KR19980042823A - A method of performing work using a high-pressure nitrogen-rich gas fluid - Google Patents

Abstract

The present invention relates to a method for indirectly heating a nitrogen-rich fluid generated from a cryogenic air separation unit (ASU) by burning a low-grade fuel gas in a burner (20) at a low pressure, 24 to expel the nitrogen enriched fluid to the outlet 28 after obtaining useful work.

Description

A method of performing work using a high-pressure nitrogen-rich gas fluid

The present invention relates to a method for obtaining work from a high pressure nitrogen enriched gaseous fluid produced from a cryogenic air separation unit or plant.

The cryogenic air separation plant can be designed to obtain nitrogen fractions by separating the generated air from the air in the distillation column, which is generated in a heated and discharged state through a pipe and heat exchanger, to a pressure near atmospheric pressure. In addition, the nitrogen fluid may intentionally repressurize to produce substantially all products produced from the air separation unit at higher than atmospheric pressure. High pressure plants can be used for applications where most separate air is required as a high pressure product. Such a high pressure plant has lower capital costs and lower construction costs than plants operating at minimal pressure due to small heat exchangers, columns and frontal end absorbers.

Proposals have been made for providing a cryogenic air separation plant in other industrial processes in the form of obtaining work from the resulting pressurized nitrogen and there have been similar proposals relating to the operation of air separation units to produce low pressure nitrogen.

US-A-2520862 discloses a method of taking nitrogen from a high pressure column of a conventional minimum pressure air separation unit (ASU) and mixing it with oxygen. The fuel, which is a high pressure gas mixture, is then combusted and the combustion products at about 500 캜 are expanded in the hot gas expander to atmospheric pressure. Alternatively, it is more economical to use a heat exchanger to recover heat from the expander exhaust gas that preheats the high pressure nitrogen / oxygen mixture prior to combustion.

US-A-3731495 discloses a method of mixing nitrogen with the combustion products of pressurized air / fuel fluid prior to taking nitrogen from the high pressure ASU and expanding the hot mixed gas to atmospheric pressure. Compressing the air using the generated axial force to produce a compressed air fluid which is used separately from the air separation unit and the combustion stage.

US-A-5040370 discloses a method for indirectly heating a recovered nitrogen fluid from an air separation plant at a pressure of 2 to 7 bar, i.e. a heat source, using a high temperature fluid without phase change. A method of producing a high temperature fluid having a temperature of 600 캜 or less utilizes oxygen generated from the ASU and performs an external work by expanding hot nitrogen in the turbine.

US-A-5076837 discloses basically a similar method, except that the heated nitrogen fluid has a pressure of at least 5 bar, a temperature of at least 700 ° C.

US-A-5268019 discloses a method of combusting pressurized fuel gas and expanding combustion products in the turbine to perform work. Nitrogen produced from the ASU is pressurized and supplied to the combustion products prior to expansion through the turbine. Nitrogen is also indirectly heat exchanged by the expanded combustion products, resulting in a temperature of 400 DEG C and then expanding in the turbine to perform further work. Oxygen generated from an air separation unit that produces nitrogen is used in a process to produce gaseous fuel such as furnace operation.

A-2266343 discloses a method of indirectly heating a nitrogen fluid using a low grade fuel gas produced by a furnace. Here, however, the fuel gas is compressed before being supplied to the burner.

A-2210455 discloses a method for indirectly heating a working fluid in a closed system by burning a high grade fuel gas, which is typically a mixture of helium, argon, hydrogen, or a mixture of hydrogen and methane And is inflated to induce work. The combustion products have a pressure of from 1 to 100 bar. This concept of heating the compressed nitrogen produced from the air separation unit has not yet been disclosed.

British A-1560096 discloses a method for regasifying natural gas. Heat is provided by heating the nitrogen that is the working fluid, but this nitrogen is recycled within the enclosure and is not a compressed gas fluid produced from the air separation unit. The nature of the heater and fuel used is unclear.

