The heat recovery steam generator (HRSG) is an integral part of steel production, cement production, paper production, and metal material production process,… In the regular maintenance plan, HRSG Cleaning is necessary for this system to make the operation process continuous. This article will help you to clearly understand why periodic cleaning of the heat recovery steam generator is required and the most common HRSG Cleaning solutions available today.
I. Why is HRSG Cleaning so necessary? How does HRSG affect the overall performance?
The HRSG is a passive heat exchanger that recovers heat from hot gas streams and turns it into steam to power a steam turbine. They may be used in a wide range of commercial and industrial. The boiler has various sizes, up to 80 feet tall and 40 feet wide. In terms of regular maintenance, HRSG Cleaning is a considerable barrier.
After using it for a long time, these HRSGs accumulate dirt and debris on their fins. Contamination will obstruct heat transport via the fins even in the smallest amounts. If pollution accumulates to a point where it obstructs the airflow, it can even block airflow past the fins, an essential process element. These issues will be detrimental to both the cost and the overall performance of the system.When there is a severe blockage, the control unit senses back pressure and slows down the turbine. These performance losses will cost the owner a lot of money if they aren’t rectified quickly. To avoid this loss, it is the smartest choice for factory owners to use a reputable and professional service like VIVABLAST to clean up contaminants through Dry Ice Blasting.
II. HRSG Cleaning method – The three popular cleaning procedures
Most of the deterioration and problems can be minimized by HRSG Cleaning. This work will focus on cleaning the back area of the boiler – the part that accumulates the most deposits to restore HRSG efficiency. Below are the three methods that have proven to be the most effective in cleaning heat recovery steam generators.
1. CO2 Ice Blast Cleaning – The most popular HRSG Cleaning method
For numerous reasons, dry ice has been demonstrated to be the most effective HRSG Cleaning. This technique, in particular, does not introduce any secondary waste streams or foreign products. Consequently, the only waste it produces is the debris and dirt removed from the surface, lowering process costs and time. It is also an environmentally safe solution and does not promote corrosion.Instead of using the hard abrasive method to grind on and damage a surface, CO2 ice blast cleaning uses soft dry ice at supersonic speeds to generate micro-explosions on the surface to go flat out the contamination of the surface. The ice explosion reaches its pinnacle when it transitions from solid to gaseous form, and CO2 expands rapidly (750-800 times its original volume) to separate debris from the surface, subsequently vacuumed away. 
Scaffolding is necessary to access the tubes’ full height and inspect the borehole range after cleaning in large volume boiler systems. Special spreading tools are used to spread the pipes to the full depth of all pipes in a module. Modules may be accessible from both sides of the tube, ensuring that both the front and rear are cleaned. After the explosion, if required, a chemical solution is used to wash away any tenacious residual deposits.
2. Pressure Wave Cleaning – Pressure wave HRSG cleaning solution
BANG & CLEAN Technologies AG of Switzerland invented the pressure wave HRSG Cleaning process in 2001, and GE licensed it in the United States. A balloon loaded with an explosive mixture is ignited near the tubes to be cleaned in this method. The tubes are shaken by pressure and vibration waves, which separate debris from the surface, which fall to the floor. Because the procedure requires a series of explosions – 100 or more – it is managed remotely to avoid injury.
3. Chemical Cleaning – HRSG Cleaning method using hydrofluoric acid
Many HRSGs are now cleaned with hydrofluoric acid (HF), especially in Europe. However, HF is a hazardous acid that can inflict severe burns. As a result, HRSGs in Oman have been cleaned using the citric acid approach. HRSG Cleaning by chemical using citric acid that has been inhibited is a viable option. However, to guarantee that the iron oxides are properly dissolved, a high temperature should be guaranteed between 80–90°C. Ammonium bifluoride can be used to somewhat compensate for this. As a result, you’ll be able to clean at a lower temperature. The elimination of silicate deposits also necessitates hydrofluoric acid or ammonium bifluoride.An uncleaned HRSG has two direct effects on plant performance: it increases exhaust side pressure drop, which reduces gas turbine (GT) efficiency. Cleaning the HRSG is an excellent technique to regain lost performance since it reduces back pressure on the gas turbine, enhancing overall system efficiency. Many HRSG Cleaning projects have used the three cleaning procedures listed above. In which, cleaning with dry ice CO2 shows to be superior and becomes the preferred method.
If you are looking for a reputable and professional unit to implement the HRSG Cleaning plan, VIVABLAST is proud to be the perfect choice for your plant. VIVABLAST is the Exclusive Contractor of SPEC Co. PTE, the Exclusive Authorized Reseller of COLD JET US in VietNam, developing dry ice manufacturing and dry ice cleaning technology for various applications. Along with that is a team of professional technicians who have undergone intensive training to perform effective HRSG Cleaning procedures.
