RU2352519C1 - Pyrolysis method of hydrocarbon raw materials - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to pyrolysis method of hydrocarbon raw material - natural gas till hydrogen and carbon, including preheating of hydrocarbon raw material and its feeding to pyrolysis stage, implemented while raw material contact with heated heat-transfer fluid, where for heating of heat-transfer fluid it is used gas fuel combustion in oxidiser with oxygen part 0.4-0.95 and coefficient of oxidant discharge 0.4-0.8, and emission gas of combustion is subject to process of energy-chemical accumulation, for which it is fed natural gas, receiving of by-product fuel, at that increasing combustible components parts and reducing gas temperature till 900-1000°C received by-product fuel is cooled till the temperature 25-150°C ensured by heating of material by it hydrocarbon raw, gaseous fuel and oxidant.

EFFECT: expenditures reduction and improvement of the method.

1 ex, 1 tbl, 1 dwg

Description

The invention relates to ferrous metallurgy, in particular to blast furnace production or coke-free reduction of metals, can be used in the carbon black industry and in the production of hydrogen, with the additional production of precious secondary fuel.

A known apparatus for the pyrolysis of hydrocarbon raw materials, in which the heating of the liquid coolant with a gaseous coolant, the separation of gaseous and liquid coolant, the pyrolysis of hydrocarbon raw materials in contact with a liquid coolant and the separation of a liquid coolant with pyrolysis products, (see. A. USSR USSR No. 1680759, C10G 9/34, publ. 1991).

A disadvantage of the known apparatus for the pyrolysis of hydrocarbons is significant heat loss due to insufficient utilization of the heat of the waste.

The closest analogue to the claimed method is a method for the pyrolysis of hydrocarbons (methane), including preheating of hydrocarbons and feeding it to the pyrolysis stage, carried out in contact with liquid and heating the liquid coolant (see US 5213770 A, May 25, 1993).

The main disadvantages of this method is the lack of a process for utilization of exhaust gases obtained by heating a liquid coolant.

The technical problem solved by the proposed method is to increase efficiency by completely processing the exhaust gas into precious secondary fuel.

The technical problem is solved in that in the known method for the pyrolysis of hydrocarbon feedstocks - natural gas to hydrogen and carbon, which includes preheating of the hydrocarbon feedstock and feeding it to the pyrolysis step carried out by contacting the feedstock with a heated liquid heat carrier, according to the invention, combustion is used to heat the liquid heat carrier gas fuel in the oxidizer with an oxygen fraction of 0.4-0.95 and an oxidizer consumption coefficient of 0.4-0.8, and the exhaust gases of combustion are subjected to an energy-chemical process accumulation, which is fed to them, natural gas, thus increasing the proportion of combustible component and reducing the gases temperature to 900-1000 ° C, the resulting secondary fuel is cooled to a temperature of 25-150 ° C by preheating a hydrocarbon feedstock, gaseous fuel and oxidant.

The proposed method is implemented according to the scheme depicted in the drawing. The scheme consists of a hydrocarbon feedstock heater 1, a hydrocarbon feedstock pyrolysis reaction chamber 2, a liquid heat carrier heating chamber 3, an off-gas energy chemical accumulation chamber (ECA) 4, a fuel heater and an oxidizing agent 5. As working media, the diagram shows: hydrocarbon feedstock 6, liquid coolant 7, pyrolysis products 8, combustion products 9, gas fuel 10, oxidizing agent 11, exhaust gases 12, natural gas for energy-chemical accumulation 13, secondary fuel 14.

