Pressurizing plunger pump for gas seal detection system of oil and gas wellhead device

Abstract

The invention discloses a pressurizing plunger pump for an air-tight sealing detection system of an oil and gas wellhead device. The pressurizing plunger pump comprises a pump shell, a plunger, a suction valve group, a discharge valve group, a valve seat, an outer packing box, a baffle ring, a sealing ring and the like. Magnets with N and S poles are arranged on the right end face of the plunger and the left end face of the discharge valve element, so that the discharge valve element is closed as soon as possible. The suction valve element, the suction valve spring seat and the suction valve ball form a rolling pair, and the discharge valve element, the discharge valve ball and the valve seat form a rolling pair, so that the valve elements are prevented from being stuck in reciprocating motion. A through hole is formed in the middle of the suction valve element, the right side end face of the plunger coincides with the left side end face of the valve seat, and the clearance volume is reduced. The outer packing box, the baffle ring and the annular cover plate form a heat dissipation device, the baffle ring is provided with inclined through holes in the circumferential direction, and cooling liquid is promoted to fully take away heat of the pump body. According to the invention, rapid and low-cost pressurization of nitrogen is facilitated, and efficient and low-cost air-tight seal detection of an oil gas wellhead device is assisted.

Description

Technical Field

[0001] The invention relates to the field of oil and gas wellhead devices, in particular to the field of oil and gas wellhead devices, and specifically to a pressurized plunger pump used in a gas seal detection system of an oil and gas wellhead device. Background Art

[0002] With the continuous deepening of oil and gas exploration and development, unconventional resources such as deep and ultra-deep oil and gas, tight oil and gas, and shale gas have become the main battlefields for oil and gas development and production increase. These oil and gas resources face technical difficulties such as deep burial, ultra-high temperature, and ultra-high pressure. Taking the Shendi Chuanke 1 well as an example, its maximum bottom hole pressure reaches 138MPa, which puts forward new, higher, and more stringent requirements for the supporting wellhead equipment. The main functions of the wellhead device include: accurately controlling the oil and gas pressure and flow during the production process, connecting the well repair equipment to complete the well repair operation during the well repair, and sealing the high-pressure oil and gas in the wellbore in an emergency. Therefore, the wellhead device must be tested for airtightness before leaving the factory to ensure the safety of the oil and gas wells and the smooth production.

[0003] At present, the gas seal test of oil and gas wellhead devices uses nitrogen (N2) as the medium. The first-stage compressor first increases the N2 to 35MPa, and then the second-stage plunger pump increases the pressure to the pressure level to be tested, such as 70MPa, 105MPa, 140MPa, 210MPa, etc. The second-stage plunger pump is connected to the oil and gas wellhead device to be tested through a pipeline, and high-pressure N2 is passed into the oil and gas wellhead device to simulate the pressure load of the oil and gas well. During the test process, the oil and gas wellhead device is in a water pool. If the gas seal is poor and leakage occurs, the pressure in the connecting pipeline will decrease. At the same time, the leaked high-pressure N2 will enter the water pool and produce a large number of bubbles, thereby judging the gas seal performance.

[0004] However, the displacement of the existing plunger pump decreases sharply when the pressure increases, and it is difficult to increase the pressure in the high-pressure stage, resulting in a long time for gas seal detection and increased energy consumption. The main reason is that N2 is a compressible medium. When the plunger cavity is compressed, the pressure of N2 increases and the temperature rises. At the end of compression, some high-temperature and high-pressure N2 remains in the clearance volume. When the plunger cavity expands, the high-temperature and high-pressure N2 in the clearance volume expands first to occupy the effective volume of the plunger cavity, and the high-temperature N2 in the clearance volume mixes with the inhaled N2, resulting in the N2 temperature in the plunger cavity at the end of expansion being significantly higher than the temperature of N2 at the suction port. The high temperature corresponds to a low density of N2, and the mass of inhaled N2 is small, that is, the efficiency of the pump is reduced. There is a lag in the closing of the discharge valve core, that is, the discharge valve core has not been completely closed when the plunger cavity begins to expand, resulting in the high-pressure N2 at the discharge port flowing to the plunger cavity, resulting in a reduction in the discharged N2. There is also a lag in the closing of the suction valve core, which causes the N2 in the plunger cavity to flow to the suction port at the beginning of compression, reducing the pump efficiency. In order to avoid this adverse effect, a larger spring force is usually used to overcome the pressure of the suction port N2 on the suction valve core, prompting the suction valve core to close quickly. However, the larger spring force causes a larger pressure difference between the plunger cavity and the suction port, that is, the pressure in the plunger cavity during the expansion phase is significantly lower than that in the suction port. The low pressure corresponds to a small density of N2, resulting in less mass of N2 inhaled. The valve core and the valve seat are in gap contact. If the gap is too small, it is easy to cause the valve core to get stuck. If the gap is too large, the valve core will not seal well under the action of uneven axial force, which will have an adverse effect on the volumetric efficiency of the pump.

