US20080047298A1 - Process and apparatus for generating a pressurized product by low-temperature air fractionation - Google Patents

Process and apparatus for generating a pressurized product by low-temperature air fractionation Download PDF

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US20080047298A1
US20080047298A1 US11/735,171 US73517107A US2008047298A1 US 20080047298 A1 US20080047298 A1 US 20080047298A1 US 73517107 A US73517107 A US 73517107A US 2008047298 A1 US2008047298 A1 US 2008047298A1
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pressure
piv
stream
process according
reservoir
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Horst Corduan
Ulrich Ewert
Gerhard Pompl
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Linde GmbH
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Linde GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04836—Variable air feed, i.e. "load" or product demand during specified periods, e.g. during periods with high respectively low power costs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04103—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression using solely hydrostatic liquid head
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04848—Control strategy, e.g. advanced process control or dynamic modeling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/10—Mathematical formulae, modeling, plot or curves; Design methods

Definitions

  • the invention relates to a process for generating a pressurized product by low-temperature air fractionation by means of internal compression in which:
  • a “distillation column system” comprises at least one separation column and also the condensers and evaporators assigned to the separation columns of the system.
  • the distillation column system for nitrogen-oxygen separation of the invention can be constructed as a one-column system for nitrogen-oxygen separation, as a two-column system (for example as a classic Linde-twin-column system), or else as three-column or multiple column systems.
  • it can have other devices for producing other air components, in particular noble gases, for example argon production.
  • At least one of the products is taken off in the liquid state from one of the columns of the distillation column system or from a condenser connected to one of these columns, brought in the liquid state to an elevated pressure, vaporized or (at supercritical pressure) pseudovaporized in indirect heat exchange, for example with feed air or nitrogen, and finally obtained as gaseous pressurized product and fed to a take-off system which consists, for example, of a gas pressure reservoir.
  • the pressure increase in the liquid can be carried out by any known measure. Generally pumps are used in this process. However, it is also possible to utilize a hydrostatic potential and/or the pressure build up vaporization in a tank.
  • “Gas pressure reservoir” is here taken to mean any system which serves for buffering gaseous pressurized product and in particular has a buffering capacity which is sufficient to compensate for periodic take-off fluctuations or which is sufficient to compensate for temporary deficits or surpluses in production which occur during load changes.
  • periodic take-off fluctuations is the oxygen supply to a steelworks in which owing to the operation of the converters at regular intervals, high volumes of oxygen are required in the short-term.
  • a further example is an air fractionation unit whose production is continuously adjusted to a current consumption, but the load (production rate) of the air fractionation unit cannot be changed at the same rate as the consumption and therefore temporary deficits or surpluses occur during the load adjustment.
  • the buffering capacity of the gas storage reservoir should be sufficient to compensate for the deficits or surpluses in production occurring due to a typical change of the consumption (within minutes or seconds) in such a manner that the production of an air fractionation plant can follow the change in consumption, without the minimum or maximum permitted pressure limits of the product being infringed.
  • the load adjustment time of a typical air fractionation unit for a change in load over the full load range of 70% to 100% is 30 minutes to 2 hours.
  • a “gas pressure reservoir” Since a “gas pressure reservoir” is associated with high capital costs, it will generally not be designed for all possible cases, but only for the take-off fluctuations typical during normal operation. Exceptional situations must be covered if appropriate by blowing off the product or by an additional supply (for example evaporator for cryogenic liquids).
  • Gas pressure reservoir is taken to mean in particular a system which has a buffering capacity which is at least equal to the amount of liquid product stream (pseudo)vaporizing to the pressurized product which the distillation column system generated in standard operation within a certain time period, for example at least equal to the amount generated within one minute, in particular at least equal to the amount generated within five minutes, or at least equal to the amount generated within 10 minutes.
  • the buffering capacity of a gas pressure reservoir is determined by its volume and the possible width of variation of its pressure, that is to say the difference between the maximum and minimum operating pressure.
  • the minimum operating pressure is established by the pressure requirements of the consumers, the maximum operating pressure by the construction of the gas pressure reservoir and safety regulations applicable thereto.
