CN111662741A

CN111662741A - Transformer capable of reducing sulfur corrosion

Info

Publication number: CN111662741A
Application number: CN202010558535.6A
Authority: CN
Inventors: 刘云
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2020-09-15
Anticipated expiration: 2040-06-18
Also published as: CN111662741B

Abstract

The invention provides a transformer capable of reducing sulfur corrosion, which achieves the effects of high-efficiency and deep desulfurization by adding a novel desulfurizer into transformer oil, and reduces the corrosion of sulfides to transformer parts. The method adopts neurospora crassa and candida utilis to ferment the liquorice waste residue, can degrade partial lignin, cellulose and hemicellulose in the liquorice waste residue, and mycelium of the neurospora crassa and the candida utilis can fully penetrate through the inside of a fermented material to exert a certain physical destruction effect on the fermented material, so that a microscopic cavity is formed in the material. The modified liquorice waste residue has the advantages that the space structure is damaged, the liquorice waste residue is rough and multi-fold, the porosity is high, the specific surface area is increased, and the adsorption performance to sulfide is greatly improved. The invention has the advantages that: the dibenzyl disulfide and the dodecanethiol in the transformer can be adsorbed simultaneously, the adsorption efficiency is over 95 percent, and negative effects on electrical parameters such as breakdown voltage, dielectric loss and resistivity of transformer oil are avoided.

Description

Transformer capable of reducing sulfur corrosion

Technical Field

The invention relates to the field of transformers, in particular to a transformer capable of reducing sulfur corrosion.

Background

The mineral insulating oil used in the current transformer is mainly refined from natural petroleum, and contains 2 main elements of carbon and hydrogen, as well as sulfur, nitrogen, oxygen and metal elements. And sulfur compounds such as mercaptan, disulfide and the like which are active in nature can cause sulfur corrosion problems. Current research indicates that dibenzyldisulfide (abbreviated as DBDS) and dodecanethiol (abbreviated as DDM) are the most predominant corrosive sulfides that cause copper corrosion. The corrosive sulfur reacts with the copper wire to generate cuprous sulfide, and the cuprous sulfide is attached to the surfaces of the insulating paper and the copper winding to reduce the insulating property of the transformer and endanger the safe operation of the transformer.

In the aspect of oil-sulfur corrosion protection, methods such as strict acceptance of new insulating oil, addition of an adsorbent to control sulfur content in oil, addition of a metal passivator and the like are generally adopted in current engineering. The protection mechanism of the metal passivator is to form a similar polymer protective film on the surface through coordination of deprotonated nitrogen atoms and copper so as to prevent corrosion of sulfide to metal. However, the passivating agent is gradually consumed during long-term operation of the equipment, and once consumed, the corrosive sulfur will re-attack the wire.

The method adopts a physical adsorption method, such as adding adsorbents such as activated alumina, a 10X molecular sieve, activated clay and the like to adsorb corrosive sulfur in the insulating oil, can effectively reduce the content of main corrosive sulfides in the insulating oil, and improves the insulating properties of the insulating oil after adsorption treatment, such as copper ion content, acid value, dielectric loss, breakdown voltage and the like. However, the method has the biggest problems of long time required for adsorption treatment, low efficiency and incomplete adsorption of corrosive sulfide.

Disclosure of Invention

The invention aims to provide a transformer capable of reducing sulfur corrosion, which achieves the effects of high-efficiency and deep desulfurization by adding a novel desulfurizer into transformer oil, and reduces the corrosion of sulfides to transformer parts.

The technical scheme adopted by the invention is as follows:

a transformer for reducing sulfur corrosion, comprising: the novel desulfurizer is added into the transformer oil for desulfurization treatment.

