![]() Exhaust gas after-treatment system and method for the exhaust gas after-treatment
专利摘要:
The exhaust gas after-treatment system (2) for an internal combustion engine, with a separator (4) comprising calcium-containing granulate arranged downstream of an internal combustion engine (1) for the chemisorption of sulphur oxides, and with an oxidation catalytic converter (3) arranged downstream of the internal combustion engine (1) and upstream of the separator (4) for the oxidation of SO2 into SO3. 公开号:DK201570197A1 申请号:DK201570197 申请日:2015-04-07 公开日:2015-10-26 发明作者:Andreas Döring;Plamen Toshev 申请人:Man Diesel & Turbo Se; IPC主号:
专利说明:
Exhaust gas after-treatment system and method for the exhaust gas after- treatment The invention relates to an exhaust gas after-treatment system. The invention furthermore relates to a method for the exhaust gas after-treatment. During combustion processes in stationary internal combustion engines, which are employed for example in power plants, and in combustion processes in non-stationary internal combustion engines, which are employed for example on ships, sulphur oxides such as SO2 and SO3 are created, wherein these sulphur oxides are typically formed during the combustion of sulphur-containing fossil fuels, such as coal, pit coal, brown coal, oil or heavy fuel oil. For this reason, such internal combustion engines are assigned exhaust gas after-treatment systems which in particular serve for the desuiphurisation of the exhaust gas leaving the internal combustion engine. For desulphurising the exhaust gas, absorptive methods are primarily known from the prior art, which as absorbent primarily use quicklime (CaO) or lime hydrate (Ca(OH)2) or calcium carbonate (CaCOs). In the process, dust or granulate is formed, wherein for removing the calcium sulphate dust from the exhaust gas filter devices have to be employed downstream of the desuiphurisation. From DE 36 03 365 C2 a method and an exhaust gas after-treatment system for the treatment of exhaust gas containing nitrogen oxides and dust are known In addition, so-called scrubbers are also employed for desuiphurisation, in which SO2 is removed from the exhaust gas with the help of water. The sulphur dioxides contained in the scrubbing water are subsequently neutralised with the help of bases such as for example NaOH. Prior to this neutralisation, oxidation of the scrubbed-out SO2 into SO3 is additionally carried out in most cases, since this promises better separation and allows the use of calcium compounds, which with S03 form CaS04 and can thus be precipitated. This is usually achieved by blowing air into the sump (US 4515754 A1). Starting out from this, the object of the present invention is based on creating a new type of exhaust gas after-treatment system and a new type of method for the exhaust gas after-treatment. This object is solved through an exhaust gas after-treatment system according to Claim 1. The exhaust gas after-treatment system for an internal combustion engine according to the invention comprises a separator having calcium-containing granulate arranged downstream of an internal combustion engine for the chemisorption of sulphur oxides and an oxidation catalytic converter arranged downstream of the internal combustion engine and upstream of the separator for the oxidation of SO2 into SO3. By using the separator it is possible to omit a filter device for removing calcium sulphate or sodium sulphate dust from the exhaust gas. The sulphur dioxides react with the calcium or sodium or magnesium-containing granulate of the separator and can be discharged via the granulate. The use of the oxidation catalytic converter for oxidation of SO2 into SO3 makes possible a short dwell time of the exhaust gas in the separator since the SO3 react more rapidly with the calcium or sodium or magnesium-containing granulate of the separator than the SO2. The exhaust gas after-treatment system according to the invention makes possible effective desuiphurisation of exhaust gas. According to an advantageous further development, the granulate in the separator comprises CaO and/or Ca(OH)2 and/or CaCOs and/or Na2C03 and/or MgO, wherein the grain size of the granulate is between 1 mm and 8 mm. Here, the separator is designed in particular as a cross flow separator with moving bed or fluidised bed. This makes possible particularly effective desuiphurisation of exhaust gas. According to an advantageous further development, a heating device is arranged upstream of the oxidation catalytic converter which heats the exhaust gas to a temperature of more than 350°C, preferably of more than 400°C, particularly preferably of more than 450°C, This makes possible a particularly effective oxidation of SO2 into SO3 and thus effective desulphurisation of exhaust gas. With an exhaust gas supercharged internal combustion engine, the oxidation catalytic converter is positioned upstream of a turbine of an exhaust gas turbocharger, wherein the separator is positioned downstream of the turbine of