DE1054625B - Process and apparatus for converting heavy hydrocarbon oils - Google Patents

Description

The present invention relates to a fluidized bed reactor combined with a thermal cracking plant and, in particular, to a unitary plant for converting heavy hydrocarbon oils which is constructed in such a way that high quality products are obtained with the least possible separation of coke and other disruptive masses, and the corresponding process to operate this system.

Methods and devices for carrying out reactions have already been developed, e.g. B. for the conversion of hydrocarbons into lighter products by bringing the feed into contact with movable or fluidized beds, solid particles heated to sufficiently high temperatures. A special example of one Systems is a fluidized bed coking plant for the conversion of heavy hydrocarbon oil residues.

Several difficulties arise in fluidized bed coking plants, and various solutions have been proposed to resolve them, but these have not always been entirely sufficient. So is z. B. oil produced from heavy oil residues in a fluidized bed coker is not always suitable as a starting material for catalytic cracking. Gas oil often contains heavy end fractions and large amounts of impurities which e.g. B. complicate the subsequent cracking with sensitive catalysts. There is also at the outlet stations of such coking a strong tendency to the formation of waste distinctions of carbonaceous residues on the walls and in the lead-out lines. These deposits are extremely cumbersome and often require the device to be shut down to clean the clogged lines and remove the deposits, which is very detrimental to the operation and throughput of the plant. Various attempts have been made to overcome these difficulties with varying degrees of success.

According to the invention, a system operating with fluidized solids, e.g. B. a fluidized bed coker, connected to a thermal cracking plant to form one unit. This is about the conversion heavy hydrocarbon oils, which tend to form troublesome hydrocarbon deposits, in The method used in lighter products is to put the oils in a moving one disperse layer of hot, finely powdered solids for at least partial conversion of the oils into Introduces gas oil vapors, the gas oil vapors thus obtained through a disperse phase above this solid layer withdraws and leads through an outlet into a recovery zone, where gas oil is separated.

Method and device
for conversion
heavy hydrocarbon oils

Applicant:

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

Representative:

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

Claimed priority:
V. St. v. America April 25, 1956

The special feature here is that at least part of this gas oil is removed from the extraction zone through a thermal one located outside Crack zone conducts, and that at least some of these other products are dispersed back into the disperse Phase leads. The layer of the fluidized bed reactor kept in motion can in each case from hot, finely powdered and catalytically inert coke particles or from fine powdery particles a cracking catalyst.

The feed for the thermal cracking plant can in addition to that generated in the fluidized bed coker Gas oil or a part thereof, or optionally in addition to unconverted fractions thereof contain additives of other oils. If z. B. the heavy hydrocarbon oil to be treated is heavy residual oil, it can be catalytically inert in contact with the fluidized bed Coking parts coke in a coking zone, the received and in the outside lying thermal Crack zone piped gas oil still with externally fed, lower boiling oil than the original one Mix residual oil and the remaining products of thermal cracking, which are in the disperse phase the coking zone, together with vapors from the coking zone of a fractionation zone respectively.

The gas oil is used with or without such additives in the thermal cracking plant at correspondingly high levels

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Temperatures decomposed to achieve sufficient thermal cracking, but not at temperatures at which large amounts of coke or other solid residues are produced. The products obtained in the thermal cracking plant are then introduced into the zone above the fluidized bed in the reactor, ie into the open or disperse phase of the reactor. If necessary, water vapor can also be introduced there together with the thermally cracked vapors. This system supplies the dispersed phase of the reactor with substantial amounts of heat, and the vapor pressure of the products normally emerging from the fluidized bed, and thus the risk of product condensation on the boiler walls and the inner surfaces of the plant, is significantly reduced. It follows that the products leaving the fluidized bed, e.g. B. the conversion products of coking, pull off considerably warmer upwards. However, further spontaneous reactions, which can lead to the formation of disadvantageous carbon-containing deposits, are largely avoided. By avoiding liquid condensation on the surfaces of vessels, the main cause is eliminated _a5 distinctions for the formation of troublesome waste, and the apparatus, including cyclones and outlet, remains substantially free of carbonaceous deposits. By introducing additional heat to the vapors flowing out, their fractionation is facilitated and a better separation of raw gasoline, gas oil and heavy residues etc. is possible. The products obtained are therefore of better quality. The amounts of disadvantageous residues and deposits are in the lighter products, ie in the raw gasoline and gas oils obtained during coking up to an end boiling point of about 540 to 600 ° C, corresponding to a distillate amount of 80% in the range of 455 to 510 ° C for over 205 ° C boiling gas oils reduced to a minimum. The unwanted heavy fractions can be enriched in this way in a bottom fraction, which is either withdrawn as such or fed back to the fluidized bed coker for further decomposition.