The novel desulfurizer is prepared by the following steps:

(1) dissolving propylene glycol methyl ether in chloroform to prepare a propylene glycol methyl ether chloroform solution with the volume fraction of 2-4.5%, uniformly mixing the licorice waste residue and the propylene glycol methyl ether chloroform solution, standing for 24 hours at normal temperature, and drying at 80 ℃ to constant weight to obtain pretreated licorice waste residue;

(2) according to bran: the mass ratio of the pretreated liquorice waste residues is 3: 7, mixing, adding ammonium sulfate and urea, adding water, repeatedly stirring uniformly, controlling the water content of the culture medium to be 56-60%, performing damp-heat sterilization at 0.1MPa for 30min, and cooling to room temperature to obtain a solid culture medium;

(3) inoculating 1-2% Neurospora crassa seed solution in a solid culture medium, fermenting at 30-32 deg.C for 36-48h, inoculating 3-5% Candida utilis seed solution, and continuing to ferment at 30-32 deg.C for 60-72 h;

(4) after the fermentation is finished, taking out the fermentation product, and drying at 45 ℃ until the water content is below 12 percent, thus obtaining the novel desulfurizer.

The licorice waste residue is the residue of licorice after glycyrrhizic acid extraction, and is obtained after air drying, crushing and sieving with a 40-mesh sieve, and the water content is 7% by measurement.

In the step (1), the liquorice waste residue and propylene glycol methyl ether chloroform solution are mixed according to the material-liquid ratio (g/mL) of 1: 1-1.5 mixing.

The dosage of the ammonium sulfate is 2 percent of the total weight of the bran and the pretreated licorice waste residue, and the dosage of the urea is 0.1 percent of the total weight of the bran and the pretreated licorice waste residue;

the spore amount in the Neurospora crassa seed liquid is 5 × 10⁸Per mL;

the Neurospora crassa is Neurospora crassa AS3.1603, which is purchased from Shanghai towering Biotech Co., Ltd.

The spore content in the Candida utilis seed solution is 3.5 × 10⁸Per mL;

the candida utilis is candida utilis CGMCC2.1180 provided by China center for culture collection of microorganisms.

The percentages referred to in the present invention are, unless otherwise specified, mass percentages.

The use method of the novel desulfurizer comprises the following steps: adding the novel desulfurizer into a transformer oil sample needing desulfurization treatment according to 10% of the weight of the oil, stirring for 2 hours at 60-70 ℃, and then filtering the adsorbed oil sample.

The waste residue of licorice contains rich cellulose, hemicellulose, lignin, protein and other high molecular compounds, and the surface of these high molecular compounds contains great amount of active functional groups, such as carboxyl, hydroxyl, amino, etc. But the liquorice waste residue is directly used as an adsorbent or is used for removing sulfides in mineral oil after being modified by acid and alkali, and the adsorption effect is not ideal.

Neurospora crassa (Neurospora crassa) has the ability to secrete cellulase, hemicellulase and ligninase, and grows well under solid state fermentation conditions. The method adopts neurospora crassa and candida utilis to ferment the liquorice waste residue, can degrade partial lignin, cellulose and hemicellulose in the liquorice waste residue, and mycelium of the neurospora crassa and the candida utilis can fully penetrate through the inside of a fermented material to exert a certain physical destruction effect on the fermented material, so that a microscopic cavity is formed in the material. The modified liquorice waste residue has the advantages that the space structure is damaged, the liquorice waste residue is rough and multi-fold, the porosity is high, the specific surface area is increased, and the adsorption performance to sulfide is greatly improved.

In recent years, a number of experts have concluded that DBDS is the main corrosive sulfur in transformer oil, and therefore have focused research on DBDS. However, since the corrosiveness of mercaptan is stronger than that of DBDS, and mercaptan is the most important component in crude oil and new transformer oil in the active sulfur composition, the influence of mercaptan cannot be ignored when researching corrosive sulfur. After the licorice waste residue is fermented by neurospora crassa and candida utilis, part of lignin, cellulose and the like are damaged, protein is exposed, the neurospora crassa and the candida utilis can also produce protein, and the protein can chemically react with dodecyl mercaptan in transformer oil to form chemical adsorption on the dodecyl mercaptan, so that the adsorption efficiency is improved.

The liquorice waste residue is pretreated by propylene glycol methyl ether chloroform solution before fermentation, so that the lignin structure can be changed, hemicellulose solvation and cellulose decrystallization are caused, the pretreated liquorice waste residue is easier to be hydrolyzed by enzyme, the utilization of microorganisms on fermentable substances and the enzymolysis are facilitated, and the degradation efficiency is improved.

