Analysis of the Flow Field and Impact Force in High-Pressure Water Descaling

This study aims to improve the performances of the high-pressure water descaling technology used in steel hot rolling processes.In particular,a 2050 mm hot rolling line is considered,and the problem is investigated by means of a fluid–structure interaction(FSI)method by which the descaling effect produced by rolling coils with different section sizes is examined.Assuming a flat fan-shaped nozzle at the entrance of the R1R2 roughing mill,the outflow field characteristics and the velocity distribution curve on the strike line(at a target distance of 30–120 mm)are determined.It is found that the velocity in the center region of the water jet with different target distances is higher than that in the boundary region.As the target distance increases,the velocity of the water jet in the central region decreases.Through comparison with experimental results,it is shown that the simulation model can accurately predict the impact position of the high-pressure water on the impact plate,thereby providing a computational scheme that can be used to optimize the nozzle space layout and improve the slabs’descent effect for different rolling specifications.

Numerical Simulation Analysis of the Transformer Fire Extinguishing Process with a High-Pressure Water Mist System under Different Conditions

To thoroughly study the extinguishing effect of a high-pressure water mist fire extinguishing system when a transformer fire occurs,a 3D experimental model of a transformer is established in this work by employing Fire Dynamics Simulator(FDS)software.More specifically,by setting different parameters,the process of the highpressure water mist fire extinguishing system with the presence of both diverse ambient temperatures and water mist sprinkler laying conditions is simulated.In addition,the fire extinguishing effect of the employed high-pressure water mist system with the implementation of different strategies is systematically analyzed.The extracted results show that a fire source farther away fromthe centerline leads to a lower local temperature distribution.In addition,as the ambient temperature increases,the temperature above the fire source decreases,while the temperature and the concentrationof theupperflue gas layer bothdecrease.Interestingly,after thehigh-pressurewatermist sprinkler begins to operate,both the temperature distribution above the fire source and the concentration of the flue gas decrease,which indicates that the high-pressure water mist system plays the role of cooling and dust removal.By comparing various sprinkler laying methods,it is found that the lower sprinkler height has a better effect on the temperature above the fire source,the temperature of the upper flue gas layer,and the concentration of the flue gas.Moreover,when the sprinkler is spread over thewhole transformer,the cooling effect on both the temperature above the fire source and the temperature of the upper flue gas layer is good,whereas the change in the concentration of the flue gas above the fire source is not obvious compared to the case where the sprinkler is not fully spread.

Application of high-pressure water jet technology and the theory of rock burst control in roadway

This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.

In situ experimental study on TBM excavation with high-pressure water-jet-assisted rock breaking

China’s first high-pressure hydraulically coupled rock-breaking tunnel boring machine(TBM) was designed to overcome the rock breaking problems of TBM in super-hard rock geology, where high-pressure water jet system is configured, including high-flow pump sets, high-pressure rotary joint and high-pressure water jet injection device. In order to investigate the rock breaking performance of high-pressure water-jet-assisted TBM, in situ excavation tests were carried out at the Wan’anxi Water Diversion Project in Longyan, Fujian Province, China, under different water jet pressure and rotational speed. The rock-breaking performance of TBM was analyzed including penetration, cutterhead load, advance rate and field penetration index. The test results show that the adoption of high-pressure water-jet-assisted rock breaking technology can improve the boreability of rock mass, where the TBM penetration increases by 64% under the water jet pressure of 270 MPa. In addition, with the increase of the water jet pressure, the TBM penetration increases and the field penetration index decreases. The auxiliary rock-breaking effect of high-pressure water jet decreases with the increase of cutterhead rotational speed. In the case of the in situ tunneling test parameters of this study, the advance rate is the maximum when the pressure of the high-pressure water jet is 270 MPa and the cutterhead rotational speed is 6 r/min. The technical superiority of high-pressure water-jet-assisted rock breaking technology is highlighted and it provides guidance for the excavation parameter selection of high-pressure hydraulically coupled rock-breaking TBM.

EVOLUTION OF LIQUID WATER CONTENT IN A SEA FOG CONTROLLED BY A HIGH-PRESSURE PATTERN

On March 16–17, 2008, a sea fog occurred in Dianbai in the west of Guangdong Province and was accompanied by a high-pressure synoptic system. Using comprehensive observation datasets, this study analyzes the evolution of liquid water content during this sea fog and investigates the relationships between liquid water content and the average diameters and count densities of fog droplets, air temperature, wind speed and turbulence exchanges. The main results are presented as follows. (1) The sea fog showed a quasi-periodic oscillation characteristic, i.e., it developed, disappeared and then developed again. (2) During the sea fog, the number of fog droplets changed significantly while the changes in average diameter of the fog droplets were relatively small. The development and disappearance of the sea fog correlated significantly with the fog droplet numbers. (3) The air-cooling mechanism played a significant role in sea fog formation and development. However, the influences of this mechanism were not evident during fog persistence. (4) During sea fog formation, weak turbulence exchanges were helpful for fog formation. During sea fog development and persistence, liquid water content increased when turbulence exchanges weakened, and vice versa. The changes in turbulence exchanges were closely related to the quasi-periodic oscillations observed in sea fog presence.

