Abstract:
Metering device in particular for metering an additive in the field of oil exploration with a metering element adjustable by an adjusting means. To improve such a metering device in that already with minimal movement of the adjusting means in a constructive simple way a particular amount of additive is added to raw material and also to quickly interrupt the metering, the metering element comprises a metering gap and a valve means arranged behind the metering gap downstream in fluids moving direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to PCT/EP2004/007950 filed 16 Jul. 2004 and to German Application No. 203 11 029.3 filed 17 Jul. 2003, all hereby incorporated herein by reference. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a dosage feed device, in particular for the dosage feed of an additive fluid in crude oil production, with a dosing element adjustable by an adjustment device. 
     This sort of additive fluid is added in the production of both crude oil and natural gas. It is used, for example, for inhibiting the formation of hydrates, inhibiting corrosion, preventing the deposition of crusts, for the suppression of wax precipitates, etc. Normally, this type of additive fluid is termed an inhibitor. The composition of the inhibitor depends on the composition of the crude oil or natural gas and is also dosed in different quantities. 
     A suitable dosage feed device is known from practice, whereby the inhibitor is added relatively early in the production of the raw material using the appropriate dosing element, which generally occurs on exit from the corresponding bed of deposits. The inhibitor is later removed before further processing of the raw material occurs in a refinery or similar facility. 
     SUMMARY OF THE PREFERRED EMBODIMENTS 
     The object of the invention is to improve a dosage feed device of the type mentioned at the beginning such that already with a minimum movement of the adjustment device in a constructively simple way, a specific quantity of additive fluid can be added to the raw material, whereby a similarly quick interruption in the dosage feed can also occur. 
     This object is solved by the features of claim  1 . 
     According to the invention, the dosing element exhibits a dosing gap and a valve device positioned following the gap in the direction of flow of the additive fluid. The amount of the additive fluid to be passed to the raw material is defined or, if necessary, can be varied by the dosing gap, whereas a fast initiation of the dosage feed and also a fast interruption of the dosage feed occurs through the valve device. According to the invention therefore, a device for the quantitative dosage feed is used in combination with a valve device essentially formed as an opening/closing device. The combination of both elements is constructed to be compact and simple and can also be actuated by the adjustment device safely and reproducibly at places where access is difficult. 
     The dosing gap can be defined such that after appropriate opening of the valve device a constant quantity of additive fluid is always fed. Consequently where necessary, variation of an opening area of the dosing gap is possible, for example, depending on the composition of the raw material to which additive fluid is to be fed, the dosing gap is set appropriately before application of the dosage feed device. Another possibility is that the dosing gap with its opening area can be directly adjusted variably at the point of application. 
     A simple realisation of a dosing gap is conceivable in which it is formed between a dosing cone and a counter element, whereby the dosing cone and counter element are movable relative to one another. Due to the relative movement the opening area of the dosing gap is varied. This variation can occur through once-only adjustment and then retention of the corresponding opening area, but it can also though be remotely controlled and can also be implemented at the point of application by appropriate relative movement of the dosing cone and counter element. 
     The dosing gap itself can be formed in various ways. It is conceivable that it is, for example, composed of a number of slit-shaped openings or also formed with an annular shape between the dosing cone and the counter element. 
     In a simply constructed embodiment the dosing cone can be formed as an end section of a displaceable sleeve which expands conically in the direction of the fluid flow, whereby at least this end section is arranged for displacement in a guide sleeve as counter element. By appropriate displacement of the displaceable sleeve with the conical end section, the opening area of the dosing gap is varied. It is, of course, also conceivable that the displaceable sleeve with conical end section is fixed and the guide sleeve moves appropriately along the end section, whereby the opening area of the dosing gap is also variable. 
     In order to realise guidance of the displaceable sleeve independently of the formation and variation of the dosing gap, a guide section of the displaceable sleeve can be supported for displacement in a support sleeve between an extended and a withdrawn position. In the extended position of the displaceable sleeve the maximum opening area of the dosing gap is produced and in the withdrawn position the opening area of the dosing gap can be reduced to zero if necessary, i.e. the dosing gap is closed. 
