CN117231492A

CN117231492A - Low-pressure chromatographic plunger pump

Info

Publication number: CN117231492A
Application number: CN202210628884.XA
Authority: CN
Inventors: 马俊
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-06-07
Filing date: 2022-06-07
Publication date: 2023-12-15

Abstract

Embodiments of the present specification provide a low pressure chromatography plunger pump, comprising: the plunger is configured to be mounted in the plunger chamber to displace a fluid; the sealing element is used for sealing the plunger component and the plunger chamber when the plunger component is installed in the plunger chamber to reciprocate; wherein the seal is mounted on the plunger member for reciprocal movement with the plunger. The seal mount has a plurality of circumferentially arranged adjustment members that can be moved in a radial direction of the axis to increase or decrease the size of the seal. On the other hand, the slope and the radian of the sealing element can effectively absorb deformation and enhance the pressing force. By the scheme, the manufacturing difficulty and the production cost of the low-pressure plunger pump are reduced, and the maintenance convenience is improved.

Description

Low-pressure chromatographic plunger pump

Technical Field

The specification relates to the technical field of chromatography, in particular to a plunger pump used in bioactive macromolecule chromatography.

Background

The present application relates to a plunger element, a pump head, a plunger pump for pumping fluid, and a method of manufacturing a plunger member of a plunger pump for pumping fluid.

In many biochemical processes, such as sample separation processes based on the liquid chromatography principle, the fluid sample to be separated is injected in a mobile phase, such as a solvent composition, which can be pumped through a pipeline to a chromatography column, which contains a colloid (stationary phase) capable of separating the different components of the fluid sample.

To pump the mobile phase to the sample separation device, a plunger may be reciprocated within the pump chamber, displacing the mobile phase. Also for injecting the fluid sample into the mobile phase, another metering plunger pump may be added at the sample injector end of the sample separation device to inject the fluid sample into the mobile phase.

Conventionally, such chromatographic separation devices were originally used for separating small molecular products, and the chromatographic packing used was also a gel of a hard inorganic framework, and because of the small pore size, a relatively high pressure was required for the separation. Therefore, the high-pressure working condition puts a very severe requirement on the sealing of the pump, for example, a plunger made of precious stone is needed for the high-pressure pump to achieve the required high-pressure sealing; however, such designs, on the one hand, make the designs of seals, bearings, etc. relatively complex, and further have to sacrifice other demands on the process, such as minimum dead volume; on the other hand, the required processing procedures are complex, and thus, the installation and maintenance are difficult.

In the current stage and the development trend of the biological technology in the future, products of macromolecular cells are already entered, and the used glue is mainly organic soft glue. Substances including biomolecules and gums are not pressure resistant, e.g. biomolecules are denatured under high pressure and gums are broken under high pressure, so the process of production must be at low pressure and the requirement for pumps is not critical. So that the pump design can be more focused on the needs of the process itself, such as: flow stability, flow accuracy, hygiene, zero dead volume, and simplicity of manufacture and maintenance.

The application discloses a pump which is simple to manufacture, convenient to maintain, stable in flow and free from dead volume in a biomacromolecule chromatography process and can achieve higher sanitation and pumping precision.

Disclosure of Invention

In view of the above, the application provides a plunger pump for bioactive macromolecule chromatography, which solves the problems in the prior art, improves the pumping precision, provides convenience for installation and maintenance, and reduces the manufacturing cost.

According to an exemplary embodiment of the present application, a plunger pump for pumping a fluid (such as a liquid and/or a gas, optionally including solid particles) is provided in a sample separation device, comprising: a plunger cavity having an inner wall surface formed about an axis of the cavity; and a piston assembly for sliding along an axis of the cavity, the piston assembly comprising a slidable flexible seal in sealing contact with the inner wall surface, and a seal mount having a plurality of circumferentially arranged adjustment structures movable in a radial direction of the axis to increase or decrease a size of the seal. The plunger assembly is mounted in a plunger cavity for displacing fluid, and the gap between the plunger assembly and the plunger chamber is sealed with a seal when the plunger member is mounted in the plunger chamber for reciprocation therewith.

