Method for cooling a process flow

1. A method of cooling a process stream with an auxiliary stream, wherein an exchange of heat between the process stream and the auxiliary stream is affected in a first heat exchanger and a second heat exchanger connected downstream of the first heat exchanger, said process comprising:

a) dividing the process stream into a first substream, a second substream, and optionally one or more further substreams,

b) regulating the individual flow rate of each substream by a valve associated therewith,

c) cooling said first substream by heat exchange with the auxiliary stream in both the first exchanger and the second heat exchanger, to form a cooled first substream,

d) mixing the second substream with the cooled first substream to form a combined substream and cooling the combined substream in the second heat exchanger to form a cooled combined substream, and

e) if said process stream is divided into said one or more further substreams, mixing each of said further substreams with said cooled combined substream and cooling the resultant combined substream in the second heat exchanger after each further substream has been mixed in,

wherein the flow rates of the substreams are regulated such that the temperatures of the substreams to be cooled in the second heat exchanger, on entry into the second heat exchanger, differ from one another by not more than 10 K, and

wherein at least one of the valves that regulate the flow rates of the substreams is fully opened.

2. The method as claimed in claim 1 , wherein the flow rates of the substreams are regulated such that the temperatures of the substreams to be cooled in the second heat exchanger, on entry into the second heat exchanger, differ from one another by not more than 5 K.

3. The method as claimed in claim 1 , wherein the first heat exchanger and/or the second heat exchanger is/are plate heat exchangers.

4. The method as claimed in claim 1 , wherein the process stream to be cooled is a hydrogen-rich gas, a helium-rich gas, or a neon-rich gas.

5. The method as claimed claim 1 , wherein the auxiliary stream is a nitrogen-rich liquid or a nitrogen-rich gas.

6. The method as claimed in claim 2 , wherein the temperatures of the substreams to be cooled in the second heat exchanger, on entry into the second heat exchanger, differ from one another by not more than 2 K.

7. The method as claimed claim 1 , wherein, prior to heat exchange in the first heat exchanger and the second heat exchanger, the auxiliary stream is separated in a separator into a liquid fraction and a gas fraction, the liquid fraction is subjected to heat exchange in the second heat exchanger and then mixed with the gas fraction to form a combined auxiliary stream, and the combined auxiliary stream is then subjected to heat exchange with the first substream in the first heat exchanger.

8. A method of cooling a process stream with an auxiliary stream, wherein an exchange of heat between the process stream and the auxiliary stream is affected in a first heat exchanger and a second heat exchanger connected downstream of the first heat exchanger, said process comprising:

a) dividing the process stream into at least a first substream and a second substream,

b) regulating the flow rate of the first substream by a first valve, and regulating the flow rate of the second substream by a second valve,

c) cooling said first substream by heat exchange with the auxiliary stream in both the first exchanger and the second heat exchanger, to form a cooled first substream,

d) mixing the second substream with the cooled first substream to form a combined substream and cooling the combined substream in the second heat exchanger to form a cooled combined substream, and

wherein the flow rates of the first and second substreams are regulated such that the temperatures of the substreams to be cooled in the second heat exchanger, on entry into the second heat exchanger, differ from one another by not more than 10 K, and

wherein at least one of the first valve and the second valve that regulate the flow rates of the first and second substreams is fully opened.

9. A method of cooling a process stream with an auxiliary stream, wherein an exchange of heat between the process stream and the auxiliary stream is affected in a first heat exchanger and a second heat exchanger connected downstream of the first heat exchanger, said process comprising:

a) dividing the process stream at least a first substream, a second substream, and a third substream,

b) regulating the flow rates of said first, second and third substreams by a first valve, a second valve, and a third valve, respectively

c) cooling said first substream by heat exchange with the auxiliary stream in both the first exchanger and the second heat exchanger, to form a cooled first substream,

d) mixing the second substream with the cooled first substream to form a combined substream and cooling the combined substream in the second heat exchanger to form a cooled combined substream, and

e) mixing the third substream with the cooled combined substream to form a further combined substream and cooling the further combined substream in the second heat exchanger to form a cooled further combined substream,

wherein the flow rates of the first, second, and third substreams are regulated such that the temperatures of the substreams to be cooled in the second heat exchanger, on entry into the second heat exchanger, differ from one another by not more than 10 K, and

wherein at least one of said first, second, and third valves is fully opened.