[0005] Therefore, it is necessary to invent a pressurized plunger pump for the gas seal detection system of the oil and gas wellhead device to achieve rapid and low-cost pressurization of N2 and ensure efficient and low-cost implementation of the gas seal detection of the oil and gas wellhead device. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a pressurized plunger pump for an oil and gas wellhead device air seal detection system, thereby facilitating efficient and low-cost implementation of oil and gas wellhead device air seal detection.

[0007] The technical solution of the present invention is as follows: A pressurized plunger pump for an air-tightness detection system of an oil and gas wellhead device comprises a pump housing, a hollow cavity is arranged inside the pump housing, a corresponding suction port is arranged below each hollow cavity, a suction valve group, a discharge valve group and a valve seat are installed in the hollow cavity; an outer packing box is installed on the left side of the pump housing, a cavity is arranged in the outer packing box, and a plunger is installed in the outer packing box; the inner cavity of the outer packing box and the hollow cavity of the pump housing constitute a plunger cavity, and the plunger can reciprocate left and right in the plunger cavity; the suction valve group is opened and the discharge valve group is closed, and the plunger cavity sucks fluid from the suction port; the suction valve group is closed and the discharge valve group is opened, and the plunger cavity discharges fluid to the discharge port.

[0008] Furthermore, the suction valve group includes a suction valve spring seat, a suction valve spring, a suction valve core, and a suction valve ball; the suction valve spring seat is installed in the hollow cavity of the pump housing, and an inwardly expanding step is provided at the installation position corresponding to the hollow cavity of the pump housing; the suction valve spring seat is provided with an axial hollow cavity, and the inner and outer sides of the suction valve spring seat are both two-stage structures, and radial and axial positioning are achieved by contacting the step surface between the two-stage structure with the step surface of the hollow cavity of the pump housing; the left end of the suction valve spring seat cooperates with the right end of the outer packing box, and the right end of the suction valve spring seat contacts the valve seat; the valve seat is an I-shaped rotating body structure, and the left and right rotating body parts are respectively a left plate and a right plate; the valve seat is provided with holes along the axial direction The annulus between the left plate and the right plate is connected to the suction port, and a plurality of flow channel holes are provided on the left plate of the valve seat, which are used to connect the suction port and the hollow cavity of the suction valve spring seat; a suction valve spool is provided between the valve seat and the suction valve spring seat, and a suction valve spring is installed between the suction valve spool and the suction valve spring seat; the suction valve spring is subjected to pre-tightening pressure during installation, and under the action of the pre-tightening pressure, the right side surface of the suction valve spool is coplanar and pressed with the left side surface of the left plate of the valve seat; a through hole is provided inside the suction valve spool, and the inner diameter of the right side annular surface of the suction valve spool is smaller than the inner envelope circle diameter of the flow channel hole of the valve seat, and the outer diameter of the right side annular surface of the suction valve spool is larger than the outer envelope circle diameter of the flow channel hole of the valve seat, so the right side surface of the suction valve spool can block the flow channel hole of the valve seat.

[0009] Furthermore, the right section of the suction valve core is provided with a cylindrical surface extending outward, a groove for installing the suction valve ball is provided on the cylindrical surface, and the outer wall of the cylindrical surface is adapted to the inner wall of the large diameter section of the suction valve spring seat, and the suction valve ball is installed between the cylindrical surface and the inner wall of the large diameter section of the suction valve spring seat, and the suction valve core, the suction valve spring seat, and the suction valve ball constitute a rolling pair. With such a design, the rolling pair is conducive to the coaxiality of the suction valve core and the suction valve spring seat, so that the suction valve core is forced along the axial direction, which is conducive to the sealing of the suction valve core and the valve seat, and avoids the suction valve core from being stuck during the reciprocating motion; at the same time, the friction of the rolling pair is relatively small, and the resistance that the suction valve core needs to overcome to open is small, which makes the pressure difference between the plunger cavity and the suction port small, which is conducive to the suction of more N2.

[0010] Furthermore, the discharge valve group includes a discharge valve core, a discharge valve ball, a discharge valve spring, and a discharge valve spring seat; the left side of the discharge valve spring seat is gap-fitted into the hollow cavity of the pump housing, and the right side of the discharge valve spring seat is connected to the pump housing by bolt three; the discharge valve spring seat is provided with a column centered on the axis, and a discharge valve spring is installed outside the column; a through hole is provided on the side of the discharge valve spring seat, and a connecting hole is provided on the pump housing corresponding to the through hole, and the two holes together constitute a discharge port; the left side of the discharge valve spring is installed in an annular groove on the right side of the discharge valve core; a conical surface is provided on the left side of the discharge valve core, and a conical surface is also provided on the inner wall of the left hole of the valve seat corresponding to the discharge valve core, and the conical surface of the discharge valve core contacts with the conical surface of the valve seat to form a sealing surface.

