Design development and industrial testing grate of sinter machines of SP-5 PJSC “MMK”

Abstract

Review of research works on improving the design of the grate bars of sinter machines of SP in the CIS has been made. It is shown that the grate of the AF-5 sinter machines does not comply with the technological and design requirements, which leads to its intense thermal and abrasive wear, deformation, falling out of the sinter carts and increased consumption of grates, as well as thermal protection overlays of the grate beams under them. On the one hand, a bed of sinter with a rational fractional composition (10‒20 mm) and a height (50 mm) of AF-5 sinter machines are shown to have a positive effect on the work of the grate, and on the opposite side, rippers of the mix bed of the loading unit and frequent short-term stops of the sinter-machines. An experimental design of a massive rationally shaped grate was developed and successfully tested on three pallets during the year. Deformation, “herringbone” and loss of grate, as well as thermal insulation pads under them were absent. Despite the fact that modern sinter machines are equipped with clamping devices of pallets, the influence of gaps between them on the speed of movement of the high temperature front in the bed has been revealed. The accelerated abrasive and thermal wear of the upper hooks of the grate located on the extreme under-grate beams has been established. The negative effect of the blades of the mix ripper and the areas of the bed below them, in which the sintering process is completed earlier than in the adjacent areas of the bed, is revealed. As a result, the residence time of the grates in high-temperature zones increases, and its thermal and abrasive wear increases. In the process of testing, it was revealed also the need to reduce the length of the cheeks of the upper hooks of the grate bars to increase the free section of the grate from 7.8 to 13.0%, which will reduce its gas-dynamic resistance. The final version provides for a decrease in the height of the grates from 60 to 50 mm and, accordingly, its weight ‒ from 10.2 to 8.7 kg, taking into account the gradual, rather than simultaneous replacement of existing grates with massive ones, and sufficient height for them a protective layer equal to 30 mm instead of 50 mm for the existing ones. Reducing the height of the protective layer from 50 to 30 mm will increase the output of sinter by 20 t/h. According to the results of the experiments, the specific consumption of massive grates is predicted to be 30 g/t of sinter at the current consumption of 67 g/t. The commercial supply of sintering pallets with new grate bars and the replacement of existing ones have begun.