In different production stages of shale gas fields, various operating conditions and parameters vary widely, and the operating conditions of the triethylene glycol dehydration unit may deviate from the optimal range, which may easily lead to insignificant dehydration effects, which will affect normal production. The HYSYS software was used to simulate the process of a 300.0×104 Nm3/d shale gas triethylene glycol dehydration unit.The influence of the process parameters on the dehydration effect of the triethylene glycol such as the triethylene glycol circulation volume, the mass fraction of the triethylene glycol lean liquid, the flow rate of the feed gas into the tower, and the temperature of the feed gas into the tower,the operating pressure of the absorption tower, the temperature of the lean triethylene glycol liquid entering the tower, the total efficiency of the trays and the number of trays in the absorption tower were quantitatively analyzed.And the reasonable operating range of each process parameter was determined to achieve the best dehydration effect and meet the requirements of dry gas export. The results show that increasing the triethylene glycol circulation, lean liquid mass fraction, absorption tower operating pressure, total tray efficiency and number of absorption trays, as well as reducing the flow and temperature of feed gas into the tower, and the temperature of triethylene glycol lean liquid entering the tower are all helpful to improve the dehydration effect of triethylene glycol; increasing the temperature of the reboiler and the flow of stripping gas are beneficial to increase the mass fraction of the lean triethylene glycol. In addition, the HYSYS simulation calculation results are compared with the on?site production data. The results show that the two are basically consistent, which verifies the accuracy of the simulation calculation results, which can be used to guide actual production. The above research has certain guiding significance for improving dehydration efficiency and reducing investment cost.
Thermogravimetric analysis (TGA) was used to study the thermodynamic behaviors of pyrolysis and incineration of six typical components of MSW, and to explore the interaction between PVC which is the dioxin precursor and other components of MSW. The effects of different components on promoting or inhibiting the decomposition of PVC were quantitatively analyzed by combining the calculation of superposition rate of calculated curve and experimental curve and the fitting of kinetic parameters. The results show that adding paper, wood chips, cardboard and PE can reduce the formation of dioxin in PVC incineration process, and PE has the best inhibition effect on the formation of dioxin.
Titanium sulfate was used as a raw material, and a titanium oxide (TiO2) was prepared by direct high?temperature calcination in a muffle furnace. FT?IR, XRD, UV?Vis, SEM were used to characterize the structure of the catalyst. The results show that the direct calcination method can prepare anatase titanium dioxide and apply it to the oxidative desulfurization of dibenzothiophene. Using acetonitrile as the extractant and titanium oxide as the catalyst, the oxidation method was used to remove dibenzothiophene from the simulated oil. The effects of catalyst dosage, reaction temperature, n(H2O2)/n(S), and different sulfur compounds on the desulfurization effect were investigated, and the recycling performance of the catalyst was also investigated. Under the optimal desulfurization conditions, the desulfurization rates of dibenzothiophene, 4,6?dimethyldibenzothiophene, benzothiophene, and mixed diesel are 99.5%, 35.6%, 65.0%, and 53.4%. After the catalyst was recycled five times, the catalytic desulfurization effect was still as high as 90.3%.
A modified dicyandiamide?formaldehyde decolorizing flocculant was prepared using cyclohexylamine as modifier, and was used to simulate dye wastewater decolorization, flocculation and sedimentation experiments. The effect of reaction temperature, reaction time, material molar ratio and other factors on the decolorization performance of the modified flocculation was studied. The results show that reaction time is 3.5 h, reaction temperature is 85 ℃, material molar ratio of dicyandiamide to formaldehyde to ammonium chloride to cyclohexylamine is 1.00∶3.00∶0.50∶0.15, the decolorization rate 88.6% is achieved at a modified flocculant dosage of 100 mg/L. The decolorization and flocculation performance of the dicyandiamide?formaldehyde modified decolorizer is obviously better than that of the unmodified product.
This paper mainly studies a technical method for detecting the metal content in oil, that is, the combination of microwave digestion and ICP?AES detection technology. Studies have shown that the method has good applicability to the elements measured in the sample, and each element has a good linear correlation with its mass concentration, both greater than 0.999, and the detection limits of iron, manganese, and lead are 0.005 0 mg/L, 0.000 3 mg/L, 0.007 0 mg/L. The reliability of the data obtained by the method was verified by the spiked recovery experiment and the precision of the experimental method. The relative standard deviation of each element was less than 2%, and the recoveries were between 94.1% and 107.6%. Compared with the conventional single detection method, the detection method constructed in this paper has the characteristics of high sensitivity, fastness and high precision.
