RECIPROCATING PUMP FLUID CYLINDER SLEEVE ASSEMBLY.

Abstract

A reciprocating pump includes a fluid end having a body that defines a plunger bore, which mates with a plunger sleeve via a threaded interface. The plunger sleeve defines the through-hole configured to receive an operatively reciprocating plunger within the plunger bore during operation of the reciprocating pump. A packing assembly, including a plurality of stacked O-rings, is disposed between the plunger sleeve and the plunger. A stuffing nut having a threaded profile for mating with a threaded surface of the plunger bore imposes a load against the packing assembly to ensure positive coupling with the plunger.

Description

RECIPROCATING PUMP FLUID CYLINDER SLEEVE ASSEMBLY FIELD OF INVENTION This description relates to positive displacement pumps, and in particular to a fluid cylinder sleeve assembly of a reciprocating pump. BACKGROUND OF THE INVENTION Hydraulic fracturing (also known as fracking) is a process for obtaining hydrocarbons such as natural gas and oil by injecting a fracturing fluid or slurry at high pressure into a wellbore to create fractures in deep rock formations. The hydraulic fracturing process employs a variety of different types of equipment at the well site, including one or more positive displacement pumps, a slurry mixer, fracturing fluid tanks, high-pressure flow iron (pipe or conduit), a wellhead, valves, charge pumps, and trailers on which some of the equipment is transported. Positive displacement pumps are commonly used in oil fields for high-pressure hydrocarbon recovery applications, such as injecting fracturing fluid down the wellbore. A positive displacement pump typically has two sections, one end of MA / a / ZUZZ / UUZ l oo Ref. 332399 power and fluid end. The power end includes a crankshaft driven by an engine that drives the plungers. The fluid end of the pump includes cylinders in which the plungers operate to draw fluid into the fluid chamber and then forcefully push it out at high pressure to a discharge manifold, which is in fluid communication with a wellhead. A sealing assembly, also called a packing assembly or packing box, is used in the cylinder chamber of the pump housing to prevent leakage of fracturing fluid around the plunger during pumping operations. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a perspective view of one modality of a positive displacement pump according to the teachings of the present description; Figure 2 is a cross-sectional side view of one modality of a positive displacement pump according to the teachings of the present description; Figure 3 is a partial cross-sectional side view of one modality of a piston sleeve assembly with a rod seal installed within a fluid cylinder according to the teachings of the present description; Figure 4 is a more detailed partial cross-sectional side view of a plunger sleeve assembly with a rod seal installed inside a fluid cylinder according to the teachings of the present description; Figure 5 is a cross-sectional view of the rod seal according to the teachings of the present description; Figure 6 is a perspective view of one modality of a piston sleeve according to the teachings of the present description; Figure 7 is a perspective view of one modality of an installation tool according to the teachings of the present description; Figure 8 is a partial cross-sectional side view of a second embodiment of a piston sleeve assembly with a surface seal installed within a fluid cylinder according to the teachings of the present description; Figure 9 is a more detailed partial cross-sectional side view of the second modality of a sleeve assembly with a surface seal installed within a fluid cylinder according to the teachings of the present description; Figure 10 is a cross-sectional view of the surface seal according to the teachings of the present description; and Figure 11 is a perspective view of a conventional chain wrench used to secure and turn the installation tool. DETAILED DESCRIPTION OF THE INVENTION During the operation of a positive displacement pump, the dynamic seal packing surrounding the plunger often wears out and sometimes fails, damaging the sealing surface of the hydraulic fracturing fluid end block. At this point, the fluid end block will require costly repair or will be discarded. This type of repair is expensive and time-consuming. The solution described herein uses a sacrificial sleeve around the plunger bore to prevent damage to the hydraulic fracturing fluid end block in the event of packing seal failure. The plunger sleeve described herein has a threaded interface with the fluid end block. This description describes two sealing designs: a rod seal and a surface seal.If the packing seal fails and the sacrificial sleeve is damaged, the sleeve can be easily removed and a new one installed. The sleeve and seal arrangement provides relatively inexpensive and reliable solutions for addressing the washing and / or cleaning of a packing segment in the pump plunger bore. Using the sleeve also increases the lifespan of the pump's fluid cylinder, thereby reducing operating and maintenance costs. As shown in Figure 1, a positive displacement reciprocating pump 100 