Currently, commonly used methods for cleaning oil pipes can be divided into two main categories: physical cleaning and chemical cleaning. These primarily include hot boiling cleaning, heating cleaning, laser cleaning, biological cleaning, ultrasonic cleaning, dry ice cleaning, and water jet cleaning. Below are several cleaning methods:
Heating Cleaning
The substances adhering to the surface of oil pipes are primarily a mixture of solid and liquid phases. Near the phase transition point, the viscosity of this substance decreases rapidly with increasing temperature. Utilizing this characteristic, heating cleaning is employed to reduce the difficulty of cleaning oil pipes. Heating cleaning mainly includes electromagnetic induction heating cleaning, far-infrared preheating flushing cleaning, and efficient hot air oil pipe cleaning.
Electromagnetic Induction Heating Oil Pipe Cleaning
This method passes the oil pipe through a medium-frequency induction coil for instantaneous heating, with the heating temperature controllable between 100 °C and 130 °C and a heating speed of approximately 10 m/min. During heating, the oil and wax on both the inner and outer surfaces of the oil pipe melt completely.
A steel wire brush rotates at high speed on the inner wall while low-pressure, high-flow clean water is used for washing. This method eliminates the need for a heating source, such as a boiler, reducing cleaning costs. However, the initial investment is relatively high.
Far-Infrared Preheating, Flushing, and Cleaning
When the working environment temperature is low, crystallization and wax formation occur on the oil pipe wall, leading to blockage of the inner wall and affecting production. Using far-infrared heating technology, the oil pipe is placed in a far-infrared radiation field.
When the environmental temperature is too low, the far-infrared oil pipe preheating system automatically starts, making it convenient and reasonable without the need for a heating medium for direct radiation heating. Energy is converted into infrared radiation through a specially designed far-infrared tube, eliminating the need for complex equipment cleaning operations in low winter temperatures.
However, since this method relies on infrared radiation heating, when multiple oil pipes obstruct each other, the cleaning effect is significantly reduced, resulting in lower cleaning efficiency.
Efficient Hot Air Oil Pipe Cleaning
This method combines electromagnetic induction heating and high-pressure water jet cleaning. The oil pipe to be cleaned is first heated using a medium-frequency electromagnetic induction coil. Then both the inner and outer surfaces of the oil pipe are simultaneously cleaned using high-pressure water jets. This method not only requires a high initial investment but also involves complex equipment processes.
The heating methods mentioned above also have the following disadvantages:
- The high temperature during heating produces smoke from the oil and other debris on the inner and outer walls of the oil pipe, polluting the environment and posing a fire hazard.
- If the heating temperature is too high, it can damage the metallographic structure of the oil pipe body, while temperatures that are too low will not achieve effective cleaning.
Chemical Cleaning
Chemical cleaning relies on chemical reactions, using chemicals or other solvents to remove dirt from the surface of objects. This method uses a boiler as a heat source, placing the oil pipe to be cleaned in a pool heated to 80-90℃ for soaking, followed by the addition of chemical cleaning agents for high-temperature boiling.
Therefore, chemical cleaning is also known as “hot boiling cleaning.” Due to the high cost, lengthy duration, and poor effectiveness of chemical cleaning methods, as well as the significant consumption of fuel and cleaning agents that can cause substantial environmental damage, this method is now rarely used.
Biological Cleaning
In recent years, a biological remediation method has emerged as a cost-effective and practical purification technology for treating oil pollution in oil pipelines. When using this method for cleaning, microbial cells produce catalytic cleaning enzymes that decompose and convert dirt and impurities on the surface of the cleaned object, achieving proper environmental protection without damage.
Biological cleaning methods primarily include enhanced and dissociative types; however, due to the immaturity of the technology, they are still in the early stages of research.
Ultrasonic Cleaning
This method utilizes ultrasonic cavitation to generate high-speed micro-jets on the surface of the object being cleaned, using the impact force of these micro-jets to clean the surface. Ultrasonic cleaning does not damage the surface of the cleaned object and is suitable for cleaning objects of any complex shape. It is widely used in various fields, including medical, electrical, and aerospace.
This method has high cleaning efficiency and quality, but requires the object to be placed at the center of the sound wave generator, and it is less effective for soft materials.
Dry Ice Cleaning
Dry ice cleaning uses compressed environmental media to spray dry ice particles. When dry ice particles impact the surface of the object being cleaned at high speed, energy conversion occurs, causing the dirt to condense and peel off. After peeling, the dirt is rapidly removed by the environmental medium. Since dry ice particles vaporize or sublime instantly after spraying, they do not damage cleaning equipment or surfaces and do not pollute the environment. However, it is essential to ensure good ventilation at the cleaning site when using this method.
Water Jet Cleaning
Water jet technology has emerged as a new and rapidly developing technology in recent years, with a wide range of applications across various industries, including aviation, petroleum, chemical, municipal engineering, coal, construction, metallurgy, and transportation. This technology pressurizes ordinary water through a pump to form a water jet with a specific pressure, used for removing dirt, cleaning pipes, cutting, and breaking rock, among other applications.
Compared to chemical cleaning methods, water jet technology has several advantages: it has a wide application range, low cost, does not corrode metals, does not pollute the environment, does not damage the cleaned object, is not limited by the shape of the object being cleaned, has fast cleaning speed, uses less water, high efficiency, high cleanliness rate, and a high degree of intelligence and automation.
Due to these significant advantages, water jet technology is favored by the global cleaning industry and is increasingly used in modern cleaning practices. As water jet technology offers fast cleaning speed, good quality, low cost, and minimal pollution, it is currently the preferred method for cleaning oil pipes in the oilfield industry.
References:
- Liu Junzhuang. Application of High-Pressure Water Jet in Remanufacturing Cleaning [D]. Shandong University, 2012.
- Wang Jiaming. High-Pressure Water Jet Technology and Its Applications [J]. Chemical Engineer, 1995(1): 57.
- Qu Wei. Application of High-Pressure Water Jet Cleaning Technology [J]. Chemical Technology and Development, 2012, 41(8): 54-56.
Author Information:
Zhang Chaoxu (1999.02-), male, from Yuncheng, Shandong Province, a student majoring in Building Environment and Energy Application Engineering at Heilongjiang Bayi Agricultural University.
Corresponding Author:
Yang Zhongguo (1979.01-), male, associate professor, master’s supervisor, from Caoxian, Shandong Province, a teacher in the Building Environment and Energy Application Engineering program at Heilongjiang Bayi Agricultural University.
Funding Project:
Heilongjiang Provincial College Student Innovation and Entrepreneurship Training Project (Simulation and Experimental Research on Cavitation Water Jet Cleaning Characteristics: No. 201910223020).
