Development of an advanced, continuous mild gasification process for the production of co-products

The principal finding of this study was the high capital cost and poor financial performance predicted for the size and configuration of the plant design presented. The XBi financial assessment gave a disappointingly low base-case discounted cash flow rate of return (DCFRR) of only 8.1% based on a unit capital cost of $900 per ton year (tpy) for their 129,000 tpy design. This plant cost is in reasonable agreement with the preliminary estimates developed by J.E. Sinor Associates for a 117,000 tpy plant based on the FMC process with similar auxiliaries (Sinor, 1989), for which a unit capital costs of$938 tpy was predicted for a design that included char beneficiation and coal liquids upgrading--or about $779 tpy without the liquid upgrading facilities. The XBi assessment points out that a unit plant cost of$900 tpy is about three times the cost for a conventional coke oven, and therefore, outside the competitive range for commercialization. Modifications to improve process economics could involve increasing plant size, expanding the product slate that XBi has restricted to form coke and electricity, and simplifying the plant flow sheet by eliminating marginally effective cleaning steps and changing other key design parameters. Improving the financial performance of the proposed formed coke design to the level of a 20% DCFRR based on increased plant size alone would require a twenty-fold increase to a coal input of 20,000 tpd and a coke production of about 2.6 minion tpy--a scaling exponent of 0.70 to correct plant cost in relation to plant size