     The displaceable sleeve can be subject to spring pressure in the direction of the withdrawn position in order to move the displaceable sleeve in a simple way into its withdrawn position, especially in an emergency, such as the failure of the adjustment device. 
     In order to define the withdrawn position in a simple manner, an especially annular stop can be spaced essentially radially outwards from the displaceable sleeve for defining the withdrawn position. In the withdrawn position this stop contacts the supporting sleeve at one end. 
     In order to realise the spring pressure constructively simply, a compression spring can be arranged between the support sleeve and a first sleeve end of the displaceable sleeve. 
     In order to not have to form the first sleeve end in a special way for the support of the compression spring, a support ring can be arranged on the first end of the sleeve. This support ring can be attached there, especially releasably. 
     In order to separate the valve device in a simple manner spatially from the dosing gap and at the same time to obtain a constructively simple solution for closing the valve device, a valve-seat sleeve can be arranged between the valve device and the dosing gap in the flow channel which is contacted on one side by an appropriate valve element in the valve closure position. This means that with an open valve device or with a valve element that does not contact the valve-seat sleeve, the additive fluid flows through the valve-seat sleeve in the direction of the raw material to which it is to be dosed. In the closed position of the valve device the valve-seat sleeve is closed by contact of the valve element, so that in principle the valve-seat sleeve can be considered as part of the valve device. Depending on the shape of the valve-seat sleeve, the valve element exhibits an appropriate shape. There is also the possibility of arranging the valve element in the interior of the valve-seat sleeve in the valve-closed position so that it closes the corresponding flow channel there. 
     A simple realisation of an appropriate valve device can be seen in that it is a non-return valve, subjected to a force in the direction of the valve-seat sleeve. In this way the valve element is opened in opposition to the applied force for dosing the additive fluid and is used especially as an emergency closure mechanism if the corresponding adjustment device fails. This means that the valve device is a normally closed valve device or a valve which is closed in the idle state. 
     A simple interaction between the valve element and the valve-seat sleeve can be seen in that the essentially spherical valve element contacts a corresponding opening edge of the valve-seat sleeve in the valve-closed position, thus tightly closing the interior of the valve-seat sleeve. Consequently, no further additive fluid can flow through the valve-seat sleeve for dosage feed in the direction of the corresponding raw material. 
     In order to be able to arrange the valve-seat sleeve relatively to the guide sleeve at a fixed distance, a spacer sleeve can be arranged between the valve-seat sleeve and the guide sleeve. With this sleeve, for example, a flange of the valve-seat sleeve, protruding radially outwards can be pressed against a protrusion of a corresponding housing part, protruding correspondingly radially inwards, where it is held in contact. 
     For the simple accommodation and support of the valve element, it can be arranged in an essentially cup-shaped element receptacle, between which and an inner side of a housing hole at least one fluid opening is formed. This means that with the valve open the additive fluid flows around the element receptacle and through the at least one fluid opening. Of course, there is also the possibility of arranging many such fluid openings, for example, in the circumferential direction of the element receptacle between it and the inner side of the housing hole. 
     In order to provide a certain quantity of additive fluid quickly, the dosing gap can exhibit a certain opening area in the withdrawn position of the displaceable sleeve. This is greater than zero so that the quantity of the additive fluid determined by the dosing gap can flow in the direction of the raw material just by opening the valve device. Of course, there is also the possibility of varying this specified opening area depending on the type and quantity of the raw material. 
     In order to remove the valve element from its sealed seating on the valve-seat sleeve in a simple manner, an actuating plunger, which is in contact at one supporting end with the valve element, can be supported for displacement within the displaceable sleeve, spacer sleeve and valve-seat sleeve. The valve element is appropriately removed from the valve-seat sleeve by displacement of this actuating plunger and the corresponding valve device or the appropriate non-return valve is opened against the spring pressure. 
     With a simple embodiment the actuating plunger can be movably joined to the adjustment device by its moving end facing away from the support end. Complex movement transfer mechanisms between the actuating plunger and adjustment device are not necessary so that the dosage feed device is overall simply constructed. 