WO95 / 05529 discloses a method of using an inert gas such as helium, argon or neon as an operating gas indirectly heated in a closed system.

EP-A-0208162 discloses a method of burning fuel in a gas turbine and heating the exhaust gas to heat a compressed gas, preferably air.

US-A-4228659 discloses that a working fluid is indirectly heated by a combustor in a closed system. A method of using nitrogen produced from an air separation unit and discharging the nitrogen after use is not disclosed.

While the above documents describe a method of using nitrogen generated from an ASU, such disclosures are divided into two categories of heat sources for nitrogen. As one category, the fuel may indirectly heat nitrogen selectively, creating a gas mixture that expands through the turbine by adding nitrogen for direct heating and burning it with high pressure air. It was recognized that this caused many disadvantages. The quality of the gas in the expander is undesirable because it is due to the presence of fuel combustion products. The capital cost of the plant is increased by the desire to provide for compressing the fuel gas and air to be combusted together. When using a combustion gas turbine, this gas turbine involves a very substantial capital cost. Also, due to the limitation of the purity of the nitrogen supplied to mix with the combustion products, the possibility of safely adding a substantial amount of oxygen mixed with nitrogen has been ruled out. Often, combustible gases with low calories are available only at near atmospheric pressure in a way to burn oxygen generated from ASUs. Therefore, it is necessary to substantially compress and regenerate such fuel gas before use in this type of method.

Another category of initiatives discloses a method of heating nitrogen by indirect heat transfer using hot gases generated in other processes. In this category, it is not necessary to use the chemical energy generated from other fluids in the combustion process, since it only delivers the heat content necessary to heat the gaseous fluids. This means that the hot fluid and the temperature must be sufficient to provide all the heat required. In practice, this requires a large surface area and high capital cost of the indirect heat exchanger.

1 is a schematic explanatory diagram of a first embodiment according to the present invention;

2 is a schematic explanatory diagram of a second embodiment according to the present invention;

3 is a schematic explanatory view of a third embodiment according to the present invention;

4 is a schematic explanatory diagram of a fourth embodiment according to the present invention;

In a first aspect of the present invention, the present invention provides a method for producing a high pressure nitrogen rich gaseous fluid comprising: performing cryogenic air separation to produce a high pressure nitrogen rich gas fluid; Supplying a fuel gas or liquid or solid fuel having a pressure of 5 bar or less to the combustion zone; Combusting the fuel; Forming a high-temperature high-pressure nitrogen-rich fluid by indirectly heating the nitrogen-rich gas fluid using heat derived from combustion of the fuel; Performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And withdrawing said nitrogen-enriched fluid. A method for obtaining work from a high-pressure nitrogen-enriched gaseous fluid produced from a cryogenic air separation unit (ASU).

Nitrogen-enriched fluid means that it may contain gases other than nitrogen as described further below.

The fuel is preferably supplied to the burner as a fuel gas at a pressure of 3 bar or less, more preferably 1.1 to 2 bar, for example 1.1 to 1.2 bar.

It may be desirable to use a blower to improve the sufficient flow of the fuel gas into the burner for combustion, but it is preferable to obtain the fuel gas from the method of generating the fuel gas and supplying it to the burner without being pressurized by the compressor.

The fuel gas is mainly supplied at least from a source of the fuel gas having a heat content of 2.5 to 16 MJ / Nm ³ , that is, the fuel gas is suitably composed of a low calorie fuel gas. This low heat content fuel gas is difficult to burn in the burner. In order to assist the combustion of the low-heat-content fuel gas, a high-calorie gas may be added in a small amount, for example, 10 vol% or less. Preferably, the additional high heat content gas is supplied below an amount that can double the heat content of the low heat content gas.

High heat content gases can be used to facilitate combustion of low heat content gases in a variety of ways. The high heat content gas can be simply mixed with the low heat content gas to produce a mixture of high heat content. This mixture can be supplied to the pilot jet in the burner or combusted to produce a hot gas containing residual oxygen that can be supplied to the burner to improve combustion.

