DE102007040092A1 - Process and apparatus for producing synthesis gas from heavy oil - Google Patents

Abstract

The invention relates to a method and a device for generating a carbon monoxide and hydrogen-containing gas (synthesis gas) (6) by partial oxidation of a higher boiling hydrocarbons (heavy oil) (11) containing insert (1) in a gasification device (POX reactor) (R ) and the cooling and washing (W) of the gasification product (4) obtained in the POX reactor (R), wastewater (5) laden with soot being mixed with naphtha (7) and then introduced into a separating device (D), from which a substantially soot-free water fraction (10) and an anhydrous naphtha / soot mixture (9) are withdrawn separately. The anhydrous naphtha / carbon black mixture (9) is fed together with heavy oil (11) to the POX reactor (R) as an insert.

Description

The The invention relates to a process for producing a carbon monoxide and hydrogen-containing gas (synthesis gas) by partial Oxidation of a higher boiling hydrocarbons containing (heavy oil) in a gasification device (POX reactor) and the cooling and Laundry in the POX reactor obtained gasification product, with accumulating laden with soot Wastewater mixed with naphtha and then into a separator is initiated, from a largely soot-free water fraction and a anhydrous naphtha / soot mixture be deducted separately.

Farther the invention relates to a device for carrying out the Process.

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. A process widely used in industry for producing synthesis gases or their precursors from hydrocarbons in synthesis gas plants is partial oxidation. Here is an i.Allg. preheated hydrocarbonaceous use in a reactor (POX reactor) at temperatures between 1300 and 1500 ° C and pressures up to 100 bar with steam and an oxidizing agent converted to a gasification product, which consists to a large extent of hydrogen (H ₂ ), carbon monoxide (CO) , Carbon dioxide (CO ₂ ) and water. The heat required for the reaction is generated by incomplete (partial) oxidation of the hydrocarbons in use. For this purpose, the POX reactor is supplied with oxygen in an amount which is insufficient for complete conversion of the hydrocarbons.

In the case of partial oxidation, in addition to gaseous components, solids such as soot and ash, which must be removed from the gasification product before it can be further processed, are formed. The gasification product leaving the POX reactor at a temperature of more than 1300 ° C. is first cooled according to the prior art and then subjected to a water wash. If the cooling takes place in direct contact with water (quenching), a large part of the solids is already washed out of the gasification product in this process step and passes into the water used for quenching (quench water). In the water wash a fine cleaning is carried out, in which a synthesis gas is produced, which has a solids content, which is typically below 1 mg / m ³ .

Of the soot removed from the gasification product provides a valuable raw material which is why it is made by quenching and / or water washing Wastewater separated and a material and / or energetic Utilization supplied becomes. It makes sense to use soot as an insert in the POX reactor returned and converted there to carbon monoxide. The economy of the use of soot depends decisively of how much the effort for the separation of the carbon black from the wastewater and, if necessary, its treatment to a feedstock is.

In a synthesis gas plant, in the heavy oil by partial oxidation is gasified (heavy oil POX), According to the state of the art, soot-laden wastewater is treated with naphtha mixed into a dispersion. While the predominant Part of the ash contained in the wastewater remains in the water phase, the soot goes, which is wetted by naphtha much better than by water, almost Completely into the naphthaphase. The dispersion is subsequently introduced into a decanter in which it contains a soot Naphtha fraction and a largely soot-free water fraction separates. That compared to heavy fuel oil expensive naphtha is recovered and again for the soot removal used.

To recover the naphtha, the soot-containing naphtha fraction is first withdrawn from the decanter and mixed with heavy oil. From the mixture of substances thus produced, the naphtha is subsequently separated by distillation and stripping. The remaining mixture of heavy oil and carbon black is diluted with fresh heavy oil and recycled as an insert into the reactor of the heavy oil POX. The soot-free water fraction from the decanter is depressurized, with light hydrocarbons dissolved in the water going into the gas phase. Both these light hydrocarbons and the distilled and stripped naphtha are liquefied by cooling, stored and later re-mixed with soot laden wastewater. Because of the large expenditure on equipment and energy, this process is only used in large plants (> 50,000 m _N ³ / h synthesis gas).

