Cost of recycles

As the reactor conversion increases, the reactor volume increases and hence reactor capital cost increases. At the same time, the amount of unconverted feed needing to be separated decreases and hence the cost of recycling unconverted feed decreases, as shown in Fig. 8.1. Combining the reactor and recycle costs into a total cost indicates that there is an optimal reactor conversion. 

Product concentration influences the separation cost and the cost of recycling unconverted reactants. Production rate has a strong effect on investment cost for the full synthesis loop. Selectivity sets the raw material... 

In recent months, three nylon producers (DMS, DuPont, and Honeywell) have developed closed-loop recycling processes for nylon carpet,15 thereby joining companies like BASF, Allied, and Rhodia, which have been recycling nylon on a modest level for years. DuPont is building a demonstration plant in Maitland, Ontario, which will be dedicated to the chemical recycling of nylon-6,6 and nylon-6. The newly developed ammonolysis process invented by DuPont can be used to depolymerize both nylon-6 and nylon-6,6. However, the cost of recycled nylon is estimated to exceed that of virgin nylon by ca. 25%. 

In those jurisdictions where money is specifically collected from consumers to underwrite the costs of recycling plastic containers, funds may be available to offset some costs of depolymerization. If bottles are provided at no cost at the sorting/baling facility, an economically attractive venture can be contemplated, but still at a large scale. Securing the feed on a long-term basis at a favorable price will require significant co-operation. 

In the most unfavourable case, the cost of recycling is a combination of the operations of collecting, dismantling, sorting, treatment and recycling. 

At Alang in the Gulf of Cambay on India s Arabian Coast, thousands of rusting old ships are run against the beach and broken apart Instead of using expensive dry docks, Indian entrepreneurs use a readily available natural resource, the beach, to dramatically reduce the cost of recycling and employ... 

High isobutane recycle purity is not required on HF alkylation units as is required on many H2SO4 units because relatively high normal butane concentrations in the reaction zone do not appreciably affect the quality of the alkylate. Isobutane purities below 60% are usually avoided, however, since this purity definitely gives lower-quality alkylate and the cost of recycling the normal butane is considerable in heat requirements as well as fractionation equipment requirements. 

Impurities affecting the catalyst must be removed. Evaluate the cost of an extra purification system for feeds, as well as the cost of recycling harmful impurities, including equipment fouling and maintenance. 

Because at the RSR level the separators are not yet known, the cost of recycles may account only for transport and conditioning of streams. Transporting gases involves high capital and operation costs for compressors. Similarly, thermal feed conditioning may involve expensive equipment, such as evaporators and furnaces, as well as the cost of heat carriers. 

The costs of recycling for different feedstock techniques in 2003 are shown in Table 26.24, which includes the transportation cost from municipality to the recycling plant. These costs are all paid by businesses, except for small businesses of (paid for by municipalities and 8% in the case of Sendai city). 

The discussion in the previous sections has evidenced that the use of biphasic systems has solved, at least in various cases, the problem of homogeneous catalyst recovery and recycle, but there still exists the problem of the cost of recycle and especially of reaction rate per volume of reactor, which derives in large part from mass- and heat-transfer limitations, but also from the low amount of catalytic centers per volume of reactor necessary to avoid side reactions and maintain a high selectivity, and/or limit catalyst deactivation or loss. These aspects often emerge only during the scaling-up and industrialization of the reaction and this is one of the reasons why many interesting reactions at the laboratory scale fail in commercialization. 

The numerator is the sum of emergy of the product (Yp) and the treated waste (Ytw) sold to the market and the untreated waste sold to the neighboring plant (Yuw). The denominator is the sum of the investment, waste disposal cost, operation cost and cost of feed streams, all in terms of emergy. Investment includes a base value (< and a term which varies with the capacity of the unit (Qi) raised to a fraction (m) - that is, +. There are two units which require investment the production unit with a capacity of X and the waste treatment unit with a capacity of Wj. In equation 10.28, Jis the sum of for both the production unit and the waste treatment unit. Waste disposal cost includes the cost of disposing treated and untreated waste (Wtw and Wuw respectively). Operation cost is the cost of recycling both the treated and untreated waste internally to the plant (Wtrn° and Wurr respectively). Lastly, cost of feed streams includes the cost of renewable feed, non-renewable feed and untreated waste from the neighboring plant R, N and Yuw respeetively). 

Profitability is the difference of the revenue earned and the cost incurred. Revenue is obtained from the sale of product to the market (Ypi), treated waste to the market (Ytwi) and untreated waste to the neighboring plant (Yuwi)- Cost is incurred from the investment of the process and waste treatment unit as well as the cost of operation (i.e. cost of feed streams, cost of disposal of treated and untreated waste, cost of recycling treated and untreated waste). Profit, lEcP and lEvP for the IE with 6 plants are as follows ... 

One might extrapolate that such levels of solubility could lead to a process that might not employ the recycle of gas in its operation (Friedrich, private communication 1983). In the case of soy beans, which have an oil content of about 16%, a solubility level of 40 wt-% oil in CO2 calculates to a CO2 requirement only 0.24 Ib/lb soy beans. At a CO2 usage of only 0.24 lb, the capital and operating cost of recycling the gas could well be more than the 1 cent cost of the COi. 

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