Long Term Vapor Control on Petroleum Tank

Long Term Vapor Control on Petroleum Tank

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

Challenge  

A tank farm located in Texas needs to comply with TCEQ environmental regulations under 30 TAC Chapter 115 (Subchapter F, Division 3) now require that external vents on a Light Aromatic Distillate petroleum storage tank—containing Volatile Organic Compounds (VOCs) with true vapor pressure ≥ 0.5 psia—be sealed and degassed through a vapor‑tight recirculation system routed to an active control device, such as a thermal oxidizer, rather than relying on passive venting. Passive floating‑roof configurations no longer provide sufficient emissions control to meet these updated standards, which demand ≥ 90% control efficiency and a maximum outlet concentration of approximately 34,000 ppmv. The new rules also mandate regular inspections, continuous monitoring, performance testing, and comprehensive recordkeeping. To ensure zero emissions, Envent provided an engineered solution to this vapor control problem 

Solution  

Envent’s engineering team designed a system to control the vapors using a mobile tank degassing unit to perform vapor control. 

 

Benefit  

The tank farm customer was able to cost effectively comply with Compliance with TCEQ regulations under 30 TAC Chapter 115 (Subchapter F, Division 3): degassing vapor control systems ensures emissions do not escape into the surrounding environment.  The benefit is compliance and improvement of health, safety and the environment. 

Mid Crude and West LEU Turnaround

Portfolio Categories: Case Studies, Degassing, Turnaround Services, Vapor Control, and Vapor Scrubbing.

 

Challenge

A Gulf Coast Refinery scheduled turnaround required taking the Mid Crude and West LEU process units out of service. To achieve this, the units needed to be depressurized and decontaminated of LEL and H2S.

Solution

Envent supplied two temporary degassing and vapor control systems to safely and efficiently combust VOCs from the two process units. To manage high pressures, Envent provided two high-pressure regulators to reduce pressure to a controlled level. Additionally, two recirculating caustic scrubbers were deployed to neutralize H2S before the vapors were combusted by two EMECS 70 thermal oxidizers.

Benefit

Envent provided a safe, efficient, and compliant solution for removing VOCs and H2S from the process units. By utilizing high pressure regulators, the system ensured a controlled pressure reduction which allowed for safe operation. The use of recirculating caustic scrubbers effectively neutralized H2S, minimizing environmental impact. Additionally, the thermal oxidizers efficiently combusted vapors, ensuring regulatory compliance while also reducing emissions. Overall, the vapor control system streamlined the turnaround process allowing maintenance and modifications to proceed as scheduled.

Vapor Processing System for Refinery Emissions

Portfolio Categories: Case Studies and Vapor Control.

Project Summary: Vapor Processing System for Refinery Emissions
Envent Corporation recently completed a comprehensive vapor processing project in Alberta, Canada, leveraging its team of specialists and engineering staff. The project managed and processed vapors containing Volatile Organic Compounds (VOCs), hydrocarbons, and chlorinated hydrocarbons from a refinery, ensuring compliance with environmental regulations while prioritizing safety and operational efficiency.

The solution involved implementing a state-of-the-art vapor control system. Key components included high-efficiency scrubbers to neutralize acidic and water-soluble contaminants and a thermal oxidizer to safely destroy hazardous organic vapors. Degassing operations were carefully managed to capture and process emissions from storage tanks and piping, minimizing environmental impact and ensuring safe handling of potentially flammable vapors.

The system design emphasized safety features, including advanced monitoring and control equipment, redundant fail-safes, and emergency shutdown capabilities. Comprehensive testing and validation confirmed the system’s effectiveness in reducing VOCs and chlorinated hydrocarbon emissions to meet stringent regulatory standards.

This project highlights Envent Corporation’s expertise in vapor control, scrubber and oxidizer technologies, and its commitment to delivering innovative, safe, and environmentally responsible solutions for industrial emissions.

Envent Supports Canadian Barge and Railcar Loading to Reduce Benzene Emissions

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

Challenge

In anticipation of an increase in benzene emissions regulation, a Canadian facility wanted to proactively reduce their outputs for benzene loading operations. Normally, this facility would load both barges and railcars with liquid benzene for shipment to their customers. They would need to implement a vapor control system that could seamlessly integrate with these operations while reducing benzene emissions to near-zero levels.

