US2041957A - Method of working up low valued materials such as pitch, acid sludge, and the like - Google Patents

Description

l May 26, 1936. A. REIS METHOD OF WORKING UP LOW VALUED MATERIALS SUCH AS FITCH, ACID SLUDGE AND THEr LIKE Filed Feb. l0, 1933 Affari: efr

Alfrecli Patented May 26, 'i936 v UNITE STATES 'M'ETIIOD OF WORKING UP LOW VALUED MATERIALS SUCH AS PITCH, ACID SLUDGE, AND THE LIKE Aurea nels, Berlin-Lichterfelde, Germany, as.

signor to Pape & Co., G. m. b. H., Ralilstedt,` Germany, a corporation Application February 10, 1933, Serial No. 656,204

l In Germany February 16, 1932 l 9 claims. (c1. 19e-'14s) This invention relates to processes for working-up pitch, tar, acid sludge and other combustible substances by heat treatment with the exclusion of air, for the purpose, in particular, of producing liquid fuels. 'I'he process differs essentially on the one hand from coking processes which produce coke in coherent form, and on the other hand from cracking processes in which the avoidance of the formation of appreciable amounts of solid coke-like residues is important if the process 'is to be of technical or commercial value.

The process in accordance with the invention mayV be employed for example for working-up acidpitches or acid'sludges of .a1l.kinds which are accumulated in the refining of petroleum and like products and are not only worthless but extremely troublesome. It is possible by means of the invention to obtain from these materials light liquid hydrocarbons, that is to say a valuable product. y

The process is also suitable in particular for working-up inferior heavy oils and bituminous substances and similar products which remain over from the treatment of petroleum or coal.

'I'he hydrocarbons obtained by the process in accordance with the invention represent especially readily volatile, .gasoline-like fuels of high quality which exhibit no tendency to knock.

' A process i'or working-up' acid sludges is known v'in which the 'organic sulphur compounds are y The main object of this process is to work-up the gas mixture obtained. for the manufacture of sulphuric acid. The organic material is mostly. converted into coke and only a moderate proportion can be obtained in the form of liquid hydrocarbons. The quality of the hydrocarbonsv produced is necessarily inferior under these circumstances. A process for working-up acidA sludges is also known accordingto which these are carefully and gradually heated in stages in l order to prevent scum or foaming.

`In'contradistinction to these known processes the essential feature of theprocess according to the invention is that the Imaterial to be treated, for example the acid sludge, is introduced into a retort heated to red heat and is heated with the exclusion of air and gasied. For this purpose a temperature of about 700 to 800 C. has proved to be suitable.

The single iigure of the drawing is a diagrammatic elevation of the invention, portions ofthe apparatus being broken away. l

In this drawing the reference numeral 2 indicates a sheet metal container into which the acid sludge or other material to be treated is placed. This container is heated by suitable heating means such as by the burner I. Fromthis container 2 the material .flows to a mixer or mill 6 after which it flows to a container 8. The material is pumped from the container 8 by the pump Il) through the pipe I2 to the dust separator Il, which is illled withRaschig-rings I8.

The gases evolved in the retort I8 simultaneously enter the separator I4 from below through the opening 20. These gases pass upwardly through the separator Il as the liquid material iiows downwardly therethrough. The liquid material together withv4 solid particles it has picked up from the gases pass from .the separator I4 to A the mill 6 and back to the container 8. The material is also drained off by the pump,22 from this container and forced through the pipe 24 to the atomizer nozzle 26 at the' top of the retort il. y

`The atomized material passes downwardly.

through the retort and is gasified and evaporated therein. The retort is provided with Scrapers 3l which extend from top to bottom. They are ro,

tated by means oir a shaft 36 and a pinion gearA 38 which engages gear teeth on the inner cir cumference on the annular ring 35 to which the sera-pers are attached. -The outer circumference of the ring 35 is provided with a peripheral groove 31 which is engaged by an annular ring Ill'se-v cured to the wall of the retort i8. This ring 39 supports the scraper assembly and permits the same` to rotate when driven by the pinion gear 38. The larger solid particles of the material Y* fall down into a wormA conveyor 4U Awhich-conveys.

away these particles, which are chiefly coke. 'I'he gases and vapors which are formed pass through the opening 42 to a centrifugal separator 44 which separates the finer solid particles and collects them in a worm conveyor 46. 'I'he gases nally pass through the pipe 48 to the dust separator i4 where they are cleaned again and from the dust separator they vpass through the to a cooling apparatus (not shown).

The vapors and gases may be passed to a cracking chamber 52 as will be hereinafter described.

On introducing the starting material into the red hot retort the greater part is converted by the action of rapid heating, in particular by the radiation of heat from the wall of the retort,

into vaporized hydrocarbons andbesides ashes only alittle coke-like residue is produced. A considerable part of the hydrocarbon vapors given olf can be obtained by fractionationinthe form of valuable fuels, the physical and chemical properties of which resemble those of a good gasoline obtained by a cracking process.

