Where Clean Air Engineering really shines is in our ability to troubleshoot systems from raw material input to product output-- our process engineers, many of them also field technicians, are expert problem solvers. Since our founding in 1972, there have been few process problems our technical staff hasn't solved. 

Clean Air consulting services balance our field services by providing a "long-view" of processes and facility operations. Take a look at some of the industries we work with, and see the solutions Clean Air Engineering field technicians and engineers developed to meet customer needs. 
 

See For Yourself -- Success!:

Cement Production  Electronics Manufacturing  Electrical Utilities  Metal Refining and Processing  Mining and Mineral Processing Plastics Manufacturing  Surface Coating Waste Treatment and Disposal

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Cement Production:

Problem:

A client wanted to monitor the HCl emissions from a cement kiln continuously for a 30 day period. Because this was a short-term monitoring project, the facility as a cost savings measure wanted to rent a system to minimize equipment and labor costs.

Solution:

Clean Air Engineering was contracted to design and install a temporary HCl CEMS utilizing gas filter correlation (GFC) and associated data acquisition system to meet the monitoring requirements. As part of the contract, Clean Air provided on-site technicians to install and provide operator training.

Innovation:

Clean Air Engineering, in conjunction with Argonne National Laboratories, conducted an experimental program to evaluate the feasibility of using an FTIR system to measure HAPs at a cement kiln. The target analytes for the program included inorganic compounds and both volatile and semivolatile organic compounds. Specifically, the following compounds were measured:

All of these compounds except ethylene are listed as HAPs by the EPA. Ethylene was included in the program because it has been identified in cement kiln emissions and it has the potential to form polynuclear aromatic hydrocarbons(PAHs) under certain conditions.

In addition to the primary target compounds listed above, ammonia (NH₃), carbon dioxide (CO₂), carbon monoxide (CO), methane (CH₄) and water vapor were also measured during the program. These compounds were included because they are known spectral interferents in the FTIR measurement of many of the target compounds, and all are present in cement kiln emissions.

Electronics Manufacturing:

Problem:

Clean Air Engineering was contracted by an electronic circuit board manufacturer to perform an engineering study to control VOC emissions from an uncontrolled treater and to eliminate the need for internal offset emissions which limited the facilityÖs production. The primary objective was to develop a plan that would control emissions with existing plant equipment, yet not affect the availability of four other treaters on site. 

Secondary objectives were to:

• Improve treater area ventilation; 
• Verify existing equipment operation; 
• Improve operating efficiency and reduce cost of existing thermal oxidizers.

After evaluation of the existing air pollution control systems, a decision was made to duct the uncontrolled treater emissions to the two existing thermal oxidizers. The system was designed to duct the uncontrolled treater flow to both existing oxidizers and regulate the flow to each oxidizer based on system load. Clean Air provided the structural (ductwork) and engineering contol design, and valve control logic with tie in to the existing PLC. Complete drawings and construction plan were provided to the clientÖs mechanical contractor, as well as on site project management and supervision. 

Result:

Once all the modifications were completed a regulatory compliance test was performed that demonstrated a 98% destruction efficiency and a reduction of 16 tons/year of facility VOC emissions.

Electrical Utilities:

Problem:

Following a major outage that included a precipitator rebuild, a utility client began experiencing sparking and low power in their precipitator that appeared to be caused by a high resistivity problem. As a potential remedy the client switched to a different coal with no improvements in operation. The fuels used were both low sulfur eastern coals with moderate amounts (greater than 10%) of iron in the ash.

Solution:

On first examination, the fuels being used should have had low to moderate resistivity values at the temperature of operation (about 300°F). Even with the low sulfur content, the moderate amounts of iron present in the ash would normally allow resistivity conditioning with natural sulfuric acid vapor present in the flue gas. This was shown to be the case both when modeling and measuring the dust resistivity in the laboratory. Yet, the precipitator was still acting as if a high resistivity dust layer were present.

In order to verify the precipitator readings, a coupon (six inches by six inches) was removed from one of the collector plates. Resistivity was then determined for the dust layer that had been clinging to the plate coupon. It turns out that a very high resistivity dust layer that could not be rapped or scraped off the newly installed plates had formed. We then contacted the client to find out what might cause such a layer.

Through further investigations and conversations with the client, we found out that in the past corrosion had been a problem with the precipitator. In order to stem any future problems, the new plates had been coated with a wax based corrosion inhibitor during the rebuild.

It was determined that during start-up, that wax based corrosion inhibitor had somewhat melted and coated the first layer of ash particles being collected. Further heating to full load conditions had left a waxy coated particle interface layer on the plates. The wax coating kept the ash from adsorbing and reacting with moisture and/or sulfuric acid vapor and therefore had a very high resistivity. Thus, the precipitator readings were verified. As ash layers in a precipitator will act like resistors in series, the highest resistance is the one that the power will have to overcome. 

