Background

Phoenix Pulp & Paper (PPP) was established in 1978 and is located 400km from Bangkok in Khon Kaen province. The company produces hard wood pulp for use in the paper industry. It has two identical process lines one 30 year old and the other 15 years old both lines have all concrete bleaching tanks. Due to poor condition of the 30 year old tanks it was decide to replace two of the concrete tanks with two new steel structures.

Operating Conditions

The production of pulp at PPP uses chloride based chemicals to whiten the pulp at high temperatures. The high temperatures combined with the corrosive nature of the process chemicals produces severe and rapid corrosion of holding vessels and process equipment. Operating conditions for the tanks were as follows:

– Diameter	4m
– Height	23- 35m
– Material of construction	Mild steel
– Medium	Pulp
– Consistency	10-12%
– pH	2-5
– Chemicals	ClO2 (Chloride Dioxide)
– Normal Temperature	70-90°C
– Max. Temperature	120°C

Special Requirements

Trepax were awarded a turnkey contract to design, supply and install a suitable lining system to protect the steel tower shells. The height of the towers and the small diameter provided a challenge for scaffold design and erection inside the tower

Corrosion Protection

The client required a least a 20 year service life for the lining. The steel shell corrosion protection layer had to be protected from the high process temperature and abrasive quality of the pulp by a brick lining. Heat transfer calculations provided confrmation to the client about the thickness of the brick lining that had to be used.

System

The lining consisted of a liquid proof glass reinforced vinyl ester lining, 65mm thick low absorption ceramic bricks bedded and jointed in a vinyl ester cement.

Project Details

Location	Khon Kaen, Thailand
Project	New Bleaching Towers
Owner	SCG Phoenix Pulp & Paper Public Company Limited
EPC	N/A
Date	2008
Work	Steel Bleaching Towers
System	Vinyl Ester & Brick Lining
Area	865 m2
Value	US$ 370,000