CS201308B1 - Method for inhibiting corrosion of metallic materials in high temperature acid medium - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for inhibiting corrosion of high temperature metal materials, particularly metal apparatuses for the hydrolysis treatment of polysaccharide, protein, lignocellulosic or the like materials, or mixtures thereof, to monomeric or other products thereof. 5

A method of inhibiting metal corrosion is known, based on the use of mixed inhibitors composed of a plurality of components, the preparation of which is complex and costly to produce.

Especially reactors in the chemical industry, especially the hydrolysis apparatus, are usually made of corrosion resistant alloys which contain a high proportion of expensive alloying? metals are very expensive.

Therefore, for some less demanding equipment and tanks, they are made of commercially available alloys and provided with protective coatings, coatings or enamels, which, however, are fragile and easily damaged.

Another way is to protect the devices against corrosion by making them made of metal-clad ceramic materials, which is introduced in some hydrolysis apparatuses, but it has the disadvantages of the difficult and highly laborious manufacture of especially small apparatuses.

SUMMARY OF THE INVENTION It is an object of the present invention to provide such a method of inhibiting corrosion of metallic materials against the action of acids, in particular apparatuses operating at elevated temperatures, which is effective, simple and unpretentious.

SUMMARY OF THE INVENTION The invention is based on the addition of an excrement and / or a hydrolyzate thereof to the acidic aggressive environment prior to its contact with and / or during contact with the metal material.

A further characteristic is that the additive of the excrements is their dry matter, or that the additive of the hydrolyzate is its concentrate.

According to the invention, the excrement additive is further composed of manure or liquid manure of livestock, preferably pig manure.

The invention can be achieved at a very low cost very effectively by inhibiting the corrosion of metallic materials in an acidic aggressive high temperature environment, particularly in the hydrolysis of polysaccharides such as straw, paper, bark and the like to produce monosaccharides. ·

It is also possible to effectively protect against corrosion even metal parts or whole metal devices at lower temperatures, below the conditions required for hydrolysis, by applying the already produced hydrolyzate.

Specific examples will be described below which show the high corrosion inhibitory effect of metallic materials when using the method of the invention over the method without using the invention. The composition of these materials is shown in Table 1.

Table 1 - composition of materials

Material Material _Titanium I II steel

C% 0.10 0.15 0.12 maximum Cr% 17.5 19 to 22 17.0—20.0 Ni% 12.5 36 to 40 8.0—11.0 Mp% 2.25 4.5 to 6.5 Ti% 0.0 0.0 99.5 0.45 Mn% - 1.5 maximum 2.0 Si% 1.3 maximum 1.0 Example 1

In a flow-through hydrolyser of anticorrosive material I, 10% dry waste paper is hydrolyzed at 180 ° C in the presence of 1% w / w sulfuric acid, ie the weight of acid per volume of mass in the hydrolyzer.

The machine operates 24 hours a day for 5 days a week.

Under these conditions, a decrease in hydrolyzer material of 1.248 mg was found. cm ' ² . hr ¹ , which represents a loss of 9.36 mm of the wall thickness of the hydrolyser coming into contact with the dyhrolyzed material over a period of 1 year.

Example 2

Under the conditions of Example 1, concentrated or dried pig slurry is added to the hydrolyzed material so that the resulting hydrolyzed dry matter is 10% dry paper and 10% slurry dry.

With a substantial increase in the production of monosaccharides of about 40%, the corrosion inhibiting effect of this process reduces 1.8 X 10 ⁴ times, i.e. to 0.000071 mg cm ^-2 . hr ^-1 , so that the annual wall loss of the hydrolyzer is reduced to 0.00052 mm compared to Example 1; is therefore negligible.

Example 3

In a stationary hydrolyzer made of conventional structural steel, see Table 1, carbohydrate livestock feed is produced by hydrolyzing straw or bark at 130 ° C in the presence of sulfuric acid and a concentration of 1% w / w and a reaction time of 3 hours. The wall of the hydrolyser is not protected by expensive paint, which is resistant to the above mentioned conditions.

Example 4

Under the conditions of Example 3, 20% of the concentrated hydrolyzate is added to the hydrolyzed material. slurry with a dry matter content of.

The annual loss of the unprotected inner wall of the hydrolyzer will decrease under these conditions

1,8. 105 times, ie to 0.0002 mm, so it is virtually negligible and eliminates the need for special and costly coatings.

