Ammonia plant costs

Table 16.14 Capital Cost Estimate of Bare-Module Equipment Cost for an Ammonia Plant—Costs in Millions of U.S. Dollars (Year 2000)...

Coal is expected to be the best domestic feedstock alternative to natural gas. Although coal-based ammonia plants have been built elsewhere, there is no such plant in the United States. Pilot-scale projects have demonstrated effective ammonia-from-coal technology (102). The cost of ammonia production can be anticipated to increase, lea ding to increases in the cost of producing nitrogen fertilizers. 

The choice of a specific CO2 removal system depends on the overall ammonia plant design and process integration. Important considerations include CO2 sHp required, CO2 partial pressure in the synthesis gas, presence or lack of sulfur, process energy demands, investment cost, availabiUty of solvent, and CO2 recovery requirements. Carbon dioxide is normally recovered for use in the manufacture of urea, in the carbonated beverage industry, or for enhanced oil recovery by miscible flooding. 

Whereas the manufacturing cost is strongly influenced by energy prices, cost of money, and capital investment, ammonia selling prices are usually deterrnined by supply and demand. Therefore, the profitabiUty of ammonia plants is deterrnined by the margin between cost of production and ammonia price. 

This report addresses ammonia plant shutdowns over the listed time period in 40 countries. It provides a basis for comparing plant performance area by area leading to better control of reliability efforts while reducing maintenance and unplanned shutdown costs. Data are presented for shutdowns due to power, equipment, instrumentation, feedstock and product inventory control. 

Figure 9-1 (curve form=0.88) gives the cost of Ammonia Plants in 1960 versus capacity. This is a typical curve and it can be expressed in equation form as ... 

Figure 9-1 Plant cost as a function of capacity for two different cost exponents. The curve form = 0.88 is the same as that given by Berk, J. M. and Haselbarth. J. E. for Ammonia Plants in Cost Capacity Data IV Chemical Engineering, Mar. 20, 1961, p. 186.

Calculate the cost of building a 1,000 ton/day ammonia plant in 1969. From Table 9-3, which gives the values of C6, m, and B for the year 1967, the following figures were obtained ... 

The possible errors that can result when this method is used blindly can be illustrated by considering the case of ammonia plants. Suppose we recalculate the cost of the plant given in Example 9-3 by using Figure 9-1 (m=0.88). An investment cost of 35,000,000 for 1960 can be obtained from extrapolating that curve. The CEPI in 1960 was 102, so the estimated cost for 1969 is... 

Note that the estimates differ by a factor of three. What is the true cost of building such a plant, and why do these estimates differ by 26,900,000 To answer these questions the actual cost of building ammonia plants must be determined. 

Table 9-4 gives the capital costs for six ammonia plants that were built between 1959 and 1969. When plant no. 5 is compared with the three other plants that have a capacity of 1,000 tons/day, it appears that its reported cost is in error. This could be a misprint, or the plant might be producing urea, nitric acid, and/or ammonium nitrate as well as ammonia. The reader must always be careful, since errors occur frequently in printed material. This is why care should be used when the cost of a plant is estimated from only one piece of information. 

The project cost of a 1,000 ton/day ammonia plant that was built in 1969 has been obtained, using Equation 9-1 with an m of 0.70 and 0.88 and the CEPI. The results appear in Table 9-5. The effect of the exponential factor is very evident for plants 1 and 2. This effect does not occur for the other plants because their rated capacity was the desired 1,000 tons/day. Exponential factors are only used when capacity extrapolations must be made. This illustrates how a difference of 0.18 in the exponential factor (m) can have a profound effect on the projected cost if the scale-up factor is large. This can be further demonstrated by drawing lines of these two slopes on log-log paper (Fig. 9-1). As the lines get farther away from the base... 

The disparity between plant costs obtained before 1963 (Rims 1 and 2 in Table 9-5 and Fig. 9-1, with m = 0.88) and those obtained after 1966 (other runs and Fig. 9-1 with m = 0.70) can be explained by advances in technology. This was discussed in Chapter 3. The use of an exponential factor to scale up size assumes that a similar plant will be built. This was not true for ammonia plants. In fact, if a company is doing developmental research it should never be true. Each plant should be better than the last. 

In ammonium phosphate and mixed and blend fertilizer (G) production, another possibility is to design for a lower-pressure steam level (i.e., 42-62 atm) in the ammonia plant to make process condensate recovery easier and less costly. 

In the past, coal or heavy hydrocarbon feedstock ammonia plants were not economically competitive with plants where the feedstocks were light hydrocarbons (natural gas to naphtha). Because of changing economics, however, plants that can handle heavy hydrocarbon feedstock are now attracting increasing attention- In addition, the continuous development and improvement of partial oxidation processes at higher pressure have allowed reductions in equipment size and cost. Therefore, the alternate feedback ammonia plants based on a partial oxidation process may become economically competitive in the near future. 

From 1940 to 1950 the number of ammonia plants doubled then from 1950 to 1960 the number more than doubled again. Since 1963, there has been a revolution in ammonia-manufacturing technology. The advent of large singletrain plants has resulted in a large increase in production capacity, the shutdown of a number of smaller plants, and a reduction in manufacturing costs. Capacity tripled in the period from about 1958 to 1968. 

A few ammonia plants have been located where a hydrogen off-gas stream is available from a nearby methanol or ethylene operation (e.g., Canadian plants at Kitimat, BC and Joffre, Alberta). Gas consumption at such operations range from 25 million to 27 million BTU per tonne of ammonia, depending on specific circumstances. Perhaps more important, the capital cost of such a plant is only about 50% of the cost of a conventional plant of similar capacity because only the synthesis portion of the ammonia plant is required. However, by-product carbon dioxide is not produced and downstream urea production is therefore not possible56. 

In Table 5.33 the Benfield process options with different packings and activators are compared. This table assumes this equipment will be used in a 1,500 tonne per day ammonia plant. The costs assume the plant was built in... 

The installed costs (in January, 1997 dollars) for a Benfield Hybrid LoHeat Process in a 1,500 tonne per day ammonia plant are shown in Table 5.34. Table 5.35 lists the energy use in different Benfield processes that could be installed in a 1,500 tonne per day ammonia plant206. 

Due to increased feedstock costs, some new ammonia plant designs use fuel more efficiently but their capital cost may be higher. The recovery of the hydrogen and ammonia from the synthesis purge gas by a cryogenic unit or a membrane system results in an ammonia capacity increase of about 5%57. 

A large ammonia plant in 2001 is more fuel-efficient than plants that were built in the 1970 s and 1980 s. A typical world-scale plant that was built in the 1970 s consumed about 42 billion BTU of natural gas per tonne of ammonia produced. Retrofitting such a plant to improve fuel efficiency can reduce gas consumption to about 36 million BTU per tonne. Ammonia plants that were built in the late 1990 s use only about 30 million BTU per tonne of ammonia, are easier to operate and have slightly lower conversion costs. Some new plants also recover more than one million BTU per tonne by generating electricity from waste heat57. 

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