 

Solution

Envent would provide this customer with two separate vapor control systems to support these loading operations.

 

(1) For the barge loading, Envent would provide an EDSU (Envent Dock Safety Unit) and EMECS thermal oxidizer to safely enrich displaced barge vapors as the vessel fills with product. The EDSU is constructed in full compliance to USCG 33 CFR 154 Subpart P to reduce explosion hazards for marine vessels and provide overpressure/vacuum protection for the barge containment. Vapors that are treated by the EDSU are sent to an EMECS thermal oxidizer, a mobile VCU capable of combusting VOC with upwards of 99.9% destruction efficiency.

 

(2) Similarly, for the railcar loading, Envent would provide an EMTOS thermal oxidizer unit to capture emissions purged from the railcar. The EMTOS is capable of high-flow vapor control while also achieving 99.9% destruction efficiency. Envent worked alongside the customer to integrate its logic interface with the customer’s PLC to ensure that loading could not occur unless the thermal oxidizer was fully operational.

 

Both of these systems required equipment that was complaint with Canadian federal statutes and guidelines. Envent worked directly with the local district authority to ensure that the electrical and fuel-burning appliance aspects met the requirements of the relevant CSA codes. Envent was able to manage this relationship, receive approval to set up the temporary unit, and arrange a field inspection for the system.

 

Benefit

Thanks to the integration of both vapor control systems, this customer has been able to continue their loading operations with an immediate impact on the reduction of benzene emissions. Fence line monitors stationed near these operations have had a significant reduction in non-compliance events thanks to the efficiency of the provided combustion systems reducing fugitive benzene emissions to the PPB range. Although Canada is imposing stricter HAP regulations, Envent is able to provide turnkey systems, such as these, to support our customers’ goal of maintaining environmental compliance.

 

 

Water Treatment – pH Adjustment Project

Portfolio Categories: Case Studies, Mobile Water Treatment, Odor Control, and Vapor Control.

Challenge

A customer facility had two large runoff tanks filled with several million gallons of high pH water associated with groundwater remediation. The customer wanted to drain both vessels to make room for additional wastewater, but each tank’s contents would need to be treated to a neutral pH prior to discharge. Additionally, sulfur precipitates in the wastewater posed an H2S risk as any treatment option would liberate it from solution. A vapor control system would be required to manage odor control and any off-gassing to minimize hazardous emissions.

Solution

Envent Corporation would provide this customer with an acid injection system for pH control as well as an industrial degassing thermal oxidizer system to manage H2S vapor control and other VOC vapors.

The injection system would recycle water from a low point connection back into a top location on the tank. In this process loop, Envent would inject a sulfuric acid solution directly into the wastewater. The treated wastewater would be pumped through an inline static mixer to promote an increased reaction in the water so pH could adjust more effectively. Envent would continue to recycle and treat the wastewater while taking pH readings to project tank health. Once a neutral range pH was achieved, the injection system was cut off and the tank was recirculated until the customer was satisfied.

On the vapor side, the reactions caused by adding acid into solution liberated H2S and other VOCs. To treat these vapors, Envent used a EMTOS thermal oxidizer paired with an recirculating caustic H2S vapor scrubber to treat and combust vapors. The caustic solution would neutralize H2S in quantities up to 60,000 ppm for the duration with zero emissions on the outlet. Any remaining vapors passed into the EMTOS thermal oxidizer for combustion with a 99.9% destruction rate efficiency. The vapor control system remained active as long as the tank continued to be circulated.

Benefit

Through this process, Envent Corporation was able to treat each tank’s wastewater to a pH level that was suitable for discharge. This allowed for future storage in each vessel for other customer project activities. Additionally, Envent’s vapor control system was able to mitigate hazardous off gasses and significantly reduce emissions from the tank. Envent was able to provide a turnkey solution to the issue at hand while working safely and efficiently to reach the customer goals.

Canada Butane Tank Degassing

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

Challenge

A Canada Refinery required the stripping and cleaning of a butane storage vessel as part of a facility transition to renewable diesel service. Envent was assigned the responsibility of degassing the tank and delivering continuous vapor control to minimize tank atmosphere to non-explosive levels. Furthermore, the tank needed to be inerted to prevent oxygen ingress into the vapor space, and the sub-freezing ambient temperature conditions had to be taken into account while devising a solution.

