FR2530261A1 - PROCESS FOR HYDROCARBON FLUID CATALYST CRACKING - Google Patents

Abstract

HYDROCARBON FLUID CATALYTIC CRACKING PROCESS WHICH CONSISTS OF: A.PREPARING IN 3 A SUSPENSION CONSISTING OF A HYDROCARBON INTENDED TO ACT AS A DISPERSING AGENT, A CRACKING CATALYST AND POSSIBLY A CRACKING ADDITIVE; B. MIX THIS SUSPENSION WITH THE FRESH CHARGE CURRENT INTRODUCED IN REACTOR 1; C. SUBMIT THIS MIXTURE OF SUSPENSION AND FRESH CHARGING CURRENT TO CRACKING. APPLICATION TO THE TREATMENT OF HYDROCARBON LOADS WITH A HIGH METAL CONTENT. CATALYST LOSS CAN BE LOWERED FROM APPROXIMATELY 50 TO 80.

Description

i r

  The present invention relates to a method of

  hydrocarbon catalyst tank for the treatment of hydrocarbon feedstocks contaminated with

large amounts of metal.

  The cracking process in question consists in preparing a suspension consisting of a hydrocarbon, a

  cracking additive and a cracking catalyst, at least

  constantly change this suspension with a cool current

  4 carbons and crack the mixture.

  In the fluid catalyst cracking process

  bituel, hereinafter referred to as FCC, the catalyst is brought into contact with the charge and the mixture flows through

  a rising column (where the reactions of

  quage) to the reactor In the reactor, the catalyst

  is separated, usually by means of cyclones, from the

  reaction, which goes to the distillation stage,

  and the catalyst is extracted and sent to the regenerator.

  The steam extraction treatment removes the weakest adsorbed compounds from the catalyst surface while the regenerator treatment burns the coke also present on the catalyst surface, the active middle parts of which clog up. causing

  thus a decrease in catalytic activity.

  The catalyst particles entrained by the gases

  of combustion are also recovered by means of

  clones arranged in the regenerator After regeneration, the catalyst returns to the process, to meet a

charge current charge.

  The product that has gone on to be distilled is sent to a fractionation column where it is separated

  in gas, naphtha, light gas oil, heavy gas oil, light oil

  Oily suspension and suspension This oily suspension

  also contains catalyst particles

  born by the products of the reaction during the separation

  catalyst at the outlet of the reactor.

  Although the most recent FCC units are

  equipped with series of cyclones with one or more stages ,.

  catalyst losses in these units remain

  rable. The fluid catalyst cracking process of the invention utilizes a catalyst loading process (described later) which allows considerable reduction.

of these losses.

  Due to the oil crisis, efforts have been made all over the world to develop processes for increasing the use of this oil. This has led to the development of cracking processes for the use of oil. the heaviest fractions of the crude as raw material for these processes, while catalysts more active and less susceptible to poisoning than those used in

  the seventies were developed.

  It is well known that the presence of certain

  rates such as Ni and V in the load to crack constitutes

  a serious obstacle when using catalysts with

  because these metals poison them quickly.

  In addition, in the heaviest crude cuts,

  portion of these metals is much higher.

  To overcome this difficulty, research has

  been undertaken with a view to finding a way to reduce the

  fet of these poisons on the catalysts known at the time.

  This has led to substances known today as

  the name of passivators or cracking additives

  The presence of these substances in the reaction medium makes it possible to treat hydrocarbon feeds with a high content of Ni and V. It has been found that compounds containing B, Sn, Te, Sb,

  Mn, Bi, W, Te, In, Ge etc. are endowed with this property.

  There is now a market for products that are

  in this application In the meantime, other techniques

  passivation has been described in publications

  On this subject, new methods tending to

  more efficient crude oil associated with such techniques

  have led to other discoveries in recent years.

  One of the aims of the process of the invention is to provide

  a fluid hydrocarbon catalyst cracking process.

  in which the catalyst losses are consid-

  reduced by approximately 50 to 80%.

  Another object of the invention is to allow catalyst fines (particles from 0 to 40 microns) to play.

  a role in cracking reactions.

  Another object of the invention is to allow the treatment of hydrocarbon feedstocks contaminated by

metals.

  These goals are achieved through the modification

  carried by means of introducing the catalyst into the process.

  Instead of using the usual method of replacing catalyst losses, consisting of using a silo under

  pressure leading to the regenerator, in the present in-

  the catalyst is supplied in the wet state, directly

in the reaction medium.

