安徽省城镇化效率与生态环境质量耦合协调时空演化

研究城镇化效率与生态环境质量耦合协调关系,有助于探寻两者之间本质联系,可为区域协调发展提供科学依据。本研究通过构建综合评价体系,测度安徽省各地级市的城镇化效率和生态环境质量水平,并借助耦合协调度和空间自相关模型,分析安徽省城镇化效率和生态环境质量耦合协调水平以及空间格局特征。结果表明:① 2005-2020年安徽省城镇化效率均值由 0.937上升至 1.055,有效决策单元数量占比77.3 %,空间上呈现以合肥、铜陵为中心向西北-东南方向辐射的特征;②安徽省生态环境质量指数总体呈波动上升的发展趋势,指数均值从0.217上升至0.413,且具有“南高北低”的空间分布格局;③安徽省城镇化效率与生态环境质量的耦合度和耦合协调度均呈现上升趋势,耦合度处于耦合阶段,协调度以中度协调类型为主,但城市间差异明显,制约了区域整体的协调发展;④耦合协调度在空间上表现出较强的正相关性,高-高和低-高集聚区集中在安徽省南部地区,低-低集聚区则分布在北部地区。为促进区域城镇化效率与生态环境质量两系统协调发展,政府未来应因地制宜制定发展策略,贯彻绿色发展理念,积极推动产业转型,通过优化资源配置促进区域良性发展。     

Optimization of the O3/H2O2 process with response surface methodology for pretreatment of mother liquor of gas field wastewater

• Real ML-GFW with high salinity and high organics was degraded by O₃/H₂O₂ process. • Successful optimization of operation conditions was attained using RSM based on CCD. • Single-factor experiments in advance ensured optimal experimental conditions. • The satisfactory removal efficiency of TOC was achieved in spite of high salinity. • The initial pH plays the most significant role in the degradation of ML-GFW. The present study reports the use of the O₃/H₂O₂ process in the pretreatment of the mother liquor of gas field wastewater (ML-GFW), obtained from the multi-effect distillation treatment of the gas field wastewater. The range of optimal operation conditions was obtained by single-factor experiments. Response surface methodology (RSM) based on the central composite design (CCD) was used for the optimization procedure. A regression model with Total organic carbon (TOC) removal efficiency as the response value was established (R² = 0.9865). The three key factors were arranged according to their significance as: pH>H₂O₂ dosage>ozone flow rate. The model predicted that the best operation conditions could be obtained at a pH of 10.9, an ozone flow rate of 0.8 L/min, and H₂O₂ dosage of 6.2 mL. The dosing ratio of ozone was calculated to be 9.84 mg O₃/mg TOC. The maximum removal efficiency predicted was 75.9%, while the measured value was 72.3%. The relative deviation was found to be in an acceptable range. The ozone utilization and free radical quenching experiments showed that the addition of H₂O₂ promoted the decomposition of ozone to produce hydroxyl radicals (·OH). This also improved the ozone utilization efficiency. Gas chromatography-mass spectrometry (GC-MS) analysis showed that most of the organic matters in ML-GFW were degraded, while some residuals needed further treatment. This study provided the data and the necessary technical supports for further research on the treatment of ML-GFW.     

Evaluation of the technoeconomic feasibility of electrochemical hydrogen peroxide production for decentralized water treatment

