Additional operating costs

A number of contributory operating cost factors that result fi om the accumulation of unwanted deposits on heat exchanger surfaces can be identified. 

The function of a heat exchanger as the name implies, is to transfer heat energy between streams. The prime reason for this is to conserve heat which is usually a costly component of any process. Reduced efficiency has to be compensated in some way in the process. If heat is not recovered the shortfall will have to be made up perhaps by the consumption of more primary fuel such as oil, coal or gas. In other operations it is necessary to raise the temperature of a particular stream to facilitate a chemical reaction, for example hydrocracking in refinery operations to produce lower molecular weight products. In power stations the efficiency of the steam condensers at the outlet from the turbines has a direct effect on the cost of 

Apart from the problem of reduced energy efficiency other problems may accrue. For example if the temperature of the feed to a chemical reactor is lower than the optimum called for in the design, the yield from the reactor may be reduced. The quality of the product may not be acceptable and additional processing may be required to improve the specification of the product. 

The presence of deposits on the surface of heat exchangers restricts the flow area. As a consequence for a given throughput the velocity of flow increases. In approximate terms. 

The presence of fouling on the surface of heat exchangers may be the cause of additional maintenance costs. The more obvious result of course, is the need to clean the heat exchanger to return it to efficient operation. Not only will this involve labour costs but it may require large quantities of cleaning chemicals and there may be effluent problems to be overcome that add to the cost. If the cleaning agents are hazardous or toxic, elaborate safety precautions with attendant costs. 

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Enzymatic Reactors Adding free enzyme to a batch reactor is practical only when the value of the enzyme is relatively low. With expensive enzymes, reuse by retaining the enzyme with some type of support makes great economic sense. As some activity is usually lost in tethering the enzyme and the additional operations cost money, stabihty is very important. However, many enzymes are stabilized by immobilization thus, many reuses may be possible. 

Implementing Chemical Leasing only makes sense, if total investment costs and additional operating costs required to keep the new process on a higher level of efficiency are lower than the expected savings. 

A plant is producing 10,000 metric tons per year (10 kMTA) of a product. The overall yield is 70%, on a mass basis (kg of product per kg raw material). The raw material costs 500/metric ton, and the product sells for 900/metric ton. A process modification has been devised that will increase the yield to 75%. The additional investment required is 1,250,000, and the additional operating costs are negligible. Is the modification worth making ... 

Workers liability health, fires, explosion, leaks, spills and other risks Operator training Additional operating costs... 

Another crucial characteristic is that many chemical production processes are only cost-efficient if operated continuously. Continuously operated chemical production plants are expensive and complex technical systems. Typically they are optimized for operation at a specific conversion rate such that operational costs per output unit are minimized. Deviations from the optimal production rates typically cause additional operational costs stressing the small contribution margins. 

See Rejowski and Pinto (2008) for an example. However, often exists a regular pump rate for which the operational costs per flow unit are minimized. Deviations from this optimized pump rate usually incur additional operational costs due to increased (relative) energy consumption. See Hane and Ratliff (1995) or Hull (2005). 

The technique requires an investment of EUR 25000 for storage and transport equipment. The amortisation period is 8 years, with a discount rate of 8 %, for a 240 tonne/yr installation, resulting in a capital cost of EUR 17/tonne of treated sand. There are no additional operational costs since the operation of Ihe overall installation does not change. 

From the practical data from two foundries in France, additional operational costs were calculated. Tuyere injection showed an additional operational cost of EUR 0.35/tonne cast iron pellet injection EUR 0.90/tonne cast iron. This calculation does not take into account any extra costs for slag disposal or maintenance works. 

It has been pointed out (83,96,97) that the direct conversion of syngases of low H2 to CO ratio does not only save the investment of the shift reactor but reduces additionally operation costs due to savings in steam demand. Hence, the overall thermal efficiency can be improved. ... 

Additional Operating Costs for Imports C.I.F. price Port costs Product 1151 From To Cost... 

Coal fired boilers in the 5-25 MW range cost around 5125-175/kW, i.e. about S2.5 million for a 20 MW FBC boiler. The annualised cost can be computed as approximately 0.2 million, assuming a 25 year life time and interest. Additional operating costs for disposing of calcium sulphate would amount to around 1 25 million/year. 

The capital cost of FGD in new coal fired nlant is about S130-150/kW. This renresents 15-20% of total capital cost of the plant Additional operating costs are of the order of 3-5/tonne Retro-fitting onto existing plant, which may not always be possible in certain industrial locations, can increase the cost by a further 30-50% Overall the installation of FGD can increase the cost of electricity generated f1] by coal fired power stations by 10-20% ... 

In cases where steady-state conditions are achieved, Donnan dialysis can be effectively integrated with Hg(II) bioreduction to Hg(0) using mixed microbial cultures. While many organisms have been shown to perform Hg(II) bioreduction in pure culture, mixed microbial cultures offer the advantage of not requiring aseptic operational conditions, and can thus be much more readily integrated with the lEMB process, where aseptic conditions would involve additional operational costs and complicate the process unnecessarily. Efficient Hg(II) bioreducing mixed cultures have... 

Increasing the flow of product by 1.6 percent with no additional operating costs can be quite attractive. Payout of the forward loop from this source alone could be only a few weeks. ... 

The ROHS Directive would impose substitution on the use of lead, mercury, cadmium, hexavalent chromium, and brominated substances polybrominated diphenyl ethers (PBDE), and polybrominated biphenyls (PBB) in electrical and electronic equipment. The Directive would allow the Commission to establish maximum concentration values, where the presence of specific materials or components is tolerated. Industry welcomes this option because heavy metals covered by the Directive are present in most materials as naturally occurring substances. As for the economic implications, the Commission recognized that substantial costs would be incurred for replacing lead in solders and estimated the additional operating costs of using tin-based solders or other alternatives would be about 150 million Euros per year. 

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