US1958528A - Hydrogenation system - Google Patents

Description

M y 15, 1934- R. E.-WILSQN 1,958,528

HYDROGENATION SYSTEM Filed NOV. 28, 1930 nUeTlITJ'T Robert E wilson.

Patented May 15,

UNITED STATES- nrnaoenmrron srsrmr Robert E. Wilson, Chicago, 111., assignor to Standard Oil Company, Chicago,

ration of Indiana q c n Application November 28, 1930, Serial No. 498,579

2 Claims.

This invention relates to a combination liquid and vapor phase hydrogenation system and it 7 pertains more particularly to a system for producing desulfurized, high-antiknock gasoline.

The object of my invention is to reduce the overall cost of gasoline production. A further object is to provide an improved means for heating the gases and vapors discharged from a liquid phase hydrogenation reaction chamber and for 10 simultaneouslyreducing the. effective hydrogen concentration so that the vapors may be subjected to avapor phase treatment at a higher temperature and lower partial pressure of hydrogen. A further object is to provide an improved, stable, high-antiknock gasoline. Otherobjects will be apparent as the detailed description of my invention proceeds.

In a liquid phase hydrogenation process ,where a relatively large amount of the liquid is recycled and a large excess of hydrogen is used, conditions are relatively unfavorable fon the production of high antiknock gasoline. 'Under conditions of optimum through-put and ninimum losses the product of a liquid phase 'hydrogenation step is mainly an oil of boiling range similar to that of ordinary gas oil and which usually is not completely desulfurized if the original heavy charging stock was of high sulfur content. some gasoline is formed but this is not of high antikno'ckquality. These products are removed fromthe liquid phase hydrogenation as gases and vapors, and ordi-.

narily must be cooled, condensed, and separated before being subjected to final vapor phase treatment for the production of high quality gasoline.

By highly superheating vapors of a light stock such as high sulfur gas oil or naphtha bottoms,

and introducing these superheated vapors into the v mixture of gases and vapors leaving the liquid phase reaction chamber, I produce a mixture that may be contacted witha catalyst at high temperatures and pressures to give a stable gasoline having a high antiknock value. The process may simultaneously convert, desulfurize and/or stabilize the light hydrocarbons.

In the accompanying'drawing I have diagrammatically illustrated my improved system, parts of the apparatus being shown in section.

Y The charging stock may be any carbonaceous material, such as petroleum residuums, gas oil, pressure tar, etc. (If coal or other solid material is .used it should. preferably be suspended in a liq- \uid oil carrier). It may be conducted from the storage tank 10 through pipe 11, pump 12, pipe -18,'mixer 14, heat exchanger 15, and pipe 16 to .55 preheater or pipe still 17. From the preheater the hot mixture is introduced by pipe 18 into liquid phase catalyst chamber 19. 'I'heliquid phase catalyst chamber is preferably a hollow cylindrical vessel and it is provided with a liquid discharge 9 pipe 20 and a gas and vapor discharge pipe 21,

the former being spaced from the top at a distance of about one-fourth to one-third the height of the tower and the latter being arranged at the top thereof. A pump 20A forces liquid from tower 19 back to the preheater 17 or to an intermediate coil thereof. This pump and the feed pumps are both regulated in accordance with suitable indicators or by float controls (not shown) so that .a constant liquid level is maintained in reaction chamber 19 and so that the amount of liquid recycled through pipe 20 is approximately the same as the amount of fresh feed added through pipe 16. These features per se form no part of my invention and wide variations therefrom are permissible.

Many petroleum oils-contain large amounts of sulfur and the gas oils which are produced from these oils are undesirable because of their high sulfur content. Also, many light hydrocarbons contain potential gum forming substances and have to be stabilized by chemical treatment and/or rerunning. Usually straight run gasolines are characterized by a. low antiknock value. My invention contemplates the use of any light hydrocarbons which it is desired to improve in one or all of these respects, and in the preferred embodiment I use high sulfur gas oil or naphtha bottoms, in addition to the heavy oils treated as above described.

The light hydrocarbons are conveyed through pipe 22, pump 23, pipe 24, mixer 25, heat exchanger 26 and pipe 27 to preheater 28, which is preferably a pipe still designed to vaporize the light oil and to superheat the vapors. The superheated vapors are conducted from preheater 28 by pipe 29, mixed with gases and vapors discharged from pipe 21, andintroduced into a vapor phase reaction chamber 30. This chamber preferably contains a suitable catalyst 31 which is mounted on trays or screens 32. The catalyst may be a: mixture of chromium or molybdenum oxides 'or it may be any other catalyst known in the art. In the liquid phase chamber 19 the catalyst is preferably in finely divided or colloidal state and it is held in suspension by the liquid and is recirculated therewith by means of pump 20A. In the vapor phase reaction chamber the catalyst is preferably in relatively large masses and is commonly referred to .as a fixed catalyst. These features per se form no part of my present invention and are 'not described in detail.

After the vapor phase hydrogenation; the mix-. ture of gases and vapors leaves vapor phase chamber 30 through pipe 33 and is passed through pipes 34 and/or 35 in amounts regulated by valves 36 and 3'7 to heat exchangers 15 and 26. The cooled mixtures are then conducted by pipes 38 and 39 to condenser coils 40 which may" be immersed in a suitable cooling fluid in container 41, the fluid being circulated the container by means of pipes 42. Gases and condensed vapors are discharged through pipe-43 into liquid separator 44 and the liquidv product 45 1 (mainly asoline) is withdrawn through pipe -46 and reducing valve 4'7.