With a suitable source of the low heat content fuel gas which is mainly used in the present invention, typically heat content of from 2.5 to 6 MJ / Nm ³ in the furnace off-gas, typically a heat content of about 8 MJ / Nm ³ in the korekseu (COREX) There is a syngas produced by partial oxidation of solid or liquid fuels, which may also include exhaust gases, typically heavy oil or other materials such as coal but also waste. These gases are suitably produced by the IGCC method (integrated gasification combined cycle), and typically have a heat content of about 10 to 16 MJ / Nm ³ .

In general, when the heat content of the fuel gas or more than 4 to 6 MJ / Nm ^3, necessary to increase the heat content of the fuel gas will not.

However, all fuels including natural gas, LPG, fuel oil, and solid fuel can be used within the scope of the present invention.

The fuel is preferably combusted at near atmospheric pressure because it is preferable that the exhaust gas produced from the burner is discharged to the atmosphere through a path that is not substantially pressurized. This differs from the preceding proposed methods of using a gas turbine in that work can be obtained by expanding the exhaust gas without creating exhaust gas under pressure.

The high pressure nitrogen enriched fluid used in the present invention is obtained from a cryogenic air separation unit (ASU). The nitrogen-enriched fluid may contain not only nitrogen but also one or more other gases from the ASU. Preferably, the oxygen separated from the ASU is supplied to the process of producing the fuel gas, or one or more low heat content components of the fuel gas. Such a process may be, for example, operation of a furnace or another fuel gas production process of the type described above. The oxygen product produced from the ASU may not be all combusted in the fuel gas production process, in which case it may be beneficial to increase the amount of gas that can be re- It is because.

Alternatively, the compressed air generated from the ASU may be added to a nitrogen fluid to produce a nitrogen fluid containing oxygen and other air gases.

However, the ASU may be operated to achieve less than the total separation of oxygen and nitrogen. In general, the nitrogen content of the nitrogen rich gas may include up to 90% pure nitrogen, for example nitrogen from air, e.g. 80 to 100% by volume N ₂ .

The work obtained by inflating the high temperature, high pressure nitrogen enriched fluid can be used to power a compression train in the ASU that provides compression, for example, air inflow in the ASU, nitrogen compression in the ASU, or oxygen compression in the ASU. Work can also be used to power generators available for powering purposes or to supply electricity.

Before the heating step, it is preferred that the nitrogen-enriched fluid has a pressure of 2 to 20 bar. It is more preferable that the nitrogen-enriched fluid has a pressure of 2 to 7 bar. Typically, the nitrogen-enriched fluid will be from 2 to 5 bar, for example 3 bar, if taken from the ASU without further compression, or from 5 to 7 bar if further compression is taken from the ASU.

The temperature of the nitrogen-enriched fluid is suitably from 400 to 1,000 占 폚, more preferably from 600 to 800 占 폚.

The nitrogen-enriched fluid may expand to perform said external work in a turbine, which may be an axial turbine or an inward radial turbine.

It is highly desirable to carry out the external work in the above-described expansion step, then recover the heat from the nitrogen-enriched fluid and transfer it to the incoming nitrogen-rich fluid before heating the nitrogen-enriched fluid by combustion of the fuel gas. This can be achieved directly by heat exchange between the exit nitrogen rich fluid and the incoming nitrogen rich liquid. The exhaust nitrogen rich fluid can also be added to the combustion products of the fuel gas heated with the incoming nitrogen rich fluid. In an additional method, the heat generated from the exhaust combustion waste gas and the nitrogen-enriched fluid is such that in a fluid in which the temperature in the incoming nitrogen-enriched fluid has not increased or increased, a liquid such as water is evaporated into the incoming nitrogen- enriched fluid, Can be used to increase recoverable energy.

It is preferable that the power generated from the combustion of the fuel is supplied to the nitrogen-rich fluid at 0.75 to 9 KW / kg mol N ₂ / hr, for example, 2 to 4 KW / kg mol N ₂ / hr.

