Objective Supersonic separation is a new gas purification and fuel gas processing technology based on contraction-expansion nozzle.The cyclone in the post-swirl supersonic separator is usually set in front of the diffuser section,which is easy to induce the positive shock wave and destroy the low temperature environment inside the separator.Moreover,the shock wave is difficult to control.Therefore,this study intends to reduce the impact of shock waves by optimizing the structure.Methods Firstly,based on the principles of thermodynamics and aerodynamics,a shock wave control theory for a rear-swirl supersonic separator was proposed.Secondly,according to the theory,a trans-swirl structure which could control shock waves was designed,and a universal design formula for the structure was established.Thirdly,through numerical simulation,the effects of three important structural parameters on the shock waves control were analyzed,namely,the dip angle of the trans-swirl structure,the length of the gradually expansion section and the twist angle of the cyclone blade.Results The separator had the best performance when the dip angle of the trans-swirl structure was set to 3.3°,the length of the gradual expansion section was set to 107 mm,and the blade torsion angle of the cyclone was set to 120°.Conclusions Compared with the traditional cyclone post-separator,the addition of the trans-swirl structure can ensure that the fluid flow area continues to increase in the gradual expansion section,thereby achieving effective control of shock waves and improving the condensation and separation efficiency.
Objective The residual catalyst during the preparation of helical carbon nanofibers(HCNFs)can affect its intrinsic properties.Acid washing is often used to remove the catalyst in helical carbon nanofibers,but it can destroy the structure of the fiber and increase the cost of use.Helical carbon nanofibers were prepared by using water-soluble salt as catalyst,and the catalyst was removed by washing to obtain high-purity helical carbon nanofibers.Methods Helical carbon nanofibers were prepared by chemical vapor deposition using potassium carbonate as catalyst and acetylene as carbon source.The potassium carbonate catalyst was removed by simple water washing,and the effect of preparation temperature on the morphology of helical carbon nanofibers was investigated.The microstructure and elemental composition of the helical carbon nanofibers were characterized by field emission scanning electron microscopy,transmission electron microscopy and energy dispersive spectroscopy.The crystal structure and surface functional groups of the helical carbon nanofibers were characterized by X-ray diffraction,Raman spectroscopy and Fourier transform infrared spectroscopy.Results The helical carbon nanofibers prepared at 700℃have a diameter of about 60 nm,a helical structure and a uniform morphology.The carbon atoms of HCNFs are arranged in a short-range order,mainly composed of C-H and C=C functional groups.The potassium carbonate catalyst has a rhombic symmetrical structure in the fiber,resulting in a chiral symmetrical growth of the fiber on both sides of the catalyst.Conclusions Helical carbon nanofibers with uniform morphology were prepared by chemical vapor deposition.High purity helical carbon nanofibers can be obtained by washing off the surface catalyst.
Objective The effect of mechanical properties of hydrate decomposition on reservoir stability was studied by multi-stage depressurization of gas hydrate under the action of different types of decomposition promoters.Methods The effect evaluation and law analysis of rock mechanics stability of hydrate sediment reservoir are carried out by using multiple factors such as different effective confining pressures,different decomposition agents and their concentrations,soaking time,and through multi-level depressurization decomposition.Results With the pressure drops and decomposition,hydrate saturation,shear strength and elastic modulus decrease gradually,and methane hydrate sediments show brittle failure.Conclusions The higher the concentration of decomposition agent is,the greater the influence on hydrate mechanics is caused.The higher the injection concentration is,the longer the soak time is,the lower the hydrate strength is,and the more obvious the effect of the decomposition agent on reducing the hydrate strength is.Alcohol decomposition agent(ethylene glycol)is easier to weaken the strength of hydrate samples and to reduce reservoir stability than salt decomposition agent(CaCl2)during hydrate production.
