DE2061191A1 - Continuous process for cracking a hydrocarbon feedstock and equipment for carrying out this process - Google Patents

Description

Continuous process for cracking a hydrocarbon the starting material and the facility to carry out this process

(Addendum to patent (patent application P 19-01 927-3))

Subject of the main patent. ... ... (patent application P 19 01 927-3) is a continuous process for cracking a hydrocarbon feedstock in Presence of divided catalyst particles in which the hydrocarbon stream is in flow contact with the {particles in an Eeactor subject, conversion products are separated from the contacted particles, separated catalyst particles having coke deposited thereon are subject to flow contact with air in a separate regenerator, which air supplied by an air compressor, combustion gas products from the regenerated catalyst particles are separated and the regenerated catalyst parts

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Chen with a reduced coke content for contacting with the hydrocarbon feedstock to the reactor are returned, which is characterized in that the air compressor is operated at maximum power " and the degree of coke deposition in the reactor is controlled by varying the intensity of the reaction in the reactor as a function of fluctuations in the air supply from the compressor.

A preferred embodiment of the method according to

the main patent (patent application P 19 01 92? .3)

is characterized in that the reaction intensity in the reactor is controlled by the temperature and the ratio of catalyst to feedstock in the reactor depending on the temperature at the outlet of the regenerator is varied while the temperature in the regenerator catalyst bed is kept constant.

The present invention aims, the method according to the main patent (patent application P 19 OI 927.3) and the device further extended to implement this * procedure W zugestalten and particularly with respect to regulation of the process conditions and with respect to the provided for controlling the process conditions KESS and control system further to be improved or simplified so that the proposed hydrocarbon feed preheater can be omitted.

This task is made according to the invention by a continuous process Method for cracking a hydrocarbon feed in the presence of divided catalyst particles by contacting the koala feed with the catalyst particles in a Seaktor after the

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Fluidized bed method, separating the. Reaction products and unreacted hydrocarbons, which are recycled into the reactor, from the catalyst particles on which coke is deposited during the reaction, regenerating the separated catalyst particles according to the fluidized bed or fluidized bed method in a separate regenerator by oxidizing the coke deposited thereon with air, which is supplied to the! regenerator from an air compressor, separating the regenerated% tured catalyst particles from the flue gases and recycling the regenerated catalyst having a reduced coke content to the reactor, wherein the air compressor at maximum power operated and the amount of coke deposits "on the catalyst particles in the reactor is controlled by varying the intensity of the reaction in the reactor as a function of the fluctuations in the air supply from the air compressor to the reactor by controlling the temperature and the ratio of catalyst to hydrocarbon feed Reactor varies as a function of the temperature at the outlet of the regenerator, while the temperature at the regenerator catalyst bed remains constant J

is held, according to patent. . ·. . ·. (Patent Application P 19 01 927.3) dissolved ", which is characterized in that, Tempe3? © tur i" Segeneratorkatalysatorbett unreacted by controlling the feed rate of the recirculated into the reactor in the circulation "hydrocarbons Xu depending on the variations of temperature in. Keep the generator catalyst bed as constant as possible *

When erfiadungsgeraäSen method, as already mentioned, the em in Marichtung for performing the method according to & ßauptpatent provided hydrocarbons

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^{Material charge preheater 1 is} omitted, with the help of which in the process according to the main patent the temperature in the generator catalyst bed is kept constant by automatically regulating the setpoint of a temperature setting control reporting unit, which is controlled with PIiIfe, by means of a temperature control unit that responds to the temperature in the generator catalyst bed a control valve regulates the fuel supply to the hydrocarbon feed

ι ^{heater controls} -

In the process of the present invention, on the other hand, the temperature in the generator catalyst bed is thereby increased kept constant that the feed rate, with the unconverted, recirculated into the reactor Hydrocarbons fed into the reactor wex - which, depending on any temperature fluctuations in the generator catalyst bed, is regulated. This is the only one essential difference between the method and the device of the invention and the method, or. the facility according to the main patent (patent application P 19 01 927 3), to which reference is made in its entirety.

A preferred embodiment of the invention is explained below with reference to the single figure of the drawing, which is a schematic flow diagram of a device for carrying out the method of the invention or a catalytic cracking plant.

