Plants capacities

Optimum plant capacity, i.e., the size of plant which yields the maximum return (Chapter 6), will be achieved if a degree of capacity utilization of 100% is reached 

3- 5 years after start-up. However, since the plant capacity must be decided about 

4- 5 years before start-up for planning and legal approval reasons, and plants which are not fully utilized over a period of time increase the specific production costs, it is essential to be able to look 7-10 years into the future in determining the optimum capacity. Therefore, precise knowledge of the market potential and of market growth trends is required. The relationship between production price and degree of capacity utilization is as follows  

PCf) = production costs at nominal capacity FC = fixed costs VC = variable costs Qj = effective plant capacity in t a  

The greater the uncertainty in the market studies and the newer the technology used, the greater will be the preference for choosing a lower capacity. Many Japanese chemical companies adopt this approach and prefer to set up several plants with smaller capacities. However, lower capacities result in higher specific plant costs and therefore in higher production costs. This is represented by the following empirical relationship  

In this example, the feed rates of crude oil to the primary unit and cracker, averaged over a period of time, can be anything from zero to the maximum plant capacity. The constraints are  

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As introduced in Section 14.2, bottlenecks in the process facilities can occur at many stages in a producing field life cycle. A process facility bottleneck is caused when any piece of equipment becomes overloaded and restricts throughput. In the early years of a development, production will often be restricted by the capacity of the processing facility to treat hydrocarbons. If the reservoir is performing better than expected it may pay to increase plant capacity. If, however, it is just a temporary production peak such a modification may not be worthwhile. 

Acetaldehyde, first used extensively during World War I as a starting material for making acetone [67-64-1] from acetic acid [64-19-7] is currendy an important intermediate in the production of acetic acid, acetic anhydride [108-24-7] ethyl acetate [141-78-6] peracetic acid [79-21 -0] pentaerythritol [115-77-5] chloral [302-17-0], glyoxal [107-22-2], aLkylamines, and pyridines. Commercial processes for acetaldehyde production include the oxidation or dehydrogenation of ethanol, the addition of water to acetylene, the partial oxidation of hydrocarbons, and the direct oxidation of ethylene [74-85-1]. In 1989, it was estimated that 28 companies having more than 98% of the wodd s 2.5 megaton per year plant capacity used the Wacker-Hoechst processes for the direct oxidation of ethylene. 

The world s largest producers are Perstorp AB (Sweden, United States, Italy), Hoechst Celanese Corporation (United States, Canada), Degussa (Germany), and Hercules (United States) with estimated 1989 plant capacities of 65,000, 59,000, 30,000, and 22,000 t/yr, respectively. Worldwide capacity for pentaerythritol production was 316,000 t in 1989, about half of which was from the big four companies. Most of the remainder was produced in Asia (Japan, China, India, Korea, and Taiwan), Europe (Italy, Spain), or South America (Brazil, Chile). The estimated rate of production for 1989 was about 253,000 t or about 80% of nameplate capacity. 

Fig. 3. Multipurpose plant capacity utilization where D represents products A, B, C, D, and E U the changeovers and X the time the plant was idle.

In 1993 there were over 100 organisations undertaking plasma fractionation woddwide, having plant capacities ranging from 4 to 1800 m /yr. Virtually all of these plants use methods based on those originally devised. Table 2 Hsts the six commercial manufacturers in the United States and the largest plasma fractionators woddwide. 

Estimates for a number of economic aspects of plasma fractionation can be made (200—206). The world capacity for plasma fractionation exceeded 20,000 t of plasma in 1990 and has increased by about 75% since 1980, with strong growth in the not-for-profit sector (Fig. 4). The quantity of plasma processed in 1993 was about 17,000 t/yr the commercial sector accounts for about 70% of this, with over 8000 t/yr in the form of source plasma from paid donors (Fig. 5). Plant capacities and throughput are usually quoted in terms of principal products, such as albumin and Factor VIII. These figures may not encompass manufacture of other products. 

