IMPROVED LIQUID RING PUMP

Abstract

Liquid Ring pumps are inherently inefficient due to energy losses caused by friction, the present invention overcomes this by providing a coating on certain surfaces of the pump to limit the friction.

Claims

1. A pump component at least partially coated with a coating comprising at least one alkoxysilane.

2. The pump component according to claim 1, wherein the coating on the pump component is, in use, in contact with a work fluid.

3. The pump component according to claim 1, wherein the component is a liquid ring pump component.

4. The pump component according to claim 1, wherein the component is a rotary vane pump component.

5. The pump component according to claim 1, wherein the component is a screw pump component.

6. The pump component according to claim 1, wherein the pump component is at least one of a rotor component, a stator component and a rotor shaft component.

7. A liquid ring pump comprising a pump component according to claim 3.

8. A rotary vane pump comprising a pump component according to claim 4.

9. A screw pump comprising a pump component according to claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order that the present invention may be well understood, several embodiments thereof, which are given by way of example only, will now be described with reference to the accompanying drawings, in which:

[0014] FIG. 1 shows a radial cross section through a prior art liquid ring pump.

[0015] FIG. 2 shows a radial cross section through a liquid ring pump according to the present invention.

[0016] FIG. 3 shows an exploded view of a section of a two stage liquid ring pump according to the present invention.

DETAILED DESCRIPTION

[0017] With Reference to FIG. 2, a radial cross section through a liquid ring pump according to the present invention is illustrated. The same reference numerals used to denote features in FIG. 1 have been used to denote the identical features in FIG. 2 and, for brevity, will not be explained further.

[0018] The surface of the casing, or stator component, 102, has a coating 123 comprising an alkoxysilane, such as methyltrimethoxysilane and/or phenyltrimethoxysilane, applied thereto. It will be appreciate that these are just two examples and other alkoxysilanes with the following properties are suitable alternatives.

[0019] The coating 123 may be applied at room temperature and requires little or no component surface preparation. Once applied, for example by spraying the coating onto the desired area of the component 102, 108, 106, or dipping the component in a coating solution, the coating 123 self-seals to form a highly hydrophobic glass like ceramic surface coating 123.

[0020] The alkoxysilanes can be applied to leave coatings with thicknesses of just 6 m, which is considerably less than the minimum radial clearance between the rotor blades 106 and internal surface of the stator 102. Thus, because the radial clearance is sealed by the liquid ring 100, no additional machining operations are required pre or post application. This also means that the coating 123 can be applied to existing liquid ring pumps already in operation to provide the benefits thereof retrospectively.

[0021] Once applied, the coating 123, develops a surface with a low coefficient of friction which in turn greatly reduces the power losses, in use, due to reduced friction between the liquid ring 100 and the coating 123 on surface of the chamber 102. The coatings also advantageously improve heat transfer from the work fluid thus increasing convective heat loss through the stator and to the external atmosphere.

[0022] Axial chamber walls (not shown) which define the rest of the chamber 102 shown in FIG. 2 are also preferably coated with the coating comprising at least one alkoxysilane to further reduce the power losses and improve heat transfer (where required).

[0023] This is better illustrated in FIG. 3, which shows an exploded view section of a two-stage liquid ring pump according to the present invention. The pump comprises two inlets 212 and two outlets 216 through which gas is conveyed to and from the pumping chamber 202. The pumping chamber 202 is defined by two axial end plates 202b which are connected to either end of a generally cylindrical chamber 202a. The work fluid, usually water, for the liquid ring is conveyed to the chamber 202 from a liquid source via the inlets 210 located in the axial end plates 202b and coaxial with the shaft 201. The axis of the shaft 201 is again eccentric to the central axis of the chamber 202. On rotation of the shaft 201 the work fluid conveyed to the chamber 202 engages with the rotor blades 206 extending radially outward from a hub 208 to form an annular liquid ring (not shown) in the pumping chamber. The pumping action of the liquid ring pump is substantially identical to that described and illustrated for FIGS. 1 and 2 except that gas can enter the pump via two inlets 212 and is exhausted via two outlets 216.

[0024] In order to reduce power losses due to friction, the surfaces of at least the chamber walls 202a and 202b defining the chamber 202 are provided with a coating comprising an alkoxysilane.

[0025] In both the examples shown in FIGS. 2 and 3 it is also advantageous to coat at least part of the surface of the rotor 106, 206, rotor hub 108, 208, and shafts 201 (not shown for FIG. 2) that, in use, will come into contact with the moving work fluid to further reduce power losses due to friction. As the rotor blades 106, 206 are intimate contact with the moving work fluid to form the ring 100, it is advantageous to coat at least their leading surface with the coating 123.

[0026] The coatings according to the present invention last considerably longer that known organic coatings applied to surfaces to reduce fluid friction due to the alkoxysilane's ability to completely coat the pump component surfaces, filling micro-voids and micro-cavities. This, together with the lack of micro-porosity associated with known organic coatings, protects metal components from oxidation mechanisms such as pitting and provides a superior surface finish. In addition, the coating forms a hard, abrasion resistant layer that protects the chamber 102, 202 and rotor 106, 108, 206, 208 surfaces from abrasion by suspended solids contained within the work fluid captured from pumped process gases.

[0027] The hydrophobic coatings formed provide resistance to water ingress along the coating-metal substrate interface of a coated component which, together with the improved bonding process, provides high resistance to de-bonding in cases where the protective coating is penetrated down to the metal substrate.

[0028] Although the examples show are for liquid ring pump components, it will be appreciated that other wet pumps such as rotary vane pumps and screw pumps designed to pump fluids comprising liquids and gas would benefit from having the coatings described herein applied to the surfaces that, in use, would come into contact with the fluid containing the gas/liquid mixtures.

[0029] Thus the improved components and pumps according to the present invention provide significant reductions in power loss and increased longevity compared to the known textured surface or organic coatings, whilst reducing the complexity associated with the rotating canister designs.

[0030] Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

[0031] Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.