Template agent is an essential part in the synthesis of molecular sieves, which has great influence on the physical properties and catalytic properties of molecular sieves. SAPO?34 molecular sieve was synthesized by hydrothermal method using stainless steel tube as crystallization vessel. The effect of PEG?800 addition on crystallinity, morphology and acidity of molecular sieve was investigated, and its MTO catalytic performance was evaluated. The results show that the molecular sieve samples synthesized with TEAOH & PEG?800 as the composite template agent are thin plate?like, the crystallinity and acidity are suitable, and the longest catalytic life is 340 min. When the methanol conversion is above 95%, the selectivity of diolefins is up to 84.0%. It is also found that the thinner the crystal thickness of the lamellar molecular sieve, the better the catalytic performance.
The hydrogenation catalysts with Mo and Ni as active centers were modified with macroporous nano?alumina as carrier and iron as auxiliary agent, and Fe?Mo?Ni and Fe?Ni catalysts were prepared by secondary nano?self?assembly method respectively. The experimental results show that the iron modified catalysts MNF?70C and NF?70C have bimodal pore structure, the larger most probable pore diameter is 50.0 nm and 40.0 nm respectively, and the smaller most probable pore diameter is 5.5 nm. It can be seen that under the action of complexing agent and promoter Fe, Fe, Mo and Ni in MNF?70C catalyst form a large number of nano self?assemblies in the form of metal bonds on the inner and outer surfaces of macroporous alumina, which are more evenly dispersed and have more pores suitable for hydrogenation reaction. The pore size distribution of MNF?70C and NF?70C catalysts in the range of 6.0~60.0 nm reached 78.05% and 72.80% respectively. It shows that the addition of structural assistant iron improves the dispersion of active metals, so as to effectively improve the pore size distribution of the catalyst. The characterization analysis of CO adsorption, H2?TPR TEM and XPS further shows that the Fe modified catalyst has linear adsorption for CO, its reduction temperature is low, and it has been evenly dispersed in the form of nanoparticles, with more catalytic active centers, indicating that this kind of catalyst has better hydrogenation catalytic activity. Because Fe is cheap, the addition of additives can improve the quality of the oil after hydrogenation or reduce the amount of catalyst active metal, so as to reduce the cost of synthetic catalyst, which is suitable for the development of heavy oil hydrogenation catalyst for industrial application.
OA?ZnCl2/SG supported catalyst was synthesized by sol?gel process using octanoic acid?zinc chloride deep eutectic solvents (OA?ZnCl2 DESs) as additive. The structure of the catalyst was analyzed by infrared spectroscopy, X?ray diffraction, N2 adsorption?desorption and scanning electron microscopy. The performance of oxidative desulfurization was studied by using OA?ZnCl2/SG as adsorbent and catalyst, and hydrogen peroxide as oxidant. The loading dose of DESs, reaction temperature, n(H2O2)/n(S) ratio, the amount of catalyst and the effect of different sulfides on desulfurization rate were investigated. The results show that the desulfurization rate of the catalyst reaches 95.6% under the optimal conditions, and after 5 cycles, the desulfurization rate drops to 89.7%.
The influence of sulfate reducing bacteria (SRB) and CaCO3 scale layer on the corrosion behavior of 20# steel was studied by laboratory simulation experiment. The uniform corrosion rate was studied by corrosion weight loss method.The corrosion electrochemical behavior of 20# steel in the injected aqueous solution was studied by electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP). The morphology and composition of corrosion products on the surface of 20# steel were analyzed by scanning electron microscopy (SEM), EDS and Raman spectroscopy. The pitting pit depth of 20# steel was analyzed by laser confocal microscopy (CLSM). The results show that there is a synergistic effect between SRB and CaCO3 scale layer. The porosity of CaCO3 scale layer and the anaerobic environment under the scale layer provide convenient conditions for the adhesion and growth of SRB. The inoculation of SRB can promote the uniform corrosion and local corrosion of 20# steel under the CaCO3 scale layer.