According to an exemplary embodiment, the pump head comprises a plunger chamber defining a working volume, and the plunger component having the above-mentioned features is mounted or mountable in the plunger chamber of the working volume such that the seal seals against the plunger member and the plunger chamber.

According to an exemplary embodiment, the plunger and the seal are rigidly connected to each other so as to be able to move together during reciprocation of the plunger to displace fluid within the plunger cavity. By forming the plunger and the sealing member as a common part to reciprocate together, i.e. by using the sealing member as a dynamic bearing guide at the same time, the guiding of the plunger in the plunger cavity is significantly improved. At the same time, the seal securely attached to the plunger also facilitates proper alignment and positioning of the plunger within the plunger cavity, further improving the accuracy of the reciprocating motion of the plunger seal assembly/plunger components within the working chamber. Thus, inaccuracy in flow rate or volume of the displacement fluid can be effectively suppressed. Furthermore, the rigid connection between the plunger and the seal significantly reduces the dead volume of fluid in the plunger cavity, as this allows the seal to be located in the front region of the plunger cavity, i.e. closer to the front flange face of the plunger cavity. Because the resilience of the seal provides protection against accidental hard impacts of the plunger member against the front wall of the working chamber. This further reduces the dead volume of the pump. The problems of mobile phase and/or sample carryover between different analytical procedures can be significantly reduced.

In one embodiment, the seal comprises or consists of an elastic material, in particular a plastic material. By configuring the seal with an elastomeric material, the seal may fill a small gap between the plunger seal assembly/plunger component and the plunger chamber wall, thereby improving sealing performance and reducing the dead volume of fluid in the plunger chamber. In embodiments, the seal is made of a chemically inert material, such as Polytetrafluoroethylene (PTFE) or Polyethylene (PE) type plastic, particularly a solvent-based inert material. This choice of material ensures that the seal is not deteriorated or damaged by displacement by chemically aggressive fluids under the sealing contribution. For example, for liquid chromatography applications, corrosive solvent materials such as organic solvent-like methanol or acetonitrile may be used and may be tolerated by chemically inert seals without degrading the seal. In embodiments, the seal may also be made of a bio-inert or bio-inert material to enable the plunger assembly to withstand without deterioration, the presence of a biological fluid sample that may be replaced by a plunger with an integrated seal.

In an embodiment, the plunger member is composed of a rigid material, in particular stainless steel metal. The material has wide source and is easy to process and manufacture.

In a preferred embodiment, the seal is mechanically fixed to the plunger. This avoids the introduction of adhesive material or the like in the plunger chamber, thereby eliminating any risk of corrosive solvolytic adhesives and contaminating the pumped mobile phase or fluid sample. The preferred sealing shape of the piston connecting portion matches and is opposite to the shape of the front piston, the two components can be connected to each other without risk of accidental separation under mechanical load. In particular, the plunger assembly provides a fixed sealing compression force by a fixed spring force, thereby ensuring or enhancing a secure connection of the seal and the plunger.

In a preferred embodiment, the circumferential sealing inclined surface along the entire circumference of the seal outboard inclined ledge adjacent to the compressive force on the plunger chamber wall may act as the actual sealing element, closing any gap between the plunger chamber and plunger. In embodiments, the seal profile has a convex inclined surface, a concave interior and an arcuate concave shape, such shape being advantageous for sealing the plunger and pump chamber on the one hand, and the arcuate concave surface being advantageous for sealing deformation absorption and for a tighter fit with the interior plunger component on the other hand.

In an embodiment, the piston assembly further comprises a regulator pull rod assembly of the plunger head, movable along the axis to act on the regulator to cause said increase or decrease in the size of the plunger head to compress the seal.

