DE1258386B - Process for the continuous degassing of coal in a shaft furnace - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

ClOb

German class: 10 a -24/01

Number: 1 258 386

File number: O 8484 VI b / 10 a

Filing date: January 17, 1962

Open date: January 11, 1968

The invention relates to a method for the continuous degassing of coal in a shaft furnace, according to which the coal is heated directly by flammable gases conducted in cocurrent and Coke and gas are withdrawn separately.

Coal is heated in the absence of oxygen to produce degassed products known as coke or grude depending on the type of coal treated as well as the temperature and treatment time of the degassing to manufacture. These products are used as fuels and as sources of carbon for metallurgical Suitable for reduction processes.

Virtually all of the coal degassing devices currently in use have a fact together. This fact is based on the fact that the heat required for the degassing process fed through a refractory or metal wall. This adds to the practical size of the device limited due to heat transfer considerations. A related one The exception is the beehive furnace, where heat is generated by convection and radiation from gases is fed, which burn in a chamber above the coal layer. Make further exceptions Coking devices in which hot inert gases are passed through layers of coal. By doing In the latter case, such processes require superheated steam or superheated combustion gases, which have been brought to the degassing temperature in a heat exchanger or furnace are.

In particular, it is a method for smoldering or charring shale coal, lignite or. Like. Became known, in which a moist column of goods as a result of downward traction of the smoldering agent from the smoldering zone from top to bottom and as long as the smoldering zone does not reach the has reached the lower end, is kept cool here and the distillation products are drawn off here, with It is essential in this procedure that the material column is supplied with combustible gas and air and advancing the charring zone by balancing the heating effect and the volume of the burning draft of the gases that pass through the carbonic acid in the direction of progress of that zone, against the cooling effect of the moisture in the Weitergangsriehtung is regulated.

In this process, the hot combustion gases are now cooled to a certain temperature of about 100 ° C, so that outside the zone heated by conduction is to be processed Product remains practically at normal temperature.

Process for the continuous degassing of
Coal in a shaft furnace

Applicant:

Marathon Oil Company, Findlay, Ohio (V. St. A.) Agents:

Dipl.-Ing. W. Meissner and Dipl.-Ing. H. Tischer, Patent Attorneys, 1000 Berlin 33, Herbertstr. 22nd

Named as inventor:
Victor Dean Allred, Littleton, Col. (V. St. A.)

Claimed priority:

V. St. v. America January 25, 1961 (84 809)

The invention is based on the object of a method for the continuous degassing of coal to create the specified type that the disadvantages associated with the previously known method overcomes and in particular makes it possible to achieve the greatest possible yield of coke and gas, so that practically no carbon for combustion occurring in the coke during the degassing comes and the volatile components of the coal are practically completely converted into usable gas will. In addition, the object on which the invention is based is the general Procedure to be designed much simpler than according to the prior art and thus to realize savings and simplifications also in terms of devices. One in this Objective pursued in context also in achieving a high throughput per unit of time and the method according to the invention to carry out using existing devices as far as possible, so that the new process only involves minor modifications in existing devices can be carried out.

The inventive method is now characterized in that the coal together with air fed in the unheated state to a combustion zone that the combustion zone as a result of the Oxygen consumption of the gas supplied with the coal only to a narrow expansion range

709 718/134

limited and that in the degassing zone following the combustion zone by the temperature of the now oxygen-free gases the complete degassing of the coal is achieved.

By means of the method according to the invention, the coal to be coked is thus in the cold state held until it approaches the combustion zone and then very quickly increases to the coking temperature brought and remains so long in the hot state that a further degassing, and although especially in the oxygen-free zone, is possible through which the fuel after leaving passes through the combustion zone. The invention is hereinafter referred to by way of example explained on the drawings.

FIG. 1 is a schematic flow diagram showing an arrangement employing a retort of the type shown in FIG Figure 2 shows the type shown with associated equipment for operation;

Figure 2 is an elevation view of a retort, partially broken away;

Fig. 3 is a vertical section through a modified retort shape;

Fig. 4 is an elevation of a further modified one Retort shape.

According to FIG. 1, the coals are first od on a vibrating chute. Like. For the purpose of removing Pieces larger than 15 cm sieved and then brought into storage container 12, which is the feed for which contain the distillation retort. A certain amount of coal is through an outlet 13 of the Feed device 15 is fed to a retort 14. A suitable allocation device 16, here a star wheel (Fig. 2), moves the coal from the feed exercise device 15 through the inlet 17 of the retort 14 and is arranged so that there is an appreciable pressure drop from inside the retort 14.

