Texaco Process Gasification Plants

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 high cost of coal handling and preparation and treatment of effluents, compounded by continuing low prices for cmde oil and natural gas, has precluded significant exploitation of coal as a feedstock for methanol. A small amount of methanol is made from coal in South Africa for local strategic reasons. Tennessee Eastman operates a 195,000-t/yr methanol plant in Tennessee based on the Texaco coal gasification process to make the methyl acetate intermediate for acetic anhydride production (15). 

The total program is planned to provide sufficient information to confidently design large scale second generation coal gasification plants (100,000 Nm3/hr of synthesis gas) using the Texaco process. 

In 2000 Farmland Industries in Kansas started up a petroleum coke gasification plant to make ammonia. The plant uses Texaco s process to make 1000 tonnes per day of ammonia.185, 186 In 2004 Rentech purchased an 830-tonne-per-day ammonia plant in Illinois and plans to convert it from natural gas to coal feedstock. Startup of the conversion is expected in 20 07.300... 

Ube Industries commissioned a 1000 t/d ammonia plant in 1984 using Texaco s coal gasification process [1161], [1173]. An energy consumption of 44.3 GJ/t NH3 is stated, which is lower than the 48.5 GJ/t NH3 quoted for another Texaco coal gasification-based ammonia plant [544]. 

Ubes Texaco Process Coal Gasification Plant, Ube comp, brochure 1984. 

The current producers of partial oxidation processes are BASF, Texaco, Shell, and Hydrocarbon Research. A process block diagram showing the three process steps can be seen in Figure 2.18 [30]. The first step is the gasification process with the addition of oxygen and water. A detailed schematic of the Shell Gasification plant (SGP) is shown in Figure 2.19 [28]. The most important features of the process are the reactor, waste-heat-boiler, carbon catcher,... 

The catalyst is not sensitive to sulfur or other oxo poisons, which is another environmental advantage. Together with the simple but effective decantation, which allows the withdrawal of organic and other byproducts at the very moment of separation, accumulation of activity-decreasing poisons in the catalyst solution is prevented. Therefore no special treatment or purification step is necessary. This reduces the environmental burden still further. For a considerable time the oxo units at Ruhrchemie s plant site were even supplied with syngas derived from coal produced by the TCGP (Ruhrchemie/Ruhrkohle s version of the Texaco coal gasification process). In various cases this can be an important factor as far as local resoruces are concerned. 

Entrained coal gasifiers are typified by the Koppers-Totzek (KT) and Texaco processes. Most of the present coal-based ammonia plants (except in China) use the KT process. The process is essentially a partial oxidation process as are most coal gasification processes. At least two KT ammonia plants have been built to use either coal or heavy oil although only one (in Finland) is known to have used both feedstocks [48]. However, any entrained gasification units presumably could be readily adapted to heavy oil or lighter hydrocarbons including natural gas. 

The sequence of the remainii steps of synthesis gas preparation is CO shift conversion, removal of H2S and CO2 by Rectisol wash (cold methanol), and liquid nitrogen wash. As in other partial oxidation processes, the H2S is converted to elemental sulfur. Ube Industries, Japan, commissioned a 1,500-tpd ammonia plant in 1984 using the Texaco coal gasification process. An energy consumption of 10.9 Gcal/tonne of ammonia is stated this is lower than the normal quoted f ure of 11.6 Gcal/ tonne of NH3 for coal-based processes 131]. Another 1,000 tpd coal-based ammonia plant is scheduled for startup at Wehei, China, in 1996. 

As discussed in the Existing Commercial Projects portion of this section, several commercial projects use the Texaco coal gasification process. However, these plants are for chemical synthesis gas application and do not include IGCC power generation. In addition, most commercial Texaco projects do not use syngas coolers to generate steam from the hot raw coal gas. 

Pilot Plant Evaluation of Illinois No. 6 and Pittsburgh No. 8 Coal for the Texaco Coal Gasification Process. Palo Alto, California Electric Power Research Institute, January 1987. AP-5029. 

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