What are Flexible Drip Screens, Bottom Ash Hopper Water Seal Trough Protection Screens, Ash Screens, Drip Lips, Water Seal Screens, Slag Screens, Splash Screens, etc?

Flexible Wire Mesh

 

For More Information See... http://www.ipieinc.com/ or http://ipieinc.com/Flexible%20Wire%20Mesh.aspx

 

 



Flexible Wire Mesh Drip Screen




Flexible Wire Mesh Drip Screen Drawing



 

What is a Bottom Ash Hopper Water Seal Trough?
A water seal trough is essentially an expansion joint between the boiler and bottom ash hopper. The trough contains a seal plate typically made of Inconel® Alloy 601, Inconel® Alloy 625, AL6XN®, or Type 316L Stainless Steel. During the transition between a boiler's cold state and constant burning, the seal plate 'grows down' to the bottom of the seal trough, which in conjunction with water, creates an air seal. The air seal helps to prevent the uneven burning of coal reducing fuel waste and slag build up. During various cycles of burn, the expansion joint flexes between the full down position and somewhere just above that position.
Typically these expansion joints fill with ash and clinkers due to protection failure / inadequate protection. This causes the water seal to fail which results in decreased fuel efficiency, tube ruptures, increased maintenance, material, and repair costs.

 
In the past, boiler makers installed various types of rigid materials (ie. castings with refractory, woven wire space cloth, expanded metal, perforated plate, etc.) in front of the water seal trough for protection. Over time, these rigid materials would cease to protect the water seal trough due to:
·         Thermal Fatigue
·         Ash Caking & Corrosion
·         Warpage
 Warpage, a primary cause of water seal trough protection failure, occurs due to the inability of the rigid material to absorb impact from clinkers and thermal distortion.
A secondary pitfall to using rigid materials for water seal trough protection, is that they easily become caught, in essence, hung up on the refractory walls. This causes damage to the refractory on the wall, as well as the rigid material itself.
Why Should I Use Flexible Wire Mesh to Protect My Bottom Ash Hopper Water Seal Trough? 
·         Easy to Install
Our flexible wire mesh screen panels ship with an attachment bar. In most cases, the panels can be bolted to your existing mounting brackets. In cases where current mounting brackets are not available, I-PIE, Inc. will design and custom fabricate mounting solutions for you and including all attachment hardware. Panels can be tagged prior to shipment for proper placement in ash hopper.
·         Reduced Water Seal Trough Inspection / Repair Time, Labor, and Material Costs
Consider the time, labor, and material costs of using the rigid materials to protect your water seal trough. Many companies contract labor and hire experts to inspect and repair their water seal trough systems. Between loss of production, building scaffolding, removing the existing water seal trough protection, inspecting & repairing the seal trough, repairing or replacing the existing water seal trough protection, and removing scaffolding, these costs add up.
While we do not have a solution for the costs of building and removing scaffolding and performing the inspection, our flexible wire mesh screen panels (after initial installation) simply roll up out of the way to allow easy access to the water seal trough. Once the water seal trough work has been performed the screen panels easily drop back in place. No removal & replacement necessary.

·         Greater Longevity than Rigid Materials
The very nature of using flexible wire mesh screen panels is that they flex - a simple and obvious concept. These screen panels flex on a horizontal plane which allows them to absorb clinker impact without warping the protection barrier, resulting in greater longevity.
·         Lighter Weight than Castings with Refractory
In many cases, the removal and installation of traditional castings requires two or more workers. Generally speaking (depending on refractory thickness, casting thickness, etc.), castings with refractory tend to have twice the weight of their size equivalent in flexible wire mesh screen panels. This causes undue stress on boilers tubes and structures, as well as, an increase in labor hours.
·         Reduced Damage to Refractory Lined Walls
Rigid forms of water seal trough protection tend to wear and chip away at the refractory lining of the ash hopper walls. The constant impact and wear effect of these rigid materials on the walls creates problems of refractory erosion, which can eventually create problems for the clinker grinders. The flexible wire mesh screen panels give, helping reduce refractory erosion.
Flexible Wire Mesh Options...
Material Types:
We offer 304 SS, 314L SS, 316L SS, 410 SS, 430 SS, Inconel® 601 Alloy, Inconel® 625 Alloy, and Tophet® Alloy 30. Other materials are available upon request. Note: Higher sulfur coals typically require lower nickel alloys. Higher ambient temperatures typically require higher nickel alloys. We will be happy to discuss your needs.

A Brief History of Water Seal Protection...