At the core of the power system, large transformers are like silent giants, shouldering the heavy responsibility of voltage conversion and energy transmission. The dryness of its internal insulation system directly determines whether Giant can operate stably in the coming decades. Facing this core challenge, the traditional hot air drying method has become inadequate. Today, we will reveal to you a more efficient and thorough solution - the coal gas phase drying process, and how it has become the "gold standard" for modern high-end transformer manufacturing.
I. The Dilemma of Traditional Drying: Why Do We Need Better Solutions?
The core and insulating materials (such as paper and cardboard) of large transformers contain a large amount of moisture. These moisture molecules are the "invisible killers" of insulation systems, significantly reducing insulation strength, causing partial discharge, and even triggering breakdown accidents during long-term operation.
The traditional hot air circulation drying method has obvious shortcomings:
Low efficiency: Hot air conducts heat slowly and is difficult to penetrate deep into the tightest turns and insulation layers of the transformer.
Huge energy consumption: To meet the standards, a large amount of air needs to be heated for a long time, resulting in high operating costs.
Uneven drying: It is prone to cause a "half-cooked" phenomenon where the surface is overheated while the inside remains moist.
High final moisture content: It is difficult to reduce the moisture content of insulating paper to below the ideal level of 1%.
Ii. What is coal gas phase drying? An efficient "deep cleaning"
Coal oil vapor drying is an advanced process that uses special kerosene vapor as the heat transfer medium and dehydrating agent. Its core principle is ingenious and efficient, and can be summarized into the following three steps:
Precise and efficient heating stage
In the vacuum tank, we heat and evaporate pure kerosene. When kerosene vapor encounters the transformer body with a relatively low temperature, it will condense rapidly and release a huge latent heat of vaporization. This heat transfer method is extremely uniform and intense, capable of penetrating every gap of the iron core and coil without any blind spots, achieving rapid and uniform heating from the inside out.
The vacuum stage of deep dehydration
When the insulating material is fully heated and the internal moisture is evaporated, we activate the vacuum system to reduce the pressure inside the tank to an extremely low level. In a high vacuum environment, the boiling point of water drops significantly (for instance, at 1000Pa, water can boil at 7℃). This enables the moisture deep in the insulating material and even inside the fibers to rapidly "boil" and vaporize, and be forcefully extracted by the vacuum pump.
The cycle of adsorption and regeneration
To further enhance the drying efficiency, a molecular sieve adsorber will be integrated into the system. It is like a super sponge, specifically designed to capture and adsorb the water vapor separated from kerosene, maintaining the continuous drying capacity of kerosene and thus achieving the recycling of energy.
The entire process is precisely controlled by an intelligent control system to ensure that each transformer can achieve the optimal drying curve.
Iii. What core values does choosing the coal gas phase drying process bring to customers?
For transformer users, choosing products manufactured using the VPD process means obtaining multiple long-term guarantees:
Ultimate insulation performance: It can stably control the moisture content of insulating paper below 0.5%, far exceeding the traditional process, greatly enhancing the electrical strength and shock resistance of the transformer.
Extra-long service life: Completely remove moisture and oxygen, effectively delay the aging of insulating materials, and extend the design life of the transformer from 30 years to 40 years or even longer.
Unparalleled reliability: Significantly reduces the failure rate caused by insulation moisture during operation, ensuring the safety and stability of the power grid and minimizing costly downtime and maintenance losses.
Outstanding environmental protection and energy efficiency: Closed-loop system, kerosene recovery rate over 99%, almost no emissions; Meanwhile, it has a high thermal efficiency and saves about 30% to 50% energy compared with traditional methods.
Faster production cycle: Efficient heat transfer reduces drying time by approximately one-third, facilitating faster project delivery.