Systems and methods for optimizing the fluid environment in a split mechanical seal - Patents.com

Abstract

The mechanical seal assembly includes a gland assembly having a chamber formed in an inner surface for mounting a fluid insert element that facilitates rotation and movement of particles present in the slurry process fluid away from the seal interface formed by the sealing surface of the stationary seal ring.

Description

[Technical field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 311,724, filed February 18, 2022, entitled "SYSTEM AND METHOD FOR OPTIMIZING FLUID ENVIRONMENT IN A MECHANICAL SEAL," which is a continuation-in-part of U.S. Provisional Patent Application No. 17 / 339,397, filed June 04, 2021, entitled "EXTERNALLY ACTIVATED SEAL IN A SPLIT MECHANICAL SEAL," which claims priority to U.S. Provisional Patent Application No. 63 / 035,504, filed June 05, 2020, entitled "EXTERNALLY ACTIVATED SEAL IN A SPLIT MECHANICAL SEAL," the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventional mechanical seals are used in a wide variety of environments and settings to provide a fluid-tight seal, such as in mechanical equipment. Typically, such mechanical seals are provided around a rotating shaft or rod that is mounted within and protrudes from a stationary machine housing.

[0003] Split mechanical seals are used in a wide variety of mechanical devices to provide gas-tight and fluid-tight seals. Typically, such mechanical seals are mounted around a rotating shaft that is mounted in and protrudes from a stationary device. The mechanical seal is typically bolted to the stationary device at the shaft's exit point, thereby preventing pressurized process fluid from being lost from the stationary device. Conventional split mechanical seals include face-type mechanical seals, which include a pair of sealing rings that are concentrically disposed around a shaft and axially spaced apart from one another. Each sealing ring includes a number of sealing faces that are biased into sealing contact with one another. Typically, one sealing ring remains stationary while the other sealing ring is coupled to the shaft and rotates therewith. The mechanical seal prevents pressurized process fluid from leaking to the outside environment by biasing the sealing faces of the sealing rings into sealing contact with one another. Typically, the rotary seal ring is mounted in a holder assembly that is disposed within a chamber defined by the gland assembly. The holder assembly may comprise a pair of holder halves or sections that are secured together by screws. Similarly, the gland assembly may comprise a pair of gland halves or sections that are also secured together by screws. Seal rings are also often split into sections, each section having a pair of sealing faces, such that each ring is a split ring that can be fitted onto a shaft without releasing one end of the shaft.

[0004] A conventional split mechanical seal has rotating and stationary components that are threaded onto a shaft and then bolted to the equipment being sealed. The rotating seal face is inserted into a rotating metal clamp after the sections are threaded onto the shaft. The stationary face and gland sections are then assembled and the split gland assembly is then bolted to the pump housing. Alternatively, the stationary and rotating sealing components may be preassembled into a subassembly that is then installed around the shaft.

[0005] Split mechanical seals, consisting of rotating and stationary subassemblies (e.g., four subassemblies), have the split and primary faces of the metal parts, elastomeric gaskets, and O-rings all in line. This makes it extremely difficult to ensure that all components are restrained in sealing alignment. For example, the O-rings are radially compressed in the grooves, causing them to expand circumferentially with protruding ends that can buckle when mated, causing pinching at the split by the metal and sealing face parts. Traditional methods of offsetting the split of the various parts in the rotating or stationary assemblies cannot be used because the entire subassembly, not the individual parts, is fixed around the shaft. This makes installation of the seal assembly into the equipment easier and faster, but it can cause misalignment of the parts and subsequent measurable leakage from the joints made by the sealing components.

[0006] Traditional split mechanical seal designs have presented several problems for users of these seals. For example, split mechanical seals often do not adequately circulate or remove contaminants present in slurries such as process fluids. If contaminants remain near the split seal faces, they can adversely affect the sealing performance of the mechanical seal and degrade the operation and function of the mechanical seal over time. Summary of the Invention

[0007] The present invention relates to a mechanical seal assembly that includes a gland assembly having a chamber formed in its inner surface for mounting a fluid insert element that promotes the movement of particles present in a slurry process fluid away from a seal interface formed by the sealing surfaces of the rotating and stationary seal rings.

[0008] The mechanical seal assembly of the present invention includes a gland assembly having a body including an outer surface and an inner surface, the inner surface defining at least one gland chamber. A fluid insert element is provided and sized and configured to be mounted in the gland chamber. The fluid insert element has a body having a non-planar bottom surface configured to be exposed to the slurry process fluid in the gland mounting area. The mechanical seal assembly further includes a holder assembly defining a holder chamber and disposed in the gland mounting area, a rotary seal ring disposed in the holder chamber of the holder assembly and having a body with a rotor sealing surface formed at one end, and a stationary seal ring disposed in the gland mounting area and having a body with a stator sealing surface formed at one end. The stator sealing surface and the rotor sealing surface are disposed adjacent to one another to define a sealing interface. The stator sealing surface and the rotor sealing surface have the same size and shape.

[0009] The body of the gland assembly has a first annular portion formed with a first fluid port extending between the inner surface and the outer surface of the gland assembly. The first fluid port is disposed in fluid communication with the gland chamber. The body of the gland assembly may also have a second annular portion formed with a second fluid port extending between the inner surface and the outer surface of the gland assembly for introducing fluid to the gland attachment area. The first annular portion may also include an optional third fluid port formed extending between the inner surface and the outer surface of the gland assembly. The third fluid port is disposed in fluid communication with the gland chamber.

[0010] The bottom surface of the fluid insert element has a curved shape that may be curved laterally. Alternatively, the curved shape of the bottom surface of the fluid insert element may be curved in the middle direction. According to the present invention, the bottom surface of the fluid insert element may have an inclined surface. Specifically, the bottom surface of the fluid insert element may have a first inclined surface and an opposing second inclined surface, each inclined at a first angle, and an intermediate inclined surface disposed between the first and second inclined surfaces and inclined at a second angle, the second angle being greater than the first angle.

[0011] According to one embodiment, the body of the fluid insert element can include a top surface, a plurality of sidewalls coupled to the top surface, and a tower portion extending outwardly from the top surface. The tower portion can include a tower top surface and a plurality of tower sidewalls, one or more of the plurality of tower sidewalls defining a sidewall opening. The tower top surface can define a first fluid opening that is aligned with the first fluid port when the fluid insert element is installed within the gland chamber. The top surface of the body of the fluid insert element can define a second fluid opening that is aligned with the first fluid opening.

[0012] The mechanical seal assembly of the present invention further includes a stator sealing element disposed about the outer surface of the stationary seal ring, an axially movable spring holder plate having a top surface, an opposing bottom surface, and a radially inwardly spaced flange portion, the top surface having a plurality of fastener openings formed therein, a plurality of biased clip assemblies configured to mount about the spring holder plate, the plurality of biased clip assemblies configured for mating engagement with the stationary seal ring to couple the spring holder plate to the stationary seal ring, and a plurality of fasteners for mounting to the fastener openings and the gland fastener holes and for securing the spring holder plate to the top surface of the gland assembly. The gland assembly has a top surface having a plurality of gland fastener holes formed therein. The stator sealing element is positionable in a radially uncompressed state when in a first unloaded position, and the spring holder plate is axially movable when the plurality of fasteners are tightened to axially move the stator sealing element to a radially compressed state when in a second loaded position. A plurality of spring holes are formed in the top surface of the gland assembly, and the seal further includes a plurality of springs for mounting in the plurality of spring holes.

[0013] The holder assembly may include an inner surface having a holder detent groove formed therein. The rotary seal ring has a rotational detent groove formed in its outer surface. Additionally, the stationary seal ring has an inner surface with a groove formed to couple to a retainer of each of the plurality of biased clip assemblies. The biased clip assembly includes an inner spring element and an outer spring element. The inner spring clip includes a body having an inner ridge formed at a first end thereof configured to engage a bottom surface of the spring holder plate and a bend formed at a second, opposite end thereof configured to engage the top surface of the stationary seal ring. The outer spring clip has a first coiled end sized and configured to fit within the bend of the inner spring clip and a bend ledge sized and configured to engage the groove formed in the inner surface of the stationary seal ring.

