Sour Tank Vapor Control

Sour Tank Vapor Control

Portfolio Categories: Vapor Scrubbing.

Challenge
A sour water tank high in H2S needed vapor control provided during a turnaround while maintenance was done in the surrounding area. The H2S concentration was as high as 500,000ppm during parts of refinery operations. The H2S needed to be reduced to a safe level while the vapors were treated and vented to atmosphere.

Solution
Vapors from the tank were routed to a liquid recirculating scrubber, which reduced the H2S concentration to an acceptable limit to where the vapors could be sent to a thermal oxidizer. Envent monitored the inlet and outlet of the liquid scrubber to ensure efficient reduction of the H2S. When liquid break through was approached, the media was changed out to guarantee the thermal oxidizer was always combusting vapors that were below the threshold of EPA mandated levels of H2S combustion.

Benefits
Envent was able to successfully reduce the H2S emissions in the area so a turnaround could continue. Also, Envent was able to adjust to severe cold conditions and prevent solidification of the liquid media. This prevented costly delays while maintaining safe turnaround operations, eliminated odors and kept the customer in compliance.

Goleta, CA, Vacuum Truck Scrubber

Portfolio Categories: Vapor Scrubbing.

Challenge
A major refinery in California was to degas a tank filled with crude oil, and blanketed with nitrogen. Due to irregularities with the tank, there was excess liquid left inside the tank after being emptied. A vacuum truck was brought in to pull out any residual crude oil in the tank. A solution was needed in order to degas the tank, as well as control the vapors on the vacuum truck when filling.

Solution
Envent provided a vapor control/degas combination solution to the refinery. An EMTOS unit would degas the tank, while a carefully designed scrubber system would control vapors coming out of the vacuum truck. The scrubber system was to be filled with one Envent’s proven liquid media. The scrubber system worked great with the passive flow from the vacuum truck. The vapors were displaced by the crude oil coming in, and were sent into the scrubber to be controlled. The Envent specially designed scrubber allows for a high surface area contact for all vapors entering the scrubber.

Benefit
Envents highly trained personnel ensured the both the scrubber and EMTOS were operated at full efficiency. Through constant monitoring, and good communication with all parties, Envent was able to provide an ideal solution to the customer. Envent was also able to save the customer thousands in potential fines, as well as avoiding a potential product release.

Emergency Pipeline Degas

Portfolio Categories: Degassing.

Challenge

A 12-inch propane pipeline was undergoing re-commissioning by a gas manufacturing company when a leak was detected. The affected segment, approximately 16 miles long, was isolated between two stations and held an estimated 12,000 barrels of liquid propane. Due to the high vapor pressure and flammability of propane, the customer needed to safely combust the product as quickly as possible while minimizing emissions and maximizing safety.

Solution

Envent Corporation designed and executed a turnkey vapor control and degassing solution using:

  • Two 200-gallon/hour propane vaporizers to convert liquid propane into vapor

  • A 20 MMBTU/hr Envent Mobile Thermal Oxidizer (EMTOS) to achieve full vapor destruction with >99.9% destruction efficiency (DRE)

  • A dual-use strategy where vaporized propane served as combustion fuel and was also routed into the process line for destruction, increasing efficiency and reducing flaring

This thermal oxidation solution allowed the pipeline to be depressurized and degassed in record time—4 times faster than traditional methods—while ensuring full compliance with emission control regulations and maintaining a safe process.

Benefit

Envent’s use of a thermal oxidizer over a mobile flare provided critical safety advantages, including integrated detonation arrestors and real-time temperature and vapor monitoring. This minimized the risk of backflow ignition and ensured safe propane vapor control during a high-pressure operation.

The pipeline was completely depressurized and free of liquid propane vapors well within the customer’s timeline, showcasing Envent’s expertise in zero emission pipeline services, mobile vapor scrubbing, and flareless pipeline evacuation.

This project highlights Envent’s ability to deliver fast, compliant, and engineered vapor control solutions in pipeline emergencies—with safety, speed, and regulatory excellence at the forefront.

EICE – Naphtha Tank Degas

Portfolio Categories: Degassing.

