Vapor Control on Temporary Storage Tanks Requires Real Time Analysis

Vapor Control on Temporary Storage Tanks Requires Real Time Analysis

Portfolio Categories: Vapor Control.

Challenge

Envent Corporation was contracted to provide vapor control services for two temporary storage tanks located at a recovery and recycle area. The tanks contained rinse water from vacuum trucks and roll-off bins, which held low concentrations of VOCs. The variable nature of the vapors presented a challenge—both vapor flow rates and VOC concentrations fluctuated significantly, making standard monitoring schedules unsuitable.

While Envent typically provides once-daily monitoring followed by a taper to weekly reviews once vapor concentrations stabilize, this project required continuous assessment due to unpredictable changes at the inlet.

Solution

To address the variability, Envent’s engineering team conducted ongoing calculations to evaluate the composition and ppm concentrations of VOCs. Based on the adsorption capacity of carbon and SCAQMD permit limits, Envent selected and deployed the following:

  • Two EVAC 2000 vapor scrubber systems, each SCAQMD permitted and pre-loaded with 1,000 lbs of activated carbon

  • Two 500 BBL temporary storage tanks to contain the rinse water

The system was designed to remain flexible. When pollutant concentrations changed, Envent adjusted the carbon loading, or in some cases, switched to a different carbon type to maintain emission control efficiency. This level of adaptability ensured continued regulatory compliance even with fluctuating vapor characteristics.

Benefit

Envent’s expertise in industrial vapor scrubbers and VOC control allowed the customer to manage a highly variable waste stream while maintaining compliance with SCAQMD emission standards.

By customizing the system to match changing field conditions, Envent delivered a cost-effective, compliant, and reliable solution. This project reinforced our commitment to tailoring vapor control systems for even the most uncertain environments—ensuring our clients always receive the best available technology and performance.

 

Envent helps Louisiana Refinery stay Environmentally Compliant

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

Challenge

A major oil and gas refinery in Louisiana was fast approaching on a major turnaround where the coker flare and adjacent unit would need to be taken down for maintenance. The adjacent unit was home to the flare scrubber where all daily vents from multiple units, such as the Coker, Diesel Hydrotreater, Sulfur Plant, Sour Water Stripper, and Gasoline Hydrotreater, came from. Having this unit shut down along with the specially designed flare would mean that all vents would need to be routed to a backup flare, one that was ill-equipped to handle the “sour” vapor streams of the plant. The option to route the vents to their onsite amine scrubbers would cost the facility around $7 to $8 MM in production.

Solution

Envent’s technical team along with project engineers worked with the refinery to scope and design a scrubber system that would perform H2S and SO2 removal before vapors would be routed to their backup flare. Envent sized and built blowers that allowed the vent header to retain its day to day pressures while routing vapors from their flare header to Envent’s temporary scrubber system. The system was equipped with High-Pressure KO Drums, HP Stainless Steel Caustic Scrubbers, Automatic isolation valves, temperature, and pressure transmitters and sensors. All equipment was installed per strict MOCs guidelines and Class I Div II location requirements. Envent provided a fully-manned operation with two technicians around the clock for the entire duration of the 30 plus day outage.

Benefit

The customer was able to keep the operation of their site’s amine scrubbers and save upwards of $8,000,000 in production cost, all while continuing to operate their main units during a planned shutdown. Envent was able to keep the refinery environmentally compliant by ensuring that all vapors vented to their backup flare were below ~5ppm of H2S/SO2.

Northern California, Mobile Water Treatment – Multi Phase Extraction

Portfolio Categories: All, Case Studies, and Mobile Water Treatment.

Challenge 

Contaminated water at a Northern California Refinery where groundwater must be extracted before it enters the bay.  There is a series of groundwater wells and pumps that maintain hydraulic control of the area’s sub surface water system and prevent the contaminated water from reaching the Bay. The source of contamination was a Methyl tert-butyl ether (MTBE) tank with an underground transfer pipe that leaked. This leak was pretty substantial in size causing a fairly large underground plumb of MTBE. We have been onsite since 2008.

 

Solution

Multi-Phase Extraction utilizes a high vacuum blower to pull a mixture of both liquid and vapor from an existing ground well. The high vacuum extracts water and vapor until ground water level drop allowing a high vacuum to be pulled on the surrounding contaminated soil.  Extract a liquid/vapor mixture separate them then send the liquid to our existing water treatment system and destroy all hydrocarbons extracted to speed up the soil remediation process.  We provided the customer with a 450 SCFM Liquid Ring DVT blower and an EMTOS 2000.

 

Benefit

Envent’s engineered multi-phase extraction, water treatment and vapor abatement system continues to be successful at cost effectively removing and treating both the groundwater to NPDES standards and the vapor stream to BAAQMD and EPA standards.  The oil refinery is in full compliance and impact on the environment mitigated.

