DE102005038571A1 - Method and device for the selective catalytic reduction of nitrogen oxides in the exhaust gas of an internal combustion engine - Google Patents

Abstract

The inventive method for the selective catalytic reduction of nitrogen oxides (NOx) in the exhaust gas of an internal combustion engine (2) with a reducing agent, wherein at least one of the following reactants (5) is added: DOLLAR A a) a reducing agent and DOLLAR A b) a reducing agent precursor, DOLLAR A is characterized in that the amount of reactant (5) to be added is determined as a function of a conversion of reducing agent which is possible under given reaction conditions of the selective catalytic reduction of nitrogen oxides. DOLLAR A The method according to the invention and the device (1) according to the invention advantageously allow the consumption of reducing agents or reducing agent precursors to be reduced in the case of a selective catalytic reduction of nitrogen oxides. In mobile applications with selective catalytic reduction of nitrogen oxides, especially in exhaust systems (3) of automobiles, the consumption of reducing agent can advantageously be reduced and the interval between two filling processes of the reactant supply can be extended.

Description

object The present invention is a method and an apparatus for the selective catalytic reduction of nitrogen oxides in the exhaust gas an internal combustion engine. The inventive method and the device according to the invention can especially advantageously in exhaust systems of mobile Internal combustion engines, in particular in the exhaust system of automobiles, motorized two-wheelers, Water and / or aircraft are used.

Statutory regulations have been made in many countries around the world that set an upper limit for the content of certain undesirable substances in the exhaust gas of internal combustion engines. These are mostly substances whose release to the environment is undesirable. The emission of nitrogen oxides (NO _x ) to the environment is undesirable. The proportion of nitrogen oxides in the exhaust gas must fall below legally prescribed limit values in many countries. Due to the general conditions, for example the design of the internal combustion engines with regard to a favorable fuel consumption and the like, the internal engine avoidance of nitrogen oxide emissions to comply with the limits often not enough, so that at least for the maintenance of relatively low limits exhaust aftertreatment is required. It has been found that a selective catalytic reduction (SCR, selective catalytic reduction) of the nitrogen oxides is advantageous. This SCR method requires a reducing agent that is nitrogen-containing. In particular, the use of ammonia (NH ₃ ) as a reducing agent has proven to be a possible alternative. Due to the chemical properties and the legal regulations in many countries, ammonia is usually not kept as pure ammonia, as this can lead to problems especially in motor vehicles or other mobile applications. Rather, instead of storing the reducing agent itself, reducing agent precursors are often stored and carried in mobile applications.

Under a reducing agent precursor is here understood in particular a substance which the reducing agent split off or chemically converted into the reducing agent can. For example, for the reducing agent ammonia urea is a reducing agent precursor. Other possible Reducing agent precursor for ammonia as Reducing agents are, for example, ammonium carbamate, isocyanic acid and Cyanuric acid.

ever after dosing of the reducing agent or the reducing agent precursor can there is a so-called breakthrough of reducing agents, in the reducing agent by the reduction catalyst, in or on which the selective catalytic reduction of nitrogen oxides expires, passes through without being implemented. Such a breakthrough of reducing agents is basically undesirable because on the one hand the reducing agent itself an undesirable substance can represent, for example, because it is toxic, and on the other hand by the breakthrough consumption of reducing agent increases. Just in mobile applications, however, is the consumption of reducing agents a very critical point, since only limited volumes for storage of reducing agent and / or reducing agent precursor to disposal stand.

From Therefore, the invention is based on the object, a method and a device for the selective catalytic reduction of nitrogen oxides propose to avoid a breakthrough of the reducing agent and at the same time as good as possible implementation effectiveness the nitrogen oxides is reached.

These Task is solved by a method having the features of claim 1 and a device with the features of claim 8. Advantageous developments are the subject of the respective dependent claims.

• a) ein Reduktionsmittel und
• b) ein Reduktionsmittelvorläufer.

In the method according to the invention for the selective catalytic reduction of nitrogen oxides in the exhaust gas of an internal combustion engine with a reducing agent, at least one of the following reactants is added:

• a) a reducing agent and
• b) a reducing agent precursor.

According to the invention Amount of reagent to be added depending on a given at Reaction conditions of the selective catalytic reduction of Nitrogen oxides possible Sales of reducing agent determined.

