# US 2018/0320962 A1 · Argon condensation system and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0320962 A1 - Document ID: US20180320962A1 - Status: Published application - Kind: A1 - Application number: 16/032,243 - Filed: 2018-07-11 - Published: 2018-11-08 - Earliest claimed: 2014-07-02 - Assignees: Praxair Technology, Inc. - Inventors: Steven R. Falta; Brian S. Powell; Henry E. Howard; Vijayaraghavan S. Chakravarthy; Maulik R. Shelat - Web page: https://patentgrep.com/patent/US20180320962A1 ## CPC - F25J 3/04672: {having a top condenser} - F25J 3/0285: {of argon} - F25J 3/04412: {in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column} - F25J 3/04678: {cooled by oxygen enriched liquid from high pressure column bottoms} - F25J 3/04715: {The auxiliary column system simultaneously produces oxygen} - F25J 3/048: {Argon recovery} - F25J 3/04848: {Control strategy, e.g. advanced process control or dynamic modeling} - F25J 2250/02: Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger - F25J 2250/20: Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams - F25J: LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS {OR LIQUEFIED GASEOUS} MIXTURES BY PRESSURE AND COLD TREATMENT {OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)} ## Abstract An argon reflux condensation system and method in which a plurality of once-through heat exchangers are connected to an argon column of an air separation plant to condense argon-rich vapor streams for production of reflux to the argon column. Condensation of the argon-rich vapor streams is brought about through indirect heat exchange with crude liquid oxygen streams that partially vaporize and are introduced into a lower pressure column of the plant for further refinement. The flow rate of the crude liquid oxygen streams are sensed and controlled at locations in the plant where the crude liquid oxygen is in a liquid state and in proportion to the size of the once-through heat exchangers. Feed stream flow rate to the argon column is controlled in response to air flow rate to the plant and product flow rate is controlled in response to the feed stream flow rate to the argon column. ## Claims ### Claim 1 (canceled) ### Claim 2 (canceled) ### Claim 3 (canceled) ### Claim 4 (canceled) ### Claim 5 (canceled) ### Claim 6 (canceled) ### Claim 7 (canceled) ### Claim 8 (canceled) ### Claim 9 (canceled) ### Claim 10 (canceled) ### Claim 11 (canceled) ### Claim 12 (canceled) ### Claim 13 (canceled) ### Claim 14 (canceled) ### Claim 15 (canceled) ### Claim 16 (canceled) ### Claim 17 (canceled) ### Claim 18 (canceled) ### Claim 19 A method of condensing argon reflux within an air separation unit having an argon column, a lower pressure column and a higher pressure column, said method comprising the steps of: extracting a crude argon feed stream from the lower pressure column; distilling the crude argon feed stream in the argon column to produce an argon-rich vapor column overhead; directing at least a portion of the argon-rich vapor column overhead to a plurality of once-through heat exchangers; condensing the argon-rich vapor streams within condensation passages of the plurality of once-through heat exchangers such that argon-rich vapor streams composed of argon-rich vapor column overhead are condensed within condensation passages of the once-through heat exchangers to produce an argon-rich liquid product stream and argon-rich liquid reflux stream returning the argon-rich liquid reflux stream to the argon column as reflux; introducing one or more streams of crude liquid oxygen column bottoms from the higher pressure column into vaporization passages of the plurality of once-through heat exchangers to partially vaporize the crude liquid oxygen streams through indirect heat exchange with the argon-rich vapor streams to produce partially vaporized crude liquid oxygen streams introducing the partially vaporized crude liquid oxygen streams into the lower pressure column; sensing liquid flow rates of the crude liquid oxygen streams directed from the bottom of the higher pressure column to the vaporization passages of the plurality of once-through heat exchangers; controlling the flow rates of the crude liquid oxygen streams to the plurality of once-through heat exchangers in response to the sensed liquid flow rates and the level of the crude liquid oxygen bottoms in the higher pressure column; and controlling a feed stream flow rate of the crude argon feed stream in response to an air flow rate into the air separation unit and by controlling the reflux flow rate of the argon-rich liquid reflux by: (i) decreasing the reflux flow rate of the argon-rich liquid reflux stream when the feed stream flow rate is above a feed stream set point to thereby cause the argon-rich liquid reflux to back up into the condensation passages of the once-through heat exchanger causing an increase in pressure of the argon-rich vapor stream and within the argon column; and (ii) increasing the reflux flow rate of the argon-rich liquid reflux stream when the feed stream flow rate is below a feed stream set point to thereby cause a decrease in the pressure of the argon-rich vapor stream and within the argon column. ### Claim 20 (depends on 19) The method of claim 19 further comprising the step of controlling a product flow rate of the argon-rich liquid product stream in response to the feed stream flow rate of the crude argon feed stream. ### Claim 21 (depends on 19) The method of claim 19 wherein the step of controlling the flow rates of the crude liquid oxygen streams further comprises: controlling the flow rates of the crude liquid oxygen streams to the plurality of once-through heat exchangers via one or more flow control valves; and adjusting the flow control valves to attain a flow rate set points that are based on the sensed liquid flow rates and the level of the crude liquid oxygen bottoms in the higher pressure column; wherein the flow rate set points are decreased as the level of the crude liquid oxygen bottoms in the higher pressure column decreases and the flow rate set points are increased as the level of the crude liquid oxygen bottoms in the higher pressure column increase. ### Claim 22 (depends on 20) The method of claim 20 wherein the feed stream set point is a function of the air flow rate into the air separation unit multiplied by a crude fraction. ### Claim 23 (depends on 20) The method of claim 20 further comprising the steps of: measuring temperatures of the partially vaporized crude liquid oxygen streams; and further controlling the feed stream flow rate of the crude argon feed stream and the argon-rich liquid product stream product flow rate in response to the measured temperatures of the partially vaporized crude liquid oxygen streams, wherein the feed stream flow rate of the crude argon feed stream decreases when the temperatures of the partially vaporized crude liquid oxygen streams are above a predetermined temperature indicative of dry out conditions within the vaporization passages. ### Claim 24 (depends on 20) The method of claim 20 further comprising the steps of: measuring temperatures of the partially vaporized crude liquid oxygen streams; and controlling the reflux flow rate of the argon reflux stream in response to the measured temperatures of the partially vaporized crude liquid oxygen streams, wherein the reflux flow rate of the argon reflux stream is decreased causing the argon-rich liquid to back up into the condensation passages and further causing an increase in pressure of the argon-rich vapor stream and within the argon column when the temperatures of the partially vaporized crude liquid oxygen streams are above a predetermined temperature indicative of dry out conditions within the vaporization passages. ### Claim 25 (depends on 20) The method of claim 20 further comprising the steps of: measuring the flow rate of the argon-rich liquid product stream; further controlling the flow rate of the argon-rich liquid product stream via one or more product flow control valves to maintain the flow rate of the argon-rich liquid product stream at a product flow rate set point; wherein the product flow rate set point being a function of the feed stream flow rate of the crude argon feed stream multiplied by a product fraction.