  By supplying the process with human virgin catalyst

  mide, that is to say in suspension in a hydrocarbon, the fine particles of the catalyst are allowed to play a role.

in the cracking reaction.

  The method of the invention makes it possible to maintain a

  more precise amounts of catalyst and cracking additive (if used)

charging current.

  The catalyst is suspended in a stream of a hydrocarbon, for example a gas oil obtained under a

  high vacuum, a heavy recycling diesel, a diesel oil

  salt LCO or FCC, naphtha, FCC heavy oil etc, this suspension being mixed with the charge or injected

  directly in the riser, after which

  kills cracking When the load is contaminated by metals, a cracking additive is used to inhibit

  Catalyst poisoning These additives are usually

  antimony, and there are several types on the market.

  The invention relates to a process for catalytic cracking

  hydrocarbon test, which basically consists in: a) preparing a suspension consisting of a hydrocarbon and a virgin cracking catalyst and optionally also a cracking additive; b) continuously mixing this suspension with the fresh feed stream of the reactor, and (c) cracking this suspension mixture and this

fresh load.

  A variant of the process would consist in injecting the

  catalyst suspension directly in the column

  aunt then to submit to cracking.

  To determine the amounts of sus Dension to be added periodically to the process, one must take into account

  consideration certain aspects of operation.

  It is well known to control the degree of contami-

  the catalyst metals by measuring the hydro-

  gene and methane produced during the implementation of the process. When the catalyst is poisoned by Ni and V,

  dehydrogen reactions occur simultaneously.

  nation and coke formation, catalyzed by these metals.

  Therefore, a higher proportion of hydrogen

  in the flue gas is an indication of the potential

catalyst.

  Usually, the catalytic action is regulated by making progressive replacements of the spent catalyst

  by regenerated or even virgin catalyst, and

  to maintain the relationship between hydrogen and

  thane present in the flue gas within

  considered acceptable It is advantageous to maintain

  keep these limits as low as possible.

  To compare the performance of the process of the in-

  With those already described in publications, a suspension containing the catalyst was prepared on an experimental scale by the methods described below, and the process of the invention was carried out. comparison, a process was performed

known caking.

  It has been found that when using the process of the invention, whether or not a cracking additive is added to the catalyst slurry, catalyst losses occur.

are significantly lower.

  It has also been found that when using the

  transferred from the invention, all that is required is a quantity of additive

  much lower cracking to reach the same hy-

  in the flue gas, the other

  This means that you have to use about half as much additive

cracking.

  It has further been found that lower hydrogen / methane ratios in the flue gas can be achieved than with the usual type of process, regardless of the amount of cracking additive used in the process. in the usual process, the hydrogen / methane ratio in the flue gas can not be lowered below a certain value,

  whatever the amount of cracking additive used.

  Therefore, the catalytic cracking process

  of the invention has proved to be more effective than those

  described in publications.

  The method of the invention will be described hereinafter with reference to the accompanying drawing, for the sake of clarity, although

  that description should not be regarded as

limiting.

  the unique figure of the drawing is a representation

schematic of the invention.

  The cracking reactor is designated 1 and consists of the riser unit and the product separator; the catalyst regenerator is designated

  by 2 and the tank to prepare the suspension by 3.

  In the mixing tank (3), equipped with a mechanical stirrer (4), a hydrocarbon (5) is introduced.

  the role of dispersing medium for the catalyst, an additive

  cracking agent (6) if necessary, and virgin catalyst (7) in suitable proportions The suspension stream thus ensured for the catalyst (8) is continuously mixed

  with the fresh charge current (9>, which gives rise to

  at a common charging current (10) which is fed into the cracking reactor (1), more precisely in

the riser.

  The reaction product stream (11) is separated and sent to the operating apparatus, not shown in the figure, while the spent catalyst stream (12)

  sent to the regenerator (2) where the regeneration

catalyst ration.

  A stream of oxidant gas (13) is fed into the regenerator (2) to burn the coke which has been deposited on the spent catalyst, giving rise to a current of

  combustion gas (14) which is subsequently removed from the regeneration

  (2) Regenerator, a regenerated catalyst stream

  Nere (15) also returns to the process and unites with the combined feed stream (10) which enters the reactor

cracking (1).

  To implement the process, a gas

  heavy oil as a filler and as a dispersing agent, and air

as an oxidizing gas.

