New NOX Knockout, Plus Heat Recovery and Emissions Control

Thermal Energy International, near Ontario Canada, has made even greater progress in the year since the last UFTO note about them (see below).

The company “has received international market patent protection for its revolutionary 90% reduction “Low NOx” FLU-ACE Air Pollution Control and Heat Recovery technology, for application to all natural gas, oil, and coal burning energy process waste exhaust gases.” (from a company press release)

The Low NOx process oxidizes NO into NO2, which can then be absorbed by any wet scrubber. If FLU-ACE is used as the scrubber, the additional benefits of heat recovery and removal of other emissions can also be accomplished.

The Low NOx technology achieves 90% NOx removal at 30% to 50% lower cost per ton removed than the competing (currently accepted) reduction methods (SCR, SNCR). Other advantages are that the Low NOX does not produce hazardous byproducts, does not adversely affect the energy efficiency and operating cost, and does not suffer from an “ammonia slip” concern; which are all documented disadvantages of SCR technology.

The Low NOx process is a simple phosphorus (P) additive atomization and injection into the flue gas; which initially creates Ozone (O3) which then reacts with NO to produce NO2, and then the NO2 is easily 90% removed through a standard wet scrubber, or 98% removed through a FLU-ACE condensing & reactive scrubber.

Adding phosphorus is not a new idea. Years ago, researchers at Lawrence Berkeley Lab worked on putting it into the scrubber slurry (see UFTO Report, June ’95) , but weren’t able to get the performance to make it practical. Thermal Energy’s chief scientist was able to figure out the complex series of chemical reactions and determine that the best way to inject phosphorus was directly into the flue gas, as it leaves the boiler.

Installation is not complex, and can be readily done as a retrofit on almost any kind of exhaust system, with only a moderate degree of site-specific engineering.

To recap–there are two stories here. One is FLU-ACE, and the other is Low NOx. They can be used together or separately.

Low NOx provides significant cost savings over available technology. If a wet scrubber is already in place, costs can be 65-75% less expensive than SCR, at 90% NOx removal. As mentioned earlier, if FLU-ACE is installed as the scrubber, then NOx removal can approach 98%, and provide heat recovery and removal of other pollutants, with costs 30-50% cheaper than SCR alone.

Notably, FLU-ACE can remove multiple emissions at the same time, including fine particulates, hydrocarbons, heavy metals and VOCs, in addition to HCl, SOx, NOx, and CO2. The system replaces the smoke stack, with a smaller foot print and lower height.

It’s also worth noting that FLU-ACE qualifies under Canadian government export support programs that can provide low interest financing and performance guarantees.

The company is seeking to raise $12 Million in debt and equity capital, and has a business plan that they will share with qualified investors or potential partners. (I have a pdf copy of the Plan Summary, which I can forward on request.)

For further information:
Thomas Hinke, President
Thermal Energy International Inc.
Neapean (Ottawa), Ontario, Canada
613-723-6776 Fax: 613-723-7286 E-mail:
Web Site –

–previous UFTO NOTE —-
Subject: UFTO Note – Flue gas heat recovery and air pollution control
Date: Thu, 22 Jan 1998

Flue gas heat recovery and air pollution control

Simple in concept, FLU-ACE has accomplished something that many others have tried unsuccessfully to do for a long time, and they have plants that have been operating for over 10 years. Their condensing heat exchanger system replaces the stack in combustion systems, recovering almost all of the waste heat, and removing most of the emissions. With modifications, it even can remove up to 50% of the CO2.

It can be thought of as pollution control that pays for itself in fuel savings–or visa versa. Water is sprayed into the hot flue gas, both cooling and cleaning it. The water is then collected, passed through a heat exchanger to recover the heat, and treated to neutralize the acidity and remove contaminants.

Condensing heat exchangers aren’t new, but they normally can be used only when the hot gas is reasonably clean. FLU-ACE can handle any kind of gas, even if it contains particulates, acids and unburned hydrocarbons. Conventional wisdom holds that corrosion, plugging and clogging should defeat this approach, but FLU-ACE has overcome problems with its patented design. Systems show no degradation after years of operation. It has even been qualified for use with biomedical incinerator exhaust.

