Gasoline Vapor Recovery Research Articles

Tailor‐made iron‐organic molecular cage embedded polydimethylsiloxane membranes via emulsion casting technique for efficient VOCs removal

AbstractUrgent needs for the removal of volatile organic compounds (VOCs) from gas streams has stimulated a vigorous research for high‐performance separation membranes. Herein, porous iron‐organic molecular cage (Fe‐cage) embedded polydimethylsiloxane (PDMS) mixed miatrix membranes (MMMs) were fabricated through emulsion casting method for efficient VOCs removal. The membrane separation performance was systematically investigated by separating VOC/N2 gas mixtures under various operating conditions (e.g., feed concentration, operating temperature) using n‐hexane, n‐heptane, and cyclohexane as model organic vapors. It was found that the resultant membranes demonstrated homogeneous Fe‐cage dispersion and intimate interfacial adhesion. With the increase of the Fe‐cage loading, the MMMs demonstrated obviously improved permselectivity for the separation of n‐hexane/N2 and n‐heptane/N2. The MMM containing 4 wt% Fe‐cage showed a n‐heptane permeability of 1657 × 10−8 mol μm m−2 s−1 Pa−1 and a n‐heptane/N2 selectivity of 145 at 25°C when the feed concentration is 4.3 mol%. These values were 231% and 158% of those for the pristine PDMS membrane, respectively. Furthermore, the VOC permeability and VOC/N2 selectivity of the membranes increased with decreasing operating temperature or increasing feed concentration. Because of its excellent mixed‐gas VOC/N2 permselectivity, the Fe‐cage embedded PDMS membrane could find use in petrochemical applications such as gasoline vapor recovery.

A novel design of cold energy cascade utilization with advanced peak-shaving strategy integrated liquid air energy storage

For the sake of alleviating the pressure of energy and environment, compressed natural gas vehicle has become an important development direction of the automobile industry in the world with its advantages of low cost and restraining greenhouse effect. However, the operation of liquid-compressed natural gas station will inevitably produce boil off gas and gasoline vapor, which will cause great pollution to the environment if discharged into the atmosphere. Furthermore, in the face of increasing number of liquid-compressed natural gas stations, how to efficiently recover the cold energy released in the process of liquid natural gas regasification is a huge challenge. In this paper, a novel design integrating boil off gas and gasoline vapor recovery, liquid air energy storage and parallel Rankine cycle is proposed to recover cold energy of LNG in different temperature ranges for liquid-compressed natural gas station. The optimal ratio of binary mixtures are selected by genetic algorithm for parallel Rankine cycle, and the result shows that compared with pure working fluid, the total net power output of binary mixtures are increased by 6.62% to 3028.01 kW. Besides, an advanced peak-shaving strategy is proposed to satisfy the electricity demand of users at different time periods. The result of economic analysis exhibits that the payback period of the system is 5.24 years. This novel design not only provides a new idea for the recovery of boil off gas and gasoline vapor, but also complements the blank in the filed of cold energy utilization of liquid-compressed natural gas station.

Machine learning approach to improve vapor recovery: Prediction and frequency converter with a new vapor recovery system

In practice, the volatile organic compounds (VOCs) pollution can exist when refueling due to the properties of the gasoline, low viscosity and high saturated-vapor pressure. A new gasoline vapor recovery system involving frequency conversion technology and machine learning is developed to cope with this problem. In the proposed system, firstly, the pumping capacity of the vacuum pump is evaluated, and test shows an almost linear relationship between suction volume and frequency. Then, the Multi-Layer Perception (MLP) neural network and the support vector regression (SVR) are employed to predict the gas-liquid ratio, and the numerical examples are presented to prove the high prediction accuracy of the MLP and SVR, respectively, where the MLP neural network has better generalization ability. Finally, compared with the two gasoline vapor recovery systems based on the 1: 1 fixed control model and the PID control model, respectively, the gasoline vapor recovery efficiency is improved significantly by the new gasoline vapor recovery system.