The retort 14 has an elongated vertical chamber, which preferably, as indicated at 14 a, is thermally insulated and dome-shaped at its upper end and extends in the direction of widened at the bottom. The bottom part of the retort is frustoconical and has a central one Outlet 18. From this outlet, the coke is discharged into a discharge device 19, which is also is shown in the form of a star wheel so that the retort pressure is maintained. Through the discharge device 19 the coke leaves the coking retort.

An oxygen-containing gas, usually compressed air, is supplied through an air inlet 22 which is extended into the interior of the retort 14 and which has a series of nozzles 22a through which the gas is distributed into the downstream coal stream across the width of the retort. This gas introduction is carried out in a suitable manner, e.g. B. controlled by means of a valve 1, with the assistance of a fan 23.

The degassing gases and combustion products are discharged through an outlet 24 in the bottom portion of the Retort 14 withdrawn and can be introduced into a separation unit 25, which is a cooler and gas-liquid separator and optionally also have a heat exchanger. The coal tar and the water resulting from this separation is stored in a tank 26 or another appropriate vessel inserted so that separation of the water from the coal tar is made possible. That The gas emitted by the unit 25 can be fed through a line 28 for further use, and part of it can also be returned to the retort through inlet 21. Optional a part of the gas exiting from the unit 25 can pass through a junction 27 of the through the Inlet 22 introduced air are admixed.

According to Fig. 2, a roll crusher 31 is provided in the lower retort part, which the agglomerated Crushed coke masses for further use. To prevent the outlet 24 from clogging, a sheet metal sieve 32 is provided, which allows easy passage of the degassing gases and combustion products while preventing clogging of the outlet by the ingress of coke will.

The oxygen-containing gas is fed into the coal stream led downwards approximately at the upper one The end of the combustion front 30 is injected. This serves to create a warm front in front of the combustion zone so that the downwardly directed coal immediately adjacent to the combustion front heats above its spontaneous ignition temperature and the burn front tends to rise up the retort, but will prevented by a balance that serves to keep this front approximately at the same height Retort to hold practically during the entire service life. Most of the available standing oxygen is consumed in the moving front surface of such a front, and the Oxygen entrained with the gas flow or the coal carried downwards becomes within a short distance consumed, so that the oxidation zone, also known as the "burn front" becomes a limited perpendicular dimension in relation to the perpendicular dimension of the entire Has treatment zone. By consuming all of the available oxygen an oxygen-free atmosphere in the retort area is found in the combustion front this front is maintained, and this means that the coal moving downwards does not burns.

It has been found that this method for the production of coke then runs particularly effective when a temperature range from 600 to 1100 ⁰ C, especially a temperature of about 820 ° C, is maintained in the coal within the combustion front. Since the highest temperatures are reached in the front surface of the combustion zone and most of the oxygen is consumed in the high temperature area, there is a temperature drop behind this front and a further temperature drop as the coal is removed from this front. The insulation of the retort prevents any appreciable heat loss, however, and the hot gases exiting the front provide an effective heating medium on their way to the outlet, maintaining distillation temperatures in the feed within the range of motion from the combustion front to the discharge.

As shown in Fig. 2, the retort widens 14 progressively towards its lower part so as to counteract the expansion of the coal. Only a small amount of the carbon

material content of the coal in the combustion front burned.

The modified retort shape according to FIG. 3 makes use of a guide for the charging of coal bottom up, and the gas flow is also directed upwards in the retort zone, with the combustion front tends to move down into the moving coal charge. In this In turn, a material equilibrium is applied to shape the combustion front with limited vertical expansion at approximately the same height in the retort for a longer period of operation to keep. The retort is also arranged to allow expansion of the solid during heating This is taken into account by an increasing in the direction of the material flow Space is provided. The retort is isolated so that the inside moving from the burn front Coal temperatures are kept sufficiently high for continued distillation.

As shown in FIG. 3, the retort 34 is fed by a belt conveyor 33. The The lower support of the retort 34 has a loading port 35 that corresponds to that of the conveyor 33 picks up incoming coal, and the coal is taken from the loading opening by a mechanism 36 which pushes the charge in through inlet 37 at the bottom of the retort. Of the Coke is discharged over the edge of the retort, the ejection being effected by a rotary stirrer 39 is supported, which represents the upper limit of the vertical retort zone. The stirrer 39 is used at the same time to crush coke pieces of excessive size.

The main part of the retort 34 is arranged within a dispensing chamber 40, which acts as thermal insulation serves. The coke discharged from the retort falls through the chamber 40 and reaches a lower one located delivery point.

An oxygen-containing gas is introduced through the inlet 42, a portion of which is arranged within the retort 34 and has a number of circumferentially arranged nozzles 42 a through which the available oxygen over the cross section of the retort on the moving front surface of the 4s combustion zone 50 is distributed. The developed combustion gases are withdrawn together with the degassing gases in the direction of the coal-coke flow and leave the chamber 40 through the pipe 44.

