What in the world is a CEMS?

CEMS is the acronym for Continuous Emissions Monitoring Systems. Also related are COMS, which are Continuous Opacity Monitoring Systems. As stated in their name, these types of systems contain equipment that monitors emissions or opacity (opaqueness of gas) on a continuous basis. Readings from these systems are typically transferred to some sort of data acquisition and storage system that can then be used to show regulatory compliance.

How do CEMS work?

There are two common types of continuous emissions monitoring systems: extractive CEMS and dilution CEMS.

In a direct extractive system, the emissions monitor analyzes a direct sample of gaseous emissions from the stack on a dry basis. This sample is obtained from the stack or duct via a probe outfitted with a filter. It then passes through a sample line, through a sample conditioner and cooler (to remove moisture) until it finally reaches CEMS analyzer. These types of systems are best suited for processes that are not particularly wet, dirty, corrosive, or highly concentrated.

In a dilution system, the emissions monitor analyzes the gaseous sample on a wet basis that has been diluted with a known ratio of air. The gas sample is obtained and delivered to the monitor in a similar fashion as the extractive system except that the sample is diluted and delivered on a wet basis to the analyzer. The analyzer measures the sample and then outputs a corrected value based on the predetermined dilution ratio. These systems are best suited for processes that are very wet, corrosive, dirty, or highly concentrated in which a direct extractive CEMS would not be and viable solution.

In both cases, readings from the monitors are then typically transferred to a DAHS, (Data Acquisition and Handling System). The DAS provides operators with CEMS data and alarms displayed in real time. Often times, the DAHS interface allows for operation of certain functions on the CEM systems, such as calibrations, blowbacks, and other maintenance controls.

CEMS Applications

CEMS can measure a wide variety of pollutants. Most commonly monitored are nitrous oxide (NOx), sulfur dioxide (SO2), carbon monoxide (CO), and ammonia (NH3). Also typically monitored for emissions calculation purposes are oxygen (O2), carbon dioxide (CO2), moisture (H20), and velocity. Other examples of less commonly monitored pollutants are HCL, mercury, particulate matter (PM) and VOC’s.

A great number of different industries employ CEMS for regulatory purposes and process-related applications. These include but are no means limited to: power generation facilities, co-generation facilities, waste incinerators, smelters, glass manufacturers, lime manufacturers, metallic processing plants, and coating and sealant operations.

Most facilities install CEMS in compliance with regulatory requirements, but can also be used as a tool to assist with operation of the facility. Since data is presented in real time, processes can be adjusted and tweaked preventatively, before compliance violations occur and can also help the facility operate more efficiently. Additionally, since there are numerous quality assurance checks that take place on CEMS data, emissions reporting is very straightforward. Data is typically very solid and defendable if proper protocols are followed.

Air Tox has an excellent working relationship with numerous vendors of CEM equipment, and has more than 25 years of experience building custom CEM systems. Contact us for any inquiries or questions you may have regarding CEM systems today.

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Non-valid data alarms

We recommend setting up alarms for whenever data is invalid for reasons other than normal maintenance, calibrations, or process down conditions. We suggest that these alarms be split up by parameter (NOx, Opacity, etc.). In order to avoid having an alarm become a nuisance, we further suggest to implement a delay instead of having it sent out for every invalid minute. One method would be to create a rule to send the alarm for the first invalid minute, and then once every 15 minutes thereafter. Another possibility would be to only send an alarm only when 15 minutes or more of data is invalid.

Emissions Warnings

Ideally, these alarms would help control emissions before an excess emission is reached. Depending on limits and operating flexibility, the thresholds on these alarms vary. However, the alarm should be configured to provide the operators enough time to make minor adjustments to correct the emissions without disrupting the process unnecessarily. Sometimes it takes trial and error to find a good set point. For instance, 1-minute alarms are typically not very useful (unless for opacity), but a 1-hour alarm may be beneficial for controlling a 4-hour average.

Calibration drift alarms

Sometimes it is not always clear just by glancing at a calibration report if there has been a failure or significant drift or perhaps daily calibration checks are not reviewed on a daily basis. In those cases, implementing an alarm for a calibration failure or major drift can be helpful as a secondary check to ensure excessive downtime is avoided due to a daily calibration failure.

Specific Malfunction Alarms

Often analyzers have numerous internal operational alarms that can be beneficial for troubleshooting and avoiding catastrophic failures. If these are brought into the data system, operators can see them and alert maintenance personnel so they can be addressed in a timely fashion. These could be such things as internal temperature, pressure, or gas flow alarms, which could indicate an obstruction or part failure. There can also be alarms on other CEM system components, such as rack, shelter, and heated sample line temperatures. Any of these alarms can provide valuable advanced warning that something is wrong on the system before excessive downtime is incurred.

