DEVICE AND METHOD FOR THE PROVISION OF PRESSURIZED MEDIUM FOR INJECTION INTO A HIGH PRESSURE PROCESS

Abstract

A pump injection arrangement can inject a medium at least one process position into a high-pressure process, in particular at least two different pressure levels. The pump injection arrangement includes injection pump apparatuses for the medium and a regulating unit coupled to the injection pump apparatuses and configured for regulating the injection by at least two of the injection pump apparatuses. The pump injection arrangement is configured for synchronized regulation of the injection pump apparatuses with dependence on one another. At least two of the synchronously regulated injection pump apparatuses are double acting bidirectionally operating high-pressure pumps that are functionally coupled with at least single redundancy to the regulating unit such that pressure can be generated via at least two shafts and the pressurized medium can be made available for injection via a joint high-pressure conduit. In this way, advantageous pressure and pumping characteristics can be achieved.

Claims

1.-20. (canceled)

21. A high-pressure system comprising: a vessel configured for high pressure; a primary compressor; a secondary compressor; a high-pressure reactor; a high-pressure separator; a low-pressure separator; and a pump injection arrangement configured to inject a medium at least one of into the high-pressure reactor or into a high-pressure polymerization process upstream of the high-pressure reactor to at least two different pressure levels, wherein the pump injection arrangement comprises: injection pump apparatuses for the medium comprising olefins, substances having a double bond, alkenes, or propylene, wherein the injection pump apparatuses are coupled to at least one of the high-pressure reactor or to a high-pressure conduit section upstream of the high-pressure reactor, and a regulating unit that is coupled to the injection pump apparatuses and is configured to regulate injection by at least two of the injection pump apparatuses, wherein the pump injection arrangement is configured to synchronize regulation of the injection pump apparatuses with one another and to inject the medium at flow rates of greater than 150 liters per hour, wherein at least two of the injection pump apparatuses that are synchronously regulated are double acting bidirectionally operating high-pressure pumps that are functionally coupled with at least single redundancy to the regulating unit such that a pressure is generated via at least two shafts and such that the medium under pressure is made available for injection via a high-pressure conduit.

22. The high-pressure system of claim 21 wherein the injection pump apparatuses are synchronized with one another such that a phase offset of 180° of pistons of at least the double acting bidirectionally operating high-pressure pumps is set.

23. The high-pressure system of claim 21 wherein each double acting bidirectionally operating high-pressure pump includes a double acting hydraulic cylinder that is connected to two high-pressure heads to provide the high-pressure conduit.

24. The high-pressure system of claim 21 wherein the pump injection arrangement has a linear position transducer coupled to one or more shafts of the pump injection arrangement.

25. The high-pressure system of claim 21 wherein the injection pump apparatuses are functionally coupled in a closed regulating circuit, wherein the pump injection arrangement includes a proximity switch coupled to one or more shafts of the pump injection arrangement.

26. The high-pressure system of claim 21 wherein the pump injection arrangement comprises at least three of the injection pump apparatuses, wherein the at least three of the injection pump apparatuses are double acting high-pressure pumps that are functionally coupled with at least double redundancy to the regulating unit such that the pressure is generated via at least three shafts and such that the medium under pressure is provided for injection via the high-pressure conduit.

27. The high-pressure system of claim 26 wherein the at least three shafts are synchronized such that a phase offset of pistons of the injection pump apparatuses is set at 120° or less.

28. A method for controlling and/or regulating the pump injection arrangement of the high-pressure system of claim 21 during injection of a medium comprising comonomers, initiators, or modifiers at a process position of a high-pressure polymerization process comprising multistage pressure build-up and a high-pressure reaction, the method comprising: regulating the injection pump apparatuses in a synchronized manner with the regulating unit with dependence of the injection pump apparatuses on one another; operating at least two of the injection pump apparatuses as double acting bidirectionally operating high-pressure pumps; functionally regulating the at least two of the injection pump apparatuses with at least single redundancy such that a pressure is generated via at least two shafts and the medium under pressure is made available for injection via a high-pressure conduit; injecting the medium at flow rates of greater than 150 liters per hour, wherein at the flow rates of greater than 150 liters per hour the medium is injected exclusively by the double acting bidirectionally operating high-pressure pumps.

