US1912974A - Distillation of lignite - Google Patents

Description

June 6, 1933. H. DEBAUCHE 1,912,974

DISTILLATION OF LIGNITE Filed March 31, 1950 baadm Patented June 6,1933

PATENT OFFICE HUBERT DEBAUCH'E, OF GOUILLET, BELIIGIUM DISTILLATION' or momma Application filed March 31, 1930, Serial no. 440,467, and in Great Britain December 17, 1929.

This invention relates to the treatment of lignite for the purpose of transforming it into a coke which is suitable for the manufacture of briquettes, ovoids and the like.

The invention contemplates subjecting the said li nite to low temperature distillation and subsequently to a high temperature distillation in order to produce a coke which will be of the character desired, and involves the use of a furnace or oven for this purpose, of a kind known as the Rolle furnace which may be constructed as described and shown in my prior Patent No. 1,713,032. This patent specification describes an improved form of Rolle furnace, but to carry the invention into effect it is not essential that such improved form of furnace should be used, although it is preferable to do so.

It is well known that good coal briquettes or ovoids made in closed moulds with a coal composed of fragments of a size from O m. m. to 1 m. m., having a proportion of 7 70 of pitch and a pressure of 225 kilos per square centimeter possess the following qualities:

1. They present great cohesion.

2. Water exercises no action on these briquettes or ovoids. Consequently if they are immersed for a long time in water, for example for 300 to 400 consecutive hours, they absorb very little water (about 10% of their weight) and not only do they not disintegrate under the action ofthe water, but their cohesion does not decrease.

If these briquettes are taken from the water, they return to their original weight by the evaporation of the water absorbed.

These briquettes can resist indefinitely and without any alteration all atmospheric influences. i

3. In a locomotive fire box or other furnace, these briquettes burn without disintegrating. e These briquettes and ovoids which are satisfactory for commercial requirements, will 15 be referred to hereinafter as good coal briquettes.

On the contrary, when lignite semi-coke is taken as produced by various existing distilling furnaces and ground to the dimensions of a size from 0 m. m. to 1 m. m. and

:converted into briquettes in closed moulds,

with 7 76 of pitch and a pressure of 225 kllOS per square centimeter or it may be ovoids, the following is observed: 1 1. The cohesion of these briquettes is very 2. The Water exercises a powerful chemical action on these briquettes- Immersed in the water during only 150 to 200 hours, these briquettes absorb as much 0 as 25% of water and completely disinte- If these briquettes are withdrawn from the water, they do not return to their original weight owing to the chemical action of the o5 absorbed Water. Consequently, these briquettes cannot resist atmospheric influences indefinitely without alteration.

3. In a locomotive fire box or other type of furnace these briquettes disintegrate under the action of fire.

Such briquettes and ovoids which do not satisfy-commercial requirements, will be referred to in the present specification as: inferior briquettes.

It is reasonable to conclude from the preceding that these inferior lignite semicoke briquettes are incapable of use in almost any case. 7

By very prolonged researches and experiments, the inventor has discovered:

- 1. That the three defects which are indicated above and which are always present in r the inferior briquettes of lignite semi-coke are due to the fact that the semi-coke used made in closed moulds with 7 of pitch and a pressure of 225 kilos per square centimeter and they will possess the three ualities of good coal briquettes mentioned a ove, that is to say that:

1. The briquettes made with such lignite semi-coke will possess great cohesion.

2. Water will exercise no action on these briquettes. Consequently if one immerses them in the water for a long-time, for example during 300 or 400 consecutive hours, they absorb very little water (about 10% of their weight) and not only will they not disintegrate in the water but their cohesion will not be decreased. When these briquettes are withdrawn from the water, they will return promptly to their original weight by the evaporation of the water absorbed. These briquettes will resist atmospheric influences indefinitely without any alteration.

3. In a locomotive fire-box or other furnace, these briquettes will burn without disintegration and even without cracking.

These briquettes and ovoids of lignite semicoke which satisfy the commercial requirements hereinafter will be referred to as: good lignite semi-coke briquettes.

The good lignite semi-coke with which these good briquettes and ovoids may be made will be referred to in the present specification as: special lignite semi-coke.

