Water-saving Potential in aeolian sand soil under straight tube and surface drip irrigation in Taklimakan Desert in Northwest China

Evaporation loss from the saturated soil beneath drip irrigation emitters highly influences the irrigation efficiency of drip krigation （D1]. Subsurface drip irrigation （SDI） is one good approach to curb this inefficiency, but in a new irrigation method, straight tube irrigation （STI）, the irrigation tubes do not need to be buried and thus STI is recommended to increase the irrigation efficiency under normal surface-applied DI. STI consists of only connectors and water-transference tubes that can directly transfer irrigation water from the lateral emitters in the drip line to the root zone of plants. Five-month field experiments were carried out in aeolian sand soil in the forest-belts of the Taklimakan Desert, which have poor water storage capacity, to compare the potential water saving between STI and DI. The preliminary results showed that, compared with DI, STI （1） improved the soil water content in soil depths from 40 to 100 cm under the soil surface; （2） achieved the same irrigation effects in relatively shorter irrigation durations; （3） had very little water loss due to deep seepage; and （4） formed a layer of dry sand about 10 to 30 cm thick immediately below the soil surface, which lessened evaporation loss of soil water beneath the emitters on the soil surface. This demonstrates that STI can maximize the water-saving potential of DI through the reduction of wetted soil perimeters on the soil surface. This is valuable information for water-saving engineering applications and projects with STI in arid and semiarid regions.

A Study of Water Treatment Chemical Effects on Type I” Pitting Corrosion of Copper Tubes

It is known that one of the causes of pitting corrosion of copper tubes is residual carbon on the inner surface. It was confirmed that type I” pitting corrosion of the copper tube is suppressed by keeping the residual carbon amount at 2 mg/m2 or less, which is lower than that of the type I’ pitting corrosion, or by removing the fine particles that are the corrosion product of galvanized steel pipes. The developed water treatment chemical was evaluated using three types of copper tubes with residual carbon amounts of 0 mg/m2, 0.5 mg/m2, and 6.1 mg/m2. The evaluation was conducted for three months in an open-circulation cooling water system and compared with the current water treatment chemical. Under the current water treatment chemical conditions, only the copper tube with a residual carbon amount of 6.1 mg/m2 showed a significant increase in the natural corrosion potential after two weeks, and pitting corrosion occurred. No pitting corrosion and no increase in the natural corrosion potential were observed in any of the copper tubes that were treated with the developed water treatment chemical. In addition, the polarization curve was measured using the cooling water from this field test, and the anodic polarization of two cooling waters was compared. For copper tubes with a large amount of residual carbon, the current density near 0 mV vs. Ag/AgCl electrode (SSE) increased when the developed water treatment chemical was added.

Performance enhancement of water bath heater at natural gas city gate station using twisted tubes

Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m^3·h^-1. Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.

Structural Analysis and Optimal Design for Water Tube Panel in an Alkali Recovery Boiler

Alkali recovery aiming at recovering NaOH is the best available technology in China's pulp and paper industry;an alkali recovery boiler is a popular one among all alkali recovery units. For the purpose of designing the most reasonable tube-panel of an evaporator in a 1500 t/d alkali recovery boiler, a total of 8 kinds of cases are put forward for finite element analysis. The modeling, meshing and calculation are carried out for each case. The stress values and their distribution rules are revealed in this paper. The slotting size for the water tubes panel is analyzed by using the optimum design module of ANSYS. After all cases are compared with each other, the optimal one is developed and exemplified in conclusion.

Performance of Water in Glass Evacuated Tube Solar Water Heater under Kenya Climatic Condition

Solar water heaters which provide a cost-effective and environmental friendly approach to hot water generation are in widespread application. Evacuated tube solar water heaters perform better than flat plate solar water heaters as a result of their greater surface area exposed for sunlight absorption. Water-in-glass evacuated tube solar water heaters are widely used as compared to heat-pipe solar water heaters due to their short payback periods. In this study, the performance of water-in-glass evacuated tube solar water heater is investigated through experiments under the climatic conditions in Kenya. The results revealed a daily efficiency range of 0.58 - 0.65 and a daily final outlet temperature greater than 55°C given an initial temperature of 25°C.

