Pumpability problems

Low-temperature distillate fuel pumpability and viscosity can be reduced below that of an untreated fuel. Below the cloud point, fuel which does not contain a wax crystal modifier is difficult to handle and pump effectively. Wax crystal modifiers help minimize pumpability problems related to yield stress and viscosity. 

Measuring the cloud point, pour point, CFPP, or LTFT will help to confirm whether pumpability problems are due to wax. Fuels at their cloud point, CFPP, or LTFT temperatures will eventually plug fuel filters when pumped. When a fuel is very near its pour point, pumping will be quite difficult. 

Water contamination in diesel fuel is common. When diesel fuel cools, ice crystals may form in the fuel well before the fuel reaches its pour point. These ice crystals will settle to the bottom of fuel tanks and may result in fuel filter plugging and pumpability problems. 

This situation can sometimes be manifested in the fuel distillation profile. More responsive fuels may have lower IBP and EP temperatures than poorly responsive fuels. Also, in poorly responsive fuels, a larger volume of fuel may distill within mid-boiling-point temperature fractions of the fuel distillation profile. The wax crystals which may form from these narrow boiling fractions tend to crystallize rapidly and at about the same temperature. Diesel fuel pumpability problems can be due to this narrow-boiling-point range wax fraction. 

Koppers Tar creosote oil is comprised primarily of two-, three-, and four-ring polynuclear aromatic compounds. Only 4% of this solvent, which contains a sizable amount of fluoranthene (bp 723°F), boils over 850°F. Typical hydrotreated 420°-850°F distillate product from this feed material has a multitude of additional components in much smaller concentrations as determined by gas chromatography (GC). The major components of the feed contribute less to the total concentration in product than in feed. Therefore, product distillates are less pure than feed distillates and less likely to solidify than feed. Indeed, Koppers Tar is itself a solid-liquid mixture which upon observation suggests handling problems. In anticipation of pumpability problems for mixtures of SRC in Koppers Tar, a viscosity study was made on several different concen-... 

Suspended Particle Techniques. In these methods of size enlargement, granular soHds are produced direcdy from a Hquid or semiliquid phase by dispersion in a gas to allow solidification through heat and/or mass transfer. The feed Hquid, which may be a solution, gel, paste, emulsion, slurry, or melt, must be pumpable and dispersible. Equipment used includes spray dryers, prilling towers, spouted and fluidized beds, and pneumatic conveying dryers, all of which are amenable to continuous, automated, large-scale operation. Because attrition and fines carryover are common problems with this technique, provision must be made for recovery and recycling. 

Handling does not end with entry into the digester since contents must be mixed, scum formation prevented and effluent removed to disposal or storage. Welsh et al (8) reported that anaerobic digestion renders the effluent less offensive and more pumpable with fewer settling problems. 

Linear, branched and cyclic paraffins can all be present in fuel. At low temperatures, fuel filtration, pumpability and injection problems are primarily due to paraffinic wax. Refiners can contend with fuel wax through processing changes and blending. Examples include ... 

Often, these fuels respond poorly to treatment with a wax crystal modifier or may require high rates of a wax crystal modifier to improve filtration and pumpability performance. This problem seems to occur whenever two situations exist ... 

Fuel applications. Bitumen, the residuum of petroleum distillation, is gaining interest as a low cost fuel. The main problem with bitumen as a fuel is handling the viscous, almost solid product. This issue has been addressed by emulsifying molten bitumen in water using cationic surfactants such as tallow alkyl propanediamine [92] and salts of similar amines with fatty acids [93]. The emulsions thus prepared are pumpable and useful as fuels for stationary burning such as in power generation facilities. 

Petcoke water slurries were prepared at mass ratios ranging from 30 70 to 70 30. EnerSol determined that mixtures of up to 50 50 were pumpable and fed without problems to the RRT reactor. Mixtures with higher petcoke concentrations were difficult to maintain in suspension. Experimentation with surfactants and stabilizers resulted in a pumpable mixture at 65% petcoke and 35% water. 

This is a CE analog of conventional zone gel electrophoresis for the separation of macromolecules based on size. The capillary is filled with a porous polymer gel, and molecular sieving occurs as the molecules move through the gel, that is, separation is based on both electrophoretic mobility and molecular size. Very high resolution is achieved. The trend is to fill the capillary with a liquid gel matrix (pumpable gel solutions, such as deriyatized celluloses dissolved in the run buffer). This allows replacement of the gel in the capillary to eliminate contamination problems from the sample matrix that occurs with fixed gels.. This technique is widely used for separation of nucleotides in deoxyribonucleic acid (DNA) sequencing (Chapter 25). 

Reference to Chapter 6 will indicate that material for incineration that cannot be handled as a liquid (e.g. nearly solid material in drums) is difficult and expensive to incinerate and it may therefore be necessary to leave sufficient solvent in a residue to make its handling easy. A site where direct transfer may be made from the solvent recovery plant to an incinerator can allow molten solids or liquids pumpable at process temperature to be destroyed without handling problems. However, incinerators tend to need considerable maintenance and to link closely the operation of solvent recovery plant to an incinerator may not be acceptable. 

Of the above liquid crystalline stmctures, the lamellar phase is the most important for food apphcations. As we will see later, these lamellar stmctures are very good stabilizers for food emulsions. In addition, they can be diluted with water, forming liposome dispersions that are easy to handle (pumpable liquids) and they interact with water-soluble components such as amylose in starch particles. Hexagonal and cubic phases, in contrast, when formed give problems in food processing due to their highly viscous nature (viscous particles may block filters). 

XI. 1.2 The usefulness of the pour point test in relation to residual fuel oils is open to question, and the tendency to regard the pour point as the limiting temperature at which a fuel will flow can be misleading. The problem of accurately specifying the handling behavior of fuel oil is important, and b use of the technical limitations of the pour point test, various pumpability tests have been devised to assess the low-temperature flow characteristics of heavy residual fuel oils. Test Method D 3245 is one such method. However, most alternative methods tend to be time-consuming and as such do not find ready acceptance as routine control tests for determining low-temperature flow properties. One method which is relatively quick and easy to perform and has found limited acceptance as a go-no-go method is based on the appendix method to the former Test Method D 1659 - 65. The method is described as follows. 

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