The present invention relates to liquefying gases, and more particularly to an apparatus and process for liquefying gases such as nitrogen and oxygen using an air separation plant for the source of the nitrogen and oxygen, and having a top running pressure of about 420 psig without requiring electrical compressors to build this pressure. This is made to reduce the power bill.
Systems and methods for liquefying gases such as nitrogen and oxygen are well-known. The main process of producing large amounts of liquid nitrogen, oxygen, and argon is with an air separation plant. An air separation plant takes in atmospheric air and through a process of fractional distillation at cryogenic temperatures the component gases, or fractions, can be separated by their boiling points. There are other processes to separate air into its different gases, such as pressure swing absorption, vacuum pressure swing absorption, and others, but these are not making a transportable liquid. Today the production of a transportable liquid gas in large quantities requires a large number of compressors and expanders with all of the associated equipment such as cooling towers that require large amounts of electrical power to run at a high cost.
The process of making liquid gas today is to take gaseous pure nitrogen from two exiting streams of the main heat exchanger's warm side, one stream being the larger flow which is the low pressure nitrogen stream, and the other nitrogen stream having about half the flow but being higher in pressure. The larger flow, lower pressure 2 psig+/−1.5 psig nitrogen gas, along with the flash pot return flow from the liquefier section, this multi low pressure flow comes from the exit of two heat exchanger's warm sides. This low pressure flow is not all used and some is vented back to the atmosphere, while the remaining flow is sent to a low pressure nitrogen compressor, where the exit of the compressor is equal in pressure to the higher pressure multi feeds. The higher pressure flow is made of the exit of the main heat exchanger along with the exit of the low pressure nitrogen compressor and the gas off of the liquefier heat exchanger turbine return's warm side. All of the gas is sent to the recycle compressor, and then all of the gas is split to two turbine boosters. After each stage of compression the heat of compression is removed. This flow will be cooled down in four steps. The first step is the split off of gas to the warm turbine expander, and the second step is the split off of gas to the cold turbine. The remaining flow exits the liquefier heat exchanger where the gas is called a Soto liquid. The third step is to reduce the flow in pressure through a needle valve causing a Joule Thompson effect. The exit of the needle valve provides a two-phase liquid. The fourth step is to cool the liquid and gas down to all liquid, which is done in the flash pot. That is all the refrigeration needed.
Existing air separation plants designed to make liquids for sale in the industrial gas market normally use a liquefier. Current liquefiers make only a small amount of liquid per recycle pass (about 15.2% of the recycle compressor flow). Once the liquid is made, it is flash potted to become subcooled, and a small amount of liquid is returned to the air separation plant for refrigeration, while, the larger part of this liquid is sent to a storage tank. No liquid nitrogen is returned to the liquefier. There remains a need for an improved liquefier device.
The present invention is directed to a system, apparatus and process for liquefying gases such as nitrogen and oxygen. The presented system is an open loop refrigeration system which uses far less electrical power than existing liquefaction systems, and can be gradually implemented to replace existing systems, as existing power contracts which typically have a term such as five years expire.
In an embodiment, the liquefier device is one part of an air separation plant, and in another embodiment is a retrofit to an existing plant. The same process can take almost any gas to a liquid. For purposes of illustration, there is shown diagrammatically in
The oxygen stream 321 and the nitrogen streams 203 and 216 are fed to the liquefier device, which is an open loop refrigeration unit that takes in the separate streams as a pure gas and which streams will exit the liquefier device as a saleable liquid nitrogen at point 537 (see
The present system takes advantage of many properties of liquid nitrogen. One of these properties is that liquid nitrogen is mostly a non-compressible fluid that can be pumped up in pressure which occurs in the liquefier device at point 528 (
Some conventional air separation plants might have an oxygen and/or nitrogen pipe line which will take the gas described here to another compressor for the pipe line's use. The remaining gas can be used along with any gas the pipe line compressor would vent from time to time. Although not illustrated, it will be understood that these types of changes are able to be performed with a minimum number of modifications or changes to the air separation plant and the liquefier device of the present invention.
