Method for operating an industrial plant

Abstract

A method of operating an industrial installation comprising a source of blast furnace gas, a coke dry quenching unit and a sorption-enhanced water-gas shift reactor, the method comprising the ordered steps of: (a) feeding a stream of blast furnace gas from the source of blast furnace gas to a cooling chamber of the coke dry quenching unit to quench coking reaction; (b) collecting a stream of enriched blast furnace gas exiting the cooling chamber; and (c) feeding the collected stream of enriched blast furnace gas to the sorption-enhanced water gas shift reactor thereby producing a CO2- rich stream and a H2-rich stream.

Description

METHOD FOR OPERATING AN INDUSTRIAL PLANTTechnical Field

[0001] The present invention generally relates to a method for operating an industrial plant, and more particularly to a method for producing hydrogen while reducing CO2 emissions of a coke dry quenching plant.Background Art

[0002] Industrial processes contribute significantly to global CO2 emissions and the current iron and steel manufacturing process is very energy and carbon intensive. With the Paris Agreement and near-global consensus on the need for action on emissions, it is imperative that each industrial sector looks into the development of solutions towards improving energy efficiency and decreasing CO2 output.

[0003] The Blast Furnace - Basic Oxygen Furnace remains the most common route for steel manufacturing allowing for the largest versatility of steel grades. One technology developed to reduce the carbon footprint is to replace conventional hot blast by a reducing gas, mainly comprising hydrogen and carbon monoxide (syngas).

[0004] Another technology developed to reduce the carbon footprint during steel production is the iron ore direct reduction process. Although annual direct reduction iron production remains small compared to the production of blast furnace pig iron, it is indeed very attractive for its considerably lower CO2 emissions, which are 40 to 60 % lower for the direct reduction - electric arc furnace (EAF) route, compared to the blast furnace - basic oxygen furnace route.

[0005] In a direct reduction shaft furnace, a charge of pelletized or lump iron ore is loaded into the top of the furnace and is allowed to descend, by gravity, through a reducing gas. The reducing gas, mainly comprised of hydrogen and carbon monoxide (syngas), flows upwards, through the ore bed. Reduction of the iron oxides occurs in the upper section of the furnace, conventionally at temperatures up to 950 °C and even higher. The solid product, called direct reduced iron (DRI) is typically charged hot into Electric Arc Furnaces (EAF), or is hot briquetted (to form HBI).

[0006] In most of the existing direct reduction shaft furnaces, and in more and more of the existing blast furnace installations, the above-mentioned syngas is generated via reforming of a carbon-containing gas, such as e.g. natural gas. Thehigher the H2 content of the reducing gas, the higher is the reduction of the CO2 emissions.

[0007] In all cases, there is a growing need to have readily available essentially pure H2 produced on-site for injection (i.e. feeding) into either one of a blast furnace, a direct reduction reactor, or any reduction apparatus demanding a reducing gas.

[0008] Moreover, increasing amount of hydrogen in syngas decreases its carbon content. However, carbon is most always needed in steel production, at least for carburizing the produced iron and obtain the desired alloy. Coke thus seems to be still much needed in steel manufacturing. Coke is produced in coke ovens and once the coking reaction is done, hot coke is transferred to a quenching unit where it could be either dry quenched or wet quenched. In a so-called dry-quenching, a cold quenching gas is passed through the hot coke and collected or extracted until the hot coke has cooled to a temperature below its kindling temperature. The hot gas is generally passed through a heat recovery unit in which steam is generated before being recycled back into the quenching unit or released to the atmosphere.Technical Problem

[0009] It is thus an object of the present invention to provide an improved approach for the treatment and valorization of waste gases in an industrial plant, in particular an improved approach for the (local) production of hydrogen and concomitant (overall) reductions of CO2-emissions.

[0010] This object is achieved by a method as claimed in claim 1 and / or an industrial installation as claimed in claim 10.General Description of the Invention

[0011] In a first aspect, the present invention relates to a method of operating an industrial installation comprising a source of blast furnace gas, a coke dry quenching unit and a sorption-enhanced water-gas shift reactor, the method comprising the ordered steps of: a) feeding a stream of blast furnace gas from the source of blast furnace gas to a cooling chamber of the coke dry quenching unit to quench coking reaction; b) collecting a stream of enriched blast furnace gas exiting the cooling chamber;c) feeding the collected stream of enriched blast furnace gas to the sorption- enhanced water gas shift reactor thereby producing a CCh-rich stream and a H2-rich stream.