     In order, when moving the actuating plunger in the axial direction, to prevent the opening area of the dosing gap due to its analogous movement from also being immediately varied when initiating this movement, the movement end can protrude by a certain delay length from the first sleeve end of the displaceable sleeve. This means that first the actuating plunger is displaced by this delay length for opening the valve device and it is only after the delay length is pushed into the first sleeve end that a corresponding displacement of the displaceable sleeve also occurs and therefore too, a variation of the dosing gap. 
     There are various possibilities of externally feeding additive fluid to the dosage feed device. To achieve this, an appropriate device housing exhibits at least one hole through which the additive fluid is fed from an appropriate reservoir into the flow channel, controlled for quantity by the dosing gap and the valve device. 
     A simple feed is conceivable in which at least one additive fluid feed flows into an annular space of the flow channel between the guide sleeve and the support sleeve. 
     In order to fill the complete available interior space in the dosage feed device with additive fluid, at least one connecting hole can carry the support sleeve through in the direction of the first sleeve end. Through this connecting hole additive fluid is also fed appropriately into the space around the compression spring out of the annular space so that it also surrounds the first sleeve end and, for example, the movable end of the actuating plunger. 
     Various adjustment devices for the axial adjustment of the actuating plunger and displaceable sleeve are conceivable. These adjustment devices are characterised by a linear movement in the axial direction. However, to electrify the dosage feed device completely and to design it reliably and redundantly, without feed lines for a medium subject to pressure, the adjustment device can exhibit at least a spindle drive, a reduction gear, in particular in the form of a so-called harmonic drive, a helically toothed spur gear and a drive motor. The drive motor is an electric motor which acts on a drive shaft. This rotates a helically toothed spur wheel which engages another helically toothed spur wheel with a larger diameter. In this way an initial reduction of the rotational speed of the electric motor occurs. The spur wheel with the larger diameter transfers the rotational movement to the harmonic drive which, after further reduction, transfers the rotational movement to an appropriate part of the spindle drive. The spindle drive is then movably connected to the actuating plunger for its movement in the axial direction. 
     With a simple embodiment of such a spindle drive, it exhibits a rotationally rigid, but axially movable threaded spindle. The latter is joined appropriately to the actuating plunger, whereby there is also the possibility of arranging another actuating rod between both depending on the size of the dosage feed device in the axial direction. Preferably, a recirculating roller-bearing spindle is used as the spindle drive. 
     With regard to the harmonic drive, it should be noted that the spur wheel with the larger diameter is joined rotationally rigidly to a wave generator of the harmonic drive, whereby the rotation of the wave generator leads to an elastic deflection of an appropriately flexible toothed sleeve on two opposing ends of the toothed sleeve so that their outer teeth engage with suitable inner teeth of a rotationally rigid ring element. The appropriate movable connection to the spindle drive occurs by means of the flexible toothed sleeve. 
     The dosage feed device according to the invention can be provided both as an add-on or integrated part of a tree, for example, on the sea bed. There is also the possibility that the dosage feed device is designed such that it is constructed for remote control and can be replaced on the tree by a suitable vehicle or robot. For this purpose it is to be considered advantageous if an appropriate device housing of the dosage feed device exhibits a number of insertion bevels on its housing outer side. These insertion bevels aid in fitting the dosage feed device to a corresponding receptacle opening on the tree in which the dosage feed device is to be inserted at least partially. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, advantageous embodiments of the invention are explained in more detail based on the figures enclosed in the drawing. 
       The following are shown: 
         FIG. 1  a longitudinal section through a first embodiment of a dosage feed device according to the invention; 
         FIG. 2  a section along the line II-II in  FIG. 1 ; 
         FIG. 3  a graph for illustrating the dependence of the displacement of an actuating plunger and the dosage feed amount of the additive fluid, and 
         FIG. 4  a longitudinal section through a second embodiment of a dosage feed device according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It should be noted that an adjustment device  3  according to  FIG. 1  is also used in  FIG. 4  in analogous form and that with both embodiments according to  FIGS. 1 and 4 , the same parts are labelled with the same reference symbols and sometimes are only mentioned together with one of the figures or also only depicted in connection with one figure. 
