A Plant Manager’s Guide to Boiler Refractory and Repair
November 30, 2018
Refractories are one of the most crucial components of a boiler system, creating a heat resistant liner that’s integral to its functioning. Unfortunately, the boiler refractory lining is often the most common reasons for outages and energy loss.
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Boiler Refractory and Repair
Boiler refractory lining repair is an inevitable part of operating an industrial boiler. Problems with your boiler refractory may include cracking, refractory door issues, pressure leaks, or damage to seals and joints. Once you’ve noticed signs of damage or dips in boiler performance, a refractory repair might be in order.
Pro Tip: Understanding your refractory and how it will react with specific fuels will better equip you to make the best decision for refractory materials.
Common Materials
In order to hold in the heat contained in boilers and furnaces, specific refractory materials are used. The materials used in boilers must be able to withstand extreme heat, pressure, and sometimes intense chemical processes. Common materials used are monolithic refractories or firebrick.
- Monolithic refractories- Include many different types of refractory materials including plastics, castables, and gunited materials. These materials don’t have a specific shape and have become a preferred option in the industry because they are economical and quicker to install.
- Firebrick- Ceramic material made to withstand extreme temperatures. As the name suggests, the material is shaped into bricks and heated with fire. Firebricks are commonly used in boiler linings.
Problems
There can be a number of reasons why a refractory lining needs to be replaced in a boiler, including:
- Rapid heating and cooling of the boiler, which can cause damage due to thermal shock to the lining.
- A chemical reaction between the materials used in refractory lining and the fuel can cause corrosion in the lining.
- Mechanical wear and tear are to be expected when high-pressure particles are in constant contact with the lining.
Considerations
- Refractoriness: A tendency at which a refractory material will deform under its own load. It is generally determined by the composition of the material used to make it.
- Porosity: The amount of voids or pores found within a refractory. The use of lower porosity materials can help to combat chemical reactions. (usually by fuel and water).
- Refractory Strength: The ability of the refractory to handle compressive loads, tension and stresses without failure.
- Specific gravity: Mainly referring to brick type refractory, the specific gravity is associated with the weight of the brick. A brick with a higher specific gravity will typically have better strength.
- Spalling: Spalling is a defect, also known as the fracture of refractory, which is caused by excessive thermal or mechanical load on the refractory.
- Thermal conductivity: A physical property that describes the general heat flow characteristics of the refractory.
- Thermal expansion: A physical property that describes the ability of the refractory product to expand while at high temperatures and contract during cooling.
- Bulk density: Measured as the weight of a given volume of the refractory and relates to probable porosity of the material used. A refractory with higher bulk density typically has higher strength, higher thermal conductivity, and greater thermal expansion. A refractory with lower bulk density will typically have lower strength but will have a greater lower thermal conductivity (higher insulating capabilities)
Repairing Refractory Linings
Boilers are critical process components that can completely shut-down a plant’s production when they fail. Partner with a refractory expert to better understand refractory linings and their proper maintenance.
Contact Us to learn more about the refractory materials that will work best for you.
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When it comes to refractory installation, there are many things that can go wrong. Refractories are a crucial part of many industrial processes, and even small installation mistakes can lead to significant problems down the line. That’s why it’s essential to get it right the first time. Here is a look at some of the most common refractory installation mistakes and how to avoid them.
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The East Bay Municipal Utility District (EBMUD) Wastewater Treatment Plant, located on the eastern shore of San Francisco Bay, provides service for an estimated 740,000 people in the greater Oakland, California area. In addition to traditional wastewater treatment, the plant also collects and treats solid waste from Bay Area food and animal processing facilities, restaurants, and wineries, diverting this waste stream away from landfills. The methane gas that is generated from the decomposition of this solid waste is then used internally as a renewable source of energy to help supply the treatment plant’s energy needs. When EBMUD began looking for a way to upgrade the failing brick refractory lining in their emergency digester gas flare structure, they turned to TFL, Incorporated. TFL developed an innovative precast refractory shape system that would offer dependable performance, structural integrity, and ease of installation. The unique system of floating wall panels is held in place using tongue-and-groove tieback shapes, bolted to the existing concrete structure. The individual panels in the system can absorb thermal and mechanical stresses independently. Given the location, potential seismic loading was also considered in the development of the system. The existing flare containment building is an oval-shaped concrete structure, with inside dimensions of 17’ wide by 47’ long. The refractory lined upper section of the structure is just over 21’ tall. The refractory wall thickness is 4-1/2”. A 2” air gap between the refractory wall and the concrete wall allows for airflow and ventilation. The refractory wall system consists of 514 precast shapes of four basic types, all manufactured in TFL’s Houston, Texas facility. The shapes were cast using Plicast HyMOR 3000 KK, a low-cement castable refractory manufactured by Plibrico Company. Stainless steel needle fibers were used for added reinforcement and to improve resistance to thermal shock and cracking. The shapes were fired to 1250o F prior to shipment, optimizing strengths and allowing the flare structure to be immediately operational, without the need for a field dry out of the refractory. NTK Construction, Inc. of San Francisco, California, was the installation contractor for EBMUD.
Mistakes happen, but here's a few that are can be avoided now, so you don't have to pay now.
Over the years, the refractory industry has faced many challenges. Precast-shape technology has helped us overcome some of them. The technology is used across different industries to produce better results and save money. If you choose to work with refractory castables, the process needs to be perfect. The physical properties of the material are sometimes weakened during the manufacturing stages by several factors. It’s even more crucial to get it right when the complexity increases to secure the performance of the lining. You can take full advantage of a castable’s physical properties by casting precast shapes in a controlled environment with experts overseeing the whole process. When it comes to drying and firing a refractory castable, you want the best lining production. Precast shapes allow you to ensure that the bake-out schedule recommended by manufacturers is followed to the tee since they can be fired in a digitally-controlled furnace. The shapes can also be fired from all sides, reducing moisture and giving off a uniform look that diminishes cracks. Additionally, the lining is less susceptible to stress, and its performance is more predictable. Precast-shape technology has many benefits, and you should take advantage of it. If you’re ready to use precast shapes to optimize your next project, contact us today to learn more about how we can help you.
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Minimize Downtime And Increase Performance With Precast Refractory Solutions from TFL! Precast Refractory Shapes can be used for a wide range of applications and industries ranging from foundry and boiler applications to petrochemical and refinery industries. Regardless of your industry or application, we have the expertise necessary to custom-manufacture durable precast shapes to meet your […]
The post Durable Precast Refractory Shapes Manufactured To Your Exact Specifications. appeared first on Refractory Materials, Precast Shapes, and Custom Solutions.
TFL Uses Custom Molding Techniques to Make Precast Refractory Shapes With Extremely Tight Tolerances
With Proper Attention to Dimensional Tolerances, Field Fit-up Problems With Precast Shapes Go Away The manufacture of precast refractory shapes inherently requires the use of some type of mold or pattern to form the castable into the desired shape. Some precast applications may require extremely tight dimensional tolerances, while others require less. The level of […]
The post TFL Uses Custom Molding Techniques to Make Precast Refractory Shapes With Extremely Tight Tolerances appeared first on Refractory Materials, Precast Shapes, and Custom Solutions.
The Rewards of Being a Part of “The Hidden Industry” The modern refractory industry dates back to the 1860s in the United States and has left an indelible mark on our society. About 34 years ago, the American Ceramic Society commissioned the publishing of the book “REFRACTORIES: The Hidden Industry, A History of Refractories in […]
The post Refractories Play a Pivotal Role in Virtually Every Industrial Process appeared first on Refractory Materials, Precast Shapes, and Custom Solutions.