[0012] The present invention provides an optimal configuration of blast furnace plant, coke dry quenching unit and sorption-enhanced water-gas shift reactor, when located on the same site of an industrial installation. Advantageously, essentially pure hydrogen is produced on-site and is readily available to be used within the industrial installation, while coke has concurrently been quenched. Indeed, as the water-gas shift reactor is a sorption enhanced water-gas shift reactor (where a single reactor is configured to realize the water-gas shift reaction and separate CO2), carbon dioxide (CO2) produced by the water-gas shift reaction will be separated from hydrogen (H2), e.g. by solid adsorption of the formed CO2, resulting in a (first) stream rich in hydrogen (hydrogen-rich stream or H2-rich stream) and a (second) stream of substantially pure CO2 exiting the sorption-enhanced water-gas shift reactor.

[0013] The water-gas shift reaction occurring in the sorption enhanced water- gas shift reactor and which describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen, is as follows:CO + H2O 5 CO2+ H2

[0014] Depending on the composition of the gas fed to the sorption-enhanced water-gas shift reactor, the H2-rich stream leaving the reactor may comprise - in addition to molecular hydrogen H2 - other components, such as e.g. N2 and / or H2O.

[0015] Indeed, nowadays, more and more blast furnaces are no longer operated with conventional hot blast, but with a so-called syngas, which is a reducing gas comprising mainly CO and H2. Depending on its production method, composition of the syngas may vary (such as e.g. its nitrogen content), which will reflect on the composition of the blast furnace gas exiting the blast furnace and being fed (possibly after treatment, such as e.g. dedusting and / or desulphurization and / or HCI removal) to the coke dry quenching unit. However, the typical composition of the blast furnace gas fed to the cooling chamber of a coke dry quenching unit according to the present invention is approximately 14.5 - 24 vol.-% CO, 14.5 - 27 vol.-% CO2, 3 - 7 vol.-% H2, 2 - 7 vol.-% H2O, 35.5 - 62.5 vol.-% N2, such as e.g. 21 vol.-% CO, 26 vol.-% CO2, 4 vol.-% H2, 2 vol.-% H2O and 47 vol.-% N2.

[0016] Depending on its composition, the hydrogen-rich stream exiting the sorption-enhanced water-gas shift reactor can then be optionally passed through a nitrogen removing unit (e.g. using membranes or pressure swing adsorption) for separating N2 from the gaseous flow and / or passed through a water vapor recovery unit (e.g. using membranes or an absorption / condensation unit) for separating H2O from the gaseous flow, thereby resulting in a (third) stream of essentially pure hydrogen. The present invention thus enables production of essentially pure hydrogen H2, which may advantageously be used on-site of the industrial plant, without needing long-distance transportation.

[0017] Moreover, the second stream exiting the sorption-enhanced water-gas shift reactor is a stream of substantially pure CO2, which may be valorized (e.g. and without being limited to, as a chemical for the production of e-fuel) due to its high-CO2 content and high purity, instead of being wasted. In other words, the second stream of substantially pure CO2 is a high added value waste gas.

[0018] According to the invention, blast furnace gas (BFG) is used to dry quench coke in the cooling chamber of the coke dry quenching unit (i.e. blast furnace gas is used a coke quenching gas), while optimizing the composition of the blast furnace gas prior to its feeding to the sorption-enhanced water-gas shift reactor.

[0019] In other words, the quenching gas is not simply recycled, but is valorized in a subsequent plant of the industrial installation. Moreover, the additional hydrogen (already physically present in the hot coke or formed upon reaction between the hot coke and the quenching gas) taken up and collected by the blast furnace gas will be separated in the sorption-enhanced water-gas shift reactor unit to be available for use instead of being burned in the closed loop of quenching gas in conventional coke dry quenching plants.

[0020] Hence, in the present invention, the composition of the blast furnace gas is optimized in that molecular hydrogen H2 is added to the blast furnace gas in the quenching unit. Added molecular hydrogen is mainly volatile hydrogen trapped in the coke during the coking process but may also be hydrogen formed upon reaction between water H2O comprised in the blast furnace gas and coke.

[0021] The composition of the blast furnace gas is further optimized in that the H2O and CO2 present in the blast furnace gas interact with hot coke, converting part ofcarbon of the coke into CO, thereby increasing the CO content of the blast furnace gas, i.e. increasing the amount of species needed to produce hydrogen H2 in the sorption-enhanced water-gas shift reactor. This inevitable reaction in dry quenching, also called coke loss, is thus also advantageously contributing to the enriched blast furnace gas composition.

