Circulating-spheres reactor

Bockhom et al. [2, 3] proposed circulated-spheres reactor for the pyrolysis of waste plastics. This reactor enabled one to remove gaseous products from the reaction zone and to achieve high heat transfer rates, namely condition (2) described above. The concept of this circulated-spheres reactor has the possibility to attain conditions (1) and (3) by improving the reactor. 

A. Homung, H. Bockhom and U. Homung, A circulated-spheres reactor for the conversion of viscous media, Chem. Eng. TechnoL, 21, 723 (1998). 

Figure 11. Treatment of PET and PBT containing waste in a circulated-spheres reactor (reprinted from [41], with permission from Elsevier).

Fig. 8.13. Diagram of a set up for continuous sol-gel preparation of alumina spheres. (1) sol preparaton (2) dropping of sol into layer of petrol ether (3) gelation reactor filled with a NH4OH solution (4) circulation pump (5) supply vessel for the gelation fluid (6) particle separation ...

Flnidized-bed processes are either bnbbling or internally circulating. The fluidized-bed reactor is very versatile for the pyrolysis of polyolefins. Nevertheless one of the problems with fluidized-bed pyrolysis of post-consumer plastics relates to the stickiness of the sand particles (the fluidization medium) that becomes coated with fused plastic. In order to solve these problems, new reactors have been proposed, snch as the conical spouted bed, the conical rotary reactor, a sphere circnlation reactor and a reactor with mechanical particle stirring. 

The typical HTGR fuels are the pebble-bed type, which is a graphite sphere, and the block type fuel i.e., a graphite block into which coated particles are inserted (Saito et al. 1994). The former is generally suitable for high temperature operation because the fuel spheres circulate slowly in the reactor and each fuel sphere is exposed to high temperature in the reactor for... 

The HTGR technology line utilizes complete passive system for RHR and shutdown. Residual heat is taken away by radiator surrounding the reactor pressure vessel utilizing namral circulation. Shutdown is accomplished by simply dropping small absorber spheres by gravity force. 

A high degree of fuel utilization is met with the on-line refuelling system. The burn-up on each sphere is measured after passing through the core. Each element is then re-circulated until the bum-up is optimized. At this time, the fuel is passed to the spent fuel storage tanks and new fuel inserted in the reactor. 

The reactor fuel system. The reactor core consisted of a stainless steel sphere 18 in. in diameter, through which was circulated 100 to 120 gpm of 93% enriched uranyl sulfate dissolved in distilled water. The temperature... 

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