JPS6090295A - Corrosion protection of furfural extraction apparatus - Google Patents

Abstract

PURPOSE:To suppress the corrosion of an apparatus for the extraction of aromatic component of a mineral oil with furfural, and to prevent the loss of furfural, by adding an antioxidant to the furfural. CONSTITUTION:The corrosion of a part of a furfural extraction apparatus between the atmospheric flushing column 6 and the pressure flushing column 7 can be prevented by injecting an antioxidant solution 11 with a pump, etc. into the mixture of an extraction oil and furfural extracted from the bottom of the extraction column 1. The injection is carried out before the mixture is heated and introduced into the column 6. The amount of the injected antioxidant solution is preferably <=1ppm based on the mixture of the extraction oil and furfural.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of a furfural extraction device that extracts aromatic components from mineral oil using furfural.

Furfural has a large dissolving power for aromatic components in mineral oils and is highly selective.1 For example, it is used in solvent refining of lubricating oils to extract and remove aromatic components from lubricating oil fractions.
It is widely used for extraction and removal of its low aromatic components.

However, furfural is highly reactive, particularly thermally unstable, and easily decomposes or polymerizes. This decomposition or polymerization of furfural not only causes loss of furfural, but also produces aldehydes, organic acids, etc., leading to corrosion of the equipment.

For this reason, conventionally, the acid substance was neutralized and removed by injecting an alkaline substance (for example, an aqueous solution of sodium carbonate) to prevent corrosion of the K-washing device.

However, the neutralization method using an alkaline substance cannot be used in an evaporation recovery system because furfural precipitates during evaporation recovery and clogs tubes such as heat exchangers.

As a result of intensive studies to solve this problem, the inventor of the present invention found that by adding an antioxidant to furfural, corrosion of the equipment can be significantly suppressed, and loss of furfural can also be significantly prevented. I found it.

The present invention was made based on this knowledge.

An object of the present invention is to provide an excellent method for preventing corrosion of a furfural extraction device, and also to propose a method for preventing loss of furfural.

That is, 1 the present invention is a method for preventing corrosion of a furfural extractor for extracting aromatic components in mineral oil using furfural, in which an antioxidant is added to the furfural, and the addition of the antioxidant is DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, which is a method for corrosion protection of a furfural extractor having at least 1 ppm of furfural in a mixture of extracted oil and furfural, is described in detail below.

The present invention is a method for extracting aromatic components from mineral oil using furfural, and in particular removes aromatic components from a vacuum distillation fraction of crude oil or deasphalted oil from a vacuum distillation residue, and has excellent stability. Suitable for furfural extraction loading used in the production of lubricant base oils.

Antioxidants are those that dissolve in furfural, and those that give hydrogen atoms from their active centers to peroxide radicals to stop the chain reaction and prevent the progress of oxidation reactions, and those that prevent oxidation by decomposing peroxides. There are compounds that prevent this. The former compounds include 2,6-tert-butyl-4-methylphenol, 2,6-cymethyl-6-tert-butylphenol, and 2.6-tert-butylphenol.
Phenolic compounds such as tert-butylphenol and bisphenol A, and N,N'-diisopropyl-P-phenylenediamine, N,N'-G 5ec
There are amine compounds such as -butyl-P-phenylenediamine. As the latter compounds, Zn-dialkyl dithiocarbamates, dialkyl sulfides, dialkyl selenides, etc. are known. In the present invention, these antioxidants can be used alone or in combination of two or more.

There is no problem in adding antioxidants to furfural, but if the mineral oil and furfural are contacted and extracted, the mixture of extracted oil and furfural, i.e. furfural is heated in a furfural recovery system. Preferably, it is added by injection before recovery.

It is preferable to add the antioxidant in an amount of at least 1 ppm to the mixture of extracted oil and furfural, and if it is less than this, a sufficient effect of preventing corrosion and preventing loss of furfural cannot be expected. . On the other hand, the amount added.

The effect increases as the amount increases, but 1% or less is preferable for economic reasons.

An example in which the present invention is applied to a lubricating oil refining device, which is a furfural extraction device, will be described below with reference to the drawings.