[0014] In another aspect, the present invention relates to a split mechanical seal, which uses mechanical features that allow the seal to operate safely in a machine, such as a centrifugal pump, using a slurry as a process fluid. The mechanical features utilize existing fluid motion, such as rotational motion of fluid around a shaft and associated components, emanating from a boundary layer of mechanical seal components associated with the shaft, to induce fluid flow and, as necessary, to move, circulate, capture, and evacuate contaminants present in the process fluid. The mechanical features of the present invention may include mechanical inserts that are mounted in selected channels formed at selected locations along an inner surface of a gland assembly mounted to the centrifugal pump. Due to the inherent splits or connections of split mechanical seals, continuous concentric spirals are not desirable. The mechanical inserts of the present invention may be mounted or located in underutilized sections, locations, or arcs of the gland element. For example, an annular cavity or chamber may be formed along an inner surface of the gland that is sized and configured to accommodate the mechanical inserts. The mechanical insert configuration can vary and preferably includes a body with an inclined or arcuate surface facing the process fluid. Thus, the configuration can include open volume arrangements to complex geometries that induce fluid-particle motion within the mechanical seal assembly and affect fluid flow. The purpose of the mechanical insert is to prevent particle adhesion and / or move the particles away from the sealing face of the seal ring. Protection of the mechanical seal interface is important to the operation and life of the split mechanical seal and will reduce maintenance and extend the life of the mechanical seal. [Brief description of the drawings]

[0015] These and other features and advantages of the present invention will become more fully understood with reference to the following detailed description and the accompanying drawings, in which like reference characters indicate like parts throughout the several different views, which illustrate the principles of the invention and which, although not to scale, show relative dimensions. [Figure 1] FIG. 1 is a perspective view of a split mechanical seal of the present invention. [Figure 2A] FIG. 2A is a partial cross-sectional view of a mechanical seal showing a seal ring and sealing element in a separated, unloaded position in accordance with the teachings of the present invention. [Figure 2B] FIG. 2B is a partial cross-sectional view of a mechanical seal showing a sealing element associated with a seal ring in a disengaged, unloaded position in accordance with the teachings of the present invention. [Figure 3A] FIG. 3A is a partial cross-sectional view of a mechanical seal showing a sealing element associated with a seal ring in an engaged and loaded position in accordance with the teachings of the present invention. [Figure 3B] FIG. 3B is another partial cross-sectional view of a mechanical seal illustrating a sealing element associated with a seal ring in an engaged and loaded position in accordance with the teachings of the present invention. [Figure 4A] FIG. 4A is a perspective view of a spring holder plate used in the mechanical seal of the present invention and which can be used to move a sealing element associated with a seal ring into an engaged position and a disengaged position in accordance with the teachings of the present invention. [Figure 4B] FIG. 4B is a perspective view of one of the spring holder sections of the spring holder plate in accordance with the teachings of the present invention. [Figure 5A] FIG. 5A is a partial cross-sectional view of a mechanical seal showing a pre-assembled gland subassembly unit in accordance with the teachings of the present invention. [Figure 5B] FIG. 5B is a partial cross-sectional view of a mechanical seal showing a pre-assembled holder subassembly unit in accordance with the teachings of the present invention. [Figure 6A] FIG. 6A is a perspective view of a stationary seal ring segment used in the split mechanical seal of the present invention. [Figure 6B] FIG. 6B is an exploded partial cross-sectional view with the spring holder plate removed illustrating the bolts, biasing clip assemblies, and spacer elements used in the mechanical seal of the present invention. [Figure 6C] FIG. 6C is an exploded partial cross-sectional view with the spring holder plate, biasing clip assembly, and spacing elements removed to show the bolts and springs used in the mechanical seal of the present invention. [Figure 7] FIG. 7 is a perspective view of a mechanical seal assembly of the present invention. [Figure 8] FIG. 8 is a partial cross-sectional view of the mechanical seal assembly of FIG. 7 in accordance with the teachings of the present invention. [Figure 9] FIG. 9 is a perspective view of a section of a gland assembly in accordance with the teachings of the present invention showing the gland chamber formed in its interior surface. [Figure 10] FIG. 10 is a perspective view of one embodiment of a fluid insert element suitable for attachment to a gland chamber in accordance with the teachings of the present invention. [Figure 11] FIG. 11 is a partial cross-sectional view of the fluid insert element of FIG. 10 in accordance with the teachings of the present invention. [Figure 12] FIG. 12 is a partial cross-sectional view of the mechanical seal assembly of FIG. 7 illustrating the installation of another embodiment of a fluid insert element in accordance with the teachings of the present invention. [Figure 13] FIG. 13 is a perspective view of another embodiment of a fluid insert element suitable for attachment to a gland chamber in accordance with the teachings of the present invention. [Figure 14] FIG. 14 is a bottom perspective view of the fluid insert element of FIG. 13 in accordance with the teachings of the present invention. BEST MODE FOR CARRYING OUT THEINVENTION

[0016] The present invention provides a mechanical seal assembly that uses a gland assembly that defines a gland chamber for mounting a fluid insert element that aids in imparting motion or adjusting, changing, or varying the trajectory of at least a portion of particulates that are present in a slurry process fluid and that are in the area or vicinity of a seal ring component. The present invention is described below in conjunction with the illustrated embodiments. Those skilled in the art will appreciate that the present invention may be implemented in many different applications and embodiments and is not specifically limited to the specific embodiments described herein.

[0017] As used herein, the terms "mechanical seal assembly" and "mechanical seal" are intended to include various types of mechanical fluid sealing systems, including single or integral seals, split seals, concentric seals, spiral seals, tandem seals, dual seals, cartridge seals, gas seals, and other known mechanical seal and sealing types and configurations.

[0018] The term "shaft" is intended to refer to any suitable device to which a mechanical seal can be attached in a mechanical system, including axles, rods, and other known devices. A shaft may move in any selected direction, such as, for example, rotationally or reciprocally.

[0019] As used herein, the terms "axial" and "axially" refer to directions generally parallel to the axis of any shaft. As used herein, the terms "radial" and "radially" refer to directions generally perpendicular to the axis of any shaft. The terms "fluid" and "fluids" refer to liquids, gases, and combinations thereof.

[0020] As used herein, the term "axially inner" or "axially internal" refers to the portion of the mechanical seal proximal to the stationary equipment and stationary equipment on which the mechanical seal is used. Conversely, as used herein, the term "axially outer" or "axially external" refers to the portion of the stationary equipment and seal assembly distal to the mechanical system.

[0021] As used herein, the term "radially inner" refers to the portion of the seal assembly proximal to any shaft. Conversely, the term "radially outer" refers to the portion of the mechanical seal distal from any shaft.

[0022] As used herein, the terms "stationary equipment" and / or "stationary surface" are intended to include any suitable stationary structure that accommodates a shaft or rod to which a seal with a gland is secured.

[0023] As used herein, the terms "process medium" and / or "process fluid" generally refer to the medium or fluid being transported through stationary equipment. In a pump application, for example, the process medium is the fluid being pumped through the pump housing.

[0024] The term "gland" as used herein is intended to include any suitable structure that enables, facilitates, or assists in the fastening of a mechanical seal to stationary equipment, while at the same time at least partially surrounding or containing one or more seal components. If desired, the gland may also provide fluid access to the mechanical seal. Those of ordinary skill in the art will also appreciate that the gland assembly may form part of the mechanical seal assembly or part of the stationary equipment.

[0025] The term "slurry" or "slurry process fluid" as used herein is intended to include process fluids or other types of fluids that contain solid particles or particulates. Thus, a slurry can be a mixture of denser solid matter particulate material suspended in a carrier medium such as water. The most common use of slurries is as a means of transporting solids or separating minerals, where the carrier medium is pumped by a device such as a centrifugal pump employing the mechanical seal assembly of the present invention. The solid particles can be of various sizes. The particles settle below a certain transport rate, and the mixture may behave like a Newtonian or non-Newtonian fluid. Depending on the mixture, the slurry may be abrasive and / or corrosive. The fluid may be a Newtonian fluid, having or exhibiting Newtonian properties, such as a change in viscosity only in response to changes in temperature or pressure. Specifically, the viscosity of a Newtonian fluid is constant for a constant temperature, regardless of the amount of shear applied to the fluid. Thus, a Newtonian fluid has a proportional relationship between viscosity and shear stress. Newtonian fluids have the ability to relatively easily and quickly precipitate particulates from the carrier medium. Newtonian fluids are also called settling slurries. The particulates in a settling slurry are typically about 100 μm or larger. The fluid may also be a non-Newtonian fluid that has or exhibits non-Newtonian properties, where the viscosity of the non-Newtonian fluid decreases or increases as a function of the type of fluid when a shear force is applied to it. Non-Newtonian fluids are also called non-settling slurries (e.g., homogeneous mixtures) because particulates are less likely to settle in non-Newtonian fluids. In non-settling slurries, the fluid contains a more homogeneous mixture of fluid and particulates. The particulates in a non-settling slurry are typically less than about 100 μm. There are various types of slurries, such as clean slurries, light slurries, and heavy slurries.

[0026] 1-6C show a mechanical seal 10 according to the teachings of the present invention. The illustrated mechanical seal 10 is preferably concentrically mounted about a shaft (not shown) and may be secured to an outer wall of a stationary equipment by fasteners such as bolts received between the illustrated bolt tabs 14. The mechanical seal 10 constructed according to the teachings of the present invention forms a fluid-tight seal, thus preventing process media, such as hydraulic oil, from escaping from the stationary equipment. This fluid-tight seal is achieved by a pair of sealing members, illustrated as a rotating seal ring 20 and a stationary seal ring 30, which form a seal therebetween. Each of the seal rings 21, 31 includes a pair of seal ring halves or segments and further includes a smooth arcuate sealing surface 21, 31, respectively. The smooth arcuate sealing surface 21, 31 of each seal ring is biased into sealing contact with the corresponding sealing surface 21 or 31 of the other seal ring. Preferably, the seal rings 20, 30 are each split into a pair of segments for ease of installation, as described below. The sealing surfaces 21, 31 of the seal rings form a fluid-tight seal operable over a wide range of operating conditions, including vacuum conditions. The rotating seal ring 20 is mounted within a holder assembly 110, which is mounted within a gland assembly 40, and the stationary seal ring 30 is mounted within the gland assembly 40.

