Air Pollution Control Innovations

Envitech has received an order from Tembec to supply an ammonia based red liquor recovery boiler scrubber for the Temiscaming sulfite pulping mill in Québec, Canada.   The scrubber system will treat the off-gas from an upstream sulfite power boiler supplied by Andritz and will meet stringent emission standards for particulate and SO₂.

This system is part of a $190-million power generation project that will upgrade Tembec’s existing specialty cellulose manufacturing facility.  The upgrade will increase annual green energy production by up to 40-megawatts, reduce sulfur dioxide emissions by 70%, and increase annual production capacity of specialty cellulose by 5,000 metric tonnes.  The upgrade will make Temiscaming one of the lowest-cost specialty cellulose manufacturing facilities in the world.

The scrubber system is engineered to Tembec’s requirements and is the result of close collaboration with the customer over several months and their engineering firm Pöyry.   The design leverages experience from several other large volumetric flow rate applications including a coal dryer scrubber, secondary lead smelter wet electrostatic precipitator (WESP) system, and a hazardous waste incinerator scrubber.  The scope of supply includes an inlet duct from the boiler exhaust fan, quencher, ammonia scrubber, condenser, WESP, caustic scrubber, heat exchangers, structural steel, access platforms, and stack.  Primary vessels will be shop fabricated and shipped to the site for assembly and installation.  This provides a lower total installed cost, greater quality control over manufacturing, and shorter delivery and installation time.  System start-up will occur in the fall of 2013.

To read more about this system, download the case study below.

A common application for Venturi scrubbers is potash mining.  Venturi scrubbers are used to remove particulate from industrial dryers that dry the potash material.  A cyclonic separator or chevron style entrainment separatordownstream of the Venturi removes particulate–laden water droplets from the gas before it is exhausted into the atmosphere.  The type of entrainment separator can impact the system performance and make a significant difference in plant emissions.  A well designed chevron style mist eliminator achieves significantly lower emissions than a cyclonic separator.  This is because the chevron style mist eliminator allows the Venturi scrubber to operated at a higher pressure drop for the same system pressure drop. The chevron entrainment separator is also more efficient at removing water drops.

A chevron style mist eliminator removes more than 99% of the water droplets down to 25 microns with less than 0.25 inches W.C. of pressure drop.  By comparison, a cyclonic mist eliminator requires 4 to 6 inches W.C. of pressure drop to remove 98% of 25 micron droplets.  The additional pressure drop required by the cyclonic separator effectively reduces the pressure drop that can be applied to the Venturi throat and consequently lowers collection efficiency.  The additional water droplets that escape the cyclonic separator (98% vs. 99% removal for 25 micron water droplets) contain particulate which will impact stack test results.

Consider an air permit for a potash facility located in the Southwestern United States.  The permit allows for the operation of two 2 dryer systems, each with a Venturi scrubber. The dryers contribute significantly to the facility wide total suspended particulate (TSP) emissions.  A typical potash dryer for this size of facility exhausts around 40,000 acfm with a particulate loading as high as 3 gr/dscf.  This is a little more than half a ton per hour of particulate for both dryers.

Venturi scrubbers with cyclonic separators designed for 99% removal result in approximately 10.4 lb/hr of particulate emissions for both scrubbers or 46 tpy. However, an equivalent Venturi scrubber with a chevron style mist eliminator achieves 99.9% removal. This results in less than 1 lb/hr of particulate emissions for both dryers, or less than 5 tpy. The higher performing Venturi scrubber design reduces plant emissions by over 40 tpy. This performance increase can have a significant difference in air quality for the surrounding community.

To download a case study on dryer Venturi scrubber, please click on the download button below.

