First   Introduction

During the refinery shutdown mainteance, the traditional steam purging is often adopted in heavy oil system, but chemical cleaning is a kind of technology of using cleaning agent to dispose heavy oil dirt, which is recycled in the temperature of 130-150℃,with catalytic diesel oil as the mother liquor. Because the industrial heavy oil cleaning agent has a strong penetration and decomposition effect, it has a strong affinity and decomposition effect on macromolecular hydrocarbons, even high C/H ratio of asphaltenes and colloid, making it achieve a good cleaning effect at low concentration (1.0-1.5%).

Second  Cleaning mechanism

1.Wetting and osmosis 

The cleaning agent contains surface active ingredients, which can reduce the effect of surface tension. When contacting with dirt, the surfactant is arranged evenly on the surface of the dirt, so that the cleaning agent can fully moisten the surface of dirt. Since the cleaning agent has a strong penetration ability, it can penetrate the tiny gaps on the surface of dirt to get inside the dirt and loosen it.

2.Chemical decomposition

The oil coke of heavy oil scale is not easy to disperse, because its molecular weight is relatively large. After adding the cleaning agent, it can be quickly decomposed into a substance with smaller molecular weight and dispersed into the cleaning solution.

3.Dispersion effect

When the cleaning agent is inside the dirt, the dirt is separated from the fouling body under the action of mechanical force and dispersed into the cleaning fluid to achieve the purpose of removing the dirt.

4.Wash stripping

Due to the flow of the cleaning fluid, some of the dirt is washed off the surface of the equipment.

5.Film-forming

The cleaning agent contains a film forming material which can form a protective film on the metal surface to prevent corrosion of the metal surface.

Third.  Characteristics  

Compared with the past cleaning method, biodegradable cleaning method greatly improve the cleaning effect, at the same time, there is no waste water, the equipment will not be corroded by water, saves steam and shortens the time of overhaul purging. Cleaning liquid can also be recycled, bringing good economic benefits.