Nitrogen-enriched fluids can be released to the atmosphere after use or used in other processes.

As a first example of the present invention, the present invention relates to a fuel gas or a combustible fuel gas having a pressure of 5 bar or less for burning the liquid or solid fuel, or a source of liquid or solid fuel means; Said cryogenic air separation unit as a source of said high pressure nitrogen enriched fluid; Means for indirectly heating the nitrogen enriched fluid using heat generated by combustion of the fuel to form a high temperature, high pressure nitrogen enriched fluid; Means for performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And means for discharging said nitrogen enriched fluid from the apparatus. ≪ RTI ID = 0.0 > [0002] < / RTI >

The source of the combustible fuel gas may be any of the above, including those connected to the furnace. The apparatus may further comprise a source of high calorie fuel gas as a regulator of a single heated fuel source or a low calorie fuel source as described above.

As described above, the apparatus includes an air separation unit as a source of said nitrogen-enriched fluid, and comprises means for separately compressing the air supplied to the air separation unit, and means for compressing said compressed And means for powering the means.

And, alternatively or additionally, means may be provided for powering the other compaction parts of the air separation unit or for operating the electric generator using the work obtained by inflating the high temperature, high pressure nitrogen enriched fluid.

A connection may be provided to supply the oxygen separated from the air separation unit to the apparatus for generating the fuel gas or the main low heat content component of the fuel gas.

The apparatus may include a turbine as a means of obtaining work by expanding the high temperature, high pressure nitrogen enriched fluid, and includes means for generating energy from the nitrogen enriched fluid after the expanding step and transferring the energy to the incoming nitrogen enriched fluid can do.

In an alternate aspect of the present invention, the present invention provides a method for producing an exhaust gas comprising: forming a substantially unpressurized exhaust gas fluid in the combustion zone by supplying fuel to the combustion zone to burn the fuel; The high-pressure nitrogen-rich fluid obtained from the separation unit (ASU) is heated by transferring the heat generated by the combustion to the high-pressure nitrogen-enriched fluid, by not mixing the nitrogen-enriched fluid and the exhaust gas fluid, ; Performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And withdrawing said nitrogen enriched fluid. ≪ RTI ID = 0.0 > [0002] < / RTI >

Exhaust gas fluid is generally present at ambient pressure, except when overpressure above ambient pressure is required to allow exhaust gas fluid to exit around the device. This flow is generally generated without inflating the exhaust gas fluid within the apparatus from which the work is generated.

In this alternative aspect of the present invention, the present invention provides an air separation unit for producing a high pressure nitrogen rich gas fluid; Means for supplying fuel to the combustion zone; Means for forming a substantially unpressurized offgas fluid in the combustion zone by forming the combustion zone for combusting the fuel; A heat exchange means for transferring the heat generated by the combustion to a high pressure nitrogen enriched fluid and heating the nitrogen enriched fluid by not mixing the nitrogen enriched fluid and the exhaust gas fluid to form a high temperature high pressure nitrogen enriched fluid; Means for performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And means for discharging the nitrogen enriched fluid from the apparatus. ≪ RTI ID = 0.0 > [0002] < / RTI >

Preferred features of this alternative aspect of the invention relate to the first aspect of the invention as described above.

The invention may be further illustrated by reference to the following drawings.

The apparatus shown in Figure 1 is connected to a heat exchanger 14 via a pipeline 12 and an air separation unit 18 connected to a second heat exchanger 18 (fuel burner 20 is connected) (10) of pressurized nitrogen generated from the pressurized nitrogen inlet (10). Nitrogen fluid is supplied from the heat exchanger 18 through the pipeline 22 to the inlet of the axial turbine 24 where it performs the outer work by expanding the nitrogen fluid and provides an axial force from the turbine . Nitrogen is then fed through the pipeline 26 to the heat exchanger 14 on the opposite side and then discharged through the outlet 28. Air is supplied to the inlet portion 30 to assist combustion, and a combustible fuel gas is supplied to the inlet portion 32. The inlet 32 is usually connected to a discharge for the offgas produced from the furnace.

