Effect of Connection Resistance between Cyclones and Backpass on Furnace Solids Suspension Density Profile and Circulation Rates in CFB

The connection section between cyclones and backpass is an important configuration in multi-cyclone circulating fluidized bed boilers (CFB). In this work, the resistance coefficient of different connection modes, and connection resistance distribution from each cyclone outlet to backpass (connection branch) in one mode are defined and calculated, in order to investigate their effects on furnace solids suspension density distribution and circulation rates. Three connection modes with different overall resistance coefficients were tested experimentally and analyzed by a 1.5-dimensional model in a four-cyclone scaling CFB apparatus. Both experimental and theoretical results show that, with larger overall resistance of a connection, there are more solids suspended in the furnace bottom and fewer in the top section. The investigation of the C-type connection has revealed that when the branch resistance of the connection decreases from branch No. 1–4, the solids suspension density and circulation rate from corresponding solids recycle loops (No. 1–4) increase. Moreover, the non-uniformity of connection branch resistance distribution will lead to uneven lateral solids suspension density distribution and circulation rates allocation. This effect is enhanced by growing superficial velocity.

Sagging Prevention for Hematite-Based Invert Emulsion Mud

The solids sagging in high-pressure high-temperature (HP/HT) reservoirs is a common challenge associated with hematite drilling fluids. This study provides a solution to hematite sagging in invert emulsion mud for HP/HT wells which involves the combination of Micromax (Mn3O4) with hematite. The particles of both weighting agents were characterized to address their mineralogical features. A Field formulation of the mud was used over a range of Micromax/hematite ratios (0/100, 20/80, and 30/70%) in laboratory experiments to address the sag performance and determine the optimal combination ratio. Then, density, emulsion stability, rheology, viscoelasticity, and filtration performance for the formulated mud were addressed. The tests were conditioned to 500 psi and 350 °F. The acquired results of sag tests indicated that incorporation of 30% Micromax solved the hematite sagging issue and brought the sag tendency within the recommended safe range. An insignificant reduction in mud density was observed upon the inclusion of Micromax, while the emulsion stability was obviously improved from 551 to 614 volts with the 30% Micromax mixture. The recommended 30/70% combination had almost no effect on plastic viscosity and yield point since they were increased by one unit, but the gel strength was improved resulting in flat rheology and better solids suspension capacity. The filtration behavior of the formulation with 30% Micromax was enhanced compared to pure hematite as it resulted in 10 and 14% reduction of the filtrate volume and filter-cake thickness, respectively. This study contributes to improve and economize the drilling cost and time by formulating a stabilized and distinguished-performance drilling mud using combined weighting agents at HP/HT.

Regime equations development for the design of Egyptian sandy canals

The construction of the High Aswan Dam in Egypt led to reducing the solids suspension in water from more than 3,500 p.p.m. to less than 100 p.p.m. As the regime of Egyptian canals has been changed completely after the construction of the High Aswan Dam, the previous derived equations are not applicable any more, and using them leads to a shortage in the carrying capacity of the canals. In the current study, extensive field measurements have been carried out on 15 stable Egyptian canals, which cover various discharges of irrigation canals with sandy soils starting from 5 m3/s to 50 m3/s and d50 ranging from 0.196 to 0.538 mm. Then, applicable regime relationships for designing stable sandy channels were determined. The new equations are useful for designing new stable canals and redesigning unstable canals within the same range. The new regime equations were verified by using the HEC- RAS program. Finally, sensitivity analysis has been performed in order to investigate the effect of changing the deduced parameters on the discharge.

Viability of Lactobacillus casei ATCC 393 and properties in Andean blackberry suspensions with probiotic and prebiotic characteristics

Food industry has grown in recent years mainly due to the supply of functional foods with probiotics and prebiotics. The viability of Lactobacillus casei and the properties of blackberry suspensions added with inulin were evaluated using a central design composed of the following factors: mass fraction of total solid blackberry concentrate (XTSBC) (0.103-0.120), [McFarland] (6-10), inulin (2.78-3.68%), and mass blackberry concentrate (BC)/mass inoculum (R) (5-20); and the dependent variables: moisture (M), pH, acidity, °Brix, total solids suspension (TSS), viscosity (μ), zeta potential (z), and Log CFU/g. Results of the experimental optimization of multiple responses were: XTSBC (0.103), [McFarland] (10), inulin (3.12%w/w), and R (18.5); being the dependent variables: M=86.7±0.0%, pH=2.74±0.01, acidity=3.1±0.0%, °Brix=11.0±0.1%, TSS=13.3±0.0%, µ=1288.0±20.1 cP, z=-13.3±0.3 mV and Log CFU/g=7.8±0.5. The probiotic microorganism Lb. casei ATCC 393 presents an adaptability in suspensions based on BC and inulin, which guarantee its viability and a possible use for obtaining an innovative spray-dried product.

An Eulerian Approach for Characterization of Solid Suspension in Multiphase Flow Systems and its Application in Hole Cleaning During Drilling

Solids suspension has broad applications in the oil and gas industry (i.e., sand production, cuttings transportation during drilling, and barite sag in drilling fluids). The conventional modeling approaches for solids suspension and transportation include mechanics models (i.e., layer models) and computational fluid dynamics (CFD) based Eulerian-Lagrangian models. One of the most important assumptions for these approaches is that the solid particles have uniform size, which is not true in the actual applications. The computational fluid dynamics/discrete element method (CFD-DEM) approach can track each single particle in the system; however, the computational time is not practical for industrial applications. This paper presents a relatively simple Eulerian approach for characterizing solids suspension in multiphase flow systems. The multiphase flow equations are derived by using a proper averaging procedure without considering interphase mass transfer. A proposed new solids suspension model, which is based on the fluid-solid interaction and kinetic theory, account for multiple solids sizes in the flow. The suspension characterizations for particles with different sizes are considered by introducing a particle size distribution function, which also captures detailed particle distribution and fluid/particle and particle/particle interactions. Therefore, a more realistic solids transportation prediction can be achieved. A simulation package is developed by solving the model using the finite difference method. The boundary-fitted coordinate system is applied to integrate the irregular geometry caused by drillpipe eccentricity and a packed solids bed. The influence of the solid phase on the carrier fluid is considered, and solid-liquid two-way coupling is implemented. The simulation package has been used for transient hole cleaning simulations during drilling. Simulation results show that cuttings’ backsliding makes the hole cleaning process in intermediate inclined wells different from that in horizontal and highly inclined wells. The cuttings movement in this part of the well follows the two-steps-forward, one-step-back routine. Well packoff is also captured by the program for improper hole cleaning operations in an intermediated inclined position. Transient hole cleaning tests were conducted on a 90 ft long, 8 × 4.5 in. flow loop. Experimental data are compared with the simulation results, and good matching is obtained. This method can also be used as a general tool for solids suspension and transportation simulation in multiphase systems.