Hydrogen and non-condensed vapors are discharged .from the top of separator 44 through pipe 48 into scrubber tower 49, which contains a suitable packing material 50 supported by screens 51. A scrubbing fluid 52, which is preferably a hydrocarbon oil such as aheavy kerosene, is collected at the bottom of tower49, discharged through pipe 53 and reducing valve 54 to gas relief tank 55, conducted from the bottom of tank 55 through pipe 5'7, pump 58 and pipe 59 to distributing nozzle 60, and sprayed in the.

tower over the packing material countercurrent to the upward fiow of gases. By this means methane and light hydrocarbons are scrubbed out andthe hydrogen is removed from the top of the scrubber through pipe 61, compressed by pump 62 and introduced by pipe 63 back into the system. Make-uphydrogen is added through pipe 64 in amounts regulated by valve 65. Hy-

drogen is introduced into the charging stock and the light oil through pipes 66 and 67' respectively, the relative amounts being regulated by valves 68 and. 69, e

The entire apparatus is constructed to withstand operating pressures of 250-300 atmospheres, although I prefer to carry out the process at a pressure of about 200 atmospheres. The use of suitable alloy steels, insulating materials, en-

- trainment arresters, etc. is of course, contemplated but these details are omitted fromthe drawing for the sake of simplicity.

The operation of my invention may be described as follows: the charging stock which may be a heavy gas ,oil or pressure tar, is forced by pump 12 into the system at a pressure of about 200 atmospheres. For every cubic foot ofcharging stock I introduce about 5,500 cubic feet of recycled hydrogen (from scrubber 49) and about 275 cubic feetof make-up hydrogen (from pipe 64). This mixture of oil and hydrogen, picks up some heat in exchanger 15 and is then heated to a temperature of about 850 F. .n preheater 1'1. The liquid phase reaction chamber is maintained at about 850 F., the exothermic reaction supplying substantially all of the 'heat that is lost by a properly insulated unit.

i The amount of light oil introduced into the system may vary within relatively wide limits and I prefer to 'use one or two'p'arts of light oil to one part of charging stock. It should be particularly noted that the vapor phase treatment is carried out in the presence of the excess hydrogen from the. liquid phase reaction chamher so that large volumes of additional hydrogen are unnecessary. 'It is not necessary to add hy-,-

drogen with the light oil, but I may use up to about 250 volumes of hydrogenper volume of light oil in order to provide more close control of conditions in the vapor-phase preheater a d chamber.

The mixture of light oil and hydrogen isheated in preheater 28 to a temperature somewhat above 900 F. so that the final-temperature of gases and vapors enteringthe'yapor phase reaction chamber is higher than the temperature in the liquid phase chamber. The exact temperatures cannot-be stated for allconditions andwill depend to a large extent on the eflectiveness of insulation, since the hydrogenation reaction itself is exothermic.

I have found that to produce a high, antiknock, st'able, sulfur-free gasoline it is desirable to maintain alower hydrogen partial pressure in the vapor phase than is used in the liquid phase. It isalso desirable to carry on the vapor phase reaction at a higher temperature. I obtain both of these desired conditionsby superheating the light oil vapors,mixing them with the gases and vapors leaving the liquid phase functional relation between the steps, but I find I that by my improved process described herein this end is attained with a maximum thermal efficiency and with a maximum recovery of the desired products.

The cooling, condensing -and separating of my finished products are in accordance with conventional practiceand will not be describedin detail. The expression destructive hydrogenation, as used in the following claims, is hereby defined as a pyrolytic conversion with hydrogen whereby heavy hydrocarbons or carbonaceous materials are converted into low-boiling products, the reaction usually being effected at temperatures of about 850-1000" F. and pressures of about 200-300 atmospheres.

While I have described a preferred embodiment of my invention it is understood that I do not limit myself to the details therein set forth except as defined by the following claims.

I claim:

1. The method hydrocarbons into motor fuel of vhigh antidetonation value which comprises subjecting such hydrocarbons to' destructive hydrogenation in liquid phase, removing gases and vapors from the of converting relatively heavy liquid phase treatment, separately superheating other light hydrocarbon vapors to a temperature above that maintained in the liquid phase treatment, mixing these superheated vapors with those obtained from the liquid'phase treatment,

and subjecting this mixture to destructive hydrogenation in vapor phase in the presence of a hydrogenation catalysiftand at a higher tempera--' ture and under a lower partial pressure of hy- Y drogen than. those prevailing in the liquid phase treatment,

2. The method of converting relatively heavy hydrocarbons into motor fuel of high antidetonation value which comprises subjecting such hydrocarbons to destructive hydrogenation in and under a pressure of about 200 atmospheres,

removing gases and vapors from the liquid. phase treatment, admixing therewith separately superheated light hydrocarbon vapors 'whereby the mixture will have a temperature of at least 900 F.

and a partial pressure of hydrogen lower than that prevailing in the liquid phase treatment, and

liquid phase at a temperature of about 850 F. l

then subjecting this mixture to destructive hydrogenation in vapor phase at a temperature of at least 900 F.

ROBERT E. Wilson. 15o

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