DE1076667B - Process for converting heavy oils into low-boiling, normally vaporous or liquid, unsaturated hydrocarbons and solid carbonaceous residues - Google Patents

Description

The invention relates to a process for converting heavy oils, in particular for coking hydrocarbon heavy oils at high temperatures for the purpose of producing unsaturated hydrocarbons of low molecular weight. Unsaturated hydrocarbons with a low molecular weight are widely used as starting materials for the production of various chemical substances and polymers. At the same time, the invention aims at the cost-saving production of relatively large amounts of lower aromatic hydrocarbons, such as benzene and toluene, within the boiling range of gasoline, ie below 221.7 ° C together with a group of unsaturated C ₆ - to C ₇ compounds, which because of the ease with which they can be polymerized into resin products are called resin formers. These substances are not only useful as chemical raw materials and solvents; most of them are in great demand as engine fuel ingredients even in large quantities at high prices where high quality is required.

A preferred coking process is a process in which fluidized or suspended particles used as heat carriers with an average diameter within a range from 5 to 1500 μ, preferably from 20 to 400 μ, which are essentially catalytically inert.

The high-grade conversion of heavy oils, e.g. B. petroleum residues in dry gas, ie C ₃ - and lighter hydrocarbons, can be done in a known manner by heat cracking at high temperature. Conversion into dry gas is intended to _{denote the conversion into C 3} and lighter hydrocarbons as well as hydrogen, whereby the amount of the products occurring as gases is either in cubic meters per. . Kilograms of feed or expressed as a percentage by weight of the original feed on a coke-free basis. The latter term is discussed in more detail below, but in general, coke-free feed means all of the feed minus the amount eventually converted to dry coke. Conversions of this type carried out at high temperature generally give good yields of ethylene when the temperature is above 648 ° C. With increasing temperatures and longer conversion times, ethylene production increases along with the production of other light gas products. Achieving dry gas yields of 40, 50% or even more is not uncommon. In other words, it means that it is not unusual when there is a process of conversion
from heavy oils to low-boiling,

usually vapor
or liquid, unsaturated hydrocarbons and solid carbonaceous ones
Residues

Applicant:

Esso Research and Engineering Company, Elizabeth, N.J. (V.St.A.)

Representative:

Dt. W. Beil and A. Hoeppener, lawyers,
Frankfurt / M.-Höchst, Antoniterstr. 36

Brook I. Smith, Elizabeth, N.J.,

Harold W. Scheeline, West Orange, N.J.,

and Edward D. Boston, Westfield, N.J. (V. St. A.),

have been named as inventors

• ■ '' man 0.44, 0.50 ^! m ³ and more per kg of input material • produced.

The invention is based on the finding that conversions that are milder are often more effective and are more cost-effective. High-grade conversions lead to a substantial destruction of products with 4 or more carbon atoms, and these are usually the most valuable of all substances produced.

Furthermore, the yields of low molecular weight materials such as hydrogen and methane and other products of little economic value are quite high.
^: On the other hand, at a very high transition temperature z. B. 704 ° C or higher and especially above 815 ° C, the yields of aromatics, such as. B. benzene, rapidly with increasing temperature. The same also applies to the yields of acetylene hydrocarbons. Where butadiene is a desirable product, as is usually the case, the production of C ₄ acetylene in large quantities is particularly undesirable because of the very considerable difficulties involved in separating the latter from butadiene. Therefore, if butadiene, iso-

909 758/532

pren, resin-forming substances in the range of the C ₀ to C ₇ compounds are produced simultaneously with benzene in a single economical process, increased yields of any of these compounds are only possible at the expense of considerable losses from some of the other compounds. The control of the process conditions to achieve high yields, e.g. B. of butadiene and resin formers with C ₆ - and C ₇ chains while achieving reasonably high yields of benzene and related aromatics causes considerable difficulties.