In order to study the salt precipitation law of the NaCl?Na2SO4?H2O ternary system at a temperature of 298.15 K, the Pitzer model was used to predict and calculate the activity coefficient and solubility of the system, and the variation of the activity coefficients of Na+, Cl- and SO
The bilirubin adsorption properties of three different types of carbon nanotubes (MW, LMW and SW) were studied. X?Ray Diffractomer (XRD) spectra shows that the diameters of the three carbon nanotubes are ranked as LMW>MW>SW. Scanning Electron Microscopy (SEM) and Brunner Emmet Teller (BET) show that MW has the best dispersion, a larger specific surface area, the largest pore size and a maximum pore volume. The bilirubin adsorption results show that the carbon nanotubes have the maximum bilirubin adsorption capacity when the temperature is set as 37℃ and the adsorption time reach 40 min. When the concentration of bilirubin is higher than 0.5 g/L, the bilirubin adsorption capacity of MW carbon nanotubes is the largest, and the maximum adsorption capacity of bilirubin reach 208 mg/g membrane. With increasing ion strength, albumin mass concentration, and under alkaline conditions, increasing pH does not benefit the absorption of bilirubin in the buffer solution. Compared with the conventional adsorbents, all the three carbon nanotubes show the excellent performance of short adsorption time and large adsorption capacity for bilirubin, which provide the experimental basis for the preparation of polymer microfiltration membranes blending with carbon nanotubes and its adsorption of bilirubin.
The sol?gel method was used to modify the multi?walled carbon nanotubes, so that SnO2 was combined with MWCNTs and doped with Cu ions. The samples M, M+Cu, M+Sn, and M+Sn+Cu were characterized by SEM, XRD, and FTIR. The surface microstructure was analyzed. The static adsorption method was used to measure the saturated adsorption capacity of different samples to VOCs. The VOCs gas volume concentration, temperature, and effects of metal doping were analyzed respectively. The results show that the saturation adsorption capacity of the four adsorbent samples is linearly related to the volume concentration and temperature of VOCs, and the larger the value of the two samples, the smaller the saturation adsorption capacity; at normal temperature (25 ℃) and normal pressure, MWCNTs adsorption capacity is almost 0, the saturation adsorption capacity of M+Cu is slightly smaller than M+Sn, and the adsorption capacity of M+Sn+Cu is about twice of M+Sn, up to 37.4 mg/g.
The flexible control operation technology is used to improve the oil production process of the beam pumping system, and the use of an elliptical speed drive motor is one of the solutions to realize this technology. In order to explore the law of movement of the valve ball in the pump with elliptical velocity drive and conventional circular velocity drive, the delayed opening of the valve ball under two working conditions was analyzed,and a fluid?solid coupling simulation model was established to analyze the force law of the fixed valve. The difference of the valve ball movement under the two working conditions was obtained. Finally, the correctness of the theoretical analysis was verified by the bench experiment. The results show that the rate of opening and reaching the maximum lift of the valve ball under the elliptical velocity drive is slower than that of the conventional circular velocity drive, but it seats faster, which can effectively prevent leakage and achieve the purpose of improving oil recovery efficiency.
The weak magnetic stress detection technology supports non?contact online detection of stress damage. It has great application potential in the field of long?distance oil and gas pipeline stress detection technology. However, as the weak magnetic signal is weak and easy to be interfered by the external environment,the detection result is prone to deviation.In order to strengthen the detection ability of weak magnetic signals, based on the microscopic characteristics of ferromagnetic materials, a weak magnetic stress detection model under an external magnetic field was established, and the change law of weak magnetic signal strength with the increase of external magnetic field strength and applied stress was obtained.The excitation characteristics of the external magnetic field to the weak magnetic stress detection signal were described,and a systematic experimental study was conductd.The results show that the tangential peak value and the normal zero point of the weak magnetic signal are located in the center of the stress concentration area, and do not fluctuate with the change of the stress and the external magnetic field.The tangential peak value and the normal peak?peak of the weak magnetic signal increase with the increase of the external magnetic field and stress. As the external magnetic field increases, the excitation effect of the external magnetic field on the weak magnetic stress detection signal increases first and then decreases.