If naphtha is available as a hydrocarbon-containing feed, even smaller amounts of synthesis gas can be produced economically by partial oxidation in a so-called naphtha POX. Although here, as in a heavy oil POX, soot laden with wastewater, from which according to the prior art, the soot is separated and recycled as an insert in the POX reactor, but the cost of Rußrückführung is much lower than in a heavy oil POX. Also in a naphtha POX is the state of the Tech nik produced from the soot-laden wastewater and naphtha a dispersion which is introduced into a decanter and there separated into a soot-containing naphtha fraction and a largely soot-free water fraction. However, the naphtha fraction containing carbon black withdrawn from the decanter is then recycled as an insert into the reactor of the naphtha POX without further treatment, while the soot-free water fraction is discharged to a wastewater treatment plant.

The prices for Naphtha and heavy oil have been developing more and more for several years, so it gets harder and harder to get through smaller amounts of syngas the gasification of naphtha at economically reasonable cost to create.

task The present invention is therefore a method of the preamble and a device for carrying out the method, which allow synthesis gas from operations containing heavy oil more economically to produce, as is possible in the prior art.

The asked task is the method according to the invention thereby solved, that the anhydrous naphtha / carbon black mixture the POX reactor is fed together with heavy oil as an insert.

The Profitability of the process of the invention depends decisively from the height of Naphtha content in the hydrocarbon-containing feed to the POX reactor from. The less expensive naphtha over the anhydrous naphtha / carbon black mixture is introduced into the hydrocarbonaceous insert, the more higher the proportion of cheaper heavy oil are. A preferred Embodiment of the method according to the invention provides, therefore, for soot removal the soot laden with soot only with the process-technically required minimum amount of naphtha to mix. Under the process technically required minimum quantity naphtha is to be understood as the naphthenge which is straight sufficient soot in the largely soot-free Water fraction up to a maximum permissible residual concentration, the typically less than 200 ppm by weight, to be reduced.

Around the soot separation from the soot containing Wastewater even with fluctuating operating conditions always with the process technology To be able to perform required minimum amount of naphtha, sees an embodiment the method according to the invention before that naphtha with regulated mass flow into the mixing device is introduced, the setpoint (the process technically required Minimum quantity for a current operating state) for the naphtha stream from the amount and soot loading of the mixer supplied laden with soot Waste water, including the process-relevant values continuously be measured.

Farther The invention relates to a device for generating a carbon monoxide and hydrogen-containing gas (synthesis gas) comprising a Gasification device (POX reactor) for obtaining a gasification product by partial oxidation of a higher-boiling hydrocarbons (Heavy oil) containing insert, a means for cooling and washing of recoverable in the POX reactor Gasification product, a first mixing device for mixing in the syngas production accumulating, soot-laden wastewater with naphtha and a separator for separating the in the first mixing device producible dispersion in a largely soot-free water fraction and a anhydrous naphtha / soot mixture.

the device side the object is achieved in that it has a second mixing device includes, in the heavy oil and the naphtha / carbon black mixture produced in the separator can be introduced and containing a heavy oil, naphtha and carbon black Mixture is deductible as an insert to the POX reactor.

A advantageous development of the device according to the invention provides the separator is a decanter.

Around even with fluctuating operating conditions the naphtha always with the for the soot separation from the soot laden Wastewater required minimum amount of mixing device to supply can, includes the device according to the invention expedient manner a control device, via that of the mixing device always for the Rußabtrennung from the laden with soot Wastewater of heavy oil POX required minimum amount of naphtha can be supplied.

The Invention is particularly suitable for use in existing synthesis gas plants, in which a synthesis gas is produced by partial oxidation of naphtha Naphtha is used to a large extent, the expensive feedstock to replace it with considerably cheaper heavy oil. A more elaborate Rebuilding the plant is not necessary for this, since already existing Plant components practically unchanged can be used further.

