RU2538754C1 - Tube furnace with flameless combustion - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to tube furnace with flameless combustion that includes a housing with convection and radiation chambers with convective and radiant coils of the furnace and burner installed in lateral sides of the furnace in horizontal rows. The radiant coil is made of horizontal tubes placed in tube plates in two rows along the central axis of the furnace housing. At that radiant burners are grouped in horizontal sections with separate fuel delivery to each burner inside the section. Raw material input to the radiant coil is placed in the furnace hearth.

EFFECT: performance of thermal destructive processes reaching the preset results in optimal conditions.

2 cl, 4 dwg

Description

The invention relates to oil refining, in particular to tubular furnaces for heating oil residues in the processes of visbreaking, thermal cracking, delayed coking.

A tubular flameless combustion furnace is known, including convection and radiation chambers in which convective and radiant coils are placed, wherein a radiant coil of horizontal pipes is placed in tube sheets in two vertical rows along the central axis of the furnace, and flameless burners are installed in the side walls of the furnace body and occupy half of its surface, providing a continuous mirror of radiation [US Pat. RF №2231713, IPC F23C 1/08].

A disadvantage of the known furnace is that only half of the radiant tubes are covered by direct radiation, which, moreover, are heated uniformly from a solid radiation mirror, the latter circumstance precludes the possibility of regulating a given temperature profile along the length of the furnace coil, as well as the residence time of the raw materials in the cracking zone and therefore, achieving maximum overhaul of the furnace

A tube furnace is known, including a box-shaped body with convection and radiation chambers, in which convective and radiant coils are placed, and burners installed horizontally in five rows in the side walls of the radiation chamber along radiant tubes from 6 to 18 m long, depending on the heat output of the furnace. Each horizontal row has a gas manifold, which makes it possible to regulate the heat output of burners of one row and heat transfer to the corresponding row of radiant pipes [summary: Technological furnaces-Xreferat.ru, Fig. 3.2].

A disadvantage of the known furnace is the narrow technological specialization of the furnace, aimed at the pyrolysis of light hydrocarbon feedstocks, for which a rigid scheme of connecting the burners to the gas manifold is sufficient, however, when heating and cracking oil residues, it does not allow controlling the effective coil length with the corresponding adjustment of heat stress and temperature profile when changing the effective length of the irradiated surface of the coil, the residence time of the raw materials in the cracking zone, a given value conversions depending on the properties of the feedstock and the specified quality of the products.

When creating the invention, the task was to expand the capabilities of the known design when conducting thermo-destructive processes with the achievement of desired results in optimal conditions.

This is achieved by the fact that in a tubular flameless combustion furnace, including a box-shaped body with convection and radiation chambers, in which convective and radiant coils and flameless burners are installed, installed in horizontal rows in the side walls of the furnace, and the radiant coil is made of horizontal pipes placed in pipe gratings in two vertical rows along the central axis of the furnace body, according to the invention, flameless burners are grouped into horizontal sections with separate fuel supply to each mountains lke inside the section, wherein the raw material input into radiant coil disposed in the bottom part of the furnace.

The input of raw materials into the radiant coil can be made single or double flow.

Distinctive features from the prototype are the grouping of flameless burners installed in horizontal rows in the side walls in horizontal sections with separate fuel supply to each burner inside the section and the placement of a single or double-flow input of raw materials into the radiant coil in the hearth of the furnace, which makes it possible to adjust the effective length of the radiant furnace coil , the residence time of the raw materials in the cracking zone, a given conversion value depending on the properties of the feedstock, a given quality of the products and continue Continuous furnace elnosti path.

The accompanying drawings show two modifications of the proposed two-chamber tube furnace, where FIG. 1 is a cross-sectional double-flow tube furnace, a front view, FIG. 2 is a side view, FIG. 1 is a cut-out, FIG. 3 is a cross-sectional single-flow tube furnace, view front, figure 4 is a side view, figure 3 with a breakout A.

The furnace includes a box-shaped housing 1, a convection chamber 2 with a convective coil 3, a radiation chamber 4 with a radiant coil 5, a tube sheet 6, flameless panel burners 7, a chimney 8, a line 9 for introducing raw materials into the convective coil 3, a line 10 for introducing raw materials from convection chambers 2 to radiation chamber 4 in the hearth of furnace 1, a line 11 for outputting cracked products from the furnace to a column or reactor (not shown), the first section 12 of flameless panel burners 7, the second section 13, the third section 14, the fourth section 15, the line 16 fuel gas inlet to manifolds with sections, valves 17, 18, 19, 20 on gas manifolds 21, 22, 23, 24 of the first, second, third and fourth sections, respectively, valves 25 (1) -48 (1) on the fuel gas supply lines from the manifold 21 of the first section 12 to the panel burners 7 of the first section, valves 25 (2) -48 (2) on the fuel gas supply lines from the manifold 22 of the second section 13 to the panel burners 7 of the second section (valve numbers are not shown because of their identity), valves 25 ( 3) -48 (3) from the collector 23 of the third section 14 to the burners 7 of the third section, valves 25 (4) -48 (4) from the collector 24 of the fourth section 15 to the burners 7 vert section.

