RU2206595C1 - Method for delayed coking of petroleum residues - Google Patents

Abstract

FIELD: petroleum processing. SUBSTANCE: method comprises preheating of raw material, mixing it with diluent in a separate mixer, and secondary heating of mixture to coking temperature, said diluent being heavy coking gas oil recirculate or pyrolysis tar, or heavy catalytic cracking gas oil, or their mixtures taken in amounts 4 to 15% of the weight of raw material. EFFECT: reduced power consumption, increased yield of coke, and extended raw material resources. 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, in which the formation of a mixture of tar and recycle, which goes after heating in the furnace for coking, is carried out in a distillation column by contacting the liquid phase of the tar with the vapor phase of the coking products coming from the coking reactor into the column. In this case, the input of primary raw materials into the column is carried out at three points. In the case of processing raw materials of heavy fractional composition in order to minimize the enrichment of raw materials with light recycle fractions, it is introduced into the column through the lower nozzle and vice versa in the case of processing raw materials of lightweight fractional composition, it is introduced into the column through the upper nozzle directly onto the sieve plate. The regulation of the circulation coefficient is carried out by supplying a heavy gas oil in the upper fitting directly to the sieve plate / G.G. Valyavin, B.M.Ezhov, O.M.Salyakhov. Thematic review "Experience in the operation of technological equipment and measures to increase the time between overhauls of delayed coking plants", M., TsNIITEneftekhim, 1979, p.30-33 /.

 The disadvantage of this method is the increase in energy consumption and a decrease in the efficiency of the delayed coking process, because in the process, light fractions used as recirculate and having low cokeability are uselessly circulating.

 The closest to the proposed method in terms of technical nature and the achieved result is a delayed coking method, including heating the feedstock - tar and feeding it to the bottom of the distillation column, where it is mixed with coking products coming from the reactors, secondary heating of the resulting mixture to the coking temperature and feeding her into the reactor / N.T. Porodenko, B.I. Bronds. Thematic review. Operation and ways to improve the reliability of reactors of delayed coking plants M., TsNIITEneftekhim, 1983, p.8 /.

 The disadvantage of this method is the fact that a significant amount of a light product circulates in the process that is practically inert to coking reactions, causing an unjustified increase in the specific energy consumption for pumping, heating and cooling the recirculate. In addition, a fairly low coke yield is achieved in the process.

 The present invention is aimed at reducing energy consumption, increasing the yield of coke, as well as expanding the raw materials used in the coking process. This is achieved by the fact that in the method of delayed coking, including preheating the feedstock - tar, feeding it to a diluent and secondary heating the mixture to a coking temperature, a part of heavy coking gas oil, or pyrolysis resin, or heavy catalytic cracking gas oil is used as a diluent , or mixtures thereof in an amount of 4-15% of the feedstock, and the mixing is carried out in a separate mixing tank.

 The method is as follows.

The feedstock, in particular the tar, is preheated in a furnace to a temperature of 340-380 ^o C and fed into a separate mixing tank, it receives 4-15% of the feedstock recycle heavy coking gas oil, or pyrolysis resin, or catalytic heavy gas oil cracking, or mixtures thereof. From the tank, the resulting mixture is fed into the furnace for heating to a coking temperature of 485-505 ^o C and through a four-way valve it enters from below into one of the coking reactors. To increase the flow rate and reduce the coking of the pipes, a turbulator, water vapor, is fed into the feed stream. The distillate coking products on top of the reactor are taken to a distillation column, where they are separated into gas, gasoline, water condensate, light, heavy and still gas oil and the products are removed from the installation.

 After filling the reactor with coke, the hot stream from the furnace is switched to the next reactor, and the first after steaming and cooling is freed from coke and prepared for the next coking cycle.

The proposed method is illustrated by the following examples, which are given in the table. These tables were obtained experimentally in a pilot installation of delayed coking at a pressure of 0.4 MPa and a temperature of 495 ^o With the exit of the furnace.

In the experiments, products with the following quality indicators were used:
- tar: density 984 kg / m ³ , coking ability 1.3%, sulfur content 1.2%, coke yield 22%;
- recycle: density 965 kg / m ³ , coking ability of 0.5%;
- pyrolysis resin: density 1070 kg / m ³ , coking ability 16%;
- heavy catalytic cracking gas oil: density 1020 kg / m ³ , coking ability 3.5%;
- heavy coking gas oil: density 980 kg / m ³ , coking ability 4%.

 In the table, examples 1-5 characterize the known method; examples 6-11 are proposed, and in examples 6, 7, a pyrolysis resin is used as a diluent; in examples 8, 9 - heavy gas oil catalytic cracking, in examples 10, 11 - heavy gas oil coking, the amount of diluent 4-15% of the feedstock.

 As can be seen from the table, in all examples of the proposed method there is a noticeable increase in the yield of coke, reaching an absolute value of 3.0% (example 7). Moreover, the increase in the yield of coke increases with an increase in the quantity and cokeability of the diluent, while in the known method this tendency is exactly the opposite.

 Thus, the proposed method of delayed coking makes it possible to reduce specific energy consumption, increase the yield of coke, and also expand the raw material base.

Claims (1)

 A method for delayed coking of oil residues, including preheating the feedstock, mixing it with a diluent in a separate mixing tank, secondary heating the mixture to a coking temperature, characterized in that recirculating heavy coking gas oil or pyrolysis resin or heavy catalytic cracking gas oil is used as a diluent , or mixtures thereof in an amount of 4-15% of the feedstock.

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