Some tips for cleaning the heat transfer oil system in asphalt mixing plants

The role of the heat transfer oil system in the stirring equipment

To keep the asphalt at the working temperature, we need to heat and insulate the asphalt stored in the asphalt tank and the asphalt pipelines. At present, the most commonly adopted method is to achieve this through the thermal conductivity characteristics of heat transfer oil. That is, the heat transfer oil is first heated to a certain temperature through heating equipment, so that the hot oil circulates in the system and transfers heat to the asphalt to achieve the purpose of temperature increase.

The deficiencies of heat transfer oil in use

Due to the fact that heat transfer oil is prone to oxidation during repeated heating, its kinematic viscosity gradually increases with the increase of usage time, resulting in an increase in residual carbon content as the temperature rises. When the operating temperature is too high, it is prone to heat decomposition, especially the formation of carbon deposits on the inner walls of pipes and hot oil furnaces, which affects the heat transfer efficiency, accelerates the aging and failure of the heat transfer oil, causes local overheating of the furnace body and pipes, damages mechanical strength, and endangers personal safety. After the heat transfer oil forms scale in the pipeline, it reduces the flow area of the oil pipeline to varying degrees, increases resistance, lowers the oil transportation capacity, and may even cause pipeline blockage and other accidents. In addition, the energy consumption in the production process increases, the service life of equipment shortens, and the pressure rises, which seriously affects production. Due to the above-mentioned disadvantages of heat transfer oil, the entire system must be cleaned and descaled after it has been in use for a period of time.

Cleaning of the heat transfer oil system

At present, the more commonly used cleaning methods for heat transfer oil pipelines in the market mainly adopt chemical methods, such as cleaning with solution cleaning agents and solid cleaning agents. The precautions during the specific operation process are as follows:

First, please have a professional heat transfer oil pipeline cleaning agency thoroughly clean the pipeline. The cleaning process flow is as follows: discharge the old oil in the system → pre-wash → clean → add new oil → dehydrate → normal operation.

Conduct a pressure test on the overall air tightness of the cleaned pipeline. Apply soapy water to all the joint welds, flanges and other connection parts. Adjust the outlet pressure of the air compressor to 0.7MPa and maintain it for 2 hours. Confirm that there is no leakage and no pressure drop at the above parts.

After injecting the new heat transfer oil and starting to use it, spot checks should be conducted on the new heat transfer oil on the 7th and 20th days respectively after use to ensure that the newly injected heat transfer oil has not deteriorated.