Sour Water Treatment Research Articles

Enhancing energy hub efficiency through advanced modelling and optimization techniques: A case study on micro-refinery output products and parking lot integration

A new model of energy carriers (micro-refinery output products) in the concept of an energy hub is presented. In addition, in the presented model, the effect of different models of parking lot in an energy hub is analyzed. In this study, the uncertainty of the number of electric vehicles was modeled using the Monte Carlo method, and then considering the same conditions, the uncertainty of the number of electric vehicles was calculated using the Probability-Possibility hybrid method. In addition, the study uses a scenario-based approach to address uncertainties related to multi-carrier energy demand and multi-carrier energy prices. In the present paper, ensuring water demand is of great importance, which is why the proposed energy hub structure of a sea desalination unit and sour water treatment that is extracted from the micro refinery output was analyzed. The optimization model presented in this paper for the energy hub is a complex integer linear programming (MILP) that is solved using a CPLEX solver in the GAMS environment. The results show that the use of the Probability-Possibility method resulted in an 8 % reduction in the final energy supply cost in the energy hub compared to the Monte Carlo method.

Development of AI-based process controller of sour water treatment unit using deep reinforcement learning

BackgroundDue to the variability in the feedstock conditions and the nonlinearity of the sour water stripping process, determining the optimal operating conditions for Sour Water Treatment Unit (SWTU) is a huge challenge. MethodsIn this study, we propose an AI-Based Process Controller (AIPC) for optimizing the SWTU, combining deep reinforcement learning (DRL) and expert knowledge. A surrogate model of an industrial SWTU digital twin was developed to serve as the environment for DRL. A reward function was designed and compared with others for evaluation. A method for seamless switching was devised to guarantee uninterrupted device operation by preventing any interference from the policy network. Significant FindingsIn contrast to the alternative control schemes, the AIPC not only demonstrates superior performance in mitigating overshooting and enhancing setpoint tracking precision but achieves a reduction in stripping steam usage. The proposed method has great potential in the field of real-time optimization.

Faulty scenarios in sour water treatment units: Simulation and AI-based diagnosis

Fault Detection and Diagnosis (FDD) is a Process System Engineering (PSE) area of great importance, especially with increased process automation. It is one of the chemical engineering fields considered promising to Artificial Intelligence (AI) application. FDD systems can be useful to supervise Sour Water Treatment Units (SWTU) behavior, as they are chemical processes that present operational difficulties when disturbances occur. SWTU remove contaminants from sour water (SW) streams generated through petroleum processing, consisting mainly of small amounts of H2S and NH3. They are considered one of the primary aqueous wastes of refineries and cannot be disposed of due to environmental regulations. However, no previous studies focused on the development of FDD systems for SWTU exist and works on its dynamics are scarce. Hence, the present work proposes to study the dynamic simulated behavior of an SWTU and develop an FDD system applying AI techniques with hyperparameters optimization. The simulation was performed in Aspen Plus Dynamics® and ran to create normal operation and six relevant faults, including occurrences in the process (e.g., inundation and fouling) and sensors. FDD was performed through data classification, and results were evaluated mainly by accuracy and confusion matrices. Even after variable reduction, FDD was satisfactory with over 87.50% accuracy in all AI techniques. RF and SVM with linear and Gaussian kernels presented the best results, with over 93% of accuracy in training and testing, and had the shortest computing times. The second column’s sump level proved to be the most relevant variable for fault identification.

Simulation and Heat Recovery from Sour Water Stripping Process Using Aspen Hysys

This research article presents a method for extracting heat from sour water process has been developed and depicted through aspen hysys. In the sour water treatment process the feed water is required to be preheated before entering the stripper and the water recovered from the bottom of the stripper possesses high temperature. In this article the water from the bottom of stripper is used to heat the incoming feed water. Two different aspen models were developed for this purpose. First one with a heater and the second one with a heat exchanger replacing the heater and using the heated water from the stripper as the heating media. The heating requirements of the feed water were met and a cost analysis revealed the second arrangement to be more economically feasible. In this way the heat generated within the system is utilized within the system. A further investigation of the separation operation has also been done by binary and ternary plots using Aspen Hysys and the results have been discussed.

