US2256017A - Coal treatment - Google Patents

Description

p M. D. CURRAN 2,256,017

COAL TREATMENT Filed April 28, 1937 3 Sheets-Sheet l wvewib'n MAMP/CE 17. Comm M. D. cuRRAN COAL TREATMENT Sept. 16, 1941.

Filed April 28, 1937 3 Sheets-Sheet 2 INVENTOR.

MmP/a'f'fl Came/w A TTORN E Y M. D. CURRAN 2,256,017

COAL TREATMENT Filed April 28, 1937 3 Sheets-Sheet 3 INVENTOR. NAMMEQ Caeen/v BY I ATTORNEY Sept. 16, 1941.

i2 m y m" c u l l illln Mg 7 A u I/ 9 WM u Mun- I 3 a 0 v 9 3 a a. 42 a, J F 7 5 UNITED STATES PATENT OFFICE COAL TREATMENT Maurice Donovan Curran, St. Louis County, Mo.

Application April 28, 1937, Serial No. 139,532

7 Claims.

This invention relates to the treatment and preparation of coal.

It is the object of this invention to provide a method and apparatus for treating coal which will render the coal more suitable both as a. fuel and for the manufacture of briquettes or other products.

When coal is treated according to the methods of this invention smoke producing volatile constituents of the coal are removed, so that when the coal is used in either domestic or industrial plants practically smoke free combustion is obtained. This factor is an increasingly important one especially in districts where soft or bituminous coal is used and objection is made to the smoke resulting from the burning of soft coal. After coal is treated according to this process, it may be used as is or it may be compressed into briquettes either with or without a binder at pressures below the pressure normally required.

Additional objects and advantages of the invention will appear from the following detailed description and from the drawings which show several embodiments of the invention.

Fig. 1 is a perspective view of one form of coal treating apparatus.

Fig. 2 is a longitudinal cross-sectional view taken along line 33 of Fig. 1.

Fig. 3 is a horizontal cross-sectional view taken along line 33 of Fig. 1.

Fig. 4 is a horizontal cross-sectional view of an optional form of a portion of the apparatus shown in Fig. 3.

For the purpose of illustrating my invention I will now describe a method and apparatus which may be used for treating coal, which is at present preferred by me since the described method has been found in practise to give satisfactory and reliable results, although it is to be understood that the various steps and apparatus used can be variously arranged and organized so that my invention is not limited to the precise arrangement and organization hereinafter set forth.

Referring now to the drawings, the numeral In indicates a gas chamber which may be supported in any suitable manner; I show it supported from a beam l2. The beam I! may be supported by a column I. A lower chamber is shown at 9 supported by the vertical supports II by suitable brackets I3 and beams l5. II shows a passage into the upper chamber which may be used for either the inflow or the outflow of gases, vapors or other fluids to or from the upper chamber. 19 shows a passage into the lower be of the form shown in Fig. 1 of the drawings.

2| is a rotating member adapted to move be-- tween the upper and lower chambers. This member may be formed with side plates 23 to which are attached sealing members 25 which may be formed as shown in the drawing. 21 shows portions of the upper and lower chambers adapted to engage these sealing members so that when they are filled with sealing material a seal is formed between plates 23 and the upper and lower chambers. The operating temperature of the apparatus is approximately from 575-935 degrees Fahrenheit and a suitable sealing means is diflicult to maintain. It has been found that if the sealing member is filled with some low In Fig. 4 an optional method of securing the sealing members to the plates of the rotating member is shown. In this method, the sealing member 25 is separated from the plates 23 by heat insulating material 29 which serves to re- 25 duce the temperature of the sealing member. In

a sealing member of the type shown in Fig. 4 it is possible to use a high boiling point pitch or liquid as a sealing means instead of a low melting point metal or solid material.

30 3| is a coal supporting means which may be a screen in the form of a wire mesh, perforated plate, spaced wire, or other means which will support coal and yet allow the passage of a fluid therethrough. The coal supporting means may 3 be supported from the plates 23 by a rod or axle 33. The plates 23 may be secured to beams which rotate about an axis 31. The rotating beams may be supported by a wheel 38 riding on a track 39. The upper chamber may be di- 40 vided into sections by baiiles 4| which may be suitably secured to the sides of the chamber as by angles 43. An asbestos flap may be secured to the bottom of these baflles and may be constructed so that when a layer of coal rests on 45 the coal supporting means, the flap will engage the surface of the coal to effect a seal between the adjoining compartments formed by the baffies.

41 is a chute which may be provided to introduce coal 49 onto the coal supporting means.