Processes for converting hydrocarbon oils have already become known at which cracking and coking stages are combined with one another. These well-known procedures however, differ from the present in several ways.

One of these known methods relates to fluidized bed coking, but not this one Coking is provided together with a thermal cracking zone for cracking the gas oil; and Likewise, in this process there is no return of the vapors from the thermal cracking to the dispersed one Phase of the fluidized bed coker, which is characteristic of the present process.

Another method concerns the fractionation of an oil to produce a gas oil and a Residue fraction, the catalytic cracking of the gas oil and the fluidized bed coking of the residues as well as the union of the resulting vaporous products from cracking and Coking with subsequent fractionation of the mixtures to produce a motor fuel, a new gas oil fraction and a new residue fraction, the latter being returned to the coking zone can return.

Nothing is said in this process about thermal cracking for the treatment of gas oil, that comes from coking or through the treatment of products from a catalytic Cracking zone; moreover, in this known procedure, the whole sequence of the stages of work is present completely different than that in the present case.

Finally, there is also a method of coking a residual oil in the presence of inert particles been proposed, with the steam products in a Wasclizone and the product vapors in a catalytic conversion zone. Even if this is due to the coking of the vortices cracking follows, the latter is catalytic cracking and not around a thermal, as in the present invention, and in addition there is no provision that To return gas oil vapors from the thermal cracking zone to a specific point in the first reaction zone. However, it is precisely these measures that are crucial for the success of the present invention Meaning.

The union of the thermal cracking plant with a fluidized bed coker, from which z. ^{B. the 1} gas oil vapors obtained during the coking flow into the cracking plant is only one possible application of the invention. Another embodiment of the invention is the combination of a thermal cracking plant, as will be described in more detail below, with a conventional catalytic fluidized bed cracking plant. With this combination of systems and processes, the products of the thermal cracking system are fed into the dilute phase of the catalytic cracking reactor. This not only reduces the tendency for coke deposits to occur in the device, but also a favorable thermal post-cracking of the vapors emerging from the catalytic cracking zone is achieved.

The vapors fed to the thermal cracking plant can in this case, in addition to the above-mentioned, from the coking gas oil vapors z. B. another circulating gas from the catalytic Contain cracking plant or a catalytically obtained raw gasoline or even one supplied from the outside Feed, e.g. B. light or heavy untreated petroleum. With such a system you have a large margin between catalytic and thermal cracking. The ratio of the different Starting materials can vary depending on the particular requirements of refining and each other the respective starting oils fluctuate very strongly.

In thermal cracking, the gas oil and / or the other products to be thermally cracked are passed through through heated lines or coiled pipes, the outlet temperature of which is 510 to 650 ° C and more. Higher temperatures lead to increased formation of unsaturated products and also result more coke. The maximum permissible temperature therefore depends on the desired type and the yields of the various products. In general, one works at temperatures below 650 ° C, if not the Production of large quantities of unsaturated products, gas and coke is desirable. The one at this thermal Pressure applied to cracking can vary widely, e.g. B. between 1.4 and 21 atm. The thermal The cracking system can contain conventional pipe coils, pipes, containers and the like. In the present In this case, a simple pipe system is preferable.

You can use an independent oven or heating device or a pipe coil for heating use, which are in the fluidized bed zone of the solid particles of a fluidized bed coking burner or a regenerator for the catalytic system. The cracking systems can also consist of several Units exist, which allows cleaning and decoking of one system while the other is in Operation is.

The main advantage is the reduction of the ι tendency to coke formation, ie to the formation of coke deposits in the upper fluidized bed part and in the discharge lines of the system, thermally cracked by feeding products, i in economic and process advantages by Vereini-, supply to thermal cracking with other methods , e.g. B. coking and / or catalytic cracking in a fluidized bed; and improving the fractionation of the products obtained from a fluidized bed system by supplying heat in the form of hot vapors from thermally cracked products coming from a separate thermal system.

The drawing shows schematically and in elevation a union of a fluidized solids working plant and a thermal cracking plant.

