RU2372373C1 - Method of delayed coking of black oils - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to oil processing and can be sued at delayed coking of unstable black oils. Method includes heating of oil stock and its feeding into coking rector by two flows, with following feeding of steam and gas coking products into rectification tower for separation. In the capacity of the first flow fed into reactor, there are taken tar or mixture of tar with recirculator - heavy gas oil for coking, heated up to temperature of coking 495 -505°C. In the capacity of the second flow it is taken asphalt, heated up to temperature 430 - 460°C.

EFFECT: method provides increasing of period of service of coiled pipes of kiln up to its carburising.

2 cl, 1 tbl

Description

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

A known method of delayed coking of oil residues (S.A. Akhmetov. Technology for the deep processing of oil and gas. Ed. "Gilem, Ufa, 2002, pp. 385-389) by heating the raw materials in heat exchangers, convection coil of the furnace, contact with combined-cycle coking products in a distillation column with the formation of secondary raw materials - a mixture of raw materials with heavy coking gas oil, its subsequent heating in the furnace and feeding into the reactor for coking.

The disadvantage of this method is that when processing heavy oil residues, the coil quickly cokes and additional operational and capital costs are required to restore the operability of the equipment.

The closest to the proposed method according to the essential features is the method of delayed coking of crude oil, when the crude oil is heated in two separate furnaces and fed into the reactor in its lower and upper parts for coking (AS No. 1694621, op. 30.11.91, BI No. 44).

In the known method, when a mixture of tar and oil residue, such as asphalt, is heated to a coking temperature (495-505 ° C), the furnace coil is quickly coked due to aggregative instability of the raw material due to the non-optimal ratio of group chemical components of the raw material, accompanied by the precipitation of the heaviest of them , for example asphaltenes, from the volume of the liquid phase to the surface of the pipe. Cracking products, in addition, have high chemical and adhesive activity, accelerating coke formation reactions, both in the volume of the reaction mass and especially at the interface: liquid - pipe metal. All this leads to an unscheduled shutdown of furnaces for cleaning pipes from coke deposits.

The technical result to which the invention is directed is to increase the duration of the furnace coil before coking during delayed coking of heavy oil residues.

The specified technical result is achieved by the fact that in the method of delayed coking of oil residues, including their heating and feeding into the coking reactor in two streams, each stream being heated in a separate furnace, followed by supplying gas-vapor coking products to the distillation column for separation, according to the invention, as the first stream fed to the reactor takes tar or a mixture of tar and recirculate - heavy coking gas oil, heated to a coking temperature of 495-505 ° C, and as a second o - asphalt heated to a temperature of 430-460 ° C.

It is advisable to feed the asphalt stream to the bottom of the reactor.

Submission to the reactor for coking in a separate stream of oil residues - asphalt, heated to a temperature of 430-460 ° C, avoids decomposition (cracking) of the feedstock and, consequently, coking of the furnace coil. The reactor load is heated to the coking temperature directly in the coking zone - in the reactor by mixing the tar or its mixture heated to coking temperature with recirculate - heavy gas oil with asphalt heated to temperatures below cracking (more than 460 ° C) temperatures.

The method is as follows. The raw materials are preheated in heat exchangers, the convection part of the furnace and mixed with recirculate in a predetermined ratio in a separate container or cubic part of the main distillation column, then the secondary raw materials - the charge is heated in the radiation part of the furnace to the coking temperature (495-505 ° C) and sent to the reactor where it is mixed with the oil residue - asphalt, fed in a separate stream to the bottom of the reactor and heated in a separate furnace to a temperature of 430-460 ° C. To reduce the risk of coking of pipes, a turbulator - water is supplied to the coil of the furnace. In the reactor, the mixture is coked to form a coke cake, which remains in the reactor, and combined-cycle products are sent to the distillation column for separation into components: gas, gasoline, water condensate, light, heavy and still bottoms gas oils. The latter is returned to the feedstock as recycle.

The following are specific examples of the implementation of the proposed method, obtained on a laboratory flow-through installation of delayed coking. The installation includes two raw material tanks, two pumps, two furnaces (P-1 and P-2) with tubular coils equipped with pressure gauges at the inlet and thermocouples and valves at the outlet of the furnaces. There is a tank with the appropriate harness for the starting product (gas oil).