Additional areas of applicability for the present invention will become apparent from the detailed description provide hereinafter. It should be understood that the detailed description and specific examples of this preferred embodiment of the invention are intended for purposes of illustration only, that the temperatures, pressures, and purities shown here are close to actual readings but may not be exact, and are not intended to limit the scope of the invention. Other embodiments could be, for example, for the production of liquefied natural gas.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following detailed description is of the best mode or modes of the invention presently contemplated. Such description is not intended to be understood in a limiting sense, but to be a non-limiting example of the invention presented solely for illustration thereof, and by reference to which in connection with the following description and the accompanying drawings one skilled in the art may be advised of the advantages and construction of the invention.
The following detailed description will describe the liquefier device of the present invention with reference to an air separation plant site having an inlet gas air flow of 780,000 standard cubic foot per hour at the inlet meter box, and will make over 650 tons a day of saleable liquids, running with the liquefier device.
THE BASE LINE. The inventor will first explain one way an air separation plant making over 650 ton a day of liquid product could run. The following explanation is based on an oxygen content of 4 ppm and zero argon on all pure nitrogen streams, and on a standard cubic foot of gas at one atmosphere and at 70 degrees Fahrenheit. The plant site location is around sea level, with an 80 degree Fahrenheit dry bulb temperature and a 70 degree Fahrenheit wet bulb temperature. In addition, the Table included herein provides temperature, pressure, and flow readings for each reference numeral point or step within the air separation plant and liquefier device assembly as described herein with reference to the FIGS., as well as the Figure location, and other comments.
THE AIR SEPARATION PROCESS. Referring now in particular to
There is a line to the instrument air supply header controlled by an on/off valve 112 normally open to send a supply of filtered air to the backup gas nitrogen system (see
In addition to splitting off to line 201, there is a stream of pure nitrogen gas off the high pressure column 114 in line 200 that will be removed in line 202 to the main heat exchanger 113, where the gas nitrogen stream is warmed and exits the main heat exchanger 113 at point 203. The gas is then directed to the high pressure nitrogen inlet line to the liquefier, shown in
The joined flow 225 will enter the low pressure column 116 at tray 65. The gas at the top of the low pressure column 116 exiting in line 210 is mostly nitrogen. The liquid nitrogen from the liquefier device in line 544 that is directed to the pure argon system (
Referring again to the low pressure column 116 in
Staying with the crude argon column 118, the gas in line 15 from the low pressure column 116 enters the crude argon column and rises to the reboiler 119 thru 38 trays. The gas will turn to liquid and gas in the reboiler 119 tube side. The liquid and gas will exit to the phase separator 121, and the gas off of the phase separator 121 is directed to the argon liquefaction system (
THE PURE ARGON SUBSYSTEM. Referring now primarily to
The argon to process comes in from
The combusted argon 402 is warm as it enters the argon heat exchanger 133. At the cold side of the argon heat exchanger 133 the flow 415 is directed to a hydrogen separator 127, and is almost forming a liquid as it enters the hydrogen separator 127. The gas in line 416 upon exiting the hydrogen separator 127 will rise to the tube side of the argon reboiler 128 due to the condensing action of the reboiler. The reboiler 128 is not cold enough to liquefy the left over hydrogen from the deoxo-catalyst bed 138, and therefore will collect at the top of the reboiler tube side and all the argon and nitrogen will liquefy and fall at 417 to the bottom of the hydrogen separator 127, as there are no trays here. The hydrogen at the top of the reboiler is removed at 419 to a flow control valve and is sent back in line 403 to joined suction flow 404 of the argon compressor.
The liquid at the bottom of the hydrogen separator 127 is removed at 418 to a level control valve that in line 420 feeds the pure argon column 130. This flow contains argon and nitrogen, with a trace of oxygen and hydrogen. This liquid was not subcooled and will flash after decompression. The liquid and gas mixture will separate, and the gas will rise thru distillation trays and the liquid will overflow the tray to the tray below until it collects at the bottom.