Influence of operational parameters in sour water stripping process in effluents treatment

Sour water are process streams, with high concentrations of hydrogen sulfide (H2S) and ammonia (NH3), absorbed during the crude oil refining process. In order to comply with environmental legislation, and reducing costs, it is treated to remove contaminants, usually in separation columns. Despite stripping be widely found in industrial plants, including refineries, few studies have approached process optimal configurations, to application in different scenarios of sour water stripping. Therefore, this work aimed to verify the process configurations influence in non-phenolic sour water treatment of two typical compositions, and to improve the efficiency, assisted by a virtual plant, in ASPEN PLUS® software. RADFRAC module was adopted to simulate the stripping column with ELECNRTL thermodynamic model. The influence of operation conditions, as boilup ratio (BR), reflux ratio (RR), number of stages (NS), sour water input position (SI), sour water temperature (ST) and pressure (P), the composition itself, and use of steam or thermal load were studied. Results showed that, regardless of the use of steam or thermal load, for bottom stripped water, the increase in BR, NS, and ST promoted a decrease in NH3 and H2S recovery, while the decrease in RR, SI and P reduced them. Use of steam performed less recovery values than thermal load. Process efficiency not changed significantly with composition. Study findings show the optimized configurations in order to obtain a better efficiency process, for a one column system, generating water with low H2S and NH3 concentrations, which allow water reuse, or disposal in accordance with Brazilian legislation.

Assessment of a Sour Water Treatment Unit Using Process Simulation, Parametric Sensitivity, and Exergy Analysis.

In this work, a sour water treatment unit was evaluated combining exergetic analysis and parametric sensitivity analysis. Process simulation was performed using Aspen HYSYS 10.1 following real refinery configurations, and the results were validated with existing data. The parametric sensitivity was evaluated by varying the effect of process variables to identify an alternative case with the best technical performance. The exergy analysis was applied to both base and alternative cases. The outcomes were exergy efficiency by stages, global exergy efficiency, total irreversibilities, and exergy by industrial services. A comparison of both cases was performed to identify opportunities for improvement in real sour water treatment. Results revealed that the overall exergy efficiency for the base case was 44.28%. After improving the technical performance, the overall exergy efficiency decreased to 36.12%; the latter indicated higher irreversibilities due to the increase in the use of industrial services. This finding suggested that those process improvements may affect the performance of this refinery unit from an exergetic point of view.

Reverse osmosis performance on stripped phenolic sour water treatment – A study on the effect of oil and grease and osmotic pressure

Technologies for water recycling within oil refineries have been gaining interest at an extensive rate due to the large volume of wastewater generated, high dependency of water and the progressive scarcity of this valuable resource. Phenols are part of a specific class of organic pollutants that have been contributing to a low-quality effluent in oil refineries due to their hazardous nature and strict environmental legislation associated. The reuse of stripped sour water within refineries is often blocked due to its rich phenolic content.This study evaluates the retention of phenols in refinery wastewater through reverse osmosis (RO) at its major source of emission, for water reclamation. The RO membrane selected exhibited rejections of up to 98% of phenols and 99% of both chemical oxygen demand (COD) and total organic carbon (TOC). Permeate quality remained intact despite flux decline caused by phenolic and hydrocarbon adsorption when the oil content, in the feed, reached 771 ppm. The effluent's low conductivity due to lack of salts led to minor osmotic pressure differences (less than 2.5 bar at a volume concentration factor of 3), therefore, showing appealing performances of reverse osmosis filtration. Characterization of all permeates obtained from cross-flow filtration experiments showed COD levels in line with water reuse quality standards for make-up water in cooling processes.