Challenge
A tank farm customer requested Envent degas a 123 foot diameter naphtha tank. The customer also requested that an internal combustion engine unit be used for the degas.

Solution
Envent’s custom EICE unit was mobilized for the job within the hour. Envent was able to stage the EICE unit within a 8͛*25͛ footprint to minimize operations disruption. The EICE captured and destroyed greater 99.428% of all vapors during the degas of the tank.

Benefit
The tank farm was able to continue operations around the tank while degassing was in progress due to the small footprint of the EICE. This saved time and money for the tank farm by not having to relocate critical equipment.

Floating Roof Gasoline Tank Degas

Portfolio Categories: Case Studies, Degassing, GHG Emission Control, and Vapor Control.

Challenge

A refinery contacted Envent Corporation to perform tank degassing on a 150,000-barrel internal floating roof (IFR) tank in preparation for inspection. The tank contained gasoline, a product with a high BTU per cubic foot, making it essential to size a thermal oxidizer correctly to avoid unsafe operating conditions. The tank’s vapor composition posed potential hazards due to volatile organic compounds (VOCs), and failure to degas effectively could delay the inspection schedule and result in significant fines.

Solution

Envent’s engineering team evaluated the tank’s vapor space, flow rate, and product BTU content to select the appropriate mobile thermal oxidizer from our industry-leading fleet. The chosen EMTOS unit met EPA BACT standards, capable of operating safely above 1400 °F to ensure >99.9% destruction efficiency (DRE) of high-BTU vapors.

Key actions included:

  • Matching pump-out flow rates with vapor destruction capacity to avoid applying excessive vacuum that could collapse the floating roof

  • Advising the customer that water washing must not begin until LEL levels are <50%, ensuring safe tank cleaning operations

  • Capturing and destroying all vapors using refinery vapor control methods tailored for high-performance tanks

This approach ensured complete control of the emissions, even as the vapor profile changed during the degassing process.

Benefit

With Envent’s expert planning and use of a properly sized thermal oxidizer, the refinery safely completed the tank degassing and conducted the inspection before the regulatory deadline—avoiding costly non-compliance penalties. The client also gained critical operational insight regarding tank vapor management and safe LEL thresholds during water washing.

This project highlights Envent’s leadership in refinery degassing solutions, turnaround vapor control, and high-BTU vapor control systems—delivering safe, fast, and compliant results for complex tank operations.

Southern California, Sour Tank Inert Degas Operations

Portfolio Categories: Degassing.

Challenge
A nationwide petroleum company had an API inspection deadline on a 110’ diameter External Floating Roof Tank containing sour crude product. There was an acute hazard in the tank for pyrophoric materials, materials which ignite in the presence of oxygen without an ignition source. The petroleum company understood that they would need an all-star team to degas, clean, and inspect this tank.

Solution
Envent has degassed numerous sour tanks with pyrophoric hazards. In fact, this extremely sensitive operation is standard procedure for Envent. Many rounds of planning occurred to prior to the project to ensure that every piece of equipment and every fitting was in place. Nothing can be out of place with tank degassing, and especially for pyrophoric tanks. Envent coordinated with a nitrogen supplier to provide the inert atmosphere required to safely degas the tank. Envent’s thermal oxidizers were staged to burn down the explosive atmosphere of the tank. By carefully controlling the pressure and atmosphere of the tank, Envent’s expert technicians were able to carefully bring the tank to an inspection-ready state, two weeks prior to the deadline.

Benefit
While a safe sour tank degas has no small price tag, it is well worth it to the tank owner. With such an acute hazard, there is no room for error. Otherwise, the costs could include property damage, or worse, a life. With Envent’s extensive experience with rare and dangerous tank operations, shouldn’t you trust them to provide you with these degassing services?

St. James Louisiana, ETP Air Stripper


Challenge
A chemical plant located in Louisiana had a boiler break down on one of their air stripper systems. In normal operation, the boiler was used to bring down the liquid level in their storage tanks. With the boiler down, the chemical plant was unable to properly run their air stripper system. Due to the highly specific requirements of the boiler, renting a replacement was a highly expensive, and time consuming process.

