METHOD FOR PREPARING GAS TANKS TO REPAIRING AND(OR) TO TECHNICAL INSPECTION AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 2003 - IPC

FIELD: methods and equipment for preparing to repairing and(or) technical inspection tanks for transporting liquefied oil gases (butane, propane and others), possibly exploitation of tanks designed for transporting and(or) storing other hydrocarbon products at condition when hazard concentration of gases may be generated in tanks. SUBSTANCE: method comprises steps of discharging remained liquefied gases from tank into system for compressing and cooling gas due to feeding inert gas to tank and periodically monitoring concentration of hydrocarbons and oxygen; supplying liquid solution for degassing and partialy diluting pyrophore depositions on inner walls of tank; then removing contaminated dissolver and separating it by liquid, solid and gaseous phases; returning regenerated dissolver for reusing it; final washing of inner surface with heated aqueous solution; removing and regenerating contaminated solution and ventilating tank. Kerosene is used as liquid dissolver. Processes of degassing and diluting are realized by two stages. At first stage kerosene is fed to tank through bubbler inserted into stationary cover of hatch. Second stage is realized after changing stationary cover by mounting cover at spraying kerosene by means of washing heads mounted in attachment secured to mounting cover. Final washing is realized at using aqueous solution of technological washing agent. Apparatus for performing the method includes system for supplying inert gas to tank; gas collector for accumulating and transporting liquefied gases for combustion in torch or to cooling station; vessels for dissolver and washing solution; systems for feeding agents for treating inner surface of tank and for removing contaminated products of degassing and washing provided with respective pipelines, pumps and locking fittings; unit for separating contaminated products; traps of slime after degassing and washing; and heat exchanger heating washing solution. Apparatus is provided with bubbler inserted to stationary cover of tank hatch; mounting cover supporting attachment for placing washing heads; heat exchangers for heating contaminated and cooling clean dissolver mounted in respective lines for feeding it to tank and removing it from tank. Desorber is used as unit for separating phases of contaminated products of degassing. Settling separator is used for separating washed products. Gas branch pipes of both apparatuses are joined with gas collector. One inlet branch pipe of separator is connected with inlet of vessel for washing solution through hydraulic seal. EFFECT: elimination of manual operations at removing pyrophore depositions, lowered consumption of energy and heat resources, significantly shortened time period for performing such operations. 6 cl, 2 dwg