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.

Strengthening pelletization of manganese ore fines containing high combined water by high pressure roll grinding and optimized temperature elevation system

Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.

Rock Breaking Performance of a Pick Assisted by High-pressure Water Jet under Different Configuration Modes

In the process of rock breaking, the conical pick bears great cutting force and wear, as a result, high-pressure water jet technology is used to assist with cutting. However, the effect of the water jet position has not been studied for rock breaking using a pick. Therefore, the models of rock breaking with different configuration modes of the water jet are established based on SPH combined with FEM. The effect of the water jet pressure, distance between the jet and the pick bit, and cutting depth on the rock breaking performance as well as a comparison of the tension and compression stress are studied via simulation; the simulation results are verified by experiments. The numerical and experimental results indicate that the decrease in the rates of the pick force obviously increases from 25 MPa to 40 MPa, but slowly after 40 MPa, and the optimal distance between the jet and the pick bit is 2 mm under the JFP and JSP modes. The JCP mode is proved the best, followed by the modes of JRP and JFP, and the worst mode is JSP. The decrease in the rates of the pick force of the JCP, JRP, JFP, and JSP modes are up to 30.96%, 28.96%, 33.46%, 28.17%, and 25.42%, respectively, in experiment. Moreover, the JSP mode can be regarded as a special JFP model when the distance between the pick-tip and the jet impact point is 0 mm. This paper has a dominant capability in introducing new numerical and experimental method for the study of rock breaking assisted by water jet and electing the best water jet position from four different configuration modes.

Various admixtures to mitigate the long-term strength retrogression of Portland cement cured under high pressure and high temperature conditions

In order to investigate the problem of long-term strength retrogression in oil well cement systems exposed to high pressure and high temperature(HPHT)curing conditions,various influencing factors,including cement sources,particle sizes of silica flour,and additions of silica fume,alumina,colloidal iron oxide and nano-graphene,were investigated.To simulate the environment of cementing geothermal wells and deep wells,cement slurries were directly cured at 50 MPa and 200?C.Mineral compositions(as determined by X-ray diffraction Rietveld refinement),water permeability,compressive strength and Young’s modulus were used to evaluate the qualities of the set cement.Short-term curing(2e30 d)test results indicated that the adoption of 6 m m ultrafine crystalline silica played the most important role in stabilizing the mechanical properties of oil well cement systems,while the addition of silica fume had a detrimental effect on strength stability.Long-term curing(2e180 d)test results indicated that nano-graphene could stabilize the Young’s modulus of oil well cement systems.However,none of the ad-mixtures studied here can completely prevent the strength retrogression phenomenon due to their inability to stop the conversion of amorphous to crystalline phases.

Key technologies for construction of Jinping traffic tunnel with an extremely deep overburden and a high water pressure

Jinping traffic tunnel is one of the deepest traffic tunnels in the world with a maximum overburden of 2 375 m and the overburden over 73% of its total length is larger than 1 500 m. The tunnel is 17.5 km long and designed to provide a shortcut road between two hydropower stations： Jinping I and Jinping II of the Jinping Hydropower Project, located on Yalong River, Liangshan State, Sichuan Province, China. The tunnel is so deep that building any shafts is impossible. The construction starts from both ends （east and west ends）, and the construction length from the west end is 10 km with a blind heading. This paper deals with an overview of this project and analysis of the engineering features, as well as key technologies developed and applied during the construction, including geological prediction, rock burst prevention under a super high in-situ stress, sealing of groundwater with a high pressure and big flow rate, ventilation for a blind heading of 10 km, wet spraying of shotcrete at zones of rock burst and rich water, etc. The application of the new technologies to the construction achieved a high quality tunnel within the contract period.

Numerical analysis on coal-breaking process under high pressure water jet

Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.

The numerical study of wave-induced pore water pressure response in highly permeable seabed

The coupling numerical model of wave interaction with porous medium is used to study wave- induced pore water pressure in high permeability seabed. In the model, the wave field solver is based on the two dimensional Reynolds-averaged Navier-Stokes （RANS） equations with a k-s closure, and Forchheimer equations are adopted for flow within the porous media. By introducing a Velocity-Pressure Correction equation for the wave flow and porous flow, a highly efficient coupling between the two flows is implemented. The numerical tests are conducted to study the effects of seabed thickness, porosity, particle size and intrinsic permeability coefficient on regular wave and solitary wave-induced pore water pressure response. The results indicate that, as compared with regular wave-induced, solitary wave-induced pore water pressure has larger values and stronger action on seabed with different parameters. The results also clearly show the flow characteristics of pore water flow within seabed and water wave flow on seabed. The maximum pore water flow velocities within seabed under solitary wave action are higher than those under regular wave action.