Objective The aim is to solve the problem that the contamination type of the completion fluid can not be effectively identified after being contained by brine and residual acid during the drilling of the target layer.Methods The contamination of brine and residual acid with different mass fractions of the completion fluid was measured,and the labels of the data samples with different contamination degrees were revised by K-means clustering algorithm.Different BP neural network models were trained according to the difficulty of obtaining data sample features and the number of hidden layers,and the classification accuracy of the models was tested by leave-one-out cross validation method.Results It is found that the more features the data samples possess,the higher classification accuracy of the trained BP neural network could be achieved,while more hidden layers would lower the classification accuracy.The BP neural network model with one hidden layer was subsequently established with data samples that contain four kinds of features including"rheology+aging+filtration loss+well name".The average classification accuracy rate reached as high as 93.18%.Conclusions The BP neural network model trained by rheology and filtration loss features can be quickly deployed in the oil-testing sites to solve the problem of failing to identify the type of completion fluid contamination due to the lack of special equipment in the field.
Objective The aim is to prepare reformate oil dechlorination agent with high chlorine capacity and realize industry application.Methods The dechlorination agent for reformate oil was prepared by using pseudo-boehmite as the carrier,loading two-component activator,screening the pore-forming components,adjusting the pore structure and optimizing the reasonable molding and baking process.The physico-chemical properties of the dechlorination agent were characterized by using BET,XRF,SEM,and the dechlorination agent performance was evaluated by using a 20 mL small test device.Results At a reaction temperature of 50℃,a volumetric space velocityof 3 000 h-1,and a chlorine mass fraction of 60 000 mg/kg in the reaction gas,the chlorine capacity of self-made dechlorination agent was 18.4%.The dechlorination agent product was applied to the reforming unit of CNOOC Ningbo Daxie Petrochemical Ltd.,the differential pressure before and after dechlorination tank was less than 50 kPa,and the chlorine mass fraction at the outlet of the dechlorination tank dropped to below 0.5 mg/kg.Conclusions The influences of adding different types and contents of active compounds and pore-forming agents,as well as the baking process parameters on the properties of dechlorination agent was clarified,which could provide reference for the preparation and optimization of similar dechlorination agents.
Objective Conventional capillary laminar flow measurement technology has nonlinear problems such as inlet and outlet pressure loss due to the structure of laminar flow sensing element.Therefore,it is necessary to improve the laminar flow sensor to solve the nonlinear problem.Methods A conical laminar flow element was proposed,which could effectively solve the nonlinear pressure loss problem in the initial stage of laminar flow by taking advantage of direct pressure extraction in the fully developed stage of laminar flow and directly reflect the linear relationship between flow and differential pressure.Three kinds of conical laminar flow elements with different gaps were designed and manufactured,and the gas micro and small flow measurement system was built.Results Within the flow range of 0.015 0-2.348 1 kg/h,the measurement errors of the three sets of devices are in the range of±2%,and the measurement error of the conical laminar flow element device based on the gap of 0.7 mm is the smallest,in the range of±1%.Conclusion It is proved that the conical laminar flow element has good performance in measuring small and micro natural gas and other gas flow.
Objective In order to improve the yield of tert-butylphenyl diphenyl phosphate(BPDP)synthesized by one-pot method,alkyl imidazole hydrogen sulfate ionic liquids with different spatial structures and electronic groups were used as catalysts.Methods This study compared the effects of N-alkyl imidazole hydrogen sulfate ionic liquids with different carbon chains and alkyl imidazole hydrogen sulfate ionic liquids with different electronic groups on the yield of BPDP synthesis,and further investigated the effects of catalyst dosage and catalyst circulation on the yield.Results When the side chain structure of the catalyst is ethyl,the yield of BPDP is the highest.Electron-absorbing groups can increase the yield of BPDP,while electron-donating groups can reduce the yield of BPDP.The yield of BPDP is the highest when the catalyst dosage is 1.5 w%of 4-tert butylphenol.The catalyst still has high catalytic activity after 6 cycles of useage.Conclusions The spatial structure and electronic groups of ionic liquid catalysts have a significant effect on the yield of BPDP.When 1-ethyl-2-fluoro-imidazole hydrogen sulfate ionic liquid is used as the catalyst,the yield of BPDP can increase to 85.3 w%,thereby economic benefits can be improved.
