Cost, acid plant

Other acetyl chloride preparations include the reaction of acetic acid and chlorinated ethylenes in the presence of ferric chloride [7705-08-0] (29) a combination of ben2yl chloride [100-44-7] and acetic acid at 85% yield (30) conversion of ethyUdene dichloride, in 91% yield (31) and decomposition of ethyl acetate [141-78-6] by the action of phosgene [75-44-5] producing also ethyl chloride [75-00-3] (32). The expense of raw material and capital cost of plant probably make this last route prohibitive. Chlorination of acetic acid to monochloroacetic acid [79-11-8] also generates acetyl chloride as a by-product (33). Because acetyl chloride is cosdy to recover, it is usually recycled to be converted into monochloroacetic acid. A salvage method in which the mixture of HCl and acetyl chloride is scmbbed with H2SO4 to form acetyl sulfate has been patented (33). 

Because of the highly corrosive nature of the nitric acid streams, adipic acid plants are constmcted of stainless steel, or titanium in the more corrosive areas, and thus have high investment costs. 

In cases where low-cost fuel is available, a gas turbine may be chosen. This would obviously make it possible to export the surplus steam. Some compressor trains in nitric acid plants are, indeed, using a gas turbine as the associated or complementary driver. 

Flue gas treatment (FGT) is more effective in reducing NO, emissions than are combustion controls, although at higher cost. FGT is also useful where combustion controls are not applicable. Pollution prevention measures, such as using a high-pressure process in nitric acid plants, is more cost-effective in controlling NO, emissions. FGT technologies have been primarily developed and are most widely used in Japan. The techniques can be classified as selective catalytic reduction, selective noncatalytic reduction, and adsorption. 

It is most economical when high-grade ores are used, becoming less economical with poorer feed materials containing iron, because of the production of chloride wastes from which the chlorine cannot be recovered. By contrast the sulfate process cannot make use of rutile which does not dissolve in sulfuric acid, but is able to operate on lower grade ores. However, the capital cost of plant for the sulfate process is higher, and disposal of waste has proved environmentally more difficult, so that most new plant is designed for the chloride process. 

Later, when nitric acid was manufd from synthetic ammonia at relatively low cost, synthetic sodium nitrate was made from it either thru the reaction between nitric acid and soda ash, or by direct absorption of nitrogen dioxide in an aq soln of Na carbonate (see above equation). The Na nitrate-nitrite soln was then heated with excess nitric acid to convert the nitrite to nitrate, and the NO thus produced was recycled to the nitric acid plant (Ref 6)... 

Estimate the capital cost for the nitric acid plant shown in Figure 4.2, Chapter 4. 

One of the main drivers for the development of new sulphuric acid catalysts over the last decades has been the desire to reduce S02 emissions from sulphuric acid plants without costly tail gas cleaning or an additional interbed... 

In 1746 Dr. John Roebuck (1718-1794), of Birmingham, and Samuel Garbett substituted lead chambers, each about six feet square, for the glass globes introduced six years previously by Joshua Ward (22), an improvement which cut down the cost of producing the acid to one-fourth of its former amount (12, 13). Three years later, after the substitution of sulfuric acid for sour milk in the old process of bleaching had created a demand for the acid, Roebuck and Garbett erected a sulfuric acid plant at Prestonpans, on the east coast of Scotland (14). Since a salt industry also flourished there, Prestonpans was named for the salt pans. 

Smelter Acid. If acid is produced involuntarily, as in a smelter operation, it is possible to estimate the cost of acid production in the same manner as that for an elemental sulfur acid plant. To the smelter, however, acid output is simply a mandated concomitant of the process required to produce the metal. Depending on the location of the smelter, the sources of demand, the size of the market, and competition from other producers, the acid sale price may or may not be sufficiently high even to yield a positive net-back, much less a desired rate of return on investment for the acid portion of the operation. This situation does not necessarily lead to closure. Positive or negative, the effect should be registered only in the overall profitability of the entire smelter operation. 

W.D. Baasel, Preliminary Chemical Engineering Plant Design pp.242-243 (Table 9.3 Capital Cost Estimate of Nitric Acid Plant), Elsevier, New York (1976). 

The method used is outlined in Ref. CE9 (Chapter 4). The capital cost estimate is adjusted to the correct plant capacity by applying a scaling index. The appropriate scaling index for nitric acid plants is 0.6 (Ref. CE9 Table 19, p.184). Therefore ... 

Table E.4 in Appendix E provides a breakdown of the total production costs encountered in the manufacture of nitric acid. The costing is based upon paying the full market price for ammonia feed (at A 300/tonne). All tangible input and output valuesarecalculated using the results of the mass and energy balances detailed in Section 7.3. Labour requirements are evaluated assuming only two operators per shift and the usual labour maintenance requirements for nitric acid plants (see Ref. CE1 1).

The capital cost of an integrated SCR unit for a new 1,000 tonne/day plant is estimated to be 1.5% of the total capital cost of the nitric acid plant. This cost includes the cost of the SCR catalyst but excludes spare parts. The capital cost of an end-of-pipe SCR unit for an existing 1,000 tonne/day plant is estimated to be 3% to 6% of the total capital cost of the nitric acid plant. But this is very dependent on the type of nitric acid process. The SCR will increase operating costs by 1.1% when NOx in the tail gas is reduced from 1,000 ppmv to 200 ppmv. The maintenance cost of the SCR unit is typically 2.5% of the capital cost97. 

Cobalt oxide (C03O4) catalysts are being used in some nitric acid plants as an alternative to platinum-rhodium (Pt-Rh). They generate less N2O, cost less and have a longer campaign life than Pt-Rh gauzes. (A paper in 2000 reported a conversion rate of ammonia to nitrous oxide as low as 0.5% over cobalt oxide catalyst)222. 

The SCR technology can be used in any nitric acid plant. The costs per tonne of CO2 equivalents removed range from 1.3 to 3.0 EUR. The reductant (natural gas or LPG) is the largest cost item in these processes and makes up 20% to 60% of the total costs221. 

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