Optimization of energy-exergy efficiencies of an advanced cold energy utilization system in liquefied natural gas filling station

In this study, a novel cold energy utilization configuration of liquefied natural gas is presented for liquefied-compressed natural gas filling station by combining gasoline vapor recovery, power generation and blood freeze-drying. Aspen Plus software is employed for modeling, and the simulation results are compared with the published literature to verify the accuracy. Based on the analysis of gasoline vapor condensation temperature, when the condensation temperature is −30.2 °C, −59.8 °C and −114 °C in turn, the recovery efficiency can be guaranteed more than 95%, and the energy consumption is the most competitive. Subsequently, the influence of evaporator and turbine outlet pressure on the performance of the power generation subsystem is studied by thermodynamic analysis. Then, the genetic algorithm is applied to determine the optimal binary mixtures, and the optimization results exhibit that the maximum net power output and exergy efficiency reach 154.6 kW and 28.96%, respectively. Meanwhile, the equivalent output power of gasoline vapor recovery subsystem and blood freeze-drying subsystem are 139.14 kW and 305.53 kW, respectively. The economic analysis demonstrates that the design payback period is only 6.3 years, providing a new idea for reasonable utilization of cold energy in liquefied-compressed natural gas station.

Vapor Recovery Unit of Gasoline from the Tanks of Filling Stations with Gas-Dynamic Cooling

This study presents a gasoline vapor recovery unit of a gas station, which is based on a vortex tube and a shell-and-tube heat exchanger. The calculation of system is made and technological scheme is presented. Shown effectiveness of the device and drawn conclusions about its rationality

Design and optimization of combined gasoline vapor recovery, cascade power and Rectisol wash for liquid natural gas cold energy utilization

The worldwide energy crisis and environmental pollution have led to an enormous demand for liquid natural gas. The recovery and application of cold energy released from the liquid natural gas vaporization process can play a significant role in solving these issues. In this study, a new configuration is proposed to realize the cascade utilization of cold energy, which includes five subsystems: gasoline vapor recovery, cascade Rankine power generation, Rectisol wash, air conditioning and liquefied air energy storage. Each subsystem is validated by the published literature of experiment and simulation, and parameters that are critical to the system are studied in depth. The genetic algorithm is then used to obtain the maximum net output power, using the working fluid composition, mass flow and fraction as optimization variables. As a result, the recovery rate of oil-gas is 95%, which meets environmental regulations for vapor recovery. When a binary zeotropic mixture (fluoromethane/carbon dioxide, 0.2247/0.7753) is selected in an actual case, the specific work and exergy efficiency of power generation are 135.16 kJ/kg and 31.57%, respectively, and 2639 kg/h of raw coal-gas can be purified to remove carbon dioxide. Under the coordination of liquefied air energy storage system coupled with an allocation algorithm, the demands and supplies of electricity and air conditioning have been matched. Therefore, the cascade utilization model provides a novel idea for cold energy recovery in natural gas stations.

Research on the general technical standards of the gasoline vapor recovery unit set

Along with the increasingly strict environmental regulation and the willingness to rapidly promote gasoline vapor recovery management, the development of technology and equipment for gasoline vapor recovery industry grows faster, and the demand for relevant technical standards is also growing. Based on the domestic and foreign development situation of gasoline vapor recovery technology and standard, this article analyzes necessity and urgency of the general technical standards for development of China’s vapor recovery unit, and then it introduces the main technical content of the national standard GB/T 35579-2017 General Specifications of Gasoline Vapor Recovery Unit”, and provides some advices to refine the related technical standards.

A novel defrosting method in gasoline vapor recovery application

Condensation method is comprehensively applied for gasoline vapor recovery (GVR), of which frosts in the heat exchanger is the greatest challenge, especially for the continuous long running cases. A novel dual channel GVR cascade refrigeration system with shell-tube heat exchanger was presented and tested in this paper. With one-work-one-standby evaporator settings, combined with refrigerant evacuation and delay switching strategies, the defrosting of low temperature shell-tube heat exchanger was analyzed and solved. Also multi-stage cycle was introduced to supply three cooling stage, which cooled the gasoline vapor from ordinary temperature to about −70 °C. By the means of industrial application validation and process calculation, the ability of the non-stop cooling during defrosting was verified. The refrigerant evacuation was proposed to prevent high pressure drop caused by frost accumulation, which also improved the cooling capacity by 28.2% and approached the defrost efficiency of 55.4%. In addition, it was found that delay switching can effectively reduce the capacity fluctuation. Based on sensitivity studies, 20 min delay was identified as the best switching timing for this device. The capacity of this system performed lower reduction, higher duty ratio and defrost efficiency.