Air flows into the third heat exchanger (36) from the inlet (30) through the pipeline (34). Fuel gas also flows into the heat exchanger 36 from the inlet 32 through the pipeline 38 where the air and the fuel gas are heated by heat exchange as described below. Air is supplied from the heat exchanger 36 to the burner 20 via the pipeline 40 and likewise the fuel gas is supplied through the pipeline 42. The combustion products of fuel gas and air produced in the burner 20 are subjected to heat exchange associated with the nitrogen fluid in the heat exchanger 18 and then heat exchange associated with the heat exchanger 36 to preheat the source of oxygen and fuel gas . This combustion product is discharged from the heat exchanger (36) through the outlet (46).

In use, the incoming nitrogen fluid from the inlet 10 is expanded in the turbine 24 and then discharged in the heat exchanger 14 by discharge of the exhaust nitrogen fluid, And is further heated in the heat exchanger 18 by the combustion of air. Generally, nitrogen first passes through a zone where heat transfer is primarily by convection, and then through heat transfer zones close to the burner flame, which is mainly formed by radiation.

Generally, the burner may be one of a type specifically designed to burn low heat content fuel gas. The burner may be a typical burner that preheats the air source and / or the fuel source supplied to the burner in a representative manner by any medium, which is heated by the combustion process. The burner may also be a burner designed to burn other gases, liquids or solid fuels.

2, the heat exchanger 14 is omitted, and the expanded nitrogen gas produced from the turbine 24 is supplied to the evaporator 18a at a position between the radiant portion and the convection portion of the heat exchanger 18a, Lt; / RTI > The combustion product mixed with nitrogen then heats the incoming nitrogen fluid which flows directly into the heat exchanger 18a via the region of the heat exchanger 18a.

In the alternative arrangement shown in Figure 3, the expanded nitrogen gas stream discharged from the turbine mixes with the combustion products produced from the fluid above the burrs of the heat exchanger 18b. In this embodiment, the heat exchanger 18b does not include any radiator, and the heat transfer is mainly by convection.

Fig. 4 illustrates a further embodiment of a device that can re-energize energy from an expanded nitrogen fluid in a third embodiment mode and does not preheat air and fuel gas at all. In this embodiment, the air and the fuel gas are directly supplied to the burner 20. Nitrogen entering the inlet 10 flows into the water saturator 50 with the hot inlet inlet line 52 through the pipeline 12 where the nitrogen saturates while passing nitrogen fluid. The moisture is removed from the saturator 50 via line 54 and then into the pump 56 which circulates the water and then into the heat exchanger 60 via line 58, Is heated by the combustion products generated from the burner (20). This hot water flows into the line 52 through the valve 62 and the moisture passing through this line 52 flows back into the saturator 60. [ And then flows into the pump 56 through the inflow part 64.

The saturated nitrogen is discharged from the evaporator 50 through line 65 and heated in heat exchanger 14 as opposed to the expander exhaust. This saturated nitrogen is further heated in the heat exchanger 18 prior to expansion in the turbine 24 and then the expanded nitrogen fluid is supplied on the opposite side of the heat exchanger 18 to further supply heat to the incoming nitrogen fluid .

Typical operating parameters of the apparatus shown in Figure 1 are shown in Table 1 below and typical operating parameters of the apparatus shown in Figures 2 and 4 are listed in Tables 2 and 3 (3a and 3b).

