Method, tube bundle reactor and reactor system for carrying out catalytic gas phase reactions
A method for carrying out catalytic gas phase reactions including providing a tube bundle reactor which has a bundle of reaction tubes that are filled with a catalyst charge and are cooled by a heat transfer medium, conveying a reaction gas through the catalyst charge, the reaction gas flowing into each reaction tube divided into two part flows introduced in the axial direction of the reaction tube at different points in the catalyst charge the catalyst charge has at least two catalyst layers of different activity, wherein the activity of the first catalyst layer, in the flow direction of the reaction gas, is lower than the activity of the at least one other catalyst layer and in step a first part flow is introduced into the first catalyst layer and each further part flow is introduced past the first catalyst layer into the at least one further catalyst layer.
1. A tube bundle reactor, comprising:
a bundle of reaction tubes that are filled with a catalyst charge and through which a reaction gas flows during operation and which are cooled by a heat transfer medium;
a metering tube is embedded at least partially in the catalyst charge in each reaction tube and arranged coaxially thereto,
wherein the metering tube extends from a gas-inlet-side end of the catalyst charge a predefined length into the catalyst charge,
wherein an interior of the metering tube is catalyst-free,
wherein the metering tube has at least one gas inflow point outside the catalyst charge, and
wherein the metering tube has at least one first gas outflow point in a region of the catalyst charge,
wherein the at least one first gas outflow point in a flow direction of the reaction gas is arranged at a predefined distance from the gas-inlet-side end of the catalyst charge so that a partial flow of the reaction gas flowing into each reaction tube flows in a bypass to the catalyst charge there,
wherein:
a first catalyst charge of the catalyst charge has at least two catalyst layers of different activity,
the at least two catalyst layers contain a same catalyst material,
a first catalyst layer of the at least two catalyst layers in the flow direction of the reaction gas contains 5 vol. % to 90 vol. % of the catalyst material of a directly adjacent at least one second catalyst layer of the at least two catalyst layers, and
a first gas outflow point in the flow direction of the reaction gas of the at least one first gas outflow point opens into the at least one second catalyst layer,
wherein the catalyst material is a methanation catalyst.
2. The tube bundle reactor according to claim 1 ,
wherein the first catalyst layer comprises particles,
wherein in each reaction tube a ratio of an annular gap between an inner wall of the reaction tube and an outer wall of the metering tube to a particle diameter of the first catalyst layer lies in a range of 2 to 6.
3. The tube bundle reactor according to claim 1 , wherein:
an axial spacing between the at least one gas inflow point and the first gas outflow point in the flow direction of the reaction gas,
an axial spacing between the respective gas outflow points, and
an axial spacing between a last gas outflow point and an end of the metering tube and a number thereof
are each selected so that a heating surface loading due to reaction heat released between the gas inflow and outflow points is in a range of at least one of 10 kW/m 2 to 150 kW/m 2 and 20 kW/m 2 to 50 kW/m 2 .
4. The tube bundle reactor according to claim 1 , wherein a square ratio of an internal diameter of each reaction tube to an external diameter of the metering tube lies in a range of 2 to 6.
5. A reactor system, comprising:
a first reactor stage;
a condenser;
a heating zone; and
a second reactor stage which are all arranged consecutively in a flow direction of a reaction gas flowing through the reactor system, wherein
the first reactor stage is a tube bundle reactor comprising:
a bundle of reaction tubes that are filled with a catalyst charge and through which the reaction gas flows during operation and which are cooled by a heat transfer medium;
a metering tube is embedded at least partially in the catalyst charge in each reaction tube and arranged coaxially thereto,
an interior of the metering tube is catalyst-free and extends from a gas-inlet-side end of the catalyst charge into the catalyst charge a predefined length, and the metering tube has at least one gas inflow point outside the catalyst charge and at least one gas outflow point in a region of the catalyst charge,
wherein a first gas outflow point, of the at least one gas outflow point, in a flow direction of the reaction gas is arranged at a predefined distance from the gas-inlet-side end of the catalyst charge so that a partial flow of the reaction gas flowing into each reaction tube flows in a bypass to the catalyst charge there,
wherein:
a first catalyst charge of the catalyst charge has at least two catalyst layers of different activity,
the at least two catalyst layers contain a same catalyst material,
a first catalyst layer of the at least two catalyst layers in the flow direction of the reaction gas contains 5 vol. % to 90 vol. % of the catalyst material of a directly adjacent at least one second catalyst layer of the at least two catalyst layers, and
the first gas outflow point in the flow direction of the reaction gas opens into the at least one second catalyst layer,
wherein the reaction gas flowing into the reactor system is conveyed through the catalyst charge,
wherein the condenser is configured to cool the reaction gas flowing out of the tube bundle reactor to a temperature below a dew point of at least a portion of components of the reaction gas and to divert the at least the portion of condensed components,
wherein the heating zone is configured to heat the reaction gas from which a portion of the condensed components has been removed in the condenser; and
wherein the second reactor stage is a reactor with a second catalyst charge, through which the reaction gas flowing out from the heating zone is conveyed,
wherein the catalyst material is a methanation catalyst.
6. The reactor system according to claim 5 , wherein at least two components of the first reactor stage, the condenser, the heating zone, and the second reactor stage form a constructive unit.
7. The reactor system according to claim 5 , wherein the second reactor stage is a cooled reactor whose average heat transfer medium temperature is 0 K to 30 K lower than a heat transfer temperature of the reactor of the first reactor stage.
8. The reactor system according to claim 7 , wherein the second reactor stage is a tube bundle reactor having a bundle of reaction tubes filled with the second catalyst charge and through which a reaction gas flows during operation and which are cooled by a heat transfer medium.
9. The reactor system according to claim 8 , wherein the reaction tubes of the two reactors of the first and second reactor stages are located in a common heat transfer medium space.
10. The reactor system according to claim 5 , wherein the first catalyst layer of the at least two catalyst layers in the flow direction of the reaction gas contains 10 vol. % to 40 vol. % of the catalyst material of the directly adjacent at least one second catalyst layer of the at least two catalyst layers.
11. The reactor system according to claim 5 , wherein the methanation catalyst contains one or more VIII side group elements.
12. The reactor system according to claim 5 , wherein the methanation catalyst contains nickel.