US1888926A - Coke oven - Google Patents

Description

Nov. 22, 1932. LAMBERTZ 1,888,926,

COKE OVEN Filed May 11, 1925 3 Sheets-Sheet 1 NOV. 22, 1932. LAMBERTZ 1,888,926

COKE OVEN Filed May 11, 1926 3 Sheets-Sheet 2 G. LAMBERTZ 1,888,926

com: ovsn Filed May 11. 1926 3 Sheets-Sheet 3 Nov. 22, 1932.

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Patented Nov. 22, 1932 UNITED STATES FATE OFFICE GUSTAV LAMBERTZ, OF REGKLINGHAUSEN, GERMANY, ASSIGNOR TO CARL STILL, OF REGKLINGHAUSEN, GERMANY COKE OVEN Application filed May 11, 1926, Serial No.

My invention relates to improvements in coke ovens for the dry distillation or carbonization of coal at high temperatures, especially coke ovens of this kind having high and relatively narrow coking chambers, the main object being to ensure as great a yield as possible of by-products and the production of coke of best quality. Other objects will hereinafter appear from the following description and annexed claims.

Repeated attempts have been made in the dry distillation of fuels in closed chambers or retorts, in such ones also of great height and relatively small width, to remove all of the volatile products of carbonization at a point near the bottom of the chamber, for instance by means of pipes hanging in the charge vertically from above, or by hollow spaces provided in the bottom part of the charge, or by like means. By this method of operation an improvement in the quality and yield of the products of carbonization, especially of the hydrocarbons was expected, because it was assumed that by being removed in a downward direction they would preferably have to find their way through the middle cooler portion of the charge and thus avoid the disadvantages due to the destructive influences of the hot oven walls. However, the hoped for advantages did not materialize in practice, or only partly, and therefore this method of operation has found but little application.

Now my invention is based on the novel discovery that these failures experienced in the removal of the gases downwards was due to the fact, that the influence which the heating of the chambers or retorts exerts on the internal process of the chamber was overlooked.

For illustrating both the prior art and the novel features of my invention reference will be made to the accompanying drawings in which all the Figures 1, 2, 3 represent similar cross sectional elevations of horizontal coke ovens with vertical heating flues, each comprising one coking chamber and two adjacent heating walls. Herein the Figs. 1 and 2 refer to usual and known arrangements,

108,314, and in Germany May 13, 1925.

whereas the Fig. 3 shows an arrangement according to the invention.

In order to make clear my invention and to explain its base, firstly the known process of carbonization in a coke oven, heated and operated in the usual manner with removal of the products of carbonization at the top of the chamber may be described with reference to the Fig. 1 as follows:

According to the generally accepted opinion strengthened by experience, there are, in a coal charge subjected to carbonization, two layers a (of. Fig. 1) of small thickness (30 to 40 mm) running parallel to the two heating walls, consisting of coal in the plastic stage, which contains much tarry and bituminous matter and forms a foamy mass; the two layers a, usually called plastic stage zones or coking seams travel according to the progress of carbonization towards each other and finally meet at the oven centre. On the inside between these two layers, lies raw, unconverted coal 6 with an initial temperature of about 100 C., which is slightly increased later; on the two outsides there remains the finished coke a of high temperature (about 900 to 1000 C.) and of very strong and dense structure interspersed with a network of horizontal and vertical fractures of varying depth, but generally not reaching the plastic stage zones. Between the coke c and the walls d owing to the shrinking of the coke a narrow fissure 8 is formed along the full area of the wall.

The plastic stage zone or coking seam a is undoubtedly the place where the chief products of carbonization including water vapour are formed. The gases and vapours here liberated naturally tend to travel away from the dense coke 0 to the loose, low resisting raw coal 6 and for this reason a permanent advancing of gases and vapours from the plastic stage zones (1 to the interior space 6 will take place.

In the oven chamber therefore a relatively cool column of continuously renewed gas I) consequently of higher specific gravity, and two very hot columns of gas 0 of much lower specific gravity, coexist. Such a system cannot be in equilibrium. On the contrary, a circular flow between I) and c arises and exists, downwards through I) and upwards through 0, because the separating layers, i. e. the plastic stage zones naturally cannot form absolutely hermetically sealed joints, particularly at the bottom of the chamber. This flow within the oven chamber is shown in Fig. 1 by arrows.

There is no doubt, that, in the lower part of the oven chamber, owing to the greater weight of the gas column b, freshly produced cool gases and vapours from I; pass through the leakages of the plastic stage Zones a towards the heated chamber walls d. These passing gases and vapours act as a cooling agent to the hot walls cl, become heated and, owing to the buoyancy obtained, rise along the walls through the existing fractures of the coke c and the fissures s upwards and are only thereafter removed through the opening 6 in the roof of the chamber. While passing through the incandescent coke c and along the highly heated walls at many useful by-products contained in the gases and vapours are cracked and destroyed, and therebythe quality and yield of such byproducts is diminished, which is a result well experienced in practice.