The liquid at the bottom of the pure argon column will first collect around the outer shell ring 129 of the reboiler shell side 128, and after that ring is full, the liquid will fill the bottom of the pure argon column 130. This liquid is then removed at 425 to a level control valve and is joined at 427 with the recondensed argon in line 431 heading to the pure argon tank 124. The gas that entered the pure argon column 130 will rise thru distillation trays until it is condensed in the tube side of the condenser 131. The condenser 131 shell side is full of liquid nitrogen and this makes it cold enough to liquefy in line 421 the nitrogen in the argon but will not liquefy the hydrogen. The liquid and gas bubbles will be removed in line 422 to the phase separator 132. A small amount of gas is removed to a flow control valve that exits at 423 to atmosphere. This valve is always very cold and needs a warming purge flow, which is received from the backup gas nitrogen system (
The argon in the storage tank 124 has a vent line 428, and the argon transport trailer 123 has a similar vent line 429 both of which will vent excess pressure through a vent auto pressure control valve. The vented gas will share the same line at 430 to the tube side of the argon recondenser 125 where it will be liquefied, and in line 431 the liquid is returned to the joined line 427 to the argon storage tank 124.
There are two argon dryer beds used in this process, identified in
THE TAKE OR VENT INLET PIPING TO THE LIQUIFER. As illustrated in
Referring now to
In
In
THE LIQUIFIER. Referring now to
The low pressure nitrogen gas stream to the liquefier device comes in from
The high pressure column gas nitrogen stream to the liquefier device comes in from
In addition, there is a flow from the turbine package or assembly,
The major flow of compressed nitrogen gas from the turbine assembly at
The two-phase stream is sent to the next heat exchanger 150 called the added cooling heat exchanger. Here the two-phase nitrogen stream will be cooled a little more but will still be a two phase stream at the exit. The two-phase stream is then directed into the pump flash pot 149 tube side where the nitrogen stream will be all liquid. The exit temperature at the pump flash pot 149 will be set to hold a boiling point of the boiler 145 after the pump. The liquid nitrogen is cold enough to be used. The liquid nitrogen off of the pump flash pot 149 will branch off to five places, which are to the liquid nitrogen pump (
Transition from
Two separate liquid nitrogen pumps 169 and 170 are shown in
The next branch off of the pump flash pot 149 in
The next branch off from the pump flash pot 149 is to the level controller valve 512 (
The last branch off from the pump flash pot 149 is to the tube side of the nitrogen production flash pot 148 (
Referring now to the liquid nitrogen feed to the boiler 145 in
Vaporized nitrogen coming out of the boiler 145 is routed to the preheater 152. The preheater 152 can be warmed by three flows, namely: the booster four aftercooler exit called the major flow controlled by valve 503, the booster one aftercooler exit controlled by valve 274, and the high pressure column and turbine exhaust flow controlled by valve 456. This can be monitored by the auto opening of valve 451. Valve 451 will drain excess liquid produced by the four turbines that is not used by the three flash pots.
The exit of the vaporized nitrogen flow from the preheater 152 goes to the turbine assembly illustrated in
Point 450 in
Filling of the oxygen production flash pot 147 shell side by a level control valve 452, this should be the only filling valve needed for the flash pot 147. Another valve 513 is provided in cased it is needed but is closed on normal operation. The liquid nitrogen being supplied to the flash pot 147 by level control valve 452 is not subcooled and will flash when decompressed. The rest of the liquid will boil away as the tube side liquid oxygen is cooled. The exit oxygen temperature control is from the liquid height of the nitrogen shell side bath, and the pressure held on the exit nitrogen gas in line 461. The vent valve 382 on the oxygen storage tank 177 (see
Looking at the nitrogen production flash pot 148 in
The pump flash pot 149 has a level control valve 454 which should be the only liquid nitrogen supply to the shell side. Other valves, including valves 530 and 512, should be closed and are there if needed. The pump flash pot 149 tube side liquid nitrogen must be monitored to control its flash off point. The liquid should be a single phase as it exits the nitrogen pump, but not so cold that it stops the boiler as it enters. The tube side liquid nitrogen therefore has to be monitored and the shell side liquid nitrogen height and pressure controlled.
After all three flash pots 147, 148, and 149 have taken what they need from the three percent of produced liquid off of the turbine exhaust phase separator 151, there should be a small amount left over. This is passed through a level control valve 451 and liquid that is not subcooled will flash when decompressed. The flashing liquid nitrogen is put into a low pressure line used by the nitrogen production flash pot exhaust gas. As this valve 451 opens and closes it will show how the exit temperature of the four turbines are doing. If the valve 451 closes a little, that shows more liquid is being used by the flash pots, or the preheater is running to warm, or the boiler pressure is changing to a lower pressure.