The main parts of the device or cracking system according to the invention shown in the drawing are a Reactor 14 and an air compressor 1, which is under automatic Control with maximum load bzvi. Top speed is running and all the compressed air it can generate is in one

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Regenerator 2 supplies, in which the pressure with the help of a Pressure Locking Control Unit (TRC) Yes, it's a back pressure valve "actuated, which is arranged in a flue gas outlet line 3, constant, and preferably

in a range of about 1.7 to 5.2 kgf / cm. To the Reactor 14 are through lines 4 and 5, respectively are equipped with a flow regulator 4a or 5a, fresh hydrocarbon feed and recirculated unreacted hydrocarbons (return gas oil) fed, the lines 4 and 5 converge and then into a reactor feed riser 7 Liünden. The temperature of the contained in the regenerator 2 dense phase or in the regenerator catalyst bed 10 with the help of a temperature detection control unit (TRC) 11 kept constant, depending on the temperature prevailing in the respective Hegeneratorkatalysatorbett the flow controller 5a controls the rate of supply of return gas oil to the reactor regulates. *

The Reakfcorbeschickungsschlagungsleitung 7 can, - as in indicated in the drawing, including steam and slurry return are fed at a constant feed rate from a fractionator (not shown). the end the Reger, eratorkatalysatorbett 10 flows through a standpipe H2 and a gate valve 13 regenerated catalyst in ck-n lower part of the charging riser 7 » in which he is intimately with the steam - the fresh hydrocarbon charge, the return gas oil and the slurry return mixed, which, as already mentioned, is also fed into the feed riser 7 will. Due to its higher temperature (around 650 ° C) the regenerated catalyst leads the combined Befichickungoölströmmen Heat and heats it to the

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desired temperature so that they evaporate and be cracked. The resulting hydrocarbon vapors and the water vapor flows up through reactor feed riser 7 to reactor 14, v / over the catalyst carry away. The temperature in the reactor 14 is measured with the aid of a temperature detection control reporting unit (TRCA) 15 regulated, the setting of the slide valve 13 controls in the standpipe 12, the temperature in the reactor 14 preferably being kept in a range from 477 to 516 ° C will.

-The strength of the afterburning occurring in regenerator 2 (Afterburn intensity) is controlled by regulating the outlet temperature of the regenerator 2 leaving Flue gases with the help of a Temperaturfeststell- ^ control unit (TRC) 16 regulated, which the setpoint of the temperature detection control reporting unit (TRCA) 15 readjusts, which in turn directly regulates the reactor temperature.

Exiting from the reactor 14 exhausted catalyst falls through a stripper 17, in which it is in countercurrent with steam fed in countercurrent to the stripper 17 via a line 18 at a controlled rate rinsed, the feed speed of the steam injected through line 18 with the aid of a flow rate detection control unit (FRC) 19 is regulated. As a result of the steam stripping, the used or exhausted catalyst is adsorbed and »trapped oil vapors removed or driven out and returned to reactor 14, from where they finally flow to the fractionator.

The stripped, exhausted catalyst "falls from the lower part of the stripper 17 under the action of gravity.

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kung through, a standpipe 20 for spent catalyst and a gate valve 21 in the regenerator 2. The gate valve 21 is controlled by a level adjusting control unit (LEC) 22 controlled in such a way that the height of the catalyst column in the stripper 17 is kept constant will. The catalyst level can, if desired, extend up to the attenuation point in reactor 2.

Apart from extremely short-term deviations, In the case of a catalytic cracker, the heat supplied must be equal to the heat dissipated or consumed, otherwise the temperature in the system will drop to a harmful height would rise or fall. The combustion taking place in the regenerator 2 in the overall system The amount of heat supplied must therefore be the same as the sum of the heat radiation losses, the sensible amount of heat going out with the flue gas from the regenerator 2 and that from the product vapors in the Reactor 14 absorbed sensible, latent and heat of reaction.

If the temperature in the regenerator catalyst bed should ever begin to drop, it would this indicates that the heat dissipated from the system or used in the system is temporarily lost to the system Exceeds the amount of heat added per unit of time. In this EaIl, the temperature detection control unit 11 reduce the setpoint setting of the flow controller 5a, which in turn determines the return oil feed rate, i.e. reduce the amount of return oil fed to the feed riser 7 per unit of time and thereby the speed of heat dissipation from the Reduce the system and thus re-enter the heat balance

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Bring equilibrium and the temperature in the regenerator or would raise it again to the oil value in the regenerator catalyst bed. It is obvious that the system of rules the device according to the invention in reverse the control processes described above also represent, iuisraaß, up to the Regeneratortc7;]]) temperature or the temperature in Regerieratorkatalysatorbett 10 can rise above the setpoint, limited.