Solution
Envent engineers designed a solution to provide an EMTOS 4500 unit while the repairs were made to the boiler. Envent’s specially trained operators matched, and maintained the necessary flow to handle the blower used on the air stripper. Two technicians were provided per shift in order to monitor the EMTOS, and to ensure the unit was keeping up with the flow demands from the air stripper.

Benefit
The chemical plant was able to minimize their cost by providing power and fuel to cut wet cost during the operations. Envent’s solution allowed the plant to safely operate their system, and bring down levels in their tank.  Through successful planning and execution, Envent saved the customer millions in fines, and rental equipment.

Texas City, Vapor Control, Emergency Response

Portfolio Categories: Degassing.

Challenge
A terminal company in Texas City utilized a flare to control vapors on their storage tanks. When the flare failed, Envent was called to control excess vapors. Envent responded to this emergency, and was able to arrive onsite within four hours.

Solution
Once the emergency call was placed, Envent’s on call personnel was able to mobilize the EMECS 42 unit onsite. With the capability to burn over 42 million BTU per hour, the EMECS was an excellent bypass option while the flare was repaired. In 12 hours, and the flare was placed back into service. With such a short repair window, quick response time was imperative. Within four hours of making the call, the excess vapors were being controlled by Envent.

Benefit
Envent keeps a fleet of vapor control solutions ready to move on a moment’s notice. Having a rigid preventative maintenance schedule, coupled with active on call personnel, Envent is always ready for any emergency.

Fort Worth, Texas, Mobile Water Treatment

Portfolio Categories: All and Mobile Water Treatment.

Challenge
A tank farm had collected over 600,000 gallons of storm water runoff. The storm water was pumped to two holding tanks waiting for treatment. The storm water needed to be treated for total suspended solids, oil and grease, benzene, toluene, ethylene and xylene. The treated water would be discharged directly into Fort Worth’s sewer system.

Solution
Envent technicians constructed a 4” temporary water pipeline over 500 feet in length to carry the storm water from the two holding tanks to Envent’s mobile water treatment system. The storm water was first filtered to remove the oil and grease, plus any suspended solids. Then a media was used to adsorb the BETX compounds.

Benefit
Envent was able to predict the media usage using 20 years of water treatment knowledge, and approved adsorption media calculations to ensure full attainment to discharge permits. The treatment system saved the customer thousands of dollars compared to hauling off or other options.

Southern California Construction Site, Dewatering Operations

Portfolio Categories: Mobile Water Treatment.

Challenge
A general contractor was tasked with making major renovations to a utility company’s electrical transmission infrastructure. This massive project occurred on 70 acres of public and private land over a period of 6 months. The renovations required the excavation of 30 sites to install new foundations and access vaults to support future infrastructure. Construction dewatering was a major concern for the general contractor because the excavations were as close as 500’ from the ocean.

Solution
Envent’s engineering team thoroughly investigated the exploratory borings that were performed across the site to analyze the soil conditions. Based on the conditions of the site, a dewatering plan was developed. Permitting the installation of wells was smoothly addressed by Envent’s engineering team. Wells were then installed at the excavation sites to remove groundwater prior to excavation operations. The groundwater was collected into several water treatment systems, located across the extents of the project. Local discharge locations had been evaluated and the sewer system was determined to be the most feasible option to discharge the treated groundwater. Envent’s engineering team coordinated with local regulatory organizations to ensure that the discharge permit was satisfied prior to the discharge of treated water. The water treatment systems were designed in accordance with local regulatory organization requirements for water treatment systems. The treatment systems included settling tanks, filtration vessels, and activated carbon treatment systems to address all known and expected contaminants of the site.

Benefit
The true benefit of treating water on-site is demonstrated by a project of this scale. There is always some degree of uncertainty when it comes to the flow rate of water that any given dewatering well can produce. The critical benefit of Envent’s dewatering and treatment system is that the savings would have scaled relative to the amount of groundwater produced – regardless of the quantity. In this case, the general contractor saved nearly $1,800,000 – when compared to transporting the water off-site. More importantly, the general contractor would have continued to save, even in the unexpected cases of higher groundwater flow rates and rain events

Southern California Refinery, Compliance Engineering

Portfolio Categories: Degassing.

