Evaluating Transfer and Pumping of Slurries From Pulsed Jet Mixed Vessels

2020 ◽  
Author(s):  
Carl W. Enderlin ◽  
Judith Ann Bamberger ◽  
Michael J. Minette
Keyword(s):  
Pressure Drop ◽  
Force Balance ◽  
Excessive Pressure ◽  
Buoyant Force ◽  
Hindered Settling ◽  
Pump Operation ◽  
Pulsed Jet ◽  
Transfer Line ◽  
Solids Concentration ◽  
Inlet Conditions

Abstract Due to gravity, solids in slurries will settle if density differences between the solids and liquid are positive (i.e., particle has a negative buoyant force) unless rheological properties and flow conditions are adequate to overcome the gravitational effects. The rate of settling depends on the force balance of the particle, which includes the surface forces associated with fluid rheology. Given the same fluid and solid properties, the larger and more dense particles tend to settle faster. When pumping slurry into a vessel at concentrations precluding hindered settling with insufficient mixing, particle and density distributions can result in preferential settling, creating stratification in the solids concentration within the vessel. For vessels with transfer line inlets located in the lower portion of the tank, the stratified solids concentration may be detrimental to the transfer system performance. Elevated concentrations of solids in the slurry entrained at the inlet to the transfer line can result in the effective viscosity or slurry bulk density exceeding the design limits of the pump. These conditions could result in plugging of the transfer line or onset of cavitation of the pumps because of excessive pressure drop. These conditions can be exacerbated with periodic inlet conditions existing at the transfer line inlet. Periodic conditions can result when vessel mixing is intermittent such as with pulsed jet mixers (PJM). The transfer line inlet conditions are impacted by the periodic nature of the PJM operations with respect to suspension of solids and their transport to the inlet of the transfer line. A scaling approach is presented, and corresponding test requirements are developed for assessing the prevention of plugging the pipeline. Line plugging mechanisms are addressed that exclude plugging due to steady-state high-density slurry entering the transfer line and reducing the net positive suction head available (NPSHA) at the pump inlet to below that required for pump operation. Items considered include the transition to reduced relative flow velocities, such that the critical pipe velocity for solids deposition, Ucd, is not maintained, and segregation of heavy solids during the transport. The recommended requirements to prevent plugging include: • Limits for viscosity and density for entrained slurry to prevent the pressure drop in the pipeline from exceeding pump capacity. • Limits for viscosity and density for entrained slurry to prevent the net positive suction head available (NPSHA) from falling below the net positive suction head required (NPSHR) for operating the pump. • Transfer line velocity and flow rate requirements to maintain solids in suspension, while avoiding line plugging that results from deposition of solids within the transfer line. This paper describes the development of the scaling and testing requirements to verify that proposed approaches for transfer and pump out are appropriately developed for operational success within the plant operating windows.

Effect of Inlet Conditions on the Pressure Drop in Confined Vortex Flow

2005 ◽  
Vol 21 (6) ◽  
pp. 1128-1133 ◽  
Author(s):  
Ali M. Jawarneh ◽  
Georgios H. Vatistas
Keyword(s):  
Pressure Drop ◽  
Vortex Flow ◽  
Inlet Conditions

Study of the pressure drop in dust scrubber affected by liquid flowability

2019 ◽  
Vol 233 (5) ◽  
pp. 1066-1073 ◽  
Author(s):  
Xiaochuan Li ◽  
Tao Wei ◽  
Xinhao Xu ◽  
Reyna M Knight ◽  
Jiahang Li
Keyword(s):  
Pressure Drop ◽  
Drag Coefficient ◽  
Linear Relationship ◽  
Gas Phase ◽  
Force Balance ◽  
Liquid Level ◽  
Gas Velocity ◽  
Two Phase ◽  
Total Drag ◽  
Quadratic Curve

The complexity of the gas-liquid two-phase flow results in equally complicated pressure drop characteristics for self-excited wet dust scrubbers. In this paper, the pressure drop of the dust scrubber was studied by measuring the total pressure drop R and the differential liquid level Δ H versus the gas velocity v at different initial liquid level b0 values, combined with the liquid flowability. The results showed that the dust scrubber varied its total drag coefficient by changing the differential liquid level Δ H of the liquid-phase and then adjusting the gas-liquid two-phase force balance ahead of and behind the choke. Under the influence of liquid flowability, the throttling strength α exhibited a linear relationship with the gas velocity of the dust scrubber when b0 ≤ 0 mm. The Δ H-v and R- v characteristics of the dust scrubber varied with different values of b0 and v. When b0 > 0, the Δ H-v curve and R- v curve exhibited an explicit quadratic curve relationship. When b0 ≤ 0 mm, the Δ H-v curve and R- v curve exhibited an explicit linear relationship, where the Δ H-v curves can be expressed by a linear equation Δ H = khv+Δ H0, and the gas-phase pressure drop R can be approximately calculated using the differential liquid level Δ H. The liquid flowability can change the choke-sectional to change the total drag coefficient, which reduced in multiple folds with an increase in the gas velocity.

