PROCESS FOR OPERATING A PLANT FACILITY DURING CATALYST REGENERATION

Abstract

The present invention provides a process of conducting catalyst regeneration in a plant facility, comprising; providing a plant facility with a unit area operating within battery limits; wherein the battery limits of the unit area are configured to receive a feed material; receiving the feed material into the battery limits and flowing the feed material within the unit area of the plant facility through a plurality of parallel flow paths in a plurality of reactor trains wherein; each reactor train comprises at least one reactor; and at least one reactor in each reactor train is charged with a catalyst; isolating in at isolation step at least one, but not all, of the plurality of parallel flow paths to provide at least one isolated reactor train and remaining on-line reactor trains; regenerating in a regeneration step the catalyst in the at least one reactor in the at least one isolated reactor train; wherein during the regeneration step the feed material flows through the parallel flow paths supplied from the battery limits and accepted for processing in the plant facility is approximately constant before and during the isolation step.

Claims

1. A process for operating a plant facility during catalyst regeneration, comprising; providing a plant facility with a unit area operating within battery limits; wherein the battery limits of the unit area are configured to receive a feed material; receiving the feed material into the battery limits and flowing the feed material within the unit area of the plant facility through a plurality of parallel flow paths in a plurality of reactor trains wherein; each reactor train comprises at least one reactor; and at least one reactor in each reactor train is charged with a catalyst; isolating in an isolation step at least one, but not all, of the plurality of parallel flow paths to provide at least one isolated reactor train and remaining on-line reactor trains; regenerating in a regeneration step the catalyst in the at least one reactor in the at least one isolated reactor train; wherein during the regeneration step the feed material flows through the parallel flow paths in the remaining on-line reactor trains; wherein the volume of feed material flowing through the plurality of parallel flow paths supplied from the battery limits and accepted for processing in the plant facility is approximately constant, varying by not more than 10%, before and during the isolation step.

2. The process according to claim 1 wherein the feed material is a mixture.

3. The process according to claim 1 or claim 2 wherein the feed material is a gas.

4. The process according to any one of claims 1 to 3 wherein the at least one reactor is a microstructure or microchannel reactor.

5. The process according to claim 4 wherein each reactor is a microchannel reactor.

6. The process according to any one of claims 1 to 5 wherein the number of reactor trains is at least two, or at least three, or at least four, or at least five.

7. The process according to any one of claims 1 to 6 wherein the plurality of reactor trains comprises at least two reactors, or at least three reactors, or at least four reactors.

8. The process according to any one of claims 1 to 7 wherein the at least one reactor is a Fischer-Tropsch reactor.

9. The process according to any one of claims 1 to 8 wherein the volume of the feed material flowing through the plurality of parallel flow paths before and during the isolation step does not vary by more than 7% or by more than 5%.

10. The process according to any one of claims 1 to 9 wherein the feed material comprises carbon monoxide and hydrogen.

11. The process according to any one of claims 1 to 10 wherein the feed material is a synthesis gas generated by gasifying biomass and/or municipal or solid waste.

12. The process according to any one of claims 1 to 11 wherein the regeneration of the catalyst takes place in situ in the isolated reactor train.

13. The process according to any one of claims 1 to 12 wherein the at least one isolated reactor train is offline for a period from about 3 days to about 14 days, or from about 4 days to about 12 days, or from about 5 days to about 10 days.

14. The process according to claim 13 wherein the at least one isolated reactor train is offline for a period of about 7 days.

15. The process according to any one of claims 1 to 14 wherein the catalyst is a metal-based catalyst, such as a cobalt or iron-containing catalyst.

16. The process according to claim 15 wherein the metal-based catalyst is a Fischer-Tropsch catalyst.

17. The process according to any one of claims 1 to 16 wherein the process is absent of flaring feedstock and/or turning down upstream units.

18. The process according to any one of claims 1 to 17 wherein the unit area of the plant facility is a Fischer-Tropsch island.

19. A plant facility for conducting during catalyst regeneration a chemical or biochemical process according to any one of claims 1 to 18.

