Thermal oil lines decontamination
The thermal oil decontamination is indispensable in industrial lines for product changeovers or for dismantling. Thermal oil circuits require proper cleaning.
Despite its many advantages, thermal oil is a dirty, water-insoluble product, commonly used as a heat transfer fluid in industrial equipment and lines for both heating and cooling.
Its main advantages are its stability and resistance to oxidation, as it must be kept at a low viscosity despite temperature changes, its high thermal conductivity for efficient and fast exchange, and its long service life, depending on infrequent oil changes.
It is usually found in closed heating circuits, starting with a stage in which its temperature increases, followed by the appropriate stages of equipment and lines to receive heat exchange, closing the circuit and returning to the initial heating stage. Typically seen in heat exchangers, line tracing, reactor liners, storage tanks, etc.
Line cleaning stages with thermal oil:
Flushing
In this first stage, the system is filled with water to push the maximum amount of thermal oil out of the circuit, one or more inlets and one or more outlets are prepared without preparing a recirculation (all the product that comes out is discarded as waste). This stage also serves as a leak test to check for possible leaks in the system (both couplings and valves). At the end of this stage, the water circuit is not completely drained, as the aim is only to push the thermal oil as far as possible and use the remaining water in the circuit for the next stage.
Chemical cleaning
At this stage, recirculation does take place. From the LAGUPRES equipment, the solution is prepared in the mixing tank and pumped into the circuit (obtaining the return in the same mixing tank, thus creating recirculation). Once the chemical has been added, temperature is added to the system, usually with plant steam, to aid degreasing.
Neutralised
The final stage is neutralisation, which consists of finalising the system liquid to a neutral pH and finally emptying it. For this purpose, the circuit is drained by gravity (if gravity draining is complicated by design, pneumatic pumps are used), and rinsing with clean water is carried out. Periodic pH checks are carried out at each rinse until the desired pH between 6-7 pH is obtained.
Final Phase
Tank decontamination work manoeuvre
The chemical cleaning impulsion pump and its respective mixing tank will be installed in the plant.
An open circuit is established, which will consist of the installation of a rotating chemical cleaning head through an upper manhole and the return will be carried out by means of a pneumatic aspirating from the drainage pipe or at the point where the water accumulates due to the slope.
Conclusions on oil decontamination
This cleaning provides the desired finish to both obtain cleaning certificates for demolition and the necessary grade for product changes if desired. The chemical treatment is not aggressive to the materials being cleaned, nor is there any pressure on the equipment during liquid pumping. Waste generation is kept to a minimum taking into account the type of product being decontaminated (1.5 times the system volume for Flushing, 1 times the volume for Chemical Cleaning and 1.5-2 times the volume for Neutralising).
It is also useful to carry out this work for thermal oil changes. Good maintenance of equipment and lines is preferable in order to extend their lifetime and increase their efficiency.