Usually the most desirable products obtained by thermal cracking of heavy hydrocarbons at high temperatures are the C ₄ and C ₅ diolefins such as e.g. B. butadiene, isoprene, piperylene and cyclopentadiene. These are used in large quantities in the manufacture of synthetic rubber and related polymers and copolymers. The next most valuable products under current economic conditions are the unsaturated resin formers with a C ₆ or C ₇ chain mentioned above. Next in sequence are the lower aromatics, such as benzene, toluene, and unsaturated aromatic resin formers, e.g. B. styrene and indole. Other unsaturated products, such as ethylene and propylene, have some value, but the lower saturated hydrocarbons, such as ethane and methane and hydrogen, have the lowest value. The diolefins are usually produced in relatively small amounts. Attempts to greatly increase the yield of these products usually result in severe losses in the yield of other products.

A particular object of the invention is therefore the production of almost maximum yields of C ₄ and C ₅ diolefins and C ₆ to C ₇ resin formers together with a good yield of C ₆ arotnates of up to 221.7 ° C boil. The control takes place by the coordinated regulation of the conversion temperature and the conversion time for the purpose of controlling the total dry gas production and a further control by the use of a low hydrocarbon partial pressure at the end product outlet opening. In particular, it appears that control of the overall conversion to dry gas is of great importance because the yields of the most desirable products, particularly diolefins and resin formers, vary considerably with this ratio. They also fluctuate in usually inverse proportion, and indeed very rapidly, but the hydrocarbon partial pressure is maintained in the reaction area.

In the drawings, Fig. 1 is a graph showing the effect of dry gas conversion on the total _{yield of C 4} to C ₅ diolefins plus C ₆ to C ₇ resin formers.

Fig. 2 is a graph showing the effect of dry gas _{conversion rates on total yields of C 6} to C ₈ aromatics plus resin formers which are C ₅ compounds and boil up to 255.4 ° C;

Fig. 3 shows schematically a typical conversion system, that works at high temperature and is suitable for carrying out the process.

It can be seen from Figure 1 that the graph shows a total _{yield of C 4} to C ₅ diolefins plus the unsaturated, predominantly linear and polymerizable hydrocarbons which can be used to make light colored resins and are commonly called resin formers. Assuming a coke-free feedstock and based on weight, this yield increases with increasing temperature. That being said, however, the total at any temperature reaches a maximum approximately at the point where the dry gas (C ₃ ) yield is between 0.37 and 0.43 m ³ per kg of coke-free feed. The effect of the dry gas conversion rate is very surprising and does not depend on the conversion temperature in any way. At a given temperature, the lower dry gas _{conversion level produces fewer C 4} to C ₅ diolefins and more C ₆ to C ₇ resin formers than higher levels of conversion. However, all of these pass through a precisely defined maximum value. This is true although the overall conversion of the feed to coke and other gaseous or liquid products remains essentially unchanged. These data are given in FIG. 1 and are shown in more detail in Table 1. The feed used to obtain this data was a South Louisiana residual oil.

Table 1 Effect of the degree of conversion

Durdi run no.
2 1 3

Temperature, ° C

KW partial pressure kg / cm ² abs.

Conversion into C ₃ and lighter gas:

Feedstock, m ^s / kg

Coke-free feed, m ³ / kg

Yield, percent by weight based on that
Input material

C ₄ to C ₅ diolefins

C ₆ to C ₇ resin formers

Other gaseous and liquid products

coke

Percentage by weight, based on coke-free
Input material

C ₄ to C ₅ diolefins plus

C ₆ to C ₇ resin formers

682.2
0.56

0.160
0.217

1.5
3.4

78.1

17th

5.9

676.6
0.56

0.287
0.346

4.8
2.5

75.7

17th

8.8

682.2
0.35

0.346
0.418

5.3
1.9

75.8

8.7

686.6
0.35

0.569
0.686

3.4
1.1

78.5

17th

5.4

It is evident from FIG. 1 and from Table 1 that the optimum degree of total yield of C ₄ to C ₅ diolefins and C ₆ to C ₇ resin formers is achieved by having a dry gas conversion between 0.25 and 0.50 m ³ / kg feed is held on a coke-free basis. The mentioned coke-free base is first determined by directly measuring the weight of the dry coke produced, this amount being subtracted from the weight of the feedstock. However, on the basis of a number of determined data, it is quite possible to calculate the coke-free input quantity after knowing the Conradson coal residue number of the charge in percent by weight. If it is a gas oil or similar material that has essentially no Conradson coal residue, the amount of "coke-free feed" is equal to the amount of "feed". On the other hand, if the feed consists of residual oils which have significant Conradson coal residue, a correction factor must be used. This correction factor, which converts the specified range of 0.25 to 0.75 m ^{3 of} feedstock, based on coke-free feedstock, into the actual number of cubic meters, based on the actual feed, is calculated as follows for each feedstock:

