MXPA98003026A - Process and gasification plant for dire reduction reactors - Google Patents

Abstract

The present invention relates to an integrated process and apparatus for supplying at least a portion of the reducing gas feed to a reduction reactor, such as a reactor for the direct reduction of iron, wherein the reducing gas contacts a material of feeding at an average operating pressure of the gas and effecting the reduction of the feed material to provide a reduced product. The integrated process comprises gasifying a hydrocarbonaceous feed material or a partial oxidation reaction to produce a synthesis gas comprising hydrogen and carbon monoxide a pressure substantially greater than the average operating pressure of the gas in the reduction reactor. The synthesis gas is expanded to lower its pressure to practically the average operating pressure of the gas in the DRI reduction reactor, thereby forming the reducing gas feed under the pressure conditions used for the DRI reaction. The lower pressure reducing gas mixture, generated by the expansion, is introduced into the DRI reactor as part or all of the reducing gas needs for the direct reduction of iron.

Description

PROCESS AND GASIFICATION PLANT FOR DIRECT REDUCTION REACTORS FIELD OF THE INVENTION This invention relates in general to the use of a syngas or synthesis gas produced during a gasification process by partial oxidation as a feedstock in a process for the direct reduction of iron, also referred to as the "DRI" process. " BACKGROUND OF THE INVENTION Motivated by the anticipated shortage of scrap and by the increase in the number of mini-steelworks as alternatives to integrated steel plants, DRI production is currently undergoing a very important expansion on an international scale. DRI processes based on solid feed materials can be essentially divided into two general technologies depending on the iron ore feed, that is, a feed based on clods and / or pellets or a feed based on fines. Another sub-division can be made depending on the hydrocarbon feedstock used, for example, coal or gas.

The main technologies based on lumps / pellets are known as "Midrex" and "HYL III", and the technology based on fines is known as the "Fior" process. All of them use reformed natural gas as a reducing gas material for the DRI reaction. The HYL III and Fior processes use natural gas steam reforming to produce a synthesis gas that includes hydrogen and carbon monoxide. Impurities such as carbon dioxide are removed by scrubbers. The Midrex process uses a combination of natural gas reforming, with steam and carbon dioxide, in an already patented reformer. Considering these modes of production of the reducing gas, the most favorable location for a DRI plant is that where the economical natural gas and the high quality iron ore are located in close proximity, since this avoids excessive transport costs. Gasification processes by partial oxidation are often used to produce a gas comprising hydrogen and carbon monoxide as the main components. This gas is generally known as synthesis gas or "syngas". Said gasification processes by partial oxidation are very effective when carried out at relatively high pressures, generally higher than 20 atmospheres. As used herein, a partial oxidation reactor may also be considered as a "gasification reactor" or simply as a "gasifier" and these terms are frequently used in an equivalent and interchangeable manner. The feed material for a partial oxidation reaction is usually a hydrocarbonaceous material, i.e., one or more materials, generally organic, which provide a source of hydrogen and carbon for the gasification reaction. The hydrocarbonaceous material may be in the gaseous, liquid or solid state or in a combination thereof, as desired, for example, a solid-liquid composition in the fluidized state. Petroleum-based feedstocks include petroleum coke, residual petroleum derived from coal, and by-products derived from heavy crude oil. The coal or coke may be in a finely divided state. Waste plastic materials can also be used as feedstock. Many of the uses of syngas produced from the partial oxidation reaction are at relatively lower pressures. Therefore, the expansion of the syngas at high pressure is usually employed through an energy recovery machine to obtain a syngas at reduced pressure. This type of expansion is usually used as a means to generate electricity. The energy generation stage is not 100% efficient and part of the energy is lost when converting it to electricity. The electricity generated in said expansion process requires voltage booster transformers, additional electrical switches and the use of electricity.