Description

EXAMPLES

[0120] Fresh synthesis gas was obtained from an upstream gasification island (see examples for specific fresh synthesis gas rate) and was supplied to a Fischer-Tropsch area comprising a plurality of reactor trains each comprising of at least one microchannel reactor. Multiple configurations of installed microchannel reactors were considered to assess its impact on the processing capability of the available syngas and the overall production from the facility.

[0121] Example 1 and Table 1 considers the installation of 1 microchannel reactor per reactor train and shows the impact on the overall facility production between normal operation and the case when 1 of the installed trains is in regeneration (regeneration mode).

[0122] Example 2 and Table 2 considers the installation of 2 microchannel reactors per reactor train and shows the impact on the overall facility production between normal operation and the case when 1 of the installed trains is in regeneration (regeneration mode).

[0123] Example 2 and Table 3 provides a similar assessment for the option of installing 3 microchannel reactors per reactor train.

[0124] The facility setup for the configurations represented by the maximum number of trains illustrated in Tables 1 to 3 are shown in FIGS. 1 to 3 respectively.

[0125] It will be apparent that whereas in these examples Train 2 is depicted as the single isolated train during regeneration, other Trains may instead (or as well) be isolated during regeneration; and that configurations of numbers of reactor trains, number of reactors per train, and the location and/or quantity of reactors and/or reactor trains being isolated during regeneration may be varied in accordance with this invention.

[0126] The quantity of synthesis gas feed assumed in Example 2 is approximately 5 times the feed of Example 1. It would therefore be clear to the skilled person that additional reactors and/or reactor trains will be necessary to process this increase in feed gas quantity. Therefore, a configuration with a disproportionally small number of reactor trains (for example, with two reactors) are not presented in Tables 2 and 3 of Example 2.

[0127] For the purposes of data reported in Tables 1 to 3, a periodic regeneration of each reactor train every 60 days is considered to reverse any effects of reversible poisoning for example, from reactive nitrogen species and those from normal deactivation mechanisms such as non-reactive carbon accumulation and mild oxidation. The reported production numbers are based on the average operating temperature for the reactor trains over a 2-year period.

[0128] During catalyst regeneration all microchannel reactors in the 1 reactor train (where catalyst regeneration is taking place) are assumed to be taken offline for a period of 7 days.

[0129] During regeneration, the catalyst undergoes a regeneration process comprising of wax removal, oxidation and reduction steps (WROR) and requires heat-up and cool-down of the catalyst bed, in a reactor, in each step.

[0130] In preparation for regeneration the synthesis gas is stopped in the offline reactor by lowering the temperature to approximately 170 C. and then the synthesis gas is cut off, resulting in an isolated reactor train. Once the reactor train scheduled for regeneration has been successfully isolated, it is ready for regeneration. The isolated reactor train is purged with hydrogen to establish the environment for wax removal step before initiating the heat up. Upon completion of the required high temperature holds, the reactor train is cooled to an appropriate transition temperature for the oxidation step. In the oxidation step, the reactors in the train are purged with nitrogen and the target level of oxygen is gradually established and heat up initiated. Upon completion of the required high temperature hold, the reactor train is cooled to an appropriate transition temperature for the reduction step. In the reduction step, the reactors in the train are purged with nitrogen and the target hydrogen environment is established and heat up initiated. Upon completion of the required high temperature hold, the reactor train is cooled to an appropriate transition temperature for the syngas re-introduction step.

[0131] Upon completion of the regeneration steps, the flow of synthesis gas is re-started and the isolated reactor train is integrated back into the plant facility.

[0132] The term turndown when used throughout the examples is to be construed as the theoretical expected turndown, for example, the results that the skilled person would expect of a conventional reactor.

[0133] The term actual when used throughout the examples is to be construed as the actual difference in production between catalyst regeneration mode (where one reactor train is offline) and normal operational mode, when a process and/or plant facility according to the present invention is employed.

[0134] The term production delta during regen is to be construed as a measure of the loss in production estimated as a difference in production levels in normal operation and when one train is in regeneration relative to the production levels in normal operation.