[0027] 2A-3B and 5B, the illustrated holder assembly 110 defines a space 111 that receives and retains the rotary seal ring 20. The holder assembly 110 is separable for ease of assembly and installation. In one embodiment, the holder assembly 110 includes a pair of arcuate holder segments 112 that are joined together to form the annular holder assembly 110. The holder assembly 110, or each of the arcuate holder segments 112 if the holder assembly is separable, includes a radially outer surface 116 that faces the gland assembly 40 and a first generally radially inner surface 124 (in addition to a radially innermost surface 138) that seals against the seal ring 20 and defines the space 111 that receives and retains the rotary seal ring 20.

[0028] A sealing element, such as an O-ring 188, is concentrically mounted around the rotary seal ring 20 to provide a seal between the rotary seal ring 20 and the holder assembly 110. As shown, the O-ring 188 is preferably mounted on the radially outer surface 184 of the axially inner portion of the rotary seal ring 20 and seals against the radially inner surface 124 of the holder assembly 110. The radially inner surface 124 of the holder assembly 110 includes a detent groove 189 for receiving and retaining the O-ring 188 mounted on the rotary seal ring 20, which facilitates assembly and operation of the mechanical seal and maintains the rotary seal ring 20 in an optimal position.

[0029] Other sealing members can seal the interfaces between different components of the mechanical seal 10. For example, a flat annular elastomeric gasket 60 can be used to seal the interface between the gland assembly 40 and the stationary equipment. Additionally, if the holder assembly 110 is split, a holder gasket 160 can be installed in a corresponding groove 158 to seal the holder sections 112 together. A holder / shaft elastomeric member, illustrated as an O-ring 142, is disposed within the holder groove 140 formed along the inner surface 138 to seal between the rotary seal ring holder assembly 110 and the shaft 12. A stationary seal ring / gland elastomeric member, illustrated as an O-ring 202, seals the interface between the stationary seal ring 30 and the gland assembly 40 and exerts radially inward pressure on the stationary seal ring 30. A gland gasket 76 is disposed within the gland gasket groove 70 (FIG. 3A) to form a seal between the gland halves when they are assembled together. Those skilled in the art will appreciate that the mechanical seal assembly 10 may include any suitable means for sealing between the different components.

[0030] Additionally, the illustrated split mechanical seal 10 may include a detent mechanism (not shown), such as an axially extending pin or flat surface element between the rotating seal ring 20 and the holder assembly 110 to prevent relative rotational motion between the rotating seal ring and the holder assembly 110. One of ordinary skill in the art would understand that suitable fasteners, such as bolts, may be used to secure the gland halves and the holder halves together. Some components of the mechanical seal 10 of the present invention are similar to the mechanical seal assemblies described in U.S. Patent Nos. 5,571,268, 7,708,283, and 10,352,457, the contents of which are incorporated herein by reference. [Patent Document 1] U.S. Patent No. 5,571,268 [Patent Document 2] U.S. Patent No. 7,708,283 [Patent Document 3] U.S. Patent No. 10,352,457

[0031] The illustrated holder assembly 110 for mounting the rotary seal ring 20 is disposed within and spaced radially inward from the chamber 24 defined by the gland assembly 40. However, it should be understood that the holder assembly 110 need not be disposed within the gland assembly 40. Instead, the holder assembly 110 may be spaced axially from the gland assembly 40. The holder assembly 110 further includes an inner stepped surface defining a second axially extending surface 133. A radially inwardly extending first wall 132 is formed between the radially inner surface 124 and the axially extending surface 133. As shown, the inner axially extending surface 133 and a radially innermost axially extending surface or inner holder surface 138 define therebetween an axially innermost second wall 134 which serves as the bottom of a cavity or rotary seal ring receiving space 111 (FIG. 2B) for receiving the rotary seal ring 20.

[0032] In one embodiment, the sealing element or O-ring 188 that seals between the rotary seal ring 20 and the rotary seal ring holder 110 is received in a groove 189, such as a detent groove, formed in the radially inner surface 124 of the holder assembly 110. The detent groove 189 is sized, positioned, and configured to receive the radially outermost portion of the O-ring 188 and to position and mount the O-ring 188 relative to the holder assembly 110 during installation without affecting operation. The detent groove 189 preferably receives the O-ring 188 above the stepped wall 132. Alternatively, the detent groove 189 receives the O-ring at another location between the holder assembly 110 and the rotary seal ring 20. A significant advantage of the detent groove 189 and its location on the radially inner surface 124 of the holder is that it reduces the amount of compression required to receive the O-ring 188 in the groove.

[0033] The illustrated rotary seal ring 20 includes a generally smooth arcuate inner surface 172 and an outer surface that includes several surfaces, including a first outer angled surface 182 forming a skirt, a relatively flat outer surface 184, and an axially inwardly tapered or angled outer surface 186. The rotary seal ring 20 also includes a smooth arcuate sealing surface 21 disposed on the top of the ring 20. As best seen in Figures 3B and 5B, the rotary seal ring detent groove 92 is formed in the flat outer surface 184 adjacent to the first angled surface 182. The detent groove 92 formed in the rotary seal ring 20 serves at least two primary functions. First, groove 92 helps position rotary seal ring 20 in the correct position relative to holder assembly 110, and second, groove 92 allows rotary seal ring 20 to be preassembled in holder assembly 110 by forming a dual capture groove (between holder detent groove 189 and rotary seal ring detent groove 92) that captures O-ring 188 therebetween while retaining rotary seal ring 20 in holder assembly 110. Rotary seal ring inner surface 172 may be formed with a generally rectangular cutout (not shown) for mounting onto holder projections (not shown) and coupling components. The inner diameter of rotary seal ring inner surface 172 is larger than the diameter of the shaft to allow for ring fitting therearound. The diameter of rotary seal segment outer surface 184 is the same as or slightly smaller than the diameter of holder segment axially extending surface 133 for mounting engagement to holder assembly 110. The diameter of the outermost surface of the rotary seal ring 20 is less than the inner diameter of the inner surface 124 of the holder assembly 110. One of ordinary skill in the art will readily appreciate based on the teachings herein that the rotary seal ring 20 may have any suitable configuration for connecting with and sealing against another sealing element, such as the static seal ring 30.

[0034] As shown in FIGS. 1-3B and 5A, the illustrated mechanical seal 10 also includes a gland assembly 40. The exemplary gland assembly 40 includes a pair of arcuate gland sections 41, 42 that mate together to form an annular seal gland assembly 40. The gland sections 41, 42 are configured to engage with one another to facilitate assembly and operation of the mechanical seal assembly 10. The gland assembly sections 41, 42 may employ an interlocking mechanism to facilitate engagement of the gland sections. Each exemplary gland section 41, 42 may include an inner surface with a first face 46 at an axially outer end with an angled lead-in surface 52, and an integrally formed stepped second face 50 extending radially outward from the first face 46. The first face 46 and second face 50 together form a first mating annular wall 48. The stepped second face 50 transitions to a radially inwardly sloping surface 56. As mentioned above, the inner surface of the gland section formed by the faces 46, 48, 50, and 56 defines the space 24 for receiving the holder assembly 110. Additionally, each of the gland sections 41, 42 has a pair of screw housings 80, 82 integrally formed therewith. Each screw housing 80, 82 may include a transverse fastener receiving opening 84 formed substantially therethrough. The transverse opening 84 receives a screw 90 for fastening the gland sections 41, 42 together. The gland assembly 40 also includes a housing gasket groove 58 formed along a bottom inner surface 59 of the gland assembly 40. The groove 58 receives a flat annular elastomeric gasket 60. The gland assembly 40 also includes an axially outer top surface 62 having a plurality of spring holes 64 and a plurality of fastener holes 66 formed therein. The spring holes 64 receive spring elements 80 and the fastener holes receive suitable fasteners, such as bolts 250.

[0035] As shown in Figures 2A-3B, 5A and 6A-6C, and particularly Figure 6A, the illustrated stationary seal ring 30 may also comprise a pair of arcuate seal ring segments, each identical or generally identical to the other. The illustrated stationary seal ring segment may comprise a generally smooth arcuate inner surface 32 extending parallel to the shaft axis and an opposing outer surface 36. A circumferentially extending recess or groove 33 is formed along an inner wall of the inner surface 32 sized and configured to receive a retaining portion of a biasing clip assembly 210 for mounting and retaining the stationary seal ring 30 to a spring retaining plate 230, as will be described in more detail below. The groove 33 may be continuous or discontinuous. If discontinuous, the groove may be formed as a series of spaced recesses along the inner surface 32. The outer surface 36 of the stationary seal ring 30 preferably comprises an axially extending first outer surface 190 terminating in a radially outwardly extending angled receiving surface 192. The stationary seal ring 30 preferably includes an axially outer upper surface 194 and an opposing smooth axially inner arcuate ring sealing surface 31 at the bottom of the seal ring. The upper surface 194 has a series of recesses or notches 196 formed therethrough that are sized and configured to selectively receive and / or engage at least a portion of the biasing clip assembly 210. This configuration facilitates alignment and receipt of the stationary seal ring 30 within the chamber 24, as well as acting as a mechanical obstacle to prevent the stationary seal ring 30 from rotating with the shaft 12 and the rotating seal ring 20.