Heating and Efficiency Comparison of a Fischer-Tropsch (FT) Fuel, JP-8+100, and Blends in a Three-Cup Combustor Sector

2012 ◽  
Author(s):  
Anna E. Thomas ◽  
Nikita T. Saxena ◽  
Dale T. Shouse ◽  
Craig Neuroth ◽  
Amy Lynch ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Pressure Drop ◽  
Performance Data ◽  
Thermal Impact ◽  
Fischer Tropsch ◽  
Commercial Use ◽  
Turbine Efficiency ◽  
Efficiency Comparison ◽  
Inlet Conditions

In order to realize alternative fueling for military and commercial use, the industry has set forth guidelines that must be met by each fuel. These aviation fueling requirements are outlined in MIL-DTL-83133F(2008) or ASTM D 7566-Annex standards and are classified as “drop-in” fuel replacements. This paper provides combustor performance data for synthetic-paraffinic-kerosene- (SPK-) type (Fisher-Tropsch (FT)) fuel and blends with JP-8+100, relative to JP-8+100 as baseline fueling. Data were taken at various nominal inlet conditions: 75 psia (0.52 MPa) at 500 °F (533 K), 125 psia (0.86 MPa) at 625 °F (603 K), 175 psia (1.21 MPa) at 725 °F (658 K), and 225 psia (1.55 MPa) at 790 °F (694 K). Combustor performance analysis assessments were made for the change in flame temperatures, combustor efficiency, wall temperatures, and exhaust plane temperatures at 3%, 4%, and 5% combustor pressure drop (%ΔP) for fuel:air ratios (F/A) ranging from 0.010 to 0.025. Significant general trends show lower liner temperatures and higher flame and combustor outlet temperatures with increases in FT fueling relative to JP-8+100 fueling. The latter affects both turbine efficiency and blade/vane life. In general, 100% SPK-FT fuel and blends with JP-8+100 produce less particulates and less smoke and have lower thermal impact on combustor hardware.

Compact Model of Slug Flow in Microchannels

2007 ◽  
Author(s):  
Dong Rip Kim ◽  
Jae-Mo Koo ◽  
Chen Fang ◽  
Julie E. Steinbrenner ◽  
Eon Soo Lee ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Liquid Water ◽  
Slug Flow ◽  
Flow Behavior ◽  
Contact Angles ◽  
Proton Exchange ◽  
Force Balance ◽  
Compact Model ◽  
Two Phase ◽  
Coverage Ratio

This paper presents a theoretical investigation of the movement of liquid droplets and slugs in hydrophobic microchannels and develops a compact model for this type of two-phase flow. This model is used in the prediction of pressure drop and liquid water coverage ratio, key parameters in the operation of Proton Exchange Membrane Fuel Cells (PEMFC), the primary motivation for this work. A semi-empirical, periodic-steady two-phase separated flow compact model is formulated to characterize the slug flow behavior. The momentum equation includes the effects of acceleration, friction and surface tension on the pressure drop. The model considers spatial changes in slug velocity through the use of a force balance formulation. The model uses a departure scheme that computes slug size and shape at entrainment. The steady state slug flow compact model is capable of predicting liquid water coverage ratio and pressure drop using liquid and gas flow rates and advancing/receding triple point contact angles as its only inputs. The results indicate that the pressure drop increases as the droplet formation frequency increases.

Experimental Study on Characteristics of Condensation and Flow Resistance Inside Horizontal Corrugated Low Finned Tubes

2018 ◽  
Author(s):  
Bin Ren ◽  
Xiaoying Tang ◽  
Hongliang Lu ◽  
Dongliang Fu ◽  
Yannan Du ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Flow Resistance ◽  
Vapor Quality ◽  
Transfer Coefficients ◽  
Finned Tubes ◽  
Heat Transfer Coefficients ◽  
Inlet Conditions