In previous blog posts we have discussed our continuing progress in the development and implementation of SO₂ Scrubber technology to control marine diesel engine emissions. We have recently finished manufacturing an exhaust gas cleaning system for SO₂ removal which is to be installed at a state of the art maritime engine test facility equipped with a 3MW diesel engine. Soon we will begin testing our system under a wide variety of conditions to fine-tune and validate our marine diesel engine emissions scrubbing technology. Once the testing is complete, we will apply for a maritime registration for our control technology.

Regulations on exhaust gas emitted from marine diesel engines are becoming increasingly stricter. The recently implemented MARPOL Annex VI specifies that the fuel used to power large sea bearing vessels must contain no more that 3.5% sulfur oxides by weight in non-Emission Control Areas and no more that 1.0% by weight in designated Emission Control Areas. This allowable weight percentage of SO_x will drastically decrease to 0.5% in 2020 for non-Emission Control Areas and 0.1% in designated Emission Control areas. One can easily predict that fuel expenses for ship-owners will increase along with the requirement for the use of lower sulfur content fuel. An economical alternative to using this more expensive fuel is to install a secondary exhaust gas cleaning system such as an SO₂ scrubber to clean diesel engine emissions before they are released to the atmosphere.

In addition to Envitech’s new ship-based marine diesel engine SO₂ scrubber demonstration system, we have seen continued success with meeting SO₂ emission limits with our land-based SO₂ marine scrubber which was installed this past March at the Port of Long Beach in Southern California. Our land based scrubber is used to clean the stack gases of ships that need to continue to run their engines to generate power while docked.

To read more about our products for marine diesel engines, download the case study below.

I recently came back from the 2012 Coal-Gen Conference in Louisville, KY. There were some interesting discussions from the plenary session with key note speakers that included assistant EPA administrator Gina McCarthy, Alstom President and CEO Pierre Gauthier, Louisville Gas & Electric VP of Transmission and Generation John Voyles, and Burns & McDonnell Engineering President & CEO Greg Graves.  A press update can be found on the Coal-Gen website.  Below is a summary of some of the take-away comments I heard from the speakers:

• Substantial reductions in air emissions (SOx and NOx) of up to 85% have been achieved since 1995.
• The costs to achieve those reductions were lower than originally forecast.
• The cost to achieve the next smaller incremental reduction is estimated to be as high as reductions achieved to date.
• Coal will continue to play a large role in US energy production.
• The EPA has the express goal to create a pathway for coal to continue as a major source of energy.
• Carbon emission limits are viewed as the biggest long -term threat to coal.
• Carbon Capture and Sequestration (CCS) for meeting carbon emission limits is considered feasible but not yet proven.
• There is currently no financial mechanism for industry to make substantial investments needed to develop and implement CCS.
• Natural gas (NG) has become a strong competitor to coal for new facilities and will play a significant role in energy production for years to come.

It was said that the carbon emission limits for utility plants are based on what is achievable using NG.  Conventional coal fired power plants have a higher carbon footprint than NG which threatens coal’s ability to meet future standards.  I was surprised there was no discussion of coal gasification as a strategy to meet future carbon emission limits.  During the conference I gave a presentation on a coal dryer scrubber that is part of just such a new facility.  The coal gasification plant is designed to reduce carbon dioxide emissions by as much as 65% compared to conventional coal fired power plants.

The discussion was interesting because of the nexus between industry and mainstream public awareness of energy policy.  I couldn’t help feel concern about the challenges ahead, but also optimism stemming from the remarkable achievements over the last several decades.

I can put these achievements into perspective from my own life experience.  My senior year in highscool I moved to California from Kansas City.  I lived with my grandparents in Redlands, California. Redlands is in San Bernardino County nestled in the hills just south of the San Bernardino mountain range.  That year in the summer of 1981 the smog was so bad the tops of the palm trees would be obscured. Even though Redlands is surrounded by several majestic mountains including Mt. Baldy, San Bernardino Mountains, and Mt. Gorgonio, you could barely see them from a short distance away.