The DRI process can use singas as feedstock, generally fed to the reaction chamber at a relatively low pressure, usually below about 5 atmospheres for a moving bed reactor and below about 15 atmospheres for a fluidized bed reactor. The exhaust gas from the DRI process is cooled, compressed, sent to a carbon dioxide separation stage and then mixed with new syn- fee feed and recycled to the DRI process. The recycle compressor is a large energy consumer and frequently uses an electric-powered motor. This motor driven by electricity is not 100% efficient and part of the energy is lost when converting electricity into power on the shaft. The use of an electric motor requires reducing transformers, an additional electric switch and a source of electricity. Alternatively, a water vapor drive with similar energy losses and with the need to use support facilities can be used. The operation of gasifiers at relatively high pressures in power generating systems, for example, the combined cycle gasification system (IGCC) is described in US Patent Nos. 5,117,6-23 and 5,345,756, wherein these systems they are coupled with expanders, gas turbines and steam turbines for power generation. US Patents Nos. 5,531,424 and 5,370,727 describe processes for the direct reduction of iron. SUMMARY OF THE INVENTION The present invention consists of an integrated process and apparatus for supplying at least a portion, or substantially all, or all of the reducing gas feed material to a reduction reactor, such as a reactor for reduction direct iron, wherein the reducing gas comes into contact with a feed material at an average operating pressure of the gas and effects the reduction of the feed material to provide a reduced product. The integrated process includes gasifying a hydrocarbonaceous feed material in a partial oxidation reaction to produce a synthesis gas comprising hydrogen, carbon and carbon monoxide at a pressure substantially greater than the measured operating pressure of the gas in the reduction reactor. The synthesis gas is expanded to lower its pressure to practically the average operating pressure of the gas in the DRI reduction reactor, to thereby form the reducing gas feed material under the pressure conditions used for the DRI reaction. The lower pressure reducing gas mixture, generated by the expansion, is introduced into the DRI reactor as part or all of the need for reducing gas for the direct reduction of iron. DESCRIPTION OF THE DRAWINGS In the attached drawings: Figure 1 is a simplified schematic drawing of a gasification process and a DRI process according to an embodiment of the invention. Figure 2 is a simplified schematic drawing of a gasification process and a DRI process according to a second embodiment of the invention. Figure 3 is a simplified schematic drawing of a gasification process and a DRI process according to a third embodiment of the invention. The corresponding reference numbers indicate corresponding parts and currents of the process in all the drawings. DESCRIPTION OF THE PREFERRED MODALITIES According to the present invention, significant improvements can be achieved by effecting a gasification reaction by partial oxidation to produce a syngas or syngas at a pressure substantially greater than the average operating pressure in the reduction reactor for the direct reduction of iron. The syngas produced from the partial oxidation reaction can then be expanded to lower its pressure to the average operating pressure for direct reduction of iron, to thereby provide the reducing gas for the DRI reaction. The reducing gas is then contacted with the feed material in the direct reduction reactor to effect the reduction of the iron oxide present therein to produce elemental iron. All the pressures referred to here are pressure metrics instead of absolute pressures, unless otherwise indicated. This approach is contrary to the practice of conventional gasifier technology where the gasifier pressure is regulated to match the pressure of downstream use. Due to the low average operating pressure used in the DRI process, operation of the gasifier at the same pressure would require a larger and more expensive installation. The gasifier would operate less efficiently at lower pressure and the separation of acid gases, such as H2S and C02 would be less efficient. Preferably, before the expansion of the singas of the partial oxidation reaction to lower its pressure and produce the reducing gas for the DRI reaction, the mixture of syngas comprising H2, CO, C02, H20, N2, H2S, COS and carbon in particles, it is partially cooled to temperatures of 90 to 370 ° C, preferably 200 to 260 ° C, and washed to remove particulate materials. After further cooling at temperatures of about -1 ° C to 65 ° C, preferably at temperatures of about 38 to 50 ° C, the singas are washed to separate their content in acid gases. About 90-100% of H2S and COS are separated to prevent iron degradation in the DRI process. The C02 is separated at the desired level for the DRI process, of the order of 50 to 100% approximately, preferably approximately 90 to 98%. The cooled and washed singas is then expanded to lower its pressure and produce energy. The expansion is effected by a turbo-expander which produces mechanical