Are you questioning whether your CEMS alarms are configured properly? Air Tox can assist with reviewing your current alarm configuration and advise on best practices. Contact us here.

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EPA’s proposed Federal Plan under the Clean Power Plan
• For any state that does not submit an approvable state plan
• Contains three main parts:
o Rate-based model trading rule
o Mass-based model trading rule
o Rate-based OR mass-based federal plan (TBD)
• Has not yet been finalized

2008 Ozone NAAQS
• On April 11th 2016, EPA determined which marginal areas reached attainment by the July 2015 deadline, and which did not.
• For the list of those areas, follow this link: https://www.epa.gov/sites/production/files/2016-04/documents/20160411factsheet.pdf
• States that have been re-classified as “moderate” will need to resubmit a SIP for compliance by 2018.

2015 Ozone NAAQS
• Standard is now 70ppb
• Air Quality Index has also been updated-may look like air quality is getting worse but that is not the case.
• States will have to submit their recommendations for designations by October 2016
• EPA will issue final designations by October 2017

CSAPR Update
• EPA issued an update to CSAPR in fall 2015 order to help moderate areas achieve compliance with the 2008 ozone NAAQS
• This identified short term measures the power sector could make that would result in meaningful NOX reductions
o Optimizing operation of existing control technology
o Turning on controls that were idled
o Upgrading to state-of-the-art low NOX combustion controls
o Shifting generation to lower-emitting plants

The post EPA’s Year Ahead 2016 appeared first on Air Tox.

The EPA seeks comment on some specific parts of the rule:

• The EPA would like input on whether short-term NOx concentrations from EGU’s disproportionally affect downwind ozone concentrations. If so, what type of short-term emission limits (daily, monthly, etc.) would be appropriate to limit this impact?

• The EPA would like comments on what types of mitigation strategies for reducing EGU NOx by the 2017 ozone season are reasonable. Options may include:
  • Turning on idling SCR and SCNR’s
  • Upgrade, replace or install state-of-the-art combustion controls such as low-NOx burners or over-fire air
  • Shifting generation towards lower NOx-emitting EGU’s

• Whether or not non-EGU controls are feasible by the 2017 ozone season (this rule does not propose any, at this point)

Comments must be received by January 19, 2016.

For questions, feel free to contact Air Tox.

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The ruling focuses on PM emission limits that are phased in two steps. The first is a less stringent 2015 limit (2016/17 for forced air furnaces) and a secondary, more strict limit by 2020. The EPA estimates that the rule will yield $74 to $165 in benefits for every dollar spent on compliance. The EPA also encourages owners with older, less clean wood burning heaters to replace them with newer, cleaner options. For more details about the rule and compliance criteria, go to the EPA’s fact page here.

As always, please contact us with any questions you may have.

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Emission Limits

Source: U.S. Environmental Protection Agency

 Testing

• Initial Compliance Test (by March 21 2016)
• Annual Compliance Tests, and/or use of CEMS

Continuous Compliance

• Annual pollution control device inspections (based on control device)
• Monitoring of operating parameters and limits
  • including minimum operating or afterburner temp, feed rate of sludge, moisture content of sludge, and site specific operating requirements for fugitive ash
  • other specific requirements based on control device

Record keeping and Reporting

• Increments of Progress – 1st and 2nd increment
• Initial Compliance Report
• Annual report
• Deviation report
• Qualified operators status report (if a qualified operator is not available for 2 weeks or more)

Other

• All operators must be fully trained and qualified- “An SSI unit cannot be operated unless a fully trained and qualified SSI unit operator is accessible, either at the facility or can be at the facility within 1 hour”. An annual review/refresher course is also required. This documentation must be updated annually on site.
• A site-specific monitoring plan must be submitted before March 21 for each continuous monitoring system, bag leak detection system (if applicable), and for ash-handling.

The post What you need to know about the EPA’s new Sewage Sludge Incinerator Rule appeared first on Air Tox.

1. 17 of these areas will receive attainment status based on 2012-2014 certified data.

2. 8 areas will receive 1-year attainment date extensions based on their 4^th highest daily maximum 8-hour value in 2014.

3. 11 areas will be bumped to “moderate” status, as they did not meet attainment based on 2012-2014 certified data. This implies that a revised SIP must be submitted for affected states. The Moderate attainment deadline is July 20^th, 2018.

In Connecticut, the Greater Hartford area along with the New York, New Jersey, Long Island area (which includes part of CT) were not attaining and not eligible for a 1-year extension. Connecticut will have to revise their SIP accordingly.

