EP2258814A1 - Process for processing fischer-tropsch off-gas - Google Patents
Process for processing fischer-tropsch off-gas Download PDFInfo
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- EP2258814A1 EP2258814A1 EP09161901A EP09161901A EP2258814A1 EP 2258814 A1 EP2258814 A1 EP 2258814A1 EP 09161901 A EP09161901 A EP 09161901A EP 09161901 A EP09161901 A EP 09161901A EP 2258814 A1 EP2258814 A1 EP 2258814A1
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2/00—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon
- C10G2/30—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen
Definitions
- the present invention pertains to a process for processing Fischer-Tropsch off-gas.
- the Fischer-Tropsch process can be used for the conversion of hydrocarbonaceous feed stocks into normally liquid and/or solid hydrocarbons (0 °C, 1 bar).
- the feed stock e.g. natural gas, associated gas, coal-bed methane, residual oil fractions, biomass and/or coal
- the feed stock is converted in a first step into a mixture of hydrogen and carbon monoxide. This mixture is often referred to as synthesis gas or syngas.
- the synthesis gas is fed into a reactor where it is converted over a suitable catalyst at elevated temperature and pressure into paraffinic compounds ranging from methane to high molecular weight modules comprising up to 200 carbon atoms, or, under particular circumstances, even more.
- hydrocarbon products manufactured in the Fischer-Tropsch process are processed into different fractions, for example, a liquid hydrocarbon stream comprising mainly C 3 + hydrocarbons, and a gaseous hydrocarbon stream which comprises carbon monoxide, unconverted methane, and lower hydrocarbons.
- the gaseous hydrocarbon stream is generally at high temperature and pressure and contains combustible components. It can thus serve as a source for generating energy.
- EP1004561 describes a process for producing normally liquid hydrocarbons comprising the steps of manufacturing syngas by partial oxidation of hydrocarbonaceous feeds at elevated temperature and pressure, catalytically converting the syngas into, int. al., normally liquid hydrocarbons and normally gaseous hydrocarbons, and expanding and/or combusting at least part of the normally gaseous hydrocarbons, and any unconverted syngas and/or hydrocarbonaceous feeds, to provide power for compersing the hydrocarbonaceous feed used in the syngas manufacture.
- WO99/15483 describes a process for producing normally liquid hydrocarbons comprising the steps of manufacturing syngas by partial oxidation of hydrocarbonaceous feeds using pressurised oxygen, quenching and/or cooling the syngas with water recycled from further on in the process, catalytically converting the syngas into normally liquid hydrocarbons, normally gaseous hydrocarbons and water, recycling the water to the syngas manufacturing step, and expanding and/or combusting at least part of the normally gaseous hydrocarbons, and any unconverted syngas and/or hydrocarbonaceous feeds, to provide power for compressing oxygen used in the syngas manufacture.
- NL7413678 describes a process for producing normally liquid hydrocarbons comprising the steps of manufacturing syngas by partial oxidation of hydrocarbonaceous feeds cooling the syngas, removing solid particles and sulphur compounds from the gas, and catalytically converting the syngas into normally liquid hydrocarbons, normally gaseous hydrocarbons and water.
- the product from the synthesis is cooled down at a pressure in the range of 20-40 ata to a temperature of -30 to -70 °C, and may then be separated into a liquid containing C 3 + hydrocarbons and a gas containing unconverted hydrogen, carbon monoxide, nitrogen and C 1 -C 2 hydrocarbons.
- the gas is expanded in a back-pressure turbine, preferably after heating to a temperature ranging from -20 to -10 °C whereupon it cools to a temperature ranging from -50 to - 70 °C. It is indicated that the back pressure turbine may be used to generate energy that can be used in the system.
- the present invention provides such a process.
- the present invention pertains to a process for processing Fischer-Tropsch off-gas which comprises the steps of
- Fischer-Tropsch off-gas as it originates from the Fischer-Tropsh process comprises hydrogen, unconverted carbon monoxide, carbon dioxide, nitrogen, C 1 -C 2 hydrocarbons, and C 3 + hydrocarbons. As it is derived from the Fischer-Tropsch process it generally is at a temperature of in the range of 40-100 °C, more in particular in the range of 50-70 °C and at a pressure of 40-80 bar, more in particular in the range of 50-70 bar.
- Suitable pretreatment steps include removal of hydrogen and/or carbon dioxide.
- the gas as it enters the process according to the invention generally is at a temperature in the range of 20-150 °C, in particular 40-100 °C, more in particular in the range of 50-70 °C and at a pressure of 15-80 bar, in particular 40-80 bar, more in particular in the range of 50-70 bar.
- the Fischer-Tropsch off-gas as it enters the process according to the invention comprises carbon monoxide, nitrogen, C 1 -C 2 hydrocarbons, and C 3 + hydrocarbons.
- the C 3 + hydrocarbons are present in an amount of at least 0.5 mol%, more in particular in an amount of at least 0.8 mol%.
- the C3+ hydrocarbons are present in an amount up to 5 mol%, more in particular in an amount up to 4 mol%.
- the C 3 + hydrocarbons are C 3 -C 6 saturated and unsaturated hydrocarbons.
- the word hydrocarbons also encompasses oxygenates, such as alcohols.
- the Fischer-Tropsch off-gas is provided to an expander.
- an expander a high-pressure gas is expanded while producing work.
- the work is used to generate power in a generator.
- Expanders are known in the art. They are used, e.g., as sources of refrigeration in industrial processes such as the extraction of ethane and natural gas liquids (NGLs) from natural gas, the liquefaction of gases (and other low-temperature processes by driving a compressor.
- a well known expander is a turboexpander, also referred to as a turbo-expander or an expansion turbine. It is a centrifugal or axial flow turbine through which a high pressure gas is expanded to produce work that is often used to drive a compressor. It is within the scope of the skilled person to select and apply a suitable expander.
- Another suitable type of expander is a twister, also known in the art.
- the gas cools down to a point in temperature and pressure which is below the condensation point of the C 3 + fraction in the composition, and a liquid condensate is formed which comprises the C 3 + fraction.
- the process is controlled by the desired end pressure to be achieved in the expander, which is in turn controlled by the desired down-stream processing for the gaseous product stream coming from the expander.
- the temperature attained in the expander is a function of the starting temperature of the off-gas as it enters the expander and the pressure reduction achieved in the expander.