Fluid number 46 40 34 42 38 16 12 22 26 28 Molar flow rate, KMOL / HR N ₂ 758.6 382.1 382.1 376.5 376.5 4747.6 4747.6 4747.6 4747.6 4747.6 O ₂ 4.8 102.5 102.5 O.O O.O O.O O.O O.O O.O O.O AR 4.5 4.5 4.5 O.O O.O O.O O.O O.O O.O O.O CO ₂ 195.3 0.0 0.0 O.O O.O O.O O.O O.O O.O O.O CO 6.1 0.0 0.0 201.3 201.3 O.O O.O O.O O.O O.O H ₂ 0.0 0.0 0.0 O.O O.O O.O O.O O.O O.O O.O H ₂ O 0.0 0.0 0.0 O.O O.O O.O O.O O.O O.O O.O Total flow, KMOL / HR 969.3 489.1 489.1 577.8 577.8 4747.6 4747.6 4747.6 4747.6 4747.6 Temperature, ℃ 120.4 302.7 20.0 302.7 20.0 350.0 70.0 700.0 400.4 121.6 Pressure, bar 1.1 1.1 1.1 1.1 1.1 6.0 6.0 6.0 1.0 1.0

Fluid number 22 26 46 40 34 42 38 12 Molar flow rate, KMOL / HR N ₂ 4747.6 4747.6 5598.7 432.4 432.4 418.7 418.7 4747.6 O ₂ 0.0 0.0 5.4 116.0 116.0 O.O O.O O.O AR O.O 0.0 5.1 5.1 5.1 O.O O.O O.O CO ₂ 0.0 0.0 221.1 O.0 O.O O.O O.O O.O CO 0.0 0.0 2.8 O.0 0.0 223.9 223.9 O.O H ₂ 0.0 0.0 0.0 O.0 O.O O.O O.O O.O H ₂ O 0.0 0.0 0.0 O.0 O.O O.O O.O O.O Total flow, KMOL / HR 4747.6 4747.6 5833.1 553.5 553.5 642.5 642.5 4747.6 Temperature, ℃ 700.0 400.4 161.4 147.4 20.0 147.4 20.0 70.0 Pressure, bar 6.0 1.0 1.0 1.1 1.1 1.1 1.1 6.0

Fluid number 22 26 46 28 58 52 Molar flow rate, KMOL / HR N ₂ 4747.6 4747.6 960.6 4747.6 O.O O.O O ₂ O.O O.O 6.1 O.O O.O O.O AR O.O O.O 5.8 O.O O.O O.O CO ₂ O.O O.O 250.4 O.O O.O O.O CO O.O O.O 1.3 O.O O.O O.O H ₂ O.O O.O 0.0 O.O O.O O.O H ₂ O 262.1 262.1 0.0 262.1 1403.8 1403.8 Total flow, KMOL / HR 5009.6 5009.6 1224.3 5009.6 1403.8 1403.8 Temperature, ℃ 700.0 405.7 120.0 125.7 45.0 150.0 Pressure, bar 5.9 1.0 1.1 1.O 8.0 6.0

Fluid number 34 32 12 54 65 Molar flow rate, KMOL / HR N ₂ 489.8 470.8 4747.6 0.0 4747.6 O ₂ 131.3 0.0 0.0 0.0 0.0 AR 5.8 0.0 0.0 0.0 0.0 CO ₂ 0.0 0.0 0.0 0.0 0.0 CO 0.0 251.7 0.0 0.0 0.0 H ₂ 0.0 0.0 0.0 0.0 0.0 H ₂ O 0.0 0.0 0.0 262.1 262.1 Total flow, KMOL / HR 626.9 722.6 4747.6 262.1 5009.6 Temperature, ℃ 20.0 20.0 70.0 20.0 69.1 Pressure, bar 1.1 1.1 6.0 6.0 5.9

Example 1

In an exemplary embodiment of the practice of the present invention using the apparatus shown in Figure 1, nitrogen is supplied at a pressure of 6 bar to 70 占 폚, and heat exchanger 14 discharges nitrogen from a turbine cooled to 400 to 122 占 폚 Heated to 350 DEG C by indirect heat exchange using a nitrogen flow. The preheated nitrogen was introduced into the convection section and then introduced into the heat exchanger 18 heated to 700 ° C and the radiant heat transfer section of the heater provided by the burner 20.