Obviously, however, the described current of the gases within the charge and especially within the lower part thereof, which current causesthe undesired overheating of the gases, simultaneously serves as a means of equalizing the differences of the rate of heating due to the usual methods of heating which have been dealt with in Fig. 1. If, as it is customary, the total amounts of both heating gas and air for combustion are supplied at asingle point at the base of the heating flues as shown in Fig. 1, then a very high temperature of about 1500 C. and more exists 'at this point ofcombustion, as the fusion of the brickwork which often takes place at this point indicates, but a lower temperature of about 1100 C. will be found at the top of the heating flue, whilst a temperature of 900 to 1000 C. for the finished coke in the chamber would be suflicient. Under these conditions the distillation and carbonization at the bottom of the charge proceeds more rapidly than in the upper parts. As a consequence, the plastic stage zonesor coking seams a which are assumed'as parallel in Fig. 1 really advance quicker at the lower than at the upper parts and meet each other in the centre of the charge earlier at the bottom than at the top. This irregularity has also been proved by actual experience. However, it has been overlooked that the influence of the flow of gas within the oven chamber diminishes this irregularity which would be greater and more injurious if that influence would be absent.

Now, when it is assumed that the gases and vapours in a coke oven referred to above and shown by Fig. 1 are removed from the lower part of the charge instead of at its top, then not only is the flow of gas within the charge itself changed but as a consequence, and in a remarkable manner, the influence of the heating also. This discovery and its useful application are new and most important, and form the base of the present invention. Therefore, a detailed explanation also of the said modification of the known method of operation described before and shown by Fig. 1 will be given in the following with reference to Fig. 2. The method illustrated by this Fig. 2 contrasts the method employed in Fig. 1 thereby that, instead of removing from the chamber the gases and vapours through an opening in the chamber roof, in the case of Fig. 2 a perforated pipe 7" arranged near the bottom of the coking cha1nber is provided for the same purpose.

The flow of gas in the lower part of the charge as shown in Fig. 1, i. e. from I) through a and towards c is impossible in Fig. 2 owing to a point of minimum pressure at the pipe 7" having been created, or what amounts to the same thing, owing to the direct drain of the descending gas column Z) through the pipe 7'. Contrariwise to Fig. 1, even the gases produced within the coke layer 0 at the end of the coking period (especially hydrogen) will flow in the neighbourhood of the exhaust pipe 1' from 0 through leakages of or towards b. In the upper part of the charge, where the direct influence of the exhaust pipe 1" is diminished,

partial quantities of gas will perhaps pass from I) through a towards 0 and travel circularwise as shown in the drawings. But this flow can be only very slight owing to the small height of gas columns and the low pressure differences arising therefrom.

With the change of the flow of gases 1n the lower part of the oven chamber referred to in Fig. 2 the heat-equalizing influence of the flow of gas on the unequal heating of the chamber wall d, as explained before with reference to Fig. 1, must necessarily cease. The higher heat caused by the flames in the lower part of the charge will act and prevail far more intensively than with the usual method corresponding to Fig. 1. The plastic stage zones a approach each other at the bottom far quicker than at the top of the charge and finally meet at the exhaust pipe 'r' long before doing so in the upper part and, after the coking process has proceeded but a short time, there appears a trough-like formation of the said zones as shown by the dotted lines a in Fig. 2.

This condition indicates that the exhaust pipe 1" is entirely surrounded by finished incandescent coke. Thus all the gases and vapours produced must consequently penetrate the incandescent coke before entering the pipe 1". In this case even a large quantity of the charge will flow along the heated chamber wall, at any rate over a part of it, because here the least resistance is offered and the travel of the gas is most convenient. Already before the condition shown by a of the plastic stage zones has arisen, the flow of gas will be modified in the manner described and the gases and vapours will pass, at least partially, in the neighbourhood of the pipe '7' through the incandescent coke, as soon as the two plastic stage zones meet at this point in the centre of the chamber. Given such conditions of flow of gas in the chamber, naturally all those disadvantages and dangers referred to above occur again, which are customary when removing the gases upwards but which ought to be avoided by removing them downwards and through the centre of the charge. The said premature progression of the coking process that occurs therefore in the lower section of the chamber due to the defects in the usual method of heating, has been recognized by the inventor as the cause of the failures in former attempts to carry away the gases in a downward direction.

After having explained before the usual and known methods of operating coke ovens of the kind referred to and after detecting and clearing up the failures of the same, the

. followin descri )tlOD of in invention and its effects will be easily understood. For this purpose, reference is made to Fig. 3 of the annexed drawings.