The chamber 40 is designed as a heat exchanger through the arrangement of a water jacket 43, fed to the water through an inlet 45 and from the evolved water vapor through an outlet 46 is peeled off at the top of the jacket.

The coke is discharged along the inclined floor of the chamber 40 through an outlet part, in which a water inlet 47 is provided for quenching the coke, so that the temperature of the Coke is lowered below its ignition temperature. Furthermore, a discharge device prevents 48, shown here as a star wheel, shows a noticeable drop in pressure while the coke is on a belt conveyor 49 is given for storage or further use.

The degassing process performed in retort 34 is essentially the same as above has been described, with the exception that the direction of flow is different, as is the movement of the Coal more like an intermittent progressive motion rather than a completely continuous one Movement occurs as is the case with the gravity flow in the retort 14 is. Loading with this procedure requires the intermittent pivoting of the loading mechanism 36 around a fulcrum 51, and this mechanism has a sector-shaped component which has a circular arc-shaped part Has considerable width, which engages with an arcuate surface 52 of the lower Support of the retort 34 is located. The sector has a cylindrical part 53 with practical the same diameter as that of inlet 37 of retort 34. A star shaped device 54, which can be driven either hydraulically or pneumatically, can be moved from a lower position from which the same then occupies when the sector-shaped component the cylinder 53 with the loading opening 35 brings to the comparison, bring to an upper loading system in which the The upper surface of the piston practically closes the inlet 37 which is the lower limit of the retort 34 represents. The movement of the loading mechanism 36 is pneumatic by another or hydraulically operated working cylinder 55 brought about.

This arrangement requires a considerable distance to be covered and a corresponding dwell time for the solids rising from the combustion zone 50 in the direction of the retort discharge. This distance and residence time are coordinated so that maximum degassing of the corresponding temperatures is reached. The device of Fig. 3 is good for treatment suitable for both coking and non-coking coals and offers the option of additional to obtain water vapor from the waste heat.

A further modification of the retort is illustrated in FIG. 4, in which a combined charging of coal by the action of gravity and pressure is applied. At this Embodiment, a belt conveyor 63 feeds the vertically arranged retort 64, the insulated Walls 64 a, with coal. The coal discharged from the conveyor 63 falls into an introduction opening 65 of the retort 64 and is by means of a Star wheel 66 assigned to the loading chamber 56 at the upper end of the retort 64. The chamber 56 is cylindrical and has a side opening 57 into which the star wheel 66 incoming batch is introduced. A screw mechanism 58 or the like presses the coal through inlet 67 into the retort. The worm wheel 66 is also arranged so that by the Inlet port 65 a pressure drop is prevented.

The retort 64 widens between the inlet 67 and the combustion front 70, its middle Part is practically cylindrical and ends with a frustoconical discharge. The lower end of the The frustoconical part has the bottom outlet 68 for the coke and represents the lower limit of the A discharge device 69 in the form of a star wheel is provided in this outlet, in order to prevent a pressure drop as well as to bring about an inevitable discharge of the coke.

The air supply pipe 72 is provided with a number of nozzles 72 a arranged over the circumference for distribution of the oxygen on the moving front surface of the combustion front 70. Roll crusher 61 are arranged near the gas vent 74, which is located above the bottom outlet 68. A sieve 62 is provided, which prevents clogging of the gas vent. The coke is discharged via the discharge device 69, the outlet 68, optionally after quenching, on Conveyor belt 59, through which the coke is fed to its further use.

The retort 64 is intended for use in a process that involves significant expansion the solids do not enter, as is the case with non-coking coals or coals with a high content volatile constituents is the case. Pieces of coke of excessive size that move up during heating are reduced to the desired grain sizes by the roll crusher 61.

In the method according to the invention, the combustion front runs in countercurrent to the flow of movement of the imported fuel, with the combustion front at approximately the same height in the retort is held during longer working hours, although this burn front tends to to move in the opposite direction to the movement of the coal.

Claims (1)

Claim: Process for the continuous degassing of coal in a shaft furnace, according to which the Coal is heated directly by flammable gases conducted in cocurrent, and coke and gas are separated be deducted, characterized in that that the coal is fed to a combustion zone together with air in the unheated state, that the combustion zone as a result the oxygen consumption of the gas supplied with the coal only to a narrow one Expansion range limited and that in the degassing zone following the combustion zone Due to the temperature of the now oxygen-free gases, the coal is completely degassed is achieved. Considered publications:
German Patent No. 406,409;
Austrian Patent No. 3758;
British Patent No. 745 808:
"The Oil and Gas Journal," July 1949, p. 90. 1 sheet of drawings 709 718/134 12.67 © Bundesdruckerei Berlin