[0036] The inner diameter of the stationary seal ring 30 defined by the inner surface 32 is larger than the shaft diameter and can also be larger than the diameter of the inner surface 172 of the rotary seal ring 20, if desired, to allow for relative movement therebetween. Thus, the stationary seal ring 30 remains stationary as the shaft rotates. An elastomeric sealing member, such as an O-ring 202, exerts sufficient radially inward biasing force to bring the seal ring segment sealing surface 35 into sealing contact with the other stationary seal ring segment. Furthermore, the O-ring 202 forms a fluid-tight and gas-tight seal between the inner surface 46 of the gland assembly 40 and the stationary seal ring 30. When the O-ring 202 is in the loaded position, it is received within a first mounting area 204 defined by the gland first surface 46, the annular wall 48, and the outer surface 190 of the stationary seal ring 30. In one preferred embodiment, the receiving surface 192 of the stationary seal ring 30 is preferably angled at an angle of about 30 degrees to about 60 degrees, and most preferably about 45 degrees, relative to the stationary seal ring outer surface 190. The stationary seal ring 30 is preferably made of a carbon material or a ceramic material such as alumina, silicon carbide, or the like.

[0037] Additionally, the biasing assembly of the split mechanical seal 10 of the present invention, shown as the biasing clip assembly 210, acts as an axial biasing means by resiliently supporting the stationary and rotating seal rings 20, 30. This is accomplished by axially biasing the seal rings such that the stationary and rotating sealing surfaces 21 and 31 are in sealing contact with one another. As shown in Figures 2A-3B, the seal rings 20, 30 are floatingly and non-rigidly supported in spaced-apart, floating relationship relative to the rigid walls and faces of the gland and holder assemblies 40, 110. As shown in Figures 2A-3B, the seal rings 20, 30 are floatingly and non-rigidly supported in spaced-apart, floating relationship relative to the rigid walls and faces of the gland and holder assemblies 40, 110. This floating, non-rigid support and spaced relationship allows the rotating and static seal segments small floating movement radially and axially relative to shaft 12 while still allowing the rotary sealing surface 21 to follow and make sealing contact with the smooth arcuate sealing surface 31 of the stationary seal ring 30. Thus, the sealing surfaces 21, 31 of the rotating and static seal rings self-align as a result of this floating motion.

[0038] The mechanical seal 10 of the present invention preferably employs a series of biasing clip assemblies 210 attached to the axially outermost ends of the gland assembly 40. The biasing clip assemblies 210 are identical, so only a description of one of the clip assemblies is required. The biasing clip assemblies 210 preferably employ a pair of generally C-shaped spring clips formed as an inner spring clip 216 and an outer spring clip 218. The inner spring clip 216 includes a first lower portion with a ridge 220 that is received within a recess 242 in the spring holder plate 230. The ridge 220 of the inner spring clip 216 engages the recess 242 to help secure the inner spring clip 216 thereto. Additionally, the inner spring clip 216 further includes a bent portion 222 at an opposite end that is received or disposed within a recess 196 formed in the top surface 194 thereof for providing an axial biasing force to the stationary seal ring 30. Thus, the bends 222 function as axial biasing members for applying an axial biasing force to the seal rings 20, 30. This axial biasing force, which is well known to those of ordinary skill in the art, is an inwardly directed force that assists in urging the respective sealing faces 21, 31 of the seal rings 20, 30 into sealing contact with one another.

[0039] The illustrated mechanical seal 10 also includes an axially movable spring holder plate 230, for example as shown in Figures 2A-4B. The illustrated spring holder plate 230 may be formed from a pair of plate sections 231, 233 that are connectable to one another. The spring holder plate 230 includes an annular body with a top surface 232 having a plurality of notches or recesses 234 formed therein, the notches or recesses being circumferentially spaced about a periphery of the body. The top surface 232 defines a series of fastener-receiving openings 236 for receiving fasteners, such as bolts 250. The spring holder plate 230 also includes a bottom surface 238 having a recess 242 formed adjacent an axially extending flange portion 240. The recesses 234 and 242 are configured to receive a portion of the biasing clip assembly 210, such as a selected portion of the inner spring clip 216. The spring holder plate sections have end faces 244 that are configured to mate with the end faces of the other spring holder plate section. One of the end faces 244 has a male projection or protrusion 246 and the other end face has a female hole or surface feature 248. The protrusion 246 is configured to be received within a corresponding hole 248 formed in the opposing end face 244 of the other spring holder plate section. Similarly, the hole 248 is configured to receive a corresponding protrusion formed in the opposing end face of the other holder plate section. The protrusion 246 and the hole 248 allow the holder plate sections to be mechanically coupled to one another. The spring holder plate 230 is sized and dimensioned such that the flange portion 240 is received between the inner surface 46 of the gland assembly 40 and the outer surface 190 of the stationary seal ring 30. When the spring holder plate 230 is tightened by the bolts 250, it compresses the spring 86 and engages the O-ring 202. The O-ring 202 is forced by the flange portion 240 over the lead-in surface 52 of the gland assembly 40 and into the mounting area 204. At the same time, the stationary seal ring 20 is urged axially towards the rotary seal ring 20 by the biasing clip assembly 210.

[0040] The biasing clip assembly 210 of the mechanical seal 10 of the present invention includes an outer spring clip 218 adapted to be mounted over the inner spring clip 216. The outer spring clip 218 has a body including a generally rounded first end 224 configured to mount to and engage an outer surface of the inner spring clip 216, as shown most clearly in FIGS. 2B, 3B, and 6B. The outer spring clip 218 also includes an opposite end with a bent ridge 228 extending outwardly therefrom. The bent ridge 228 overlaps the bent portion 222 of the inner spring clip 216 and is configured to couple to and engage a recess 33 formed along the inner surface 32 of the stationary seal ring 30. The bent ridge 228 of the outer spring clip 218 retains and attaches the stationary seal ring 30 to the gland assembly 40 by engaging the recess 33. By retaining or attaching the stationary seal ring 30 to the gland assembly 40, the components of the mechanical seal 10 can be pre-assembled, which helps facilitate easy installation of the split mechanical seal 10. One of ordinary skill in the art will readily appreciate that the inner and outer spring clips 216, 218 may have any suitable shape or configuration capable of engaging the spring plate holder 230 and the stationary seal ring 30 to apply an axial biasing force to the stationary seal ring and the spring plate holder.

[0041] In assembly and operation, the mechanical seal 10 can be constructed from four select halves or sections with select sealing elements that are preassembled to form a subassembly unit. For example, as shown in FIG. 5A, each gland section of the gland assembly 40 can be preassembled with select elements to form a gland subassembly unit 260 that includes the stationary seal ring 30, the spring holder plate 230, a corresponding half or section of the O-ring 202, and a selected number of biasing clip assemblies 210 that correspond to the number of recesses 234 formed in the top surface 232 of the spring holder plate 230. The inner spring clip 216 is installed on and around the spring holder plate 230, and then the outer spring clip 218 is installed over or on the inner spring clip 216. The bent overhang 228 of the outer spring clip 218 engages a recess 33 formed along the inner surface 32 of the stationary seal ring 30, and the opposite end of the spring clip engages a spring holder plate 230. The springs 86 are mounted in spring holes 64 formed in the top surface 62 of the gland assembly 40, and the spring holder plate 230 is secured to the top surface by bolts 250 when placed in corresponding fastener holes 66.

[0042] Similarly, as shown in FIG. 5B, each holder section of the holder assembly 110 can be preassembled with selected elements to form a holder subassembly unit 270, which includes corresponding halves or sections of the rotary seal ring 20 and the O-ring 188. The holder spacer element 126 is disposed within the holder space 111. The spacer element 126 helps to initially axially locate selected seal components, such as the O-ring 188 and the rotary seal ring 20, in selected axial positions to prevent accidental damage to these components. The holder spacer element is removed before the holder assembly is mounted around the shaft 12. The O-ring 188 is disposed within the detent groove 92 formed in the outer surface 184 of the rotary seal ring 20. When the O-ring 188 and the rotary seal ring section are disposed within the gland assembly 40, the O-ring 188 is positioned to be received within the detent groove 189 formed in the inner surface 124 of the holder assembly 120. The detent grooves 92, 189 act to capture and retain the O-ring 188 without excessive axial or radial loading on the O-ring. The gland and holder subassembly units 260, 270 may also include other sealing elements including, for example, the holder gasket 160, the gland gaskets 60, 76, and other O-rings and sealing elements such as the O-ring 142. These sealing elements are also split to fit within the subassembly units.