energy that can be used to drive an electric generator and produce electrical energy or that can be used directly to drive a compressor, pump or other device that requires mechanical energy. Before the expansion of the syngas to produce energy, the syngas is preferably heated to temperatures of about 145 to 650 ° C, preferably about 260 to 485 ° C, in order to increase the energy output of the expansion mechanism which is proportional to the absolute temperature of the inlet gas. The high pressure synthesis gas can be treated to separate acid gases, such as C02 and H2S, by washing or contacting with a solvent. The low pressure reducing gas that is fed to the DRI reduction reaction may include a gaseous recycle stream leaving the DRI reactor and which is also treated to remove acid gases, mainly C02, by washing with a solvent. The same solvent that is used to wash and remove the acid gas content of the high pressure synthesis gas can also be used to remove acid gases from the reducing gas at low pressure. Therefore, the separation of acid gases for both the high pressure synthesis gas and the low pressure reducing gas can be conveniently carried out in an integrated circuit, parallel or in series, with respect to the separator or common regeneration means. The synthesis gas can be saturated with water and can undergo a displacement reaction to vary the relative proportions of hydrogen and carbon monoxide. Normally, the desired H2 / C0 ratio is between approximately 1.5 and 10 for the DRI process in order to control the heat balance within the DRI reactor. The higher H2 / CO ratios can also reduce the energy requirements of the recycle compressor since the water produced from the iron reduction reaction with H2 is condensed from the recycle gas before compression. Preferably, the energy generated by the expansion of the syngas and the heat generated by any cooling and displacement reaction stage is used as a source of power and energy in the plant that includes the DRI reduction reactor. Conveniently, the overhead gas of the reduction reactor is recycled to the DRI reactor as a reducing gas after the treatment including compression and the energy generated by the expansion is directly used to drive the compression. In another embodiment, the present invention combines the energy released as a result of the decrease in syngas pressure with the energy requirements of the DRI recycle gas compressor, thus eliminating inefficiencies in the generation / use of electricity and increasing the efficiency of energy for both processes and minimizing costs. This can be achieved by determining the needs of the DRI recycling process and then carrying out the gasification by partial oxidation at a pressure sufficient to meet and match the energy needs of the DRI recycle compressor. This invention can be very efficient and economical in terms of costs with a simple shaft configuration. In addition to increasing energy efficiency, a large part of the installation can be eliminated, including the electric motor drive of the recycle gas compressor, a part of the electrical substation, the step-up transformers and voltage reducers and other infrastructure related to the DRI process. With regard to gasification, the generator and its associated installation can be eliminated. The invention also encompasses a direct reduction apparatus comprising a direct reduction reactor configured to bring the reducing gas into contact with the feed material therein, to effect the reduction of the feed material and thus to provide a reduced product. The DRI reaction system is designed to operate at an average gas operating pressure of approximately 1 to 15 atmospheres. More specifically, a moving bed reactor operates preferably at about 1-5 atmospheres and a fluidized bed reactor operates preferably at about 10-15 atmospheres.

The apparatus of the invention also includes means for partially oxidizing a hydrocarbonaceous feedstock to produce a synthesis gas including hydrogen and carbon monoxide, at a pressure substantially greater than the average operating pressure of the gas in the reduction reactor, means in communication with the gasification means for receiving the reducing gas and means for expanding the reducing gas to lower its pressure to practically the average operating pressure of the gas in the reduction reactor, and means for feeding the lower pressure reducing gas generated by the means of expansion to the reactor as at least a part of the reducing gas feed material for the direct reduction reaction. The apparatus may further include means for cooling and washing the synthesis gas and means for separating at least a part of its content in acid gases. Means for reheating the washed synthesis gas before its expansion are also preferably provided. The apparatus may further include means for recycling the excess reducing gas from the reduction reactor system back to the reduction reactor system; compressor means for compressing the recycle reducing gas; means for separating the acid gases, mainly C02, from the recycle reducing gas; and means for directly coupling the expansion means to the compressor means, whereby all or part of the energy generated by the expansion is directly used to drive the compressor means.