It is the simplest and most feasible method to enhance heat transfer by replacing the smooth tube with various kinds of special-shaped enhanced tubes. In this paper, the characteristics of condensation and flow resistance inside horizontal corrugated low finned tubes were studied experimentally. The effects of steam inlet conditions and condensation tubes structural parameters were analyzed. The results showed that the heat transfer performance inside corrugated low finned tubes was greater than that inside smooth tubes. Like inside smooth tubes, the heat transfer coefficients increased with the vapor quality and steam mass flux. But the enhancement rate showed the opposite trend. And the heat transfer coefficients inside corrugated low finned tubes increased with the decrease of pitch and increase of protrusion height. Meanwhile, the variation trend of pressure drop gradient changing with inlet conditions and construal parameters was consistent with trend of heat transfer coefficient. The performance evaluation criteria were used to evaluate the comprehensive performance. It was found that the maximum performance evaluation factor was acquired at the minimum vapor quality and mass flux. The maximum value was 2.24 happened in the tube with pitch of 6 mm and height of 0.7mm. Finally, both the correlation for heat transfer coefficient and correlation for pressure drop gradient were developed by fitting experimental data. And this would provide calculation foundations for the design of horizontal condensers with corrugated low finned tubes.

On the Penetrator Nose Drag Measurements

2010 ◽  
Author(s):  
Joseph P. Holland ◽  
Yesenia Tanner ◽  
Phillip A. Schinetsky ◽  
Semih Olcmen ◽  
Stanley Jones
Keyword(s):  
Wind Tunnel ◽  
Power Series ◽  
Viscous Fluid ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Terminal Velocity ◽  
Force Balance ◽  
Supersonic Wind Tunnel ◽  
Buoyant Force ◽  
Nose Shape

In the current study, a rigid body penetrator nose shape that is optimized for minimum penetration drag [1] has been tested to determine the aerodynamic drag of such a penetrator in comparison to three additional nose shapes. Other nose shapes tested were an ogive cylinder, a 3/4 power series nose, and a standard cone. Fineness ratio for the studied nose geometries was chosen as l/d = 1 to maximize variation of the aerodynamic drag forces acting on the nose shapes. This paper discusses the measurements carried out in the University of Alabama’s 6″ × 6″ supersonic wind tunnel, using a 4 component force balance system. In separate experiments, drop tests were made in a viscous fluid to determine the skin-friction effects on these nose shapes. Supersonic wind-tunnel experiments were performed on each of the nose shapes at nine different Mach numbers ranging from 2 to 3.65. Results show that the nose shape optimized for penetration has the lowest drag coefficient of all the shapes at each Mach number within an uncertainty of 5.75%. In the viscous flow drop-test experiments, each nose shape was dropped from rest through water and then separately through viscous fluid (Nu-Calgon vacuum pump oil) under freefall conditions. Each drop was recorded via videotape, and the video was then analyzed to find the terminal velocity of each individual nose shape. Using classical dynamics equations, the weight, buoyant force, and experimentally determined terminal velocity are used to determine the drag force applied to each nose cone shape. Results indicate that while the optimal shape has a lesser drag coefficient than tangent ogive and the cone, the 3/4 power series shape is observed to have the least drag coefficient. In addition to the experiments performed, results on further investigation of the optimal nose shape for penetration are presented. The nose shape has been split into a series of line segments, and a program written has been utilized to search through numerical space for the combination of line segment slopes that produces the nose geometry with the lowest nose shape factor. The results of the numerical analysis in this study point to a different nose shape than the “optimal nose” shape tested in the current study.

One-Dimensional Models of the Human Biliary System

2006 ◽  
Vol 129 (2) ◽  
pp. 164-173 ◽  
Author(s):  
W. G. Li ◽  
X. Y. Luo ◽  
A. G. Johnson ◽  
N. A. Hill ◽  
N. Bird ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Cystic Duct ◽  
Biliary System ◽  
Maximum Pressure ◽  
Equivalent Diameter ◽  
Excessive Pressure ◽  
Subsequent Formation ◽  
One Dimensional ◽  
Normal Human ◽  
Dimensional Models

This paper studies two one-dimensional models to estimate the pressure drop in the normal human biliary system for Reynolds number up to 20. Excessive pressure drop during bile emptying and refilling may result in incomplete bile emptying, leading to stasis and subsequent formation of gallbladder stones. The models were developed following the group’s previous work on the cystic duct using numerical simulations. Using these models, the effects of the biliary system geometry, elastic property of the cystic duct, and bile viscosity on the pressure drop can be studied more efficiently than with full numerical approaches. It was found that the maximum pressure drop occurs during bile emptying immediately after a meal, and is greatly influenced by the viscosity of the bile and the geometric configuration of the cystic duct, i.e., patients with more viscous bile or with a cystic duct containing more baffles or a longer length, have the greatest pressure drop. It is found that the most significant parameter is the diameter of the cystic duct; a 1% decrease in the diameter increases the pressure drop by up to 4.3%. The effects of the baffle height ratio and number of baffles on the pressure drop are reflected in the fact that these effectively change the equivalent diameter and length of the cystic duct. The effect of the Young’s modulus on the pressure drop is important only if it is lower than 400Pa; above this value, a rigid-walled model gives a good estimate of the pressure drop in the system for the parameters studied.