The effect of Hydrogen sulfide oxidation with ultraviolet light and aeration on sour water treatment via membrane contactors

During natural gas extraction and production, hydrogen sulfide (H2S) is often brought to the surface. In some cases, H2S could be present in water streams, referred to as “sour water”, treatment of that sour water is required before disposal or reuse. Sour water can be treated in a variety of ways including conventional stripping and chemical scavenging. Hydrophobic membrane contactors are an alternative technology for the treatment of sour water. Due to the hydrophobic nature of the membrane, dissolved gases, including H2S, can pass through while water is retained on the feed side. The sodium hydroxide receiving solution acts as a trap that captures the H2S. Once the H2S is trapped, ultraviolet (UV) light and oxygen can be applied to oxidize the sulfide to non-hazardous forms of sulfur allowing more disposal options for the receiving solution. This research focused on evaluating the feasibility and performance of a hybrid process combining a membrane contactor and a sulfide oxidation step through UV light and aeration.Oxidation experiments showed that UV light alone can oxidize the sulfide to disulfide. On the other hand, UV combined with oxygen, via aeration, was capable of further oxidizing sulfide to sulfate and thiosulfate; the two main sulfur species present in the treated water based on mass balance calculations. Both oxidation methods (UV with and without aeration) were found to follow a first order reaction rate, that of UV alone was 0.015 min−1, and when combined with aeration the rate was more than two times higher (0.035 min−1). The proposed hybrid technology can be applied in both upstream and downstream operations as a standalone process for the treatment of sour produced and process water.

Sourwater treatment by fenton process and its effect on phytotoxicity with <i>Lactuca sativa

In this work, degradation of stripped sourwater by Fenton´s oxidation process was investigated by a central composite design and response surface methodology. The effects of initial concentrations of H2O2 and Fe2+ on the total phenols degradation was studied in a batch reactor. The optimum total phenols degradation was 92% achieved within an H2O2 concentration of 4.4 g L-1 and iron concentration of 162 mg L-1. The mathematical kinetic model adequately represented the experimental results. The results indicated that the Fenton oxidation rate (1/m) and removal efficiency (1/b) were more dependent on iron concentration than H2O2 concentration. After the Fenton process, the sourwater presented a seed germination rate (L. sativa) above 80%, indicating reduced phytotoxicity of the treated effluent. It was also observed that the H2O2 concentration significantly affected the inhibition concentration (IC50).

Systems engineering based advanced optimization for sustainable water management in refineries

Refineries are increasingly compelled to play an imperative role in achieving sustainable management of water as mandated by sustainable development goals (SDGs). Existing optimization models lack the ability to addresses this challenge of obtaining optimal refinery water network configuration for problems of industrial scale due to difficulty in application of complex solution algorithms of mixed integer non-linear problem (MINLP) formulations to large dimensions. Therefore, the optimization formulation in this work exploits process engineering derived constraints to build an integrated superstructure, which results in a simplified non-linear problem (NLP), and thus reduces computational complexity. Further, to substantially minimize fresh water consumption, the proposed model incorporates novel features of a modern refinery complex viz. distributed effluent treatment plant based on total dissolved solids (TDS) levels in waste water, segregation of sour water treatment based on phenolics content in condensate stream, and minimizing cooling tower blowdown rates by optimizing the cycles of concentration in cooling tower operation. The formulation is demonstrated for optimal water routing and economic benefits of the proposed approach through a representative case study of a real refinery complex. Towards the goal of zero liquid discharge, an efficient new scheme of recycling treated water to the boiler feed water system and cooling tower make up water requirements in optimal ratios, has been suggested from the results of the proposed model. Sensitivity of water reallocation in optimal refinery water network with respect to crude quality and desalter performance is also presented through application of proposed optimization framework in the case studies.

