Hanam Canada Corporation

A coal or biomass based project costing about $10 million or less would provide net revenues before tax of $3.5 million per year and a return on investment of 15%. Production could be increased fivefold with relatively low additional investments.

Preliminary cash flow and return of investment summary 

It is anticipated that the ethanol produced will meet commercial quality standards shown.  It may be possible to sell a grade of ethanol for fuel use that retains some of the byproduct oxygen containing compounds in the product. For example, propanol and butanol are known to improve the performance of ethanol containing gasoline and are sometimes intentionally added. A distillation column and storage tanks would allow blending to the most desirable higher alcohol concentrations.  Ethanol used for gasoline currently limits the amounts of methanol and acetic acid in the product.  These would be removed to meet current specifications.

Ethanol specification

A 7 t/h coal gasification system is proposed to generate synthesis gas. Several types of coal gas generators are available. The type of coal gas generator shown in exhibit 3 would be about 8 feet in diameter by 40 feet high.  Pulverized coal and superheated steam pass through the tubes of an externally heated spiral heat exchanger. Syngas leaves from the top of the generator and is cooled and cleaned. Ash is removed from the bottom of the cleaning system. The approximate chemical reaction for syngas generation from coal with the gasifier is as follows: 

5C     +    5H₂O    =    CO₂    +    3CO   +    3H₂    +  CH₄

Ethanol synthesis system

A diagram of the ethanol process is provided.  The optimum synthesis gas composition and the effect of variations in syngas composition on the process should be calculated.  The copper-based catalyst used for methanol synthesis operates at 254 ^oC, 50 bar pressure, whereas the TKK ethanol catalyst system operates at a slightly higher temperature, 280 ^oC and a similar or lower pressure.

The recycle compressor capacity limits the ethanol production that can be achieved.  The 2 kg ETOH/d Japanese system used a reciprocating compressor with a capacity of 0.14 acfm at 294 to 735 psia. The methanol plant has a reciprocating recycle compressor with a capacity of 111 acfm at 740 psia. The lab process was operated only with pure hydrogen and carbon monoxide, generally in the volume ratio 2.5/1 but also at a ratio of 1.4/1. 

The reactor for the 2 kg EtOH/d system was 38.4 mm dia X 2600 mm long 316L SS. The depth of catalyst was 370- 1940 mm and the reactor temperature 280 ^oC. The methanol reactor is 914mm dia X 13,400 mm long.  The lab reactor was heated with a hot oil heater.  The methanol system is heated with steam only on start-up. Steam is generated to control the exothermic reactions. About 4 to 11% of the carbon monoxide was converted to ethanol per pass over the catalyst.  Therefore the recirculation rate was much higher than the feed gas rate.  Gas from the converter was cooled to 5 to 10 ^oC then product was condensed and separated.  About 0.14 to 0.28 kg of 10 to 24 mesh granular silica catalyst are packed in the converter tube.  Two separate catalysts are used: a synthesis catalyst and a hydrogenation catalyst.  The composite catalyst system achieves up to 80% selectivity (the amount of ethanol produced compared with the maximum possible) for converting syngas to ethanol.  The synthesis catalyst produces acetaldehyde and acetic acid that are hydrogenated to ethanol by the reduction catalyst.  The two catalysts were kept separate in similar tubular reactors. The life of the catalyst system is expected to be about one year.

Ethanol Process Flow Diagram