U.S. capacity for producing biofuels manufactured by biological or thermal conversion of biomass must be dramatically increased to approach the potential contributions based on biomass availabiUty. For example, an incremental EJ per year of methane requires about 210 times the biological methane production capacity that now exists, and an incremental EJ per year of fuel ethanol requires about 14 times existing ethanol fermentation plant capacity. 

The long lead times necessary to design and constmct large biomass conversion plants makes it unlikely that sufficient capacity can be placed on-line before the year 2000 to satisfy EJ blocks of energy demand. However, plant capacities can be rapidly increased if a concerted effort is made by government and private sectors. 

Table 32. Biofuels Utilization and Production and Biomass-Fueled Electric Power Plant Capacities in the United States ...

Capacity Limitations and Biofuels Markets. Large biofuels markets exist (130—133), eg, production of fermentation ethanol for use as a gasoline extender (see Alcohol fuels). Even with existing (1987) and planned additions to ethanol plant capacities, less than 10% of gasoline sales could be satisfied with ethanol—gasoline blends of 10 vol % ethanol the maximum volumetric displacement of gasoline possible is about 1%. The same condition apphes to methanol and alcohol derivatives, ie, methyl-/-butyl ether [1634-04-4] and ethyl-/-butyl ether. 

The quantity of coproduct acetylene produced is sensitive to both the feedstock and the severity of the cracking process. Naphtha, for example, is cracked at the most severe conditions and thus produces appreciable acetylene up to 2.5 wt % of the ethylene content. On the other hand, gas oil must be processed at lower temperature to limit coking and thus produces less acetylene. Two industry trends are resulting in increased acetylene output (/) the ethylene plant capacity has more than doubled, and (2) furnace operating conditions of higher temperature and shorter residence times have increased the cracking severity. 

Worldwide, approximately 180, 000 t/yr acetylene product is recovered as a by-product within olefin plants. This source of acetylene is expected to increase as plant capacity and furnace temperature increase. The recovery may include compression and transfer of the acetylene product via pipelines directly to the downstream consumer. 

In 1991, U.S. plant capacity for producing acetylene was estimated at 176, 000 t/yr. Of this capacity, 66% was based on natural gas, 19% on calcium carbide, and 15% on ethylene coproduct processing. Plants currendy producing acetylene in the United States are Hsted in Table 13. 

Plant capacity is a function of feed size distribution and Hberation. Separators can accept a size range as wide as 50—1000 p.m. Capacities are typically 1000 2500 kg/(h-m) based on rotor length which could be up to 3 m and have dia 150—250 mm. The feed should be as dry as possible because moisture interferes seriously with separation. Heaters are usually provided before the feed enters the charged field. Final cleaning is often conducted in electrostatic-type separators. Electrostatic shape separation, a newer form of ion bombardment separation, involves separation of particles based on shape and density without consideration to conductivities (37). 

Titanium dioxide [13463-67-7] is by far the most often used inorganic pigment (14). In 1993 the estimated worldwide plant capacity was around 3.7 X 10 t. Plant utilization in that year was only about 78%, thus the world demand for Ti02 pigment in 1993 can be estimated to have been about 2.9 X 10 t. Growth in worldwide production of this pigment has been phenomenal since it was first produced in 1918. 

United States production of phenylenediamines is shown ia Table 3 (30). Production of both the m- and -phenylenediamines are not reported siace they are produced captively for use ia the manufacture of polyamides. However, aromatic polyamide plant capacity is about 30,000 t/yr. 

The quantity of catalyst used for a given plant capacity is related to the Hquid hourly space velocity (LHSV), ie, the volume of Hquid hydrocarbon feed per hour per volume of catalyst. To determine the optimal LHSV for a given design, several factors are considered ethylene conversion, styrene selectivity, temperature, pressure, pressure drop, SHR, and catalyst life and cost. In most cases, the LHSV is ia the range of 0.4—0.5 h/L. It corresponds to a large quantity of catalyst, approximately 120 m or 120—160 t depending on the density of the catalyst, for a plant of 300,000 t/yr capacity. 