- the pressure of the gas as it leaves the expander is at least a factor of 2 lower than the pressure of the gas as it enters the expander.
- the pressure of the gas as it leaves the expander may be a factor 2.5 lower than the pressure of the gas as it enters the expander, or a factor of 3 lower.
- the gas as it leaves the expander prefferably be at a pressure in the range of 1-10 bar, in particular 3-8 bar.
- the temperature of the gas is reduced to a value in the range of -100 to - 20 °C.
- the generation of low-temperature cold by the expander is an additional advantage of the process according to the invention. For example, it can be used too cool process streams of processes carried out in the vicinity of the process according to the invention.
- the gas as it enters the expander is at a temperature in the range of 20-150 °C, in particular 40-100 °C, more in particular in the range of 50-70 °C and at a pressure in the range of 15-80 bar, in particular 40-80 bar, more in particular in the range of 50-70 bar and the gas as it leaves the expander is at a temperature in the range -100 to -20 °C, more in particular in the range of -80 to -40 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- the gas as it enters the expander is at a temperature in the range of 20-150 °C, in particular 20-80 °C, more in particular in the range of 40-60°C and at a pressure in the range of 15-45 bar, more in particular in the range of 20-38 bar and the gas as it leaves the expander is at a temperature in the range -100 to -20 °C, more in particular in the range of -70 to -30 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- the gas as it enters the expander is at a temperature in the range of 100-150 °C, more in particular in the range of 110-130 °C and at a pressure in the range of 40-80 bar, more in particular in the range of 50-70 bar and the gas as it leaves the expander is at a temperature in the range -60 to -10 °C, more in particular in the range of -40 to -20 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- the gas as it enters the expander is at a temperature in the range of 50-90 °C, more in particular in the range of 60-80 °C and at a pressure in the range of 15-45 bar, more in particular in the range of 20-38 bar and the gas as it leaves the expander is at a temperature in the range -60 to -10 °C, more in particular in the range of -45 to -25 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- liquid condensate is formed.
- the amount and composition of the condensate formed depends on the composition of the Fischer-Tropsch off-gas and on the conditions at which the expander is operated.
- the process according to the invention aims at forming a condensate comprising a substantial amount of C 3 + hydrocarbons.
- the condensate contains more than 50 wt% of C 3 + hydrocarbons, in particular more than 70 wt% of C 3 + hydrocarbons, still more in particular more than 80 wt% of C 3 + hydrocarbons, still more in particular more than 90 wt%, calculated on the total weight of the condensate formed.
- the condensate may also contain one or more of C 2 hydrocarbons, C 1 hydrocarbons, and carbon dioxide.
- the condensate is withdrawn from the expander. It may, optionally after removal of carbon dioxide, be processed further by combining it with the liquid effluent from the Fischer-Tropsch reactor, or by combining it with other refinery steams with a comparable composition.
- the condensate contains a substantial amount of C 3 + hydrocarbons as specified above, in particular where it contains more than 70 wt% of C 3 + hydrocarbons, more than 80 wt% of C 3 + hydrocarbons, or even more than 90 wt% of C 3 + hydrocarbons
- the condensate can, for example, be processed by combining it with other hydrocarbon streams with the same composition
- the condensate is provided to the LPG pool.
- the condensate contains less than 50 wt% of C 3 + hydrocarbons, it may be necessary to subject the condensate to a separation step to separate the C 3 + fraction from the lower-boiling components.
- the C 3 + fraction can then be processed as described above.
- the condensate may contain water.
- an expander is used to remove water from the gas stream while generating energy.
- the gaseous effluent is also withdrawn from the expander. It may be processed in a number of different ways.
- the gaseous effluent from the expander is fed through a heat exchanger. Feeding the effluent to a heat exchanger is advantageous for two reasons. In the first place, it allows heating of the gaseous effluent to a temperature in a range suitable for further processing. At the same time, it can be used to cool down other streams.
- the gas as it leaves the expander is at a pressure of 1-10 bar, in particular 3-8 bar, and is provided to a heat exchanger, where the temperature of the gas is increased to a value in the range of 25-60 °C, in particular to a value in the range of 40-50 °C.
- the process according to the invention comprises the step of splitting the Fischer-Tropsch off-gas stream into at least two streams, wherein a first stream is brought to a pressure in the range of 1-10 bar, in particular 3-8 bar, and a temperature in the range of 25-60 °C, in particular in the range of 40-50 °C, and a second stream is brought to a pressure in the range of 10-50 bar, in particular 20-40 bar, and a temperature in the range of 25-100 °C.
- This embodiment allows the production of both high-pressure fuel gas and low-pressure fuel gas.
- high-pressure fuel gas is gas at a pressure in the range of more than 10 bar to 50 bar, more in particular in the range of 20-40 bar, and a temperature in the range of 25-100 °C.
- the temperature is 26-60 °C, in particular 40-50 °C.
- the temperature is 50-100 °C, in particular 60-80 °C.
- the gas generally is at a temperature at least 20 °C above its saturation temperature.
- low-pressure fuel gas is gas at a pressure of 1-10 bar, in particular 3-8 bar, and a where the temperature of the gas is increased to a value in the range of 25-60 °C, in particular to a value in the range of 40-50 °C.
- the gas generally is at a temperature at least 20 °C above its saturation temperature.
- HPFG may, for example, be provided to a gas turbine generator (GTG).
- GTG gas turbine generator
- LPFG may, for example, be provided to a furnace and/or boiler, e.g., a steam-methane reformer furnace (SMR), or a high-pressure steam boiler combined with a superheater.
- SMR steam-methane reformer furnace
- the Fischer-Tropsch off-gas stream is divided into two streams, wherein one stream is subjected to an expansion step in an expander unit to a temperature and pressure which is such that the gas is below it condensation point, resulting in the formation of liquid condensate.
- the Fischer-Tropsch off-gas is provided to a pre-heater before being provided to the expansion step.
- a pre-heater By increasing the temperature of the Fischer-Tropsch step before the expansion step, more energy will be generated in the expansion step.
- the heat provided in the pre-heater may be low-level heat generated by other processes at the location where the process according to the invention is carried out.
- the temperature of the gas is increased to a value in the range of 101-150 °C, in particular 110-140 °C.
- expanders may also be incorporated which do not generate condensate.
- There expanders can, for example, be used to decrease the pressure of the Fischer-Tropsch off-gas to a value of more than 10 to 50 bar, in particular to 20-40 bar.