Under a reducing agent precursor Here, in particular, a substance is understood, which is a reducing agent can split off or which are converted into a reducing agent can. A reducing agent comprises in particular a nitrogen-containing Substance, preferably ammonia. Possible Reducing agent precursor For example, urea, isocyanic acid, cyanuric acid and / or Ammonium carbamate. The reactant may in particular in the form of a Solid and / or an aqueous Solution added become.

Under reaction conditions are here understood in particular all conditions that have an influence on the position of the reaction equilibrium and / or the yield of the reduction reaction. According to the invention, the reaction conditions are preferably determined, in particular measured and / or calculated, and a maximum possible conversion of reducing agent determined on the basis of these reaction conditions taking into account the reaction kinetics.

Especially it may also be advantageous to have at least one reaction condition considering to calculate a measured value. In particular, then in the calculation the design of the exhaust system are taken into account. For example For example, a temperature before a reduction catalyst can be measured and in the calculation of the temperature of the reduction catalyst the thermal mass of the reduction catalyst and / or the thermal Mass of an upstream trained honeycomb body such as in particular a particle filter are taken into account. That means For example, that with a sudden increase in the exhaust gas temperature the exhaust gas in front of the reduction catalyst already has the higher temperature has, the reduction catalyst due to its thermal Mass, however, does not yet have this temperature. Especially can also the dynamics in the exhaust system and / or the operation of the internal combustion engine considered become.

Prefers this means that if the stoichiometric implementation of the Nitrogen oxides needed Amount of reducing agent greater than the amount of reducing agent that can be converted on the basis of the reaction kinetics is only the amount determined from the reaction kinetics to reducing agent or an appropriate amount of reducing agent precursor added becomes.

• 2.1) eine Reaktionstemperatur,
• 2.2) einen Abgasmassenstrom,
• 2.3) eine mittlere Abgasgeschwindigkeit und
• 2.4) eine Abgaszusammensetzung.

According to an advantageous development of the method according to the invention, the reaction conditions comprise at least one of the following variables:

• 2.1) a reaction temperature,
• 2.2) an exhaust gas mass flow,
• 2.3) has a mean exhaust gas velocity and
• 2.4) an exhaust gas composition.

Under a reaction temperature 2.1) is in particular the temperature a reduction catalyst understood on or in the one Selective catalytic reduction of nitrogen oxides takes place. Of the Exhaust gas mass flow 2.2) is in particular due to the operating state given the internal combustion engine, as well as the middle Exhaust gas velocity 2.3) and the exhaust gas composition 2.4). The Sizes 2.1), 2.2), 2.3) and / or 2.4), as well as other reaction conditions can in particular measured and / or calculated. A calculation can in particular taking into account the operating data of the internal combustion engine the configuration of the corresponding exhaust system done.

According to one further advantageous embodiment of the method according to the invention runs the selective catalytic reduction in a reduction catalyst, wherein the amount of reactant to be added as a function of at least one average temperature of the reduction catalyst is determined. in this connection is at least on the basis of the temperature of the reduction catalyst the maximum possible Amount of reducing agent determined in the reduction catalyst can be implemented. Is the stoichiometrically calculated amount reducing agent above this particular maximum amount, so only the maximum amount of reducing agent or only the corresponding amount of reducing agent precursor added.

Especially includes the reduction catalyst - like all others in the frame catalysts disclosed in this invention - a honeycomb body which for a Fluid can flow through channels having. A honeycomb body may in particular be a ceramic or a metallic honeycomb body. Metallic honeycomb body preferably comprise at least one at least partially structured metallic layer, in particular so twisted, entangled or is wound up for that an exhaust gas can flow through channels arise. The reducing agent catalyst may in particular a titanium dioxide (anatase) - supported vanadium / tungsten mixed oxide or metal exchanged ceelites, especially iron exchanged Ceolites, preferably of the type X, Y, ZSM 5, ZSM 11 and / or of the faujasite type include.

According to one further advantageous embodiment of the method according to the invention becomes a maximum amount of reducing agent based on the reaction conditions determined and the amount corresponding to the maximum amount of reducing agent added to the reagent.

