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HASLE cylindrical precast - the solution for cyclone targeted zone

The cyclone targeted zone is considered one of the most critical area in the dust separator unit, especially in Circulating Fluidized Bed (CFB) boiler. Because of the highly abrasive condition caused by the medium sand, the lining in this area has much shorter life than others. Thus, the targeted zone has become a bottle neck, forcing plants to shutdown sooner than it should be. This result in higher maintenance expenses and production loss which can be very costly.

Article By: Pawin Fahpinyo pf@hasle-refractories.com
Sales and Technical Support Manager | May 2019


The solution is to apply material which can withstand aggressive abrasion and provides a repellent surface protecting from alkali and other corrosion, especially in the targeted zone. A set of pre-fired precast element is perfect for this ultimate challenge. 

HASLE refractories has combined its reputable castable HASLE D59A known as anti-coating castable, engineering and precast fabrication know-how to produce HASLE Cylindrical Modular Lining Elements.
Since installed in 2017, the confirmed life is almost double (1.5 years) of the regular castable lining’s (less than 1 year) and the installation is still in service and expected to last for at least another 3 years.

The challenges


In 2016, HASLE Refractories was contacted by the maintenance management of a Bolier Unit in a process industry. The plant had problems with refractories lifetime of the cyclones targeted zones in its CFB boiler. The boiler has a 130t steam/hour capacity, providing 20.5MW power. It uses sludges – the waste from viscose production process, wood chip, and coal as fuel.

The life of the lining at the targeted zones in both cyclone units were less than 1 year (shorter than other refractory linings in the plant). It was obvious that one cause of failure was the extreme erosion caused by the sand used as bed material. Another cause discovered later was the corrosion from alkalis. Coating covered most areas in the cyclones.

Because the targeted zone is in the curved area of the cyclone, standard precast solutions will not fit these surfaces as they were designed for a flat wall or roof. The precast to be installed here must have a curved surface to fit the cylindrical shape of the cyclone.

Attacked areas in cyclone no. 1 and no. 2 marked in purple

Inspection at shutdown:

 Highly eroded linings in cyclone no. 1 and 2 
 

 Highly eroded linings in cyclone no. 1 and 2 

Coating in cyclones no. 1 and 2.
Coating in cyclones no.1  and 2.
A fully flexible anchoring system would make it possible to adjust elements accordingly, but at the price of reduced overall strength of the installation. On the other hand, a rigid and stronger anchoring system would make alignment awkward creating a rough, uneven surface, resulting in a shortened overall lifetime

The Solution:


In 2017, HASLE Refractories developed a precast element for the cyclone targeted zone. Each element is casted in a precise mold using specialized equipment to maximize performance. After casting, the elements are pre-fired to eliminate residual water, thus preventing any vapor pressure problems.
Thanks to a smart element and anchoring design, combining steel anchors with a tongue-and-groove system in the elements, the penetration resistance and installation flexibility are maximized.

The Performance:


In 2017, 2 sets of HASLE Cylindrical precast elements was installed in two cyclone units targeted zones.
After 1.5 years the elements have not only survived the harsh condition at the targeted zone but is still in almost perfect condition. Also, the amount of coating was less than on the nearby castable lining supplied by another supplier.


Picture shows the HASLE brand marks on the element surfaces after 1.5 years

Below picture-gallery of taken on installationsite and after 1.5 years of operation.

HASLE precast Modular Lining installed at the flat wall and Cylindrical precast installed at the targeted zone in cyclone no. 1 at the installation
The condition after 1.5 years (April 2018)
HASLE precast Modular Lining installed at the flat wall after 1.5 years.
Cylindrical element installed at the targeted zone after 1.5 years.
HASLE precast Modular Lining installed at the flat wall and Cylindrical precast installed at the targeted zone in cyclone no. 2 at The installation in 2017.
The condition after 1.5 years (April 2018)
HASLE precast elements were being installed in a cyclone

Conclusion:


Cyclone targeted zone is recognized as one of the most critical areas in the dust separator unit especially in CFB boilers. Because of the extreme abrasion and corrosion, the lining at this area last shorter than others nearby. The targeted zone therefore often becomes a bottle neck. HASLE precast elements, both the standard Modular Lining design and the Cylindrical design can withstand abrasion and alkalis at extreme levels. Already now, they have a confirmed lifetime almost double that of a normal castable solution in the targeted zone.


The Lining is expected to last at least another 3 years


The precast linings are still in service and expected to last at least another 3 years. This will reduce the cost of refractory materials and installation and will also have a positive effect on the plant run factor. 
HASLE precast has again proven themselves that they are the right solution for the cyclone targeted zone
 

Installations all over the world

HASLE Castables are used with very good references in a variety of Industries throughout the world, among these in Cement factories, Boilers and Incineration Plants. 

› See also our Case Stories and References 

HASLE look forward to becoming part of the solution to your refractry challenges. We are happy to offer advice and technical sparring through our international sales network. Feel free to contact HASLE for a noncommittal visit or recommendation.

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