has a power end 102 operatively coupled to a fluid end 104 by a plurality of tie rods 106. The fluid end 104 has a fluid end block 105 that includes a suction manifold 108 connected to a fluid source that supplies a fracturing fluid, commonly referred to as a slurry, which is a mixture of water, abrasive proppants (silica sand or ceramic), and corrosive chemical additives. The fluid end 104 is also coupled to a discharge manifold 110 that discharges the high-pressure fluid from the pump 100 into a cased wellbore. The pump 100 can also be used to inject a cement slurry into the wellbore for cementing operations. The pump 100 can be aboveground, skid-mounted, or trailer-mounted. Figure 2 is a cross-sectional view of a reciprocating pump 100 incorporating a sacrificial plunger bore sleeve 200 described herein. The pump 100 includes a power end 102 MA / a / ZUZZ / UUZ l □□ operatively coupled to a fluid end 104 having a fluid end block 105 (also referred to herein as fluid end body 105). The fluid end block 105 has a plurality of chambers formed therein, including a plurality of cylinder chambers 208 (only one shown in Figure 2). Each of the cylinder chambers 208 is in communication with a suction manifold 108 and a discharge port 210. A suction cover plate 209 is connected to one end of each cylinder chamber 208 on a rear side of the fluid end block 105 opposite the tie rods 106. A suction valve 211 opens the cylinder chamber 108 to the suction manifold 108 during the pump's inlet stroke. A discharge valve 212 opens the discharge port 210 of the cylinder chamber 208 during the discharge stroke. The fluid end 104 further includes plungers 214 extending through plunger holes 215 defined in cylinder chambers 208. Each plunger 214 is adapted to reciprocate within the corresponding cylinder chamber 208 during operation of the reciprocating pump 100. The power end 102 of the reciprocating pump 100 includes a crankshaft 216 comprising one or more crankshaft turns, corresponding to one or more cylinders 206 of the fluid end 104, and a main shaft. The crankshaft revolutions are connected to the main shaft and each is offset from the crankshaft's rotating axis 216. The crankshaft 216 is mechanically coupled to a power source (not shown) via a slewing gear 218 and a pinion 220. The main gear 218 meshes with the crankshaft 216 and the pinion 220 connects to a power source or motor (not shown).The teeth of the main gear 218 mesh with the teeth of the pinion gear 220, thereby transmitting torque between them. Each revolution of the crankshaft engages with one of the respective pistons 214 via a mechanical linkage 222, each of which includes a connecting rod 224, a crosshead 226, and a short rod 228. Each crosshead 226 is positioned within a hole in the corresponding crosshead 230, within which the crosshead 226 is reciprocated. The connecting rods 224 connect the respective crossheads 226 to the respective crossheads of the crankshaft revolutions. Furthermore, the short rods 228 connect the respective crossheads 226 to the respective crossheads of the pistons 214. During operation, the power source or motor (not shown) rotates the pinion shaft 220, which rotates the pinion gear teeth that mesh with the swing gear 218 and the crankshaft 216. The crankshaft 216 rotates the crank around the central axis of the main shaft. The crank's rotation, in turn, drives the motor. MA / a / ZUZZ / UUZ l □□ the mechanical joints 222, which include the respective connecting rod joints 224, cross joints 226, and short rods 228, causing the cross joints 226 to reciprocate within the corresponding cross joint holes 230. The reciprocating motion of the cross joints 226 is transferred to the respective joints of the plungers 214 via the short rods 228, causing the plungers 214 to reciprocate within the corresponding fluid chambers 208. As the plungers 214 reciprocate within the respective fluid chambers 208, fluid is drawn into the fluid cylinders 206 from the suction manifold 108 and thereafter discharged from the fluid cylinders 206 to the discharge manifold 110. Figure 3 is a more detailed partial cross-sectional view of the fluid cylinder showing one embodiment of the plunger sleeve 200 by using a rod seal 300 (e.g., having an annular body) disposed on the sleeve's outside diameter. The fluid end of the pump includes a body 105 having a plunger bore 215, which includes an inner wall having first and second threaded surfaces of inside diameters 312 and 314. The plunger bore 215 further incorporates a seal assembly 302. The seal assembly 302, also commonly referred to as packing, seal packing, packing assembly, packing stack, or packing box, is disposed in MA / a / ZUZZ / UUZ l □□ the cylinder chamber around the plunger 214 to prevent leakage of fracturing fluid around the plunger during pumping operations. The packing assembly 302 includes multiple individual metal and / or elastomer O-ring seal components (e.g., waste ring, head ring, pressure ring, adapter ring, spacer ring) inserted into a packing box successively to form the packing seal during installation. This seal stack is energized by a gland nut 304 that is also installed on machined contours and a threaded surface of defined