I joined the football team and in August we had to do 2 practices a day.  At 3:00 pm each day, like clockwork, a thick brown, cloud of smog would roll down the valley from Los Angeles.  The cloud would envelope the football field like something out of the horror movie, “the fog”.  The team would continue to practice hard in the heat and smog.  At night, I would go home to my Grandparents house and hack for 2 hours from all the dirty smog I had been breathing in that day.  It’s hard to describe just how awful the smog was in the early 80's.

Today, the situation in Southern California is substantially improved.  I often drive up to LA or San Bernardino from San Diego for projects we’re doing in the area.  On most days you can see the San Bernardino mountain range from as far away as Temecula as you come over the hill.  This is a distance of over 65 miles.  Southern CA still has bad days, but the situation is dramatically improved from the dark, brown clouds of smog that used to invade the LA basin in 1981.  The visible improvement is supported by data that has been taken over that same period of time.  SOx and NOx reductions have declined substantially since the early 80’s and in the face of increasing populations.  SCAQMD has recently implemented a SOx and NOx Reclaim Program to make further reductions in the area.

There is no question that meeting tough regulatory standards are difficult, but based on my own experience living in Southern California over the last 30 years, they have made a tremendous difference in the quality of life form millions of people.  I think sometimes these improvements are underappreciated because they are gradual and occur over a long period of time.  What seems certain is that American ingenuity always seems ready and able to meet the challenge.

Click on the icon below to download a copy of the Coal Dryer Scrubber presentation from the 2012 Coal-Gen conference.

I will be giving a presentation at the 2012 Coal-Gen Conference on a Coal Dryer Scrubber for Integrated Gasification Combined Cycle Power (IGCC).  The conference will be held in Louisville, KY at the International Louisville Convention Center, August 15-17^th, 2012.   The presentation will be given between 1:30 pm to 3:00 pm on Wednesday, August 15^th in Section 4A, Particulate Control in Material Handling System.

The scrubber is an innovative design for a large volumetric flow rate (2.1M cfm) Venturi Scrubber – condenser system.  Below is the abstract for the presentation. 

ABSTRACT

A 582-megawatt (MW) electric generating plant in the South Eastern United States is scheduled to be operational in 2014.  The facility uses state-of-the-art gasification technology and is an Integrated Gasification Combined Cycle (IGCC) plant.  The process uses locally mined lignite coal for fuel.  The coal has high moisture and must be dried before it is converted to syngas in the gasification process. The coal dryer uses nitrogen for the carrier gas which passes through a Venturi Scrubber-Condenser System to remove particulate and condense moisture before it is re-circulated back to the dryer. The Venturi Scrubber-Condenser System is sized for over 2.1 million cubic feet per minute (cfm) of gas divided into 6 trains.

Two arrangements for meeting the specification requirements were evaluated for the system design including: 1) a single train consisting of one Venturi scrubber and one cyclonic separator-condenser per train, and 2) a modular arrangement consisting of four separate Venturi’s and four cyclonic-separator-condensers per train.  This presentation will discuss the design considerations in evaluating the optimum arrangement and the derived benefits from the final configuration.   Some of the benefits include lower capital and installation cost, better corrosion resistance, smaller footprint, and greater operating performance.

To view an installation video of the Coal Dryer Venturi Scrubber-Condenser, click on the icon below.

 To download the 2012 Coal-Gen Conference presentation, click on the icon below.

I’ve made several blog posts regarding the removal of hazardous air pollutant (HAPs), including lead, from a secondary lead smelter in CA using a Wet Electrostatic Precipitator (WESP). There is also an article published in the August 2010 issue of Pollution Engineering on this system.  My last blog post references a letter to the EPA reporting metals reductions as high as 98% and 99% and reductions of lead from 615 lb/yr to 1.22 lb/hr.  The facility is now achieving emissions that are several orders of magnitude lower than other secondary lead smelters.

