Techniques For Restoration Of Heavy Crude Oil-contaminated High-salt Fine-grained Soil: Synergism Of Supplementing Heat Cleaning With Sonochemistry And Coal-adsorption

Along with steady progress in petroleum industry, organic contamination engendered by petroleum prove to be a point of people's attention. There have been 29 producing oilfields in the Bohai Bay rim, belonging to three domestic main oilfields (Liaohe, Dagang, Shengli). The procedure of production is running the risk of crude oil dripping, dropping, leaking, et al. The leaking crude oil caused severe oil contamination in the coastal territory. So it is necessary to conduct a thorough renovation. In this paper, a typical study area was selected in the Yellow River Estuary to research and develop techniques for restoration of heavy crude oil-contaminated high-salt fine-grained soil.In chapter one of this paper, the merits and faults of various measures in restoration of oil-contaminated soil are balanced, and it is indicated that the restoration effect of conventional technology is restricted for tetracyclic condensed aromatics in soil. However, sonochemistry has an unique advantage in the realization of separating oil-soil hybrid system, and it is considered as one of the most potential technologies to carry out oil-soil homogeneous system decontamination. In this chapter, research content, research objective, research method and technique routing are been introduced, too. As purification method applied on some contaminated sites are determined by soil structure, pollutant type and its concentration, requirement standard and corresponding cost with soil purification to a large extent. Characteristics of heavy crude oil, high-salt fine-grained soil and its contamination feature are studied in chapter two and chapter three separately. The former includes variation curve of viscosity with temperature of heavy crude oil, properties of heavy crude oil,variation curve of yield stress with temperature shift of heavy crude oil,rheological curve with temperature of heavy crude oil, the influence of cooling rate on the firstly breaking up & decaying curves of the shear stress of heavy crude oil, and variation curve of wax-crystal structure of heavy crude oil with temperature. The latter includes grain size distribution of soil, soluble salts types and heavy crude oil contamination distribution in soil near oilwell. In chapter four, water temperature under sonochemical reactor is determined by a mercury thermometer at different actuation duration. oil removal efficiency under diverse technological parameters are examined in decontaminating petroleum hydrocarbon-contaminated beach fine soil. In chapter 5, adsorption studies are conducted using bunkercoal taken from oilfield central heating system station to test the feasibility of oily rinsing wastewater cyclic utilization under static and dynamic adsorption. In the end, research conclusions and the necessity of perspectives are introduced in chapter 6.Through the development of above-mentioned studies, the major research achievement and conclusions drawed from the study on restoration techniques are as follows:(1) Characteristics of heavy crude oil includes several aspects, such as,variation curve of viscosity with temperature, properties of heavy crude oil,variation curve of yield stress with temperature shift, rheological curve with temperature, the influence of cooling rate on the firstly breaking up and decaying curves of the shear stress and variation curve of wax-crystal structure with temperature, etc.The heavy crude oil of high solidation point showes a viscous solid property at normal temperature. As wax-crystal structure may play an important role in the process. Viscosity of detained oil is substantially affected by the temperature with a feature of non-Newtonian fluid. And it has a higher solidification point at normal pressure. The fluid model of the crude oil belonges to bingham liquid as temperature increment reaches to 50℃. Rise in temperature could destroy the network structure formed by wax-crystal, asphaltene and colloid, and this could boost rheological characteristic of heavy crude oil. The waxy crude oil has complex composition,high solidification point(24.1℃)and exhibits most complex rheology. It has been found out that the cooling rate has a great influence on thixotropy in the experiments,and the higher the cooling rate,the greater the yield stress and equilibrium stress.(2) The soil of Yellow River estuary region which is contaminated by petroleum is alluvial and fine soil, and the investigated iron content of soil sample is adequately high, among which the upper range of peak concentration of calcium cation is 353.3mg/kg, the upper range of peak concentration of magnesian cation is 690mg/kg, and the upper range of peak concentration of bicarbonate ion content is close to 180mg/kg. According to its specific size and mineraliogical properties, the seaside soil can be defined as one of active solids, which tend to affect the subsequent oil-soil separation in all property. Whereas, the contaminated soil exceeding the allowed figure 500 mg/kg is richly distributed close to the surface, especially in 30cm depth range or so. The peak value of oil content in soil attains 627.935mg/kg.