Large Eddy Simulation of a Helical Coil Steam Generator Test Section

2017 ◽  
Author(s):  
Jonathan K. Lai ◽  
Elia Merzari ◽  
Marilyn Delgado ◽  
Samuel J. Lee ◽  
Saya Lee ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Large Eddy Simulation ◽  
Steam Generator ◽  
Test Section ◽  
Helical Coil ◽  
Reynolds Stresses ◽  
Eddy Simulation ◽  
High Heat Transfer ◽  
Large Eddy ◽  
Inlet Conditions

The helical coil steam generator (HCSG) is a compact heat exchanger that can have high heat transfer even when the pressure drop is low. This makes it advantageous in small modular reactors and high-temperature reactor designs. In order to investigate the fluid phenomena around these helical banked tubes, a test section was built at Texas A&M University to represent flow across two half-rods within HCSG. This study focuses on the validation of large eddy simulation (LES) for this particular geometry. Pressure tap and particle image velocimetry (PIV) measurements have been recorded at an inlet Reynolds number of 8643, and both mean and fluctuating data is compared with the numerical results. The highly scalable spectral-element code Nek5000 has been used to produce the LES calculations. First, simulations of varying polynomial order expansions are made to determine the spatial resolution required to capture the turbulent scales. Then, simulations with different inlet conditions are compared with experimental data. The pressure drop shows good agreement with pressure tap measurements while velocity shows similar characteristics with PIV. Furthermore, the components of the Reynolds stresses and modes from proper orthogonal decomposition have been developed to validate the physics captured.

Near-Critical CO2 Flow Measurement and Visualization

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Farzan Kazemifar ◽  
Dimitrios C. Kyritsis
Keyword(s):  
Pressure Drop ◽  
Critical Point ◽  
Flow Structure ◽  
Greenhouse Gas Emission ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Inlet Temperature ◽  
Mass Flow Rates ◽  
Inlet Conditions ◽  
Co2 Flow

Near-critical CO2 flow has been studied because of its potential application in carbon dioxide capture and sequestration, which is one of the proposed solutions for reducing greenhouse gas emission. Near the critical point the thermophysical properties of the fluid undergo abrupt changes that affect the flow structure and characteristics. Pressure drop across a stainless steel tube, 2 ft long with 0.084 in. ID, at different inlet conditions and mass flow rates have been measured. The effects of variations of inlet conditions have been studied. The results show extreme sensitivity of pressure drop to inlet conditions especially inlet temperature in the vicinity of the critical point. Also, shadowgraphs have been acquired to study the flow structure qualitatively.

scholarly journals Experimental Study on the Removal of Real Exhaust Pollutants from a Diesel Engine by Activated Carbon

2019 ◽  
Vol 9 (15) ◽  
pp. 3175 ◽  
Author(s):  
Zongyu Wang ◽  
Hailang Kuang ◽  
Jifeng Zhang ◽  
Lilin Chu ◽  
Yulong Ji
Keyword(s):  
Activated Carbon ◽  
Pressure Drop ◽  
Removal Efficiency ◽  
Industrial Applications ◽  
Pollutant Removal ◽  
Exhaust Gas ◽  
Excessive Pressure ◽  
Secondary Pollution ◽  
Pm Removal ◽  
Thermal Stability Of

So far, most of the experimental researchers studying the removal of diesel exhaust pollutants have done so with simulated exhaust gas, which cannot demonstrate the ability of catalysts accurately. Because activated carbon (AC) has low price, no secondary pollution, good adsorption performance, and certain catalytic activity, it has good application prospects in the field of marine exhaust pollutant removal. In this paper, the removal of particulate matter (PM), carbon monoxide (CO), and NOx from real exhaust gas by AC was studied. The results show that PM removal efficiency reached up to 77%, while the pressure drop increased with running time. AC may degenerate to some extent with the increase of temperature, resulting in a negative removal efficiency of CO. The denitration efficiency of AC was up to 34.5% without urea, and further increased to 44.8% after spraying urea, still a distance from industrial applications. In the future, it may be necessary to install a fan to compensate the reactor or to backwash the reactor to avoid excessive pressure drop. The thermal stability of the AC also needs to be improved. To increase the denitration performance, it may be helpful to modify the AC or impregnate other metal oxides.

Sign in / Sign up

Export Citation Format

Share Document