The chute is tilted in order that as the coal passes down through it, the larger pieces of coal will come to the surface and the finer pieces will flow along the bottom of the chute. If the dichamber. The upper and lower chambers may rection of rotation of the rotating member and screen is as indicated by the arrow in Fig. 2, and the chute positioned as there shown, the larger pieces of coal will flow onto the bottom of the screen and the flner particles of coal will then rest on top of the larger pieces and will-thus not fall through the screen.

Each coal screen may be provided with anarm 5| secured thereto which will tilt the screen and empty it of its contents when the arm strikes a trip member 53. after passing over the trip member, the trays resume their normal position.

A hopper 54 may be provided beneath the trip member allowing the\ coal which is emptied from the screens to fall into the hopper and be carried away by a worm 55.

The entire rotating assembly may be driven in any suitable mamier as by a cable 51 which may in turn be driven by a sheave 59 connected to a suitable source of power.

Removable plates 6i may be provided on the bottom of the lower chamber in order to allow access thereto. Ports 63 may be provided in the walls of the upper chamber to allow access to the baflle flaps 45 or in any other position where it is desired to obtain access to the inside of the chambers.

In'operation, coal is dumped in the chute 41 and runs down onto the coal supporting means 3|.

The various compartments which are formed by the bafiies may be used to carry out different operations on the coal. For instance, the first compartment indicated by the numeral 65 may be utilized to heat and drive off all the .moisture present in the coal. This may be done by introducing a hot gas through the passage I! into the upper chamber and allowing it to pass through the coal to be drawn off through the passage IS in the lower chamber. Steam may be used as the hot gas in the first compartment if so desired. The coal may then be allowed to pass under a baflie into a second compartment 61 where it may be treated by some fluid which will serve as a solvent for a portion of the volatiles in the coal. This fluid may be one of a number of suitable gases or mixtures. Ordinary coal tar or coke oven gas may be used as a carrier for any one of a number of solvents. It has been found that crude benzol with a boiling range of 175-265 degrees Fahrenheit, crude coal tar naphtha with a boiling range of 265-340 degrees Fahrenheit, crude pyridine (Barrett specification), tar distillate boiling off at temperatures below 420 degrees Fahrenheit, tar distillate boiling off below 590 degrees Fahrenheit and tar distillate boiling 011 between 420-670 degrees Fahrenheit may serve as solvents with varying degrees of success. The flrst three solvents named when volatilized and carried through the coal by a hot gas, produced acoai which could be made into satisfactory briquettes and which burned smokelessly. In general it has been found that the higher boiling point solvents have been the most effective under the conditions in which the work was carried out. I believe however, that the effectiveness of any of these solvents can be varied according to the conditions surrounding the work. Economic factors will largely govern the type of solvent used but generally speaking, the boiling point of: the solvent ought to be below the temperature prevailing in the process so that it stays in gaseous form while passing through the coal layer. The fluid may be introduced through one of the passages i'i into the upper chamber and drawn off through a passage I! in the lower chamber after passing through the coal.

The particular temperature at which the treatment is affected is important. For the proper treatment of the coal, I prefer that its temperature be raised to a point high enough to allow the hot gaseous solvent to remove smoke producing volatiles from the coal and yet not to such a temperature that the surface thereof will become tacky. Of course, in a material which varies in quality like coal it is possible to have a small portion of the coal showing a softened surface and some of the softened material may cling to the parts of the apparatus, but I use a temperature that is sufilciently low to avoid such a caking of the coal as would impair the working of the apparatus and entail the needless expenditure of heat.

It is obvious that the speed of passage of the coal through the apparatus as well as the temperature and velocity of the hot gas will affect the temperature of the coal in the apparatus. I prefer to keep the temperature of the coal just below the softening point which can readily be accomplished by varying the temperature of the incoming gases between 500 and 800 Fahrenheit to produce the desired result. At the softening point, the coal begins to swell and its surface becomes tacky or adhesive. Thus if the coal is heated to the softening point, it will stick to the apparatus and it will be necessary to clean the apparatus at frequent intervals. In addition to being an expensive procedure, the period taken for cleaning removes equipment and men from service for the time required. If the temperature of the coalis kept below this point, it will not stick to the apparatus and can be handled very easily. It can be used either as it comes'from the apparatus or pressed into briquettes. Other processes for making briquettes have either raised the temperature of the coal above the softening point in order to make it cohesive or have resorted to the use of binders which may cost as much as 75 cents per ton. Either method has proven unsatisfactory, one because of the difllculty in handling the sticky coal and the other because of its cost. With my method, I have found the solvent which I carry through the coal by means of a hot gas places the coal in such a condition with its temperature just below the softening point that the pressure of briquetting machinery will bring the coal to the softening point and will form good briquettes. The briquetting dies may be heated if desired. The solvent which is carried by the hot gas removes smoke-producing hydrocarbons or volatile matter and a smokeless fuel results.