A quantity of reducing agent is understood below to mean the amount of reducing agent which is determined as a function of the amount of nitrogen oxides to be reacted in the exhaust gas, which therefore in particular leads to a stoichiometric conversion of the nitrogen oxides present in the exhaust gas. The amount of nitrogen oxides can basically be measured and / or calculated. The calculation of the nitrogen oxide concentration as well as all other variables can be based, in particular, on the operating data of the internal combustion engine known from engine management. The maximum quantity can not be greater than the sales quantity, because the maximum quantity is the corresponding one Nitric oxide concentration flows. That is, according to the invention, the maximum amount is smaller than the conversion amount, if the reaction conditions allow only a partial conversion of the reducing agent. This is the case in particular if the temperature in the selective catalytic reduction, in particular the temperature of a corresponding reduction catalyst, is too small. If the reaction conditions are appropriate, in particular the temperature is correspondingly high, corresponds to the maximum amount of sales volume.

• 5.1) Harnstoff und
• 5.2) Ammoniak.

According to a further advantageous embodiment of the method according to the invention, the reaction medium comprises at least one of the following substances:

• 5.1) Urea and
• 5.2) Ammonia.

Basically the use of a nitrogenous reducing agent and a corresponding reducing agent precursor advantageous. Urea provides an easily stocked ammonia precursor as a reducing agent precursor. In particular, the urea can be stored as solid urea and added or in the form of an aqueous urea solution.

Especially when the reducing agent and / or the reducing agent precursor in Form of a liquid, for example in the form of a solution, preferably an aqueous Solution, stored and added, it is advantageous to continue this solution Add at least one substance, which is the freezing point of this solution or this substance is lowered. In the case of urea as a reducing agent precursor, which in the form of an aqueous solution, in particular ammonium formate may be added here. For ammonium formate it is the corresponding salt of formic acid. A appropriate solution is available under the brand name "Denoxium".

• 6.1) Messung und
• 6.2) Berechnung.

According to a further advantageous embodiment of the method according to the invention, the reaction conditions are determined in at least one of the following ways:

• 6.1) Measurement and
• 6.2) Calculation.

• 6.2) insbesondere im Rahmen der Motorsteuerung erfolgen und/oder die Daten der Motorsteuerung verwenden.

This applies to each of the above-mentioned reaction conditions 2.1), 2.2), 2.3) and 2.4), and for all other reaction conditions. The measurement can be carried out in each case by appropriately trained sensors, for example nitrogen oxide sensors and / or lambda probes, temperature sensors, flow meters and the like. The calculation can be carried out in each case in particular based on the engine operating data of the internal combustion engine. So can the calculation

• 6.2) take place in particular in the context of engine control and / or use the data of the engine control.

• 7.1) eine Aggregatszustandsänderung des Reaktionsmittels und
• 7.2) eine Umwandlung eines Reduktionsmittelvorläufers in ein Reduktionsmittel.

According to a further advantageous embodiment of the method according to the invention, a temperature reduction by at least one of the following operations is taken into account in step 6.2):

• 7.1) an aggregate state change of the reagent and
• 7.2) a conversion of a reducing agent precursor into a reducing agent.

Under an aggregate state change 7.1) is here in particular an evaporation of the reagent or a reagent solution Understood. Under a conversion 7.2) is in particular a hydrolysis and / or thermolysis of the reducing agent precursor in a reducing agent understood. In particular, it can be here to act on the hydro- and / or thermolysis of urea to ammonia.

• a) eines Reduktionsmittels und
• b) eines Reduktionsmittelvorläufers,

einen Reduktionskatalysator zur selektiven katalytischen Reduktion von Stickoxiden und eine Steuereinrichtung zur Steuerung der Reaktionsmittelzugabe. Erfindungsgemäß ist die Steuereinrichtung so ausgebildet, dass die durch die Reaktionsmittelzugabe zugegebene Menge an Reaktionsmittel so gesteuert wird, dass die Menge an Reduktionsmittel bei der selektiven katalytischen Reduktion kleiner oder gleich einer Maximalmenge an Reduktionsmittel ist, die abhängig von Reaktionsbedingungen im Reaktionskatalysator ist.According to a further aspect of the present invention, an apparatus for the selective catalytic reduction of nitrogen oxides (NO _x ) in the exhaust gas of an internal combustion engine is proposed which comprises a reagent addition for addition of at least one of the following reactants:

• a) a reducing agent and
• b) a reducing agent precursor,

a reduction catalyst for the selective catalytic reduction of nitrogen oxides and a control means for controlling the addition of reactant. According to the invention, the control means is arranged to control the amount of reactant added by the reactant addition so that the amount of reducing agent in the selective catalytic reduction is less than or equal to a maximum amount of reducing agent which is dependent on reaction conditions in the reaction catalyst.