internal diameter 314 on the fluid end body 105. The gland nut 304 preloads the seal stack to ensure positive engagement with the plunger 214.To remedy the washing and / or cleaning of the inner wall of the piston bore 215, the fluid cylinder incorporates a piston sleeve 200 (for example, having a tubular or annular body) disposed between the packing assembly 302 and the inner wall of the piston bore 215 of the fluid cylinder. The piston sleeve 200 can be made from a durable, hard material or have a coating selected from the group consisting of steel, a tungsten carbide compound, a non-ferrous metal, and a non-metallic composite material now known or to be developed in the future. The plunger sleeve 200 includes a through-hole 316 that accommodates the plunger 214 as it reciprocates during operation of the reciprocating pump 100. The plunger sleeve 200 includes an outer diameter surface incorporating a threaded profile 306 configured to engage with the threaded surface 312 formed on the fluid end block 105. The threaded interface defined between the sleeve 200 and the block can employ any standard thread profile. Alternatively, a modified tail ACME thread with a round or larger root radius can be used. The plunger sleeve 200 includes an inner wall defining the through-hole 316, and the packing assembly 302 is received within the through-hole 316 of the sleeve such that the packing extends radially between an outer surface of the plunger 214 and the inner wall of the plunger sleeve 200.The 302 gasket seals the defined radial space between the plunger 214 and the inner wall of the plunger sleeve 200 to facilitate sealing of the plunger 214 within the plunger bore of the fluid cylinder. As shown in Figures 3-5, the plunger sleeve 200 includes a stage 308 that defines the first and second segments of the plunger sleeve 200. A first segment of the plunger sleeve 200 defined on a first side of the stage 308 (for example, disposed within the rod seal 300) may have a thinner wall compared to an adjacent, or attached, second segment of the plunger sleeve 200 defined on a second side of the stage 308. An outside diameter of the first segment may be smaller than an outside diameter of the second segment. The rod seal 300 is disposed on an outside diameter surface of the plunger sleeve 200 separate from the packing assembly 302 and functions to prevent the intrusion of hydraulic fluids if the packing seal 302 fails.The 300 rod seal has an internal diameter profile of 500 that is contoured to have higher and lower features to create a seal against the external diameter of the 200 plunger sleeve (Figure 3). The plunger sleeve is omitted from Figure 5 to more clearly illustrate the 500 internal diameter profile. With reference to Figure 6, the plunger sleeve 200 further includes a tool coupling structure 600 configured as a locking feature at an annular end designed to interface with a custom installation tool 700 shown in Figure 7. One end of the cylindrical installation tool 700 is contoured with equidistant rectangular protrusions or flanges 702 that correspond to equidistant rectangular notches 602 on the end of the plunger sleeve 200. To install the plunger sleeve 200, the installation tool 700 is used to rotate the sleeve. ML / a / ZUZZ / UUZ l □□ of the plunger 200 so that the threaded profile 306 interacts with the threaded face of the hole. A chain wrench 1200, such as the one shown in Figure 11, can be used to securely hold and turn the installation tool 700 where its locking features 702 engage or fit with the notches 602 of the plunger sleeve 200. Once the plunger sleeve 200 is advanced into its proper position within the cylinder bore, a plurality of set screws can be advanced radially inward to secure the plunger sleeve 200 in place through through holes 604 in the walls of the plunger sleeve 200 and prevent further rotation. It should be noted that the coupling interface of the plunger sleeve tool 200 and the corresponding face of the custom installation tool 700 can incorporate alternative profiles that allow the installation tool to firmly grip the plunger sleeve, enabling its rotation so that it can advance along the threaded interface with the plunger bore during installation and retract along the same threaded interface during removal and maintenance. For example, the alternative coupling profile of the tool can use triangular teeth or coupling elements of other suitable shapes. ML / a / ZUZZ / UUZ 1OO Figures 8-10 provide several views of another embodiment of the plunger sleeve 800 incorporating an annular surface seal 802. The plunger sleeve 800 also includes an outside diameter surface incorporating a threaded profile 804 configured to engage a threaded profile 801 formed in the fluid end block 805. The threaded interface 804 may employ any standard thread profile. Alternatively, a modified tail ACME thread with a round or larger root radius may be used. The plunger sleeve 800 includes an inner wall defining a through-hole 816 (or internal passage), and a packing assembly 806 is received within the through-hole 816 of the sleeve such that the packing seal assembly 606 extends radially between an outer surface of the plunger 810 and the inner