The Neurospora crassa inoculated firstly can decompose the waste residue of the liquorice to generate reducing sugar for the utilization of the Candida utilis, the Candida utilis forms various vitamins and growth factors in the growth and metabolism process, and the substances are helpful to enhance the activity of the Neurospora crassa, increase the enzyme production efficiency and promote the enzymolysis of the waste residue of the liquorice.

The invention has the advantages that: the adsorption efficiency is more than 95%, the adsorption time is short, only 2h is needed, the efficiency is high, and no negative influence is caused on the electrical parameters of the transformer oil, such as breakdown voltage, dielectric loss, resistivity and the like.

Detailed Description

Example 1: a transformer for reducing sulfur corrosion, comprising: the novel desulfurizer is added into the transformer oil for desulfurization treatment.

The novel desulfurizer is prepared by the following steps:

(1) dissolving propylene glycol methyl ether in chloroform to prepare a propylene glycol methyl ether chloroform solution with the volume fraction of 3.5%, uniformly mixing the licorice waste residue and the propylene glycol methyl ether chloroform solution, standing for 24 hours at normal temperature, and drying at 80 ℃ to constant weight to obtain pretreated licorice waste residue;

(2) according to bran: the mass ratio of the pretreated liquorice waste residues is 3: 7, mixing, adding ammonium sulfate and urea, adding water, repeatedly stirring uniformly, controlling the water content of the culture medium to be 60%, performing moist heat sterilization at 0.1MPa for 30min, and cooling to room temperature to obtain a solid culture medium;

(3) inoculating 2% Neurospora crassa seed solution into a solid culture medium, fermenting at 32 ℃ for 36h, then inoculating 5% Candida utilis seed solution, and continuing to ferment at 32 ℃ for 60 h;

In the step (1), the liquorice waste residue and propylene glycol methyl ether chloroform solution are mixed according to the material-liquid ratio (g/mL) of 1: 1.2 mixing.

the spore amount in the Neurospora crassa seed liquid is 5 × 10⁸Per mL;

the spore content in the Candida utilis seed solution is 3.5 × 10⁸Per mL;

example 2: a transformer for reducing sulfur corrosion, comprising: the novel desulfurizer is added into the transformer oil for desulfurization treatment.

The novel desulfurizer is prepared by the following steps:

(1) dissolving propylene glycol methyl ether in chloroform to prepare a propylene glycol methyl ether chloroform solution with the volume fraction of 2%, uniformly mixing the licorice waste residue and the propylene glycol methyl ether chloroform solution, standing for 24 hours at normal temperature, and drying at 80 ℃ to constant weight to obtain pretreated licorice waste residue;

(2) according to bran: the mass ratio of the pretreated liquorice waste residues is 3: 7, mixing, adding ammonium sulfate and urea, adding water, repeatedly stirring uniformly, controlling the water content of the culture medium to be 56%, performing damp-heat sterilization at 0.1MPa for 30min, and cooling to room temperature to obtain a solid culture medium;

(3) inoculating 1.5% Neurospora crassa seed solution into a solid culture medium, fermenting at 30 ℃ for 48h, then inoculating 4% Candida utilis seed solution, and continuing to ferment at 30 ℃ for 72 h;

In the step (1), the liquorice waste residue and propylene glycol methyl ether chloroform solution are mixed according to the material-liquid ratio (g/mL) of 1: 1.5 mixing.

The rest is the same as example 1.

Example 3: a transformer for reducing sulfur corrosion, comprising: the novel desulfurizer is added into the transformer oil for desulfurization treatment.