The three flash pots 147, 148, and 149 shell sides will exit gas nitrogen. The oxygen production flash pot 147 will exit the shell side nitrogen gas in line 461 to the condenser 146. At the exit of the condenser pass there is a branch off to a pressure control valve 260 or a check valve 261. Check valve 261 will take a small flow during startup to the turbine exhaust header but when the turbine exhaust pressure goes above the flash pot pressure auto pressure control valve 260 will move the gas to a low-pressure line. During normal operation, check valve 261 is closed and pressure control valve 260 is controlling. The nitrogen production flash pot 148 shell side will exit the shell side gas in line 459 to the added cooling heat exchanger 150, then join with the exhaust from valve 451, and the joined flow is to the condenser 146. The flow off of the condenser 146 will pick up the exit of the auto pressure control valves 260 and 262, and then enter the boiler 145. The gas off of the shell side of the pump flash pot 149 in line 460 will go to the added cooling heat exchanger 150. The exit off of this pass will go to the condenser 146, and exit to a branch off to a check valve 263 and to an auto pressure control valve 262. Check valve 263 will take a small flow during startup to the turbine exhaust header but when the turbine exhaust pressure goes above the flash pot pressure, an auto pressure control valve 262 will move the gas to a low pressure line. Normal operation is check valve 263 closed and pressure control valve 262 is controlling. Now the low pressure line off the three flash pots 147, 148, and 149 will go to the boiler 145, then to the oxygen cooler 144, and then to auto pressure control valve 264.
The four turbine exhaust flow at point 450 from
The pressure control valve 264 should run wide open if all the flow from the low pressure nitrogen inlet line (
The nitrogen gas exit from the aftercooler 156 will branch off to three places, namely, a flow to the surge control return gas flow through control valve 271, a flow 273 to warm the preheater 152 (
The last flow from the aftercooler 156 is to the check valve 276 heading to the next booster 159. The exit of the check valve 276 is joined with a small flow in from line 275 (from
The flow from the surge control system 282 check valve and the flow from the aftercooler 160 will enter the flow meter 280. The gas will be compressed by the next booster 163 and exit to the aftercooler 164. The exit of the aftercooler 164 will branch off to the surge control valve 281 and to the booster 167. The surge control system is normally closed, but for startup valve 281 slowly opens to a check valve 282 which will add flow to the booster 163 inlet.
The rest of the exit flow from aftercooler 164 will go to a joined flow of the surge control system exit check valve 285 and from line 458 from
There is an air feed 2 coming from the air separation unit in
The gas nitrogen supply coming in to the back up gas nitrogen system from
The purpose of each of the branches off of the main purge header will now be explained. As shown in
There are four separate branches 34, 35, 42, and 43 off of the main purge header to the turbine package shown in
Another flow off of the main purge header is to point 41 in
THE OXYGEN FILTER HOUSE. Some air separation plant sites have built-in heat pumps and gel trap filters to remove solid concentrations in the liquid oxygen at the reboiler. Some plants have a filter to the transport trailers at the filling station. Some plants have a filter to the storage system. Those plant sites will not necessarily need the liquid oxygen filter house illustrated in
The inventor's new liquefier takes almost all the oxygen production out of the air separation plant as gas. This will leave behind a small amount of liquid oxygen that has some solid contamination which must be removed to hold down the concentration of the contamination. The oxygen filter house system has two gases and one liquid to move around without blending. The gasses here are pure nitrogen gas, and atmosphere air, and the liquid is pure liquid oxygen. To do this, each system must be protected. The best known way to protect a purity is to keep the pressure above atmosphere pressure, and then to use a blocking system, or a way to stop one flow from moving into the next one. Since the pressures here are above atmosphere pressure, a double block and bleed system is used. This will stop flow by a valve whose exit is to atmosphere. If a valve that is used to block a flow were to leak, then that flow could leak but only to the atmosphere, and not to the next product. All the double block and bleed nest of valves must have a relief valve.