Envent performs Soil Vapor Extraction near Public School

Portfolio Categories: All.

 

Challenge

A customer was in need of a soil vapor extraction system for a project located within 2,000′ of a public school for a three month pilot project duration. The system was needed to scrub the following VOCs: BTEX, TCE and PCE. Upon successful completion of the pilot project, our customer could then determine the need for a permanent system. Given the close proximity of sensitive receptors (children), the customer had to be assured our system would perform.

Solution

Given Envent’s experience in Soil Vapor Extraction and already having a portable various locations air permit on-hand, we had the solution on the shelf ready to go. A fully self-contained SVE scrubber trailer was dispatched to the job site. This one trailer had everything needed to pull vapors from below ground, pass through lead/lag carbon vessels and vent to atmosphere through a 14′ vent stack. A chart recorder logged VOC concentration, and daily monitoring samples were drawn from sample ports at the inlet, midpoint and outlet of the scrubber. An on-board blower was throttled to provide the best flow rate, and power was provided by an electrical tie-in to existing job power pole.

Benefit

The benefit to the customer was the ability to test the equipment sizing and flow capabilities prior to spending capital on an unproven system. Envent’s system gave the customer the confidence they needed to move forward with the construction phase of their project. This project complied 100% with local regulations and the regional air permit. All emissions data logged during the project was presented to the customer in a project closure report.

Washington Refinery – Sulfur Loading Rack Vapor Control

Portfolio Categories: Odor Control, Vapor Control, and Vapor Scrubbing.

 

 

Challenge

A refinery sulfur recovery loading rack was giving off foul/hazardous odors to truck drivers and personnel located in immediate surrounding area of sulfur recovery unit (SRU) during truck loading events. Truck drivers inside the refinery were required to dawn SCBA’s and load trucks with truck dome hatches open. They had to visually validate fill levels during loading events to prevent overfilling. Envent was requested to quickly find a solution to eliminate foul/hazardous odors and maintain an automated/unmanned long term solution, keeping truck drivers and SRU personnel safe from high H2S vapors during truck loading.

Solution

Envent engineered an unmanned, automated vapor control solution tied into existing plant power. Envent system consisted of an interchangeable truck dome hatch with windows for truck drivers to verify loading events. A movable vapor line arm creating 500 CFM of vacuum was then steam traced and fit up to a skid mounted ESCRUB 1000-P (knocking out sulfur fines) followed by ESCRUB 1000-SS Re-Circulating Packed Column Scrubber filled with an H2S scrubbing liquid media (removing all H2S).

Benefits

Envent’s engineering department was able to custom design and build an unmanned vapor control solution alleviating refinery engineering manpower. Furthermore, Envent engineering streamlined a significant portion of an otherwise lengthy refinery MOC process by supplying system design specifications and drawings for Envent equipment (which is designed and fabricated in-house by Envent). Envent removed an ongoing odor control concern by creating a long term solution within weeks of design inception. Ultimately, Envent was able to eliminate H2S hazards all together; knocking inlet vapors from 1500ppm H2S to 0.0 ppm H2S.

Truck drivers, refinery operators and contractors are now working freely in the SRU without any odors or H2S hazards.

 

Vapor Control of Fuel Gas Recovery Line Provides Client Quickest Turnaround Ever

Portfolio Categories: Turnaround Services and Vapor Control.

 

Challenge

A client asked Envent to help them to do the vapor control on the fuel gas recovery line at their refinery during their hydrogen plant turnaround event. As the hydrogen plant was being taken offline, the refinery fuel gas consumption would decrease, causing an excess of fuel gas. The excess capacity of the fuel gas line that Envent needed to control was as high as 3 million standard cubic feet per day, while also maintaining compliance with Envent’s Alternative Monitoring Plan from the Environmental Protection Agency.

Solution

Extensive engineering efforts were involved to overcome the customer’s challenge. A pressure loss study for two parallel streams of high pressure fuel gas was conducted to size regulator systems. Project-specific upgrades were implemented on the thermal oxidizer control systems. Control and isolation valves were designed into the system during a project PHA to handle unforeseen process conditions. Specialty, auxiliary detonation arrestors were installed to mitigate additional hazards; analyzers were installed to monitor key process conditions.

Benefit

With this flexible, but thoroughly engineered solution, the fuel gas vapors were treated successfully without any environmental or safety incidents. Knowing that their fuel gas recovery system was in good hands, our customer completed their turnaround faster than it had ever been done before.

 

 

Pipeline Clearing + LPG Bullet Depressurization and Degas

Portfolio Categories: Degassing and Vapor Control.

