RU2537582C2 - Method of black production from hydrocarbon gas - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention can be used in chemical, petrochemical, general rubber and pain and varnishes producing branches of industry. The rich mixture of hydrocarbon gas with air is burnt at air excess factor equal to α=(1…1.2)α_COmax≈0.7…0.9. The α_COmax value is defined against numbers of hydrocarbon n and hydrogen m atoms in an apparent molecule of hydrocarbon gas and calculated as the ratio (2n+m)/(4n+m). The mixture of hydrocarbon gas fuel with air may be heated up to 60-299°C before delivery to burning. Hydrocarbon gas preheated up to 100-400°C is subjected to pyrolysis with combustion products. The combustion products are hardened by superheated demineralised water, cooled in the heat exchanger and outputted through the target product collector.

EFFECT: increasing output of carbon black due to improved carbon-black formation.

5 cl, 1 dwg, 4 ex

Description

The invention relates to a technology for producing carbon black (soot) from hydrocarbon gas, both natural and associated, and can be used in the chemical, petrochemical, rubber, printing, and varnish and paint industries using carbon black.

Currently, more than 90% of carbon black obtained by technological schemes of continuous processes is produced from liquid raw materials. However, these processes are very sensitive to the quality of the feed (hydrocarbon composition, the content of non-hydrocarbon impurities), which in the case of liquid feed (heavy pyrolysis resin, heavy catalytic cracking gas oil, anthracene fraction, etc.) is not constant from batch to batch. In this regard, there are deviations in the structure parameters of the carbon black particles and its particle size distribution from the expected values, that is, the inconsistency in the quality of carbon black, which can lead to a deterioration in the quality of the final product containing carbon black (printing ink, structural materials, etc.) .

The composition of natural gas from known fields is more defined, so the quality of carbon black from it can be more stable. However, modern technological processes of industrial production of carbon black from natural gas do not provide the same high performance as from liquid raw materials.

The most common are batch technologies based on regenerative gas heaters.

Known methods for producing carbon black by pyrolysis of natural gas in a stream of products of combustion of the same gas mixed with air, in which part of the carbon-containing pyrolysis products are fed into the pyrolysis zone of the raw materials with subsequent quenching of products (USSR Authenticity Certificate No. 850642, publ. 30.07.1981, class C09C 1/50 [2] and RF patent RU 2174992, published on October 20, 2001, class C09C 1/48 [3]). At the same time, recirculation of a part of the pyrolysis products taken to the quenching zone increases the depth of pyrolysis of the feedstock by introducing active particles into the composition of the reacting mixture and additional condensation centers of carbon black precursor molecules.

The disadvantages of these methods are:

1) insufficiently high yield of carbon black due to large values of the coefficient of excess air (more than 1.2 in the method [2] and 0.9-1.1 in the method [3]), in connection with which part of the carbon of the feed is oxidized to CO ;

2) large values of dispersions of quality indicators of carbon black (parameters of the structure of the material of carbon black particles and its particle size distribution) and the practical impossibility of obtaining high values of the specific surface area of soot particles due to the participation in the formation of additional condensation centers introduced with recirculation products.

More productive is the prototype method of producing soot from hydrocarbon gas by pyrolysis of hydrocarbon gas (natural or petroleum associated gas), which includes burning a mixture of hydrocarbon gas-fuel and air, mixing combustion products with hydrocarbon feed gas, quenching the pyrolysis products with demineralized water introduced into in the form of jets into the soot aerosol stream, further cooling of this aerosol in heat exchangers with their removal through the target product collection devices (RF patent RU 2114138, publ. 06/27/1998, cl . C09C 1/48 [4]).

The disadvantage of this method is the significant loss of carbon on its oxidation due to the high values of the coefficient of excess air in the combustion chamber.

The objective of the invention is to increase the yield of carbon black by increasing soot formation.

The problem is solved due to the fact that in the method of producing soot from hydrocarbon gas (natural or oil associated), including burning a mixture of hydrocarbon gas-fuel and air, pyrolysis of the hydrocarbon gas in the mixture with combustion products, quenching of the pyrolysis products with demineralized water and further cooling of this aerosol in a heat exchanger with their removal through the target product collection device, fuel combustion is carried out as part of a rich air-fuel mixture with the excess coefficient air α = (1 ... 1,2) α _COmax ≈0.7 ... 0.9, and demineralized water is supplied to quenching in an overheated state (at a temperature of 120-130 ° C).

In this case, it is preferable to determine the characteristic value of α _COmax from the numbers of atoms, respectively, of carbon n and hydrogen m in a conventional hydrocarbon gas molecule and calculate it as the ratio (2n + m) / (4n + m), and for the parameter of the raw material that determines the required values of the raw material consumption , fuel, air and water, as well as temperatures of intermediate products and the duration of the induction period of soot formation, soot particle growth and quenching at the required output parameters, structure and dispersion of the target product, take the diffusion flame black index and characterizing hydrocarbon gas propensity to sooting.