Objective Mixing hydrogen into natural gas will change the properties and flow state of the fluid,thus affecting the metering accuracy of the flowmeter.ANSYS Fluent was used to simulate the velocity distribution of hydrogen-mixed natural gas after bending pipe,and analyze that whether the existing installation conditions of orifice flowmeter and ultrasonic flowmeter are suitable for hydrogen-mixed natural gas pipeline.Methods Simulating the velocity field of hydrogen-mixed natural gas after single 90°bending pipe and double 90°bending pipe,and comparing the velocity distribution of hydrogen-mixed natural gas with different hydrogen content on the pipeline center line and some sections after the bending pipe to analyze whether the installation position of the flowmeter specified in the current standard achieves symmetrical velocity distribution for hydrogen-mixed natural gas,and to determine whether the length of the front straight pipe section of the installation position of the elbow back flowmeter stipulated in the current standard needs to be extended.Results (1)At the 44D and 50D sections after a single 90°bending pipe,the H2 molar fraction with 10%-30%H2 did not return to the symmetrical velocity distribution;(2)At the 44D section and 50D section after the double 90°bending pipe,the flow velocity with 10%H2 has returned to the symmetrical velocity distribution,while the flow velocity with 20%-30%H2 has not returned to the symmetrical velocity distribution;(3)At the 30D section after the double 90° bending pipe,the velocity with 10%H2 did not return to the symmetrical velocity distribution.Conclusions (1)For hydrogen-mixed natural gas,the length of the straight front section of the single bending pipe rear flowmeter stipulated in the current standard should be appropriately extended;(2)For 20%-30%H2,the length of the straight pipe section in front of the flowmeter after the double bending pipe should be appropriately extended;(3)When the orifice aperture ratio decreases,the length of the straight pipe section in front of the orifice flowmeter with 10%H2 should be appropriately extended.
Objective In order to improve the separation rate of oil-water-sand mixed liquid in the process of oil exploitation and transportation,an integrated oil-water-sand pre-separation equipment was designed and its practical capability was tested.Methods Based on the orthogonal test,the structural parameters of the cyclone oil-water separation unit were optimized by numerical simulation method,and the optimum operating conditions were explored.The accuracy of simulation results and the feasibility of designed equipment size were verified by an example.Results Structural parameters of the oil-water-sand pre-separation equipment were determined as follows:the main diameter of the cyclone of 66.5 mm,the overflow port diameter of 4.6 mm,the bottom flow port diameter of 14 mm,and the large cone angle of 20°.The optimal operating conditions under this size were identified with the oil phase volume fraction of the mixed liquid was set at 10%.The simulation demonstrated that the optima inlet flow rate,the overflow split ratio,and the oil removal efficiency was 15 m/s,15%,and 83.1%,respectively,while the corresponding values were 15 m/s,15%-20%,and 79%in real tests.Conclusions The results of numerical simulation were consistent with the experimental results.The optimized equipment can satisfy the requirements of oil-water separation pretreatment and has great application prospects.
Objective Aiming at the corrosion problem caused by crude methanol with high moisture content in the storage tank,the anticorrosive coating for methanol storage tank was studied.Methods The epoxy-phenol resin paint coating samples and inorganic zinc silicate coating samples were soaked in pure methanol and methanol solution with water content of 37.5%,and the appearance,film thickness,weight and infrared spectrum before and after soaking were compared and analyzed,including the microscopic morphology of the coating before and after soaking was tested by optical microscope.Results The anti-corrosion performance of the epoxy-phenol resin paint significantly changes in both solutions.In a methanol solution with a moisture content of 37.5%,the epoxy ether bond is destroyed,hydroxyl functional groups appear,and the performance of the paint film decreases,resulting in damage to the paint film.The performance of inorganic zinc silicate coatings shows little change in both solutions.Conclusion In aqueous methanol,inorganic zinc silicate coatings have stronger corrosion resistance.
