Endurance testing of outboard motors for boats was typically done in lakes and sometimes on barges. It was time consuming and presented logistic problems and numerous other challenges for the research and development department at outboard motor factories. When a company in Oklahoma decided to build their own endurance test cell area, the Environmental Protection Agency (EPA) required them to control the emissions from the test engines. Four test cells were considered for air pollution abatement. The initial design exhaust volume was in excess of 4,400 SCFM (6,940 Nm3/Hr) per test cell. This high exhaust volume per cell posed a significant capital and operating cost problem when the company considered pollution control equipment.
The company believed a thermal incinerator would be the preferred solution because of the low cost of natural gas in Oklahoma. After looking at equipment capital cost and operating costs they recognized the benefit of considering a catalytic oxidizer. After thorough technical evaluation, The customer chose Anguil Environmental Systems to solve their VOC problem and ensure that the new test cells were in EPA compliance.
Automotive catalysts have proven effective in handling exhaust gases from internal combustion engines, where both un-burned hydrocarbons and carbon monoxide are destroyed. Anguil analyzed the operation and concluded that the enclosed engine test cells needed significantly less exhaust volume than the 4,400 SCFM (6,940 Nm3/Hr) proposed. Anguil determined that the exhaust from even the largest stern drive engine was under 800 SCFM (1,262 Nm3/Hr) of air. It was critical for this to be under negative pressure, so no carbon monoxide would leak into the test facility. Using 850 SCFM (1,341 Nm3/Hr) as a design criteria, Anguil determined that a 6,800 SCFM (10,725 Nm3/Hr) catalytic oxidizer could handle the initial four test cells with the additional capacity for four future test cells.
Anguil supplied and installed the catalytic oxidizer inside the building on a mezzanine adjacent to the test area. Anguil supplied only enough catalyst to handle the initial loading from four test cells, which reduced the initial capital cost. Anguil engineers performed an exhaust stack test analysis to determine what concentration of carbon monoxide and hydrocarbons was present. The presence of carbon monoxide dictated a total enclosure around the catalytic oxidizer. Anguil placed an exhaust fan in the enclosure, creating negative pressure and eliminating the possibility of carbon monoxide leaking into the facility. The oxidizer was equipped with a variable speed/variable frequency drive to provide a high degree of turndown if only one test cell was being run. A stainless-steel plate and frame type heat exchanger was used to accommodate high exotherm across the catalyst.
Some of the engines in the facility were diesel engines and some endurance runs were lengthy. Since these engines potentially could go out of tune, a ceramic particulate filter was installed within the catalytic oxidizer down-stream of the gas burner to protect the catalyst from unburned carbonaceous materials. The periodic cycling and high fire of the gas burner eventually vaporizes these carbonaceous materials and allows them to be oxidized by the catalyst.
After approximately eight months of successful operation, the company decided to expand and add the four additional test cells. The new exhaust fans and ductwork were completed by Anguil’s installation crew and additional catalyst was added to meet the company’s increased capacity. The result is a state-of-the-art engine test facility in compliance with EPA requirements.
Ventilation Air Methane (VAM) refers to the ventilating exhaust from coal mines with methane concentrations between 0.1 and 1.9%. Although the concentration is extremely low, the volume of VAM flow is extremely large. Experts predict that more than 50% of all VAM is exhausted from mine ventilation systems directly to atmosphere and remains underutilized; thus the total quantity of methane released is significant. This will damage the ozone (O3) layer in the atmosphere and as a result, contribute to climate change.
The Chinese government is giving an incredible amount of attention to environmental protection and making the corresponding regulations increasingly restrictive. This has hit the coal industry hard. Almost every coal mining enterprise in China must quickly determine how to meet the regulatory standards and at the same time, efficiently utilize the huge amount of VAM.
A large coal mining company in Shanxi Province, China, decided to adopt a new technology to capture the VAM and convert it into usable energy. After careful evaluation of the suppliers, Anguil’s team in Shanghai was selected to provide the VAM air pollution control system. Anguil Environmental is headquartered in the United States with more than 1,900 pollution abatement installations around the world. Having a presence in Asia for over two decades, the company has successfully installed hundreds of their pollution abatement systems in China.
After a comprehensive design review, Anguil recommended the Regenerative Thermal Oxidizer (RTO) technology equipped with hot gas bypass to destroy the VAM emissions and some low concentration Coal Bed Methane (CMM) from the drainage pipes. With Anguil’s RTO design, no auxiliary energy is required for combustion so long as adequate incoming methane concentrations are maintained, typically above 0.35%.
Any excess heat produced during the oxidation process is routed from a hot gas bypass dampers to a boiler system to generate enough steam, which is led to the steam turbine for electricity generation. Different from traditional methods of power generation by burning the coal or gas, using the excess heat from the RTO does not result in the presence of nitrogen oxide (NOX) and can keep the hot air stream at a very stable temperature, which is very important for the following power generation. There is enough steam to also provide building heat during the winter and cooled shaft air during the summer.
This way, the RTO system is not a just destruction technology; the emissions are converted from a greenhouse gas to a revenue generating initiative for the coal mining enterprise as they are able to sell the electricity.
This VAM abatement project consists of six RTOs that process a total exhaust volume of 540,000 Nm3/hr (336,448 SCFM) with an average methane concentration of 1.2%. Once at full capacity, the system will generate electric power with an installed capacity of 15 megawatts which will be returned to the national power grid. Independent reports show that the methane destruction efficiency is above 99.5% and the system is capable of destroying 51 million cubic feet of methane annually.
Under the close cooperation between the different departments and the full support from Anguil headquarters in the United States, the RTOs were installed on time and within budget. The mining customer recognized Anguil with a Best Engineering Organization Unit Award.
As a new method to utilize a very low concentration of VAM in high efficiency, this project has received extensive attention locally. As reported by several local news outlets, the initiative has been listed as a Methane Zero Net Emission Demonstration Project by China National Development and Reform Commission.