 

Solution

Envent supplied two CSA-compliant EMECS 70 thermal oxidizers to offer redundant vapor control for the butane tank. Each oxidizer unit was modified in accordance with Canadian Standards, enabling their operation under local permitting. Both units were integrated into an existing flare line system, allowing tank vapors to be channeled to each combustor. In addition, Envent provided a nitrogen generation system to introduce inert makeup gas into the tank atmosphere. Each generator was capable of heating the nitrogen prior to injection, preventing the formation of condensable materials in the vapor lines. As a result, Envent continuously swept VOC-laden vapors to the thermal oxidizers for 99.9% DRE combustion, while oxygen-free inert gas was introduced into the tank volume.

 

Benefit

The thermal oxidizer system, furnished by Envent, enabled the Canada Refinery to successfully degas the butane tank to levels appropriate for manned entry and maintenance. Envent delivered a turnkey system that complied with all local Canadian regulations, resulting in a seamless entry and setup process. The end user was also able to minimize their emissions and adhere to their maintenance schedule.

 

Keywords: Canada Tank Degassing, Degassing Tank in Canada, Canada Refinery Degassing

Refinery Wastewater Treatment – Innovative Benzene Removal Solution

Portfolio Categories: Case Studies, GHG Emission Control, Mobile Water Treatment, Vapor Control, and Vapor Scrubbing.

Challenge:
A refinery faced significant challenges with high benzene emissions from its wastewater, exceeding the Benzene Waste Operations NESHAP (BWON) requirements. Crude desalter process water, typically directed to the refinery’s Wastewater Treatment Unit (WWTU), contained high levels of dissolved benzene and phenols. These contaminants were not fully removed during primary treatment, leading to their release in an open-topped biological system, which created compliance issues. The presence of multiple constituents in crude desalter brine water makes conventional benzene stripping and removal systems difficult or cumbersome to operate effectively. As a result, benzene-laden brine water continued through their system unchecked, leading to downstream emissions.

Solution:
Envent Corporation’s engineering team, in collaboration with the refinery, developed a scalable benzene stripping solution specifically designed to address this issue. The team designed, implemented, and operated an innovative nitrogen stripping system that efficiently removed 93% of the benzene from the desalter brine water at a flow rate up to 1,250 GPM, while allowing other constituents to pass through unaffected. The stripped brine water was seamlessly reintegrated into the refinery’s wastewater treatment system. Additionally, the nitrogen-stripped benzene vapor were safely routed to a hydrogen sulfide scrubbing system and a state-of-the-art thermal oxidizer, achieving an impressive destruction efficiency of 99.9%.

Benefit:
The implemented system brought significant benefits, transforming the refinery’s wastewater treatment process. The system operated flawlessly, eliminating the need to open towers for media replacement, debris clearing, or any internal servicing, which greatly enhanced reliability and minimized operational downtime over conventional benzene stripping systems. This innovative solution also allowed the refinery to conduct extensive parameter testing, enabling fine-tuning for optimal performance. As a result, the refinery achieved a substantial reduction in benzene emissions, demonstrating Envent’s commitment to sustainability and responsible waste management.

By implementing this advanced benzene water treatment and benzene vapor control solution, Envent not only effectively addressed the refinery’s benzene emissions challenge but also reinforced our position as a leader in providing custom-tailored and sustainable environmental solutions. This project highlighted Envent’s expertise in designing and deploying cutting-edge technologies to solve complex environmental problems.

2024 Hydrocracking Unit: Depressurization

Portfolio Categories: Case Studies, Turnaround Services, and Vapor Control.

Challenge

During a scheduled refinery turnaround, a customer needed to safely degas their Selective Hydrocracking Unit to perform critical maintenance. The unit would undergo hot hydrogen stripping to purge residual hydrocarbons, but strict emission control limitations at the facility’s flare stack required an alternative vapor control system for handling high volumes of hydrogen and nitrogen gas.

To meet both safety and regulatory compliance, the customer required a turnkey mobile vapor control solution capable of managing near-100% hydrogen vapors and 100% nitrogen displacement vapors while reducing internal atmosphere concentrations to below 2% LEL.