the exhaust gas turbocharger. Through the relatively high temperatures and pressures which are present upstream of the turbine the oxidation of SO2 into SO3 in the oxidation catalytic converter is favoured. According to a further advantageous further development, the exhaust gas after-treatment system comprises a device for introducing NH3-precursor substances (urea) or gaseous NH3 info the exhaust gas, which is arranged downstream of the oxidation catalytic converter. Desulphurisation of the exhaust gas can thereby be further improved. The method for the exhaust gas after-treatment according to the invention is defined in Claim 12. Preferred further developments of the invention are obtained from the subciaims and the following description. Exemplary embodiments of the invention are explained in more detail with the help of the drawing without being restricted to this. There it shows: Fig. 1: a block diagram of a first exhaust gas after-treatment system according to the invention; Fig. 2: a block diagram of a second exhaust gas after-treatment system according to the invention; Fiq. 3: a block diagram of a third exhaust qas after-treatment system according tfc/ J to the invention; and Fig. 4: a block diagram of a fourth exhaust gas after-treatment system according to the invention. The present invention relates to an exhaust gas after-treatment system for an internal combustion engine, for example for a stationary internal combustion engine in a power plant or for a non-stationary internal combustion engine employed on a ship. The exhaust gas after-treatment system is employed in particular on a marine diesel engine operated with heavy fuel oil. Fig. 1 shows a first exemplary embodiment of an exhaust gas after-treatment system 2 located downstream of an internal combustion engine 1, wherein the exhaust gas after-treatment system 2 comprises an oxidation catalytic converter 3 which is arranged downstream of the internal combustion engine 1. In the oxidation catalytic converter 3, SO2 reacts into SO3 according to the following reaction equation The following chemical elements are employed as active components in the oxidation catalytic converter 3 for the oxidation of SO2 into SO3: V (vanadium) and/or K (potassium) and/or Na (sodium) and/or Fe (iron) and/or Ce (cer) and/or Cs (ceasium) and/or oxides of these elements. The component of vanadium (V) amounts to more than 5 %, preferably more than 7 %, particularly preferably to more than 9 %. As base material· the oxidation catalytic converter 3 utilises ΊΠΟ2 (titanium oxide) and/or 81(¾ (silicon oxide), preferentially stabilised by WO3 (tungsten oxide). In addition, the exhaust gas after-treatment system 2 according to the invention comprises a separator 4 arranged downstream of the oxidation catalytic converter 3 comprising calcium or sodium or magnesium-containing granulate, the separator 4 preferentially being a moving bed reactor or fluidised bed reactor. The calcium or sodium or magnesium-containing granulate preferentially comprises CaO and/or Ca(OH)2 and/or CaCOs and/or Na2C02 or NaHCGa, MgO. Here, the sulphur oxides react with the calcium-containing granulate according to the following reaction equations, namely for Ca(OH)2 according to the following reaction equations and for CaCOa according to the following reaction equations and for Na2C03 and NaHCOs according to the following reaction equations and for MgO according to the following reaction equations Here it is significant according to the invention that SO3 reacts more rapidly with the calcium or sodium or magnesium-containing granulate than SO2, which is why the oxidation catalytic converter 3 for the oxidation of SO2 into SO3 is arranged downstream of the internal combustion engine 1 and upstream of the separator 4. Because of this the effectiveness of desulphurisation can be increased. Preferentially, oxidation of SO2 into SO3 takes place in the oxidation catalytic converter 3 in such a manner that downstream of the oxidation catalytic converter 3 the component of SO3 in ail sulphur oxides (SOx) in the exhaust gas amounts to at least 20 %, preferably to more than 40 %, particularly preferably to more than 60 %. In the separator 4, the sulphur oxides react with the granulate into calcium or sodium or magnesium sulphate, which can be discharged together with the granulate of the separator 4. The grain size of the granulate in the separator 4 amount to between 1 mm and 8 mm, preferentially to between 4 mm and 8 mm. Because of the relatively large grain size of the granulate the same, in addition, does not react with the sulphur oxides as far as to the centre, but consists in the core at least partially of components that have not yet reacted with sulphur oxide, which are then surrounded by a shell of calcium sulphate. The separator 4 is preferentially assigned a device in order to separate from the granulate calcium sulphate intercepted in the moving bed or fluidised bed via the granulate, which is discharged from the moving bed reactor or