29. The method of claim 28 comprising either: regulating at least two of the injection pump apparatuses with a phase offset of 180° of pistons with dependence on one another; or setting a phase offset of pistons of the injection pump apparatuses at not more than 120°.

30. The method of claim 28 comprising providing the medium under pressure at the process position on a high-pressure conduit of all of the injection pump apparatuses regulated for the process position.

31. The method of claim 28 wherein the regulation is position-based on a basis of measured data of a linear position transducer coupled to one or more shafts of the pump injection arrangement.

32. The method of claim 28 wherein the regulation is performed in a closed regulating circuit.

33. The method of claim 28 wherein at least three of the injection pump apparatuses that are synchronously regulated are operated as double acting bidirectionally operating high-pressure pumps and are functionally regulated with at least double redundancy such that the pressure is generated via at least three shafts and such that the medium under pressure is provided for injection via the high-pressure conduit.

Description

DESCRIPTION OF FIGURES

[0049] Further features and advantages of the invention may be derived from the description of at least one embodiment with the aid of drawings, and also from the drawings themselves. In the case of reference symbols which are not explicitly described in relation to one figure, reference may be made to the other figures. The drawings show

[0050] FIG. 1 an illustrative flow diagram of a process to which the present invention can be applied;

[0051] FIG. 2 a sketch of the technical structure of a double acting pump;

[0052] FIG. 3A, 3B an illustration of the pressure characteristics which can be achieved when a plurality of pumps are connected compared to the pressure profile of an individual traditional double acting pump;

[0053] FIG. 4 a sketch of the technical structure of a phased pump, for example as can be used for injection of catalyst;

[0054] FIG. 5 a sketch of the technical structure of a double acting pump having an implemented open regulating circuit, for optional use or implementation in a pump injection arrangement according to the invention;

[0055] FIG. 6 a sketch of the technical structure of a double acting pump having an implemented closed regulating circuit, for use or implementation according to the invention in a pump injection arrangement;

[0056] FIG. 7 a sketch of the technical structure of a singly redundant pump injection arrangement according to the invention comprising double acting pumps, with two pump shafts and with an implemented open regulating circuit;

[0057] FIG. 8 a sketch of the technical structure of a doubly redundant pump injection arrangement according to the invention comprising double acting pumps, with three pump shafts and with an implemented open regulating circuit;

[0058] FIG. 9 an illustration of a regulating option of a doubly redundant pump injection arrangement according to the invention.

DETAILED DESCRIPTION OF THE FIGURES

[0059] FIG. 1 shows an illustrative high-pressure treatment process having a plurality of injection positions. A high-pressure system 1 comprises vessels 2 designed for high pressure, a primary compressor 3, a secondary compressor 4 (in particular hypercompressor), a reactor 5, a high-pressure separator 6 and a low-pressure separator 7. Process medium M, for example ethylene, is conveyed from the first vessel 2 via the compressors and the reactor and the separators to the second vessel 2, and is conveyed from the second vessel 2 back to the first vessel 2, with an internal return circuit from the high-pressure separator 6 also being provided before the hypercompressor 4. The process medium M is not the same as the injected medium.

[0060] An injection of medium is carried out, for example, at at least three process positions, in particular in each case by means of an individual pump injection arrangement, or optionally also by means of a single pump injection arrangement for at least two or more process positions. A pump arrangement according to the invention for building up the pressure can be realized for each of the injection steps S1, S2, S3 described below.

[0061] In a step S1, an injection of comonomers and modifiers, in particular, is carried out, especially to a first pressure level. In a step S2, an injection of comonomers, in particular, is carried out, especially to a second pressure level higher than the first pressure level, in particular downstream of all compressors of the process. This can, for example, be advantageous in the case of comonomers in the liquid phase, especially also for the purpose of minimizing the load on compressors. In a step S3, an injection of catalysts, in particular, is carried out, especially to the second pressure level or to a further even higher pressure level.