Preferably, the conical adjuster rod assembly is a moving rod and the adjuster is a radial expansion member, and preferably the moving rod further comprises a spring which maintains the adjuster in use to a fixed radial expansion force to compress the seal with a fixed radial force.

Preferably, the movable rod spring has a detent member, which is a spring in a constant compression stroke, while the detent member is slidable relative to the plunger, thereby maintaining a fixed spring force.

Preferably, the piston chamber is made of a ceramic material, such as chromium oxide, to provide a smooth inner surface.

In an embodiment, the pump head comprises a static plunger guide unit arranged in the plunger chamber. The static plunger guide unit may be placed at a greater distance from the flange face of the plunger chamber than the plunger seal as a dynamic plunger guide unit. In an embodiment, the static plunger guide unit is a rigid plastic seal that forms part of the plunger washing chamber and guides the plunger assembly at the plunger base, i.e. in the rear position. Particularly, a cleaning cavity can be arranged between the two guide units, so that on one hand, friction heat generation of the plunger can be effectively reduced, the service life of the seal is prolonged, and on the other hand, leakage of materials or formation of solid crystals caused by evaporation can be effectively avoided.

In an embodiment, the pump may comprise a pump base to be assembled with the pump head, and a plunger driver configured to drive the plunger to reciprocate within the plunger cavity in an assembled state. After the plunger members are worn, the pump head may be removed from the pump base and reassembled with the replaced plunger members of the pump head. In embodiments, the pump may comprise a backdrive mechanism, in particular a backdrive spring, arranged to provide a backdrive force to the plunger upon plunger drive urging the plunger forward to its upper end position in the plunger chamber. In another embodiment, the pump may be driven directly using a stepper.

In an embodiment, the pump includes a pump head flow module that includes an inlet and an outlet with a check valve. In particular, the flow channel module may also be combined with a rotary valve, with the valve core rotating to select different flow channels.

Compared with the prior art, the beneficial effects that above-mentioned at least one technical scheme that this description embodiment adopted can reach include at least:

the seal mount has a spring force which can be fixed by a spring and which ultimately acts on a plurality of circumferentially arranged adjustment members which move in the radial direction of the axis in order to increase or decrease the size of the seal, thereby autonomously adjusting the sealing force. On the other hand, the slope and the radian of the sealing element can effectively absorb deformation and enhance the pressing force. By the scheme of the application, the manufacturing difficulty and the production cost of the low-pressure plunger pump are reduced, the maintenance convenience is improved, and the process applicability is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 shows a cross-sectional view of a pump according to an exemplary embodiment of the application

Fig. 2 shows an exploded view of a pump plunger according to an exemplary embodiment of the application.

Detailed Description

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, apparatus may be implemented and/or methods practiced using any number and aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.

In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.

At present, in the production process of a biomacromolecule chromatographic plunger pump, the following problems mainly exist:

1. conventionally, such chromatographic separation devices were originally used for separating small molecular products, and the chromatographic packing used was also a gel of a hard inorganic framework, and because of the small pore size, a relatively high pressure was required for the separation. Therefore, the high-pressure working condition puts a very severe requirement on the sealing of the pump, for example, a plunger made of precious stone is needed for the high-pressure pump to achieve the required high-pressure sealing; however, such designs, on the one hand, make the designs of seals, bearings, etc. relatively complex, and further have to sacrifice other demands on the process, such as minimum dead volume; on the other hand, the required processing procedures are complex, and thus, the installation and maintenance are difficult.

2. In the current stage and the development trend of the biological technology in the future, products of macromolecular cells are already entered, and the used glue is mainly organic soft glue. Substances including biomolecules and gums are not pressure resistant, e.g. biomolecules are denatured under high pressure and gums are broken under high pressure, so the process of production must be at low pressure and the requirement for pumps is not critical. So that the pump design can be more focused on the needs of the process itself, such as: flow stability, flow accuracy, hygiene, zero dead volume, and simplicity of manufacture and maintenance.