Objective By endowing polymer microspheres with a fluorescent characteristic that enables them to have tracer performance,the actual situation of adsorption,retention,and migration of polymer microspheres in the formation can be clearly understood based on the detection of the produced liquid.However,a difficult problem that needs to be solved urgently is how to maximize the displacement ability of keeping the original microspheres with the effective integration of fluorescent materials and polymer microspheres.Methods The preparation of fluorescent microspheres was achieved through copolymerization reaction using ordinary core-shell microspheres with cationic functional monomers,acrylamide,and other main components as carriers and carbon quantum dots as fluorescent materials.The fluorescence intensity was measured and a comparative experiment of Zeta potential,hydration expansion,and sealing performance was carried out.Results The fluorescence yield rate of carbon quantum dots was high,with a minimum detection limit of 0.05%;The Zeta potential data demonstrated that the fluorescent monomer was successfully fixed to the core layer of the microspheres,ensuring effective fusion of the fluorescent material with the prototype microspheres;The difference in sealing efficiency between fluorescent microspheres and ordinary core-shell microspheres was within 3%,and the hydration expansion and sealing performance of them were basically same.Conclusions The introduction of the carbon quantum dot fluorescent material into the core layer has not changed the characteristics of the polymer microspheres,and the detection limit value is low,which is expected to be used in subsequent field applications.
Objective In order to find a new absorbent with good absorption performance,low solvent loss,and low energy consumption for CO2 capture,the preparation and performance of guanidine amino acid ionic liquids to capture CO2 in flue gas was investigated.Methods Three kinds of guanidine amino acid ionic liquids with low viscosity,namely[TMG][Lys],[TMG][Ala],and[TMG][Asp],were prepared using tetramethylguanidine(TMG)as a cation and lysine(Lys),alanine(Ala),and aspartic acid(Asp)as anions.The effects of anionic types on CO2 absorption were investigated.Results The alkaline[TMG][Lys]had a higher CO2 absorption,with a CO2 absorption capacity of 0.64 mol CO2/mol IL under the condition of atmospheric pressure,45℃,and 80 mL/min.The addition of water had a positive effect on the absorption of CO2.The absorption capacity of 30 wt%[TMG][Lys]aqueous solution increased to 0.99 mol CO2/mol IL and could still keep 0.81 mol CO2/mol IL after 5 absorption-desorption cycles.The decarbonization mechanism of[TMG][Lys]was analyzed by Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance hydrogen spectroscopy(1 H-NMR).CO2 mainly reacts with the amino group on the anion to form carbamate to achieve efficient capture of CO2 in the flue gas.Conclusions It can provide reference for the development of new absorbents in industrial CO2 capture.
Objective The aim is to explore the impact of fracturing construction parameters on the erosion of movable elbow,and movable elbow erosion behavior and change trend of maximum erosion rate under different working conditions.Methods The CFD software is used to establish a model of double-curved movable elbow with a diameter of 69.85 mm,and the erosion behavior of the movable elbow under different installation angles,proppant mass flow rates,fracturing fluid flow rates and viscosity conditions is simulated and calculated in combination with the actual fracturing conditions.Results Under different working conditions,the maximum erosion rate of the elbow occurs at the outlet of the outer arch side of the second curved arc.Under the same condition of other parameters,the maximum erosion rate of the movable elbow appears a minimum when the installation angle is 75°.When the mass flow rate of proppant is in the range of 4.2-25.2 kg/s,the maximum erosion rate increases linearly.When the mass flow rate of proppant reaches 33.6 kg/s,the erosion rate decrease slightly due to the"shielding effect".Erosion rate shows an approximate exponential growth trend with the increase of fracturing fluid flow rate;When the viscosity of the fracturing fluid is within the range of 10-40 mPa·s,the maximum erosion rate of the movable elbow is relatively stable,and the maximum erosion rate also increases with the increase of the viscosity,and tends to be stable after the viscosity reaches 120 mPa·s.Conclusions The research results are basically consistent with the field practice,which can provide effective reference for the layout of moveable elbow and the optimization of construction parameters in the fracturing field.
Objective Through reducing the total mass of the main container of LNG film tank,the development and market expansion of LNG storage facilities are promoted.Methods The basic geometric parameters of the main container of the film tank are designed,and the mathematical model of the tank and the required objective function are established.The stress of the tank in the full tank state is analyzed and calculated,and the basic geometric data is parameterized and the thickness of the tank wall is optimized by ANSYS software.The mathematical model of the dome is solved by using particle swarm optimization algorithm and MATLAB software programming.Results The optimal curvature radius of the dome is 28 000 mm,the minimum thickness of the tank wall is reduced by 0.50 mm,the total mass of the tank roof is reduced by 103 t,and the maximum thickness of the tank wall is reduced by 0.62 mm.Conclusions The optimized calculation results are qualified after the air pressure test,which has important reference value for the lightweight research and cost reduction of LNG film tank.
