JPH05137918A - Cleaning liquid and cleaning method using the same - Google Patents

Abstract

PURPOSE:To provide a cleaning liq. for a filter element having both a drastic cleaning effect and a corrosion preventing effect on a metallic material. CONSTITUTION:An org. corrosion inhibitor is added to nitric acid to obtain a cleaning liq. having both a cleaning effect by the strong acid and a corrosion inhibiting effect and a blocked filter element is cleaned by immersion in the cleaning liq. Blocking matter hard to remove by the conventional method can efficiently be removed and scale in a chemical device as well as in a filter device is very effectively removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning liquid for removing clogging of filtering elements such as lubricating oil and fuel oil, and particularly notch wire elements, and a cleaning method using the same.

[0002]

2. Description of the Related Art In chemical devices such as filters and heat exchangers, solids and the like contained in fluids to be handled gradually accumulate to form scales, and their removal is always a problem. Especially in the case of notch wire elements used for filtering oils,
Silica, iron, calcium, magnesium, carbon in oil,
Fine particles of compounds such as aluminum and sodium get caught and clogged, resulting in poor passage of the fluid. Therefore, many methods of backwashing with a filtrate have been proposed in order to remove the clogging.

[0003]

However, it is difficult to completely remove the clogging in the method by backwashing, and it is often necessary to repeat it frequently on a regular basis. Moreover, there is a problem that the valuable filtrate is consumed. In particular, when filtering low-quality heavy oil, etc., a large amount of inorganic substances adhered, and it was very difficult to remove the clogging of the element due to such substances. Therefore, various attempts have been made on a method of radically washing the clogging with another solvent, but the compound causing the clogging is not usually dissolved in water or an organic solvent. In addition, inorganic strong acids or strong alkalis or hydrofluoric acid are all deleterious substances, and there are obstacles such as severe corrosion of element materials. Is not commercially available. The present invention has been made based on such a background, and provides a cleaning solution which has a drastic cleaning effect and also has an anticorrosive effect on a metal material, which is satisfactory on both sides, and a cleaning method using the cleaning solution. The purpose is to

[0004]

[Means for Solving the Problems] The present invention for achieving the above object is a cleaning liquid for a filter element, characterized in that an organic corrosion inhibitor is added to nitric acid. As the nitric acid used in the cleaning liquid of the present invention, commercially available dilute nitric acid can be applied. The concentration of nitric acid is not particularly limited, but usually, 68 wt% (azeotrope with water) or 50 wt% of a commercially available product or the like can be conveniently used.

The corrosion inhibitor used in the cleaning liquid of the present invention is an organic corrosion inhibitor. Among them, organic adsorption corrosion inhibitors are particularly preferable. Typical examples are amines, surfactants, etc. The mechanism of action is that an inhibitor having a polar group and a hydrophobic group is adsorbed on the metal surface at the polar group part and at the hydrophobic group part. It prevents corrosion by interfering with the movement of substances involved in the corrosion reaction. This adsorptive inhibitor has a characteristic of exhibiting a good anticorrosive action in an acidic liquid.

The amount of the organic corrosion inhibitor added to nitric acid is 0.1 to 10 g based on 50% by weight nitric acid.
/ Liter, preferably 0.2 to 5 g / liter. If the amount of the inhibitor added is less than 0.1 g / liter, the anticorrosion effect is low, and if it exceeds 10 g / liter, the nitric acid has a negative effect on the cleaning action, and the balance between the cleaning effect and the anticorrosion effect is impaired. ..

Next, a cleaning method using the cleaning liquid of the present invention will be described. As for the cleaning method, the object to be cleaned such as the clogged notch wire element is removed and immersed in the cleaning liquid. The concentration of the cleaning liquid can be arbitrarily selected depending on the state of adhered substances such as clogging of the cleaning target. If a cleaning solution prepared by adding a predetermined amount of an organic corrosion inhibitor to 50% nitric acid is used as a stock solution, it is usually preferable to use it after diluting it 5 to 10 times with tap water. When the stock solution is diluted with water, water may be added to the stock solution, or the stock solution may be added to water. Of course, it is also possible to use the undiluted solution as it is. The immersion time is preferably about 10 to 20 minutes, although it depends on the concentration of the cleaning liquid. When the dilution of the cleaning liquid exceeds 10 times, the concentration becomes low and the immersion is required for a long time, which lowers the work efficiency, which is not preferable.

In the above cleaning method, the oil and sludge adhering to the object to be cleaned are immersed in a cleaning liquid such as light oil having a low cetane number and a solvent such as 1,1,1-trichloroethane before being immersed in the cleaning liquid. It is desirable to wash it off thoroughly. Also, the object to be cleaned that has been taken out after being immersed in the cleaning solution is thoroughly washed off with warm water or tap water, and compressed air of about 3 to 5 kgf / cm ² is blown to the object to be cleaned that is still wet to remove water and to remove the notch. It is necessary to blow away the solid material having a softened surface remaining in the spaces or the recessed portions. In this case, it is more effective to blow the compressed air while illuminating the object to be cleaned with a small fluorescent lamp or the like, since the degree of cleaning can be easily understood. In addition, when washing an object to be washed taken out from the above washing liquid with warm water or tap water, it is extremely effective to remove residual solids by adding a neutral detergent to a concentration of about 1% and applying ultrasonic waves. is there.