The inventor provides a plunger pump which is simple to manufacture, convenient to maintain, stable in flow and free from dead volume in a biomacromolecule chromatography process and can achieve higher sanitation and pumping precision through extensive and deep experiments.

The application solves the technical problems of reducing the production and manufacturing complexity and the maintenance cost of the plunger pump used in the chromatographic separation of the bioactive macromolecules.

More specifically, the solution adopted by the application comprises the following steps: the seal mount has a spring force which can be fixed by means of a spring and which ultimately acts on a plurality of circumferentially arranged adjustment elements which are displaced in the radial direction of the axis in order to increase or decrease the size of the seal, enabling an autonomous adjustment of the seal pressing force. On the other hand, the slope and the radian of the sealing element can effectively absorb deformation and enhance the pressing force. This reduces the difficulty in manufacturing and the cost of production of the low pressure plunger pump, and improves the maintenance convenience.

The following describes the technical scheme provided by each embodiment of the present application with reference to the accompanying drawings.

The pump includes a front cover 101 with fluid inlet and outlet channels, which can be made of stainless steel or plastic, and the advantage of using plastic is that when the front cover is connected to the pump head, a sealing ring is not needed, and the front cover can be pressed on the pump head 203 by the plastic of the plastic itself. The front cover has an inlet flow path 102 and an outlet flow path 103, and is respectively connected to check valves (not shown). The inner diameter of the flow path can be easily changed according to physical properties such as viscosity of the actual material. In particular, the front cover may be combined with a selector valve through which the flow path is selected.

Mounted along the axis of the front cover is a pump head 203 which is precisely positioned by a positioning groove on a pump seat 301, the pump head having an inlet 212 for the cleaning chamber, an outlet 207, the inlet and outlet being provided with a check valve.

At the front of the pump head, there is a cavity 202 that is a piston cavity, which may be made of a ceramic material, such as chromium oxide, which is mainly due to the smooth surface that is intended to be formed from the ceramic material, and which is easier to machine to the required dimensional accuracy. The cavity is pressed on the pump head through the front cover, and the cavity is sealed with the pump head through an O-shaped ring 205.

The portion of the plunger 206 inside the piston chamber has a front deformable portion 204 and the cover portion acts as a seal compression force adjuster having a plurality of radially deformable strip-shaped tabs 261. The plunger 206 encloses a coaxial pull rod 209 having a tapered portion 291 at the forward end thereof, and as the taper moves rearward relative to the piston 206, the tapered expansion joint props up the deformed strip 261, causing the end diameter of 261 to become larger, thereby exerting radial pressure on the encased seal 208.

The pull rod 209 is compressed inside the plunger 206 by a spring 304, a spring call positioning nut 305 is positioned at the end of the pull rod, the end of the pull rod is provided with an external thread 292 for positioning the positioning nut, and an installation auxiliary hole 306 is arranged at the end of the pull rod for fixing the pull rod when the positioning nut is locked. The outer circumferential surface of the retaining nut matches the inner diameter of the plunger 206 but remains slidable relative to each other. The end of the positioning nut is provided with a plane 351 for acting as an acting end of a tool such as a wrench during installation.

The spring has a sufficiently long compression stroke that the compression force of the spring provides a fixed force to the pull rod relative to the plunger 206, which force provides a fixed radially outward force to the adjuster 261, thereby compressing the seal against the inner wall of the piston chamber with a fixed pressure. According to hooke's law, the spring force is linearly related to the amount of deformation, and since the expansion of the body 291 at the end of the rod provides only a small displacement, the deformation of the spring is very small, thereby maintaining a substantially constant pull rod force and thus a substantially constant radial sealing force.

Matching the profile of the plunger front is a seal 208, the inner surface of which has an arcuate concave collar 282 which, when matching the plunger front, has a partial gap 210, the outer surface of which has a convex surface 281 which is sloped to the sides from the maximum outer diameter. The advantage of this deconfiguration is that when the seal is deformed by pressure, the deformation occurs in both arcuate and oblique directions and there is room 210 to accommodate some amount of deformation.