Table 2

Material HCl % Corrosive environment h ₂ so ₄ % Exkrem. % Temperature Noc: 2 ° C Reaction pH Material loss mg.cm ^-2 h ^-1 Mark the curves in the graph 0.0 1 0.0 20 May 2.4 0.01 70 0.11 103 0.75 130 1.47 1 190 1.62 230 1.70 AND 0.0 1.3 98.7 120 2,0 0.00 190 0.05 2 230 0.09 0.0 2,0 98.0 120 1.4 0.00 190 0.15 3 230 0.22 0.2 0,5 0,0 0.0 100 ALIGN! -. 0.00 1.0 130 0.00 4 190 0.00 HER 0.0 1 0.0 100 ALIGN! 2.4 0.00 130 0.03 190 0.30 1 230 0.47 0.0 1.3 98.7 120 2,0 0.00 190 0.00 2 230 0.08

Table continuation

Material HCl % Corrosive environment H ₂ SO ₄ % Exkrem. % Temperature Noc: 2 ° C Reaction pH Material loss mg.cm 'hr ^-1 Mark the curves in the graph II 0.0 2,0 98.0 120 1.4 0.00 190 0.03 3 230 0.15 0.2 0,5 0,0 0.0 100 ALIGN! 0.00 1.0 130 0.00 4 190 0.00 Titanium 0.0 1.0 0.0 100 ALIGN! 2.4 0.10 130 0.40 190 0.66 1 230 0.76 0.0 1.3 98.7 130 2,0 0.00 190 0.00 2 230 0.05 0.0 2,0 98.0 120 1.4 0.00 190 0.03 3 230 0.10 0.2 0,5 0,0 0.0 100 ALIGN! _ 0.00 l.o 130 0.00 4 190 0.00

The results of the measurement of the corrosion inhibition efficiency of material I, II and titanium with and without the use of hydrolyzed manure in the environment of different concentrated acids as a function of temperature are summarized in Table 2.

Corrosion of the materials listed in Table 2 as a function of temperature is shown in the graph in the attached drawing.

Corrosion inhibition efficiency versus sulfuric acid concentration at 180 ° C was measured in the presence of both distilled water and distilled water with addition of 10 wt. % dry matter of pig slurry, which is current for hydrolysis apparatuses. The results are summarized in Table 3.

Table 3 Inhibition of corrosion by excrement at 180 ° C

Material Concentration H ₂ SO <% Decrease material distilled water mg.cm ^-1 . ¹ hour of distilled water + 10 wt% dry matter of pig slurry Reduction AND . 0.5 0,3337187 0.0000244 1,4.10 ¹ 1.0 1,2481606 0.0000710 1,8.10 ¹ 2,0 1,5845070 0.0000695 2,3.10 ¹ II 0.5 0,0321130 0.0000611 5,3.10 ² 1.0 0,0931278 0.0000575 1,6.10 ³ 2,0 0,0979448 0,0000672 1,5.10 ³ Titanium 0.5 0,0253165 0.0000354 0,7.10 ³ 1.0 0,0675105 0,0000464 1,5.10 ³ 2,0 0,1919831 0,0000401 4,8.10 » Common 0.5 10,8510000 0.0001021 4,2.10 ³ kon- 1.0 34.8638920 0.0001942 1,8.10 ³ stoikění 2,0 41,6473190 0.0001822 2,6.10 " steel

From these measurements it is obvious that the addition of pig slurry will find its application especially where its hydrolysis is possible without relationship or negatively affecting the processed material, ie in the hydrolysis of polysaccharide materials such as straw, paper and bark for the production of monosaccharides either for fermentation or other treatment. All the water used to dilute the acids used can then be replaced by liquid pig manure, which will also bring considerable benefits in terms of environmental protection.

Hydrolysate of pig slurry, whether in its original diluted concentration or in a possible concentration, will find application in the protection of metal parts and equipment at lower temperatures, below the temperatures required for its hydrolysis, for example industrial or other coolers, liquid heating systems and others.

As can be seen from the above examples, in order to achieve a very effective protection of the corrosion-reducing material, depending on the material used, the less resistant the material is by three to five orders of magnitude, it is necessary to use an additive corresponding to 10% dry pig manure.

It is also conceivable to apply the hydrolyzate slurry to the walls of the metal apparatus to be protected for a short period of time, i.e. only for a time sufficient to achieve the desired corrosion inhibition for a certain period of time and to repeat the procedure before that time.

Claims (5)

SUBJECT OF THE INVENTION Method for inhibiting corrosion of metallic materials in an acidic aggressive medium of high temperature, in particular of metal apparatuses for the hydrolysis treatment of polysaccharide, protein, lignocellulosic and other materials, or mixtures thereof, to monomeric or other products thereof, characterized in that by contact with the metallic material and / or during the contact, the addition of excrement and / or its hydrolyzate is added. 2. Method according to claim 1, characterized in that the admixture of the excrements is formed by their desserts. . 3. Process according to claim 1, characterized in that the additive of hydrolyzates of the manure is a concentrate thereof. 4. A method according to claim 1, wherein the additive is formed to go or liquid manure of livestock. 5. A method according to claims 1 to 3, characterized in that pig manure is used as excrement.