With the development of artificial intelligence technology and big data Internet technology, the pipeline leak detection technology is developing in the direction of intelligence. Based on the classification of continuous pipeline leak detection technology and discontinuous pipeline leak detection technology, this paper introduced the principles of various leak detection methods, summarized and analyzed the research status of long?distance oil pipeline leak detection technology at home and abroad. The application of combined oil pipeline leak detection and location technology in long?distance oil pipeline detection was prospected.
The wet gas gathering pipelines will produce natural gas hydrate with the condition of high pressure and low temperature, which may cause blockage of pipelines or failure of key control equipment. Adding alcohols Thermodynamic?Inhibitor(THI) is one of the feasible proposals to prevent hydrate formation. If the amount of THI is poured excessive, the costs of procurement, transportation, storage and water treatment will increase in large quantities. Therefore, it is significant to determine the minimum dosage of THI based on a reasonable safety margin. Calculation of THI injection dosage based on empirical formula method and phase equilibrium software, without considering the effect of flow. In this paper, a method coupling of phase equilibrium and flow was used to optimize the injection dosage of THI. Based on the OLGA component tracking model, the temperature, pressure and THI concentration along the line are tracked, and then the THI dosage was predicted more accurately. Taking the gas gathering pipeline of land and submarine as an example, different calculation methods were compared. The results show that the new method can reduce the THI consumption by more than 10%.
As the main weighting agent of oil?based drilling fluids, barite has many problems with high?density oil?based drilling fluids. In order to explore the applicability of micro?manganese mineral powder in oil?based drilling fluids. The particle size distribution and microscopic morphology of barite and micro?manganese ore powder were analyzed by laser particle size analyzer and scanning electron microscope. The differences in rheology, water loss and wall?building, lubricity, settlement stability, and reservoir protection performance between barytic petroleum?based drilling fluid system and micromanganese slag oil?based drilling fluid system were studied. The results show that under the condition of low density, the difference between the micromanganese ore powder system and the barite system is small; under high density conditions, the micro?manganese ore powder system has low viscosity and high cutting, the viscosity coefficient of the mud cake is less than 0.10, the sedimentation density difference is less than 0.03 g/cm3, and the permeability recovery rate after acid dissolution is higher than 95.00%. Its rheology, lubricity, sedimentation stability, and reservoir protection performance are better than the barite system, but compared with the barite system, the micro?manganese ore powder system has a large water loss and poor mud cake quality. It is recommended to compound the micro?manganese ore powder with a weight Spar to improve the water loss of the system. The research results fully reveal the difference in performance between the micro?manganese mineral powder oil?based drilling fluid system and the heavy crystal oil?based drilling fluid system, and provide support for the micro?manganese mineral powder to improve the performance of high?density oil?based drilling fluids, and also increase the weight of high?density oil?based drilling fluids. It also provides a new development direction for the application of ultra?high density oil?based drilling fluid weighting agents.
Sinopec Dalian Research Institute of Petroleum and Petrochemicals developed the "low temperature diesel absorption" VOCs treatment device for an aromatics and styrene tank farm. However, the waste gas volume sucked into the liquid ring compressor is always unstable. In this paper, a new automatic bleed gas volume control scheme of liquid ring compressor was adopted, the optimal control parameters were obtained by designing the bleed air control scheme for the compressor motor frequency and the opening of the return valve of the liquid ring compressor according to the pressure on the pipeline connected to the tank area. The results show that this technology can meet the requirements of energy saving and consumption reduction while ensuring that the exhaust gas is discharged up to the standard, and take into account the long?term stable operation of the equipment.
