US2167099A - Apparatus for producing a smokeless solid fuel - Google Patents

Description

July 25, 1939. P. J. M. BENEZECH, ,1

APPARATUS FOR PRODUCING A SMOKELESS SOLID FUEL Filed Ocfc. 29, 1935 2 Sheets-Sheet 1 July 25, 1939. L. P. J. M. BENEZECH 2,167,099

APPARATUS FOR PRODUCING A SMOKELESS SOLID FUEL Filed Oct. 29 1955 2 Sheets-Sheet 2 I v l I I 1 1 ks/ Patented July 25, 1939 PATENT OFFICE APPARATUS FOR PRODUCING A SMOKELESS SOLID FUEL Louis Philippe Joseph Marius Bnzech, Carmaux, France, assignor, by mesne assignments, to Koppers Company, Pittsburgh, Pa., a corporation of Delaware Application October 29, 1935, Serial No. 47,215 In France October 29, 1934 1 Claim.

The invention relates to the production of a smokeless, large-piece fuel from caking coal and more particular to the manufacture of smokeless briquettes out of such coals. i

It is already known to heat (carbonise) th coal briquettes in the absence of air, in order to produce a smokeless fuel, the shape of which corresponds to that of the raw briquettes, and which does not crumble when burned. Briquettes thus no treated are often called coke briquettes. Easy combustibility, high strength, cleanness and high reactivity are the distinct features of the coke briquettes which give, therefore, an excellent domestic fuel.

Hitherto, it was only possible to carbonise such coal briquettes consisting of non-caking coal, in particular anthracite. If caking coals are being used, the briquettes will lose their shape on being coked and they Will stick together. Consequent- 1y, no coke briquettes of a definite uniform shape are obtained, but lumps of an irregular shape, similar to the lumps obtained in the production of coke from caking coal.

The invention has, therefore, for its principal object a process of producing coke briquettes of any desired, but definite uniform shape and size from caking coal of any kind, even from coals being highly bituminous, such as gas coal and gas flame coal.

30 The process according to the invention mainly consists in subjecting the raw briquettes prior to the carbonisation, to an oxidising treatment, preferably by air at an increased temperature, which, however, must not be raised during the 35 oxidation to the point at which the coal 'perceptibly begins to fuse. According to the invention, this pretreatment of oxidation is carried into effect in such a Way that the coal in the individual briquettes partly or wholly loses its caking capacity, so that the coal in the briquette oxidised has lost the character of a caking coal.,

After the pretreatment of the raw briquettes they are subjected in a second stage of the process to a heat treatment at temperatures above the sof- 45 tening point of the coal, whereby the volatile matter is driven-off to the desired degree and a solid body of cokelike nature is obtained which does not soften in the fire.

The oxidation of the briquettes may be per- 50 formed according to the invention while they are at rest or in motion. In the subsequent coking of the oxidised briquettes, which operation preferably follows immediately the oxidation, the

briquettes may be kept at rest or be slightly moved similar to the movement of the charge in a continuously operated vertical chamber oven for the production of gas and coke.

Furthermore, the process according to the invention, may be used to produce a smokeless fuel having the shape of raw coal lumps from pieces of caking coal not being previously briquetted. In this case, the lump coal is treated in the manner as described for briquettes.

The principal feature of the equipment consists in that the carbonisation of the oxidised briquettes is carried out in an indirectly heated retort or the like, similar to the vertical chamber oven, and the hot waste gases drawn-off from the heating system of said carbonising retort are brought into contact with the raw briquettes preferably after the addition of air or another suitable oxidising medium in a second retort or container placed above the carbonizing retort so that the oxidised briquettes pass downwards immediately into the carbonising retort.

In order that the invention may be clearly understood and easily carried into effect, an embodiment of the apparatus adapted for carrying through the present process is represented by way of example in the accompanying drawings in which Figure 1 is a vertical section of the apparatus,

Figure 2 is a vertical section of the apparatus on line II--II of Figure 1, and

Figure 3 is a horizontal section on line III-III of Figure 2.

In these drawings, I is a hopper to which the raw briquettes coming from the press are fed and which has a closeable lower outlet 2.

Below the hopper is arranged an apparatus 3 having the shape of a shaft furnace and a closeable filling branch 4. The bottom of the furnace 5 is inclined and has a closeable outlet 6. In

line with the axis of the outlet 6 is arranged the l charging opening 7 of-the coking chamber 8 of the briquette coking oven.