[0022] A still further advantage of the present method is that the (enriched) blast furnace gas is heated by heat exchange with the hot coke during the dry quenching process. The amount of heat collected by the (enriched) blast furnace gas may depend on process parameters such as the temperature of the coke to quench or the flow rate of the quenching gas (blast furnace gas).

[0023] While the water-gas shift reaction is, from a thermodynamic point of view, preferably performed at lower temperatures because it is an exothermic reaction, it usually requires the use of a catalyst, having an improved catalytic activity at increased temperatures. As a result, a sorption-enhanced water-gas shift reactor is usually fed with gases at a temperature of about 300-400 °C depending on the catalyst.

[0024] As the (enriched) blast furnace gas to be fed to the sorption-enhanced water-gas shift reactor collects heat from the hot coke to be quenched, there is no need for a further heating thereof, thereby further reducing costs, energy consumption and CO2 emissions.

[0025] As the enriched blast furnace gas exiting the coke dry quenching unit may have a temperature between 600 °C and 800 °C, e.g. of about 650 °C, about 700 °C or about 750 °C, the hot enriched gas may preferably be cooled down and its heat collected for further use in the industrial plant, e.g. collected by heat exchange with another process gas (i.e. a gas being used in the plant). The present method may thus advantageously provide for an improved utilization of the heat of the coke to be quenched and an increase energy recovery.

[0026] Further advantageously, the coke loss (i.e. coke being converted into carbon monoxide upon reaction between the hot coke and CO2 contained in the quenching gas during the dry-quenching process) is of similar magnitude when using blast furnace gas as quenching gas compared to conventional coke dry quenching processes, and may even be lower. A reduced coke loss results in increased cokeproduction and reduced CO2 emissions, which are beneficial from a financial and environmental point of view.

[0027] Yet another advantage of the present invention is that CO2 produced upon dry quenching of the coke (due to the hot coke reacting with the quenching gas) is not emitted into the atmosphere as per conventional coke dry quenching processes, but is collected in the blast furnace gas and absorbed in the sorption-enhanced water-gas shift reactor, thereby avoiding further CO2 emissions and increasing the CO2 saving of the industrial installation. Moreover, the captured CO2 is substantially pure and will not require any elaborate purifying treatment before its further use or storage.

[0028] The present inventive method is thus advantageously a method for reducing CO2 emissions of the industrial installation. The method is also advantageously a method for producing H2, preferably locally producing H2 where it is needed and could be directly of use, thereby alleviating the need for H2 storage and especially transport.

[0029] In the present text, “hydrogen-rich stream” or “H2-rich stream” means that the hydrogen concentration in the stream is at least 35 vol.-%, preferably at least 37 vol.-%, more preferably at least 38 vol.-%, still more preferably at least 40 vol.-%.

[0030] In the present text, “essentially pure hydrogen” or “essentially pure H2” means that the hydrogen concentration in the stream is at least 80 vol.-%, preferably at least 90 vol.-%, more preferably at least 95 vol.-%.

[0031] In the present text, “substantially pure CO2”, or alternatively “CO2-rich”, means that the CO2 concentration in the stream is at least 70 vol.-%, preferably at least 80 vol.-%, more preferably at least 82 vol.-%.

[0032] In embodiments, the enriched blast furnace gas exiting the coke dry quenching unit may be fed to a heat recovery steam generator prior to being fed to the sorption-enhanced water-gas shift reactor. Advantageously, excess heat would be recovered from the enriched blast furnace gas and reused in the industrial plant e.g. to produce steam and / or electricity, thereby alleviating the energy requirement of the plant and further reducing its CO2-emissions.

[0033] In preferred embodiments, at least part of the steam generated in the heat recovery steam generator is fed to the sorption-enhanced water-gas shift reactor in order to allow the water gas shift reaction in the sorption-enhanced water-gas shiftreactor to occur (as per normal practice and what is known in the field, e.g. by adapting i.e. fine-tuning process parameters such as temperature, concentration of reactants, ... of this reaction). Indeed, if needed or desirable, steam should preferably be added to the reactor for the water-gas shift reaction to occur to the desired extent (H2O reacting with CO to generate CO2 and H2).

[0034] Advantageously, a dedicated boiler for production of steam is not required for the sorption-enhanced water-gas reactor, using the heat recovery steam generator of a coke dry quenching plant. Moreover, the sorption-enhanced water-gas shift reactor does not require additional fuel for the production of steam (or in any case a much-reduced amount with respect to a conventional method), further reducing fuel consumption and CO2 emissions of the industrial plant.