- the temperature of the expanded gas may be in the range of 0-80 °C. If so desired, the thus expanded gas may be provided to a heat-exchanger where it is heated to a temperature which makes it suitable for use as HPFG.
- a Fischer-Tropsch off-gas is provided through line 1 to an expander 2.
- expander 2 the gas expands while generating energy.
- the expander is coupled to a generator (not shown).
- the effluent from the expander is fed to a heat exchanger 4, where its temperature is increased.
- the effluent from the heat exchanger, which is HPFG is withdrawn through line 5.
- Part of the effluent say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off through line 7, depressurised in valve 9, to form LPFG which may be processed in processing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater.
- processing unit 6 which is, for example, a GTG.
- Table 1 temperatures and pressures of gas streams in Figure 1.
- general T (°C) pref. T (°C) FT off gas (1) 20-80 40-80 20-150 40-100 50-70 50-70 expanded gas (3) 10-50 20-40 0-20 5-15 heat-exchanged gas (HPFG) (5) 10-50 20-40 25-60 40-50 depressurised gas (LPFG) (9) 1-10 3-8 25-60 40-50
- the temperature attained in expander 2 is too high for a condensate to be formed. This process is thus not in accordance with the present invention.
- Figure 2 illustrates one embodiment of a process according to the invention.
- Fischer-Tropsch off-gas is provided through line 1.
- Part of the gas say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off through line 11.
- the remainder of the Fischer-Tropsch off-gas is provided to an expander 2.
- expander 2 the gas expands while generating energy.
- the expander is coupled to a generator (not shown).
- the effluent from the expander is fed to a heat exchanger 4, where its temperature is increased.
- the effluent from the heat exchanger, which is HPFG is withdrawn through line 5 and fed to processing unit 6, which is, for example, a GTG.
- the part of the Fischer-Tropsch off-gas withdrawn through line 11 is fed to an expander 12.
- expander 12 the gas expands while generating energy.
- the expander is coupled to a generator (not shown). This generator may be the same as the generator connected to expander 2, or a separate generator may be provided.
- a liquid condensate is formed, which is withdrawn through line 14.
- the gaseous effluent from the expander is withdrawn through line 13 and fed to a heat exchanger 15, where its temperature is increased.
- the effluent from the heat exchanger 15, which is LPFG may provided through line 16 to processing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater.
- Table 2 temperatures and pressures of gas streams in Figure 2.
- liquid condensate is formed in expander 12 but not in expander 2.
- expander 2 and heat exchanger 4 are replaced with a valve, where the gas is depressurised to form HPFG, which is then provided to processing unit 6, which is, for example, a GTG.
- FIG. 3 illustrates a further embodiment of the present invention.
- a Fischer-Tropsch off-gas is provided through line 1 to an expander 2.
- expander 2 the gas expands while generating energy.
- the expander is coupled to a generator (not shown).
- the effluent from the expander is fed to a heat exchanger 4, where its temperature is increased.
- the effluent from the heat exchanger, which is HPFG is withdrawn through line 5.
- Part of the effluent say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off through line 7.
- the remainder of the HPFG in line 5 is fed to processing unit 6, which is, for example, a GTG.
- the part of the Fischer-Tropsch off-gas withdrawn through line 7 is fed to an expander 17.
- expander 17 the gas expands while generating energy.
- the expander is coupled to a generator (not shown). This generator may be the same as the generator connected to expander 2, or a separate generator may be provided.
- a liquid condensate is formed, which is withdrawn through line 18.
- the gaseous effluent from expander 17 is withdrawn through line 19 and fed to a heat exchanger 20, where its temperature is increased.
- the effluent from the heat exchanger 20, which is LPFG may provided through line 21 to processing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater.
- Table 3 temperatures and pressures of gas streams in Figure 3.
- liquid condensate is formed in expander 17 but not in expander 2.
- additional heat is provided to the gas before in is fed to the expander. This allows the conversion of low-level waste heat to energy. For example, it may be attractive to pre-heat the Fischer-Tropsch off gas from a temperature in the range of 40-100 °C, in particular 50-70 °C, to a temperature in the range of 101-150 °C, in particular in the range of 110-140 °C.
- This embodiment can be integrated in the process according to the invention in a number of ways. A few of these are elucidated in figures 4-6 .
- FIG. 4 illustrates a further embodiment of a process according to the invention.
- Fischer-Tropsch off-gas is provided through line 1.
- Part of the gas say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off through line 24.
- the remainder of the Fischer-Tropsch off-gas is provided to valve 22, where it depressurised and cooled down.
- the effluent from valve 22, which is HPFG, may provided through line 16 to processing unit 6, which is, for example, a GTG.
- the part of the Fischer-Tropsch off-gas withdrawn through line 24 is fed to a pre-heater 25, where the temperature of the gas is increased.
- the effluent from the pre-heater 25 is provided through line 26 to an expander 27.
- expander 27 the gas expands while generating energy.
- the expander is coupled to a generator (not shown).
- a liquid condensate is formed, which is withdrawn through line 28.
- the gaseous effluent from the expander is withdrawn through line 29 and fed to a heat exchanger 30, where its temperature is increased.
- the effluent from heat exchanger 30, which is LPFG is withdrawn through line 31 and fed to processing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater.
- Table 4 temperatures and pressures of gas streams in Figure 4.
- liquid condensate is formed in expander 27.
- pre-heater 25 makes for an increased amount of energy generated in expander 27.
- Fischer-Tropsch off-gas is provided through line 1. It is fed to pre-heater 32, where its temperature is increased. The effluent from pre-heater 32 is withdrawn through line 33. Part of the gas, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off through line 36. The remainder of the gas is provided to expander 34. In expander 34, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent from expander 34, which is HPFG, is withdrawn through line 35 and fed to processing unit 6, which is, for example, a GTG. The part of the gas withdrawn through line 36 is fed to an expander 37.
- processing unit 6 which is, for example, a GTG.
- expander 37 the gas expands while generating energy.
- the expander is coupled to a generator (not shown). This generator may be the same as the generator connected to expander 34, or a separate generator may be provided.
- a liquid condensate is formed, which is withdrawn through line 38.
- the gaseous effluent from the expander is withdrawn through line 39 and fed to a heat exchanger 40, where its temperature is increased.