Industrial boilers and cogeneration plants are ideal applications. The installed base includes district heating systems, sewage treatment plants, hospitals, pulp and paper mills, and university campuses. Heat recovery is even greater when the exhaust gas is high in moisture content, e.g. in paper mills and sewage treatment. The largest system to date is 15 MW thermal, but there is no limit on the size.

A fossil power plant could use about 15% of the recovered heat for makeup water heating, so the economics are better when there are nearby uses for the heat. The company really wants to do a coal burning power plant–a slipstream demo could be the first step.

The company is a small publicly traded Canadian firm (symbol TMG – Alberta Stock Exchange). They have a dormant U.S. subsidiary, and are seeking U.S. partners, joint ventures and alliances for market expansion.

(UFTO first reported on FLU ACE in October ’95)

The following materials are excerpted from the company’s materials:

The unique FLU-ACE technology is a combined heat recovery and air pollution control system, which recovers up to 90% of the heat normally wasted in hot chimney flue gases. FLU-ACE substantially reduces the emission of “Greenhouse Gases” (including C02), “Acid Gases” (including SOx), Nitrogen Oxides (NOx), unburned hydrocarbons (such as THC and VOCs), and particulates (such as soot and fly ash). It eliminates the need for a conventional tall smoke stack or chimney.

Thermal Energy International Inc. has built eleven FLU-ACE Air Pollution Control and Heat Recovery Systems in Canada. All of Thermal’s FLU-ACE installations in Ontario have been approved by the Ontario Ministry of Environment and Energy. The life expectancy of the FLU-ACE system is at least thirty-five to forty years. In December 1997, the company received patent protection in 42 countries; the US patent is expected early in 1998.

Low NOx FLU-ACE provides a payback on investment and is self financing from the savings that it generates for the industry user. The company is able to provide “Off-Balance” Sheet financing or 3rd party financing options for acquisition of its FLU-ACE technology by industrial and institutional buyers.

Using a direct-contact gas-to-liquid mass transfer and heat exchange concept, the system is designed to process flue gas from combustion of fossil fuels, waste derived fuels, waste, biomass, etc. The FLU-ACE System is configured as a corrosion resistant alloy steel tower at a fraction of the size of any conventional stack. All of the hot flue gas from one source or multiple sources (including co-gen and boilers) are redirected into the FLU-ACE tower, where it is cooled to within one to two degrees of the primary water return temperature, which enters the tower typically at between 16¡C (60¡F) and 32¡C (90¡F) depending on the season and outside air temperature. The heat (both latent and sensible) from the flue gas is transferred to the primary water which then reaches up to 63¡C (145¡F) and with special design up to 85¡C (185¡F), and circulated to various heat users.

FLU-ACE most sophisticated version (HP) reduces air pollutant emissions by over 99% including particulate down to 0.3 micrometers in size, and simultaneously recovers 80-90% of the heat in the flue gas normally exhausted into the atmosphere. This results in a reduction of fuel consumption by the facility up to 50%.

Parallel Active Harmonic Filters

There is a common perception in the utility industry that power quality should be dealt with at the service entrance. As a general rule, however, managers of commercial and industrial facilities know that the real problems are inside the plant–their own (heavy) equipment is usually the cause of disruptions to their own sensitive loads.

There are greater benefits when harmonic and displacement power factor correction solutions are placed close to the causes of the problem. A facility’s internal electrical system can be better utilized, chances of harmonic related mysterious shutdowns are eliminated, and resonance cannot occur.

Parallel active harmonic filters (AHFs) use fast switching semiconductors to inject harmonic current onto ac lines. Microprocessor logic circuits monitor the total current of the load(s); determine the harmonic content; and control the switching sequence of the power semiconductors to inject a current waveform to exactly cancel and thus remove the bulk of the harmonic current.

AHFs are installed parallel to nonlinear loads, and use current transducers to monitor the load current. They do not use power factor capacitors. The power semiconductors are insulated gate bipolar transistors (IGBTs) that move power from the ac lines to a dc bus capacitor circuit and back to the ac lines in a prescribed manner. (Before the advent of IGBTs, active harmonic filters were ineffective and quite expensive.) Some AHFs can also measure and inject reactive current for system displacement power factor correction.