Since the success of this installation, Anguil has received several more orders from other mining companies looking to utilize VAM and reduce their environmental impact. Anguil’s VAM system proves that mining operations can profit by incorporating a properly designed oxidation technology for air purification and combine it with some sort of heat recovery system for steam, heat or electricity production.
A soil and groundwater remediation firm had contacted Anguil Environmental Systems with a need to process increased Volatile Organic Compound (VOC) loading with their two Anguil Model 50 Regenerative Thermal Oxidizers (RTOs).
The customer was experiencing high variability in VOC loading during remediation and their RTOs would shut down due to excessive temperature in the combustion chambers.
Anguil modified both RTOs to incorporate a Hot Gas Bypass, a feature designed to allow incoming process streams to have LEL levels up to 25%. HGBP diverts hot gases from the combustion chamber to the stack during high VOC loading conditions. The residence time of the diverted hot gases as they pass to the stack ensures the emissions are destroyed without affecting the system’s destruction efficiency.
Hot Gas Bypass (HGBP) is commonly ordered on new RTOs with either highly consistent VOC loading or high variability in loading. HGBP is also commonly ordered from Anguil for retrofitting onto Anguil-built RTOs and oxidizers supplied by other manufacturers.
Anguil retrofitted both RTOs with a new HGBP in the field. This required mechanical, rigging, and electricians onsite who were all managed by Anguil. After completion, the RTOs were able to handle the fluctuation of the customer’s process without any further high temperature shutdowns.
Quality Environmental and Energy Solutions from Anguil Environmental Systems
At Anguil Environmental Systems, we are well-equipped to provide emission abatement solutions for any industrial facility. For additional information about our capabilities and how we can benefit your company, contact us today. One of our customer service representatives will answer and address any questions or concerns you may have.
OXIDIZER SERVICE SERIES: PART 3
At the risk of sounding repetitive, the very same wording with which we began Part 2 of our Oxidizer Service Series, Crafting Your Oxidizer Maintenance Plan, applies to Stocking Spare Parts for your Oxidizer System as well. In other words…
Many will come to this article hoping for a one-size-fits-all list for stocking spare parts for an oxidizer system. As a company that provides service for any oxidizer regardless of style or original manufacturer, we at Anguil have long wanted the same. A set recipe for success would certainly make life easier. For those in need of a quick answer, or a starting point from which to grow, we do not wish to disappoint.
Absent of knowing anything else about the operating context of a particular oxidizer system, our best recommendation for building a Spare Parts Program is as follows:
- From the documentation as listed in Part 1 of our Oxidizer Service Series – Better Maintenance Starts with Better Documentation – gather your P&ID and updated Electrical Schematics, including panel layout diagrams.
- Compile a list of your Permit Requirements, especially as relating to allowable downtime in a given year and bypass allowance.
- Sit down with an oxidizer service provider such as Anguil. Using the P&ID and control panel diagrams as a guide, tag each system component as falling into one of four categories: CRITICAL, RECOMMENDED, CONVENIENCE, and ORDER AS NEEDED.
- Show the tagged diagrams to your maintenance personnel and get their feedback on whether their experiences agree with this analysis.
- Once the parts have been prioritized, they can be priced out and purchased according to the needs of your facility. Keep in mind that many oxidizer manufacturers do have OEM discounts with oxidizer component providers so they can be competitive on providing the right parts for your system.
- Regularly inventory your stock once parts are purchased and on your shelves. We recommend tying this activity in to your regular maintenance routine.
Why does your Oxidizer Spare Parts Program deserve significant attention?
Consider the following:
As reliable as oxidizer systems of today can be, upsets will happen with any class of industrial equipment. The downtime associated with any particular upset can easily be dramatically reduced if the right parts are immediately available on site. What is it worth to your company if you can look back over a year and say that downtime was cut in half – or cut even more?
Chances are that wording very similar to the following may already be in your environmental permit: “OPERATOR will stock the recommended spare parts as determined by MANUFACTURER.” If not there, this type of wording is definitely making it into the safety regulations governing the design and operation of oxidizer systems. Stocking an appropriate level of spare parts for your oxidizer system may be a code compliance issue for your site.
As mentioned earlier, upsets will happen. When they do, you want to be in a partnership with your local regulatory agency. Regulators across the country are getting tougher and smarter. If you are making the case for leniency in a particular downtime situation, but you cannot demonstrate that you’ve taken steps to stock the spare parts recommended by your system’s manufacturer, you may be seen as not holding up your side of the bargain.
Making the decision to have a well-stocked spare parts inventory is comparable to the same decision that we make in our own personal lives in deciding to have adequate auto, home, or life insurance in place. Nobody looks forward to sending in a payment every month to the insurance company. It is easy and short-sighted to think you are not getting anything back for your money, until you need to use it. For spare parts, this is comparable to having the necessary components available in your stockroom to get your system back up and on-line in a minimum amount of time as opposed to lengthy downtime, lost production revenue, and plant headache due to not having the proper “insurance” in place. After all, having a stockroom full of “unused” spare parts is similar to having purchased several “unused” insurance policies. It is always better to have the appropriate insurance in place should it be needed.
Anyone that owns and operates an oxidizer system has already made both a significant investment in, and a long-term commitment to, environmental compliance. Clearly, this is already part of your corporate mission statement. Stocking an appropriate level of spare parts for your system is just one part of that same long-term commitment.
Operating Context Matters
Although we stress the importance of a well designed oxidizer spare parts program, we also consider thermal and catalytic oxidizers in their various forms to be dependable technologies. As manufacturers of these systems, we take pride in the reliability of the oxidizers we build and fully expect there to be several years of trouble-free operation. As much as we want to sell large spare parts packages with every oxidizer system, continuously harping on the need for a large contingent of recommended spare parts can seem counter intuitive even to us at times. Designing a recommended spare parts program for a particular customer can be tricky and, unfortunately, also often gets less thought than it deserves. However, there is a concept that can guide the proper approach to your oxidizer spare parts plan. That concept is your specific operating context.