주유소 유증기 회수설비 사용에 따른 가솔린 증기의 개인노출양상

Objectives: The purpose of this study was to investigate the possible effects of a gasoline vapor recovery system on personal exposure levels of gasoline vapor constituents including benzene, toluene, ethyl benzene, xylene(BTEX), and methyl tert-butyl ether(MTBE) among gas station workers in a metropolitan area. Methods: Thirty-one gas station workers at ten gas stations in a metropolitan area were selected as subjects for this study. Test method PV2028 as recommended in the OSHA process was used for sampling and analysis. Results: The personal exposure levels of benzene, toluene, ethyl benzene, xylene, MTBE and gasoline vapor in the gas station workers were 0.0018±0.0069 ppm, 0.0077±0.0137 ppm, 0.0002±0.0008 ppm, 0.0016±0.0084 ppm, 0.2619±0.3340 ppm, and 1.4940±1.7984 ppm, respectively. After adjustment for refueling frequency and volume, personal exposure levelswere higher in the gas stations where gasoline vapor recovery systems(Stage Ⅱ) were not installed, but the results were not statistically significant. Gasoline vapor concentrations showed a positive correlation to the level of MTBE, a gasoline additive. Conclusions: Vapor recovery systems(Stage Ⅱ) were effective not only in reducing emissions of air pollutants, but also in reducing exposure to hazardous substances among gas station workers. In addition, acorrelation between gasoline vapors and MTBE concentration was confirmed.

Preparation of ZIF-69 membranes for gasoline vapor recovery

The compact ZIF-69 membranes have been prepared by seeded growth method for the recovery of gasoline vapor which is a major challenge in the petrochemical industry. The membrane performances for separating N2/n-alkane mixtures at various operating conditions (e.g. trans-membrane pressure difference, operating temperature, feed concentration, and stage cut) were systematically investigated. The highest separation factor was 2.60 with the corresponding permeance of 5.02 × 10−8 mol/(m2 s Pa) for the N2/n-C6H14 model mixtures. Moreover, the effects of n-alkane components (n-C5H12, n-C6H14, and n-C7H16) on the separation performances were studied, and the separation factors followed α(N2/n-C7H16) > α(N2/n-C6H14) > α(N2/n-C5H12), due to the different adsorption capacities of n-alkanes on ZIF-69 materials. The present work demonstrates that the ZIF-69 membrane is a highly promising candidate for the application in gasoline vapor recovery.

유증기 회수설비 유무에 따른 주유소 근로자들의 요중 trans, trans-Muconic acid, Hippuric acid에 관한 연구

Objectives: This study aims to investigate the excretion aspect of urinary t, t-MA and hippuric acid by measuring concentrations of urinary metabolites according to the use of gasoline vapor recovery system. Materials:In order to analyze urinary metabolites, samples from the 23 gas station workers ten gas stations in the Seoul and Gyeonggi Province area were collected once daily after work. In addition, a survey was conducted on work factors and lifestyle habits as factors affecting the concentration of urinary metabolites. Results: The average concentrations of t, t-MA and hippuric acid after work were <TEX>$0.124{\pm}0.177mg/g$</TEX> creatinine and <TEX>$0.557{\pm}0.251g/g$</TEX> creatinine among workers at gas stations where gasoline vapor recovery systems were installed. The average concentrations of t, t-MA and hippuric acid were <TEX>$0.160{\pm}0.113mg/g$</TEX> creatinine and <TEX>$0.682{\pm}0.619g/g$</TEX> creatinine among workes at gas stations where gasoline vapor recovery systems were not installed. Average concentrations were higher at gas stations where a gasoline vapor recovery system was not installed, but the differences were not statistically significant differences. Urinary t, t-MA and hippuric acid average concentrations of smokers and non-smokers were higher in the gas stations where gasoline a vapor recovery system was not installed. T, t-MA as a factor evaluation affecting the concentration of urinary metabolites was not statistically significant in all factors, while hippuric acid was statistically significant only for age(p=0.024). Conclusions: The average concentrations of urinary t, t-MA and hippuric acid were higher in gas stations where gasoline vapor recovery systems were not installed compared to gas stations where such a system was installed. There needs to be an assessment of biological monitoring according to refueling activity considering skin absorption of benzene and toluene and presence of gasoline vapor recovery system.