The liquid oxygen flow from the air separation plant comes in from
If the oxygen produced by the air separation plant is to be dumped, the whole system is assumed to be or going bad. Quick action must be taken, and all the valves to be closed at once are 313, 316, 381, 61, 63, 69, 64, 70, 343, 357, 346, 360, 377, 378, 339, 372, 351, 365, 352, 366, 342, 355, and 369. In addition, all the valves to open at the same time are 68, 338, 345, 376, 359, 315, 66, 72, 341, 350, 364, 354, 368, 371, and 380. The valves to control the flows are valve 312, 68, 336, 177. Valve 312 controls the height of the tube side of the oxygen production flash pot vessel 147 (
When the purity is established, the system of opening the different subsystems starts. The largest flow will be the liquefier oxygen (from
When the purity of the air separation plant's liquid oxygen is good, then for a short time the oxygen with all the solids will go to storage during the time the filters are being worked on. The filters must be opened slowly, and dumping or bypass liquid to storage can continue. In the embodiment shown in
Setting up filter 175 for service. The liquid oxygen is at a good purity and first open reboiler auto level controller valve 343 in manual mode is opened about 25%. This will vent liquid oxygen out bleed valve 345. When a steady stream of liquid oxygen is detected, then valve 346 is opened, and bleed valve 345 is closed. This will vent liquid oxygen out bleed valve 350. The line supplying bleed valve 350 is small and it should take a few minutes to cool down enough to allow a steady flow of liquid oxygen to exit. A close eye must be kept on the active liquid controller, as it is very possible to over draw the liquid from the reboiler, and if this is starting to happen the auto controller valve 336 will close. If the liquid from the reboiler is being overdrawn then for a short time valve 350 should be closed until the reboiler height is reestablished and the auto controller valve 336 reopens. Then, valve 350 is reopened. By monitoring the temperature sensor 348, the cooling process can be tracked. After the liquid oxygen is flowing at a steady stream out valve 350 and the purity is still satisfactory, then valve 352 is opened to vent out bleed valve 354 and valve 350 is closed. After a steady stream of liquid oxygen is seen exiting valve 354 then open valve 355 and close valve 354. The reboiler auto controller valve 336 is also then set to a higher level and reboiler auto level controller 343 is set to auto mode with a set point at normal reboiler height. The bypass line is then closed by closing valves 342 and 339, and then opening valves 338 and 341. The system is now filtering the solids out of the liquid oxygen from the air separation plant, and the liquefier liquid oxygen is joined to storage.
Next, filter 176 is reactivated, going from the same sequence as above. Recap closed valves are 61, 63, 64, 69, 70, 345, 357, 360, 377, 378, 339, 350, 351, 372, 365, 354, 366, 342, 369, 380, and 315. The valves open at this time are 338, 341, 346, 352, 355, 376, 371, 359, 364, 368, 316 and 381. The valves in auto control are 68, 313, 312, 343, 336, and 382.
Bleed valve 364 is open so any liquid could vent, but to make sure valve 61 is opened so that a flow will be started and seen by flow monitor 60. Flow monitor 60 will be set to 100 scfh and for now valve 68 will control the flow. Then flow controller valve 69 is opened in manual mode to 25% open, and the gas nitrogen will vent out of valve 72. Auto flow controller valve 68 will then start to close, because valve 69 is taking some of the flow. Then, valve 70 is opened, and valve 72 is closed. Auto control valve 68 is set to 90 scfh and auto flow controller valve 69 is adjusted to a set point of 100. If the flow falls below 90 scfh then valve 68 will be called to open. If valve 68 is called to open, then the operator will be notified. The solid contamination the filter removes will turn to gas before the filter temperature 362 hits −90 degrees Fahrenheit. When the temperature hits −80 degrees Fahrenheit the reactivation is finished. Now, valves 69, 70, and 364 are closed, and valve 72 is opened. Valve 68 is in control and set to open if the flow goes below 90 scfh as seen by flow monitor 60. Closing valve 61 therefore will stop the entry of nitrogen gas and by default valve 68 will auto open.