Objective Internal corrosion data governance is an important prerequisite for realizing the digital transformation of corrosion control and management business.At present,under the background of different sources of corrosion data,inconsistent data storage formats,and abnormal data,internal corrosion data governance is introduced which can efficiently solve the problems of disconnection between corrosion business management and data management,low standardization of data and difficult control of data quality.Methods This paper explored and analysed the current situation of internal corrosion data collection and management,the data governance process,and the data governance effectiveness in the surface gathering and transportation system of PetroChina Southwest Oil&Gasfield Company(hereinafter referred to as Southwest Oil&Gasfield),and combine the corrosion data and control management platform of Southwest Oil&Gasfield to show the storage situation of the internal corrosion data in the key blocks.Results (1)Through the formulation of internal corrosion data standards and management methods,the data entry format is standardized,the data sharing capability is improved,the data communication costs are reduced,and the timely,accurate,complete and standardized entry of various types of data is ensured;(2)abnormal data identification research is carried out on the internal corrosion data through the box diagram,and the identification accuracy rate reaches 88.3%,which realizes the efficient calibration of the internal corrosion data quality and improves the credibility of the corrosion data analysis and evaluation results;(3)based on the study of internal corrosion data entry,the data entry of 205 field stations and 233 pipelines was completed in 2022,it is helpful to fully display the corrosion situation of gas stations and pipelines in Southwest Oil&Gasfield;(4)based on the internal corrosion data after the treatment,the decision-making support research of corrosion data is carried out around corrosion prediction,risk assessment and overall pipeline corrosion control,and the effective utilization rate of data is improved.Conclusions The continuous promotion of internal corrosion data governance can support the digital transformation of corrosion control and management business in Southwest Oil&Gasfield,and lay a solid foundation for the construction of a digital integrated collaborative model of the entire business chain of Southwest Oil&Gasfield.
Objective The aim is to analyze the causes for the frequent abnormal rise of reactor pressure difference during hydrogenation evaluation test and put forward countermeasures.Methods X-ray fluorescence spectrometer(XRF),plasma spectrometer(ICP-OES),X-ray diffractometer(XRD)and other advanced instrument characterization and oil analysis methods were used to analyze the mud,raw oil and catalyst.Results (1)The top of the catalyst bed was full of mud,and the catalyst agglomerated in severe cases,which was the direct cause for the abnormal rise of pressure difference.(2)The mud was rich in elements such as Zn and Fe.(3)The pollution was more serious when the straight-run kerosene or diesel was stored in galvanized iron barrel,especially for the naphthenic straight-run diesel with high acid value and low viscosity,and the Zn mass fraction exceeded 100μg/g in short time,which was the fundamental cause for the abnormal rise of reactor pressure difference.Conclusions (1)For different petroleum fractions,suitable storage containers should be selected for sampling.(2)The storage container should be replaced in time and the independent hydrogenation protection section,demetallization section should be set for contaminated oil products during the evaluation test.(3)Special attention should be paid to the corrosion protection of acid-containing crude oil and its fractions during processing,especially naphthenic high-acid crude oil and its distillate.
Objective The leakage and diffusion rules of natural gas long-distance transportation pipelines caused by hydrogen blending under multi-factor coupling are explored.Methods Taking the West-East Gas Transmission Second Line Project as the research object,Fluent software is used to establish a two-dimensional plane leakage and diffusion model of the pipeline,and the effects of hydrogen blending ratio,leakage aperture,wind speed and atmospheric temperature on the leakage and diffusion of hydrogen blended natural gas are analyzed by single-factor and multi-factor coupling.Results As the proportion of hydrogen blending increases,the concentration and width of the methane diffusion region decreases,while the opposite is for hydrogen.The concentration and extent of hydrogen blended natural gas diffusion increase with the enlargement of leak aperture.With the increase of wind speed,the concentration of diffusion after the leakage of hydrogen blended natural gas increases,and the distribution gradually shifts downwind direction,while the diffusion height decreases.The influence of atmospheric temperature on the leakage and diffusion of hydrogen blended natural gas is not significant.The influence degree of different factors on the leakage and diffusion range of hydrogen blended natural gas pipeline is leakage aperture>wind speed>hydrogen blending ratio>atmospheric temperature.Conclusions Among the four influencing factors,the leakage aperture has the greatest influence on the leakage and diffusion of hydrogen blended natural gas pipelines.Therefore,the emphasis should be focused on preventing the leakage caused by pipeline cracking and perforation caused by corrosion and other factors of hydrogen blended natural gas pipelines.