The scheme works as follows. Hydrocarbon feedstock (natural gas) 6 with a temperature equal to the ambient temperature enters the hydrocarbon feedstock heater 1, where it is heated to 500-700 ° C, then it enters the hydrocarbon feedstock pyrolysis reaction chamber 2, where the heated hydrocarbon feedstock under the action of a liquid coolant 7 Heats up to a temperature of 1300-1500 ° C and thermal decomposition of natural gas into hydrogen and carbon is carried out by the reaction:

CH ₄ = C + 2H ₂

From the pyrolysis reaction chamber of hydrocarbon feedstock 2, pyrolysis products exit 8. Heating of the liquid coolant 7 is carried out by the combustion products of fuel 9, which are obtained by burning gas fuel (natural gas) with an oxidizing agent 11. Gas fuel 10 and an oxidizing agent 11 with an initial temperature equal to the ambient temperature enter the gas fuel heater and oxidizer 5, the fuel 10 is heated to a temperature of 500-700 ° C, and the oxidizer 11 to a temperature of 600-1000 ° C, after which the gas fuel 10 and the oxidizer 11 are fed to rhenium into the heating chamber of the liquid coolant 3. Waste gases 12 with a temperature of 1400-1600 ° C from the heating chamber of the liquid coolant 3 enter the chamber of energy-chemical accumulation (ECA) of the exhaust gases 4, where natural gas for ECA 13 is supplied with a temperature equal to the ambient temperature in an amount of 0.05-0.12 m ³ / m ^{3 of} exhaust gas of combustion. In the chamber of energy-chemical accumulation (ECA) of the exhaust gas 4, chemical reactions occur between methane (CH ₄ ) of natural gas 13 and carbon dioxide (CO ₂ ) and water vapor (H ₂ O) of the exhaust gas 12 according to the following chemical reactions:

CO ₂ + CH ₄ = 2CO + 2H ₂ ;

2H ₂ O + CH ₄ = 2H ₂ + CO ₂ .

As a result of this, the temperature of the exhaust gas of combustion decreases to 900-1000 ° C and secondary fuel 14 is obtained in the chamber of energy-chemical accumulation 4 with a temperature with a high content of carbon monoxide (CO) and hydrogen (H ₂ ) compared to the exhaust gas 12. The resulting secondary fuel 14 is sent to the hydrocarbon feed heater 1 and the gas fuel and oxidizer heater 5, where it heats the hydrocarbon feed 6, gas fuel 10 and oxidizer 11, as a result of which they are cooled to a temperature of 25-100 ° C and sent to to the shipper.

The heat of combustion, heat production and the specific amount of fuel gas obtained during the pyrolysis of 1 m ^{3 of} hydrocarbon raw materials (natural gas) depend on the oxidizer used (the ratio of oxygen and nitrogen in the oxidizer - K _O2 ) and on the combustion mode (oxidizer consumption coefficient - α) . Fuel characteristics depending on K _O2 and α are presented in table 1.

Thus, in the inventive method for the pyrolysis of hydrocarbons in a liquid coolant when receiving secondary fuel, it is possible to significantly reduce the consumption of fuel and energy resources by obtaining secondary fuel of various parameters and to ensure transportation of the resulting secondary fuel by lowering its temperature during regenerative heating of hydrocarbon raw materials, gas fuel and an oxidizing agent.

Table 1. K _O2 α The specific amount of fuel gas, m ³ Calorific value of fuel gas, kJ / m ³ Heat output of fuel gas, ° С 0.40 0.4 6.76 7903 2022 0.5 7.16 6829 1890 0.6 4.05 5755 1758 0.8 3.72 4072 1472 0.60 0.4 5.66 8952 2102 0.5 4.42 7799 1976 0.6 3.18 6645 1849 0.8 2.92 4641 1544 0.80 0.4 5.12 9639 2148 0.5 3.97 8463 2027 0.6 2.82 7286 1905 0.8 2.54 5086 1593 0.95 0.4 4.87 10016 2172 0.5 3.77 8839 2054 0.6 2.66 7660 1935 0.8 2,36 5361 1621

