An ammonia converter, wherein the ammonia converter has a casing, wherein the ammonia converter has a starting material inlet and a product outlet, wherein the ammonia converter has at least a first catalyst bed and a second catalyst bed, wherein the flow passes through the first catalyst bed and the second catalyst bed radially from the outside to the center, wherein the ammonia converter has at least one heat exchanger, wherein the heat exchanger is designed as a tube bundle heat exchanger, wherein the tube bundle heat exchanger has a central tube and a plurality of heat exchanging tubes, wherein the heat exchanging tubes are arranged parallel to the central tube and around the central tube, wherein the tube bundle heat exchanger has a deflection device, wherein the deflection device is arranged between the heat exchanging tubes and the central tube in terms of flow, wherein the tube bundle heat exchanger is surrounded in a ring shape by the first catalyst bed such that the gas mixture heated by the reaction in the first catalyst bed is fed to the tube bundle heat exchanger and thus heats the gas mixture inside the heat exchanging tubes, characterized in that the heat exchanger is a co-current flow heat exchanger, which is configured in such a way that, in said heat exchanger, the gas flow through the heat exchanging tubes is guided in the same direction as the gas flow flowing around the heat exchanging tubes, wherein the starting material inlet is directly connected to the heat exchanging tubes in terms of gas flow, wherein the deflection device is configured to guide the gas flow out of the heat exchanging tubes into the central tube, such that the flow through the central tube is in the opposite direction to the flow through the heat exchanging tubes, wherein the central tube is directly connected to the space between the casing and the first catalyst bed in terms of gas flow. wherein the ammonia converter has a casing, wherein the ammonia converter has a starting material inlet and a product outlet, wherein the ammonia converter has at least a first catalyst bed and a second catalyst bed, wherein the flow passes through the first catalyst bed and the second catalyst bed radially from the outside to the center, wherein the ammonia converter has at least one heat exchanger, wherein the heat exchanger is designed as a tube bundle heat exchanger, wherein the tube bundle heat exchanger has a central tube and a plurality of heat exchanging tubes, wherein the heat exchanging tubes are arranged parallel to the central tube and around the central tube, wherein the tube bundle heat exchanger has a deflection device, wherein the deflection device is arranged between the heat exchanging tubes and the central tube in terms of flow, wherein the tube bundle heat exchanger is surrounded in a ring shape by the first catalyst bed such that the gas mixture heated by the reaction in the first catalyst bed is fed to the tube bundle heat exchanger and thus heats the gas mixture inside the heat exchanging tubes, characterized in that the heat exchanger is a co-current flow heat exchanger, which is configured in such a way that, in said heat exchanger, the gas flow through the heat exchanging tubes is guided in the same direction as the gas flow flowing around the heat exchanging tubes, wherein the starting material inlet is directly connected to the heat exchanging tubes in terms of gas flow, wherein the deflection device is configured to guide the gas flow out of the heat exchanging tubes into the central tube, such that the flow through the central tube is in the opposite direction to the flow through the heat exchanging tubes, wherein the central tube is directly connected to the space between the casing and the first catalyst bed in terms of gas flow.