Patent Application
20150361969
Chemical injectors
Seals are a common wear item on chemical injectors. The seals wear out due to chemical exposure, operating pressure and temperature. If the chemical injector is operated at very low pressures the seal does not work well and if at high pressure the seals wear out too fast. Seal failure causes a mess that needs to be cleaned up, and possibly an environmental pollution problem.
In an embodiment, a chemical injector or pump is provided that does not have seals and that will never leak onto soil. The pump is mounted inside a tank that contains chemical in use, so that if there is flow by the plunger, the chemical is still contained in the tank.
In an embodiment, there is disclosed a chemical injector, comprising a tank, a stinger extending into the tank, the stinger having a pump head comprising a piston head within a sleeve, the sleeve defining a chamber, and having an inlet check valve for one way flow of fluid into the chamber and an outlet check valve for one way flow of fluid out of the chamber, the piston head having a close tolerance liquid seal with sleeve; a drive connected to reciprocate the piston head in the sleeve; and outlet tubing connected to the outlet check valve and the outlet tubing extending out of the tank.
In various embodiments, there may be included any one or more of the following features, in the chemical injector, the liquid seal comprises a metal alloy to metal alloy seal, the outlet tubing is connected into a sight glass outside of the tank, the stinger extends downward into the tank from an upper surface of the tank, a housing encloses the drive for the plunger and the outlet tubing passing through the housing, and any of the previously mentioned features contained within a secondary containment structure.
There will now be described embodiments of the chemical injector with reference to the figures by way of example, and in which like reference characters denote like elements, in which:
Referring to
As shown in
The housing 30 houses a drive 34 for the pump 20. The drive 34 provides the motive force for moving the reciprocating plunger head 33 inside sleeve 27. Various drives may be used. In the embodiment shown, a wheel 36 rotates on an axle 38. The axle 38 has an axis A and an eccentric portion 70 has an axis that is parallel to but off-set laterally from axis A. A plate 71 has a central opening (not shown) that receives the eccentric portion 70 and is connected via links 39 to plunger 32. As the axle 38 rotates, the axis of the eccentric portion 70 rotates around the axis A, and this eccentric motion causes links 39 and plunger 32 to reciprocate. The amount of movement by the plunger 32 may be made larger or smaller by change the degree of lateral offset of the axis of the eccentric portion 70 from the axle 38. The wheel 36 may be driven by a motor (not shown) that is connected by a belt (not shown) to the wheel 36. In another embodiment (not shown), an oscillating rotary output of an electric motor may be used for the motor. In another embodiment (not shown) a continuously rotating motor could be used, coupled to the rod 38 so that the rod end moves in a continuous circle as in a conventional piston engine.
The plunger end of the injector is shown in
As seen best in cross-section in
The sleeve 27 may be reinforced by for example annular metal elements 46 secured together by rods 48 around sleeve 27. The close tolerance liquid seal also helps allow trapped gases to escape the chamber 47 defined by the sleeve 27 and reduce or eliminate cavitation. Either or both of the solid surfaces forming the seal may be any of various hard materials such as for example metal alloy, where the metal alloy may be tungsten carbide of any suitable grade, metal or ceramic or combinations of various such materials. The object is to avoid weak seals such as elastomeric or polymeric seals that degrade relatively rapidly in the chemicals or due to wear.
Outlet tubing 52 is connected to the outlet check valve 28, and the outlet tubing extends out of the tank 12 through the housing through loop 54 to a rate gauge 56. Chemical pumped by the pump 20 enters the bottom of the rate gauge 56 and exits the top. The end 58 of the outlet tubing 52 may be connected to an injection point in for example an oil industry vessel, tubular or pipe (not shown). A pressure safety valve 60 may be provided on the outlet tubing 52. A shut off valve 62 may be provided on the end 58 of the tubing 52 to allow the rate gauge 56 to be isolated from the injection point, and the rate gauge 56 drained through valve 64 while air may enter the tubing 52 through valve 63 to allow the rate gauge to drain. The rate gauge 56 may operate in conventional fashion by starting with the rate gauge 56 empty and allowing it to fill with pumping and marks on the gauge 56 along with a timer can be used to determine how fast the rate gauge 56 fills. The rate gauge 56 may be drained into a tray 66, and the chemical then returned to the tank 12. A conventional tank level gauge 68 may be provided on the tank 12.
The stinger 20 may be inserted into any part of the tank 12, including a manifold or secondary vessel 21 connected to the tank 12 and such a manifold or secondary vessel may be considered part of the tank 12 so long as the parts are connected for free flow of fluid from the main part of the tank to the manifold or secondary vessel. As shown in
Thus there is disclosed a reciprocating top drive system that reciprocates a pump rod 32 that goes to the bottom of the pump stinger 22 to the bottom of the tank 12. The pump head 50, comprising piston head 33 and sleeve 27 is mounted at the end of the stinger 22 and is submerged in fluids in the tank 12. The pump head 50 is for example carbide piston and sleeve 27 with a very tight machined tolerance that allows the piston head 33 to pump up and down and glide in a film of the chemical that is slipping by the tolerance.
The tolerance will only let a very small portion of the liquids to sneak by the piston 33 and that thin film lubricates the piston 33 evenly all around the cylinder 27. This pump, made with conventional materials used for oil servicing tools, can operate at low pressures or high pressures up to 5000 PSI with low wear.
This is believed by the inventor to be a huge breakthrough in well site chemical pumps to reduce spills and maintenance costs over the years. Also it prevents or at least reduces environmental problems from chemical getting into soil.
The pump is a vertical top drive assembly reciprocating a pump rod 32 up and down in the stinger tube 22. The stinger tube 22 is easily removed by flipping the top drive back and pulling the stinger tube out to maintain check valves or pump head parts.
A secondarily contained bulk tank preferably houses all the fittings and sight glasses so that there is no chance of loose connections or broken sight glasses to worry about leaking into soil.
Everything is preferably secondarily contained and will rarely leak.
A high pressure rate gauge 56 may be used to set the chemical injection rate per day. As the fluid discharges the pump, it passes through a visible high pressure sight glass and it gives precise injection rates as per field conditions, field conditions consist of exact line pressures, chemical viscosity, chemical temperature and pump power input RPM. All of these conditions can change your pump rate so it is best to set every pump to field conditions.
The tank level gauge 68 and the high pressure rate gauge 56 are preferably mounted inside the tank secondary containment area 16 so that all gauges and fittings are inside the secondary containment area 16. The pump goes in the chemicals tank 12, and is sealless. Previous pumps known to the inventor had Teflon seals, which wore out. This pump may run at high pressure for example 6000 psi. The pump outlet goes through a rate gauge or like device to check how much is being injected.
The submersible design that allows a machined piston and cylinder to be used without a Teflon seal is a big advancement since the liquid slip lubricates and allows any small air bubbles to be pushed out of the piston. This design reduces or eliminates any air locks that will not let the pump prime and pump correctly. The slip fluid keeps the piston washed clean.
The high pressure sight glass makes it possible to meter the exact amount of chemical needed daily to cut chemical waist and cost.
Immaterial variations in the disclosed embodiments may be made without departing from the claims.