Solution

Envent Corporation deployed three of its Envent Mobile Emission Control Systems (EMECS)—mobile thermal oxidizer units engineered for high-capacity vapor destruction. The system was designed to:

  • Combust up to 10 MMSCFD of hydrogen gas and 5 MMSCFD of nitrogen vapor streams

  • Handle depressurization of high-pressure hydrogen using auxiliary regulators

  • Maintain >99.9% destruction efficiency (DRE), exceeding EPA BACT and MACT standards for refinery vapor control

To complete the purge, Envent supported a series of nitrogen purging and huff-and-puff cycles, venting the nitrogen-rich vapors to the EMECS units until hydrocarbon levels reached LEL-free status, ensuring the system was safe for maintenance access.

Benefit

Envent’s mobile degassing solution reduced the customer’s planned downtime by an entire day, completing the hydrocracking unit degassing in under 24 hours. The use of mobile thermal oxidizers over the facility flare reduced VOC, NOx, and CO emissions, with combustion efficiency proven to be over 20 times greater than the on-site flare system.

This project showcased Envent’s unmatched ability to deliver safe, cost-effective, and compliant vapor control services during complex refinery maintenance operations. With the largest fleet of mobile thermal oxidizers, hydrogen sulfide vapor control equipment, and deep regulatory expertise, Envent enabled the facility to maintain emissions compliance, protect nearby communities, and accelerate its return to production.

Degassing Of An LNG-Powered Freight Vessel

Portfolio Categories: Case Studies and Marine Vapor Recovery.

 

Challenge

A customer tasked Envent to create a temporary system allowing for the degassing of an LNG-powered freight vessel while it was docked at port in order to perform critical maintenance on the vessel. The solution would allow the customer to continue standard operations without delay, remove Natural Gas Vapors from within the fuel tanks, and maintain compliance with Environmental Protection Agency (EPA) clean air standards as well as the US Coast Guard. Envent has USCG certifications to operate on the marine water ways and docks.

Solution

Envent supplied the customer with an EMECS 70, the industry leading mobile thermal oxidizer unit. The freighter has two 900 m3 LNG tanks each containing trace amounts of liquid LNG and pressurized vapors. Vapors are vacuumed out of the vessel using state of the art blower units and then routed to the thermal oxidizer at a control pressure and incinerated to greater than 99.9% efficiency at a rate of 60,000 CFH. This process continued until both LNG vessels were completely de-pressured. The vapor control, vessel degassing and purging of the vessels is completed within hours. Mobilization and demobilization of the marine vapor control systems is seamless.

Benefit

Envent’s solution allowed for the customer to successfully continue operations without having to delay any standard procedures. In addition, the customer was able to start maintenance work on both LNG tanks immediately after this process was completed. Both of these achievements allowed the customer to save a valuable amount of time and money.

Pipeline Evacuation Project

Portfolio Categories: All, Case Studies, and Compression.

Challenge

A West Coast natural gas transmission and distribution company required inspection & maintenance on a segment of methane pipeline. That section of pipe would need to be drepressured/ evacuated and deinventoried prior to performing the required maintenance. The client did not want to release the natural gas into the atmosphere (~1 Million lbs CO2e), or lose that volume of valuable natural gas to a flaring.  Besides the May 2023 promulgation of Part Two of the Pipeline and Hazardous Materials Safety Administration (PHMSA) MEGA Rule requires measures to enhance pipeline safety and reduce pipeline failures. PHMSA issued the Mega Rule in response to a number of incidents that highlighted the need for improved pipeline regulations. .  The customer opted for the EPA Best Management practice of Pipeline recompression.  Envent was contracted to perform this with our state-of-the-art line of mobile cross-compression pipeline evacuation units.  Operators of natural gas pipeline systems routinely reduce line pressure and discharge (“blowdown”) gas from pipeline sections to ensure safe working conditions during maintenance, testing, repair, and replacement activities.  This impacts the 3 million miles of natural gas pipelines that crisscross the US.