• Gas diffusion electrode (GDE) is a suitable setup for practical water treatment. • Electrochemical H₂O₂ production is an economically competitive technology. • High current efficiency of H₂O₂ production was obtained with GDE at 5–400 mA/cm². • GDE maintained high stability for H₂O₂ production for ~1000 h. • Electro-generation of H₂O₂ enhances ibuprofen removal in an E-peroxone process. This study evaluated the feasibility of electrochemical hydrogen peroxide (H₂O₂) production with gas diffusion electrode (GDE) for decentralized water treatment. Carbon black-polytetrafluoroethylene GDEs were prepared and tested in a continuous flow electrochemical cell for H₂O₂ production from oxygen reduction. Results showed that because of the effective oxygen transfer in GDEs, the electrode maintained high apparent current efficiencies (ACEs,>80%) for H₂O₂ production over a wide current density range of 5–400 mA/cm², and H₂O₂ production rates as high as ~202 mg/h/cm² could be obtained. Long-term stability test showed that the GDE maintained high ACEs (>85%) and low energy consumption (<10 kWh/kg H₂O₂) for H₂O₂ production for 42 d (~1000 h). However, the ACEs then decreased to ~70% in the following 4 days because water flooding of GDE pores considerably impeded oxygen transport at the late stage of the trial. Based on an electrode lifetime of 46 days, the overall cost for H₂O₂ production was estimated to be ~0.88 $/kg H₂O₂, including an electricity cost of 0.61 $/kg and an electrode capital cost of 0.27 $/kg. With a 9 cm² GDE and 40 mA/cm² current density, ~2–4 mg/L of H₂O₂ could be produced on site for the electro-peroxone treatment of a 1.2 m³/d groundwater flow, which considerably enhanced ibuprofen abatement compared with ozonation alone (~43%–59% vs. 7%). These findings suggest that electrochemical H₂O₂ production with GDEs holds great promise for the development of compact treatment technologies for decentralized water treatment at a household and community level.     

北京山区植被恢复建设对流域径流量影响研究

植被恢复是山区保持水土资源、恢复生态环境的关键措施.为探究植被恢复对流域产水量的影响,以密云水库集水区红门川森林流域为研究对象,采用Mann-Kendall非参数趋势检验、基于分离评判原理的水文分析法、Zhang(2001)模型等方法,定量分析了1989－2009年间北京山区气候及森林变化对流域径流量的影响.研究结果表明:红门川流域年降水及产流性降水量在研究时段内均呈波动下降趋势(P>0.05);流域年径流呈显著性减少趋势,且年径流量在1998 年前后发生减少突变(P<0.01);气候变化对红门川流域径流减少贡献率为43%,植被恢复建设导致的森林数量及质量变化对流域径流减少贡献率为18.6%,其他人类活动影响贡献率为38.4%.综合比较得知,与植被恢复建设相比,降水减少对山区产水量减少影响更大.研究结果可为北京山区森林流域水土资源规划及管理提供参考.     

一起钢质无缝气瓶爆炸事故技术分析

文章简要描述了一起消防气体灭火钢质气瓶爆炸事故,对爆炸气瓶进行了断口分析、金相试验和理化试验,并分析了事故的原因,提醒制造厂家规范制造工艺,对预防类似事故的发生具有一定的参考意义。     

Indicating landfill stabilization state by using leachate property from Laogang Refuse Landfill

Variation and evolution process of leachate can be applied as a reference for landfill stabilization phase. In this work, leachates with different ages were collected from Laogang Refuse Landfill, and characterized with 14 key parameters. Simultaneously, principal component analysis （PCA） was applied to develop a synthetic parameter-F based on these 14 parameters, and a logarithm equation was simulated for the landfill stabilization process finally. It was predicted that leachates would meet Class I and Class II in standard for pollution control on the landfill site of municipal solid waste （GB 16889-1997） after 32 years and 22 years disposal under the natural attenuation in the humid and warm southern areas of China, respectively. The predication of landfill state would be more accurate and useful according to the synthetic parameter F of leachate from a working landfill.     