  A variant of the process according to the invention

  is to prepare a suspension of the catalyst in a hy-

  (8), with or without cracking additives, and at least

  inject this suspension continuously into the riser

  te, that is to say without going through the mixing stage of

  this suspension with the fresh charge current (9).

  The usual process that has been used as a

  parison is the following is sent the catalyst stored in a silo to

  the regenerator by putting the silo under pressure and we have-

  The catalyst is continuously fed into the process. The cracking additive is diluted with gas oil in a drum and fed continuously into the feed stream.

  sufficient quantities to achieve the desired results.

  The mixture thus obtained is cracked.

  To confirm the results obtained at the laboratory scale, a prototype unit was built in order to

  The tests were intended to give

  These figures are safer than those determined at the laboratory scale, among other things for catalyst losses, to set ideal operating conditions and to compare

  a method common with that of the invention.

  The following non-limiting examples are given in

  As an illustration of the invention.

  The catalysts that can be used for the

  The catalysts of the invention are the usual catalysts, for example: low-grade alumina, high-grade alumina, zeolites, etc. Throughout the tests, the quality of the charge

remained the same.

Example I

  The purpose of this example is to control the effectiveness

  of the feed system of the invention in relation to this

him of the usual process.

  In tests 1 and 2, the catalyst was replaced

  continuously as the usual process, ie

  say silo to regenerator In tests 3 and 4, we have

  used the process of the invention: a suspension of

  The lysine in diesel was prepared in a tank of

  lange equipped with a mechanical stirrer This suspension was sent continuously in the process at the same time

that charge.

  The feed used for these tests is a heavy gas oil from a Leona crude, while the catalyst is high grade alumina.

  replacement is exactly equal to the amount lost.

TABLE I

  Es, sai Charge (m / iour) Replacement (t / day)

1,153 0.45

2,285 0.66

3,239 0.13

4,255 0,20

  The usual comparison of Trial 3 versus Trial 2 shows a 80.3% decrease in the amount of

Catalyst replaced.

example 2

  These tests are intended to establish the conditions

  optimal operating procedures of the process In these tests, the

  The usual method (test 5) is compared with that of the invention

  (test 6) The reaction temperature, the catalytic ratio

  oil / oil and the combined load ratio are all

  kept as constant as possible A combined load

  born from 1.0 means that no recycling is done.

  Table II gives the average results of the tests.

TABLE II

  Tests 5 6 Charge (m 3 / day) 186 186 Charge temperature (C) 165 169 Catalyst circulation (rpm) 3.0 2.4 Catalyst / oil ratio 22, 8 18.3 Reaction temperature (C ) 492 490 dense stage TABLE II (continued) Tests 5 6 Regenerator temperature (C) diluted stage 612 628 cyclone 620 639 Combined charge ratio 1.0 1.0 Hydrogen / methane ratio in the flue gas 3,17 2, 70 Cracking additive (kg / day) * 24 8 Replacement catalyst (kg / day) 200 100 * antimony type commercial additive replacement exactly equal to lost catalyst The table above shows that in the process of

  the invention, the catalyst losses are half less.

  It should also be noted that even with only one third of the additive, the hydrogen / methane ratio is lower, which means that the cracking additive is used more efficiently.

Example 3

  The purpose of this example is to find

  both the amount of cracking additive used, as in

  the usual process of replacing the catalyst, the

  hydrogen / carbon (H 2 / C 1) is lower than that

  which leads the method of the invention.

  In the process of the invention, there is obtained a report

  H 2 / C 1 port 2.7 and 2.7 kg Sb daily Sb doses are calculated in terms of commercial cracking additive used Table III gives the results obtained.

TABLE III

kg of Sb / day H 2 / C

1.80 3.8

2.76 3.17

3.50 3.3

4.00 3.5

  In the usual process, whatever the quantity

  the additive used, the H 2 / C 1 ratio can not be

  brought to a value below 3 P 17.

Claims (3)

  1 Chromatic Fluid Catalyst Cracking Process   hydrocarbons, characterized in that it comprises the following stages:   a) preparation of a suspension consisting of a hydrocarbon   bure, a virgin cracking catalyst, and optionally a cracking additive; b) continuously mixing this suspension in the charge stream of the fresh reactor; and c) cracking of the mixture of the suspension and the charge fresh.   Process according to Claim 1, characterized   in that the suspension is injected directly and in   tinu in the riser and subjected to cracking.   Process according to claim 1 or 2, characterized   in that catalyst particles of less than 40 microns are made capable of playing a role in the cracking reaction.