It is also preferable to pre-heat the mixture of hydrocarbon gas-fuel with air to 60-299 ° C.

The yield of the target product is further enhanced if the hydrocarbon feed gas is heated to 100-400 ° C before being fed to the pyrolysis.

The essence of the invention lies in the implementation of the pyrolysis of hydrocarbon feed gas in conjunction with the products of combustion of a rich mixture of hydrocarbon gas fuel and air, which is burned with a coefficient of excess air in the range of 0.7 ... 0.9. In this case, soot formation increases, which allows to increase the yield of the target product.

The invention is explained in more detail using the process flow diagram, where

1 - combustion chamber of hydrocarbon gas fuel

2 - a chamber for the pyrolysis of hydrocarbon gas,

3 - hardening chamber,

4 - actuator for supplying air to the combustion chamber,

5 - actuator feed hydrocarbon gas fuel

6 - Executive device for the supply of hydrocarbon gas raw materials,

7 - actuator supply of superheated demineralized water,

8 is a computer that controls the actuators,

9 - heat exchanger (s),

10 is a device for collecting the target product.

Hydrocarbon gas-fuel and air are supplied to the combustion chamber 1 by means of actuators 5 and 4 at the command of computer 8 in accordance with a program that sets the coefficient of excess air α = (1 ... 1,2) α _COmax ≈0.7 ... 0.9 in fuel mixture. As this rich mixture of hydrocarbon gas-fuel and air is burned, the combustion products enter the pyrolysis chamber 2. The hydrocarbon gas feed is supplied to the same chamber 2 by the actuator 6 by the command of computer 8, and the mixture is pyrolyzed with this gas . The pyrolysis products are then quenched in chamber 3 with superheated demineralized water injected in the form of jets into the soot aerosol stream by means of an actuator 7 at the command of computer 8. Further cooling of this aerosol is carried out in a heat exchanger 9. After that, the target product is discharged through the target product collecting device 10.

The values of the consumption of raw materials, fuel, air and water, as well as temperatures and the duration of the various stages of the technological process are set depending on the properties of the hydrocarbon feed (the tendency of hydrocarbon gas to soot formation) and the required parameters of the structure and dispersion of the target product.

Wherein:

1) the characteristic value of the coefficient of excess air α _COmax is determined by the formula:

,

,

where n and m are the numbers of atoms, respectively, of carbon and hydrogen in a conventional hydrocarbon gas molecule, determined by its component composition (molar mass excluding non-hydrocarbon impurities and mass fractions of carbon and hydrogen in the hydrocarbon part of the gas);

2) the propensity of hydrocarbon feedstocks to soot formation is evaluated by the value of the diffusion flame blackness index (PCPD), determined using an instrument with an oil-free burner [1];

3) the air and hydrocarbon gas involved in combustion are heated to a temperature of 60-299 ° C before being fed into the combustion chamber;

4) hydrocarbon gas, which is the raw material for the production of soot, is heated to a temperature of 100-400 ° C before being fed to the pyrolysis;

5) the time point of the beginning of hardening is determined based on the required properties of soot and its output, taking into account the geometry of the flow part of the reactor, the flow rate of the reactants and products, as well as the values of the soot formation induction period τ _ind. and the required soot particle growth time τ _growth ;

6) the period of induction of soot formation is calculated by the formula:

,

,

; p - давление в реакторе, Па;where a = (9.2-3.8i _R ) 10 ^-9 and b = 21000-1800i _R are the coefficients that are functions of the tendency of hydrocarbon gas to soot formation;

; p is the pressure in the reactor, Pa;

- эффективное значение «восстановленной» концентрации углеводородов в зоне пиролиза; α_пир. - эффективное значение коэффициента избытка воздуха в зоне пиролиза, рассчитываемое с учетом расходов воздуха и углеводородного газа, участвующего в горении и сажеобразовании; L₀ - стехиометрический коэффициент газа по отношению к воздуху;

- the effective value of the "restored" concentration of hydrocarbons in the pyrolysis zone; α _feast. - the effective value of the coefficient of excess air in the pyrolysis zone, calculated taking into account the flow rates of air and hydrocarbon gas involved in combustion and soot formation; L ₀ is the stoichiometric coefficient of gas with respect to air;

7) the required growth time of soot particles in the design mode of operation of the reactor is calculated by the formula:

,

,

Where

- время релаксации досажевого углерода (время снижения доли углерода сырья, находящегося в досажевом состоянии, в е раз);

- relaxation time of carbon black (time to reduce the proportion of carbon of raw materials in the carbon black state, e times);

ξ _Sp. - the required value of the depth of soot formation (degree of conversion of carbon of raw materials into soot), which is in the range from 0 to 1.