wall of the sleeve 800.The packing assembly 606 seals the defined radial space between the plunger 810 and the inner wall of the sleeve 800 to facilitate sealing the plunger within the plunger bore of the fluid cylinder. The packing assembly 606 is positioned in the cylinder chamber around the plunger 810 to prevent fracturing fluid leakage around the plunger during pumping operations. The packing assembly 606 includes multiple individual metal and / or elastomer O-ring seal components (e.g., waste ring, head ring, pressure ring, adapter ring, spacer ring) inserted sequentially into a packing box to form the packing seal during installation. This packing stack 606 is energized by a gland nut 814, which is also installed on machined contours and a threaded surface 815 in the fluid end block 805.The gland nut 814 preloads the seals 606 to ensure their positive energized engagement with the plunger 810. The plunger sleeve 800 may further incorporate a stage 808 that defines the first and second segments of the plunger sleeve 800. A first segment of the plunger sleeve 800 defined on a first side of the stage 808 may have a thinner wall compared to an adjacent second segment of the plunger sleeve 800 defined on a second side of the stage 808. An outside diameter of the first segment may be smaller than an outside diameter of the second segment. As shown in Figures 8 and 9, the plunger sleeve 800 incorporates an annular groove 812 at the inward-facing end in which the annular surface seal 802 is disposed. The annular surface seal 802 is disposed on the end face of the plunger sleeve 800, separate from the packing assembly 606, and functions to prevent the intrusion of hydraulic fluids if the packing seal 606 fails. As shown in Figure 10, the annular surface seal 802 may have a hole groove of ML / a / ZUZZ / UUZ l □□ 900 lock oriented towards an internal diameter thereof. A metal energizing ring (not shown) may be used with the 802 annular surface seal. Similar to the plunger sleeve 200 shown in Figure 6, the plunger sleeve 800 shown in Figure 8 also includes a tool-coupling profile that may include locking features on an annular end designed to interface and mate with the same custom installation tool 700 shown in Figure 7. One end of the cylindrical installation tool 700 is contoured with equidistant rectangular flanges that correspond to equidistant rectangular notches on the end of the plunger sleeve 800. To install the plunger sleeve 800, the installation tool is used to rotate the sleeve so that its threaded face interlocks with the threaded face of the plunger bore. The same chain wrench, such as the one shown in Figure 11, can be used to securely hold and turn the installation tool 700 that engages the end of the castle element of the plunger sleeve 800.Once the 800 plunger sleeve advances to its proper position within the plunger bore, a plurality of set screws can be used to secure the sleeve in place through through holes in the sleeve walls to prevent further rotation. Certain embodiments of the description provide a fluid cylinder for a fluid end section of a reciprocating pump, comprising a body with a pressure chamber and a plunger bore fluidly communicating with the pressure chamber. The plunger bore includes a packing segment configured to contain a packing assembly. The fluid cylinder includes a plunger sleeve received within the packing segment of the plunger bore seal. The interface between the plunger bore and the sleeve includes a threaded interface for securely engaging and retaining the plunger sleeve within the plunger bore. The plunger sleeve is configured to contain the plunger within its through-hole such that the plunger is configured to reciprocate within the plunger bore during operation of the reciprocating pump.The fluid cylinder includes a retaining mechanism fixed within the piston bore such that the retaining mechanism is configured to retain the sleeve within the packing segment of the piston bore. The novel features of the present invention are set forth below, particularly in the appended claims. However, modifications, variations, and changes to the illustrative embodiments described above will be evident to those skilled in the art, and the piston sleeve assembly for the packing bore described herein therefore encompasses such modifications, variations, and changes and is not limited to the specific embodiments described herein. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A fluid end of a reciprocating pump, characterized in that it comprises: a body defining a plunger bore, the plunger bore having first and second threaded surfaces of internal diameter; a plunger sleeve having a first threaded profile configured for engagement with the first threaded surface of the internal diameter of the plunger bore, the plunger sleeve defining a through-hole configured to receive a reciprocating plunger within the plunger bore during operation of the reciprocating pump; a packing assembly including at least one annular seal disposed between the plunger sleeve and the plunger; and a stuffing nut having a second threaded profile for engagement with the threaded surface of the second internal diameter of the plunger bore.

