CS239806B1 - A method of producing ethylene and acetylene - Google Patents

Abstract

The subject of the invention is a method for producing ethylene and acetylene from petroleum raw materials by high-temperature pyrolysis. The heat carrier, which directly transfers energy to the raw material, uses residual gas flue gases, from which, in addition to carbon dioxide, carbon monoxide is also removed by low-temperature condensation or absorption separation. The pyrogas thus formed contains an increased amount of the desired Cz fraction at the expense of the carbon monoxide and carbon dioxide content.

Description

233308

The present invention provides a process for the preparation of ethylene and / or acetylene by high temperature pyrolysis furnaces, petroleum fractions and / or hydrocarbons by direct contact of the pyrolyzed feedstock with a heat carrier in the separation of carbon oxides.

High temperature pyrolysis of crude oil, petroleum and / or hydrocarbons is a petrochemical process that utilizes hydrocarbon feedstocks to produce energy-rich low hydrocarbons, especially acetylene and its homologues, while producing olefins, especially ethylene and propylene.

Unlike ethylene units, where the pyrolysis temperature is up to 850 ° C, high temperature pyrolysis uses temperatures above 1000 ° C. The amount of energy supplied to the raw material is directly influenced by the energy content of the products, especially the acetylene: ethylene ratio. At higher acetylene temperatures, the final pyrolysis temperature is above 1,200 ° C, and therefore most successful technological processes select the pyrolysis of the direct contact of the heating medium with the raw material (Šlejnikov V. M .: Ustanovki po · proizvodstvuacetilena iz nefti i gaza, Moscow 1905).

Typically, the flue gas is used as the heating medium, either the raw material portion (process KELOGG, MONTECATINI, etc.) or, in the newer processes, the time of the pyropolymer, which is not chemically utilized (the process of HTP by HOECHST, KUREHA CHIYODA, BASF etc. .). For the combustion, pure oxygen is used, both to prevent the loss of energy for heating the inert gases, but in particular to allow the formation of nitrogen oxides at higher temperatures.

The residual gas used for the combustion comprises hydrogen, methane, carbon monoxide and carbon dioxide, the hydrocarbons Cz and C3-4 fractions in the residual gas are present in the minimum amounts in terms of recoverable products or in the residual gas. with the possibility of recycling pyrolysis. Part of the residual gas needs to be vented to prevent incrementing (CO2, Na, Ar) content in the pyrolysis. Some processes (HTP process) divide the CO2 from the pyridine as a separate component (Kamptner Η K.:Chem. Eng.). (Feb. 28, 1966, pp. 80-82.)

The pyropylene composition and pyrolysis yield depend on the thermodynamic equilibria and the kinetics of the individual partial reactions. The highest yields have two-stage reactors in which the combustion gases are produced in the first stage and the raw material is sprayed in the second stage. In the first stage of such reactors, a temperature of more than 2600 < 0 > C is formed, with considerable radical dissociation of most of the inlet components as well as upstream products. To combine the degradation reactions of the decomposition of carbonaceous structures to carbonaceous carbon, a large-scale reaction time (10-3 s) and an addition of water vapor (secondary water vapor) are used to effectively shift the reaction equilibria. in particular, there are those reactions: (Vvedensky: Thermodynamic Calculations of Petrochemical Processes, SNTZ1963):

2 Ur -} - O2 H2O2 CO + O2 ---> 2 CO2

2 CHi + 3 O2 ------ 2 CO + 4 H2O Ο ,, Η? ,, ► n 'CH2' H2O> H "+ - OH" CO2> CO + 0 '' CH2 '> · Cj-2 H 'n -CH 3, CH 3' -> and C 2 H 2 + b C z H d + + C x H y In particular, radical grafts of oxygen, water and hydrocarbons are used in the reaction. The resulting product is dependent on the amount of energy, ie the temperature and the degree of radicalization, which affects the reactivity of the feedstock, further from the reaction time and the composition of the combustion gas and the raw material.

The temperature of the reaction in the given structure of the reactor is mainly due to the amount and the heating of the residual gas in the ratio of the soil and the secondary water vapor. The reaction time is determined by the design and loading of the reactor, as well as the efficiency of quenching the reaction at the outlet of the reactor (Pat. No. 1,460,638). In the context of the present invention, it has been found that the reaction equilibria significantly affect the carbon oxides and the concentrations of radicals involved in their formation and their decomposition. Important is their ratio to the hydrocarbon feedstock and hydrogen. The combustion of the residual gas takes place with a target gas excess (1 to 5%), i.e. the oxygen is completely reacted. There is a significant reduction atmosphere in the reactor, and carbon monoxide is produced in addition to carbon dioxide. The kinetics of combustion of two residual gas components, methane and carbon monoxide, also play an important role here. The higher combustion rate, as well as the CO / CO2 equilibrium shifted considerably in favor of CO, results in an increase in carbon monoxide content.

The higher 00 content in the residual gas reduces the combustion rate, i.e., at a very short reaction time in the reactor, the energy utilization of the residual gas has an impact and the process yield.