[0035] According to the same or other embodiments, the blast furnace gas is fed to the cooling chamber of the coke dry quenching unit at a temperature below 100 °C, such as from about 70 °C to 30 °C, preferably of about 50 °C or about 40 °C. Such a low temperature with respect to the temperature of a conventional coke dry quenching gas advantageously allows for a reduced flow rate of quenching gas (e.g. from 1450 Nm3 / Tcoke for a quenching gas at a temperature of about 140 °C to 1100 Nm3 / Tcoke).

[0036] As already mentioned above, the present inventive method allows the formation of a H2-rich stream which may rather easily, yet efficiently be turned into an essentially pure hydrogen stream, using conventional treatment steps, in case the purity respectively the amount of hydrogen in the H2-rich stream is deemed not sufficient for the intended downstream utilization thereof. Advantageously, such a H2- rich stream or essentially pure H2 stream may be locally used, i.e. consumed within the industrial installation, thereby greatly alleviating transport and storage requirements generally known to hamper its use.

[0037] Indeed, hydrogen production and / or import is very expensive and difficult, requiring specific infrastructure for hydrogen storage and transport, which currently limit its use to some specific, high added-value applications with low production volume. Locally producing hydrogen could lessen or eliminate the need of a further device within the installation for a reducing gas / fuel obtained from a carbon containing gas such as e.g. natural gas, in turn further reducing the CO2-emissions of theinstallation. In embodiments, the H2-rich stream exiting the sorption-enhanced water- gas shift reactor may be directly (or indirectly through a N2 and / or H2O removal unit) fed to a direct reduction reactor and / or to a blast furnace (preferably the blast furnace producing the blast furnace gas being fed to the cooling chamber of the coke dry quenching unit). In (the same or alternative) embodiments, the H2-rich stream exiting the sorption-enhanced water-gas shift reactor may be directly (or indirectly through a N2 and / or H2O removal unit) fed to other industrial plant e.g. to be used as reactant for the production of chemicals such as ammonia or e-fuel.

[0038] For example, regarding injection in a blast furnace, from 0.1 vol.-% up to 1 vol.-%. of H2 demand of recent process of blast furnace with H2 injection may be met by the H2 locally produced. Additionally, the stream of enriched blast furnace gas exiting the cooling chamber of the coke dry quenching unit may advantageously be subjected to a dedusting step (i.e. be dedusted) upstream of the sorption-enhanced water-gas shift reactor, such as - depending on the embodiments - upstream and / or downstream of the heat recovery steam generator. Alternatively or additionally, the stream of enriched blast furnace gas may be compressed prior to being fed to the sorption-enhanced water-gas shift reactor (such as e.g. - if applicable - downstream of a deduster / dedusting unit and of the heat recovery steam generator.

[0039] According to another aspect, the present invention relates to an industrial installation comprising a source of a source of blast furnace gas, a coke dry quenching unit and a sorption-enhanced water-gas shift reactor, wherein the source of the stream of blast furnace gas is in fluidic communication with a gas inlet of a cooling chamber of the coke dry quenching unit; and wherein a gas outlet of the cooling chamber is in fluidic communication with an inlet of the sorption-enhanced water-gas shift reactor. In particular, the present invention relates to an installation (configured) for implementing the method according to the first aspect. Specific embodiments of the installation are recited in the appended claims, and advantages recited with respect to the method mutatis mutandis apply to the installation.

[0040] In some preferred embodiments, the installation comprises a control unit configured for controlling at least one of:- a temperature of the blast furnace gas upstream of the cooling chamber of the coke dry quenching unit,- a flow rate of the blast furnace gas upstream of the cooling chamber of the coke dry quenching unit,- a temperature of enriched blast furnace gas downstream of the cooling chamber of the coke dry quenching unit and upstream of the sorption-enhanced water-gas shift reactor,- a composition of a gas exiting the sorption-enhanced water-gas shift reactor,- a temperature of the enriched blast furnace gas exiting the heat recovery steam generator,- a flow rate of steam between the heat recovery steam generator and the sorption-enhanced water-gas shift reactor, and- a temperature of steam between the heat recovery steam generator and the sorption-enhanced water-gas shift reactor.