The main units are a fluidized bed reactor 11, a burner or regenerator 13 and a furnace 15 which contains a thermal cracking plant or a coil system 17 .

A suitable feed, e.g. B. heavy petroleum residues is fed to the system through an inlet point 21 and a storage vessel 23. From there it passes down through line 27 to a pump 25 and further through line 29 into a layer of fluidized solids, e.g. B. finely divided petroleum coke, which has been preheated before entering the reactor 11 accordingly. For coking such a fuel, the temperature of the coke particles in the reactor is preferably kept between 485 and 620 ° C. The feed is suitably distributed in the fluidized bed of the reactor by nozzles which are not shown here but are well known in the art. The ones obtained from the decomposition of the feed; Vapors cross the interface 31 between the fluidized bed and the dispersed zone above it and from there pass into a gas-solid separation device, e.g. B. a cyclone 33, from which the solids trickle back preferably through a dip tube 35 , while the vapors pull through the line 37 up into a washing device 39 , which is suitable with. Impact walls 41 is equipped. The scrubber can, but need not, be attached above the reaction vessel. The washed vapors flow upward past a series of baffles into a fractionation tower 43, which is preferably mounted immediately above the scrubber, but may be in any other suitable location. Here the vapors are fractionated into ι coking raw gasoline and gases, which are withdrawn through line 45 upwards. A liquid fraction, e.g. A gas oil, for example, is carried away through line 47 and heavy residues through line 49 and pump 51. Some of the latter can flow back to the coking layer (through the appropriately valved lines 53, 55 and 57) , while some can be withdrawn as product through line 59. Preferably, at least some of the heavy residues will pass through

the line 61 and the heat exchanger 63 led into the line 65 and back into the scrubber. These oils promote the removal of heavy debris and solids from the scrubber. If necessary, the heat exchanger 63 can also be bypassed by a line 67.

A portion of the heavy cycle stream can be passed through line 69 into feed line 27 and introduced into the coker with fresh feed for further processing.

Hot fluidized solid particles are introduced into the upper part of the fluidized bed in the reactor through a conduit 71 which carries them from a burner or regenerator 13. Spent particulate matter may be passed from the reactor through fluidized solids line 73 to the burner or regenerator. A portion of the recycled particulate matter may be directed from the burner through line 75 to a quench air separator 77 . Here the coke is sprayed with water or with water and steam to cool it down, and the finer particles carried along by the gas stream are fed through line 79 into the burner or regenerator; returned. Water is supplied through line 81 , and the coarser particles separated in the cooling and air separation system can be conducted through line 83 to outlet line 85 . A stream of air promoting the removal of the coke product can be introduced through line 87 .

The device described above is preferably used for the industrial coking of oils.

According to the invention, the gas oil stream withdrawn through line 47 in the vicinity of the bottom of the fractionation zone 43 preferably flows into an intermediate container 91 or another corresponding device. Such a container is not always necessary, but it is generally useful. From here the gas oil passes through line 93 to a pump 95 which, under sufficient pressure, conveys it through line 97 into the thermal cracking system 17 , the pressure of which on the outlet side is 1.4 to 21 atmospheres. Additional feed oil supplied from outside, e.g. Gas oil, circulating oil from a catalytic cracking device, cracked or untreated raw gasoline or mixtures thereof can also be passed through line 99 into the intermediate container. Vapors that arise from the intermediate container can flow back through line 101 into the coker. If necessary, other side streams can also be withdrawn from the fractionation system. Separate devices for such discharges can be provided in connection with the tower at a suitable point; however, a part of the flow from one of these connections to the tower is expediently preferably through line 105 and pump 107 after line 109, heat exchanger III and inlet line 113 to regulate the heat demand and to maintain the reflux to a higher point> in the fractionation tower returned. A portion of this circulated oil can flow through line 115 into the wash zone. A part of the condensed raw gasoline obtained from the coking can also be removed via the pump 139 ; and feed line 151 back into it for additional control of the conditions in the upper part of the tower.