Envitech is in the design phase for a new project that will apply the WESP technology to an industrial facility that has lead emissions similar to stack emissions from a controlled secondary lead facility.  The WESP system guarantees 95% lead removal from inlet concentrations of 0.003 gr/dscf.

The system was selected after the facility performed a thorough evaluation of different technologies including HEPA and cartridge filters as well as other WESP suppliers.   The system will be operational in Q1 2013 with stack test results due by the middle of 2013.

Envitech is implementing cost reductions that will enable reduced capital expenditure for future installations and make the technology more economically feasible to be considered best available control technology (BACT) by the EPA.   This new system will be a good surrogate to further demonstrate the performance of the Envitech WESP system to get the lead out!

Click on the link below to download a white paper from the International Conference on Thermal Treatment Technologies and Hazardous Waste Combustions (IT3/HWC) on a WESP system for a secondary lead smelter.

In previous blog posts I discussed an ultra-low SO2 (sulfur dioxide) scrubber using a 2-stage packed bed scrubber design.  The system treats the off-gas from a thermal oxidizer that oxidizes the waste gas streams from various sources at a waste oil re-refining facility in Southern, California.  The low emission limit enables the facility to remain outside of the South Coast Air Quality Management District (SCAQMD) Regional Clean Air Incentives Market   RECLAIM program.  To meet this objective, the scrubber system has to meet an emission limit of < 2.7 ppm outlet emission with an inlet load of approximately 104 lb/hr.  The limit must be met on a continuous basis which is monitored by a CEMs unit provided by Cemtek.  Envitech provided the scrubber as a turn-key installation and recently turned the system over to facility operations personnel. The CEMs unit is reporting emissions of < 0.5 ppm, well below the permit limit.

Please click on the icon below to download a paper on the scrubber system. 

In 2010 I blogged about a Marine Scrubber system to remove SO₂ from marine diesel engine exhaust gas.  This month, Envitech completed a 3MW marine diesel engine SO2 scrubber that will be used to clean the stack gases of ships while at dock at the Port of Long Beach, CA.   The scrubber will be used for the Advanced Maritime Emissions Control System (AMECs) by Advanced Cleanup Technologies, Inc..    The system will undergo duration tests at the port during 2012 and 2013 with the goal of obtaining a verification certificate by the California Air Resources Board (CARB). 

The AMECs system is a stationary system that uses a bonnet to capture the exhaust gas from the ships stack while at port. The exhaust gases are conveyed to the AMEC system to clean the gases of particulate (PM), NOx and SOx before exhausting to atmosphere. This allows the ship to operate its auxiliary engines and boiler system while at port to provide power to the ship.  The AMECs system provides a cost effective way for ships and port operators to reduce emissions and to meet tougher regulatory standards. 

In a parallel track, the maritime industry is looking for ways to meet tougher standards not only at port but while operating at sea based on the IMO Annex VI MARIPOL Tier III requirements. Envitech continues to develop De-SOx technology options for ship based marine diesel engines.  We are currently building a 3MW marine diesel SO₂ scrubber system that will be used in a demonstration unit for a complete after treatment system for SOx and NOx. The system will undergo validation testing in a state of the art marine engineering facility.  Testing will begin before the end of this year.

Please click on the icon below to download a case study on the Envitech HYSEA DeSOx scrubber.

In 2009 I gave a paper at International Conference on Thermal Treatment Technologies (IT3) on a wet electrostatic precipitator (WESP) system for the Quemetco secondary lead smelting facility in Southern California.  It was explained that the system was an add-on control to help the plant meet a cancer risk index by removing low concentrations of metals.  The facility was meeting stack emission limits and had similar control technology used by other facilities in the industry including bag-houses, HEPA filters, and wet scrubbers. Because residential neighborhoods had moved closer to the boundaries of the plant over the years, the stack emission limits were insufficient to meet the cancer risk index.  In other words, the facility had to achieve lower emission levels than other similar plants. The WESP system was installed in 2007 and provided a performance guarantee for arsenic, lead, and nickel which were the larger contributors to the cancer risk index.