  • a “gas pressure reservoir” can be formed, for example, by one or more dedicated gas pressure reservoir vessels or by a pipeline system having long piping lengths which serves, for example, for supplying a plurality of consumers with pressurized gas.
  • Such a “gas pressure reservoir” is operated in a defined pressure range which is determined by a minimum permissible pressure and a maximum permissible pressure. Between these two values there is typically a difference of at least 2 bar, in particular at least 5 bar, preferably at least 10 bar.
  • the larger the permissible width of variation of the pressure the greater the available capacity in the pressure buffer of the gas pressure reservoir.
  • the necessary capacity of the pressure buffer depends essentially on the course of the take-off fluctuations which are generally subject to a defined systematic change.
  • the pressurized product obtained in the distillation column system must have a pressure which is higher than the pressure in the gas pressure reservoir. Hitherto this demand was met by the internal compression product being vaporized at a pressure which ensures introduction of the pressurized product into the gas pressure reservoir even at the maximum pressure of the gas pressure reservoir. The pressure during vaporization and also the operating pressures in the distillation column system are kept constant. In the case of a currently lower pressure in the gas pressure reservoir, the gaseous pressurized product is throttled, as a result of which energy is lost.
  • one aspect of the present invention is to provide a process of the type mentioned above which operates particularly expediently with respect to energy.
  • the elevated pressure (that is to say the pressure of the internal compression product) is varied and the elevated pressure (PIV) is varied as a function of the pressure (PA) of the gas pressure reservoir.
  • the vaporization can take place at reduced pressure when the pressure in the gas pressure reservoir is below its maximum value. This means that less energy need be used for vaporizing the product stream.
  • a gaseous heat carrier stream is compressed to a high pressure (PW) and used at this high pressure for the (pseudo)-vaporization of the liquid product stream by indirect heat exchange.
  • PW high pressure
  • MW high pressure
  • PA pressure
  • the last-mentioned variation can be directed according to the pressure of the internal compression product (PIV); the said dependence on the pressure (PA) of the gas pressure reservoir is then an indirect one.
  • the heat carrier stream can be formed, for example, by a substream of the feed air or by a nitrogen stream from the distillation column system. Frequently, a substream of the feed air is recompressed, used as heat carrier stream, and subsequently introduced into the distillation column system for nitrogen-oxygen separation. “Rate” is taken to mean here the molar amount per unit time which is measured, for example, in Nm 3 /h.
  • energy can also be saved as a result of the fact that the cold generation at reduced pressure (PA) in the gas pressure reservoir is decreased by varying the amount of cold generated in the cold generation system of the process as a function of the pressure (PA) of the gas pressure reservoir.
  • PA pressure
  • the cold generation system can comprise one or more expansion machines for work-producing expansion of one or more process streams, one or more cold systems driven by external energy and or the supply of cold by one of more low-temperature liquid streams.
  • the rate of one or more process streams passed via an expansion turbine is controlled. At reduced pressure in the gas pressure reservoir, this is decreased. Correspondingly decreased demand for pressure energy leads to further energy savings.
  • one or more operating parameters of the distillation column system is varied as a function of the pressure (PA) of the gas pressure reservoir.
  • a load change system can comprise feed-forward control, for example an ALC (automatic load change), or a multivariable control unit, for example an MPC (model predictive control).
  • feed-forward control for example an ALC (automatic load change)
  • MPC model predictive control
  • the controlled adjustment of these operating parameters ensures consistency between the selected internal compression pressure and the operating point of the distillation and in addition avoids impermissible loading of the heat exchanger.
  • An essential advantage of use of a load change system is the possibility of limiting the gradient of the internal compression pressure, that is to say the internal compression pressure does not follow the take-off pressure at any optional speed, but in a controlled manner. This can lead to an increased throttling or to blowing off of the product stream, in the event of rapid change of the take-off pressure in a transition phase, even in the process according to the invention. In contrast to conventional processes, such occurrences proceed only for a short time, however.
  • the load change system in this embodiment of the invention is constantly active and adjusts the preset value for the internal compression pressure to the current take-off pressure.
  • the preset pressure value of the load change system forms the sum of the current take-off pressure and a preselected difference, in order to avoid unnecessary blowing off when the take-off pressure rises.