- the effluent from the heat exchanger 40 which is LPFG, may provided through line 41 to processing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater.
- Table 5 temperatures and pressures of gas streams in Figure 5.
- liquid condensate is formed in expander 37 but not in expander 34.
- FIG. 6 A further embodiment of the present invention where a pre-heater is used in combination with an expander is illustrated in Figure 6 .
- Fischer-Tropsch off-gas is provided through line 1. It is fed to pre-heater 32, where its temperature is increased. The effluent from pre-heater 32 is withdrawn through line 33, and led to expander 42. In expander 42, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent from expander 42 is withdrawn through line 43. Part of the gas, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off through line 44. The remainder of the gas, which is HPFG is fed to processing unit 6, which is, for example, a GTG.
- processing unit 6 which is, for example, a GTG.
- the part of the gas withdrawn through line 44 is fed to an expander 45.
- expander 45 the gas expands while generating energy.
- the expander is coupled to a generator (not shown). This generator may be the same as the generator connected to expander 42, or a separate generator may be provided.
- a liquid condensate is formed, which is withdrawn through line 46.
- the gaseous effluent from the expander is withdrawn through line 47 and fed to a heat exchanger 48, where its temperature is increased.
- the effluent from the heat exchanger 48 which is LPFG, may provided through line 49 to processing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater.
- Table 6 temperatures and pressures of gas streams in Figure 6.
- liquid condensate is formed in expander 45 but not in expander 42.
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Abstract
The present invention pertains to a process for processing Fischer-Tropsch off-gas which comprises the steps of: a) subjecting a Fischer-Tropsch off-gas to an expansion step in an expander unit to a temperature and pressure which is such that the gas is below it condensation point, resulting in the formation of liquid condensate; b) removing the liquid condensate from the expander; c) removing the gaseous effluent from the expander. A number of integrated processes are also described and claimed.
Description
- The present invention pertains to a process for processing Fischer-Tropsch off-gas.
- The Fischer-Tropsch process can be used for the conversion of hydrocarbonaceous feed stocks into normally liquid and/or solid hydrocarbons (0 °C, 1 bar). The feed stock (e.g. natural gas, associated gas, coal-bed methane, residual oil fractions, biomass and/or coal) is converted in a first step into a mixture of hydrogen and carbon monoxide. This mixture is often referred to as synthesis gas or syngas. The synthesis gas is fed into a reactor where it is converted over a suitable catalyst at elevated temperature and pressure into paraffinic compounds ranging from methane to high molecular weight modules comprising up to 200 carbon atoms, or, under particular circumstances, even more.
- The hydrocarbon products manufactured in the Fischer-Tropsch process are processed into different fractions, for example, a liquid hydrocarbon stream comprising mainly C3+ hydrocarbons, and a gaseous hydrocarbon stream which comprises carbon monoxide, unconverted methane, and lower hydrocarbons.
- The gaseous hydrocarbon stream is generally at high temperature and pressure and contains combustible components. It can thus serve as a source for generating energy.
-
EP1004561 describes a process for producing normally liquid hydrocarbons comprising the steps of manufacturing syngas by partial oxidation of hydrocarbonaceous feeds at elevated temperature and pressure, catalytically converting the syngas into, int. al., normally liquid hydrocarbons and normally gaseous hydrocarbons, and expanding and/or combusting at least part of the normally gaseous hydrocarbons, and any unconverted syngas and/or hydrocarbonaceous feeds, to provide power for compersing the hydrocarbonaceous feed used in the syngas manufacture. -
WO99/15483 -
NL7413678 - While the processes of the above references contain attractive features to generate and re-use energy, there is still need for an integrated process to process the gaseous products resulting from the Fischer-Tropsch process which combines the generation of energy with further attractive features.
- The present invention provides such a process.
- The present invention pertains to a process for processing Fischer-Tropsch off-gas which comprises the steps of
- a) subjecting a Fischer-Tropsch off-gas to an expansion step in an expander to a temperature and pressure which is such that the gas is below it condenstation point, resulting in the formation of liquid condensate;
- b) removing the liquid condensate from the expander;
- c) removing the gaseous effluent from the expander.
- In the process according to the invention, the generation of energy through using an expander is combined with the recovery of condensate, which is in itself a valuable product.
- A number of embodiments of the invention are described in detail and by way of example only with reference to the accompanying drawings.
-
Figure 1 illustrates a process which is not according to the invention. -
Figure 2 illustrates an embodiment of the process according to the invention. -
Figure 3 illustrates a further embodiment of the process according to the invention. -
Figure 4 illustrates a further embodiment of the process according to the invention. -
Figure 5 illustrates a further embodiment of the process according to the invention. -
Figure 6 illustrates a further embodiment of the process according to the invention. - Fischer-Tropsch off-gas as it originates from the Fischer-Tropsh process comprises hydrogen, unconverted carbon monoxide, carbon dioxide, nitrogen, C1-C2 hydrocarbons, and C3+ hydrocarbons. As it is derived from the Fischer-Tropsch process it generally is at a temperature of in the range of 40-100 °C, more in particular in the range of 50-70 °C and at a pressure of 40-80 bar, more in particular in the range of 50-70 bar.
- Before the Fischer-Tropsch off-gas is provided to the process according to the invention, it may be subjected to one or more pretreatment steps. Suitable pretreatment steps include removal of hydrogen and/or carbon dioxide.
- The gas as it enters the process according to the invention generally is at a temperature in the range of 20-150 °C, in particular 40-100 °C, more in particular in the range of 50-70 °C and at a pressure of 15-80 bar, in particular 40-80 bar, more in particular in the range of 50-70 bar.
- The Fischer-Tropsch off-gas as it enters the process according to the invention comprises carbon monoxide, nitrogen, C1-C2 hydrocarbons, and C3+ hydrocarbons. In general, the C3+ hydrocarbons are present in an amount of at least 0.5 mol%, more in particular in an amount of at least 0.8 mol%. In general, the C3+ hydrocarbons are present in an amount up to 5 mol%, more in particular in an amount up to 4 mol%. In general the C3+ hydrocarbons are C3-C6 saturated and unsaturated hydrocarbons. In the context of the present specification, the word hydrocarbons also encompasses oxygenates, such as alcohols.