[0041] Advantageously, the control unit allows for a fine-tuning of the operating conditions of the sorption-enhanced water-gas shift reactor so as to optimize (i.e. maximize) hydrogen production. While the amount of CO fed to the sorption-enhanced water-gas shift reactor may not be readily, finely and / or instantly adaptable / tunable, controlling the amount and temperature of steam injected into the sorption-enhanced water-gas shift reactor may allow a full conversion of carbon monoxide CO into carbon dioxide CO2, thereby optimizing the reaction conditions and maximizing the yield of hydrogen H2 (as all CO will react, maximum yield of H2 will be achieved).

[0042] The control unit may also be configured for controlling the purification of the H2-rich stream in order to produce essentially pure H2, e.g. for monitoring the amount of water removal from the H2-rich stream and adapt (feedback loop) the amount of steam fed to the sorption-enhanced water-gas shift reactor, so as to maximize H2 production without unduly increasing H2O content of the H2-rich stream.

[0043] In embodiments, the sorption-enhanced water-gas shift reactor may be operated such as disclosed e.g. in EP 3 967 653 A1 .

[0044] “About” in relation with a numeric, means that said numeric value explicitly covers a range of values from -10 % to + 10% of said numeric value, preferably a range of values from -5 % to +5 % of said numeric value or even a range of values from -2.5 % to +2.5 % of said numeric value.Brief Description of the Drawings

[0045] Further details and advantages of the present invention will be apparent from the following detailed description of non-limiting embodiments with reference to the attached drawing, wherein Fig. 1 is a diagram illustrating one embodiment of an industrial installation configured for implementing the present method.Description of Preferred Embodiments

[0046] Figure 1 shows a diagram of a plant 10 configured for implementing the present method. The two main component of the plant 10 are a coke dry quenching (CDQ) plant 20 and a sorption-enhanced water-gas shift reactor 40.

[0047] A blast furnace (not shown) produces a blast furnace gas 12, which is at least partially sent to the cooling chamber 24 of a coke dry quenching unit 22 in the CDQ plant 20, to cool the hot coke produced by a coke oven battery (not shown). As known in the art, the blast furnace gas exiting the blast furnace may be subjected to a gas cooling / and or cleaning step prior to being fed to the cooling chamber 24 in the CDQ unit 22. The blast furnace gas is injected at the bottom of the cooling chamber 24 of the CDQ unit, crossing the coke bed from the bottom to the top of the cooling chamber 24. The hot coke is charged from the top of the cooling chamber and is discharged from the bottom, as in conventional CDQ technology.

[0048] In embodiments, considering a coke rate of 345 Tcoke / THM (tonne hot metal, tonne = metric ton) and a blast furnace gas (BFG) production of 1700 Nm3 / THM, the available BFG to cool down the coke is 4900 Nm3 / Tcoke. About 1400 Nm3 / Tcoke equivalent to 28 vol.-% of available BFG is injected to the cooling chamber.

[0049] The BFG is preferably injected at a temperature of about 40 to 50 °C and collects the heat of the hot coke in the cooling chamber, thereby increasing its temperature to about 700 °C.

[0050] The BFG during its path toward the outlet of the cooling chamber 24 collects the coke dust present in the hot coke and the residual volatile matter (here below called VM) of coke, mainly composed by H2. The amount of H2 released depends from many factors like coke quality and coke distillation process in the coke oven battery, but may be estimated to result in an increase of about 0.5 vol.-% of the H2 content in the blast furnace gas.

[0051] After exiting the cooling chamber of the CDQ unit, the now hot enriched BFG enters a first dust removal unit 26 for removal of coarse part of coke breeze. Typical compositions of blast furnace gas and enriched blast furnace gas are given in Table 1 below.

[0052] Table 1

[0053] Downstream of the first dust removal unit 26, the hot enriched blast furnace gas is fed to a heat recovery steam generator 28, where heat from the BFG generates high pressure steam 13, having a pressure of about 100 bar and a temperature of about 500 °C. The enriched blast furnace gas 14 exits the heat recovery steam generator 28 as a cooled enriched BFG with a temperature of about 165 °C.

[0054] The cooled enriched BFG enters a second heat exchange 30 in order to further cool it down to a temperature of about 80-100 °C and at the same time to preheat boiler feed water 15 which will enter a deaerator system 32 for the heat recovery steam generator unit 28.

[0055] The further cooled enriched BFG 16 enters a secondary dust catcher unit 34 (or dust removal unit), in order to remove all residual dust present in the BFG and achieve a residual dust level suitable / acceptable for a compressor 42 arranged upstream of the sorption-enhanced water-gas shift reactor 40 (from 10 to 20 barg).