[0062] The steps S1, S2, S3 indicate by way of example the positions in the process where an injection can be necessary, in particular a high-pressure injection. In the following, the technology by means of which the respective (high-pressure) injection can preferably be carried out will be explained in more detail. A pressure monitoring and radial expansion steps can also be carried out here.

[0063] FIG. 2 shows by way of example the structure of a double acting bidirectionally operating high-pressure pump, in particular without implementation of regulation according to the invention. In a double acting hydraulic cylinder, a piston 16 acts on a shaft 15 which is connected to two high-pressure heads (plunger pumps).

[0064] In the graphs shown in FIG. 3A, 3B, the pressure [p] is in each case plotted against time [t].

[0065] FIG. 3A illustrates pressure pulsation when using a bidirectionally operating pump. This pulsation occurs, in particular, periodically during operation and is stronger or weaker, in terms of absolute value or percentage, depending on the quality of the pump. In FIG. 3A, a schematic illustration of a double acting pump is shown underneath the graph for the sake of completeness.

[0066] FIG. 3B shows pump characteristics or a pressure profile which can be realized by means of three unidirectional pumps connected to one another. Pressure pulses can be at least largely avoided. A respective pump is relieved by one of the further pumps as soon as the further pump has built up the desired pressure level to be maintained (intermittent operation without appreciable time overlap). In FIG. 3B, a schematic illustration of three single-acting phased pumps is shown underneath the graph for the sake of completeness.

[0067] FIG. 4 shows by way of example the structure of an arrangement of three unidirectionally operating high-pressure pumps. To regulate the interplay of the individual unidirectionally operating pumps, a regulator 8 is provided; each of the three pumps is coupled to the regulator 8. Advantages of this arrangement: advantageous pressure characteristics; good availability. However, this arrangement can become disadvantageous, especially above throughputs of greater than 150 liters per hour.

[0068] FIG. 5 shows a bidirectionally operating pump unit 11 having a regulator 8 which regulates the pump unit 11 in an open regulating loop. Proximity switches are provided on the shaft 15 on both sides of the cylinder. Advantages of this arrangement: high throughput, especially thanks to a comparatively large plunger size; proximity switches for switching over; movement regulation based on ratio of amounts or by means of a proportionality valve; switchover point in time able to be set quickly and promptly. It has been found that the arrangement shown in FIG. 5 can be optimized further.

[0069] FIG. 6 shows a bidirectionally operating pump unit 11 having a regulating unit 20a which regulates the pump unit 11 in a closed regulating loop. A linear position transducer and a closed PID regulating loop make a fast autonomously regulated switchover procedure possible. Advantages of this arrangement: optimized regulating properties, in particular also in the case of a system comprising further connected bidirectional pump units.

[0070] A double acting hydraulic cylinder, in which a piston 16 operates, is connected to two high-pressure heads (plunger pumps). A double acting high-pressure pump having a joint high-pressure conduit 14 is formed. A first control line 21 connects the regulating unit 20a to the appropriate components of the pump 11. The regulating unit 20a is configured for synchronizing a plurality of bidirectional pump units with a phase offset, in particular as a function of the number of the synchronized pump units.

[0071] Such a double acting pump 11 having a shaft 15 and in particular also having a displacement measuring system and proportional valve for the hydraulics can be implemented according to the invention in a phase offset-synchronized configuration which optionally has absolutely no phased flow pumps.

[0072] FIG. 7 shows a pump injection arrangement 10 as per a first embodiment having a control/regulating device 20 which regulates a first injection pump apparatus 11 and a second injection pump apparatus 12 in a matched fashion.

