Introduction of cavitation jet cleaning technology

　　Cavitation refers to the explosive growth of cavitation bubbles (i.e. gas nuclei, generally less than 20 μm in radius) due to the evaporation of liquid due to local low pressure of liquid flow system (lower than the saturated vapor pressure of liquid at the corresponding temperature). When cavitation bubble collapses, it will cause a powerful micro-jet impact, resulting in a very short-lived high-pressure pulse. The tiny space around bubble will form a local hot spot, resulting in extreme high temperature and high pressure, accompanied by complex physical reactions, chemical reactions, mechanical actions, and electrochemical reactions. action and thermal action. According to calculations, when free cavitation bubble collapses, flow velocity of micro-jet near the wall can reach 70 to 180m/s, and impact force generated on the surface of object is as high as 140 to 170Mpa. The diameter of micro-jet is about 2 to 3μm. Numbers of jet impacts is about 100 to 1000 times/(s·cm²).

　　The cavitation jet underwater cleaning technology is a new type of underwater facility cleaning technology formed by introducing cavitation into water jet cleaning technology, that is, artificially generating high-density cavitation bubbles in the water jet beam, using a large number of cavitation bubbles to the strong micro-jet impact force generated by collapse of local tiny areas on the surface of object can achieve the purpose of cleaning hard dirt and attached sea creatures of the facility. This technology not only has the advantages of high efficiency, energy saving, environmental protection, safety, etc., but also does not damage the base material of facility, and does little or no damage to the original anti-corrosion layer. It can reasonably and effectively clean thin area of equipment such as ship propellers.

Advantage

　　The principle of cavitation jet cleaning method determines that it is very suitable for cleaning operations in underwater submerged environments. Using a lower pressure water source will not cause harm to the operator or the surface to be cleaned. There is no restriction on the cleaning water source, which can be tap water or sea water (pumps, pipelines, etc. need to be resistant to corrosion), and it is convenient to obtain materials. There is no need to add any chemical reagents, no toxic emissions during the operation, and it is an environmentally friendly cleaning technology. High cleaning efficiency, convenient for automatic transformation. Using cavitation jet technology for construction can achieve high cleaning efficiency, excellent cleaning effect, safety and environmental protection construction requirements and good economy. Compared with traditional cleaning speed of more than 10 to 20 square meters per hour, cavitation jet cleaning plate can reach hundreds of square meters to thousands of square meters per hour, and can clean various types of dirt with different pollution levels.

Application field

1. Cleaning of offshore oil structures

　　my country's large-scale marine structures are mainly pile-leg oil production platforms, and it is expected that semi-submersible oil production platforms will gradually increase in the future. In order to ensure the safety of platform, personnel and facilities, it needs to be cleaned effectively within a certain period. With the rapid development of offshore oil industry, there are more and more large-scale marine structures, and cleaning tasks increase rapidly. Efficient and safe cavitation jet cleaning technology will become an inevitable need.

2. Cleaning of subsea oil facilities

　　Offshore oil engineering includes a large number of subsea oil facilities such as underwater oil recovery systems, and it is very difficult to clean them reasonably and effectively in a complex marine environment. Carrying cleaning equipment by divers or ROVs is the only effective method at present. The development of modular and automated cavitation jet cleaning equipment can effectively solve the cleaning problems of underwater facilities.

3. Ship cleaning

　　FPSO, ships, etc. operate in the marine environment for a long time, and a thick layer of marine organisms and dirt will be formed on the surface of hull below the waterline. A large area of corrosion will inevitably be formed on the surface of hull of a ship operating all year round. On this basis, the adhesion of algae, shells and other marine organisms will form a tight and hard dirt layer. The marine biofouling layer and dirt layer seriously affect the sailing speed of ship, increase the cost of fuel consumption and shorten the service life of ship. In ship cleaning industry, cavitation jet cleaning technology undoubtedly has a broad space for development.

4 coastal engineering cleaning

　　In common coastal projects, long-term accumulation of marine biological dirt and silt directly affects the normal operation of ports and waterways; long-term erosion of marine organisms also has serious adverse effects on bridges and tide-proof lifts, directly affecting the firmness and quality of these facilities. service life etc. Therefore, it is of great significance to clean coastal engineering, and cavitation jet cleaning technology also has a broad application space.