Production of a-methylstyrene (AMS) from cumene by dehydrogenation was practiced commercially by Dow until 1977. It is now produced as a by-product in the production of phenol and acetone from cumene. Cumene is manufactured by alkylation of benzene with propylene. In the phenol—acetone process, cumene is oxidized in the Hquid phase thermally to cumene hydroperoxide. The hydroperoxide is spHt into phenol and acetone by a cleavage reaction catalyzed by sulfur dioxide. Up to 2% of the cumene is converted to a-methylstyrene. Phenol and acetone are large-volume chemicals and the supply of the by-product a-methylstyrene is weU in excess of its demand. Producers are forced to hydrogenate it back to cumene for recycle to the phenol—acetone plant. Estimated plant capacities of the U.S. producers of a-methylstyrene are Hsted in Table 13 (80). 

Shell is the sole principal U.S. manufacturer of petroleum sulfonate having an estimated aimual plant capacity of ca 27,000 metric tons Witco and Peimrico-Morco are beheved to supply a total of ca 7,000 metric tons aimuaHy. 

Modifications of the basic process are undersoftening, spHt recarbonation, and spHt treatment. In undersoftening, the pH is raised to 8.5—8.7 to remove only calcium. No recarbonation is required. SpHt recarbonation involves the use of two units in series. In the first or primary unit, the required lime and soda ash are added and the water is allowed to settie and is recarbonated just to pH 10.3, which is the minimum pH at which the carbonic species are present principally as the carbonate ion. The primary effluent then enters the second or secondary unit, where it contacts recycled sludge from the secondary unit resulting in the precipitation of almost pure calcium carbonate. The effluent setties, is recarbonated to the pH of saturation, and is filtered. The advantages over conventional treatment ate reductions in lime, soda ash, and COg requirements very low alkalinities and reduced maintenance costs because of the stabiUty of the effluent. The main disadvantages are the necessity for very careful pH control and the requirement for twice the normal plant capacity. 

Includes one thermal black plant (capacity, 25,000 t). Estimate. 

Number of plants Capacity, 10 Number of plants Capacity, 10 ... 

The specific use appHcations of sodium chlorite varies from country to country. Important factors are the regulatory and environmental laws in effect for air and water quaUty standards. Sodium chlorite is generally priced at about four to six times the cost of sodium chlorate. The Hst price of 80% technical-grade NaC102 in January 1991 was 2.65/kg (146). In 1990, the estimated consumption of sodium chlorate for the production of sodium chlorite in Canada was about 2700 metric tons and about 9100 metric tons in the United States (74). In Western Europe, the 1990 chlorate consumption estimate was about 11,000 metric tons. A summary of 1991 U.S. and foreign sodium chlorite producer annual plant capacities in various world market areas is given in Table 3. 

Plant capacities for the production of benzyl chloride in the western world totaled 144,200 t/yr in 1989. Monsanto, with plants in Belgium (23,000 t/yr) and Bridgeport, New Jersey (40,000 t/yr) is the largest producer. Bayer in West Germany (20,000 t/yr) and Tessendedo Chemie in Belgium (18,000 t/yr) are also principal producers. 

The Pott-Broche process (101) was best known as an early industrial use of solvent extraction of coal but was ended owing to war damage. The coal was extracted at about 400°C for 1—1.5 h under a hydrogen pressure of 10—15 MPa (100—150 atm) using a coal-derived solvent. Plant capacity was only 5 t/h with an 80% yield of extract. The product contained less than 0.05% mineral matter and had limited use, mainly in electrodes. 

Order-of-Magnitude Estimates. Unit capital cost data (dollars per aimual ton of product) are occasionally reported for chemical plants. These data can be multiphed by a selected plant capacity to estimate a capital cost. This is, however, feasible only if the reference process, conditions, and capacity are similar. 

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