Further, when the plunger moves forward in the pump cover direction to compress the fluid, the reaction force of the fluid acts on the sealing end surface, and the sealing end surface is tightly supported on the end surface of the pull rod conical surface 291 through deformation, so that the sealing end surface is effectively supported to compress the fluid. Further, when a greater fluid compression force occurs, the sealing end face will push the end face of the pull rod cone 291 to move in the opposite direction, thereby causing the outward expansion of the adjuster 261, increasing the compression force of the seal against the pump chamber, thereby providing better sealing under the high pressure of the compressed fluid. Further, when the plunger pulls the pumping fluid back, the other inclined surface of the sealing surface 281 is reacted with the adjusting member 261 by the reaction force of the pump cavity, and then reacted with the pull rod conical portion 291, so that the pull rod is slightly displaced toward the pump cover, and the pressure of the adjusting member on the sealing member is reduced, that is, the compression force between the sealing member and the pump cavity is reduced, the sealing compression force in the pumping return stroke of the plunger is reduced, the leakage of feed liquid is not caused, and the reduced compression force can slow down the abrasion of the sealing because the pumping return stroke belongs to the negative pressure stage. On the other hand, displacement of the tie rod causes the spring 304 to return to the set amount of elastic deformation, and thus to return to the set seal compression force.

The rear end of the plunger 206 is provided with a static bearing ring 303 which is pressed against the pump seat 301 and the plunger 206 by a more resilient sealing ring 302, which forms a seal against the plunger, and which is of a rigid plastic such as PTFE or the like, on the one hand, and on the other hand, facilitates the support of the plunger and the formation of a seal. The bearing ring is pressed tightly against the pump body 301 by the pump head 203.

Further, a cleaning chamber 211 is formed between the static bearing ring and the dynamic seal of the front section of the plunger, and has an inlet 212, an outlet 207, and check valves respectively. The cleaning cavity can lubricate the sealing element and the inner surface of the cavity on one hand and wash away abrasion particles, and on the other hand, the friction heat generation of the sealing element can be effectively reduced, so that the service life of the sealing element is prolonged.

When the sealing element is replaced, only the pump head 203 and the associated pump cover 101 are required to be detached, the pump head is removed from the plunger head, the tool insertion hole 306 is used for fixing the pull rod 209, the tool with the plastic surface is used for pressing the plunger 206, the pull rod 209 in the plunger relatively moves forwards to eject the old sealing element, and meanwhile, a new sealing element is replaced, the plunger 206 is slowly loosened, and the sealing element is completely ejected onto the plunger. Finally, the pump head is positioned to the pump body through the positioning groove on the pump body 301, and the plunger is inserted into the pump cavity, so that the assembly is completed.

As the main part 206 and the pull rod 209 of the plunger, only a common stainless steel material is needed, and the outer surface of the plunger 206 only needs to achieve a certain surface smoothness within the forward and backward movement range of the contact between the plunger 206 and the static bearing 303, and the rest surfaces have no roughness requirement.

In an embodiment, the moving seal 208 moves with the plunger, greatly reducing the dead volume of the pump chamber 201. Further, the moving seal 208 has a collapsible space 210 so the plunger can be fully compressed onto the pump cap 101, thus achieving almost zero dead volume.

In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment focuses on differences from other embodiments. In particular, for the method embodiments described later, since they correspond to the system, the description is relatively simple, and reference should be made to the description of some of the system embodiments.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims

1. A low pressure plunger pump design is provided for pumping fluid in a sample separation device, wherein the pump head comprises: a plunger (206) configured to be mounted in the plunger chamber (201) to displace a fluid; a seal (208) for sealing the plunger member (204) and the plunger chamber (201) when the plunger member (204) is mounted for reciprocal movement in the plunger chamber (201); wherein a seal (208) is mounted on the plunger member (204) for reciprocation with the plunger (206) to achieve near zero dead volume process requirements and pumping accuracy.