Here is an example that illustrates the idea of operating context in regards to developing a spare parts plan for your oxidizer system. Several years ago, while presenting our final proposal for an oxidizer system to a potential customer, we included a recommended spare parts package valued at approximately $20,000.00. The potential customer was mildly put off by this number. The retort at the time was, “You mean for the amount I am spending on this equipment, I have to buy $20,000.00 worth of parts just to make sure it runs right?”
Later that same week, we attended a pre-bid meeting for another potential customer. During the review of the bid specifications, the presenter stated, “As part of your bid package for this system, we would like to see your recommended spare parts list. Fair warning, anyone that turns in a package less than $20,000.00 will get scoffed at. That would indicate you don’t understand our production situation.” So in the course of one week, we had met two different potential customers, both somewhat offended by a $20,000.00 recommended spare parts package, albeit for different reasons. The kicker is both potential customers were considering the very same model of RTO!
Happily both ‘potential customers’ did eventually become ‘customers,’ and although seemingly at odds with one another, neither customer was technically wrong. The first customer was in an area of the country where the oxidizer system was allowed to be turned off for several months of the year and also allowed oxidizer downtime of up to ten days during the run season. The second customer was located in a non-attainment zone and only allowed up to four hours to finish a current production batch upon an oxidizer upset. At that point for the second customer, all production had to stop until the oxidizer was running again. Clearly, although the model of oxidizer system was exactly the same, the approach to developing a customized spare parts plan was completely different for these customers – and very permit-driven.
At Anguil, we are eager to help you in the mission of designing an Oxidizer Spare Parts Plan that is right-sized for your operating context.
This is the third of four parts in Anguil’s Oxidizer Service Series. We encourage you to also view Part 1: Better Maintenance Starts With Better Documentation as well as Part 2: Crafting Your Oxidizer Maintenance Plan and Part 4: Oxidizer System Optimization.
OXIDIZER SERVICE SERIES: PART 4
As promised, this is the fourth installment of Anguil’s Oxidizer Service Series. If you have read through the first three parts, this can be seen as a capstone of those efforts. Having a strong oxidizer service plan, backed up with recommended spare parts and all of the proper documentation will not only improve your system performance but also allow you to focus on optimizing your oxidizer efficiency. Setting all of these aspects in place within your overall maintenance plan will help you become proactive in ensuring your system’s reliability. However, this does not take into account how much you are spending on a daily basis to operate. So, how much is your oxidizer costing you to operate? Do you know how much it should be costing you to run if it’s running efficiently? A fully optimized oxidizer will help you save money on operating costs, reduce your greenhouse gas footprint, and contribute to your bottom line in very measurable ways.
Oxidizer system optimization can fall into two categories. The first is “reactive,” meaning you identify and respond to the small inefficiencies that may occur over the life of an oxidizer system. The second would be “proactive.” It is our goal that all of the tools we are providing you within this compilation allow you to act proactively, with the goal of you integrating these tools into your overall maintenance plan.
Things to Consider:
- Over the course of a year, unnecessarily treating an additional 1,000 SCFM (1,605 Nm3/hr) of process exhaust in an oxidizer system can cost upwards of $10,000 with an RTO and over $30,000 for a thermal recuperative system.
- Making a modest improvement in the Thermal Energy Recovery (TER) of an RTO system – even as little as 1% – can cut natural gas bills by 20% or more.
- Most emission abatement systems are designed and installed based on a theoretical projection of future production levels often with a safety factor included. If an oxidizer remains at a facility for 15 to 20 years as many do, it is very unlikely that an existing system is optimized for current production conditions, emission characteristics, and process demands.
It is also important to know that most emission abatement systems are designed and installed based on a theoretical projection of future production levels. If an oxidizer remains at a facility for 15-20 years, it is very unlikely that an existing system is optimized for current production conditions, emission characteristics, and process demands.
Plant managers owe it to themselves to periodically review the operating costs associated with their oxidizer system. This periodic review will allow for informed decisions about both reactive and proactive efforts, translating directly into lower operating costs. If PMEs or testing of the oxidizer is regularly required and included in your maintenance plan, this is an excellent time to schedule an operating cost review. Operating costs can be reviewed during monthly or even weekly walk-by inspections and checklists. These inspections are typically performed by your own personnel. However, Anguil can provide you with a checklist for Monthly Maintenance Day inspections of the system components needing inspection, independent verification, and/or calibration on a monthly basis. The more your maintenance team knows about your system and their capability to perform checks like this on their own, the more money you will save, and the more efficient your system will run.
What follows are some general strategies for oxidizer optimization, applicable to a wide-range of system types. With limited historical information, an oxidizer company like Anguil can quickly determine which of the following strategies could be a good fit for you.
KNOW HOW MUCH YOUR OXIDIZER IS SUPPOSED TO BE COSTING YOU TO OPERATE
Make sure you can answer the following questions:
- What is the expected annual operating cost of our oxidizer?
- How close is our actual operating cost to that expected value?
With relatively minimal inputs, oxidizer vendors can run a performance model and give you the expected operating cost range for your system.
PAY ATTENTION TO THE PERCENTAGES
After five years of operation, an RTO originally designed for 95% Thermal Energy Recover (TER) could easily slip to 93% TER. This might not sound like a big deal, but that decrease in TER actually equates to a 40% increase in natural gas consumption. Percentage points do accrue over the course of a year, so get to know the critical parameters to watch as your system ages.
KNOW YOUR EMISSION LOADING – ESPECIALLY THE AMPLITUDE AND DURATION OF PEAKS
Especially the amplitude and duration of peaks. The size of an oxidizer is almost always determined by the peak emission levels coming from an application, but it is the average emission loading that dictates operating costs. Estimates for future “worst case scenarios” are made in the design phase to ensure a system is not undersized. After a couple years of operation, examine your actual day-to-day production loading to make sure you are not operating an oxidizer designed to handle a theoretical peak loading which you would in fact never reach.