The advantages of the method are illustrated by the following examples (for a reactor with a capacity of 400 tons of carbon black per year, with a channel diameter in the pyrolysis zone of 0.216 m and its length l = 1.22 m).

Example 1. The composition of natural gas (molar fractions of the main components):

CH ₄ (0.9793); C ₂ H ₆ (0.0083); C ₃ H ₈ (0.00209); C ₄ H ₁₀ (0.00744); C ₅ H ₁₂ (0.00182); C ₂ H ₄ (0.00105).

;The values of the fuel parameters: n = 1.04; m = 4.16; α _COmax = (2n + m) / (4n + m) = 0.749; L ₀ = 17.22; i _R = 0.0537;

;

a = (9.2-3.8i _R ) 10 ^-9 = 8.996 · 10 ^-9 ; b = 2100-1800i _R = 2.09 · 10 ⁴ .

To organize the flow of gaseous reactants and products along the reactor path with given speeds and residence times in the respective zones, the air and natural gas at the inlet to the reactor have excess pressure. Moreover, taking into account the hydraulic resistance in the previous sections, the pressure in the pyrolysis zone is p = 2.4 · 10 ⁵ Pa.

With the coefficient of excess air in the combustion chamber α = 1.15α _COmax = 0.861, the initial temperature of the gas for pyrolysis and the gas-air mixture at the inlet to the combustion chamber 300 K, the ratio of the amounts of gas for combustion and pyrolysis ψ = 0.5:

;

;

;

;

; время роста частиц техуглерода

; степень превращения углерода сырья в технический углерод

.the temperature of the combustion products at the outlet of the combustion chamber 1912 K, the temperature of the mixture of combustion products and gas supplied to the pyrolysis T = 1454 K; product flow velocity in the pyrolysis zone u = 10.9 m / s; soot induction period

; carbon black particle growth time

; the degree of conversion of carbon raw materials into carbon black

.

Example 2. The composition of natural gas (molar fractions of the main components):

CH ₄ (0.9793); C ₂ H ₆ (0.0083); C ₃ H ₈ (0.00209); C ₄ H ₁₀ (0.00744); C ₅ H ₁₂ (0.00182); C ₂ H ₄ (0.00105).

;The values of the fuel parameters: n = 1.04; m = 4.16; α _COmax = (2n + m) / (4n + m) = 0.749; L ₀ = 17.22; i _R = 0.0537;

;

a = (9.2-3.8i _R ) 10 ^-9 = 8.996 · 10 ^-9 ; b = 2100-1800i _R = 2.09 · 10 ⁴ .

To organize the flow of gaseous reactants and products along the reactor path with given speeds and residence times in the respective zones, the air and natural gas at the inlet to the reactor have excess pressure. Moreover, taking into account the hydraulic resistance in the preceding sections, the pressure in the pyrolysis zone is p = 2.4 · 10 ⁵ Pa.

With the coefficient of excess air in the combustion chamber α = 1.15α _COmax = 0.861, the initial temperature of the gas for pyrolysis and the gas-air mixture at the inlet to the combustion chamber 300 K, the ratio of the quantities of gas for combustion and pyrolysis ψ = 0.7:

;

;

;

;

; время роста частиц техуглерода

; степень превращения углерода сырья в технический углерод

.the temperature of the combustion products at the outlet of the combustion chamber 1911 K, the temperature of the mixture of combustion products and gas supplied to the pyrolysis T = 1559 K; product flow velocity in the pyrolysis zone u = 10.9 m / s; soot induction period

; carbon black particle growth time

; the degree of conversion of carbon raw materials into carbon black

.

Example 3. The composition of natural gas (molar fractions of the main components):

CH ₄ (0.9793); C ₂ H ₆ (0.0083); C ₃ H ₈ (0.00209); C ₄ H ₁₀ (0.00744); C ₅ H ₁₂ (0.00182); C ₂ H ₄ (0.00105).

;The values of the fuel parameters: n = 1.04; m = 4.16; α _COmax = (2n + m) / (4n + m) = 0.749; L ₀ = 17.22; i _R = 0.0537;

;

a = (9.2-3.8i _R ) 10 ^-9 = 8.996 · 10 ^-9 ; b = 2100-1800i _R = 2.09 · 10 ⁴ .

To organize the flow of gaseous reactants and products along the reactor path with given speeds and residence times in the respective zones, the air and natural gas at the inlet to the reactor have excess pressure. Moreover, taking into account the hydraulic resistance in the preceding sections, the pressure in the pyrolysis zone is p = 2.4 · 10 ⁵ Pa.