[0043] When the holder and gland subassembly units are assembled together, the O-rings, e.g., O-rings 188, 202, may become pinched when the sealing elements are moved from an unloaded position to a loaded position. For example, as the O-rings are compressed radially, they may expand circumferentially with the ends of the O-ring segments protruding and potentially buckling when mated, causing pinching by the metal and sealing surface components at the split location. To prevent this from happening, the present invention provides a select collection of components forming a loading assembly that does not prematurely load the O-rings 188, 202 before the subassembly units are assembled around the shaft 12, thereby preventing the O-rings 188, 202 from being pushed out beyond the ends of the holder and gland segments.

[0044] With respect to the holder subassembly unit 270, each of the O-ring 188 segments is concentrically fitted to the rotary seal segment 20 and preferably placed in contact with the rotary seal outer surfaces 182, 184 and the rotary seal ring detent grooves 92 to form the rotary seal ring preassembly. The O-ring 188 and rotary seal ring 20 are installed in the holder assembly 110 such that the O-ring 188 is received within the detent grooves 189, 92 formed in the surfaces 124, 184. This prevents, reduces, or minimizes premature and unnecessary loading of the O-ring 188 when the holder subassembly unit 270 is assembled. Thus, the end areas of the O-ring segments do not extrude beyond the end faces of the holder and gland segments. The holder preassembly units 270, 270 are then fitted to the shaft 12. A coupling mechanism such as a drive flat may be used to rotatably couple the rotary seal ring 20 to the holder assembly 110 for relative rotation therewith. The coupling mechanism may be located on either the holder assembly or the rotary seal ring, but in a preferred embodiment is located on both the rotary seal ring and the stationary seal ring. A detent groove 189 on the holder assembly 110 and a detent groove 92 on the rotary seal ring 20 receive and hold the O-ring 188 in an optimal position. The O-ring 188 exerts sufficient radial inward force to bring the axial seal faces 25 of the rotary seal segments into sealing contact with one another. The holder segments are then secured together by tightening the screws 170 that are securely held within the fastener receiving apertures 164. The rotary seal ring segments are spaced from the inner surface 124 of the holder assembly and non-rigidly supported therein by the O-ring 188, allowing for small radial and axial floating motion of the rotary seal ring 20. When the O-ring 188 is placed in the detent groove, it is in a no-load position.

[0045] With respect to the gland pre-assembly unit 260, the O-ring 202 is placed around the stationary seal ring 30 and then adjacent to the lead-in surface 52 formed along the inner surface of the gland assembly 40. The springs 86 are mounted within corresponding spring holes 64 formed in the top surface 62 of the gland assembly 40. The spring holder plate 230 is secured to the gland assembly top surface 62 by partially tightening the bolts 250 into the fastener holes 66. The spring holder plate 230, the springs 86, and the bolts 250 can form a load assembly. A number of biasing inner clips 216 are mounted along the perimeter or outer edge of the top surface 61 of the gland assembly. The ridges 220 at the first ends of the inner spring clips 216 are mounted in recesses 242 formed in the bottom surface 238 of the spring holder plate 230. The outer spring clip 218 includes a bent ledge 228 with an end or tip that, when attached to the inner spring clip 216, is received in a groove 33 formed in the inner surface 32 of the stationary seal ring 30. The O-ring 202 is captured between the lead-in surface 52 (FIG. 3B) and the outer surface 190 of the rotary seal ring 30.

[0046] As shown in FIGS. 2A and 2B, the gland subassembly unit 260 places the O-ring 202 in the disengaged, unloaded position, and the holder subassembly unit 270 places the O-ring 188 in the detent grooves 188, 92 to disengage, unloaded position. Thus, the O-ring 188, 202 is not extruded beyond the sealing surfaces of the holder and gland sections. Once fully assembled, an operator can move the O-ring 188, 202 to the engaged, loaded position by axially moving the spring holder plate 230 inward. For example, an operator can selectively tighten the bolt 250 using a suitable tool, such as a wrench. When tightened, the bolt 250 acts to move the spring holder plate 230 inward along the axis against the bias of the spring 86. The bottom surface of the flange portion 240 contacts the O-ring 202 and urges the O-ring 202 in an axially inward direction beyond the angled lead-in surface 52 and into the space 204. The O-ring 202 is thus urged (e.g., loaded) into the region 204 by radial compression such that the O-ring is disposed in sealing contact with the outer surface 190 of the stationary seal ring 30 and the inner or inner surface 46 of the gland assembly 40. The O-ring 202 is thus disposed in an engaged and loaded position. Furthermore, when the stationary seal ring 30 is coupled to the spring holder plate 230 by the biasing clip assembly 210, axial movement of the spring holder plate 230 acts to push or move the stationary seal ring 30 in an axially inward direction. The stationary seal ring 30 contacts the rotary seal ring 20 via the sealing surfaces 21, 31, thus urging the rotary seal ring 20 in an axially inward direction. Axial movement of the rotary seal ring 20 pushes the O-ring 188 out of the detent groove 189 formed in the inner surface 124 of the holder assembly 110. Once the O-ring 189 is out of the detent groove 189, it is compressed (e.g., loaded) between the inner surface 124 of the holder assembly 110 and the outer surface 184 of the rotary seal ring 20. Thus, the O-ring 188 is contained within the detent groove 92 when in both the loaded and unloaded positions.Detent grooves 189 and 92 are preferably separate grooves with curved cross-sections and sized and configured to receive O-ring 188 .

[0047] Thus, the illustrated load assembly can be used to move the O-rings 202, 188 axially to an engaged and loaded position where they are radially compressed. The O-rings are compressed after the gland and holder subassembly units are assembled and secured to the fixture around the shaft. The load assembly of the present invention avoids the O-rings being pushed past the end faces prior to assembly where they may be pinched when the subassembly units are secured together. Because the gland and holder surfaces that define the area where the O-rings 202, 188 are mounted are in contact with each other prior to the O-rings being radially compressed in the sealing position, there are no protruding ends of the O-ring segments that could lead to mis-mounting of the sealing element.

[0048] The spring holder plate 230 further includes sections 231, 233 that are secured together using male and female mechanical connections. Before being tightened by an operator, the spring holder plate 230 serves to hold the rotating and stationary O-rings 188, 202 in a free or unloaded position while the gland and holder subassembly units 260, 270 are secured around the shaft. The pre-assembled subassembly units 260, 270 allow for sequential installation of these units. Specifically, the holder subassembly unit 270 (e.g., rotating subassembly unit) is secured to the shaft 12, and then the gland subassembly unit 260 (e.g., stationary subassembly unit) is secured to a stationary device around the rotating component. Axial movement of the spring holder plate 230 via the bolts 250 presses the sealing surfaces 21, 31 and the rotating and stationary O-rings 188, 202 into their operating positions. Thus, a single element can be used to displace the O-rings 188, 202 from a radially uncompressed state (eg, an unloaded position) to a compressed, energized state (eg, a loaded position).

[0049] Another embodiment of the mechanical seal assembly of the present invention is shown, for example, in Figures 7-14. Like reference numerals indicate like or similar parts throughout the various figures. The mechanical seal assembly 300 forms a no-flush or zero-flush mechanical seal assembly since no external fluid, such as a flushing or barrier fluid, needs to be introduced into the seal interior to flush particulates from the sealing face of the seal ring. Specifically, the illustrated mechanical seal assembly 300 of the present invention relates to a split mechanical seal assembly that uses a gland assembly having a gland chamber formed in its inner surface that is sized and configured to receive one or more fluid insert elements or components. When mounted within the gland chamber, the fluid insert components form an expanded fluid volume space that facilitates circulation of slurry process fluid through the rotating elements of the seal. The illustrated mechanical seal assembly 300 is preferably concentrically mounted around the shaft 12 and can be secured to the outer wall of a stationary device by fasteners such as bolts received between the illustrated bolt tabs 14 or gland land areas 370. A mechanical seal assembly 300 constructed in accordance with the teachings of the present invention provides a fluid-tight seal, thus preventing slurry process fluid from escaping stationary equipment. The fluid-tight seal is achieved by a pair of sealing members, illustrated as a rotating seal ring 320 and a stationary seal ring 330, forming a seal therebetween. Each of the seal rings 20, 30 includes a pair of arcuate seal ring halves or segments, each of which further includes a smooth arcuate sealing face or surface 324 and 334, respectively. The seal ring segments may be identical or substantially similar to one another. The smooth arcuate sealing surface 324, 334 of each seal ring is biased by the biasing clip assembly 210 into sealing contact with a corresponding sealing surface of the other seal ring to form a fluid-tight seal. The sealing surfaces 324, 334 of the seal rings form a fluid-tight seal operable over a wide range of operating conditions, including vacuum conditions. The sealing surfaces 324, 334 of each seal ring are preferably the same size and shape to form a line-to-line sealing surface or interface.Specifically, referring to the sealing surface 334 of the stationary seal ring, the illustrated sealing surface 334 has end surfaces that form a two-dimensional plane in a single plane. The sealing surface 334 extends from the inner end surface 332 to the outer end surface. The sealing surface 334 of the stationary seal ring 320 is formed in a similar manner. Thus, the sealing surfaces 324, 334 have the same size and shape, fully overlap, and are aligned to form a fluid-tight seal. Once the rotating seal ring 320 is installed in the holder chamber of the holder assembly 380, the holder assembly is in turn installed in the gland mounting area of ​​the gland assembly 340. The stationary seal ring 330 is also installed in the gland mounting area.