[0011] Furthermore, the outer peripheral surface of the discharge valve core is provided with a plurality of support frames, the support frames are provided with grooves for installing the discharge valve balls, the discharge valve balls are provided between the support frames and the inner wall of the valve seat, the discharge valve core, the discharge valve balls and the valve seat form a rolling pair, the rolling pair is conducive to the coaxiality of the discharge valve core and the valve seat, and promotes the discharge valve core to be stressed along the axis direction, which is conducive to the sealing of the discharge valve core and the valve seat, and avoids the discharge valve core from being stuck during the reciprocating motion. At the same time, the friction of the rolling pair is relatively small, the resistance to be overcome by the discharge valve core to open is small, and the pressure difference between the plunger cavity and the discharge port is small, which is conducive to the discharge of N2.

[0012] Furthermore, the outer packing box is fixed to the left side of the pump casing by bolt four; the outer packing box is provided with a heat dissipation device, and the heat dissipation device is provided with an annular groove on the outside of the outer packing box, an annular cover plate is provided on the outside of the annular groove, and multiple retaining rings are provided in the annular groove along the axial direction. The retaining ring divides the chamber formed by the annular groove of the outer packing box and the annular cover plate into multiple cavities, and each retaining ring is provided with at least one through hole to connect the multiple cavities in the annular groove to each other; a coolant inlet and a coolant outlet are respectively provided at the left and right ends of the annular cover plate for the inflow and discharge of coolant.

[0013] Furthermore, the interior of the outer packing box is a through hole, and the left half is provided with three steps that gradually decrease from left to right, a large packing is installed in the rightmost step, an inner packing box is provided on the left side of the large packing, a step surface is provided on the outer side of the middle section of the inner packing box, and the inner packing box gland is sleeved on the outer side of the middle section of the inner packing box; an internal threaded section for matching the inner packing box gland is provided on the left side of the outer packing box, the inner packing box gland is threadedly connected to the outer packing box, and the right side surface of the inner packing box gland is connected to the inner packing box The stepped surface on the outer side of the middle section is pressed tightly; the inner middle section of the inner packing box is provided with a convex ring extending inward, on which a small packing is provided, and a gland bushing is provided on the left side of the small packing; an external threaded section is provided on the left side of the inner packing box, and a matching outer packing box gland is provided, the inner packing box and the outer packing box gland form a threaded connection, and the outer packing box gland presses the gland bushing onto the small packing; the outer wall of the plunger is clearance-matched with the gland bushing, small packing, large packing and inner wall of the outer packing box from left to right.

[0014] Furthermore, a groove is provided on the left side of the discharge valve core, in which a discharge valve magnet is installed, and fixed to the discharge valve core by bolt 1; a groove is provided on the right end of the plunger, in which a plunger head magnet is installed, and fixed to the plunger by bolt 2. Such a design, because the magnetism of the discharge valve magnet and the plunger head magnet relative to each other is different, thus generating mutual attraction, can promote the rapid closing of the discharge valve core, reduce the high-pressure N2 flowing into the plunger cavity through the discharge port during the expansion stage, and avoid the reduction of the mass of the discharged N2.

[0015] Furthermore, a first sealing ring is provided on the circumferential mating surface between the discharge valve spring seat and the pump housing; a second sealing ring is provided between the mating surfaces of the discharge valve spring seat, the valve seat and the pump housing; a third sealing ring is provided between the mating surfaces of the valve seat, the suction valve spring seat and the pump housing; a fourth sealing ring is provided between the suction valve spring seat and the pump housing; a fifth sealing ring is provided on the mating surface between the outer packing box and the outer housing; and a sixth sealing ring is provided on the mating surface between the outer packing box and the plunger.

[0016] The present invention is beneficial in that: Compressing N2 is a process of increasing temperature and pressure. As the pump continues to work, the number of times N2 is compressed increases. In addition, due to the presence of high-temperature and high-pressure N2 in the clearance, the overall temperature of the pump and the temperature of N2 in the plunger cavity both increase. High temperature corresponds to low density of N2, and the mass of inhaled N2 is small. Therefore, it is proposed to design a heat dissipation device. The outer packing box, retaining ring, and annular cover plate constitute the heat dissipation device. The retaining ring is provided with eight oblique through holes along the circumferential direction, and the through holes of the three retaining rings are all oblique through holes, so that the coolant, such as water flow, can produce violent disturbances, promote the full mixing of the coolant inside, and take away the heat of the pump as a whole, thereby reducing the temperature in the plunger cavity. It is beneficial to inhale more N2 during the expansion stage of the plunger cavity, that is, it is beneficial to improve the volumetric efficiency of the pump; at the same time, the pump is kept working within a suitable temperature range to prevent the pump from overheating and causing performance degradation or damage.

