Patent EA-004521-B1 (EA)
Title: Method and apparatus for the on-site generation of a gas
Inventor: KOHLER JOHN
IPC: C25B15/08
Filed: 2001-02-21
Abstract: 1. A method for the on-site generation of a gas comprising the steps of: a) forming a dissociatable electrolyte solution which, in use, dissociates into positively charged and negatively charged ions at least one of which is an ion of a gaseous element; b) heating the electrolyte solution upstream of at least one electrolytic cell and thereby causing it to circulate and re-circulate through conduits and through the or each electrolytic cell by means of a thermosyphon effect; 2. A method for the on-site generation of a gas as claimed in claim 1 in which circulation of the electrolyte solution is facilitated by entraining gas bubbles produced in the or each electrolysis cell in dissolving tubes mounted substantially horizontally leading from the or each electrolysis cell to the or each gas separator substantially vertically thereby providing a gas lift effect. 3. A method for the on-site generation of a gas as claimed in claim 1 in which the electrolyte concentration in the solution is strengthened, if necessary, and any make up water is saturated by passing the electrolyte and make up water through an electrolyte salt dissolving tube . 4. A method for the on-site generation of a gas as claimed in claim 1in which the electrolyte solution is a metal halide and gas generated at the anolyte side of the electrolysis cell is a halogen. 5. A method for the on-site generation of a gas as claimed in claim 4 in which the metal halide salt is sodium chloride and the and gas generated at the anolyte side of the electrolysis cell is chlorine. 6. A method for the on-site generation of a gas as claimed in claim 5 in which hydrogen gas and sodium hydroxide or potassium hydroxide to be generated at the catholyte side of the electrolysis cell. 7. A method for the on-site generation of a gas as claimed in claim 6 to 13 in which sodium hypochlorite or potassium hypochlorite is also produced by mixing chlorine and sodium hydroxide, or chlorine and potassium hydroxide. 8. An apparatus for the on-site generation of a gas comprising at least one electrolytic cell having an anolyte section and a catholyte section, at least one section being connected, by fluid conduits, to a fluid heater which, in use, heats an electrolyte solution prior to its ingress into said section and facilitates circulation of the electrolyte solution through the apparatus by means of a thermosyphon effect, the electrolytic solution being dissociatable into positively charged and negatively charged ions at least one of which is an ion of a gaseous element, the heating element in turn being connectable by fluid conduits to an electrolyte replenishment means, at least one gas separator which, in use, separates gas produced in the electrolytic cell from electrolyte solution, the apparatus lacking a reservoir for the storage of electrolyte solution. 9. An apparatus for the on-site generation of a gas as claimed in claim 8 in which the or each gas separator is positioned operatively above the or each electrolysis cell and in which conduits linking the or each electrolysis cell is orientated operatively substantially vertically thereby facilitating circulation of the electrolytic solution by means of a gas lift effect. 10. An apparatus for the on-site generation of a gas as claimed in claim 9 in which the replenishment means is a substantially horizontally orientated electrolyte salt dissolving tube through which electrolyte solution from the or each gas separator flows prior to flowing through the heating element. 11. An apparatus for the on-site generation of a gas as claimed in claim 8 in which the salt dissolving tube is connected to an electrolyte salt replenishment hopper which contains a desired salt, and is also connected to a salt separator, which is connected to the heating element, the salt separator removing micro particulate salt from the electrolyte prior to its introduction into the heating element. 12. An apparatus for the on-site generation of a gas as claimed in claim 11 in which the electrolyte is a metal halide solution, the gas generated at the anolyte side of the electrolysis cell to be a halogen and hydrogen gas and a metal halide hydroxide are generated at the catholyte side of the electrolysis cell. 13. An apparatus for the on-site generation of a gas as claimed in claim 12 in which the metal halide is sodium chloride, the gas generated at the anolyte side of the electrolysis cell is chlorine and hydrogen gas and sodium hydroxide are generated at the catholyte side of the electrolysis cell. 14. An apparatus for the on-site generation of a gas as claimed in claim 8 in which the anolyte and catholyte sections of the or each electrolytic cell are separated from one another by an ion selective membrane made of perfluoropolymer which allows the passage of sodium or potassium ions therethrough but which is impermeable to halogen, hydrogen gas and hydroxyl.