fluidised bed reactor together with the granulate. This device can for example be a drum peeler, a drum screen or a mill. The granulate freed of calcium sulphate can subsequently be returned to the separator 4 in order to thus form a granulate circuit and more effectively utilise the granulate. Fig. 2 shows a version of the invention in which the internal combustion engine 1 is shown as an exhaust gas supercharged internal combustion engine, in which the exhaust gas after-treatment system 2 accordingly comprises a turbine 5 of an exhaust gas turbocharger, in which exhaust gas leaving the internal combustion engine 1 is expanded for extracting mechanical energy. In the case of such an exhaust gas supercharged internal combustion engine, the oxidation catalytic converter 3 is arranged seen in flow direction of the exhaust gas upstream of the turbine 5, wherein the separator 4 is arranged downstream of the turbine 6. The high pressures and temperatures in the exhaust gas flow which are present upstream of the turbine 5 favour the oxidation of SO2 into SO3 in the oxidation catalytic converter 3. A further exemplary embodiment of an exhaust gas after-treatment system 2 according to the invention for an internal combustion engine is shown by Fig. 3, wherein the exhaust gas after-treatment system 2 of Fig. 3 just like the exhaust gas after-treatment system 2 of Fig. 1 comprises the oxidation catalytic converter 3 and the separator 4. In addition, the exhaust gas after-treatment system 2 of Fig. 3 comprises a heating device 6 arranged upstream of the oxidation catalytic converter 3, which heats the exhaust gas upstream of the oxidation catalytic converter 3 to a temperature of more than 350°C, preferably of more than 400°C, particularly preferably of more than 450°C. This favours the oxidation of SO2 into SO3 in the oxidation catalytic converter 3. A further exemplary embodiment of an exhaust gas after-treatment system 2 according to the invention for an internal combustion engine is shown by Fig. 4, wherein the exhaust gas after-treatment system 2 of Fig. 4 just like the exhaust gas after-treatment system 2 of Fig. 2 comprises the oxidation catalytic converter 3, the turbine 5, the separator 4 and additionaily a device 7 for introducing gaseous NH3 into the exhaust gas, wherein this device 7 for introducing the gaseous NFf3 into the exhaust gas is arranged downstream of the oxidation cataiytic converter 3, so that accordingly NH3 is introduced into the exhaust gas of the internal combustion engine 1 downstream of the oxidation catalytic converter 3. In the process it can be provided to introduce the NH3 into the exhaust gas flow either directly in gaseous form or to inject an NFf3-precursor substance such as for example urea into the exhaust gas flow and evaporate the same in the exhaust gas flow into NH3, Introducing gaseous NH3 into the exhaust gas flow downstream of the oxidation catalytic converter 3 has the advantage that the subsequent desuiphurisation can thereby be improved because of this. With the exhaust gas after-treatment systems 2 shown in Fig. 1 to 4 a multi-stage separator 4 preferentially designed as moving bed reactor or fluidised bed reactor can be employed in order to improve the separation of calcium or sodium or magnesium sulphate, wherein in particular when a multi-stage separator 4 is used, granulate of different grain size is used in the individual stages of the separator 4. Preferentially, a separator 4 designed as a cross flow separator is utilised. The exhaust gas after-treatment system 1 according to the invention allows effective desuiphurisation of exhaust gas by way of the method for the exhaust gas after-treatment according to the invention. For desulphurising exhaust gas with the help of the exhaust gas after-treatment system 2 according to the invention, exhaust gas leaving the internal combustion engine is initially conducted via an oxidation catalytic converter 3 in order to make possible oxidation of SO2 into SO3. Following this, the exhaust gas is conducted via a separator 4 comprising calcium-containing granulate. As described, desulphurisation of the exhaust gas can be improved by introducing NH3 into the exhaust gas. Oxidation of SO2 into SO3 can be improved by providing or utilising a high exhaust gas temperature. Reference is made to the explanations regarding Fig. 1 to 4. In addition to the use of granulate the separation with the help of exhaust gas scrubbers is also expedient, which are arranged downstream of a catalytic converter for the S02-oxidation. Because of this, the separation rate in the exhaust gas scrubber on the one hand is increased since SO3 is significantly better soluble in water than S02, as a result of which either the separation performance can be improved and/or the scrubber reduced in size. In addition, blowing air into the sump for the oxidation of SO2, as described in US 4515754 A1 can be omitted. List of reference numbers 1 Internal combustion engine 2 Exhaust gas after-treatment system 3 Oxidation catalytic converter 4 Separator 5 Turbine 6 Heating device 7 Device/ device for introducing gaseous NH3 into the exhaust gas