Example 1

[0135] Fresh synthesis gas was obtained from an upstream gasification island at the rate of 460 kmol/hr (with a H2:CO molar ratio of 2.00 and approximately 8 mol % inerts) and was supplied to a Fischer-Tropsch area comprising a plurality of reactor trains each comprising of at least one microchannel reactor. The rest of the process is as described above.

[0136] Table 1 shows the outcomes of installing 1 to 4 reactor trains (each with 1 microchannel reactor) in the unit area for processing the available syngas feed. In all the cases, except the case of 1 reactor train of 1 microchannel reactor, the unit area is able to accept 100% of the available fresh syngas feed during both normal operation and regeneration modes.

TABLE-US-00001 TABLE 1 Configuration 1: One microchannel Fischer-Tropsch reactor per reactor train Turndown Actual Turndown Actual Turndown Actual Turndown Actual 100.0% N/A 50.0% 24.8% 33.3% 2.3% 25.0% 0.6% Production delta during Regen Normal Regen Normal Regen Normal Regen Normal Regen Number of reactor trains online 1 0 2 1 3 2 4 3 Per-pass conversion 70.0% 0.0% 70.0% 70.0% 70.0% 70.0% 70.0% 70.0% Overall conversion 70% 0.0% 90.2% 70.0% 91.9% 90.9% 92.7% 92.2% R/F (internal recycle/fresh feed molar 0.0 0.00 0.50 0.00 0.59 0.53 0.64 0.61 ratio) Total liquids, BPD 224 0 298 224 310 303 314 312 Time average, BPD 200 282 308 313

[0137] In the case where there is only 1 reactor train of 1 microchannel reactor when 1 reactor train is taken offline for regeneration there are no available reactor trains to accept synthesis gas. Consequently, the upstream units would have to be shut down or 100% of the gas would have to be flared. The case of one reactor train of 1 microchannel reactor is therefore not an embodiment of the present invention.

[0138] In the case of 2 reactor trains of 1 microchannel reactor each, when 1 reactor train is taken offline for regeneration, the expected turndown for a conventional facility is or 50%. In a conventional facility, for example a fixed bed reactor or a slurry bubble column reactor, catalyst regeneration would typically involve the turndown of upstream units to reduce the intake of available synthesis gas. This is required in conventional facilities to control the increase in temperature that would otherwise occur due to the added reaction heat load and potentially lead to unstable operation and poor product selectivity. Advantageously, the modular nature of the reactor configuration according to the present invention allows flexibility in design to maximise the utilisation of the synthesis gas available from upstream units. Therefore, when using the approach of the present invention, additional feed available is accepted by the remaining 1 (out of 2 installed) trains online (owing to the enhanced heat removal capacities of the microchannel reactor) and the actual reduction in production is only found to be approximately 25%.

[0139] Furthermore, as the third train is added, the production delta during regeneration decreases to about 2% owing to the ability to maintain increased production levels using the approach according to the invention compared to the turndown expectations. Further adding the fourth train reduces the production delta during regeneration to less than 1% but offers marginal improvement in the time-averaged production thereby reducing the value of the investment required. In practice, while it is possible to maintain the production at or near constant level irrespective of the mode of operation (for example, less than 1% production delta during regeneration), a less than 10% or less than 5% production difference based on the ability to process 100% of the available syngas would likely be acceptable.

Example 2

[0140] Fresh synthesis gas obtained from an upstream gasification island at the rate of 2236 kmol/hr (with a H2:CO molar ratio of 2.00 and approximately 8 mol % inerts) was supplied to a Fischer-Tropsch area comprising a plurality of reactor trains each comprising of a plurality of microchannel reactors. The rest of the process is as described above.

[0141] Table 2 shows the outcomes of installing 3 to 6 reactor trains (each with 2 microchannel reactors) while processing the said quantity of syngas feed. The arrangement of 3 or more installed reactor trains (each with 2 microchannel reactors) is able to accept 100% of the available fresh syngas load during normal operation and the regeneration modes.

[0142] Table 3 shows the outcomes of installing 3 to 5 reactor trains (each with 3 microchannel reactors) while processing the same quantity of syngas feed as exemplified in Table 2. In this instance as well, the arrangement of 3 or more installed reactor trains (each with 3 microchannel reactors) is able to accept 100% of the available fresh syngas load during normal operation and in regeneration mode. The inclusion of an extra microchannel reactor in each reactor train (compared to the case represented in Table 2 where there are 2 installed reactors per train) reduces the production delta during regen, as shown in Table 3.

