煤泥水浓度偏高原因分析及处理技术

煤泥水浓度是影响脱介效果和精煤产品质量的重要因素,在指导分选生产中起着重要作用。以山西焦煤西山煤电屯兰选煤厂煤泥水浓度偏高情况为例,分析了高频筛回收效果差、絮凝剂添加不科学、浓缩机溢流大、重介系统筛板、筛篮跑粗等因素是影响煤泥水浓度偏大的主要原因。针对上述问题提出控制浓缩机溢流电流在280~310 A,絮凝剂配制成0.1%溶液;降低设备底煤厚度等技术方案。改造后,选煤厂煤泥水质量浓度低于13 g/L,提高产品产率,实现节能降耗,提高选煤厂的效率。     

Optimization models for shale gas water management

There are four key aspects for water use in hydraulic fracturing, including source water acquisition, wastewater production, reuse and recycle, and subsequent transportation, storage, and disposal. Water use life cycle is optimized for wellpads through a discrete‐time two‐stage stochastic mixed‐integer linear programming model under uncertain availability of water. The objective is to minimize expected transportation, treatment, storage, and disposal cost while accounting for the revenue from gas production. Assuming freshwater sources, river withdrawal data, location of wellpads, and treatment facilities are given, the goal is to determine an optimal fracturing schedule in coordination with water transportation, and its treatment and reuse. The proposed models consider a long‐time horizon and multiple scenarios from historical data. Two examples representative of the Marcellus Shale play are presented to illustrate the effectiveness of the formulation, and to identify optimization opportunities that can improve both the environmental impact and economical use of water. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3490–3501, 2014     

Optimal maintenance scheduling of a gas engine power plant using generalized disjunctive programming

A new continuous‐time model for long‐term scheduling of a gas engine power plant with parallel units is presented. Gas engines are shut down according to a regular maintenance plan that limits the number of hours spent online. To minimize salary expenditure with skilled labor, a single maintenance team is considered which is unavailable during certain periods of time. Other challenging constraints involve constant minimum and variable maximum power demands. The objective is to maximize the revenue from electricity sales assuming seasonal variations in electricity pricing by reducing idle times and shutdowns in high‐tariff periods. By first developing a generalized disjunctive programming model and then applying both big‐M and hull reformulation techniques, we reduce the burden of finding the appropriate set of mixed‐integer linear constraints. Through the solution of a real‐life problem, we show that the proposed formulations are very efficient computationally, while gaining valuable insights about the system. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2083–2097, 2014     

Integration of scheduling and control for batch processes using multi‐parametric model predictive control

Integration of scheduling and control results in Mixed Integer Nonlinear Programming (MINLP) which is computationally expensive. The online implementation of integrated scheduling and control requires repetitively solving the resulting MINLP at each time interval. (Zhuge and Ierapetritou, Ind Eng Chem Res. 2012;51:8550–8565) To address the online computation burden, we incorporare multi‐parametric Model Predictive Control (mp‐MPC) in the integration of scheduling and control. The proposed methodology involves the development of an integrated model using continuous‐time event‐point formulation for the scheduling level and the derived constraints from explicit MPC for the control level. Results of case studies of batch processes prove that the proposed approach guarantees efficient computation and thus facilitates the online implementation. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3169–3183, 2014     

浅谈大型分馏塔内件安装的常见问题及整改措施

分馏塔是蜡油加氢裂化装置分馏系统最重要的设备,其运行好坏直接影响产品质量。而分馏塔塔径大,塔内件安装难度突出,故其施工和验收要格外仔细。本文主要介绍在安装大型分馏塔内件过程中出现的一些常见问题,并根据其原因提出了相应的整改措施。     

乙炔发生器溢流管的改造

对乙炔发生器溢流管进行了改造,降低了乙炔发生器压力和电石消耗,优化了操作条件,使乙炔收率由86.81%提高至88.53%,可节约电石成本1 083.6万元/a,经济效益显著。     

Performance-based seismic fragility analysis of retaining walls based on the probability density evolution method

Seismic fragility analysis is an efficient way to study the seismic behaviour and performance of structures under the excitation of earthquakes of varying intensity, and an essential part of the seismic risk assessment of structures. A recently developed dynamic reliability methodology, the probability density evolution method (PDEM), is proposed for the dynamic reliability and seismic fragility analysis of a retaining wall. The PDEM can obtain an instantaneous probability density function of the seismic responses and easily acquire the seismic reliability of the structural system. An important advantage of the PDEM is its high efficiency relative to that of the Monte Carlo simulation method, which is often used in the reliability and fragility analysis of structures. The present study uses a typical gravity retaining wall to illustrate stochastic seismic responses and fragility curves that can be obtained by the PDEM. The combined uncertainties of the seismic force and soil properties are explicitly and systematically modelled by stochastic ground motions and random variables respectively. The performance of the retaining wall is analysed for different acceptable levels of backfill settlement. Additionally, seismic fragility curves are constructed without assuming the distribution of the seismic response.     

基础设施PPP项目脆弱性影响因素研究

以基础设施 PPP 项目为对象,借助网络模型,对其进行脆弱性影响因素的研究。基础设施 PPP 项目作为一个系统,其脆弱性往往由脆弱性影响因素诱发。将影响因素作为网络中的节点,因素间的关联关系及强度作为边和权重,在此基础上构建无向加权网络。通过对网络模型参数的计算,可以按照重要程度对脆弱性影响因素进行排序,从而为基础设施 PPP 项目的风险管理提供理论依据和实践指导。     

50m高钢管混凝土一次顶升浇筑施工技术

邯钢酸洗镀锌主厂房采用双肢钢管混凝土柱，依据混凝土顶升的施工原理、顶升压力，分折影响因素，改进混凝土配合比，设置止回装置和排气、溢流孔，解决了钢管混凝土一次顶升的难题。     

两过水土石围堰不同破坏程度原因分析

两过水土石围堰导流标准和导流方案相同,在经受流量Q=3000m3/s左右的洪水后,两围堰产生了截然不同的破坏结果。从上下游堰顶高差、挑流平台高程设计及消能等方面,分析了结构物产生破坏的原因。