KNOW WHAT OXIDIZER SYSTEM WOULD BE SPECIFIED FOR YOUR PROCESS TODAY
Vapor combustion technologies have evolved over the years. Knowing what is specified for your application in today’s energy conscious market can illuminate cost effective upgrades to existing equipment. Alternatively, an entirely different oxidation technology may be specified for your application today, so knowing what is currently available can save you from sinking too much money into an outdated oxidizer system.
IMPROVE PRIMARY HEAT RECOVERY
Oxidizers are typically designed with internal heat recovery. Usually, hot purified gases leaving the combustion chamber are used to pre-heat the incoming solvent laden air stream, which is the primary heat recovery of an oxidizer system. Projects improving the primary heat recovery of an oxidizer system offer the quickest payback because they provide additional heat recovery at all times the oxidizer is in service. For example, a coating company increased the primary heat recovery in their RTO and the system is now self-sustaining, meaning no supplemental fuel is required during most operating conditions. This coating company increased the primary heat recovery in their RTO and the system is now self-sustaining.
CONSIDER SECONDARY HEAT RECOVERY
If improving primary heat recovery is not cost effective or oxidizer operating conditions do not allow it, secondary heat recovery may be the best option for conserving the heat input to an oxidizer system. Heat exchangers can be added to the exhaust stack of an existing oxidizer to capture excess stack heat in air, water, or even steam. There are a wide variety of low back-pressure designs that can be added to an oxidizer’s stack without requiring a replacement of the oxidizer system fan. See our Oxidizer Energy Recovery Options article for an in-depth look at this optimization strategy.
FOCUS ON COMBUSTION AIR
Combustion air, in both your oxidizer system and process burners, is often overlooked as a potential area for operating cost savings. Making sure burners are tuned properly and only firing when necessary can make a big difference. With RTOs, there is an additional money saving opportunity to install flameless supplemental fuel injection (SFI) systems where combustion air is not needed at all. Also, retrofit options that utilize a heat exchanger to supply combustion air from the chamber or stack.
INVESTIGATE AN EMISSION CONCENTRATOR
Burning air is expensive. In fact, fuel usage for most thermal and catalytic oxidizers will decrease as emission levels increase. If a significant portion of the process air being treated is near ambient temperature with low levels of contaminants, an emission concentrator may be an optimization option for your facility. Often utilized on paint booths and floor sweeps, this technology is capable of absorbing emissions and converting them into a smaller, more fuel rich air stream that reduces the heat input required by a combustion device. Concentrators can increase the capacity of an oxidizer by a factor of eight to 25 when added upstream of an existing system.
KNOW WHAT GRANT MONEY IS AVAILABLE TO YOU
Energy reduction upgrades to existing equipment will have an associated capital cost. These expenses can often be supplemented with grant money from utility companies if there is a significant reduction in fuel usage and/or electrical consumption. Know what grant money is available to you, whom to contact, when, and how to apply. Anguil routinely partners with our customers to secure grant money on applicable projects. We have found the Database for State Incentives for Renewables & Efficiency (DSIRE) to be a great resource.
PROPERLY MAINTAIN EXISTING SYSTEMS
No matter how well an abatement system is designed and manufactured, it cannot continue to operate at high efficiency levels without maintenance. Small inefficiencies in system operation can lead to large operating expenditures over the course of a year. While a formal maintenance plan with checks and balances is ideal, it is often not feasible. However, as noted in part two of the Oxidizer Service Series on Crafting a Maintenance Plan, there are basic service guidelines which can help improve uptime, keep you in compliance and reduce operating costs. With today’s energy prices, a regular service schedule can pay for itself many times over.
Anguil has written extensively on oxidizer operating cost reduction strategies. For more in-depth information that is not included in these optimization suggestions, view the full version of Anguil’s Operating Cost Reduction Strategies.
This is the fourth and final installment in Anguil’s Oxidizer Service Series. We encourage you to also view Part 1: Better Maintenance Starts With Better Documentation, Part 2: Crafting Your Oxidizer Maintenance Plan and Part 3: Stocking Spare Parts for Your Oxidizer System.
Anguil Environmental Systems performed a series of upgrades on a 25-year-old three-chamber Regenerative Thermal Oxidizer (RTO) originally manufactured by Smith Engineering.
The goal was to extend the life of the unit and improve its operating performance for this wall covering manufacturer. The oxidizer’s media was replaced with an extruded monolith block media to increase the thermal energy recovery (TER) of the unit while maintaining its VOC destruction efficiency. The new media provides the owner with an operating savings of over $250,000 per year.
Along with new media, Anguil improved the airflow distribution of the system by installing new stainless-steel cold face perforated sheets and media supports. Proper distribution of the incoming air increases the system’s thermal efficiency and ensures proper destruction of VOCs. The insulation was repaired or replaced where needed to eliminate exterior hot spots.
Due to the age of the RTO, it was becoming increasingly difficult to find replacement parts for the control panel. Anguil updated the controls by replacing the control panel with a unit equipped with a new PLC, HMI, VFDs, and ethernet controls to provide remote monitoring and troubleshooting.
The new media significantly reduced the oxidizer operating costs. The new control panel provided the customer with new up to date drawings and the latest panel components to be able to monitor and control the RTO more easily.
More and more, companies operating air pollution control equipment today realize that the initial capital cost of an oxidizer system can be rapidly eclipsed by continued operating expenses if careful attention is not periodically given to the system.
Below are ten tips to ensure your oxidizer is operating at peak performance. The first five tips focus on parameters end-users should know about their oxidizer systems, while the last five address energy reduction projects to be considered.
1. Know how much your oxidizer is supposed to be costing you to operate.
It is surprising how many facilities cannot answer the following two questions.
- How much is our oxidizer operation expected to cost?
- How close is our oxidizer operating to that expected value?
