If you are reading this, there is a very good chance that you have come in contact with the latest EPA regulations affecting diesel and gas engines, most commonly known as RICE NESHAP. With over 900,000 engines estimated to be affected, there are lots of people searching for knowledge on the requirements of this new ruling. As with any Federal regulations, the reading can be extensive, confusing and the process to achieving compliance quite intimidating.
If you are the owner/operator for an affected engine, you should know that compliance is relatively simple, once you have identified your need to comply. This initial determination might be the most difficult part. This article will provide a brief background on the RICE NESHAP rules, tools to help you determine any applicability to your specific situation, and some suggestions on how to navigate through the process of selecting the right organization and equipment to achieve compliance in the least disruptive way.
First, some background on the rule itself…
As part of an effort to reduce engine emissions, the U.S. Environmental Protection Agency (EPA) adopted new national emission standards for hazardous air pollutants (NESHAP) in 2010. The new regulations apply to existing stationary compression ignition (CI) and spark ignition (SI) reciprocating internal combustion engines at area and major sources of hazardous air pollutants (HAPs). Compliance to the new standards is required by 2013.
A compression ignition (CI) engine is a diesel engine, whereas a spark-ignited engine is fueled by a gaseous fuel (i.e.: natural gas). RICE NESHAP is an acronym for Reciprocating Internal Combustion Engines National Emissions Standards for Hazardous Air Pollutants. Unless you operate a substantial power plant with many engines, your facility likely falls under the “area source” classification (read below for more details).
Do I need to comply?
Should you care about RICE NESHAP? To determine if your engine(s) must comply with the new regulations, you should first gather the following engine information:
- Horsepower of the engine(s).
- Annual hours of operation.
- Annual hours of operation for non-emergency purposes.
- Annual hours of operation for maintenance checks and readiness purposes.
- Date of engine manufacture.
This information allows for each engine to be classified as either an emergency or non-emergency engine, as well as its source group. The engines are distinguished as either a major source or area source of HAPs. A major source is an area that produces over 10 tons of carbon monoxide (CO) annually, while an area source is any engine not classified as a major source.
Once you have this information, use this tool for a step-by-step questionnaire that will help you identify specific requirements for a specific engine/application.
It is clear that I have to comply, now what?
If you have to comply, the deadlines are May 3rd, 2013 for compression-ignited (diesel) engines, and October 19th, 2013 for spark-ignited engines (gaseous-fuel engines).
Bringing an existing engine into compliance with RICE NESHAP requires two main components that fall under the “hardware” category:
First, the rules will require a modification to the engine’s exhaust system. The purpose of the modification is to reduce hazardous pollutants emitted by the engine. Depending on the engine type (diesel, rich-burn gas or lean-burn gas), you may be required to use an oxidation catalyst, a 3-way catalyst and/or particulate filter. A 3-way catalyst is ideal for rich burning natural gas engines while an oxidation catalyst is ideal for lean burn natural gas and diesel applications. Particulate filters can also be used with CI engines. An oxidation catalyst consists of a catalyst element enclosed in a steel or stainless steel housing. The catalyst housing is installed in the engine’s exhaust piping, and as the exhaust gases flow through it, a catalytic reaction oxidizes carbon monoxide (CO) into carbon dioxide (CO2).
Tip: For affected diesel engines, RICE NESHAP requires a 70% reduction of carbon monoxide (CO). Carbon monoxide is selected as the target because it is easiest to measure, and all other pollutants can be expected to be reduced if a CO reduction is attained.
The second piece of hardware consists of a closed crankcase ventilation system (CCV). In older diesel engines, crankcase emissions were released from the engine into the atmosphere through a vent. If you operate older diesel engines, you may be familiar with the small vent line that would often transport collected oil to a bucket or pan on the floor of the engine room (hopefully not to the bare floor!). A closed crankcase ventilation system is now required to capture the oil in blow-by gas, return it to the crankcase, and then redirect the gaseous emissions back to the intake system for combustion. CCV systems use filter elements that must be periodically cleaned or replaced. Closed crankcase ventilation systems are simple devices that can help keep engine rooms and engine components clean, as well as reduce oil usage.