[0073] In this configuration as singly redundant pump injection arrangement 10 having two shafts 15, in each case provided by an injection pump apparatus 11, 12, advantageous synchronization in respect of phase offset can be realized with minimal engineering outlay. Two regulating circuits 21, 22 are synchronized by means of the regulating unit 20a by a phase offset of 180° being set. One of the shafts 15 switches over while the other shaft (or the corresponding piston 16) is located precisely in the middle (middle position), and vice versa: first piston 16 at the stop, second piston in the middle position. This two-shaft pump arrangement gives twice the volume flow compared to the single shaft arrangement. It has been found that this two-shaft pump arrangement can be operated at half speed for the volume flow of a single shaft arrangement. This not least also increases the operating life of the high-pressure components to a considerable extent. The two-shaft arrangement can optionally be operated using only one shaft, especially in the case of maintenance work/technical malfunctions.

[0074] Advantages of this arrangement: comparatively low speeds; comparatively small fluctuation or variation of the throughput volume; optionally doubled throughput rate at maximum operating load (maximum piston speed).

[0075] FIG. 8 shows a pump injection arrangement 10 according to a second embodiment having three injection pump apparatuses 11, 12, 13 coupled to one another by regulation (three head arrangement). The joint high-pressure conduit 14 is supplied by all three injection pump apparatuses.

[0076] In this configuration as doubly redundant pump injection arrangement 10 having three shafts 15, the advantages can be realized even more perceptibly, especially also in respect of operational reliability, compared to the arrangement having only two shafts. In particular, the three individual shafts 15 are in normal operation arranged with a phase offset of 120° or controlled/regulated via the corresponding regulating circuits 21, 22, 23 (first piston 16 at the stop, second piston ⅓ offset; third piston ⅔ offset). This pump injection arrangement 10 gives, for example, the same maximum high-pressure volume flow as a two-shaft pump injection arrangement. At a maximum volume flow, a travel speed reduced by ⅓ can be realized for each shaft 15. Each shaft travels at only ⅔ of its mechanically/technically possible maximum speed, which also ensures particularly gentle operation.

[0077] The arrangement shown in FIG. 8 enables the advantages of the invention to be ensured even more comprehensively, especially also in respect of operation having even lower pulsation, or also in respect of greater failure safety or additional maintenance options, as illustrated in FIG. 9: one of the three double acting pumps 11, 12, 13 can optionally be switched off or be decoupled from the pump injection arrangement 10 (here by way of example the middle injection pump apparatus 12).

[0078] If one of the shafts 15 fails for maintenance reasons or technical malfunctions, the two remaining shafts can be accelerated to the mechanically/technically possible speed and the phase offset can be brought to 180°. The volume flow of the total arrangement can thus be kept constant and pulsation is minimized even in out-of-the-ordinary situations. In other words: advantages in respect of standby properties can also be realized in addition to the advantages mentioned above in respect of FIG. 7.

LIST OF REFERENCE SYMBOLS

[0079] 1 High-pressure system [0080] 2 (High-pressure) vessel (buffer, collection vessel) [0081] 3 Primary compressor [0082] 4 Secondary compressor, in particular hypercompressor [0083] 5 Reactor [0084] 6 High-pressure separator [0085] 7 Low-pressure separator [0086] 8 Regulator [0087] 9 Double acting high-pressure pump, in particular unregulated [0088] 10 Pump injection arrangement [0089] 11 First injection pump apparatus, in particular double acting high-pressure pump [0090] 12 Second injection pump apparatus, in particular double acting high-pressure pump [0091] 13 Third injection pump apparatus, in particular double acting high-pressure pump [0092] 14 (Joint) high-pressure conduit, for injection [0093] 15 Individual pump shaft [0094] 16 Piston [0095] 20 Control/regulating device [0096] 20a Controller unit [0097] 21 First control line [0098] 22 Second control line [0099] 23 Third control line [0100] M Process medium, in particular ethylene [0101] S1 Step 1, in particular injection of comonomers and modifiers [0102] S2 Step 1, in particular injection of comonomers [0103] S3 Step 1, in particular injection of catalysts [0104] p Pressure [0105] t Time