Effects of the Produced Water from a Sour Oilfield in South Kuwait on the Production Tubing

Kuwaiti oil production faces a growing challenge in the increasing quantities of produced water generated in the production of oil. The high water cut of the produced fluid from the wells and the high salinity of the produced water lead to significant degradation of subsurface equipment, specifically the production tubing. Debris generated through the degradation of the inner part of the tubing becomes a constituent of the scaling that deposits in the tubing and blocks the flow of the production fluid, inducing higher maintenance costs. This paper looks at the characteristics of the scaling in regard to the produced water and outlines the economic impact of the produced water induced degradation of the tubing structure.

Emitter discharge characteristics of vertical tube irrigation affected by various factors

To examine the working principle of vertical tube irrigation, variations in vertical tube emitter discharge and their causes were analyzed in the laboratory experiment. The effects of the pressure head, initial soil water content, and tube diameter on the emitter discharge of the vertical tube were studied. The results show that quantitative relationship between the time and cumulative infiltration and emitter discharge of the vertical tube is obtained, and R 2 is more than 0.98. Emitter discharge exhibits a positive and negative correlation with the pressure head and soil water content, respectively. Tube dia- meter has a nonsignificant effect on the emitter discharge. Changes of the soil water content around the emitter water outlet are the main causes of emitter discharge variations. In the experiments, the range of vertical tube emitter discharge is 0.056-1.102 L/h. The emitter of vertical tube irrigation automatically adjusts the soil water content and maintains the root zone soil water content within an appropriate range, which achieves continuous irrigation, and further achieves the effect of water-saving.

Performance of U-tube Solar Water Heaters Facing Different Directions

System performance of solar water heaters depends upon collector and storage tank designs, solar radiation intensity and ambient temperature, amongst others. Evacuated glass tube collectors with U-tubes inside are less prone to leakages than the all-glass or the heat pipe types. U-tube solar water heaters suspended on walls and balconies could help overcome present day roof space restriction and increasing apartment-style housing. As such, their performance would depend upon its orientation when mounted in a vertical position. This paper reports the results of outdoor tests conducted on natural convection U-tube solar water heaters oriented towards different directions. Long and short term test procedures were employed to allow us to compare their performances as if they were tested simultaneously side-by-side.

计算机视觉的电站锅炉水冷壁缺陷检测方法

发电厂锅炉巡检可有效避免安全事故发生,针对现场巡检过程中,锅炉水冷壁巡检区域较大,部分区域检测困难问题,开发一种基于YOLOv3模型的水冷壁缺陷检测系统。无人机携带视觉采集装置,对豫能集团某电厂锅炉水冷壁进行图像采集,画面经压缩后实时无线传输到检测末端装置,采用YOLOv3算法对水冷壁数据进行分析,对模型重要参数进行调整并做出样本增广与平衡化改进处理,提高检测效果,共测出磨损、裂缝、氧化等106处失效部位,与人工检测对比,成功率达77.9%。该方法解决了在巡检区域大、部分区域检测困难问题,使大型电站锅炉在开展水冷壁检测方面实际付出的成本得到有效缩减。

HEOS治疗宫腔粘连术后预防再粘连3种方法的对比研究

目的 比较3种不同方法在HEOS系统治疗不同程度宫腔粘连术后预防再粘连疗效的研究。方法 分析昆明市妇幼保健院收治的284例的轻中重度宫腔粘连患者,使用HEOS系统治疗后,分为3组,A组(节育环组)放置宫内节育环+透明质酸钠凝胶、B组(球囊组)放置Foley水囊管+透明质酸钠凝胶、C组(对照组)仅放置透明质酸钠凝胶。比较3组术后宫腔粘连恢复情况、月经改善情况、子宫内膜厚度以及术后不良反应。结果轻度宫腔粘连组,月经改善情况中3组比较,差异有统计学意义(P<0.05),A组比C组月经改善率高(对R×C卡方检验两两比较,校正显著水平,P<0.017),其他疗效指标中无显著差异(P>0.017),但A组不良反应率较C组高(P<0.017)。在中度宫腔粘连组,B组的宫腔粘连改善率与其他两组比较有显著差异(P<0.017)。在月经改善率、子宫内膜厚度、不良反应方面,A、B组均较C组增加(P<0.017)。重度宫腔粘连组中,A组各疗效指标均较其他组高(P<0.017)。结论 综合疗效指标和不良反应率分析,对轻、中、重度宫腔粘连,术后依次为放置透明质酸钠凝胶、Foley水囊管+透明质酸钠凝胶、宫内节育环+透明质酸钠凝胶为各程度粘连的最佳选择。达到个体化及分层管理,可取得良好临床效果,值得推广。