'After treatment in the second compartment, the coal passes into the third compartment 69 where it is dumped into the hopper 54 and removed as by screw 55.

I If for any reason it is desired to add a binder tothe coal, the apparatus described in this invention can be advantageously used for such purpose. It would be possible to provide another compartment in which a binder could be sprayed on the coal or this might be done in the third compartment shown. The binder could be atomized in one of the chambers and a gas introduced to carry the binder in this finely divided state through the coal.

It is not, however, necessary to add a binder to the coal treated by this process, in order to form briquettes but where because of other factors it might be desirable such apparatus would prove advantageous.

In the method just described, the evaporation of the moisture in the coal and the dissolution of the volatiles is carried out in separate compartments. It is possible to simultaneously evaporate the moisture and dissolve and carry away the volatiles in one compartment and with only one gas if so desired. It is also possible to preheat the coal and drive off much of the moisture either while it is coming down the chute or before it enters the chute. The speed at which the rotary member revolves is dependent on the temperature of the entering gases, the particular solvent gas used and the type of coal being treated.

It might be desirable, in certain instances, to arrange the apparatus 50 that the gases could be introduced in the lower chamber and pass upward through the coal into the upper chamber to be carried off.

The coal as removed from the hopper is well prepared for manufacture into briquettes by placing it in moulds and subjecting it to suitable pressure.

The selling price of briquettes is determined by the price of coal and the cost of making satisfactory briquettes has been such that there has been a very small profit in general in this business. I effect one economy in that I make briquettes without the use of a binder. Another economy is that I hold the temperature below those heretofore used in treating the coal. This not alone effects a saving in that less heat is consumed in heating the coal, but it also avoids the caking of the material in the apparatus. This caking entails not merely the cost of cleaning out the apparatus but the cost of having the apparatus out of service.

It can thus be seen that the invention provides a practical expeditious method of removing the objectionable volatile matter from coal as well as for preparing the coal for use in the manufacture of briquettes or other products. The method of this invention lends itself to the continuous production system and makes it possible to utilize equipment of a size which can be manufactured economically.

While I have illustrated and described but one method of carrying out my invention, it is obvious that various modifications, substitutions, and additions may be made in the method and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. The hereinbefore described method of removing volatile smoke-producing material from coal which comprises passing a hot gas over coal which carries with it the vapor of a normally liquid aromatic substance that is effective to free the coal of its smoke-producing hydrocarbons while maintaining the coal at a temperature sufficient to maintain the normally liquid substance in a gaseous state and remove smoke-producing volatiles from the coal.

2. The hereinbefore described method of removing volatile smoke-producing material from coal which comprises passing a normally liquid hydrocarbon in gaseous state over the coal while maintaining the coal at a temperature suflicient to maintain the normally liquid hydrocarbon in a gaseous state and remove smoke-producing volatiles from the coal.

3. The hereinbefore described method of removing smoke-producing volatile hydrocarbons from coal which consists in passing a hot gas above 400 C. carrying crude benzol, with a boiling point of about 175-265 F., in a gaseous state over granular coal and thereby removing volatile smoke-producing material from the coal while maintaining the coal at a temperature below its softening point.

4. The hereinbefore described method of removing volatile smoke-producing material from coal which consists in passing a hot gas above 400 C. carrying crude coal tar naphtha, with a boiling range of about 245-355 F., in a gaseous state over granular coal and thereby removing volatile material from the coal while maintaining the coal at a temperature below its softening point.

5. The hereinbefore described method of removing smoke-producing volatile hydrocarbons from coal which consists in passing a vapor of an aromatic solvent of the hydrocarbons through the coal by means of a hot gas while maintaining the coal at a temperature just below its softening point.

6. The hereinbefore described method of removing volatile smoke-producing material from coal which consists in passing a hot gas above 500 C. carrying crude tar distillate, with a boiling point below 660 F., in a gaseous state over granular coal and thereby removing volatile material from the coal while maintaining the coal at a temperature below its softening point.

'7. The hereinbefore, described method of removing volatile smoke-producing material from coal which consists in passing a hot gas above 500 C. carrying crude pyridine, with a boiling point below 660 F., in a gaseous state over granular coal and thereby removing volatile material from the coal while maintaining the coal at a temperature below its softening point.

MAURICE DONOVAN CURRAN.

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