Thermal oxidation of fossil fuels or other sulfur containing material generates sulfur dioxide, SO2. Petroleum refineries, secondary lead smelters, paper and pulp manufacturers, geothermal power generators, waste incinerators, and mineral processors are the primary emitters of SO2. SO2 contributes to respiratory illness and aggravates existing heart and lung conditions.   It contributes to acid rain, damaging vegetation, sensitive ecosystems, and waterways. It is one of the six common criteria pollutants. Criteria pollutants are subject to primary and secondary National Ambient Air ..read more

For economic reasons, a refinery desires to maintain refining capacity during periodic maintenance shutdown of their sulfur recovery unit (SRU).  A temporary caustic scrubber had been used to remove sulfur from sour fuel gas  during shutdown but was quite expensive and logistically difficult.  Several technologies were evaluated to replace the temporary scrubber for a permanent, lower cost solution. Considered technologies included a reverse jet scrubber, fiber film contactor, and an Envitech packed bed caustic scrubber. Envitech’s packed bed scrubber was selected.  The sc ..read more

A catalyst production facility operates a calciner that generates a small stream of hot dirty gas. The exhaust is cleaned using a particulate/SO2 scrubber followed by a vertical entrainment separator.  The configuration is problematic for operation.  The scrubber requires a long duct run from near grade to the scrubber inlet flange.  There is a U-shaped bend to the inlet flange.   Particulate condenses in the duct and plugs over time.  The process is routinely shut down to clean out accumulated material. This limits production capacity.  The customer sought t ..read more

A dual purpose, low flow scrubber is needed for a facility that extracts lithium from geothermal brine. The scrubber treats a chlorine (Cl2) rich stream from a chlor-alkali process and HCl from a caustic storage tank vent line.  The scrubber is installed outdoors in a desert environment with significant seismic and wind requirements.  Temperatures reach 113oF in the summer.  The furthest emission source is 70 ft away. The scrubber will use and induced draft (ID) fan to pull exhaust gas from the upstream sources. The fan must be corrosion resistant and capable of pulling a low fl ..read more

In 2012 Envitech supplied a wet electrostatic precipitator (WESP) to remove submicron particulate and lead particles from a metal processing coating device. Envitech recently completed the start-up of a 2nd WESP for a different coating device at the same facility. Both systems are designed to remove greater than 95% of lead from low inlet concentrations. The inlet lead concentration is similar to that of a secondary lead smelter reverb furnace. Click on the link to read about the secondary lead smelter WESP. The scope of supply for the new system includes a WESP, instruments, control system ..read more

The California Air Resource Board (CARB) is considering new rules in California affecting chrome plating processes for metal finishers. An estimated 100,000 people participate in the chrome plating supply chain. A hundred and fifty chrome plating operations are in California. Eighty to ninety of those are for defense and aerospace applications. Chrome plating is a process where an electrical charge is applied to a plating bath containing an electrolytic salt (chromium anhydride) solution. The electrical charge causes the chromium metal in the bath to fall out of solution and deposit onto a met ..read more

There are several different waste incinerator source categories controlled by EPA standards under the Clean Air Act (CAA). These include hazardous waste combustors (HWC), sewage sludge incinerators (SSI), municipal solid waste (MSW) incinerators, commercial and industrial solid waste (CISWI) incinerators, and Hospital, Medical, and Infectious Waste Incinerators (HMIWI). Each incinerator type has its own Maximum Achievable Control Technology (MACT) standard which establishes technology based limits for emitted HAPs. MACT standards are part of the National Emission Standards for  Hazardous ..read more

A common wet scrubber air pollution control application is the removal of sulfur dioxide (SO2) and related compounds from combustion processes. This class of compounds is often referred to as SOx. The formation of SOx and SO2 occurs from sulfur bearing fuels or materials oxidizing to SO2 upon combustion. SO2 has negative health effects and can contribute to respiratory illness, especially in children, the elderly, and individuals with pre-existing conditions.   In addition to health effects, SO2 contributes to acid rain which can harm plants, trees, rivers, streams, and lakes. SO2 al ..read more

A refinery is upgrading an SO2 quencher-scrubber treating incinerator exhaust from a thermal oxidizer of a sulfur recovery unit (SRU).   The quencher is a re-purposed eductor type Venturi that is at end of life and will be replaced.  Scrubber recirculation water passes through a heat exchanger to subcool the gas, eliminating make-up water.  Upstream heat recovery is removed which increases the gas flow rate to the scrubber. Duct design to the new quencher must ensure flange connections properly mate and will withstand stresses and loads.  A 180o ductwork bend makes the ..read more

Industrial facilities are increasingly called upon to consider the use of wet electrostatic precipitators (WESPs) for emissions control as regulations for PM 2.5 and specific heavy metals become more stringent. Facility and Environmental, Health, and Safety (EHS) Managers may need to become familiar with WESP technology and how they can be applied to their facilities. WESPs date back to the 1970’s and are a tried-and-true method for removing submicron particulates, aerosols, SO3, opacity, and condensed heavy metals. They are generally robust and suitable for 24/7 continuous operations. Their u ..read more