The function and importance of the Vapour Generator in Solvent degreasing systems
At first, the vapour generator seems straightforward in that it generates sufficient vapour to provide cleaning during the vapour degreasing phase of a wash program. However, typically found on sealed solvent degreasing systems such as those made by Karl Roll of Germany, the Vapour generator has multiple functions.
The vapour generator’s functions include: –
- Vapour for cleaning functions – vapour degreasing provides a pure distillate in vapour form. Before vapour degreasing commences, the parts are typically 20-30°C cooler than the vapour produced. When vapour transfers to the components getting cleaned, the vapour condenses, reverting to liquid with such volume that it flows over 100% of the surface of the components under gravity to thoroughly remove the organic residue from the components.
- Producing vapour for distillation – Unlike most aqueous systems, solvent systems are self-cleaning. German sealed systems typically recycle the total volume of solvent every 3-4 hours. Meaning in a 24/7 operation the solvent is recycled 3000-4000 times every year. The vapour passes through a condenser to revert to a liquid, typically running back to a holding tank or water separation tank and from these vessels, pumping the solvent to a wash tank that then overflows to the vapour generator, completing the circulation of solvent around the system.
- Producing vapour for heating wash and rinse tanks – Historically, heating the vapour generator and baths using electrical heating elements was the norm. However, in recent decades, using excess solvent vapour to provide heating capacity has improved system efficiency by reducing the connected kW required to drive the system.
- The collection of high boiling point waste oils, greases, waxes and other contaminants – The secondary benefit of point 2, distillation is any liquid with a boiling point 30-40°C higher than the solvent remains in the vapour generator. Over time these high boilers typically waste oils and greases from washing build up to a point where their removal becomes essential. Stopping the process of cleaning and switching the machine over to “rest distillation” enables the operator to drain off the waste products while leaving the solvent in the machine.
- A place to introduce solvent stabilisers and defoaming agents – With modern sealed machines’ ability to clean themselves efficiently, it’s not unusual for the same solvent to remain in the machine for several years. Continuous heating and cooling combined with the introduction of oils and greases from cleaning can result in the solvent’s slow and progressive degradation. Adding stabilisers via the vapour generator brings the solvent back to original OEM specifications. Calculation of the required amount of stabiliser via a simple testing procedure and look-up chart allows the operator to manage the system safely and quickly.
- A vessel for storing dirty solvent to feed a continuous distillation process – Sometimes, the manufacturing process demands a 24/7 operation, or the volume of waste collected in the vapour generator is too great, resulting in cleaning issues before the shift ends. Under these circumstances, coupling a smaller vapour generator style vessel to the main vapour generator enables the system to automatically transfers a small volume of dirty solvent and boil it down to just the waste products ready for automatic discharge into a suitable storage container.