[0017] 2. At the initial stage of the expansion of the plunger cavity, due to the small pressure difference between the plunger cavity and the discharge port, the discharge valve core cannot be closed in time, and the high-pressure N2 at the discharge port will flow back to the plunger cavity through the discharge valve group, resulting in reduced pump efficiency. Therefore, magnets are provided on the right end face of the plunger and the left end face of the discharge valve core, and the two magnets are N and S poles respectively. The magnetic opposites attract each other to prompt the discharge valve core to close as soon as possible, effectively preventing the high-pressure N2 from flowing from the discharge port to the plunger cavity, thereby improving the pump efficiency.

[0018] 3. A suction valve ball is provided between the suction valve core and the suction valve spring seat, and the suction valve core, the suction valve spring seat and the suction valve ball form a rolling pair. The rolling pair is conducive to the coaxiality of the suction valve core and the suction valve spring seat, so that the suction valve core is forced along the axis direction, which is conducive to the sealing of the suction valve core and the valve seat, and avoids the suction valve core from being stuck during the reciprocating motion; at the same time, the friction of the rolling pair is relatively small, and the resistance that the suction valve core needs to overcome to open is small, which makes the pressure difference between the plunger cavity and the suction port small, which is conducive to the suction of more N2.

[0019] 4. A discharge valve ball is provided between the discharge valve core and the valve seat, and the discharge valve core, the discharge valve ball and the valve seat form a rolling pair. The rolling pair is conducive to the coaxiality of the discharge valve core and the valve seat, so that the discharge valve core is forced along the axis direction, which is conducive to the sealing of the discharge valve core and the valve seat, and prevents the discharge valve core from being stuck during the reciprocating motion.

[0020] 5. A through hole is provided in the middle of the suction valve core, and the plunger can pass through the through hole of the suction valve core. The left end face of the plunger coincides with the right end face of the discharge valve seat, which effectively reduces the clearance volume, is beneficial to improve the efficiency of the pump, and realizes efficient N2 pressurization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional partial cross-sectional view of the present invention.

[0022] Figure 2 It is a cross-sectional view of the present invention.

[0023] Figure 3 for Figure 2 Enlarged image on the left.

[0024] Figure 4 for Figure 2 Enlarged image on the right.

[0025] Figure 5 It is a flow diagram of N2 in the expansion stage of the present invention.

[0026] Figure 6 It is a flow diagram of N2 in the compression stage of the present invention.

[0027] Figure 7 This is a schematic diagram of the present invention when the plunger moves to the left dead point and is about to start compression.

[0028] Figure 8 This is a schematic diagram of the present invention when the plunger moves to the right dead point and is about to start expanding.

[0029] Fig. 9 It is a structural schematic diagram of the valve core of the suction valve of the present invention.

[0030] Fig.10 It is a schematic structural diagram of the retaining ring of the present invention.

[0031] Fig.11 It is a schematic structural diagram of the valve core of the discharge valve of the present invention.

[0032] Fig.12 It is a schematic structural diagram of the pump housing of the present invention.

[0033] Fig.13 It is a structural sectional view of the pump housing of the present invention.

[0034] Fig.14 It is a schematic diagram of the flow of the cooling liquid of the present invention.

[0035] Reference numerals: 1. Pump housing; 2. Suction valve spring seat; 3. Suction valve spring; 4. Suction valve ball; 5. Suction valve core; 6. Valve seat; 7. Discharge valve magnet; 8. Bolt 1; 9. Discharge valve core; 10. Discharge valve spring; 11. Discharge valve ball; 12. Discharge valve spring seat; 13. First sealing ring; 14. Second sealing ring; 15. Third sealing ring; 16. Fourth sealing ring; 17. Fifth sealing ring; 18. Plunger head magnet; 19. Bolt 2; 20 , plunger; 21, outer packing box; 22, large packing; 23, inner packing box; 24, inner packing box gland; 25, gland bushing; 26, outer packing box gland; 27, small packing; 28, annular cover plate; 281, coolant inlet; 282, coolant outlet; 29, retaining ring; 30, bolt three; 31, sixth sealing ring; 32, bolt four; a, suction port; b, plunger cavity; c, discharge port; d, discharge chamber; S1, ring surface 1; S2, ring surface 2. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the embodiments. It should be noted that, in this article, words such as "upper", "lower", "left", "right", etc. are only used to facilitate the description of the drawings, and do not limit the direction in actual use, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises", or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements that are inherent to such process, method, article, or device.

[0037] like Figure 1-14 As shown in the figure, the dotted arrow represents the movement direction of the plunger, the solid arrow represents the flow direction of N2, and the dot-dash arrow represents the flow direction of the coolant. A pressurized plunger pump for an oil and gas wellhead device air seal detection system has at least one plunger, preferably, a three-plunger plunger, including a pump housing 1, such as Fig.12 As shown, three hollow cavities are provided inside the pump housing 1, and a corresponding suction port a is provided below each hollow cavity, and a suction valve group, a discharge valve group, and a valve seat 6 are installed in the hollow cavity; an outer packing box 21 is installed on the left side of the pump housing 1, and a cavity is provided in the outer packing box 21, and a plunger 20 is installed in the outer packing box 21; the inner cavity of the outer packing box 21 and the hollow cavity of the pump housing 1 constitute a plunger cavity b, and the plunger 20 can reciprocate left and right in the plunger cavity b; the suction valve group is opened and the discharge valve group is closed, and the plunger cavity b sucks fluid from the suction port a; the suction valve group is closed and the discharge valve group is opened, and the plunger cavity b discharges fluid to the discharge port c.