     With the longitudinal section through a first embodiment of a dosage feed device  1  according to the invention according to  FIG. 1  the said dosage feed device exhibits an adjustment device  3 . The adjustment device  3  comprises various drive groups or gear groups. A rod-shaped intervening link  57  of the adjustment device  3  is releasably joined at one end  58  to a threaded spindle  45  of a spindle drive  39 . The threaded spindle  45  is supported for axial displacement in an associated spindle nut  44  as a further part of the threaded drive  39 . Normally, the intervening link  57  and the threaded spindle  45  are movably arranged in the axial direction, but are arranged rotationally rigidly within an appropriate device housing  48 . 
     The spindle nut  44  is partially inserted into a rotary sleeve  58  and attached to it releasably. The rotary sleeve is rotationally supported in a corresponding inner hole of the device housing  48  by means of oblique roller bearings. The rotation of the rotary sleeve  58  occurs by means of rotation of a flexible, approximately cup-shaped toothed sleeve  59  of a reduction gear  40  which is formed as a harmonic drive  41 . At its open end on its outer side the toothed sleeve  59  exhibits teeth which engage corresponding inner teeth of a fixed ring element  60 . Within the toothed sleeve  59  a wave generator  61  is arranged as a further part of the harmonic drive  41 . This in each case widens oppositely located sections of the toothed sleeve so that its corresponding outer teeth engage the inner teeth of the ring element  60 . 
     The wave generator  61  is rotationally rigidly joined to a first spur wheel  53  of a helically toothed spur gear  42 . Corresponding helical teeth on the first spur wheel  53  engage helical teeth on a second spur wheel  54 , whereby the second spur wheel  54  is arranged on a drive shaft  62  on which two motors  43  transfer their driving force. 
     There is also the possibility of arranging a further second spur wheel with associated drive shaft  62  and motors  43  also in the empty space  55 , refer to  FIG. 2 , or of arranging more than two second spur wheels with appropriately associated parts in the circumferential direction of the first spur wheel  53  in the device housing  48 . 
     The threaded spindle  45  exhibits an inner hole on its side facing away from the intervening link  57  and a code carrier  46  of a position sensor  47  is at least partially inserted into the said inner hole and is releasably attached there. The code carrier  46  moves together with the threaded spindle  45  so that by detecting the movement of the code carrier  46 , conclusions can be drawn about the movement of the threaded spindle  45 , intervening link  57  and the displaceable sleeve  12  which is moved by it, refer to the other versions. The detection of the movement of the code carrier  46  occurs using appropriate sensor elements, which scan position-specific patterns on the code carrier  46 , whereby these sensor elements are arranged in an end sleeve  56  of the corresponding position sensor  47 . 
     The device housing  48  in the embodiment according to  FIG. 1  exhibits on its housing outer side  52  a row of insertion bevels  49 , which border a stepwise reducing cross-section of the device housing  48  in the direction to the left in  FIG. 1 . These insertion bevels act as insertion aids for the dosage feed device  1  when it is employed using a remotely controlled device, such as a remotely controlled vehicle, etc. in the area of a tree, for example on the sea bed. In this way the dosage feed device  1  can be replaced easily by remote control. 
     The appropriate embodiment according to  FIG. 4  is mounted directly on the tree, whereby it can be sited together with the tree at the application location or it can be removed from there. 
     The actual dosage feed of an additive fluid  2  occurs at the end of the device housing  48  positioned to the left in  FIG. 1 . Here, it exhibits a discharge opening  63  through which the additive fluid  2  can be dosed into a dosage feed line  50 . The appropriate raw material, such as the crude oil or natural gas produced, flows along this dosage feed line  50 . 
     For the sake of simplicity appropriate feed lines for the additive fluid  2  are not illustrated in  FIGS. 1 and 4 . The dosing of the additive fluid  2  occurs by adjusting a dosing cone  9  in the axial direction, whereby the dosing cone  9  is part of a displaceable sleeve  12 . Between the dosing cone  9  and a counter element  10  formed as a guide sleeve  13  an appropriate dosing gap  15  is formed, refer also to  FIG. 4 , which exhibits different opening areas  8  depending on the adjustment of the displaceable sleeve  12  in the axial direction. 