Moving to the cool down of filter 176, the cleaned exit flow of filter 175 is used to cool down filter 176. Opening valve 351 will vent liquid oxygen out bleed valve 371. Once a steady stream of liquid oxygen is seen exiting valve 371, valve 371 is closed, and auto flow control valve 372 is opened, and will be open 25% in manual mode. This will pass a liquid oxygen flow through a check valve (373), to a flow monitor (375), and exit valve 376. Once a steady flow of liquid oxygen is seen exiting valve 376, then valves 378 and 364 are opened. The cool down flow will be seen on flow meter 375.
Auto flow controller valve 372 will be put into auto control mode, and be set to 100 scfh controlling the flow seen at flow meter 375. The cooling process will be seen on temperature monitor 362. This process of cooling the filter will take hours due to the small flow. Once the temperature monitor 362 reaches a −250 then the cool down mode is complete, and the filter 176 will be put on standby mode.
To set up a standby mode for filter 176, the flowing valves must be closed; 351, 372, 378, 364, and the valves to be open are 371 and 376. The process of standby is to let a cooled filter 176 sit with valves closed. If there is any gas expansion, the vessel is protected by relief valve 363. In addition, there will be a cycling of opening and closing valve 364 once every ten minutes, since protecting a vessel with only a relief valve may be insufficient in reducing the expansion of gas trapped.
The next mode of operation of the liquid oxygen filters is dull filter running, which is how to move the filtration from one filter to the next. The standby mode is stopped. The only valve in operation on filter 176 is valve 364, which will open and close on a timer of once every 10 minutes for one tenth of a second. This will stop on an open sequence, and valve 357 will open in manual control to 25% open. A flow of oxygen liquid will be seen coming out of bleed valve 359. Then valve 360 is opened and valve 359 is closed. Liquid oxygen will go out through valve 364. During the startup of filter 176 the amount of liquid oxygen to be used will cause auto level control valve 343 to start closing. If valve 343 were to close, then the valve opening on auto level control valve 357 which is in manual mode is reduced to 10%. After liquid oxygen is exiting valve 364 then valve 366 is opened, and bleed valve 364 is closed. Liquid oxygen will flow out of bleed valve 368. After that valve 369 is opened. Now both filters 175 and 176 are filtering.
The next step is to stop filter 175. Level controller valve 343 in manual is set at 5% open, and level controller valve 357 is put into auto mode with a set point of the reboiler height. This will take about 3 to 5 minutes to settle out, and then valves 343, 346, 351, 352, and 355 are closed, and valves 354, 350, and 354 are opened.
Filter 175 is drained, with any liquid oxygen in filter 175 will drain out of valve 350 as the liquid turns to gas. In addition, valve 61 is opened and auto control valve 63 is set to 100 scfh. This will vent nitrogen gas out of valve 66. Then valve 64 is opened and valve 66 is closed. Auto flow control valve 68 is set to open below 90 scfh, and auto control valve 63 is set to open below 100 scfh. This should cause valve 68 to close because the flow will be above the set point. The liquid in filter 175 will be draining out of valve 350.
Filter 175 is put in to heat up, after the liquid is drained out of valve 350. Then the flow will stay the same. The point to monitor is the filter temperature sensor 348. When the filter temperature hits −80 degrees Fahrenheit, the heat up is done.
To put filter 175 into cool down, the heat up is stopped by closing valves 61 and 63. This will cause auto flow control valve 68 to open due to a loss of flow. The set point for valve 68 is open below 90 scfh. Valve 64 is then closed, and bleed valve 66 is opened. Using the clean liquid oxygen out of filter 176, valve 365 is opened to bleed valve 371 is closed. After valve 371 has a steady flow of liquid oxygen exiting it, then valve 372 opened and valve 371 is closed. Valve 372 is put in manual mode and open 10%, and once liquid oxygen comes out of valve 376, open valve 377 and close valve 376. Flow meter 375 will show a flow and should be set to a flow rate of 100 scfh and auto flow control valve 372 will be used to control the flow. The flow will exit valve 350. Once the flow cools down the filter to −250 as seen on temperature sensor 348 then the cool down is done.
Put filter 175 to stand by mode. Stop cool down and close valves 365, 372, 377, and 350. Open bleed valves 371, and 376. Now cycle valve 350 open and closed once every ten minutes to stop an over pressure.