考虑“筒中筒”耦合作用的深水隔水管柱与钻柱碰摩运动规律

深水钻井时,旋转钻柱与海洋环境力作用下发生振动的隔水管柱易发生接触,造成钻柱与隔水管柱的碰撞或者摩擦。为了解隔水管柱与钻柱间的运动状态,减轻两者间碰摩,保证作业安全性,提出了一种模拟深水隔水管柱-钻柱组成的“筒中筒”耦合系统模型,通过分析二者间的位移与接触力,实现海洋深水钻井作业时隔水管柱与钻柱的耦合动力学模拟的建立。模拟结果表明,考虑隔水管柱与钻柱接触的情况下,海流作用和涡激作用对钻柱的动力学特征具有较大影响;海流速度增加,隔水管柱弯曲程度变大,隔水管柱的振动特征会限制钻柱运动;井口转速增加对钻柱的涡动特征影响小,但会增大钻柱与隔水管柱内壁的接触力,增大钻柱与隔水管柱的失效风险。该理论为海洋深水钻井摩阻分析提供了新的借鉴。

Y型管式油水分离结构分离特性仿真分析

管式油水分离技术具有占地面积小、分离效率高、成本低等优点,基于管式油水分离原理,设计一种Y型管式油水分离结构,利用Fluent数值模拟软件,采用标准k-ε湍流模型和Mixture多相流模型,对Y型管内部流场特性以及外部参数对分离效率的影响进行了研究。结果表明,Y型管对流体扰动小,内部流场特性稳定不易产生涡流,能够实现油水分离,支管与主管交汇处存在油水分离现象;油水分离效率随着油滴粒径的增大而逐渐提高,油滴粒径越大越利于油相上浮聚集在Y型管上层,能有效提高油水分离效率;入口速度对油水分离效果的影响很大,速度越大,油相上浮时间越短,Y型管的分离效率越低;分离效率随支管分流比的增大而增大,当入口速度为0.5 m/s时,分流比超过0.4后,分离效率不再增加。研究结果为油水分离提供了新思路,可为Y型管的设计提供理论参考。

超临界W型火焰锅炉结构效应导致前墙水冷壁温差偏大问题的研究与治理

为解决某锅炉前墙水冷壁温差偏大导致水冷壁频繁超温爆管的问题,从管外传热和管内吸热两方面对热偏差进行分析,发现采用内螺纹管技术的水冷壁管具有自补偿特性,通过数值模拟试验发现结构效应带来温度场和气流场的变化对热偏差影响显著,是造成水冷壁变形和泄漏的主要原因,进而提出二次风差异配风、水冷壁前墙喷涂绝热涂料和优化卫燃带等治理方案,成功治理了水冷壁超温爆管问题.

角管式锅炉过热器模块制造技术简介

本文针对我公司某角管式锅炉过热器模块结构特点及制造难点进行简要介绍,重点针对此类模块结构产品的制造工艺流程及制造技术进行详细阐述。

AlCrNbSiTi高熵合金涂层高温水蒸气腐蚀研究

采用磁控溅射在不同偏压条件下制备AlCrNbSiTi高熵合金涂层,通过分析不同偏压涂层的形貌、化学成分、硬度,以及被水蒸气腐蚀后的涂层形貌,研究偏压对AlCrNbSiTi涂层结构及性能的影响。结果表明,偏压对涂层表面粗糙度的调控非常显著,150 V偏压的样品表面粗糙度只有3.35 nm;50 V偏压的样品具有最大硬度和弹性模量,分别为18.19 GPa和232.4 GPa。涂层水蒸气腐蚀失效机制为点腐蚀,偏压为50 V时腐蚀坑出现时间最晚,耐腐蚀性能最好。

