Methanol, production coal gasification

Figure 6. Synthesis gas production for methanol via coal gasification...

In Table 1 som system characteristics essential for understanding vhere risks can be generated in three alcohol-producing systems are compared with each other. Methanol production via gasification of coal has been included to show the difference between a fossil and biomass resource. Methanol production leads to whole-resource utilization something which today is not possible with existing techniques for ethanol production from cellulose-containing plants. Ihe waste streams from ethanol production... 

Produced from Co l. Estimates of the cost of producing methanol from coal have been made by the U.S. Department of Energy (DOE) (12,17) and they are more uncertain than those using natural gas. Experience in coal-to-methanol faciUties of the type and size that would offer the most competitive product is limited. The projected costs of coal-derived methanol are considerably higher than those of methanol produced from natural gas. The cost of the production faciUty accounts for most of the increase (11). Coal-derived methanol is not expected to compete with gasoline unless oil prices exceed 0.31/L ( 50/bbl). Successful development of lower cost entrained gasification technologies could reduce the cost so as to make coal-derived methanol competitive at oil prices as low as 0.25/L ( 40/bbl) (17) (see Coal conversion processes). 

Methanol, a clean burning fuel relative to conventional industrial fuels other than natural gas, can be used advantageously in stationary turbines and boilers because of its low flame luminosity and combustion temperature. Low NO emissions and virtually no sulfur or particulate emissions have been observed (83). Methanol is also considered for dual fuel (methanol plus oil or natural gas) combustion power boilers (84) as well as to fuel gas turbines in combined methanol / electric power production plants using coal gasification (85) (see Power generation). 

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). 

Hydrocarbons from Synthesis Gas and Methanol. Two very important catalytic processes in which hydrocarbons are formed from synthesis gas are the Sasol Eischer-Tropsch process, in which carbon monoxide and hydrogen obtained from coal gasification are converted to gasoline and other products over an iron catalyst, and the Mobil MTG process, which converts methanol to gasoline range hydrocarbons using ZSM-5-type 2eohte catalysts. 

Whereas near-term appHcation of coal gasification is expected to be in the production of electricity through combined cycle power generation systems, longer term appHcations show considerable potential for producing chemicals from coal using syngas chemistry (45). Products could include ammonia, methanol, synthetic natural gas, and conventional transportation fuels. 

We will consider three processes in more detail to show how the sulfur in the original feedstock material (coal or oil shale) is recovered as elemental by-product sulfur. In this way yields of sulfur per barrel of product can be computed. The three processes will illustrate examples of coal gasification for production of SNG, methanol or indirect liquids, direct liquefaction for production of naphtha and synthetic crude oil and finally, oil shale retorting for production of hydrotreated shale oil. 

Staege H. The production of methanol and hydrogen by Kopper-Totzek coal gasification process. Erdol-Erdgas-Zeitschrift, 92 381-387, 1976. 

Methanol, also called methyl alcohol and once commonly know as wood alcohol, is a clear, volatile liquid mp, -98°C bp, 65°C). Until the early 1900s, the major commercial source of methanol was the destructive distillation (pyrolysis) of wood, a process that yields a product contaminated with allyl alcohol, acetone, and acetic acid. Now methanol is synthesized by the following reaction of hydrogen gas and carbon monoxide, both readily obtained from natural gas or coal gasification ... 

Thus a variety of hydrocarbons, ranging from natural gas to coal, are used in methanol production. Regardless of the feedstock used to prepare the synthesis gas, it is necessary to remove sulfur so that the converter catalyst is not poisoned. Before natural gas or naphtha is reformed, the feedstock is desulfurized. In the partial oxidation and coal gasification processes, the feedstock is first oxidized and the resulting synthesis gas is desulfurized before entering the converter. 

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. 

Winkler process, the Koppers-Totzek process, and the Texaco process. Downstream adjustment and treatment of the raw product gases is required when these processes are used to supply feedstock or cofeedstock to a typical low-pressure methanol process operating at 220 to 270°C and 5.066 to 10.132 MPa (50 to 100 atm). A few of the operating details of these and other commercial coal gasification processes are presented here. 

In this paper, we have studied the solar methanol production by a solar-assisted coal gasification system, which will be able to start-up GCRED-system, from a point of fossil/solar energy hybridization using solar thermochemical process (STC). 

SOLAR-ASSISTED COAL GASIFICATION FOR SOLAR METHANOL PRODUCTION AND COST ANALYSIS TO START-UP GCRED-SYSTEM... 

We have made cost analysis for the solar methanol production for the system of Fig. 1. In this analysis, SCOT-solar farm (Solar Concentration Off-Tower central receiver beam-down configuration) is used for solar concentrating system(Fig.2). This solar concentrating system has an economical advantage, since the heavy chemical plant can be installed on the ground. Since the high temperature of 1000-1200°C is obtained by the SCOT-solar farm, chemical plant (or reactor) for solar-assisted coal gasification can be operated. Table 1 shows estimated investment cost... 

The estimated cost was 0.6-0.8 /gallon methanol. This figure shows that the solar methanol produced by the solar-assisted gasification is equal to that by the conventional process. Also, this is competitive to the gasoline (1.0-1.2 /gallon). These results show that the solar methanol production by the solar-assisted coal gasificahon with SCOT-solar farm can be operated in the commercial base. The cost of the solar methanol produced from H2 by PV is estimated to be 8-10 times higher than that by the conventional process[13]. 

The following equations represent the possible reactions in different processing steps involving four representative fuels natural gas (CH4) and liquefied propane gas (LPG) for stationary applications, liquid hydrocarbon fuels (CmHn) and methanol (MeOH) and other alcohols for mobile applications, and coal gasification for large-scale industrial applications for syngas and hydrogen production. Most reactions (Eqs. 1.1-1.14 and 1.19-1.21) require (or can be promoted by) specific catalysts and process conditions. Some reactions (Eqs. 1.15-1.18 and 1.22) are undesirable but may occur under certain conditions. 

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