A typical invention genäfie in the situation or a typical one Execution of the method of the invention works under or with approximately the following conditions:

Density of the return oil ^{25 0 APl}

Return oil temperature 282 ° C

Average reactor temperature '4-99 ° C

Regenerator catalyst bed temperature 663 ° C

Regenerator flue gas temperature 691 ° C

Temperature of the regenerator

supplied air 93.3 ° C

Coke composition CnHn CO ₂ ZCO ratio in flue gas. 1.0

Net heat of combustion (HU) 6880 kcalZkg coke

Heat loss to the flue gas 1? 4-5 kcalZkg coca

Heat input to the process 5135kcalZkg coke

Air requirement 8.75 Nm-VkG coke

Heat input to the process 58 '/ kcalZNm ^ air

Heat supply to the return oil 154 000 kcalZi.r ''

It can be seen from the above values that the return oil feed rate changes by 155.0 mV'iog must be made to allow for a change in the air supply speed.

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ability of 28.3 m ^ / min to compensate.

The temperature setting control unit 16 must be set to a somewhat higher setpoint value than the temperature setting control unit 11 in order to ensure a regulated afterburning. The difference zwisehen these two temperature setpoints should be at least approximately be 2.78 ⁰ C, to ensure an acceptable Eegelbarkeit, but on the other hand not be so high that air wasted M that can be better utilized for the combustion of additional coke in increased conversion (in reactor 14) or higher conversion is obtained.

In some cases it can be expedient and desirable to work with a flue gas outlet temperature which is 27.8 C or more above the temperature in the regenerator catalyst bed in order to maintain a high average oxygen concentration in the gases rising through the regenerator catalyst bed, whereby the on the regenerated The remaining coke content of the catalyst is further reduced than would otherwise be possible. Because * this control and regulation system works properly, the setpoint temperature in the regenerator catalyst bed must of course be above the ignition temperature of carbon monoxide. This temperature is preferably between about 650 and 663 ^C C.

If the temperature of the fumes exiting the regenerator head is at any time during the process Should slide below the nominal value, this would be an indication that the strength of the afterburning as a result of a fall in the; Oxygen f'n-ohalt «in the out

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belly gases rising from the regenerator catalyst bed subsides. This in turn would be an indication that the average coke concentration on the catalyst increases in the regenerator, i.e. that coke is deposited on the catalyst (in reactor 14) faster than (in the regenerator 2) is burned. In response to this change in the operating conditions, the (flue gas) Temperaturfest'stell control unit would 16 immediately the setpoint adjustment of the temperature detection control reporting unit 15 des Reduce reactor 14, which then changes the setting of slide valve 13 i & standpipe 12, i.e. would be more closed. As a result of the reduced reaction temperature in combination with the in this way The set ratio of catalyst to oil would then reduce the rate of coke deposition Conversion speed or the degree of immersion so for a long time until it is again in the correct proportion to the amount of air supplied to the regenerator per unit of time (Line 1a). It is easy to see that when the flue gas outlet temperature increases threatens, this is a sign that coke is deposited less quickly than burned off, and that in this case the The automatic control process described above runs in exactly the opposite direction to the degree of conversion for as long increase until the coke deposition and combustion rates are again equal. A change in the Reactor temperature around et v / a 0.28 to 0.56 ° G equals one Changing the air supply speed or the tendency to coke the coal hydrogen charge is about 1% off.

In practical operation, the control system can be further simplified by using the Temperaturfer.trLeIl control unit 16 by a potentiometer or another

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Replaces the temperature sensor and sets the temperature detection alarm unit 15 by hand. The (reactor) temperature control unit 15 includes signaling devices for high and low temperatures, which give signals when the temperature reaches one of the two specified limit values Steps to bring the Realctorteraperatur back into the prescribed range. If, for example, the warning signal sounds for the exceeding of the maximum temperature, then measures have been taken to tighten other controllable variable reaction conditions than the temperature. For example, the catalyst level in the reactor, the Catalyst activity or sludge recycle feed rate increased or the rate at which diluent water vapor is fed into feed riser 7 or the temperature in the regenerator catalyst bed decreased * If, on the other hand, the warning signal should sound that the predetermined lower target temperature limit value was not reached, then measures counteracting the measures outlined above were taken. Optionally, the reactor temperature control can be equipped with one or more level adjustment mechanisms, by means of which one or more of the interventions or changes listed above are carried out automatically.

