Mastering Amine unit Issues 8 Scenarios Where SRE Can Assist

Amine plants play a crucial role in gas sweetening, but they can face numerous operational challenges. Sulfur Recovery Engineering (SRE) offers specialized services to troubleshoot and resolve these issues, ensuring optimal performance and reliability. Here’s a brief description of each problem and how SRE addresses it:

1-Foaming

• Problem: Heavy hydrocarbons and contaminants in the inlet feed cause foaming in absorbers, leading to reduced efficiency and potential operational disruptions.

• Solution: SRE utilizes advanced Gas Chromatography (GC) technology for rapid identification of contaminants, along with onsite foam testing and evaluation of anti-foam agents to mitigate foaming issues effectively.

2-Corrosion

• Problem: Corrosive environments within the amine plant can degrade equipment integrity, leading to increased maintenance costs and safety risks.

• Solution: SRE quickly identifies corrosion potential areas through simulation, reviews and refines monitoring programs, and helps minimize corrosion through an online operations and maintenance (O&M) monitoring program.

3-Off-Spec Gas / LPG

• Problem: Off-spec gas or LPG indicates deviations from desired product specifications, impacting product quality and compliance.

• Solution: SRE conducts rapid onsite testing to diagnose issues, identifies trace sulfur components, and achieves 99% closure of the sulfur balance, ensuring compliance with product specifications.

4-Fouling

• Problem: Fouling in amine plants results from contaminants and particulates accumulating in key components, reducing operational efficiency.

• Solution: SRE reviews and optimizes filtration programs to prevent fouling, ensuring smooth operation and minimizing maintenance downtime.

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5-Sulfur Plant Feed Quality

• Problem: Inaccurate sulfur component levels and impurities in the regenerator overhead impact the efficiency of sulfur recovery processes.

• Solution: SRE performs onsite analytical testing to accurately measure sulfur components, identifies mercaptans breakdown, speciates BTEX compounds, and quantifies hydrogen cyanide (HCN) concentrations. We quickly optimize the acid gas circuit to improve overall efficiency and reduce corrosive issues.

6-Hydrocarbon Entrainment

• Problem: Ineffective separation equipment allows hydrocarbons to enter the process stream, reducing the purity and efficiency of amine treatment.

• Solution: SRE reviews and enhances the performance of inlet separation equipment, quantifying hydrocarbon levels in the process stream to mitigate entrainment issues.

7-Inefficient Energy Usage / High Carbon Intensity

• Problem: Excessive energy consumption and high carbon intensity increase operational costs and environmental impact.

• Solution: SRE optimizes energy usage through circulation rate adjustments and reboiler duty fine-tuning, recommends alternative amines with lower energy requirements, and assists in transitioning from steam to electric drives for enhanced efficiency.

8-Root Cause Analysis of Common Alarms

• Problem: Common alarms such as pressure differentials, analyzer errors, and pH fluctuations indicate underlying operational issues affecting plant reliability.

• Solution: SRE conducts detailed root cause analysis on absorber pressure differential (delta P), H2S and total sulfur analyzer errors, fuel gas H2S analyzer errors, sulfur plant tail gas analyzer (ADA) erratic behavior, quench pH, quench cooler fouling, and hydrogen analyzer plugging. Our expert analysis identifies operational inefficiencies and implements targeted solutions to improve overall plant reliability and safety.

SRE’s specialized expertise and innovative solutions address the complex challenges faced by amine plants, ensuring efficient operation, regulatory compliance, and enhanced performance. By partnering with SRE, clients benefit from reduced downtime, lower operational costs, and optimized plant reliability in their gas sweetening operations.

Discover how SRE’s specialized services can optimize your plant’s performance and ensure smooth operations

Hydrocarbon Present in Amine Solvent Downstream of Absorber

Problem Definition

A South American Refinery Client requested assistance tackling the problem of hydrocarbon being present in their amine solvent (rich amine). The client reported an incidence of hydrocarbon in their acid gas stream going to SRU. They are looking into putting a flash tank in service for the amine circuit and require SRE’s analysis to determine prime location, operation guidelines, and instrumentation required. There was an existing flash tank and was put out of service long ago, the tank was designed as a charge drum for amine system. P&ID of the amine circuit was provided (flash tank situated after the lean-rich amine heat exchanger) along with their current option.

SRE’s Response

Within a couple of days of receiving the request, SRE reviewed the P&ID and information provided by the client to present the recommendations. Flash drum should be installed after the absorber, and before the lean-rich amine heat-exchanger, to ensure Hydrocarbon is condensed and a significant amount of H₂S is NOT flashed. As per industry practice, absorbers operating below 10 bar usually do not require a flash drum. It was advised to the client to further investigate the event of hydrocarbon carryover to ensure there is no permanent damage to the amine circuit/equipment.

A write-up was sent to the client explaining where the flash drum should be installed and what the limitations will be. In addition, operation guidelines and instrumentation requirements were also presented to the client. For the short term, the client was advised to ensure that the amine inlet separator is functioning well, and that extra precautions are taken to stop hydrocarbon from entering the amine circuit.

RESULTS

The client was fully onboarded with SRE’s recommendations. They will strive to ensure that the flash drum will be installed upstream of lean-rich amine heat-exchanger and that proper instrumentation will be used. Operation guidelines have been provided to the client and will be further refined as the need arises.