In the embodiment illustrated, the coking chambers 8 are each formed by a hollow sheet metal cylinder of comparatively great wall thickness and are surrounded by refractory brickwork 9. The chambers 8 may also be constructed of refractory material, similar to the chamber walls of the well-known coke ovens. Whether the retorts be constructed of metal or of refractory material depends on the temperature at which the briquettes are to be carbonized.

As may be seen from Figures 2 and 3,- flues I0 are arranged on both sides of the chambers 8,

the waste gas is mixed with the heating media.

In this way the combustion is retarded in the flues I so that a uniform heating of the whole area of the chamber wall is obtained. The flues I3 lead toawaste-gas main flue Ila, with which,

preferably at the side of every coking chamber, a

vertical channel I5 and a horizontal channel I6 arranged at the longitudinal side of the oven, are connected.

A pipe I! governed by a damper IIa and communicating with the lower portion of the oxidising shaft furnace 3, is fixed to the vertical channel I5; The mouth of pipe I! ports into the shaft furnace 3 and is partly covered by a partition I8, being preferably perforated, whereby choking of the pipe I 1 by briquettes charged into the shaft 3, is prevented. An injector-like pipe I9 also reaches into the pipe II. It comes from a blower 20, so that air can be blown into the pipe I9 and thus into the pipe 11.

The channel I3 communicating with the waste gas collecting channel Ila, is connected with a pipe 2I governed by a damper 2Ia and leading to a heat exchanger 22. The waste gas outlet of the latter is communicated with the pipe I'I through a pipe 23.

Steam is generated in the heat exchanger22 or steam is superheated therein. The steam is supplied from the heat exchanger 22 through a pipe 24 governed-by a. valve 24a to many steamnozzles arranged in the lower portionof the coking chambers 8. Any suitable regulating means may be provided in order to distribute the steam into the individual nozzles in the required manner.

By the combination of the heating system for the chambers 8 with the oxidiser 3, it is rendered possible to feed the hot waste heating gases from the chambers 8 at a definite regulatable temperature and with a fixed content of oxidising gases to the oxidising shaft 3. The temperature of the gases is regulated by a corresponding adjustment of the dampers I'Ia and 2Ia and by varying the air supplied through the pipe I9, which air may be preheated, if required.

When the oxid ser 3 is out of operation and during charging and discharging, it is possible to draw off the hotcombustion gases temporarily through a safety valve 26. When the oxidiser 3 is permanently out of operation, the waste gas channel I 4 is connected to a chimney (not shown).

The gases entering the oxidiser 3 flow through the charge of raw briquettes therein and escape through a pipe 21 connected to a fan 28 which produces the suction required for moving the gases through the heating and oxidising system.

The distillation gases evolved in the coking chamber 8 pass through an ascension pipe 29 into the gas main 30 and from these into the distillation ga pipe 3I. The composition of these gases is similiar to that of the usual coal distillation gases. able manner and then used.

The briquettes coked in the chambers 8 are removed through the dischargers 32 arranged below the chambers 8.

Under certain circumstances, it will be suit- The gases may be treated in a suit- I able to maintain the top portion of the chambes 8 at a temperature differing from that of the medium-area of the chamber walls. For this purpose, additional heating flues are provided in the upper area of the heating walls, said heating flues being connected through apertures 35, governed by dampers 34 with the main heating flues -III in such a way that the hot gases for the main flues I0 may circulate through the additional heating flues 33. By suitably adjusting the dampers 34, the quantity of the hot'gases circulating in the additional flues 33, may be regulated and thus the temperature in the upper area of the coking chamber can be kept at the desired height. The flues 33 may also have any other suitable shape, in order to bring about the most effective circulation of the hot gases.

The apparatus as described and illustrated may be operated advantageously in the following manner:

In the customary way the ovoid-shaped briquettes are made from a coal of 0-6 millimeters grading and containing ash and volatile matter from a mixture of coal and 6% pitch as binder. The raw ovoid-shaped briquettes stored in hopper I) are charged into the oxidiser 3, which is then closed. The ovoid-shaped briquettes are now brought into contact with a mixture of hot waste gases and fresh air in the proportion of about two to three,- the temperature of the gas mixture being about 200 centigrade. The ovoids may be treated with the oxidising gases for four hours. Both temperature and time of oxidation and the proportion of air to waste gases in the oxidising gases may vary according to the nature of the coal and size and shape of the ovoid-shaped briquettes to be oxidised. In any case, the oxidation is carried on so long until the caking property in the skin of the ovoidshaped briquettes is reduced so that the ovoidshaped briquettes in the following carbonisin'g stage do not stick together.

