Air Pollution Control Innovations

Sewage Sludge Incinerator Mercury Control Scrubber

Posted by Andy Bartocci on Mon, May 13, 2019 @ 04:53 PM

A municipal waste water treatment plant operates a 2,750 lb/hr fluid bed sewage sludge incinerator (SSI). The Mecury Control Renderingincinerator had been shut down due to safety issues with the granulated activated carbon (GAC) mercury control scrubber. The plant sought expert help to evaluate and recommend a technology solution to replace the GAC and to get the SSI back in operation.

Based on extensive waste incineration gas cleaning experience, the facility contracted Envitech to evaluate the process, make recommendations, and implement a solution.

Envitech reviewedMercury Control Scrubber available literature and data to establish a conservative but justifiable design inlet concentration with sufficient capacity to meet a more conservative design condition without structural changes to the equipment.

An additional Envitech study compared W.L. Gore sorbent polymer catalyst (SPC) mercury control modules to sulfur impregnated activated carbon taking into account capital and operating cost, mercury removal efficiency, safety, and performance risk. The facility implemented Envitech’s recommendation for an Envitech SBC mercury control scrubber. A vessel constructed of fiber reinforced plastic (FRP) provides excellent corrosion resistance and low cost. An inlet heater duct with controls optimizes temperature for maximum performance. An internal duct with bottom outlet near grade direct connects to the existing stack. The vessel has extra capacity to double the number of SPC modules to meet the conservative inlet concentration if needed.

The equipment was commissioned in December, 2018. Inlet and outlet stack tests confirm greater than 96.4% removal and emissions less than 5% of the MACT limit for existing FB SSI. The Envitech SPC mercury control scrubber provides an economic, high performance, safe solution for continued incineration operation.  It can be applied to other types of applications that require mercury control downstream of wet scrubber equipment.  It provides a worthwhile technology to consider for mercury control.

Click on the link below to download a sewage sludge incinerator (SSI) mercury control scrubber case study and other SSI incinerator scrubbing literature.

 

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Topics: Scrubbers, MACT Standards, Incinerator Scrubber

Ozone Injection NOx Control for Medical Waste Incinerators

Posted by Andy Bartocci on Tue, Oct 30, 2018 @ 12:39 PM

Early this year I posted about achieving ultra-low emission limits for medical waste incinerator scrubbers.Med waste incinerator scrubber Front  An example was given for a captive incinerator at the University of Texas Medical Branch (UTMB) in Galveston, TX. It’s one of the only systems in the United States permitted as a “new” medical waste incinerator according to the EPA HMIWI (hospital, medical, and infectious waste incinerator) MACT standard. This standard has the most challenging emission limits found in industry today. That is because in 2009 the EPA completed a source review and revised the standard based on a MACT-on-MACT analysis.  Data used to set limits for each pollutant was individually based on waste feed and not incinerator/scrubber technology performance.  This resulted in emission limit reductions for lead (Pb), cadmium (Cd), and dioxins/furans (D/F) that were orders of magnitude below the previous standard and below the capability of installed equipment.  The impact of the new standard is discussed in greater detail in a 2013 blog post and corresponding paper from the Air & Waste Management Association (AWMA) International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC)..
Medical waste incinerator Scrubber add-on controlsExisting incinerators needed to be upgraded with add-on controls to meet the new standard.  New incinerators need air pollution control equipment capable of extraordinarily high removal efficiency for particulate, Pb, Cd, and D/F.  A new medium sized incinerator between 200 to 500 lb/hr capacity, has the additional challenge of meeting NOx.  A medical waste incinerator can be tuned to a NOx limit of about 130 ppmv.  The MACT standard limit for a new medium sized medical waste incinerator was set at 67 ppmv which means NOx abatement is required to guarantee compliance.