The process is based, as has been emphasized pipe above, on the employment of an unusually rapid heating of the raw material in a gasifying chamber of which the walls are heated to a high temperature and act mainly by radiation on the raw material. In order to increase the area of the radiating surface and to reduce the thickness of the layers through which the radiation passes the gasifying chamber may be provided with builtin parts or insertions which must also be heated to a high temperature.

With the rapid heating there are necessarily associated the features that the amount of material present in the gasifying chamber is kept small and the duration. of the material in the chamber is short. It has been found that by suitably regulating the operating conditions any material can be gasified in a very short time in such a manner that only a dry solid residue remains over.

A particularly suitable method of carrying the process according to the invention into effect is to introduce the material into the gasifying chamber in a finely divided form which may be effected in particular by atomizing or disintegrating the liquid or liquefied material through nozzles or by other known means for this purpose.

In the process according to the invention the size of the drops, the intensity of the radiation and the duration in the gasifying chamber must be relatively regulated or adapted to suit one another in such a manner that the residual grains leave the gasifylng chamber in a condition in which they have been sufliciently used up. The

period of duration in the gasifying chamber and the passage of the drops through it can also be regulated by the introduction of gases which exert no harmful effect on the gasied material.

It is also important that the drops in the middle of the retort, that is to say those lying furthest away from the radiating surface, are subjected to a suiiiclently intense radiation. The density of the drops, therefore, must not be so great that the radiation is too strongly absorbed before it reaches the middle of the retort; on the other hand, the economy of the process requires that the permissible density of the drops and, therefore, the permissible output of the ga/ sifying chamber is sufficiently utilized. This taking into consideration of the absorption of the radiation in the gasifying chamber which is filled with drops is, therefore, a feature of the process.

Example 1 As the gaslfying retort there is employed a vertical iron `tube of 40 cm. internal Width and 3 metres-in height. Into the retort, which is heated to '150 C., molten petrol-pitch is blown-in from the top through an atomizing nozzle, the output being 60 kg. per hour. The size of the drops is of the order of 0.1 mm'., the period of duration in the gasifying chamber is of the order of 1 sccond. The pressure in the retort is the atmospheric pressure. For regulating the atomization and the movement of the material in the gasifying chamber the gases resulting from the decomposition are employed.

An important advantage of the process is that the vapors formed in the gasifying chamber may be conducted to a following heat treatment process (cracking) of any desired nature without previous condensation, and that for this cracking process the temperature, the duration of the process and the form of the cracking chamber 52 may be entirely independent of the gasifying condiformation of troublesome scum or foam.

tions. Since the most favourable conditions for the gasifying process and the cracking are in general considerably dierent, the division of the heat treatment into two parts enables the operation to proceed more advantageously than when the same conditions are maintained during the entire heating. According to the conditions. the gasifying chamber and the cracking chamber can be fitted in two separate furnaces or in one furnace.

It is advantageous in many cases to separate the residual grains formed in the gasifying chamber before introduction of the gas or vapor formed 'into the cracking chamber. Any suitable known apparatus may be employed for this separation and the removal may take place continuously or intermittently. In general it is preferable to separate the residual grains dry, that is to say to maintain the separator atso high a temperature that the tar vapors cannot condense. 'I'he carbonaceous material which remains as residue and forms a valuable by-product in the case of a small ash content.

The process may be carried out at the ordinary pressure or at an increased pressure. The materials obtained, insofar as they cannot otherwise be profitably used, can be returned to the process. This holds good, in contradistinction to the usual cracking process, in particular also for heavy oils and for tar-like or pitch-like`dstillates. In the case of raw materials which cannot be converted by heat alone without dilculty into a liquid which will ow, the admixture of distillates may also assist in facilitating the disintegration.

For the purpose of receiving or for receiving and removing the residue there may be arranged evolution of sulphurous acids during decomposi- 4 tion of acid pitches or acid sludge in the red hot retort, the acid sludge, in accordance also with the invention is intimately mixed before the heat treatment with an excess of basic substances in the presence of water, and the mixture is treated at the temperature of boiling Water or at a somewhat lower temperature until the evolution of gas (sulphurous acid and carbonic acid) is ended. By this means it is possible to allow the gases evolved to escape in a uniform flow without the Although during the neutralization process an emulsion-like mixture of Water and sludge tends to occur, the excess water can subsequently be separated mechanically from the neutralized mixture, so that the neutralized acid sludge can be conducted for further treatment into the highly heated retort in a condition in which it is nearly free from water. As basic additions there may be employed, for example, slaked lime, chalk, dolo-` mite, magnesia, sodium carbonate.

Example 2 10 kg. of chalk are stirred with 20 litres of hot I water and 20 kg. of acid sludge (originating from excess water is poured on and the neutralized acid Dressing.