[0143] In the case of 4 reactor trains of 2 microchannel reactors each, when 1 reactor train is taken offline for regeneration, the expected turndown for a conventional facility is or 25%. In a conventional facility, for example a fixed bed reactor or a slurry bubble column reactor, catalyst regeneration would typically involve the turndown of upstream units to reduce the intake of available synthesis gas. This is required in conventional facilities to control the increase in temperature that would otherwise occur due to the added reaction heat load and potentially lead to unstable operation and poor product selectivity. Advantageously, the modular nature of the reactor configuration according to the present invention allows flexibility in design to maximise the utilisation of the synthesis gas available from upstream units. Therefore, when using the approach of the present invention, additional feed available is accepted by the remaining 3 (out of 4 installed) trains online (owing to the enhanced heat removal capacities of the microchannel reactor) and the actual reduction in production is only found to be 7%.

[0144] Furthermore, as the number of reactor trains is increased, the production delta during regen decreases owing to the ability to maintain increased production levels using the approach according to the invention compared to the turndown expectations.

[0145] While it is possible to maintain the production at a near constant level irrespective of the mode of operation (for example, less than 1% production delta during regen), a less than 10% or less than 5% production difference based on the ability to process 100% of the available syngas may be acceptable in practice.

TABLE-US-00002 TABLE 2 Configuration 2: Two microchannel Fischer-Tropsch reactors per reactor train Turndown Actual Turndown Actual Turndown Actual Turndown Actual 33% 16% 25% 7% 20% 4% 17% 1% Production delta during Regen Normal Regen Normal Regen Normal Regen Normal Regen Number of reactor trains online 3 2 4 3 5 4 6 5 Per-pass conversion 70.0% 70.0% 70.0% 70.0% 70.0% 70.0% 70.0% 70.0% Overall conversion 82.5% 70.0% 87.7% 82.5% 90.4% 88.0% 91.4% 90.7% R/F (internal recycle/fresh 0.25 0.00 0.40 0.25 0.51 0.41 0.56 0.52 feed molar ratio) Total liquids, BPD 1265 1059 1386 1288 1456 1402 1489 1469 Time average, BPD 1200 1345 1428 1476

TABLE-US-00003 TABLE 3 Configuration 3: Three microchannel Fischer-Tropsch reactors per reactor train Turndown Actual Turndown Actual Turndown Actual 33% 9% 25% 3% 20% 2% Production delta during Regen Normal Regen Normal Regen Normal Regen Number of trains online 3 2 4 3 5 4 Per-pass conversion 70.0% 70.0% 70.0% 70.0% 70.0% 70.0% Overall conversion 89.4% 82.6% 91.4% 89.5% 92.2% 91.4% R/F (internal recycle/fresh 0.47 0.25 0.56 0.47 0.61 0.56 feed molar ratio) Total liquids, BPD 1428 1294 1491 1440 1517 1494 Time average, BPD 1386 1469 1505

[0146] As can be seen when comparing Tables 2 and 3, the production delta during regen (i.e. difference in production between the normal and regeneration operational mode) decreases more rapidly as the number of microchannel reactors per reactor train increases. Additionally, as the number of reactor trains increases, the production delta during regens decreases owing to the ability to maintain increased production levels with an arrangement according to the present invention. This is exemplified in FIG. 4.

[0147] The longer the duration and higher the frequency of the regeneration process, the more relevant are the advantages of process according to the invention. Typically, as the catalyst deactivates, the reactor operating temperature is increased to maintain the conversion. A consequence of higher operating temperatures is a decrease in the favourable product make. Since regeneration can improve the activity of the catalyst and reverse the impact of deactivation, a high regeneration frequency may be desirable to maintain the catalyst in a higher activity state to maximize the production of favourable products. In these instances, the ability to maintain the production at target rates independent of the state of the catalyst is beneficial to maximize the value of the products from the facility.