The gas oil fraction passed through line 47 to intermediate container 91 is passed through the thermal cracking plant at such a rate that

Claims (4)

the desired thermal conversion becomes possible. As already stated above, the pipe system 17 for the thermal cracking in the furnace 15 should have a temperature at the outlet of at least 510 ° C., but also up to 650 ° C. and more. However, this temperature and the conditions given by the design and the mode of operation should be such that adverse decomposition in the pipe system 17 is avoided. The thermally cracked gas oil leaves the furnace ίο through line 121 and flows through one or more lines 123 and 125 into the disperse phase located in the upper part of the reactor. The thermally cracked vapors introduced there in this way move up through the cyclone 33 and its outlet 37 into the washing zone 39 and the fractionation zone 43 above it. Because of their overheating and the reduction in their partial pressures, the vaporous products of thermal cracking are not so large More tendency towards coking and other formation of disadvantageous deposits in the dilute phase of the reactor. In addition, the thermally cracked vapors also result in condensates that are better suited as gasoline additives, which results in certain advantages in further processing as well as advantages of an economic nature. These advantages can be increased by introducing oil and / or untreated light crude gasoline, which are circulated during catalytic cracking, through line 99 into the feed or into the intermediate container 91 that supplies the thermal cracking system. In addition, as already mentioned above, the heat supplied to the products rising from the fluidized bed significantly facilitates the fractionation of the products being withdrawn upwards and prevents the accumulation of disruptive impurities as residues in the gas oil stream withdrawn as the end product from lines 47 or 103, e.g. Metal compounds, heavy residues and the like which would contaminate the cracking catalysts with which they subsequently come into contact. The gaseous products withdrawn from the top of the fractionation tower through line 45 are passed through a heat exchanger and / or condenser 131 and from there into a distillate drum 133. The condensed water vapor and other water can be withdrawn from the process through the outlet line 135 from this system, which receives the condensed and cooled products at about 37.degree. C. and under low pressure, preferably up to about 0.35 atm. Liquid hydrocarbons in the form of raw gasoline originating from coking together with thermally cracked raw gasoline are fed through line 137 to pump 139, from which they are carried to a collecting tank or through line 141 to further treatment facilities or through line 151 to regulate the conditions in the upper one Part of the fractionation tower can be diverted. The flow can be divided as required using suitable valves. The gaseous products under normal conditions, e.g. Hydrogen or C3 and lighter hydrocarbons are mixed with some heavier fractions under equilibrium conditions. For further treatment and recovery of desired fractions, the mixture is withdrawn upward through line 143 from the plant, depending on its economic efficiency. Instead of the reactor 11 of a fluidized bed coking plant, a conventional catalytic fluidized bed cracking reactor can be provided for the first stages of the process. The other measures remain pretty much the same as described above. In a conventional type of catalytic cracking unit, the fractionation zone is not provided at the top of the reactor and the products are fractionated. One works towards the desired fractions, z. B. on light and heavy raw gasoline; Catalytically cracked gas oil is separated and drawn off by conventional devices. The cycle oil or a very temperature-resistant part of it can then be passed through the thermal cracking system for further conversion. The cracked products obtained in the thermal cracking system can be passed into the disperse phase of the fluidized bed cracking reactor and removed above through the extraction system in the same way and with the same advantages as described above. For example, in the case of heavy raw gasoline, which comes either from simple distillation or from other sources, the octane number can be improved by thermal treatment before it is fed into the upper zone or the disperse phase in the main reactor. This applies to both the coking reactor and a catalytic cracking reactor. The gas oil obtained during coking can be fed back through the heating coil into the coking plant and then fed with the raw gasoline to a catalytic cracking plant. The intermediate container 91 or a corresponding device can optionally be located within the fractionation tower, the line 151 being used for commissioning. Patent claims: 1. Process for the conversion of heavy hydrocarbon oils that lead to the formation of troublesome Carbonaceous deposits tend, in lighter products, by introducing the oil into one kept in motion disperse layer of hot, finely powdered solids for at least partial Conversion of the oils into gas oil vapors, removal of the gas oil vapors thus obtained through a disperse Phase above this solids layer and through an outlet into a recovery zone where gas oil is deposited, characterized in that at least part of this gas oil from the Recovery zone passes through an external thermal cracking zone and that at least part of the products generated in the cracking zone back into the disperse phase leads. 2. The method according to claim 1, characterized in that for the kept moving Layer of hot solid particles made of catalytically inert coke particles are used. 3. The method according to claim 1, characterized in that for the kept moving Layer of finely powdered solid particles from a Cradi catalyst can be used. 4. The method according to claim 1 and 2, characterized in that the heavy hydrocarbon oil is a heavy residue oil and that it can come into contact with the fluidized bed from catalytically inert coking particles coked in a coking zone that the obtained and Gas oil fed into the external thermal cracking zone still with externally supplied,