DD138780B1 - METHOD FOR THE MICROBIOLOGICAL DEHYDRATION OF PETROLEUM AND PETROLEUM FRACTIONS - Google Patents

Description

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Field of application of the invention

The invention relates to a process for the desulfurization of petroleum and petroleum fractions using desulfurizing anaerobic microorganisms.

Characteristic of the known technical solutions

Petroleum and petroleum fractions have more or less extensive admixtures of undesirable compounds on _f such as organic sulfur compounds.

With the use of petroleum and petroleum fractions, these substances are corrosive, lead to high air pollution by sulfur dioxide and reduce the activity of petroleum refining catalysts and petrochemicals.

Usually, the removal of the unwanted petroleum sulfur compounds by hydrocatalytic desulfurization takes place at high temperatures and high pressure.

However, the cost of such procedures is currently limited. very considerable and the methods used are not universally applicable to all petroleum fractions.

Further, methods for aerobic and anaerobic (USP No. 2641564) microbiological desulfurization are known.

According to the cited patent specification, a hydrogenation of the organic sulfur compounds is carried out by microbiological means with exclusion of air, wherein the hydrogen required for this purpose is microbially obtained within the reaction systems. This requires such reaction vessels that can accommodate at least the nutrient solutions necessary for two different bacterial species in such a way that no mutual influences occur. The fermentors consist of several divided by partitions reaction chambers.

For the microbiological desulphurization of petroleum hydrocarbons, the following reaction conditions are given:

a temperature range of 25-75 ° C, a pH of 6.5 to 7.5 and a pressure range of 1 to 300 at, preferably at 10 at.

The activity of the microorganisms used is increased by additions of complex growth regulators. The microbial degradation of petroleum hydrocarbons is limited by the addition of diverters such as carbohydrates. As conversion products of organic petroleum sulfur compounds formed in addition to hydrogen sulfide small amounts of sulfides and organic acids. The fermenters used, made of high-quality pressure-resistant material, contain built-in partitions or membranes, which are reliable at the specified pressure values.

The described fermentors with porous partitions are ineffective in petroleum and certain petroleum fractions, as by bonding the pores, the metabolic activity of microorganisms is affected, the reactions of the microbial metabolism - hydrogen generation and desulfurization - are hindered and thus the degree of desulfurization is reduced.

Due to insufficient turbulence in the fermentors, the mass transfer is unfavorable and consequently only low desulfurization rates could be achieved even at high residence times.

Object of the invention

The aim of the invention is to obtain low-sulfur or sulfur-free petroleum or petroleum fractions by an anaerobic microbiological desulfurization, which is technically and economically superior to the hitherto known anaerobic processes by technical improvements and more favorable reaction.

Explanation of the essence of the invention

The implementation of the previously known method for anaerobic desulfurization of petroleum hydrocarbons is fraught with defects such. B. unfavorable mass transfer, use of at least 2 bacteria species, low desulfurization, which have a decisive influence on the economy of the process.

The object of the invention is to develop an economically advantageous continuous process for anaerobic microbiological desulfurization of petroleum and petroleum fractions by technical improvement, targeted strain selection and more favorable fermentation conditions.

According to the invention, the anaerobic desulfurization is carried out such that petroleum or petroleum fractions are emulsified so finely with a non-ionic, non-sulfur surfactant, the aqueous nutrient medium, the water and the active Desulfuriziererkultur that a quasi-homogeneous distribution of the products in the aqueous culture medium is produced and maintained throughout the fermentation time. As a result, the physiological performance of the desulfurization culture is increased and a high mass transfer rate is achieved, which makes it possible to achieve high levels of desulfurization at short residence times.

The continuous, operated at atmospheric pressure fermentation is carried out in process engineering simple fermentors without porous partitions, with a favorable for the reaction of the microbial metabolism turbulence can be generated.

The hydrogen necessary for the anaerobic fermentation is supplied to the fermentor from the outside as a technically produced gas. The microorganisms separated by fermentation after separation are partially or completely returned to the fermentor in a physiologically active state, so that a cell density of greater than 10 ⁹ cells / ml is always maintained.

According to the invention, the control of the continuous anaerobic fermentation is carried out using a simply composed aqueous nutrient medium by maintaining an rH ₂ value in the range from 1.7 to 7.0, preferably from 3.0 to 6.0, and a redox potential with a Value from -20OmV to -45OmV - preferably at -285mV-.

The microorganism culture used consists of obligate anaerobic, gram-negative bacteria of the genus Desulfovibrio.

Due to the fermentation conditions used, in addition to the desulfurization of the petroleum sulfur compounds, partial hydrogenation of the unsaturated compounds present in the products takes place.

The ratio of petroleum or petroleum fraction to aqueous nutrient medium can be varied in the range of 10-40 to 90-60.

With residence times of 2-4 days, desulphurisation efficiencies over 50% can be achieved.

embodiments

The process according to the invention is explained in more detail with reference to the following examples:

example 1

The system for carrying out the method is shown in FIG.

