加工原糖过滤系统用密压机增稠过滤、真空吸滤机脱泥

我厂1987年4月开始原糖加工,一碳汁过滤利用现有8台62m^2密压机全汁过滤。生产过程中,密压机通常在0.7MPa压力下操作,过滤能力不足,后工序等糖浆煮糖、滤泥含糖高,糖份损失大。翌年,根据生产存在的问题投入两台40m^2真空吸滤机,过滤一碳汁采用密压机增稠过滤,真空吸滤机脱泥的工艺流程。通过近两期的生产实践成效显著。

密排缸压机框式机架强度的简单计算

载荷形式的确定和框架的假设 1.框架结构。压板上举式压机的框板强度计算在压机设计中非常重要,计算方法也较多,一般将油缸化成集中力。我们认为,上述假设只能适用于油缸支承盘长度a和两油缸中心距d之比a/b<0.8的情况(如图1)。对于a/b>0.8时,(如我厂生产的YB8—1800型绝缘板热压机和FCY_(10)—2000型复合材料压机,其a/d=0.87)对于这种情况,把油缸作为均布载荷处理要更为合理(如图2)。应力测试结果已经证明了这一点。 2.框式机架是一个封闭的多次静不定空间框架体,其准确计算是很困难的。为了简化计算,作如下假设:

Design and Fabrication of Hybrid Piezomotor Applied in Precision Positioning Devices

The motor’s configuration is designed and the dynamic analysis equations based on its simplified model are deduced. A testing system utilizing grating is set up to test this new motor, and the theoretical movement principle for the motor is proved by experiments. The pulse waveforms are applied to drive the motor to move in steps. The motor has a displacement resolution of 10 nm and a maximum velocity of 0.6 mm/s. It can drive a 200 g slider whose range is 20 mm. A one-dimensional precision positioning platform is fabricated by using the new hybrid piezoelectric motor. The prototype is made up of two servomotors and two piezoelectric motors, which are controlled automatically by a computer. The positioning range of the platform is 10 cm.

Fabrication of FeAl/TiC composites through reactive hot pressing

FeAl/TiC composites were fabricated by reactive hot pressing blended elemental powders. The TiC content was varied from 50% to 80%(volume fraction) and the aluminum content in the binder phase was changed from 40% to 50%(mole fraction). The effects of these compositional changes on the densification process and mechanical properties were studied. The results show that with the increase of TiC content, densities of the composites decrease due to insufficient particle rearrangement aided by (dissolutionreprecipitation) reaction during hot pressing. Closely related with their porosities and defect amount, the hardness and bend strength of the composites show peak values, attaining the highest values with TiC content being 70% and 60%, respectively. Increasing the aluminum content is beneficial to the densification process. But the hardness and bend strength of the composites are reduced to some extent due to the formation of excessive oxides and thermal vacancies.

Impact of Mechanical Aeration on the Soil Resistance to Penetration and Density of Grassy Sward

The aim of this study was to analyze the effects of mechanical perforation of a golf course grassy sward, subject to maintenance machinery traffic and golf players trampling on its compaction and density. The evolution of soil compaction state after aeration was also conducted in four stages of measurement. This operation aims to improve the structure and soil texture, which is also called ＂perforation＂ or ＂coring＂. The taken cores leaving on the soil holes of adjustable depth and density （350 holes/mE） are made with an aerator machine called Vertidrain. Soil resistance to penetration and density were determined at the initial state before aeration as well as 10, 20, and 30 days after aeration. Compared to the initial state, the results show that mechanical aeration greatly affects the grassy sward ground by reducing its resistance to penetration as 35% and 43% decrease in penetration resistance were noticed at 5 cm depth l0 and 20 days after aeration, respectively. Also, resistance to penetration decreased by 41% and 48% at 15 cm depth during the same two periods of time with a relatively constant moisture content. However, soil resistance to penetration at 5 and 15 cm depths only decreased by 21% and 26%, respectively. Regarding the soil density measured after aeration, a significant improvement at the 1% level with the method of variance analysis was observed compared to that at the initial state （e.g. 1.33 g·cm^-3） Indeed, the density was 1.29, 1.26 and 1.30 gcm^-3 10, 20 and 30 days after aeration, respectively.

