US1960974A - Refining of crude liquid hydrocarbons - Google Patents

Description

May 29,v 1934.

C. KRAUCH El' AL REFINING OF CRUDE LIQUID HYDROCARBONS Filed June 26. 1931 Carl much INVENToRs m. fL t l L r mv w nu 2. RE E n@ maw BY am ATTORNEYS Patented May 29, `1934 'n UNITED STATES y l umu l BEFINING F CRUDE LIQUID HYDRO- CARBONS Aktien; Germany y t, Frankfort-on-the-Main,

application June ze, 1931, serial No. 541,031 In Germany July 27, 1925 6 Claims. (Cl. ISIS-23) This application is a continuation-impart of the application for Letters Patent Ser.V No. 123,030, iled July 16, 1926.

'I'he present invention relates toa. method for 6 reilning crude liquid hydrocarbons richin hydrogen with a.' view to removing therefrom impurities diminishing the value of said liquid hydrocarbons, as for example, resinous bodies, asphalts, highly unsaturated hydrocarbons of high 10 molecular weight or like bodies poor in hydrogen or substances poor in hydrogenv containingoxygen as for example, phenols or acids, or sulphur. We have found that crude liquid hydrocarbons rich in hydrogen can be purified with great -adl5 vantage by washing them with a mixture comprising methanol and cyclic hydrocarbons of low boiling point, for example, boiling below 100 C. Said cyclic hydrocarbons mayv belongl to the aromatic or hydroaromatic series and'benzene v and its homologues, such as toluene or xylene, or

cyclohexax/'le and its homologues may be employed with particular advantage as admixtures tothe inethanol to formv the washing agent.

By washing we understand extracting, or dissolving out the impurities from the crude liquid hydrocarbons, while the bulk of said hydrocarbons remains undissolved.

The new process is particularly applicable to the puriiication of crude hydrocarbon oils, boiling wholly or for the most part, say to the extent of more than 90 per cent, above 325 C.. which are rich in hydrogen and which contain, for example, more than 13, and preferably-more than' 131/, parts of hydrogen for each 100 parts of 35 carbon. Such hydrocarbons will usually have an averagemolecular weight of 300 to 400 or more. As examples of the crude hydrocarbons, which v may be reiined with advantage in accordance with the present invention may be-mentioned 40 crude lubricating oils, primary tar, the highboiling crude fractions of destructive hydrogenation products, crude mineral oil fractions rich in hydrogen, fractions of low temperature carbonization tar and preferably fractions' of the said hydrocarbons boiling above 325 C. The crude hydrocarbons to be purified are preferably of paraiiinic or naphthenic nature. The washing liquid should preferably contain at least 2 parts by volume of methanol for each part by volume of `the cyclic hydrocarbon employed and usually washing liquids containing between 3 and 5 parts by volume of methanol for each part of cyclic hydrocarbon will give good results in practice. Even more methanol may be present in the said washing liquids and the proportion may be for example 8 parts by volume of methanol to 1 part by volume of the cyclic hydrocarbon. The cyclic hydrocarbon appears to exercise the function of a solvent intermediary, since to a certain degree the separating action is improved, if larger amounts 'of methanol are contained in the washing mixture, but, if the. amount of methanol is increased too much the lseparating action is greatly impeded, since not enough cyclic hydrocarbon is then present to enable it to exercise its beneiicial function. The methanol may be either natural or synthetic.

The amount of washing liquid employed may be varied in a wide degree but good results are obtained in practice b'y working with 1 part or 7o more of washing liquid for eachpart of crude hydrocarbon to be rened.

The washing treatment may be carried out at any suitable temperature, but good results are n obtained in'practice by working at about 15 C. 75 or somewhat higher, for example, at 30 C. If higher temperatures, as for example a temperature of 60 C., be employed it may be advantageous to carry out the washing operation unde pressure as otherwise a considerable volatilization of the washing liquid is liable to occur.

Prior to the washing treatment, itmaybe advantageous to separate solid paraflins from the crude hydrocarbon oils, for example, by cooling to low temperatures and removing the paraiiln wax separated by filter pressing or centrifuging.

The washing operation is preferably carried V out in a continuous mannerand advantageously by counter-current washing. If the crude oil has a higher specific gravity than the washing liquid, when working in counter-current it is preferably introduced-at the top of the washing i apparatus and the washing liquid at the bottom of the said apparatus,l whereas if the Washing liquid has a higher specific gravity than the oil the opposite method of procedure is adapted. For the counter-current'washing operation it is advantageous to employ a high tower or column. How the invention may be carried out in practice will be further illustrated with 'reference to the accompanying drawing, lwhich shows diagrammatically' in elevation and partly in sectionv apparatus which may b e employednin the said process with particular advantage' but it should be understood that the invention is not limited to operations carried out in the said apparatus.

