Heavier feedstocks likely for ammonia Ammonia producers throughout the world are facing new constraints on feedstocks posed by the world energy imbalance. In the near future, the worldwide pattern of feedstocks used to make ammonia will remain about the same, although the geographic pattern for use of different hydrocarbons may change. But later, a. shift to much more use of heavy hydrocarbons and of coal could develop, according to engineers at M.W. Kellogg. Ammonia demand will continue to grow under pressure of population growth and will be met by increasing production from large-size units with capacities ranging up to about 1500 metric tons a day, according to Leon J. Buividas, manager of inorganic processing for Kellogg. Capacity to make ammonia will reach 77 million metric tons worldwide in 1977, Mr. Buividas told the 78th national meeting of the American Institute of Chemical Engineers in Salt Lake City, double the 38 million metric tons produced in 1967. The bulk of synthetic ammonia produced today—75 to 80%—comes from steam reforming of hydrocarbons, and about 60 to 65% of this is based on natural gas feedstock. Most production in North America and Europe will continue to be based on natural gas feedstocks. But as gas reaches a cost of $1.00 per million B.t.u., other feedstocks will get more serious consideration, particularly fuel oils. At the same time, with gas abundant in the Middle East and North Africa, ammonia production in large volume could begin there. Where natural gas becomes relatively expensive compared to heavier hydrocarbons, a shift to partial oxidation processes from reforming will occur, according to Mr. Buividas and his associates at Kellogg, James A. Finneran and Orlando J. Quartulli. Even where natural gas continues to be used as feedstock, liquid fuels will be used more in steam reformer units to reduce production costs. Coal-based ammonia production can be justified where the cost of coal is low, where gas does not exist, and where the alternative is expensive imported oil (for example, in South Africa and India), Mr. Buividas says. Use of coal will be governed to a great degree by whether an attractive price differential can be maintained on a longterm basis. High costs of mining and transportation reduce coal's potential economic advantages, however. The Kellogg engineers conclude that operating costs are optimum for plants in the capacity range of 1000 to 1500 tons a day. Potential savings in total cost per ton of ammonia begin to diminish as capacities exceed 2000 tons a day. For their comparisons of feedstock and fuels for making ammonia, the en-
gineers base their analysis on a plant with a capacity of 1000 tons a day. For a plant using natural gas as feedstock and fuel, gas costs of about 10 cents per million B.t.u. can make the feed and fuel cost as low as 6% of the total cost of making a ton of ammonia, Mr. Buividas says. If the gas cost goes to $1.00 per million B.t.u., feed and fuel can take some 33% of the operating costs. The wide cost differential appears to favor building ammonia plants in places where gas costs very little. However, prudent plant designers and operators add about 30% to the plant investment for any inventory of spare parts and additional off-site facilities for plants in undeveloped countries with low gas costs. When this is done, a cost differential of $31 a ton can drop to about $15 a ton. However, if gas cost rises to $1.50 to $2.00 per million B.t.u., then production of ammonia where feed costs are low becomes increasingly more economical. Naphtha-based ammonia plants require an investment of about 15% more than a natural gas-based plant. For a 1000 ton-a-day plant, this added investment is about $7 million, Mr. Buividas says. In addition, the cost of feed is significantly greater for naphtha. For such reasons, naphtha-based ammonia plants are unlikely to be built in the U.S. Going to heavy oil feeds, such as fuel oil, could lead to economic advantages if the cost differential between gas and such oils is large enough. But the feed and fuel advantage is offset by much higher investment cost. Use of heavy oil feeds requires a partial oxidation process in place of steam reforming. Such processes require plants with additional equipment, including an air separation unit, additional desulfurization, carbon removal and recycle, and other facilities. Opinion varies widely among engineers on the investment differential between gas-fed and heavy-oil-fed plants. Some put the difference at as low as 20%; others at 40%. Mr. Buividas and his associates estimate that partial oxidation of fuel oil has an economic advantage over natu-
Feedstock costs radically influence ammonia costs Feedstock
Natural gas Naphtha
Fuel oil
Material cost Per million B.t.u. Per ton
Ammonia cost* Per ton
$0.10 0.50 1.00 0.50 1.00 2.00
— — — $18.90 37.80 75.60
$6.46 18.32 33.80 19.94 36.80 70.54
0.29 0.58 0.87 1.00
10.00 20.00 30.00 34.00
12.54 22.19 31.84 36.19
a Operating cost per ton of ammonia produced in plant with capacity of 1000 tons per stream day. Source: M. W. Kellogg Co.
ral gas costing $1.00 per million B.t.u. when fuel oil costs less than about 90 cents per million B.t.u. If both gas and fuel oil cost $1.00 per million B.t.u., gas still has an advantage of $2.39 a short ton of ammonia in operating costs. The cost differential is more favorable for fuel oil when compared to naphtha, but nears zero at a cost of $1.00 per million B.t.u. Coal-based ammonia plants have an even larger investment cost disadvantage, Mr. Buividas says. Cost of a coalbased plant may be more than 1.75 times that of a natural gas-based plant and at least 1.3 times that of a fuel-oilbased plant. Feed and fuel requirements also are higher for coal-based plants. Heat requirements for a ton of ammonia are about 50% more for coal than natural gas, even including credits for by-products from coal gasification. They are about 15% more for naphtha or fuel oil compared to gas. The quantity of feed and fuel for a ton of ammonia generally is double for coal compared to naphtha or fuel oil. If coal costs less than about $15 a ton, however, feed and fuel costs per ton are less than using natural gas costing $1.00 per million B.t.u.
PVC makers hit with health hazard suit A class action suit has been filed against Goodyear Tire & Rubber and Bordon Chemical alleging damage to the health of supermarket employees who wrap meat in polyvinyl chloride packaging films manufactured by these companies. The suit, brought by Florine Schultz on behalf of herself and more than 283 other meat wrappers for the Pick-n-Pay supermarket chain in the Cleveland area, asks for more than $285 million in compensatory and punitive damages. The suit claims that these companies misrepresented the safety of PVC packaging films to encourage purchase of their products even though they were aware that the films had not received adequate clinical testing. As a result, meat wrappers were exposed to dangerous air contamination caused by thermal decomposition of the films as they were cut by a hot wire in the packaging process. Inhalation of the fumes released from the film caused skin and throat irritation among the workers and is linked to serious skeletal deterioration and permanent heart and brain injury, the suit claims. A Borden official said that the company had not yet received a copy of the complaint as of early last week. However, public statements by Mrs. Schultz's lawyer that there is medical evidence linking PVC packaging wraps with cancer and other physical injuries is "without foundation," the Borden official points out. A Goodyear spokesman says that the company is "preSept. 2.1974C&EN
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