Centrifugal separators and separation methods providing intermediate material ejection control
A separator includes a drum ejection passage control element and an intermediate ejection control element both mounted on a drum assembly. The drum ejection passage control element is moveable between a first position and a second position. In the second position a drum ejection passage is open for ejection of material from a maximum diameter of a separator volume, while in the first position the drum ejection passage control element blocks the drum ejection passage to prevent the ejection of material from the maximum diameter of the separator volume. An intermediate ejection path is formed in the separator, each extending from an intermediate ejection path inlet at an intermediate region of the separator volume to an intermediate ejection path outlet. The intermediate ejection control element is moveable to alternately open or close the intermediate ejection path for fluid communication to the separator volume.
1 . An apparatus including:
(a) a drum assembly having a drum rotational axis, the drum assembly including a separator volume in fluid communication with a feed inlet to the separator volume;
(b) a drum ejection path included in the drum assembly, the drum ejection path (i) including a drum ejection path entry position located at a first radial distance from the drum rotational axis and (ii) extending from the separator volume to an area outside of the separator volume;
(c) a drum ejection control element mounted on the drum assembly so as to be rotatable therewith about the drum rotational axis, the drum ejection control element also being mounted on the drum assembly so as to be moveable along a drum ejection control element range of movement, wherein when the drum ejection control element is in a first position along the drum ejection control element range of movement the drum ejection path is defined with a first minimum flow area therethrough and wherein when the drum ejection control element is in a second position along the drum ejection control element range of movement the drum ejection path is defined with a second minimum flow area therethrough greater than the first minimum flow area through the drum ejection path;
(d) an intermediate ejection path included in the drum assembly, the intermediate ejection path (i) including an intermediate ejection path entry position located at a second radial distance from the drum rotational axis less than the first radial distance and (ii) extending from the separator volume to the area outside of the separator volume such that the intermediate ejection path extends outwardly with respect to the drum rotational axis from the intermediate ejection path entry position; and
(e) an intermediate ejection control element mounted on the drum assembly so as to be rotatable therewith about the drum rotational axis, the intermediate ejection control element also being mounted on the drum assembly so as to be moveable along an intermediate ejection control element range of movement, wherein in a first position along the intermediate ejection control element range of movement the intermediate ejection path is defined with a first minimum flow area therethrough and wherein in a second position along the intermediate ejection control element range of movement the intermediate ejection path is defined with a second minimum flow area therethrough, the second minimum flow area through the intermediate ejection path being greater than the first minimum flow area through the intermediate ejection path.
2 . The apparatus of claim 1 wherein the intermediate ejection path is defined at least in part by a middle ejection passage formed in the drum ejection control element, the middle ejection passage having a middle ejection passage inlet at an inside surface of the drum ejection control element and having a middle passage outlet at an outside surface of the drum ejection control element.
3 . The apparatus of claim 2 wherein:
(a) the intermediate ejection path includes an inner ejection passage having an inner ejection passage inlet at an inside surface of the intermediate ejection control element and having an inner ejection passage outlet at an outside surface of the intermediate ejection control element; and
(b) the inner ejection passage outlet of the inner ejection passage at least partially aligns with the middle ejection passage inlet of the middle ejection passage when the intermediate ejection control element is in the second position along the intermediate ejection control element range of movement so as to expose the middle ejection passage inlet to the separator volume through the inner ejection passage.
4 . The apparatus of claim 2 wherein the intermediate ejection path includes at least a portion of the drum ejection path.
5 . The apparatus of claim 1 wherein:
(a) the drum ejection path includes a drum ejection passage formed in the drum assembly; and
(b) the drum ejection control element in the first position along the drum ejection control element range of movement substantially completely blocks the drum ejection passage so that the first minimum flow area through the drum ejection path is substantially zero.
6 . The apparatus of claim 5 wherein the drum ejection control element in the first position along the drum ejection control element range of movement substantially completely blocks an inlet end of the drum ejection passage.
7 . The apparatus of claim 5 wherein when the intermediate ejection control element is in the first position along the intermediate ejection control element range of movement the first minimum flow area through the intermediate ejection path is substantially zero.
8 . The apparatus of claim 1 wherein when the intermediate ejection control element is in the first position along the intermediate ejection control element range of movement the first minimum flow area through the intermediate ejection path is substantially zero.
9 . The apparatus of claim 8 wherein:
(a) the intermediate ejection path is defined at least in part by a middle ejection passage formed in the drum ejection control element; and
(b) the intermediate ejection control element in the first position along the intermediate ejection control element range of movement substantially completely blocks the middle ejection passage.
10 . The apparatus of claim 9 wherein the intermediate ejection control element in the first position along the intermediate ejection control element range of movement substantially completely blocks an inlet end of the middle ejection passage.
11 . The apparatus of claim 1 :
(a) further including a number of additional drum ejection paths included in the drum assembly, the number of additional drum ejection paths being spaced apart at different angular orientations about the drum rotational axis and wherein each respective additional drum ejection path (i) includes a respective drum ejection path entry position located at the first radial distance from the drum rotational axis and (ii) extends from the separator volume to the area outside of the separator volume; and
(b) wherein in the first position along the drum ejection control element range of movement each additional drum ejection path is defined with a respective first minimum flow area through the respective additional drum ejection path and wherein in the second position along the drum ejection control element range of movement each respective additional drum ejection path is defined with a respective second minimum flow area through the respective additional drum ejection path greater than the respective first minimum flow area through the respective additional drum ejection path.