With the coefficient of excess air in the combustion chamber α = 1.15α _COmax = 0.861, the initial temperature of the gas for pyrolysis and the gas-air mixture at the inlet to the combustion chamber 600 K, the ratio of the amounts of gas for combustion and pyrolysis ψ = 0.5:

;

;

;

;

; время роста частиц техуглерода

; степень превращения углерода сырья в технический углерод

.the temperature of the combustion products at the outlet of the combustion chamber 1912 K, the temperature of the mixture of combustion products and gas supplied to the pyrolysis T = 1518 K; product flow velocity in the pyrolysis zone u = 11.4 m / s; soot induction period

; carbon black particle growth time

; the degree of conversion of carbon raw materials into carbon black

.

Example 4. The composition of natural gas (molar fractions of the main components):

CH ₄ (0.800); C ₂ H ₆ (0.080); C ₃ H ₈ (0.040); C ₄ H ₁₀ (0.040); C ₅ H ₁₂ (0.020); C ₂ H ₄ (0.020).

The values of the fuel parameters: n = 1,355; m = 5.069;

α _COmax = (2n + m) / (4n + m) = 0.7416; L ₀ = 16.97; i _R = 0.08704;

;

;

a = (9.2-3.8i _R ) 10 ^-9 = 8.996 · 10 ^-9 ; b = 2100-1800i _R = 2.09 · 10 ⁴ .

To organize the flow of gaseous reactants and products along the reactor path with given speeds and residence times in the respective zones, the air and natural gas at the inlet to the reactor have excess pressure. Moreover, taking into account the hydraulic resistance in the preceding sections, the pressure in the pyrolysis zone is p = 2.4 · 10 ⁵ Pa.

With the coefficient of excess air in the combustion chamber α = 1.15α _COmax = 0.853, the initial temperature of the gas for pyrolysis and the gas-air mixture at the inlet to the combustion chamber 600 K, the ratio of the quantities of gas for combustion and pyrolysis ψ = 0.5:

;

;

;

;

; время роста частиц техуглерода

; степень превращения углерода сырья в технический углерод

.the temperature of the combustion products at the outlet of the combustion chamber 1927 K, the temperature of the mixture of combustion products and gas supplied to the pyrolysis T = 1532 K; the flow rate of products in the pyrolysis zone u = 10.67 m / s; soot induction period

; carbon black particle growth time

; the degree of conversion of carbon raw materials into carbon black

.

As can be seen from the above examples, the process for producing carbon black from natural gas is quite sensitive to the composition of the feedstock, the initial temperature of the hydrocarbon gas feedstock and the gas-air fuel mixture supplied to the combustion chamber, and also to the ratio of the amounts of hydrocarbon gas used, respectively , as fuel and as raw material for carbon black.

Literature

1. A method for assessing the propensity of hydrocarbon fuel for soot formation during combustion: US Pat. 2,199,737; Grew up. Federation: IPC G01N 33/22 / Zavyalov V.A., Isaev A.V., Reznikov M.N., Shishaev S.V .; Applicant and patent holder of FSUE “25 State Research Institute of the Ministry of Defense of Russia”. - No. 2001110714/28; declared 04/23/2001; publ. 02/27/2003.

2. Auth. USSR certificate No. 850642, publ. 07/30/1981, class С09С 1/50.

3. RF patent RU 2174992, publ. 10/20/2001, class C09C 1/48.

4. RF patent RU 2114138, publ. 06/27/1998, class C09C 1/48.

Claims (5)

1. A method of producing carbon black from a hydrocarbon gas (natural or oil associated), including burning a mixture of hydrocarbon gas-fuel with air, pyrolysis of the hydrocarbon gas in the mixture with combustion products, quenching the pyrolysis products with demineralized water and further cooling the aerosol in a heat exchanger with removing them through the device for collecting the target product, characterized in that the combustion of hydrocarbon gas-fuel is carried out as part of a rich mixture of it with air at a coefficient excess air that α = (1 _{... 1,2) α COmax ≈0,7 ... 0,9} , and demineralised water is fed to quenching the pyrolysis products in the superheated state. 2. The method according to claim 1, in which the characteristic value of α _COmax is determined by the number of carbon atoms n and hydrogen m in the conventional hydrocarbon gas molecule and calculated as the ratio (2n + m) / (4n + m). 3. The method according to any one of claims 1 or 2, in which the mixture of hydrocarbon gas-fuel with air is heated to 60-299 ° C before being fed to the combustion. 4. The method according to any one of claims 1 or 2, in which the hydrocarbon feed gas is heated to 100-400 ° C before being fed to the pyrolysis. 5. The method according to claim 3, in which the hydrocarbon gas is fed to a pyrolysis feed to 100-400 ° C.

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