RU2256687C1 - Method of retarding of petroleum residue coking - Google Patents

Abstract

FIELD: petroleum refining industry; petroleum residue coking retarding method.

SUBSTANCE: the invention is pertaining to the field of petroleum refining industry and is aimed at improvement of operation of installation of petroleum residue coking retarding. The method includes a preliminary heating of the original crude, its mixture with a recirculator - a heavy gas-oil of a coking with production of a secondary raw material and heating it up to the temperature of coking in the reactor with formation of a coke and distillate products of coking and preparation of the reactor. In case of failure of one of the reactors the thermal formation of the secondary raw material is cooled and is directed for separation into the rectifying tower, while in the operating reactor they conduct preparation and the following cycle of a coking is exercised in the same reactor. The invention allows by recovery of the process of coking to raise its efficiency.

EFFECT: the invention allows upgrade the coking process efficiency.

2 cl, 1 dwg, 1 tbl

Description

The invention relates to methods for delayed coking of oil residues and can be used in the refining industry.

There is a method of delayed coking according to a one-block coking scheme of raw materials, in which the block consists of three reactors, where the raw materials are preheated, mixed with recirculate and after secondary heating in the furnace coil is sent to coking in one of the reactors. While the reactor is filled with coke, operations are carried out in the neighboring reactor to prepare it for the next coking cycle: the reactor is steamed, cooled, the hatches are opened and the coke is unloaded, then the hatches are closed, the reactor is pressed and heated (Benderov D.I., Pokhodenko N. T, Bronds B.I. "The process of delayed coking in unheated chambers", Moscow, Chemistry, 1976, pp. 32-33).

The disadvantage of this method is a sharp decrease in the efficiency of the delayed coking process when trying to switch to the optimal 48-hour cycle of the reactors, when the duration of the coking stage is 24 hours should be equal to the time for preparation of the reactor is 24 hours. In this case, an even number of reactors is necessary for efficient operation, while the odd ones remain unclaimed.

Known methods of delayed coking according to a one-block scheme (two reactors and one furnace) and two-block (four reactors with two furnaces), where the sequence of operations and the mode are similar to the above method [ibid, p.21 and 35]. These are more promising processes of delayed coking, having an even number of reactors and operating on a continuous circuit. However, in the event of a shutdown of one of the reactors (for example, for repair), the process according to the one-block scheme with two reactors is generally interrupted, and by the two-block it sharply reduces its efficiency.

Closest to the proposed method in terms of technical nature and the number of similar features is a delayed coking method, including preheating the feedstock, mixing it with a diluent in a separate mixing tank, reheating the mixture to a coking temperature and feeding it to the coking reactor. Moreover, this method can be carried out according to a two-, three- or four-reactor scheme using as a diluent a distillate product that provides the required quality of secondary raw materials [RF patent No. 2206595, Republic. June 20, 2003, IPC С 10 В 55/00].

In the known method, as well as in the above, when one of the reactors fails, the delayed coking process either interrupts (according to a one-block scheme with two reactors) or decreases its efficiency (according to schemes with three and four reactors). In this case, the main technological load is borne by the furnace, the reaction coil, which must be provided with a minimum permissible load of 20 t / h throughout the coking cycle, otherwise, the furnace coil is coked, the furnace tubes burn out, which reduces the overhaul distance of the furnace and, consequently, reliability process. Ultimately, all this leads to an increase in capital and operating costs and a decrease in the efficiency of the process.

Thus, the problem arose of increasing the reliability of the process in the event of failure of one of the reactors and the forced transfer of the process to a longer coking cycle.

The technical result is the restoration of the process of delayed coking with a simultaneous increase in the yield of coking products.

The specified technical result is achieved by the fact that in the delayed coking method, which includes preliminary heating of the feedstock, mixing it with recirculate - heavy coking gas oil in a separate mixing tank to obtain secondary feedstock and heating the latter to the coking temperature, coking in the reactor with the formation of coke and distillate products coking followed by their separation in a distillation column into gas, gasoline, light, heavy and bottoms gas oils and preparation of the reactor for the next coc cycle According to the invention, after filling the reactor with coke, the secondary raw materials, after heating in the furnace, are cooled and sent to the distillation column for separation, and the next coking cycle is carried out in the same reactor.

It is advisable to cool the secondary raw materials after heating in an oven with recirculated gas, heavy coking gas oil, to a temperature of 380-420 ° C.

The supply of heat-treated secondary raw materials to the distillation column after filling the reactor with coke allows us to provide the necessary loading of the reaction coil of the furnace, restore the efficiency of the furnace and increase the overhaul distance of the furnace.