12 . The apparatus of claim 11 :
(a) further including a number of additional intermediate ejection paths included in the drum assembly, the number of additional intermediate ejection paths being spaced apart at different angular orientations about the drum rotational axis and wherein each respective additional intermediate ejection path (i) includes a respective intermediate ejection path entry position located at a respective radial distance from the drum rotational axis less than the first radial distance from the drum rotational axis and (ii) extends from the separator volume to the area outside of the separator volume such that the respective additional intermediate ejection path extends outwardly with respect to the drum rotational axis from the respective intermediate ejection path entry position; and
(b) wherein in the first position along the intermediate ejection control element range of movement each additional intermediate ejection path is defined with a respective first minimum flow area through the respective intermediate ejection path and wherein in the second position along the intermediate ejection control element range of movement each additional intermediate ejection path is defined with a respective second minimum flow area through the respective intermediate ejection path greater than the respective first minimum flow area through the respective additional intermediate ejection path.
13 . The apparatus of claim 1 wherein the drum ejection control element is mounted on the drum assembly with one side of the drum ejection control element facing a drum ejection control positioning chamber of the drum assembly.
14 . The apparatus of claim 1 wherein the intermediate ejection control element is mounted on the drum assembly with one side of the intermediate ejection control element facing an intermediate ejection control positioning chamber of the drum assembly.
15 . A method including:
(a) rotating a drum assembly of a centrifugal separator at a separator velocity about a drum rotational axis, the drum assembly including a separator volume in fluid communication with a feed inlet to the separator volume and further including a drum ejection path, the centrifugal separator further including a drum ejection control element mounted on the drum assembly for movement along a drum ejection control element range of movement, wherein when the drum ejection control element is in a first position along the drum ejection control element range of movement the drum ejection path is defined with a first minimum flow area therethrough and wherein when the drum ejection control element is in a second position along the drum ejection control element range of movement the drum ejection path is defined with a second minimum flow area therethrough greater than the first minimum flow area through the drum ejection path to enable material in an area of a maximum diameter of the separator volume to be ejected from the separator volume along the drum ejection path when the drum ejection control element is in the second position along the drum ejection control element range of movement;
(b) while rotating the drum assembly at the separator velocity, moving an intermediate ejection control element mounted on the drum assembly and rotating therewith from a first position along an intermediate ejection control element range of movement to a second position along the intermediate ejection control element range of movement, wherein when the intermediate ejection control element is in the first position along the intermediate ejection control element range of movement an intermediate ejection path of the drum assembly is defined with a first minimum flow area therethrough and wherein when the intermediate ejection control element is in the second position along the intermediate ejection control element range of movement the intermediate ejection path is defined with a second minimum flow area therethrough greater than the first minimum flow area through the intermediate ejection path to enable material at an intermediate area of the separator volume to be ejected from the separator volume along the intermediate ejection path when the intermediate ejection control element is in the second position along the intermediate ejection control element range of movement, the intermediate ejection path extending from an intermediate ejection path inlet which is radially inward of the maximum diameter of the separator volume to an intermediate ejection path outlet which is radially outward of the intermediate ejection path inlet; and
(c) while rotating the drum assembly at the separator velocity, returning the intermediate ejection control element from the second position along the intermediate ejection control element range of movement to the first position along the intermediate ejection control element range of movement.
16 . The method of claim 15 further including maintaining the drum ejection control element in the first position along the drum ejection control element range of movement while moving the intermediate ejection control element from the first position along the intermediate ejection control element range of movement to the second position along the intermediate ejection control element range of movement and while returning the intermediate ejection control element from the second position along the intermediate ejection control element range of movement to the first position along the intermediate ejection control element range of movement.
17 . The method of claim 15 wherein:
(a) the drum ejection control element includes a middle ejection passage, the middle ejection passage forming part of the intermediate ejection path; and
(b) moving the intermediate ejection control element from the first position along the intermediate ejection control element range of movement to the second position along the intermediate ejection control element range of movement includes moving the intermediate ejection control element from a position in which the intermediate ejection control element substantially completely blocks the middle ejection passage to a position in which the middle ejection passage is open to the separator volume.
18 . The method of claim 17 wherein an upper lateral surface of the intermediate ejection control element covers a middle ejection passage inlet of the middle ejection passage when the intermediate ejection control element is in the first position along the intermediate ejection control element range of movement and is displaced at least partially from the middle ejection passage inlet when the intermediate ejection control element is in the second position along the intermediate ejection control element range of movement.
19 . The method of claim 15 wherein the intermediate ejection path coincides with a part of the drum ejection path so that material ejected through the intermediate ejection path travels through part of the drum ejection path.
20 . The method of claim 15 wherein moving the intermediate ejection control element from the first position along the intermediate ejection control element range of movement to the second position along the intermediate ejection control element range of movement includes releasing a positioning fluid for the intermediate ejection control element from an intermediate ejection control element positioning chamber defined between a surface of the drum assembly and a surface of the intermediate ejection control element.