This special lignite semi-coke presents characteristics which are peculiar to it and which are found only in the lignite semi-coke which is produced under certain well determined conditions, but which are not met with in other lignite semi-cokes.

The researches and experiments made by the inventor have enabled him to discover that, in order to obtain good briquettes of lignite semi-coke of which the three chief qualities have been herewith enumerated, it is essential that the lignite semi-coke used for their manufacture, should possess the two characteristic properties as follows:

A. The fragments of semi-coke must be clean and brilliant, that is to say, they must not" become coated during the distillation with a thin coat of graphitic amorphous carbon, because this coating results in neutralizing to a very serious extent the binding action of the pitch and consequently renders the cohesion of the briquettes very unsatisfactory.

B. Each fragment of semi-coke must be completely deprived of all the heavy hydro carbons contained therein.

Indeed, the presence of heavy hydrocarbons in a lignite semi-coke denotes that the semi-coke contains particles of lignite of which the chemical transformation which takes place by the distillation is incomplete and if briquettes are made with such semicoke, the following is observed:

1. Immersed in the water, the briquettes absorb water up to about 25% of their weight and sometimesmore.

2. The water absorbed'by these briquettes exercises a chemical action which disintegrates them completely.

3. In a locomotive fire-box or other furnaces these briquettes will disintegrate under the fire action.

The reason that a lignite semi-coke, although containing only a small amount of heavy hydrocarbons gave after agglomeration only a bad briquette, was hitherto unknown, and the discovery that this was due to the presence of heavy hydrocarbons is the result of numerous researches and experiments made by the inventor.

These two characteristic properties A and B do not exist in the lignite semi-coke which was hitherto made and which is produced by the' various distilling furnaces; this is the reason Why this lignite semi-coke cannot give and does not give after agglomeration good briquettes but only bad briquettes.

On the contrary the special lignite semicoke made in accordance with the invention possesses in thehighest degree the two characteristic properties A and B and consequently it gives good briquettes which possess the three chief qualities mentioned above.

The process by which this special lignite semi-coke is produced and which is an object of the present invention, must employ both low temperature distillation and a high temperature distillation. The lignite to be distilled must be gradually heated in such a way as to extract the utmost quantity of oil at the lowest temperature possible. Then the temperature of distillation must be progressive 1y increased so as to reach the high temperature, owing to the difficulties which are en countered in the elimination of the last particles of oil.

With the lignite which was employed in the experiments carried out by the inventor, the low temperature distillation commenced at 300 C. and was almost entirely completed at about 450 C.500 0., but for the removal of the last traces of heavy hydrocarbons it was necessary to raise the temperature to about 800 C., for the semi-coke inside the retort, and which would correspond to a temperature of 1000 C. to 1100 C. for the hot gases in the flues at the lowest portion of the furnace.

It will be understood that the temperatures employed will vary according to the lignite treated, and that the above temperatures are sible with the gas and vapours produced by the distillation itself so as to prevent the semicoke fragments being covered by a thin coating of graphitic amorphous carbon.

Further, the researches and experiments made by the inventor, have resulted in the discovery that good briquettes of lignite semi-coke, that is to say briquettes manufactured with lignite semi-coke possessing the two characteristic properties A and B mentioned above, possess a supplementary quality which exists only in a very much less degree in the coal or good briquettes of coal. This supplementary quality, is the ready combustibility which is far greater for good briquettes of lignite semi-coke, than for the coal or the good briquettes of coal.

In the course of the researches and experiments made on an industrial s -ale by the inventor in Belgium and in New Zealand on locomotives while drawing normal trains or on steam boilers, it was undeniably verified that in the same locomotive lire box or other furnace, a very much higher weight of good briquettes of lignite semi-coke could be burned than is the case with coal or good briquettes of coal. This difference amounted to from to This higher combustion of good briquettes of lignite seI11i-cokc-, naturally means a greater production of steam for the same boiler and it can be concluded therefore, that the use of good briquettes of lignite semi-coke in steam locomotives or in marine boilers constitutes a considerable reserve of power which is a consideration when it is a question of hauling a train on a prolonged incline or accelerating the speed of a train or steamer.

There is no doubt that this remarkable property of good briquettes of lignite scmicoke constitutes a strong argument in favour of their employment.