2. The reciprocating pump according to claim 1, characterized in that it further comprises a rod seal disposed between the piston sleeve and the piston bore, the rod seal having a contoured internal diameter profile that engages with the piston sleeve.

3. The reciprocating pump according to claim 1, characterized in that it further comprises an annular seal disposed at an outer diameter interface between the piston sleeve and the piston bore.

4. The reciprocating pump according to claim 1, characterized in that it further comprises an annular seal separate from the packing assembly and disposed in an annular groove in an end-face interface between the plunger sleeve and the plunger bore.

5. The reciprocating pump according to claim 4, characterized in that the annular seal disposed at the end-face interface between the plunger sleeve and the plunger bore comprises a keyhole groove.

6. The reciprocating pump according to claim 1, characterized in that an end face of the piston sleeve comprises a plurality of circumferential notches configured for coupling with a plurality of circumferential flanges of an installation tool.

7. The reciprocating pump according to claim 1, characterized in that an end face of the plunger sleeve comprises a tool coupling contour configured for coupling with a corresponding circumferential contour of an installation tool that operates to rotate the plunger sleeve so that it advances along the first threaded surface of the plunger bore internal diameter.

8. A fluid cylinder for a fluid end section of a reciprocating pump, characterized in that it comprises: a body defining a plunger bore, the plunger bore having first and second threaded surfaces of internal diameter; a plunger sleeve having a first threaded profile configured for engagement with the first threaded surface of the internal diameter of the plunger bore, the plunger sleeve defining a through-hole configured to receive a reciprocating plunger within the plunger bore during operation of the reciprocating pump; a packing assembly including at least one O-ring disposed between the plunger sleeve and the plunger; a stuffing nut having a second threaded profile for engagement with the second threaded surface of the internal diameter of the plunger bore;and a separate O-ring from the packing assembly, the separate O-ring disposed between the plunger sleeve ML / a / ZUZZ / UUZ l □□ and the plunger bore.; 9. The fluid cylinder according to claim 8, characterized in that the piston sleeve has a stage defining the first and second piston sleeve segments, wherein an outside diameter of the first segment is less than an outside diameter of the second segment, and wherein the separate annular seal is disposed between the first piston sleeve segment and the piston bore.

10. The fluid cylinder according to claim 8, characterized in that the separate annular seal is disposed in an annular groove in an end-face interface between the piston sleeve and the piston bore.

11. The fluid cylinder according to claim 10, characterized in that the separate annular seal comprises a keyhole groove.

12. The fluid cylinder according to claim 8, characterized in that an end face of the plunger sleeve comprises a tool coupling contour configured for coupling with a corresponding circumferential contour of an installation tool that operates to rotate the plunger sleeve so that it advances along the first threaded surface of the plunger bore internal diameter.

13. A plunger sleeve assembly for a reciprocating pump, characterized in that it comprises: a tubular sleeve for installation within a plunger bore of a fluid cylinder of the reciprocating pump, the tubular sleeve having a through-hole configured to receive a plunger; the tubular sleeve having a first threaded profile disposed on an outer surface thereof for coupling with a first threaded surface of the plunger bore; and a first end face of the tubular sleeve having a tool coupling contour configured for coupling with a corresponding circumferential contour of an installation tool that operates to rotate the tubular sleeve so that it advances along the first threaded surface of the plunger bore.

14. The piston sleeve assembly according to claim 13, characterized in that the tubular sleeve has a stage defining the first and second piston sleeve segments, wherein an outside diameter of the first segment is less than an outside diameter of the second segment; and an annular seal disposed at an interface between the first piston sleeve segment and the piston bore.

15. The piston sleeve assembly according to claim 13, characterized in that the tubular sleeve ML / a / ZUZZ / UUZ l □□ has a second end face defining an annular groove configured to receive an annular seal disposed at an interface between the tubular sleeve and the piston bore.

16. The piston sleeve assembly according to claim 13, characterized in that a plurality of through holes is defined in the tubular sleeve, the plurality of through holes being configured to receive a plurality of fixing screws to secure the tubular sleeve within the piston bore.

17. The piston sleeve assembly according to claim 13, characterized in that it further comprises a packing nut having a second threaded profile for coupling with a second threaded surface of the piston bore, wherein the packing nut, when installed in the fluid cylinder, is configured to apply an axial load against the packing assembly to cause positive coupling of the packing assembly with the piston.

18. The piston sleeve assembly according to claim 13, characterized in that it further comprises a packing assembly that includes a plurality of stacked ring seals configured to seal the coupling between the tubular sleeve and the piston.

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