The novel desulfurizer is prepared by the following steps:

(1) dissolving propylene glycol methyl ether in chloroform to prepare a propylene glycol methyl ether chloroform solution with the volume fraction of 4.5%, uniformly mixing the licorice waste residue and the propylene glycol methyl ether chloroform solution, standing for 24 hours at normal temperature, and drying at 80 ℃ to constant weight to obtain pretreated licorice waste residue;

(2) according to bran: the mass ratio of the pretreated liquorice waste residues is 3: 7, mixing, adding ammonium sulfate and urea, adding water, repeatedly stirring uniformly, controlling the water content of the culture medium to be 58%, performing damp-heat sterilization at 0.1MPa for 30min, and cooling to room temperature to obtain a solid culture medium;

(3) inoculating 1% Neurospora crassa seed solution into a solid culture medium, fermenting at 32 ℃ for 36h, then inoculating 3% Candida utilis seed solution, and continuing to ferment at 32 ℃ for 72 h;

In the step (1), the liquorice waste residue and propylene glycol methyl ether chloroform solution are mixed according to the material-liquid ratio (g/mL) of 1: 1 and mixing.

The rest is the same as example 1.

Comparative example 1: compared with example 1, the difference is only that: the licorice waste residue was not pretreated with propylene glycol methyl ether chloroform solution, and the other steps were the same as in example 1.

Comparative example 2: compared with example 1, the difference is only that: the licorice waste residue is fermented only by neurospora crassa, and other steps are the same as example 1. The method comprises the following specific steps:

(3) inoculating 2% Neurospora crassa seed solution into a solid culture medium, and fermenting at 32 ℃ for 96 h;

Evaluation of desulfurizing agent Performance:

200g of corrosive sulfur-containing oil (DBDS content 153.68mg/kg, DDM content 113.45 mg/kg) was added to the desulfurizing agents obtained in examples 1-3 and comparative examples 1-2 in an amount of 10% by weight of the oil, and the mixture was stirred at 65 ℃ for 2 hours. And then filtering the oil sample with good adsorption to obtain the transformer oil subjected to adsorption desulfurization, measuring the DBDS and DDM content in the oil sample subjected to adsorption treatment, and evaluating the performance of the desulfurization adsorbent, wherein the result is shown in Table 1.

TABLE 1 variation of DBDS and DDM content of oil samples before and after adsorption

Group of	Residual concentration of DBDS (mg/kg)	DBDS removal (%)	Residual concentration of DDM (mg/kg)	DDM removal Rate (%)
					Example 1	4.52	97.1	2.41	97.8
Example 2	6.34	95.9	5.52	95.1
					Example 3	7.06	95.4	4.49	96.0
Comparative example 1	58.71	61.8	32.63	71.2
					Comparative example 2	35.90	76.6	53.72	52.6

Claims

1. A transformer for reducing sulfur corrosion, comprising: the novel desulfurizer is added into the transformer oil for desulfurization treatment.

2. The transformer of claim 1, wherein the transformer has reduced sulfur corrosion, and further comprising: the novel desulfurizer is prepared by the following steps:

3. The transformer of claim 2, wherein the transformer has reduced sulfur corrosion, and further comprising: the licorice waste residue is the residue of licorice after glycyrrhizic acid extraction, and is obtained after air drying, crushing and sieving with a 40-mesh sieve, and the water content is 7% by measurement.

4. The transformer of claim 2, wherein the transformer has reduced sulfur corrosion, and further comprising: in the step (1), the liquorice waste residue and propylene glycol methyl ether chloroform solution are mixed according to the material-liquid ratio (g/mL) of 1: 1-1.5 mixing.

5. The transformer of claim 2, wherein the transformer has reduced sulfur corrosion, and further comprising: the dosage of the ammonium sulfate is 2 percent of the total weight of the bran and the pretreated licorice waste residue, and the dosage of the urea is 0.1 percent of the total weight of the bran and the pretreated licorice waste residue.

6. The transformer of claim 2, wherein the amount of spores in the Neurospora crassa seed solution is 5 × 10⁸one/mL.

7. The transformer of claim 2, wherein the Candida utilis seed solution has a spore content of 3.5 × 10⁸one/mL.

8. The transformer of claim 2, wherein the transformer has reduced sulfur corrosion, and further comprising: the novel desulfurizer is prepared by the following steps:

(4) after fermentation, taking out the fermentation product, and drying at 45 ℃ until the water content is below 12 percent to obtain the novel desulfurizer;