TECHNOLOGIES OF PREVENTION OF LOSSES (EMISSIONS) OF HYDROCARBONS FROM FUEL TANKS OF VEHICLES

This article is devoted to a comprehensive analysis of existing technologies and methods to prevent hydrocarbon losses from fuel tanks, taking into account the study of the advantages and disadvantages of these technologies that affect the effectiveness of emission prevention. The aim of the work is to identify the best technologies, systems, trends, features of capture and prevention of hydrocarbon losses from fuel tanks. The main causes of fuel losses from car fuel tanks are considered. Losses of hydrocarbons from fuel tanks due to large and small "breaths" are described. The physical properties of gasoline that characterize its evaporation and evaporation ability are described. The largest sources of emissions in the form of evaporation from vehicles are listed. Three separate mechanisms related to losses through the breathing valve of the fuel tank and fuel leakage are considered. Qualitative characteristics of the fuel-air mixture that evaporates from car tanks and emissions of pollutants during refueling of car fuel tanks are given. The causes, sources, consequences of fuel losses from car fuel tanks are considered and summarized in the figure. Also, the modern means of capturing hydrocarbon vapor from the fuel tanks of cars, which are relevant today, are summarized in the table. Based on a comprehensive situational analysis of current technologies and methods to prevent loss of hydrocarbons from fuel tanks, taking into account the study of the advantages and disadvantages of these technologies, we have identified the best technologies to prevent losses from large and small breaths. KEY WORDS: FUEL TANKS, PETROL, LOSSES, EMISSIONS, ANALYSIS, LOSS PREVENTION TECHNOLOGIES.

Method for predicting the degree of hydrocarbon vapor recovery at absorption

Over the years of practical use of absorption, various methods for calculating absorbers have been developed. Among others, the calculation of mass transfer processes was created based on the use of a so-called mass transfer coefficient β, showing how much mass of the target substance passes from the gas phase to the liquid one through a surface area unit per time unit. To determine β, empirical equations are used depending on their validity for a particular type of absorber and operating conditions given. However, these calculations are relatively complex and fail to be applicable to whatever absorber design used. The calculations of phase transitions using phase equilibrium constants do not depend on the design features of the equipment where mass transfer occurs. However, to date, the phase equilibrium theory has been applied to calculate the separation of a multicomponent mixture under no air condition; therefore, it could not be used to predict phase transitions when a gas-air mixture contacts a liquid absorber. Based on the theory of phase transitions, the authors developed a simplified method for predicting the degree of oil vapor recovery at absorption. The technique was successfully tested through calculating the efficiency of the jet absorption unit used to recover oil vapor. Also, the installation performance at absorbent replacement was simulated. The replacement of easily volatile oil used as a working fluid with oil of a lower saturated vapor pressure was shown to significantly increase the degree of hydrocarbon vapor recovery. The possibility of applying the technical solution is limited with the following conditions: low-volatile liquids used as absorbent cannot be highly viscous and have a high pour point; their quality should not deteriorate when absorbing oil vapor; the cost of replacing the working fluid should be reasonable.

USING PASSIVE ULTRASENSITIVE HYDROCARBON DETECTION TO ELUCIDATE NASCENT PIPELINE LEAKS: A COLUMBIA PIPELINE CASE STUDY

Underground and above ground hydrocarbon transport pipelines often contain carbon dioxide (CO2), hydrogen sulfide (H2S), water and chlorine which cause corrosion. Corrosion often begins as pinpoint leaks that expand over time. These leaks are often difficult to detect using conventional methods until a major event occurs. Pressure testing can determine a leak to be present, but does not pinpoint the location of the leak. Pipeline pigs normally only detect leaks after they become significant and costly. The use of methane detectors has also been utilized with the recent popularity of drones. However, the use of airborne methane detectors has been less than successful due to the limited linear range of the methane detectors and poor sensitivity. Passive ultrasensitive sorbent modules have been used to detect nascent leaks at parts per billion ( ppb) levels, which is 1,000 times more sensitive than traditional methods. Passive ultrasensitive sorbent modules contain a specially engineered oleophilic (i.e. oil loving) adsorbent encased in a microporous membrane. These membrane pores are small enough to prevent the entrance of soil particles or water, but are large enough to allow hydrocarbon vapor molecules to pass through and concentrate on the adsorbent material within. The result is a 1,000-fold increase in concentration allowing for ppb level detection. The Columbia natural gas condensate pipeline case study took place in 2007 just southwest of Pittsburgh and involved a pipeline buried at a depth of approximately 6 ft. Ultrasensitive passive modules were installed at the surface above the pipeline. A battery operated hand drill was used to drill a 1 inch hole in the ground to an approximate depth of 3 ft. The module was inserted into the hole, covered with dirt, and left for 4 days. After retrieval the modules were analyzed by thermal desorption/mass spectrometry. The objectives of the survey were to: examine potential fingerprints for evidence of gas condensate leakage, determine if nascent leaks could be distinguished from baseline readings, compare results with pipeline maintenance records for ground-truthing purposes. The results of the project showed: several locations along the pipeline exhibited strong potential as leakage points, the results were validated with a known leak along the pipeline, the data helped to monitor the efficiency of prior pipeline repair work, baseline levels of hydrocarbons were statistically derived from the data, potential nascent leak points were identified along the pipeline.