Client      Electric Utility
Description      In a recent contract we provided a utility client with a design package that included items such as materials of construction, insulation and access requirements, bag cleaning system components, damper requirements, fabric specification, G/C ratio, fabric type, bag and cage specification, bag spacing, number of modules, etc.  This design specification was incorporated into the client's procurement package.  We then assisted the client in the subsequent procurement process by providing proposal review and commentary.

Coal-Fired Boiler Bag Specification

Client      Utility Client
Description      ETS was retained by a utility client to improve the performance of their pulse jet baghouse.  The operation was plagued with premature bag failure.  ETS concluded that the underlying cause of the problems was an uneven distribution of the gas.  This maldistribution results in very high localized velocities which rapidly erodes the bags.  We designed a modification to the inlet gas plenum which solved the uneven distribution and thus bag wear.  The modifications were made and the system has since experienced improved bag life and significantly lower operating costs.  

Consulting and Engineering Program for Steel Mill

Client      Inland Steel - Harbor Works
Description      ETS was contracted to execute a major consulting and engineering program for Inland Steel - Harbor Works coal pulverizing facility to assess the pulverized coal injection emission control system for a large (10,000 molten tons/day) blast furnace. The work scope entailed a detailed baghouse and emission control assessment, an engineering feasibility study of repairing and/or replacing the emission control system, and options for that design. ETS was responsible for sizing and specifying the system hardware, including two 70,000-acfm cyclone precleaners, screw conveyors, and supporting equipment that was to be engineered into the existing system. The work scope also included various conceptual baghouse/cyclone designs (including costs), conveying capacity analysis, system sizing, connecting ductwork and explosion vent sizing, calculating structural steel loads, structural steel design, and selecting and developing the instrumentation to ensure reliable system operations. ETS also assisted in system start-up and troubleshooting.

Reverse Air Baghouse System Evaluation

Client      Utility Company - Electrical Generating
Description      ETS was contracted by a major utility to conduct an inspection of the fabric filter system located in one of their facilities in central Pennsylvania.  The baghouse had been in service for many years and had a history of operation at lower than design inlet gas temperatures (sub acid dew point) due to frequent low boiler load conditions and other operational problems.  Utility personnel were concerned about the overall condition of the system and requested inputs so that they could make decisions about extending its length of service versus purchasing new equipment.  They also expressed concerns over a high rate of bag failures, high pressure drop across the bags, and corrosion related failures in several specific areas of the baghouse, inlet ductwork, and the penthouse gallery.

The ETS work scope called for conducting external and internal inspections of the baghouse system including the inlet and outlet ductwork, inlet and outlet turning vanes, system control panels and component monitoring instrumentation, all baghouse compartments and all associated equipment including bags and bag tensioning systems, tube sheets and thimbles, access doors and gaskets, all compartment flow dampers (inlet, outlet, reverse air, and relief), reverse air manifolds, baghouse hoppers and dampers, and the baghouse penthouse.

The inspection identified several problems; among them was improper bag tensioning practices, outdated controls and broken component monitoring instrumentation, eroded inlet turning vanes, several malfunctioning dampers, etc.  In addition the back section of the inlet ducting was almost completely plugged with fly ash that had accumulated over the years.  It was our concern that this accumulation restricted gas flow to the last few compartments of the baghouse, causing a system flow imbalance, thus having a negative impact on bag life, emissions and pressure drop.  There was evidence of acid condensation on the internal walls of the outlet and reverse air ductwork, however there appeared to be very little or no loss of metal in these areas.  In general the physical integrity of the baghouse and its connecting ductwork was in good condition, considering the age of the system and its history of operating at low inlet gas temperatures.

