LIQUID RING COMPRESSORS

Abstract: A double-lobe (140a, 140b) liquid ring gas compressor includes a port member having two circumferentially spaced intake ports (143a, 143b) and two circumferentially spaced discharge ports (145a, 145b). The intake ports are axially offset from the discharge ports. The intake ports are con­ nected to a common intake passage (142a, 142b) in the port member, and the discharge ports are similarly connected to a common discharge passage (146a, 146b) in the port member. These passages respectively communicate with intake (23a, 23b) and discharge (25a, 25b) manifolds in a head member which can be identical to the head member of a single-lobe liquid ring vacuum pump.

Description: This invention relates to a liquid ring compressor and more particularly to such a compressor for compressing gases to pressures above atmospheric pressure. A typical liquid ring vacuum pump has one intake and one compression stroke per cycle. This is a so-called single-lobe pump. The asymmetrical construction of a single-lobe pump is acceptable in a liquid ring vacuum pump which is generally limited to a pressure differential across the pump of 15 to 20 p.s.i.g. Liquid ring compressors (i.e., liquid ring pumps used to compress gases to super-atmospheric pressure) are, however, capable of achieving pressure differentials substantially greater than 15 to 20 p.s.i.g. Above about 25 p.s.i.g. the asymmetrical design of single-lobe pumps becomes a significant problem due to the practical limits imposed by rotor shaft stress and deflection caused by unbalanced forces in the pump. Accordingly, liquid ring compressors for providing pressure differentials above about 25 p.s.i.g. typically have a balanced double-lobe design (i.e., two intake and two compression strokes per cycle) which significantly reduces force imbalances acting on the shaft. Heretofore the substantially different designs of liquid ring vacuum pumps and high pressure liquid ring compressors have generally precluded the design of common parts useful in both vacuum pumps and compressors. This effectively increases the cost of both the vacuum pumps and the compressors. In addition, the double-lobe design of high pressure liquid ring compressors has previously necessitated the use of complex, multi-passage heads to accommodate the dual intake and dual discharge passages of such compressors. This has increased the complexity and cost of high pressure liquid ring compressors. In view of the foregoing, it is an object of this invention to provide liquid ring compressors which can have a substantial number of parts in common with liquid ring vacuum pumps. Another object of this invention is to provide less complex and less costly double-lobe liquid ring compressors. Still another object of this invention is to provide lower cost double-lobe liquid ring compressors which can have a substantial number of parts in common with single-lobe liquid ring vacuum pumps. US . A .. 2677276 discloses a liquid ring compressor comprising: an annular housing; a quantity of pumping liquid maintained in the housing; a rotor rotatably mounted in the housing and having a plurality of circumferentially spaced, radially extending blades for engaging the pumping liquid and forming it into a recirculating annular ring inside the housing, the housing being shaped to cause the inner surface of the liquid ring to diverge from the rotor axis in the direction of rotor rotation at two circumferentially spaced intake zones of the pump and to converge toward the rotor axis in the direction of rotor rotation at two circumferentially spaced compression zones of the pump, the intake and compression zones alternating circumferentially of the pump; and an annular port member concentric with the rotor and extending into an annular recess in a first axial end of the rotor, the port member including two diametrically opposite intake ports arranged to admit gas to be compressed to said intake zones and two diametrically opposite discharge ports axially displaced from the intake ports and arranged to receive compressed gas from said compression zones, the discharge ports being interconnected within the port member and communicating with a discharge passage and the intake ports being separated from the discharge ports and communicating with a common intake passage. According to this present invention such a liquid ring compressor is characterised in that the intake ports are interconnected within the annular port member. In the preferred embodiment, the intake ports are interconnected within the port member and communicate with the intake manifold in the head member of the pump at the same location as the single intake port passage in a similar conically or cylindrically ported single-lobe liquid ring vacuum pump. The discharge ports are similarly interconnected within the port member (but separated from the intake port passage) and communicate with the discharge manifold in the head member at the same location as the single discharge passage in the above-mentioned vacuum pump. Accordingly, the head member of the double-lobe compressor can be of simple design with one intake passage and one discharge passage. The double-lobe compressor of this invention is therefore less costly and can use the same rotor, the same head member, the same bearing brackets, the same shaft, etc., as the above-mentioned single-lobe vacuum pump. Only the port member and the housing need be changed to convert the single-lobe vacuum pump to the double-lobe compressor of this invention. Further features of the invention, its nature and various advantages will be more apparent from the following detailed description of embodiments of the invention. Reference is made to the accompanying drawings