1. A process for preparing polyolefin in a polymerization loop reactor, said polymerization loop reactor comprising:
a plurality of interconnected pipes defining a flow path for a polyolefin slurry, and
one or more settling legs provided on at least one horizontal part of said interconnected pipes, said process comprising:
feeding olefin monomer, liquid diluent, polymerization catalyst, optionally hydrogen, and optionally olefin co-monomer into said polymerization loop reactor; and
polymerizing said olefin monomer and optionally said olefin co-monomer to produce said polyolefin slurry in said polymerization loop reactor;
wherein a circulation velocity of the polyolefin slurry inside the at least one horizontal part of said interconnected pipes provided with one or more settling legs is reduced by at least 20% and at most 60% compared to a circulation velocity inside a remainder of said polymerization loop reactor.
2. The process according to claim 1, wherein an internal diameter of said at least one horizontal part of said interconnected pipes provided with one or more settling legs is increased by a factor of at least 1.10 and at most 1.40 compared to an internal diameter of the remainder of said interconnected pipes.
3. The process according to claim 1, wherein a bottom ends of two vertical pipes are connected to each other by two horizontal pipes, and wherein both of said two horizontal pipes are provided with one or more settling legs.
4. The process according to claim 1, wherein a bottom ends of two vertical pipes are connected to each other by two horizontal pipes, wherein at least one of said two horizontal pipes is provided with one or more settling legs, and wherein an internal diameter of at least one of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 0.99 times the internal diameter of the remainder of said interconnected pipes.
5. The process according to claim 1, wherein a bottom ends of two vertical pipes are connected to each other by two horizontal pipes, and wherein the internal diameter of each of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 0.99 times the internal diameter of the remainder of said interconnected pipes.
6. The process according to claim 1, wherein said polymerization loop reactor is a single loop reactor.
7. The process according to claim 1, wherein said polymerization loop reactor is a double loop reactor comprising two serially connected loop reactors.
8. The process according to claim 1, wherein the polyolefin is polyethylene.
9. A loop reactor suitable for a polyolefin polymerization process comprising:
a plurality of interconnected pipes defining a flow path for a polyolefin slurry,
means for introducing olefin monomer, polymerization catalyst and diluent into said loop reactor,
one or more settling legs provided on at least one horizontal part of said interconnected pipes, and
a pump suitable for maintaining said polyolefin slurry in circulation in said loop reactor; wherein a bottom ends of two vertical pipes are connected to each other by two horizontal pipes, and wherein at least one of said two horizontal pipes is provided with one or more settling legs, and wherein a circulation velocity of the polyolefin slurry inside at least one horizontal part of said interconnected pipes provided with one or more settling legs is reduced by at least 20% and at most 60% compared to a circulation velocity inside a remainder of said loop reactor.
10. The loop reactor according to claim 9, wherein both of said two horizontal pipes are provided with one or more settling legs.
11. The loop reactor according to claim 9, wherein an internal diameter of at least one of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 1.0 times an internal diameter of a remainder of said interconnected pipes.
12. The loop reactor according to claim 9, wherein an internal diameter of each of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 1.0 times an internal diameter of a remainder of said interconnected pipes.
13. The loop reactor according to claim 9, wherein an internal diameter of at least one of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 0.99 times an internal diameter of a remainder of said interconnected pipes.
14. The loop reactor according to claim 9, wherein an internal diameter of at least one of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 0.95 times an internal diameter of a remainder of said interconnected pipes.
15. The process according to claim 1, wherein an internal diameter of said at least one horizontal part of said interconnected pipes provided with one or more settling legs is increased by a factor of at least 1.10 and at most 1.50 compared to an internal diameter of the remainder of said interconnected pipes.
16. The process of claim 15, wherein the internal diameter of said at least one horizontal part of said interconnected pipes provided with one or more settling legs is increased by a factor of at least 1.30 and at most 1.36 compared to an internal diameter of the remainder of said interconnected pipes.
17. The process according to claim 1, wherein a bottom ends of two vertical pipes are connected to each other by two horizontal pipes, and wherein at least one of said two horizontal pipes is provided with one or more settling legs.
