EvapoRite Systems : Air Systems

OVERVIEW

Water Remediation, LLC is one of several companies offering compressed air evaporation systems. The typical system uses a high volume air compressor, pontoon floats, and an array of siphon-based nozzles (described below). Although the technique for mixing the water and air might be different amongst evaporation companies, the siphon-based nozzle is quite common. In fact, manufacturers throughout the United States offer siphon-based nozzles as one of the many products they manufacture for resale.

EvapoRite Systems, Inc. tested siphon-based nozzles used by previous evaporation companies as well as nozzles sold on the open market. Our tests included runs in a controlled environment, as well as field operations. They were designed to measure flow rates, efficiency levels, and energy costs. EvapoRite did not test any of the nozzles used by any of Water Remediations current competitors.

HOW SIPHON NOZZLES WORK

The engineering principles behind siphon-based nozzles are the same for everyone, which is why the nozzzles are so similar in terms of volume and air flow. Efficiency, however, changes with the manner in which the mixing of air and water occurs. This is where the engineering of each nozzle is most unique.

In siphon-based nozzles an air compressor forces a large volume of air through a nozzle at high pressure. The air flow creates a vacuum that sucks water through a siphon-tube extending from the nozzle into the pond. The siphoned water is mixed with the air by the nozzle creating an atomized spray that is efficiently evaporated.

Siphon-based nozzles are manufactured by a variety of companies. Air atomized nozzles are engineered for specific purposes that are typically characterized by a requirement for high efficiency with low water flow rates (volume). Generally speaking, air nozzles will atomize less water in one hour than hydraulic nozzles atomize in two minutes.

COMPARISON DATA
Air Atomization vs. Hydraulic Atomization

	Atomization Rates Shown in Microns per Volume Atomized¹	Flow Rates Shown as Gallons of Water Atomized per Nozzle per Hour (per System per Hour)	Evaporation Efficiency	Diesel Fuel Costs Gallons Burned by System per Hour (Fuel Cost per Barrel Eliminated²)	Daily Production Shown in Barrels³
Compressor operating thirty-two air atomized nozzles at - 90 PSI with a 18-20 CFM sustained	<100	12 --- (384)	>60%	7.8 --- ($4.26)	105-120
Pump operating four hydraulically atomized nozzles at 400 PSI	100-200	468 --- (1,872)	18-22%	0.75 --- ($0.24)	160-180
Pump operating forty hydraulically atomized nozzles at 100 PSI	~400	384 --- (18,432)	2.0-3.2%	1.20 --- ($0.36)	180-200

1 - Atomization capabilities included in engineering data provided by nozzle manufacturer
2 - Diesel fuel costs calculated at $3.00 per gallon

3- Data reflects summer production rates for a standard system operating 20 hours per day

FINAL ANALYSIS: Compressed air evaporation systems are not cost effective. The energy demand of the air compressor is six to ten times higher than pump-based systems, and the ‘per nozzle’ volume is forty to fifty times lower than its hydraulic counterpart. In other words, these systems use a lot of energy to efficiently eliminate a low volume of water. This results in a high ‘per barrel’ cost. These systems do offer a viable alternative for very specific elimination requirements; however, cost and volume preclude universal application.

Atomization	Reducing the flow of wastewater into an evaporable mist. Atomization is critical. Higher atomization rates create smaller water droplets, which results in greater surface area per volume atomized. This typically results in higher evaporation efficiency.
Atomization Methods	Impact. This method forces a pressurized water stream into another object such as a pin, screen, or ‘chopping’ mechanism to achieve atomization Hydraulic: This method combines water pressure with the appropriate nozzle design to achieve the level of atomization desired. Air: This method uses a combination of pressurized air and nozzle design to generate exceptionally high levels of atomization. There are three water feed options for air atomized systems: 1) pressure; 2) gravity, and 3) siphon
Flow Rate	Refers to the total amount of water being atomized by each nozzle during a given period of time (per minute, per hour, etc…).
Evaporation Efficiency	This is a measure of the total amount of atomized water that gets evaporated. This number will vary month-to-month, and even day-to-day, depending upon any number of variables, such as: 1) water quality; 2) weather conditions; 3) systems deployment configurations; and 4) system capabilities.
Energy Cost	This is a measure of the total cost of the energy required to evaporate a unit of wastewater

Ratings:

Flow Rates (Rating: Poor): Compressed air evaporation systems are characterized by exceptionally low flow rates. This is the primary inhibitor of daily production and the single highest contributor to elimination costs. Flow rates for air atomized systems are measured on a scale of gallons per hour, as opposed to the “gallons per minute” attributed to hydraulic atomized systems. Flow rates can be increase by using pressure, or even gravity, but this can degrade the efficiency of a nozzle designed for siphoning. Most compressed air evaporation systems employ the siphon technique, and this is inherently the lowest volume method of air atomization. This is the technique used by our system.
Efficiency (Rating: Exceptional): Air atomizing nozzles are designed for efficiency. Atomization is their strength, but this strength is negated by volume. These nozzles atomize less than one-quarter gallon of water per minute (less than twelve gallons per hour). Further, they are atomizing this low volume with more 15 to 20 cubic feet per minute of high-pressure air flow (~90 PSI). This makes them very efficient. We have measured evaporation rates in excess of 70% of the volume atomized. NOTE: Efficiency is achieved by balancing air flow with water injection. Forcing more water into the nozzle can degrade efficiency significantly.
Heating (Rating: Neutral): Simply stated, thirty percent of nothing is still nothing. It’s relatively easy to heat air flowing through the nozzles by as much as several hundred degrees. This improves efficiency, but it does nothing to increase flow rates, which are the primary inhibitor of performance. Consider an example. Assume the heated air increases efficiency from 60% to 90%. This will result in 30% more water being evaporated per hour. Assuming a single-nozzle flow rate of ten gallons per hour, which is pretty standard for siphon nozzles, each nozzle would eliminate three extra gallons per hour (about one additional barrel every fourteen hours).
Energy Costs (Rating: Poor): Our system was burning through an average of 7.8 gallons of diesel fuel per hour. Assuming a 60% efficiency rate with 32 nozzles atomizing 10 gallons of wastewater per hour, we were eliminating approximately

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