[0056] Compressed enriched blast furnace gas 17 is fed to the sorption- enhanced water-gas shift reactor 40 to be treated as per standard SEWGS technology to produce a H2-rich stream 44 and a CO2-rich stream 46. However, compared to the standard SEWGS technology the content of H2 is increased and CO2 contained in the BFG or resulting from its (partial) conversion into CO (due to the so-called coke loss) during coke dry quenching followed by its reconversion into CO2 in the water-gas shiftreaction is included in BFG for removal in the sorption-enhanced water-gas shift reactor, thereby reducing CO2 emissions.

[0057] The high-pressure steam 13 generated by the heat recovery steam generator 28 is fed to a steam turbine 38 to expand the steam up to a pressure of about 70 bar producing electric energy M. Such energy is sent to power stations for use within the industrial installation and / or may e.g. (partially) be used by the compressor 42 of the SEWGS unit, reducing the energy requirement of this compressor.

[0058] The reduced pressure steam 18 may further be used by the sorption- enhanced water-gas shift unit 40 at the operating pressure of the system.

[0059] Simulations have been carried out for multiple examples to determine the coke loss and H2 production of an installation operated by a method according to the present invention and by a comparative method using conventional quenching gas.

[0060] Before entering in the detail of comparison of H2 enrichment in case of different cooling gas and operating condition, it is necessary to explain the phenomena of H2 enrichment during coke quenching and the reference value assumed for the calculation.

[0061] The phenomena of H2 production during coke quenching are due to two effects:- Volatile matter produced by hot coke during quenching.- Chemical reaction of cooling gas with hot coke.

[0062] Phenomenon 1 - Volatile matter is stripped

[0063] The first phenomenon is due to the residual volatile matter contained in the coke being stripped by the cooling gas (i.e. quenching gas) during the cooling phase (i.e. coke dry quenching). This stripped volatile matter is mainly composed by H2. Based on the inventors past experience, the volatile matter released by the coke is from 2,7 to 18 Nm3-H2 / T- coke quenched. Many parameters of the coking process have an influence in this value, but it depends neither on the type and chemical composition nor on the flow rate of the quenching gas. As per the inventors’ experience, the most common value is about 6 Nm3 / T-coke. It shall be highlight that in case of high volatile matter being produced, the released gas may comprise not only H2but also methane CH4. For this reason, the value of 6 Nm3 / T-coke seems to be the most realistic value.

[0064] As indicated above this H2 production is independent from the type (i.e. nature) of the quenching gas, meaning that this contribution is valid for BFG as well as any other quenching gas.

[0065] Considering a traditional CDQ process, the amount of gas used is of about 1450 Nm3 / coke. In this case the percentage increase of H2 is equivalent to:6%AH2T= — — — -xl00 = 0.41 % 7 1450 + 6

[0066] Considering the above indicated range of VM released by coke the increase of H2 can be from 0.18 vol.-% up to 1.23 vol.-%.

[0067] Now considering the present inventive CDQ process, since the quenching gas circuit is open and the temperature of BFG circuit is lower (assumed at about 40 °C is these simulations), the amount of BFG used to cool down the coke at the same target as per conventional CDQ process (i.e. 160 tph) is 1100 Nm3 / t-coke. In this case, the percentage increase of H2is equivalent to:

[0068] Considering the range above indicated of VM released by coke the increase of H2 can be from 0.24 vol.-% up to 1.61 vol.-%.

[0069] Phenomenon 2 - Chemical reactions

[0070] The second phenomenon is a set of chemical reactions between hot coke and cooling (i.e. quenching) gas, in which the carbon component of coke in solid state become CO in gas state (which may be similar to a “gasification of coke”). In particular the chemical compositions vary through the following reactions:Boudouard reaction: C + CO2 ±52 COCoke water gas reaction: C + H2O *5 H2 + CO

[0071] The above chemical reactions occur in parallel during coke cooling (i.e. quenching), depending on the actual temperature, pressure, gas flow rate and chemical composition of the cooling gas, in particular the H2O and CO2 content in the gas.

[0072] In traditional CDQ process the amount of gasified coke (called coke loss) in managed by injection of a certain amount of combustion air in the system. The main target is to keep the H2and CO percentage below the explosion limit (namely below 5 vol.-% of H2and 8 vol.-% CO) and reduce the coke loss below a certain value (between 1 % to 1.4 vol. -% of coke inlet). Ensuring a minimal, non-zero coke loss (typically of about 1 %) even at low flow rate in conventional CDQ process advantageously provides a minimum steam production for a CDQ steam boiler.