18. The process according to claim 17, wherein an internal diameter of at least one of said two horizontal pipes provided with one or more settling legs is equal to 0.90 to 0.95 times the internal diameter of the remainder of said interconnected pipes.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A lens comprising:
a light incident surface, the light incident surface being a concave surface and defining a receiving recess;
a first light emitting surface, the first light emitting surface being a convex curved surface and opposite to the light incident surface, the first light emitting surface comprising a first border, the first light emitting surface and the light incident surface cooperatively forming a convex lens portion with an optical axis; and
a second light emitting surface located at a side of the first light emitting surface adjacent to the first border, the longer the distance between a point of the second light emitting surface and the optical axis being, the longer the distance between the point and the light incident surface being.
2. The lens as claimed in claim 1, wherein the light incident surface is a concave curved surface.
3. The lens as claimed in claim 1, wherein the lens further comprises a ring-shaped flat surface surrounding the light incident surface, the ring-shaped flat surface extends from the edge of the light incident surface.
4. The lens as claimed in claim 1, wherein the convex lens portion has a focal point located in the receiving recess.
5. The lens as claimed in claim 1, wherein the lens is used in a vehicle lamp, the second light emitting surface is arranged at a side of the first light emitting surface adjacent to the ground.
6. The lens as claimed in claim 1, wherein the projection area of the second light emitting surface on a plane perpendicular to the optical axis is smaller than that of the first light emitting surface.
7. The lens as claimed in claim 1, wherein the lens further comprises a connecting surface connecting the first light emitting surface to the second light emitting surface, and the connecting surface is substantially parallel to the optical axis.
8. The lens as claimed in claim 7, wherein the light connecting surface comprises a light reflective film formed thereon.
9. The lens as claimed in claim 7, wherein the projections of the first light emitting surface, the second light emitting surface, and the connecting surface on a plane perpendicular to the optical axis cooperatively form a circle.
10. A light source module comprising:
a light source; and
a lens, the lens comprising:
a light incident surface facing the light source, the light incident surface being a concave surface and defining a receiving recess;
a first light emitting surface, the first light emitting surface being a convex curved surface and opposite to the light incident surface, the first light emitting surface comprising a first border, the first light emitting surface and the light incident surface cooperatively forming a convex lens portion with an optical axis; and
a second light emitting surface located at a side of the first light emitting surface adjacent to the first border, the longer the distance between a point of the second light emitting surface and the optical axis being, the longer the distance between the point and the light incident surface being.
11. The light source module as claimed in claim 10, wherein the light source is received in the receiving recess.
12. The light source module as claimed in claim 10, wherein the light incident surface is a concave curved surface.
13. The light source module as claimed in claim 10, wherein the lens further comprises a ring-shaped flat surface surrounding the light incident surface, the ring-shaped flat surface extends from the edge of the light incident surface.
14. The light source module as claimed in claim 13, wherein the light source module further comprises a circuit board, the light source is a light emitting diode mounted on the circuit board, and the ring-shaped flat surface is attached to the circuit board.
15. The light source module as claimed in claim 10, wherein the convex lens portion has a focal point located in the receiving recess, and the light source is located on the focal point.
16. The light source module as claimed in claim 10, wherein the lens is used in a vehicle lamp, the second light emitting surface is arranged at a side of the first light emitting surface adjacent to the ground.
17. The light source module as claimed in claim 10, wherein the projection area of the second light emitting surface on a plane perpendicular to the optical axis is smaller than that of the first light emitting surface.
18. The light source module as claimed in claim 10, wherein the lens further comprises a connecting surface connecting the first light emitting surface to the second light emitting surface, and the connecting surface is substantially parallel to the optical axis.
19. The light source module as claimed in claim 18, wherein the light connecting surface comprises a light reflective film formed thereon.
20. The light source module as claimed in claim 18, wherein the projections of the first light emitting surface, the second light emitting surface, and the connecting surface on a plane perpendicular to the optical axis cooperatively form a circle.