Emergency Vapor Scrubbing – Southern California Refinery

Emergency Vapor Scrubbing – Southern California Refinery

Portfolio Categories: All, Case Studies, Odor Control, Vapor Control, and Vapor Scrubbing.

Challenge
A refinery in Southern California experienced severe plugging in a section of piping downstream of their coker unit.  In order to eliminate the restriction, the refinery needed to perform a line break and attempt to clear the line.  The column attached to the line contained high concentrations (2500 ppm) of ammonia vapors and the facility was unable to empty this column using their existing equipment.  This outage was severely impacting production and had the potential to affect ongoing maintenance work – the refinery needed a contractor to mobilize immediately to provide an emergency vapor scrubbing solution.

Solution
Envent is a specialist – and we mobilize 24/7/365 to provide customized, engineering solutions.  The Envent engineers designed an SCAQMD permitted vapor control system using the ESCRUB 2000-SS, a dual-column, recirculating scrubber preloaded with phosphoric acid to neutralize the ammonia vapors, followed by two granular activated carbon vessels to remove all hydrocarbon contaminants.  Envent staffed the job around the clock with two technicians for the next week.

Benefit
The customized solution was mobilized within 24 hours and all of the ammonia vapors were neutralized successfully.  The customer greatly appreciated the fast call to action and a reliable solution that worked from the start.

Freeport, Texas, Out of Service Storage Tank Contaminated Water Treatment

Portfolio Categories: All and Mobile Water Treatment.

Challenge
A facility on the Gulf Coast had an out of service tank that once contained Pyrolysis Gasoline (Pygas), but had recently been used to store various waste streams and contaminated water.  The 132′ diameter, 56′ tall internal floating roof tank was due for inspection and the facility had no way to treat the contaminated water, which contained a myriad of oils and particulates.

Solution
Envent engineers began with a job walk and gathered samples from the tank.  The team tested a number of coagulants during an extensive bench test and worked with the facility to ensure that the selected coagulant was compatible with their downstream treatment processes.  Envent used the coagulant with the Envent Cavitated Air Flotation (CAF) Unit – an 88 GPM workhorse to treat suspended particles in water.  The CAF unit was under vapor control to ensure safe operation, the waste stream was stored for disposal, and the effluent was held in a temporary tank to allow sampling prior to discharging to the facility’s downstream treatment process.

Benefit
Envent estimated that the job would take eight days to process 1,000,000 gallons of contaminated water.  The project lasted just under six days and all of the processed water was free from oil and suspended particles.  The facility was able to process the water and begin the tank inspection process.  The treatment system saved the customer time and money compared to deep-welling or attempting to run the contaminated water through their own system.

Deer Park Refinery, Complete Turnaround Solution

Portfolio Categories: All, Case Studies, and Turnaround Services.

Challenge
A refinery conducted a turnaround on a Hydrocracker unit in the Deer Park area, and they required a complete turnaround solution.  Having worked with Envent before, the customer knew that we could solve all of their needs. We first needed to depressure the Hydrocracker unit, initially comprised of nearly pure Hydrogen, and then perform multiple nitrogen sweeps. Simultaneously, Envent provided vapor control for temporary frac tanks used to store chemical wash water. Finally, we were able to decontaminate the chemical wash water once the decommissioning was complete.

Solution
The engineers at Envent developed three separate systems, including the use of the Envent Turnaround Safety Skid, to surpass the customer’s requests.  The Turnaround Safety Skid, equipped with redundant high pressure regulators and shutdown systems for both the process stream and the supplemental fuel stream, along with the EMECS 70 and two EMECS 42s, safely depressured the unit. An exchanger and receiver were used in conjunction with the EVAC 1000 to control the vapors from the temporary frac tanks. Lastly, liquid phase carbon scrubbing vessels were available to process the contaminated chemical wash water. Three separate systems, working together, to provide a total, engineered solution.

