No abstract

No abstract

No abstract

Аннотация. В работе рассмотрен класс пространственноинвариантных нелинейных систем с распределенными параметрами. Известны обобщенные критерии анализа устойчивости таких систем. Однако, они применимы только для систем, структурная схема которых представима в виде последовательного соединения нелинейного элемента и линейной части системы. В данной работе с использованием пространственного фильтра, разработана методика применения обобщенных критериев на нелинейные системы, в которых не представляется возможным выделение нелинейности в виде отдельного звена.

One of the most difficult problems in the operation of electric-arc steel furnaces (EASF) with transformer powers of 400-500 kW/ton is the stability of the lining above the slag belt.In this connection, we have investigated the rate and character of the damage to various zones in the lining of the walls of high-power EASF brought into operation at the Donetsk Metallurgical Works.The DSP-100NZA furnace is fitted with a 50-MW transformer. In the period of open burning of the arc, the power fed to the furnace is limited by the stability of the lining and ranges from 28-31 to 7-12 MW. The asymmetry of the power generation between the phases is 20%.The thermal fluxes to the lining opposite the arc with maximum transformer power (Pa = 40 MW) reach 2000 kW/m 2. During open burning of the arc in these operating regimes, they do not exceed 700-800 kW/m 2.For lining the walls, use is mainly made of PSSh periclase--spinellide refractories.In a series of furnace campaigns, MKhVP and MPM (TU 14-200-278-78) refractories have been tried out at the overheating sites opposite the arc, but they did not give an appreciable improvement in stability.The wall refractory wear rate per melt, averaged over a campaign, ranged from 9.7 mm opposite the overloaded phase at the boundary between the vertical and conical parts of the wall to 3.2 mm under the roof of the furnace opposite the underloaded phase.In the first 18 months of operation of the furnace, the length of a campaign ranged from 62 to 121 melts, averaging 88 melts.However, the wall lining opposite the arc, especially opposite the arc of the overloaded phase, was repaired after 40-60 melts in most of the campaigns.To elucidate the character of the furnace wall wear, we made a petrographic investigation of refractories from several zones of masonry, and also made chemical analyses.Specimens of spent refractories were taken opposite the middle-power phase and between the phases from the fifth-sixth rows (from the top) of masonry, which were less subject t,o the influence of the slag and where together with high irradiation there is less effect from the dressing materials.