[0073] The theoretical calculation of H2increase in CDQ traditional process is based on a simulation model considering thermodynamics equilibrium of the above- mentioned reactions. As a result, only a certain amount of H2O is converted into H2and a certain amount of CO2is converted into CO. The increase of H2component in the cooling gas of conventional CDQ process is between 16.61 Nm3 / T-coke and 23.26 Nm3 / T-coke, which is equivalent to 1 .13 vol. -% to 1 .57 vol.-%.

[0074] In the present inventive method, some important differences are present. The first difference is the chemical composition of the quenching gas, which are quite different as presented in Table 2 below.

[0075] Table 2

[0076] The amount of H2O is much lower in BFG than in conventional CDQ cooling gas, meaning that the maximum amount of H2 generated during coke quenching is lower than in conventional CDQ process.

[0077] The second difference is the temperature of the gas at the injection (i.e. entry / inlet) of the of cooling chamber of the CDQ unit. BFG is injected at a temperature around 40 °C instead of 140 °C. As a result, since the target of the CDQ plant is to cool down the coke up to a target temperature of 160°C, the amount of BFG requiredper tonne of coke is reduced to 1100 Nm3 / Tcoke, instead of 1450 Nm3 / Tcoke required when using conventional CDQ quenching gas. With a lower gas flow rate, the temperature of the BFG exiting the cooling chamber will be higher (because the thermal energy removed from the coke will remain the same and BFG flowrate is lower), making the BFG substantially more reactive than conventional CDQ quenching gas. This means that the reactivity of H2O and CO2 with coke is expected to be higher.

[0078] The above two effect are opposite to each other. To make an estimation of H2production it is assumed the same amount of H2O and CO2typical of traditional CDQ process will react with coke in conventional process and according to the present inventive method.

[0079] The increase of H2content in the new CDQ process using BFG as quenching gas is about 5.56 Nm3 / T-coke equivalent to about 0.50 vol.-% of H2content in the BFG. Regarding the coke loss, calculation show a value of about 0.45 vol.-%.

[0080] Another simulation has also been carried out assuming a different composition of the BFG. The H2O content is the amount relevant to the saturation at the available temperature of BFG. The temperature of BFG can range according to the environmental condition but since the variation is very small, the H2O amount in the gas can have only small variation, resulting in a non-significant variation of H2 production. The CO2 content can vary in a range of ± 5 vol.-%, which change the coke loss rate of ± 0.03 vol.-% without significantly varying the H2 generation.

[0081] Yet another simulation has also been carried out reducing the reactivity of H2O and CO2. In this scenario, the H2 generation is 2.81 Nm3 / T-coke t equivalent to an H2 increase of 0.23 %. In this scenario the coke loss is increased to 0.52 vol.-%, which is 0.07 % more than according to the reference scenario. This scenario indicates the strong sensitivity of H2O content and reaction activity for H2 generation and the low effect of CO2 content in the BFG.

[0082] The opposite simulation has also been carried out, by increasing the reactivity of H2O and CO2. In this scenario, the H2 generation is 9.6 Nm3 / T-coke which is equivalent to an H2 increase of 0.89 vol.-%. In this scenario the coke loss is still increase to 0.51 vol.-%, which is 0.06 vol.-% more than according to the reference scenario.

[0083] Conclusion

[0084] In conclusion, the H2 generation inside a CDQ unit using BFG as quenching gas, according to the most realistic scenario, will increase the content of H2 in the BFG used in the process of about 11 .56 Nm3 / T-coke, equivalent to an increase of 1 .04 vol.-% of H2 content in the BFG. Considering the lowest and highest generation scenario, the increase of H2 is from 5.51 to 27.6 Nm3 / T-coke, equivalent to an increase from 0.47 to 2.7 vol.-% of H2 content in the BFG.

[0085] Finally, from the above simulations, the amount of coke loss generated by use of BFG is much lower than in conventional CDQ process (0.45 vol.-% for new process versus 1 vol-% for traditional CDQ process). In the worst condition, assuming a different reaction balance compared to conventional CDQ process, the coke loss rate according to the present inventive method is almost half of the coke loss in conventional CDQ process (0.52 % versus 1.00 %).