After conducting the inspection ETS provided an inspection report listing all observations, concerns, and commentary on the condition of the equipment.  The report also included a list of items that should be addressed.  The list was prioritized based on a perceived return on investment (ROI) starting with the best ROI and ending with the least ROI.  The report also included ETS recommendations for equipment restorations and O&M procedures that would not only improve baghouse operations but enable the system to operate for at least ten additional years.  The initial ETS inspection took place in 2001.  In 2007 ETS was requested to conduct a follow-up inspection to determine the status of the system and monitor the effect that the actions taken in follow up to our original report had on the condition and operational reliability of the system.  While the control panel has not yet been updated, most of the other recommendations were acted upon.  It was reported that removing the ash in the inlet duct and replacing the turning vanes had resulted in improved flow distribution across the system, bag life had improved and the system has been operating reliably, even though the baghouse system sees frequent dew point excursions because of operational upsets such as boiler tube leaks and continual swinging of load levels.

Develop Preventive Maintenance Plan and Manual

Client      Railroad Company Industrial Boiler Baghouse
Description       ETS was hired by an eastern based railroad company to develop a Preventive Maintenance (PM) plan for the air pollution control system (APC) serving three stoker boilers at one of their work facilities in Pennsylvania.  Each boiler was followed by its own mechanical collector, the flue gases were then directed to a common reverse air baghouse, an ID fan, and stack.  A dry acid gas removal reactor was expected to be installed just prior to the baghouse in the future.

The purpose of the PM plan and its accompanying PM manual was to fulfill state air pollution MACT permit requirements and to formalize the current PM practices that have produced acceptable APC operation and performance and to maintain optimum operating parameters for the APC system.  An additional benefit of the manual was to provide an aid in training of new operations and maintenance (O&M) personnel assigned to the baghouse and associated APC equipment.

This preventive maintenance manual was to provide direction to the maintenance department by monitoring and documenting maintenance of the equipment.  A systematic walk through by a qualified mechanic checking equipment parameters and operating conditions, and noting any unusual visual or audible conditions, can be very effective if done on a regular basis.  These scheduled PM inspections were to insure that the baghouse equipment was operating properly; to insure proper and timely maintenance; to provide audible and visual checks to detect abnormal equipment operation; and to assist in scheduling regular maintenance and repairs to eliminate downtime.  The manual represented a recommended preventive maintenance plan.  It identified the parameters that needed to be monitored, how frequently, and the level of personnel assigned to the task.  It also provided expected parameter ranges and what actions should be taken if the parameter reading fell outside that range.

The PM plan was implemented by the facility in 2007 and a subsequent plan was developed by ETS for a second facility in 2008.

Baghouse System Design Consultation

Client      Electric Utility
Description       A prominent Virginia based utility company retained ETS, Inc. to assist them in the design and specification of a new fabric filter system for the client's generating plant in the eastern portion of the state.  The initial ETS task was to develop a techno-economic comparison of an ESP, a reverse-air fabric filter system, and a pulse-jet fabric filter system.  This effort included comparative analysis of different fabrics and two different gas-to-cloth (G/C) ratios for each baghouse type.  Space requirements for all three devices were estimated and comparative capital and operating costs were developed using methodology detailed in the EPA OAPQS Control Cost Manual.  In addition ETS addressed current and future fine particulate emission and their impact on evaluated technologies. 

In this case the pulse-jet was the recommended approach; the client embraced the recommendation and requested that ETS develop a baghouse system specification.  This flange-to-flange (inlet to outlet) design included all baghouse items including, baghouse and hopper materials of construction, baghouse insulation and access requirements, bag cleaning system components, damper requirements, fabric specification, G/C ratio, bag and cage dimensions and specification, bag spacing, and number of bag modules.  Additional details addressed were gas distribution modeling and requirements, baghouse instrumentation and monitoring requirements, and performance guarantees such as pressure drop (expected and maximum), bag life, and outlet emission requirements.  The design also established vendor experience criteria as well as listing suggested general and technical requirements that would be relevant to final design and subsequent operation of the baghouse.

