Industrial cleaning classification

Fineness requirement

General industrial cleaning, precision industrial cleaning, ultra-precision industrial cleaning

1. General industrial cleaning includes the cleaning of the surface of vehicles, ships and aircraft, which can only remove the coarse dirt;

2. Precision industrial cleaning includes the cleaning of various products during processing, the cleaning of various materials and equipment surfaces, etc., which is characterized by the removal of small dirt particles;

3. Ultra-precision industrial fine washing includes ultra-precision cleaning of mechanical parts, electronic components, optical components, etc., in the process of precision industrial production, in order to eliminate extremely small dirt particles.

Cleaning method

Physical cleaning and chemical cleaning

1. Physical cleaning is the use of mechanics, acoustics, optics, electricity, thermal principles, relying on external energy, such as mechanical friction, ultrasonic, negative pressure, high pressure, impact, ultraviolet light, steam and other cleaning methods to remove dirt on the surface of the object without changing the pollution components. That is, the method does not change the original chemical molecular composition.

① Mechanical cleaning method: cleaner and scraper cleaning method, drill pipe cleaning method, shot peening cleaning method.

② Hydraulic cleaning method: low pressure hydraulic cleaning (low pressure cleaning pressure is 196-686 kpa, about 2-7 kg force/square centimeter, equal to 0.2-0.7Mpa).

③ High pressure hydraulic cleaning: The pressure of high pressure cleaning is 4900 kpa, about 50 kg force/square centimeter, equal to 5Mpa. This method is also called high pressure water jet method, high pressure cleaning machine.

2. Chemical cleaning is a method that relies on the action of chemical reactions and uses chemicals or other solvents to remove dirt on the surface of objects. Such as the use of a variety of inorganic or organic acids to remove rust on the surface of the object, scale, oxidizer to remove the surface of the object stains and so on. The use of chemical agents to make the surface pollution or covering layer (such as scale layer) chemical reaction with it to be removed, such as pickling of scale layer, alkali washing, etc. In order to make the substrate not corroded in chemical cleaning or to control the corrosion rate within the allowable range, an appropriate amount of corrosion inhibitors and additives that play the role of activation, penetration and wetting are usually added to the chemical cleaning solution. Methods: Soaking method, circulation method, running cleaning method is also called chemical cleaning method without stopping.

3. The principle of electronic cleaning anti-scaling and descaling is: the use of high-frequency electric field to change the molecular structure of water, so that it is anti-scaling and descaling. When water passes through a high-frequency electric field, its molecular physical structure changes, the original association chain macromolecule breaks into a single water molecule, the positive and negative ions of salt in water are surrounded by a single water molecule, the movement speed is reduced, the number of effective collisions is reduced, the electrostatic attraction is reduced, and the structure on the heated wall tube surface is unable to achieve the purpose of scale prevention. At the same time, due to the increase of the dipole moment of the water molecule, the absorption ability of the water molecule with the positive and negative ions of the salt (scale molecule) increases, so that the scale on the heating surface or the pipe wall becomes soft and easy to fall off, resulting in the effect of scaling.

4. Electrostatic scale prevention and descaling are the same as electronic scale removal, and the purpose of scale prevention and descaling is achieved by changing the state of water molecules. Only the latter uses the action of electrostatic fields, rather than the action of electrons. The mechanism is that water molecules have polarity (also called dipoles), and when the water dipoles pass through the electrostatic field, each water dipole will be sequentially arranged in a positive or negative order. If the water contains dissolved salts, its positive and negative ions will be surrounded by water dipoles, and are also arranged in the water dipole group in a positive and negative order, and can not move themselves, so they can not be near the tube (device) wall, and then deposited on the tube (device) wall to form scale. At the same time, the oxygen released by the water can produce an extremely thin oxide layer on the tube wall, which can prevent the corrosion of the tube (device) wall.

Cleaning medium

Wet cleaning and dry cleaning

Generally, cleaning in the liquid medium is called wet cleaning, and most traditional cleaning methods are wet cleaning.

2. Cleaning in the gas medium is called dry cleaning, such as laser cleaning, ultraviolet cleaning, plasma cleaning, dry ice cleaning, etc., corrosion inhibitor is in the corrosive medium, adding a small amount of a substance, can greatly reduce the corrosion rate of metal, this substance is called corrosion inhibitor. This method of protecting metals is called corrosion inhibitor protection.

Classification of corrosion inhibitors:

The mechanism of action is divided into: anode, cathode, mixed type. The characteristics of the protective film are divided into oxidation type, adsorption type and precipitation type. Other categories :① organic and inorganic corrosion inhibitors ② liquid phase, gas phase, solid phase corrosion inhibitors ③ steel, copper, aluminum corrosion inhibitors ④ acid, alkaline, neutral corrosion inhibitors.

Cleaning object

Cleaning before production, cleaning without stopping production and maintenance cleaning

1. Cleaning before putting into operation: New chemical equipment must be chemically cleaned and passivated before putting into operation. Practice has proved that chemical cleaning and passivation before driving are of great significance to the safety and economic benefits of production. The economic benefits are enormous.

The purpose of cleaning passivation before putting into operation

The raw materials of the system, such as steel pipe, steel plate and stainless steel, will form rolling skin when rolling; During the manufacturing, storage, transportation, and installation of the equipment, rust, welding slag, and oil rust prevention agents coated on the steel for anti-corrosion will be formed, and impurities such as dust, sand, cement, and thermal insulation materials will also be mixed into the equipment. Due to the increase of equipment capacity from steel pipe, steel plate factory, equipment manufacturing, storage and transportation, installation to the final production of the time becomes longer, the number of welding joints of the equipment increases, the heating surface increases, and the total amount of impurities such as rolled skin, rust, welding slag, rust prevention agent and sediment increases.

After cleaning, a dense chemical passivation film is formed on the clean metal surface, which can effectively prevent the recurrence of dirt and effectively protect the equipment. Protect the equipment from corrosion or other chemical damage

2, do not stop production cleaning: in the process of chemical equipment production, some equipment can not be stopped for maintenance and cleaning. Therefore, the continuous cleaning technology came into being. Domestic non-stop cleaning technology is relatively perfect, and chemical cleaning and passivation technology can be carried out in the state of equipment operation. So as to ensure the operation safety and efficiency of the equipment.

3, production maintenance and cleaning: production maintenance, that is, in the chemical enterprise annual planned maintenance time, all equipment for production maintenance and cleaning operations. Relatively speaking, the shutdown maintenance is a single equipment for circulating chemical cleaning or high pressure water jet cleaning operations.