Solution

These portable recompression units require no additional utilities. The natural gas powered 400 Hp engine, drives the portable cooler, compressor, and alternator for battery backups. Equipped with industry standard Safety Shut Off Valve, bolt up consists of a single hose run to and from the compressor. No regulator, no additional fuel line, or no added tie in points. Suction gas pressure is introduced into the compressor, which is compressed high enough to move the volume back into the main pipeline. As suction pressure drops, the unit auto adjusts its compression ratio to meet its target discharge pressure. Envent’s fleet is comprised of 1, 2, and 3 stage compressors capable of evacuating pipelines to <5 psi, from 1400 psi! A summary report is delivered to the client with swept volume, $ saved, CO2e documentation, and much more. We provided our newest unit for this temporary compression project.

Benefit

By using Envent, the client can have the peace of mind knowing that they will have the latest in pipeline evacuation technology. Equipped with Ariel Smart Compressor technology, these units provide a state of the art advancement in temporary pipeline recompression, also known as pipeline evacuation and cross-compression: Remote monitoring, data logging, automated PSV protection (automated recycle loop), and much more. Since 1992, reliability, efficiency, and responsiveness are core values within this business segment and to Envent. In addition to the benefits listed above, the client also benefits financially, as they are able to recover the cost of the gas recovered.

Envent is ready to respond to your next pipeline evacuation needs! We help our customers throughout the US and Canada with methane mitigation and industrial decarbonization.

Emergency Natural Gas Cross Compression – 52-Inch Pipeline Leak

Portfolio Categories: Compression.

 

Challenge

A natural gas transmission customer in the Northeast U.S. required immediate intervention to address a leak on a 52-inch natural gas pipeline. The urgency stemmed from the potential for environmental impacts, natural gas loss, and regulatory non-compliance. Without a swift and emissions-free response, the incident could have resulted in substantial financial loss and air quality violations.

Solution

Envent Corporation responded within 24 hours with one of its newest Natural Gas Cross Compression Units, a three-stage mobile compression system engineered for zero emission pipeline services. Envent’s team successfully:

  • Drew pipeline pressure down to 15 PSIG in under 14 hours

  • Redirected and compressed natural gas from the impacted pipeline segment to a parallel pipeline, eliminating the need for flaring or venting

  • Completed the project using mobile compression services with no atmospheric emissions, meeting all local, state, and federal environmental standards

This operation leveraged Envent’s expertise in pipeline degassing, gas recovery services, and mobile gas recompression technologies.

Benefit

Envent’s natural gas cross compression services prevented the release of harmful greenhouse gases, achieving zero emissions during the emergency response. This not only safeguarded valuable gas resources, but also minimized downtime and environmental risk.

Our ability to mobilize nationwide within hours, supported by established offices throughout North America, ensures we can respond to critical pipeline events rapidly. With the largest and most efficient mobile gas recompression units on the market, Envent continues to lead the industry in pipeline evacuation services, natural gas compression, and flareless pipeline maintenance—providing safe, compliant, and cost-effective solutions under pressure.

Flare Gas Scrubber System & Compliance

Portfolio Categories: Case Studies and Vapor Scrubbing.

Challenge

An Envent customer needed to perform maintenance on their distillation unit, SATS unit, and flare. For this project, the customer rented a temporary flare to combust VOCs while their main flare unit was serviced. The customer came to Envent requesting sour gas scrubbing. H2S levels up to 15,000 ppm were to be expected in their flare gas. Customer also requested that the H2S concentration be neutralized to remain in compliance with the EPA. In order to stay in compliance, H2S concentrations could not exceed 160 ppm at their temporary flare.

Solution

Envent proposed a customized scrubber system to neutralize the sour gas so that the customer could be in compliance with the EPA. Envent mobilized multiple pieces of equipment including three ESCRUB-2000s, three high pressure knockout pots, and two frac tanks. The three scrubbers and knockout pots were connected directly to the customer’s flare header in parallel in order to handle the highest flows and concentrations that were provided. The scrubber system was manned 24/7 by a team of two technicians and one crew lead to ensure operation and caustic change-outs were performed safely and efficiently.

Benefit

Envent provided an efficient setup which neutralized the H2S concentrations in the customer’s sour gas. The scrubber system was manned 24/7 to ensure equipment was fully functional and to keep the customer in compliance. Envent’s customer was satisfied with the professionalism and safe work practices when handling hazardous chemicals.

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