In May 2011, the EPA released the new National Emissions Standards for Hazardous Air Pollutants (NESHAP) for secondary lead smelting facilities.  The report sites in section III.B.2 that two of the 14 secondary lead smelting facilities have estimated actual lead emission only moderately lower than the allowable emission level (about 2-3 time lower).  The majority of the other facilities have estimated actual emissions in the range of 10 to 100 times lower than allowable.  However, one facility with highly advanced controls has an estimated actual emission of about 1,500 times below allowable emission levels. This facility is the Quemetco facility operating with a WESP system.  It can be surmised the plant is achieving emission levels 15 to 150 times lower than the other lead smelting facilities.

In June of 2010 a public letter on behalf of RSR Corporation (Quemetco) was presented to Mr. Charles French, Metals and Minerals Group, of the EPA. The letter states that the WESP system yielded dramatic reductions in air emissions from its operations.  The cancer risk was reduced by 87% to 2.88 cancer cases in one million exposed individuals over a 70-year evaluation period.  Prior to installation of the WESP, Quemetco emitted 615 pound of lead annually.  The letter reports that lead emissions plummeted to 1.22 pounds per year – a 99.8 percent reduction.  A table is provided in the letter that summarizes significant reductions of other hazardous air pollutants. Some of the reported metals reductions include the following: 

The data presented in the letter is consistent with the initial stack test data that was shared with Envitech following the installation.  Although the system provided a guarantee for only three metal compounds, we expected similar removal for any condensed metal at the inlet of the WESP.  The data demonstrates this was the case.

The consistent performance since the installation in 2007 demonstrates the tremendous capability of the WESP system to achieve dramatic reductions of condensed metals in a robust fashion for a process that must operate 24/7/365 days per year.

For a copy of the full paper, please download the white paper below.

Last month I attended the 30^th International Conference on Thermal Treatment Technologies & Hazardous Waste Combustors (IT3).  The conference was held May 10-13 in Jacksonville Florida.  The IT3 Conference provides a forum for the discussion of state-of-the-art technical information, regulations, and public policy on thermal treatment technologies and their relationship to air emissions, greenhouse gases and climate change.  Envitech has been a long time participate of the conference dating back to our founding in 1994 and this year was a sponsor for the annual meeting.

It was announced during the Program Advisory Committee (PAC) meeting that I will be the new Vice Technical Chair for the conference.  Roy Cross of AMEC (formerly MACTEC) will hold the past Chair position and Gary Elliott of Lafarge North America will be the acting chair.  I look forward to working with this group to plan next year’s conference and to help the conference grow.

This year’s conference had several worthwhile technical tracks ranging from Biomass, Waste-to-Energy, Alternatives to Incineration, and Multi-Metal CEMs.  Particularly noteworthy were the sessions on Regulators Perspective on HWC MACT Implementation and An Introduction to Recently Announced Combustion MACT Regulations. These sessions were haired by Mel Keener of the Coalition for Responsible Waste Incineration (CRWI) and co-chaired by Heather McHale of Coterie Environmental.  The sessions were well attended by conference attendees.  The Regulators Perspective included 3 U.S. EPA representatives, Frank Behan, Charlie Hall – Region 5, and Kishor Fuitwala – Region 6, as well as to representatives from Alabama Department of Environmental Management (DEM).  The session on MACT regulations included the, non-hazardous solid waste rule, industrial boiler and process heater rule, commercial and industrial solid waste incinerator rule, Portland cement rule, Hospital/Medical/Infectious Waste Incineration Rule, Sewage Sludge Incinerator Rule, and the Electric Utilities rule. Many of these rules had recent updates that will impact owners/operators.  The presentations were designed to explain the impact and timelines or the recent rule changes.

For a white paper from the conference on ultra low SO₂ control for thermal oxidizers, click on the link below.