Coal Ash Pumping Challenges

Coal-fired Plants Residuals 101

Coal-fired plants generate energy through burning coal to heat water in a boiler, producing high-pressure steam. The steam is shot at a turbine that spins a generator to create electricity. 

Burning coal at these levels produces an enormous quantity of residuals referred to as “coal ash.” The coal ash is the combustion residuals or CCRs. Power plants produce a variety of residuals:

• Fly ash is a fine powdery material, and the largest amount of residue produced when burning coal on a large scale. It is around 80-90% of the total residue after combustion and is considered particle pollution that contains heavy toxic materials like lead, arsenic, mercury, cadmium, and uranium. 
• The bottom ash is the by-product of coal combustion collected from the bottom of furnaces. It represents 10-20% of the total residue and is coarser and more granular than the fly ash.
• Also, there is boiler slag that is a coarse, granular, incombustible by-product of coal combustion. Depending on the boiler type, this residue is disposed of in a variety of different ways.

Coal Ash Safety and Disposal

Coal ash is usually extracted from the site operation and moved to a settling area specially designed to contain and avoid environmental risks. The Environmental Protection Agency, or EPA, is the organism in charge of regulating the best practices of coal ash waste extraction and storage. Federal action was needed to ensure protective coal ash disposal because of large spills near Kingston, TN, and Eden, NC. These spills caused widespread environmental and economic damage to nearby waterways and properties.

Coal ash has high levels of different toxic heavy metals such as lead, mercury, arsenic, chromium, and selenium that are very harmful to the health and safety of humans and wildlife. And it has a high environmental impact. Some power plants dredge the material and transport it through pipes into specially designed ponds. These ponds secure the material and do not permit it to leak and contaminate underground waters and its surroundings. 

Recycling Coal Ash

Coal ash is one of the largest forms of waste around the world. A natural course of action was to find ways to make this waste somehow useful and reduce the pollution impact. Fly ash has been used as an additive in cement, grout, and concrete, and also has been used to fill some roadbeds during harsh winter seasons. 

The EPA estimates that over 110 million tons of coal ash are generated each year in the United States alone. The environmental impact of that much coal ash is significant. Repurposing coal ash can benefit the environment and the economy by reducing the costs associated with the disposal and increasing revenue with the sale of coal ash products. 

Coal Ash Removal Operation

In most industrial operations, the coal ash comes as a slurry with decanted material and is conformed by a dense mixture. This slurry is highly abrasive and challenging to remove to a landfill or pond. Most of the time, the material is pumped into a pipeline that takes the material to a landfill or transport truck to dispose of.

Pumping operations are challenging due to the highly abrasive nature of the slurry. They require extremely durable centrifugal pumps that can process this material. Unfortunately, many of these pumps tend to wear fast and slow down the operation, which translates into lost time and money. 

DAE Pumps outperforms other pumps on the market by providing longer-lasting impellers, wearable parts, and pumps. DAE Pumps makes economical, reliable pumps that last longer, and all parts are available for immediate delivery. The DAE Pumps centrifugal pump design enables the efficient handling of high solid, high abrasive/corrosive slurries without clogging for avoiding downtimes and costly equipment maintenance.