Heat exchange configurations for oligomerization of olefins

1. A process comprising:

a) introducing at least 1) ethylene, 2) a catalyst system or catalyst system components comprising i) a heteroatomic ligand transition metal compound complex and an organoaluminum compound or ii) a heteroatomic ligand, a transition metal compound, and an organoaluminum compound, 3) optionally, an organic reaction medium, and 4) optionally, hydrogen into a reaction mixture within a reaction zone;

b) forming an oligomer product in the reaction zone; and

c) controlling a pressure in a heat exchange system to provide a reaction mixture temperature within the reaction zone, the heat exchange system comprising a first heat exchanger providing indirect contact between at least a portion of the reaction mixture and a first heat exchange medium, the first heat exchanger comprising a first heat exchange surface having

i) a first heat exchange surface first side in contact with the at least a portion of the reaction mixture, and

ii) a first heat exchange surface second side in contact with the first heat exchange medium;

where a pressure on the first heat exchange surface second side is less than 1 atmosphere (101.3 kPa); and

where the first heat exchange medium has a boiling point at 1 atmosphere (101.3 kPa) greater than an average reaction mixture temperature on the first heat exchange surface first side and a boiling point at the pressure on the first heat exchange surface second side less than the average reaction mixture temperature on the first heat exchange surface first side, and

where a temperature difference between the average reaction mixture temperature on the first heat exchange surface first side and a first heat exchange medium temperature on the first heat exchange surface second side is less than 20° C.

2. The process of claim 1 , wherein a first part of the at least a portion of the reaction mixture on the first heat exchange surface first side indirectly contacts a liquid phase of the first heat exchange medium on the first heat exchange surface second side and a second part of the at least a portion of the reaction mixture on the first heat exchange surface first side indirectly contacts a vapor phase of the first heat exchange medium that are on the first heat exchange surface second side.

3. The process of claim 2 , wherein a volume ratio of the liquid phase to the vapor phase of the first heat exchange medium on the first heat exchange surface second side is in a range from 1:1 to about 9:1.

4. The process of claim 1 , further comprising:

controlling the reaction mixture temperature by controlling a first level of the liquid phase of the first heat exchange medium on the first heat exchange surface second side, controlling the pressure on the first heat exchange surface second side, or any combination thereof.

5. The process of claim 4 , wherein controlling the first level of liquid phase of the first heat exchange medium comprises:

adding or removing first heat exchange medium to or from the heat exchange system.

6. The process of claim 4 , wherein the first level of the liquid phase of the first heat exchange medium is controlled such that 50% to 90% of a surface area of the first heat exchange surface second side contacts the liquid phase first heat exchange medium.

7. The process of claim 1 , wherein the heat exchange system further comprises one or more pressure control devices in fluid communication with the first heat exchange surface second side, the one or more pressure control devices providing the pressure of less than 1 atmosphere (101.3 kPa) on the first heat exchange surface second side.

8. The process of claim 7 , wherein controlling the pressure on the first heat exchange surface second side comprises adjusting the pressure set point on the one or more pressure control devices.

9. The process of claim 1 , wherein the heat exchange system further comprises a second heat exchanger providing indirect contact between the first heat exchange medium and a second heat exchange medium, the second heat exchanger comprising a second heat exchange surface having

i) a second heat exchange surface first side in contact with the first heat exchange medium, and

ii) a second heat exchange surface second side in contact with the second heat exchange medium;

where the second heat exchanger is fluidly connected to the first heat exchanger via a plurality of conduits allowing for flow of the first heat exchange medium between the first heat exchange surface second side and the second heat exchange surface first side,

where the second heat exchange surface does not contact the reaction mixture, and

where a pressure on the second heat exchange surface first side of the second heat exchanger is less than 1 atmosphere (101.3 kPa).

10. The process of claim 9 , wherein a first part of the at least a portion of the reaction mixture on the first heat exchange surface first side indirectly contacts a liquid phase of the first heat exchange medium on the first heat exchange surface second side and a second part of the at least a portion of the reaction mixture on the first heat exchange surface first side indirectly contacts a vapor phase of the first heat exchange medium that are on the first heat exchange surface second side, and

wherein at least a first part of the second heat exchange medium on the second heat exchange surface second side indirectly contacts the vapor phase of the first heat exchange medium on the second heat exchange surface first side and a second part of the second heat exchange medium on the second heat exchange surface second side indirectly contacts liquid phase of the first heat exchange medium on the second heat exchange surface first side.

11. The process of claim 10 , further comprising controlling a reaction mixture temperature in the reaction zone by controlling a first level of the liquid phase of the first heat exchange medium on the first heat exchange surface second.

12. The process of claim 11 , wherein the first level of the liquid phase of the first heat exchange medium of the first heat exchange surface second side is controlled by:

controlling a second level of a liquid phase of the first heat exchange medium on the second heat exchange surface first side,

adding or removing first heat exchange medium to or from the heat exchange system, or a combination thereof.

13. The process of claim 9 , wherein the heat exchange system further comprises one or more pressure control devices in fluid communication with at least one of the plurality of conduits controlling the pressure in the heat exchange system comprises providing the pressure of less than 1 atmosphere (101.3 kPa) on the first heat exchange surface second side and on the second heat exchange surface first side.

14. The process of claim 13 , wherein controlling the pressure in the heat exchange system comprises adjusting a pressure set point on the one or more pressure control devices.

15. The process of claim 10 , wherein a second level of the liquid phase of the first heat exchange medium on the second heat exchange surface first side is vertically higher relative to a common reference point on the ground than a first level of the liquid phase of the first heat medium on the first heat exchange surface second side.

16. The process of claim 9 , wherein the first heat exchange surface comprises horizontally oriented tubes or plates, wherein the second heat exchange surface comprises vertically oriented tubes or plates.

17. The process of claim 1 , wherein the first heat exchange medium comprises water.

18. The process of claim 1 , wherein a ratio of heat exchanged reaction mixture volume to the total reaction mixture volume within the reaction zone is in a range from 0.7 to 1:1.

19. The process of claim 1 , wherein the first heat exchange medium temperature on the first heat exchange surface second side is within 4.5% of the average reaction mixture temperature on the first heat exchange surface first side.

20. The process of claim 1 , wherein a reaction mixture temperature at any point in the reaction zone is within ±3% of the average reaction mixture temperature in the reaction zone and/or the temperature difference between the average reaction mixture temperature on the first heat exchange surface first side and the first heat exchange medium temperature on the first heat exchange surface second side is less than 5° C.