[0086] Legend

Claims

Claims1 . A method of operating an industrial installation comprising a source of blast furnace gas, a coke dry quenching unit and a sorption-enhanced water-gas shift reactor, the method comprising the ordered steps of: a) feeding a stream of blast furnace gas from the source of blast furnace gas to a cooling chamber of the coke dry quenching unit to quench coking reaction; b) collecting a stream of enriched blast furnace gas exiting the cooling chamber; and c) feeding the collected stream of enriched blast furnace gas to the sorption- enhanced water gas shift reactor thereby producing a CCh-rich stream and a H2-rich stream.

2. The method as claimed in claim 1 , wherein the enriched blast furnace gas is fed to a heat recovery steam generator between step b) and step c).

3. The method as claimed in claim 2 wherein part of the steam produced by the heat recovery steam generator is fed to the sorption-enhanced water-gas shift reactor.

4. The method as claimed in any one of claims 1 to 3, wherein the blast furnace gas is fed to the cooling chamber of the coke dry quenching unit at a temperature below 100 °C, preferably of about 50 °C or about 40 °C.

5. The method as claimed in any one of claims 1 to 4, wherein the H2-rich stream is fed to a blast furnace.

6. The method as claimed in any one of claims 1 to 5, wherein the H2-rich stream is fed to a direct reduction furnace.

7. The method as claimed in any one of claims 1 to 6, wherein the stream of enriched blast furnace gas is compressed prior to step c).

8. The method as claimed in any one of claims 1 to 7, wherein the stream of enriched blast furnace is dedusted between step b) and step c).

9. The method as claimed in claim 8 when depending on claim 2, wherein the stream of enriched blast furnace gas is submitted to a primary dedusting upstream of the heat recovery steam generator and is submitted to a secondarydedusting downstream of the heat recovery steam generator and upstream of the sorption-enhanced water-gas shift reactor.

10. An industrial installation comprising a source of a source of blast furnace gas, a coke dry quenching unit and a sorption-enhanced water-gas shift reactor, wherein the source of the stream of blast furnace gas is in fluidic communication with a gas inlet of a cooling chamber of the coke dry quenching unit; and wherein a gas outlet of the cooling chamber is in fluidic communication with an inlet of the sorption-enhanced water-gas shift reactor.

11. The installation as claimed in claim 10, wherein the installation implements and / or is configured for implementing the method as claimed in any one of claims 1 to 9.

12. The installation as claimed in claim 10 or 11 , further comprising a control unit configured for controlling at least one of: a temperature of the blast furnace gas upstream of the cooling chamber of the coke dry quenching unit, a flow rate of the blast furnace gas upstream of the cooling chamber of the coke dry quenching unit, a temperature of enriched blast furnace gas downstream of the cooling chamber of the coke dry quenching unit and upstream of the sorption- enhanced water-gas shift reactor, a composition of a gas exiting the sorption- enhanced water-gas shift reactor.

13. The installation as claimed in any one of claims 10 to 12, further comprising a heat recovery steam generator arranged in fluidic communication between the coke dry quenching unit and the sorption-enhanced water-gas shift reactor.

14. The installation as claimed in claim 13, further comprising a compressor arranged in fluidic communication between the heat recovery steam generator and the sorption-enhanced water-gas shift reactor.

15. The installation as claimed in claim 13 or 14, further comprising a control unit configured for controlling at least one of: a temperature of the enriched blast furnace gas exiting the heat recovery steam generator, a flow rate of steam between the heat recovery steam generator and the sorption-enhanced water- gas shift reactor and a temperature of steam between the heat recovery steam generator and the sorption-enhanced water-gas shift reactor.

16. The installation as claimed in any one of claims 10 to 15, further comprising a first dust removal unit arranged in fluidic communication between the coke dry quenching unit and the sorption-enhanced water-gas shift reactor.

17. The installation as claimed in claim 16 when depending on claim 13, wherein the first dust removal unit is arranged in fluidic communication between the coke dry quenching unit and the heat recovery steam generator, and wherein the installation further comprises a second dust removal unit arranged in fluidic communication between the heat recovery steam generator and the sorption- enhanced water-gas shift reactor.

18. The installation as claimed in any one of claims 10 to 17, further comprising a blast furnace, wherein at least one gas inlet of the blast furnace is in fluidic communication with an outlet of the sorption-enhanced water-gas shift reactor.

19. The installation as claimed in any one of claims 10 to 18, further comprising a direct reduction furnace, wherein at least one gas inlet of the direct reduction furnace is in fluidic communication with an outlet of the sorption-enhanced water-gas shift reactor.

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