Gasifiers

In addition to coal, gasifiers can be used on a variety of feedstocks. Almost anything that will burn can be gasified. There are many types of gasifiers. Some are fluidized beds, and others are moving beds. The coal fed to the gasifier can be dry or a coal/ water slurry. 

Shadle, D. A. Berry, and M. Syamlal, Coal conversion processes, gasification, Kirk-Othmer Encyclopedia of Chemical Technology, 5th Ed., John Wiley Sons, 2001. 

Murakami, T. Suda, Y. Matsuzawa, and H. Tani, The superior technical choice for dual fludized bed gasification, Ind. Eng. Chem. Research, 45, 2281-2286 (2003). 

---

Benfield process Removal of carbon dioxide from fuel gases, such as those obtained by gasifying coal in the Lurgi process, by countercurrent scrubbing of the gases by hot potassium carbonate solution. 

Konjac flour Konygreen Koppers-Totzek Koppers-Totzek gasifier... 

Lupus erythematosis Lupusvulgaris Lurgi Arosolvan process Lurgi Distapex process Lurgi gasifier... 

Lurgi Spblgas process Lurgi-type gasifier Lustral Lustran... 

The first anhydride plant in actual operation using methyl acetate carbonylation was at Kingsport, Tennessee (41). A general description has been given (42) indicating that about 900 tons of coal are processed daily in Texaco gasifiers. Carbon monoxide is used to make 227,000 t/yr of anhydride from 177,000 t/yr of methyl acetate 166,000 t/yr of methanol is generated. Infrared spectroscopy has been used to foUow the apparent reaction mechanism (43). 

The gasification plant is equipped with two Texaco gasifiers, each capable of producing all of the synthesis gas required for operation of the complex. Eastman chose an entrained-bed gasification process for the Chemicals from Coal project because of three attractive features. The product gas composition using locally available coal is particularly suitable for production of the desired chemicals. Also, the process has excellent environmental performance and generates no Hquids or tars. EinaHy, the process can be operated at the elevated pressure required for the downstream chemical plants. 

The cmde product from the gasifier contains CO2 and H2S, which must be removed before the gas can be used to produce chemicals. The Rectisol process is used to remove these contaminants from the gas. This is accompHshed by scmbbing the product with cold methanol which dissolves the CO2 and H2S and lets the H2 and CO pass through the scmbber. The H2S is sent to a Claus sulfur plant where over 99.7% of the sulfur in the coal feed is recovered in the form of elemental sulfur. A portion of the clean H2 and CO are separated in a cryogenic distillation process. The main product from the cryogenic distillation is a purified CO stream for use in the acetic anhydride process. The remaining CO and hydrogen are used in the methanol plant. 

In 1984, the Ube Ammonia Industry Co. began operating the largest Texaco coal gasification complex to date. This faciUty is located in Ube City, Japan, and has a rated gasification capacity of 1500 t/day of coal, and production capacity of 1000 t/day of ammonia. The plant has successfully gasified coals from Canada, AustraUa, South Africa, and China. At the present time the plant uses a mixture of petroleum coke and coal (43). 

The Ube plant consists of four complete trains of Texaco quench-type gasifiers. During normal operation, three gasifiers are on line and one is on standby. Each gasifier consumes 500 t/day of coal to generate syngas for 350 t/day of ammonia. Up to the middle of 1990 the Ube plant gasified 2.2 million t of coal and petroleum coke. 

When completed in 1996, the Weihe plant will gasify 1500 t/day of coal to produce 300,000 t/yr of ammonia, which will be used to manufacture 520,000 t/yr of urea fertilizer. This project is the eighth Texaco oil or coal gasification plant Hcensed by Chinese industry. 

Steam also is blended with air in some gasification units to promote the overall process via the endothermic steam—carbon reaction to form carbon monoxide and hydrogen. This was common practice at the turn of the nineteenth century, when so-called producer gasifiers were employed to manufacture LHV gas from different types of biomass and wastes. The producer gas from biomass and wastes had heating values around 5.9 MJ /mr at... 

A survey of commercial thermal gasification in the United States shows that few gasifiers have been installed since 1984 (115). Most units in use are retrofitted to small boilers, dryers, and kilns. The majority of existing units operate at 0.14 to 1.0 t/h of wood wastes on updraft moving grates. The results of this survey are summarized in Table 36. Assuming all 35 of these units are operated continuously, extremely unlikely, the maximum amount of LHV gas that can be produced is about 0.003 to 0.006 EJ/yr (222—445 td /d). 

---