• 9.1) eine Reaktionstemperatur,
• 9.2) einen Abgasmassenstrom,
• 9.3) eine mittlere Abgasgeschwindigkeit und
• 9.4) eine Abgaszusammensetzung.

According to an advantageous embodiment of the device according to the invention, the reaction conditions comprise at least one of the following variables:

• 9.1) a reaction temperature,
• 9.2) an exhaust gas mass flow,
• 9.3) has a mean exhaust gas velocity and
• 9.4) an exhaust gas composition.

Especially can these and other reaction conditions can be measured and / or calculated. A calculation may in particular be based on the data of the engine control the internal combustion engine.

• 10.1) Ammoniak und
• 10.2) Harnstoff.

According to a further advantageous embodiment of the device according to the invention, the addition of reactant is suitable for adding at least one of the following reactants:

• 10.1) ammonia and
• 10.2) Urea.

Under the suitability is understood in particular that corresponding Stockpiling and funding for the Reactant, ie in particular for ammonia and / or urea are formed. Furthermore, the suitability includes, for example, in Trap of a liquid Reactant, in particular a reagent solution, a corresponding nozzle or similar.

According to one further advantageous embodiment of the device according to the invention the controller is adapted to the reaction conditions to calculate.

According to one further advantageous embodiment of the device according to the invention are formed means for measuring the reaction conditions.

in this connection these may be, in particular, temperature sensors, lambda sensors, gas concentration sensors and / or flow meter act.

The inventive device is especially for the implementation the method according to the invention suitable. The for the inventive method disclosed advantages and details are transferable to the device according to the invention. and applicable. This also applies to in the context of the device according to the invention disclosed details and advantages that equally in the inventive transfer and applicable.

in the The invention will be explained in more detail below with reference to the attached figures, without that the invention is limited to the embodiments shown there. Show it:

1 Schematically an embodiment of a device according to the invention for the selective catalytic reduction of nitrogen oxides and

2 schematically a reducing agent mass profile against time.

• a) eines Reduktionsmittels und
• b) eines Reduktionsmittelvorläufers.

1 schematically shows an embodiment of a device according to the invention 1 for the selective catalytic reduction of nitrogen oxides (NO _x ) in the exhaust gas of an internal combustion engine 2 , The exhaust gases of the internal combustion engine 2 be in an exhaust system 3 delivered, which is the device 1 includes. The device 1 includes a reagent addition 4 for adding at least one of the following reactants 5 :

• a) a reducing agent and
• b) a reducing agent precursor.

The reducing agent is in particular a nitrogen-containing reducing agent and basically serves for the selective catalytic reduction of nitrogen oxides in a reduction catalyst 6 , Ammonia (NH ₃ ) is preferred as reducing agent and urea ((NH ₂ ) ₂ CO) as reducing agent precursor. In particular, the reducing agent precursor may be in solid form or in the form of an aqueous solution as a reactant 5 by the addition of reactant 4 be added. Furthermore, the device according to the invention comprises 1 a control device 7 for controlling the addition of reactant 4 , For this purpose, the control device 7 via a signal line 8th with the addition of reactant 4 or with a reagent supply unit 9 connected.

The reagent supply unit 9 in particular comprises a corresponding reservoir for the reagent and corresponding conveyor. In the case of a liquid reagent supply, the conveyor may in particular comprise a pump. In the case of addition of the reagent 5 As a solid, the conveyor may in particular comprise a suitable conveyor for a solid transport. Particularly preferred is the addition in the form of pellets or prills, if the reactant is added as a solid. Pellets or prills are understood to mean, in particular, small quantisable or separable reactant particles.