[0050] The stationary seal ring segment 330 may include a generally smooth, arcuate inner surface 332 extending parallel to the longitudinal axis of the shaft 12, and an opposing outer surface. A circumferentially extending recess or groove 333 is formed along an inner wall of the inner surface 332 sized and configured to receive a retaining portion of the biased clip assembly 210 for mounting and retaining the stationary seal ring 330 to the spring retainer plate 230, as will be described in more detail below. The groove 333 may be continuous or discontinuous. If discontinuous, the groove 333 may be formed as a series of spaced recesses along the inner surface 332.

[0051] The inner diameter of the stationary seal ring 330, defined by its inner surface 332, is larger than the diameter of the shaft to permit relative motion therebetween. Thus, the stationary seal ring 330 remains stationary as the shaft rotates. An elastomeric sealing member, such as the O-ring 202, exerts sufficient radially inward biasing force to bring the axial sealing face of one seal ring segment into sealing contact with the other stationary seal ring segment. Additionally, the O-ring 202 forms a fluid-tight and gas-tight seal between the inner surface 374 of the gland assembly 340 and the stationary seal ring 330. The stationary seal ring 330 is preferably made of a carbon material or a ceramic material such as alumina, silicon carbide, or the like.

[0052] The illustrated gland assembly 340 has a body 342 coupled to a stationary equipment via known fastening mechanisms and techniques. For example, as shown in Figures 1, 7-9, and 12, the gland assembly 340 may employ bolt tabs 18 that may be disposed about the gland body to accommodate fasteners such as bolts. In the current embodiment, the gland body 342 includes fastener channels 372 formed in the gland land area 370. According to one embodiment, the fastener channels 370 help define the land area 370 and the fastener housings 80, 82 of the gland assembly 340. The fastener channels 372 are sized and configured to accommodate fasteners for securing the gland assembly 340 to the stationary equipment. The gland assembly body 342 has an inner surface 374 and an outer surface 376 that includes a radially outer first annular portion 344 and a radially inner stepped second annular portion 346. One or more gland chambers 360 are formed in the inner surface 376 of the gland assembly. The gland chamber 360 may be formed to extend along the entire usable circumference of the inner surface 374 of the body 342, or may be formed as separate, distinct gland chambers 360, each extending only a portion of the circumference of the inner surface 374. According to one embodiment, multiple gland chambers 360 may be formed in the inner surface 374, collectively extending along an arc of between about 65 degrees and about 90 degrees of the inner circumference defined by the inner surface 374, and preferably extending between about 75 degrees and about 80 degrees of the inner circumference. The gland chamber 360 has a floor 362 and a set of walls 364 that define the gland chamber 360. The inner surface 374 and the fixed devices of the gland assembly 340 form a space 308 (e.g., a gland mounting area) in which other components of the mechanical seal assembly are mounted and that is sized to contain a slurry process fluid. The floor 362 of the gland chamber 360 may have a shape and configuration complementary to the shape of the upper surfaces of the fluid insert elements 440 , 430 .

[0053] The body 342 of the gland assembly 340 is formed with a number of optional radially extending ports. According to one embodiment, the body 342 is formed with a barrier or flushing fluid port 352 at the first annular portion 344. The flushing fluid port 352 extends from the outer surface 376 of the body to the floor 362 of the gland chamber 360. The flushing fluid port 352 can be configured to couple to a fluid line, such as an external piping system, for introducing a flushing fluid, such as water, into the interior space 308 of the mechanical seal assembly 300. The flushing fluid can be used to flush or displace particulates, typically present in a slurry process fluid, from the seal faces 324, 334. The gland assembly 340 can also optionally include a clean-in-place (CIP) fluid port 354 that allows a user access to the interior space 308 of the mechanical seal assembly 300. According to one embodiment, the CIP fluid port 354 is formed in the stepped annular portion 346 of the gland body 342. The CIP fluid port 354 extends from the outer surface 376 to the inner surface 374 of the gland assembly 340. Thus, the CIP fluid port 354 is disposed in direct fluid communication with the interior space 308. The CIP fluid port can be configured to couple to a fluid line, such as a piping system, for introducing a cleaning fluid, such as water, into the interior space 308. The cleaning fluid can be used to displace particulates in the process fluid from the seal interface, thereby clearing particulates from the space 308. The gland assembly 340 can also include an optional mechanical port 348 formed in the first annular portion, the mechanical port 348 extending from the outer surface 376 of the gland assembly to the inner surface or floor 362 of the gland assembly 340. The mechanical ports 348 may be sized and configured to receive fasteners 350 that can be used to secure the fluid insert elements 400 , 430 within the gland chamber 360 .

[0054] The illustrated mechanical seal assembly 300 may also include a holder assembly 380 that defines a space that receives and retains the rotary seal ring 320. The holder assembly 380 may be split to facilitate assembly and installation. In one embodiment, the holder assembly 380 includes a pair of arcuate holder segments that are joined together to form an annular holder assembly. The holder assembly 380, or each arcuate holder segment if the holder assembly is split, includes a body having a radially outer surface 382 that faces the gland assembly 340 and a first generally radially inner surface 384 (in addition to a radially innermost surface 386) that seals against the seal ring 320 and defines a space that receives and retains the rotary seal ring 320.

[0055] A sealing element, such as an O-ring 188, is concentrically mounted around the rotary seal ring 20 to provide a seal between the rotary seal ring 20 and the holder assembly 110. As shown, the O-ring 188 is preferably mounted on a radially outer surface of the axially inner portion of the rotary seal ring 320 and seals against a radially inner surface 384 of the holder assembly 380. The radially inner surface 384 of the holder assembly 380 optionally includes a detent groove 189 for receiving and retaining the O-ring 188 mounted on the rotary seal ring 320, for facilitating assembly and operation of the mechanical seal and for maintaining the rotary seal ring 320 in an optimal position.

[0056] Other sealing members may be provided to seal the interfaces between the different components of the mechanical seal assembly 300. For example, a flat annular elastomeric gasket 60 may be used to seal the interface between the gland assembly 340 and the stationary equipment. Additionally, if the holder assembly 380 is split, a holder gasket 160 may be installed in a corresponding groove to seal the holder sections together. A holder / shaft elastomeric member, illustrated as an O-ring 142, is disposed within a holder groove formed along the innermost surface 138 and seals between the rotating seal ring holder assembly 380 and the shaft 12. A stationary seal ring / gland elastomeric member, illustrated as an O-ring 202, seals the interface between the stationary seal ring 330 and the gland assembly 340 and exerts radially inward pressure on the stationary seal ring 330. A gland gasket 76 is disposed within the gland gasket groove 70 (FIG. 9) to form a seal between the gland halves when they are assembled together. Those skilled in the art will appreciate that the mechanical seal assembly 300 may include any suitable means for sealing between the different components.

[0057] Additionally, the illustrated split mechanical seal 300 may include a detent mechanism (not shown), such as an axially extending pin or flat surface element between the rotating seal ring 320 and the holder assembly 380, to prevent relative rotational motion between the rotating seal ring 330 and the holder assembly 380. One of ordinary skill in the art would understand that suitable fasteners, such as bolts, may be used to secure the gland halves and the holder halves together. Some components of the mechanical seal 300 of the present invention are similar to the mechanical seal assemblies described in U.S. Patent Nos. 5,571,268, 7,708,283, and 10,352,457, the contents of which are incorporated herein by reference.

[0058] According to one embodiment, one or more of the illustrated seal rings 320, 330, holder assembly 380, and gland assembly 340 may include detent grooves similar to the detent grooves described above in connection with the mechanical seal assembly 10. These detent grooves operate and function in the same or similar manner.

[0059] In the mechanical seal assembly 300 of the present invention, an axially external biasing clip assembly 210 is used to generate and apply an axially inwardly extending biasing force to the stationary seal ring 330 to force the rotating and stationary seal ring sealing faces 324, 334 into sealing contact with one another. The illustrated biasing clip assembly 210 also acts as an axial biasing mechanism by resiliently supporting the stationary and rotating seal rings 320, 330. This resiliently supporting is accomplished by axially biasing the seal rings toward one another to force the stationary and rotating seal surfaces 334 and 324 into sealing contact with one another to form a sealing interface. The seal rings 320, 330 are floatingly and non-rigidly supported in spaced-apart floating relationship relative to the rigid walls and faces of the gland assembly 340 and holder assembly 380. This floating, non-rigid support and spaced apart relationship allows the rotating and static seal segments to float radially and axially relative to shaft 12 while allowing the rotary sealing surface 324 to follow and make sealing contact with the smooth arcuate sealing surface 334 of the stationary seal ring 330. Thus, the sealing surfaces of the rotating and static seal rings self-align as a result of this floating motion.