Referring to the drawing A is a container for i crudeliquid hydrocarbon mixture to be refined, B is a' line provided with the valve B1 through ll.

which said crude liquid hydrocarbon mixture is passed to the regulating booster C. Said booster passes the hydrocarbon through lineEtothepoint F where it enters into the washing tower K.l G. is a container for washing liquid which is passed through line H and valve Hi by means of the regulating booster D to the point J where it is introduced into the bottom of the washing tower K. The washing liquid passes upwards in the tower whereas the crude hydrocarbon undergoing treatment pass'es downwards. A surface of separation forms at Kr and the position of the said surface is maintained constant by suitable regulation of the rate of working of the boosters C and D. The column is preferably lled with distributing materials, such as lumps of burnt fire-clay,V Raschig rings and the like. The washed hydrocarbon issues from the tower through valve L and is passed by way of line M to the mid'dle of the distillation column N. The said column N is heated by the coil N1 arranged in the lower part thereof to which hot flue gases are introduced from X through line Nn. The cold flue gases pass off from the said coil at Z. The upper part of the said column N is cooled by the coil Nm, cooling water being introduced at Pr and withdrawn at P. In the said column any Washing liquid contained in the washed hydrocarbon is expelled and passes off by way of line Q to the condenser R. The washing liquid thus ,recovered is returned to the container G by way of line Rr. 'Ihe washing liquid containing the impurities removed from the crude hydrocarbon passes oi from the tower K through valve W1 and is introduced into the middle part of the distillation column O at W. Said distillation column O is heated by the coil Or to which hot flue gasesare introduced through valve X1 and withdrawn through valve Xu. In the other part of said distillation column a cooling coil On is contained to which Water is introduced at Pn and removed at Pm. The washing liquid thus recovered passes olf from the tower 0 at S to the condenser R and is thence returned by way of line Rr to the container G. In addition to or instead of the indirect heating by hot flue gases of the distillation columns N and O, hot nitrogen may be introduced from U into the said towers through the valves V and V1. The refined hydrocarbon oil is withdrawn from the bottom of the distillation column N by way of the pipe T and may be passed to storage or to a place where it may be employed. The impurities recovered from the washing liquids are withdrawn from the bottom ofthe column O by way of line Y.

The following examples will further illustrate how the invention maybe carried out in practice but it should be understood that the invention is not limited to the said examples.

Example 1 Referring to the drawing, a washing liquid consisting of a mixture of 1 part by volume of cyclohexane and 4 parts by volume of methanol was introduced into the container G and a crude Columbian lube distillate into the tank O the boosters C and D were operated at such a rate that the amount by volume of washing liquid present at any time in the tower K was twice that of the amount of lube distillate present. The washed lube distillate containing' a little of the washing liquid was drawn oif continuously from the tower K through valve L and passed into the distillation column N. The refined product was drawn off at T. In the washing tOW- er a temperature of about 30 C. was maintained. The impurities washed out pass off from the distillation column O through line Y and the Washing liquid passes oi at S and after condensation in the condenser R is returned to the tank G. The following table shows the improvement of the oil in the process according to this example Initial oil Retlned product Speciflc gravity 0.022 0.912. Viscosity at 38 0-.... 44.9 39.82. Viscosity at 99 0....... 2.59 2.58. Viscosity index 40 Color D ark greenish- Yellowish-green;

brown; opaque.` translucent. Yield--. 88 to 90 percent by weight.

Example 2 A different crude Columbian lube distillate was treated in the manner described in Example l. The results obtained were as follows:

Example 3 A residue resulting from the distillation of destructively hydrogenated brown coal producer tar (that is brown coal producer tar, which has been subjected to treatment with hydrogen or gases giving off hydrogen at elevated temperature with or without the aid of elevated pressure or catalysts or both and this has been converted into more valuable organic products) is Washed in a counter-current in the manner above described with a mixture of 1 part, by volume, of benzene and between 4 and 5 parts, by volume, of methanol. From the bottom of the column or tower, a nearly colorless oil is withdrawn which has the character of a mineral oil and can be employed, for example, as lubricating oil. It is obtained in aA yield of about 40 to 50 per cent of the crude distillation residue. The mixture of methanol and benzene removed at the upper end of the tower or column contains all tarry and other impurities of the crude residue and may be separated by distillation.

Example 4 A high boiling fraction of a crude German mineral oil is washed in the manner described in the foregoing example. Thereby the impurities contained in the crude product in an amount of about '10 to 15 per cent thereof are removed. The refined product is a valuable lubricating oil free from asphalt.

What we claim is:-

1. The process of refining a crude liquid hydrocarbon, boiling to the extent of at least 90 per cent above 325 C. and containing more than 13.0 per cent of hydrogen for each 100 parts of carbon, which comprises washing said hydrocarbon with a mixture of methanol and a hydroaromatic hydrocarbon of low boiling point.

2. The process of refining a crude liquid hydrocarbon, boiling to the extent of at least 90 per cent above 325 C. and containing more than 13.0 per cent of hydrogen for each 100 parts of carbon, which comprises washing said hydrocarbon with a mixture of methanol and cyclohexane. A

3. The process of rening a crude liquid hydrocarbon boiling to the extent of at least 90 per cent above 325 C. and containing more than 13.0 per cent of hydrogen for each 100 parts of carbon which comprises washing said crude liquid hydrocarbon with at least an equal amount of a mixture of methanol and a hydroaromatic hydrocarbon of low boiling point. v

4. The process of rening'a crud(` liquid hydrocarbon boiling to the extent of at least per cent above 325 C. and containing more than 18.0 per cent of hvdrogen for each 100 parts of carbon which comprises washing said crude liquid hydrocarbon with at least an equal amount of a mixture of atleast one part of methanol for leach part of a hydroaromatic hydrocarbon of low boiling point.

5. The process of refining a crude liquid hydrocarbon boiling to the extent of at least 90 per cent above 325`- C. and containing more than 13.0 per cent of hydrogen for each 100 parts of carbon which comprises washing said crude liquid hydrocarbon continuously in counter-current with at least an equal amount of a mixture of at least one part of methanol for each part. of cyclohexane.

6. A process for rening a crude lubricating oil. which comprises washing said lubricating oil at a temperature of about 30" C. in countercurrent with about twice the amount. by volume. of a mixture of about 4 parts of methanol and one part of c vclohexane.

CARL KRAUCH. LLATHIAS PIER. AUGUST EISENHUT.

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