Envitech is building two scrubber systems to treat exhaust gases from two new medical waste incinerators that will treat captive waste at a research facility.  The incinerators are permitted as new medium size incinerators which must meet the 67 ppmv NOx limit. The scrubbers have an equipment arrangement for meeting emission standards for PM, HCl, SO2, Pb, Cd, Hg, D/F, and opacity.  The schematic below shows the components of the gas cleaning system. The quencher is used to cool the gas to saturation and remove large particulate. The packed bed condenser/absorber sub-cools the gas and removes acid gases with caustic injection. The Venturi scrubber removes particulate and the majority of heavy metals. The gas then passes through additional polishing controls to meet the ultra-low emission limits for Pd, Cd, Hg, and D/F. The polishing equipment includes a re-heat duct followed by a filter and carbon bed adsorber.Med waste scrubber PFD

NOx removal is achieved by injecting ozone injection into the quencher outlet. The sizIMG_1032 Backside 1e of the condenser/absorber is increased to provide sufficient residence time for ozone-NOx reactions to occur.  Ozone is highly selective for NOx relative to other combustion products.   The NOx is rapidly converted to water soluble species. NO and O3 react to form NO2 and O2.  NO2 and O2 react to form N2O5 and O2. N2O5 and water react to form 2HNO3 which is readily absorbed with caustic solution.

Envitech used it’s rectangular scrubber design for the condenser absorber. To maintain a modular design and make it shippable.  The vessel was flanged connected and shipped in two pieces. The scrubber system otherwise looks like a typical medical waste incinerator scrubber except the condenser/absorber is double the height compared to systems that do not require NOx control.

The system has been built and shipped to the site. The major components are installed at the facility.  Envitech will deliver a water treatment system in 2019 to treat the scrubber effluent before it is discharged to the facilities main water treatment system.  System Start-up is scheduled for 2020.

Click on the link below to download a case study and other medical waste incinerator scrubbing literature.

 Download Literature

Topics: Scrubbers, Acid Gas, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, NOx

Achieving Ultra-low Emission Limits for Medical Waste Incinerator Scrubbers

Posted by Andy Bartocci on Wed, May 16, 2018 @ 08:00 AM

Last March I gave a paper and presentation at the International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC) in Houston, TX.  The paper discusses the challenges for meeting ultra-low emission limits for medical waste incinerators. 1102_UTMB_Scrubber_Skid Wet scrubbers are used to control hazardous air pollutants (HAPs) on many hospital, medical, and infectious waste incinerators (HMIWI).   The Maximum Available Control Technology (MACT) standard for these incinerators was revised and became final in 2009.  The new standard has the lowest emission limits for incinerators today. The limits exceeded the capability of systems designed to the previous standard with respect to particulate matter (PM), lead (Pd), cadmium (Cd), mercury (Hg), and dioxin/furans (D/F).  By 2014 all existing medical waste incinerators were either shut down or upgraded to comply with the new standard.  Envitech successfully upgraded four existing medical waste incinerators.  A paper presented at the 2012 IT3/HWC conference describes one of these systems which was installed at the National Institute of Health (NIH), Rocky Mountain Labs.

The challenge moving fo1102_General_Assembly_1rward will be new medical waste incinerators which have even more stringent, ultra-low emission limits.  Building a new incinerator requires critical decisions on control technologies and permitting.  The IT3/HWC paper reviews these issues for specific HAPs and discuss trade-offs between permitting a new medium size incinerator versus a large incinerator.   An example is provided of an air pollution control system meeting the emission requirements for a new large medical waste incinerator at the University of Texas Medical Branch (UTMB) in Galveston, TX.  Envitech is also building gas cleaning systems for two new medium size medical waste incinerators for a research facility which integrate NOx control using ozone injection.

 

Please click on the links below download the presentation and paper.