In an under normal pressure, normal temperature, at a pH of 7.0 continuously operating Anaerobicfermentor2 is a mixture of 1 an emulsion of petroleum 23, aqueous nutrient medium, with the addition of a non-ionic, sulfur-containing surfactant of the type polyethylene propylene adduct21 and generated a portion of the required water.

Due to the composition of the aqueous nutrient medium, a concentration of 0.70 kg of ammonium chloride

1,40kg Magnesium Chloride.6 Hydrate

0,70kg sodium sulphate

2.10kg sodium lactate

0.40kg of potassium hydrogen phosphate

per cubic meter of aqueous fermentation medium in Anaerobicfermentor 2 maintained.

The ratio of petroleum to aqueous nutrient medium is 40 to 60. The turbulence necessary for the reaction is achieved by withdrawing a portion of the fermentation medium from the Anaerobicfermentor 2 via line 3, after passage through pump 5, the required hydrogen is injected via line 7 , passes to the entry point 6 and the anaerobic fermentor 2 is supplied again. The supplied liquid-gas jet contains the necessary hydrogen in finely divided form. Via line 4, physiologically active microorganisms from the separation stage 10 are returned to the anaerobic fermentor 2.

The fermentation conditions which are most favorable for the bacterial culture used and the high desulphurisation power to be achieved are achieved by setting the control and regulating device 8 to a redox potential of -285 mV.

The microorganisms used, whose isolation was carried out by known methods, were used as mixed culture, consisting mainly of Gram-negative obligate anaerobic bacteria of the species Desulfovibrio desulfuricans used.

Via line 9 leaves the multicomponent system microorganism / aqueous nutrient medium / desulfurized oil the Anaerobicfermentor 2 and enters the separation stage 1Ö, where optionally with or without demulsifier, the aqueous nutrient medium and the still physiologically active microorganisms are separated from the desulfurized product, which then via line 12 reaches the storage tank 14.

The resulting in the separation stage 10 aqueous microorganism suspension is concentrated via line 11 through the separator 13 and fed the physiologically active bacterial suspension via line 4 to the Anaerobicfermentor 2.

The process wastewater leaving the separator 13 via line 15 passes into the wastewater treatment.

The forming fermenter exhaust gas leaves via line 16 the Anaerobicfermentor 2 and enters the gas separation plant, where unreacted hydrogen is separated from the exhaust gas and is used again.

The low-hydrogen waste gas is fed to the gas desulphurisation plant 18, in which hydrogen sulphide and other sulfur-containing gas constituents, such as sulphides or multicaptans, are separated from the fermenter waste gas. The conversion of the gaseous sulfur compounds into elemental sulfur takes place in the sulfur recovery plant 19. The thus purified exhaust gas is fed to a combustion unit 20.

Under these fermentation conditions, the petroleum used could be desulphurized to 65% with a residence time of 2 days.

Example 2

According to the technology described in Example 1, petroleum is subjected to anaerobic desulfurization under the following reaction conditions:

Use of an aqueous nutrient medium of the following composition (based on m ^{3 of} fermentation medium)

0.70 kg NH ₄ Cl], 00 kg Na ₂ SO ₄ 1.40 kg MgSO ₄ -6 H ₂ O 3.00 kg sodium lactate 0.40 kg K ₂ H PO ₄

- Normal temperature, normal pressure

- Ratio of petroleum to aqueous nutrient medium 40:60

- pH 8.0

- Redox Potential -200mV

The mixed culture consisted mainly of obligate anaerobic bacteria of the species Oesulfovibrio vulgaris. The isolation of the microorganisms was carried out by known microbiological methods.

Under these fermentation conditions, the petroleum used could be desulphurized to 50% with a residence time of 3 days.

Example 3

In the plant described in Example 1, crude oil is anaerobically desulphurized under the following conditions:

Composition of the nutrient solution analogously to Example 2 plus 500 g of yeast extract per m ^{3 of} fermentation medium

- pH in the fermentation medium 9.0

- Redox Potential-400 mV

- normal pressure, normal temperature

- Ratio of petroleum to aqueous nutrient medium 40:60

The used mixed culture, isolation according to the known microbiological methods, consisted mainly of desulphuricants of the species Desulfovibrio desulfuricans and Desulfovibrio vulgaris.

By maintaining a residence time of 55 hours, a desulphurisation capacity of 60% could be achieved.

Claims (1)

Invention claim: Process for the microbiological desulphurisation of petroleum and petroleum fractions using desulphurizing anaerobic bacteria and addition of non-ionic, non-sulfuric surfactants in a continuous fermentation operating under normal temperature, normal pressure and at a pH of 6.5-9.0, characterized by that oil or petroleum fractions are emulsified with aqueous nutrient medium in the ratio of 10-40 to 90-60 with gassing with technical hydrogen, that a redox potential of -200 mV to -450 mV is maintained and that to maintain a cell density of greater 10 ⁹ cells / ml the microorganisms in a physiologically active state in a known manner after separation into the anaerobic fermenter be recycled.