After the oxidation is completed, the safety valve 26 is opened for a short time and thereupon the whole charge of oxidised briquettes is drawn from the oxidiser 3 into the coking chamber 8. The charge in the chamber 8 is lowered previously, by actuating the discharger 32 to such an extent that the chamber 8 can receive a further charge from the oxidiser 3, Preferably, the useful volume of the chamber 8 is made three times as large as that of the oxidiser 3 and the chamber 8 is intermittently operated, so that the oxidation will last about three times as long as the carbonization in the second stage of the process.

The coking of the briquettes takes place at temperatures of about 650 centigrade, but other temperatures may be taken,'for instance 550 and 750 centigrade, corresponding to the desired properties of the fuel to be produced. During carbonization steam is supplied'from below into the chamber 8, so that the lower portion of the charge is cooled. It may be noted, that the treatment of the briquettes shows three different actions. In the upper portion, the individual briquettes are coked, in the middle portion the distillation is completed and in the lower portion of the chamber the charge s cooled down. It is, however, possible, to operate the chamber in such a manner, so that at any time two charges only are present therein.

The temperature of the briquettes in the oxidiser 3 must not be above the distillation and ignition point of the coal briquetted, but it has to be as high as possible, in order to obtain a sufficient oxidation within the shortest possible time.

The briquettes being oxidised have practically the same weight, since the loss of weight is normally less than 0.2%. Also the percentageof volatile matter has scarcely become smaller. In most cases the decrease is not more than 1%. The surface of the briquettes has become dull black. The skin of the oxidised briquettes is stronger than that of the raw briquettes.

When oxidised, the briquettes can be coked practically in any oven, but preferably in an intermittently operated oven. The ovens to be used may be vertical, inclined or horizontal chamber or retort ovens.

According to the invention, the process can be used for the manufacture of briquettes of any desired shape. Also any binder may be used, such as tar-pitch,oil-pitch, tar, waste liquor of the cellulose production,. potassium, silicate or other ceramic binders and the like. Finally, it is also possible to coke, according to the invention,

briquettes made without any binder, such as briquettes made from slack by means of high pressure, with or without preheating the coal. The effect of the process, the hardness, strength of the briquette bodies and toughness of the final product depend more on the nature of the coal treated than on the binder used.

The oxidation of the raw briquettes herein before described is further of advantage, if briquettes of coal which. in itselfis non-caking, is to be worked with a pit-coal tar binder. In such a case, the oxidation is performed preferably at a temperature of about 60 centigrade, in

piece coal, the coal is subjected first to an oxida-- tion at a temperature below the softening and ignitioh point of the coal and then heated in' an air-tight container to temperatures above the softening point, the pre-oxidation of the coal be ing advanced, so far that in the subsequent distillation the individual coal pieces do not stick together.

For example, a coal of a grain size of 22-45 mm. with 9% ash and 25% volatiles may be treated. This coal is oxidised by a mixture of hot waste gases and air. The quantity of air of the mixture may be 50%, the temperature of the gases about 200 centigrade and the time of the oxidising treatment 8 hours. These conditions may be varied according to the natur of the coal to be treated.

After the caking capacity of the coal has been sufficiently reduced by the oxidising treatment, the large-piece coal is subjected to dry distillation in an air-tight container at temperatures above the softening point, for example, at about 700 centigrade. Contrary to the usual distillation, the oxidised coal pieces do not alter their original shape and do not cake together. A

fuel is obtained, having a bluish-gray colour and a high strength andhardness, which is of easy combustibility. Owing to its low'manufacturing temperature, this fuel represents an excellent domestic fuel.

I claim:

Apparatus for coking briquettes comprising: a series of alternate vertically discharging distillation chambers and vertical heating flues therefor arranged side-by-side in a row, the heating flues comprising, up-fiow and down-flow limbs spaced parallel to each other longitudinally of the row; a separate oxidation chamber for each of the distillation chambers, adapted for oxidation of preformed briquettes, each individual oxidation chamber being disposed directly over its distillation chamber and having closeable inlet and outlet means for gravity feeding of briquettes to its distillation chamber, and each individual oxidation chamber having gas conveyance means for circulation of oxidizing gas in through the briquette outlet into the oxidation chamber in direct contact with briquettes therein and having regulable means for feeding oxidation air into the gas conveyance means; a separate ofitake means, including a vertical flue disposed vertically at one end of each distillation chamber, individual to each of the distillation chambers and to the heating flues therefor and the individual oxidatillation chamber therefor; and separately regulable means including a gas temperature regulator for separately conducting hot gas from the respective oiftake means to the gas conveyance means individual thereto, so as to by-pass the vertical flue of the ofltake means.

[LOUIS PHILIPPE JOSEPH mmms BfiN'EZECH.

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