Economics disassembly

A slurry is being filtered at a net rate of 10,000 gal/day by a plate and frame filter with 15 frames, with an active filtering area of 1.5 ft2 per frame, fed by a positive displacement pump. The pressure drop varies from 2 psi at start-up to 25 psi after 10 min, at which time it is shut down for cleanup. It takes 10 min to disassemble, clean out, and reassemble the filter. Your boss decides that it would be more economical to replace this filter with a rotary drum filter using the same filter medium. The rotary filter operates at a vacuum of 200 mmHg with 30% of its surface submerged and rotates at a rate of 5 min/rev. If the drum length is equal to its diameter, how big should it be ... 

As mentioned in Section 5.2, the economic margin of dismantling is very tight and the logistic boundary conditions—for example, regarding the sporadic number of similar units and the broad variety of product types—are rather unfavorable for automation. Depending on the flexibility of automated disassembly installations, three strategies can be used. 

Some standardized products (e.g., videotapes, ray tubes of computer monitors) can be collected in large numbers so that automated disassembly cells especially designed for these products can work economically. 

K. Feldmann, H. Scheller, H. Meerkamm, and D. Krause, Design for Recyclability and Economic Planning of Disassembly Based on the Recyclinggraph Tool in proceedings of RECY 94, Erlangen, Germany, pp. 76-90 (1994). 

Disassembly costs are largely ignored in product pricing. The incineration of plastics is stUl often the most economical solution. It makes little practical sense to consider plastics recycling within an isolated framework. 

Disassembly depth indicates how far down a product is disassembled. The optimal disassembly depth can, for example, be determined by economic analysis, where a trade-off between revenues and costs is made (Langella 2007). 

Steel strutted retaining structure is one of the common forms widely used in construction in deep foundation pit because of its convenient installation and disassembly. Lots of economic benefits are linked with the reuse of steel struts. Since steel strut can work immediately to effectively reduce the displacement of excavation after installation, priority could be given to the use of this form of supporting in case of buildings adjacent around the foundation pit or small deformation of the pit required (Bin, 2012 Wang, 1998). 

The latter could be implemented by requiring delay times after application for a building demolition permit. Economic instruments for this phase would include increasing the cost of disposal of demolition waste and providing incentives, perhaps in the form of subsidies, for entities that set up deconstruction, recycling, and/or materials reuse businesses. Information instruments could include Eco-Labelling schemes that have as one of their criteria the ability to disassemble products into recyclable materials. 

For waste such as automobile parts, there is a wider mix of materials, often assembled. Disassembly is economically justified only if components weigh more than 100 g, and sorting is often best carried out manually. MIR and FTR spectrometry can be used. 

RBMK fuel assemblies have to be separated from their long upper support rods and separated into two fuel bundles before storage in dry casks. To achieve closer packing of fuel rods, fuel assemblies can be disassembled and consolidated for better economics of storage. Before going to dry storage, fuel casks have to be dried and filled with inert gas. 

For high-volume production, snap-fit designs provide economic, rapid assembly. In many products, such as inexpensive housewares or hand-held appliances, they are designed for one assembly only, with no nondestructive means for disassembling them. Where servicing them is anticipated, provision is made for the release of the assembly with a tool. Other designs, such as those used in the battery compartment covers for calculators and radios, are designed for easy release and reassembly many hundreds of times. 

Automated disassembly of electronic and automotive products would be of considerable benefit to the mechanical recycling of plastics fractions. The results of a Delphi Study [3] provided an indication of the full or partial technical feasibility and economic viability of automated disassembly. 

The featureless music wire pin is economical and widely available. A countersunk top plate hole or two-ply top plate is generally used for high-performance applications. Notice that no disassembly is required to service a pin. 

Design choices about durability, disassembly, and reusability affect the economics of product recovery. The challenge is to develop a framework for incorporating sustainability in design. Designers must appreciate the interactions between product attributes, sustainability, and consumer behavior (Edwards 2009). 

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