The coated ash layer was also looked at in a cross-sectional photo-micrograph taken using a scanning electron microscope.

Result:

Clean Air Engineering recommended that the precipitator be cleaned to remove the ash build-up off the plates and to start-up the unit on natural gas to drive off the volatiles of the wax based corrosion inhibitor, before switching back to coal. As a result of these recommendations, the precipitator power levels and resistivity returned to normal.

Problem #2:

A large utility client had been experiencing a nuisance opacity problem while burning high sulfur coal. The client was burning 4% sulfur coal in cyclone fired boilers. Pollution control equipment included an oversized electrostatic precipitator (ESP) and three limestone absorber modules. Ammonia injection was used upstream of the ESP to reduce SO₃ emissions. Opacity monitors placed upstream of the absorbers showed less than 5% opacity in the flue. However, complaints had been received from the surrounding community regarding the stackÖs lingering plume.

Solution

Clean Air Engineering conducted an investigative test program that was devised to determine the cause of the plume. The study was performed using various ammonia injection rates. The main objectives of the study were to:

• Determine the cause of the plume exiting the stack; and 
• Determine the effects of ammonia injection on the plume and ESP operation.

• SO₂ and SO₃ concentrations 
• Particulate grain loadings 
• Particle size distribution 
• Particle morphology and composition with respect to particle size 
• NO and NO₂ emissions 
• In-situ resistivity (ESP inlet only) 
• Stack opacity by visual emissions readings

Result:

From the above work, it was determined that the plume problem had two main sources. The first was an abundance of sulfuric acid vapor created in the boiler. From the test parameters, a curve was generated which minimized SO₃ emissions while maximizing ESP collection efficiency. The second portion of the plume came from emissions of NO₂ (NO_x). The client decided to pursue methods of reducing the amount of NO_x created in the boiler.

Metal Refining and Processing

Problem:

An integrated steel producer in the Midwest was faced with a challenge to continuously monitor hydrocarbon emissions from a sinter plant scrubber stack in response to regional ozone regulations that require the continuous emissions monitoring of VOCs. The monitoring application would require sampling and analysis of a saturated gas stream. The client wanted to evaluate existing technology for the design and purchase of a system. 

Solution:

Clean Air Engineering conducted a three month study that included the design, installation, and operation of a temporary CEMS that was used to evaluate three separate monitoring technologies. Data from this study was used in the development of a monitoring plan and design of a CEMS.

Result:

Data from this study was used in the development of a monitoring plan and design of a CEMS.

Mining and Mineral Processing

Problem:

An industrial client was exceeding the regulatory permitted particulate and opacity emission limits for a taconite grate kiln scrubber. From the analysis of previous emission test data, Clean Air Engineering determined that scrubbing water carryover was significantly contributing to measured particulate emissions, and creating an opacity problem as well. We proposed a mist eliminator retrofit to solve this problem.

Solution:

The Clean Air design, using proprietary profiles and custom drainage-supports, eliminated essentially all of the free water from the scrubber exhaust. Clean Air Engineering designed, fabricated and supervised the installation of the mist eliminator to fit within the existing scrubber shell. This required the design and fabrication of a new vane profile to meet the requirements of the systemÖs gas flow (>600,000 acfm).

Result:

Post retrofit testing was performed by the client and the measured particulate emissions are less than half of the levels measured prior to the mist eliminator retrofit. In addition to bringing the facility within its particulate and opacity limits, the retrofit is also expected to improve on scrubber water utilization and reduce the facilityÖs maintenance costs.

Surface Coating
 

Clean Air Engineering has performed numerous engineering projects, in conjunction with normal / routine process and oxidizer compliance demonstrations, to optimize the operation of thermal oxidizers and to reduce energy consumption.

As a result of these programs, our clients have realized reduced energy usage and associated costs, reduced CO₂ (greenhouse) emissions, longer equipment/systems life (i.e. lower temperatures reduce stress on metallic heat exchangers), and reduced maintenance costs for facilities.

Clean Air Engineering has determined for one client, that the average reduction in temperature which could be achieved through optimization of existing thermal oxidizers has been conservatively estimated at 25°F per TO. At that rate, the client estimated that the on-going energy savings would total approximately $500,000 per year.

These estimated optimization savings are for energy use reductions only. They do not include the savings that will be realized from the elimination of unplanned process shutdowns, lower maintenance and equipment replacement costs, and the avoidance of damages to expensive control and process equipment.

Waste Treatment and Disposal

Clean Air Engineering is a strategic supplier to a major waste-to-energy company providing compliance testing services for six facilities. As part of the contract, Clean Air Engineering provides quarterly, semi-annual, and annual testing services to demonstrate compliance with regulatory emissions limits for 19 combustor units.

The test parameters include the determination of the following: