APPARATUS AND METHOD FOR INVESTIGATING NAPHTHA REFORMING PROCESSES

Abstract

An apparatus and a method are used for investigating the naphtha reforming process in catalyst test devices with reactors arranged in parallel. The apparatus has a plurality of reactors arranged in parallel with reaction chambers (R1, R2, . . . ), a product fluid supply, a process control, and at least one analysis unit. Each individual reactor has an outlet line for the product fluid stream, wherein the analysis unit is operatively connected to each outlet line for the product fluid stream and the apparatus is functionally connected to the control of the apparatus. In carrying out the method, naphtha-containing reactant fluid streams are brought into contact with catalysts in the individual reactors and the product fluid streams are subsequently supplied to the online analysis unit from the respective outlet lines of the individual reactors and analyzed. Using the evaluation of the online analytical characterization data, the process parameters of the respective reactor unit are adapted. The process steps of analytical characterization, evaluation, and adaptation of process parameters are repeated for the duration of the investigation.

Claims

1. An apparatus for investigating naphtha reforming, wherein the apparatus comprises: a plurality of reactors arranged in parallel with reaction chambers (R1, R2, . . . ), a product fluid supply common to one or a plurality of these reactors, a process control, and an analysis unit, wherein each individual reactor has an outlet line for the product fluid stream, wherein the analysis unit is operatively connected to each outlet line for the product flow unit, and the analysis unit is functionally connected to the control of the apparatus, and wherein the analysis unit is suitable for analysis of a gaseous product fluid stream, and the analysis unit, together with the process control, allows the determination and optimization of an octane number in the reactors arranged in parallel.

2. The apparatus as claimed in claim 1, wherein the analysis unit is an online analysis unit.

3. The apparatus as claimed in claim 1, wherein the reactor is a tubular reactor.

4. The apparatus as claimed in claim 1, wherein each reactor is equipped with an individually controllable heating device.

5. The apparatus as claimed in claim 1, wherein the apparatus has a number of 2 to 40 reactors arranged in parallel.

6. The apparatus as claimed in claim 1, wherein the individual reactors have a catalyst capacity in the range of 0.5 to 200 cm.sup.3.

7. The apparatus as claimed in claim 1, wherein a temperature sensor is arranged in parallel in the interior of at least one of the reactors.

8. The apparatus as claimed in claim 1, wherein the outlet lines of the individual reactors are connected to a repressurization gas and pressurization gas device.

9. The apparatus as claimed in claim 1, wherein the outlet lines of the individual reactors are equipped with membrane valves and the pressure inside the reactors is controlled by adjusting the membrane valve.

10. A method for investigating naphtha reforming using an apparatus as claimed in claim 1, wherein a naphtha-containing reactant fluid stream containing at least one hydrocarbon from the group with 5 to 14 carbon atoms, and hydrogen with a hydrogen content in the range of 0.5-60 vol. % is supplied to the individual reactors R1, R2, . . . , brought into contact in the respective reactors with a catalyst at a temperature in the range of 100° C. to 600° C., and converted to one product fluid stream each, and this product fluid stream is subsequently supplied to an outlet line, wherein the method comprises: (i) analytically characterizing the individual product fluid streams by an analysis unit, wherein the analysis relates to quantification of one or a plurality of components, (ii) comparing a result value of quantitation with a set value, wherein the comparison comprises the storage of an evaluation model, (iii) adapting a process parameter that relates to the reaction process of the respective reactor from the outlet line of which the product fluid stream was analyzed, and repeating the process steps (i) through (iii) by analyzing the product fluid stream that is discharged from the respective outlet lines.

11. The method for investigating naphtha reforming as claimed in claim 10, wherein the product fluid stream contains less than 1% of condensed product fluid.

12. The method for investigating naphtha reforming as claimed in claim 10, wherein the process parameters are pressure in one of the reactors, temperature of a reactor heater, and/or flow rate of the reactant fluid stream of a feed supply.

13. The method for investigating naphtha reforming as claimed in claim 10, wherein the duration of the analytical characterization is in a range of 0.1 min to 300 min.

14. The method for investigating naphtha reforming as claimed in claim 10, wherein the method is carried out over a duration of 24 h to 3000 h.

15. The method for investigating naphtha reforming as claimed in claim 10, wherein the evaluation model relates to calculation of the octane number and the method is such that adaptation of the process parameters is carried out so that the octane number of the reformate in the product fluid stream has a predetermined target value, wherein the target value of the octane number is kept constant for the duration of the method.

16. The method for investigating naphtha reforming as claimed in claim 10, wherein bringing into contact of the naphtha-containing reactant fluid stream is carried out at a pressure in the range of 1.2 to 100 bar.

17. The method for investigating naphtha reforming as claimed in claim 10, wherein the naphtha reforming is carried out for optimization of the process conditions.

18. The method for investigating naphtha reforming as claimed in claim 10, wherein testing of the ageing behavior of catalysts is carried out under conditions equivalent to those of an industrial reforming facility.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0062] FIG. 1 shows an example of a diagram of the method according to the invention and of the control loop, wherein an online analytical characterization of the product fluid stream from an outlet is first carried out, and at least one result value, and preferably a plurality thereof, is compared to at least one set value, and preferably a plurality thereof. A data analysis is carried out by means of an evaluation model, with adaptation of process parameters being conducted. The control loop is repeated. The octane number in the product fluid stream is preferably kept constant for the duration of the catalytic test investigation by adapting the temperature of the individual reactors.

[0063] FIG. 2 shows a schematic diagram of an apparatus with four reactors arranged in parallel, which are equipped with an online analysis unit, in which the analysis unit is operatively connected to a partial stream line of the outlet line 1.

[0064] FIG. 3 shows in the upper part of the y axis a schematic diagram of the octane number values (which are kept constant while the temperatures of the different catalysts are built into three reactors arranged in parallel), with the measurements being tracked over a period of 10 hours. The tracking of the temperature of the respective reactor heater for the respective catalysts is given in the lower part of the y axis. The x axis represents this time period required in order to keep the octane number of the C5+ hydrocarbons at a constant level.

[0065] FIG. 4 shows a diagram of a controller that is coupled to a system. “System” here refers to a parallel reactor apparatus. The controller receives time-dependent values from the product fluid streams of the individual lines and adapts a process parameter based thereon.

[0066] FIG. 5 shows an overview of a control circuit that is a component of a catalyst test device. According to the method of the invention, the control circuit is a component of an apparatus with reactors arranged in parallel.

[0067] FIG. 6 shows an overview of a control circuit in a process sequence, wherein subdivision is carried out here between process 1 and process 2, which refer to two different reactor units of a catalyst test device respectively.

[0068] In all of the embodiments shown in FIGS. 4 through 6, the coupling of the process control relates to the connection with a parallel reactor apparatus.

[0069] The term “system” as used herein has no limiting effect, and refers to any arrangement of parallel reactors. The term “process” in FIG. 5 also refers to the method in combination with reactors arranged in parallel.

[0070] The number of reactors arranged in parallel is limited by technical manageability with respect to the upper limits on the number of reactors. An aspect of the method according to the invention is the use of two or more parallel reactors, and preferably four or more reactors. The degree of parallelization affects the configuration of the method, as the analysis time in analysis of product fluids is subject to specified minimum times. In addition to the analysis time, other parameters also affect the duration. In particular, the analysis column should preferably be regenerated after analysis is carried out.

[0071] There are therefore processing times (durations) for the groups of process analytics, analysis evaluation, and data processing. The duration in these groups is preferably a maximum of half the reaction time of the system (Nyquist-Shannon sampling theorem).

[0072] The term “multiplexer” used herein refers to a selection valve by means of which the product fluid streams of the respective reactors are switched on the analysis device sequentially in time (also referred to herein as being “multiplexed”). “Demultiplexing” of the controller means that the manipulated variable determined from the data is assigned to the reactor—and the process taking place in the reactor—that originally provided these data. It can be seen from this that the multiplexers and demultiplexers must occupy the same number of positions.

[0073] In the following, individual process steps of the method according to the invention, as shown in FIGS. 1, 5 and 6, are explained in further detail:

1. A multicomponent mixture of an outlet line of a reactor is separated by means of an online analysis unit into its individual components.
2. The separated individual components show more or less pronounced differences with respect to the retention times, which are connected with time trends.
a. The analytical evaluation is preferably connected with a grouping of analysis data according to boiling ranges, and the result of this evaluation is preferably used for determination of the octane number. Data compression to an individual value is particularly preferred in this case. It is necessary for the actual controller to be supplied only with a time-dependent input variable. Moreover, the data compression preferably takes place in a model-based manner. In connection with the method according to the invention, the model consists of compression of the analytical characterization data, preferably determined by means of online gas chromatography, to an octane number. Moreover, it is also conceivable for the analytical characterization to take place by means of IR spectroscopy.
3. The controller is an element of the apparatus that reacts to a parameter in a time-dependent manner.
a. In the specific case, the controller in particular:
i. is programatically represented (is an algorithm)
ii. is configured as an interval-controlled search and approximation algorithm.
iii. Alternatives: Simplex search algorithm, other search algorithms are also included in the present invention.

[0074] By means of the process analytics, in the case of chromatographic methods, images of the processes are produced in a time-discrete manner. At specified intervals, i.e. the sampling frequency, individual samples are taken of the substance mixtures (i.e. of the reformates) coming from the respective reactor.

[0075] The substance mixtures are analyzed, i.e. decomposed into their components. In naphtha reforming and the method according to the invention, it is particularly preferred to carry out a gas chromatographic analysis at this point. The gas chromatographic analysis can be considered to be incomplete chromatography, as the substance mixture is broken down into groups whose mutual demarcation is carried out by means of a characteristic known substance.

[0076] A part of the method according to the invention is therefore that a plurality of time trends is compressed to a single time trend. The actual value of the octane number is preferably entered into the controller (specifically as function x=octane number(t)). Instead of the term octane number, one can also use the term research octane number, abbreviated as RON.

[0077] A controller within the meaning of the present invention can process exactly one input variable. For this reason, if the system to be controlled yields a plurality of actual values, these must be condensed to a single time-dependent variable.

[0078] A controller can control exactly one system. In this case, the response of the controller (manipulated variable) can be distributed among a plurality of actuators and thus a plurality of influencing possibilities. For example, the temperature and the flow of a reactor can be switched to the same controller output and thus the same manipulated variable. The system then responds to all influencing variables simultaneously.

[0079] Two or more controllers are preferably used to influence the temperature of a reactor. In this case there should preferably be the same number of systems as controllers (thermosensor (1); controller (2); actuator (3); heating element (4); thermosensor (1)). In order for the control(s) to function, one must ensure that the mutual influence of the controllers on one another is sufficiently small. If a particular threshold for mutual influence is exceeded, the systems may begin to vibrate. As a rule, these vibrations are undesirable, as critical operating states may be reached.

EXAMPLES

[0080] In order to illustrate the method according to the invention, a test run was carried out with five different catalysts under the conditions of naphtha reforming. Industrially manufactured catalysts were used, specifically approx. 9 g of catalyst for each reactor. The duration of the investigation was 200 hours, with the results shown in FIG. 3 being a section of a time range of 10 hours. The individual experiments were carried out such that the octane number was kept constant, which can be seen in the upper part of FIG. 3. The temperature of the individual reactors was constantly increased in order to compensate for the loss of activity seen in connection with catalyst ageing. On average, the temperature over the time interval of 200 hours was increased each time by 1.5 to 5° C. in order to keep the octane number of the product fluid stream in a constant range. The measurement values for the octane number show a standard deviation of ±0.3. It should be noted that this is an extremely small standard deviation that has not been published in the literature in this manner with laboratory equipment. The high accuracy is of great significance with respect to the technical reliability of the data achieved by means of the method according to the invention.

LIST OF REFERENCE NUMBERS

[0081] 1 Reactor 1 [0082] 1iv Reactor 4 [0083] 2 Outlet line connected to reactor 1 [0084] 2iv Outlet line connected to reactor 4 [0085] 3 Partial stream line [0086] 4 Online analysis unit [0087] 5 Process control [0088] 6 Reactor heater for reactor 1 [0089] 6iv Reactor heater for reactor 4 [0090] 7 Connection of process control to reactor heater 1