WO2014072033A1

WO2014072033A1 - Method and device for obtaining synthesis gas from a residual gas containing hydrocarbons

Info

Publication number: WO2014072033A1
Application number: PCT/EP2013/003258
Authority: WO
Inventors: Jürgen GLASER; Albrecht Heinzel
Original assignee: Linde Aktiengesellschaft
Priority date: 2012-11-08
Filing date: 2013-10-29
Publication date: 2014-05-15
Also published as: DE102012021837A1

Abstract

The invention relates to a method and a device for obtaining synthesis gas (11) from a mixture (1) containing higher boiling point hydrocarbons which is compressed (V) and separated into a process condensate (13) predominantly comprising higher boiling point hydrocarbons and a compressed gas flow (3) which preponderantly contains low boiling point hydrocarbons and is subsequently reacted in a reactor (POX reactor) (P) by partial oxidation, wherein a crude synthesis gas (6) containing soot and flowing out of the POX reactor is subjected to water scrubbing (Q) in which an effluent (7) containing soot is generated. The invention is characterized in that at least a part of the process condensate (13) is mixed with the effluent (7) containing the soot to absorb the soot and separate it from the effluent (7).

Description

description

Process and apparatus for obtaining synthesis gas from a

Hydrocarbon-containing residual gas

The invention relates to a process for the production of synthesis gas from a substance mixture containing higher boiling hydrocarbons, which is compressed and present in a predominantly higher-boiling hydrocarbons

Process condensate and a compressed gas stream is separated, which consists mainly of low-boiling hydrocarbons and is subsequently reacted in a reactor (POX reactor) by partial oxidation, wherein a soot from the POX reactor effluent synthesis gas is subjected to a water scrubbing in which a soot-containing Wastewater arises.

Furthermore, the invention relates to a device for carrying out the

inventive method.

In the present document are to be understood by higher boiling hydrocarbons of carbon and hydrogen existing compounds in

Standard conditions exist as a liquid, while low-boiling

Hydrocarbons are gaseous under standard conditions.

Carbon monoxide and / or hydrogen-containing gas mixtures, so-called synthesis gases, are important starting materials for the production of a large number of products, such as

Ammonia, methanol or even synthetic fuels. One method widely used in industry for producing synthesis gases in synthesis gas plants from hydrocarbons is partial oxidation (POX). Here, a hydrocarbon-containing use in a reactor (POX reactor) at temperatures between 1 300 and 1 500 ° C and pressures up to 150 bar with water vapor and an oxidizing agent to a synthesis crude reacted, which consists to a large extent of hydrogen, carbon monoxide, carbon dioxide and Water exists. The heat required for the reaction is generated by incomplete (partial) oxidation of the hydrocarbons in use. For this purpose, the POX reactor oxygen is added in an amount that is not sufficient for a complete conversion of the hydrocarbons. At partial oxidation besides gaseous components also arise

Solids such as soot and ash or slag, which must be removed from the syngas before it can be treated further. That with one

Temperature of more than 1 300 ° C from the POX reactor emerging synthesis crude is first cooled and then subjected to a water wash. If the cooling of the synthesis raw gas in direct contact with water (quenching), so in this process step, a large part of the solids from the

Washed out synthesis gas and passes into the water used for quenching. In the water wash a fine cleaning, in which the solids content of Syntheserohgases is typically reduced to about 1 mg / m ³ .

The soot removed from the synthesis gas represents a valuable raw material, which is why it is separated from the wastewater produced by quenching and / or water scrubbing and fed to a material and / or energetic use.

It makes sense for the soot to be recycled as an insert into the POX reactor and converted there to carbon monoxide. The costs incurred for separating soot from the wastewater have a decisive influence on the economy of the entire partial oxidation process.

In order to use the resulting in the partial oxidation of carbon soot, according to the prior art, the loaded with soot wastewater with naphtha to a

Dispersion mixed. The soot, which is much better wetted by naphtha than by water, passes almost completely into the naphthaphase. The dispersion is then introduced into a decanter in which it separates into a soot-containing naphtha fraction and a substantially soot-free water fraction. The soot-containing naphtha fraction is withdrawn from the decanter and recycled as feed into the POX reactor, while the largely soot-free water fraction is for the most part returned to the quench water loop; a small part is delivered to a wastewater treatment plant.

