Time related temperature field over a reactor internal surface

Abstract

In the synfuels production business, reactors that are subjected to thermal and mechanical loads are used. These reactors are continously cooled by means of internal water jackets. The jackets have been subjected to structural failures resulting from thermal fatigue. It was important to map the time dependent temperature field in reality. A comprehensive test programme has been conducted on an operating reactor for a period of 10 months. A network of 120 thermocouples, were installed in the jacket in order to map the temperature field over the jacket, having a developed area of about 12 m × 6,4 m and link it with the associated reaction process. In addition a finer grid consisting of 46 inner surface thermocouples, were used in the test. The results obtained were somewhat surprising: The measured temperature field, over the inner surface of the jacket is essential asymmetric. Looking at the vertical distribution of individual generators of the cylindrical jacket, it seems that two generators indicated higher temperatures than the average. In general, hotsports are generated at these generators lower part and gradually move toward the top of the reactor. The appearance and disappearance of hot spots seem to be random for 1 to 5 minutes all over the inner surface of the jacket. They have higher frequency adjacent to the hotter generators. Cold spots having temperatures around 230 °C, which is the temperature of the cooling water are more numerous, over larger areas and have a duration of about 15 to 30 minutes. The results indicated that there are not “hot bands” in the jacket, as opposed to what was assumed before the test. The time dependent temperature field was processed and presented on a computer screen.