Innovations Promise Better Energy Efficiency

It's very difficult for our industry to replace traditional methods of achieving the final product. In most cases, an innovative technology must have an overwhelming appeal to make inroads. We continue to rely on the same distillation process, hydraulic equipment and heating methods. Fortunately we've gained much improvement by tweaking energy intense equipment through better process control, better monitoring, or government mandates. However, five new technologies have the potential to create significant change.

Stable Structure Zeolite Membranes – Although there have been improvements in energy recovery methods for the typical distillation tower, the reboiler-reflux tray separation method remains a fixture in most chemical and petroleum plants. Zeolite membranes promise to lower energy use but have suffered from structural defects that limit their use. A new rapid heat technology being tested at the University of Minnesota Institute of Technology (Minneapolis, Minn.) removes structural defects in zeolite membranes. Membranes can be made 10 to 100 times thinner, allowing molecules to quickly pass through with less pressure drop. If tests are successful, low energy membrane separators may replace energy-intensive distillation and heat separation processes over the next 20 years . The new membrane technology can reduce energy consumption by as much as 98% in some types of separations with a typical result being 50%-70%.

“These five technology ideas are worth watching.”

Electric Gas Turbine Burner – Most advancements in burner technology have been in reducing NO_x. Low-NO_x and ultra low-NO_x burners have been retrofitted in many old furnaces and are standard in new furnaces. Several innovative ideas gaining interest would turn flame-filled furnaces we have today into flameless high efficiency cogenerators. Combined heat and power optimizes performance while providing a flameless alternative. A convection furnace that uses small gas or liquid micro-turbines instead of burners produces both electricity and provides heat in an unusually flexible manner. Turbines allow for high efficiency electrical production while supplying heat for your process. System efficiency can be determined by current cost of electricity versus heat needed for the process. You can make electrical production somewhat independent of process requirements by using supplemental firing or added other heat recovery methods, such as steam production, along with the process requirements.

Solid Oxide Fuel Cell – Unlike the more popular hydrogen fuel cells which transport H⁺ from the anode to the cathode, the solid oxide fuel cell transfers O^-2 from the cathode to the anode. The reaction occurs at very high temperatures (1,800ºF) but has several important advantages in an industrial processing plant. The idea has been around for a while, but has been overshadowed until recent studies focused on reducing the 1,800ºF maximum temperature to a more equipment friendly 1,000ºF –1,400ºF. The fuel can be a number of hydrocarbons from natural gas to pentane or heavier. Electrical efficiency is between 40%-60%/ With heat recovery, the process has achieved overall efficiency between 80%-90%. There's very low NO_x production (~0.5 ppm) and no carbon monoxide. Because there are no flames or moving parts with the cells, maintenance costs are expected to be low.

Adaptive Energy Management System – Just when we've started to accept energy management control systems, new technology is being added to bring some artificial intelligence to the system. These systems learn from past practices and also use predictive information. Instead of just monitoring current energy uses and using provided equations to determine system response, newer systems actually learn from direct feedback and can adjust algorithms to the latest data. By building in the possibility that units can foul, wear down or not quite operate as predicted, better energy decisions can be made and information can be summarized to allow plants to keep aware of changes in their system.

Biomass Steam Boiler– A biomass boiler may not save theoretical energy like the other four technologies mentioned; however it can reduce overall carbon footprint. Using wood chips or other biomass may seem a step backwards, but in a carbon tax environment, using a carbon-neutral source can improve carbon efficiency and save money. Sometimes biomass can be used to partially replace other solid fuels, like coal. Biomass can be gasified to produce a synthetic gas that can be fed to furnaces. The key is to find a bio source that's nearby so that transportation costs don't outweigh benefits.

Although these five technology ideas are still long shots, they're worth watching. Is there a breakthrough technology that you think can change our industries? If so, please let us know.

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Gary Faagau is Chemical Processing's Energy Columnist. You can e-mail him at GFaagau@putman.net.