The partial oxidation is suitable for the recovery of hydrocarbon-rich wastes or residues whose material use is otherwise impossible or only possible with great effort, and which can therefore be obtained inexpensively. As an example of a cost-effective substance that is suitable for synthesis gas production by means of Partial oxidation is suitable, here is called a residual gas from the oil shale processing. The oil shale is pyrolyzed in a retort process, wherein

arise hydrocarbon-rich pyrolysis gases, which are then cooled. In this case, a liquid phase consisting of hydrocarbons is separated, which is a synthetic crude oil. What remains is a retort residual gas, which consists to a large extent of short-chain hydrocarbons (essentially C ^ to C ₁₀ ), but also impurities such. As carbon dioxide, hydrogen sulfide, carbon dioxide sulfide or nitrogen. When compacting such a Retorte- residual gas to the required for a partial oxidation pressure higher boiling hydrocarbons condense, so that a predominantly of higher boiling hydrocarbons (C ₄ to C ₀₎ existing process condensate and a

Gas phase arise in which the vast majority of low-boiling

Hydrocarbons is included. According to the prior art, the

Process condensate introduced together with the gas phase in the POX reactor to be implemented there. The retort residual gas is significantly less expensive than naphtha, so that soot recovery using naphtha would negatively impact the economics of syngas production.

Object of the present invention is therefore to provide a method and an apparatus of the type described above, which are suitable to overcome the described disadvantages of the prior art.

This object is achieved procedurally according to the invention that at least a portion of the process condensate is mixed with the soot-containing wastewater to absorb soot and separate from the wastewater.

By means of the process according to the invention, the amount of naphtha required for soot removal can at least be reduced in comparison with the prior art; at best, it is possible to completely dispense with the use of expensive naphtha. The amount of naphtha savings depends on the quantity and the quality of the process condensate. For example, if the process condensate has a chemical composition equivalent to that of naphtha and precipitates in an amount sufficient to remove soot, naphtha can be completely replaced with process condensate. If the chemical composition of the process condensate deviates so much from that of naphtha that it alone is not suitable for the Rußabtrennung is usable, a mixture of process condensate and naphtha can be used, which has a limited naphtha requirement. Preferably, not used for the removal of soot

Process condensate fed directly to the POX reactor as an insert.

It makes sense to load the process condensate laden with soot or the soot-laden hydrocarbon fraction formed from process condensate and naphtha and introduce it as an insert into the POX reactor, thereby achieving a substantially complete utilization of the substance mixture containing higher boiling hydrocarbons.

Process condensates which consist essentially of hydrocarbons having 4 to 10 carbon atoms and have a boiling range between 35 ° C. and 180 ° C. at atmospheric pressure are particularly suitable for carrying out the process according to the invention. Such compositions are found in process condensates resulting from the compression of retort residual gases resulting from oil shale processing. It is therefore proposed that a retort residual gas be used as a substance mixture containing higher boiling hydrocarbons and the process condensate obtained therefrom be used as a medium for the separation of soot from soot-containing wastewater.

Furthermore, the invention relates to a device for obtaining synthesis gas from a mixture containing higher boiling hydrocarbons, with a reactor for carrying out a partial oxidation (POX reactor), a

Compressor upstream of the POX reactor for compressing the higher-boiling hydrocarbons-containing mixture, a separator arranged downstream of the compressor for the separation of process condensate obtained during compression, and a decanter arranged downstream of the POX reactor for separating soot from soot-laden wastewater.

This object is achieved according to the device device according to the invention in that the separator is connected to the decanter in such a way that process condensate can be mixed with soot-laden wastewater and introduced into the decanter. In order to use carbon black and hydrocarbons from the decanter material, the decanter is preferably connected to the POX reactor so that a soot-laden hydrocarbon fraction from the decanter can be introduced into the POX reactor.