Objective The aim is to verify the stability of the fixed bed carbonyl sulfur(COS)hydrolysis process developed in the laboratory and catalyst in long-term operation under factory gas quality conditions,so as to provide basic data for process package development,industrial device design and application.Methods A 6 000 m3/d natural gas fixed-bed COS hydrolysis technology field test device was independently designed and constructed.The stability of COS hydrolysis rate of the test device for more than 16 000 h continuous operation was investigated by using the natural gas from the outlet of the wet desulfurization absorber of the factory as the test raw material.Results The experimental results showed that when the reaction temperature was greater than 70℃and 100℃respectively,and the volumetric space velocity was less than 6 000 h-1,the COS hydrolysis rate can be stably greater than 98%and 99%.The process and catalyst achievements were applied to the upgrading and renovation project of product gas quality in natural gas purification plants.The industrial unit operated stably for over 5 600 h,and the 72 h performance evaluation results of the unit showed that the hydrolysis reaction temperature was 100-120℃,the carbonyl sulfur mass concentration at the reactor outlet was less than 0.3 mg/m3,and the average hydrolysis rate reached 99.69%.Conclusions The natural gas fixed bed COS hydrolysis technology developed in the laboratory is stable and reliable,with high catalyst hydrolysis rate.It can provide a technical solution for selective desulfurization of natural gas with COS as the main organic sulfur component and high content in domestic sulfur-containing gas fields.
Objective GB/T 17283-2014 is an important test method for measuring the dew point in natural gas and similar gases.At present,the standard does not stipulate the precision of the measurement results.This study determines the precision index of the dew point results,which provides the consistency evaluation basis for the users of the standard,and also can provide technical reference for revising the standard.Methods Using eight dew point instruments with different instrument manufacturers and models,the precision test is carried out through testing water-gas standard substance dew points under different pressure.Referring to the repeatability standard deviation of the determination results provided by the Russian standard GOST 20060-2021 Determination of water dew point temperature of natural gas,the precision index of the results of water dew point measured by cooling mirror condensate hygrometer was studied and determined.Results The limits of repeatability and reproducibility of measurement results are specified according to the measurement range of water dew point.The water dew point is-40.0℃≤tB≤-30.0℃,the limit of repeatability is≤2.0℃,and the limit of reproducibility is≤3.0℃.The dew point of water is-30.0℃
Objective The effects of different operating parameters and flue gas conditions on the separation efficiency of sulfur trioxide in flue gas by controlled condensation method(CCM)were studied to avoid the corrosion perforation of the device and the generation of high-salt sewage due to the high mass concentration of sulfur trioxide in flue gas.Methods The effects of different operating parameters and flue gas conditions on the condensation separation efficiency of sulfur trioxide in flue gas were studied by using the self-developed sulfur trioxide in flue gas control condensation efficiency evaluation device.Results The change of flue gas flow rate and sulfur trioxide mass concentration in flue gas had a significant effect on the condensation separation efficiency of sulfur trioxide.The introduction of quartz filter cotton at the end of the condensation system could obviously eliminate the influence of sulfur trioxide mass concentration change in flue gas on the condensation separation efficiency of sulfur trioxide.When the temperature of the flue gas sampling pipeline was higher than the dew point of the acid mist and the temperature of the condensation pipe was between the dew point of the acid mist and the dew point of the water vapor,the holding temperature of the flue gas sampling pipeline and the temperature change of the condensation pipe had little effect on the condensation separation efficiency of sulfur trioxide in the flue gas.The change of sulfur dioxide mass concentration in flue gas has little effect on the condensation separation efficiency of sulfur trioxide in flue gas.Conclusion According to the established sulfur trioxide condensation separation method,the separation efficiency for sulfur trioxide is greater than 95%.