COMPARAÇÃO ENTRE OS TRATAMENTOS POR ESGOTAMENTO E MEMBRANA PARA A ÁGUA ÁCIDA PROVENIENTE DE REFINARIA DE PETRÓLEO

As refinarias de petróleo apresentam uma grande importância no mercado mundial e tem como função realizar o refino de óleo cru extraído do solo, transformando-o em diversos subprodutos derivados tais como gasolina, querosene, GLP e óleo diesel. Para certas etapas do procedimento de refino, a água é um importante recurso na purificação desses produtos. No entanto, após sua utilização, a água contaminada por resíduos tóxicos, chamada de “água ácida” numa tradução livre do inglês sour water, necessita de tratamento para descarte no meio ambiente ou para ser reutilizada no processo de refino. Para evitar riscos ambientais e industriais relacionados à sua contaminação, as refinarias buscam solucionar esse problema, que é analisado de várias maneiras. Esse trabalho tem como objetivo avaliar e comparar duas alternativas de tratamento da água ácida: tratamento por esgotamento a vapor e separação por osmose reversa. Foi utilizado o software ASPEN PLUSÒ para modelagem e análise dos processos. A modelagem incluiu a caracterização da água ácida e a escolha do modelo termodinâmico adequado à representação do equilíbrio de fases e demais propriedades físico-químicas necessárias. Os resultados confirmam que o processo de tratamento da água ácida por esgotamento é o mais adequado.Petroleum refineries have a large importance in world business. Their main function is to refine crude oil, converting it to several products such as gasoline, diesel oil, LPG and fuel oil. In refinery operations, water is an important source of purification of the crude oil. However, after being used the water becomes contaminated by toxic residues that are dangerous to the environment if disposed incorrectly. Another option is purifying the water so that can be used again in other refining operation. For this alternative the contaminated water is referred as ‘’sour water’’. To avoid environmental and industrial risks related to its use, the refineries seek for a solution to their problem by applying the effluent treatment. In this scenario, the industries use modeling software to evaluate the benefit to cost ratio for the treatment of sour water. Lastly, this work has the objective of evaluating and comparing alternative processes such as stripping and membrane treatment, by formulating mathematical models that are going to be simulated by software used by Chemical Engineers, called ASPEN PLUSÒ , and an analysis of its preliminary cost.

Application of membrane contactors to remove hydrogen sulfide from sour water

Wastewater containing hydrogen sulfide (H2S), also known as sour water, is a byproduct stream generated during oil & gas (O&G) production. Because H2S is both toxic and corrosive, treatment to remove it is generally practiced, either by chemical treatment or stripping. Within the O&G industry, sour water strippers are generally used, especially when there is a need for recycle/reuse or for safe handling. However, those treatment processes have limitations in terms of chemical consumption or high capital cost (due to expensive materials of construction). Commercially available membrane contactors are a potential alternative technology for sour water treatment with advantages such as low capital cost, modular & compact design and thus, portability. The hydrophobic character of the membrane allows H2S gas from the sour water to permeate through, while preventing the passage of water. When applied in this novel approach, the H2S passing through the membrane dissolves into a receiving solution containing a chemical, e.g. amines or sodium hydroxide, which immediately converts the H2S to a non-hazardous form thereby maximizing the concentration gradient across the membrane. Process performance has been evaluated by coupling experimental data with mass transfer equations, using the overall mass transfer coefficient as the process performance indicator. Experiments showed a mass transfer coefficient of 0.243cm/min for both gas field sour process water and synthetic solutions, indicating no immediate membrane fouling. This process could be implemented in gas processing facilities or refineries with an amine regeneration unit as a side stream of the amine could be used as the receiving solution. It also has potential as a “fit-for-purpose” solution for groundwater treatment and other niche applications.

An exergy-based approach to determine production cost and CO2 allocation in refineries

In view of the continuous yet finite exergy supply to Earth, the determination exergy cost together with CO2 emission for fuel production is essential to the environmental evaluation of most processes. A petroleum refinery comprising atmospheric and vacuum distillation, delayed coking, fluidized catalytic cracking, hydrotreating, hydrogen generation, as well as residue/waste treatment units, such as sulphur recovery and sour water treatment, was analysed. Although high indexes of exergy conservation were observed for process units (>97%), the total exergy destroyed in the refinery was almost 800 MW. The calculation of the unit exergy cost and unit CO2 cost for produced fuels were performed by solving the set of linear equations used to describe the exergy cost formation for these fuels. The unit exergy costs found for diesel, gasoil, gasoline and hydrotreated diesel were 1.026 MJ/MJ, 1.028 MJ/MJ, 1.049 MJ/MJ and 1.10 MJ/MJ, respectively, while the unit CO2 costs for these fuels were 1.49gCO2/MJ, 1.20gCO2/MJ, 4.86gCO2/MJ, 6.34gCO2/MJ, respectively, reflecting the processing level and its efficiency as well as the C/H ratio of the burnt fuels.

