Industry:

Power Generation

Date:

Feb 2024

The Challenge:

An engineer from a power plant in Florida contacted us to look at two of their coal ash silos that had two different type of failed external wrapping systems at the base of the silo (which was 90 foot off the ground, causing a cavity that could have allowed valuable coal ash to weep from the bottom of the silo and into the atmosphere. Upon inspection, on Silo #1, the rubber liner was damaged in multiple locations and is leading to concrete deterioration and crevices. Corrosion. On Silo #2, there was a polymer liner that failed at the seam, thereby allowing ingress of moisture and escape of coal ash. Each silo is 50 feet diameter. The repair included coating and sealing 16″ up onto the steel silo and 12 inches onto the concrete base.

Repair at Coal Ash Silo

The Solution offered:

CorrocoatUSA’s Sales Engineer arrived on site  within a week of the call. One week after that, we devised a specification that includes removal of each types of failed wrap using pneumatic tools, working a portion of the surface from 125 foot manlifts. The coating specification included for priming each respective substrate using Plasmet ZF for the Steel and Plasmet ECP for the concrete, followed by a layer of multiaxial fiberglass and finished off with an additional coat of Plasmet ZF and a polyurethane topcoat for UV protection. An unexpected problem that was encountered during the project was discovered while filling holes with the Corrofill E. (Note that there were there were hundreds of holes ranging from the size of a pinhead to the diameter of a walnut – see top right image.) Although the silo was said to be depressurized during the operation, the shape and size of the silo created a natural draft and therefore pressure on the silo.

After filling about 80% of the holes, the pressure increased on the remaining cavities to the point that pinholes formed in the Corrofill E once placed. It took several passes and  significant skill and patience to finally stop all of the air from escaping and fashion the filler to a shape that would allow for effective fiberglass application.

Ultimately, Corrocoat was up to the challenge and we solved a difficult and potentially expensive problem that we expect should last for the life f the plant.

Product:
Plasmet ZF
Plasmet ECP
Corrocoat Epoxy Laminating Resin (ELR)
Corrothane AP (PU topcoat)

*Note that Coal ash is a by-product from burning coal used in thermal power plants. Coal ash is used in industry for a variety or
commercial purposes, primarily as an additive in contentious concrete

A coal ash silo is a large storage structure used to hold coal ash, a byproduct of coal combustion in power plants. Coal ash consists of materials like fly ash, bottom ash, and boiler slag, which are produced when coal is burned to generate electricity. These silos are typically made of steel or concrete and are designed to safely store the ash until it can be transported or processed for disposal or recycling.

The silo plays a critical role in managing the environmental impact of coal ash, which contains harmful substances like heavy metals. Proper containment in silos helps prevent the ash from contaminating air, soil, and water. The silos are equipped with systems to load the ash into trucks or railcars for removal. Some facilities also have mechanisms for conditioning the ash to reduce dust and improve handling.

Coal ash silos are often part of a broader ash management system that includes pollution control equipment, ash ponds, and recycling processes. Recycled coal ash can be used in the manufacture of concrete, road base materials, and other products, reducing the environmental footprint of coal-fired power generation. However, proper maintenance and monitoring of these silos are crucial to prevent structural failures and environmental hazards