The enormous combustibility of good briquettes of lignite semi-coke was not hitherto known and this discovery is the result of the numerous researches and experiments on a large scale made by the inventor on good briquettes of lignite semi-coke, that is to say, on the briquettes manufactured with lignite semi-coke possessing the characteristic prop erties A and B mentioned above.

The applicant has also discovered that a Rolle furnace is particularly suitable for this treatment of lignite in as much as it produces just the conditions necessary to ob tain the special lignite semi-coke with the characteristic properties mentioned.

The Rolle furnace, the use of which is known for low temperature distillation, has been invented for' the distillation of the lignites in Saxony which contain much oil and more than 50% of water. Such a furnace has hitherto been employed exclusively for distilling oil and benzol from carbonaceous material and the coke hitherto produced was regarded at the best as a more or less unimportant by-product.

The inventor, however, discovered that the Rolle furnace offers great advantages for the treatment of lignite so as to obtain as its main product the coke desired and the oil or benzol obtained by distillation becomes therefore a by-product.

It thus follows that an object of the present invention is to utilize a Rollo furnace for the distillation of lignito to produce the particular kind of coke necessary for being subscquently briquetted. v

'In carrying the invention into effect, the accompanying drawing illustrates a vertical section of a Rollo furnace suitable to the purpose of the present invention.

According to the drawing the furnace comprises a central vertical cylindrical retort a into which the fuel is fed at its upper end Z) and from the lower end 0 of which the coke is periodically withdrawn. The retort chamher is formed by a centre tubular chamber formed by a series of superimposed rings d of conical form and spaced apart a suitable distance so as to permit the distillate escaping into the centre space and being led away by the usual outlet pipes 6.

Such a form of furnace is preferably modified by regulating the thickness of the annu lar layer f of fuel whereby as the lignite sinks progressively downwards, the thickness of such annular layer becomes thinner as at 9 towards its lower end, Owing to the heat treatment which is thus applied to the lignite, the latter is never in contact, during the distilling operation, with the hot gases which cause distillation and thus the fragments of semi-coke obtained are not covered by a coat of graphitic amorphous carbon, and nearly all the quantity of oil contained in the lignite is extracted at low temperature. After this oil has been removed, there remains in the semi-coke only a small quantity of heavy hydrocarbons and it is essential that these must be extracted, as has been mentioned above, in the form of oil in bringing the distillation to a higher temperature which is a high temperature distillation so that no heavy hydrocarbons are retained and consequently no particles of insufficiently distilled lignite are left in the coke which will assist or tend to cause disintegration of the briquette formed from the coke when exposed to moisture or to fire.

The coke produced in such a furnace is found to be clean in character and shows a brilliant appearance and will be easily agglomerated after crushing with the normal proportion of pitch or other binder with the result that very great cohesion of the briquettes is obtained and a suitable proportion of pitch would be 7.5% of'the mass. Further, the briquette will not crack when ex posed to heat, it will possess very high calorific value and itwill not disintegrate in the presence of moisture or fire.

From the foregoing it will be understood that by the use of the described form of furnace or oven and the temperature treatment indicated lignite is treated in such a way that a coke or semi-coke is produced which is very suitable for the use of briquettes or ovoids and on test these have been shown to possess just those characteristics which are necessary to ensure economic commercial manufacture and use.

As tested for driving locomotives, the briquettes have been found to be economical as being able to drive or haul a load with a greater speed than could be done by means of ordinary coal or briquettes as prepared in other ways.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is The process of producing a semi-coke for the manufacture of briquettes by continuously feeding downwardly through a heating zone of two different temperature ranges, a confined thin annular column of lignite, subjecting this annular column of lignite first to a temperature of 300 C. to 500 C., the heating being applied indirectly and to the outer periphery of the column of lignite, and then subjecting this heat treated column of lignite as it is fed further downwardly to a temperature of 800 (1., the heating being applied indirectly and to the outer periphery of the column to convert the lignite to a semicoke, withdrawing the distillation vapors and gases evolved from the lignite in its passage through the heating zones inwardly to a central zone at numerous points throughout the height of the column of lignite and selectively conducting off these evolved vapors at different levels from this central zone.

In testimony whereof I have signed my name to this specification.

HUBERT DEBAUCHE.

Images