In the following, the invention will be explained in more detail with reference to an exemplary embodiment shown schematically in FIG.

FIG. 1 shows a detail of a device in which synthesis gas is produced from a retort residual gas with the aid of a POX reactor.

Via line 1, a retort residual gas containing higher boiling hydrocarbons is fed to the compressor V, where it is compressed to a pressure which is sufficiently high to be able to introduce it into the POX reactor P. the

Compressor V is followed by a separator A, in which the compressed stream 2 is introduced to condensed in the compression components, which are predominantly higher-boiling hydrocarbons, as

Separate process condensate, so that a largely consisting of low-boiling hydrocarbons gas stream 3 can be fed to the POX reactor P as an application to together with water vapor 4 and oxygen to 5

Synthesis gas to be implemented. The synthesis gas withdrawn via line 6 from the POX reactor P at a temperature of typically more than 1300 ° C. is quenched by water in the quench device Q, wherein at the same time most of the entrained soot and ash particles are washed out and transferred to a first wastewater stream 7 becomes. For fine cleaning, the only coarsely purified synthesis gas 8 is forwarded from the quench device Q in the water wash W, are removed in the remaining soot and ash particles by means of fresh water 12 from the gas, so that a washed, largely soot and ash-free synthesis crude 9 and a with small amounts of soot and ash laden second waste stream 10 arise. During the loaded with soot traces

Wastewater stream 10 in the quench device Q serves as quench water, the synthesis crude gas stream 9, which consists mainly of carbon dioxide, carbon monoxide and hydrogen, processed in the separator T to the synthesis gas 1 1. To separate off the soot, the first waste water stream 7 with process condensate 13, which is supplied from the separator A, is mixed to form a dispersion 14, which is then introduced into the decanter D, where they are in soot-laden

Process condensate 15 and a largely soot-free water fraction 16 separates. The soot-laden process condensate 15 is withdrawn from the decanter and returned as a feed into the POX reactor P, while the largely soot-free water fraction 16 is discharged to a wastewater treatment plant (not shown).

Claims

claims

Process for the recovery of synthesis gas (11) from a mixture of substances (1) containing higher boiling hydrocarbons, which compresses (V) and is present in a predominantly higher-boiling hydrocarbon

Process condensate (13) and a compressed gas stream (2) is separated, which consists predominantly of low-boiling hydrocarbons and is subsequently reacted in a reactor (POX reactor) (P) by partial oxidation, wherein a soot from the POX reactor effluent synthesis crude (6) a water wash (Q) is subjected, in which a soot - containing wastewater (7) is formed, characterized in that at least a portion of the

Process condensate (13) with the soot-containing wastewater (7) is mixed to receive soot and separated from the wastewater (7).

A method according to claim 1, characterized in that the laden with soot process condensate (15) is recycled and introduced as an insert in the POX reactor (P).

Method according to one of claims 1 or 2, characterized in that the process condensate (13) consists essentially of hydrocarbons having 4 to 10 carbon atoms and at atmospheric pressure has a boiling range between 35 ° C and 180 ° C.

Method according to one of claims 1 to 3, characterized in that it is in the higher-boiling hydrocarbons-containing mixture (1) is a retort residual gas from the oil shale preparation.

Apparatus for recovering synthesis gas (11) from a substance mixture (1) containing higher boiling hydrocarbons, comprising a reactor (P) for carrying out a partial oxidation (POX reactor), a compressor (V) arranged upstream of the POX reactor for compressing the gas higher-boiling hydrocarbon-containing substance mixture (1), a downstream of the compressor (V) arranged separator (A) for separating accumulating in the compression process condensate (13) and a downstream of the POX reactor (P) arranged decanter (D) for the separation of Soot from soot-laden wastewater (7), characterized in that the separator (A) is connected to the decanter (D) such that process condensate (13) with soaked wastewater (7) can be mixed and introduced into the decanter (D).

Apparatus according to claim 5, characterized in that the decanter (D) with the POX reactor (P) is connected such that a soot-laden

Hydrocarbon fraction (15) from the decanter (D) in the POX reactor (P) can be initiated.