Challenge

A customer in the Gulf Coast engaged Envent with the need to depressure and clear a pipeline running from its refinery to 3.5 miles South of refinery for an emergency repair and inspection. The customer also brought up the need to a depressurization and de-inventory for an LPG Bullet tank during the same time frame.

Solution

Envent, with efficient emergency response and state-of-the-art equipment was able to provide a cost effective solution that not only cleared the pipeline, but also de-pressurized and degassed the LPG bullet with the same crew and EMECS, one after another. This in turn helped our customer perform necessary maintenance and repairs to the pipeline as well as LPG Bullet tank.

Benefit

With Envent’s response time, it not only provided the depressure and degas service for the customer, but saved them time and money, cutting each job in half and performing a 2-in-1 service (1 mobilization, 1 demobilization). With the time that Envent saved them, they were able to perform additional maintenance to pipeline that might not have been available had we not responded.

 

Envent Provides Vapor Recovery System to Underground Toxic Cleanup

Portfolio Categories: Odor Control and Vapor Control.

Challenge 

A chemical manufacturing facility in the Southeastern US had a large underground cleanup of toxic chemicals that had been spreading underground for many years. They had a design for the tent enclosure that the heavy equipment would be working in but needed a vapor recovery system to make sure none of the hazardous vapors affected any of the workers in the area or the nearby town. The system had to keep contaminant levels below one part per billion to stay within specs.

Solution

Envent’s Engineering team were able to provide custom designed redundant 5,000cfm systems utilizing over 100,000lbs of carbon at one time to keep the job on schedule and within discharge limits to keep everyone safe. Envent also provided additional equipment to provide fresh air for the large excavators’ engines so the same contaminants didn’t destroy the expensive equipment and incur large repair bills. Envent also provided custom piping to duct out the high temp exhaust from the equipment. With turn key services, Envent also provided backup power for the whole site along with temporary large industrial Air Conditioners to keep the inside of the tent at a safe level for workers even with 100+ degree heat with high humidity in the middle of summer.

Benefit

Envent was able to provide a safe redundant turnkey system that helped our client get the job done and provide a safe area for the workers performing the work in Hot humid weather. Envent’s top level engineering and project team was able to adapt to multiple changes in scope on the project and get design done and equipment to the site in minimal time to minimize delays and keep the project moving forward. This project was completed with no violations from DTSC even with the very strict limits placed on outlet of the system.

 

Envent Engineers ensure Environmental Compliance

Portfolio Categories: All, GHG Emission Control, and Vapor Control.

Envent Engineers ensure Environmental Compliance During Tank Cleaning

 

Challenge

Envent provided vapor control on 5 temporary frac tanks during a tank cleaning. The source tank was emptied of a slop oil mixture. The product was going to be separated by a centrifuge into water, oil, and solid components. The temporary tanks in use accepted water/oil outputs and contained a heavy oil/sludge input mixture. The main technical challenge in this project was ensuring that the passive carbon system would not be spent at a faster pace than what was expected, and possibly result in compliance violations. The amount of product being pumped into the frac tanks would vary along the vapor control and could not be predicted. In addition to trying to comply with our emission limits, we had to be sure that all the system was the most cost and time effective solution.

Solution

Once the scope was outlined, calculations were performed to infer the amount of carbon needed based on the vapor pressure of the tank mixture. After we gather all the products data, we were able to design a carbon system according to the type of product in the tanks, the number of tanks, the pumps output, etc. Envent used a system of two EVAC 2000 (2,000 lbs carbon vessels), including a flame arrestor, interconnecting hoses, and tank fittings.

Benefit

SCAQMD permits are particularly complex for centrifuge operations and the compliance of centrifuge projects requires attention to detail. Envent engineers experience was valuable when laying out the equipment in the most efficient way so that in case of an equipment failure we would still comply with all the SCAQMD permit limits.

 

Envent helps to provide a solution to handle Liquid Ammonia

Portfolio Categories: Degassing, Odor Control, and Vapor Control.

Envent helps to provide a solution to handle Liquid Ammonia tank skid evacuation

Challenge 

A customer tasked Envent to help evacuate an Ammonia tank skid and the surrounding piping so that multiple valves in the system could be replaced safely. Envent would have to provide a solution to handle liquid ammonia, associated temperature issues, and chemical hazards.