The “out of site, out of mind” approach is entirely too prevalent when it comes to air pollution control equipment. While that speaks highly for the reliability of systems installed today, it also hints at a blind spot around the day-to-day operating cost of oxidizer systems. With relatively minimal inputs, oxidizer vendors can run a performance model for you and give you the expected operating cost range for your oxidizer system.
2. Pay attention to the percentages.
After five years of operation, a Regenerative Thermal Oxidizer (RTO) originally designed for 95% TER (Thermal Energy Recovery) may have slipped to 93% TER. This might not sound like a big deal, and this may go unnoticed by even the most attentive maintenance department. However, an average sized RTO (25,000 SCFM, 40,125 Nm3/hr) operating for a full year at 93% TER versus 95% TER could cost upwards of an additional $65,000.00 a year! Percentage points do count over the course of a year. Get to know the critical parameters to watch as your system ages.
3. Know your VOC loads – especially the amplitude and duration of peaks.
Often it is peak VOC (Volatile Organic Compound) loads that determine your oxidizer design, but average VOC loads that determine your oxidizer operating cost. When an oxidizer is specified, designed, and installed, oftentimes it is the anticipated VOC loading peaks that dictate the amount of heat recovery incorporated. Typically, estimates for a future “worst case scenario” are made to ensure a conservative approach is taken. After a couple years of operation, it may be time to examine whether the design was too conservative and the peak solvent usage is much lower than originally estimated. Operating an oxidizer designed to handle a theoretical peak loading may be costing you much more than necessary for your actual day-to-day production loading.
4. Know what oxidizer system would be specified for your process today.
Finding out exactly what would be specified to treat your process exhaust today is a valuable exercise, especially if your existing equipment is in need of significant repairs or upgrades. Knowing what would be specified in today’s energy conscious market can serve to illuminate cost effective upgrades to your existing equipment.
For instance, five to 10 years ago, an RTO with 90% heat recovery may have been specified to treat your process exhaust. Today, oxidizer vendors may prescribe an RTO with 95% or 96% heat recovery and a hot gas bypass damper to deal with high VOC loading periods. If your existing oxidizer system is due for repairs, a service provider such as Anguil can also determine whether it would be cost effective to upgrade to today’s standards at the same time.
Alternatively, it may be a completely different oxidation technology specified today. With today’s control schemes, RTOs have expanded their applicability greatly over past years, while also dropping significantly in initial capital cost. Knowing exactly what would be specified today can save you from sinking too much money into an outdated oxidizer system.
5. Know what grant money is available to you.
Energy reduction upgrades to existing equipment will have an associated initial capital cost. This can be significantly reduced with grant money from local utility companies. Across the country, money has been earmarked for the specific purpose of funding energy reduction projects. Know what grant money is available to you, whom to contact, and when and how to apply. The main intent of these programs is to take upgrade projects that you (or your management) may be on the fence about and contribute the funds necessary to make them very attractive.
6. Concentrate high volume low VOC airstreams prior to oxidizer.
If a significant portion of the air entering your oxidizer is at or near ambient temperature with low levels of VOC loading, a VOC concentrator may be applicable for reducing the heat input required by your oxidizer system.
As a result of recent regulations, many facilities around the country have been forced to improve localized VOC capture as well as prove high destruction efficiency in their oxidizer system. In many cases, this has led to the installation of additional capture hoods or enclosures and increased the amount of air to be treated by a particular oxidizer system. A concentrator can take exhaust air at or near ambient temperatures and concentrate it so that what is actually sent over to the oxidizer system is reduced by a factor of eight to 15 times. This greatly reduced airflow is typically fuel-rich with VOCs and much less of an operating cost burden on the oxidizer system.
7. Focus on combustion air.
Combustion air, both in your oxidizer system or in your process burners, is often overlooked as a potential area for operating cost savings. Next to the main oxidizer system fans, the smaller combustion fan supplying high-pressure air across the oxidizer burner can seem insignificant. However, these smaller fans, more often than not, are supplying fresh air at outdoor temperatures directly into the oxidation chamber where it must be heated to full oxidation chamber temperature. At a temperature difference usually over 1400 F, it does not take much airflow over the course of a year to add up to significant operating cost dollars.
Making sure burners are tuned properly and not firing on excess combustion air can make a big difference. With RTOs, there is the additional opportunity to install a flameless fuel injection system where combustion air is not needed at all. Finally, even with a perfectly tuned burner, combustion air can be preheated using a heat exchanger or a blend with stack air.
8. Improve primary heat recovery.
Oxidizers are typically designed with some form of internal heat recovery. Usually the hot purified gases leaving the combustion chamber are used to pre-heat the incoming pollutant-laden airstream. This is referred to as the Primary Heat Recovery of an oxidizer system. Projects that improve the primary heat recovery of an oxidizer system often offer the quickest payback because they provide additional heat recovery at all times the oxidizer is in service. For recuperative thermal and catalytic units, this typically consists of adding additional passes to the internal air-to-air heat exchanger. For RTOs and RCOs this would be handled with increasing or changing the type of ceramic heat recovery media or changing the control scheme that dictates how often beds are switched from inlet to outlet.
9. Consider secondary heat recovery.
If improving primary heat recovery is not cost effective, or oxidizer operating conditions do not allow it, secondary heat recovery may be the best option for conserving the heat input to an oxidizer system. Heat exchangers can be added to the exhaust stack of an existing oxidizer to capture excess stack heat in air, water, or even steam. There is a wide variety of low back-pressure designs that can be added to an oxidizer’s stack without requiring a replacement of the oxidizer system fan.
Payback for these projects is greatly improved if the captured heat can be used back in the exhaust generating process itself, because again, it is assumed that the process is operating at all times the oxidizer is operating. For example, fresh air is passed through a secondary heat exchanger in an oxidizer exhaust stack and supplied back as base loading for the oven zones the oxidizer is treating. Every time the oxidizer is on the oven zones require heat, so this heat recovery project pays back all year long. If the same fresh air was supplied back to the plant as tempered makeup air, this may only provide payback during the heating season.