Benefit
Envent provided all of the equipment, technicians, and engineers to complete the job safely and ahead of schedule. In fact, this was the fastest the Hydrocracker had ever been decommissioned in the history of the facility – a full day ahead of schedule. The Envent engineering team supported all phases of the design and implementation process, including all PHA, HAZOP, and MOC processes leading up to the turnaround, working in tandem with the customer.

Houston Area Refinery, FCCU Turnaround Service

Portfolio Categories: All, Case Studies, and Turnaround Services.

Challenge

A refinery customer planned a turnaround for their Fluidic Catalytic Cracking Unit and was in need of turnaround service support.  Because Envent has demonstrated the ability to help our customers meet the new, stricter emission limits imposed by the new Petroleum Refinery Sector Risk & Technology Review (RSR) regulations, the refinery knew they were getting the best.  The refinery had to depressure their unit from 35 PSIG at 3500 SCFM to bring the LEL concentration below 10%.  This stream would also include high H2S and temperatures up to 100 ⁰F.  The customer estimated the depressurization and decontamination to last approximately six days.

Solution

Envent mobilized two EMECS-42 thermal oxidizers, one ESCRUB-6000 recirculating scrubber to remove H2S, two KO pots, and all associated safety equipment to complete the decommissioning.  A key component of the safety equipment was an automatic safety valve to isolate both systems in the event of a process upset.

Benefit

Envent was able to safely complete the unit depressurization and decontamination without incident, working with the refinery at each step along the way to finish two days faster than planned.  Envent has become the leader in turnaround support.

Port Arthur Refinery, Delayed Coker Turnaround

Portfolio Categories: All, Case Studies, and Turnaround Services.

Challenge

A refinery customer planned a turnaround for their 4 Drum Delayed Coker Unit.  Due to the stricter emission limits imposed by the new Petroleum Refinery Sector Risk & Technology Review (RSR) regulations, the refinery needed Envent’s help.  The refinery had to depressure their unit from 50 PSIG down to 5 PSIG, at which point they would begin a combination of steaming up to 20,000 lb/hr of steam and sweeping with nitrogen up to 1100 CFM.  This project involved varying process heat values, high H2S levels (>800 ppm), temperature swings, and the requirement to maintain low pressure on the facility’s flare header (<46″ WC).

Solution

Envent mobilized two EMECS-42 thermal oxidizers, two ESCRUB-6000 recirculating scrubbers to remove H2S, two condensers to handle the steam, a pipeline separator to remove heavy liquid, and all associated safety equipment to complete the decommissioning.

Benefit

Envent’s solution maintained environmental compliance throughout the entire project, and completed the job with zero safety incidents.  Through the use of Envent’s customized flareless turnaround solution, the Delayed Coker Unit was completed three days ahead of schedule, saving the customer over $6MM.

Deer Park Refinery, Hydrocracker Turnaround

Portfolio Categories: All, Case Studies, and Turnaround Services.

Challenge
A refinery conducted a turnaround on a Hydrocracker unit in the Deer Park area. The facility required a flareless turnaround due to the new Petroleum Refinery Sector Risk & Technology Review (RSR) regulations. In order to remain in compliance and shorten the duration of the decommissioning phase, Envent was called upon to depressure the unit.

Solution
The engineers at Envent developed a plan using three EMECS 42 thermal oxidizers, averaging 3400 SCFM, to depressure the unit from 180 PSI of nearly pure Hydrogen. Envent worked hand in hand with the refinery and a chemical cleaning company to first depressure the unit, and then complete three separate sweeps of nitrogen to decommission the unit.

Benefit
Envent’s solution maintained 100% compliance throughout the project, as documented on the Enforce Compliance Report. The engineers and technicians on site completed the turnaround safely with zero incidents.  Envent has since helped the same facility on four additional turnarounds.

Customer Commendation

"With the new Flare-less regulations the Hydro-Cracker turnaround would have been delayed by several days without your assistance. In my opinion your portable combustion units were most effective in addressing our needs. The capability of your engineered system to handle the temperature and flow rates of our unit depressurization was key to the success of our turnaround." -Refinery Operations Coordinator

Emergency Response – Soil Degas

Portfolio Categories: All and Soil Vapor Extraction and Remediation Systems.