Briefly stated, my invention consists in the combination of means for the removal of the volatile gaseous products of carbonization from the bottom of the chamber or retort with means for controlling the heating of the chamber walls as to the vertical direction, which controlling is accomplished in such a manner that a substantially uniform heating over the entire height of the chamber is achieved and that in the vicinity of the draw-off point of the gases a premature process of coking. as described in Fig. 2, becomes impossible.

Naturally, the said means required for heating must ensure within the heating tines a complete control of the flame tmnperatures over the total height of the heating wall witl'iout being affected by accidental influence. An excellent means free from all objections tziat can be adopted for this purpose is explained in the patent application Petsch Ser. No. 724,708, filed July 7, 1924, and that has been made use of in the coke oven to be described by the following.

For drawing off the volatile gaseous prod nets of carbonization in accordance with Fig. 3, a perforated pipe 1", situated near the chamber bottom, is provided, which, however. could be replaced by any equivalent means. The vertical heating flues are heated by gas entering at the base in the same manner as shown in Figs. 1 and 2 through a gas distrib- 65 uting main h and nozzles f at the bottom of each heating flue. The air for combustion is conveyed by a sole-flue is into passages 71, m arranged within the binder walls which separate the single fines and enters the heating flues at dilferent levels by a plurality of superimposed outlets n. By correctly dimensioning these outlets n, as explained in the said patent application Ser. No. 724,708, the heating of the chamber walls over their total height is practically uniform and can be controlled without trouble. Experience has shown that by employing this method of heating the temperature of the wall surfaces directly acted on by the flames seldom differ from each other by more than a few degrees centigrade at any point. Such a uniform vertical heating naturally ensures an equal progression of the plastic stage zones (is. Therefore, any premature coking of the bottom part of the oven charge is rendered impossible by employing the means described in the said patent application.

By suitably modifying the dimensions of the air outlets it is even possible to introduce a relatively greater quantity of air in the upper part of the flues than necessary for a quite uniform heating and thereby render the heating still substantially uniform but rather weaker at the lower than at the upper parts, which method retards moderately the progress of coking in the lower part of the chamher. In this case the plastic stage zones will meet somewhat earlier in the upper part than in the lower part. Chamber or retort ovens operated in the usual manner by removing the gases upwards through the roof and supplied with greater heat in the top sections are considered disadvantageous on account to the overheating of the ascending gases and vapours. By removing the gases and vapours downwards as herein proposed, however, such considerations do not arise. On the contrary the higher rate of heating in the upper part and the diminished rate in the lower part of the chamber brings advantages to the suction of the gas because by this means an uninterrupted flow of the gases and vapours arising from the plastic stage Zones will be assured through the centre of the charge towards the draw-off point which flow takes place practically over the total area of the charge and during the full period of coking.

From the above description it is evident that the downward suction of the volatile gaseous products of carbonization through the interior of the oven charge and their draw-off at or near its bottom can only be practically and successfully achieved by combination with means for uniform and easily controllable vertical heating. Only by this combination which avoids surely the premature coking of the bottom part of the charge and the resulting stoppage of the draw-off point by incandescent coke the effect is obtained that the gaseous distillation products will be led 0E without any obstruction and damage and with useful saving of the valuable by-products.

The invention is not limited to the special constructions described and shown. For example, the peculiarity of arranging vertical heating flues is in no way a necessary condition for constituting the invention. Any means which ensured the control and uniformity of the heating of the chamber wall as to the vertical direction, when combined with means for drawing oif gaseous products of distillation at or near the bottom of the chamber, fall within the scope of this invention.

lVhat I claim is:

1. In an intermittently operable horizontal coke oven, a coking chamber, vertical heating flues, means for feeding combustible gas to said flues adjacent the base thereof, means for supplying the total combustion air in several definite portions to said flues at different levels above the gas inlet, required to produce a gradual combustion and nearly uniform heating throughout the length of the flues, in combination with means for drawing off gaseous distillation products adjacent he bottom of said coking chamber.

2. In an intermittently operable horizontal coke oven, a coking chamber, vertical heating flues, means for feeding combustible gas to said flues adjacent the base thereof, means for supplying the total combustion air in several. definite portions to said flues at different levels above the gas inlet, required to produce a gradually increasing combustion and a nearly uniform heating throughout the length of the flues, in combination with means for drawing off gaseous distillation products, adjacent the bottom of said coking chamber.

3. In an intermittently operable horizontal coke oven, a coking chamber, vertical flues defined by walls certain of which are pro- 1 vided with vertical air passages having outlets adapted to discharge into the flues at different levels in each of said flues, the cross sectional areas of said outlets increasing from the base of the flue toward the exit end thereof, and means for feeding gas to the base of the flues, in combination with means for drawing off from all levels of the chamber gaseous distillation products adjacent the bottom of said coking chamber.

In testimony whereof I affix my signature.

GUSTAV LAMBERTZ.

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