duplex stainless steel winner
recovery of sodium from the effluent stream is another notable benefit, generating annual savings of R600 000 by reducing the need for salt cake makeup. Environmental impact The environmental advantages of the MPPT are equally impressive. Installation of the tank has significantly reduced effluent volume, sodium and sulphate during upset conditions, thereby improving the mill’s sodium effluent compliance by 0.1 tons per day. The tank has decreased sodium effluent by 0.5 tons per day, aligning with Sappi Ngodwana’s environmental sustainability goals. One of the most crucial environmental benefits is that the tank enables statutory maintenance during annual outages without disposal of soda into the effluent stream. This feature not only supports environmental compliance but also enhances the overall sustainability of the mill’s operations. Fabrication challenges Constructing such a large and complex structure within a live, highly congested operating plant presented numerous challenges. ND Engineering’s field erection teams had to navigate a host of difficulties including limited space, environmental hazards like airborne contaminants and weather conditions and the logistical constraints of working in an active industrial environment. The tank was surrounded by vessels, equipment, pumps and large structures, leaving no access to any side of the plinth. The nearest assembly area was more than 25 metres away across a road frequently used by chemical tankers,
which could not be blocked for extended periods. The project also required lifting prefabricated tank sections over structures standing at least 15 metres high – all while minimising disruptions to the plant’s operations. Innovative solutions To overcome the challenges, ND Engineering adopted a piece-large approach: fabricating large sections of the tank off-site and assembling on-site using a tower crane with 14-ton lifting capacity. This crane was strategically positioned to avoid blocking roads and to minimise disruptions to the plant’s daily operations. This innovative construction approach not only allowed ND Engineering to complete the project within an extremely short timeframe of 2,5 months but also enabled significant cost savings by eliminating the need for a massive main lift crane. Despite the complexity and risks associated with working in such a constrained environment, ND Engineering completed the project without a single lost- time injury, underscoring commitment to safety and excellence. Conclusion The MPPT project is a shining example of ND Engineering’s expertise in stainless steel fabrication and ability to deliver innovative solutions under challenging conditions. By harnessing the strength and versatility of duplex stainless steel, ND Engineering has not only improved Sappi Ngodwana’s operational efficiency and environmental footprint but also set a new standard of excellence in the industry.
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Issue 3 – 2024
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