Challenge

An underground natural gas pipeline was discovered leaking in a residential area. Although the pipeline owner quickly fixed the leak, much of the soil had become saturated with odorized natural gas. In order to protect the nearby residences and shops, the company needed an engineered solution to degas the soil as quickly as possible.

Solution

Envent worked with a geotechnical expert to drill 20 wells in the affected area in order to quickly pull the natural gas vapors from the soil. Slotted PVC was placed in each well and manifolded to one of two Envent Mobile Thermal Oxidizer (EMTOS) Systems. Each EMTOS unit was able to continuously pull explosive, odorized vapors from each well and burn them in a controlled environment. After the first day of operation, local residents stopped complaining about odors, and after the sixth day no hazardous natural gas could be detected in the air coming from the ground.

Benefit

Envent was able to respond immediately and provide a carefully engineered degas solution with the safety of the community in mind. Having the nation’s largest selection of mobile thermal oxidizers, Envent could provide units of optimal size along with all necessary hoses and fittings to pull vapors from 20 different wells. Methane has a global warming potential (GWP) approximately 28-36 times higher than CO2 (1), and Envent’s units were able to oxidize the natural gas and odorants to CO2 with 99.9% efficiency. Lastly, the customer and community were very satisfied. Emergency response procedures have been written to perform the same operations should a similar situation happen in the future.

(1) https://www.epa.gov/ghgemissions/understanding-global-warming-potentials

Port Arthur Refinery, Flareless Hydrocracker Turnaround

Portfolio Categories: Degassing, Turnaround Services, and Vapor Scrubbing.

Challenge

A refinery customer had to complete a flareless turnaround involving their Hydrocracker Unit.  The stricter emission limits imposed by the new Petroleum Refinery Sector Risk & Technology Review (RSR) regulations would not allow them to use the full capacity of their existing flare.  This meant that they would take much longer than in the past to prepare the Hydrocracker Unit for maintenance.

Solution

Envent mobilized three EMECS-42 thermal oxidizers, two ESCRUB-6000 recirculating scrubbers, and all associated safety equipment to complete the decommissioning.  This process involved the initial depressuring of over 99% hydrogen of the Hydrocracker unit, and was followed by multiple nitrogen purges and scrubbing of residual Hydrogen Sulfide (H2S) vapors.  Throughout the entire project, Envent maintained low pressure (<27” WC) on the refinery’s flare header by using a supplemental, variable frequency drive blower to prevent unauthorized emissions.

Benefit

Envent’s solution maintained environmental compliance throughout the entire project, and completed the job with zero safety incidents.  Through the use of Envent’s customized flareless turnaround solution, the Hydrocracker Unit was decommissioned on schedule.

Vapor Control – Pipeline Sour Crude

Portfolio Categories: Vapor Control.

Challenge

A California oil company needed a trusted vapor control provider that could meet strict safety standards, comply with rigorous air district permitting, and deploy reliable mobile degassing equipment. With projects located throughout South Coast AQMD and Central California—some of the most strictly regulated air quality regions in the world—the client required a partner capable of delivering a cost-effective, fail-safe vapor control solution for multiple remote tank degassing operations.

Envent, known for its industrial degassing, pipeline vapor control, and refinery vapor control services, was selected due to its unmatched safety record and the largest fleet of mobile thermal oxidizers in the U.S.

Solution

Envent mobilized two Envent Mobile Thermal Oxidizer Systems (EMTOS) from its fleet of 14 uniquely sized units. This allowed for flexibility throughout the project:

  • A smaller mobile thermal oxidizer was deployed for continuous low-flow vapor control, minimizing pilot gas consumption

  • A high-capacity unit was introduced when rapid tank degassing was required to move through the explosive range and achieve <10% LEL, as required by tank vapor management plans

  • Both systems were configured for 100% redundancy, ensuring operational reliability throughout the job

  • The flexibility to scale up or down based on vapor flow made this a highly economical vapor control solution

Benefit

By leveraging Envent’s engineered vapor control systems, the client minimized both cost and environmental risk. The smaller unit reduced pilot gas demand, while the larger EMTOS system allowed for efficient, high-flow vapor destruction during critical degas operations—ensuring compliance with EPA BACT requirements (>1400 °F combustion) and South Coast AQMD emission limits.

