RU2488626C1 - Thermal conversion reactor - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to a thermal conversion reactor of heavy hydrocarbon raw material, which consists of a shell, upper and lower bottoms having separation space, a heat-treated raw material inlet branch pipe tangentially located on the shell below the separation space, and steam and liquid product outlet branch pipes located on upper and lower bottoms; at that, the shell, upper and lower bottoms are formed with surfaces of rotation about vertical axis; lower bottom is made in the form of a convex-concave rotation surface with a convex part adjacent to the reactor shell, and liquid product outlet branch pipe is located tangentially on the outside of convex surface of lower bottom.

EFFECT: decrease of intensity of coke deposition in the reactor and improvement of the product quality.

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Description

The invention relates to reaction apparatus for liquid-phase thermal conversion (thermal cracking, visbreaking, pitching, thermopolycondensation) of heavy hydrocarbons, prone to the formation of coke deposits on the surface of the equipment, and can find application in the oil refining industry.

A number of known designs of reactors for liquid phase thermal cracking [US Pat. RF №2137804, C10G 9/14, publ. September 20, 1999, Pat. RF №2370521, C10G 9/14, publ. 10/20/2009, Pat. RF №2372378, C10G 9/14, publ. November 10, 2009, Pat. RF №2443752, C10G 9/14, publ. 02/27/2012], including a casing with lower and upper caps and pipes for supplying raw materials and removal of thermal cracking products, an inner pipe located motionless coaxially with the casing and installed in the casing with the possibility of extraction from the reactor, in the lower part of which there is a distributor, and also an external or internal device for circulating the reaction mass.

However, the known reactors have stagnant zones at the junctions of the internal and external elements to the shell, as well as at the points of expansion and contraction of the flow of the reaction mass, which leads to coking of these sections of the reactor and the need for periodic shutdown and cleaning of the reactor. The withdrawal of vapor-liquid products of liquid-phase thermal cracking for further processing in a two-phase state through one pipe leads to unstable operation of a pressure reducing valve located on the product withdrawal line from the reactor, which creates a pulsating, unstable mode of processes occurring both in the reactor and in fractionation equipment, accompanied by emissions of the reaction mass from the reactor and deterioration in the quality of both distillate products by color and residual products of the process are contained ju mechanical impurities (coke particles). In addition, the proposed reactors are bulky and difficult to manufacture and maintain.

Known reactor for liquid-phase thermal cracking, which organized cross-counterflow movement of the reaction mass through the use of internal devices [US Pat. RF №2345121, C10G 9/14, publ. January 27, 2009], which improves the efficiency of the thermal cracking process by reducing the degree of coking of the reactor. During the thermal cracking process, the raw materials, after heating together with steam or thermal cracking gases, are tangentially fed through the horizontally arranged nozzles into the inner glasses, in which rotational spiral flows are formed. Under the action of centrifugal force, an organized spiral flow is discharged from the reactor, and the resulting thermal cracking products are discharged through nozzles located in the upper part and in the lower part of the reactor.

However, the known reactor has a large number of internal elements, is cumbersome, difficult to manufacture and maintain, in addition, the design of the reactor does not provide for devices that impede the entrainment of gaseous liquid droplets formed due to high turbulence and disorganized movement of the reaction medium in the reactor.

Closest to the claimed invention according to the technical nature of the thermal cracking reactor described in the method of processing oil residues [US Pat. RF №2408653, C10G 9/00, publ. January 10, 2011], which consists of a shell, upper and lower bottoms and has a separation space, a vapor outlet pipe located on the upper bottom, a liquid product outlet pipe located axially on the lower bottom of the reactor, and a pipe for supplying heat-treated raw materials tangentially located on the shell below the separation space, i.e. above the level of the liquid phase in the reactor, comprising 50-75% of the height of the reactor. With the tangential introduction of a two-phase flow of raw materials into the reactor due to centrifugal and gravitational forces in the free separating space of the reactor, an accelerated and clear separation of the reaction mass into vapor and liquid phases occurs.

The disadvantage of the reactor is the presence of a stagnant zone at the junction of the outlet pipe of the liquid phase to the reactor due to a change in the direction of movement of the liquid phase when the liquid product is removed from the reactor from horizontal rotational motion to vertical translational, which leads to coking of the lower zone of the reactor, which reduces the quality of the product due to the high content of mechanical impurities (coke particles). In addition, the rotational movement of the liquid reaction mass in the reactor with the axial location of the outlet pipe leads to the formation of a funnel and a high probability of a breakthrough of the gas phase in the outlet pipe of the liquid phase at a high angular velocity of rotation of the liquid reaction mass.

