Deposits free running

Lasers have been used to initiate deton in RDX. Three types of initiation mechanisms have been described (Ref 102) (1) instantaneous deton caused by a shock wave in a thin metallic film (deposited on the expl) with the shock wave generated by a Q-switched laser pulse (2) instantaneous deton by direct interaction of a Q switched laser pulse and the test expl and (3) DDT produced by free-running laser pulses. Coarse RDX cannot be initiated, but milled RDX (particle size less than 40 microns) is readily initiated at various packing densities. The threshold fluences for the initiation of 1.18g/cc l,52g/cc milled RDX via mechanism (1) are 45,3J/cm2 and 127.9J/cm2, respectively. Detons are either essentially instantaneous or the sample bums without deton. For direct initiation [mechanism (2)], the threshold laser energy for 1.18g/cc RDX was 0.8J, or the same as in thin film initiation. However, deton was no longer instantaneous but required about 2 microsec for build-up. The 1.52g/cc RDX was initiated directly without delay (laser energy not given)... 

A free-running or loose deposit is an adhering layer of solid particles. A tacky deposit is caused by the presence of tacky (liquid, oily) constituents. Dense deposits are formed, for example, in the combustion of Estonian shales at 500-1000°C and also of the poor coal under Moscow. Dense deposits are also formed in the combustion of certain kinds of fuel oil. In practical conditions, all forms of deposit may be present at the same time, and it is sometimes difficult to observe the boundary between them,... 

Free-Running Deposits. The composition (as regards particle size) and quantity of free-running deposits precipitated from a gas flow depends on the size distribution and concentration of the particles in the flow, the operating time of the plant, the velocity and direction of the flow, and also the diameter and mutual arrangement of the pipes. 

The formation of free-running deposits is possible when the process of dust sticking predominates over the detachment of adhering particles under the influence of the air flow. 

Fig. IX.9. Amount of free-running deposits as a function of the flow velocity calculated from Eq. (IX. 10). 1) First term of the equation 2) second term of the equation.

Fig.IX.il. Amount of deposits as a function of the flow velocity. 1) Total, i.e., free-running plus dense 2) dense.

Tacky Deposits. If the deposits contain particles with tacky surfaces, the adhesion of such deposits increases sharply, and the deposits themselves become tacky rather than free-running. Tacky deposits may be distinguished from the free-running type by eye. 

If dense deposits are accompanied by free-running deposits, the sum of these may be calculated, with due allowance for (IX.10), from the following formula [455] ... 

Fig. IX.13. Rate of growth of the thickness of the deposits (6) on the front of a pipe in a transverse flow as a function of the flow velocity. 1) Average over the length of the pipe 2) growth of the ridge of free-running deposit 3) growth of the ridge of dense deposit at a temperature of 640-664 C 4) the same at 565-588 C.

The amount of dense deposits (m2) varies with the velocity of the flow in the same way as the amoimt of free-running deposits (see Fig, IX,9), However, the laws governing the variation in the total amount ffree-running plus dense) of the deposits, which is characterized by the quantity m in formula (IX. 15), has its own special characteristics. As the velocity of the air flow rises from Vj to v the amount of the total deposit increases principally on account of the free-running components (Fig, IX,11), Further increasing the velocity of the flow, subject to the condition v < v < v/, increases the proportion of the dense deposits. For v > vV, the... 

Hence there are two special velocities of gas flow the first is v. below which both free-running and dense deposits are formed and above which there are only dense deposits the second is above which no deposits are formed at all. 6pik [455] considered that v should be of the order of 220 m/sec. However, we feel that this velocity is too low (see 31). 

Figure IX.13 also shows the experimental relation between the rate of growth of the deposits and the rate of gas flow. In all cases the rate of growth of the free-running deposits was many times greater than that of the dense deposit. For a velocity of 8-11 m/ sec there was a sharp transformation from free-running to dense in the form of the deposits.

We have considered examples in which the formation of a dense deposit was accompanied by the formation of a free-running one. It is possible to have other cases in which tacky and dense deposits are formed at the same time as, for example, in the case of the combustion of fuel oil. The ash of fuel oil consists of metal-corrosion products (iron salts and oxides), the remains of substances used in the acid and alkali treatment of petroleum, salts of bore-hole water, contaminant particles, and particles of unburned carbon (soot and carbides). When the individual ash components interact with each other and with the gas medium, both dense and tacky deposits are formed. Despite the fact that in the... 

The lees from the last pressings of juice are often brown. Even after filtration, the resulting juice should not be blended with the free run it should be fermented separately. The gross lees from the first pressings are effectively clarified by filtration, which should be carried out as soon as possible since this deposit is very fermentable. The filtrate can be blended with juice which has already undergone an initial racking. 

A) Extract the mixture with about 40 ml. of chloroform, in which the free base is very soluble. Run off the lower chloroform layer, dry it with potassium carbonate as in (a), and then add carbon tetrachloride slowly with stirring to the filtered chloroform solution until the base starts to crystallise out. Allow to stand for a short time (t.e., until the deposition of crystals ceases) and then filter at the pump as the crystals lose the last trace of solvent, they tend as before to break up into a fine powder, the deep green colour becoming paler in consequence. 

These results and the comparison between the catalyst particles before and after catalytic run point out the ability for these particles both to exchange electrons and oxygen anions and to change morphology under the conditions of the catalytic reaction with spreading of the oxides one over the other. These two phenomena should be at the basis of the explanation of synergy effect in molybdates based catalysts. The fact that some FexCoi.xMo04 particles remain free (i.e. not deposited on bismuth molybdate particles) show that even more active and selective catalysts may be obtained in more reliable preparation conditions. 

In compounds 7 and 8, we have studied the influence, on the thermal behavior, of the presence of Me3Si substituents on the Cp ring of Ti(lV) trichloro derivatives. Such groups should help in the elimination of the Cl atoms through formation of volatile Me3SiCl in the gas phase. Thermal analyses showed that both compounds are volatile and decompose below 623 K. Cold wall CVD experiments run at 973 K and normal pressure yielded in both cases thick films (up to 15 pm) that were identified by XRD as TiC. The deposits were free of chlorine but slightly contaminated with... 

Carbon residue is a measure of deposit formation in the long run. Biodiesel manifests a more pronounced coke formation than conventional diesel. For this reason the content of mono-, di-, and triglycerides, should each be kept below 0.4wt%. The total bounded and free glycerol should be below 1.5%. 

How do the amounts and types of coke deposited on the various metal surfaces vary as a function of time In the present investigation, the resulting coke was obtained during 120-min runs. In the future, shorter and longer runs are needed to determine the kinetics of coke formation and to determine whether one type of coke is a precursor for another type. Possibly both filament and needle cokes act to some extent as a filter for gas phase coke to form eventually amorphous or knobby coke in which metal-containing coke is eventually covered with metal-free coke. 

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