液化石油气-空气混气系统及其运行维护中常见问题和对策探讨

分析了液化石油气-空气混气系统作为城市调峰气源时,日常运行及维护保养中出现的问题,结合应用实例,提出了解决办法。探讨了如何保障系统的正常运转,使其切实起到调峰作用。

镁合金低压铸造专用混合保护气体系统

研制了一种镁合金低压铸造专用混合保护气体系统。该系统可实现压缩空气、SF6以及CO2三种气体按比例混合,并提供常压熔炼、低压过程保护、泄露保护三路供气支路。实际应用表明,该混气系统可实现对镁合金低压铸造全过程的有效阻燃保护。

LPG混气系统供气量调节与储气罐容积分析

对液化石油气混气系统,由于供气与用气之间存在不平衡,会造成系统中的压力波动,增加运行的难度,因而系统中往往要设置压力缓冲储气罐。分析了混气系统供气量的调节,采用仿真的方法,模拟用气量的变化,分析得出了储气罐容积计算的数学模型,给出了以系统的压力变化为参数确定压力缓冲储气罐容积的方法。

基于自适应步长ADMM的电-气混联系统多时间尺度优化调度

随着微型燃气轮机和以其为基础的热电联供单元的大量配置,电力、天然气系统之间的联合优化调度越来越受到关注。针对电-气混联系统的优化调度问题,提出双层多时间尺度优化调度框架,考虑到各子系统间信息的不透明特性,上层基于日前预测数据和自适应步长交替方向乘子法(ADMM)建立以系统成本为目标函数的分布式日前优化调度模型;针对可再生能源和负荷的波动,下层基于短时预测数据建立以遵循日前调度方案为目标的实时调度模型。通过算例分析验证了所提电-气混联系统优化调度模型和框架的有效性。

考虑风电场接入的电-气混联系统优化调度

考虑风电消纳及系统运行经济性,建立计及风电场的电-气混联系统优化调度模型,以系统运行成本最小为目标函数,采用原对偶内点法对模型求解。以修改的IEEE39节点电力系统及20节点天然气网络为仿真算例,分析电转气设备接入前后以及是否参与系统旋转备用需求等不同场景的优化结果。算例仿真结果表明,电转气设备可以充分消纳电网富余电量,提高系统风电消纳能力。

促进风电消纳的电-气混联系统优化模型及求解算法

本文通过考虑电转气设备接入后对风电场运行效益的积极作用,将风电投资商作为电转气设备的运营主体,建立促进风电消纳的双层优化模型。其中,配置层模型以风电运营商投资收益最大为目标函数,采用飞蛾扑火算法得到电转气设备安装容量,运行层模型以系统运行成本最小为目标函数,采用原对偶内点法计算得到系统运行参数,通过中间变量在双层模型间进行传递直至迭代搜索到最优配置方案。以修改的IEEE39节点电力系统网络及20节点天然气网作为仿真算例,分析电转气设备配置前后以及不同风险水平下的优化结果。

大尺寸密闭空间内甲烷—空气混合过程的数值模拟

根据10 m3多功能步入式爆炸罐的结构特点,依据进气—混气一体化的设计理念,建立了适用于10 m3爆炸罐的轴对称直管式进气—混气系统,并利用计算流体力学软件FLUENT,对进气—混气系统的具体设计参数进行了优化。通过模拟得到了直管上不同开孔孔径、开孔间距条件下小孔体积流量率的变化规律,发现减小整体开孔孔径、减小开孔间距、调整个别小孔大小能够提高小孔体积流量率的一致性,达到气体快速均匀混合的效果。

基于改进交替方向乘子法的电—气—热系统分布式优化调度

随着微型燃气轮机和以其为基础的热电联供单元在配电网中的大量接入,电力系统、天然气系统和供热系统之间的耦合关系和联合优化越来越受到关注。针对电—气—热混联系统日前调度问题,建立了以系统经济成本为目标函数的日前调度模型。其次,建立了配电网、热网模型并考虑了动态特性的天然气网络模型。另外,考虑到电—气—热系统之间信息不透明特性,提出了基于改进交替方向乘子法(ADMM),即带高斯回代ADMM的分布式优化调度方法。最后通过算例分析验证了所提模型和优化框架的有效性。

水帘式混气自动静电喷涂系统软件的修改

对SPC200系统软件进行修改，可以满足生产过程中不同规格、品种产品的要求，进一步降低消耗，提高生产作业率，达到系统设计能力。

Experimental study on gas–liquid dispersion and mass transfer in shear-thinning system with coaxial mixer

The effects of impeller type, stirring power, gas flow rate, and liquid concentration on the gas–liquid mixing in a shear-thinning system with a coaxial mixer were investigated by experiment, and the overall gas holdup, relative power demand, and volumetric mass transfer coefficient under different conditions were compared. The results show that, the increasing stirring power or gas flow rate is beneficial in promoting the overall gas holdup and volumetric mass transfer coefficient, while the increasing system viscosity weakens the mass transfer in a shearing–thinning system. Among the three turbines, the six curved-blade disc turbine(BDT-6) exhibits the best gas pumping capacity; the six 45° pitched-blade disc turbine(PBDT-6) has the highest volumetric mass transfer coefficient at the same unit volume power.