Historically, AHFs have been viewed as either did not working well or costing far too much. If only the initial equipment cost is considered, a 5th harmonic tuned filter will be cheaper. However, when all costs are included, AHFs are the most economical and the most complete solution.

Products are available commercially for use 1) on utility distribution lines, 2) at the point-of-common-coupling (PCC) for facilities to the utility, 3) within the three phase distribution system inside facilities, 4) on the three phase four wire facility distribution system, and 5) to remove neutral harmonics on three phase four wire systems.


Electronic Power Conditioning Inc. (EPC) is offering a series of compact AHF devices called AccuSine, in 50/100/300 amps sizes for placement close to loads. AccuSine can also be paralleled (up to 5 units) for larger requirements such as the utility interface when appropriate. It is designed with the fastest response possible — spectrum cancellation responds in 8 milliseconds (about 1/2 cycle). This approach will cancel interharmonics (noninteger multiples of the fundamental) above 60 Hz, where FFT cannot. This permits AccuSine to correct for “all” types of loads (eventually to include welders and arc furnaces).

With rapid switching of the IGBTs (20 kHZ), AccuSine cancels all harmonics up to the 50th order. Customers do not need to choose which specific orders or put up with limited range of orders to be canceled (as with products from other suppliers).


AccuSine is a flexible product, and can be used in many applications, for power factor correction only, harmonic cancellation only, or both simultaneously. It can be applied to single loads or on a bus for many loads.

Some frequent applications include:

VFD — Variable frequency drives are the largest group of harmonic polluters in use today. AccuSine eliminates the distortion of one or many VFDs depending upon the installation.

WWTP — Water and wastewater plants use many VFDs for pump and fan applications. With AccuSine the current harmonics can be limited to any amount desired, even to

Office Buildings — AccuSine will protect the tenants from VFDs on air handling units and DC drives on elevators. TDD can be kept

Generators — Generators are unstable and overheat when small amounts of the total load are nonlinear. Placing AccuSine between the generator and the loads converts the loads into linear loads. Thus full capacity can be used when PFC and harmonic suppression are both used.

UPS – Input & Output — UPSs create significant harmonic distortion on the AC lines. AccuSine will maintain TDD to

UPSs do not operate well with a high content of nonlinear loads on their output. AccuSine on the UPS output is the answer.

Plant Entrance Systems — IEEE 519-1992 requires harmonic current distortion emissions be held to defined levels. AccuSine on the low voltage system provides absolute compliance regardless of the load dynamics.

DC Motor Controls — DC drive applications have rapidly changing loads that create poor power factor and large amounts of harmonic current due to the SCR phase converter. Only AccuSine can remedy both the power factor and harmonic current pollution simultaneously and dynamically.


In June ’98, EPC announced the successful installation of an AccuSine Power Correction System at a wastewater treatment plant in Oregon, where variable frequency drives (VFDs) had been installed to improve control of raw sewage pumps and to decrease operating costs through variable speed operation. Interference with the computer management system was an unexpected complication. Noise pickup caused multiple logic errors. Sometimes erroneous warnings were sounded. Additionally, depending upon the total load of the VFD/raw sewage pump system, the circuit breaker protecting the management control system would trip thus shutting the plant down. If partially treated sewage is dumped into the adjacent river as a result of computer failure, substantial government fines occur.

After costly and time consuming on-site studies, harmonics from the VFD were determined to be the cause. The initial solution was to install an input line reactor (believed to be the lowest cost solution), which was partially successful. However, at near full load and speed conditions, the problem persisted. AccuSine has eliminated the problem.

This installation required an AccuSine rated at 50 amperes and 480 volts performing only harmonic cancellation to correct the harmonic current caused by a VFD rated at 125 horsepower. AccuSine has successfully reduced the total harmonic current distortion from 39% to 4% insuring trouble free operation of the plant.


EPC has a website with more information and a national list of reps.
(Available March 1 — in the meantime,
temporary site is

Contact: Jim Johnson, VP Sales 541-753-7220,
Electronic Power Conditioning, Inc. (Corvallis OR)

Additional ref: “Parallel Active Harmonic Filters: Economically Viable Technology”, Charles Gougler and James R. Johnson, IEEE PES Winter Power Meeting, Feb ’99