     Within the displaceable sleeve  12  an actuating plunger  32  is movably supported in the axial direction. It is in contact at one end with the intervening link  57  or is movably joined and in contact at its opposite end with a valve element  24  of a valve device  7 . The valve device  7  is formed as a non-return valve  26 . 
     With regard to the other details of the dosage feed device reference is made to  FIG. 4 . 
       FIG. 2  shows a section along the line II-II, whereby  FIG. 1  corresponds to a section along the line I-I from  FIG. 2 . In  FIG. 2  in particular the arrangement of the first and second spur wheels  53 ,  54  of the helically toothed spur gear can be seen. The end sleeve  56 , in which the code carrier  46  is movably supported in the longitudinal direction is situated centrally in the first spur wheel  53 . 
     In the circumferential direction of the first spur wheel  53 , on one hand, the second spur wheel  54  is arranged as is also the empty space  55  for the further arrangement of a second spur wheel. Further such empty spaces  55  with appropriate second spur wheels, drive shafts, motors and similar equipment are possible, refer to  FIG. 1 . 
     In  FIG. 3  a graph shows the dependence of a displacement of the intervening link  57  or the threaded spindle  45  in the range from 0 to approx. 100% and a corresponding quantity of dosed additive fluid, whereby the corresponding dosage amount is set in relation to the quantity of raw material to which the additive fluid is dosed. Generally, it has been found that approximately 3% of additive fluid or inhibitor is sufficient, whereby if necessary, the amount is increased to 4%. According to the invention, there is the possibility of adding the 3% amount of the additive fluid to the raw material with just a very slight adjustment displacement (1% referred to the complete adjustment displacement) of the threaded spindle  45  and corresponding intervening link  57 , whereby this occurs by adjustment of the valve element  24  by means of the actuating plunger  32 . The 3% amount is defined by the opening area of the dosing gap  5 . If a further adjustment of the threaded spindle  45  occurs in the axial direction (refer to the range between 1% and 100% on the horizontal axis in  FIG. 3 ), then, refer to the description concerning  FIG. 4 , the opening area  8  of the dosing gap  5  is gradually increased, whereby the dosed amount of the additive fluid is then increased from 3% to 4% along this relatively long adjustment displacement. 
     In  FIG. 4  a longitudinal section according to  FIG. 1  is illustrated without the corresponding device housing  48  and adjustment device  3 . 
     The displaceable sleeve  12  exhibits apart from the end section  11 , in which the dosing cone  9  is formed, at least one further guide section  14 , along which the displaceable sleeve  12  is supported in a supporting sleeve  15  movable in the axial direction. The movable support occurs between an extended position  16 , refer to the dashed representation of a support ring  21 , and a withdrawn position  17  illustrated in  FIG. 4 , refer here also to the corresponding arrangement of the support ring  21 . For defining the withdrawn position  17 , the displaceable sleeve  12  exhibits on its outer side an annular stop  18  which is in contact with the support sleeve  15  in the withdrawn position  17 . 
     A compression spring  20 , which exerts a force on the displaceable sleeve  12  in the direction of the withdrawn position  17 , is supported between the supporting sleeve  15  and the support ring  21  arranged on a first sleeve end  19  of the displaceable sleeve  12 . Between the dosing cone  9  and the essentially cylindrical guide sleeve  13  as counter element  10 , the dosing gap  5  is formed which exhibits a defined opening area  8  in the withdrawn position  17  at its discharge end positioned downstream in the fluid flow direction  6 . This opening area  8  is used for defining the 3% amount according to  FIG. 3 . 
     The guide sleeve  13  is supported in an appropriate receptacle on the support sleeve  15  and a spacer sleeve  28  is arranged between the guide sleeve  13  and a valve-seat sleeve  22 . Both the spacer sleeve  28  and the valve-seat sleeve  22  border in their interiors an appropriate flow channel  23  for additive fluid  2 . 