Stress characteristics of surrounding rocks for inner water exosmosis in high-pressure hydraulic tunnels

Seepage and stress redistribution are the main factors affecting the stability of surrounding rock in high-pressure hydraulic tunnels.In this work,the effects of the seepage field were firstly simplified as a seepage factor acting on the stress field,and the equilibrium equation of high pressure inner water exosmosis was established based on physical theory.Then,the plane strain theory was used to solve the problem of elasticity,and the analytic expression of surrounding rock stress was obtained.On the basis of criterion of Norway,the influences of seepage,pore water pressure and buried depth on the characteristics of the stress distribution of surrounding rocks were studied.The analyses show that the first water-filling plays a decisive role in the stability of the surrounding rock; the influence of seepage on the stress field around the tunnel is the greatest,and the change of the seepage factor is approximately consistent with the logarithm divergence.With the effects of the rock pore water pressure,the circumferential stress shows the exchange between large and small,but the radial stress does not.Increasing the buried depth can enhance the arching effect of the surrounding rock,thus improving the stability.

High temperature and high pressure rheological properties of high-density water-based drilling fluids for deep wells

To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.

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.

High Pressure-Differential Thermal Analysis and Ultrasonic Wave Amplitude Analysis of Ice-Water Equilibrium at 1.5-5.0 GPa

Water is the most active component in all geological systems. It has an importanteffect on the physical properties of minerals and melts. It also plays a key role in the evolutionof the Earth. Accurate thermodynamics data on water are currently confined to pressures below1.0 GPa and temperatures below 900℃. Presented in this paper are new data available on theP-T properties of water at pressures up t0 5. 0 GPa, developed from differential thermal analysis and ultrasonic wave amplitude analysis. It has been found that there may exist anotherternary point at 3. 0 GPa and that ultrasonic wave amplitude change of ice-water transitionshows two inflection points above 2. 0 GPa, consistent with the two peaks of differential thermal curves above 2. 0 GPa. It may be a new phenomenon which needs further study.

A COMPARISON OF HIGH PRESSURE PHASE EQUILIBRIA AND ORITIOAL PHENOMENA FOR AQUEOUS C_4-ALKANE-SYSTEMS WITH OTHER ALKANES SYSTEMS

In an optical high--pressure autoclave with saphire windows and magnetic stirring, phase equilibria data in mixtures of water-n--butane and water-iso--butane were measured in a temperature range from 500K to 600K and at a pressure from 10MPa to 300MPa. The critical curves of these systems start at the critical point of pure water and tend to higher pressures and lower temperatures. These curves pass a temperature minima 624K and 625K respectively and then tend to a high temperature and pressure. Excess volumes on the phase equilibria surface were given. The results are discussed in view of the phase equilibria of other water--n--alkane systems.

High Pressure Water-Jet Technology for the Surface Treatment of Al-Si Alloys and Repercussion on Tribological Properties

Recent developments in high pressure water-jet technology have brought the process to the forefront as a means of surface treatment. Water jet technology offers cleaning, cutting, processing as well as potential refinement of surface properties. By adapting the process parameters the surface characteristics can be changed while the profile remains the same. In the present study, water-jet technology was used for the surface treatment of Al-Si alloy to investigate its effect on tribological properties. Dry sliding wear behavior was investigated against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration. Optical microscopy examination reveals that ploughing of grains, transgranular and intergranular propagation of cracks;are the mechanisms by which material is removed during water jet treatment. While, on the other hand, SEM observation of the wear track reveals that plastic deformation and delamination are the dominant wear mechanism during the wear process. Water jet treatment was compared to hot isostatic pressing in terms of its effects on wear resistance and surface porosity of Al-Si alloy. It was found that, hot isostatic pressing reduces the total amount of porosity at the expanse of hardness while water jet treatment produces a compressed surface having higher hardness and compressive residual stress, which ultimately increases wear resistance.

Experimental study of water effects on gas desorption during highpressure water injection

For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion. The law of water effect on gas desorption was obtained after water invasion through experiment for the first time. The results show that water＇s later invasion not only can make the quantity of gas dcsorp- tion greatly reduced, but also can make gas desorption end early. Therefore, when evaluating the applications of high-pressure water injection to increase gas extraction efficiency, we should take water damaging effects on gas desorption into account.

Forward-headed structure change of acetic acid–water binary system by stimulated Raman scattering

The acetic acid-water binary system is a classical hydroxy-carboxy mixed system, while new and interesting phenomena appear under stimulated Raman scattering(SRS).Compared with the weaker signal of the acetic acid-water binary system obtained in spontaneous Raman scattering, SRS provides a finer band and a relatively distinct structural transition point.The structural transformation points are respectively at 30% and 80% by volume ratio under the condition of spontaneous Raman spectroscopy, while they are respectively at 15% and 25% under the condition of SRS.This phenomenon is attributed to the generation of laser induced plasma and shockwave induced dynamic high pressure environment during SRS.