P = G (I -0.01 R)

where P represents the actual optimal dry gas production expressed in ^ms dry gas (C ₃ ) per kg actual feed, G is the number m ⁸ dry gas (C ₃ -) per kg coke free feed, and R represents the Conradson coal residue.

If the Conradson coal residue is known, this value is used in the formula. The lower value of the feed is then determined by substituting 0.25 for G in the formula, the upper feed amount is obtained by substituting 0.5 for G in the formula.

The following example explains the use of the formula to determine the optimal production of C ₄ to C ₅ diolefins + C ₆ -C ₇ resin formers:

Assuming R— 17, then using the lower value 0.25 for G results in the following value for P:

P = 0.25 (1-0.01-17)
= 0.2

For the upper value 0.5 of G we get:

F = 0.5 (1-0.01-17)
= 0.4

These two values 0.2 and 0.4 are the minimum and maximum amounts in m ^{3 of} dry gas that are produced per kg of feed in this special case.

The optimum range only shifts within moderate limits if the most valuable products are the C _{6 to} C ₈ aromatics plus the largely aromatic unsaturated hydrocarbons with a broader boiling range. The latter range from C ₅ compounds (isoprene, piperylene) to a boiling point of 272 ° C. and are generally known as resin formers because of their easy polymerizability.

These hydrocarbons usually give hard and dark colored polymers. The proceeds are indicated graphically in Fig. 2, where the maximum values appear very sharply delineated. The total yield is higher at lower temperature, i.e. H.

exactly the opposite of the results shown in FIG. However, the maximum values (total values) are still in the range from about 0.31 to 0.62 m ^{3 of} dry gas per kg of coke-free feedstock. The same general phenomena are observed when moving to a different type of feed. As long as the operating conditions are maintained so that dry gas conversion is achieved within the preferred limits, the yields of the most valuable products will remain high.

As shown in Table 2, and when the conversion conditions were adjusted (by controlling the contact time) to keep the dry gas yield constant (based on coke-free starting material), the yields of butadiene, C ₅ diolefins and C ₆ to C ₇ resin formers remained correct constant.

Table 2
Influence of the nature of the input material

Input material example A. B. unprocessed South 25th killed gas oil Louisiana Return Temperature, ⁰ C standing oil KW partial pressure, kg / cm ² abs. 682.2 682.2 Conversion to C ₃ and slightly 0.35 0.35 30th teres gas: Input material, m ³ / kg .... Coke-free feedstock, 0.416 0.347 m ³ / kg Yield in percent by weight 0.416 0.416 35 on a coke-free basis Total dry gas with substantial shares Ethylene, propylene, Me than USW 40 Butadiene 43.3 39.3 Ci diolefins 32 3.1 ü
C ₆ to C ₇ resin formers .... 3.1 2.9 Other C ₄ products that go up 2.7 2.5 45 Boil 221 ° C 24.8 20.8

The two feedstocks shown in Table 2 are quite different from each other. The raw gas oil has essentially no Conradson carbon residue number, while the South Louisana heavy residue oil has a very large residue, 17%. Based on the total amount used, the conversion to dry gas was 39.3 percent by weight for the residual oil and 43.3 percent by weight for the raw gas oil. However, the overall _{yields of butadiene, C s} diolefins and C ₆ to C ₇ resin formers remain almost the same. The calculation of the actual dry gas production to indicate the optimal production of C ₆ to C ₈ aromatics plus the largely aromatic C ₅ resin formers up to the boiling point 272 ° C is carried out

according to the formula given above: P = G (1-0.012?).

But here G is preferably in the range 0.3783-0.623 rather than 0.2492-0.4984. Of the The total range for all products is between approximately

0.2492 to 0.623 m ^{3 of} dry gas per kg, based on coke-free starting material. The absence of coke in the starting material is important here.