[0038] like Figure 1 , 2As shown in , 4, the suction valve group includes a suction valve spring seat 2, a suction valve spring 3, a suction valve core 5, and a suction valve ball 4; the suction valve spring seat 2 is installed in the hollow cavity of the pump housing 1, and an inwardly expanding step is provided at the installation position corresponding to the hollow cavity of the pump housing; the suction valve spring seat 2 is provided with an axial hollow cavity, and both the inner and outer sides of the suction valve spring seat 2 are two-stage structures, and radial and axial positioning are achieved by the step surface between the two-stage structure and the step surface of the hollow cavity of the pump housing 1; the left end of the suction valve spring seat 2 is in contact with the outer disk The right end of the root box 21 cooperates, and the right end of the suction valve spring seat 2 contacts the valve seat 6; the valve seat 6 is an I-shaped rotating body structure, and the left and right rotating body parts are respectively the left plate and the right plate; the valve seat 6 is provided with a hole along the axial direction, and the annulus between the left plate and the right plate is connected to the suction port a, and a plurality of flow channel holes are provided on the left plate of the valve seat 6 (the through holes are all inclined from left to right in the axial direction), preferably eight flow channel holes are provided to connect the suction port a and the hollow cavity of the suction valve spring seat 2; between the valve seat 6 and the suction valve spring seat 2, there is a hole as shown in the figure. Figure 7 The suction valve core 5 is shown, and a suction valve spring 3 is installed between the suction valve core 5 and the suction valve spring seat 2; during installation, the suction valve spring 3 is subjected to pre-tightening pressure, and under the action of the pre-tightening pressure, the right side of the suction valve core 5 is coplanar with the left side of the left plate of the valve seat 6 and pressed tightly; the interior of the suction valve core 5 is provided with a through hole, the inner diameter of the right annular surface of the suction valve core 5 is smaller than the inner enveloping circle diameter of the flow channel hole of the valve seat 6, the outer diameter of the right annular surface of the suction valve core 5 is larger than the outer enveloping circle diameter of the flow channel hole of the valve seat 6, and the right side of the suction valve core 5 can block the flow channel hole of the valve seat 6. The flow channel inclination angle is preferably designed to be 45°, so that a smaller spring force can be used, and a smaller spring force is conducive to reducing the pressure difference between the plunger cavity b and the suction port a during the expansion stage, and increasing the mass flow of the inhaled N2.

[0039] like Figure 4 As shown, the right section of the suction valve core 5 is provided with a cylindrical surface extending outward, and a groove for installing the suction valve ball 4 is provided on the cylindrical surface, and the outer wall of the cylindrical surface is adapted to the inner wall of the large diameter section of the suction valve spring seat 2, and the suction valve ball 4 is installed between the cylindrical surface and the inner wall of the large diameter section of the suction valve spring seat 2, and the suction valve core 5, the suction valve spring seat 2, and the suction valve ball 4 constitute a rolling pair. The rolling pair is conducive to the coaxiality of the suction valve core 5 and the suction valve spring seat 2, avoiding the suction valve core 5 from being stuck during the reciprocating motion; at the same time, the friction of the rolling pair is relatively small, the resistance to be overcome by the suction valve core 5 to open is small, and the pressure difference between the plunger cavity b and the suction port a is small. Compared with the common clearance fit positioning in the prior art, the suction valve core 5 of the present invention adopts the solution of the suction valve ball 4, so it does not require high processing accuracy and is easy to install and replace.

[0040] like Figure 4As shown, the discharge valve group includes a discharge valve core 9, a discharge valve ball 11, a discharge valve spring 10, and a discharge valve spring seat 12; the left side of the discharge valve spring seat 12 is gap-fitted in the hollow cavity of the pump housing 1, and the right side of the discharge valve spring seat is connected to the pump housing 1 by a bolt 30; the discharge valve spring seat 12 is provided with a column with the axis as the center, and the discharge valve spring 10 is installed outside the column; a through hole is provided on the side of the discharge valve spring seat 12, and a connecting hole is provided on the pump housing 1 corresponding to the through hole, and the two holes together form a discharge port c; the left side of the discharge valve spring 10 is installed in the annular groove on the right side of the discharge valve core 9; a conical surface is provided on the left side of the discharge valve core 9, and a conical surface is also provided on the inner wall of the left hole of the valve seat 6 corresponding to the discharge valve core 9, and the conical surface of the discharge valve core 9 contacts with the conical surface of the valve seat 6 to form a sealing surface.