- In the first step of the process according to the invention the Fischer-Tropsch off-gas is provided to an expander. In an expander, a high-pressure gas is expanded while producing work. The work is used to generate power in a generator. Expanders are known in the art. They are used, e.g., as sources of refrigeration in industrial processes such as the extraction of ethane and natural gas liquids (NGLs) from natural gas, the liquefaction of gases (and other low-temperature processes by driving a compressor. A well known expander is a turboexpander, also referred to as a turbo-expander or an expansion turbine. It is a centrifugal or axial flow turbine through which a high pressure gas is expanded to produce work that is often used to drive a compressor. It is within the scope of the skilled person to select and apply a suitable expander. Another suitable type of expander is a twister, also known in the art.
- In the expander, the gas cools down to a point in temperature and pressure which is below the condensation point of the C3+ fraction in the composition, and a liquid condensate is formed which comprises the C3+ fraction.
- The process is controlled by the desired end pressure to be achieved in the expander, which is in turn controlled by the desired down-stream processing for the gaseous product stream coming from the expander. The temperature attained in the expander is a function of the starting temperature of the off-gas as it enters the expander and the pressure reduction achieved in the expander.
- In one embodiment, the pressure of the gas as it leaves the expander is at least a factor of 2 lower than the pressure of the gas as it enters the expander. Depending on the exact manner in which the process is carried out, the pressure of the gas as it leaves the expander may be a factor 2.5 lower than the pressure of the gas as it enters the expander, or a factor of 3 lower.
- It is preferred for the gas as it leaves the expander to be at a pressure in the range of 1-10 bar, in particular 3-8 bar.
- In one embodiment, in the expander the temperature of the gas is reduced to a value in the range of -100 to - 20 °C. The generation of low-temperature cold by the expander is an additional advantage of the process according to the invention. For example, it can be used too cool process streams of processes carried out in the vicinity of the process according to the invention.
- In one embodiment, the gas as it enters the expander is at a temperature in the range of 20-150 °C, in particular 40-100 °C, more in particular in the range of 50-70 °C and at a pressure in the range of 15-80 bar, in particular 40-80 bar, more in particular in the range of 50-70 bar and the gas as it leaves the expander is at a temperature in the range -100 to -20 °C, more in particular in the range of -80 to -40 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- In another embodiment the gas as it enters the expander is at a temperature in the range of 20-150 °C, in particular 20-80 °C, more in particular in the range of 40-60°C and at a pressure in the range of 15-45 bar, more in particular in the range of 20-38 bar and the gas as it leaves the expander is at a temperature in the range -100 to -20 °C, more in particular in the range of -70 to -30 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- In a further embodiment the gas as it enters the expander is at a temperature in the range of 100-150 °C, more in particular in the range of 110-130 °C and at a pressure in the range of 40-80 bar, more in particular in the range of 50-70 bar and the gas as it leaves the expander is at a temperature in the range -60 to -10 °C, more in particular in the range of -40 to -20 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- In a further embodiment the gas as it enters the expander is at a temperature in the range of 50-90 °C, more in particular in the range of 60-80 °C and at a pressure in the range of 15-45 bar, more in particular in the range of 20-38 bar and the gas as it leaves the expander is at a temperature in the range -60 to -10 °C, more in particular in the range of -45 to -25 °C and at a pressure in the range of 1-10 bar, more in particular in the range of 3-8 bar.
- In the expander, liquid condensate is formed. The amount and composition of the condensate formed depends on the composition of the Fischer-Tropsch off-gas and on the conditions at which the expander is operated. The process according to the invention aims at forming a condensate comprising a substantial amount of C3+ hydrocarbons. In one embodiment, the condensate contains more than 50 wt% of C3+ hydrocarbons, in particular more than 70 wt% of C3+ hydrocarbons, still more in particular more than 80 wt% of C3+ hydrocarbons, still more in particular more than 90 wt%, calculated on the total weight of the condensate formed. Depending on the conditions, the condensate may also contain one or more of C2 hydrocarbons, C1 hydrocarbons, and carbon dioxide.
- The condensate is withdrawn from the expander. It may, optionally after removal of carbon dioxide, be processed further by combining it with the liquid effluent from the Fischer-Tropsch reactor, or by combining it with other refinery steams with a comparable composition.
- More in particular, where the condensate contains a substantial amount of C3+ hydrocarbons as specified above, in particular where it contains more than 70 wt% of C3+ hydrocarbons, more than 80 wt% of C3+ hydrocarbons, or even more than 90 wt% of C3+ hydrocarbons, the condensate can, for example, be processed by combining it with other hydrocarbon streams with the same composition In a preferred embodiment, the condensate is provided to the LPG pool.
- Where the condensate contains less than 50 wt% of C3+ hydrocarbons, it may be necessary to subject the condensate to a separation step to separate the C3+ fraction from the lower-boiling components. The C3+ fraction can then be processed as described above.
- Depending on operating conditions and gas composition, the condensate may contain water. In one embodiment of the present invention an expander is used to remove water from the gas stream while generating energy.
- The gaseous effluent is also withdrawn from the expander. It may be processed in a number of different ways. In one embodiment, the gaseous effluent from the expander is fed through a heat exchanger. Feeding the effluent to a heat exchanger is advantageous for two reasons. In the first place, it allows heating of the gaseous effluent to a temperature in a range suitable for further processing. At the same time, it can be used to cool down other streams.
- In one embodiment, the gas as it leaves the expander is at a pressure of 1-10 bar, in particular 3-8 bar, and is provided to a heat exchanger, where the temperature of the gas is increased to a value in the range of 25-60 °C, in particular to a value in the range of 40-50 °C.
- In one embodiment, the process according to the invention comprises the step of splitting the Fischer-Tropsch off-gas stream into at least two streams, wherein a first stream is brought to a pressure in the range of 1-10 bar, in particular 3-8 bar, and a temperature in the range of 25-60 °C, in particular in the range of 40-50 °C, and a second stream is brought to a pressure in the range of 10-50 bar, in particular 20-40 bar, and a temperature in the range of 25-100 °C. This embodiment allows the production of both high-pressure fuel gas and low-pressure fuel gas.
- In the present specification, high-pressure fuel gas (HPFG) is gas at a pressure in the range of more than 10 bar to 50 bar, more in particular in the range of 20-40 bar, and a temperature in the range of 25-100 °C. In one embodiment, the temperature is 26-60 °C, in particular 40-50 °C. In another embodiment, the temperature is 50-100 °C, in particular 60-80 °C. The gas generally is at a temperature at least 20 °C above its saturation temperature.