The acid gas separation means can employ the same solvent medium to separate acid gases from the high pressure synthesis gas and the low pressure reducing gas. Therefore, the means for separating acid gases both in the case of the high pressure synthesis gas and in the case of the low pressure reducing gas, can be conveniently incorporated in an integrated circuit, in parallel or in series, with respect to separators or common regeneration. Preferably, the apparatus includes a displacement reactor for subjecting the reducing gas mixture to a displacement reaction to vary the relative proportions of hydrogen and carbon monoxide in the mixture. With reference to Figure 1, a hydrocarbonaceous feed material 5 and air, oxygen or an air stream enriched in oxygen 6, are fed in sufficient quantities to a gasifier by partial oxidation 10 where the feed material is converted to a gas of synthesis 8 which normally comprises a mixture of hydrogen, carbon monoxide, water vapor, carbon dioxide and trace amounts of other partial oxidation products, such as nitrogen, methane, hydrogen sulfide and carbonyl sulphide. The hydrogen / carbon monoxide ratio varies depending on the feedstock and the operating conditions of the gasifier, but is generally from about 0.5 to about 3. The gasifier 10 is operated at a high pressure of approximately 20 to 150 atmospheres, which is well above the average operating pressure of the gas used in the DRI reactor 12, where the reducing gas mixture 32 is fed, after treated and expanded to lower its pressure at the average operating pressure of the gas used in the DRI reactor. The feedstock 5 can comprise liquid and / or gaseous hydrocarbonaceous fuels and / or a pumpable slurry of solid carbonaceous fuel, and can be fed to the gasifier 10 in the form of a pumpable or dry slurry, depending on the gasifier used. The slag and / or ashes 9 are recovered as a residual by-product. The possible pumpable slurries include coal, particulate carbon, petroleum coke, concentrated sewer sludge and mixtures thereof, in a vaporizable liquid carrier which may comprise water, liquid C02, liquid hydrocarbon fuel and mixtures thereof. Liquid fuels can include liquefied petroleum gas, distillates and residues of petroleum, gasoline, naphtha, kerosene, crude oil, asphalt, diesel, residual oil, asphalt sands oil and oil shale, coal-derived oil, aromatic hydrocarbons such as benzene, toluene and xylene fractions , coal tar, cycle gas oil from fluid catalytic cracking operations, coke oil gas furfural extract and mixtures of the above. Gaseous fuels can include vaporized liquid natural gas, refinery outlet gas, hydrocarbonaceous gases L- and residual gases containing carbon from chemical processes. Other equivalent feeding materials can be used in each of the categories.

The synthesis gas 8 leaving the gasifier 10 is cooled in the heat exchanger 14 to a suitable temperature for its subsequent washing and modification in a displacement reactor. Alternatively, it can be cooled by direct water injection in the singas. This temperature can vary from about 90 to 650 ° C, preferably from about 200 to about 370 ° C. The heat exchanger 14 can be used to generate water vapor, which can be used in other parts of the process or to generate energy. The syngas cooled and / or quenched 15 enters the scrubber 16 where it is washed with water to remove solid particulate materials such as ash and carbon unconverted as soot, and water soluble impurities such as ammonia, HCN, metals alkalines, chlorides and the like. The syngas becomes saturated with water in the scrubber as a result of the intimate contact of the water with the syngas.

The gasifier 10 can be suitably chosen from the various commercial gasifiers available. A suitable gasifier is the Texaco cooling gasifier, which is supplied as an integrated unit including the heat exchanger 14 and the scrubber 16. The operating pressure of the gasifier can vary from about 20 to 100 atmospheres, preferably from 25 to 80. atmospheres and will normally be of an order of magnitude greater than in the DRI process, for example, between 5 and 20 times approximately the average operating pressure, of the DRI process gas. The exact operating pressure of the gasifier is chosen according to the economic optimization of the configuration. The washed and saturated synthesis gas 17 can be fed, if desired, to a displacement reactor 18 wherein the ratio of hydrogen to carbon monoxide is altered to meet the needs of the DRI process in particular. The desired hydrogen / carbon monoxide ratio can vary considerably depending on the DRI technology used and typically ranges from about 1.5: 1 to about pure hydrogen. The exothermic displacement reaction converts water and carbon monoxide to hydrogen and carbon dioxide. Multi-bed displacement reactors with intermediate gas cooling between the reactor beds can be used to increase the conversion of CO to H2. For a single-bed reactor or for the first reactor of a multi-bed reactor system, the "displaced" singles stream 19 containing hydrogen and carbon monoxide leaves the displacement reactor 18 at a temperature of 285 to 595 ° C. approximately, preferably from about 425 to 510 ° C. For the second and subsequent reactors of a multi-bed reactor system, the "displaced" singles stream 19 containing hydrogen and carbon monoxide leaves the displacement reactor 18 at a temperature of approximately 230 to 400 ° C, preferably 260 at 345 ° C approximately. The heat generated by the shifted syngas stream 19 is dissipated in the heat exchanger 20 and used to generate useful water vapor in other parts of the process. The displaced and cooled synthesis gas stream 21 leaves the heat exchanger 20 and enters an acid gas separation system 22 where compounds containing sulfur and carbon dioxide are separated. Commercially available a number of acid gas separation systems and their choice will depend on the degree of separation of sulfur compounds and carbon dioxide required by the DRI process and depending on the operating pressure of the acid gas separation system . The acid gas stream 21a that separates in the acid gas separator system 22 enters a sulfur recovery unit 24 where elemental sulfur 25 or sulfuric acid can be recovered by known means. The acid gas separator system 22 used in particular will determine the required degree of cooling of the displaced synthesis acid entering the acid gas separator system 22. The temperature of the "sweet" synthesis gas stream or of which has separated the acidity 27 and leaving the gas separator system 22 varies normally between -1 ° C and 65 ° C approximately, preferably between 25 and 50 ° C approximately. The acid gas separator system 22 may be designed to eject or vent part or all of the C02 (not shown) separately from the H2S, or both H2S and C02 may be sent to the sulfur recovery unit 24. After the acid gas separation, the synthesis gas stream 27 is reheated by means of the heat exchanger 28 at a trature of about 145 to 815 ° C. The pressure of the hot syngas stream 29 is then reduced by means of a gas expansion device 30 to the desired pressure for the DRI process. The amount of preheating in the exchanger 28 is determined by the required outlet pressure and by the energy 31 generated in the expansion device 30. Typically, the trature of the syngas stream / reducing gas 32 leaving the expansion device 30 is about 35 to 260 ° C and its pressure is about 0.5 to 15 atmospheres. The singles / reducing gas stream 32 is now at the average operating pressure for the DRI process and constitutes the reducing gas feed material. Before entering the DRI process, the reducing gas 32 can be further heated, typically at tratures of about 425 to 815 ° C, to thereby provide the desired operating trature for the DRI process. The syngas 8 leaving the gasifier 10 has thus become the reducing gas 32 which enters the DRI process system 12. The reducing gas 32 here reduces the iron ore to metallic iron, being passed normally in counterflow and in contact with the iron ore. A number of DRI processes are commercially available, using iron ore feeds based on pellets or based on fines, and the present invention is considered applicable to all these processes. Referring now to Figure 2, the raw coal 14 is milled in the mill 7 to form ground coal which is slurried with water 11 to form the hydrocarbonaceous slurry feed material 5 which is pumped to the gasifier 10. The preferred gasifier is a downflow cooling gasifier, integrated with the Fior process. Air, oxygen or an oxygen enriched air stream 13, in parallel current, is fed with the feed slurry 5 into the gasifier 10, which is a flow-through gasifier comprising a gasification zone and a cooling zone and operates at a pressure of approximately 50 atmospheres. The reaction trature in the gasification zone is approximately 1100 to 1600 ° C. The hot syngas produced from the reaction in the gasification zone passes to the cooling zone where it is cooled with water to remove slag 9 and partially clean the syngas which is saturated with water and leaves the cooling zone of the gasifier 10 as the current 8 to 250 ° C approximately and to a pressure of 50 atmospheres approximately. The syngas stream 8 is washed with water in the soot scrubber 16, which separates practically all particulate, alkali metals, heavy metals and chlorides, entrained. The saturated and washed singas 17 then enters the displacement reactor 18 where the ratio of H2 to CO is adjusted to a value above 6, as is convenient for the DRI reaction system. The shifted syngas stream 19 is cooled in the heat exchanger 20 from 450 ° C to 40 ° C approximately before leaving as a singlet stream 21 entering the high pressure acid gas absorber 22, where all or most of the H2S and C02 is separated from the singas by a solvent. The liquid solvent containing the acid gases is usually referred to as the "rich" solvent and leaves the high pressure gas absorber 22 as a stream of liquid 36 and enters the separating / regenerating plant of C02 / H2S 26 where the rich solvent it is heated and separated from H2S and C02 to produce clean solvent streams 64 and 72 and a head gas stream 39 containing H2S and C02. Stream 39 enters the sulfur recovery unit 24 which can be a Claus system, where the sulfur 25 is recovered in its elemental form. The H2S-free syngas stream 27 leaves the high-pressure gas absorber 22 with its substantially eliminated acid gas content and said syngas is usually referred to as "sweet syngas". The sweet singapore stream 27 is reheated in the heat exchanger 28 from about 40 ° C to 500 ° C to form a heat stream of syngs 29 which enters the gas expansion device 30 to generate power in the generator 31. sweet singlet stream 32 leaves the gas expansion device 30 at a lower pressure of about 10-12 atmospheres, which is the average operating pressure of the gas used in the DRI reactor train of the Fior process. As an example, at at speeds d? Typical feed of 70-80 tons / hour of coal, 60-70 tons / hour of oxygen and 250 tons / hour of fines of iron ore, a change of pressure in the expansion device 30 from 50 atmospheres to 10-12 atmospheres approximately it can produce a power of approximately 10 megawatts. The sweet singlet stream 32 is combined with the recycle head gas stream 63 exiting the low pressure acid gas absorber 23. The combined gaseous stream 34 is at the operating pressure of the DRI reactors and thus constitutes the reducing gas stream 34. The reducing gas stream 34 enters the reheater 57 where it is heated to a temperature of 650 ° C approximately and exits as the stream of hot reducing gas 42 entering the fluidized bed DRI 40d. The main component of the Fior plant consists of an inclined cascade of four fluidized bed DRI reactors 40a, 40b, 40c and 40d. The iron ore fines supplied to the uppermost reactor 40a pass successively downwards through the reactors. The first reactor 40a is a preheater while the other three are reduction reactors. In the reactors 40b, 40c and 40d, the fines pass against a counterflow of reducing gas 42 which metallizes the iron ore and also serves as a fluidizing gas for the fluidized beds.

