METHOD OF NEUTRALIZATION OF FUEL TANKS OF LIQUID-PROPELLANT ROCKETS AFTER DRAINING AGGRESSIVE AND TOXIC FUEL COMPONENTS Russian patent published in 2020 - IPC B08B3/08 

FIELD: machine building.

SUBSTANCE: invention relates to machine building, particularly, to cleaning methods, neutralization of inner surfaces of fuel tanks of liquid-propellant rockets after draining aggressive and toxic components of liquid propellant rocket fuel (RFC). Method for neutralization of fuel tanks of liquid-propellant rockets after draining aggressive and toxic components of rocket fuel (RFC): an oxidizing agent – nitrogen tetroxide (N₂O₄) and combustible – asymmetric dimethylhydrazine (C₂H₈N₂) by method of removal of liquid non-drained residues, vapor phase and RFC phase adsorbed on inner surfaces of tanks. Removal of fuel remains is performed in two stages. At first step, residues of liquid and simultaneously vapor phase of fuel components are removed by evaporation at temperature of 35–50.0 °C and simultaneous removal of vapors pumping to residual content thereof in tanks volumes, equilibrium with phase adsorbed liquids on their inner surfaces: for N₂O₄ – C^a_ads=70.0–80.0 mg/m³, for C₂H₈N₂ – C^g_ads=6.0–9.0 mg/m³. At the second stage, the phase of RFC adsorbed on inner surfaces of tanks is removed by washing the solvent based on trans-1,2-dichloroethylene and methylene chloride at temperature of up to 50 °C with steam-condensate method to minimum residual content of fuel components vapor in tank volumes: for RFC N₂O₄ – C^a_add≤2.0 mg/m³, for RFC C₂H₈N₂ -C^g_add≤0.1 mg/m³. At the first stage of the process, pairs of fuel components removed from fuel tank volumes are recuperated and converted to liquid state by compression and cooling at pressure of not less than 2.0 MPa and temperature – minus (8.0–10.0)°C for vapors N₂O₄ and minus (50.0–55.0)°C for C₂H₈N₂ vapor.

EFFECT: broader technological capabilities of the process of cleaning and neutralizing fuel tanks after draining RFC by using alternative CFC-113 ozone-friendly solvents, with the condition of achieving high quality of cleaning surfaces and eliminating effects of corrosion damage of structural materials and contamination of internal surfaces of tanks.

1 cl, 1 dwg, 1 tbl