- In the present specification low-pressure fuel gas (LPFG) is gas at a pressure of 1-10 bar, in particular 3-8 bar, and a where the temperature of the gas is increased to a value in the range of 25-60 °C, in particular to a value in the range of 40-50 °C. The gas generally is at a temperature at least 20 °C above its saturation temperature.
- HPFG may, for example, be provided to a gas turbine generator (GTG). LPFG may, for example, be provided to a furnace and/or boiler, e.g., a steam-methane reformer furnace (SMR), or a high-pressure steam boiler combined with a superheater.
- In one embodiment the Fischer-Tropsch off-gas stream is divided into two streams, wherein one stream is subjected to an expansion step in an expander unit to a temperature and pressure which is such that the gas is below it condensation point, resulting in the formation of liquid condensate.
- In one embodiment of the present invention the Fischer-Tropsch off-gas is provided to a pre-heater before being provided to the expansion step. By increasing the temperature of the Fischer-Tropsch step before the expansion step, more energy will be generated in the expansion step. The heat provided in the pre-heater may be low-level heat generated by other processes at the location where the process according to the invention is carried out.
- In one embodiment, in the pre-heater the temperature of the gas is increased to a value in the range of 101-150 °C, in particular 110-140 °C.
- In the process according to the invention expanders may also be incorporated which do not generate condensate. There expanders can, for example, be used to decrease the pressure of the Fischer-Tropsch off-gas to a value of more than 10 to 50 bar, in particular to 20-40 bar. The temperature of the expanded gas may be in the range of 0-80 °C. If so desired, the thus expanded gas may be provided to a heat-exchanger where it is heated to a temperature which makes it suitable for use as HPFG.
- As will be evident to the skilled person, where one or more heat-exchangers or pre-heaters are used in the process according to the invention, these apparatus generally do not cause a substantial difference in pressure between the gas entering the apparatus and the gas leaving the apparatus. A pressure difference of less then 15% of the inlet pressure, in particular less than 10% of the inlet pressure, more in particular less than 5% of the inlet pressure is appropriate.
- Various embodiments of the process according to the invention will be illustrated below with reference to the attached figures. It is noted that the present invention should not be considered limited thereto or thereby.
- In the process of
Figure 1 , a Fischer-Tropsch off-gas is provided throughline 1 to anexpander 2. Inexpander 2, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent from the expander is fed to aheat exchanger 4, where its temperature is increased. The effluent from the heat exchanger, which is HPFG, is withdrawn throughline 5. Part of the effluent, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off throughline 7, depressurised invalve 9, to form LPFG which may be processed inprocessing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater. The remainder of the HPFG inline 5 is fed toprocessing unit 6, which is, for example, a GTG. - The following table summarises the general and preferred temperatures and pressures of the various gas streams.
Table 1: temperatures and pressures of gas streams in Figure 1. general pressure (bar) pref. pressure (bar) general T (°C) pref. T (°C) FT off gas (1) 20-80 40-80 20-150 40-100 50-70 50-70 expanded gas (3) 10-50 20-40 0-20 5-15 heat-exchanged gas (HPFG) (5) 10-50 20-40 25-60 40-50 depressurised gas (LPFG) (9) 1-10 3-8 25-60 40-50 - In this embodiment, the temperature attained in
expander 2 is too high for a condensate to be formed. This process is thus not in accordance with the present invention. -
Figure 2 illustrates one embodiment of a process according to the invention. In this embodiment, Fischer-Tropsch off-gas is provided throughline 1. Part of the gas, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off throughline 11. The remainder of the Fischer-Tropsch off-gas is provided to anexpander 2. Inexpander 2, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent from the expander is fed to aheat exchanger 4, where its temperature is increased. The effluent from the heat exchanger, which is HPFG, is withdrawn throughline 5 and fed toprocessing unit 6, which is, for example, a GTG. The part of the Fischer-Tropsch off-gas withdrawn throughline 11 is fed to anexpander 12. Inexpander 12, the gas expands while generating energy. The expander is coupled to a generator (not shown). This generator may be the same as the generator connected toexpander 2, or a separate generator may be provided. In expander 12 a liquid condensate is formed, which is withdrawn throughline 14. The gaseous effluent from the expander is withdrawn throughline 13 and fed to aheat exchanger 15, where its temperature is increased. The effluent from theheat exchanger 15, which is LPFG, may provided throughline 16 toprocessing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater. - The following table summarises the general and preferred temperatures and pressures of the various gas streams.
Table 2: temperatures and pressures of gas streams in Figure 2. general pressure (bar) pref. pressure (bar) general T (°C) pref. T (°C) FT off gas 20-80 40-80 20-150 40-100 (1) 50-70 50-70 expanded gas (3) 10-50 20-40 0-20 5-15 heat-exchanged gas (HPFG) (5) 10-50 20-40 25-60 40-50 expanded gas (13) 1-10 3-8 -100 - -20 -80 - -40 heat-exchanged gas (LPFG) (16) 1-10 3-8 25-60 40-50 - In this embodiment, liquid condensate is formed in
expander 12 but not inexpander 2. - In a variation of this process (not illustrated),
expander 2 andheat exchanger 4 are replaced with a valve, where the gas is depressurised to form HPFG, which is then provided toprocessing unit 6, which is, for example, a GTG. -
Figure 3 illustrates a further embodiment of the present invention. - In the process of
Figure 3 , a Fischer-Tropsch off-gas is provided throughline 1 to anexpander 2. Inexpander 2, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent from the expander is fed to aheat exchanger 4, where its temperature is increased. The effluent from the heat exchanger, which is HPFG, is withdrawn throughline 5. Part of the effluent, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off throughline 7. The remainder of the HPFG inline 5 is fed toprocessing unit 6, which is, for example, a GTG. - The part of the Fischer-Tropsch off-gas withdrawn through
line 7 is fed to anexpander 17. Inexpander 17, the gas expands while generating energy. The expander is coupled to a generator (not shown). This generator may be the same as the generator connected toexpander 2, or a separate generator may be provided. In expander 17 a liquid condensate is formed, which is withdrawn throughline 18. The gaseous effluent fromexpander 17 is withdrawn throughline 19 and fed to aheat exchanger 20, where its temperature is increased. The effluent from theheat exchanger 20, which is LPFG, may provided throughline 21 toprocessing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater. - The following table summarises the general and preferred temperatures and pressures of the various gas streams.