Following this logic, in the past comfort heat applications may have been ignored. But considering today’s unstable and rising fuel costs, coupled with the energy recovery grants available to facilities, these projects deserve attention.
10. Properly maintain existing systems.
Finally, no matter how well an overall system is designed, it cannot continue to operate at a high efficiency level without proper maintenance. A handful of small inefficiencies in system operation can lead to large operating cost bills over the course of a year. At today’s energy prices, regular calibration of feedback instruments and control loops can pay for itself many times over.
All too often, production facilities take the “No News is Good News” approach to their air pollution control equipment when they really should be chasing the benefits of “Company Stays Green and Saves Green” headlines instead.
Tekra Corporation has always had an eye on their energy conservation. They are a custom coater of plastic films in Wisconsin where state regulations require over 98% of the Volatile Organic Compounds (VOCs) emitted from their process be destroyed in an oxidizer system. While considering their first oxidizer system, Tekra’s Engineers did their homework and invested in an early model Regenerative Thermal Oxidizer (RTO). While at the time RTOs were not the cheapest oxidizer option capital-wise, Tekra knew that long-term, an RTO was their best choice for reliable air pollution control, lower operating costs, and a smaller carbon footprint. “We have always tried to be a green company,” said Zachary Gernetz, Project Engineer for Tekra.
In 2003, it was time for Tekra to replace their aging RTO system, and they turned to Anguil Environmental Systems out of Milwaukee, WI. The equipment of choice was again an RTO, although Anguil’s RTO had significant advantages over the previous model including: 95% TER (Thermal Energy Recovery), lower horsepower, lower operating temperatures, and better options for turndown and idle modes.
“Tekra went so far as to have us install a small odometer-style meter right on the front of the control panel for the Anguil RTO, showing exactly how many BTUs they were saving over their previous unit,” says Greg Blando, Service Manager for Anguil.
CERAMIC MEDIA RETROFIT
Tekra’s focus on achieving better energy efficiency did not end there. With a new nationwide focus on green business practices and energy costs on the rise, they again challenged Anguil to perform even better in 2009. Anguil studied the temperature charts of the RTO system and took air samples during peak VOC loading production runs and determined that the 95% TER of the system could be pushed closer to 97% without creating any adverse high-temperature conditions in the RTO. Thermal Efficiency of an RTO relates to the ceramic media inside of this type of oxidizer which captures and then utilizes energy from combustion to pre-heat the incoming, untreated airstream.
“A two percent improvement in TER may not sound all that impressive,” says Mike Scholz, Project Engineer for Anguil. “But most RTOs out there today were designed to achieve about 95% TER. The natural gas required by those systems is directly tied to that five percent of energy lost. Getting back two of the ‘lost five percent’ is actually a 40% reduction in energy lost. In practical terms, that two percent improvement in TER can translate into 40% less on your RTO natural gas bill.” In addition, the enhanced performance at Tekra put their oxidizer into a self-sustaining mode more often, meaning the fuel value in the VOC-laden exhaust gases are enough to operate the RTO and no auxiliary fuel is needed, hence fewer greenhouse gases emitted.
Because of advances in RTO ceramic heat recovery media, Anguil is routinely able to provide RTO operators like Tekra with a performance upgrade by either adding to the top of existing media beds or at times, replacing the top several layers of existing beds with new extruded ceramic media blocks. “With this type of project, payback is king,” comments Lee Kottke, a manufacturer’s rep for Anguil closely involved in the Tekra relationship. “That’s why it is exciting that Anguil can achieve this level of success with only partial media change-outs. That keeps the project cost down and payback periods very reasonable.”
There are other possible effects on project payback to consider. Deeper media beds may require the relocation of chamber instrumentation – like thermocouples. Also, higher efficiency media styles can come with increased back pressure and electrical horsepower cost. Often, however, as in the case of Tekra’s RTO, the electrical penalty is minor compared to the natural gas savings.
Gernetz said that with two coaters running a variety of coating weights and line speeds, it is difficult to get an exact dollar savings. However, prior to the media replacement their RTO often required natural gas to maintain temperature when only treating the exhausts from one coating line. Post retrofit, “the RTO rarely requires natural gas even when only one coater is operating and never when both are on,” says Gernetz. Zach added, “Jobs that were never self-sustaining before are now, so I know that the media retrofit is saving us money.” He estimates a two year payback for this retrofit.
Considering some enhancements to your RTO? Think about this:
- Up until recently, most RTOs were designed with 95% Thermal Energy Recovery (TER%) or less.
- Rule of Thumb for a self-check: If the average RTO outlet temperature is more than 100°F higher than the RTO inlet temperature, your actual TER% is probably less than 95%.
- Even a small increase in TER% can have a dramatic effect on RTO fuel usage. In some cases, a bump in TER% could eliminate RTO fuel use entirely.
- Advances in ceramic media have allowed Anguil to improve TER% in RTOs by only replacing a portion of the existing ceramic media beds, improving payback periods.
- Anguil has performed this retrofit on numerous RTOs, regardless of original manufacturer, and we offer free savings analysis for those interested.
According to Chris Anguil, President of Anguil Environmental Systems, Inc, “When I reflect on the relationship between Anguil and Tekra, it strikes me how RTOs, while such a huge leap forward in energy efficiency over previous oxidizer styles, are continuing to evolve. Advances in media and controls mean there is still room for efficiency improvements on any RTO system out there, regardless of age. Anyone owning an RTO should follow Tekra’s lead and continue to ask if they can do even better energy efficiency-wise. We applaud Tekra’s commitment to environmental compliance and energy efficiency and thank them for challenging us with this opportunity.”