  • this type of load control can be combined with a load change system for the product rates.
  • gas pressure reservoir for example a pipeline
  • the pressure course in the gas pressure reservoir is determined on the basis of available information on the future need of the connected end consumers. This can be used in the context of the present invention for determining the preset pressure value for the load change system in order to avoid blowing off product as far as possible.
  • the elevated pressure (PIV) is only just above the instantaneous pressure (PA) of the gas pressure reservoir ( 19 ); in particular, the difference (PIV ⁇ PA) between these two pressures is constantly less than half, in particular less than one third, in particular less than one fifth, of the range of variation of the pressure of the gas pressure reservoir ( 19 ).
  • the range of variation of the pressure of the gas pressure reservoir is taken to mean the difference between the maximum permissible pressure and the minimum permissible pressure of the gas pressure reservoir.
  • the invention moreover relates to an apparatus for generating a pressurized product by low-temperature air fractionation comprising:
  • FIG. 1 shows a roughly simplified plan of the process and the apparatus according to the example.
  • FIG. 2 shows a diagram of the time course of the take-off pressure and the internal compression pressure.
  • Air 1 is brought to a first pressure P 1 in a main air compressor 2 .
  • the compressed air 3 is purified in a purification unit 4 .
  • the purified air 5 is branched into a first substream 6 and a second substream 7 .
  • the first air substream 6 is cooled in a main heat exchanger 9 to about dew point and flows via the lines 10 and 11 into the distillation column system 12 for nitrogen-oxygen separation which, in the example, has a high-pressure column, for example, at 5-15 bar, and a low-pressure column, for example, at 1.2-3 bar, which are in a heat-exchange relationship via a shared condenser-evaporator, called the main condenser.
  • the air 11 is introduced into the high-pressure column in a virtually completely gaseous state.
  • the air is fractionated into at least one oxygen-enriched product steam 13 and at least one nitrogen-enriched fraction (which is not shown).
  • the product stream 13 has, for example, an oxygen content of 98 to 99.5 mol %. It is taken off in the liquid state, for example from the bottom of the low-pressure column or the evaporation space of the main condenser.
  • a pump 14 the liquid product stream 13 is brought to an elevated pressure PIV which is higher than the operating pressure of the distillation column from which it was taken off and is, for example 15 to 30 bar.
  • the oxygen 15 is passed at the elevated pressure in liquid or supercritical state to the cold end of the main heat exchanger 9 and in the main heat exchanger is vaporized or pseudovaporized and warmed to about ambient temperature.
  • the product stream leaves the system as gaseous pressurized product 16 , 18 and is introduced into a gas pressure reservoir 14 which, in the example, is constructed as a pipeline system.
  • the gaseous pressurized oxygen is finally delivered to a number n, which is in principle as many as is desired, of consumers V 1 to Vn.
  • the pipeline system also serves as product buffer.
  • the pressure of the gas pressure reservoir (at the point where line 17 joins) in the example can vary between a maximum permissible pressure of 30 bar and a minimum permissible pressure of 15 bar.
  • the heat required for the (pseudo)vaporization is supplied by a heat carrier stream 21 which is also termed internal compression air and is a part of the second air substream 7 which is recompressed in a secondary compressor 20 to a high pressure PW which is higher than the first pressure P 1 .
  • the pressure P 1 is, for example, 5-15 bar, and the pressure PW is, for example, 30 to 40 bar.
  • This pressure in substream 21 / 22 is adjusted via the valve 8 and the guide vanes of the compressor 20 .
  • the internal compression air 22 flows through the main heat exchanger 9 to the cold end and in so doing is condensed or, at supercritical pressure, is pseudo-condensed, in indirect heat exchange with the (pseudo)-vaporizing oxygen 15 .
  • the internal compression air is expanded via a valve 30 and at 23 enters, in part liquefied state, the distillation column system 12 for nitrogen-oxygen separation.
  • Another part 25 of the second air substream 7 / 21 is passed out of the main heat exchanger at an intermediate temperature as a turbine stream. Its rate relative to the internal compression air is adjusted via the guide vanes of the turbine. The ratio of the rates of the first substream 6 and second substream 7 / 21 is set via an expansion valve 30 in substream 22 .