The design specification was reviewed, and the client's management team decided to incorporate the ETS design into a final design specification that would be incorporated in a procurement package.  ETS provided technical oversight in the development of the final design package.  We then assisted the client in the subsequent procurement process, including vendor interviews and selection.

Baghouse Design

Client      Great Wall Iron Works, Taiwan
Description       Three new residual oil fired boilers were to be installed at a brewery contracted by Great Wall Iron Works. The boilers were to be equipped with limestone injection systems to reduce sulfur dioxide emissions, and the resulting high particulate emissions required the addition of particulate controls. Each boiler would operate eight hours per day, exhaust 36,000 acfm at 385°F with a 480 ppm SO2 concentration, and require 99.5% particulate removal to meet local emission standards. Because of very limited space for emission control equipment, a custom-designed baghouse was needed, and a major metal fabrication facility in Taiwan was retained. In order to obtain the expertise needed to design the baghouse for this relatively unique application, ETS was retained by the fabricator.

Because of the space constraints, ETS chose a pulse-jet baghouse design with five independent filter modules; provisions were made for both off-line and on-line cleaning. Off-line cleaning was recommended to enhance removal from the bags of potentially sticky particulates resulting from incomplete oil combustion. The high exhaust temperature and SO2 content, combined with the daily start-up and shut-down cycle, meant that the filter bags had to be designed to withstand temperature extremes and possible acid attack, in addition to the stresses generated by the pulse-jet cleaning system. Several filter fabric options including acid resistant woven and felted fiberglass, aromatic polyimide (P84) and polyphenelyne sulfide (PPS) were provided to the client.

ETS completed the total design of the baghouses and their support structures, and provided detailed fabrication drawings for every aspect of construction of the baghouse. Both the design and the drawing processes were greatly facilitated by the use of computer-aided design techniques. ETS also provided specifications for the baghouse components that would not be fabricated, such as the filter bags/cages, inlet and outlet dampers, air compressor, and the dust removal system. Additionally, ETS designed the baghouse control systems and provided drawings and component specifications for their assembly and operation. Finally, ETS also provided supporting manuals describing operation and maintenance procedures specific to this application.

Client      Midwest Furniture Manufacturer
Description      ETS was contracted by a large furniture manufacturer in the midwest to research and specify the best-suited VOC emission control system for their operation. ETS had previously consulted with this company to resolve a notice of violation (NOV) for VOC emissions with State and USEPA officials. This client had neglected to obtain an air permit to construct and operate their three year old plant (which is the reason they wish to remain anonymous). ETS was able to successfully negotiate an agreement with the regulators and avoid fines and significant operating limitations. Using stack test data and mass balance data, ETS was charged with performing the following tasks:

• Review files and existing data and plant statistics
• Define emission problems
• Identify technically feasible options and alternative control techniques
• Define budgetary capital and operating costs and expected delivery
• Solicit vendor inputs to confirm item options and techniques
• Rank control options

• Meet with the client to present findings and recommendations and define installation requirements.

Client      Bandag Incorporated
Description      ETS was retained by Bandag, Inc. to conduct an engineering evaluation on its Tread Grinding Dust Collection System and to identify and design a system that would improve dust pickup at the buffing stations, and at the same time reduce the potential for fires in the system baghouse. The engineering evaluation of the existing dust collection system included the following:

• Buffer station gas volume measurements and experiments to determine the gas volume that provides satisfactory dust pickup
• Determination of baghouse inlet dust loading, gas volume, static pressure, and dust particle size distributions
• Ductwork structural evaluation
• Baghouse structural evaluation
• System fan evaluation and analysis of various upgrade/replacement options.

