The DynaWave technology is attractive in that it has a low capex to fulfil emission re-quirements without having to stop running a plant for maintenance
Half a dozen DuPont MECS DynaWave reverse jet scrubbers, which have applications in Sulphur Recovery Units (SRUs), have been installed in the GCC area during the past decade with Saudi Arabia, Qatar and the UAE being the main states using the technology in the region, a senior DuPont official has revealed.
“Half of the DynaWave scrubbers currently installed and running in the GCC region are in Saudi Arabia,” said Yves Herssens, global market leader, DuPont Clean Technologies.
The DynaWave reverse jet scrubber aims to provide SRUs with a simple and highly flexible product that adheres to strict regula-tions aimed at enhancing the long-term sustainability of today’s oil and gas industry and reduce the global environmental impact of SRU units.
“Over 80 per cent of the DynaWave scrubbers installed in the region are used for the oil and gas industry. Since DuPont and MECS only started commercialising the technology for SRU applications outside of the USA in the last few years, the current installed base in the region is still mainly on sulphuric acid plants for the recovery of spent acid,” said Herssens.
“However, we see increased interest from the oil and gas industry to invest in DynaWave scrubbers as a solution for handling by-pass cases of SRUs and their Tail Gas Treating Units (TGTUs).”
The DynaWave reverse jet scrubber is an open duct in which scrubbing liquid is injected, through a non-restrictive reverse jet noz-zle, counter current to the dirty inlet gas. Liquid collides with down flowing gas to create the “Froth Zone,” a region of extreme tur-bulence with a high rate of mass transfer. The clean, water saturated gas continues through the scrubber vessel to mist removal de-vices. The liquid reverses direction and returns to the vessel sump for recycle back to the reverse jet nozzle. For SRU applications, DynaWave technology is used after the incinerator and before the stack.
The most appealing benefit of the MECS DynaWave technology for SRU applications is that it can process the entire SRU tail gas stream during TGTU shutdowns or upsets. This is because it has such a high operational flexibility, compared to any other kind of scrubbers. This allows an operator to continue operations under any given circumstances of the plant. In addition, it has the benefit that it can be used as an excellent polishing technology for very low SO2 emission levels to supplement the conventional TGTU pro-cess during normal operations. Stack outlet emissions down to less than 5 ppm were achieved with this technology. With the DynaWave technology, results were achieved that were below current detection limits.
Herssens said the technology has proven to be a low capital expenditure solution to reliably fulfil emission requirements under any given circumstances, without having to stop running a plant for maintenance or malfunctioning. “This is what really attracts people in the industry from this region but also all over the world,” he said.
As scrubbers are defined as devices that use a liquid to capture and remove pollutants and as they can be found in many different industries and applications, there is no obvious way to measure the total amount of scrubbers in the region, said the official. Indeed, many types of scrubbers do exist on the market ranging from spray towers over packed columns and venturis to even dry scrubbers. Each of them has its own features and depending on the application and the desired duty one can be a better choice over the other.
However, a key parameter in the design of scrubbers is the liquid-to-gas ratio (L/G). It is commonly expressed in gallons per mi-nute (gpm) of liquid divided by actual cubic feet per minute (acfm) of gas.
The bigger this L/G ratio, the higher the collection effi-ciency of the system. “For highly reliable and high collection efficiencies in fluctuating gas conditions such as SRU offgases and sul-phuric acid plants, the DynaWave Wet Gas scrubber is unique in its design due to its capability to work with extremely high L/G ratios. In these applications, the DynaWave technology clearly has been installed much more than any other type of scrubber tech-nology,” Herssens said.
“In the GCC region, we have also seen the DynaWave technology being used as a solution for treating offgases of waste incinera-tion. Also the titantium dioxide industry is considering the use of this technology in the region. This is not surprising, since this is the industry for which the technology was originally developed back in the 1970s. In general, regulations and international pressure drive emitters from different industries in the region to significantly reduce pollution and sulphurous emissions.”
Herssens noted that currently only a minority of SRUs have a scrubber in the region. “However, if the scrubber needs to address bypass cases in addition to its use as a polishing step after a tail gas treating unit, DynaWave is recognised as the only proven tech-nology that can reliably do the job.”
FEW, BUT AWARENESS RISING
Currently over 400 DynaWave scrubbers are installed all over the world and the GCC region accounts for less than 2 per cent of that number. But, Herssens said, DuPont had seen big progress in market awareness in the Gulf. “Some companies started the engi-neering, but we expect the big boom in the coming years as environmental awareness continues to rise,” he said.
“With the commercialisation of the technology in the SRU market we expect to significantly increase the share in this region which has many sulphur plants in the need to reduce emissions. Obviously, growth is very much related to environmental regulations, world bank standards, company objectives and local good neighbourhood objectives.”
Next to the DynaWave technology, DuPont now also offers a regenerative scrubbing technology, as a cost effective and radically new alternative to amine-based TGTUs. This technology is called SolvR and uses a solvent to regenerate SO2, rather than H2S. By doing this, the size of a new Claus reactor can be significantly reduced. For existing Claus units this can also be an interesting debot-tlenecking solution.
“In the USA, we currently have one operational reference in the sulphuric acid industry. We expect that the technology will become a game changer in the SRU market in the coming years,” said Herssens.
As a science and technology company, DuPont limits its scope of supply to basic engineering, licence and proprietary equipment. If a client has in house engineering capacities they can opt to do the detailed engineering and construction themselves, but often DuPont works through global EPC companies that can offer a turnkey installation to the client. DuPont has a network of representatives over the world, including offices in Dammam and Dubai and local agencies in Kuwait and UAE.