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.

A Numerical Study on the Extinguishing Performances of High-Pressure Water Mist on Power-Transformer Fires for Different Flow Rates and Particle Velocities

In order to study the extinguishing performance of high-pressure-water-mist-based systems on the fires originating from power transformers the PyroSim software is used.Different particle velocities and flow rates are considered.The evolution laws of temperature around transformer,flue gas concentration and upper layer temperature of flue gas are analyzed under different boundary conditions.It is shown that the higher the particle velocity is,the lower the smoke concentration is,the better the cooling effect on the upper layer temperature of flue gas layer is,the larger the flow rate is and the better the cooling effect is.

High-pressure capacity expansion and water injection mechanism and indicator curve model for fractured-vuggy carbonate reservoirs

Water injection for oil displacement is one of the most effective ways to develop fractured-vuggy carbonate reservoirs.With the increase in the number of rounds of water injection,the development effect gradually fails.The emergence of high-pressure capacity expansion and water injection technology allows increased production from old wells.Although high-pressure capacity expansion and water injection technology has been implemented in practice for nearly 10 years in fractured-vuggy reservoirs,its mechanism remains unclear,and the water injection curve is not apparent.In the past,evaluating its effect could only be done by measuring the injection-production volume.In this study,we analyze the mechanism of high-pressure capacity expansion and water injection.We propose a fluid exchange index for high-pressure capacity expansion and water injection and establish a discrete model suitable for high-pressure capacity expansion and water injection curves in fractured-vuggy reservoirs.We propose the following mechanisms:replenishing energy,increasing energy,replacing energy,and releasing energy.The above mechanisms can be identified by the high-pressure capacity expansion and water injection curve of the well HA6X in the Halahatang Oilfield in the Tarim Basin.By solving the basic model,the relative errors of Reservoirs I and II are found to be 1.9%and 1.5%,respectively,and the application of field examples demonstrates that our proposed high-pressure capacity expansion and water injection indicator curve is reasonable and reliable.This research can provide theoretical support for high-pressure capacity expansion and water injection technology in fracture-vuggy carbonate reservoirs.

A study of hydrate plug formation in a subsea natural gas pipeline using a novel high-pressure flow loop

The natural gas pipeline from Platform QKI8-1 in the southwest of Bohai Bay to the onshore processing facility is a subsea wet gas pipeline exposed to high pressure and low temperature for a long distance. Blockages in the pipeline occur occasionally. To maintain the natural gas flow in the pipeline, we proposed a method for analyzing blockages and ascribed them to the hydrate formation and agglomeration. A new high-pressure flow loop was developed to investigate hydrate plug formation and hydrate particle size, using a mixture of diesel oil, water, and natural gas as experimental fluids. The influences of pressure and initial flow rate were also studied. Experimental results indicated that when the flow rate was below 850 kg/h, gas hydrates would form and then plug the pipeline, even at a low water content （10%） of a water/oil emulsion. Furthermore, some practical suggestions were made for daily management of the subsea pipeline.

循环冷却水系统的电化学水质稳定技术案例分析

水垢沉积和金属腐蚀会导致循环冷却水系统传热效率下降和能耗增加,严重影响工业生产的安全稳定运行。以某厂循环水系统的电化学除垢设备为案例,通过分析其处理效果和经济效益,为电化学技术处理循环冷却水的应用推广提供依据。现场所得运行数据表明,该厂所采用的电化学除垢设备能够有效改善水质,防止结垢,控制循环冷却水系统的腐蚀情况。每年减少循环水系统补水量和排污量各4.38×10^(5) t,并显著降低药剂投加量。经济核算显示该电化学系统每年可节省约212.9万元。

新型电化学水处理装置及重要参数

近年来,电化学水处理设备因其环境相容性及多功能性而受到极大的关注。针对现有电化学设备的不足,设计了一款除垢刮刀外置的新型电化学水处理设备。该设备因除垢刮刀外置而不占用电解室内部过多空间,新颖的滚筒型设计能够同步完成吸垢、脱水工作,在保证电解反应进行的同时减少水资源的浪费。为了验证不同参数下水处理的效果,仿照该设备阴阳极电解区的原型搭建了一款小型电解槽实验平台,完成了硬度测试与COD去除效果的单流通与循环流实验。通过综合对比发现:当电流密度为10.88 mA/cm^(2),循环水流量为10 L/h,电极板间距为5 mm时,水处理效果最佳,此时循环水的硬度去除率达到19.6%~24.46%,单位面积、单位时间结垢量为13.7 g/(h·m^(2)),单位水垢重量能耗低至0.16 kWh/g,COD的浓度由起初的106 mg/L降至18.8 mg/L,总去除率高达82.26%。总体来说,该电化学系统有着较好的除垢及降解有机物的效果,能够为未来电化学设备的研发或电化学理论的深入研究提供一定的借鉴与参考。

