the chamber of refractory material such as carboincrease in temperature of the gases as the com- 7 I rundum or chromite block encased as at H formbustion chamber is approached.

ing an air passage l2 therebetween into which The stack-discharged, melting, crushed mate- 45 extends veins I! of the refractory wall for furrial passes through the flames or is heated therenace cooling. The combustion chamber includes by and is completely melted and collects at the a discharge outlet II for the gases which also bottom in the stream bed 35. In all probability serves as a charge-receiving intake. The comthere is also formed in said stream bed a cone bustion chamber has one or more spouts or tap 36 of unmelted rock. The molten bath at the 50 holes i5 from which discharge the molten streams stream bed is drawn oil through the tap holes I5. ll which are blasted by air or steam supplied as The present invention permits the utilization -at IT to form the mineral fiber or wool. of small pieces of mineral and thus the employ- The means for combustion are supplied ment of a conveyor system from the mine to the a through the opening I! and herein said supply excessive. But, more important than this is the change from coke to a powdered fuel, such as coal. This reduces the fuel cost approximately 80% or more. The use of relatively fine or crushed mineral does not require a long tempera.- ture contact period to melt the smaller particles. Also, the small size of the mineral particles permits each particle to be intimately contacted by the hot gases passing from the combustion chamber so that the raw material is preheated substantially to the melting point before it discharges into the combustion chamber and, by reason of. the small size of the said material, contact with the flamesin the combustion chamber lmmediately melts the mineral and the liquid is ready for discharge through the tap holes. Thus, a very high temperature is obtained at the melting point of the material thereby providing a better physical condition of the molten mineral which in turn permits the production of better fibre or a greater proportion of a commercially acceptable fibre.

Another economy in operation consists in utilizing the heat radiating from the combustion chamber for pre-heating the air supplied to the fuel. This, while apparently insignificant, is of considerable importance, since the temperature of the air does not have to be raised to the heat of the furnace at the melting point from that of the atmosphere. The temperature of the furnace in the interior at the contact point of the flame and the mineral material is between 3000 and 3500 degrees Fahrenheit or thereabout. The introduction of air under ordinary temperatures to the interior of a furnace with the before-mentioned temperature therein .would involve an unnecessary fuel loss and cooling of the furnace.

By reason of the intense heat and arrangement employed herein, it may be necessary, in order to prevent pre-melting, to add cold air to the as cending gases of combustion and herein the condition of this character is illustrated by the cold air discharge pipe I" connected to a header llll in turn connected by line I22 toa blower |2l controlled by a valve I20. This arrangement insures positive cooling to the adjusted degree. If

desired, the blower may be omitted and the header intake or intakes suitably controlled so that the draft in the stack will serve to direct into the stack a suitablyadjusted amount of cool air. The result is that pre-melting of the material, while passing through the stack, is prevented and clogging of the melted material in said stack is thus prevented.

As shown clearly in Fig. 2, the present type of furnace readily lends itself to multiple spout discharge. In this way a plurality of spouts Ii can discharge into a single blow chamber and the capacity of the unit be doubled by the addition of one or more additional spouts without requiring any appreciable additional equipment, thus materially reducing plant operation but securing,

increased production without any material in- Juries in attendance or maintaining charges or capital investment. The rate of flow of the material through the stack can be regulated to take care of the desired number of outlets or, spouts.

As shown in Fig. 1 each of the blasts I! may be controlled by a valve H1 so that the pressure may be regulated. Since the streams It discharge from different parts of the furnace,

- and since the temperature may vary slightly,

said streams are of slightly different viscosities. The several streams having a slightly diflerent viscosity and the several blasts or nozzles i'! having diflerent pressures can produce any final type of material and such a material will include a mixture oi materials made under different conditions, that is, one nozzle may blow a coarse strong fiber and another nozzle may blow nothing but fuzz. These two extreme types of materials when intermingled in the blow chamber 8 having the opening H9 produce a material of good mechanical strength as well as good insulating value and to a degree not obtainable with a single nozzle. v

The invention claimed is:

1. The method of manufacturing-molten material for rock and mineral wools which comprises maintaining a blast flame of pulverized fuel, maintaining a supply of raw material, withdrawing a continuous relatively thin stream of material from said supply, preheating said stream of raw material by passing it in countercurrent relationship to the products of combustion from said flame, controlling said preheating operation whereby said raw material, at the end thereof, is substantially at its melting temperature, projecting said, preheated material directly across said flame, whereby it is melted, connecting said melted material in a pool, and withdrawing said melted material from said pool at points of different temperature in a plurality of streams in the presence of a plurality of jets, whereby said molten material is formed into wool.

2. The method of manufacturing mineral wool which comprises maintaining a pool of. the molten rock, supplying sufllcient. heat to said pool to maintain its fluidity and withdrawing said material in a plurality of streams from different points of temperature of said pool and contacting a jet with each of said streams whereby said molten material is formed into wool.

3. In making mineral wool, the method which comprises melting a suitable material of the type described, discharging the molten product in a plurality of streams of differing viscosities, and shredding the material in the several streams into mineral wool.

4, In making mineral wool, the method which comprises melting a suitable raw material of the type described, discharging the molten product in a plurality of streams of differing viscosities, shredding the material in the several streams into mineral wool, and intermingling the wool produced from the several streams.

5. The method of manufacturing mineral wool insulating material comprising .the steps of reducing a mineral material to form a plurality of molten streams, shredding the streams by blasts to produce different types of textured fibre, and intermingling the types of fibres.

6. The method of manufacturing mineral wool insulating material comprising the steps of reducing a mineral material to form a plurality of molten streams, shredding the streams by independently controlled blasts to produce different types of textured fibre, and intermingling the types of fibres.

'1. The method of producing mineral wool fibres which comprises placing a suitable solid, raw mineral wool forming material into a furnace, melting the raw material to form a pool of molten material, discharging said molten material directiy from said pool in a plurality of discrete streams, and discharging a gaseous medium under pressure against said streams at such velocity as to disintegrate said streams to form mineral wool EDWARD R. POWELL.