Study on the Development of ZIF-8 Membranes for Gasoline Vapor Recovery

The recovery of gasoline vapor is still a major challenge in the petrochemical industry. In this study, a zeolitic imidazolate frameworks (ZIFs) membrane has been developed and first applied to gasoline vapor recovery. Zeolitic imidazole framework (ZIF-8) membranes were fabricated by a facile solvothermal seed growth method on ZrO2 supports. X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis measurements were conducted to study the morphologies, structure, and physical and chemical properties of ZIF-8 membranes. The effects of trans-membrane pressure drop, operating temperature, feed concentration, and stage cut on the separation performances of ZIF-8 membranes were systematically investigated. At 293 K, the ZIF-8 membrane showed an optimum n-hexane (n-C6H14) permeance of 7.16 × 10–8 mol/(m2·s·Pa) with the corresponding separation factor of 2.46 for the nitrogen/n-hexane model mixtures at a trans-membrane pressure drop of 0.05 MPa, a stage cut of 0.293, and a n-hexane volume f...

Sensitivity analysis and optimization for gasoline vapor condensation recovery

Volatile organic compounds (VOCs) are easily evaporated and discharged from everywhere into the atmosphere, especially in various operations of gasoline. The emission of VOCs is always a significant environmental problem, and the control of VOCs pollution has been a hot topic in the field of air purification. In this paper, the condensation separation method for gasoline vapor recovery was investigated and four gasoline vapors of S1–S4 were selected for the sensitivity analysis and optimization of the condensation process, using the Model Analysis Tools from Aspen Plus. Generally, to control VOCs pollution efficiently, both the vapor recovery efficiency and the outlet vapor concentration of the condensation recovery system should be simultaneously considered. Then an optimized three-stage condensation process was proposed, whose condensation temperatures were optimized and designed at 1°C, −40°C and −110°C, respectively. Further, based on the comprehensive consideration of both meeting the more strict VOCs emission standard and ensuring the condensation recovery system work stably and economically, it was recommended that the maximum total vapor recovery efficiencies for S1–S4 should be 99.73%, 99.79%, 99.82% and 99.19%, and the minimum outlet vapor concentrations be 2.87g/m3, 2.75g/m3, 3.04g/m3 and 16.98g/m3, respectively. Accordingly, the condensation temperature of the copious cooling stage should be set at −130°C. Moreover, the total cooling duties for the single-stage and three-stage condensation processes were investigated and compared when the condensation temperature of the recovery system ranged from 20°C to −110°C. The total cooling duties of the three-stage condensation process for S1–S4 would be saved by 12.23%, 15.68%, 13.96% and 15.65%, respectively. Finally, a three-stage condensation system was developed for the industrial gasoline vapor recovery, which has performed well since its installation.

Gasoline Vapor Recovery Based on Integrated Technology of Absorption-Adsorption

Two tests were designed to investigate activated carbon adsorbing gasoline vapor. In the inlet vapor-air mixture of the adsorption towers, the vapor volume fractions were 0.05 and 0.40, and the mixture flow were 40 m3/h and 65 m3/h respectively. The test results showed that their recovery rate were above 95％. A new integrated technology of absorption-adsorption for gasoline vapor recovery was developed. The recovery rate was up to 99.6％, and the outlet vapor volume fraction can be controlled below 0.0032. The integrated system will appear distinct comprehensive benefit.