in which: Figure 1 is an elevational view, partly in section, of a conventional double-ended, single-lobe, conically ported liquid ring vacuum pump; Figure 2 is a cross sectional view taken along the line 2-2 in Figure 1. The sectional portion of Figure 1 is taken along the line 1-1 in Figure 2; Figure 3 is a perspective view of one of the port members in the vacuum pump of Figures 1 and 2; Figure 4 is a perspective view of the port member of Figure 3 with its outer frusto-conical surface member removed; Figure 5 is a planar projection of the outer frusto-conical surface of the port member of Figure 3; Figure 6 is another perspective view of the port member of Figure 3 taken in the opposite direction from Figure 3; Figure 7 is an elevational view, partly in section, of a double-ended, double-lobe, conically ported liquid ring compressor; Figure 8 is a cross sectional view taken along the line 8-8 in Figure 7. The sectional portion of Figure 7 is taken along the line 7-7 in Figure 8; and Figures 9-12 are views respectively similar to Figures 3-6 showing one of the port members in the compressor of Figures 7 and 8. Figure 1 shows a conventional double-ended, single-lobe, conically ported liquid ring vacuum pump 10. The two ends of pump 10 are mirror images of one another about the transverse plane including axis A-A. Accordingly, only the right-hand end of pump 10 (shown in cross section in Figure 2) will be discussed in detail. Gas to be pumped enters stationary head member 20b via intake manifold 22b. Intake manifold 22b is connected to intake passage 42b in stationary conical port member 40b (shown in greater detail in Figures 3-6). The gas inlet flange opening 41b of port member 40b mates with the gas outlet opening 23b of head member 20b. The gas to be pumped flows from intake passage 42b into rotating rotor 60 via intake port 43b. Rotor 60 is fixedly secured to rotating shaft 80. Shaft 80 is rotatably mounted by means of bearings 30a and 30b in head members 20a and 20b, respectively. Rotor 60 and shaft 80 rotate in the direction of arrow 62. Rotor 60 includes a plurality of circumferentially spaced, radially and axially extending blades 64. Rotor 60 is surrounded by an annular housing 90 which extends between head members 20a and 20b and which is eccentric to rotor 60. A quantity of pumping liquid (usually water) is maintained in housing 90. Rotor blades 64 engage the pumping liquid and form it into an annular ring inside housing 90 as rotor 60 rotates. On the left-hand side of the pump as viewed in Figure 2 the inner surface of the liquid ring diverges from the outer surface of port member 40b in the direction of rotor rotation. Accordingly, on this side of the pump, the gas pumping chambers bounded by (1) adjacent rotor blades 64, (2) the inner surface of the liquid ring, and (3) the outer surface of port member 40b are expanding in the direction of rotor rotation. Gas is therefore pulled into these chambers via intake port 43b, and this portion of the pump is accordingly known as the intake zone of the pump. On the right-hand side of the pump as viewed in Figure 2 the inner surface of the liquid ring converges toward the outer surface of port member 40b in the direction of rotor rotation. Accordingly, on this side of the pump the above-mentioned gas pumping chambers are contracting in the direction of rotor rotation. The gas in these chambers is therefore compressed in this compression zone of the pump, and the compressed gas is expelled via discharge port 45b and discharge passage 46b in port member 40b. Discharge passage 46b communicates with discharge manifold 26b in head member 20b via mating discharge flange opening 47b in port member 40b and gas inlet opening 25b in head member 20b. In accordance with this invention, most of the parts of single-lobe vacuum pump 10 can also be used to provide a double-lobe compressor 110 as shown in Figures 7-12. Preferably, only housing 190 and port members 140 are different from the corresponding parts of pump 10. The other parts of compressor 110 are preferably the same as the corresponding parts of pump 10, and these parts therefore have the same reference numbers in the drawings of both devices. As in the case of vacuum pump 10, the two ends of compressor 110 are mirror images of one another about the transverse plane including axis A-A in Figure 7. Considering first the parts of compressor 110 that are different from the corresponding parts of pump 10, the shape of housing 190 is best seen in Figure 8. As shown in that Figure, housing 190 is concentric with shaft 80 and provides two intake zones (lower left and upper right as viewed in Figure 8) and two compression zones (upper left and lower right as viewed in Figure 8). Port member 140b is shown in greater detail in Figures 9-12. The gas inlet flange opening 141b and gas discharge flange opening 147b of port member 140b are respectively similar to the corresponding openings 41b and 47b of port member 40b so that port member 140b communicates with head member 20b in exactly the same way that port member 40b communicates with that head member. The interior of port member 140b, however, differs from the interior of port member 40b. In particular, intake passage 142b extends axially only approximately one half the length of port member 140b from the plane of end flange 150b to intermediate flange 152b. Circumferentially, intake passage 142b extends approximately three quarters of the way around port member 140b, excluding only the one quarter of the circumference of the port member adjacent to gas discharge flange opening 147b. The circumferential ends of intake passage 142b are defined by axially and radially extending partitions 154b and 156b. The circumferential extent of