In the figure, 1 is the extraction tower, and the lower part contains mineral oil, i.e., the lubricating oil fraction 2.
is introduced, and furfural 3 recovered in a furfural dehydration tower 4, which will be described later, is introduced into the upper part, and aromatic components in the lubricating oil fraction are extracted. Rough rice after extraction) tJ:,
The raffinate is extracted from the upper part of the extraction column 1, a small amount of furfural is removed from the upper part by a raffinate stripper 5, and a raffinate as a product is obtained from the lower part.

On the other hand, the mixture of extracted oil and furfural extracted in the extraction tower 2 is extracted from the lower part of the extraction tower 1.

It is heated and first introduced into the atmospheric pressure flash tower 6. Then, it is further heated and introduced into the pressurized flash tower 7.

The furfural recovered in these flash towers 6.7 is dehydrated in a furfural dehydration tower 4, taken out from the bottom, and circulated to the extraction tower 1.

On the other hand, extracted oil is recovered from the lower part of the pressurized flash tower 7, residual furfural is removed by an extract stripper 8, and extracted oil is recovered from the lower part.

Raffinate stripper5. Furfural 1 containing water recovered from the extract stripper 8 and the upper part of the furfural dehydration tower.

It is separated into a water layer and a furfural layer by OBM 419, and the furfural layer is introduced into a furfural dehydration tank, and the water layer is introduced into IJ tube 10, where the remaining phenol is recovered.

In such a furfural extraction device.

In particular, corrosion is likely to occur between the normal pressure flash tower 6 and the pressurized flash tower 7. Therefore, in order to effectively prevent this corrosion, it is preferable to inject the antioxidant 11 before the mixture of extracted oil and furfural extracted from the lower part of the extraction column is heated. Since the antioxidant 11 is generally solid at room temperature, it is preferable to dissolve or disperse it in a suitable solvent, such as a special solvent, or in furfural, and inject it with a pump. The amount of injection is such that the antioxidant is at least 1 ppm of the extracted oil and furfural mixture.

The injected antioxidant acts on the furfural denatured by the addition of Rl'sK before it is introduced into the atmospheric flash tower 6, stops the denaturation chain reaction of furfural, suppresses the formation of corrosive substances, and suppresses the formation of furfural. Prevent mistakes.

The present invention as described above has the effect of preventing corrosion of the furfural extraction device and suppressing the loss of furfural.

The effects of the present invention will be described below using Examples and Comparative Examples.

Examples 1-6. Comparative Example: Extracted oil from heavy oilseed oil fraction (normal pressure equivalent boiling point: 430 to 590°C) [specific gravity (15/4°C) 1.02. Viscosity (100℃)
34Jcst, remaining coal 4. s wt%) to 15 wt
% and furfural 85 wt% K antioxidant were added respectively to an autoclave, and carbon steel (JIE + standard 5TB 35.15m x 15mm x
240
It was kept at a temperature of 3°C for 3°. After cooling, the degree of erosion was measured from the weight loss of the test piece. Further, the loss area of furfural was measured by gas chromatography.

These results are shown in Table 1.

As is clear from the results in Table 1, 1 ppm of antioxidant
It can be seen that the above addition can significantly suppress corrosion of carbon steel or alloy steel and prevent loss of furfural.

Example 7 Equipment capacity: 9000 BPSD 2.6-G ter from 11 in the diagram in the lubricating oil solvent purification equipment as shown in the diagram.
The reactor was operated for one year with 1 ppm of t-butyl-4-methylphenol added to the mixture of extracted oil and furfural. As a result, the normal pressure flash tower 6 and the pressurized flash tower 7
When the tubes of the heat exchange tower located between the tubes were inspected, it was found that the wall thickness and occurrence of pitting had decreased by a large IJ compared to the previous year when no antioxidant was added.

[Brief explanation of drawings]

The figure shows a lubricating oil solvent purification device which is an example of a furfural extraction device to which the present invention is applied. In the figure, 1 is an extraction column, 6 is a normal pressure flash column, and 7 is a pressurized flash column.

Claims (2)

[Claims] (1) A corrosion prevention method for a furfural extraction device that extracts aromatic components in mineral oil using furfural, the method comprising adding an antioxidant to the furfural. (2) A method for preventing corrosion of a furfural extraction device according to claim 1, characterized in that the amount of antioxidant added to the mixture of extracted oil and furfural is at least 1 ppm.