Gasifier is the main equipment of CWS gasification system. In order to study the influence of gasifier failure on gasification system, a dynamic risk assessment method based on dynamic Bayesian network and risk matrix is proposed in this paper. Taking the gasifier failure as an example, the dynamic Bayesian network model of the gasifier was first established, and the prior probability of the root node event was calculated by combining the fuzzy evaluation method, and the dynamic Bayesian network was introduced to calculate the posterior probability. Then, based on the principle of analytic hierarchy process (ahp) and Borda, a comprehensive risk assessment for gasifier failure was established, and maintenance factors were introduced to predict the risk trend of the gasifier after maintenance and draw a dynamic risk matrix. The results show that the risk of the system decreases after the maintenance factor is introduced, which proves that the maintenance factor has a positive effect on the system and guarantees the production capacity of the system
Based on the limitation of the eccentric twin screw extruder's own structure, a new type of eccentric three screw extruder was designed. Polyflow software was used to analyze the pressure field, shree velocity field, velocity vector field, mixing index, separation scale, average mixing efficiency, logarithmic stretching and other parameters. The flow and mixing mechanism of the eccentric tri?screw extruder were studied and compared with that of the eccentric twin?screw extruder. The results show that under the same conditions, the stretching and folding effect of the eccentric three?screw extruder is better, and the mixing efficiency is higher than that of the eccentric twin?screw extruder, which provides a theoretical basis for further exploring the chaotic mixing mechanism and optimizing the eccentric multi?screw extruder.
This paper proposes a model?free control protocol design method based on off?policy reinforcement learning for solving the optimal consensus problem of heterogeneous multi?agent systems with leaders. The dynamic expression of local neighborhood error is complicated for the heterogeneous multi?agent systems because of its different system state matrices. Compared with the existing solution of designing observer for distributed control of multi?agent system, the method of solving global neighborhood error state expression proposed in this paper reduces the complexity of calculation. Firstly, the dynamic expression of global neighborhood error of multi?agent system constructed from augmented variables is established. Secondly, the coupled Bellman equation and HJB equation are obtained through the value function of quadratic form. Then, the Nash equilibrium solution of the multi?agent optimal consensus is obtained by solving the optimal solution of the coupled HJB equation, and the Nash equilibrium proof is given. Thirdly, an off?policy Q?learning algorithm is proposed to learn the Nash equilibrium solution of the multi?agent optimal consensus. Then, the proposed algorithm is implemented by using the critic neural network structure and gradient descent method. Finally, a simulation example is given to verify the effectiveness of the proposed algorithm.
This paper studies the formation containment control algorithm for multiple spacecraft systems under actuator and sensor faults. Firstly, the orbit dynamics of the spacecraft is modeled and linearized. Then, an adaptive descriptor observer is designed to obtain the estimated values of system states as well as actuator and sensor faults. By adjusting the nonsingular matrix, the performance of the observer can be improved and the observer error can converge near the origin. Based on the estimated system states and actuator faults, formation containment controller is designed. The sufficient conditions for the convergence of formation error and observer error are obtained through Lyapunov analysis. Finally, the system performance under the designed algorithm is verified by a simulation example.
In this work, the inner and outer loop control strategy is adopted for the unmanned aerial vehicles (UAVs) formation system. Firstly, a sliding mode control method based on memory event?triggered mechanism (METM) is proposed for the position subsystem under delay and disturbance. The second?order model is established for each UAV, and the leader?follower framework is adopted to realize the desired flight formation. Secondly, an adaptive METM is proposed to alleviate the transmission burden, in which control input feedback is introduced. For the resulting communication delay of the control input in the proposed METM and the external disturbance to the system, a sliding mode controller is designed, which maintains desirable control performance and solves the influence of communication delay and bounded disturbance to a certain extent. Thirdly, the stability of the closed?loop system is proved by applying Lyapunov theory and H∞ control theory, and a method that facilitates solving controller gain and triggering parameter through a series of linear matrix inequalities (LMIs) is proposed. Moreover, based on the obtained virtual control quantity, a tracking controller is designed for the attitude subsystem. Finally, a simulated example is exploited to verify the effectiveness of the proposed method.
With the increasing complexity of networked power systems, traditional control schemes are difficult to meet the actual needs. Bandwidth constraints, network security and actuator saturation have become important factors affecting the stability of power systems. An improved event trigger mechanism was introduced to improve the utilization rate of bandwidth resources for the problem of bandwidth resource limitation, and a new mathematical model of power system under deception attack and actuator saturation was constructed. Based on this number model, the sufficient conditions for the asymptotic stability of the power system were obtained by Lyapunov theory, and the design scheme of the security controller was given by using linear matrix inequality technique. Finally, an example of power system was given to illustrate the effectiveness of the proposed scheme.
