Nonoxidizing heating of chip‑powder dispersions of ferrous metals in hydrocarbon atmosphere

The process of inorganic and organic components temperature transformation of metal waste into solid and gaseous products in a continuous hot briquetting muffle furnace has been studied. The composition of the hydrocarbon atmosphere formed in the muffle under conditions of limited access to the oxidizer has been determined. It is shown that the thermal destruction of the coolant oil phase proceeds according to a complex mechanism of consecutive reactions, including polycondensation, polymerization, and deep compaction with a constant decrease in the hydrogen content and ends with the formation of a coke‑like carbon residue on the surface of metal particles and an air suspension of finely dispersed carbon particles (smoke). When it is heated to hot briquetting temperatures of 750–850 °C, chemically active dispersions of ferrous metals are protected from oxidation first by a hydrocarbon gas with a density of 9.0–13.5 kg/m3, then by a pyrocarbon coating with a thickness of 0.1–0.3 mm up to the completion of the processes of pressing and cooling the briquette.

INVESTIGATION OF THE PROCESS OF OBTAINING PYROCARBON IN AN ELECTROTHERMAL FLUIDIZED BED

Carbon materials with a wide range of performance properties are used in various science, technology, and industry fields. For example, Pyrocarbon has the prospect of being used in nuclear power engineering, special metallurgy, aerospace technologies, heat exchange equipment, medicine, mechanical engineering, reactor building and other industries. The research described in the article aims to study the process of obtaining pyrocarbon in an electrothermal fluidized bed. The research is based on experimental methods of studying the process of obtaining pyrolytic carbon. Pyrocarbon is precipitated during pyrolysis (thermal destruction) of hydrocarbons in an electrothermal fluidized bed reactor. Natural gas was used as a fluidizing agent, and crushed fine electrode graphite of the GE model was used as a fluidized bed. When producing batches of pyrocarbon material, taking into account that the particle size will increase, these particles were crushed and subsequently used as a fluidized bed, thereby replacing graphite with pyrocarbon. As a result of the experimental studies carried out in the reactor with the electrothermal fluidized bed reactor, the batches of pyrocarbon material that were produced based on artificial graphite were produced. Studies using electron microscopy showed a change in the color and structure of the pyrocarbon coating depending on the processing cycle in the electrothermal fluidized bed reactor at temperatures of 900–1200 °C. Diffractometric analysis showed that pyrocarbon was identified in the treated material. Therefore, the adequacy of the method for calculating the heat balance has been confirmed. Bibl. 36, Fig. 7, Table 1.

RESEARCH OF THE PROCESS OF IMMOBILIZATION OF ASH REMNANTS OF ENERGY OBJECTS IN AN ELECTROTHERMAL

The Gas Institute of the National Academy of Sciences of Ukraine together with the Institute for Safety Problems of NPPs of the National Academy of Sciences of Ukraine, the NSC «Kharkiv Physical-Technical Institute» and the Institute of Nuclear Research of the National Academy of Sciences of Ukraine are realization work on the development of technology for the immobilization of radioactive materials generated during operation and accidents on energy objects. As a model of radioactive ash, the authors used ash remnants of coal-fired power plants that potentially representsources of ionizing radiation. As a result of a series of experiments in a specially created laboratory plant with an electrothermal fluidized layer it was possible to apply a pyrocarbon coating to this type of ash. After coating the particles of ash with pyrocarbon, ionizing b-radiation decreased by about 30–35 %, a-activity decreased by 28 %. The thermal efficiency of the methane pyrolysis process at this plant is on average 8–12 %. The conducted researches point to the prospect of immobilization of saline remnants of atomic and thermal energy by encapsulating pyrocarbon in an electrothermal fluidized bed. Ref. 9, Fig. 4, Tab. 1.