It’s remarkable just how much money and extra work a simple solution can solve. It can be hard to wrap our heads around the idea that a 3-inch Teflon lined, in-line static mixer can do the acid injection work of expensive tanks that take up 400 square feet and cost thousands annually. Yet this is exactly what an in-line static mixer provided for a Utah energy company.
The job at hand involved neutralizing effluent to a neutral pH before introduction to the sewer system. Waste water from power plants needs acid introduced before this kind of discharge can take place. The power plant had been using a pair of complicated tanks to introduce sulfuric acid.
One tank had a propeller mixer for neutralizing the waste water, and the second was a smoothing tank that diluted the acid. Operating them demanded 65,000 kw-hr of electricity every year. Together, the tanks took up 400 square feet of space.
Sulfuric acid is very corrosive. Mechanical parts wear much faster and need steady replacement. Insoluble sulfates also built up in the bottom of the tanks. The pH probe was fouled regularly. Annual maintenance ran about $25,000.
Efficient In-Line Static Mixing
An in-line static mixer is lined with corrosion resistant teflon. Depending on the acid being used, it can be lined with teflon & kynar. For this job, a 3-inch Teflon lined in-line static mixer was ideal. An injection port allowed for the introduction of sulfuric acid. The pH probe can be placed downstream, informing the sulfuric acid dosing pumps.
The advantages aren’t just about space. A huge amount of energy had gone into keeping those tanks whirring away, in a way that was inefficient for even dilution and mixing. In-line mixers mean that the flow that’s already occurring is used. A static mixer creates vortices and back-flow that efficiently mix. Various mixing elements build on each other’s efficiency exponentially.
Beyond this, a lack of mechanical parts means that maintenance costs are all but eliminated. Placement of the pH probe means less replacement or re-calibration need there. The neutralization process is simpler and more efficient than it was before, with less cost, less downtime, and more accurate information provided for acid injection.
Solutions like this abound, and can drastically change the costs, stresses, and time requirements of a variety of mixing needs.