SU998820A1 - Method of separating carbon dioxide from hydrocarbon mixtures - Google Patents

Description

The disadvantages of this method are that it requires a large amount of heat in the stripping columns (desorbers), as well as high energy costs for compressing carbon dioxide produced in the gas phase for its injection into the formation, which leads to a large increase in energy costs. The aim of the invention is to reduce energy costs when implementing the method (for the same degrees of purification). The goal is achieved by the fact that according to the method of separating carbon dioxide from hydrocarbon mixtures, including the absorption of carbon dioxide by amines from the compressed source gas with the subsequent regeneration of the absorbent and its compression of carbon dioxide, dividing the initial mixture into two streams, all of which are compressed to an intermediate pressure, the second is subjected to absorption, then compressed to an intermediate pressure, mixed with the first stream and dissolved to a low temperature {1st separation per steam fraction s and liquid (cd carbon dioxide, the liquid fraction is compressed, and the vapor fraction is returned to the original mixture. The drawing shows a scheme for implementing the method. The method is carried out following purified from mechanical impurities and free water compressed to a pressure of 0.588 MPa Noah's gas 1 is divided into two streams 2 and 3, containing 50-60 and 4O-5O% of raw gas, respectively. Stream 2 is sent successively to absorbers 4-6. Purified gas 7 is obtained from the top of absorber 6 and use, for example, on top marvelous needs and from the bottom of the absorber, the saturated COj solution of the absorber 8, after being heated in the heat exchanger 9 with the regenerated solution of MEA 1O from the stripping column 11, is fed to the stripping flask from I. Carbon dioxide 12, saturated with water, is cooled in an air cooler 13 to condense most of its contents water vapor and is directed to the separator 14. The water condensed at the same time 15 is fed to the top of the steam separator 11, and the carbon dioxide 16 separated in the separator 14 com is primed from 0.118 MPa to 2.06 MPa (interim pressure) by the compressor 17 mixed with n flow of crude oil 3, precompressed by compressor 18 to a pressure of 2.06 MPa, and subjected to stream 19 of low-temperature condensation, for which stream 19 is cooled in heat exchanger 20 by reverse flow of liquid carbon dioxide 21 produced in separator 22, then cooled to -ZO 35 ®C in the evaporator of the propane refrigeration machine 23 and sent to separator 22. Dry gas 24 from separator 22 is directed to the flow of petroleum gas 1, and liquid CO2 is pumped to a pressure of 25 to a pressure of 19.6 MPa and pumped into the formation. PRI me R. The feedstock was taken as a crude gas containing 70 vol.% With a volume of 175 million m / year, of the following composition, mole% N22.3; CO2 70 | C 11.30; C 2 7.0; Sz 5,6; ps4 2.6; nCg 2.6; PS 1.2, As an absorbent, an aqueous 70% solution of MEA, wt.%, is used. Oil gas 1 is compressed to a pressure of 0.588 MPa, cooled in air coolers to -t 35 ° C, cleaned of mechanical impurities, divided into two streams — flow 2 (100 million m / year) and flow (375 million). Gas stream 3 is directed to absorption purification using MEA to absorbers 4-6, and gas stream 3 is bypassed. Purified petroleum gas 7 in the amount of 32.3 m / year is used for fuel needs, and a saturated CO2 absorbent 8 in the amount of 430993 kg / h passes through a transfer to 9, where it is partially heated to 90 ° C with regenerated MEA from the stripping column 11 and serve - in the upper part of the stripping column 11. Carbon dioxide 12, leaving the top of the stripping column (desorber) 11 with water vapor 12 is cooled in an air cooler 13 until condensed water is separated into a. the separator 14 and served in the upper part of the Stripping column. Separated CO2 16 is compressed to a pressure of 2.06 MPa, mixed with stream of gas oil 3, precompressed to pressure 2, MPa, cool 1 stream 19 in a 2 O heat exchanger, then in an evaporator 23 to minus and feed into a separator 22. Dry gas 24 and the amount of 23.2 million m / year are mixed with crude petroleum gas 1, and carbon dioxide in liquid form in the amount of 16.6 t / h

Nvosom 25 is heated to a pressure of 19.6 MPa and pumped into the reservoir.

The positive effect of the method is obtained by reducing energy consumption for absorption purification, since not all of the raw gas, but only a fraction (about 42%) is subjected to absorption purification, and due to the fact that the extracted yriiepo a dioxide in the proposed cost

Compression of petroleum gas from 0.118 doO, 588 MPa, kWh

Cooling the groove after komprimirovani, iW .4

Pumping in the cleaning unit, kWh

. Including: IEA regeneration

desorber irrigation

Cooling of regenerated MEA water for irrigation of desorber, kWh

Cooling gas from the second absorber to the third, kWh

Compriming SO l from 0.118 to 19.6 MPa, kWh

Bypass gas charging

This is obtained in liquid form, which will allow it to be injected into the wells up to a pressure of 19.6 MPa by a pump, which requires a small energy expenditure on compression in comparison with compression.

The table shows the comparative cost data for the proposed and known methods. .

Way

Famous I Suggested

696.5

1696.5 51.8 51.8

80.85

141 1.49 1.42

67

38.1

7.2

Claims (2)

3764 Absorption methods for purifying petroleum gas from CO l, in which amines, in particular monoethanolamine (MEA), are used as an absorbent, require large capital expenditures (making expensive column equipment) and, moreover, are very energy-intensive ( due to high heat consumption and high energy consumption for compression of the altered CQg). If in the source (raw) gas the COj content is less than 30%, its absorption is advisable only by absorbing MEA, since it is economically suitable for BBS. If the content of CO 2 in the source gas exceeds 87%, it does not make sense to purify it, since Corresponding to the conditions of CO2 injection into the reservoir, the presence of hydrocarbon gases up to 13–15% is allowed in it. The combination of the MEA process with the process of low-temperature separation (NTS) is advantageous at a definite content in the source gas SO. and carrying out the NTS process in a certain temperature mode with a certain distribution of the source gas between the CI of CO 2 IEA and the NTS. The selected limits on the distribution of the quantities of the source gas by cleaning the MEA and the NTS are the most profitable in terms of energy and capital costs. The proposed method allows to reduce energy costs in general up to 35% and it is acceptable for gas with a high content of carbon dioxide in the source gas. DETAILED DESCRIPTION OF THE INVENTION Claims of separation of carbon dioxide from hydrocarbon mixtures, advantageously under compressor mode of oil production by injection of high pressure carbon dioxide, including the absorption of carbon dioxide by amines from a compressed source mixture with subsequent regeneration of the absorbent and carbon dioxide from it, its compression, differing so that with. In order to reduce energy costs, the initial mixture is divided into two streams, the first of which is up to intermediate pressure, the second is subjected to absorption, then slid down to intermediate pressure, mixed with the first stream and separated into low-temperature separation into a vapor fraction of hydrocarbons and a liquid fraction, and steam fractional returns to the source mixture. Sources of information taken into account during the examination 1. Germany Patent - 2808838, cl. C 1O K 3/04, 1978. 2. Cole A, L, and Rizenfeld F. C, Gas purification. M ,, Himi, 1968, p. 25 (prototype).