(3) Heating effect could be brought forth in the process of ultrasonic wave transmission, which may enhance the temperature of the medium. Whereas, it is not obvious with heating effect of sonochemical cleaning reactor in this study. When used to clean crude oil-contaminated soil at a higher temperature, it is necessary to supply some external heat producer to heat up scavenger system efficiently. And in this paper, thermal effect of ultrasound is made inquiry into the foundament in terms of theory. Theory supposes that for target spot the temperature rise can reach 36℃/s during 3000W/cm3 of high intensity ultrasound processing. In fact, the temperature rise could not arise in sonochemical reactor used in laboratory for some reasons. The effect of factors such as:slurry concentration; duration time of irradiation; slurry pH; different alkaline additives and free radical reagent H2O2 on the desorption of hydrocarbon from fine salty soil, is considered in the study. A system of process parameters are proposed in decontaminating petroleum-contaminated soil, especially decontaminating high waxy-crude oil contaminated soil, such as system temperature 20℃, slury concentration(mass ratio of water to solid)6:1, time 5min, alkalic reagent Na₂CO₃ and pH9,slurry bing stirred timely. For the time being, the removal efficiency of one sonochemistry reactor could maintain a level of over 90%。And several equivalent hybrid orbital theory is employed in explaining the mechanism during oil and soil separation process at micro level. Through the experiment, we improve techniques of heavy crude oil-contaminated high-salt fine-grained soil by synergism of supplementing heat cleaning with sonochemistry. In the course, the consolidation of the soil being processed is found out and interpreted by"differential pressure theory". In addition,it is considered that the cause of creation of surface active separating agent results from saponification reaction, which takes place after alkaline reagents are added to slurry system in terms of theory.(4) From the economical viewpoint, because coal has a developed micropore distribution, it usually has a enormous specific surface area, thereout it performs a snapping adsorption characteristic distinct from other sorbents. In addition, Organic pollutants (e.g. heavy crude oil) have a special property which could strongly sorb to carbonaceous sorbents such as coal and activated carbon (BC and AC, respectively). Bunkercoal is used as sorbent, which has an obvious low cost advantage. The overall viability of the technique in turn rely on the availability of a simple and energy-efficient water remediation strategy.In this thesis, Yangquan bituminous coal sorbent to decontaminate wastewater of heavy oil rinsing wastewater in laboratory scale is carried out, which investigates the effecting and influencing factors in wastewater remediation. First of all, ultimate analysis, ash analysis, Eshka gravimetric method, X-ray fluorescence spectrometry are adopted to measure fractionated components in Yangquan bituminous coal. Secondly, it is determined about the time needed to satisfy the separation of slurry. Subsequently, it is conducted about oil adsorption of batch experiments of temperature, pH, time, granular size, dosage of sorbent. A better adsorption purpose could be reached at the time that temperature 20℃, pH5, adsorption time over 10min, sorbent particle diameter as little as possible, sorbent dosage as much as possible could be ensured. Lastly, on the basis of static adsorption experiments, breakthrough curve of dynamic adsorption tests at 2.5mL/min,5.0mL/min,10.0mL/min three different rates of inflow are carried out respectively, which both confirm furtherly the significance of static experiments and reflect the capability of adsorption and the rate of oil removal during the remediation operation.Focus on the recycle & reuse technology of heavy crude oil extraction from wastewater, a lot of work about oily rinsing wastewater remediation by Yangquan bituminous coal sorbent filtering medium is conducted in laboratory. The remediation of heavy crude oil rinsing wastewater by Yangquan bituminous coal sorbent filtering medium is a novel process method. This method may ensure that the cleaned water could be reused in the next soil cleaning stage. The spread and exploitation of this rearch findings has an important financial and social benefit for the national strategy practice of the Huanghe River Delta High-efficiency Ecological Economic Region construction.Based on research findings of this paper, two China Invention Patents have been applied for, and four articles have been written and published. In the light of chapter one content, a paper of"Review on ultrasonic disintegration of heavy/viscous oil-bearing soil"is engaged and will be published in June of 2011 by Chinese Journal of Soil Science. In accordance with chapter three content, a paper of"Pilot survey of feature on viscous oil contaminating seaside soil in the Bohai Bay Rim"had been published in Journal of Chemical Industry and Engineering(China) in January. According to chapter four content, a paper of"Impact factor of sonochemical cleaning technique decontaminating petroleum hydrocarbon-contaminated beach fine soil"had been published in Journal of Chemical Industry and Engineering(China) in Aprial. In line with chapter five content, a paper of"Remediation of Rinsing Wastewater for Recovery and Reuse by Yangquan Bituminous Coal Adsorbent Filtering Medium in Heavy Oil-Contaminated Site"has been engaged by Journal of Chemical Industry and Engineering(China).The innovations of this thesis are as follows:(1)In this paper, a set of process parameters has been set up, which could restore heavy crude oil-contaminated high-salt fine-grained soil through taking advantage of synergism of supplementing heat cleaning with sonochemistry. And in standard laboratory conditions, a fine effect could be reached. This has been applied for China Invention Patent of"Purification technique of sonochemistry to decontaminate heavy crude oil-contaminated soil"(application No. 201010610382.1).(2)This paper puts forward that bunkercoal being combusted in Gudao oil extraction factory of Shengli Oilfield administration could be used as sobent to purify the rinsing wastewater. A technical method has been founded, which could treat oily rinsing wastewater by a special process of static adsorption. This has also been applied for China Invention Patent of"Purification technique of feed coal sorbent fixed-bed to decontaminate oily rinsing wastewater"(application No. 201010610374.7).