Browsing by Author "Swai & Wolfred, H. Njeri Kiragu & J"

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    Preliminary plant design and economics for the production of fertilizer-grade urea from ammonia and carbon dioxide
    (University of Dar es Salaam, 1978) Swai & Wolfred, H. Njeri Kiragu & J
    A urea plant with a daily capacity of 1000MT and a stream efficiency of 300 days per year is proposed. The preliminary plant design and economic evaluation of this venture have been carried out. Survey of urea synthesis processes has shown that the total recycle stami carbon CO2 stripping process is the best choice. Liquid ammonia and compressed carbon dioxed form product urea via an intermediate product, ammonium carbonate. The synthesis section operates at high temperature and pressure. The uncontrolled ammonia and carbon dioxide are separated from the urea solution and recycled to synthesis section in the form of carbonate solution. The urea solution is flash-evaporated, prilled and screened. The undersize and oversize prills are recycled to evaporation as urea solution. We have designed and selected the various pieces of equipment. Consumption of stream (the main utility) is 60,000 kg/hr. it is produced in the bollar as high pressure steam and then stepped down in pressure via the carbon dioxide compressor and power-generating turbines. Total capital estimate is Tsh. 189.8 million. At a local price of urea of Tsh. 1880/ton, the gross income in the first year of operation is Tsh. 564 million against total production cost of Tsh 503.5 million. Broak-even and shut-down points occur at 72% and 50% production capacity respectively. Rates of return on investment before and after income tax are 25.9% and 14.9%. Discounted cash flow rate of return is 23.7%. pay-back periods excluding and including financing interest are 3.8 and 6 years respectively. This venture proves to be very profitable and we recommend that detailed-estimate and final design should be done as soon as possible. Market research and promotion should prece destart-up.