FIELD
The present disclosure relates to valves for high pressure fluid applications, and more particularly, to a valve seat with a ceramic insert for a reciprocating pump.
BACKGROUND
Hydraulic fracturing (a.k.a. fracking) is a process to obtain hydrocarbons such as natural gas and petroleum by injecting a fracking fluid or slurry at high pressure into a wellbore to create cracks in deep rock formations. The hydraulic fracturing process employs a variety of different types of equipment at the site of the well, including one or more positive displacement pumps, slurry blender, fracturing fluid tanks, high-pressure flow iron (pipe or conduit), wellhead, valves, charge pumps, and trailers upon which some equipment are carried.
Positive displacement pumps are commonly used in oil fields for high pressure hydrocarbon recovery applications, such as injecting the fracking fluid down the wellbore. A positive displacement pump may include one or more plungers driven by a crankshaft to create a high or low pressure in a fluid chamber. A positive displacement pump typically has two sections, a power end and a fluid end. The power end includes a crankshaft powered by an engine that drives the plungers. The fluid end of the pump includes cylinders into which the plungers operate to draw fluid into the fluid chamber and then forcibly push out at a high pressure to a discharge manifold, which is in fluid communication with a well head.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of an embodiment of a valve seat with a ceramic insert according to the teachings of the present disclosure;
FIG. 2 is a partial close-up view of an embodiment of a valve seat with a ceramic insert according to the teachings of the present disclosure;
FIG. 3 is a perspective view of an example embodiment of a valve body according to the teachings of the present disclosure;
FIG. 4 is a cross-sectional view of an embodiment of a valve assembly according to the teachings of the present disclosure; and
FIG. 5 is a perspective view of an example embodiment of a frac pump according to the teachings of the present disclosure.
DETAILED DESCRIPTION
Referring to FIG. 1, a cross-sectional view of a valve seat 10 for a fluid inlet valve assembly 40 and/or a fluid outlet valve assembly 40 of a reciprocating pump 50 (FIG. 5) is shown. The inlet valve assembly 40 is disposed in a fluid inlet passage and the outlet valve assembly is disposed in the fluid outlet passage in the fluid end 54 of the pump 50. The valve assemblies 40 may incorporate a spring 42 so that they are spring-loaded. The valve seat 10 described herein is applicable to both the inlet and the outlet valve assemblies, which are hereinafter referred to as the valve assembly without distinction.
The valve assembly 40 includes a valve seat 10 (FIGS. 1 and 2) and a valve body 30 (an example shown in FIG. 3) engaged therewith. The valve body 30, when in its closed position, is seated and engaging the circular opening defined by the valve seat 10. When in its open position, the valve body 30 is lifted away and spaced from the opening defined by the valve seat 10. The valve seat 10 includes a generally tubular body 12 having an inner diameter surface and an opposing outer diameter surface. The inner diameter surface of the valve seat 10 forms a cylindrical bore along a center axis of the valve seat 10, which is coaxial with the fluid passage axis when the valve assembly 40 is disposed in the fluid inlet/outlet passage. The outer diameter surface of the valve seat body 12 contacts and engages an inside surface of the fluid passageway. In an exemplary embodiment, the outer diameter surface of the valve seat forms an interference fit with the wall of the fluid passageway. A sealing element 14, such as an O-ring, is disposed in an annular groove 15 formed in the outer diameter surface of the tubular valve body 12 to sealingly engage the inside surface of the fluid inlet passage. The valve seat body 12 forms an interference fit or is press fit against the inside surface of the fluid cylinder so that the valve seat 10 is securely disposed within the fluid inlet passage. According to certain embodiments, at least a portion of the valve seat 10 and valve body 30 is fabricated from a metal such as carbon steel or stainless steel. The valve seat 10 further includes a collar 16 with an insert 17 that has a tapered or curved shoulder 18 that extends upwardly and radially from the tubular body 12. At a horizontally-oriented interface at the inner diameter surface between the collar 16 and the insert 17 is a chamfer edge 19, so that the insert 17 is slight recessed from the inner diameter surface of the insert body 12, as best seen in FIG. 2. This chamfered edge 19 may be formed by machining, for example. In contrast, the conventional insert has an inner diameter bore surface that is flush with the valve seat body inner diameter surface. In this embodiment shown in FIGS. 1 and 2, the back face of the insert 10 has an angled face 20 that results in the back face of the insert having two angles 24 and 25 that are both greater than 90 degrees. The outer surface of the collar 16 and tubular valve seat body 12 contact and abut against the inside surface of the fluid inlet passage. The collar 16 further includes an annular groove 21 that slightly undercuts into the outer surface of the tubular valve seat body 12. The curved shoulder 18 of the collar 16 extends at an angle from the tubular valve seat body 12. The collar 16 has an outer diameter that is greater than the outer diameter of the tubular valve seat body 12. The valve seat insert 17 is affixed to an upper inside surface of the valve seat collar 16 by press-fit, shrink-fit, bonding, sintering, welding or combinations thereof. The insert 17 has a curved shoulder 18 that flares radially outward and an annular inner diameter ledge 22 that is disposed above the chamfered edge 19.
