Solids erosion

Note Liquid dump valves are normally fail closed to prevent giis blowby. That means that in ca.se of loss of instrument gas or air pressure, the spring will drive the valve to the closed position. However, the valve can mechanically fail because the level controller malfunctions or the seat cuts out due to solids erosion, which would cause it to fail in an open configuration. 

Fig. 9-3 Conceptual model to describe the interaction between chemical weathering of bedrock and down-slope transport of solid erosion products. It is assumed that chemical weathering is required to generate loose solid erosion products of the bedrock. Solid curve portrays a hypothetical relationship between soil thickness and rate of chemical weathering of bedrock. Dotted lines correspond to different potential transport capacities. Low potential transport capacity is expected on a flat terrain, whereas high transport is expected on steep terrain. For moderate capacity, C and F are equilibrium points. (Modified with permission from R. F. Stallard, River chemistry, geology, geomorphology, and soils in the Amazon and Orinoco basins. In J. I. Drever, ed. (1985), "The Chemistry of Weathering," D. Reidel Publishing Co., Dordrecht, The Netherlands.)...

Advanced industrial and utility power systems typically use direct fired gas turbine engines. Using coal to directly power a gas turbine has yet to be accomplished commercially, primarily because the ash causes erosion of the blades and deposition on the blades. If the combustion products contain a significant fraction of molten ash particles, deposition on the tmbine blades occurs which blocks the flow path and degrades performance. If the ash particles are solid, erosion of the blades occurs which also degrades performance. In addition, mineral matter can cause corrosion of the blades. The size distribution, concentration, and composition of the ash, as well as the turbine design, determine the lifetime of the turbine blades. 

Solids materials that are insoluble in hydrocarbon or water can be entrained in the crude. These are called bottom sediments and comprise fine particles of sand, drilling mud, rock such as feldspar and gypsum, metals in the form of minerals or in their free state such as iron, copper, lead, nickel, and vanadium. The latter can come from pipeline erosion, storage tanks, valves and piping systems, etc. whatever comes in contact with the crude oil. 

Erosion is the deterioration of a surface by the abrasive action of solid particles in a liquid or gas, gas bubbles in a liquid, liquid droplets in a gas or due to (local) high-flow velocities. This type of attack is often accompanied by corrosion (erosion-corrosion). The most significant effect of a joint action of erosion and corrosion is the constant removal of protective films from a metal s surface. This can also be caused by liquid movement at high velocities, and will be particularly prone to occur if the solution contains solid particles that have an abrasive action. 

Levy A 1995 Solid Partiole Erosion and Erosion-Corrosion of Materials (Materials Park, OH ASM International)... 

Valve Trim Various alloys are available for valve parts such as seats, disks, and stems which must retain smooth finish For successful operation. The problem in seat materials is fivefold (1) resistance to corrosion by the fluid handled and to oxidation at high temperatures, (2) resistance to erosion by suspended solids in the fluid, (3) prevention of galling (seizure at point of contact) by differences in material or hardness or Both, (4) maintenance of high strength at high temperature, and (5) avoidance of distortion. 

Pressure. Flow 0t(AP/pd - Only source of energy is from fluid being atomized. Simplicity and low cost. Limited tolerance for solids uncertain spray with high-viscosity liquids susceptible to erosion. Need for special designs (e.g., hypass) to achieve turndown. 

Erosion Erosion is the destruc tion of a metal by abrasion or attrition caused by the flow of hquid or gas (with or without suspended solids). The use of harder materials and changes in velocity or environment are methods employed to prevent erosion attack. 

Erosion-corrosion can be defined as the accelerated degradation of a material resulting from the joint action of erosion and corrosion when the material is exposed to a rapidly moving fluid. Metal can be removed as solid particles of corrosion product or, in the case of severe erosion-corrosion, as dissolved ions. 

In this case, reduced river water levels resulting from a drought may have caused an increase in the amount of sand and sdt entrained in the water, thereby increasing its erosive character. This may also account for the greater metal loss along the bottom half of the tubes, where heavy solids would tend to accumulate. 

Turbulence and high fluid velocities resulting from normal pump operation accelerated metal loss by abrading the soft, graphitically corroded surface (erosion-corrosion). The relatively rapid failure of this impeller is due to the erosive effects of the high-velocity, turbulent water coupled with the aggressiveness of the water. Erosion was aided in this case by solids suspended in the water. 

Erosion is the wear of the pump internal parts by suspended solid particles contained in the fluid being pumped. The most affected parts are wear rings, shaft sleeves, packing, mechanical seal faces, lip seals, the pump casing and the impeller. 

Erosion can be caused by small particles not visible to the human eye, like dissolved minerals in hard water. Larger solids like sand, boiler scale, and rust can also cause serious erosion inside the pump. 

The fluid being pumped is often not well defined. Terminology like well water, industrial effluent, raw water, boiler feed water, condensate water, etc., is usually the only definition we have of the fluid being pumped. Any of these fluids can contain several concentrations of. solids that cause erosion and wear inside the pump. 

Dust-laden streams can also cause operational problems. A turboexpander that can efficiently process condensing streams (gas with fog droplets suspended) can usually handle a stream with suspended solid particles, as long as the particle size does not exceed 2-3 p. The newer designs reduce erosion of expander back rotor seals by disposing of... 

In support of the power recovery expander market for fluid catalytic cracking units in refineries, some turboexpander manufacturers have an ongoing program to improve the solid particle erosion characteristics of the machine. Improved erosion characteristics will result in longer blade life, less downtime, and consequently greater profits for the users. 

The following briefly reviews the parameters that affect erosion and the programs instituted by Elliott to obtain basic erosion data. The data from these studies have been integrated into Elliott s erosion prediction program. Table 4-13 lists some of the more important parameters affecting expander blade erosion from solid particles. Many of these parameters directly relate to the particle itself. 

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