DEVICE FOR SEPARATING LIQUID DROPLETS FROM A GAS STREAM

Abstract: Device for the separation of liquid droplets from a gas stream comprising a plurality of wave plates (1, 2 and 3) arranged close to one another in such a way that a passage (5, 12) is defined between two adjacent plates, which passage alternately comprises a narrowing part (21) and a widening part (22) that is joined to the narrowing part (21), wherein a bend in the passage lies between the largest width of the widening part (22) and the smallest width of a narrowing part (21) that is joined to the widening part (22).

Description: The present invention relates to a device for the separation of liquid droplets from a gas stream, comprising a plurality of wave plates arranged close to one another in such a way that a passage is defined between two adjacent plates, which passage alternately comprises a narrowing part and a widening part that is joined to the narrowing part. During normal operation of this device, gas with liquid droplets flows through the passage. Gas comes into contact with the walls of the wave plates that define the passage. As a result of this contact, the liquid droplets collect on the wall and gas with substantially no liquid droplets leaves the passage. To reduce the detrimental effect of vortices on the separation efficiency of the separator, each passage of the known device alternately comprises a narrowing part and a widening part that is joined to the narrowing part, wherein the largest width of the widening part is located at the location of the largest curvature (smallest radius of curvature) of the bend. Such Known devices are described, for example, in US-A-1 926 924 and FR-A-2 395 061. It is an object of the present invention is to improve the known device. To this end the device for the separation of liquid droplets from a gas stream according to the invention comprises a plurality of wave plates arranged close to one another in such a way that a passage is defined between two adjacent plates, which passage alternately comprises a narrowing part and a widening part that is joined to the narrowing part, wherein a bend in the passage lies between the largest width of the widening part and the smallest width of the narrowing part that is joined to the widening part. The geometry of the passage is defined with respect to the axis of the passage. An advantage of the device according to the present invention is that the shape of the passage prevents turbulence in the gas stream which could have an adverse effect on the separating function of the device, as the formation of vortices is suppressed over a part of the passage beginning before the location of the largest curvature (smallest radius of curvature) of the bend. The invention will now be discussed by way of example in more detail with reference to the accompanying figure which shows schematically a part of a vertical cross-section of three plates belonging to the device according to the present invention. The three wave plates shown in the figure are indicated by reference numerals 1, 2 and 3, the longitudinal axes of the plates 1, 2 and 3 being perpendicular to the drawing plane of the figure. The wave plates 1 and 2 are arranged near each other in such a way that a passage 5 is defined between the external surfaces of the facing walls 7 and 8 of the plates 1 and 2, and a passage 12 is defined between the external surfaces of the facing walls 13 and 14 of the wave plates 2 and 3 arranged near each other. The axes of the passages 5 and 12 are indicated by broken lines 18. Each of the passages 5 and 12 comprises a widening part 20, a narrowing part 21 that is joined to the widening part 20, and a widening part 22 that is joined to the narrowing part 21. The largest width of each of the widening parts 20 is upstream of the bend 25 in the axis of the passage 5 or 12, and the smallest width of each of the narrowing parts 21 is downstream of the bend 25 so that a bend in the passage lies between the largest width of the widening part and the smallest width of the narrowing part that is joined to the widening part. The device for the separation of liquid droplets from a gas stream is placed in a vessel (not shown) provided with an inlet (not shown) and an outlet (not shown) in such a way that the device lies between the inlet and the outlet, the gas stream flowing through the device in a direction indicated by arrows 27. During normal operation, gas with liquid droplets flows from the inlet to the outlet through the passages 5 and 12 of the device according to the invention. The gas stream collides with the external surfaces of the facing walls 7 and 8 and the facing walls 13 and 14, as a result of which the liquid droplets collect on the walls 7, 8, 13 and 14. Gas substantially free from liquid droplets leaves the device and flows to the outlet. If the device is oriented such that the longitudinal axes of the plates 1, 2 and 3 run vertically, the droplets on the walls 7, 8, 13 and 14 will collect on the bottom edges of the plates. From here, the droplets can be led to a container (not shown) provided with a discharge (not shown). Preferably, the ratio of the largest width of the widening part to the smallest width of the narrowing part is between 1.3:1 and 2:1. In order to prevent further formation of undesired turbulence in the gas stream in the widening part of the passage, the angle between the walls that define that part of the passage are suitably chosen between 1° and 10° and very suitably between 3° and 8°. In a not shown alternative embodiment, the plates are hollow and the walls are provided with orifices through which liquid on the walls can flow into the hollow of the plates. This last embodiment is suitable for those applications of the device according to the invention in which the longitudinal axes of the plates run horizontally. The parts of the wave plates 1, 2 and 3 extend over a half wave. The plates can also extend over a whole wave or over a greater number of waves. If the wave plates 1, 2 and 3 were to extend over a whole wave, they could be shaped such that every passage exhibited a narrowing part whose smallest width was downstream of the not shown bend in the passage downstream of the largest width of the widening part 22, said narrowing part being followed by a widening part. The device according to the invention can also comprise more than three wave plates arranged close to one another.

Claims: Device for the separation of liquid droplets from a gas stream comprising a plurality of wave plates (1,2,3) arranged close to one another in such a way that a passage (5,12) is defined between two adjacent plates, which passage alternately comprises a narrowing part (21) and a widening part (20,22) that is joined to the narrowing part, wherein a bend (25) in the passage lies between the largest width of the widening part and the smallest width of the narrowing part that is joined to the widening part. Device as claimed in claim 1, wherein the ratio of the largest width of the widening part to the smallest width of the narrowing part is between 1.3:1 and 2:1. Device as claimed in claim 1 or 2, wherein the angle between the plate walls (7,8,13,14) that define the widening part of the passage lies between 1° and 10°. Device as claimed in claim 3, wherein the angle lies between 3° and 8°. Device as claimed in any one of claims 1-4, wherein the plates are hollow. Device as claimed in claim 5, wherein the walls of the plates are provided with orifices.

Inventors: SWANBORN, ROMBOUT ADRIAAN
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1989
Main classification: B01D45
IPC codes: B01D45