intermediate flange 152b is co-extensive with intake passage 142b. Discharge passage 146b extends circumferentially all the way around port member 140b on the side of intermediate flange 152b remote from passage 142b. Discharge passage 146b communicates with gas discharge flange opening 147b via the gap in intermediate flange 152b and between partions 154b and 156b. The conical outer surface of port member 140b has two circumferentially spaced intake ports 143b1 and 143b2, each of which communicates with intake passage 142b. Each of intake ports 143b1 and 143b2 is located adjacent a respective one of the intake zones of the pump in order to admit gas to those zones. The conical outer surface of port member 140b also has two circumferentially spaced discharge ports 145b1 and 145b2, each of which communicates with discharge passage 146b. Each of discharge ports 145b1 and 145b2 is located adjacent a respective one of the compression zones of the pump in order to discharge compressed gas from those zones. Intake ports 143b1 and 143b2 are located between the planes of end flange 150b and intermediate flange 152b. Discharge ports 145b1 and 145b2 are located between the plane of intermediate flange 152b and the small end of port member 140b. For the most part, gas introduced into the pump via intake port 143b1 exits via discharge port 145b1, and gas introduced into the pump via intake port 143b2 exits via discharge port 145b2. From the foregoing it will be seen that by changing only the housing (90, 190) and the port members (40, 140), either a single-lobe liquid ring vacuum pump or a double-lobe liquid ring compressor can be constructed using other parts that are identical for either the pump or the compressor. Although the invention has been illustrated in the context of conically ported liquid ring pumps and compressors in which the port members are tapered inwardly in the direction away from end flange 50 or 150, those skilled in the art will appreciate that the invention is equally applicable to cylindrically ported liquid ring pumps and compressors in which the port members are cylindrical and therefore not tapered.

Claims: A liquid ring compressor (110) comprising: an annular housing (190); a quantity of pumping liquid maintained in the housing; a rotor (60) rotatably mounted in the housing and having a plurality of circumferentially spaced, radially extending blades for engaging the pumping liquid and forming it into a recirculating annular ring inside the housing, the housing being shaped to cause the inner surface of the liquid ring to diverge from the rotor axis in the direction of rotor rotation at two circumferentially spaced intake zones of the pump and to converge toward the rotor axis in the direction of rotor rotation at two circumferentially spaced compression zones of the pump, the intake and compression zones alternating circumferentially of the pump; and an annular port member (140) concentric with the rotor and extending into an annular recess in a first axial end of the rotor, the port member including two diametrically opposite intake ports (143) arranged to admit gas to be compressed to said intake zones and two diametrically opposite discharge ports (145) axially displaced from the intake ports and arranged to receive compressed gas from said compression zones, the discharge ports (145) being interconnected within the port member and communicating with a discharge passage (146) and the intake ports being separated from the discharge ports and communicating with a common intake passage (142), characterised in that the intake ports (143) are interconnected within the annular port member (140). A liquid ring compressor as claimed in claim 1 wherein the end of the port member (140) adjacent the first end of the rotor (60) includes a flange (150) disposed in a plane substantially perpendicular to the rotor axis, and a gas inlet opening (141) communicating with said intake ports (143) and a gas discharge opening (147) communicating with said discharge ports (145) are disposed in the first flange. A liquid ring compressor as claimed in claim 1 or claim 2 wherein the port member (140) has an outer surface which tapers inwardly toward the rotor axis in the direction into the annular recess. A liquid ring compressor as claimed in any preceding claim wherein the port member (140) includes a separating flange (152) disposed in a plane substantially perpendicular to the rotor axis intermediate the intake ports (143) and discharge ports (145) of the port member, which flange separates the intake passage (142) from the discharge passage (146). A liquid ring compressor as claimed in claim 4 wherein the intake passage (142) extends approximately 75% around the circumference of the port member (140) adjacent the first axial end of the port member. A liquid ring compressor as claimed in claim 5 wherein the discharge passage (146) extends approximately 100% around the circumference of the port member (140) adjacent the second axial end of the port member, and wherein the portion of the discharge passage adjacent the first axial end of the port member occupies the 25% of the circumference of that end of the port member which is not occupied by the intake passage (142). A liquid ring compressor as claimed in claim 6 wherein the separating flange (152) is circumferentially coextensive with the intake passage (142), and wherein the portion of the discharge passage (146) adjacent the first axial end of the port member (140) is separated from the intake passage by two circumferentially spaced, axially and radially extending partitions (146, 156).

Inventors: HAAVIK, HAROLD K.
Applicants: THE NASH ENGINEERING COMPANY
Application year: 1986
Main classification: F04C19
IPC codes: F04C19