After starting the installation and heating the furnace with starting gas oil, the raw material composition (tar mix with diluent, turbulizer) is fed to the furnace coil along line 9 instead of the starting product. The flow of raw materials with a temperature of 320-380 ° C enters through the input line 10 from the convection coil 3 of the convection chamber 2 into the horizontal pipes of the radiant coil 5 of the radiation chamber 4, placed in the tube sheets 6 vertically along the central axis of the furnace body 1, where it is heated by radiation from flameless burners 7, installed in horizontal rows in the side walls, grouped into horizontal sections 12, 13, 14, 15. Placement of a single-threaded or two-threaded input of raw materials along line 10 in the hearth (lower) part of the furnace and the flow of raw materials through the radio Tnom coil sequentially from the bottom up through the sections 12-15 burner panel 7, to which fuel is distributed from the common header 16 enables adjustment of the effective (irradiated) radiant coil length and profile of the product temperature therealong.

As the coil 5 passes through the radiation chamber in the region of the first section 12 of the panel burners 7, the temperature of the feed stream is increased along the second-order curve to the decomposition value (cracking) of the feed (420-430 ° C), while the flow structure inside the pipe also changes and changes from uniform (liquid medium) to a two-phase (gas-vapor - liquid) with a dispersed-ring structure; in the region of the second section 13 of panel burners 7, the temperature of the feed stream is raised in the previous way to 440-460 ° C, while the feedstock decomposes (cracked) to form low molecular weight, low-viscosity components (gas, gasoline, light and heavy gas oil), the flow volume increases exponentially dependences, accordingly, the flow velocity increases and the flow movement becomes more stable due to the predominance of the dispersion-ring structure of the flow on the greater part of the coil; in the region of the third section 14 of panel burners 7, the temperature of the feed stream increases smoothly to 480 ° C, while more heat-resistant naphthenoaromatic hydrocarbons are involved in the cracking process with a further increase in the fraction of low molecular weight components in the cracking products; in the region of the fourth section 15 of the panel burners 7, the temperature of the feed stream is raised to 490-510 ° C and the feed conversion is adjusted to a predetermined value. The products of heat treatment (cracking) are removed from the furnace through line 11 to a reactor or column (not shown).

The above technology of heating and conversion of raw materials in a tube furnace to 9-15% (gas + gasoline) is used in the processes of delayed coking of oil residues to produce petroleum coke and distillate products - raw materials for the production of motor fuels.

To use the proposed tube furnace in the process of visbreaking oil residues with a socking section to obtain boiler fuel M 100 with a viscosity VU _{80 ° C} = 16 ° E, the above dynamics of increasing the temperature of the raw materials are stored in the region of the first (12) and second (13) sections of panel burners 7 by appropriate adjustment of the fuel supply through remotely controlled valves 25-48, 25 (2) -48 (2), and in the area of the third (14) and fourth (15) sections of the panel burners, the temperature of the product in the coil - soking sections - is reduced to the level 440-460 ° C and can withstand stably about obtaining a given conversion of 5-12% (gas + gasoline) to obtain a product of a given quality.

To use the proposed tube furnace in the furnace visbreaking of oil residues to obtain boiler fuel M 100, the fuel supply to the panel burners of the first section 12 is shut off by a valve 17 on line 21, while the effective (irradiated) coil length is reduced by 25%. In the region of the second section 13 of panel burners, the temperature of the feed stream is increased according to the second order curve to the value of the cracking of the raw material (420-430 ° C), in the region of the third section of 14 panel burners, the temperature of the feed stream is increased to 440-460 ° C, in the region of the fourth section 15 panel burners, the temperature of the feed stream is increased to 470-480 ° C and the feed conversion is adjusted to a predetermined value of 5-12% (gas + gasoline) to obtain a product of a given quality. In this case, the stream 11 before entering the column is cooled to a temperature of 350-380 ° C with a "cold stream" (quench).

Thus, the proposed flameless combustion tube furnace allows you to adjust the specified (effective) length of the radiant coil, the temperature profile on the irradiated surface of the coil, the residence time of the raw materials in the cracking zone, the specified conversion value depending on the properties of the feedstock and the given quality of the products.

Claims (2)

1. Tubeless flameless combustion furnace, comprising a housing with convection and radiation chambers, in which convective and radiant furnace coils and burners are installed, installed in horizontal rows in the side walls of the furnace, and the radiant coil is made of horizontal pipes placed in two rows along the tube sheets the central axis of the furnace body, characterized in that the flameless burners are grouped in horizontal sections with separate fuel supply to each burner inside the section, while the input of raw materials into the radiant kites IR is located in the hearth of the furnace. 2. The flameless combustion tube furnace according to claim 1, characterized in that the input of raw materials into the radiant coil is single or double-threaded.

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