In an exemplary, non-limiting embodiment, the insert 17 is made or fabricated of a ceramic material that may include zirconia, partially stabilized zirconia, a tungsten carbide such as tungsten carbide nickel, or tungsten carbide cobalt, titanium carbide, silicon nitride, or sialon. The hardness of the ceramic material may range from about 12 to 22 GPa with reference to the Vickers hardness number. In certain embodiments, the entire valve seat 10 and the valve body 30 may be formed from ceramic material or only a portion of one or both of the valve seat and the valve body may be formed from the ceramic material. Generally, it is desirable to use a ceramic insert material that is of a greater hardness than the valve seat body material. The use of an insert 17 thus extends the life span of the valve assembly 40, which is typically subject to corrosion, erosion, or pitting during pump operation.
FIG. 5 is a perspective view of an exemplary positive displacement pump 50 in which the embodiments of the novel valve seat configuration described here can be deployed. A positive displacement pump, also known as a frac pump, is typically driven by high horsepower diesel or turbine engines (not shown). The engine's revolutions-per-minute (RPM) is usually reduced through the use of a transmission. The transmission is usually multi-geared such that higher pump loads use lower gearing and lighter loads use higher gearing. The frac pump 50 comprises two major components: a power end 52 and a fluid end 54 held together by a stay rod assembly 56 that includes a plurality of stay rods and tubes. The power end 52 includes a crankshaft (not explicitly shown) powered by the engine (not explicitly shown) that drives a plurality of plungers (not explicitly shown). The fluid end 54 of the pump includes cylinders (not explicitly shown) into which the plungers operate to draw fluid from a suction manifold 58 into the fluid chamber and then forcibly push out at a high pressure to a discharge manifold 59. The discharged liquid is then injected at high pressure into an encased wellbore. The injected fracturing fluid is also commonly called a slurry, which is a mixture of water, proppants (silica sand or ceramic), and chemical additives. The frac pump increases pressure within the fluid cylinder by reciprocating the plunger longitudinally within the fluid head cylinder. The power end 52 further includes a pinion gear, bull gears, rod caps, bearing housing, connecting rods, crossheads, and pony rods that work together to reciprocate the plunger. Because of the extreme conditions under which a frac pump operates, some of which are discussed above, there is considerable wear and tear on the various component parts including the valve seats and valve bodies in the fluid end 54. Such wear and tear require constant maintenance, and ultimately, replacement of worn parts. Maintenance and repair result in machine downtime and increase the overall cost of oil and gas production. The novel valve seat configuration described herein can be employed for any valve and seal present in the frac pump, as well as other types of equipment that may be present at an exemplary hydraulic fracturing site. An exemplary hydraulic fracturing site employs positive displacement pumps, a slurry blender, fracturing fluid tanks, high-pressure flow iron (pipe or conduit), trailers upon which some equipment are carried, valves, wellhead, charge pump (typically a centrifugal pump), conveyers, and other equipment at the site of a hydraulic fracturing operation or other types of hydrocarbon recovery operations.
The features of the present invention which are believed to be novel are set forth below with particularity in the appended claims. However, modifications, variations, and changes to the exemplary embodiments described above will be apparent to those skilled in the art, and the valve seat with ceramic insert described herein thus encompasses such modifications, variations, and changes and are not limited to the specific embodiments described herein.
Patent Application
20230106466
