Photo.com

China’s crude oil import keeps showing double digit year-on-year growth. Total import for 2007 is estimated at 160 million metric tons. The strong increase is paralleled by fast growing oil-refining capacity in China.

Gansu Lanke Petrochemical Equipment (Lanke), one of China’s largest heat exchanger manufacturers for the petrochemical industries, has helped make the growth possible with pioneering product development: the company has successfully replaced conventional austenitic stainless steel of type 316L (1.4404) in plate air-cooler and plate shell heat exchangers with duplex 2205 (1.4462) from Outokumpu. This application of duplex stainless steel in the plates of these types of heat exchangers, previously considered impossible, was made possible by strong R&D support from Outokumpu.

Lanke’s first plate air-cooler heat exchanger using duplex 2205, installed at the Guangzhou Petrochemical Oil Refinery in early 2006, is still in operation after two years from start-up. As a comparison, 1.4404 plates normally have a service life of no more than 3 months (6 months in some operating environments), but severe corrosion has been detected after only 1 month in operation. The operating conditions in oil refinery plate air-cooler and plate shell heat exchangers are characterized by temperatures of up to 140 °C and 170 °C respectively and chloride content of hundreds of parts per million (ppm).

Lanke engineers first started experimenting with duplex 2205 as a replacement for austenitic 1.4404 some six years ago, attracted by the high strength and corrosion resistance of the duplex grade. The engineers wanted to change the plate design to increase heat transfer. Their new design, however, complicated forming, and duplex grades feature only moderate elongation and limited formability compared to austenitic grades. With help from Outokumpu – in the form of information on the metallurgical properties of 2205, samples, examination of test plates, and various tests – Lanke finally developed a new shape, pressing technique, and production route applicable for 2205 sheet, 0.6mm thick, in year 2005.

Today, Chinese oil refineries widely use tubular heat exchangers. However, plate heat exchangers achieve the same heat transfer effect with only 30 percent of the space and weight, and 50 percent of the cost, compared to tubular heat exchangers. Such savings enabling higher efficiency are important when oil refinery capacities increase to avoid a consequent need to expand heat exchangers. As a result, plate heat exchangers are expected to replace more and more tubular units. Using duplex heat exchanger plates, oil refineries reap major financial benefits as maintenance shutdowns become fewer and shorter.

When first considering duplex stainless steel for plate air-cooler and plate shell heat exchangers, Lanke turned to Outokumpu. Chang-ching Sun of Outokumpu’s representative office in Beijing explains why: “Lanke’s decision was backed up by Outokumpu’s two-fold image in China. First, Outokumpu is well-known for developing new stainless steel grades and bringing them fast to the market. Second, we are known for strong technical competences.”
 
The cooperation between Lanke and Outokumpu continues. The two companies are currently investigating possibilities also to use Outokumpu’s duplex grades LDX 2101® (1.4162) and 2304 (1.4362) in plate heat exchangers.

For more information, contact:

Chang-ching Sun
Technical Manager, Chief Representative
Outokumpu Asia Pacific Ltd., Beijing
Phone +86 10 6590 1998, ext. 18
Email: chang-ching.sun(at)outokumpu.com