DE2606098A1 - MECHANICAL PROCESS FOR DEWATERING THE SOOT FROM OIL GASIFICATION - Google Patents

Description

260609 ?!

A3CH21656

Mechanical process for dewatering the soot produced during oil gasification,

Akzo GmbH Wuppertal

Incomplete combustion of heavy oils with gases containing oxygen is known to produce a carbon monoxide and Synthesis gas containing hydrogen and soot as a solid residue. Well-known methods of oil gasification include the Shell and the Texaco process. These methods are for example in Hydrocarbon Processing "Volume 46, No. 11 (The 1967 Petrochemical Handbook Issue), Nov. 1967, page 227, in Engineering Chemistry, Vol. 48, No. 7, pp. 1118-1122, in British Patents 734,475 and 780,120 and U.S. Pat. No. 2,914,418 described.

The call generated by these known methods has a specific surface area of 600 to 1500 ία ² / g (determined according to BET), a micropore volume of 0.8 to 4 ml / g (measured according to the N. method), a macropore volume of 1 , 5 to 5 ml / g (measured with the Hg porosimeter) and an oil absorption of 2 to 6 ml / g. It is usually washed out of the gas mixture using water. This gives an aqueous suspension with a carbon black content of 0.3 to 4 percent by weight, usually water and carbon black are then separated from one another, on the one hand to circulate or discharge the water, on the other hand to obtain the soot, which is known to have valuable properties and, for example used as an absorbent «can be grounded. For the general aries RuA

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ORIGINAL INSPECTED

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initially from water to something immiscible with water Solvent, for example on toluene or on a mineral oil, in order to agglomerate. After removing the Water, the agglomerate is separated by evaporating the solvent. Such methods are described in GB-PS 741 135, for example. You are re the risk of fire, the risk of a solvent explosion and with regard to the usual solvent losses disadvantageous. A further disadvantage of this method is that the necessary effective washing of the agglomerate cannot be carried out without it Difficulties can be integrated into the overall process. In addition, these processes are associated with high investments and operating costs.

Since no better method of separating soot has been available up to now, attempts have been made to reduce the dangers and solvent losses of the known processes as far as possible. The literature suggests the carbon black suspension e.g. to thicken by sedimentation, centrifugation or filtration su a paste with 6 to 10 weight percent * This is but only when using comparatively large amounts of additives possible (see NL-OS 7 203 Ο46). The paste should then be granulated and by evaporating the water, for example in a hot air stream, further drying. A disadvantage of this method is that the energy consumption is very high. Apart from that It is very difficult to obtain an aqueous suspension of rufis by sedimentation, centrifugation or filtration, pressureless or under Thicken pressure to a satisfactory soot content. This is especially true in the case of soot with BET overflowing at least 600 »/ g.

The present invention relates to a method by which the aqueous carbon black suspension is thickened in a mechanical manner, for example up to a »carbon black content in the range from 12 to 25 percent by weight. Here, in carbon black concentrate, the

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processed in a known manner into the usual molded products can be.

The present invention relates to the process described below for separating water from a aqueous carbon black suspension and the thickened carbon black / water mixture obtainable by this process.

The method according to the invention is characterized in that that the mixture, consisting essentially of water and soot, is dynamically pressed out with the aid of a belt filter press, the filter belts between which the soot / water mixture is located located / deflected several times by at least 90 ° per revolution 'T7 © rdsn and at least one of the straps is permeable to water is. The bands are preferably deflected 3 to 50 times, in particular 5 to 20 times.

Here, under dynamic wringing, there is a procedure understood, in which the soot particles are moved so that they are under the influence of differently directed shear forces Take ateta alternating positions in relation to one another.

The usual filter presses used for some other purposes are for the dewatering of aqueous ones Soot suspensions not suitable. Screw presses, for example twin screw presses, have proven themselves in the practice of soot dewatering also not proven. Although this achieves a satisfactory thickening with a short operating time, However, there is a risk that the close-meshed wall screens will clog within a short time. They have to be fine-meshed Wall sieves should therefore be used so that the required for thickening up to the desired soot concentration is found in the screw press high pressure can build up.

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Before the aqueous soot suspension according to the invention Process is concentrated, it can be subjected to a pretreatment. However, this is generally not necessary. A possible pretreatment is flocculation followed by Decanting and / or filtering “for example using a vacuum filter, centrifuge, or decanter. If desired, can the pretreatment and the method according to the invention in one and the same device.

The carbon black suspensions to be thickened by the process according to the invention are generally 0.2 to 10 percent by weight, preferably 0.5 to 5 percent by weight. At these concentrations, the suspensions are liquid or pasty.

One advantage of the method according to the invention is that the carbon black mass discharged from the press is so consistent that it can easily be granulated or otherwise shaped. It is also advantageous that the granules obtainable have sufficient dimensional stability so that they can be transported mechanically and dried in a dryer with stationary or moving items to be dried, without deforming or caking. The granules obtainable in this way are moreover so dimensionally stable that they can be used directly as a shaped carbon black mass without further treatment. The inventive method is also advantageous in that can be cleaned than the available · carbon black concentrate if desired, in a simple manner, before, during or after the dynamic pressing. In addition, the method according to the invention offers the advantage that no additives such as binders or flocculants have to be added to the soot suspension to be dewatered . Finally, a significant advantage of the method according to the invention also exists in terms of energy savings, since the soot soup is two to four times more concentrated

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is than in the known method and consequently less water has to be evaporated.

Example _}

A 2 percent strength by weight aqueous carbon black suspension obtained from the partial oxidation of Bunker C oil was dewatered. The carbon black of the suspension had a BET surface area of 950 m / g, a micropore volume (N ₂ method) of 1/8 ml / g, a macropore volume (Hg porosimeter) of 3.2 ml / g and an oil absorption of 3 , 2 ml / g.

The carbon black suspension described above was fed to a belt filter press (Bellmer-Winkle press) in an amount of 600 liters per hour. The filter belts loaded with the suspension were deflected four times by 180 ° and twice by 145 ° per revolution. There were 75 kg per hour of a carbon black / water mass having a carbon black concentration of 16 weight percent and 525 liters almost obtained soot-free water. The granular carbon black obtained after complete drying did not differ from the carbon black used in terms of porosity and specific surface area. The belt filter press was operated for 300 days without difficulty «

Comparative example 1

The 2 percent by weight aqueous carbon black suspension described above was poured into a continuously operating 4000 g disc puree. treated. The soot concentration of the suspension could only be increased to 3.3 percent by weight.

Comparative example 2

The 2 percent by weight aqueous carbon black suspension described above was fed into a twin screw press (manufactured by Fa. Stord-Bartz, Bergen, Norway). The carbon black suspension obtained Although it had a carbon black concentration of 12 percent by weight

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on, but the press was clogged after only one hour of operation and had to be shut down.

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Claims (4)

2 606 093 - 7 - A3CH21656 Patent claims: 1) Process for separating water from a mixture consisting essentially of carbon black and water / thereby characterized in that the mixture is pressed out dynamically with the aid of a belt filter press, the filter belts, between which the soot / water mixture is located, depending Be deflected several times by at least 90 ° and at least one of the bands is permeable to water. 2) Method according to claim 1, characterized in that the belts are deflected 3 to 50 times. 3) Method according to claim 1, characterized in that the bands are deflected 5 to 20 times. 4) carbon black / water mixture, characterized in that it is obtained by the method of claims 1 to 3. 609836/0844 ORtQiNAl, INSPECTED