[0041] like Fig.11 As shown, the outer peripheral surface of the discharge valve core 9 is provided with a plurality of support frames (preferably four support frames are used to balance the cost and the requirements of the force-bearing surface), and the support frames are provided with grooves for installing the discharge valve ball 11, and the discharge valve ball 11 is provided between the support frame and the inner wall of the valve seat 6. The discharge valve core 9, the discharge valve ball 11, and the valve seat 6 constitute a rolling pair, which is conducive to the coaxiality of the discharge valve core 9 and the valve seat 6, and promotes the discharge valve core 9 to be stressed along the axial direction, which is conducive to the sealing of the discharge valve core 9 and the valve seat 6, and avoids the discharge valve core 9 from being stuck during the reciprocating motion. At the same time, the friction of the rolling pair is relatively small, the resistance to be overcome by the discharge valve core 9 to open is small, and the pressure difference between the plunger cavity b and the discharge port c is small, which is conducive to the discharge of N2.

[0042] like Figure 3 As shown, the outer packing box 21 is fixed to the left side of the pump housing 1 by bolts 32; the outer packing box 21 is provided with a heat dissipation device, which is provided with an annular groove on the outside of the outer packing box 21, an annular cover plate 28 is provided outside the annular groove, and multiple retaining rings 29 are provided in the annular groove along the axial direction. The retaining rings 29 divide the chamber formed by the annular groove of the outer packing box 21 and the annular cover plate 28 into multiple cavities. Each retaining ring 29 is provided with at least one through hole to allow the multiple cavities in the annular groove to communicate with each other; a coolant inlet 281 and a coolant outlet 282 are provided at the left and right ends of the annular cover plate 28, respectively, for the inflow and discharge of coolant. Fig.14 As shown, the dotted arrows in the figure represent the flow direction of the coolant, and can be set in the reverse direction. The coolant can be water or other heat-conducting fluids.

[0043] like Figure 3As shown, the interior of the outer packing box 21 is a through hole, and three steps that gradually decrease from left to right are provided in the left half, a large packing 22 is installed in the rightmost step, an inner packing box 23 is provided on the left side of the large packing 22, a step surface is provided on the outer side of the middle section of the inner packing box 23, and an inner packing box gland 24 is sleeved on the outer side of the middle section of the inner packing box 23; an internal threaded section for matching the inner packing box gland 24 is provided on the left side of the outer packing box 21, the inner packing box gland 24 is threadedly connected to the outer packing box 21, and the right side surface of the inner packing box gland 24 is connected to the outer side of the middle section of the inner packing box 23 The stepped surface is pressed tightly; a convex ring extending inward is provided in the inner middle section of the inner side of the inner packing box 23, on which a small packing 27 is provided, and a gland bushing 25 is provided on the left side of the small packing 27; an external threaded section is provided on the left side of the inner packing box 23, and a matching outer packing box gland 26 is provided, the inner packing box 23 and the outer packing box gland 26 are threadedly connected, and the outer packing box gland 26 presses the gland bushing 25 onto the small packing 27; the outer wall of the plunger 20 is respectively matched with the inner wall clearance of the gland bushing 25, the small packing 27, the large packing 22, and the outer packing box 21 from left to right.

[0044] A groove is provided on the left side of the discharge valve core 9, in which a discharge valve magnet 7 is installed, which is fixed to the discharge valve core 9 by a bolt 1 8. A groove is provided on the right end of the plunger 20, in which a plunger head magnet 18 is installed, which is fixed to the plunger 20 by a bolt 2 19. Such a design, because the magnetic properties of the discharge valve magnet 7 and the plunger head magnet 18 relative to each other are different, a mutual attraction is generated, which can promote the rapid closing of the discharge valve core 9, reduce the high-pressure N2 flowing into the plunger cavity b through the discharge port c during the expansion stage, and avoid the reduction of the mass of the discharged N2.

[0045] A first sealing ring 13 is provided on the circumferential mating surface between the discharge valve spring seat 12 and the pump housing 1; a second sealing ring 14 is provided between the mating surfaces of the discharge valve spring seat 12, the valve seat 6 and the pump housing 1; a third sealing ring 15 is provided between the mating surfaces of the valve seat 6, the suction valve spring seat 2 and the pump housing 1; a fourth sealing ring 16 is provided between the suction valve spring seat 2 and the pump housing 1; a fifth sealing ring 17 is provided on the mating surface between the outer packing box 21 and the outer housing 1; a sixth sealing ring 31 is provided on the mating surface between the outer packing box 21 and the plunger 20.

[0046] A preferred embodiment is that the pressurized plunger pump used in the air seal detection system of an oil and gas wellhead device is described by taking the middle cylinder as an example, and a suction port a is provided on the lower side of the pump housing 1, and a discharge port c is provided on the side perpendicular to the suction port a, and a through hole is provided on the pump housing 1 to connect the discharge ports of the three cylinders, and the pressurized N2 is discharged through the discharge ports c on the front and rear sides of the pump body.