Along with exhaust and crankcase emissions there are several other subjects that may require attention to bring an engine into compliance. These subjects include: low sulfur diesel fuel requirements (now standard in most US jurisdictions), standard work practices, engine operating limits, start-up requirements, demonstrating compliance and EPA reporting requirements.
Traps to avoid…
I mentioned earlier that the solutions to achieve compliance are relatively simple. While true, the technical aspects of compliance require an understanding of a few concepts that can create problems for inexperienced providers. I expect that most engine maintenance/service organizations will be familiar with these topics, but as an owner/operator, you should confirm that these points have been taken into account:
Exhaust System Backpressure – When retrofitting a catalyst housing to an existing exhaust system, the impact to the overall system backpressure must be considered. A catalyst system can increase total backpressure by 5″ to 10″H2O. Depending on the existing exhaust piping layout, this additional pressure drop may cause you to now exceed the backpressure limits of the engine. Careful sizing and analysis will need to be performed to stay within the backpressure limitations. Most manufacturers of emissions reduction equipment will use software to calculate the expected total backpressure created by a proposed exhaust piping system. I recommend that you request their sizing/selection report, and compare it to the engine exhaust data to confirm that the maximum backpressure limit will not be exceeded.
Catalyst Placement – Proper placement of a catalyst housing within the exhaust system is key to the effectiveness of the catalyst in reducing emissions from the engine. Most catalysts require temperatures in excess of 450°F to operate efficiently. A typical diesel engine will have exhaust gas temperatures in the 900°F range. But this temperature is at the engine exhaust manifold outlet, and it dissipates as the gases travel downstream through the exhaust piping. Placement of the catalyst further down the exhaust stream would result in lower exhaust gas temperatures coming in contact with the catalyst, therefore reducing its efficiency. In cases where the catalyst must be located further down the exhaust stream, insulation around the exhaust system may be required to maintain a temperature suitable for an effective catalytic reaction. To ensure system performance, the catalyst must be mounted upstream of any silencer incorporated into the exhaust system. Not only will it benefit from the higher exhaust gas temperatures, but it will also be less likely to clog from particles separating from the silencers’ internal packing material (most silencers use internal sound-deadening material to achieve higher attenuation levels). Where space is at a premium, the catalyst housing can be designed as an integral part of a replacement silencer, which then takes the place of the existing silencer. This option is known as a combination catalyst/silencer (here is a Sample OxiSilencer).
Support Structure – Before installation of the catalyst system, the support system needs to be evaluated. Larger systems require additional supports as the connecting pipe may not be able to support the weight of the catalyst. A steel ladder support system may be required and is recommended to be pre-fabricated to reduce the service time of the system.
Catalyst Sizing – The sizing of the catalyst is another key factor in the effectiveness of the system. The volume of the catalyst must be calculated correctly for a given exhaust flow rate in order to satisfy RICE NESHAP, or specific pollutant reduction requirements. Under-sizing the catalyst will not allow the desired reduction to be met, while over-sizing the catalyst adds unnecessary cost to the system.
Tip: To size the catalyst properly, the following engine data is required: exhaust gas flow rate, temperature at the catalyst, and the engine’s maximum backpressure allowance. This form may be helpful in gathering the necessary data. If you need help locating some of these data points, contact me.
Service Requirements – Catalysts typically require servicing every 8,700 hours of operation. Servicing consists of removal of the catalyst element from the housing, inspecting it and cleaning it by blowing compressed air in the direction opposite to normal flow. An element that has been “poisoned” (permanently damaged due to excessive oil in the exhaust stream, or high sulfur content in the fuel) will need to be replaced. To facilitate service requirements, the catalyst housing should include an access panel, located where it is easily accessible and free from obstructions.