Limiting explosible concentration of hydrogen–oxygen–helium mixtures related to the practical operational case

This paper presents data on the limiting (minimum) concentrations of hydrogen in oxygen, in the presence of added helium, at elevated temperature and pressure related to the practical operational case. A 5 L explosion vessel, an ignition sub-system and a transient pressure measurement sub-system were used. Through a series of experiments carried out using this system, the limiting concentrations of hydrogen in oxygen and helium at different initial pressures and temperatures for the practical operational case were studied, and the influence of ignition energy and initial temperature on the limiting concentration of hydrogen in oxygen and helium was analyzed and discussed. The variation of ignition energy within the studied range is found to have a significant effect on the limiting concentration of hydrogen in oxygen and helium at lower initial temperature. However, when the ignition energy is higher than 32 mJ, the limiting hydrogen concentration remains almost changeless as the initial temperature increases from 21 °C to 90 °C. The limiting explosible concentration of hydrogen–oxygen–helium mixture decreases as the ignition energy increases when the initial temperature is lower. When the initial temperature is higher, the ignition energy has little effect on the limiting hydrogen concentration of hydrogen–oxygen–helium mixtures. When the initial temperature reaches 90 °C, the limiting hydrogen concentration remains almost changeless with an increase in ignition energy. The limiting explosible concentration of hydrogen in the mixtures, at the initial temperature of 21 °C and the ignition energy of 0.5 mJ, is 8.5% and that of oxygen is 11.25%.     

Dynamic behavior of direct spring loaded pressure relief valves in gas service: Model development,measurements and instability mechanisms

A synthesis of previous literature is used to derive a model of an in-service direct-spring pressure relief valve. The model couples low-order rigid body mechanics for the valve to one-dimensional gas dynamics within the pipe. Detailed laboratory experiments are also presented for three different commercially available values, for varying mass flow rates and length of inlet pipe. In each case, violent oscillation is found to occur beyond a critical pipe length, which may be triggered either on valve opening or closing. The test results compare favorably to the simulations using the model. In particular, the model reveals that the mechanism of instability is a Hopf bifurcation (flutter instability) involving the fundamental, quarter-wave pipe mode. Furthermore, the concept of the effective area of the valve as a function of valve lift is shown to be useful in explaining sudden jumps observed in the test data. It is argued that these instabilities are not alleviated by the 3% inlet line loss criterion that has recently been proposed as an industry standard.     

Optimization of HSE in maintenance activities by integration of continuous improvement cycle and fuzzy multivariate approach: A gas refinery

Gas refineries have been continuously focusing on Health, Safety and Environment programs to improve maintenance activities. Several researches have studied on this area with different analysis methods. This study presents an integrated approach for optimization of factors contributing to the implementation of Health, Safety and Environment (HSE) in maintenance activities. HSE managers in each sector answered standard questionnaire whit respect to HES. The methodology is based on fuzzy data envelopment analysis (FDEA) and Deming's continuous improvement cycle. Also, this method is used to rank the relevant performance efficiencies in certain and uncertain conditions of each HSE sectors whit considering HSE in maintenance activities. It corresponds and integrates its registered HSE-MS with OHSAS 18001:2007 and ISO 14001:2004 to evaluate multiple inputs and outputs of over 36 subsidiary HSE divisions with parallel mission and objectives simultaneously. Also, it determines efficient target indices and could assure continuous improvement in the organization. This is the first study that introduces an integrated approach to improve HSE management programs in a gas refinery by a robust and continuous improvement approach.     

Validation of the UN test method N.5

Many substances react with water in such a way that flammable gases are formed. For transport issues this reaction may possess a considerable hazard especially if the cargo is wetted by rain or by water from other sources. In the UN Recommendations on the Transport of Dangerous Goods these kinds of problems are addressed. The UN test N.5 “Test method for substances which in contact with water emit flammable gases” corresponds to this hazard. Classification according to the test method is done by measurement of the gas evolution rate of the flammable gas by any suitable procedure. At BAM a gravimetric approach is used to measure the gas evolution rate. In this paper we present the evaluation of the apparatus by means of an absolute calibration routine utilizing a reaction where a known amount of gas is produced as well as the evaluation of important parameters influencing the gas evolution rate using different substances. It can be shown that the apparatus is capable of measuring absolute gas volumes as low as 6 mL with an acceptable error of about 17% as determined from the reaction of Mg with demineralized water.