Coal process development unit

Figure 1. Simplified diagram of coal process development unit...

Review of coal Hquefaction research may be found ia References 1—3. Hereia, those processiag schemes for coal Hquefactioa that, siace the 1970s, have received atteatioa beyoad the laboratory to pilot plants or process development units are presented. 

Fault Tree Analysis Report for CoaF Coal Gasitication Failure rales (per year basts) for over 400 events Coal-gasification Process Development unit 50. 

DATA BOUNDARY Coal-gasification Process Development unit systems and... 

In this study detailed fault trees with probability and failure rate calculations were generated for the events (1) Fatality due to Explosion, Fire, Toxic Release or Asphyxiation at the Process Development Unit (PDU) Coal Gasification Process and (2) Loss of Availability of the PDU. The fault trees for the PDU were synthesized by Design Sciences, Inc., and then subjected to multiple reviews by Combustion Engineering. The steps involved in hazard identification and evaluation, fault tree generation, probability assessment, and design alteration are presented in the main body of this report. The fault trees, cut sets, failure rate data and unavailability calculations are included as attachments to this report. Although both safety and reliability trees have been constructed for the PDU, the verification and analysis of these trees were not completed as a result of the curtailment of the demonstration plant project. Certain items not completed for the PDU risk and reliability assessment are listed. 

In thermal processes the formation of asphaltols always precedes other reactions such as major heteroatom rejection and distillate formation. In fact, in the SRC process bituminous coals are actually dissolved by the time the coal slurry exits the preheater (4,11). This has recently been demonstrated at the SRC process development unit (PDU) in Wilsonville, Alabama (11) (see Figure 2). 

The continuing search for technical and economic improvements in the coal gasification areas has provided incentives to develop newer process concepts starting in 1979. The Joint Program for 1979 includes processes in the Process Development Unit (PDU) stage of development which promise technical and/or economic improvements. Gasification processes included in the 1979 program are ... 

Catalysts currently employed in process development units for coal liquefaction are hydroprocessing catalysts developed for petroleum refining (5l6). They are composed of combinations of Mo or W with Co, Ni or other promoters dispersed on alumina or silica-alumina supports. When used in liquefaction, these catalysts deactivate rapidly f6-9i causing decreases in product yield and quality and problems with process operability. Thus the... 

The chars were produced in a process development unit scale fluidized-bed flash pyrolyser (90 from pulverized Mlllmerran and Wandoan subbituminous coals from Queensland, Australia. Mlllmerran coal was pyrolyzed at various temperatures between 500 and 800 C and Wandoan coal at 550°C. The resulting chars were screened to yield a size fraction with a median mass size around 80 pm. Hie properties of the chars are presented in Table I. 

Mann R.M., Harris G.E., Menzies W.R., Simonson A.V. and Williams W.A. Environmental, health and safety data base for the KRW coal gasification process development unit. Report GRI-85/0123, Gas Research Institute, Chicago IL (1985). 

Ireland Mine hvAb coal was used in the coal pyrolysis studies. The method of heat treatment was essentially that reported by Petrakis and Grandy (8), Ireland Mine coal was also the feed coal used to obtain most of the coal liquefaction products. The coal-derived liquids investigated were centrifuged liquid products (CLP) and their subfractions from selected runs in the Pittsburgh Energy Technology Center s 400-lb coal/day coal liquefaction process development unit (PDU) (9). 

This molten salt gasification process is the basis for the Rockwell International molten salt coal gasification process. A 900-kg-h l (1 ton/h) process development unit pilot plant has been built and is being tested under contract from the Department of Energy. This plant includes the gasifier and a complete sodium carbonate recovery and regeneration system. 

Atmospheric Pressure, Entrained Flow Coal Gasification Process Development Unit Program." Palo Alto, California Electric Power Research Institute, February 1983. AP-2846. 

Shale Oil. In the United States, shale oil, or oil derivable from oil shale, represents the largest potential source of Hquid hydrocarbons that can be readily processed to fuel Hquids similar to those derived from natural petroleum. Some countries produce Hquid fuels from oil shale. There is no such industry in the United States although more than 50 companies were producing oil from coal and shale in the United States in 1860 (152,153), and after the oil embargo of 1973 several companies reactivated shale-oil process development programs (154,155). Petroleum supply and price stabiHty has since severely curtailed shale oil development. In addition, complex environmental issues (156) further prohibit demonstration of commercial designs. 

After 1973 the United States invested heavily in synthetic fuel research and development, hoping synthetics could sciwc as economical substitutes for crude oil. However, coal conversion is not profitable unless the price of crude oil is over 50 per barrel, which is why the processes developed were mothballed when world crude oil prices fell in the 1980s. 

Development of the LPM process is included within the American Gas Association-United States Office of Coal Research joint program on producing substitute natural gas (SNG) from coal. The development program consists of three phases which are proceeding in an overlapping manner. These are reviewed in Table I. Completion of the program is scheduled for June 30, 1975. 

Materials of construction are becoming more critical with development of the newer processes and unit operations. Therefore, an expanded materials research program is essential to the successful development of a coal gasification industry. 

Processes and equipment for the gasification of inferior coke and chars from low-temperature carbonization of subbituminous and lignitic coals were developed in Germany (13), where the relatively large yield of low-temperature tar was welcomed as raw material for hydrogenation processes. The market for low-temperature tar in the United States has been too small and the selling price too low to encourage the use of low-temperature chars for gas production. 

---