The control device 7 is in the present embodiment via further signal lines 8th also with the internal combustion engine 2 connected. The control device may be part of the engine management or also data from the engine management of the internal combustion engine 2 receive. According to the invention, it is possible that on the basis of the operating data and / or a known operating map of the internal combustion engine 2 Reaction conditions for the selective catalytic reduction of nitrogen oxides in the reduction catalyst 6 be calculated. This can be done for example on the basis of the data, in particular the operating parameters of the internal combustion engine, in particular also the design and design of the exhaust system 3 can be taken into account. Under reaction conditions are understood in particular a reaction temperature, an exhaust gas mass flow, an average exhaust gas velocity and / or an exhaust gas composition. All these are reaction conditions that influence the maximum possible amount of nitrogen oxides to be converted reduction catalyst 6 to have. On the basis of this maximum possible amount of nitrogen oxides to be reacted, a maximum amount of reducing agent in the reduction catalyst 6 certainly. Furthermore, a calculation of the amount of sales of reducing agent, which is necessary to the nitrogen oxides in the exhaust gas of the internal combustion engine 2 completely reduce. If this stoichiometrically determined amount of sales is greater than the maximum amount, then only the maximum amount of reducing agent or the corresponding amount of reactant 5 added.

In the present embodiment, as a reactant 5 Urea as reducing agent precursor for the reducing agent in the form of an aqueous urea solution via the addition of reactant 4 added to the exhaust stream. The reagent 4 then meets a hydrolysis catalyst 17 wherein, for example, a thermolysis of the urea ((NH ₂ ) ₂ CO) in ammonia (NH ₃ ) and isocyanic acid (HCNO) and hydrolysis of the isocyanic acid with water (H ₂ O) to ammonia and carbon dioxide (CO ₂ ): (NH ₂ ) ₂ CO -> NH ₃ + HCNO HCNO + H ₂ O -> NH ₃ + CO ₂

The resulting ammonia then serves as a reducing agent in the reduction catalyst 6 where it reacts with nitrogen monoxide (NO) and / or nitrogen dioxide (NO ₂ ) to nitrogen (N ₂ ) and water.

In the method according to the invention and the device according to the invention, it is advantageously possible to reduce the transit time of the exhaust gas from the internal combustion engine 2 to the reduction catalyst 6 to make use of, so that the data of present at any time t nitrogen oxide emissions of the internal combustion engine 2 as the basis for the calculation of sales data on the reduction catalyst 6 serve at a time t + .DELTA.t, wherein the time interval .DELTA.t substantially the duration of the exhaust gas from the internal combustion engine 2 to the reduction catalyst 6 represents. This transit time can be based on the data of the internal combustion engine with knowledge of the configuration of the exhaust system 3 be calculated. For this purpose, data about the exhaust gas mass flow and the average exhaust gas velocity can also be used.

Furthermore, in the present embodiment, means for measuring the reaction conditions are formed. These include in particular a nitrogen oxide sensor 10 , a first temperature sensor 11 and a second temperature sensor 12 , With the help of the first temperature sensor 11 the exhaust gas temperature can be determined while the second temperature sensor 12 the determination of the temperature in the reduction catalyst 6 serves. The means presented here for measuring reaction conditions 9 . 10 . 11 may be formed individually or in any combination with each other also in combination with other sensors such as in particular lambda sensors and / or reducing agent concentration sensors.

2 shows schematically mass progressions M against the time t. Both the mass and the time are given in relative units. A first mass course 13 indicates the amount of reducing agent per unit time required due to the amount of nitrogen oxides contained in the exhaust gas to substantially fully convert this amount. A second mass course 14 indicates maximum amount of reducing agent which can be maximally reacted due to the reaction conditions. first 13 and second mass course 14 are identical in some time intervals. 2 shows that there are time intervals 15 . 16 are in which the first mass profile above the second mass profile 14 lies. This means that for the stoichiometric conversion of the nitrogen oxides more reducing agent would have to be added than on the reduction catalyst 6 can be implemented. If this were done, this would lead to a breakthrough of the reducing agent by the reduction catalyst 6 would be done. In the case of ammonia as a reducing agent, this would mean that unreacted ammonia is the reduction catalyst 6 would leave. This increases the consumption of reducing agent, which is a disadvantage, in particular in mobile applications, since the amount of reactant to be entrained is limited by the installation space. Therefore, this would mean that the reagent supply would have to be replenished faster than if it did not come to the breakthrough of ammonia. Therefore, here according to the invention in the time intervals 15 . 16 the amount of reducing agent through the second mass profile 14 and thus limits the maximum amount. Although there is thus an incomplete conversion of nitrogen oxides, but they could not be reacted with a further increased amount of reducing agent, since the reaction conditions allow only the implementation of the maximum amount of reducing agent. Therefore, the method according to the invention and the device according to the invention advantageously result in the consumption of reducing agent and thus of the reaction agent being the same with the same nitrogen oxide conversion efficiencies 5 is lowered. In the times when the first mass course 13 essentially identical to the second mass profile 14 is, the addition of reactant is carried out according to the first mass profile 13 , that is, the sales volume.

