Patent ID: 8257508

Claim:
A method of removing buildup in a heat exchanger, the method comprising: a. closing a first inlet valve of pumping vessel, wherein the first inlet valve controls a supply of a solvent into the pumping vessel, wherein the pumping vessel is a positive displacement pumping vessel, wherein the solvent is liquid petroleum gas; b. closing a first exit valve of the pumping vessel, wherein the first exit valve controls a supply of a solvent exiting the pumping vessel; c. closing a second inlet valve of the pumping vessel, wherein the second inlet valve controls a supply of a method gas into the pumping vessel, wherein the method gas is capable of existing with the solvent without negatively impacting the integrity of the solvent, wherein the method gas is a high pressure method gas; d. continuously opening and closing a second exit valve to maintain pressure within the pumping vessel, wherein the second exit valve controls a supply of the method gas exiting the pumping vessel; e. opening the first inlet valve to introduce the solvent into the pumping vessel, wherein the pumping vessel includes a pumping vessel housing forming a pumping vessel chamber and a moveable float located within the pumping vessel chamber, wherein the moveable float is attached to the pumping vessel chamber by a mechanical linkage; f. engaging the moveable float by continuously introducing solvent into the pumping vessel chamber until the solvent reaches a predetermined level, wherein upon reaching the predetermined level the mechanical linkage of the moveable float engages to close the first inlet valve, to close the second exit valve, and to open the second inlet valve; g. opening the first exit valve of the pumping vessel to discharge the solvent, wherein the discharged solvent is injected into the heat exchanger, wherein the solvent is injected into the heat exchanger at a variable rate; h. closing the first exit valve of the pumping vessel; and i. closing the second inlet valve of the pumping vessel.