The production of carbon dioxide (CO2) for food and beverages, as well as for a variety of other applications, is an increasingly specialized business. Carbon dioxide is now sourced from a variety of processes, including as a byproduct of ammonia and ethanol production, and increasingly as captured gas from larger industrial processes such as steam methane reformers. Capturing CO2 offers companies’ an opportunity to reduce their carbon footprint. The growing demand for CO2 for enhanced oil recovery and shale gas fracking also is generating increased interest in CO2 sources.
As CO2 sources become more diverse, so does the requirement for purification technologies to achieve the required final quality/purity of the raw recovered CO2. Around the world, governments are taking a more focused look at one of the main application areas for CO2, the food and beverage market, where increasingly rigorous food safety regulations are impacting the production, storage, and distribution of CO2.
Today, ethanol production is the dominant source for by-product CO2 as the quality of the raw gas is high and the path to a high purity end product is short. In North America, the ethanol business is the most important source for CO2 but several new sources — such as ammonia, hydrogen, and ethylene oxide sources — are emerging, and every CO2 plant process has to be designed to the specific purpose. In this article, we examine those design considerations.
Customized CO2 Technology
Union Engineering, which is focused on CO2 only and has several patents on CO2 technology, sees a rapidly changing market place from a plant design perspective. Michael Mortensen, CSO of Union Engineering, explains, “We increasingly meet with clients with new raw CO2 sources derived from differing syngas production processes, many of them related to biomass or other environmentally friendly processes. Because these customers are extracting and purifying CO2 to food grade level from syngas that is being produced from various sources, the impurities that need to be removed differ and the processes designed to remove them have to be customized for each project.”
Raw or crude CO2 falls into three categories of purity — high, medium, or low. High purity has a CO2 concentration of 85– 99 percent and is sourced from ethanol production, a fermentation process, and ammonia and ethylene production. Within this group, technologies like CO2, which efficiently removes components with a relatively high boiling point like aromatics, oxygenates, and various sulfur components, can be used and this eliminates the use of any process water.
Medium purity CO2 raw gas is derived from Hydrogen Manufacturing Units (HMU). The tail gas from a PSA (pressure swing adsorption unit) typically contains CO2 in the range of 45–55 percent. Union’s patented FlashCO2 technology turns the tail gas to high purity liquid CO2, and further improves the overall HMU capacity by up to 10 percent. FlashCO2 has proved extremely energy efficient and eliminates steam consumption. Low purity CO2 raw gas is sourced from combustion of fossil fuel, lime, or cement kilns and requires an upgrading unit to make it feasible for use in a CO2 liquefaction unit.
Low purity raw gas has a CO2 concentration less than 10–12 percent. By utilizing Union’s absorption and stripping technologies you can turn a low purity raw gas to a 99%+ high quality CO2 gas, ready for purification and liquefaction
Total Cost of Ownership and Reduced Carbon Footprint
“Along with the more customized technologies the market demands for CO2 purification, Union understands that the total cost of ownership is an essential consideration for our customers,” according to Mortensen. “The market requires high quality plants that save on utility consumption and thereby reduce a company’s carbon footprint. This is in line with our strategy and focus, and this is partly the explanation of our still increasing success in the CO2 technology business.”
Union Engineering is headquartered in Denmark, and has further production, sales, and service facilities in the US, Brazil, China, Singapore, Dubai, and the Netherlands.
In the spring of 2013 Union acquired the US-based Wittemann Company adding another 130 years of experience to the group. Commercially the company operates within Beverage, Industrial Gases, Desalination, and Oil & Gas industries and has a global Customer Service organization.