SRE continues to provide support to this client as they are in the process of the modifications.

Solids Contamination

Problem Definition

European Refinery Client requested assistance with solids contamination in their DEA system. Corrosion issues in the regenerator bottom section and reboiler were reported. Amine analysis results were sent to SRE for review.

SRE’s Response – Solids contamination

Within one hour of receiving the request, SRE provided review of DEA analysis results and reported to the client that Heat Stable Amine Salt (HSAS) levels were considerably higher than maximum guideline level of 2 weight percent and were the probable cause of corrosion in the regenerator and reboiler.

The contamination in the system was the result of high corrosion rates found in the unit. A report on HSAS management was sent to the client. Additional guidance was provided to the client on short-term mitigation of HSAS using neutralization to immediately reduce the corrosion problem.

RESULTS

Using SRE’s guidelines, the client was able to reduce HSAS to an acceptable level. Solids contamination and corrosion rates were reduced.

SRE continues to provide assistance to this client to maintain the unit within guidelines for HSAS, solids and corrosion.

Troubleshooting SRU Feed Streams

“The SRU is only as good as what it receives in terms of amine acid gas and SWS acid gas”.

When evaluating the performance of an SRU, the first things to check are the feed stream quality and consistency. Since the SRU is only as good as what it receives, there are many potential areas for troubleshooting with regards to upsets with the feed stream units. All SRUs have an Amine Acid Gas feed stream, and many refineries have an additional Sour Water Stripper Acid Gas feed stream. The first indication that there maybe an issue with your feed streams is swings within your air demand signal. Large and uncontrollable swings in the combustion air demand signal occur due to fluctuations in the acid gas feed stream compositions and flow rates. Typically, when these fluctuate by more than 10%, the Air Demand Signal will fall outside of the optimal range and result in an immediate loss in recovery efficiency.

While plant swings can be unpredictable, they can be prepared for, new gas streams should be introduced slowly for a smoother transition. This can, for example, give the ADA time to adjust to the changing H2S content in the feed stream. Plant upsets can never be fully eliminated, so the SRU instrumentation must be regularly calibrated in order to be prepared for feed stream swings. Full performance testing of the upstream amine and SWS units is the best way to optimize performance and minimize swings in the feed stream compositions and flows.

Another common issue with SRU feed streams is when they have high hydrocarbon contents. Hydrocarbons require much more oxygen to oxidize in the reaction furnace, which throws off the air demand. Also, more hydrocarbons means more CS2 production, which will hurt the recovery efficiency if it isn’t hydrolyzed. If sufficient amounts of hydrocarbon make it into the converters, catalyst poisoning will occur and deactivate the catalyst.

Excessive accumulation of hydrocarbons in the feed streams can be due to:

Over circulation of amine, or amine temperatures falling below inlet gas temperatures, which results in HC condensation.

Insufficient flash tank residence time or skimming operation can also increase hydrocarbons in the amine or SWS acid gas. The same goes for the reflux drum.

Sometimes the Reflux Drum purge rate is too low, or sometimes the pump does not start, resulting in LPG carryover to the RF.

High levels of other contaminants can be problematic as well; BTEX, mercaptans, and methanol are all catalyst poisoning compounds that should be kept below threshold levels in order to ensure their full destruction in the reaction furnace. High CO2 contents will increase COS production and reduce efficiency if not fully hydrolyzed in the first converter.

The best way to minimize contaminants in the feed streams is to perform regular maintenance, testing, and optimization of the amine and sour water units.

The Benefits of Baseline SRU Evaluation

The typical lifecycle of a new unit is to go from design basis to simulations and data sheets and then from construction and commissioning to startup.  In the case of the Sulfur Recovery Unit (SRU), an additional step may be taken after startup in the Performance Guarantee of the unit where the Operating Company ensures the Licensor has designed and built a unit which meets the BoD.  Most of the time, though, Operators choose to forego the Performance Guarantee (budget, timing, incapable of meeting testing conditions, etc.).  Beyond the money-back aspect, what Operators are foregoing is the crucial sample set illustrating how the unit truly performs: an operating baseline.
Real analytical results are better than a simulated material balance.

Long after the unit is operational and just about when problems start to arise, recently SRE was brought in by an SRU Operator to determine the problems with their SRU.  As we’ve mentioned in our webinars, SRE starts any troubleshooting with analytical results of the unit’s current performance.  However, this snapshot in time is meaningless without something to which to compare it.  Once the current performance was determined and the BTEX breakthrough was obvious, we asked “has the unit always been like this?”  And that’s when the Operator will bring out the material balance in the SRU’s As Built drawings – we’re now trying to compare apples with oranges – and better yet, the simulation never took into consideration any aromatics in the whole design.

Although troubleshooting exercises can be solved without reference data, having something to compare to always helps.  Solving a problem fast means less downtime and more production.  Even better is data on a regular basis.  Trends can provide leading indicators to potential problems and to future catastrophes, saving big money down the road.

Having a baseline set of analytical results, benchmarks the performance of the SRU.  It’s an invaluable reference which will be far more accurate than the material balance provided by the Licensor.  Further, if you’re lucky, the test results will show areas for improvements or at the least, confirm that your unit is healthy.