Challenge
A Southern California refinery was operating a thermal oxidizer in the South Coast Air Quality Management District (SCAQMD). Permit conditions regulated the maximum permissible flow rate as 250 SCFM to the thermal oxidizer. The facility used an automated data recorder to monitor the flow rate entering the unit. When the recorder registered a value of 267 SCFM, the refinery needed to find a solution to their problem as soon as possible, as SCAQMD fines would build up with each passing day.

Solution
Envent’s I&E team mobilized the same day to analyze the control system of the thermal oxidizer. The problem was quickly determined to be caused by an error with the automated data recorder. Envent’s I&E team retrofitted the sensor equipment and recalibrated the recording system. In the meantime, the refinery needed to give an explanation to the SCAQMD concerning this potential Notice of Violation (NOV). The refinery contracted Envent’s team of qualified Professional Engineers to conduct an analysis on the exhaust blower which controlled the vapor flow rate to the thermal oxidizer. With a qualified background in mechanical engineering, the team of PE’s were able to draft a concise engineering report explaining why it would not be physically possible for the blower to produce the violation flow rate of 267 SCFM. Based on the analysis, the reading must have been caused by sensor error, thus putting the SCAQMD at ease that no violations had occurred.

Benefit
The refinery knew that Envent was the national expert for vapor control technology. Not only was Envent able to diagnose the problem and immediately procure a new sensor, but they were able to recalibrate the refinery’s equipment. As with all projects, when engineering support was needed, Envent’s team of qualified engineers was there to provide support. When you consider vapor control providers, take into account the price of true quality

Southern California Pipeline Facility, Vapor Control Operations

Portfolio Categories: Vapor Control and Vapor Scrubbing.

Challenge
A national pipeline logistics company with several pipelines crossing Southern California regularly needs to perform maintenance and repairs. Project scopes range from one vacuum truck removing a few barrels of product from a single valve box over a few hours to full blown, multi-line segment drain-downs, nitrogen sweeps, integrity tests, and pipeline reinstatement. The challenge lies in the storage of residual product in temporary tanks, the scrubbing of vacuum truck exhaust, and the efficient combustion of pipeline vapors in thermal oxidizers during blowdowns and degassing. These vapors are being scrubbed within South Coast Air Quality Management District (SCAQMD) – arguably the most regulated air in the world.

Solution
Envent regularly provides temporary tank vapor control systems using their line of carbon vessels, sized efficiently based on stored product influent flow rates into a single tank or banks of 20 tanks. These systems are closely monitored and the results are recorded to document system effectiveness. Product going into these tanks is vacuumed from the pipeline segments. Those vacuum trucks are usually located at several key locations across the pipeline network. To properly abate the vapors off the vacuum trucks, Envent will supply three, four, sometimes even five separate EVAC 1000 trailer mounted vacuum truck exhaust scrubbers for quick deployment and relocation. As the vacuum trucks move from line segment to line segment and then to the temporary tanks, EVAC scrubbers are re-positioned for reliable intermittent or continuous use. When the pipeline needs to be blown down or swept with nitrogen or refilled back into service, Envent’s EMTOS and EMECS lines of thermal oxidizers are the best available control technology for safety, efficiency, and reliability.

Benefit
Envent’s line of carbon vessels range from 200 LB carbon drums up to 5000 LB carbon vessels. Depending on the quantity of temporary tanks, product stored, and duration of project, Envent can provide low maintenance passive vapor scrubber systems. Envent’s temporary tank systems can be set up adjacent to residential areas without any concern for odors leaving the facility. The EVAC line of vacuum truck scrubbers are a versatile equipment line. These scrubbers are reliable because there are no moving parts, no emissions to report, no waiting for equipment warm-up, and can even be operated by the customer for increased savings. Finally, the EMTOS and EMECS mobile thermal oxidizers range from 250 CFM rating to 6000 CFM rating and provide up to 70″ water column vacuum for fast blowdowns and nitrogen sweeps. And with over 13 different thermal oxidizers sized appropriately for the particular project parameters, Envent provides odor free results with 99.999% destruction of vapors

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