Surpluses

Next, we carry out a heat balance within each shifted temperature interval according to Eq. (6.1). The result is given in Fig. 6.17. Some of the shifted intervals in Fig. 6.17 are seen to have a surplus of heat... 

Interval Temperature Stream Population INTERVAL ICPc ICPh INTERVAL Surplus/ Deficit... 

Now cascade any surplus heat down the temperature scale from interval to interval. This is possible because any excess heat available from the hot streams in an interval is hot enough to supply a deficit in the cold streams in the next interval down. Figure 6.18 shows the cascade for the problem. First, assume that no heat is supplied to the first interval from a hot utility (Fig. 6.18a). The first interval has a surplus of 1.5 MW, which is cascaded to the next interval. This second interval has a deficit of 6 MW, which reduces the heat cascaded from this interval to -4.5 MW. In the third interval the process has a surplus of 1 MW, which leaves -3.5 MW to be cascaded to the next interval, and so on. 

The shaded areas in Fig. 6.24, known as pockets, represent areas of additional process-to-process heat transfer. Remember that the profile of the grand composite curve represents residual heating and cooling demands after recovering heat within the shifted temperature intervals in the problem table algorithm. In these pockets in Fig. 6.24, a local surplus of heat in the process is used at temperature differences in excess of AT ,in to satisfy a local deficit. ... 

For any one case, say the base case, the project cashflow is constructed by calculating on an annual basis the revenue items (the payments received by the project) and then subtracting the expenditure items (the payments made by the project capex, opex and host government take). For each year the balance is the annual cash surplus (or cash deficit). Flence, on an annual basis... 

Cash surplus is also commonly known as net cash flow. 

Having discussed the elements of the cash surplus/deficit calculation, remember that in any one year this can be calculated from... 

The project cashflow s constructed by performing the calculation for every year of the project life. Atypical project cashflow is shown in Figure 13.9, along with a cumulative cashflow showing how cumulative revenue is typically split between the capex, opex, the host government (through tax and royalty) and the investor (say the oil company). The cumulative amount of money accruing to the company at the endof the project is the cumulative cash surplus or field life net cash flow. 

The cumulative cash surplus accrues to the investor at the end of the economic lifetime of the project, and may be termed the field life net cashflow. 

The proflt-to-investmentratio (PIR) may be defined in many ways, and is most meaningful when deflated and discounted. On an undeflated and undiscounted basis, the PIR may be defined as the ratio of the cumulative cash surplus to the capital investment. This indicates the return on capital investment of the project, is simple to calculate, but does not reflect the timing of the income/investment in the project. 

The project cashflow discussed so far follows a pattern typical of E P projects a number of years of expenditure (giving rise to cash deficits) at the beginning of the project, followed by a series of cash surpluses. The annual cashflows need to be evaluated to incorporate the timing of the cash flows, to account for the effect of the time value of monef. The technique which allows the values of sums of money spent at different times to be consistently compared is called discounting. 

Year Cash Surplus ( m) Discount Factor (mid year) Discounted Cashflow ( m)... 

The total undiscounted cash surplus (the ultimate cash surplus) is 190 m. The total discounted cash surplus ( 24.8 m) is called the net present value (NPV) of the project. Since in this example the discount rate applied is 20%, this figure would be the 20% NPV also annotated NPV(20). This is the present value at the beginning of Year 1 of the total project, assuming a 20% discount rate. 

The cumulative cashflow was used to derive ultimate cash surplus - the final value of the cumulative cashflow maximum exposure - the maximum value of the cash deficit payout time - the time until cumulative cashflow becomes positive. 

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Using estimates of proven reserves and commitments to energy and chemical uses of gas resources, the net surplus of natural gas in a number of different countries that might be available for major fuel methanol projects has been determined. These are more than adequate to support methanol as a motor fuel. 

Chlorine cannot be stored economically or moved long distances. International movements of bulk chlorine are more or less limited to movements between Canada and the United States. In 1987, chlorine moved in the form of derivatives was 3.3 million metric tons or approximately 10% of total consumption (3). Exports of ethylene dichloride, vinyl chloride monomer, poly(vinyl chloride), propylene oxide, and chlorinated solvents comprise the majority of world chlorine movement. Countries or areas with a chlorine surplus exported in the form of derivatives include Western Europe, Bra2il, USA, Saudi Arabia, and Canada. Countries with a chlorine deficit are Taiwan, Korea, Indonesia, Vene2uela, South Africa, Thailand and Japan (3). 

Alternatively, short-rotation hybrid poplar and selected grasses can be multicropped on an energy plantation in the U.S. Northwest and harvested for conversion to Hquid transportation fuels and cogenerated power for on-site use in a centrally located conversion plant. The salable products are Hquid biofuels and surplus steam and electric power. This type of design may be especially useful for larger land-based systems. 

Most modem coke ovens operate on a regenerative heating cycle in order to obtain as much surplus gas as possible for use on the works, or for sale. If coke-oven gas is used for heating the ovens, the majority of the gas is surplus to requirements. If producer gas is used for heating, much of the coke-oven gas is surplus. 

Central Shipping and Receiving Building. Such a building could also include many other warehousing and distribution operations such as a mailroom, printing/copy center, stores, surplus warehouse, etc. 

Stores Building and Surplus Warehouse. This could be a separate building or it could be combined with the central shipping and receiving building. In some companies such a building would require special security installations. 

Material Control. Production forecasting, scheduling, direct and iadirect material procurement, purchasiag, shipping and receiving, storerooms, storage, surplus equipment, and reclamation of materials are iacluded. 

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