Coal to Methanol

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). 

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... 

The indirect liquefaction processes include Fischer-Tropsch and coal to methanol. Both processes have operated on a commercial scale. For the past 25 years, a Fischer-Tropsch facility has operated in South Africa. Presently the South Africans are constructing an advanced and larger facility. Coal-to-methanol plants existed in the United States, but were replaced by natural gas-to-methanol facilities because it was more economical to do so. 

It is also produced with a different labor force, different automation and construction philosophy and with a different product mix. Likewise, coal to methanol plants that were built in the U.S. in the past did not have to contend with the environmental and institutional constraints that exist in the U.S. today. 

PANELIST PASSMAN As I indicated, we are paying attention now to Fischer-Tropsch and coal-to-methanol processes with particular attention toward their transportation potential, and there are other potentials as well. If you are talking about an R D program and ET, most of the money is toward the direct processes. 

The opening of trade with China has resulted in several chemical company expansions in that country and nearby countries. In 2005, the two national chemical giants, Dow Chemical Company and Dupont Company have large-scale plans for investment in China. Dow is planning a large coal-to-methanol-to-olefins complex that includes chlor-alkali facilities that will take five to ten years for completion. Dupont has recently doubled its investment in China and plans to spend another 600 million BY 2010, a portion of which may go to build a titanium dioxide plant. Dupont employs about 5000 people on Mainland China and recently built a Research... 

CTM. See coal, -to-methanol CWS. See coal, -water slurry cycle... 

LPG. See gas, liquified petroleum LPIE. See ion exchange, liquid-phase LPM. See methanol, low-pressure LPMEOH. See coal, -to-methanol, liquid-phase methanol LPST. See turbine, low-pressure steam LPT. See turbine, low-pressure LTFT. See Fischer-Tropsch (FT) synthesis, low-temperature... 

A C02-neutral solution is obtained if the CO2 released during combustion of the methanol is recovered from the ambient during the methanol production step. A C02-free coal-to-methanol production is given by taking H2 as a supplemental feed and a non-fossil source of high temperature heat (e.g., nuclear). 

FIGURE 8a Plan view of 1750 mt/d methanol plantship [BARD11982. Coal-to-methanol study using OTEC technology. For Johns Hopkins University Applied Physics Laboratory. Brown and Root Development, Inc., Houston, Texas.)... 

The hydrogen purity can be considerably increased if the user is satisfied with a hydrogen yield lower than that in the above example. Reducing the pressure on the permeate gas side may lead to higher hydrogen yields or hydrogen purities. It is well conceivable that this process, which was introduced by the chemical industry only a few years ago, still offers a considerable development potential and that it may be worth considering its use also at other points of the coal-to-methanol process chain. 

Almost without exception, the raw gases produced from coal contain more carbon monoxide than required for methanol production. This is why most coal-to-methanol plants include facilities to shift some of the carbon monoxide contained in the raw gas. 

A system particularly suited K> provide both steam and power to a coal-to-methanol complex is the Circulating Fluid Bed Combustion Process together with conventional heat recovery and power generating systems. This technology, developed by LURGI in the seventies, combines high efficiency with low SO2 and NOx emissions. More than 90% of the sulphur contained in the coal is captured in die combustion zone already, and due to low combustion temperature, less than 200 mg of nitrous oxides per m of flue gas can be analysed. Coal burnout is between 98 and 99%, depending on the fuel. 

Although modem plants are designed to export as little waste water as possible and attempts are made on the premises to recondition the waste water for cooling or boiler feed water service, almost all coal-to-methanol plants still have a considerable demand for raw water. Main consumers are cooling and boiler feed water supply systems, whereas other services such as potable water and water for general operating purposes account for only a small portion of the demand. 

Fig.7J. Bloc diagram of a coal to methanol plus SNG plant...

One of the many possible routes from coal to methanol is illustrated by a process flow diagram, and a material and energy balance is compiled for this typical example. 

Coal-to-Methanol, An Engineering Evaluation of Texaco Gasification and ICI Methanol-Synthesis Route. Palo Alto, California Electric Power Research Institute, August 1981. AP-1962. 

CTM [Coal To Methanol] A general name for processes that convert coal to methanol. 

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