Simulating Surface Aeration Systems at Different Scale of Mixing Time

Macro and micromixing time represent two extreme mixing time scales,which governs the whole hydrodynamics characteristics of the surface aeration systems.With the help of experimental and numerical analysis,simulation equation governing those times scale has been presented in the present work.

Micromixing characteristics in a gas-liquid-solid stirred tank with settling particles

The parallel-competing iodide-iodate reaction scheme was used to study the micromixing performance in a multi-phase stirred tank of 0.3 m diameter.The impeller combination consisted of a half elliptical blade disk turbine below two down-pimping wide-blade hydrofoils,identified as HEDT + 2WH_D.Nitrogen and glass beads of100 μm diameter and density 2500 kg-m^(-3) were used as the dispersed phases.The micromixing could be improved by sparging gas because of its additional potential energy.Also,micromixing could be improved by the solid particles with high kinetic energy near the impeller tip.In a gas-solid-liquid system,the gas-liquid film vibration with damping,due to the frequent collisions between the bubbles and particles,led to the decrease of the turbulence level in the liquid and caused eventually the deterioration of the micromixing.A Damping Film Dissipation model is formulated to shed light on the above micromixing performances.At last,the micromixing time t_m according to the incorporation model varied from 1.9 ms to 6.7 ms in our experiments.

Effect of carbon on microstructure of CrAlC_xN_(1-x) coatings by hybrid coating system

A systematic investigation of the microstructure of CrA1CxN1-x coatings as a function of carbon contents was conducted. Quaternary CrA1CxN1-x coatings were deposited on Si wafers by a hybrid coating system combining an arc-ion plating technique and a DC reactive magnetron sputtering technique using Cr and AI targets in the Ar/N2/CH4 gaseous mixture. The effect of carbon content on microstructure of CrA1C^N~ x coatings was investigated with instrumental analyses of X-ray diffraction, X-ray photoelectron, and high-resolution transmission electron microscopy. The results show that the carbon content of CrA1CxN1-x coatings linearly increases with increasing CH4/（CH4/N2） gas flow rate ratio. The surface roughness of the CrA1CxN1-x coating layer decreases with the increase of carbon content.

Optimal air-supply mode of hybrid system with radiant cooling and dedicated outdoor air

The hybrid system with radiant cooling and dedicated outdoor air not only possesses high energy efficiency, but also creates a healthy and comfortable indoor environment. Indoor air quality will be improved by the dedicated outdoor air system(DOAS) and indoor thermal comfort can be enhanced by the radiant cooling system(RCS). The optimal air-supply mode of the hybrid system and the corresponding design approach were investigated. A full-scale experimental chamber with various air outlets and the ceiling radiant cooling panels(CRCP) was designed and established. The performances of different air-supply modes along with CRCPs were analyzed by multi-index evaluations. Preliminary investigations were also conducted on the humidity stratification and the control effect of different airflow modes to prevent condensation on CRCP. The overhead supply air is recommended as the best combination mode for the hybrid system after comprehensive comparison of the experiment results. The optimal proportion of CRCP accounting for the total cooling capacities in accord with specific cooling loads is found, which may provide valuable reference for the design and operation of the hybrid system.

Mixture Preparation and Combustion of CNG Low-Pressure Compound Direct Injection Spark-Ignited Engines

A set of compressed natural gas (CNG) multi-point direct injection system of spark-ignited engines and the corresponding measurement and data acquisition systems were developed in this paper. Based on different injection modes, the mixture formation and combustion of CNG low-pressure direct injection (LPDI) engines were studied under varying factors such as air/ fuel ratio, injection timing. Meanwhile, three-dimensional simulations were adopted to explain the mixture formation mechanisms of CNG low-pressure compound direct injection (LPCDI) mode. On the basis of test results and simulation of the mixture homogeneous degree, the conception of injection window was proposed, and the LPCDI mode was proved to be more beneficial to the mixture concentration stratification formation in cylinder under lean-burning conditions, which resulted in effective combustion and stability.