Therefore, in the sense of the present invention, the CO content of the system is to be minimized. To maintain the inert level, especially the nitrogen, the required portion of the recirculated gas is separated by the system, but a high level of CO 2 reduces the yields of the C2-fraction.

The process of producing ethylene and acetylene from hydrocarbon feedstocks in accordance with the invention by high temperature pyrolysis at a temperature of 10-10 800 ° C and a pressure of 0.03 to 2.0 MPa 5 - with direct contact of the feedstock with the heat recovery carrier which are the flue gas of the residual gas which is generated from the pyrolysis by dividing the fractions including carbon in the molecule and more and the carbon dioxide being characterized by separating the carbon monoxide from the residual gas to a concentration below 15%, preferably below 5% by volume physical / or chemical procedures. It is preferred to use a low temperature condensation followed by distillation at a temperature of -109 ° C to 160 ° C with distillation. the remainder is returned to the pyropolymer and / or to the absorption decomposition. In the following, the examples illustrate, but do not limit, the use of the invention

On the two-stage pyrolysis of the HTP Hoechst reactor, the hydrocarbon feedstock is primary gasoline, composed of: paraffins naphthenes aromatics olefins 72 to 77% by weight2 to 26% by weight. 0.9 wt.%, 0.1 wt.

The raw material distillation range is 30 to 120 ° C. Primary gasoline is enriched in saturated pyrrole gas with a saturated C 3 to C 5 pyrrole fraction (15 to 17% of total) and gassed and heated to 180 ° C enters the reactor.

Oxygen and residual gas entering the first stage of the reactor are in excess of 4% of the compound: hydrogen 62.5% v / v methane 1.6.0% v / v carbon monoxide 20.0% v / v, moreover (nitrogen, argon, ethylene) 1.5% vol.

Secondary water vapor is added at a temperature of 380 QC and the amount. 70% by weight. The amount of gas is 52% by weight. raw materials.

By burning the gas, a temperature of 2500 degrees C is formed, and after the feedstock is added, the reaction temperature is 1200 to 1250 ° C. The pressure in the reactor is 0.3 MPa. The reaction time is from 1 to 10 -3 s. The pyridine gas produced is cooled to 250 ° C, higher portions are condensed and water is condensed.

After cooling to 3030 ° C and separation of the C 3 to C 5 fraction, the pyrrole gas has the composition: θθ / ο v / v% v / v.

B

The lower acetylene and ethylene depletion is due to the imperfect separation of the carbon oxides, consisting in the separation of CO 2 and the release of part of the residual gas from the system. A portion of the carbon monoxide was returned to the reactor in the residual gas. Example 2 Plane in the composition: hydrogen methane oxide carbon monoxide, .argon, ethylene 1 S: 16% 1 binds to 65.5% v / v 17.6% v / v 15.5% v / v, i; Art.

The amount and composition of the feedstock as well as the amount of secondary water vapor remain unchanged.

The composition of the pyrope after separation of the heavier parts. water, the C3 to Cs fraction is as follows:% vol% vol acetylene 12.6 16.5 ethylene 12.0 17.0 hydrogen 33.5 3.4 methane 13.0 '' 10.5 carbon monoxide 13.5 19 , 1 carbon dioxide 14.5 32.2 inerts 0.9 1.3

The higher content of acetylene and ethylene results in a reduction of the carbon monoxide content of the residual gas caused by the partial separation of the pyrolysis gas into hydrogen and methane fractions, with CO being mainly present in the methane fraction. In particular, a hydrogen fraction is used for the residual gas, the possible fluctuations of which are equalized from the pressure gas cylinder. This saves natural gas when the machine is started up, but it reduces the running time of the machine. Example 3

Residual gas is supplied to the apparatus as in Example 1 in an amount of 32.6% to the feedstock of the composition: hydrogen methane oxide carbon monoxide, argon, ethylene 73.8% v / v, 19.7. % vol.5.0% vol 1.5% vol acetylene 12.0 15.1 ethylene 11.5 15.6 hydrogen 31.8 3.1 methane 13.0 10.1 carbon monoxide 14.2 19 3 carbon dioxide 16.6 35.5 inerts 0.9 1.2

The amount and composition of the feedstock as well as the amount of secondary water vapor remain unchanged.

The composition of the pyropolymer after the separation of the heavier parts, water, C3 to C5 is as follows:

Claims (1)

] 'e e M e τ Process for producing ethylene and acetylene from petroleum, petroleum fractions and / or hydrocarbons by high-temperature pyrolysis at a temperature of 100Ό to 2 800 ° C and a pressure of 0.13 to 2.0 MPa with direct contact of the feedstock with a reaction heat carrier. It is produced from pyroplyn after isolation of fractions of 2 or more carbons and carbon dioxide, characterized by the fact that OF THE INVENTION gas is separated by carbon monoxide to a residual gas content below 15% by volume, preferably 5% by volume, by physical and / or chemical processes, preferably by low temperature condensation followed by distillation at a temperature of -100 to -160 ° C, the distillation residue returns to the pyrop gas and / or to the absorption delenle.