 Download Literature

Topics: Scrubbers, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

Carbon Bed Adsorber and Filter Used to Remove Lead (Pb), Dioxin, Furans, and Mercury (Hg) to Meet New Medical Waste Incinerator Emission Limits

Posted by Andy Bartocci on Thu, Apr 14, 2016 @ 08:30 PM

WMC.jpgIn 2009, the US EPA revised the emission limits for the Hospital, Medical, and Infectious Waste Incinerator (HMIWI) MACT standard. You can follow the link to the blog piece published in May 2013 on the new standard. It dramatically reduced the emission limits for several pollutants including particulate (PM), lead (Pb), and dioxins and furans (D/F). Several existing medical waste incinerators in operation at the time were not capable of meeting the new limits, especially for lead (Pb) and/or dioxin and furans (D/F). Cost effective add-on controls were needed to bring existing system into compliance with the new rules and to allow them to continue to operate.

 

To meet this new challenge, Envitech designed a carbon bed adsorber and filter package to be installed downstream of existing wet scrubbers. The package is comprised of a new fan to overcome additional system pressure drop. Heat of compression from the fan and a re-heater duct heats the wet gas above the dew point to prevent condensation fouling in downstream filter and/or carbon bed adsorber. The system is delivered pre-assembled on a skid to reduce installation time and cost. A cartridge filter removes low concentrations of condensed Pb particulate. The carbon bed adsorber removes dioxins, furans and mercury (Hg). Envitech has upgraded four medical waste incinerators to meet the new MACT standards. All four are operational and compliant with the new standards.

In one case for Wyoming Medical Center (WMC), space was limited for add-on controls. The system had to be installed outdoors and capable of withstanding below freezing temperatures. The existing system did not meet the new limits for lead (Pb) and dioxins/furnace (D/F).The add-on controls included a cartridge filter and a carbon bed adsorber. The equipment was insulated and heat traced to maintain temperature above the dew point after re-heat. System features include:

  •  Shop and skid mounted assembly for ease of installation.
  • Insulation and heat tracing for outdoor operation in a cold climate.
  • Silicon controlled rectifier (SCR) controller to control the heater duct.
  • Compressed air pulse cleaning for automatic particulate removal from the cartridge filters.
  • Pre-wired instrumentation to a control box located on the skid.
  • Manways to facilitate maintenance access.

The system has been operational since 2014 and has been used on a routine basis during cold winter months.   The system comfortably passed a stack test in 2015. Compliance for lead (Pd) is 20 times below the limit and Dioxins/Furans (D/F) is 5 times below the limit. The re-heat and filter package has been used on several other medical waste incinerators and provide a cost effective solution for meeting stringent emission limits. 

Download a free case study to find out how Wymoming Medical Center met the new EPA HMIWI emission limits for their existing medical waste incinerator.

Download  Case Study

Download a free white paper from the 2010 Internationa Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC) on the 2009 HMIWI MACT standard for medicl waste incinerators.

Download Free Paper 

Topics: particulate control, Venturi scrubbers, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

IT3/HWC 2015 Conference October 20-22, 2015 – Wet Electrostatic Precipitator for Medical Waste Incinerators

Posted by Andy Bartocci on Tue, Sep 22, 2015 @ 01:47 PM

Envitech will attend the International Conference on Thermal Treatment Technologies (IT3/HWC), October 20-22, 2015 at the Crowne Plaza Hotel in downtown, Houston, Texas.  The preliminary technical program can be downloaded from the conference website.   The conference features key note speakers from Veolia, Clean Harbors, Essroc, TCEQ, and B3 Systems.

Envitech will have an exhibit booth and present a paper, “Meeting the New Hospital, Medical, and Infectious Waste Incinerator (HMIWI) MACT with a Wet Electrostatic Precipitator (WESP)”.  The paper will provide an overview of a new medical waste incinerator scrubber system with a wet electrostatic precipitator to treat the off gas from two existing medical waste incinerators. The new system was required to achieve a 20% reduction in particulate (PM) emissions, and a 93% reduction in lead (Pb) emissions from the previous gas cleaning system.  The new system has been operational since October 2014.  The table below compares the performance of the emission limits to the new compliance standards. The results demonstrate the system comfortably meets the new EPA MACT standards.