Survey-Based Analysis of Water Consumption Law in High-Rise Public Buildings and Water-Saving Performance of Pressure-Reducing Measures

Facing the contradiction of water scarcity and water wastage in most cities of China, this study aims at probing into the factors influencing water-use efficiency and assessing water-saving potential by adopting pressure control measures based on field survey conducted in 23 high-rise buildings in Suqian, China and laboratory tests. Results showed that per capita water consumption (PCWC) exceeding water consumption norms is common in these buildings. The hourly water consumption variation law is quite different among different types of buildings. These differences should be considered in designing building water supply systems to lower water and energy consumption. On the basis of correlation analysis, the order of factors influencing the PCWC follows average tap water pressure, percapita building area, and building age, suggesting pressure management in high-rise buildings is a key water-saving measure. Field tests of outflow characteristics under different water pressures indicated that over-pressure outflow (OPO) is a common cause of water wastage in buildings, however, no branch pipe pressure control measures were found in all the surveyed buildings. Laboratory tests showed that branch pipe pressure-reducing measures can lower water consumption and improve the comfortability of use as well. Therefore, in addition to applying high efficiency water-saving devices, we strongly recommend that branch pipe pressure-reducing measures should be strictly implemented in designing new building water supply systems and reconstruction of existing old building water supply systems, thereby, promoting water, energy saving and development of green building.

Effects of high-pressure activated slightly acidic electrolyzed water on cleaning and sterilization of pig transfer vehicles

The establishment of biosafety system is of enormous importance to the livestock and poultry production in terms of mitigating the transmission of diseases and implementing regional prevention and control measures.However,the current sterilization technology presents several drawbacks,including time-consuming procedures,chemical residues,and challenges in treating the sewage after rinsing.In this study,a novel cleaning and sterilization method that combines slightly acidic electrolyzed water and high pressure water-jet was developed.An orthogonal test was conducted to examine the correlation between high-pressure conditions and the various non-structural parameters on the efficacy of sterilization rate.In a field test,the effectiveness of the technology in cleaning pig transfer vehicles was evaluated by the total plate count and variations of community composition.The findings revealed that the combination of process parameters,including an available chlorine concentration of 200 mg/L,rinsing pressure of 170 bar,rinsing duration of 10 s,and residence time of 15 min,resulted in a removal rate of colony concentration on the surface of pig transfer vehicles of(96.50±0.91)%.Moreover,it was demonstrated to effectively inhibit a variety of pathogenic bacteria.The innovative cleaning system has the potential to replace traditional methods and reduces pollution while saving time and labor.It introduces a novel approach for sterilization of transportation in livestock and poultry farms as well as the biosafety construction of the animal husbandry.

Experimental Study on High Electrical Breakdown of Water Dielectric

By means of a coaxial apparatus, microsecond charging have been carried out with ferent ethylene glycol concentrations of ethylene pressurized water breakdown experiments with different surface roughness of electrodes and difglycol/water mixture. The experimental results about the breakdown stress and the effective time are presented. The breakdown stress is normalized to the situation that the effective time is transformed to 1 μs and analyzed. The conclusions are as follows： （1） the breakdown stress formula is modified to E = 0.561MA^-1/10teff^-1/^NP^1/8 ;（2） the coefficient M is significantly increased by surface polishing and ethylene glycol additive; （3） it is accumulative for the capacity of improving electrical breakdown strength for surface polishing, ethylene glycol additive, and pressurization, of which pressurization is the most effective method; （4） the highest stress of 235.5 kV/cm is observed in ethylene glycol/water mixture with an ethylene glycol concentration of 80% at a hydrostatic pressure of 1215.9 kPa and is about one time greater than that in pure water at constant pressure; （5） for pressurization and surface polishing, the primary mechanism to improve the breakdown strength of water dielectric is the increase in the breakdown time delay. Research results indicate great potential in the application of the high power pulse conditioning system of water dielectric.

Flow Characteristics of Crude Oil with High Water Fraction during Non-heating Gathering and Transportation

In order to ensure the safety of the non-heating gathering and transportation processes for high water fraction crude oil,the effect of temperature,water fraction,and flow rate on the flow characteristics of crude oil with high water fraction was studied in a flow experimental system of the X Oilfield.Four distinct flow patterns were identified by the photographic and local sampling techniques.Especially,three new flow patterns were found to occur below the pour point of crude oil,including EW/O&W stratified flow with gel deposition,EW/O&W intermittent flow with gel deposition,and water single-phase flow with gel deposition.Moreover,two characteristic temperatures,at which the change rate of pressure drop had changed obviously,were found during the change of pressure drop.The characteristic temperature of the first congestion of gel deposition in the pipeline was determined to be the safe temperature for the non-heating gathering and transportation of high water cut crude oil,while the pressure drop reached the peak at this temperature.An empirical formula for the safe temperature was established for oil-water flow with high water fraction/low fluid production rate.The results can serve as a guide for the safe operation of the non-heating gathering and transportation of crude oil in high water fraction oilfields.

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.