Pressurized closed flow cleaning system

A method for cleaning equipment having hydrocarbon and solid contaminants on an interior surface, comprising the steps of connecting a supply conduit between a pressure vessel and equipment to be cleaned and connecting a return conduit between said equipment and said pressure vessel, said pressure vessel, said supply conduit, said equipment and said return conduit comprising a closed flow system;

• introducing an aqueous cleaning solution for solubilizing the hydrocarbon contaminants in said pressure vessel to partially fill said pressure vessel and provide a headspace above a level of said cleaning solution in said vessel;
• heating said cleaning solution;
• circulating cleaning solution which has been heated through said closed flow system and bringing said cleaning solution into contact with said hydrocarbon and solid contaminants in said equipment to thereby remove the hydrocarbon and solid contaminants;
• maintaining a pressure in said closed flow system at a value above atmospheric pressure;
• introducing an inert gas into the cleaning solution in said pressure vessel to strip hydrocarbon gas contaminants from said solution and pass said gas contaminants to said headspace;
• venting the hydrocarbon gas contaminants from the headspace;
• and conducting the gas contaminants to a disposal site.

A method for cleaning equipment having hydrocarbon contaminants on an interior surface, comprising the steps of introducing an aqueous cleaning solution for solubilizing hydrocarbon contaminants into a pressure vessel to partially fill said pressure vessel and provide a headspace above a level of said cleaning solution in said vessel;

• heating said cleaning solution in the vessel to a temperature above a boiling point of water;
• flowing the cleaning solution serially through a group of process vessels containing solid and hydrocarbon contaminants to thereby remove said hydrocarbon and solid contaminants from said process vessels;
• returning the cleaning solution to said pressure vessel;
• and periodically reversing a flow of said cleaning solution through said process vessels.