 

Pollutant

 

Units

Compliance

Limit

Test Result

% of limit

Particulates, EPA Method 5 gr/dscf 0.020 15%
Pb EPA Method 29 mg/dscm 0.018 6%
Cd, EPA Method 29 mg/dscm 0.013 10%
Hg mg/dscm 0.025 1.0%
Dioxins/furans, EPA Method 23 Total (ng/dscm) 0.85 5%
  TEQ (ng/dscm) 0.020 15%
HCl, EPA Method 26 ppmv 7.7 1.6%
SO2 ppmv 4.2 35%

Click on the icon below to download a copy of the paper.

Free_Paper

Topics: particulate control, Venturi scrubbers, wet electrostatic precipitators, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

Medical Waste Incinerator Scrubber Used to Process Ebola Waste

Posted by Andy Bartocci on Wed, Nov 05, 2014 @ 08:43 PM

Envitech recently got noticed in a local news story by Michael Chen of Channel 10 News, “Local Company Helps Dispose of Ebola-tainted Waste”.  The story talks about the challenges of processing Ebola waste and how Envitech’s Medical Waste Incinerator Scrubber at the University of Texas Medical Branch (UTMB) was used to dispose of waste generated by an Ebola patient in Texas.

UTMB operates the only permitted medical waste incinerator in the state of Texas.  Since 1991 the facility has operated an incinerator which uses an Envitech wet scrubber system to clean the exhaust gases of harmful pollutants.  A new incinerator system was recently installed to meet the new EPA rules promulgated for the hospital, medical, and infectious waste incinerator (HMIWI) maximum achievable control technology (MACT) standard.  The impact of these rules is discussed in a previous blog post.

The outlet emission requirements of the new standards are a significant reduction from the previous 1997 standards.  The allowable outlet emissions for many of the metals, i.e. lead (Pd), Cadmium (Cd) are less than 1% of the previous emission limits. For example, the allowable concentrations for Pb,and Cd are measured in 10-7 and 10-8 gr/dscf, respectively.  These are some of the lowest HAPs emission limits for industrial sources in the United States. Medical Waste Scrubber Below is a summary performance guarantee for the new scrubber system based on the new HMIWI standard:

  • PM < 18.3 mg/dscm (0.008 gr/dscf)
  • Lead < 0.00069 mg/dscm (3.0 x 10-7 gr/dscf)
  • Cd < 0.00013 mg/dscm (5.7 x 10-8 gr/dscf)
  • HCl < 5.1 ppmv dry
  • SO2 < 8.1 ppmv dry
  • Dioxins/Furans < 0.035 ng/dscm on TEQ basis

Recent episodes of processing highly infectious waste from Ebola patients may re-ignite a policy debate on medical waste disposal. In the early 1990, many hospitals were going to a model of owning and operating a relatively small medical waste incinerator to process and destroy medical waste generated in-house. These systems typically have a capacity of 500 to 1,500 lb/hr. As air emission standards became stricter, many hospitals decided to shut down their incinerators and ship their waste to larger, centralized medical waste incinerators. These systems are much larger in capacity. For example, the largest medical waste incinerator facility is in Baltimore, MD with a permitted capacity of 150 ton/hr. The trade-off of a centralized waste incinerator is the risk and liability of transporting the waste on public roads and highways. The recent Ebola outbreaks bring to light that some of this waste can be highly infectious and pose a significantly greater risk to public health. It also came to light that a single Ebola patient generates a substantial amount of infectious waste. In this scenario, it may make more sense for facilities to have the capacity to destroy their own waste and avoid the risk of transporting it over great distances on public roads.

The advancement of scrubber technology and compliance with the new, more stringent EPA MACT standards, confirm the ability to operate medical waste incinerators with virtually no harmful emissions into the air.  In addition to the UTMB medical waste scrubber system, Envitech has upgraded several other medical waste incinerators for meeting the new standards.  Based on the extreme low emission limits, the results are truly groundbreaking and may encourage states and facilities to permit new systems.

For more information on HMIWI regulations, please read our white paper.

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Topics: Venturi scrubbers, MACT Standards, Ebola Waste, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber