GB2579648A

GB2579648A - Injection device

Info

Publication number: GB2579648A
Application number: GB1820075.8A
Authority: GB
Inventors: Derek Baker Martin; David Eastwood Timothy; Ebbah Enock
Original assignee: Calor Gas Ltd
Current assignee: Calor Gas Ltd
Priority date: 2018-12-10
Filing date: 2018-12-10
Publication date: 2020-07-01
Also published as: GB201820075D0

Abstract

An injector comprising a tube 2 with one or more orifices 3 and a sliding member 4 which can move to vary an occluded proportion of the orifices, for injecting a first fluid, such as a liquid hydrocarbon, into a second fluid. The sliding member may move axially along the tube which preferably comprises at least two orifices circumferentially spaced around the tube and/or at a common axial position along the tube. The sliding member can be shaped to occlude part of or all of just one orifice and can have a leading portion that is not wholly perpendicular to the tube. The sliding member can be within the tube or can be a sheath outside. The orifices may have tapered inner bores, a changing radial cross section or can comprise non-linear walls between an outer and inner tube surface. An actuator may move the sliding member to control the differential pressure, flow rate or spray pattern. A system is also described comprising the injector and a vessel, e.g. a pipeline, wherein the injector can be inside the vessel. A method of injection is also disclosed, which can include atomization of the first fluid by passing it through the orifices.

Description

Injection device

Field of the Invention

[0001] The present invention relates to injection devices, systems and methods for injecting a first fluid into a second fluid. More particularly, the present invention relates to injection devices for use in the injection of liquid hydrocarbons or other chemicals into a natural gas stream.

Background

[0002] Fluid injection technology is used for a range of industrial purposes such as chemical processing, water treatment, corrosion control, vessel cleaning and the treatment of natural gas.

[0003] A range of injection devices are known in the art. US2016263537A1 relates to an injection quill and methods of using the same. US2017043311A1 relates to an injection device shaped to atomise a liquid into droplets by means of a gas. US6170979B1 relates to a fluid injection apparatus for introducing additives to a fluid stream that avoids the introduction of points of weakness into a pipeline.

[0004] Common injection devices are known to possess a number of shortcomings in the areas of flow control, turndown ratio and long term precision. Some conventional systems attempt to overcome these shortcomings by utilising multiple injector devices. Such systems are often unsuitable for applications where fine dynamic control is required due to the step changes and disturbances in performance caused when activating or deactivating individual injectors. Multiple injector systems find particular challenges in applications where a significant range of flowrates of the injectant is required.

[0005] In the field of natural gas treatment, regulatory requirements typically require natural gas to have a calorific value within an optimal energy range. Natural gas is made up of several component gases and is therefore subject to natural variation of composition. The compositional inconsistency influences the energy contained within a given volume of gas and it may be necessary to enrich the gas in order to meet the regulatory requirements. Natural gas is often enriched by injecting the natural gas source with a hydrocarbon, typically propane, in sufficient quantities to meet thermal energy requirements.

[0006] The flexibility, controllability and turndown of an injection system are desirable characteristics for any injection system and are key considerations in the enrichment of natural gas via an injection device. The composition and flowrate of natural gas typically varies throughout the life of the natural gas source, resulting in a wide operating envelope requirement for the hydrocarbon gas injection system; accuracy of control is key. An accurate injection system reduces the requirement to flare off-spec gas and increases the availability of the gas source.

[0007] There is therefore a need for injection devices that operate at high accuracy over a large range of flowrates and that can smoothly and dynamically transition between required flowrates.

Statements of Invention

[0008] One aspect of the present invention provides a fluid injector for injecting a first fluid into a second fluid, the injector comprising: a tube, wherein the tube comprises one or more orifices; and, a sliding member, wherein the sliding member is moveable such that it varies an occluded proportion of the one or more orifices.

[0009] Another aspect of the present invention provides a system for injecting a first fluid into a second fluid, the system comprising: an injector comprising a tube, wherein the tube comprises one or more orifices; and, a sliding member, wherein the sliding member is moveable such that it varies an occluded proportion of the one or more orifices; a vessel; wherein the one or more orifices of the injector are in fluid communication with the interior of the vessel.

[0010] Another aspect of the present invention provides a method for injecting a first fluid into a second fluid, the method comprising the steps of: (a) providing a system for injecting a first fluid into a second fluid, the system comprising: an injector comprising a tube, wherein the tube comprises one or more orifices; and, a sliding member, wherein the sliding member is moveable such that it varies an occluded proportion of the one or more orifices; a vessel; wherein the one or more orifices of the injector are in fluid communication with the interior of the vessel; (b) flowing the first fluid into the tube; and (c) passing the first fluid through the one or more orifices into the second fluid.

[0011] According to one aspect of the invention there is provided an injector for injecting a first fluid into a second fluid. The injector comprises a sliding member and a tube. The tube may be a pipe, duct, conduit or similar component that may be configured to allow flow of the first fluid into the tube. The tube may be any shape such as an irregular shape, a cylinder, elliptic cylinder, rectangular prism, or any combination of shapes. The shape of the tube will typically be selected based upon the intended application of the injector. A cylindrical tube may be situationally advantageous due to its internal surface area to volume ratio. The tube will typically comprise an inner and an outer surface with the inner surface at least in partial contact with any fluid flowing through the tube during use. The tube may be supported at one or more ends by a supporting means which may be a mount, locking device, flange, stand, clamp or any other suitable supporting means.

[0012] The tube has one or more orifices in the form of one or more slots, holes or apertures through which the first fluid may flow. The one or more orifices extend through the wall of the tube to allow fluid to pass between the inside and outside of the tube. The one or more orifices may be tapered or curved to promote the formation of a specific spray pattern. More particularly, the one or more orifices may each have a tapered inner bore and/or may comprise a first portion and a second portion, wherein the first portion has a smaller radial cross section than the second portion. Alternatively, the one or more orifices may be curved such that the walls of the one or more orifices formed between the outer surface and the inner surface of the tube are non-linear. Each orifice may also extend through a nozzle or spout designed to promote a specific spray pattern and connected to the outer surface of the tube. Where present, the portion of the orifice extending through the nozzle or spout may also be curved.

[0013] Where the tube has at least two orifices, the orifices may be arranged such that they are axially separated, circumferentially separated, or axially and circumferentially separated along or around the tube. The two or more orifices may not be the same size and/or shape to account for specific requirements relating to fluid flow dynamics and/or pressure management. It may be advantageous for the at least two orifices to have the same geometric shape. It may be further advantageous to arrange the at least two orifices such that they are axially overlapping and circumferentially spaced. The orifices will generally be positioned proximal to the axial mid-point along the length of the tube but may alternatively be positioned in any suitable position along the tube.

[0014] In operation, the number of open orifices and/or percentage a specific orifice is open is varied using a moveable sliding member. The sliding member may be a plunger, shuttle, piston or component of similar design. Generally, the sliding member is configured such that it is at least partly flush with, and seals against, the circumference of the tube. When the injector is in a fully closed position, the sliding member completely occludes the one or more orifices such that no fluid can pass through the one or more orifices. When the injector is in a fully open position, the sliding member is positioned such that it does not obstruct the passage of fluid through any portion of the one or more orifices. In operation, the sliding member moves at least between these two extremes. Advantageously, the movement of the sliding member is axial movement relative to the tube of the injector. Optionally, the sliding member may be incapable of circumferential movement or rotation relative to the tube. The sliding member may be positioned inside the tube, outside the tube, or within a cavity between the inner and outer surfaces of the tube. It may be advantageous to position the sliding member inside the tube to aid the control of pressure and/or flowrates.

[0015] Movement of the sliding member can vary the occluded portion of the one or more orifices to maintain a constant pressure differential across the injector, independent of flow of the first fluid. Movement of the sliding member may beneficially provide control over flow rate of the first fluid. Through control of pressure and/or flow rate, the sliding member may also be used to maintain a desired atomised spray pattern of the first fluid into the second fluid. It may be advantageous to configure the sliding member to move such that its position relative to the tube and the one or more orifices can be varied automatically based on the fluid injection flow required. The optimal pressure across the injector, optimal flow rate of the first fluid, and optimal spray pattern are typically determined by the compositional characteristics and flowrate of the second fluid into which the first fluid is to be injected. The geometry and process requirements of the equipment or vessel that houses the second fluid may also influence the optimal operational parameters.

[0016] The injector may further comprise an actuator configured to move the sliding member. The actuator may be an air operated actuator, a mechanical actuator or an electrical actuator. Preferably, in operation the actuator will move the sliding member axially along the tube in order to vary the occluded proportion of the one or more orifices. The actuator may be configured such that movement of the sliding member maintains a desired differential pressure across the injector, a desired backpressure on one or more components of a wider system to which the injector may be connected, a desired flow rate of the first fluid, or any combination thereof. According to one aspect of the invention, the actuator moves the sliding member to maintain constant differential pressure independent of the flow rate of the first fluid.

[0017] According to one aspect of the invention, the sliding member may comprise a number of segments depending upon the requirements of the injector. The segments may be sealing portions designed to seal against one or more surfaces of the tube, the one or more orifices, the housing, or the inlet. The segments may also comprise instrumentation, one or more spacing portions, one or more connecting portions, or alternative functional segments as required.

[0018] The sliding member may rest within a housing connected to one end of the tube. The housing may be configured to support the sliding member, to secure the tube to connect the sliding member with the actuator, to seal the injector against a portion of a structure, or any combination thereof. The housing may be connected to the tube by a receiving portion configured to accept one end of the tube. The housing and the tube may be connected by one or more suitable fastening means such as, but not limited to, threaded fastening or lock and key receptors. The portion of the housing connected to the tube may have a cross section substantially similar to the cross section of the tube. The housing may have a shoulder, collar or stop such that, when the injector is in the fully open position, the sliding member abuts against the shoulder and is prevented from travelling further away from the axial centre point of the tube. The housing may additionally comprise one or more seals.

[0019] The injector may further comprise an inlet connection to fluidly connect the inner portion of the tube with a source of the first fluid. The inlet connection may be connected to the tube at the opposite end of the tube to the housing or in any other suitable location or arrangement. The inlet connection may be connected to the tube by one or more suitable fastening means such as, but not limited to, threaded fastening or lock and key receptors. The inlet connection and the tube may be connected by means of an inlet mount. The inlet mount may be configured to receive, support and/or connect the inlet connection and/or one end of the tube. The inlet connection is configured to allow fluid to flow into or out of one end of the injector tube. The inlet connection comprises an inlet aperture that may have a cross section substantially similar to the cross section of the tube. The inlet connection may additionally comprise one or more seals. While it is envisaged that fluid may, situationally, enter the injector via the one or more orifices, in general operation, the first fluid may flow into the tube of the injector via the inlet connection. Typically, pressure across the injector causes the first fluid to flow through inlet connection, into the tube and through the one or more orifices into the second fluid.

[0020] The leading portion of the sliding member may be sloped or otherwise configured such that the surface is not partly or wholly perpendicular to the inner surface of the tube and/or the central axis of the tube. The leading portion of the sliding member is considered to be the region of the member closest to the tube inlet connection. Suitably, the leading portion of the sliding member may be chamfered, bevelled or cut out such that, in operation, two or more orifices which are circumferentially spaced and axially overlapping, such that at least a portion of the orifices are positioned at a common axial position along the tube, may not be equally obstructed or occluded by the sliding member.

[0021] The components of the injector may be made from any suitable material. Suitable materials may include metals, alloys, plastics, polymers, organic chemical derived materials, inorganic materials, composite materials, and any combination thereof. The materials utilised in the construction of the injector of the present invention may be advantageously selected to provide a specific benefit to the injector. For example, a high strength corrosion resistant plastic or metal alloy may be employed where the injector is in contact with a corrosive environment. Alternatively, the injector may comprise a material that limits or reduces the build-up of undesirable deposits on the surfaces of the injector.

[0022] As will be understood by the person skilled in the art with the benefit of this disclosure, the sliding member of the present invention provides the injector with the flexibility and variability to smoothly and precisely adjust the occluded portion of the one or more orifices to influence pressure, backpressure, flow, or spray patterns, as required. The smooth ramping transition enabled by the sliding member prevents sudden step changes in performance in the event that the injector requires adjustment due to a change in circumstances. The variability of the injector allows accurate control under high turndown conditions, e.g. a 50:1 turndown ratio.

[0023] The injector of the present invention allows use of a single injector where traditionally, multiple fixed orifice injectors would have been employed. Established systems activate or deactivate individual injectors to control injection flows, system pressures, etc. The present invention replaces the conventional array of injectors with a single device which reduces the required the number of moving parts and overall number of system components while allowing a smooth and gradual transition from an open state to a closed state, as required.

[0024] According to another aspect of the invention there is provided a system for injecting a first fluid into a second fluid. The system may comprise an injector as herein described and a vessel. The one or more orifices of the injector are in fluid communication with the inside of the vessel. It may be advantageous for the one or more orifices to be wholly located inside of the vessel. In practice, the vessel may be a tank, reactor, trench, receptacle or pipeline carrying a second fluid. The injector may be positioned such that the tube spans the interior of the vessel, diametrically spans the interior of the vessel, or extends only partially into the interior of the vessel. It may be advantageous to arrange the injector such that it is perpendicular to the walls of the vessel. However, the injector may be arranged in any suitable orientation relative to the vessel.

[0025] The injector may be partly or wholly contained inside the vessel and the vessel may support the injector partly or wholly at one or more ends of the injector. Where the second fluid is flowing through the vessel, the one or more orifices of the injector tube may be positioned on the tube such that the first fluid flowing through the one or more orifices enters a steam of the second fluid flowing through the vessel in a co-current configuration, a counter-current configuration, a cross-current configuration or any combination thereof. The desired orientation of the one or more orifices relative to the flow of the second fluid will depend upon factors such as fluid mixing requirements, acceptable levels of contact between the first fluid with walls of the vessel, evaporative considerations and the dynamics of fluid flow in the vessel.

[0026] The system may be configured to promote mixing of the first fluid and second fluid downstream of the injector. In operation, the movement of the sliding member, the shape of the sliding member, the position of the one or more orifices, the geometry of the one or more orifices and the characteristics of the fluid flowing through the injector may function synergistically to provide an advantageous spray pattern and/or mixing dynamic when the injector is used to inject a first fluid into a second fluid.

Optionally, the system may comprise a mixing device. The mixing device may be positioned downstream of the injector to promote mixing of the first fluid and the second fluid. The mixing device may be a static mixer, a mechanical mixer, a jet mixer or any other suitable mixing apparatus.

[0027] The system may further comprise one or more flow control valves. The flow control valves may be gate valves, globe valves, ball valves, butterfly valves, diaphragm valves or any other suitable type of valve. The flow control valves may control the flow of the first fluid to and/or through the injector such that the sliding member of the injector may be actuated to control pressure independently of flow. Alternatively, where the sliding member is actuated to control flow rate of the first fluid through the injector, the upstream flow control valve may beneficially be removed or absent from the system.

[0028] The section of vessel in which the injector is contained may be connected to a larger structure or process via one or more flanges. Positioning the injector within a flanged section of a vessel enables the injector to be easily removed and accessed for repair, maintenance or replacement. The vessel may also be connected to, or alternatively, comprise, one or more analytical instruments. Suitable analytical instruments may include temperature probes, pressure sensors, flow rate analysers, compositional analysers, or any suitable analysis instrument, as required.

[0029] According to another aspect of the invention, there is provided a method for injecting a first fluid into a second fluid. The method may be used with the injector or system herein described. The method comprises the steps of (b) flowing a first fluid into the tube of the injector, and (c) injecting the first fluid into a vessel through the one or more orifices of the injector. The vessel may contain a second fluid or a flow thereof. The steps of the method may be carried out in any order or sequence.

[0030] Where the first fluid is a liquid, the method may further involve the step of atomising the first fluid. The first fluid may be atomised via its passage through the one or more orifices of the injector.

[0031] The method may further involve the step of actuating the sliding member to maintain a constant differential pressure across the injector. This method step may optionally be carried out dependent, or independent the flow rate of the first fluid, as required.

[0032] Specific features of the system may result in additional methods steps as part of method. In situations where the system comprises a flow control valve positioned upstream of the injector, the method may further involve the steps of (i) actuating the sliding member to maintain a constant backpressure on the flow control valve, and/or (ii) actuating the flow control valve to provide a specific flow rate of the first fluid to the injector. Similarly, if the system comprises a mixing device, the method may additionally comprise the step of mixing the first fluid and the second fluid via the mixing device downstream of the injector.

Brief Description of the Drawings

[0033] Embodiments of the present invention will now be described with reference to the following drawings, in which: Figure 1 is an axial cross section of an injection device of the present invention where the injector is in the open position; Figure 2 is an axial and a circumferential cross section of the tube of the injector of Figure 1; Figure 3 is an axial cross section of a sliding member that may be utilised with the injection device of Figure 1 or Figure 2; Figure 4 is an axial and a circumferential cross section of the housing of the injector of Figures 1 and 2; Figure 5 is an axial cross section of the injection device of Figure 1 where the injector is in the closed position; Figure 6 is an axial and a circumferential cross section of the inlet mount and inlet connection of the injector of Figures 1 and 2; Figure 7 is a schematic of a system for the injection of a first fluid into a second fluid; Figure 8 is an axial cross section of alternative sliding members that may be utilised with the injectors of the present invention.

Figure 9 is a flowchart with the steps of an exemplary method for injecting a first fluid into a second fluid; and Figure 10 is a flowchart of the method of Figure 9 including additional method steps.

Detailed Description

[0034] The following examples present various aspects of the present invention and means of implementing the same. The examples provided are merely exemplary injectors and are not intended to limit the scope of the invention.

[0035] Figure 1 shows a cross section of an injector 1 within the scope of the present invention. The injector 1 comprises a cylindrical tube 2, shown in both axial and circumferential cross sectional isolation in Figure 2, having three orifices 3 in the form of rectangular slots cut into the wall of the tube. The tube has a central axis 23 extending in the axial direction. The orifices extend from the inner surface of the tube 21 to the outer surface of the tube 22. The orifices 3 are circumferentially spaced and are positioned in an axially overlapping alignment such that each orifice is positioned at a common axial position along the tube. The three orifices 3 are arranged such that they are positioned at about forty five degree intervals around the circumference of the tube 2 and are positioned close to the mid-point of the axial length of the tube 2.

[0036] The orifices 3 are tapered towards the outer surface 22 of the tube 2 such that surface area of each orifice 3 on the outer surface 22 of the tube 2 is greater than the surface area of the same orifice 3 on the inner surface 21 of the tube 2. The tapering 3 reduces the pressure upon the fluid passing through the orifices 3 and promotes a desirable spray pattern of the first fluid 11 in combination with atomisation in situations where the first fluid 11 is also a liquid.

[0037] A sliding member 4, shown in isolation in Figure 3, is positioned partly inside the tube 2. The sliding member is made up from of several substantially cylindrical segments 41. The leading segment 45 of the sliding member 4 is a cylinder with the diameter comparable to the inner surface 21 of the tube 2. The sliding member 4 rests such that the leading segment 45 axially contacts and seals against the inner surface 21 of the tube 2. The leading portion 46 of the sliding member 4 is substantially perpendicular to the inner surface 21 of the tube 2. When the injector 1 is in a fully open position, as shown in Figure 1, the sliding member 4 rests partly within the tube 2 such that the entire surface area of the three orifices 3 is exposed and unobstructed by the sliding member 4. The sliding member includes a number of grooves 42, 44 used to locate sealing rings to reduce leakage between the segments 41 and the inner surface 21 of the tube 2, or between the segments 41 and the first and second portions 65, 66 of a housing 6.

[0038] The end of the tube 2 in which the sliding member 4 rests is connected to housing 6, as shown in isolation in Figure 4. The other end of the housing is connected to an inlet connection 7 via an inlet mount 10. When the injector 1 is assembled, one end of the tube 2 is accepted by a receiving portion 64 of the housing 6 such that the housing 6 surrounds the end of the tube 2. The inner bore of the receiving portion has a diameter comparable to the outer surface 22 of the tube 2 such that the receiving portion 64 seals against the outer surface of tube 2. The axial end of the tube 2 abuts against a first internal shoulder 63 that prevents the tube 2 from further entering the housing 6. The housing 6 has a first portion 65 and second portion 66 with sequentially smaller cylindrical inner bores that each share their cylindrical centre axis with the receiving portion 64 and the injector tube 2, respectively. Part of the sliding member 4 not within the tube 2 rests within the first and second portions 65, 66. The tube 2 and housing 6 are configured such that when connected, an enlarged segment 47 of sliding member 4, larger in diameter than the other segments, rests inside the housing and abuts against a second internal shoulder 61 when the injector is in the fully open position as shown in Figure 1. The second internal shoulder 61 and the enlarged segment 47 prevent the sliding member 4 from travelling further away from the axial centre point of the tube 2.

[0039] Figure 5 shows a cross section of the injector 1 of Figure 1 where the injector 1 is in the closed position. In Figure 5, the sliding member 4 has moved along the inside of the tube axially away from its rest position in the housing 6 by means of an actuator 8 (not shown), to obstruct the three orifices 3 of the tube 2. When the sliding member 4 is positioned as shown in Figure 5, the first fluid 11 entering the tube 2 via the inlet connection 7 is prevented from leaving the tube 2 as no viable flow path through the orifices 3 is present. In operation, the sliding member 4 moves between the positions shown in Figure 1 and Figure 5 to sufficiently occlude the three orifices 3 to maintain a desired pressure, flowrate of fluid, or spray pattern, as required. When the injector 1 is in the fully closed position, as shown in Figure 5, the sliding member 4 is prevented from travelling further towards the inlet connection 7 due to the abuttal of the enlarged segment 47 and the end of the tube 2 within the receiving portion 64 of the housing 6.

[0040] Figure 6 shows the inlet connection 7 and inlet mount 10 of the injector 1. The inlet mount 10 has an inner bore of sufficient and consistent diameter to receive and seal against a narrow gauge portion of the inlet connection 7 and the end of the injector tube 2 which is not connected to the housing 6. The inlet mount 10 connects and aligns the inlet connection 7 with the injector tube 2. The injector tube 2, inlet connection 7 and inlet mount 10 each share the same cylindrical centre axis when the components are connected. In operation, the first fluid 11 enters the injector 1 via the inlet connection 7.

[0041] Figure 7 shows an injection system 100 in which the injector 1 of Figure 1 may be utilised. The injector 1 is mounted such that the injector tube 2 diametrically spans a section of a pipeline vessel 101. The pipeline vessel 101 is connected to a pipe network via flanges 104 such that the section of pipeline containing the injector 1 may be easily isolated and removed for maintenance or replacement. The orifices 3 of the injector 1 are contained wholly within the vessel 101 such that when the first fluid 11 flows into the injector 1 via flow control valve 103 upstream of the injector 1, the first fluid 11 is dispersed within the second fluid 12 flowing through the vessel 101. Downstream of the injector 1 is a mixing device 102. The mixing device improves the mixing dynamics of the first fluid 1 and second fluid 12, as required.

[0042] Figure 8 shows alternative configurations of the sliding member of Figure 3. The leading portion 46 of the leading segment 45 may be sloped, bevelled, chamfered or cut away such that it is not wholly perpendicular to a central axis 23 of the tube 2. The sliding member 4 may occlude different orifices 3 of the tube 2 to different extents when the injector 1 is in a partially closed position. The sliding members of Figure 8 may allow more accurate control of spray patterns, flow rate of the first fluid 11, or injector pressure depending upon the application to which the injector 1 is applied.

[0043] Figure 9 shows a flowchart with the steps of an exemplary method 200 for injecting a first fluid into a second fluid. The method involves the steps of (b) 201 flowing a first fluid into the injector and (c) 202 injecting the first fluid into a second fluid through one or more orifices of the injector. The method 200 of Figure 9 is applicable to the injector 1 of Figure 1 and any alternative injector within the scope of the present invention.

[0044] Figure 10 shows a flowchart of the method 300 of Figure 9 including additional method steps that may be optionally implemented in an injection system 100 having a mixing device 102 and a flow control valve 103 as part of the components of the system in which the injector is housed. More particularly, the method 300 of Figure 10 may be applied to the system of Figure 8 with a flow control valve and mixing device. The method includes of the steps of (b) 201 flowing a first fluid into an injector; (c) 202 injecting a first fluid into a vessel through one or more orifices of the injector; (d) 301 atomising the first fluid; and (e) 302 mixing the first fluid and the second fluid via a mixing device. Additional method steps include: (aa) 303 actuating a sliding member to maintain a constant flow rate of the first fluid through the injector, (ba) 304 actuating a sliding member to maintain a constant differential pressure across the injector, (ca) 305 actuating a flow control valve to provide a specific flow rate of the first fluid to the injector, and (cb) 306 actuating a sliding member to maintain a constant backpressure on the flow control valve. When the method of Figure 10 is applied to the injection system of Figure 8, the second fluid will be contained within the vessel in which the injector is housed.

[0045] The injector 1, system 100 and method 200 of the present invention may be applicable to a range of industrial and commercial situations. In particular, the injector 1 is envisaged for the injection of hydrocarbons or other chemicals into a gas stream. More particularly, the injector 1 may be used to inject one or more hydrocarbons into as natural gas stream.

[0046] In natural gas applications, the injector 1 may be utilised to inject liquid hydrocarbons into a natural gas stream. The liquid hydrocarbon is atomised by the injection device to facilitate the evaporation and mixing of the hydrocarbon with the natural gas stream. The liquid hydrocarbon may be methane, ethane, ethylene, acetylene, propane, propene, butane, isobutane or any other suitable hydrocarbon. In some situations, it is advantageous to use propane as the liquid hydrocarbon. The liquid hydrocarbons may be derived from fossil fuels and/or biological renewable sources.

[0047] The injector of the present invention may provide a number of additional advantages when used for the enrichment of natural gas. The injector's design allows the handling of liquid hydrocarbons instead of merely gaseous hydrocarbons. The ability to deliver and atomise liquid hydrocarbons into a gas stream allows the use of smaller pipes, fittings, instruments and control equipment than would be required for enrichment operations via gas delivery. The injection, atomisation, and subsequent evaporation removes the additional energy required for vaporisation of the injection fluid in gas to gas delivery systems. Liquid delivery also allows the system to be operated at a lower design temperature which is particularly advantageous in high pressure applications. Moreover, the ability to operate a low temperatures reduces or removes the requirement for insulation in the injection equipment to reduce heat losses as the hydrocarbons do not need to be maintained in their gaseous state.

[0048] In lower pressure bio-hydrocarbon applications in particular, the injector can be used to maintain a constant backpressure on the upstream flow control valve to reduce the potential for hydrocarbon liquid 'flashing' in the valve. A reduced risk of flashing allows greater flexibility in valve design, valve control and the viable operating temperature of the wider system.

[0049] The injector of the present invention may also be utilised to inject hydrate inhibitors, corrosion inhibitors, biocides, antifoam agents, deoilers, demulsifiers and any combination thereof into a natural gas or liquid hydrocarbon stream. It is also envisaged that the injector of the present invention may be utilised to inject reactants in a chemical processing stream.

[0050] In addition to the claimed subject matter in the appended claims, the following concepts and features may serve as basis for additional claims in this application, or in subsequent divisional applications. The concepts and features below are not intended as an exhaustive list and provide further examples of injectors, systems and methods within the scope of this disclosure.

[0051] A first concept is an injector for injecting a first fluid into a second fluid, the injector comprising: a tube, wherein the tube comprises one or more orifices; and, a sliding member, wherein the sliding member is moveable such that it varies an occluded proportion of the one or more orifices.

[0052] A second concept is a system for injecting a first fluid into a second fluid, the system comprising: the injector of the first concept; and a vessel, wherein the one or more orifices of the injector are in fluid communication with the interior of the vessel.

[0053] A third concept is a method for injecting a first fluid into a second fluid, the method comprising the steps of: (a) providing a system of the second concept; (b) flowing the first fluid into the tube; and (c) passing the first fluid through the one or more orifices into the second fluid.

[0054] The following features may be included in any combination, permutation or suitable manner with any of the first, second or third concepts, as appropriate.

Feature A: An injector wherein the tube is open at each end, optionally wherein the tube is a pipe, duct or conduit. Feature B: An injector wherein the tube is an irregular shape, a cylinder, an elliptic cylinder, rectangular prism or any combination of shapes. Feature C: An injector wherein the tube is supported at one or more ends. Feature D: An injector wherein the injector is supported by means of a mount, locking device, flange, stand, clamp, or screw fit mechanism. Feature E: An injector wherein the tube comprises at least two orifices. Feature F: An injector wherein the tube comprises at least two orifices and the at least two orifices are arranged such that they are axially overlapping, such that at least a portion of at least two of the at least two orifices are positioned at a common axial position along the tube, and are circumferentially spaced. Feature G: An injector wherein the tube comprises at least two orifices and the at least two orifices are arranged such that they are axially spaced and are circumferentially overlapping, such that at least a portion of at least two of the at least two orifices are positioned at a common circumferential position around the tube. Feature H: An injector wherein the tube comprises at least two orifices and the at least two orifices are arranged such that they are axially spaced and are circumferentially spaced. Feature I: An injector wherein the tube comprises at least three orifices and the at least three orifices are arranged such that some of the orifices are axially overlapping or are circumferentially overlapping. Feature J: An injector wherein the one or more orifices are tapered or curved. Feature K: An injector wherein the one or more orifices extend through a nozzle or spout on the outer surface of the tube. Feature L: An injector wherein the injector comprises at least two orifices that are of different sizes and/or shapes. Feature M: An injector wherein the injector comprises at least two orifices that are of identical size and/or shape. Feature N: An injector wherein the sliding member is a plunger, shuttle, or piston. Feature 0: An injector wherein the sliding member is shaped such that it may occlude part or all of only one of the at least two orifices. Feature P: An injector wherein the leading portion of the sliding member comprises a sloped surface such that it is not wholly perpendicular to a central axis of the tube. Feature Q: An injector wherein the sliding member is at least partly flush with, and seals against, the circumference of the tube. Feature R: An injector wherein the sliding member is within the tube. Feature S: An injector wherein the sliding member is a sheath positioned on the outside of the tube. Feature T: An injector wherein the sliding member is within a cavity between the outer surface and the inner surface of the tube. Feature U: An injector wherein the sliding member fully occludes all of the one or more orifices when the injector is in a fully closed position and occludes no part of the one or more orifices when the injector is in a fully open position. Feature V: An injector wherein the sliding member may be moved adopt any position along the tube between the fully closed and fully open positions. Feature W: An injector wherein the sliding member is configured to move axially along the tube. Feature X: An injector wherein the sliding member is configured to be incapable of circumferential movement relative to the tube. Feature Y: An injector wherein the components of the injector are formed from materials comprising metals, alloys, plastics, polymers, organic chemical derived materials, inorganic materials, composite materials, and any combination thereof. Feature Z: An injector wherein the injector further comprises an actuator configured to move the sliding member. Feature AA: An injector wherein the actuator is an air operated actuator, a mechanical actuator or an electrical actuator. Feature AB: An injector wherein the sliding member is actuated to maintain a constant differential pressure across the injector, optionally wherein the differential pressure is maintained independent of flow rate through the injector. Feature AC: An injector wherein the sliding member is actuated to maintain a constant flow rate of the first fluid through the injector. Feature AD: An injector wherein the sliding member is actuated to maintain a constant backpressure on the flow control valve. Feature AE: An injector wherein the sliding member is actuated to maintain a desired spray pattern of fluid passing through the one or more orifices. Feature AF: An injector wherein the sliding member comprises one or more spacing and/or connecting segments. Feature AG: An injector wherein the sliding member comprises one or more seals configured to seal against the circumference of the tube. Feature AH: an injector wherein the sliding member comprises one or more analytical or measurement instruments. Feature Al: An injector wherein the injector comprises a housing. Feature AJ: An injector herein the housing is connected to one end of the tube. Feature AK: An injector wherein the housing is configured to contain part of the sliding member. Feature AL: An injector wherein the housing comprises a stop configured to prevent the sliding member from wholly leaving the interior of the tube. Feature AM: An injector wherein the housing comprises one or more seals. Feature AN: An injector wherein the injector comprises an inlet connection. Feature AO: An injector wherein the injector comprises an inlet mount configured to connect the inlet connection to one end of the tube. Feature AP: A system comprising a vessel, optionally wherein the vessel is tank, reactor, trench, receptacle or pipeline. Feature AQ: A system comprising a mixing device, optionally wherein the mixing device is positioned downstream of the injector. Feature AR: A system wherein the mixing device is a static mixer, a mechanical mixer, or a jet mixer. Feature AS: A system comprising a flow control valve, optionally wherein the flow control valve is positioned upstream of the injector. Feature AT: A system wherein the flow control valve is a gate valve, globe valve, ball valve, butterfly valve or diaphragm valve. Feature AU: A system wherein the injector is positioned such that the tube diametrically spans the interior of the vessel. Feature AV: A system wherein the one or more orifices of the injector are in fluid communication with the interior of the vessel. Feature AW: A system wherein the one or more orifices of the injector are located wholly inside the vessel. Feature AX: A system wherein the tube of the injector is positioned such that the fluid entering the vessel through the one or more orifices enters the vessel in a co-current configuration, a counter-current configuration, a cross-current configuration, or any combination thereof. Feature AY: A system wherein the vessel is connected via one or more flanges. Feature AZ: A method comprising the step of atomising the fluid via passage of the fluid through the one or more orifices of the injector. Feature BA: A method comprising the step of actuating the sliding member of the injector to maintain a constant differential pressure across the injector. Feature BB: A method wherein the sliding member of the injector is actuated dependent, or independent the flow rate, pressure, or spray pattern, as required. Feature BC: A method comprising the step of actuating the sliding member to maintain a constant backpressure on the flow control valve. Feature BD: A method comprising the step of actuating the flow control valve to provide a specific flow rate of fluid to the injector. Feature BE: A method comprising the step of mixing the first fluid and the second fluid via the mixing device downstream of the injector.

Claims

Claims 1. An fluid injector for injecting a first fluid into a second fluid, the injector comprising: a tube, wherein the tube comprises one or more orifices; and a sliding member, wherein the sliding member is moveable such that said member varies an occluded proportion of the one or more orifices.
2. An injector as claimed in claim 1, wherein the sliding member is configured to move axially along the tube.
3. An injector as claimed in claim 1 or 2, wherein the tube comprises at least two orifices.
4. An injector as claimed in claim 3, wherein the at least two orifices are circumferentially spaced around the tube.
5. An injector as claimed in claim 4, wherein at least a portion of each of the at least two orifices are positioned at a common axial position along the tube.
6. An injector as claimed in any one of claims 3 to 5, wherein the sliding member is shaped such that said member may occlude part or all of only one of the at least two orifices.
7. An injector as claimed in any of the preceding claims, wherein a leading portion of the sliding member is not wholly perpendicular to a central axis of the tube.
8. An injector as claimed in any of the preceding claims, wherein the sliding member is within the tube.
9. An injector as claimed in any of claims 1 to 7, wherein the sliding member is a sheath positioned on the outside of the tube.
10. An injector as claimed in any of the preceding claims, wherein: at least one of the one or more orifices has a tapered inner bore; or at least one of the one or more orifices comprises a first portion and a second portion, wherein the first portion has a smaller radial cross section than the second portion; or at least one of the one or more orifices comprises walls formed between an outer surface and an inner surface of the tube, wherein the walls are non-linear.
11. An injector as claimed in any of the preceding claims, wherein the tube is supported at one or more ends.
12. An injector as claimed in any of the preceding claims, further comprising an actuator configured to move the sliding member, optionally wherein the actuator is configured to move the sliding member to maintain a constant differential pressure across the injector.
13. A system for injecting a first fluid into a second fluid, the system comprising: the injector as claimed in any of the preceding claims; and a vessel; wherein the one or more orifices of the injector are in fluid communication with the interior of the vessel.
14. A system as claimed in claim 13, wherein the injector is inside the vessel.
15. A system as claimed in claim 13 or 14, further comprising a mixing device, optionally wherein the mixing device is positioned downstream of the injector.
16. A system as claimed in any of claims 13 to 15, further comprising a flow control valve, optionally wherein the flow control valve is positioned upstream of the injector.
17. A system as claimed in any of claims 13 to 16 wherein the injector is positioned such that the tube diametrically spans the interior of the vessel.
18. A system as claimed in any of claims 13 to 17, wherein the vessel is a pipeline.
19. A method of injecting a first fluid into a second fluid, the method comprising the steps of: (a) providing a system as claimed in any of claims 13 to 18; (b) flowing the first fluid into the tube; and (c) passing the first fluid through the one or more orifices into the second fluid.
20. A method as claimed in claim 19, further comprising the step of: atomising the first fluid by passing the first fluid through at least one of the one or more orifices.
21. A method as claimed in claim 19 or 20, further comprising the step of: actuating the sliding member to maintain a constant differential pressure across the injector.
22. A method as claimed in claim 21, wherein the constant differential pressure is maintained independent of the flow rate of the first fluid.
23. A method as claimed in any of claims 19 to 22, wherein the system comprises a flow control valve positioned upstream of the injector and the method further comprises the step of: actuating the sliding member to maintain a constant backpressure on the flow control valve.
24. A method as claimed in any of claims 19 to 23, further comprising the step of: mixing the first fluid and the second fluid downstream of the injector.
25. A method as claimed in any of claims 19 to 24, wherein the first fluid is a liquid hydrocarbon derived from fossil fuels and/or biological renewable sources, a chemical reactant, or a chemical treatment.