Wherein the seal mount, i.e. the plunger assembly (204), has a fixed spring force which can be formed by a spring (304) which ultimately acts on a plurality of circumferentially arranged adjustment members (261) which move in the radial direction of the axis to increase or decrease the size of the seal (208), thereby having the function of autonomously adjusting the sealing and plunger chamber inner wall pressing force;

wherein, sealing member (208) has surface slope and interior surface cambered surface, and these two are favorable to the sealed of plunger and plunger room on the one hand, and on the other hand is favorable to reducing the wearing and tearing of sealed, improves sealed life.

2. Pump according to claim 1, characterized in that the pull rod (209) has a conical head (209) which in use is axially movable to adjust the size of the seal adjuster (261) to cause the increase or decrease in the size of the seal.

3. Pump according to claim 2, wherein the conical portion (291) provides a substantially fixed axial tension by means of the spring (304) so as to exert a substantially fixed radial force on the radial adjustment member (261); the spring (304) has a sufficient compression stroke, and small stroke variations have very little effect on the spring force according to Hooke's law, so that the spring can almost provide a substantially constant spring force which constantly tightens the pull rod (209) and thus exerts an almost constant radial force on the adjustment member (261).

4. The pump of any of the preceding claims, wherein the seal (208) has an inner arcuate surface (282) defining a partial cavity (210) therebetween and the plunger adjustment member (204), the cavity being capable of accommodating a degree of deformation of the seal.

5. The plunger assembly of claim 4, wherein the seal (208) has an inner arcuate surface (282) by which and the peripherally convex inclined surface (281) facilitates a degree of deformation of the seal in the axial direction upon plunger compression, said deformation further creating radial pressure against the plunger cavity inner surface (201).

6. The plunger assembly according to any one of the preceding claims, wherein the plunger rod conical head (209) is arranged such that when the compressed fluid moves axially, the fluid pressure acts against the plunger seal, and the seal deformation presses against the adjustment member (209) moving in opposite directions, thereby acting against the pressure adjustment member (261) creating an additional radial pressing force against the seal.

7. The plunger assembly of claim 6, wherein the plunger is in a retracted imbibition phase, the external ramp structure of the sealing surface (281) causes a radial compression force to react against the pressure adjustment member (261) and thus against displacement of the pressure adjustment lever (209) in the direction of the pump head, and the spring (304) is compressed back to an equilibrium state, thereby maintaining a reasonable radial compression force between the sealing surface and the pump chamber.

8. A pump according to any preceding claim, the pump body (301) having a ring of mounting grooves to facilitate accurate positioning of the pump head (203).

9. The pump of any of the preceding claims, the pump head (203) having a flushing liquid inlet and outlet, the flushing inlet (212) having a check valve, the flushing outlet (207) having a check valve.

10. The pump of any of the preceding claims, the plunger having a seal packing force retainer (305) that threadably positions the spring (304) in a fixed stroke, creating a fixed pull force on the packing pull rod (209) to achieve a substantially constant seal (208) radial packing force; in particular, the tie rod has mounting holes (306) for assisting in the mounting of the positioning element (305).

11. Pump according to any one of the preceding claims, comprising a fixed static plunger guide unit (303) provided on the pump body (301); in particular, the distance from the flange surface of the plunger chamber (201) is greater than the distance from the movable plunger guide unit, i.e., the plunger seal (208).

12. Pump according to any of the preceding claims, characterized in that it comprises at least one of: a fluid inlet interface (103) configured to provide a fluid path between fluid to be pumped and a working volume (201); the fluid outlet interface (102) is configured to provide a fluid path with the working chamber (201), an outlet for pumped fluid, the inlet and outlet being provided with a check valve, respectively.