[0009]

EXAMPLES Next, the present invention will be described more specifically by way of examples. Example 1 A cleaning solution was prepared by adding 13.2 g of an organic adsorptive corrosion inhibitor to 20 liters of commercially available 50% nitric acid, and the cleaning solution was diluted 2.5 times, 5 times, and 10 times with tap water. A cleaning solution was prepared. On the other hand, as an object to be cleaned, a notch wire element (25μ
m) About 8 oils, sludge, etc. adhering to each other, after thoroughly washing off with 1,1,1-trichloroethane as a solvent, the above-mentioned 4 including the stock solution prepared
The seed cleaning solution was immersed at 14.5 ° C. for 10 minutes and 20 minutes, respectively. Then take out each element, wash the washing solution thoroughly with tap water, and then illuminate with a small fluorescent lamp for 5k.
Residual solids were blown off by blowing compressed air of gf / cm ² and dried. These eight washed notch wires
The result of measuring the cleanliness of the element is shown in FIG. According to this example, the method of diluting the cleaning solution about 10 times and immersing for about 20 minutes is the most effective and economical. As shown in FIG. 4, the measuring method of the cleanliness is as follows:
Is made blind, tap water is injected from the upper hole 2, the water amount is adjusted so that the water level is fixed to the upper end of the upper metal fitting of the element 1, and the injected water amount is measured with a measuring cup, and the reference unit amount m ³
/ H. Then, the standard unit amount m ³ / h in the new element was taken as the cleanliness of 100%, and the cleanliness of the cleaning element was converted and expressed as each cleanliness%.
However, the following hypothesis was established for the measurement of this cleanliness. The openings of the elements are uniform. The head pressure from the tap was ignored.

Example 2 Notch wire element 3 having different pollution levels
For the seeds, the cleanliness (%) as a result of immersing the seeds in the same procedure as in Example 1 for 20 minutes in a 10-fold diluted cleaning solution and cleaning the seeds is shown in FIG.
It was shown to.

Example 3 A clogged contaminated notch wire element was immersed for 10 minutes in a dilute cleaning solution having a nitric acid concentration of 33%, and then ultrasonically cleaned in a neutral detergent solution (concentration of 1%) for 30 minutes. As a result, the filtration amount was 4.4 times that before washing.

EXAMPLE 4 Prior to washing the contaminated notch wire element that had been clogged, it was heated in an electric furnace at 250 ° C. for 2 hours and then washed in the same manner as in Example 3. The amount was 21.8 times, showing a marked improvement. Although the cleaning liquid of the present invention is strongly acidic, there is no problem in cleaning stainless steel, aluminum, etc. due to the effect of adding a corrosion inhibitor. However, caution is required for solder as it has corrosive properties as shown in FIG. FIG. 3 is a diagram showing the results of measuring the corrosion weight loss of a solder sample when immersed in a 5% cleaning solution at 13.0 ° C. for 10 minutes and 20 minutes.

Other Precautions for Handling the Cleaning Solution of the Present Invention (1) Since it is strongly acidic, be careful when handling it, especially wear glasses and acid-resistant gloves. (2) The stock solution and the diluted solution do not deteriorate even after long-term storage, and can be used repeatedly until the acidity is lost. (3) Since the added corrosion inhibitor tends to settle, be sure to thoroughly stir the liquid before using it before using it. (4) When disposing as used waste liquid, neutralize with alkali such as caustic soda before disposal.

[0014]

By using the cleaning liquid of the present invention,
It becomes possible to remove the clogging of the notch wire element, which has been difficult in the past, of the filtration device, and the recovery effect of the filtration capacity is great. Moreover, the cleaning liquid is effective not only in the filtering device but also in other chemical devices such as the removal of scale of the heat exchanger, and the usage area is gradually expanding.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the dilution ratio of a cleaning liquid of the present invention-the immersion time and the cleanliness of an object to be cleaned.

FIG. 2 is a diagram showing a comparison of cleanliness of washed elements.

FIG. 3 is a diagram showing corrosiveness to solder.

FIG. 4 is an explanatory view of an element cleanliness measurement method.

[Explanation of symbols]

 1 Notch wire element 2 Tap water inlet (inlet / outlet of liquid) 3 Hole for fixing the center axis of the notch wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C01B 21/38 7305-4G

Claims (2)

[Claims] 1. A cleaning liquid for a filtering element, wherein an organic corrosion inhibitor is added to nitric acid. 2. A method for cleaning a filter element, which comprises immersing the filter element in a cleaning liquid containing nitric acid and an organic corrosion inhibitor.