Vibration compaction characteristics of rock filling embankment

The dynamic model experiment of the rock filling embankment was carried out to investigate the vibration compaction mechanism. The rock filling materials were compacted by the plate-vibrated compactor, and the characteristics of the rock filling materials, such as settlement, pressure change and response waveform, were measured by the dynamic earth pressure gauge and aceelerometer. Moreover, a new method for detecting the compactness of the rock filling embankment was proposed based on the maximum dry density and modulus of deformation. The results show that the process of vibration compaction includes compact, elastic deformation and loose stages, and the vibratory pressure transfers to the surroundings from the vibration center in non-linear rule. Furthermore, the test results obtained by the present method are basically in agreement with those obtained by the traditional method, and the maximum relative error between them is about 0.5%.

Study on seal improvement and rotor thrust control of centrifugal compressor

Fluid pressure variations due to process fluctuations or balance drum seal degradation can result in rotor thrust increasing that may jeopardize thrust bearing and compressor’s reliability. Also, the leakage flow through balance drum seal can seriously affect the efficiency of compressor. A method that can improve both the efficiency and reliability of centrifugal compressor is presented. The method focused on rotor thrust control and balance drum seal upgrading. The low leakage feature of Dry-Gas-Seal（DGS）, high reliability of labyrinth, and the feasibility of upgrading existing structure are taken into account at the same time to design a combined labyrinth-dry gas seal system on the balancing drum. Based on the combined seal system, a Fault Self-Recovering（FSR） system for the fault of rotor shaft displacement is introduced to assure the safety and reliability of centrifugal compressor. The modern Computational Fluid Dynamics（CFD） is used to validate this envision. The numerical result and relevant information indicate that the combined sealing system could improve the efficiency of the centrifugal compressor by about 4%.

Study on hydrostatic gas lubricated non-contacting mechanical seal

The principle and characteristics of hydrostatic gas lubricated non-contacting mechanical seal （HSGLNMS） are introduced. The flow field of the gas film is established by numerical analysis of end faces of HSGLNMS. The distribution of gas film pressure and seal performance parameters inclu- ding opening force and leakage are obtained. Influence of operating parameters and sealing configu- ration on the sealing performance is studied. HSGLNMS has been designed and manufactured. Its working film thickness and leakage are measured to verify the theoretical analysis. The investigation results show that HSGLNMS demonstrates good speed adaptability, which means that the seal runs successfully with both low and high speed, showing excellent performance. The seal can be regula- ted and controlled online ; the opening force will not be raised greatly with the increasing of the num- ber of throttle orifices, but the leakage of seal increases apparently ; the uniform pressure groove im- proves the sealing performance, for example, opening force and stiffness are raised obviously. While leakage is reduced. Finally, the theoretical analysis is verified by experiment.

Numerical Analysis of the Thermal Behavior of a Hermetic Reciprocating Compressor

A numerical model to predict the temperature field in a hermetic reciprocating compressor for household refrigeration appliances is presented in this work. The model combines a high resolution three-dimensional heat conduction formulation of the compressor＇s solid parts, a three-dimensional CFD （computational fluid dynamics） approach for the gas line domain and lumped formulations of the shell gas and the lubrication oil. Heat transfer coefficients are determined by applying CFD to the gas line side and correlations from the literature on the shell gas and oil side, respectively. The valve in the gas line simulation is modelled as a parallel moving fiat plate. By means of an iterative loop the temperature field of the solid parts acts as boundary condition for the CFD calculation of the gas line which returns a cycle averaged quantity of heat to the solid parts. Using an iteration method which is based on the temperature deviation between two iteration steps, the total number of iterations and consequently the computational time can be reduced. The loop is continued until a steady-state temperature field is obtained. Calculated temperatures of the solid parts are verified by temperature measurements of a calorimeter test bench.

Experimental Study on Frictional and Sealing Performances of Packing Rings in an Oil-free Gas Compressor

To enhance the reliability and to extend service life of packing rings, tribological and sealing perfor- mances are investigated based on the experimental results. Friction force, leakage rate and power consumption of three materials of pressure packing seals are measured in a refitted vertical gas compressor. The rings are made of common filled polytetrafiuroethylene （Filled PTFE）, PTFE reinforced with 30% mass fraction carbon fiber （30%CF^PTFE）, and carbon-carbon composites infiltrated with PTFE （C/C＋PTFE）, respectively. It is found that packing rings will periodically vibrate with the periodic vibration of pressure packing after the travel direction of motion abruptly turns to the reverse direction. Furthermore, the amplitude of vibration slows down with the increasing crank angle. Approximate value of friction force is available by multiple-point fast Fourier transformation （FFT） employed to process the experimental results by reducing the impact of vibration to a great extent. Of three materials of rings employed in experiments, Filled PTFE presents minimal leakage rate accom- panied with maximum power consumption. And 30%CF＋PTFE exhibits minimum friction power and moderate leakage rate. As for C/C＋PTFE, its high mechanical and thermal properties are favorable factors to enhance the ability of operating under high pressure and velocity and to improve the wear resistance. Unfortunately, this also leads to a large leakage rate. Comprehensive consideration should be taken into to evaluate the availability, reliability and service life for a type of packing ring under dry running conditions.