[0060] The mechanical seal assembly 300 of the present invention may employ a series of biased clip assemblies 210 attached to the axially outermost ends of the gland assembly 340. The biased clip assemblies 210 are identical, so only one clip assembly needs to be described. The biased clip assemblies 210 may employ generally C-shaped spring clips formed as an inner spring clip 216 and an outer spring clip 390. The inner spring clip 216 has a first lower end 220 that is configured to be attached between the spring holder plate 230 and the upper or outer surface of the gland assembly 340 when the two are coupled together to secure the first lower end 220 therebetween. According to one embodiment, the end face of the stationary seal ring 330 may be relatively flat. According to another embodiment, the end face of the stationary seal ring 330 may be flat and annular, or the end face may be formed with a recess, such as the recess 196. Although the inner spring clip is described as being mounted within a recess, the present invention also contemplates that the inner spring clip may abut a flat end surface. Additionally, the inner spring clip 216 may include a flexure 222 mounted to or disposed in contact with an upper surface of the stationary seal ring 330 for providing an axial biasing force thereto. The flexure 222 thus functions as an axial biasing member for applying an axial biasing force to the seal rings 320, 330. This axial biasing force, as is well known to those of ordinary skill in the art, is an inwardly directed force that assists in forcing the respective sealing faces 324, 334 of the seal rings 320, 330 into sealing contact with one another.

[0061] The illustrated mechanical seal assembly 300 also includes an axially movable spring holder plate 230. The illustrated spring holder plate 230 may be formed from a pair of plate sections connectable to one another. The spring holder plate 230 includes an annular body with a top surface 232 that may optionally include a plurality of notches or recesses 234 that are circumferentially spaced about the periphery of the body. The top surface 232 defines a series of fastener-receiving openings 236 for receiving fasteners, such as bolts 250. The spring holder plate 230 also includes a bottom surface 238 with a recess 242 formed adjacent an axially extending flange portion 240. The recesses 234 and 242 are configured to receive a portion of the biasing clip assembly 210, such as a selected portion of the inner spring clip 216. The spring holder plate segments have end faces 244 that are configured to mate with end faces of the other spring holder plate segment. The spring holder plate 230 is sized and dimensioned such that the flange portion 240 is received between the inner surface 374 of the gland assembly 340 and the outer surface of the stationary seal ring 330. When the spring holder plate 230 is tightened by the bolts 250, it compresses the plate 230 and engages the O-ring 202. The O-ring 202 is forced by the flange portion over the lead-in surface of the gland assembly 340 and into the mounting area 204. At the same time, the stationary seal ring 330 is urged axially toward the rotary seal ring 20 by the biasing clip assembly 210.

[0062] The biased clip assembly 210 of the mechanical seal 10 of the present invention includes an outer spring clip 216 adapted to be operatively coupled to an inner spring clip 390 and functioning as a retainer. Specifically, the outer spring clip 390 has a body including a generally rounded or coiled first end 392 configured to mount within and engage a bend 222 of the inner spring clip 216. The engagement of the coiled portion 392 with the bend 222 serves to retain and mount the outer spring clip 390. The body of the outer spring clip 390 also includes a bend ridge 394 disposed opposite the coiled portion 392. The bend ridge 394 is configured to overlap an end region of the stationary seal ring 330 and engage and be received within a groove 333 formed in an inner surface 332 thereof. The bent overhang 394 of the outer spring clip 390 retains and attaches the stationary seal ring 330 to the gland assembly 340 by engaging the recess 333. By retaining or attaching the stationary seal ring 330 to the gland assembly 340, the components of the mechanical seal assembly 300 can be pre-assembled, which helps facilitate easy installation of the split mechanical seal assembly 300. One of ordinary skill in the art will readily appreciate that the inner and outer spring clips 216, 390 may have any suitable shape or configuration capable of engaging the spring plate holder 230 and the stationary seal ring 330 to apply an axial biasing force to the stationary seal ring and the spring plate holder.

[0063] 7-11, the mechanical seal assembly 300 includes a fluid insert element 400 sized and configured to be received within the gland chamber 360 formed in the inner surface 374 of the gland assembly 340. The fluid insert element 400 may have any selected size, shape, or configuration. When received within the gland chamber 360, the fluid insert element 400 has an exposed surface that faces and is exposed to the slurry process fluid in the space 308. The exposed surface of the fluid insert element 400 may have any selected shape, and preferably has a non-planar shape formed with one or more curved, angled, or stepped surface features sufficient to promote the movement of the process fluid, and any particulates contained therein, back toward the stationary equipment and away from the seal interface formed by the seal surfaces 324, 334. According to one embodiment, the illustrated fluid insert element 400 has a body 402 having a top surface 404 and a series of side walls or sides 406. The body 402 also has a bottom surface 408 that forms an exposed surface in contact with or exposed to the slurry process fluid. The top surface 404 of the body can have any selected shape or configuration and according to one embodiment includes a stepped tower section 410. The stepped tower section 410 can include a top portion 412 and connected sidewalls 414. The sidewalls 414 can be solid and therefore closed, or alternatively, one or more of the sidewalls 414 can have fluid openings 416 formed therein. The fluid openings 416 can have any selected shape or configuration. The top portion 412 of the tower section 410 can also include an opening 418 that can be aligned with the flushing fluid port 352. Similarly, the body section can also include a fluid opening 420 formed in the top surface 404 that can be aligned with the opening 418 and the fluid port 352. Additionally, the top surface 404 can have an opening 422 aligned with the mechanical port 348 for receiving and retaining a portion of the fastener 350. Adjacent side wall 406B may have a side opening 424 formed therein. To allow for reversibility of fluid insert element 400, openings 422 may also be formed at opposing ends of top surface 404, and additionally, side openings 424 may also be formed in opposing side wall 406A.The illustrated bottom surface 408 can be formed in any selected manner. According to one embodiment, the bottom surface 408 has a curved shape that is curved or extends laterally between side walls 406A and 406B. According to another embodiment, the bottom surface 408 can have a curved shape that is extended in a medial (front-to-back) direction between side walls 406C and 406D. According to another embodiment, the bottom surface 408 may be curved in both the laterally and medial directions.

[0064] According to alternative embodiments, the fluid insert element may include different shapes and configurations to enhance or promote the movement of particulates within the slurry process fluid away from the sealing surfaces of the seal rings 320, 330. For example, as shown in FIGS. 12-14, the illustrated fluid insert element 430 includes a body 432 having a top surface 434 and a series of side walls or sides 436. The body 432 also has a bottom surface 438 that forms an exposed surface in contact with or exposed to the slurry process fluid. The top surface 434 may have any selected shape or configuration, and according to one embodiment includes a stepped tower section 440. The stepped tower section 440 may include a top portion 442 and connected side walls 444. The side walls 444 may be solid and therefore closed, or one or more of the side walls 444 may have fluid openings 446 formed therein. The fluid openings 446 may have any selected size, shape, or configuration. The top portion 442 may also include an opening that is alignable with the flushing fluid port 352. Similarly, the body portion may include fluid openings 420 formed in the top surface 434 that may be aligned with the tower portion openings and fluid ports 352. Additionally, the top surface 434 of the body 432 may have openings 452 formed therein that are aligned with the mechanical ports 348 for receiving and retaining portions of the fasteners 350. Adjacent side walls may have side openings formed therein. For example, as shown in the illustrated embodiment, side walls 436A and 436B may each have openings 454 formed therein. To allow for reversibility of the fluid insert element 430, openings 452 may also be formed at opposing ends of the top surface 434, and further, opposing side walls 436A and 436B may have side openings 454 formed therein. The illustrated bottom surface 438 may be formed in any selected manner. According to one embodiment, the bottom surface 438 has a multi-contour shape that includes both curved and angled regions. For example, the bottom surface 438 may be angled in the middle (e.g., between side walls 436C and 436D). The angled surface may include opposing angled ends 462 and an intermediate angled portion 464. The angled ends 462 may be angled at a smaller or shallower angle than the angle of inclination of the intermediate angled portion 464.The bottom surface 438 also includes a curved region 468 that extends laterally between the side walls 436A and 436B.

[0065] When assembled, the fluid insert elements 400, 430 can be inserted into the gland chamber 360 with the fluid openings aligned with the mechanical port 348 and the flushing fluid port 352. The space 308 formed between the outer surfaces of the seal rings 320, 330, the inner surface 374 of the gland assembly, and the bottom surface of the fluid insert components forms an annular chamber or space 308 that contains the slurry process fluid. The slurry process fluid to be sealed is contained and flows within this space 308. The movement of the rotating components of the mechanical seal assembly 300, such as the holder assembly 380 and the rotating seal ring 320, creates turbulence within the slurry process fluid, which in turn promotes the movement of the process fluid within the space 308. It is during this movement that particulates within the slurry process fluid accumulate at the seal interface. According to another embodiment, the holder assembly 380 can have one or more surface features formed on its outer surface in the form of pumping vanes to further promote the movement of the slurry process fluid. Particulates present in the slurry process fluid may accumulate on the sealing faces 324, 334 of the seal rings 320, 330 during use and may damage the sealing faces over time. To facilitate migration of particulates away from the sealing faces 324, 334 and to protect the seal components, the gland chamber 360 accommodates a fluid insert component having a specially configured bottom surface that facilitates migration of particulates away from the sealing faces by changing the flow dynamics within the space 308. Specifically, the gland chamber 360 may have a depth or height sufficient to accommodate the fluid insert component while increasing the space formed between the bottom surface of the fluid insert component and the outer surface of the holder assembly 380. This arrangement of components provides or creates a larger flow area or volume within the space 308. This substantially increased space or volume allows the fluid insert component to displace particulates from the seal interface, thereby preventing particle deposition and adhesion on the sealing faces 324 and 334.The combination of the gland chamber 360 and fluid insert elements 400, 430 provides a larger flow area volume within the seal, eliminating the potential impact of contaminant particles on the seal faces. As the slurry is pumped or moved during use, the bottom surfaces of the fluid insert elements encourage the movement of particulates away from the seal faces. More specifically, the shape of the bottom surfaces 408, 438 encourages the movement of particulates away from the seal faces, as shown by arrows 470 in Figures 8 and 12. Arrows 470 indicate the exit paths and associated trajectories of fluid particles.