The reducing gas 42 is supplied to the lowermost reactor 40d by means of a gas inlet plenum (not shown) and exits as overhead gas 43 which enters the reactor 40c as the reducing gas and exits as overhead gas 44 which enters the reactor 40b as reducing gas and exits as overhead gas 45 which enters the scrubber 52. Within each of the three reduction reactors, there are multiple cyclones (not shown) to clean the overhead gas. fine iron powder, which is returned to the respective fluidized beds by means of dip tubes (not shown). In the scrubber 52, the particulate materials and water are separated from the overhead gas 45, which is cooled to about 37 ° C and comes out as a stream of cooled, clean, particle-free overhead gas 53, whose stream of It divides into streams of clean head gases 54 and 55. The clean head gas stream 54 serves as a fuel for reheater 57 and can also be supplemented with natural gas, as desired. The clean head gas stream 55 enters the compressor 56 where it is compressed to approximately 11-14 atmospheres and flows out as a compressed-head gas stream 61, which enters the low pressure acid gas absorber 23 , where its content in C02 is reduced by approximately 10-100%, preferably by approximately 60-95%. The low content CO 2 gas leaves the low pressure acid gas absorber 23 as the current 63 which is combined with the reduced pressure sweet syngas stream 32, to form the reducing gas stream 34 which enters the superheater 57 where it is heated to form the hot reducing gas stream 42 which enters the reactor 40d.

In the uppermost preheater reactor 40a, natural gas 66 serves as a fluidizing gas and also as a fuel. The effluent gas 68 leaving the reactor 40a is washed and treated separately (not shown). In an alternative arrangement, the overhead gas from the reduction reactor 40b can be used as the fluidizing heating gas in the preheater reactor 40a. The metallized iron product 58 leaving the lowermost reactor 40d is sent to a briquetting plant 59. The output is referred to as hot briquetted iron 65 or HBI. The space comprising the iron ore feed system (not shown), the DRI reactors 40a to 40d and the briquette plant 59, is kept sealed under an average gas operating pressure of about 10-12 atmospheres to minimize the reoxidation of iron. Figure 2 also shows an embodiment of the invention wherein the separation of acid gases from the higher pressure synthesis gas and from the lower pressure recycle reducing gas is integrated. The high pressure acid gas absorber 22 and the low pressure acid gas absorber 23 each use a common solvent solution to separate acid gases, such as an amine or Selexol® (Union Carbide Co.), and said solvent circulates via the common H2S / C02 separator or solvent regenerator. The solvent solution absorbs and separates the acid gases that come into contact with it in the respective absorbers. Figure 2 shows the simplest form of integration which consists of a parallel configuration in which the liquid solvent stream 36 containing the acid gases C02 and H2S exits the high pressure absorber 22. At the same time, the liquid solvent stream 60, which also contains acid gases, mainly C02, exits from the low pressure absorber 23. Both streams 60 and 36 enter the C02 / H2S / regenerator 26 separator where C02 and H2S are separated from each other. solvent, thereby regenerating the solvent to form a "clean solvent" leaving the separator / regenerator 26, which is divided into the solvent streams 64 and 72. The solvent stream 64 is recycled to the high pressure absorber 22 for its reuse, and the solvent stream 72 is recycled to the low pressure absorber 23 for reuse. The separated C02 and H2S gas stream 39 exits the top of the separator / regenerator 26 and enters the sulfur recovery unit 24 where elemental sulfur 25 is recovered. Figure 3 is a variant of the process of Figure 2 in where the integrated separation of the acid gases is effected by means of a series configuration. In this way, only the liquid solvent stream 36 leaving the high pressure absorber 22 enters the C02 / H2S / regenerator 26 separator. The regenerated clean solvent stream 72 leaving the separator / regenerator 26 is divided into the streams. 