Implementation strategies for high accuracy grinding of hydrodynamic seal ring with wavy face for reactor coolant pumps

Large size mechanical seals are one of the most important components used in reactor coolant pumps.However,the hydrodynamic seal rings with wavy face are difficult to machine due to their high hardness and high form accuracy demand.In order to solve this difficult problem,a novel four-axis linkage grinding method using a cup wheel to process the hydrodynamic seal rings by line contact was proposed.A preliminary study indicates that the form error of the ground seal ring surface is extremely sensitive to different linkage relations of the four axes.By taking the center height of the cup wheel and the laws of motion along the X-axis,Z-axis,B-axis and C-axis as control variables,their effects on the principle form error of the ground surface are evaluated.Six implementation strategies are proposed to reach lower principle form errors.It is found that the minimal principle form error is only 9.64 nm and hence its influence on the ground seal ring shape can be neglected in designing an ultra-precision grinding machine.In addition,the results indicate that the position accuracy of the X-axis at the microscale is acceptable no matter which implementation strategy is selected.This study is expected to serve as a theoretical basis for design and development of the four-axis ultra-precision grinding machine.

4H-Si C monolithic Darlington transistors with slight current gain drop at high collector current density

Profit from high current gain features, 4 H-Si C power Darlington transistor has the capacity for handling high current transmission. In this paper, monolithic Darlington transistors were fabricated using a simultaneous formation process for both n-type(emitter) and p-type(base) ohmic contact. The isolated device shows current gain of 1061 and 823 with collector current density(JC) increasing from 200 to 800 A/cm2, exhibiting a slight current gain drop at high JC. By extracting the interface state density(Dit) between Si O2 and p-type 4 H-Si C, it is found that this advantage owes to the improvement of the shallow bulk minority carrier lifetime in base region. Furthermore, ISE-TCAD(technology computer aided design) simulation was carried out to study the relationship between base minority lifetime and the current gain, from which the total base minority lifetime is estimated to be 48 ns. The open base breakdown voltage(BVCEO) is 850 V at a leakage current of 2 μA due to the electric filed crowding at the isolation bottom between drive bipolar junction transistor(BJT) and output BJT. To solve this, non-isolated devices were also fabricated with improved BVCEOof 2370 V, indicating the superior potential of 4 H-Si C monolithic Darlington transistors for high power application, while the current gain is deceased to 420, which needs further improvement.

Synergistic high efficiency and low energy loss of all-small-molecule organic solar cells based on benzotriazole-basedπ-bridge unit

Reducing energy loss(V_(loss))is one of the most crucial challenges in organic photovoltaic cells.The V_(loss),determined by the differences between the optical band gap(E_(g))of the active layer material and the open-circuit voltage(V_(oc))of the device,is generally alleviated by lowering the energy difference between the lowest unoccupied molecular orbital(LUMO)and highest occupied molecular orbital(HOMO)level of the donor(D)and acceptor(A).In this work,we synthesized two A-π-D-π-A-type small-molecule donors(SMDs)SM-benzotriazole(BTz)-1 and SM-BTz-2 by introducing a BTzπ-bridge unit and terminal regulation.The BTzπ-bridge unit significantly lowers the HOMO energy level of SMDs,resulting in high V_(oc)and high mobility,achieving a balance of low energy loss(<0.5 eV)and high efficiency.Ultimately,the organic solar cells based on SM-BTz-2 as the donor and Y6 as the acceptor obtain a high V_(oc)of 0.91 V,J_(sc) of 22.8 mA cm^(−2),fill factor of 68%,and power conversion efficiency(PCE)of 14.12%,which is one of the highest efficiencies based on the SMDs with triazoleπ-bridges to date.What’s more,the BTzπ-bridge unit is a potential unit that can improve mobility and reduce energy loss.