Low Btu gasification

Ahner, D. J., May, T. S., and Sheldon, R. C., Low BTU Gasification Combined-Cycle Power Generation, Presented at Joint Power Generation Conference, Miami Beach, September 15-19, 1974. 

Low BTU gasification technology is commercially available for most types of biomass feedstocks and can be expected to have an impact on energy supplies by 1985. Many of these commercial processes are based on low BTU coal gasification technologies and the gas produced can best be used as fuel for supplying process heat, process steam or for electrical power generation. 

Coal gasification is being developed as an alternative method of energy production. Low Btu gasification of coal is being evaluated for use in combined-cycle electrical generation in which the low Btu coal gas is combusted in a gas turbine and... 

Natural gas requires no fuel treatment however, low-Btu gas, espeeially if derived from various coal gasification processes, requires various types of cleaners for use in a gas turbine. These cycles can get very complex as indicated by a typical system, which utilizes a steam bottoming cycle to achieve high efficiency. Vaporized fuel oil gas is already cleansed of its impurities in the vaporization process. 

Most biomass gasification systems utilize air or oxygen in partial oxidation or combustion processes. These processes suffer from low thermal efficiencies and low Btu gas because of the energy required to evaporate the moisture typically inherent in the biomass and the oxidation of a portion of the feedstock to produce this energy. 

A search of the recent literature indicates identifiable plans for 19 high Btu coal gasification, 10 medium and low Btu gas, and 15 liquefaction projects. These range from laboratory scale, through seeking funds for feasibility studies, to the construction of commercial scale demonstration plants. The implied coal input in Table V is based on extrapolations to commercial size of those projects which are sufficiently advanced to provide data on input and/or output, site, and time frame. Other projects may be included later but they could not make a contribution before the mid-1990 s. 

While on the subject of coal gasification, we should remember that low- and medium-Btu gas from coal should be considered as lower cost alternatives to pipeline quality high-Btu gas. For one thing, the capital investment for low-Btu gas plants is lower than the high-Btu gas plants as shown below ... 

As a result of this sudden about-face by the Carter Administration and their new found religion in switching to natural gas, it shouldn t surprise anyone to find there will be little incentive for anyone to keep working very hard on coal gasification whether it be for low-Btu, high-Btu or medium-Btu gas or any combination of them. 

Major Technical Issues Facing Low and Medium Btu Gasification... 

In the area of Low-Btu Coal Gasification, the technology to produce environmentally acceptable (150-200 Btu/SCF) gas from coal is available. In fact, one can select from at least eight... 

In particular, the subject today is the barriers to commercialization of coal gasification. There will be a couple of points where it will apply to liquefaction, but the concentration will be on gasification. I will talk mostly about high Btu coal gasification (i.e., pipeline gasification) as compared with industrial gasification (i.e., low/medium Btu gasification). 

The flexicoking process is an adaptation of the fluid coking process that uses the same reactor as a fluid coker but has an integrated gasification unit available for coke gasification to produce, in addition to the typical fluid coking slate of products, a low-BTU gas. 

In a solid waste gasification system for a small community, the low-BTU gas could be burned in a dual-fueled engine-generator. Two modes of operation are possible ... 

A) Gasification Apparatus. The above defined generating sets are generally fed with low BTU gas by a down draft gasifier with a fixed carbonization bed. 

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