For a complete list of EPA attainment/nonattainment area designations, see link below:

http://www.epa.gov/ozonepollution/pdfs/20150819fr.pdf

If you have any questions on how this may affect your facility, please contact AIRTOX.

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A calibration becomes out of control (OOC) when the cal drift value is 4 times the drift specification limit, or when the cal drift value is over 2 times the drift specification limit for 5 days in a row. The latter situation is for Part 60 calibrations only. For a Part 75 calibration, the data becomes invalid from the time of the failed calibration to the time of the next passing calibration. For Part 60 calibrations, data is invalidated back to the last good calibration up until the next passing calibration. In short, those invalid hours can add up pretty quick, especially with multiple OOC cals.

How to avoid:

• If a cal has been drifting over 2 times the drift limit for 3 days or more, make necessary adjustments and run a calibration until drift is under 2x the limit. This avoids having 5 days in a row of drift over 2x the limit.
• Recalibrate a failed cal as quickly as possible to minimize downtime
• Schedule regular maintenance on the analyzers to minimize chances of an analyzer malfunction
• Remember to change cal gas values in the DAS system when you change out a cal gas bottle. The calibration can be manually revalidated if this is the cause of an OOC cal, but this wastes time and can cause unnecessary confusion on site.
• Call Air Tox for help with adjusting and recalibrating analyzers. We have a 24×7 emergency service that can dial into your system at any time to perform calibrations.

Poor Maintenance:

An analyzer requires regular maintenance in order for it to function properly. The lack of regular maintenance can lead to major system failures, which can take up to days to correct.

How to avoid:

• Develop and maintain a regular maintenance schedule. An effective schedule will include weekly, quarterly, semi-annually, and annual items to be checked, tested and replaced. Air Tox can advise on what specific elements should be included in this schedule, and are experts at performing maintenance services.

Missed or Failed Audit Tests:

Audit tests such as a Linearity check, Cylinder Gas Audit (CGA), and Relative Accuracy Test Audit (RATA) are required on a quarterly and annual basis. Data becomes invalid on the expiration of the grace period for these audits, or when an audit is failed.

How to Avoid:

• Make sure you are aware of your site-specific audit requirements to ensure that the grace period for completing them is not missed.
• All involved parties should be familiar with testing protocols and procedures
• Complete quarterly maintenance before an audit so that analyzers are functioning at maximum potential
• Complete a daily calibration before the start of an audit
• If your facility has a flow monitor, running a flow test to verify the accuracy of the flow curve and velocity data is recommended before a RATA.
• Air Tox is extremely competent in performing all audit tests, and has a wealth of experience troubleshooting should a test fail for any reason.

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The EPA issued a final action on May 22, 2015 to ensure states have implementation plans in place for emissions to be fully compliant with the Clean Air Act (CAA) during periods of Startup, Shutdown and Malfunction (SSM). In the rule, there are 36 states that are required to correct specific SSM provisions and submit a State Implementation Plan (SIP) revision that addresses this action by November 22, 2016.

In the past, there have been some exemptions from emission limits during periods of SSM that have been approved by the EPA and adopted into SIPs. This final action by the EPA was issued, in part, as recent court decisions have challenged these SSM exemptions to the CAA (which have been allowed as affirmative defense provisions in the past), stating they cannot be allowed in SIPs.

If you are not sure how this rule is going to affect you, or if you need help ensuring that you will maintain compliance, contact Air Tox to see how our staff of experts can help you: info@airtoxenviro.com.

The post Startup, Shutdown and Malfunction Emissions – EPA Final Action appeared first on Air Tox.

The following are steps that states will take to comply with the plan:

1. Under the plan, states are given a unique target rate of CO2 emissions per unit of electricity generated to be achieved by 2030.
2. States will develop and submit action plans by 2016 of how they will achieve their assigned rate.
3. States must show meaningful progress towards their goal by 2020.

According to the EPA, under this plan, carbon dioxide pollution from the power sector will be reduced by 30% by 2030.

The Climate Action Plan allows states a large range of flexibility in developing their action plans, thereby letting states make the decision of when and where to make cuts in emissions. For instance, states can choose from a number of reduction strategies, including

• Co-firing or switching to natural gas only
• Retirements
• Efficiency improvements at plants
• Construction of natural gas combined-cycle plants
• Expanding renewable energy
• Multi-state cooperation programs
• Market-based trading incentives
• Energy conservation programs

It is the EPA’s intention that under this Climate Action Plan, states will be able to reduce harmful CO2 emissions all the while providing an incentive for innovation and guaranteeing a reliable and affordable energy system.

For more information, click on the link below:

http://www2.epa.gov/carbon-pollution-standards/clean-power-plan-proposed-rule

Slider reference: Rahm Emanuael/ CC-BY-SA-3.0

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