[0047] like Figure 5As shown in the figure, the dotted arrow represents the movement direction of the plunger, and the solid arrow represents the flow direction of N2. The plunger 20 reciprocates under the drive of the prime mover. The plunger 20 moves from the right dead point to the left, and the plunger chamber b is in the expansion stage. The space of the plunger chamber b increases, and the N2 pressure in the plunger chamber b decreases. The discharge valve core 9 is closed under the combined force of the N2 pressure in the plunger chamber b, the high-pressure N2 pressure at the discharge port c, and the discharge valve spring 10; as the plunger chamber b continues to expand, when the force of N2 at the suction port a acting on the suction valve core 5 is greater than the combined force of the suction valve spring 3 and the N2 pressure in the plunger chamber b acting on the suction valve core 5, the suction valve core 5 opens, and N2 enters the plunger chamber b through the suction port a and the through hole of the left plate of the valve seat 6.

[0048] like Figure 6 As shown in the figure, the dotted arrow represents the movement direction of the plunger, and the solid arrow represents the flow direction of N2. When the plunger 20 moves from the left dead point to the right, the plunger chamber b is in the compression stage, the volume of the plunger chamber b becomes smaller, and the N2 pressure in the plunger chamber b increases; when the combined force of the N2 pressure in the plunger chamber b and the suction valve spring 3 acting on the suction valve spool 5 is greater than the force of the N2 pressure at the suction port a acting on the suction valve spool 5, the suction valve spool 5 is closed; as the plunger chamber b continues to compress, the pressure in the plunger chamber b further increases, and the force of N2 in the plunger chamber b acting on the discharge valve spool 9 is greater than the combined force of the N2 pressure at the discharge port and the discharge valve spring 10 acting on the discharge valve spool 9, the discharge valve spool 9 is opened, and the high-pressure N2 flows into the chamber d of the discharge valve spring seat 12 through the hole in the middle of the suction valve spool 5 and the gap between the discharge valve spool 9 and the valve seat 6, and finally N2 is output through the discharge port c. The expansion and compression phases of the plunger chamber b constitute a complete stroke. The expansion phase sucks in low-pressure N2, and the compression phase discharges high-pressure N2. The left and right dead points of the stroke are as follows: Figure 7-Figure 8 As shown, the annular surface 2S2 has a limiting effect on the annular surface 1S1.

[0049] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention are still improvements of the technical solution of the present invention.

Claims

1. A pressurized plunger pump for an oil and gas wellhead device air seal detection system, characterized in that: It includes a pump housing, a hollow cavity is provided inside the pump housing, and a corresponding suction port is provided below each hollow cavity, and a suction valve group, a discharge valve group and a valve seat are installed in the hollow cavity; an outer packing box is installed on the left side of the pump housing, a cavity is provided in the outer packing box, and a plunger is installed in the outer packing box; the cavity in the outer packing box and the hollow cavity of the pump housing constitute a plunger cavity, and the plunger reciprocates in the plunger cavity.

2. A pressurized plunger pump for an oil and gas wellhead device air seal detection system according to claim 1, characterized in that: The suction valve group includes a suction valve spring seat, a suction valve spring, a suction valve core, and a suction valve ball; the suction valve spring seat is installed in the hollow cavity of the pump housing, and an inwardly expanding step is provided at the installation position corresponding to the hollow cavity of the pump housing, and the suction valve spring seat is provided with an axial hollow cavity, and the inner and outer sides of the suction valve spring seat are both two-stage structures, and radial and axial positioning are achieved by contacting the step surface between the two-stage structure with the step surface of the hollow cavity of the pump housing; the left end of the suction valve spring seat cooperates with the right end of the outer packing box, and the right end of the suction valve spring seat contacts the valve seat, and the valve seat is an I-shaped rotating body structure, and the left and right rotating body parts are respectively a left plate and a right plate; the valve seat is axially parallel to the axis A hole is provided in the left side plate and the right side plate, and the annulus between the left plate and the right side plate is connected to the suction port. A plurality of flow channel holes are provided on the left side plate of the valve seat, which are used to connect the suction port and the hollow cavity of the suction valve spring seat. A suction valve core is provided between the valve seat and the suction valve spring seat, and a suction valve spring is installed between the suction valve core and the suction valve spring seat. When installing, the suction valve spring is subjected to pre-tightening pressure, and under the action of the pre-tightening pressure, the right side surface of the suction valve core is coplanar with the left side surface of the left side plate of the valve seat and is pressed tightly. The inner diameter of the right side annular surface of the suction valve core is smaller than the inner envelope circle diameter of the flow channel hole of the valve seat, and the outer diameter of the right side annular surface of the suction valve core is larger than the outer envelope circle diameter of the center flow channel hole of the valve seat, so the right side surface of the suction valve core can block the flow channel hole of the valve seat.