[0066] The advantages of using the fluid insert element are numerous. The fluid insert element 400, 430 aids in additional circulation of the slurry process fluid around the seal faces. The fluid insert element also aids in increasing the dissipation of frictional heat that may be generated at the seal faces. Additionally, the slurry process fluid movement that the fluid insert element generates during use aids in preventing the stationary O-ring from clogging with particulate matter. Additionally, since the fluid flow is driven by the rotating components of the mechanical seal assembly and the fluid insert element promotes the movement of particles away from the seal faces, there is no need to provide or use an external flushing fluid. Thus, there is no need to provide the associated fluid supply structure or power required to flush the mechanical seal assembly 300. Additional surface features may be added to selected rotating components (e.g., the outer diameter of the dynamic / rotating seal face) to increase the fluid flow velocity. Another advantage of the mechanical seal assembly 300 according to the present invention is that the seal can be configured to utilize the available space 308 in the gland assembly to form a gland chamber 360 to optimize fluid flow and slurry process fluid flow characteristics.

[0067] As a simple example, in a conventional 3.5 inch mechanical seal, the typical chamber area between the inner surface of the gland or housing and the holder assembly may be approximately 8.50 cubic inches. In accordance with the present invention, with the combination of the gland chamber 360 and the attached fluid insert elements 400, 430 as shown and described herein, the volume area can be increased to approximately 10.8 cubic inches. Thus, the mechanical seal assembly 300 of the present invention utilizes a fluid insert element that adds approximately 15% to approximately 30% additional volume within the space 308.

[0068] The illustrated fluid insert elements 400, 430 have selected configurations for forming a number of different flow paths, including a return flow path for particulates in the slurry process fluid. The geometry of the fluid insert elements provides a pressure differential due to the flow regime around the rotating shaft 12. This pressure differential induces a fluid flow that moves the slurry particles. The geometry of the bottom surface of the fluid insert elements 400, 430 expels the particles away from the seal face area and imparts momentum to the particles so that they can be expelled back from the seal face to a process fluid reservoir (e.g., in a stationary device). This configuration of the fluid insert elements also eliminates or reduces flush flow requirements (i.e., no flush or zero flush system). One of ordinary skill in the art will readily recognize that the fluid insert elements may have any selected shape or configuration, so long as the bottom surface of the fluid insert elements is configured to impart flow to the process fluid and promote particulate movement away from the seal face.

[0069] The fluid insert elements 400, 430 can be formed using conventional additive manufacturing techniques. Additionally, forming the components as separate components eliminates the need to machine complex patterns and shapes into the inner surface of the gland assembly. The fluid insert elements 400, 430 can also allow fluid to flow independent of the direction of shaft rotation (e.g., bi-directional operation). Additionally, the symmetrical configuration of the fluid insert elements allows for bi-directional operation.

[0070] The fluid insert element may be constructed of any suitable material including, for example, polyurethane, plastic, rubber, EPDM, H-NBR, etc. The material may be selected to provide improved resistance to wear (i.e., the commonly known erosion of stainless steel glands) compared to conventional metallic materials.

[0071] It should thus be seen that the present invention effectively attains the objects set forth above, among those made apparent from the preceding description. Since certain changes may be made to the above construction without departing from the scope of the present invention, it is intended that all matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense.

[0072] Moreover, the following claims are to be understood as covering all the general and specific features of the invention described herein, and all statements regarding the scope of the invention are to be deemed to fall within their scope.

[0073] Having described the invention, what is claimed as new and desired to be secured by Letters Patent is as follows:

Claims

1. 1. A mechanical seal assembly for mounting to stationary equipment having a rotating shaft and containing a slurry process fluid, comprising: a gland assembly configured to be attached to the stationary equipment and to define a gland attachment area, the gland assembly having a body including an outer surface and an inner surface, the inner surface defining at least one gland chamber; a fluid insert element sized and configured to be attached to the gland chamber, the fluid insert element having a body with a non-planar bottom surface configured to be exposed to the slurry process fluid within the gland attachment area; a holder assembly defining a holder chamber and disposed within the gland mounting area; a rotary seal ring disposed within the holder chamber of the holder assembly and having a body with a rotor sealing surface formed at one end; a stationary seal ring disposed within the gland mounting area and having a body with a stator sealing surface formed at one end, the stator sealing surface and the rotor sealing surface disposed adjacent one another to form a sealing interface.

2. The mechanical seal assembly of claim 1 , wherein the stator sealing surface and the rotor sealing surface have the same size and shape.

3. 3. The mechanical seal assembly of claim 2, wherein the body of the gland assembly has a first annular portion having a first fluid port formed therein extending between the inner surface and the outer surface of the gland assembly, the first fluid port being positioned to be in fluid communication with the gland chamber.

4. 4. The mechanical seal assembly of claim 3, wherein the body of the gland assembly has a second annular portion having a second fluid port formed therein extending between the inner surface and the outer surface of the gland assembly for introducing fluid into the gland mounting area.

5. 5. The mechanical seal assembly of claim 4, wherein the first annular portion defines a third fluid port extending between the inner surface and the outer surface of the gland assembly, the third fluid port being positioned in fluid communication with the gland chamber.

6. The mechanical seal assembly of claim 4 , wherein the bottom surface of the fluid insert element has a curved shape.

7. The mechanical seal assembly of claim 6 , wherein the curved shape of the bottom surface of the fluid insert element is curved laterally.

8. The mechanical seal assembly of claim 7 , wherein the curved shape of the bottom surface of the fluid insert element is curved in a medial direction.

9. The mechanical seal assembly of claim 6 , wherein the bottom surface of the fluid insert element has an inclined surface.

10. 10. The mechanical seal assembly of claim 9, wherein the bottom surface of the fluid insert element has a first inclined surface and an opposing second inclined surface, each inclined at a first angle, and an intermediate inclined surface disposed between the first and second inclined surfaces and inclined at a second angle, the second angle being greater than the first angle.

11. 4. The mechanical seal assembly of claim 3, wherein the body of the fluid insert element includes a top surface, a plurality of sidewalls coupled to the top surface, and a tower portion extending outwardly from the top surface, the tower portion having a tower top surface and a plurality of tower sidewalls, one or more of the plurality of tower sidewalls having a sidewall opening formed therein.

12. 12. The mechanical seal assembly of claim 11, wherein the tower top surface defines a first fluid opening that aligns with the first fluid port when the fluid insert element is installed within the gland chamber, and the top surface of the body of the fluid insert element defines a second fluid opening that aligns with the first fluid opening.

13. a stator sealing element disposed about the outer surface of the stationary seal ring; an axially movable spring holder plate having a top surface, an opposed bottom surface, and a radially inwardly spaced flange portion, the top surface defining a plurality of fastener openings; a plurality of biasing clip assemblies configured to be mounted about the spring holder plate and configured for mating engagement with the stationary seal ring to couple the spring holder plate to the stationary seal ring; a plurality of fasteners for mounting in the fastener openings and the gland fastener holes and for securing the spring holder plate to the top surface of the gland assembly; the gland assembly having a top surface with a plurality of gland fastener holes formed therein; 5. The mechanical seal assembly of claim 4, wherein the stator sealing element is positionable in a radially uncompressed state when in a first unloaded position, and the spring holder plate is axially movable when the plurality of fasteners are tightened to axially move the stator sealing element to a radially compressed state when in a second loaded position.

14. The mechanical seal of claim 13 , further comprising a plurality of spring holes formed in the top surface of the gland assembly, the plurality of springs being adapted to mount in the plurality of spring holes.

15. 14. The mechanical seal of claim 13, wherein the holder assembly includes an inner surface having a holder detent groove formed therein, and the rotary seal ring has a rotational detent groove formed in the outer surface thereof.

16. 14. The mechanical seal of claim 13, wherein said stationary seal ring has an inner surface with a groove formed therein to mate with a portion of each of said plurality of biasing clip assemblies.

17. Each of the plurality of biasing clip assemblies comprises:

1. An inner spring clip comprising a body, the body comprising: an internal ridge formed on a first end thereof, the internal ridge configured to engage a bottom surface of the spring holder plate; an inner spring clip having a bend formed at a second opposite end, the bend being configured to engage the top surface of the stationary seal ring; 17. The mechanical seal of claim 16 including an outer spring clip having a first coiled end sized and configured to fit within the bend of the inner spring clip and a bend flared portion sized and configured to engage the groove formed in the inner surface of the stationary seal ring.

Images