Pushing coke is an important process in coke oven production. In the process of pushing coke, under the three-body contact state of steel, coke powder, and refractory brick, coke powder plays an important role in lubrication. In this article, a study on the macro- and micro-behavior and mechanism of coke powder lubrication is carried out through tribological tests. The results show that in the process of sliding friction, coke powder plays a role of lubrication through forming a powder layer and shearing occurred inside the powder layer. The load keeps at 5 MPa, under the lower velocity, the powder layer is thinner and delamination occurred in local position. While under the higher velocity, the coke powder can form a compact and complete powder layer and exhibit better lubrication characteristics. However, when the velocity increases to 0.52 m/s, the continuous powder layer is not formed, so the friction coefficient is higher, the frictional surface wears seriously and results in vibration to occur. The velocity keeps at 0.40 m/s, and the powder layer inclines to deteriorate under higher load. When the load increases to 20 MPa, a part of the powder layer is damaged, and severe wear occurs on the surface.
18 June 2018 in Advances in Mechanical Engineering
Serious vibrations can occur in the coke pushing ram in the coke pushing process and may directly affect the regular production of coke oven, in order to avoid vibration, it is necessary to study the vibration characteristics of coke pushing ram. In this article, the coke pushing resistance is derived via the coke pushing current and a mathematical model of coke pushing ram in the coke pushing process is established to study the vibration mechanism of coke pushing ram. The results indicate that in the low-velocity and heavy-load coke pushing process after the slipper enters the carbonization chamber, the coke pushing velocity is less than the critical velocity, which indicates that the stick-slip vibration occurs in the coke pushing ram, and the factors affecting the coke pushing ram stability mainly include the difference between the static and dynamic friction coefficients, stiffness, and damping. The results are validated by numerical simulation and experiment test.
As an environmental semiconductor material, TiO2 has important applications in the fields of environmental protection and water treatment. The preparation of P25 particles into nano-functional material films with a high specific surface area has always been a bottleneck limiting its large-scale application. In this paper, a one-step method of preparing TiO2 nanocomposites by doping carbon nanotube (CNT) and carbon quantum dots (CQD) with tetrabutyltitanate and P25 TiO2 under ultrasonic radiation is proposed to synthesize a novel antifouling material, which both eliminates the bacterium of Escherichia coli and shows good photoelectric properties, indicating a great value for the industrial promotion of TiO2/CNT. This mesoporous composite exhibits a high specific surface area of 78.07 M2/g (BET) and a tested pore width range within 10–120 nm. The surface morphology of this composite is characterized by TEM and the microstructure is characterized through XRD. This preparation method can fabricate P25 particles into a nano-functional material film with a high specific surface area at a very low cost.
8 February 2024 in Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
In view of the problems that the mechanical seal for the water pump is prone to deformation, friction and wear, and loss of sealing performance in the process of use, taking the temperature change of end surface as the research entry point, the temperature distribution, stress and strain diagram of rotating ring, and stationary ring are obtained by thermal-stress coupling simulation. The temperature change of stationary ring is studied by the experiments, and the friction state of end surface of rotating ring and stationary ring are observed. The results indicate that the test temperature of stationary ring is slightly lower than simulation temperature, which is related to the thermocouple fixed on the side of the stationary ring for temperature measurement. In addition, comparing the micro morphology of end surface of rotating ring before and after the experiment, it is found that there is significant plastic deformation on the inner diameter of rotating ring, which is related to the stress generated by the thermal-mechanical coupling of inner diameter of rotating ring exceeding the material limit, consistent with the simulation results.
By introducing the coke powder into the friction pair, the effects of load and temperature on the lubricity of coke powder at the frictional interface are studied. Before the test, the microcrystalline structures of coke powder at different temperatures are characterized by X-ray diffraction (XRD). After the test, the friction surfaces are observed by electron microscope and energy spectrum, the oxide compositions of friction surface are characterized by XRD, and the lubrication mechanism of coke powder is investigated. The results show that at RT (room temperature), as the load increases, the forming of the powder layer gradually deteriorates. When the load is 5 MPa, at a low temperature, the powder layer is thicker, and the coke powder exhibits better lubricity. In contrast, at a high temperature, affected by the temperature, the lubricity of coke powder declines, and the friction coefficient is higher.
In order to find out the key factor affecting the stability of coke pusher, the structural deformation and vibration mode parameters of the coke pusher are obtained by thermal-structural coupling simulation and thermal-modal coupling simulation, and the vibration signals in the process of coke pushing are collected for time-domain analysis and time-frequency analysis. The results show that the coke pusher vibrates after being affected by the friction, and the vibration frequencies are close to the natural frequencies; that is, the friction has a great influence on the stability of the coke pushing rod. In addition, affected by the friction, the deformation of the bottom of coke pusher is the largest, resulting in unstable contact between the bottom of coke pusher and the ground of carbonization chamber, which is very easy to cause vibration.