Velocity steam, replacement

For corrosion and safety reasons, the condensate recovered from these sources is best not returned to the deaerator for use as boiler feedwater. However, depending on the contaminant, the condensate may be reused for a number of services. Our favorite reuse of such contaminated condensate is as a replacement for velocity steam in the heater-tube passes of a fired furnace. 

Where new boilers are married to old steam and condensate systems, similar effects occur because of the transport of debris and the resultant blockages of valves and steam traps. Where the replacement boilers are of a higher rating than the existing boilers, the problems are further exacerbated (often due to surging, faster steaming times, or increased steam velocities). 

Having replaced the loop seal piping, (some units use a steam trap instead of this loop seal), I started steam flow to the turbine. But the vacuum in the surface condenser, which had started out at an excellent 27 in Hg, slipped down to 14 in Hg. This loss in vacuum increased the backpressure in the turbine case. The higher pressure in the turbine case reduced the velocity of the steam striking the buckets on the turbine wheel, which reduced the amount of work that could be extracted from each pound of steam. 

Upstream water level (in which case we could calculate the jet velocity by Bernoulli s equation) or if it were a jet of steam from a boiler with constant steam temperature and pressure (in which case we could calculate the jet velocity by the methods developed in Chap. 8). For a fixed jet velocity, at what velocity should we run the blade to get the maximum amount of useful work from it Here we want to maximize dWldm from calculus we know that this will be a maximum when d dWldm)ldV is zero. First we replace F, using Eq. 7,43 ... 

To allow us to better assess the impact of water, instead of adding external water to the reactant feed stream directly, a situation that causes the partial pressures of the syngas reactants to be altered, or the total pressure of the reactor to increase, we utilized a method that leads to constant reactant partial pressures, constant total gas space velocity, and constant total pressure before, during and after H2O addition. That is, we replaced an equivalent amount of cofed inert gas with the same amount of steam in an incremental manner. 

Possible operating problems for such dryers include deposit formation and erosion of the flash tubes due to high-velocity transport of particles that may contain abrasive impurities such as sand. Erosion, particularly in bends, can be minimized or taken care of by using special materials or replaceable elbows. Deposits may form within the dryer walls if the transporting steam temperature falls to saturation level. Corrosion is also a problem to be considered. Often, stainless steel construction is required. It is important to disintegrate the solids prior to feeding in the flash dryer as the transport steam does not suspend large lumps and the like. 

The situation immediately after catalyst replacement can be analyzed using base-case ratios. If the activity of the new catalyst is higher than the old catalyst, then the reaction rate is increased. Because the only reaction involved is for cumene production, 33% more steam is produced. Therefore, the steam velocity in the pipe leading to the steam header is increased by 33%. Because the flow is fully turbulent, the friction factor remains constant, and, assuming unchanged density. 

Physical and thermal parameters improved sharply after such a modification due to decreased matrix material in the fuel elements and increased flow cross section. Six element channels were gradually replaced by five element channels during refueling of the operating reactor. The removal of one of the elements allowed for an increase in steam velocity in the upward flowing fuel elements (Samoylov et ah, 1976). Stainless steel was used as the outer sheath material. Uranium dioxide dispersed in matrix alloy was used as fuel elements in SHS channels. Improvements in the performance of various BNPP parameters are listed in Tables A5.5 and A5.6. 

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