A recreational products company bought a three year-old manufacturing facility with an existing Regenerative Thermal Oxidizer (RTO) for the production of their outboard engines. They required emission control equipment to manage the Volatile Organic Compounds (VOCs) emitted by the solvents used in the engine painting processes. The company wanted to minimize overall costs by utilizing the existing RTO to control their emissions. However, the paint exhaust produced 80,000 SCFM (128,400 Nm3/hr), an impossible challenge for the existing RTO, which had been designed and built to control only 17,000 SCFM (27,285 Nm3/hr). Looking towards the future, the company wanted an air pollution control system capable of managing future expansion.
Anguil’s engineering team demonstrated a solution that allowed the company to utilize the 17,000 SCFM (27,285 Nm3/hr) RTO that came with the building. By placing two 40,000 SCFM (64,200 Nm3/hr) Rotor Concentrators upstream from the RTO, the company could cost-effectively expand their operation and still achieve regulatory compliance.
This outboard engine manufacturing plant had multiple paint spray booths and ovens producing 80,000 SCFM (128,400 Nm3/hr) of exhaust air. Controlling the higher temperature oven exhaust alone would preclude the use of technologies such as VOC adsorption. However, the combined booth and oven exhaust allowed Anguil to use its integrated VOC emissions concentrator/oxidizer technology, reducing the 80,000 SCFM (128,400 Nm3/hr) paint line exhaust to 8,000 SCFM (12,840 Nm3/hr), thus incorporating the existing RTO.
This reduction was made possible when spray booth and oven exhausts were directed to the concentrator system. The VOCs from these sources are adsorbed onto zeolite that is impregnated onto a honeycomb substrate as the air passes through the substrate. These adsorbed VOCs are then desorbed off the concentrator wheel in an airflow that is one-tenth the process flow rate-resulting in a VOC concentration approximately 10 times higher than the process stream. Since the desorption air must still be controlled by an oxidizer to meet regulatory requirements, this smaller flow rate reduces the capital cost of the oxidizer. With the concentration of VOCs leaving the concentrator subsequently much higher than the original process, the operating cost of the oxidizer is also significantly reduced.
One advantage of the RTO is its low operating cost. Vertical beds of ceramic media alternately store and release heat or energy to elevate the process air temperature. Since RTOs have such high heat recovery, the process air can be heated to a value very close to the combustion chamber set-point temperature. Heat released from VOC oxidation further elevates the process air temperature to the point where the RTO is self-sustaining with no auxiliary fuel usage. The use of supplemental fuel injection (SFI) also reduces the point of self-sustained operation to a lower process inlet concentration. Operation with SFI minimizes combustion air introduction into the chamber, which further reduces operating fuel usage.
Many integrated VOC emissions concentrator/oxidizer systems employ the excess heat from the oxidizer as a source of desorption energy at the concentrator wheel. Since the RTO can be so fuel efficient, the oxidizer outlet temperature is low, limiting the use of heat recovery from the oxidizer. Because the RTO was an existing unit and the customer wanted to maintain high energy efficiency, a dedicated heat source was installed to desorb the VOCs from the concentrator wheel.
The RTO used at this facility was an existing unit that experienced several operating problems. To minimize the overall cost of the emission control for the paint system, Anguil provided mechanical and electrical modifications to allow its integration with the concentrator. The resulting benefits of the concentrator/RTO integration included:
- Additional process flow capacity: low concentrator desorption flow allowed for additional process lines to be integrated with existing RTO
- Automated and integrated control system design: including compliance with insurance/safety requirements and remote telemetry for easy system monitoring
- Prolonged equipment life: oxidizer re-insulation eliminated hot spots
- Enhanced VOC destruction: valve repair minimized leakage, while the control valve captured/oxidized the VOC “spike” typical of two-chamber RTO installations
- Reduced operating costs and NOx emissions: Supplemental fuel injection (SFI) reduces the auxiliary fuel requirement and greatly reduces the NOx output from the RTO
Your air pollution control system represents a significant investment in not only initial capital but also ongoing maintenance and operation. Routine inspections performed by your staff combined with thorough maintenance plans provided by Anguil Environmental Service Technicians will ensure you get the most from your investment over the entire life of the system. Anguil has almost four decades of experience servicing a full range of oxidizer technologies, regardless of manufacturer, make or model. Following the recommendations made below will help keep your system operating both efficiently and effectively, reducing costly repairs and avoiding downtime.
It is our goal here at Anguil to provide owners of our equipment the necessary checklists and training to comfortably perform the routine inspections with their own personnel. In the event you own another manufacturer’s equipment the checklist below may vary slightly.
Inspections include a combination of equipment checks on the “high use” items and data recording to build a history of unit performance. When performing equipment checks, operators should refer to manufacturer’s O&M Manuals for detailed procedures. For the data-gathering items, refer to historical data and note any significant changes from typical values.
WEEKLY MAINTENANCE CHECKS – TO BE PERFORMED BY THE LOCAL MAINTENANCE STAFF OF THE EQUIPMENT OWNER/USER.
- Examine air inlet filters for dirt and obstruction, clean or replace as necessary.
- Check to ensure all fan/motor guards are in place and properly secured.
- Prior to operating the system, ensure that all oxidizer doors and access panels are closed and latched.
- Check the fan(s) mounting bolts to ensure they have remained tight.
- Perform a visual inspection of the oxidizer for any loose hardware or damper linkage.
- Visually inspect the oxidizer surface looking for any new “hot-spots” which may be identified by burnt paint and other signs of overheating found on the oxidizer shell or valve housing.
- During the oxidizer’s normal operation, check for fan vibration, abnormal sounds or increased noise levels.
- Visually inspect and listen for unusual sounds during valve operation. Valves should shift smooth and evenly in both directions.
- Inspect the oxidizer fuel train for leaks or loose hardware.
- Check all temperature device read-outs to confirm temperature operation is within normal ranges.
- View pressure device read-outs to confirm operation is within normal range.
- Verify temperature chart recording device is “On” and recording data.
MONTHLY MAINTENANCE CHECKS – TO BE PERFORMED BY THE LOCAL MAINTENANCE STAFF OF THE EQUIPMENT OWNER/USER.