Solution

Envent provided the customer with a High Pressure Regulator, a SS Knockout Vessel, and an EMECS 20 Thermal Oxidizer all connected by SS Hose. The customer system had an initial pressure of 200 psig which was reduced to a manageable pressure by the High Pressure Regulator. However, as pressure decreased, the temperature of the vapor stream would decrease as well, resulting in freezing of the liquid ammonia. To combat this issue, a constant heat source was applied to the SS Knockout Vessel, thereby preventing the ammonia from freezing and allowing it to vaporize sufficiently. The ammonia vapors were routed into the EMECS 20 Thermal Oxidizer where they were combusted with over 99.9% efficiency. Using the EMECS 20 onboard blower, Envent maintained a vacuum on the system so once ammonia levels reduced to nearly zero, the valves could be removed and replaced. The constant vacuum helped to prevent any release of ammonia vapor into the atmosphere, and eliminated worker exposure to the chemical. The process was continued until all valves were replaced safely.

Benefit

Using Envent’s solution allowed the customer to complete their maintenance work in a timely manner. Additionally, using Envent’s thermal oxidizer significantly reduced the amount of emissions that the customer would create. Therefore, the customer was able to proceed with standard operations immediately and cut costs significantly.

 

Degassing of an LNG-powered Freight Vessel

Portfolio Categories: Degassing and Vapor Control.

Envent Corporation | Marine Vapor Degassing

CHALLENGE 

A customer has tasked Envent to create a temporary system allowing for the degassing of an LNG-powered freight vessel while it docks in port to remove cargo. The solution would allow the customer to continue standard operations without delay, clear unwanted vapors from within the fuel tanks, and maintain compliance with Environmental Protection Agency regulations.

SOLUTION 

Envent supplied the customer with an EMECS 70, the industry leading mobile thermal oxidizer unit, as well as cryogenic-rated SS hose, a knockout drum, and a high-pressure regulator. The freighter has two 900 m3 LNG tanks each containing trace amounts of liquid LNG and pressurized vapors. The process stream was routed through the cryogenic-rated SS hose down to the knockout drum allowing for the vaporization of LNG to a gaseous state while simultaneously increasing its temperature from subzero to suitable levels. Fire water was run past the knockout drum in order to aid with the heat exchange. Vapors were 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 depressured.

BENEFIT 

Envent’s depressure 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.

 

Envent helps in overcoming local Environmental regulations

Portfolio Categories: Case Studies, Degassing, and Odor Control.

Odor Control Units from Envent Corporation for Pipelines, Refinery, Sewer, Industrial Tanks and emergency response

Challenge

A large Oil and Gas customer needed to perform much-needed maintenance on one of their Crude Oil tanks in the North East. The processes of degassing and cleaning crude tanks are relatively common throughout the industry; however, this project inherited some issues that first needed to be addressed. To start off: the crude oil contained a high level of H2S ( 1500ppm), the sulfur and entrained mercaptan made it so that the odors of this tank would be immediately detectable to any residents in the area. The composition of the crude was also very light, meaning that the tank would liberate vapor very quickly, this vapor could easily enter the atmosphere and dispense among the surrounding area. The risk for exposure to H2S to the neighboring residents would also be extremely critical. The tank was located in a small terminal, where it was surrounded by a residential subdivision to the south, a retirement community to the north, and a large community center to the east. The concern for public opinion in a region where Oil and Gas companies are not seen favorably was also important, this was made clear to them when their last maintenance event at the site was met with public complaints, and local camera crews in regards to the odors during the event. To worsen the situation: the local environmental department had limited the vapor control devices allowed to only one option: Carbon Adsorption.

Solution

Envent Corporation worked with our customer’s Engineers, and Compliance Specialists in order to develop a plan that not only met the needs of the site to be “Good neighbors” but also addressed their safety concerns while expediting the project to minimize the downtime for the tank. Envent developed a liquid/carbon scrubber system that was capable of adsorbing all of the VOCs that saturated the vapor space in the tank. The system was capable of a high volume flow of ~4,000 SCFM. This flow kept the tank seals and roof openings from reliving any vapors onto the atmosphere. Multiple monitoring devices were placed around the tank to ensure that no vapors were escaping around the tank or any processes. Liquid phase chemical media was used to safeguard the activated carbon, while a multi-port manifold was used to divert and manage flow to specific scrubber trains. A nitrogen suppression system was also engineered for the safety of the crew and integrity of the system. Lastly, Envent also prepared multiple support structures for media and chemical change-outs to ensure the system was designed so that no downtime would be had during the project.

Benefit

Envent’s solution kept the vapor space in the tank safe from the initial vapor space opening until the tank was deemed gas free and safe for entry. The system adsorbed well over 12,000 lbs of VOCs while maintaining a 100% DRE throughout the multiple scrubber trains. While the tank was estimated to reach a gas-free state in about 3 days, degassing was completed in just 26 hrs. This rapid completion of the degas allowed the customer to move-up scheduled work, saving them extra costs from the multiple contractors who were on standby. The project received no complaints from the neighbors, and no attention from the local media, which in this case; is very good news.

 

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