74 and 76. The solvent stream 74 enters the low pressure acid gas absorber 23 for reuse and the solvent stream 76 enters the high pressure acid gas absorber 22 for reuse. The liquid solvent stream 60 leaving the low pressure acid gas absorber 23 is also directed to the high pressure acid gas absorber 22 where the charge of the acid gas in the solvent can be increased as a consequence of the higher operating pressure of the solvent. high pressure gas absorber 22. The higher charge of C02 in the solvent stream 60 entering the high pressure absorber 22 reduces the required solvent flow rate. In a modification that achieves the most efficient integration in the plant, the synthesis gas expansion device 30 can be coupled directly to the compressor 56 which compresses the recycled reducing gas from the DRI process. In this way, the power generator 31 or the expansion device 30 can directly drive the compressor 56. Directly coupling the energy outlet 31 of the expansion device 30 with the recycle compressor 56 offers the advantages of eliminating the need of a generator on the side of the expansion device and of a motor on the side of the compressor, together with its associated electrical connections, as well as increasing efficiency by avoiding energy losses in the conversion of mechanical energy to electrical energy and again to mechanical energy. Even if the loads of the expansion device and the compressor do not match, many advantages can be achieved. In the case of unequal loads, an engine / generator on the shaft could be coupled to allow the export or import of energy, as required. The motor / generator would still be much smaller than required by an uncoupled generator and motor and the efficiency can still be improved. The composition and pressure of the singas can be adjusted to meet the needs of any current commercial DRI processes based on the production of syngas, including the HYL III, Midrex and Fior processes and other processes such as the Finmet and Circored processes. The present invention is adaptable to a variety of geographical circumstances and feeding materials and offers many operational advantages. By adjusting the gasifier pressure well above the average operating pressure of the reactor gas or DRI reactors, an expansion device can be used to generate power for the plant. Optimizing the conditions of the expansion device, including the singles reheat and acid gas separation systems, can generate most or all of the energy required to meet the gas production and preparation needs and / or the DRI plant.

Claims (20)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following claims is claimed as property: 1.- An integrated process to supply at least a portion of a reducing gas to a system of reaction for the direct reduction of iron, wherein a feed of iron ore is brought into contact with the reducing gas at an average operating pressure of the gas to produce elemental iron, characterized in that it comprises: (a) gasifying a hydrocarbonaceous feedstock in a partial oxidation reaction to produce a high temperature, high pressure synthesis gas comprising hydrogen and carbon monoxide, wherein the pressure of the synthesis gas is substantially higher than the average operating pressure of the gas used in the reaction for the direct reduction of iron; (b) expanding the synthesis gas at high pressure to lower its pressure to practically the average operating pressure of the gas used in the reaction for the direct reduction of iron, thereby using the synthesis gas as the reducing gas for said direct reduction of iron; and (c) contacting the reducing gas with an iron ore feed at an average operating temperature of the gas to thereby produce elemental iron.
2. 2. - A process according to claim 1, characterized in that the expansion of the synthesis gas is used to produce energy.
3. 3. - A process according to claim 1, characterized in that before said expansion, the synthesis gas is cooled and washed to remove acid gases contained therein.
4. 4. - A process according to claim 2, characterized in that the singas is heated before its expansion.
5. 5. - A process according to claim 3, characterized in that the reducing gas fed to the direct reduction iron reaction system includes a gaseous recycle stream that has left the reaction system of direct reduction of iron and because the acid gases have been separated from the recycle gas stream.
6. 6. A process according to claim 5, characterized in that the acid gases separated from the synthesis gas and the acid gases separated from the recycle gas leaving the reaction system of direct reduction of iron, is carried out in an integrated circuit, in parallel or in series with respect to a common separating or regenerating medium.