If one now considers the effects of the hydrocarbon partial pressure, it can be seen from Table 1 that this is 0.56 kg / cm ² abs. in the first two work steps, in the last two, however, 0.35 kg / cm ² abs. fraud. In Table 2, Examples A and B were at 0.35 kg / ² abs. (using steam to reduce the partial pressure) performed. For the optimal production of C ₄ to C ₅ diolefins, the lower partial pressures are to be preferred, whereas higher pressures are suitable for the production of aromatics. The preferred working conditions for the two general product classes are listed in Table 3.

Table 3 Preferred working conditions

C4 to C6 diolefins plus
Ce to C7 resin formers

Main product

Ca to Cg aromatics

plus Co-resin formers,

which boil up to 254.4 ° C

Conversion to C ₅ and lighter gases, m ³ / kg of coke-free feed

Temperature, ⁰ C

KW partial pressure

From the foregoing it will be seen that control of the degree of conversion, as measured by the production of dry gas, is an important factor in controlling the final product distribution. In general, the production of butadiene, C ₅ diolefins and C ₆ to C ₇ resin formers drops significantly with a higher degree of conversion. The production of aromatics, including the broad range of C ₅ compounds up to the boiling range of 272.1 °, which are resin formers and are largely of an aromatic nature, increases rapidly, as does the concentration of such aromatics in the gasoline fraction. Ethylene production, although higher in absolute terms, falls in relation to the total yield of dry gas. These data are summarized in Table 4.

Table 4

0.2496 to 0.4992
648.8 to 815.5
<1.406

4992 to 0.6864
732.1 to 926.6
> 1.406

Higher Normal Conversion Unrwand- degree of efficiency degree of efficiency Example C Example D Temperature, ⁰ C 737.7 676.6 KW partial pressure, kg / cm ² abs. 0.7 0.56 Conversion to dry gas, m ³ / kg of coke-free return stand input material 0.755 0.318 Yield, weight percent, based on the entire return stand material Butadiene 1.6 23 C ₅ diolefins 1 8 2.9 C ₆ to C ₇ resin formers .... 0.5 O Q C ₆ to C ₈ aromatics 9.5 3.7 C ₅ haf z former up to 254.4 ° C 5.6 4.7 coke 24 17th Concentration of aroma th in C ₆ -221 ° C range 95 28 Concentration of ethylene in C ₂ and lighter Pro ducts, mole percent 26th 36

The method of applying the principles of the invention is described in more detail below will.

In Fig. 3, a sump or collector 11 for fluidized and preheated solid particles is one heat-transporting material shown. These particles are proportionate and preferably im essentially complete, non-catalytic in nature. Collection container 11 is with the bottom of a transport tube 13 connected, in which a whirling and / or stripping gas can be introduced through inlet 15 can. The hot suspended solid particles flow down the transport line by gravity. A suitable valve, not shown, can be provided for regulating and / or switching off the Electricity if necessary.

The transport line 13 includes a U-bent pipe 17 into which further whirling and / or Lifting gas can be admitted at inlets 19 and 21. There are as many inlets used as necessary, as is self-evident for the expert. There are adjustable control organs at these points necessary, as indicated, to control the steam supply and thereby the carbon partial pressure in to control the reaction vessel.

The ascending pipe part of the flow tube, in particular the upper part thereof, serves as a reaction vessel for the process (item 25). The one to be transformed Feedstock, in the particular case a heavy residual petroleum oil, is replaced by a suitable one Nozzle system 27 sprayed into the ascending stream of hot solid particles. The input material is preferably preheated and is usually essentially liquid, but can also be solid particles made of pitch, bitumen, bituminous coal, etc. The whirled up or suspended heat-carrying particles come into contact with the feedstock, which is in finely divided form is present and cause its thermal transformation. The temperature of these particles is sufficient high in order to maintain the required reaction temperature.

This temperature can range from 621 to 871.1 ° C and be even higher. For optimal production of butadiene, C ₅ diolefins and the C ₆ to C ₇ resin formers, a temperature below 732.2 ° C is desirable and should preferably be between 648 and 704.4 ° C. In cases in which the C ₆ to C ₈ aromatics and related products are more in demand, higher temperatures, namely at least above 704.4 ° C and preferably above 732.2 ° C, are necessary.