     At its end facing the valve device  4 , the valve-seat sleeve  22  exhibits a circular shaped opening with an opening edge  27  with which the essentially spherical valve element  24  is in sealed contact in the valve-closed position  25  according to  FIG. 4 . The valve element  54  is arranged in an element receptacle  29  of the non-return valve  26 , whereby this element receptacle  29  is subjected at its end facing the discharge opening  63  to a force from a compression spring  64  in the direction of the valve-closed position  25 . 
     Between the element receptacle  29  and an inner side  30  of an appropriate housing hole  31 , in which the non-return valve  26  is positioned, at least a fluid opening  51  is formed through which additive fluid  2  flows in the direction of the discharge opening  63  when the non-return valve is open. 
     There is the possibility of arranging one or many such fluid openings  51 . 
     The actuating plunger  32  is movably supported in the axial direction within the valve-seat sleeve  22 , the spacer sleeve  28  and the displaceable sleeve  12 . It is in contact with the valve element  24  with its support end  33  allocated to the non-return valve  26 . With its other movable end  34  it is in contact with or movably connected to the intervening link  57 . In the valve-closed position  25  the actuating plunger  32  at its end section in the region of the movable end  34  protrudes from the first sleeve end  19  of the displaceable sleeve  12  by a certain delay length  35 . When the intervening link  57  moves due to appropriate movement of the threaded spindle  45  in the axial direction, the actuating plunger  32  is first displaced without, due to the appropriate delay length  35 , the displaceable sleeve  12  being displaced. Through this first displacement of the actuating plunger  32  the valve element  24  is moved out of the valve-closed position  25  by the support end  33  so that it is no longer in sealing contact at the opening edge  27 . Through this movement of the valve element  24 , the non-return valve  26  is opened and the amount of additive fluid  2  determined by the opening area  8  of the dosing cone  9  in the withdrawn position  17  of the displaceable sleeve  12  flows through the valve-seat sleeve  22  and fluid opening  51  in the direction of the discharge opening  63  and finally into the dosage feed line  50 . Here, mixing with the produced raw material occurs. 
     With further movement of the intervening link  57  through further actuation of the adjustment device  3 , refer also to  FIG. 1 , contact with the first sleeve end  19  of the displaceable sleeve  12  finally occurs together with its corresponding displacement in the axial direction in the direction of the discharge opening  63 . Consequently the dosing cone  9  is also displaced relative to the guide sleeve  13 , whereby the opening area  8  is enlarged. If the displaceable sleeve  12  is positioned in the extended position  16 , the opening area  8  of the dosing gap  5  is enlarged so far that the 4% amount of the additive fluid according to  FIG. 3  enters the dosage feed line  50  via the discharge opening  63 . However, this increase in the additive fluid amount occurs only if required and only if the 3% amount is not sufficient. 
     With the failure of the adjustment device  3 , automatic closure of the dosage feed device  1  occurs due to the spring pressure on the displaceable sleeve  12  in the direction of the withdrawn position  17  as well as the spring pressure of the non-return valve  26  in the direction of the valve-closed position  25 . 
     According to the invention, the non-return valve  26  as a valve device  7 , the valve-seat sleeve  22  and the displaceable sleeve  12  form a dosing element  4  with the dosing cone  9  and corresponding dosing gap  5 . 
     The feed of the additive fluid  2  to the dosage feed device  1  occurs in an appropriate annular space  37  between the guide sleeve  13  and support sleeve  15 , whereby appropriate feed holes or additive fluid guides  36  can extend radially outwards from the annular space at several points. In order to be able to feed additive fluid from the annular space  37  also in the direction of the first sleeve end  19  with the compression spring  20 , the support sleeve  15  exhibits at least one connecting hole  38 . 
     With regard to the embodiment according to  FIG. 1  it is again pointed out that the functioning principle of the dosage feed device is according to the embodiment in  FIG. 4 , whereby analogously the adjustment device  3  according to  FIG. 1  is used in the embodiment according to  FIG. 4 .