7. 7. A process according to claim 1, characterized in that the synthesis gas is subjected to a displacement reaction to increase the proportion of hydrogen contained therein.
8. 8. - A process according to claim 1, characterized in that energy and heat are generated during the integrated process, which are recovered and used as sources of energy and heat for the integrated process.
9. 9. - A process according to claim 2, characterized in that the reducing gas leaving the reaction system of direct reduction of iron is compressed to the average operating pressure of the gas and recycled to the iron reduction reaction, and because the energy generated by the expansion of the synthesis gas is directly used to drive the compression of the reducing gas.
10. 10. A process according to claim 1, characterized in that the hydrocarbonaceous feed material is selected from the group consisting of liquid, gaseous and solid hydrocarbonaceous fuel, a pumpable slurry of solid carbonaceous combustion and mixtures thereof.
11. 11. A process according to claim 10, characterized in that the pumpable grout of solid carbonaceous fuel is selected from the group consisting of coal, particulate carbon, petroleum coke, concentrated sewer sludge and mixtures thereof, in a vaporizable liquid vehicle. selected from the group consisting of water, liquid C02, liquid hydrocarbon fuel and mixtures thereof.
12. 12. A process according to claim 10, characterized in that the liquid hydrocarbonaceous fuel is selected from the group consisting of liquefied petroleum gas, distillates and residues of petroleum, gasoline, naphtha, kerosene, petroleum crude, asphalt, diesel, residual oil, asphalt sands oil and oil from bituminous shale, petroleum derived from coal, aromatic hydrocarbons, coal tar, gas oil from cycles from fluid catalytic cracking operations, coke oil gas furfural extract and mixtures of the above.
13. 13. A process according to claim 10, characterized in that said gaseous hydrocarbonaceous fuel is selected from the group consisting of vaporized liquid natural gas, refinery outlet gas, Cx-C4 hydrocarbon gases and residual gases containing carbon from chemical processes.
14. 14. An integrated direct reduction device, characterized in that it comprises: (a) a direct reduction reaction system configured to bring a reducing gas into contact with a feed material there, to effect the reduction of the feed material, whose system is adapted to operate at an average gas operating pressure; (b) a gasification medium by partial oxidation to gasify a hydrocarbonaceous feedstock, to produce a high pressure synthesis gas comprising hydrogen and carbon monoxide at a pressure substantially higher than the average operating pressure of the reaction system gas of direct reduction; (c) a medium in communication with the gasification medium by partial oxidation, adapted to receive and expand the synthesis gas at high pressure, thereby decreasing its pressure to the average operating pressure of the gas of the direct reduction reaction system, and to thereby form the reducing gas from the synthesis gas; and (d) a means for feeding the reducing gas to the direct reduction reaction system, to provide at least a portion of the reducing gas feed needed to effect the reduction of the feed material.
15. 15. - An apparatus according to claim 14, characterized in that it also comprises a means adapted to produce energy from the expanded synthesis gas.
16. 16. An apparatus according to claim 15, characterized in that it further comprises a means for cooling and washing the synthesis gas leaving the gasification medium by partial oxidation and a means for separating its content in acid gases, as well as a means for reheating the synthesis gas cooled and washed before its expansion.
17. 17. - An apparatus according to claim 16, characterized in that it further comprises a means for cooling and washing the excess reducing gas leaving the direct reduction reaction system, a means for separating its content in acid gases and a means for recycling the reducing gas washed and free of acid gases as a portion of the feed to the direct reduction reaction system.
18. 18. An apparatus according to claim 17, characterized in that the means adapted to separate acid gases from the synthesis gas and the means adapted to separate acid gases from the reducing gas leaving the direct reduction reaction system, are incorporated in an integrated circuit in parallel or in series with respect to a common separator or regenerator means.
19. 19. An apparatus according to claim 18, characterized in that the direct reduction reactor comprises a compressor means for compressing said recycle reducing gas; and a means for directly coupling the expansion medium of the synthesis gas with the compressing means of the reducing gas, whereby the energy generated by said expansion means is adapted to drive said compressor means.
20. 20. An apparatus according to claim 14, characterized in that it further comprises a displacement reactor for subjecting the synthesis gas to a displacement reaction, to vary the relative proportion of hydrogen and carbon monoxide contained therein.