- Check the burner linkage and external burner components for wear or signs of loosening that could cause gradual slipping and adjustment issues with gas and air settings.
- Check fan drive belts for correct alignment, alignment and wear. The belts should have enough tension to allow only one-half-inch movement when pushed or pulled, up or down by hand. A quick check for alignment can be done by testing the tension on the inner and outer belts. The tension should be equal.
- Remove all pressure switch sensing lines, or open drain valves if available, to ensure they are clear and dry.
- Process air and exhaust fan/motor bearings should be greased, per manufacturer’s recommendation. Rotate the shaft slowly by hand while applying the grease. Avoid over-greasing as it can damage the bearing seals.
- Drains or weep holes on all fan motors should be checked for debris and cleaned as necessary.
- Verify oil level of compressed air lubricator, add as necessary.
- Verify burner flame visually at burner or system Peep-Sight for color and intensity. The flame should typically be “Blue” with “Orange/Yellow” tips. The flame strength should not be “Lazy”, you should verify intensity at several different firing rates.
SEMI-ANNUAL MAINTENANCE CHECKS – CAN BE PERFORMED BY MAINTENANCE STAFF OF THE EQUIPMENT OWNER/USER OR AN ANGUIL ENVIRONMENTAL SERVICE TECHNICIAN.
- The interior of the oxidizer should be inspected. While inside, inspect the insulation for signs of deterioration, damage or gaps. Use extreme caution when entering or exiting the oxidizer to avoid damaging the door or the door threshold insulation (if applicable). Internal entry to be made by qualified personnel per site safety requirements.
- Clean the inner lens of the burner view port with a soft, dry cloth.
- Check the ceramic media for buildup of particulate or residue and visible damage.
- Before closing access doors, inspect the gaskets replacing or repairing as necessary to maintain a leak free seal.
- Visual inspection (only) of poppet valve shafts, seats, and disks. Caution: This should be performed by trained / authorized personnel only, after adhering to all lock-out / tag-out safety precautions. Note:The flow control valves may shift without warning if the mechanical safety pins are not installed.
- Remove the UV scanner and clean the view lens with a lint free cloth.
- Replace the spark igniter.
- Inspect the exterior of the burner for damage or areas showing excessive heat.
- Inspect all fan flex joints and replace as necessary
- The T-dampers and linkage (if applicable) should be inspected for proper operation and the linkage checked for tightness and lubrication at appropriate points.
- Verify burner flame visually at burner or system Peep-Sight for color and intensity. The flame should typically be “Blue” with “Orange/Yellow” tips. The flame strength should not be “Lazy”, you should verify intensity at several different firing rates.
- Review past alarms for identification of areas requiring specific attention to eliminate possible future alarms.
YEARLY INSPECTION: PREVENTIVE MAINTENANCE EVALUATIONS (PMES):
The Anguil Preventive Maintenance Evaluation (PME) is a two to three day thorough evaluation of your system performed by a qualified Anguil Field Service Engineer. Typically, PMEs are scheduled on an annual or semi-annual basis. It does require the system be cooled down and not running for one day to complete the internal inspection. On the second day of a PME the availability of process airflow is recommended in order for the system to be inspected under normal operating conditions.
The inspection is based upon a comprehensive checklist followed up with a written formal report for your records. The formal reports are an important component of a proper maintenance / record-keeping program and are often very helpful when working with local regulatory agencies. In some cases, record keeping and regular maintenance are required as a component of an air permit. The checklist is broken down into the following four areas of your system:
- Mechanical: An external and internal inspection of the oxidizers mechanical components will be performed. This includes items such as: ductwork, valves, linkage, heat exchanger, reactor, fan, motor assembly, burners, catalyst, stack & observation ports.
- Electrical: The electrical components will be inspected and electrically tested to insure that they are functioning properly. This includes: switches, lights, relays, timers, controllers, recorders, motors, starters, actuators, disconnects, and wiring. Additionally, the system’s “Safety Circuit” will be tested for proper operation and a new spark igniter(s) installed.
- Process Control Loops: The temperature and pressure control loops will be inspected and tested to verify correct operation and sequence. This entails a visual inspection and adjustment of the air/fuel mixture ratio of the burner, if necessary. Also, an operational review of various controllers, actuators, thermocouples, pressure switches and variable speed drives will be performed. We will also evaluate the system (or catalyst) ready circuit, the inlet and atmospheric bypass damper circuits, the warning alarm circuits, and the shutdown alarm circuits.
- Oxidation Efficiency Test: If requested – an optional oxidation efficiency test can be performed by using portable detector units or collecting 1-Hour process inlet / outlet samples for laboratory analysis. This service keeps you alert of any potential problems related to your system’s Destruction Rate Efficiency (DRE) and is ideal as a pre-test to help eliminate “surprises” during expensive formal compliance testing.
Upon completion of a PME you will receive a formal evaluation report detailing the current condition of your oxidizer as well as our recommendations for improving performance, efficiency, reliability and safety.
ADDITIONAL TESTING AND MAINTENANCE IDEAS TO CONSIDER:
Repeat Training Sessions: Your maintenance team may require additional training sessions as a refresher or due to employee turnover. Anguil will travel to your site and perform follow-up training sessions, often coupled with any of the inspection visits listed above.
Catalyst Maintenance: If your system includes catalyst – Anguil can help you remain in compliance and build a catalyst performance history with regular testing of your catalyst. Regular evaluation is key to maintaining catalyst performance. A standard laboratory activity test should be performed yearly, with additional follow-up testing as necessary. A formal evaluation report will be provided. Additionally, Anguil can provide other catalyst services such as catalyst rejuvenation, catalyst replacement, and also a “catalyst buy-back” program for spent catalyst.
For further information please contact the Anguil Service Department, we offer all of the services listed and more on any make or model oxidizer system! Programs can be purchased individually or grouped into a custom designed service plan.