The delayed coking reactor consists of a furnace and a cube equipped with thermocouples for measuring temperature, a monometer, a valve, a condenser-refrigerator, a gas separator, a gas clock. The laboratory facility is equipped with appropriate electrical equipment and instrumentation.

The end of the experiment was determined by increasing the pressure at the inlet to the furnace by 25% of the initial value. At the end of the experiment, we made a material balance, examined the furnace coils, took samples of coking products for analysis. Analyzes of raw materials and coking products were carried out according to well-known methods adopted in oil refining. The research results are shown in the table.

As a raw material, tar was used with a density of 982 kg / m ³ and coking ability of 11%; asphalt - with a density of 1050 kg / m ³ , coking ability - 23%. Recirculate - heavy gas oil - with a density of 850 kg / m ³ , coking ability of 0.3%.

The table shows the performance of the delayed coking unit (according to the known and proposed methods). The table shows that the known method of the furnace P-1 and P-2 operate in parallel on the same raw materials and in the same mode both at a temperature of 495-505 ° C at the outlet of the furnace, and the flow rate (50/50) therefore, the main operational indicator - the length of the overhaul run until coking of the furnace coil in these furnaces is identical. So, when the P-1 furnace is operating on clean tar (examples 1, 3, 4, 5) or with the addition of recirculate - heavy gas oil (example 7), good results are observed for the length of the overhaul run, which is 100-120 minutes, but when adding in the feedstock (tar) even a relatively small amount (20%) of oil residue - asphalt, the main indicator is the length of the overhaul run of the known method is reduced from 120 to 40 minutes, i.e. 3 times, and the proposed method this problem is not observed with any combination of indicators on the composition of the raw materials, technological mode, quality of coke precisely because the proposed method has a significant difference from the known method, namely, that each component of the feedstock is heated at the optimum for this type of raw material, in particular, asphalt is heated to a temperature (430-460 ° C) of the beginning of decomposition of this raw material.

The table shows that the proposed method (examples No. 3, 4, 5, 7) - in all the above modes, with separate heating of the raw material components to produce coke with a quality indicator - the volatiles content satisfying the relevant standard, the overhaul mileage before the coil is coked the furnace is 100, 120 and more than 120 minutes and exceeds the similar indicator of the known method by 1.4-3 times.

Thus, the proposed method allows to increase the duration of the run of the coil of the furnace during the processing of oil residues by half compared with the known method while maintaining the volatile content of coke in the regulatory range.

The performance of the delayed coking unit (by known and proposed methods) Example No. Raw materials - furnace loading composition,% The ratio of flow rates,% Outlet temperature, ° С Coking mileage, min ** Volatile matter in coke, P-1 P-2 P-1 P-2 from P-1 from P-2 P-1 P-2 % one* tar - 100 tar - 100 fifty fifty 495 495 120 120 8-9 2 * tar - 80 tar - 80 fifty fifty 495 495 40 40 8-9 asphalt - 20 asphalt - 20 3 tar - 100 asphalt - 100 80 twenty 495 430 120 > 120 8-9 four tar - 100 asphalt - 100 90 10 500 430 one hundred 120 8-9 5 tar - 100 asphalt - 100 80 twenty 500 460 one hundred one hundred 7-8 6 * tar - 65 tar - 65 recycle - 15 recycle - 15 fifty fifty 505 505 70 70 7-8 asphalt - 20 asphalt - 20 7 tar - 100 asphalt - 100 80 twenty 505 460 > 120 one hundred 7-8 recycle - 15 * - known method ** - laboratory flow furnace; 25% increase in outlet pressure is the end of the experiment.

Claims (2)

1. A method of delayed coking of oil residues, comprising heating the oil feed and supplying it to the coking reactor in two streams, each stream being heated in a separate furnace, followed by supply of combined-gas coking products to a distillation column for separation, characterized in that as the first stream, fed into the reactor, take tar or a mixture of tar and recirculate - heavy coking gas oil, heated to a coking temperature of 495-505 ° C, and as a second - asphalt, heated to a temperature of 430- 460 ° C. 2. The method according to claim 1, characterized in that the asphalt stream is fed down to the coking reactor.