With mobile vapor control, thermal oxidizers, and complete turnaround vapor control solutions, Envent delivered the flexibility, compliance, and reliability the client required. The project demonstrated why only Envent has the fleet, expertise, and permitting knowledge to support complex, multi-phase tank degassing for refineries and terminals—especially in California’s most challenging regulatory environments.

Midwest Facility – Meeting EPA Requirements


Challenge
A mid-west facility was under a time and regulatory constraint to reduce H2S emissions coming from a cold feed storage tank. There were many requirements that had to be met to sufficiently perform this job including having a high flow at the system. Envent had to figure out a way to knock out aerosol and oily carryover, and scrub H2S for an undetermined duration with no equipment failure.

Solution
Envent worked with the facility to provide a series of passive scrubbers, recirculating scrubbers, knockout pots, and blowers to adequately perform the job. Numerous studies were completed to consider pressure drop, clogging/plugging, spikes in LEL and H2S changes in seasonal patterns, including maintenance. Our Envent Engineers worked hand in hand with the facility’s engineers to scope the project and account for any potential hurdles to maximize system performance and reliability.   

Benefit
Providing engineering, equipment, and specialized technicians allowed the facility to meet the deadline of lowering their H2S, which allowed them to continue operation. The extensive knowledge of scrubber utilization and maintenance provided by Envent gave the customer various operations to maximize performance. Without this acquired knowledge, longevity and equipment failure would’ve continued to present a challenge for the facility.

Northern California Refinery, Sour Naptha Degas

Portfolio Categories: Degassing.

Challenge
In mid April 2016 a Northern California Refinery discovered a seal leak on a 145 ft. diameter x 75 ft. tall above ground external floating roof storage tank that was in Sour Naptha service. Due to the sour nature of the product in the tank, this seal leak presented substantial safety and environmental hazards to any personnel working at the refinery as well as to the surrounding community.

Solution
Envent responded quickly to the Northern California Refinery’s emergency and provided a BAAQMD permitted dual column packed bed recirculating H2S scrubber along with our EMTOS-2000. Initial concentrations of H2S during the degas were ~600ppm at the inlet of the H2S scrubber and 0 at the inlet to the EMTOS 2000, thermal oxidizer. Envent simultaneously managed N2 flow keeping O2 less than 12% eliminating pyrophoric hazards.

Benefit
Our engineered solutions and expedited deployment allowed us to safely degas this Sour Naptha tank. Once the concentrations of H2S dropped to below zero ppm we were able to utilize a bypass around the scrubber to enable a higher flow rate from the tank. This allowed us to finish the tank five days faster than expected. Ultimately with the fast turnaround, Envent was able to save this Northern California refinery ~$30,000 on the project and protected the community from hazardous H2S vapors.

Southern California, Vapor Control

Portfolio Categories: Vapor Scrubbing.

Challenge
Reducing fugitive emissions from the top lid of an old oil recovery unit DAF Cell. Leak Detection And Repair (LDAR) is being taken very seriously in more and more areas of the country. This facility’s oil recovery cells were becoming aged and so the facility wanted to take proactive measures to ensure that no fugitive emissions would escape through the lids.                                         

Solution
Envent designed, fabricated , and installed a completely automated thermal oxidizer capable of reducing the pressure in each DAF cell. The thermal oxidizer can selectively draw from each cell to maintain a slight vacuum – ensuring that no fugitive emissions are released. 

Benefit
Satisfied the air district by building a safe, effective, and reliable solution. The system uses plan utilities to save cost on generator and supplemental fuel expenses. Additionally – the system is fully automated, allowing the thermal oxidizer to be run without continuous supervision.                                           

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