при коэффициенте избытка окислителя α=0,6, при этом происходит нагрев жидкометаллического теплоносителя до 1600°С. Далее в нагревательной камере 3 происходит разделение газовой и жидкой фазы, при этом жидкометаллический теплоноситель направляется в реакционную камеру 2, а отходящие газы в 12 с температурой 1600°С - в камеру энергохимической аккумуляции (ЭХА) отходящих газов 4, также в камеру 4 подводится природный газ 13 с температурой 0°С в количестве 0,10 м³/м³ отходящих газов 12. После смешения потоков 12 и 13 температура газовой смеси вторичного топлива 14 становится равной 900°С, а доля СО и Н₂ увеличилась соответственно в 1,45 и 2,42 раза по сравнению с отходящими газами 12. Далее вторичное топливо 14 отправляется в подогреватель углеводородного сырья 1 и в подогреватель подогрева топлива и окислителя 5, где охлаждается до температуры 65°С, далее вторичное топливо смешивается в единый поток и направляется к потребителю топлива.Example. Hydrocarbon feedstock (natural gas) 6 with a temperature of 0 ° C is supplied to the hydrocarbon feed heater 1, at the same time secondary fuel 14 with a temperature of 900 ° C is supplied to the heater 1, the hydrocarbon feedstock 1 is heated with secondary fuel 14 without mixing. Next, the hydrocarbon feed with a temperature of 600 ° C enters the pyrolysis reaction chamber of hydrocarbon feed 2, at the same time, the liquid metal coolant 7 with a temperature of 1600 ° C flows into chamber 2, while the hydrocarbon feed is heated to a temperature of 1300 ° C, which contributes to the process of hydrocarbon pyrolysis raw materials. Then, in the reaction chamber 2, the gas and liquid phases are separated (similar to the prototype), the products of the pyrolysis of hydrocarbon raw materials 8 with a temperature of 1300 ° C go to the consumer, and the liquid metal coolant 7 with a temperature of 1300 ° C enters the heating chamber 3, where the combustion products 9 with a temperature of 2197 ° C, obtained by burning fuel 10 with an initial temperature of 600 ° C in an oxidizing agent 11 with an initial temperature of 827 ° C

when the coefficient of excess oxidizer α = 0.6, the heating of the liquid metal coolant to 1600 ° C. Then, in the heating chamber 3, the gas and liquid phases are separated, while the liquid metal coolant is sent to the reaction chamber 2, and the exhaust gases at 12 with a temperature of 1600 ° C are sent to the energy-chemical accumulation chamber (ECA) of the exhaust gases 4, and natural gas 13 with a temperature of 0 ° C in the amount of 0.10 m ³ / m ^{3 of} exhaust gas 12. After mixing the flows 12 and 13, the temperature of the gas mixture of the secondary fuel 14 becomes equal to 900 ° C, and the proportion of CO and H ₂ increased respectively by 1, 45 and 2.42 times compared with outgoing g basics 12. Next, the secondary fuel 14 is sent to the hydrocarbon feed preheater 1 and to the fuel and oxidizer preheater 5, where it is cooled to a temperature of 65 ° C, then the secondary fuel is mixed into a single stream and sent to the fuel consumer.

As a result, it was found that in this case it is possible to obtain secondary fuel with a heat of combustion of 7240 kJ / m ³ , with a heat output of 1920 ° C in the amount of 3.8 m ³ / m ^{3 of} hydrocarbon feedstock.

Claims (1)

The method of pyrolysis of hydrocarbon feedstocks - natural gas to hydrogen and carbon, including preheating of the hydrocarbon feedstock and feeding it to the pyrolysis step carried out by contacting the feedstock with a heated liquid coolant, characterized in that for heating the liquid coolant, gas fuel is burned in an oxidizer with a fraction of oxygen 0.4-0.95 and an oxidizer consumption coefficient of 0.4-0.8, and the exhaust gases are subjected to a process of energy-chemical accumulation, for which natural gas is fed into it, obtaining a secondary e fuel, thus increasing the proportion of combustible component and reducing the gases temperature to 900-1000 ° C the resulting secondary fuel is cooled to a temperature of 25-150 ° C by heating them to hydrocarbon feed of gaseous fuel and oxidant.