The objective of the invention is to reduce the intensity of coke deposition in the reactor and to improve the quality of the product due to the creation of hydrodynamic conditions in the reactor favorable for the occurrence of thermal conversion.

The technical result that can be obtained by implementing the method:

- reduction in the intensity of coke deposition in the reactor due to the elimination of stagnant zones,

- improving the quality of the liquid product by reducing the concentration of solids in the liquid product as a result of a decrease in the intensity of coke formation.

The specified technical result is achieved by the fact that in the thermal conversion reactor of a heavy hydrocarbon feedstock, consisting of a shell, an upper and lower bottom having a separation space, a nozzle for introducing heat-treated raw materials, tangentially located on the shell below the separation space, and nozzles for withdrawing vapors and liquid product located on the upper and lower bottoms, respectively, a feature is that the shell, upper and lower bottoms are formed by the surfaces of rotation around the vertics the axis of the axis, wherein the lower bottom is made in the form of a convex-concave surface of revolution, with a convex portion adjacent to the shell of the reactor, and the outlet pipe of the liquid product is located tangentially on the outside of the convex surface of the lower bottom.

The proposed reactor is simple to manufacture, does not contain internal devices, has a reduced metal consumption.

The execution of the shell, upper and lower bottoms in the form of a surface of revolution around the vertical axis of the reactor allows for a smooth change in the direction of flow of the reaction mass at the inlet and outlet of the reactor, and also provides rotational movement with a constant angular velocity, which reduces coke deposits in the reactor by creating favorable hydrodynamic conditions. In this case, a calm phase interface is formed, which is a surface of revolution, which prevents the formation of droplets of the liquid product and reduces their entrainment from the reactor with vapors due to better separation of vapors and liquids in the field of centrifugal forces and, accordingly, reduces the color (improves the quality) of distillate products emitted of vapors, in addition, this ensures high mechanical strength of the reactor.

The implementation of the lower bottom in the form of a convex-concave surface of revolution with a convex part adjacent to the shell of the reactor, and the location of the outlet pipe of the liquid product tangentially from the outside of the convex surface of the bottom bottom allows you to eliminate the stagnant zone at the junction of the outlet pipe of the liquid product to the reactor and reduce coke deposits in the reactor.

The drawing illustrates the invention.

The reactor 1 consists of a shell 2, an upper 3 and a lower 4 bottom and is equipped with a raw material input pipe 5, a vapor outlet pipe 6 and a liquid product outlet pipe 7.

When carrying out thermal conversion, the heated heavy hydrocarbon feedstock (I) is fed into the reactor 1 through the feed inlet pipe 5. From the pipe 6 located on the upper bottom 3 of the reactor, thermal conversion pairs (II) are withdrawn, and from the pipe 7 located on the lower bottom 4 reactor, liquid product (III) is removed.

The following are examples illustrating the operability of the proposed reactor.

Example 1. The vacuum residue of West Siberian oil is heated to 485 ° C and subjected to visbreaking at 460 ° C and a pressure of 1.0 MPa for 8 min in a reactor with a convex-concave bottom. The residue (+ 180 ° C) obtained as a liquid product with a yield of 86.5 wt.%, Has a conditional viscosity at 80 ° C of 13.0 and 0.29 wt.%, Mechanical impurities, which meets the requirements of GOST 10585-90 to fuel oil M 100. In this case, coke deposition on the inner surface of the reactor, determined by the gravimetric method, amounted to about 0.02 kg / t of processed raw materials.

Example 2 (in the conditions of the prototype). Vacuum residue of West Siberian oil visbreaking in the conditions of example 1 in a reactor with a convex elliptical bottom. The residue (+ 180 ° C) obtained as a liquid product with a yield of 86 wt.%, Has a conditional viscosity at 80 ° C of 13.5 and 0.45 wt.%, Mechanical impurities. In this case, coke deposition on the inner surface of the reactor amounted to 0.07 kg / t of processed raw materials.

Thus, the proposed reactor design makes it possible to obtain a product with a reduced content of mechanical impurities (heavy fuel oil) from heavy hydrocarbon feedstocks, as well as to reduce coke deposition in the reactor.

Claims (1)

A thermal conversion reactor for a heavy hydrocarbon feedstock, consisting of a shell, upper and lower bottoms, having a separation space, a nozzle for introducing heat-treated raw materials tangentially located on the shell below the separation space, and nozzles for withdrawing vapors and liquid product located on the upper and lower bottoms, respectively characterized in that the shell, upper and lower bottoms are formed by surfaces of rotation around a vertical axis, while the lower bottom is made in the form of a convex-concave the surface of rotation with a convex part adjacent to the shell of the reactor, and the outlet pipe of the liquid product is located tangentially from the outside of the convex surface of the lower bottom.

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