The inventive method and the inventive device 1 allow advantageously reduce the consumption of reducing agent or reducing agent precursor in a selective catalytic reduction of nitrogen oxides. In mobile applications with selective catalytic reduction of nitrogen oxides, especially in exhaust systems 3 of automobiles, it is thus advantageously possible to reduce the consumption of reducing agent and thus to lengthen the interval between two replenishment processes of the reagent supply. Under mobile applications are understood in particular automobiles, motorized two-wheelers, watercraft and aircraft.

1

contraption for the selective catalytic reduction of nitrogen oxides

2

Internal combustion engine

3

exhaust system

4

Reagent addition

5

reactant

6

reduction catalyst

7

control device

8th

signal line

9

Reaktionsmittelzuführeinheit

10

nitrogen oxide sensor

11

first temperature sensor

12

second temperature sensor

13

first mass History

14

second mass History

15

time interval

16

time interval

17

hydrolysis catalyst

Claims (12)

Process for the selective catalytic reduction of nitrogen oxides (NO _x ) in the exhaust gas of an internal combustion engine ( 2 ) with a reducing agent, wherein at least one of the following reactants ( 5 a) a reducing agent and b) a reducing agent precursor, characterized in that the amount of reactant to be added ( 5 ) is determined as a function of a given reaction conditions of the selective catalytic reduction of nitrogen oxides possible conversion of reducing agent. Process according to claim 1, wherein the reaction conditions include at least one of the following sizes: 2.1) a reaction temperature, 2.2) an exhaust gas mass flow, 2.3) a mean exhaust gas velocity and 2.4) an exhaust gas composition. Method according to one of the preceding claims, in which the selective catalytic reduction in a reduction catalyst ( 6 ), the amount of reactant to be added ( 5 ) as a function of at least one average temperature of the reduction catalyst ( 6 ) is determined. Method according to one of the preceding claims, in which a maximum amount of reducing agent is determined on the basis of the reaction conditions and the amount of reactant corresponding to the maximum amount of reducing agent ( 5 ) is added. Method according to one of the preceding claims, in which the reaction agent ( 5 ) comprises at least one of the following substances: 5.1) urea and 5.2) ammonia. Method according to one of the preceding claims, in the reaction conditions in at least one of the following ways be determined: 6.1) Measurement and 6.2) Calculation. A method according to claim 6, wherein in step 6.2) a temperature decrease is taken into account by at least one of the following operations: 7.1) an aggregate state change of the reagent ( 5 ) and 7.2) a conversion of a reducing agent precursor into a reducing agent. Contraption ( 1 ) for the selective catalytic reduction of nitrogen oxides in the exhaust gas of an internal combustion engine ( 2 ), comprising a reagent addition ( 4 ) for adding at least one of the following reactants ( 5 ): a) a reducing agent and b) a reducing agent precursor, a reducing catalyst ( 6 ) for the selective catalytic reduction of nitrogen oxides and a control device ( 7 ) for controlling the addition of reactant ( 4 ), characterized in that the control device ( 7 ) is designed so that by the reagent addition ( 4 ) added amount of reagent ( 5 ) is controlled so that the amount of reducing agent in the selective catalytic reduction is less than or equal to a maximum amount of reducing agent, which depends on reaction conditions in the reduction catalyst ( 6 ). Contraption ( 1 ) according to claim 8, wherein the reaction conditions comprise at least one of the following quantities: 9.1) a reaction temperature, 9.2) an exhaust gas mass flow, 9.3) an average exhaust gas velocity, and 9.4) an exhaust gas composition. Contraption ( 1 ) according to claim 8 or 9, wherein the reagent addition ( 4 ) is suitable, at least one of the following reactants ( 5 ): 10.1) ammonia and 10.2) urea. Contraption ( 1 ) according to one of claims 8 to 10, in which the control device ( 7 ) is suitable to calculate the reaction conditions. Contraption ( 1 ) according to one of claims 8 to 11, in which means ( 10 . 11 . 12 ) are designed to measure the reaction conditions.