Stripped sour water treatment by advanced oxidation processes

This study assessed the application of photolysis (UV), peroxidation (H2O2), peroxidation combined with ultraviolet light (UV/H2O2), Fenton’s reagent (H2O2/Fe(II)) and photo-Fenton (H2O2/Fe(II)/UV) processes in the treatment of stripped sour water from the Petrobras Replan Oil Refinery in Paulinia City, Sao Paulo State, Brazil. To evaluate the efficiency of the process, the concentration of dissolved organic carbon (DOC) was monitored throughout the reaction period. Among the evaluated processes, peroxidation combined by ultraviolet radiation showed the best potential for its application in the stripped sour water treatment.

Petroleum Refinery Stripped Sour Water Treatment Using the Activated Sludge Process

A pilot study was performed over 91 days to determine if the activated sludge process could treat a segregated stripped sour water (SSW) stream from a petroleum refinery. The study was performed in two periods. The first period was terminated after 19 days, as a result of excessive sludge bulking. The elimination of sludge bulking during the 70-day second period is attributed to operational changes, which included aerating the influent to oxidize reduced sulfur, adjusting the influent pH, and adding micronutrients to satisfy biological requirements. The pilot plant provided a chemical oxygen demand (COD) removal of up to 93%. Nitrification was achieved, with effluent ammonia values < 1 mg-N/L. These results indicate that direct treatment of SSW with the activated sludge process is possible and has direct application to full-scale petroleum refinery wastewater plant upgrades.

Compliance strategy for cyanides in petroleum refinery wastewater: Part 1—source characterization and treatment

AbstractA small (&lt; 8,000 m3/day, &lt; 50,000 bbl/day) petroleum refinery was having difficulty in complying with the 200 μg/L total cyanide limit in its NPDES permit. In addition, extensive cyanide corrosion was found during a turnaround of the fluid catalytic cracking unit (FCCU). Finally, the refinery was facing a NPDES permit renewal, in which the new total cyanide limit was expected to be 1.0 μg/L, the water quality standard for marine waters. The refinery, therefore, had both environmental and economic incentives for reducing cyanide in its FCCU process wastewater. The refinery undertook a multi‐faceted approach to its cyanide problem, including consideration of source treatment, stripped sour water treatment, end‐of‐pipe treatment optimization, and discharge permit modification. This paper addresses the source characterization and treatment activities that were conducted as a part of the strategy.Although the generation of cyanide in the FCC process is well documented, quantification of cyanides has historically been difficult due to analytical interferences from the high levels of sulfides in condensate streams from the unit. Measurements of cyanide by traditional analytical methods can be in error by orders of magnitude, and proper implementation of control technologies can be a guessing game. As a result, effective control techniques such as polysulfide injection are often avoided because of potential process upset.Modified analytical techniques for cyanide (both free and total) and thiocyanate in refinery sour water and hydrocarbon liquids were developed. Water and hydrocarbon samples from the FCCU product distillation and gas compression systems were analyzed with these techniques, and a cyanide mass balance was developed. From the results, the following conclusions were drawn: With certain process configurations, cyanides can spread far beyond the immediate condensate streams. The amount of cyanide generated in an FCCU may be higher than normally anticipated. Simple modifications to the existing system have the potential to substantially reduce cyanides, especially iron‐complexed cyanides. Source treatment with polysulfide can be optimized with these improved analytical techniques. Polysulfide treatment at non‐traditional, less risky locations may be adequate for meeting effluent discharge requirements. The degree of treatment required will also depend on final NPDES permit limitations. Negotiation of favorable limits can substantially reduce treatment needs. Follow‐up studies to further optimize cyanide control are planned.