  • the turbine air 25 is expanded to about the operating pressure of the high-pressure column in an expansion turbine 26 .
  • the expanded turbine air 27 is introduced together with the first substream 10 via line 11 into the high-pressure column of the distillation column system for nitrogen-oxygen separation 12 .
  • the turbine 26 in the example is a preferred element in a cold generation system of this unit, but other types of cold generation systems not requiring such a turbine, could be used.
  • the entire air fractionation unit would operate in a steady state and the pump 14 would continuously generate a pressure of somewhat more than the maximum take-off pressure of, for example, 30 bar.
  • the adjustment to the current take-off pressure would be achieved solely by an appropriate throttling in valve 18 .
  • the outlet pressure of pump 14 is adjusted to the instantaneous take-off pressure.
  • the pump 14 is set to an outlet pressure, or elevated (PIV) pressure, which is about 0.5 to 2 bar above the instantaneous take-off pressure, or pressure (PA) of the gas pressure reservoir ( 14 ).
  • PV outlet pressure
  • PA pressure
  • a certain difference as a margin is logical in order that, even when the take-off pressure increases, the gaseous pressurized product 16 need not be blown off immediately via line 28 and valve 29 .
  • the corresponding fine adjustment is performed by valve 18 in which only a slight pressure decrease is performed, however.
  • the various pressures in the air fractionation unit including the parameters of the separation process in the interior of the distillation column system 12 for nitrogen-oxygen separation are controlled by means of a central process control system (which is not shown) which is conducted by an automatic load change system.
  • a central process control system which is not shown
  • the valves 8 and 30 are activated which determine the rate and pressure of the internal compression air 22 , the valve 24 for establishing the rate of the turbine air 25 , the pump 14 for establishing the current rate of the oxygen product and valve 18 for fine adjustment of the product pressure to the take-off pressure.
  • the process control system can also intermittently close valve 18 and blow off the gaseous pressurized product into the atmosphere via the line 28 and the valve 29 .
  • FIG. 2 in the upper part, shows an example of a time course of the take-off pressure PA and the internal compression pressure PIV qualitatively over a period of five hours plotted along the x axis.
  • the lower part of the diagram of FIG. 2 is the time course of the rate which is delivered by the gas pressure reservoir to the consumers (continuous line).
  • a continuous line shows the course of the take-off pressure PA in the pressure reservoir or in the product pipeline of the gas pressure reservoir (the “pressure of the gas pressure reservoir”).
  • the take-off pressure PA can range within the range of variation of the gas pressure reservoir pressure between a minimum operating pressure (min) and a maximum operating pressure (max).
  • min minimum operating pressure
  • max maximum operating pressure
  • the internal compression pressure PIV the “elevated pressure” shown as a dashed line at the top follows the course of the take-off pressure PA in principle at some distance and with delay.
  • the difference PIV ⁇ PA is less than one third of the range of variation of the pressure of the gas pressure reservoir.
  • the internal compression pressure PIV cannot be changed as rapidly as desired, so that short-term blow off of product can also occur with the process according to the invention (see dashed line at the bottom in FIG. 2 ).
  • the blow-off rate can be kept low, however, by the invention.
  • the minimum operating pressure (min) is 20 bar and the maximum operating pressure is 35 bar, the difference PIV ⁇ PA is below 2 bar, preferably in the range between 0.5 and 1 bar.
  • the invention may be applied to any other internal compression process, in particular to those having differing cold generation having one or more turbines, which blow air into the high-pressure column and/or the low-pressure column or expand a nitrogen-enriched fraction from one of the separation columns of the distillation column system 12 .
  • the closed-loop control according to the invention can be further refined by evaluating information on the future consumption rates of the consumers V 1 to Vn and obtaining therefrom a prediction of future values of the take-off pressure, for example according to the method described in EP 1542102 A1.