In addition, this technique makes it possible to restore the coking work cycle if it is carried out according to a one-block scheme and to increase the yield of coking products - according to a two-block one. In general, this technique ensures the efficiency of the coking process in the event of a shutdown of one of the reactors.

Comparison of the proposed invention with the prototype revealed a new action: when one of the reactors is stopped, the heat-treated secondary raw materials are fed into the distillation column for separation while the working reactor goes through the preparation stage for the next coking cycle in the same reactor, so we can conclude meeting the criterion of "novelty."

Search by distinguishing features did not reveal similar solutions, therefore, the invention meets the criterion of "inventive step".

The drawing shows the proposed method, where the dashed line shows a new action.

The method is as follows.

The feedstock 1, in particular the tar, is preheated in a furnace 2 to a temperature of 335-385 ° C and served in a separate mixing tank 3, it enters the same amount of 10-50% of the feedstock - recycle 4 - gas oil coking fractions.

From the tank, the resulting mixture (secondary raw materials) 5 is fed into the coils of the furnace 2 for heating to a coking temperature of 480-510 ° C and through a switching valve it enters the bottom of the coking reactor 6. To increase the flow rate and reduce the coking of pipes, a turbulator is fed into the furnace feed stream 7 - water condensate. The distillate coking products 8 from the top of the reactor are taken to a distillation column 9, where they are separated into gas 10, gasoline 11, water condensate 12, light 13, heavy 14, bottoms 15 gas oils, after which the obtained products are removed from the installation.

After filling the reactor with coke 16, after ~ 24 hours, the hot stream from the furnace in the absence of a prepared parallel reactor is switched to a distillation column, after which the temperature of the stream at the inlet of the column is lowered using a cold 17 jet (180-200 ° С) to a predetermined temperature (380-420 ° C). Control and measuring devices automatically increase the flow rate for additional heat removal of the 18 columns. An increase in the flow rate of these flows is produced by the value of the coke yield (15-30%) adjusted for the fraction (25-50%) of the switched feed stream 19 in the total feed supply to installation 1.

The coke-filled reactor is prepared for the next coking cycle without changing the usual sequence of operations, i.e. they are steamed, cooled, and after removing the hatches, they are free of coke 16 by hydraulic cutters, then the hatches are closed, pressed, heated with a hot parallel stream from the furnace and the stream from the furnace is switched to the prepared reactor in full after 48 hours from the start of the process. Further, all operations are repeated.

The resulting coking products are used for their usual purpose: gas - as fuel; gasoline, light and heavy gas oils as raw materials for the production of motor fuels; distillation gas oil - as a component of boiler fuel. The bottoms gas oil output is controlled by the column loading temperature and column pressure.

The proposed method is illustrated by the following examples, which are given in the table. The data presented were obtained by calculation and experimentally at a pressure in the reactor of 0.4 MPa and a temperature of 498 ° C at the outlet of the furnace.

In the process of delayed coking, tar was used with the following quality indicators: density 970 kg / m ³ , coking ability 12%, sulfur content 1.3%, coke yield 21%.

As can be seen from the table, in all examples of the proposed method there is a recovery in the process of delayed coking (example 3 in comparison with example 2; example 6 versus example 5) with a doubled raw material productivity, an increase in the yield of coking products: distillates (raw materials for production of motor fuels) - by 40-80% abs., coke by 5-10% abs.

In example 8 (according to the proposed method), a standardized scheme (UZK 21-10 / 300) of the delayed coking process was modernized (example 7), which allows you to switch to a 48-hour coking cycle and double the raw material productivity, increase the coke yield by 50% and distillate 40%.

Thus, the proposed method by restoring the process of delayed coking in the event of failure of one of the reactors makes it possible:

- restore the efficiency of the furnace, increase the turnaround mileage of the furnace and the reliability of the installation itself;

- increase the yield of coking products;

- reduce capital and operating costs and increase the efficiency of the process.

Claims (2)

1. The method of delayed coking of oil residues, including pre-heating the feedstock, mixing it with recirculate - heavy coking gas oil in a separate mixing tank to obtain secondary raw materials and heating the latter to the coking temperature, coking in the reactor with the formation of coke and distillate coking products, followed by separation in a distillation column into gas, gasoline, light, heavy and bottoms gas oils and preparation of the reactor for the next coking cycle, characterized in that after After filling the reactor with coke, the secondary raw materials after heating in the furnace are cooled and sent to the distillation column for separation, and the next coking cycle is carried out in the same reactor. 2. The method according to p. 1, characterized in that the secondary raw material after heating in the furnace is cooled by recirculate - heavy coking gas oil to a temperature of 380-420 ° C.