This hot nitrogen fluid is then passed through an axial turbine 24, which generates an axial force used to provide some of the energy required for the ASU air compressor.

The fuel gas used in the burner used a low-calorie fuel gas, such as a furnace gas, of 4.4 MJ / Nm ³ , which can be mixed with a small amount of coke oven gas or natural gas to aid combustion . Initially both 20 ° C fuel gas fluid and combustion air fluid were preheated to 303 ° C in heat exchanger 36 before entering the burner 20. The fuel gas generated from the burner was discharged from the heat exchanger 36 at 120 캜 and exhausted to the atmosphere. The conditions to be fulfilled in these units can be listed as follows:

Nitrogen flow rate = 4747.6 kgmols / hr

Nitrogen inlet pressure = 6 bar

Nitrogen inlet temperature = 700 ° C

Axial force output = 12.2 MW

Fuel gas heating (LHV) = 15.83 MW

While the invention has been described by reference to specific embodiments thereof, numerous variations and modifications of the invention are, of course, contemplated within the scope of the invention.

An advantage of the present invention, as illustrated, is that it recovers internal energy from available ASU waste nitrogen fluids at high pressures by expanding nitrogen in expanders with high thermal efficiency. Preheating nitrogen to the maximum temperature that the expander can accommodate will maximize the amount of axial force generated. By indirectly heating nitrogen primarily by low pressure evacuator off-gas and in a secondarily ignited heater, it maximizes the conversion efficiency from thermal energy to axial energy. This is assisted by preheating the combustion air and the fuel gas against the fuel gas of the ignited heater. Using an ignited heater to indirectly heat nitrogen means that it maximizes the efficiency of the process because there is no need to compress the fuel gas or burn the air. This is very important when using very low calorific fuel such as blast furnace gas.

Claims (30)

