Particulate, SO2, and Nox Control

Southern Research has extensive experience in each of the primary air pollution control technologies, including: electrostatic precipitation (particulate); fabric filtration (particulate); selective and non-selected catalytic reduction (NOx); and wet/dry scrubbing (SO₂). We offer in-depth capabilities to assist with the operation, performance, and measurement of each of these advanced technologies.

Electrostatic Precipitation

Southern Research is a pioneer in electrostatic precipitator research. Specifically, we have conducted air pollution control research and measurement regarding ESPs since the late 1960s. In addition, the standard electrostatic precipitator performance model was originally developed at Southern Research and has been updated over the past four decades. A sophisticated Windows-based version of this model is currently available to our clients. Moreover, we have conducted on-site testing of hundreds of full-scale utility and industrial electrostatic precipitators, both cold-side and hot-side. Our research has focused on understanding special performance problems, including hot-side ESP performance problems such as sodium depletion and back corona.

Fabric Filtration

Southern Research has the experience and in-depth expertise to assist utility and industrial clients with fabric filter performance issues. For more than 30 years, we have studied baghouses (fabric filters) applied to coal-fired flue gases, and we have experience with both low-ratio (reverse-gas, reverse-gas-sonics, and shake-deflate) and high-ratio (pulse-jet) types of baghouses. Specifically, Southern Research has conducted on-site testing at a number of full-scale fabric-filter installations, and we have conducted several utility-industry surveys on baghouse applications for the Electric Power Research Institute (EPRI).

Additionally, we have conducted extensive research regarding filtration fabrics for coal fly ash applications and worked closely with the EPRI in the development of their COHPAC^® process for using fabric filters as polishing units downstream of poorly performing ESPs. This process has assumed significant importance, as activated carbon injection for vapor-phase mercury control has been aggressively marketed as the TOXECON^® process.

Electrostatic Precipitator and Fabric Filter Modeling

Southern Research developed the industry-standard computer models for particulate control systems. These models include:

• EPA/SRI ESP Model (demo model available for download)
  • Instructions for download (PDF file)
  • Download demo
• Fly Ash Resistivity Model (included in ESP model)
• Fabric Filter Pressure Drop Prediction Model

Utilizing our models and expertise, we have the capability to predict how fuel changes will affect electrostatic precipitator performance. Additionally, we can estimate the effects of flue gas conditioning systems on emissions. The models assist us in analyzing performance problems by determining if a control device is performing as it should; also, the models provide a cost-effective means to evaluate upgrade strategies. Specifically, the fabric filter model is a useful tool in determining how design changes affect pressure drop (energy penalties). Our scientists developed the basic ash resistivity model, currently used worldwide, as part of the electrostatic precipitator model; the current version was updated recently to improve its predicted capability for fly ashes from coal blends.

Selective and Non-Selective Catalytic Reduction for NOx Control

Southern Research has participated in several programs investigating the performance of both SCR and non-SCR systems for NOx control.

• We have conducted numerous measurements of ammonia and SO₃ downstream from full-scale and pilot-scale units.
• In our Catalyst Test Facility, we have studied the de-NOx concentrations and SO₂ conversion properties of a variety of catalyst materials, both new and used (including honeycomb- and plate-type) for numerous clients.
• Southern Research has developed our own unique catalyst formulations and tested them, and we are currently studying the mercury oxidation potential of new, used, and regenerated catalysts in a pilot setting.
• We conducted a multi-year study for EPRI to evaluate the issues of ammoniated fly ash and the problems this type of ash might pose relative to ash sales and its use in concrete production.

Wet/Dry Scrubbing for SO₂ Control

A variety of chemical and physical test methods are used to characterize the performance of wet and dry FGD scrubber technology. Routine analyses are performed at the site (e.g., slurry pH and percent solids) to ensure proper operation. However, a number of test methods require specialized equipment (e.g., total mercury, mist eliminator performance) and are performed either on site or at off-site laboratories to assist with problem solving or system performance optimization.

Southern Research maintains laboratory facilities for conducting many of the standard chemical and physical tests on reagents, slurries, solids, and other FGD products. We are proficient in standard manual test methods and instrumental test methods with our IC, AA, ICP-MS, HPLC, GCMS, and spectrophotometer. Additionally, we perform specialized testing of limestone, gypsum, and other FGD byproducts. Many of these tests are very useful in screening and selecting reagents as well as evaluating alternate sources of supply. Southern Research is familiar with in situ sampling methods for both reactive and non-reactive slurries and reagents, and we offer the capability to measure particle size, settling rates, and total dissolved solids. These tests are primarily used for problem solving and characterizing reagent preparation (i.e., slaking and grinding) operations. Southern Research offers the following field and laboratory capabilities:

Field Sampling Methods

• Controlled Condensation Method for SO₃, including SO₂
• EPA Method 30B measurement of total or speciated mercury
• Semi-continuous instrumental measurement of total or speciated mercury
• Mist eliminator/moisture carryover rates and droplet-size distributions
• Gas flow distribution
• Isokinetic particulate sampling for total mass and particulate size distributions
• Flue gas analysis
• Reagent and slurry sampling

Lime and Limestone Analysis

• Available Lime Index
• Calcium and magnesium content, Calcium Carbonate Equivalence
• Lime or limestone slurry solids content
• Particle size
• Dissolution rate and magnesium availability

Gypsum and Scrubber Byproduct Analysis

• Weight percent solids
• Density, specific gravity
• Chlorine, fluorine, and total sulfates
• Calcium sulfate and calcium sulfite
• Major and minor dissolved metal species