Oxidation of hydrogen sulfide by an enrichment from sour water coproduced with petroleum

We have previously demonstrated that the chemoautotroph and facultative anaerobeThiobacillus denitrificans may be readily cultured aerobically or anoxically in batch and continuous reactors on hydrogen sulfide under sulfide-limiting conditions. A sulfide-tolerant strain ofT. denitrificans (strain F) was isolated by enrichment and recently used in a successful field test of a microbial process for the treatment of sour water coproduced with petroleum at an Amoco Production Co. site in Wyoming. Prior to the initiation of this field test, it was determined that the sour water at this site contained low concentrations of indigenous autotrophs, which could grow on thiosulfate as an energy source. Samples of this sour water have now been used to produce an enrichment culture for sulfide oxidizers. This enrichment has been characterized with respect to hydrogen sulfide oxidation, response to oxygen, pH and temperature optima, and sulfide tolerance. The enrichment was shown to be strictly aerobic and to grow on sulfide as an energy source with complete oxidation of sulfide to sulfate. The enrichment has a tolerance of sulfide comparable to that ofT. denitrificans strain F. However, the enrichment has a higher optimum temperature (35°C) than strain F and was shown to oxidize sulfides over a much broader range of pH values (3.5–10).

A Field Demonstration of Sour Produced-Water Remediation by Microbial Treatment

Summary The potential for detoxification and deodorization of sour produced waters by microbial treatment was evaluated under field conditions. A sulfide-tolerant strain of the chemautotroph and facultative anaerobe Thiobacillus denitrificans was introduced into an oil-skimming pit of the lease automatic custody transfer (LACT) Unit 10 at the Salt Creek field in Wyoming. Field produced water enters this pit from the oil/water separation treatment train at an average flow rate of 5,000 B/D with a potential maximum of 98,000 B/D. Water conditions at the pit inlet are 4,800 mg/L total dissolved solids (TDS), 100 mg/L sulfide, pH 7.8, and 107°F. An aqueous solution of ammonium nitrate and diphosphorous pentoxide was added to this water to provide required nutrients for the bacteria. The first 20% of the pit was aerated to a maximum depth of 5 ft [1.5 m] to facilitate the aerobic oxidation of sulfide. No provisions for pH control or biomass recovery and recycle were made. Pilot operations were initiated in Oct. 1992 with the inoculation of the 19,000-bbl pit with 40 lbm of dry-weight biomass. After a brief acclimation period, a nearly constant mass flux of 175 lbm/D sulfide was established to the pit. Bio-oxidation of sulfide to elemental sulfur and sulfate was immediate and complete. Subsequent pilot operations focused on process optimization and process sensitivity to system upsets. The process appeared most sensitive to large variations in sulfide loading owing to maximum water discharge events. However, recoveries from such events could be accomplished within hours. This paper details all pertinent aspects of pilot operation, performance, and economics. From this evidence, the oxidation of inorganic sulfides by T. denitrificans appears to represent a viable concept for the treatment of sour water coproduced with oil and gas.

Microbial treatment of a synthetic sour brine

The ability of the chemoautotroph and facultative anaerobeThiobacillus denitrificans to deodorize and detoxify an oil-field-produced water containing sulphides was evaluated under simulated field conditions. A sulphide-tolerant strain ofT. denitrificans was used to remove inorganic sulphide from a synthetic sour brine containing 4000 mg L−1 total dissolved solids (TDS) and 100 mg L−1 sulphide. The sour brine was treated continuously in a rectangular plugflow reactor which approximated the scaled dimensions of an existing field detention pond. The head space of the reactor was purged with N2 in order to capture H2S off-gases in a zinc acetate trap. Brine was fed to the reactor continuously for 90 days at rates corresponding to residence times of 0.17–6 days. Temperature and pH ranged from 22 to 40.5°C and 7.5 to 8.8, respectively. The start-up biomass concentration was approximately 100 mg L−1 (by dry weight). No. additionalT. denitrificans biomass was added to the reactor after start-up. At residence times of 0.3 days and greater inorganic sulphide was undetectable in the effuent. No H2S was detected in the outlet gas or the zinc acetate trap. Approximately 80% of the sulphide feed was oxidized to sulphate and removed from the reactor in the liquid effluent. The remainder was partially oxidized to elemental sulphur which was retained in the reactor. It is suggested that oxidation of inorganic sulphides byT. denitrificans represents a viable process concept for the treatment of sour water co-produced with oil and gas.

4880542 Biofilter for the treatment of sour water: Kerry L Sublette assigned to Combustion Engineering Inc

4880542 Biofilter for the treatment of sour water: Kerry L Sublette assigned to Combustion Engineering Inc