Performing cryogenic air separation to produce a high pressure nitrogen enriched gaseous fluid; Supplying a fuel gas or liquid or solid fuel having a pressure of 5 bar or less to the combustion zone; Combusting the fuel; Forming a high-temperature high-pressure nitrogen-rich fluid by indirectly heating the nitrogen-rich gas fluid using heat derived from combustion of the fuel; Performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And withdrawing said nitrogen enriched fluid. A method for obtaining work from a high pressure nitrogen enriched gaseous fluid generated from a cryogenic air separation unit (ASU). The method of claim 1, wherein the fuel is a fuel gas supplied to the combustion zone at a pressure of 3 bar or less. 3. The method of claim 2, wherein the fuel gas pressure is between 1.1 and 2.5 bar. 3. The method of claim 2 wherein the fuel gas pressure is 1.1 to 1.2 bar. Any one of claims 1 to A method according to any one of claim 4, wherein said fuel gas is mainly supplied from the heat content of at least 2.5-12 MJ / Nm ³ in the fuel gas supply source. 6. The method of claim 5, wherein the fuel gas having the heat content is a syngas produced from a partial oxidation of solid or liquid fuel, an exhaust gas produced from the furnace, a corex discharge gas, or the like. 7. The method of claim 6, wherein the gas is combusted without being compressed. 8. The method of claim 6 or 7, wherein the fuel gas having the heat content is mixed with a small amount of gas having a substantially high heat content. The method of claim 8, wherein the high heat content gas is coke oven gas, natural gas or LPG. Claim 8 according to any one of claims 9, wherein the heat content of from 2.5 to 16 MJ / Nm ³ in the fuel gas has a heat content of from 2.5 to 4 MJ / Nm ^3, a gas mixed with a sufficient amount of that has a substantially high heat content It is a method of increasing the heat content of the mixture to 4 to 6 MJ / Nm ^3. 11. The process according to any one of claims 8 to 10, wherein the small amount is sufficient to double the heat content of the fuel gas added with the high heat content gas. 4. The method according to any one of claims 1 to 3, wherein the fuel is natural gas, fuel oil or LPG. 13. The method according to any one of claims 1 to 12, wherein the nitrogen enriched fluid comprises at least one other gas generated from an ASU other than nitrogen. 14. The method according to any one of claims 1 to 13, wherein power is supplied to the gas compression in the air separation unit using a work obtained by expanding the high temperature, high pressure nitrogen enriched fluid. 15. The method according to any one of claims 1 to 14, wherein the oxygen separated from the air separation unit is supplied to the process for producing the fuel. 16. The process according to any one of the preceding claims, wherein the nitrogen-enriched fluid before the heating step has a pressure of from 2 to 20 bar. 17. The method of claim 16, wherein the nitrogen enriched fluid before the heating step is at a pressure of 2 to 7 bar. 18. The process according to any one of claims 1 to 17, wherein the nitrogen-enriched fluid before the expansion step has a temperature of 400 to 1,000 占 폚. 19. The method of claim 18, wherein the nitrogen-enriched fluid has a temperature of 600 to 800 占 폚. 20. The method of any one of claims 1 to 19, wherein the high temperature, high pressure nitrogen enriched fluid is expanded in the turbine to perform the outer work. 21. The method of any one of claims 1 to 20, wherein after the external work is performed in the expansion step, the heat remaining in the nitrogen-enriched fluid is transferred to the high-pressure nitrogen-enriched fluid, And the nitrogen-enriched fluid is heated using the generated heat. 22. The process according to any one of claims 1 to 21, wherein the power input by combustion of the fuel is supplied at 0.75 to 9 KW / kg mol N ₂ / hr. A combustible fuel gas 32 having a pressure of not more than 5 bar for burning the fuel gas or the liquid or solid fuel, or a source of the liquid or solid fuel means 20; Said cryogenic air separation unit as a source of said high pressure nitrogen enriched fluid; Means (18) for forming a high temperature, high pressure nitrogen enriched fluid by indirectly heating said nitrogen enriched fluid using heat generated by combustion of said fuel; Means (24) for performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And means (28) for discharging said nitrogen enriched fluid from the apparatus. The method of claim 23, wherein the thermal unit to the content is included as substantially 4 MJ / Nm ³ or more of adding the additional gas source. 25. A method according to claim 23 or 24, further comprising: means for compressing the air supplied to be separated from the air separation unit; and means for supplying power to the compression means by applying the work obtained by expanding the high- Further comprising means. 26. The apparatus according to any one of claims 23 to 25, wherein the oxygen separated from the air separation unit is supplied to the apparatus for generating the fuel gas. 26. The apparatus according to any one of claims 23 to 26, wherein the means (24) for expanding the high temperature, high pressure nitrogen enriched fluid comprises a turbine. 28. The apparatus according to any one of claims 23 to 27, comprising means (14) for generating energy from the nitrogen enriched fluid after the expansion step and for transferring the energy to the incoming nitrogen enriched fluid. Forming a substantially unpressurized exhaust gas fluid in said combustion zone by supplying fuel to said combustion zone to combust said fuel; The high-pressure nitrogen-rich fluid obtained from the separation unit (ASU) is heated by transferring the heat generated by the combustion to the high-pressure nitrogen-enriched fluid, by not mixing the nitrogen-enriched fluid and the exhaust gas fluid, ; Performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And discharging said nitrogen enriched fluid. ≪ Desc / Clms Page number 17 > An air separation unit for generating a high-pressure nitrogen-rich gas fluid; Means for supplying fuel to the combustion zone; Means (20) for forming a substantially unpressurized offgas fluid in said combustion zone by forming said combustion zone for combusting said fuel; A heat exchange means (18) for transferring the heat generated by the combustion to a high pressure nitrogen rich fluid, wherein the nitrogen rich fluid is not mixed with the exhaust gas fluid, thereby heating the nitrogen rich fluid to form a high temperature high pressure nitrogen rich fluid; ; Means (24) for performing an external work by expanding the high temperature, high pressure nitrogen enriched fluid; And means (28) for discharging said nitrogen enriched fluid from said apparatus.