  • the load change system can then move early the state of the air fractionation unit in a direction which corresponds to the internal compression pressure PIV required in the future. In this manner, a still better adjustment of the course of the internal compression pressure to the take-off pressure can be achieved, which contributes significantly to avoiding occasional blow-off of product.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)
US11/735,171 2006-04-13 2007-04-13 Process and apparatus for generating a pressurized product by low-temperature air fractionation Abandoned US20080047298A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06007760A EP1845323A1 (de) 2006-04-13 2006-04-13 Verfahren und Vorrichtung zur Erzeugung eines Druckprodukts durch Tieftemperatur-Luftzerlegung
EP06007760.9 2006-04-13

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US20080047298A1 true US20080047298A1 (en) 2008-02-28

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WO2018005768A1 (en) * 2016-06-30 2018-01-04 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Method for the production of air gases by the cryogenic separation of air
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US20180003434A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour I'etude Et I'exploitation Des Procedes Georges Claude Apparatus for the production of air gases by the cryogenic separation of air
WO2018005719A1 (en) * 2016-06-30 2018-01-04 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Method and apparatus for the production of air gases by the cryogenic separation of air with variable liquid production and power usage
US20180003437A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for operating an air separation plant
EP3699535A1 (de) * 2019-02-19 2020-08-26 Linde GmbH Verfahren und luftzerlegungsanlage zur variablen bereitstellung eines gasförmigen, druckbeaufschlagten luftprodukts
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US10161676B2 (en) * 2014-04-15 2018-12-25 Linde Aktiengesellschaft Process and apparatus for the low-temperature fractionation of air
US20170038140A1 (en) * 2014-04-15 2017-02-09 Linde Aktiengesellschaft Process and apparatus for the low-temperature fractionation of air
CN109564061A (zh) * 2016-06-30 2019-04-02 乔治洛德方法研究和开发液化空气有限公司 用于通过低温分离空气以可变液体产量和功率使用来产生空气气体的方法和设备
US10260801B2 (en) * 2016-06-30 2019-04-16 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes George Claude Method for operating an air separation plant
US20180003434A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour I'etude Et I'exploitation Des Procedes Georges Claude Apparatus for the production of air gases by the cryogenic separation of air
US20180003435A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Apparatus for operating an air separation plant
WO2018005719A1 (en) * 2016-06-30 2018-01-04 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Method and apparatus for the production of air gases by the cryogenic separation of air with variable liquid production and power usage
US20180003433A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the production of air gases by the cryogenic separation of air
US20180003437A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for operating an air separation plant
WO2018005768A1 (en) * 2016-06-30 2018-01-04 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Method for the production of air gases by the cryogenic separation of air
WO2018005787A1 (en) * 2016-06-30 2018-01-04 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Method and apparatus for operating an air separation plant
US20180003432A1 (en) * 2016-06-30 2018-01-04 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Apparatus for the production of air gases by the cryogenic separation of air with variable liquid production and power usage
US10260802B2 (en) * 2016-06-30 2019-04-16 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Apparatus for operating an air separation plant
US10267561B2 (en) * 2016-06-30 2019-04-23 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Apparatus for the production of air gases by the cryogenic separation of air
US10281207B2 (en) * 2016-06-30 2019-05-07 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the production of air gases by the cryogenic separation of air with variable liquid production and power usage
US10281206B2 (en) * 2016-06-30 2019-05-07 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Apparatus for the production of air gases by the cryogenic separation of air with variable liquid production and power usage
US10302356B2 (en) * 2016-06-30 2019-05-28 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the production of air gases by the cryogenic separation of air
RU2748320C2 (ru) * 2016-06-30 2021-05-24 Л'Эр Ликид Сосьете Аноним Пур Л'Этюд Э Л'Эксплуатасьон Де Проседе Жорж Клод Способ и устройство для получения воздушных газов путем криогенного разделения воздуха с помощью изменяемых выхода сжиженных продуктов и потребления электроэнергии
RU2741174C2 (ru) * 2016-06-30 2021-01-22 Л'Эр Ликид, Сосьете Аноним Пур Л'Этюд Э Л'Эксплуатасьон Де Проседе Жорж Клод Способ получения воздушных газов путем криогенного разделения воздуха
EP3699534A1 (de) * 2019-02-19 2020-08-26 Linde GmbH Verfahren und luftzerlegungsanlage zur variablen bereitstellung eines gasförmigen, druckbeaufschlagten luftprodukts
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TW200834025A (en) 2008-08-16

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