About Compliance Testing and Monitoring…
RICE NESHAP regulations require compliance testing of all engines requiring catalyst systems. Emissions levels are tested before and after the addition of a catalyst system to ensure compliance to the required emission reduction target.
Depending on the engine size and source classification, periodic re-testing may also need to be performed (for example, every 8,760 hours or every 3 years, whichever comes first, for “Not Limited Use Engines” above 500HP). Besides the pre-installation, post-installation tests and periodic retesting, continuous monitoring of the catalyst system is also required for engines above 500HP. For these engines, a Continuous Parametric Monitoring System (CPMS) must be installed along with the catalyst system. The CPMS typically includes a control panel, a thermocouple and pressure differential sensors for each catalyst system. The CPMS is responsible for recording the temperature at the inlet of the catalyst, and the pressure drop across the catalyst. A low reading on temperature indicates insufficient operating temperature for the catalytic reaction to take place, while a high pressure drop across the catalyst element points to a clogged element. Any of these conditions must be corrected to allow the catalyst system to perform as intended. For a given site that has multiple engines, a single control panel can be configured to monitor multiple systems.
Installation and Service Providers – From A to Z
While the installation of a typical catalyst system is well within the capabilities of most mechanical contractors, I recommend that engine service/maintenance organizations be included in any plan to comply with RICE NESHAP requirements. For engine-generators installations, who best to bring familiarity with engine exhaust systems, engine performance data gathering and subsequent emissions testing than the group that performs regular maintenance on your engines? Service organizations are quickly coming up to speed with RICE NESHAP rules and many are now ready to provide comprehensive solutions. At a minimum, any provider should be able to perform these tasks:
- Assist you in determining your specific compliance responsibilities under the regulations. With the experience of previous installations, the right service provider may be very helpful in identifying the applicable requirements for your facility. Besides the need for an oxidation catalyst, will your facility require a CPMS? Will testing be required every 3-years or every 5-years?
- Coordinate with a reputable manufacturer of emissions reduction equipment for the sizing and selection of the appropriate products for your application (for both exhaust and crankcase emissions). Some installations may allow for the installation of a catalyst housing upstream of the existing silencer. Others may not have sufficient space, and may require that the existing silencer be replaced with a combination catalyst/silencer. Involving a manufacturer early in the process may allow for a custom solution that reduces overall costs for your project.
- Engage and coordinate with electrical and mechanical sub-contractors (if not self-performing these tasks) to layout electric requirements and mechanical modifications needed in your engine room. A single provider that can offer a comprehensive, turn-key solution should provide you with peace of mind knowing that there is a single point of responsibility.
- Assist you in establishing contact with a third-party testing agency to perform pre-installation, post-installation and any future re-tests.
- Provide Owner’s Manuals with recommended operating and maintenance practices for all installed equipment.
- Provide a service contract to perform future maintenance on the proposed equipment.
Ready to move forward to compliance?
If you suspect that your facility may be affected by RICE NESHAP, here are some additional resources to help you reach your compliance goals:
- RICE NESHAP FAQs – most common questions and links to the full text of the rules.
- RICE NESHAP Applicability Quiz – a handy tool that will assist you in determining whether you are affected by this ruling.
- Additional documentation on typical emissions reduction solutions.
- Sample form for gathering pertinent engine data to size and select a solution for RICE NESHAP compliance.
- Search for your regional EPA office here: EPA Regional Office Locator. Or contact:
Ms. Melanie King, Energy Strategies Group, Sector Policies and Programs Division (D243–01)
Environmental Protection Agency
Research Triangle Park
North Carolina 27711
Telephone: (919) 541–2469
Fax: (919) 541–5450
As you embark toward compliance with RICE NESHAP, let me know how you do! What obstacles do you find, and what resources were most helpful? If you need assistance in preparing a guideline specification for a RICE NESHAP compliance project, call me. I will be glad to help! And, as always, if you have a quick question, please post it here. I will try to answer it or at least direct you to the right source!
Good luck with your projects!