The control system can be designed to be more complicated than specified in the previous paragraph, but it can is the simple design described and shown in the drawing, in which the operating personnel it is left to take appropriate steps to keep the reactor temperature within the specified

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rich "when it exceeds or falls below a warning signal is given, to keep, preferred, ^ i e application this rule scheme improves the with any Raw materials or hydrocarbon feeds, which are otherwise suitable for catalytic cracking processes, the results to be achieved and, in particular, wiikfc for any starting material with a quality that fluctuates during operation.

Suitable catalysts for the process of the invention are all conventional, well-known to those skilled in the art Cracking catalysts for fluidized bed catalytic cracking processes.

- patent claims -

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Claims (4)

- 13 - Patent claims '(\ / Continuous process for cracking a carbon-hydrogen feed in the presence of divided catalyst particles by contacting the hydrocarbon feed with the catalyst particles in a reactor by the "let bed method", separating the reaction products and unreacted hydrocarbons from the catalyst particles on which " coke separates during the reaction, regeneration of the separated catalyst particles according to the fluidized bed or fluidized bed method in a separate regenerator by 'oxidizing the coke deposited thereon with air supplied to the regenerator from an air compressor, separating the regenerated catalyst particles from the flue gases and recycling the regenerated catalyst particles with reduced coke content to the reactor, the air compressor operated at maximum power and the extent of the coke deposition on the catalyst particles in the reactor by reducing the intensity of the reac tion in the reactor as a function of | the fluctuations in the air supply from the air compressor to the regenerator is controlled by varying the temperature and the ratio of catalyst to hydrocarbon feed in the reactor as a function of the temperature at the outlet of the regenerator while the temperature in the. Regeneratorkatal7 / satorbett is kept constant, according to patent. ... ... (patent application P 19 01 927.3), characterized in that the temperature in the Rep; eneratorkatn3ysatorbett by regulating the feed rate; from in the cycle to the 109830/1708 BAD ORIGINfcgm ^ üf -.% Reactor recirculated, unreacted hydrocarbons depending on the fluctuations in the temperature of the egg in the regenerator catalyst bed, if possible is kept constant. 2. The method according to claim 1, characterized in that that the temperature Uxid the ratio be changed from catalyst to hydrocarbon feed in the reactor by turning off the feed of hot regenerated catalyst from the regenerator to the reactor changes. 3. Device for catalytic cracking, in particular according to claim 1 or 2, with \ a) a reactor with a first line arranged at its upper part, a stripper connected to the the lower part of the reactor is connected and a temperature detection control reporting unit is equipped, b) a regenerator, at the upper end of which a flue gas outlet line with a back pressure valve and at its lower part a standpipe, which is equipped with a slide valve and extends into the lower part Part of the regenerator extends into it and an air supply line, which in turn with an air compressor connected, connected isb, c) wherein the temperature fixed part control reporting unit the position of the slide valve in the standpipe of the regenerator controls depending on the temperature fluctuations in the reactor, 109830/1708 BAD ORIGWAD ^ d) a feed supply line, which the lower Part of the reactor connects to the lower end of the standpipe and connects via this connection point .extends out and with a supply line for fresh hydrocarbon feed as well as one another feed line is connected for the feed recirculated to the reactor, e) in the supply lines for fresh hydrocarbon ^ material loading or; iia recirculated Flow regulators arranged in hydrocarbons, f) another temperature control unit, the temperature associated with the reactor locking control signaling unit cooperates as essential components, characterized in that g) another on the lower part of the regenerator (2) Connected temperature locking control unit (11) is provided with the flow | regulator (5 &) in for the supply of in the reactor (14-) recirculated, unreacted hydrocarbons provided line (5) functionally connected is. 4. Apparatus according to claim 3? characterized in that the temperature detection control unit (11) a guardian organ for inducing attitudes of the flow regulator (5a) depending on the temperature adjustment in the lower part of the regenerator (2) bsw. Has Regeneratorkatalysatorbotts (10). 109830/17 09
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