Table 3: temperatures and pressures of gas streams in Figure 3. general pressure (bar) pref. pressure (bar) general T (°C) pref. T (°C) FT off gas 20-80 40-80 20-150 40-100 (1) 50-70 50-70 expanded gas (3) 10-50 20-40 0-20 5-15 heat-exchanged gas (HPFG) (5) 10-50 20-40 25-60 40-50 expanded gas (19) 1-10 3-8 -100 - -20 -70 - -30 heat-exchanged gas (LPFG) (16) 1-10 3-8 25-60 40-50 - In this embodiment, liquid condensate is formed in
expander 17 but not inexpander 2. - In one embodiment, additional heat is provided to the gas before in is fed to the expander. This allows the conversion of low-level waste heat to energy. For example, it may be attractive to pre-heat the Fischer-Tropsch off gas from a temperature in the range of 40-100 °C, in particular 50-70 °C, to a temperature in the range of 101-150 °C, in particular in the range of 110-140 °C.
- This embodiment can be integrated in the process according to the invention in a number of ways. A few of these are elucidated in
figures 4-6 . -
Figure 4 illustrates a further embodiment of a process according to the invention. In this embodiment, Fischer-Tropsch off-gas is provided throughline 1. Part of the gas, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off throughline 24. The remainder of the Fischer-Tropsch off-gas is provided tovalve 22, where it depressurised and cooled down. The effluent fromvalve 22, which is HPFG, may provided throughline 16 toprocessing unit 6, which is, for example, a GTG. - The part of the Fischer-Tropsch off-gas withdrawn through
line 24 is fed to a pre-heater 25, where the temperature of the gas is increased. The effluent from the pre-heater 25 is provided throughline 26 to anexpander 27. Inexpander 27, the gas expands while generating energy. The expander is coupled to a generator (not shown). In expander 27 a liquid condensate is formed, which is withdrawn throughline 28. The gaseous effluent from the expander is withdrawn throughline 29 and fed to aheat exchanger 30, where its temperature is increased. The effluent fromheat exchanger 30, which is LPFG, is withdrawn throughline 31 and fed to processingunit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater. - The following table summarises the general and preferred temperatures and pressures of the various gas streams.
Table 4: temperatures and pressures of gas streams in Figure 4. general pressure (bar) pref. pressure (bar) general T (°C) pref. T (°C) FT off gas 20-80 40-80, 20-150 40-100 (1) 50-70 50-70 depressurised gas (HPFG) (23) 10-50 20-40 25-60 40-50 pre-heated gas (26) 40-80 50-70 101-150 110-140 expanded gas (29) 1-10 3-8 -50 - -10 -40 - -20 heat-exchanged gas (LPFG) (31) 1-10 3-8 25-60 40-50 - In this embodiment, liquid condensate is formed in
expander 27. The use ofpre-heater 25 makes for an increased amount of energy generated inexpander 27. - A further embodiment of an integrated process is presented in
Figure 5 . In this embodiment, Fischer-Tropsch off-gas is provided throughline 1. It is fed to pre-heater 32, where its temperature is increased. The effluent frompre-heater 32 is withdrawn throughline 33. Part of the gas, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off throughline 36. The remainder of the gas is provided toexpander 34. Inexpander 34, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent fromexpander 34, which is HPFG, is withdrawn throughline 35 and fed toprocessing unit 6, which is, for example, a GTG. The part of the gas withdrawn throughline 36 is fed to anexpander 37. Inexpander 37, the gas expands while generating energy. The expander is coupled to a generator (not shown). This generator may be the same as the generator connected to expander 34, or a separate generator may be provided. In expander 37 a liquid condensate is formed, which is withdrawn throughline 38. The gaseous effluent from the expander is withdrawn throughline 39 and fed to aheat exchanger 40, where its temperature is increased. The effluent from theheat exchanger 40, which is LPFG, may provided throughline 41 toprocessing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater. - The following table summarises the general and preferred temperatures and pressures of the various gas streams.
Table 5: temperatures and pressures of gas streams in Figure 5. general pressure (bar) pref. pressure (bar) general T (°C) pref. T (°C) FT off gas (1) 20-80 40-80 20-150 40-100 50-70 50-70 pre-heated gas (33) 40-80 50-70 101-150 110-140 expanded gas (HPFG) (35) 10-50 20-40 50-100 60-80 expanded gas (39) 1-10 3-8 -60 - -10 -40 - -20 heat-exchanged gas (LPFG) (41) 1-10 3-8 25-60 40-50 - In this embodiment, liquid condensate is formed in
expander 37 but not inexpander 34. - A further embodiment of the present invention where a pre-heater is used in combination with an expander is illustrated in
Figure 6 . In this embodiment, Fischer-Tropsch off-gas is provided throughline 1. It is fed to pre-heater 32, where its temperature is increased. The effluent frompre-heater 32 is withdrawn throughline 33, and led toexpander 42. Inexpander 42, the gas expands while generating energy. The expander is coupled to a generator (not shown). The effluent fromexpander 42 is withdrawn throughline 43. Part of the gas, say, between 10 and 90 vol%, in particular between 30 and 70 vol%, is separated off throughline 44. The remainder of the gas, which is HPFG is fed toprocessing unit 6, which is, for example, a GTG. The part of the gas withdrawn throughline 44 is fed to anexpander 45. Inexpander 45, the gas expands while generating energy. The expander is coupled to a generator (not shown). This generator may be the same as the generator connected to expander 42, or a separate generator may be provided. In expander 45 a liquid condensate is formed, which is withdrawn throughline 46. The gaseous effluent from the expander is withdrawn throughline 47 and fed to aheat exchanger 48, where its temperature is increased. The effluent from theheat exchanger 48, which is LPFG, may provided throughline 49 toprocessing unit 10, which is a furnace and/or boiler, for example a SMR or a high-pressure steam boiler combined with a superheater. - The following table summarises the general and preferred temperatures and pressures of the various gas streams.
Table 6: temperatures and pressures of gas streams in Figure 6. general pressure (bar) pref. pressure (bar) general T (°C) pref. T (°C) FT off gas 20-80 40-80 20-150 40-100 (1) 50-70 50-70 pre-heated gas (33) 40-80 50-70 101-150 110-140 expanded gas (HPFG) (43) 10-50 20-40 50-100 60-80 expanded gas (47) 1-10 3-8 -60 - -10 -40 - -20 heat-exchanged gas (LPFG) (49) 1-10 3-8 25-60 40-50 - In this embodiment, liquid condensate is formed in
expander 45 but not inexpander 42.
