Chemical production has to comply with increasingly higher standards in terms of quality control, process and energy efficiency, environmental requirements and cost control. Implementing innovative solutions that combine them all has become one of the major objectives for process engineers. At Achema, the leading international show for chemical engineering, 3M and ThyssenKrupp presented their resource-efficient solutions for the process industry.
Up-Cycling: maintaining the level of quality
The US-based polymer specialist, 3M, and its subsidiary, Dyneon, leader in production of fluorothermoplastics, developed what they call up-cycling technology. This process reuses perfluoropolymer (a carbon and fluor material) without sacrificing its characteristics while eliminating the disposal of end-of-life monomers it contains.
Thanks to its temperature and chemical resistance, perfluoropolymer is used in numerous applications such as in fuel and powertrain systems. However, its monomer components are usually incinerated or disposed of in landfills when they reach the end of their useful life. This presents a double disadvantage—in terms of both pollution and cost—as disposal and incineration have a price.
With the collaboration of the university of Bayreuth (Germany), they started a pilot plant that closes the fluoropolymer loop and recovers the monomers. Exit waste disposal, welcome reuse of resources. But the plant goes beyond recycling. “We call this up-cycling and not recycling because the monomer we get is first class quality,” Judith Seifert, Manager Marketing Communications for 3M Europe, told DirectIndustry e-magazine. “We keep the level of quality.”
“This chemical recycling process ensures the monomer keeps its full quality and we can use it for the production of new”
How does this technology work? “It’s a reactor,” states Judith Seifert. “The waste material is heated up to 600°C to take out the monomer. We reduce it to small parts or powder, put it into the distillation plant and we clean it. This high temperature chemical recycling process ensures the monomer keeps its full quality and we can use it for the production of new fluoropolymers.”
Opened in 2015, the pilot plant, which receives end-of-life monomers from various producers, can up-cycle 500 tons of product per year. 3M and Dyneon are already working on a second step—up-cycling PTFE compounds, including little microspheres of glass fibers and graphite. “It will be high value for all manufacturers as those compounds are also hard to dispose of.”
ODC technology: energy conservation for chlorine production
Chlorine is one of the chemicals that is widely used by industry, whether for medicines or for the manufacture of plastics. In total, 80 million tons of chlorine are produced each year. But making this highly reactive gas is one of the most energy-intensive chemical processes. One ton of chlorine requires up to 3,400 kilowatt hours of electricity.
Together with Bayer, plant engineering specialist TyssenKrupp has developed a new process for making chlorine based on the fuel cell principle. This ODC (oxygen depolarized cathode) technology is commercialized for chlor-alkali and hydrochloric acid electrolysis. The new electrolysis process is simple. While the anolyte side remains normal, oxygen is introduced on the cathode side, eliminating hydrogen.
This reaction reduces the voltage required for electrolysis and therefore “consumes 30% less energy than conventional methods,” Dr. Adrian Schervan, Head of Global Sales told DirectIndustry e-magazine. “All chlor-alkali production facilities can afford this technology, as long as the right conditions are present. Such technology makes sense when electricity costs over 80 euros per megawatt.”
A recycling solution
Applied to hydrochloric acid electrolysis, ODC technology also allows for the recycling of chlorine from hydrochloric acid waste. “The hydrochloric acid electrolysis technology using ODC recycles the chlorine from a waste of NaCl [sodium chloride] by-products back into the process. This is something that is requested today in the industry. By recycling these by-products to chlorine, we solve the problem of NaCl disposal and NaCl sold on the market. Because it’s a huge quantity of NaCl which you cannot get rid on the market. So, it’s a very elegant way of solving such a production issue.”
Power consumption is also reduced “from 1700 kvh/ton of chlorine with the conventional methods to 1070 kvh/ton of chlorine with the ODC technology,” confirms Dr. Schervan.
This technology is used by Bayer in a plant near Shanghai to produce 250,000 tons of chlorine each year.