3. The pressurized plunger pump for the gas seal detection system of oil and gas wellhead device according to claim 2, characterized in that: The right section of the suction valve core is provided with a cylindrical surface extending outward, a groove for installing the suction valve ball is provided on the cylindrical surface, and the outer wall of the cylindrical surface is adapted to the inner wall of the large diameter section of the suction valve spring seat, the suction valve ball is installed between the cylindrical surface and the inner wall of the large diameter section of the suction valve spring seat, and the suction valve core, the suction valve spring seat and the suction valve ball constitute a rolling pair.

4. The pressurized plunger pump for the gas seal detection system of oil and gas wellhead device according to claim 2, characterized in that: The discharge valve group includes a discharge valve core, a discharge valve ball, a discharge valve spring, and a discharge valve spring seat. The left side of the discharge valve spring seat is gap-fitted in the hollow cavity of the pump housing, and the right side of the discharge valve spring seat is connected to the pump housing by bolt three; the discharge valve spring seat is provided with a column with the axis as the center, and the discharge valve spring is installed outside the column; a through hole is provided on the side of the discharge valve spring seat, and a connecting hole is provided on the pump housing corresponding to the through hole, and the two holes together form a discharge port; the left side of the discharge valve spring is installed in the annular groove on the right side of the discharge valve core; a conical surface is provided on the left side of the discharge valve core, and a conical surface is also provided on the inner wall of the left hole of the valve seat corresponding to the discharge valve core, and the conical surface of the discharge valve core contacts with the conical surface of the valve seat to form a sealing surface.

5. The pressurized plunger pump for the gas seal detection system of oil and gas wellhead device according to claim 4, characterized in that: The outer peripheral surface of the discharge valve core is provided with a plurality of support frames, the support frames are provided with grooves for installing the discharge valve balls, the discharge valve balls are arranged between the support frames and the inner wall of the valve seat, and the discharge valve core, the discharge valve balls and the valve seat form a rolling pair.

6. The pressurized plunger pump for the gas seal detection system of oil and gas wellhead device according to claim 1, characterized in that: The outer packing box is fixed to the left side of the pump casing by bolt 4; the outer packing box is provided with a heat dissipation device, which is provided with an annular groove on the outside of the outer packing box, an annular cover plate on the outside of the annular groove, and multiple retaining rings along the axial direction. The retaining ring divides the chamber formed by the annular groove of the outer packing box and the annular cover plate into multiple cavities, and each retaining ring is provided with at least one through hole to connect the multiple cavities in the annular groove to each other; a coolant inlet and a coolant outlet are respectively provided at the left and right ends of the annular cover plate for the inflow and discharge of coolant.

7. The pressurized plunger pump for the gas seal detection system of oil and gas wellhead device according to claim 1, characterized in that: The interior of the outer packing box is a through hole, and three steps that gradually decrease from left to right are provided on the left half. A large packing is installed in the rightmost step. An inner packing box is provided on the left side of the large packing. A step surface is provided on the outer side of the middle section of the inner packing box. The inner packing box gland is sleeved on the outer side of the middle section of the inner packing box. An internal threaded section for matching the inner packing box gland is provided on the left side of the outer packing box. The inner packing box gland is threadedly connected to the outer packing box. The right side surface of the inner packing box gland is connected to the middle section of the inner packing box. The stepped surface on the outside is pressed tightly; a convex ring extending inward is provided on the inner middle section of the inner side of the inner packing box, a small packing is provided on the convex ring, and a gland bushing is provided on the left side of the small packing; an external threaded section is provided on the left side of the inner packing box, and a matching outer packing box gland is provided, the inner packing box and the outer packing box gland form a threaded connection, and the outer packing box gland presses the gland bushing onto the small packing; the outer wall of the plunger is clearance-matched with the gland bushing, small packing, large packing and inner wall of the outer packing box from left to right.

8. The pressurized plunger pump for the gas seal detection system of oil and gas wellhead device according to claim 4, characterized in that: A groove is provided on the left side of the discharge valve core, a discharge valve magnet is installed in the groove and fixed to the discharge valve core by bolt one, and a groove is provided on the right end of the plunger, a plunger head magnet is installed in the groove and fixed to the plunger by bolt two.

9. A pressurized plunger pump for an oil and gas wellhead device air seal detection system according to any one of claims 1 to 8, characterized in that: A first sealing ring is provided between the discharge valve spring seat and the circumferential mating surface of the pump housing; a second sealing ring is provided between the mating surfaces of the discharge valve spring seat, the valve seat and the pump housing; a third sealing ring is provided between the mating surfaces of the valve seat, the suction valve spring seat and the pump housing; a fourth sealing ring is provided between the suction valve spring seat and the pump housing; a fifth sealing ring is provided on the mating surface of the outer packing box and the outer housing; a sixth sealing ring is provided on the mating surface of the outer packing box and the plunger.

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