井下多级并联微旋流器流量均布性分析及优化

采用多级并联微旋流器的方式实现井下油水分离,不仅可以提高采出液含油体积分数,同时能够满足高处理量要求。在井下工作时,若油水分离设备与套管间形成的油套环空流场结构不合理,会导致每级微旋流器组得到的流量不均匀,影响多级并联微旋流器分离装置的整体分离性能。基于数值模拟和响应面Box-Behnken试验设计方法,构建了分离装置和套管形成的油套环空流体域的结构参数与流量不均匀系数、最大压力损失间的数学模型,并对模型的有效性进行了验证。分析结果表明:当每级入口间距为400 mm、每级入口角度为90°、总级数为3级、出入口面积比为0.5时,优化后的流量不均匀系数从0.02653减小到0.01289,降幅达51.41%;与初始结构对比,当雷诺数在3000~8000范围内变化时,优化结构的流量不均匀系数在各种工况下比较稳定,最大可减小0.04708,最小为0.01125;优化后的结构呈现了较好的流量均匀分配性能及适应性。所得结果可为井下多级并联微旋流器的设计及应用提供参考。

水冷壁高温腐蚀原因分析

通过宏观分析、显微组织观察、扫描电镜与能谱成分分析和X射线衍射分析,对某电厂水冷壁向火侧进行高温腐蚀原因分析。结果表明:由于该锅炉采用四角切圆燃烧方式导致水冷壁局部高温;复合空气分级低NO_(x)燃烧系统导致部分燃烧器区域处于贫氧还原性气氛,使烟气中CO+H_(2)S浓度过高;锅炉入炉煤硫份超过设计值较多,形成高浓度的H_(2)S和SO_(2);水冷壁向火侧腐蚀以硫腐蚀为主。针对该锅炉水冷壁高温腐蚀问题,给出以下建议:控制入炉煤硫份,降低煤中的硫元素含量,减少H_(2)S和SO_(2)浓度;燃烧优化调整,采用侧边风技术,向炉膛内通入空气,降低水冷壁高温腐蚀区域的还原性气氛浓度,增加局部含氧量;在高温腐蚀严重的区域,对其水冷壁管进行防高温腐蚀喷涂处理,以增强其抗高温腐蚀性能。

絮凝-真空抽滤-土工管袋联合处理泥浆脱水模型试验

近年来,土工管袋因其良好的排水反滤性能广泛应用于河湖清淤泥浆的脱水处理中,但在脱水后期存在脱水速率缓慢的问题。为此,开展物理模型试验验证在添加絮凝剂的条件下,采用增压式抽真空来增加土工管袋内泥浆后期脱水固结速率的可行性,同时还比较了“空气动力振荡法”与“管袋顶部加荷法”2种方法的抽滤脱水效率。试验结果及分析表明:“空气动力振荡法”会使土工管袋内的原本相对密实泥浆出现裂隙,使得土工管袋内泥浆的气密性被破坏;“管袋顶部加荷法”增加了管袋内泥浆压力,提高了反滤层两侧的压力梯度,使得清淤泥浆的抽滤速度提高;真空抽滤可以显著降低土工管袋内部、抽滤管道周围的泥浆含水率,且抽滤管道越靠近土工管袋中心,抽滤效率越高,泥浆含水率也越低。

湿法锌冶炼过程中对余热锅炉安全的探索与实践

湿法锌冶炼过程中余热锅炉的安全至关重要。宝徽集团主要针对余热锅炉的爆管现象和积灰问题,对余热锅炉安全进行了改造实践。改造后,余热锅炉进气口烟气的流速明显降低,有效降低了爆管风险,余热锅炉的安全性大大提升。清灰方式升级为弹簧振打、爆破共同作用后,清灰效果显著增加,管道积灰现象改善。

固相萃取结合液质联用法快速筛查和分析生活饮用水中的56种抗生素

目的:建立生活饮用中56种抗生素的固相萃取-液相色谱-串联质谱分析方法。方法:将生活饮用水通过大容量采样管连接到固相萃取柱上净化,用C18柱梯度洗脱分离目标物,以乙腈和0.1%甲酸水为流动相,经电喷雾离子源电离,多反应监测模式串联质谱检测。结果:56种抗生素的最低检测浓度为0.1~2.0μg·L^(-1),在其线性范围内的相关系数均大于0.995,3个浓度水平的加标回收率为63.3%~113.0%,相对标准偏差在3.1%~8.3%。结论:该方法前处理简单、快速,适用于生活饮用水中多种抗生素的快速筛查和定量检测。