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Expert HRSG Cleaning
Heat Recovery Steam Generator Cleaning
US Cleanblast; HRSG’s accumulate contaminants and deposits on their finned tubes, which are used to conduct heat. Even in small amounts, the contamination resists the transfer of heat through the fins, resulting in a loss of efficiency. If the contamination accumulates to a certain amount, plugging airflow, it may severely restrict the flow of gas across the tube banks, which is an important part of the process. When there is a case of severe blockage the control unit senses back pressure does this slow the turbine?
Engineer: It doesn’t slow the turbine, the turbine runs at constant speed. What happens is it creates elevated back pressure on the turbine. Because of that the turbine generates less power, the turbine efficiency drops, and the Heat Rate (amount of energy used to generate one kilowatt-hour) becomes higher as well.
Engineer Testimony :We have instrumentation that records it. The backpressure went from 21” WC (water column) before to 18”WC after the cleaning. As mentioned before, the lower the backpressure, the better the turbine output, the higher the efficiency and the lower the Heat Rate.
How do calculate the cost savings?
Engineer- There are 2 folds here. The manufacturer of the gas turbine has curves that allow you to determine the production and efficiency losses at elevated backpressure. The second part is that there is also a manufacturer’s limit on how high the backpressure can go before the equipment would suffer a catastrophic damage. The control system would automatically shut down the turbine if that limit is reached. If the boiler deposits are high enough to approach that backpressure limit, in order to prevent the automatic “turbine trip” the operators would reduce the power output to stay within the allowable limits. In our case, we had to reduce the output by as much as 20-25 MW (Megawatts). So you are losing a significant amount of power, corresponding revenue and efficiency.
Debris and contaminant build up on a Heat Recovery Steam Generator (HRSG) can be detrimental to efficiency, cost, and overall performance. HRSG’s are large heat exchangers that recover extreme heat from hot gas streams and create steam that can be used to power a steam turbine. They can be used in a variety of commercial and industrial applications. They come large or small, with some measuring as large as eighty feet tall and forty feet wide.
Over the years of use, these HRSG’s accumulate contaminants and debris on their fins, which are used to conduct heat. Even in small amounts, the contamination resists the transfer of heat through the fins, resulting in a loss of efficiency. If the contamination accumulates to a certain amount, plugging airflow, it may even block the flow of gas across the fins, which is an important part of the process. When there is a case of severe blockage the control unit senses back pressure and slows the turbine. Still, more efficiency is lost. All of this efficiency loss is not necessarily easy on the plant owners’ wallets. To avoid this loss, plant owners call upon professionals like US Cleanblast to clean the contaminants through Dry Ice Blasting and therefore boost efficiency. It has been said that for every ½ inch of pressure drop, a plant owner can save $100,000. This is why it is very crucial to keep HRSG’s contaminant free.
Cleaning HRSG’s with Dry Ice Blasting
Dry ice blasting is proven to be the best method of cleaning HRSG’s for many reasons. When the other options are considered, you soon learn why. First off, high pressure water blasting and soda blasting create a secondary waste stream, which contributes to the amount of waste. With water blasting, if not contained properly, the water carrying contaminates may flow down into drains or into the ground. The expenses for residual cleanup of both water blasting and soda blasting add to the overall cost and time of the process. Another inefficient method – sand blasting – will not work because the sand’s abrasive nature erodes the fin and tube metal and causes permanent damage. Also, blasting silica sand is a federal offense and may result in major fines.
The Benefits of Dry Ice Blasting in Power Plants
There are many benefits to dry ice blasting HRSG’s. First, with dry ice blasting, there is no secondary waste stream or foreign product introduced since, upon impact, the frozen CO2 (dry ice) sublimates to a gas. Therefore, the only residue to clean up is the debris and contaminants that were cleaned from the surface, minimizing the cost and time of the process. Also, dry ice blasting does not promote corrosion and abrasion, is USDA, FDA, and EPA approved, and is an environmentally safe process.
Expert Industrial and Commercial Cleaning
USCleanblast is ISN safety certified and all employees completed extensive safety training and are OSHA certified. This includes CO2 blasting, CPR, first aid, fork lift, aerial lift training and more. Employees are also very experienced working with containment and high elevations and insure that the job is being done correctly and safely. A large New Jersey power plant engineer stated “I am very pleased with your work quality.” US Cleanblast has dry ice blasted hundreds of large and small projects and is the proud owner of a perfect safety record.