The effect of the compound system of IAEC?1306H (Isotridecyl alcohol polyoxyethylene ether carboxylic acid solution), alcohol solution and alkali agent on the viscosity of heavy oil was studied. The results show that under the same mass fraction conditions, maltitol has better viscosity?reducing effect on heavy oil than sorbitol, and NH3·H2O water has better viscosity?reducing effect on heavy oil than IAEC?1306H and alcohol solution.The mmonia water and IAEC?1306H have similar on the viscosity reduction effect of on heavy oil.With the increase of the volume fraction of NH3·H2O and the mass fraction of IAEC?1306H, the viscosity of the heavy oil gradually stabilizes.In the binary compound system, the binary system formed by compounding sorbitol and maltitol with IAEC?1306H respectively has the same viscosity reducing effect on heavy oil. And due to the nature of the alkali agent, the compounding of the alkali agent and IAEC?1306H is more conducive to the viscosity reduction of heavy oil.In the ternary compound system, the ternary system formed by the combination of NH3·H2O, maltitol and IAEC?1306H has a better viscosity?reducing effect on heavy oil, with a viscosity?reducing rate of more than 96%, and the dosage of NH3·H2O, IAEC?1306H, and maltitol are used less.
In order to reduce the heat resistance and improve stability of convective heat transfer in liquefied natural gas(LNG) vaporizer, the flow and heat transfer processes of supercritical pressure LNG were analyzed by numerical method in a vertical tube. The influence of heat fluxes and flow directions on heat transfer characteristics was discussed, and the effects of the flow field , the temperature field , and the turbulent kinetic energy changes on the heat transfer instability were investigated.The results show that the heat transfer of supercritical methane in vertical tube is unstable,at high heat flux density, the inner wall temperature and the average temperature of the pipe are unstable and and shock in the heat transfer deterioration range; At the low heat flow density , the local convection heat transfer coefficient is unstable , and it shocks in the heat transfer deterioration range; Under the same heat flux density, the heat transfer instability of upward flow is greater than that of downward flow, because the thermal influence of upward flow is greater than that of downward flow. The gas?like film is the main reason of heat transfer instability.
The Finite Element Method was used to study the flow field of different screw combination sections of single?screw extruder. The Polyflow software was used to calculate the pressure field, shear rate field, velocity vector, mixing index and other parameters of the flow field of ordinary screw, ordinary screw and pineapple head combined screw, ordinary screw and pin combined screw. The post?processing results were compared and analysed.The results show that the ordinary threaded screw can provide a greater axial velocity for the fluid; although the pineapple head screw has greater resistance, the more oblique section design can provide better axial and circumferential velocity for the fluid; the barrier effect of the screw causes a part of the fluid to flow back. The three new types of screws can effectively stretch and shear the fluid while providing a good linear velocity for the fluid to make its dispersion and mixing more uniform. According to the analysis of the curve results, the mixing effect of pin?screw is the best.
Taking the 6?PTRT parallel as the research object, the pose error model of 6?PTRT parallel robot is established, the closed?loop vector method of single branch chain is used to establish the error equation based on its input and output relationship. According to the pose error model of 6?PTRT parallel robot,the mechanism error is converted into the drive rod error,the influence of the error parameters of each drive rod length on the output pose error is analyzed by using MATLAB software;the objective function of pose error correction of 6?PTRT parallel robot is established, and the adaptive weighted particle swarm optimization algorithm based on shrinkage factor is used to optimize the error parameters of each drive rod, modify the terminal pose, and improve the kinematics accuracy, which provides a theoretical basis for the dynamics, pose calibration and trajectory planning and control of 6?PTRT parallel robot.
Due to the interference of noise, periodicity, nonlinearity and nonstationarity, most of the existing causal analysis methods are often unreliable and inaccurate in industrial process control systems. In order to improve the plant-level oscillation source location performance, a causal relationship detector based on improved convergence cross mapping was proposed. First, the adverse effects of noise and periodicity on causality detection were pointed out. Then, the empirical mode decomposition (EMD) and the trend fluctuation analysis were combined to realize the oscillation signal denoising. The periodicity of the signal was effectively removed by singular spectrum analysis. The denoising and periodicity?removing signal was analyzed by using convergent cross mapping, and then the source of plant level oscillation could be accurately located. Simulation results show that, the proposed method can improve the accuracy of plant?level oscillation source location in process control system.
As natural gas accounts for an increasing proportion of energy consumption, how to accurately predict the future natural gas consumption is of great significance to the rational planning of natural gas. For this problem,a short?term natural gas load forecasting model based on wavelet transform and deep learning was proposed. First,the collected natural gas load was decomposed by using different wavelets , and then normalized it.Secondly, the data wes trained and predictd by using the deep learning algorithm Long Short?Term Memory (LSTM); then the predicted data was separately integrated by using wavelet reconstruction.Finally, the average absolute percentage error, average absolute error and root mean square error were used as evaluation indicators to evaluate the prediction results of different wavelets, and the optimal order and number of layers of the optimal wavelet were calculated.The examples show that the 22nd?order 6th layer of Fk wavelet transforms has higher prediction accuracy than other wavelets transforms and direct use of LSTM for prediction.