In some circumstances it is advantageous to mix 'the neutralized acid sludge with other :n terials capable of being cracked before introduction into the retort because the yields of valuable hydrocarbons are then higher than with separate treatment. Further, by intimate mixture of the neutralized sludge with a suiiicient quantity of oil the result can be obtained that there is formed a liquid, easily flowing emulsion which, like other liquids, can be pumped through pipes or sprayed through nozzles. For this purpose there may be employed suitable heavy oils and in particular the heavy oils which collect in the receivers in the treatment of acid sludges.

Example 3 Neutralized acid oil and heated. The proportions of the mixture are 120 kg. of oil to 100 kg. of the crude acid sludge contained in the neutralizedV product. 'I'here is formed an emulsion which 'is stable at 90 C. and flows easily.

With the process in accordance with the invention the whole ofthe sulphur content of the acid sludge remains in the retort residue and is thus rendered harmless, with the single exception of a proportion of sulphuretted hydrogen inthe gas evolved, which can be absorbed in gas purifiers by known methods after condensation oi the liquid fuel.

' I claimz- 1. A method oi' working-up low valued materials such as pitch, acid sludge and the like to produce light liquid hydrocarbons therefrom,

which comprises gasifying and evaporating a portion of said. materials by rapidly passing the same in a nely divided state downwardly through a zone heated by radiation to a temperature equivalent to red heat and at least to about 700 C., and in which air has been excluded.

2. A method oi working-up low valued materials such as pitch, acid sludge and the like to produce light liquid hydrocarbons therefrom, which comprises gasiiying and evaporating a portion of said materials by rapidly passing the same in a tlnely divided state downwardly through a Zone heated by radiation to a temperature equivaient to red heat and at least to about 700 C., and in which air has been excluded, and in' then cracking the vapor thus formed.

3. A method o1' working-up low valued ma#- terials such as pitch, acid sludge and the like to lproduce light liquid hydrocarbons therefrom,

which comprises gasifying and evaporating a portion of said materials by rapidly passing the same in a finely divided sta-te downwardly through a zone heated by radiation to a temperature equivalent to red heat and at least to about 700 C., and in which air has been excluded, separating the solid particles from the vapor formed, and

subjecting the vapor without being condensed to a cracking process.

4. A method of working-up low valued materials such as pitch, acid sludge and the like to sludge is stirred with heavy through a zone heated by radiation to a ternperature over 700 C. and from which oxygen has been excluded, and cracking the vapor thus formed.

5. A method of Worg-up low valued umta-l1 g rials such as. pitch, acid sludge and the like to produce light liquid hydrocarbons therefrom, which comprises gasifying and evaporating a portion of said materials by rapidly passing the same in a iinely divided state downwardly through a zone heated by radiation to a temperature equivalent to red heat and at least to about 700 C.,and in which air has been excluded, regulating the duration of the passage of the divided material through said zone by introducing into it said zone a gas which does not ailect the properties-of the material and which by its own velocity regulates the passage oi the material.

6. A method of working-up low valued mate- `rials such as pitch, acid sludge and the like to 20 in a iinely divided state downwardly through a zone heated by radiation to a temperature equiv- 25 aient to red heat, and'in which air has been excluded, regulating the duration `of the passage of the divided material through said zone by introducing into said zone a gas which does not aii'ect the properties of the materials and which 80 by its own velocity regulates the passage oi' the material, subjecting the vapor formed without being rst condensed to a cracking process.

'7. A method of working-up low valued materials such as pitch, acid sludge and the like to produce light liquid hydrocarbons therefrom,

ywhich comprises mixing the material with water and a basic alkaline substance such as chalk' to neutralize said material, rapidly passing said neutralized material in a finely divided state i0 downwardly 4through a 'zone heated by radiation to a temperature equivalent to red heat and at least to about '100,n C. to gasiy and evaporate the same, and cracking the vapor thus formed.

8. A methodof working-up low valued mated5 'raus such as pitch, acid sludge and the like w produce light liquid hydrocarbons therefrom, which comprises mixing the material with water 'and a basic alkaline substance such as chalk to neutralize said material, removing the excess 50 water from said neutralized material, mixing the neutralized material with oil, rapidly passing said mixture in a iinely divided state downwardly through a zone heated by radiation to a teniperature equivalent to red heat to gasii'y and evaporate the same. l

9. A method of working-up low valued materials such as pitch, acid sludge and the like tu produce light liquid hydrocarbons therefrom, which comprises mixing the material with water and a basic alkaline substance such as chalk to neutralize said material, removing the excess water from said neutralized material, mixing neutralized material with Oli, rapidly passing said mixture in a nely divided state downwardly t5 through a. zone heated by radiation to a tenuel perature equivalent to ,red heat to gasify and evaporate the saine, and cracking the vapor thus formed.

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