Gasifier construction

Status of Indirect Liquefaction Technology The only commercial indirect coal liquefaction plants for the production of transportation fuels are operated by SASOL in South Africa. Construction of the original plant was begun in 1950, and operations began in 1955. This plant employs both fixed-bed (Arge) and entrained-bed (Synthol) reactors. Two additional plants were later constructed with start-ups in 1980 and 1983. These latter plants employ dry-ash Lurgi Mark IV coal gasifiers and entrained-bed (Synthol) reactors for synthesis gas conversion. These plants currently produce 45 percent of South Africa s transportation fuel requirements, and, in addition, they produce more than 120 other products from coal. 

Eastman Chemical Company has operated a coal-to-methanol plant in Kingsport, Tennessee, since 1983. Two Texaco gasifiers (one is a backup) process 34 Mg/h (37 US ton/h) of coal to synthesis gas. The synthesis gas is converted to methanol by use of ICl methanol technology. Methanol is an intermediate for producing methyl acetate and acetic acid. The plant produces about 225 Gg/a (250,000 US ton/a) of acetic anhydride. As part of the DOE Clean Coal Technology Program, Air Products and Cnemicals, Inc., and Eastman Chemic Company are constructing a 9.8-Mg/h (260-US ton/d) slurry-phase reactor for the conversion of synthesis gas to methanol and dimethyl... 

Some 20 IGCC plants, in various forms, some with other gasifiers but most using oxygen, are now operating or are in the process of construction. Modifications of the IGCC plant to sequestrate the carbon dioxide produced will be discussed in Chapter 8. 

Number of Commercial Shell Gasifiers (Including Those Under Construction)... 

Based on a survey reported for 2003, there are 163 commercial gasification projects worldwide consisting of a total of 468 gasifiers.4 More than 120 plants began their operations between 1960 and 2000 with the majority (more than 72 plants) commissioned after 1980. Up to 34 new plants are at various stages of planning and construction. 

This paper reports on research involved the design, construction, and evaluation of a portable instrument, a "luminoscope", for detecting skin contamination by coal tars via induced fluorescence. The instrument has been used in the laboratory to measure the fluorescence of various coal tars and recycle solvents from liquefaction processes spotted on filter paper on rat and on hamster skin. The practical use of the devices in field test measurements to monitor skin contamination of workers at coal gasifier is discussed. The paper also discusses the practicality and usefulness of the luminescence method for detecting skin contamination. 

Fortunately, efforts in addition to those of DOE are being implemented. The Tennessee Valley Authority is sponsoring the construction of an entrained flow gasifier to operate at elevated pressure and to provide synthesis gas to their small Ammonia Plant at Muscle Shoals, Alabama. Ironically, this ammonia plant was originally built using coke-fed water gas sets for synthesis gas production. It was converted to use natural gas steam reforming when cheap natural gas became available. The use of coal will provide valuable data on MBG production and purification. 

None of these current processes has a distinct advantage over the other two in all situations of coal gasification. However, we believe that the Winkler is best suited for the production of methanol because it yields a clean gas with a low inerts content. Other advantages include the plant s low environmental impact, the minimal coal preparation required and the simple construction of the Winkler gasifier. 

A typical world scale plant produces 850 kt/y (2,500 t/d) methanol and requires about 32 PJ/y of gas . Typical construction period is three years with a lifetime of 15 years. Recently, some plants have been constructed at double this capacity (5,000 t/d) and claim much reduced capital costs, which is detailed in the second column. However, although economy of scale applies, some of the reduction in capital claimed probably comes from importing oxygen into the complex to run an auto-thermal gasifier. The coal case produces about 1.4 million tonnes of methanol and is based on the optimum size of an entrained-bed gasifier and requires 45PJ (about 1.8 million tonnes) of black coal. The coal option produces by-products of sulphur, ash and electricity. The fixed variable relationship plotted in Figure 11.9. 

Tampella Corporation is commercializing the U-GAS process, which was developed by the Institute of Gas Technology. Tampella has constructed a 10-MW, integrated U-GAS-combined cycle power plant in Finland that uses coal, peat, and wood wastes as feedstocks. U-GAS incorporates a single-stage, fluid-bed gasifier in which coal reacts with steam and air at 950 to 1090°C at pressures... 

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