火焰清理机高压水除鳞装置的优化

针对板坯火焰清理机高压水除鳞装置除鳞效果差的问题,采取了调整高压水除鳞装置的位置、在高压水管增开排空管道以及将高压水除鳞装置的整体框架改为可拆卸式结构的优化措施,结果表明,板坯表面质量得到提高,同时减少了热坯急冷变形弯曲的现象,上述措施简单、可靠、合理,易于实现。

基于正交实验的电化学法处理循环冷却水的应用研究

为解决循环冷却水成垢问题,采用实验室小试和中试研究相结合的方法,以广西柳州钢铁集团有限公司焦化厂的循环冷却水为研究对象,通过正交实验设计,探索了阴极极板材料、极板间距、电压、反应时间4个因素的交互影响,构建了正交实验表。实验结果表明,阴极材料的选择和实验参数的调整对电化学去除循环冷却水中Ca^(2+)和Cl^(-)的效果具有明显影响。极差分析结果显示,阴极材料对除垢效果的影响最为显著,而电压对除氯效果的影响最为显著。通过中试研究对小试实验结果进行验证,取得了显著的经济效益。

论电化学循环水处理设备在化工企业实际应用效果

随着水资源的日益紧缺,环保压力的增加,循环水系统作为企业水资源的主要消耗者,节约循环水和减少排污对企业具有重要的经济利益。对电化学设备在某化工企业6 400 m^(3)/h循环量系统中的应用情况进行了技术和经济分析。电化学设备运行后,循环水系统的水质达到了设计要求,且优于《工业循环冷却水处理设计规范》(GB/T 50050—2017)的现行国标标准;电化学设备运行后,平均每日减少用水量为324m^(3),预期年节水量为11.6万m^(3);电化学设备运行一个多月累计节约药剂费用超过7 000元,预计全年节约药剂费用5万元~7万元。电化学设备在循环水系统中的应用效果良好,在水质控制、节水减排和减少化学药剂使用等方面均有显著效果。

蒸发式冷凝器结垢分析与处理

蒸发式冷凝器作为一种综合了风冷式冷凝器和冷却塔的高效换热器,在节能减排领域具有良好的应用前景,但其工作过程中循环冷却水的浓缩决定了在使用时不可避免会遇到如结垢、腐蚀、微生物滋生等影响设备安全和正常运行的问题,本文通过介绍蒸发式冷凝器原理及目前限制其应用的主要难点,对比分析常见蒸发冷循环冷却水处理方式的优劣并与电化学水处理(EST)技术进行对比,结合实际项目改造数据,得出EST设备在去除结垢因子、减少蒸发式冷凝器盘管结垢、抑制腐蚀以及循环水系统杀菌灭藻方面有较好的效果,是目前值得推广的一种循环冷却水处理方式。

某半导体产业园区冷冻站节能改造研究

针对某半导体产业园区3套冷冻站的全年运行工况,表明过渡季及冬季系统运行能效偏低,具备较大节能潜力,且存在冷却水系统维护费用高和末端用户空调费用结算困难问题。通过采用匹配用户需求的节能改造方案,其包括3套冷冻水系统连通、2套冷却水系统连通、冷却水系统在线杀菌除垢、末端用户分区计量。依据改造后的运行数据结果可知,在3套冷冻水系统冷冻水供水温度符合要求的基础上,有效减少运行设备数量,可为同类型项目提供改造参考。

电化学水处理技术在工业循环水中的应用分析

介绍了电化学水处理技术在工业循环水中的应用原理,阐述了电化学水处理技术的特点,与其它水处理方法相比,电化学水处理技术在除垢、杀菌、防腐蚀、经济、环保等方面具有科学性、先进性、实用性。

高压水除鳞系统能效在线评估方法研究

高压水除鳞系统在线能效评估是以高压泵运行信号、除鳞信号、集管设计参数等数据,结合泵类设备做功机理模型,对该系统的能效进行在线评估,从而使辅助设备管理人员对设备异常做出判断,提升高压水系统的运行效率。

变频电磁除垢装置在李楼煤业的研究与应用

李楼煤业能源中心能源站循环系统设备和管道内部易产生腐蚀、结垢,造成设备、管道严重腐蚀,对能源站的稳定运行产生了严重影响。针对化学除垢+人工除垢的方案成本高,对各种化学药剂投放时间、投放精度的要求极高,很难适应矿区空调水系统的实际工作需求,人工除垢则存在着效率低、盲区大、安全性差的不足问题,提出了一种新的变频电磁除垢装置,能够产生交变的高频电磁场,管道内的水分子在经过高频电场时能够被磁化,降低水质中各种结垢离子的结晶性,进而提升防垢效果。通过挂片试验对比,在采用电磁除垢装置以后,能够将空调水系统中的平均腐蚀速率降低67.7%,有效地提升了李楼煤业空调系统的应用可靠性。

中水回用技术的研究与应用

应对水资源短缺的有效方法是中水循环利用技术。本文针对污水现状、来源及处理工艺的不同,探讨了中水回用的概念、技术应用的比较、污水指标及处理工艺机理方法的比较。论述了采用膜分离技术和电化学吸附除垢除盐技术处理并回收中水,详细说明为了实现水资源最大程度的循环利用,将这些技术应用于废水再利用,可以为实现零排污奠定基础。