In either case, the fluidizing gas can be steam or a light hydrocarbon gas. When the hydrocarbon partial pressure should be kept low,

9 10

as this is especially for the production of butadiene warm or combustion area as a flow tube

and related materials, steam or trained burner 45 must have a

other non-hydrocarbon gas has air inlet port 47. If necessary, further,

be used in suitable proportions. Air inlet openings, not shown, are provided The system, as shown in FIG. 3, can be without 5.

further at atmospheric pressure or near this. In the preheater or burner 45, the

Pressure to work. However, even with increased solid particles, it can usually affect the

Pressures up to 3.4, 6.8 kg / cm ² or even brought to the required temperature that all-

higher pressures - if necessary - can be worked. borrowed carbon-containing solid particles or else Working with pressure naturally requires pressure.

control valves, etc., which are not shown. have placed the tion vessel on it. However, if

The conversion time required between the feedstock, a combustible fuel, such as. B. gas oil or

and the hot solid particles in reactor 25 is torch oil (low-grade heavy oil) together with air.

Quite short and is preferably 0.05 to 1 semen to be part of the required amount or a similar time. The time naturally depends on the heat required, or on all of the necessary heat

licn from the dimensions of the reaction vessel and the heat.

The speed and the degree of dispersion of the solid The hot solid particles flow off together with material parts from which the vessel flows. the combustion gases upwards into a separator - the degree of conversion - e.g. B. the one for dry gas - device or a cyclone separator 51, from which depends both on the temperature and on the 20 the exhaust gases exit upwards. The severed contact time. The degree of conversion should consist of particulate matter flowing down into a sump, to almost all of the feedstock in container 1 1 _1, from where the operation is continuously repeated for vapors and carbonaceous residues or coke.

to convert. The latter is based on the heat, although the most varied of solids, such as sand, carrying solid particles, which thereby remove some mullite, silicon carbide, metal particles and the like.

be cooled. The one that can be used as a flow tube becomes the one that arises in the process

formed vessel 25 emerging stream of solid oil coke is generally preferred because it is un-

Particles, vapors, etc. flows into a cyclone separator that is available indirectly. In general,

27, in which a jet 28 acts as a quenching medium, contains more oil coke in the process than in combustion. B. a hydrocarbon oil, such as. B. the requirement to generate the required heat.

set material, is sprayed into it, which is wiped out the vapors. Therefore, the excess coke can be used for

cools and further reactions are partially withdrawn by quenching other purposes, e.g. B. by line

wisely prevents. At this point there should be at least 57, with the outflow of material through valve 59

be cooled by 27.8 ° C so that further reactions can be controlled.

become essentially impossible. The solid part 35 The hydrocarbon partial pressure in the reactive

Sections are separated and the solids drainage area can be removed by increasing the use of steam

line 29 of the cyclone separator into a scraper through the lines 19 and 21 are lowered. As

Direction 31 headed. Steam or other inert indicated above should be used for the generation of C ₄ bis

flowing medium, the partial pressure is below 0.84 kg / cm ^a abs in the bottom of the stripping C _{5 diolefins.}

device 31 initiated via line 33 and the ab- 40 and preferably below 0.7 kg / cm ² abs. lie, where

striped gas or vapor products are through a preferred range of from 0.35 to 0.56 kg / cm ²

Line 35 removed and to a not shown rear abs. is. For other products it can be higher and

extraction plant led. z. B. up to 1.4 kg / cm ² abs. and be more.

