Increased production pressures have sparked a rise in inquiries regarding rapid dry-out materials. Often times, the inquirer wants to use a rapid fire material to reduce the downtime of their furnace equipment. The faster a furnace can be brought back online, the faster production can resume; very important, as time is money. However, people looking for a good balance of refractory properties should consider plastic refractories. They are proven performers and may provide a better cost solution.
Fast dry-out refractory materials are advanced castables, usually reduced cement types, bonded by both high purity calcium aluminate cements and silica fume, which may have the potential to yield nearly the same properties as their non-fast dry-out counterparts.
While they are promoted as an easy solution which provides time savings, they come with limitations to their material properties as well as cautions on dry-out:
- Lower strength properties due to reduced cure times.
- Limitations for accelerated dry-outs for linings greater than 9 in. or 12 in. It is common to require a longer dry-out, requiring a custom schedule from the refractory vendor. In some cases, these heat-up ramps are significantly extended.
- Vapor permeable enclosures are a must – weep holes, multiple venting sources.
- Vigorous air circulation is required.
- Several suppliers still put holds in the dry-out.
The benefit is that the dry-outs can be cut in about half the normal time. This can save up to 40 - 50 hours. However, the reduced properties can affect the overall performance of the refractory.
The important decision that the end-user needs to make is the trade-off between long-term strength of the material versus the short-term benefit of getting back online.
There might be a better option
Plibrico's line of plastic refractories and Exo-SetTM products, by comparison, might be the choice to make. While the project manager must determine the cost comparison between installing a reduced dry-out material versus a plastic material, often the plastic refractory remains a solid choice. It gives a balance of good properties along with the benefit of reduced dry-out times. The result is the best of all worlds.
Plastic refractories are useful in many applications, including repairs. They install easily, and Phos-bonded plastics bond well to existing refractory. They have good thermal shock resistance and can be fired immediately at a rate of 100°F/hr.
Plibrico's Exo-Set Uno gun mixes can be a good solution offering material higher placement rates, no curing time required, and a 50°F/hr ramp up to 1000 °F. These rates are comparable to most reduced dry-out castables. Other advantages over fast dry-out alternatives include:
- No cure time vs reduced cure time.
- Low temperature water release at 212°F – over 95% of the water is removed by 212°F.
- Higher permeability which allows for better pressure release during de-watering.
- Higher Porosity - thermal shock resistance.
- Low conductivity.
- Good abrasion resistance.
In the end, Plibrico plastic refractories and Exo-Set products emerge as a clear solution due to their properties, refractory contractor product familiarity, and ease of installation. They have a proven and consistent reputation of success in a wide variety of applications and are often the better cost solution.
Read the article online at: https://www.drybulkmagazine.com/dry-bulk/21092018/considering-plastic-refractories-for-rapid-dry-out-materials/