NSPS

Normal Superphosphate. From its beginning as the first commercial phosphate fertilizer, normal superphosphate (NSP), also called ordinary or single superphosphate, has continued among the top fertilizers of the world (Fig. 8). Use of normal superphosphate decreased steadily on a percentage basis because of growing production of more concentrated materials, but grew on a P2 s basis to a maximum of 6.7 x 10 t... 

The sustained world popularity of NSP results from simplicity of production and high agronomic quaHty as a carrier of available P2O5, calcium, sulfur, and usually some incidental micronutrients. In terms of agronomic value for large numbers of crops, no phosphate fertilizer has been shown to be superior to NSP. It is likely to remain in strong demand in parts of the world where simplicity of production or sulfur fertilization has high priority and where transportation costs are not prohibitive. 

NSP is produced by the reaction of phosphate rock and sulfuric acid. This reaction quickly yields a soHd mass containing monocalcium phosphate monohydrate and gypsum, CaSO 2H20, according to the simplified equation... 

Properties. Important properties of NSP are free acid content, as H2SO4, 1—2% moisture content, 5—8% P2O5 soluble, in neutral citrate... 

Production Technology. A moderately high (33.5% 2 5 BPL) grade of phosphate rock is required for the production of a product that contains 20% available P2 5 Significant process variables in the manufacture of NSP are Hsted in Table 5. 

A modification of the NSP production process involves use of a mixture of sulfuric and phosphoric acids. The resultant product is referred to as enriched superphosphate and can contain up to 40% P2O5. The usual P2O5 content of enriched superphosphate is about 27%. 

Cost Fa.ctors, The dehvered costs of the phosphate rock and sulfuric acid raw materials often account for more than 90% of the cost of producing NSP, thus the production cost varies considerably with plant location. Because the rock is richer in P2O5 than is the low analysis NSP product, NSP need not be produced near the phosphate mine. However, deUvery of sulfuric acid and shipment of product to market are important cost factors. Most United States NSP plants have been located east of the Mississippi river, with concentration in the southeastern and extreme southern parts of the country where the largest use of the product has occurred. Production and use of the product also has been high in California. 

The complete chemistry of TSP production has been studied and reported in great detail (34). As in the production of NSP there are also reactions with impurity minerals. In fact, the increasing amounts of such impurities in U.S. commercial phosphate rocks, especially those from Florida, are now reflected in somewhat lowered amounts of citrate-soluble P2O5 product. The range of constituents in commercial TSP from wet-process acid and phosphate... 

Economics. In contrast to NSP, the high nutrient content of TSP makes shipment of the finished product preferable to shipping of the raw materials. Plants, therefore, are located at or near the rock source. The phosphoric acid used, and the sulfuric acid required for its manufacture, usually are produced at the site of the TSP plant. As in the case of NSP, the cost of raw materials accounts for more than 90% of the total cost. Most of this is the cost of acid. 

Environmental intmsion from MHD plants is projected to be not only weU below the mid-1990s acceptable limits, but also low enough to satisfy the more stringent requirements expected in the future. Emissions of SO, particulates can be reduced to levels weU below the 1979 NSPS without... 

Fig. 9. Measured coal-fired flow faciUty (CFFF) NO emissions where ( ) represents high sulfur coal, (e) low sulfur coal, (A) low sulfur coal having K2/S = 1.15, and ( ) LMF5-G. A, Illinois No. 6 coal (3% S) B, Montana Rosebud coal (1% S), and the NSPS range is between the dotted lines. To...

Fig. 10. Effect of potassium on SO2 removal where (—) represents the NSPS limit, and (V) represents LMF4-T, ( ) LMF4-U, and ( ) LMF4-V.

The plant is designed to satisfy NSPS requirements. NO emission control is obtained by fuel-rich combustion in the MHD burner and final oxidation of the gas by secondary combustion in the bottoming heat recovery plant. Sulfur removal from MHD combustion gases is combined with seed recovery and necessary processing of recovered seed before recycling. 

The basic seed processing plant design is based on 70% removal of the sulfur contained in the coal used (Montana Rosebud), which satisfies NSPS requirements. Virtually complete sulfur removal appears to be feasible and can be considered as a design alternative to minimize potential corrosion problems related to sulfur in the gas. The estimated reduction in plant performance for complete removal is on the order of 1/4 percentage point. The size of the seed processing plant would have to be increased by roughly 40% but the corresponding additional cost appears tolerable. The constmction time for the 500 MW plant is estimated to be ca five years. 

Emission Standards. In order to have a nationwide basis for air pollution emission controls and to set a minimum emission limit, the EPA developed New Source Performance Standards (NSPS). The NSPS set specific poUutant emission limits or describe the best available control technology (BACT) that should be appUed at that source. The EPA has issued NSPS, which apply to new constmction as weU as to large modifications, for many different sources. Sources in the chemical industry include the foUowing. 

In 1971, EPA estabhshed New Source Performance Standards (NSPS), which required coal-fired utihty boilers built after August 17, 1971 to emit no... 

Fig. 7. Environmental emissions, where represents new source performance standards (NSPS) requirements 1 represents a pulverized coal (PC) plant ...

BSRT Biomass solids retention time NSPS New source performance standards... 

Control of NO under the CAAA of 1990 will be accomphshed through the issuance of a revised NSPS in 1994, with the objective of reducing emissions by 2 miUion tons a year from 1980 emission levels. The teemission standards will not apply to cyclone and wet bottom boilers, unless alternative technologies are found, as these cannot be retrofitted with existing LNB technologies. 

New Source Performance Standards (NSPS) were promulgated under Sections 111(b) and 129 of the CAA Amendments of 1990. The NSPS apphes to new municipal sohd-waste combustors (MWCs) with... 

Regulated Pollutants The NSPS regulates MWC emissions, and nitrogen oxides (NOJ emissions from individual MWC units larger... 

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