Put filter 175 into dull operation mode. When needed filter 175 will be put into dull operation with filter 176. First open auto level control valve 343 in manual mode at ten percent open. This will vent liquid oxygen out of bleed valve 345. When a steady flow of liquid oxygen exits bleed valve 345, then open valve 346, and close bleed valve 345. The flow will exit valve open valve 350. The temperature monitor 348 will show the progression of cool down to operation. Once the flow out of valve 350 shows a steady stream of liquid oxygen then open valve 352 and close valve 350. The flow will now exit bleed valve 354. Once bleed valve 354 shows a steady flow of liquid oxygen then open valve 355, and close valve 354. Now put auto level controller valve 343 into auto mode and set auto level controller valve 357 into manual mode at five percent open. Once the system is working for a few minutes and is stable, then put the filter 176 into stop mode. Put valve 357 into auto level control.
Put filter 176 into a stop mode. The system just switched over from filter 176 on line to filter 175 on line. Now stop filter 176 and close all valves 357, 360, 366, and 369. Now open 368, 364, and 359. Any liquid in filter 176 will be able to drain out of valve 364. Then again go through the warm up steps above.
During the operation of the filters there is a differential pressure gauge to show filter clogging. This should be monitored and logged to find out how long the filter can be in operation. The differential pressure gauge for filter 175 is 347, and the filter 176 has differential pressure gauge 361. This is a list of relief valves found on
The liquefier presented herein will boil liquid nitrogen to generate running gas pressures for the turbines. The liquefier is designed to work with an air separation plant, running at a stable state. The air separation plant will supply a steady stream of gaseous nitrogen and oxygen from the main heat exchanger warm end. Then, from the new liquefier, a stream of sub cooled liquid nitrogen and liquid oxygen will be sent to storage, along with a small amount of liquid nitrogen that will be returned to the air separation plant to make liquid oxygen in the low pressure column, and liquid argon both to storage. The air separation plant will be running at a reduced pressure due to the low pressure column's lower pressure. The air separation plant will be running on a maximum oxygen gas removal mode. The air separation plant, with a MAC flow like shown above, and this presented liquefier will produce liquid argon, and 2,000 scfh oxygen liquid needed to keep the hydrocarbons under 5% and remove all the krypton and xenon solids that would normally build up in the low pressure column's reboiler and be cleaned up in the oxygen filters. The plant can run a lower pressure by having almost all the oxygen removed as a gas, then oxygen gas will be liquefied in this invention, then put to storage as sell able product. The liquefaction of the oxygen gas from the low pressure column, that is not needed for a pipe line gas customer can then take place in the present liquefier. All the gas nitrogen that is not needed for a pipe line customer can be liquefied in the presented liquefier.
The presented liquefier will produce sell able liquid for less cost than what is being used today. The compressing of gas to a pressure needed to make liquid costs a lot of money. The temperature of the liquids to storage can be adjusted to meet the storage tank positive pressure requirements. The sub cooler in the distillation cold box has no control passed original design for reducing the liquid oxygen to storage temperature. This invention gives the control. The oxygen filter system can be used on any plant making liquid oxygen. This will produce liquid oxygen with less contamination. This liquefier can be placed at the end of a long pipe line to liquid at remote location. This will reduce shipping cost, and reduce truck traffic around the main plant. This liquefier can also be placed on-board a ship moving liquefied natural gas. This will keep the liquid cold to stop the venting.
While the present invention has been described at some length and with considerable particularity with respect to the several described embodiments and particularly with respect to the particular and principal intended embodiment, it is not intended that it should be limited to any such particulars or embodiments or any particular preferred embodiment but is to be construed with reference to the particular appended claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the effective and intended scope of the invention with respect both to apparatus for practicing the invention and to methods of performing and practicing the invention. As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range.
This application claims the benefit of U.S. Provisional Application No. 62/506,932, filed May 16, 2016, which is incorporated herein by reference in its entirety.
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0795727 | Sep 1997 | EP |
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Entry |
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PCT/US18/33052 Written Opinion of the International Searching Authority and International Search Report. |
Number | Date | Country | |
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20180335256 A1 | Nov 2018 | US |
Number | Date | Country | |
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62506932 | May 2017 | US |