Ultimately, ETS outlined specifications to describe the general qualities, performance, and basic systems required in the fabrication and construction of the finishing line modification. The system modification involved replacing an existing spark arrestor with a medium-low energy cyclone, replacing the existing fan with a larger fan with improved system entry, and recommending fabric types to provide superior resistance to burning with Hysil used as a precoat. Included in the specifications were identification of all labor, materials, equipment, tools, supplies, taxes, and services required for construction activities, such as:

• Demolition and removal of existing ductwork from above buffing hoods to baghouses, including spark arrestor boxes and ductwork support
• Demolition and removal of ductwork from baghouses to fans and fan discharge duct
• Constructing two foundations and making roof penetrations for two new columns
• Installing new structural steel platform framing in cyclone area
• Removing fans and motors
• Removing platform and decking handrail
• Installing new motor and fan support framing and deck extension framing.

Client      Boxley Quarries
Description      ETS was retained by a large rock quarry operation to design a turnkey crushed stone transfer and air pollution control system. The work scope included design, specification, fabrication and installation of appropriate screw conveyors, belt conveyors, dust supression systems and a 25,000 acfm fabric filter control system. This system allowed the client to meet the federal and state air pollution standards for both point source and ambient dust.

Client      Anonymous Concrete Manufacturer
Description      ETS was retained by a national concrete and polymer concrete manufacturer to obtain state permits to construct and operate a polymer concrete plant after the fact. An initial background study of the case revealed that the plant had been operating for two years without a permit. The obvious task was to obtain an operating permit and bring this source into compliance.

To accomplish this, ETS did the following:

• Performed EPA emission tests for particulate and volatile organic compounds
• Performed the necessary input-output calculations to determine air pollutant emissions from the plant stacks not tested
• Acted as liaison between the state Air Pollution Control Board and the client, including representing client during meetings with state
• Completed proper state permit forms to construct and operate the source.

Client      E. I. DuPont de Nemours & Company, Inc.
Description       ETS was retained by a major chemical company to assess the air pollution control equipment of a catalyst production process. The system was plagued with visible emissions and was a constant source of complaints from local enforcement agencies. A program was agreed upon that included the following main tasks:

• Problem definition and profile of emission chemistry.
• Selection of alternative control techniques.
• Specific recommendations - including equipment specification and recommended operation.

The project was a success due to ETS's ability to first define the problem and then apply basic chemical engineering principles. ETS recommended a solution to achieve the program goals.

Client      Kerr Industries
Description      The fabric finishing division of this Fortune 500 company had a baghouse operating on a coal-fired boiler. ETS was involved in upgrading the overall capability of the baghouse system. This application had been plagued with high system pressure drop. The causes for excessive pressure drop were numerous, including insufficient bag cleaning, poor coal quality, improper boiler operation, and, at full load conditions, excessive gas-to-cloth ratio. Improvements were made to the cleaning system and alternate fabrics were screened to determine their capability to operate effectively at extremely high gas-to-cloth ratios (>8:1). Tremendous improvements were made and the system in now able to operate at full boiler load conditions.

Client      Anonymous
Description      ETS was retained as an expert witness by a major steel manufacturer for problem assessment and testimony. The client was operating a pulse jet baghouse for control of particulate emissions from an electric arc furnace. The system was designed to handle 100,000 acfm, but due to excessive pressure drop could handle no more than 80,000 acfm. To date, ETS has researched this problem, including conducting a detailed data and inspection review, an engineering evaluation with economic analyses, and issuance of a report discussing the problem assessment and solutions to the problem.

Client      Titan
Description      ETS was retained by a leading cement manufacturer to improve the performance of a large clinker cooler baghouse system. The operation was plagued with high emission rates and premature fabric failure. ETS was able to identify the causes and recommended a list of solutions, including modification of bag construction and baghouse system components. ETS was given the contract to engineer and supervise the implementation of these modifications. The end result is that the system is operating reliably with no emission problem, and bag life has been increased from less than one to more than three years.

The client was so pleased with ETS's work, they contracted ETS to upgrade their finish mill and row mill baghouses. ETS has also performed numerous diagnostic and compliance tests along with trial burn emission tests for this client over the last 20 years.