The partially quenched vapor products flow.

up from the separator 27, namely by 45 chen, their degree of dispersion and the contact time before

the line 37, in which they are controlled by the speed by a suitable cooling-quenching

medium can be deterred even further. This as the one with which the steam is used. The tempe-

Spray jet from line 39 introduced coolant temperature of the solid particles and the speed,

lowers the temperature of the product quickly to a level with which it can be passed through the at 47

Value that is sufficient to control a further self-decomposition 50 air volume admitted,

to prevent the products. The coolant can be The solid particles used, preferably

Water, or coke made from inert hydrocarbons, should be large enough to stir them up.

stand. It can also be a stream of proportionally that can; however, their size can range between one

be cool solid particles, what the skilled person is very small average diameter of z. B.

is known. The quenching at 28 can already 55 10 μ and a larger diameter of z. B.

sometimes be sufficient, since the cooling of solid-800 μ and more fluctuates. A preferred area

Particles of matter are also required (the one afterwards is 20 to 400 μ.

must be re-heated, which will be explained), In summary, there is the new method which is preferred to moderate quenching, e.g. invention in a conversion of heavy coals at 28 is cooled by 27.7 to 55.56 ° C and then 60 hydrogen or hydrocarbons Materiabei 39 is further cooled, at least around lien in low-boiling substances, the yield of 55.56 ° C and usually more. The quenched products is selectively controlled. This is achieved in that the products are then fed into a fractionation device that a) directs the degree of conversion through over or another recovery plant, not shown, with the aim of monitoring the dry gas production. 65 these between 0.2492 and 0.4984 m ³ / kg application

After stripping, the used solid material will be kept, controlled while b) the

Particles of matter in the scraper 31 through line 41 via hydrocarbon partial pressure within the reac-

a U-bend in a preheating or burning area is controlled tion area. The necessary control

directed. Steam or other lifting or ventilation measures are ensured by the determination of the

Processing gas is introduced through line 43. Check the feedstock's pre-70 carbon residue number

"" ■ - 909 758/532

Conradson and the carbon and hydrogen percentages contained therein and the subsequent application of the formula given above. A shift in the optimal production of C _{4 to} Cg diolefins plus C ₆ to C ₇ resin formers (for the production of lightly colored resins) to mainly aromatic substances (plus ethylene and some acetylene hydrocarbons and including the resin formers for the production of dark colored resins) only requires a shift in working conditions with the aim of increasing dry gas production into the alternative, optimal range. Further control of the process is achieved by controlling the hydrocarbon partial pressure.

Claims (7)

Patent claims: 1. A process for converting heavy oils into low-boiling, normally vaporous or liquid, unsaturated hydrocarbons and solid carbonaceous residues, a stream of this material in finely divided form with a fluidized mass of essentially non-catalytically active heat-carrying solid particles at a reaction temperature of at least 621 ° C is brought into contact, characterized in that the duration of contact between the feedstock and the heat transfer medium is such that the feedstock is converted into at least 0.2492 and not more than about 0.623 m ³ dry gas (C ₃ -) per kilogram of coke-free feedstock , and that at the same time such an amount of a non-hydrocarbon gas is introduced into the reaction region as is sufficient to keep the hydrocarbon partial pressure below about 1.40620 kg / cm ² abs. so that, irrespective of the nature of the feedstock, essentially optimal economic yields of C ₄ to C ₅ diolefins, C ₆ to C ₇ resin formers and lower aromatic compounds are obtained. 2. The method according to claim 1, characterized in that the dry gas conversion has a further restriction to the range between 0.2492 and 0.4984 m ^s per kilogram of coke-free feed and the hydrocarbon partial pressure to values below 0.84372 kg / cm ² abs. in order to obtain a particularly high yield of C ₄ to C ₅ diolefins plus light C ₆ to C ₇ resin formers. " 3. The method according to claim 1 and 2, characterized in that the solid particles from one carbonaceous residue consist; that arises in the process. 4. The method according to claim 1 to 3, characterized in that the conversion at a Contact time of 0.05 to 1 second is carried out. 5. The method according to claim 1, characterized in that the dry gas production between about 0.3738 and 0.623 m ³ / kg of coke-free feedstock is kept to an optimal production of lower aromatics and C ₅ resin formers with a boiling range up to 272.1 ° C to get. 6. The method according to claim 1 to 5, characterized in that the hydrocarbon partial pressure in the reaction vessel by using water vapor as a diluent and carrier gas for the solid particles below 0.8437 kg / cm ² abs. is held. 7. The method according to claim 1 to 6, characterized in that that a residual hydrocarbon oil is used as the starting material. 1 sheet of drawings © 909 758/532 2.60