Claims (15)
- Process for processing Fischer-Tropsch off-gas which comprises the steps ofa) subjecting a Fischer-Tropsch off-gas to an expansion step in an expander unit to a temperature and pressure which is such that the gas is below it condensation point, resulting in the formation of liquid condensate;b) removing the liquid condensate from the expander;c) removing the gaseous effluent from the expander.
- Process according to claim 1, wherein the pressure of the gas as it leaves the expander is at least 20 bar below the pressure of the gas as it enters the expander.
- Process according to claim 1 or 2, wherein gas as it leaves the expander is at a pressure of 1-10 bar, in particular 3-8 bar.
- Process according to claim 4, wherein in the expander the temperature of the gas is reduced to a value in the range of -100 to -20 °C.
- Process according to any one of the preceding claims, wherein the gas as it leaves the expander is at a pressure of 1-10 bar, in particular 3-8 bar, and is provided to a heat exchanger, where the temperature of the gas is increased to a value in the range of 25-60 °C, in particular to a value in the range of 40-50 °C.
- Process according to claim 5, wherein the gas at a pressure of 1-10 bar, in particular 3-8 bar and a temperature in the range of 25-60 °C, in particular in the range of 40-50 °C is provided to a furnace and/or boiler, for example a steam methane reformer furnace or a high-pressure steam boiler combined with a superheater.
- Process according to any one of the preceding claims, which comprises the step of splitting the Fischer-Tropsch off-gas stream into at least two streams, wherein a first stream is brought to a pressure in the range of 1-10 bar, in particular 3-8 bar, and a temperature in the range of 25-60 °C, in particular in the range of 40-50 °C, and a second stream is brought to a pressure in the range of 10-50 bar, in particular 20-40 bar, and a temperature in the range of 25-100 °C.
- Process according to claim 7, wherein the Fischer-Tropsch off-gas stream is divided into at least two streams, wherein a stream is subjected to an expansion step in an expander unit to a temperature and pressure which is such that the gas is below it condensation point, resulting in the formation of liquid condensate.
- Process according to any one of the preceding claims wherein the Fischer-Tropsch off-gas is provided to a pre-heater before being provided to the expansion step.
- Process according to claim 9 wherein in the pre-heater the temperature of the gas is increased to a value in the range of 101-150°C, in particular 110-140°C.
- Process according to claim 1, comprising the steps of- providing Fischer-Tropsch off-gas;- separating the gas to form a first fraction and a second fraction;- providing the first fraction to an expander, where the gas expands while generating energy;- feeding the gaseous effluent from the expander to a heat exchanger where its temperature is increased;- providing the effluent from the heat exchanger, which is HPFG, to a processing unit;- providing the second fraction to an expander, where the gas expands while generating energy, under formation of a liquid condensate, which is withdrawn from the expander;- withdrawing the gaseous effluent from the expander, and providing it to a heat exchanger, where its temperature is increased;- providing the effluent from the heat exchanger, which is LPFG, to a processing unit, which is a furnace and/or boiler.
- Process according to claim 1, comprising the steps of- providing Fischer-Tropsch off-gas to an expander, where the gas expands while generating energy;- feeding the gaseous effluent from the expander to a heat exchanger where its temperature is increased;- separating the gas to form a first fraction and a second fraction;- providing the first fraction, which is HPFG, to a processing unit;- providing the second fraction to an expander, where the gas expands while generating energy under formation of a liquid condensate, which is withdrawn from the expander;- withdrawing the gaseous effluent from the expander, and providing it to a heat exchanger, where its temperature is increased;- providing the effluent from the heat exchanger, which is LPFG, to a processing unit, which is a furnace and/or boiler.
- Process according to claim 1 comprising the steps of- providing Fischer-Tropsch off-gas;- separating the gas to form a first fraction and a second fraction;- providing the first fraction to a valve, where it depressurised and cooled down;- providing the effluent from the valve, which is HPFG, to a processing unit;- providing the second fraction to a pre-heater, where the temperature of the gas is increased;- providing the effluent from the preheater to an expander where the gas expands while generating energy under formation of a liquid condensate, which is withdrawn from the expander;- withdrawing the gaseous effluent from the expander, and providing it to a heat exchanger, where its temperature is increased;- providing the effluent from the heat exchanger, which is LPFG, to a processing unit, which is a furnace and/or boiler.
- Process according to claim 1 comprising the steps of providing Fischer-Tropsch off-gas to a pre-heater, where its temperature is increased;- separating the effluent from the preheater to form a first fraction and a second fraction;- providing the first fraction to an expander where the gas expands while generating energy;- providing the effluent from the expander, which is HPFG, to a processing unit;- providing the second fraction to an expander where the gas expands while generating energy under formation of a liquid condensate, which is withdrawn from the expander;- withdrawing the gaseous effluent from the expander, and providing it to a heat exchanger, where its temperature is increased;- providing the effluent from the heat exchanger, which is LPFG, to a processing unit, which is a furnace and/or boiler.
- Process according to claim 1 comprising the steps of- providing Fischer-Tropsch off-gas to a pre-heater, where its temperature is increased;- providing the effluent from the preheater to an expander where the gas expands while generating energy;- separating the effluent from the expander to form a first fraction and a second fraction;- providing the second fraction to an expander where the gas expands while generating energy under formation of a liquid condensate, which is withdrawn from the expander;- withdrawing the gaseous effluent from the expander, and providing it to a heat exchanger, where its temperature is increased;- providing the effluent from the heat exchanger, which is LPFG, to a processing unit, which is a furnace and/or boiler.
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DE102013226126A1 (en) * | 2013-12-16 | 2015-06-18 | Technische Universität Bergakademie Freiberg | All-thermic methane reforming with physical energy recovery |
JP2021045749A (en) * | 2015-11-17 | 2021-03-25 | ダウ グローバル テクノロジーズ エルエルシー | Method and system for reducing co2 from industrial process |
JP2022066275A (en) * | 2015-11-17 | 2022-04-28 | ダウ グローバル テクノロジーズ エルエルシー | Method and system for reducing co2 from industrial process |
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