权利要求:
Claims (15) [1] 1. An exhaust gas after-treatment system (2) for an internal combustion engine, with an exhaust gas scrubber arranged downstream of an interna! combustion engine (1), or a separator (4) comprising calcium and/or sodium and/or magnesium-containing granulate for the chemisorption of sulphur oxides, and with an oxidation catalytic converter (3) arranged downstream of the internal combustion engine (1) and upstream of the separator (4) for the oxidation of SO2 into SO3. [2] 2. The exhaust gas after-treatment system according to Claim 1, characterized in that the granulate in the separator (4) comprises CaO and/or Ca(OH)2 and/or CaCOs and/or Na2C03 and/or NaHCOs- [3] 3. The exhaust gas after-treatment system according to Claim 1 or 2, characterized in that the grain size of the granulate is between 1 mm and 8 mm. [4] 4. The exhaust gas after-treatment system according to any one of the Claims 1 to 3, characterized in that the separator (4) is designed as moving bed reactor or fluidised bed reactor. [5] 5. The exhaust gas after-treatment system according to any one of the Claims 1 to 4, characterized in that the separator (4) is designed as a cross flow separator. [6] 8. The exhaust gas after-treatment system according to any one of the Claims 1 to 5, characterized in that the separator (4) is designed in multiple stages, wherein the grain sizes of the granulate in the individual stages of the separator (4) differ from one another. [7] 7. The exhaust gas after-treatment system according to any one of the Claims 1 to 8, characterized in that the oxidation catalytic converter (3) as active component for the oxidation of SO2 into SO3 comprises vanadium and/or potassium and/or sodium and/or iron and/or cer and/or ceasium and/or oxides of these elements, wherein the oxidation catalytic converter utilises titanium oxide and/or silicon oxide as base material preferentially stabilised by tungsten oxide. [8] 8. The exhaust gas after-treatment system according to any one of the Claims 1 to 7, characterized in that the oxidation catalytic converter (3) as active component comprises vanadium with a component of more than 5 %, preferably of more than 7 %, particularly preferably of more than 9 %. [9] 9. The exhaust gas after-treatment system according to any one of the Claims 1 to 8, characterized in that with an exhaust gas supercharged internal combustion engine the oxidation catalytic converter (3) is positioned upstream of a turbine (5) of an exhaust gas turbocharger, wherein the separator (4) is positioned downstream of the turbine (5) of the turbocharger. [10] 10. The exhaust gas after-treatment system according to any one of the Claims 1 to 9, characterized in that upstream of the oxidation catalytic converter (5) a heating device (6) is arranged, which heats the exhaust gas to a temperature of more than 35G°C, preferably of more than 400°C, particularly preferably of more than 450°C, [11] 11. The exhaust gas after-treatment system according to any one of the Claims 1 to 10. characterized by a device (7) for introducing gaseous NH3 into the exhaust gas flow, which is arranged upstream of the oxidation catalytic converter (5). [12] 12. The exhaust gas after-treatment system according to any one of the Claims 1 to 11, characterized in that the SCVSOx-ratio downstream of the SCVoxidation catalytic converter amounts to at least 0,4, preferably to at least 0.5, most preferably to at least 0.6. [13] 13. The exhaust gas after-treatment system according to any one of the Claims 1 to 12, characterized in that the sulphate layer of the granulate is removed and said granulate returned upstream of the separator and/or into the separator. [14] 14. A method for the exhaust gas after-treatment of exhaust gas leaving an internal combustion engine, wherein the exhaust gas is conducted via an oxidation catalytic converter (3) for the oxidation of SO2 into SO3 and subsequently via a separator (4) comprising calcium-containing granulate for the chemisorption of sulphur oxides. [15] 15. The method according to Claim 14, characterized in that the same is carried out with the help of the exhaust gas after-treatment system according to any one of the Claims 1 to 13.
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同族专利:
公开号 | 公开日 DK179598B1|2019-02-26| CN105089744A|2015-11-25| FI20155247A|2015-10-09| KR20150116789A|2015-10-16| DE102014005150A1|2015-10-08| FI127391B|2018-04-30| KR102271576B1|2021-07-02|
引用文献:
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法律状态:
2019-02-26| PME| Patent granted|Effective date: 20190226 |
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申请号 | 申请日 | 专利标题 DE102014005150.1|2014-04-08| DE102014005150.1A|DE102014005150A1|2014-04-08|2014-04-08|Exhaust after-treatment system and exhaust aftertreatment process| DE102014005150|2014-04-08| 相关专利
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