Excess material handling costs

Finally, one company received and stored plastic compounds at a site location a mile from the manufacturing facility and incurred close to 150,000 annually in excess material handling costs. This added 0.03 to the cost of every pound of plastic used, which was a material addition that had been invisible without ABC. 

Overproduction is the excess production or acquisition of items beyond what is actually needed. When overproduction occurs, additional capital investment is necessary, and costs are increased without adding value since more storage space and material handling are necessary. Overproduction that results in excessive material handling adds to risks. 

Inefficient materials handhng and storage increase product cost, delay product delivery, and consume excessive square feet of plant and warehouse space. Studies have indicated that actual materials-handling cost runs between 20 and 50 percent of the total product cost even though it does not add any value to the finished product. In addition, from 80 to 95 percent of the total overall time devoted to processing a customer order from fabrication to shipment is... 

Soils with a moisture content above 20% must also be dewatered or treated to prevent excessive energy costs and residence times in the TDU. Dewatering may be carried out with a filter press, air drying, or gravity separation. Alternatively, contaminated soil is sometimes treated with lime to lower the moisture content and improve the material handling characteristics. Whichever method is chosen, the goal is to achieve a soil moisture content of approximately 8-12 /o.f This allows for the benefits of steam distillation without excessive fines in the off-gas as would happen if the soil were too dry. 

Because an excess of ammonia is fed to the reactor, and because the reactions ate reversible, ammonia and carbon dioxide exit the reactor along with the carbamate and urea. Several process variations have been developed to deal with the efficiency of the conversion and with serious corrosion problems. The three main types of ammonia handling ate once through, partial recycle, and total recycle. Urea plants having capacity up to 1800 t/d ate available. Most advances have dealt with reduction of energy requirements in the total recycle process. The economics of urea production ate most strongly influenced by the cost of the taw material ammonia. When the ammonia cost is representative of production cost in a new plant it can amount to more than 50% of urea cost. 

The ratio of fluorspar to sulfuric acid fed depends on the relative cost of each raw material. As of this writing, fluorspar is more expensive than sulfuric acid thus, most often a slight excess of sulfuric acid is desirable. Too much sulfuric acid, however, yields a reaction mixture which becomes wet, sticky, corrosive, and hard to handle. 

Terephthalic Acid from Toluene. Both carbon monoxide and methanol can react with toluene to yield intermediates that can be oxidized to terephthalic acid. In work conducted mainly by Mitsubishi Gas Chemical Company (62,63), toluene reacts with carbon monoxide and molar excesses of HF and BF3 to yield a jtanz-tolualdehyde—HF—BF3 complex. Decomposition of this complex under carefully controlled conditions recovers HF and BF3 for recycle and ra-tolualdehyde, which can be oxidized in place of para-xyiene to yield terephthalic acid. One drawback of the process is the energy-intensive, and therefore high cost, decomplexing step. The need for corrosion-resistant materials for construction and the need for extra design features to handle the relatively hazardous HF and BF3 also add to the cost. This process can be advantageous where toluene is available and xylenes are in short supply. 

In model constraints given next, Q is a wrap-around operator (Shat et al., 1993), r, holds the duration of tasks in number of time intervals (5=8 h) and set K, gives the tasks belonging to chemical z. The objective function minimizes the total cost of the schedule in relative money units (r.m.u.). Eq 2 ensures that the volume handled by the task does not exceed the capacity of the vessel Vm. Eq 3 ensures that material production only occurs if the corresponding task is executed. The periodic schedule features exactly one batch of each chemical (eq 4). Eqs 5-6 are the excess resource balances. Eq 7 ensures that the start-up procedure does not require more units than those available. 

Spilled material is sometimes directly reused either by reprocessing in a refinery or as a heating fuel. Some power plants and even small heating plants such as those in greenhouses can use a broad spectrum of hydrocarbon fuels. Often the equipment at refineries cannot handle oils with debris, excessive amounts of water, or other contaminants and the cost of pre-treating the oils can far exceed the value that might be obtained from using them. 

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