Heating and Cooling Hybrid System with Gas Mixture Sourced Heat Pump and Heating Boiler

Preliminary investigation shows that air sourced type heat pumps by energy efficiency are competitive with gas boilers having 93% of coefficient of performance （COP） if heat pumps are used in climatic zones, having outside air temperature higher than （-3 ℃ to -5 ℃）. But, in such conditions the heat pump＇s evaporator is covered by ice crust, which cuts off the flow of outside air-heat source through the evaporator of heat pump. For avoiding stating problems it is recommended to use as heat source a mixture of waste warm gases. In this article a high efficiency heating-cooling system is developed, consisting of warm gases mixture sourced heat pump, heating boiler operating simultaneously with heat pump and solar air heater. The heating demand of the served house is shared between boiler and heat pump. Instead of outside air the warm gases mixture enters into evaporator of heat pump. A new construction of heat exchanger was developed. The article presents the structure and principle of operation, as well as the method for optimization and design of suggested system. Analysis proved high energy efficiency and cost effectiveness of the new system.

Modern Electrical Power Source on New System of Dissipation and Renewable Energies Sources

This paper presents some solutions of modem renewable energy system applied actually in dissipation energy source： wind turbine, solar panel battery charge, SSS （support set system）, and standby diesel generator cooperated in series, parallel and hybrid system with main energy system. Its solution enable obtain independent individual energy source in different work exploitations. One of problems concerned with alternative energy source is changes of output voltages and output power dependence of climatic conditions. Possible solution is application of decoupled adjustable speed generation system in renewable energy generation. The decoupled generation system consists of： alternative energy source, internal combustion engine drives permanent magnet generator and DC/AC, or AC/AC converter. Performance of single decoupled generation set is discussed supported by results of laboratory tests. To provide high quality voltage is applied an additional energy storage, made from super capacitor and bidirectional DC/DC convert. Such system performs very stiff voltage in any load condition. Integration of solar battery panels or renewable wind energy system is provided via DC link of the variable speed decoupled autonomous generation system. Results of computer simulation and laboratory experiments are presented in the paper.

Absorption Spectroscopy of （8,1） Band in d^3△-a^3П System of CS Radical

The CS radical was generated by discharging the mixture gas of CS2 and Helium. The Doppler limited spectra of CS were recorded in the region of 12350-12950 cm^-1 using optical heterodyne concentration modulation absorption spectroscopy. Three hundred and twenty-six lines were recorded and assigned to the d^3△-a^3П （8,1） band, in which eighty-three transitions were first observed. A set of improved molecular constants for the d^3△（v=8） and a^3П（v=1） levels were determined by a non-linear least-squares fitting of all the lines to the effective Hamiltonian.

Large-scale Experimental System for Multiphase Fuel/Air Explosions

A large-scale experimental for multiphase combustion and explosion study was developed and manufactured. The explosion tank consists of a 2 m diameter, 3.5 m long tube and ellipsoidai dames on both ends. The volume of the experimental tank is 10 ma. Pressure histories of the explosion pressure can be measured at different locations in the tank. High pressure glass windows of 200～300 mm were used to have access to the visualization of the explosion process. The explosion process of methane/air mixture and methane/coal dust/air mixture initiated by a 40 J electric spark at the center of the tank was studied in the large^scale experimental system. Five pressure sonsars were arranged in the tank with different distances from the ignition point. Ton dust dispersion traits were equipped to eject dust into the tank. A high-speed camera system was used to visualize the flame propagation during the explosion process. The characteristics of the pressure wave and flame propagated in methane/air mixtures and methane/coal dust/air mixtures have been

Performance Analysis of the Aeration Valves and Its Protections at the Generating Units in ITAIPU Hydroelectric Power Plant

With the growing energetic need present in the world, it is increasingly necessary for the researches and facilities to seek a better use of renewable natural resources. This paper is applied in the study of the performance of the aeration system of the Francis turbines present in Itaipu Hydroelectric Power Plant. When a Francis turbine operates off its optimal conditions, a vortex is formed inside the draft tube that, besides produces cavitation and pressure fluctuations, can pulse at frequencies with risk of resonance with hydraulic system, producing efforts and vibrations that may cause structural failures in the turbines, generators and civil parts of the power house. These damaging effects can be reduced using atmospheric aeration of the turbines. Because of this, the availability and effectively of the aeration system is fundamental to smooth the behavior of the turbines, helping preserve the health of the power plant. An analysis of the performance of the aeration system will be done using maintenance records and disturbances analysis reports （RAP）, allowing verification of the operating conditions of the turbine and fatality of water inlet in air pipes. Through the improvements detected, it is possible to reduce machine stoppages by tripping, thus increasing the availability of the turbines.