Plant oversizing

If a plant cmshes to obtain stone of 0.6 and 7.6 cm for lime-kiln feed, coarse aggregate, or fluxstone, much undersized material is also produced. Oversized material can be reduced by recycling through the cmsher system, but the subsized stone, called spall, is wasted in a spall pile. Such spalls have potential value as by-products for use as, eg, asphalt (qv) filler. 

Consider a process plant having a connected load of 15 000 kW and a running load of 12 500 h.p. at almost 0.65 p.f. lagging. Let a few large induction motors aggregating 2000 h.p. be replaced by as many oversized synchronous machines, with the purpose of improving the system p.f. in addition to performing the motor s duties. 

A new nose eone was obtained and initial maehining performed by die repair faeility. The nose eone is supported by six radial pins. The nose eone and inlet easing were sent to die main plant to ensure die pin hole loeations were properly positioned. Here, die inlet easing was assembled and oversized pin holes were drilled and reamed in die pieees. Pins made to fit die holes were also maehined. Repau maehining... 

For plant such as boilers, operating in parallel controls should ensure that one boiler acts as a lead to minimize part-load operation. As far, as is possible, plant should be sized to meet the load and oversizing should be avoided. 

Accuracy and reproducibility are of vital importance to industry. Quite apart from the effect of these factors on the final product, several plant items are frequently links in a continuous chain of production processes. A sizing error in one machine, for example, could overstress and damage the succeeding machinery. Similarly, an error in a press may increase stress on the tool and could necessitate an additional operation to remove excessive flash . Wear in a material preparation unit could allow oversize material to be passed to a molding machine, creating an overload situation with consequent damage. 

After a number of weeks of painful work at the Buna plant, a terrible typhus epidemic broke out. The weaker prisoners died in hundreds. An immediate quarantine was ordered and work at the Buna stopped. Those still alive were sent, at the end of July 1942, to the gravel pit but there work was even still more strenuous. We were in such a state of weakness that, even in trying to do our best, we could not satisfy the overseers. Most of us got swollen feet. Due to our inability to perform the heavy work demanded of us our squad was accused of being lazy and disorderly. Soon after, a medical commission inspected all of us they carried out their job very thoroughly. Anyone with swollen feet or particularly weak was separated from the rest. Although I was in great pain, I controlled myself and stood erect in front of the commission, who passed me as physically fit. Out of 300 persons examined, 200 were found to be unfit and immediately sent to Birkenau and gassed. 

The Sydney plant is a combination of older mercury cell technology (updated ICI Mark 1 cells) and modern derivative plants (hydrochloric acid, sodium hypochlorite and ferric chloride) combined with liquid chlorine packing. The mercury cells had originally been in excess of 80 000 tonnes per annum capacity and cells had been progressively taken off-line following closure of chlorinated solvents (CTC/PCE) and EDC/VCM manufacture over a period of 10 years. This had left an asset significantly oversized compared with the present market demands. 

This part of a plant survey is, unfortunately, seldom carried out, as it may be considered that there is little, in practice, that can be done to change the plant design or operating conditions. Nevertheless, it can often be a useful exercise to undertake, especially if it is suspected that the tower is considerably undersized or oversized, or if there is evidence of cooling tower fouling. 

Staff at the Modesto Energy Project believe this particular baghouse was somewhat oversized, because the emissions from the plant were of such concern during permitting and construction.1 Modesto personnel are required to keep 25 percent, of the bag requirement as spares on site.1... 

Chippers and flakers are the most widely used knife reduction systems. Chippers produce coarse particles from roundwood, slabs, plywood trim, and other residues from the primary wood industry. Chippers are the initial reduction step in particle preparation and further size reduction is necessary to produce a satisfactory particle. The chipping operation may be located at the particleboard plant or the chips may be delivered to the plant from an in-woods chipping operation, a chip-n-saw mill, or from another primary wood industry. Screening after the chipper removes all fines and oversize chips before they enter the secondary reduction step. Oversize chips are recycled to the chipper and fines are normally sent to the boiler for fuel. 

At this section of the plant in the past, chemical process operators (not maintenance mechanics) handled the tank-filling step in the hydrotest process. Operators would typically drape a fire hose into an oversize roof nozzle and fill the tank from the nearest hydrant. In this case, it was reported the two mechanics asked their maintenance supervisor if they could connect the hose to a flanged lower-valved nozzle on the tank. The supervisor remembers requesting the mechanics to roll a blind flange at the top for venting purposes if they used the lower nozzle for filling. There must have been a miscommunication. Obviously the mechanics failed to understand the dynamics of the filling operation when they chose to open only the two 1/2-inch top vents. 

With rising feedstock prices and hard competition in the market, many producers have looked for possibilities to revamp or modernize their older, less efficient plants so that they can stay competitive. Most revamp projects have been combined with a moderate capacity increase because some of the original equipment was oversized and only specific bottlenecks had to be eliminated, not entailing excessive cost. As the market possibilities for a company do not increase in steps of 1000 or 1500 t/d but slowly and continuously, such a moderate capacity addition will involve less risk and will often be more economical than building a new plant. 

Phosphorus or potassium deficiency can cause spots or patches of dark flesh. Oversize tubers with hollow centers may also indicate potassium deficiency. If deficiencies are suspected, have soil tested and amend as needed. If plants show symptoms of phosphorus deficiency, raise soil pH to 6.0 so the mineral will be more available to the plants. 

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