Cost-Effective Control of Ground-Level Ozone Pollution in and around Beijing

Abstract Ground level ozone pollution has become a significant air pollution problem in Beijing. Because of the complex way in which ozone is formed, it is difficult for policy makers to identify optimal control options on a cost-effective basis. This paper identifies and assesses a range of options for addressing this problem. We apply the Ambient Least Cost Model and compare the economic costs of control options, then recommend the most effective sequence to realize pollution control at the lowest cost. The study finds that installing of Stage II gasoline vapor recovery system at Beijing’s 1446 gasoline stations would be the most cost-effective option. Overall, options to reduce ozone pollution by cutting vehicular emissions are much more cost-effective than options to “clean up” coal-fired power plants.

Simulation of Condensation Process for Gasoline Vapor Recovery

A condensation separation model was designed to simulate and optimize the gasoline vapor condensation recovery systems in gas stations using Aspen Plus software. The relationship of either vapor recovery ratio or system energy consumption with condensation temperature was investigated. The results showed that the recovery system should be properly optimized into three-stage condensation processes. When the condensation temperatures at the three-stage were 2°C, -30°C and -80°C, respectively, the system recovery ratio would slightly exceed the national standard index of 95% of China and the system energy consumption could be almost controlled within the lowest level. Moreover, if the condensation temperature at the third stage was -120°C, the recovery ratio would be up to 99.62% and the energy consumption could be controlled in a little rising.

311 給油所におけるガソリンベーパー液化回収技術(大気環境保全・改善技術(2))

311 給油所におけるガソリンベーパー液化回収技術(大気環境保全・改善技術(2))

Separation of gasoline vapor from nitrogen by hollow fiber composite membranes for VOC emission control

This study deals with removal of volatile organic compounds (VOCs) from nitrogen by membranes for emission control. Hollow fiber composite membranes comprising of a thin layer of poly(ether block amide) supported on microporous poly(vinylidene fluoride) substrate were prepared for this purpose. The membranes were initially examined for the removal of representative VOCs from binary VOC/nitrogen mixtures. Then the separation of actual gasoline vapors, with and without gasoline additives, from nitrogen using the composite hollow fiber membranes was investigated. The separation performance of the membranes at various operating conditions (e.g. feed composition, operating temperature) was evaluated. It was found that the hollow fiber composite membranes were effective for the recovery of gasoline vapors from nitrogen. At ambient temperature, an overall permeate VOC concentration as high as 95 wt% was obtained, and the overall VOC flux was in the range of (2–4) × 10 −2 g/(m 2 s). The composition profile of the recovered gasoline was different from the gasoline vapor in the feed gas, and blending reformulation may be needed for the recovered gasoline to meet certain volatility and octane ratings. The membrane was found to be stable for gasoline vapor recovery during a 10-month period of testing.

Reduction of post-shift traffic injuries among gasoline station workers: Are they related to the reduction of occupational gasoline vapor exposure?

Aims: Solvents exposure is known to impair psychomotor performances. With gasoline vapor recovery devices (GVRD) installed, this study should observe a decrease of traffic injuries after shift among gasoline workers. Methods: The occupational injury registry data of 1991–2000 in a petrochemical company containing 20,000 workers were analyzed. Cumulative injury rate (CIR) was calculated to estimate lifetime risk. The potential workday loss (PWDL) and the potential salary loss (PSL), which summed up the expected workdays and salary loss assuming a uniform retirement age of 65, were calculated for traffic injuries. Workers of gasoline sales were compared with those without gasoline exposure for commuting traffic injuries. The rate ratio (RR) was calculated based on a person–time data. Results: The CIR dropped 3.14 times during 1997–2000 for commuting accidents on the way back home compared with that during 1991–1992, and the PWDL and PSL dropped 25.2 and 21.5 times, respectively, which corresponded with the time of installments of GVRD. The RRs of commuting accidents on the way back home in the exposed group significantly decreased from 2.15 to 0.53. Conclusions: The decrease of commuting injuries on journey back home for gasoline workers were probably related to the effective reduction of solvent exposure.

A breath of bad air

A breath of bad air