Cleaner production pays

In 1998, the UNEP invited SSCPL to participate in and sign its international declaration for cleaner production practices. The paper presented there – developed in association with the Administrative Staff College of India (ASCI – a noted consulting organisation) - is reproduced here. Most of the recommendations herein are being implemented at SSCPL’s new plant coming up currently to meet an extra 600,000 cylinders per year overseas requirement.

CLEANER PRODUCTION

Initiative for LP Gas Cylinder Manufacturing Industry in India

Background of LP Gas Industry in India

Liquefied Petroleum Gas (LP Gas) is commonly used in India for cooking. Currently, India consumes around 5 million tonnes of LP Gas per annum out of which 90% is sold in cylinders of 12, 14.2, 15 and 19 kg net LP Gas capacity and the rest in bulk to large industrial users. There are three market segments namely domestic households, commercial establishments such as hotels and restaurants, and industries that use in cylinders as well as bulk. The consumption pattern is 80% domestic (all in cylinders), 12% commercial and industrial (in cylinders) and 8% industrial in bulk. There are roughly around 30 million households in India that use LP Gas and more than 12 million households who have registered and are waiting for LP Gas supply. The industry is growing by 10 to 14% every year for the past decade or so.

The LP Gas markets until 1993 were the monopoly of Government oil companies, which mostly sourced LP Gas from indigenous production from refineries and gas fractionation plants and limited imports due to severe infrastructure constraints. From 1993 the private sector has been playing an active role and has significantly added to the infrastructure and increased availability of gas through imports. Even the government oil companies have added new import facilities and some new refineries are expected to come into production shortly. Inspite of all this, a demand supply gap of 5 million tonnes is projected for the year 2006. The LP Gas markets are poised to grow at a faster rate in future as demand continues to outstrip supply

LP Gas Cylinder Manufacturing

The LP Gas market is served mostly in cylinders. Currently, it is estimated that there are 65 million cylinders in India and every year 7 to 8 million cylinders are being added to serve the new customers and to provide for replacement of old cylinders that have to be scrapped. There are about 55 LP Gas cylinder manufacturing units that typically produce 100,000 to 300,000 cylinders per year. Although capacity seems adequate for meeting the future demand, the manufacturing process technology is more than 20 years old. The excess capacity has prevented any major efforts to improve the process technology. As the industry is on the threshold of further growth in terms of capacity utilization, the time is ideal to introduce Cleaner Production Initiatives to improve resource utilization, reduce pollution and the damage to the environment. This is possible by information dissemination, setting up of demonstration units, technical assistance / collaborations and financial assistance which is precisely the approach proposed by UNEP.

Potential for Cleaner Production in LP Gas Cylinder Manufacturing

It is possible to address the following areas in cylinder manufacturing through Cleaner Production concept.

Simultaneous blanking (diagonally) of two cylinder blanks from a coil that will be lesser in width compared to the individual sheets that are conventionally sheared into squares and cut into blanks. The scrap generation will reduce by 7% with the new process. On an average for typical production of 6 million cylinders per year about 7000 tonnes of steel will be saved.

Each cylinder half is deep drawn into a cup shape in a single stage from a circular blank. If the deep draw is done in two stages, reduction in thickness at the stress points will be reduced and the thickness of the raw material steel coil / sheet can be reduced by 0.2 mm. It is expected that 7% saving is possible on the steel processed which again translates into 7000 tonnes of steel for a typical production of 6 million cylinder per year.

The seam welding is carried out by submerged arc welding process using AC motor driven DC generator. M/s Kirloskar Electric Company, the manufacturer who supplied these machines to all the cylinder units has even discontinued this product line. AC Rectifier machines consume less power compared to the AC motor - DC generator system and will be a better alternative.

About 0.9 litres of fuel oil is used for heat treatment of each cylinder for relieving the stresses built up during the fabrication process. It is possible to use LP Gas instead of fuel oil and achieve better thermal efficiency and reduced pollution.

For surface preparation shot blasting and zinc metallizing (anti corrosive coat) process are used. The machines being used are rather old and newer machines with better process technology will reduce the pollution and improve efficiency of the process. On the basis of 6 million cylinders production per year the industry uses 600,000 tonnes of steel grit for surface cleaning and 900,000 tonnes of zinc wire with an application efficiency of around 80% for the metallization process. The saving in zinc and steel grit through better process techniques have to be estimated.

The painting process is mainly spray process using compressed air and the paint handling is manual. The application efficiency is hardly 15 to 20%. On the basis of 6 million cylinders production per year, the industry consumes 900,000 litres of zinc primer and 600,000 litres of synthetic enamel paint. With improved handling techniques and electrostatic or powder coating techniques, the application efficiency can be improved enormously.

Conclusion

It is estimated that each year the cost of cleaning up the environmental damage due to industrialization, outdated production technologies and other inappropriate policies / practices would be about 4% of the GDP for India. At the micro level the economics of production (not using clean technologies) may result in damage to environment that would be more expensive to clean up. The LP Gas cylinder manufacturing industry is a mature industry and can do with technology upgradation (capital stock replacement) to reduce pollution and improve the resource utilisation. An evaluation by experts in the field such as Cleaner Production Unit of UNEP would establish the benefits from the "externalities" of Cleaner Production concept for LP Gas cylinder manufacturing.