In the following, the invention will be explained in more detail with reference to an embodiment schematically illustrated in the figure, in which from higher-boiling hydrocarbons by partial oxidation synthesis gas cooling and scrubbing with water, a synthesis gas containing hydrogen and carbon monoxide is produced.

About the line 1 For example, the POX reactor R is a higher-boiling hydrocarbon-containing use 1 fed with oxygen 2 and water vapor 3 by partial oxidation to a mainly hydrogen and carbon monoxide, but also containing soot gasification product 4 is implemented. In the cooling and washing device W, the gasification product 4 cooled and freed from soot, with a soot laden with soot 5 and the soot-free synthesis gas 6 be generated. The soot laden with soot 5 is then introduced into the mixing device M1 and with naphtha 7 , which is supplied at the same time volume controlled via the control element a, mixed into a dispersion. The soot from the sewage, which is much better wetted by naphtha than by water, passes into the naphthaphase, while in the sewage 5 contained ash in the water phase remains. The mixing device M1 is always supplied only the minimum amount of naphtha, which is required to bring the soot content in the water phase below a predetermined limit. Via wire 8th the dispersion is withdrawn from the mixing device M1 and introduced into the separator D. If the separating device D is a decanter, then after a residence time of typically 2 to 5 minutes from the top of the decanter a largely anhydrous naphtha / carbon black mixture is produced 9 and over its bottom a largely soot-free water fraction 10 deducted. The naphtha / soot mixture 9 is returned before the POX reactor R, in the mixing device M2 with heavy oil 11 mixed and over wire 1 , as part of the insert, fed to the POX reactor R.

Claims (5)

Process for producing a carbon monoxide and hydrogen-containing gas (synthesis gas) ( 6 ) by partial oxidation of a higher-boiling hydrocarbon (heavy oil) ( 11 ) containing insert ( 1 ) in a gasification device (POX reactor) (R) and the cooling and washing (W) of the gasification product obtained in the POX reactor (R) ( 4 ), whereby accumulating, loaded with soot wastewater ( 5 ) with naphtha ( 7 ) and then introduced into a separating device (D) from which a largely soot-free water fraction ( 10 ) and an anhydrous naphtha / carbon black mixture ( 9 ) are separated, characterized in that the anhydrous naphtha / carbon black mixture ( 9 ) together with heavy oil ( 11 ) is fed to the POX reactor (R) as an insert. A method according to claim 1, characterized in that the Rußabtrennung loaded with soot wastewater ( 5 ) with the process-technically required minimum amount of naphtha ( 7 ) is mixed. Device for producing a carbon monoxide and hydrogen-containing gas (synthesis gas) ( 6 ), comprising a gasification device (POX reactor) (R) for obtaining a gasification product ( 4 ) by partial oxidation of a higher-boiling hydrocarbon (heavy oil) ( 11 ) containing insert ( 1 ), means (W) for cooling and scrubbing the gasification product obtainable in the POX reactor (R) ( 4 ), a mixing device (M1) for mixing soot laden wastewater in the production of synthesis gas ( 5 ) with naphtha ( 7 ) and a separating device (D) for separating the dispersion (M1) which can be produced in the mixing device (M1) 8th ) into a largely soot-free water fraction ( 10 ) and an anhydrous naphtha / carbon black mixture ( 9 ), characterized in that it comprises a second mixing device (M2) into which heavy oil ( 11 ) and the naphtha / carbon black mixture produced in the separating device (D) ( 9 ) and from the substance mixture containing a heavy oil, naphtha and carbon black as an insert ( 1 ) is removable to the POX reactor. Device according to claim 3, characterized in that the separator (D) is a decanter. Device according to one of claims 3 or 4, characterized in that it comprises a control device, via which the mixing device (M1) always only the soot removal from the soot-laden wastewater ( 5 ) required minimum amount of naphtha ( 7 ) can be fed.