CO CONVERSION CONTROL FOR MULTISTAGE FISCHER-TROPSCH SYNTHESES

Abstract

The present invention relates to methods for operating Fischer-Tropsch syntheses for the production of long-chain hydrocarbons and to plants for carrying out these processes, wherein the CO conversion is controlled and/or the catalyst deactivation is compensated.

Claims

1.-15. (canceled)

16. A method for operating a Fischer-Tropsch synthesis, wherein the method comprises: I) feeding a synthesis gas containing H.sub.2 and CO into a first fixed-bed synthesis reactor which comprises a first catalyst bed to form hydrocarbons by catalytic reaction, II) feeding a product stream leaving the first fixed-bed synthesis reactor and comprising hydrocarbons to a product separation to separate a fraction of hydrocarbons from the product stream, III) feeding a remaining fraction of the product stream, which comprises short chain and shorter chain hydrocarbons to a second fixed-bed synthesis reactor comprising a second catalyst bed to form long chain hydrocarbons by catalytic reaction, wherein synthesis gas is exclusively fed to the first fixed-bed synthesis reactor and furthermore, a weight volume flow of the synthesis gas introduced into the first fixed-bed synthesis reactor is adjusted to a value and kept constant at this value during the method, a molar H.sub.2:CO ratio in the synthesis gas is adjusted to a value of from 1.7:1 to 2.3:1, an inert gas content in the synthesis gas is from 0% to 40 vol. %, the same cobalt-based Fischer-Tropsch catalyst is used in both fixed-bed reactors, a weight ratio of catalyst in the first fixed-bed synthesis reactor to catalyst in the second fixed-bed synthesis reactor is set to be from 1.1:1 to 4.3:1, the first fixed-bed synthesis reactor is operated at a pressure of from 10 bar to 50 bar, and the second fixed-bed synthesis reactor is operated at a pressure from 10 bar to 50 bar, and wherein a reactor temperature is controlled to an equal value of from 180? C. to 250? C. in both synthesis reactors depending on a desired total CO conversion, which is between 40 and 90 mol %, and the control is such that a hydrogen conversion, considered over all stages, is at most 99 mol %.

17. The method of claim 16, wherein the product separation is a multi-stage product separation.

18. The method of claim 16, wherein water is additionally separated in the product separation.

19. The method of claim 16, wherein the molar ratio of H.sub.2 to CO in the synthesis gas is adjusted to a value of from 1.8:1 to 2.3:1.

20. The method of claim 16, wherein the molar ratio of H.sub.2 to CO in the synthesis gas is adjusted to a value of from 2.0:1 to 2.3:1.

21. The method of claim 16, wherein the molar ratio of H.sub.2 to CO in the synthesis gas is adjusted to a value of from 2.2:1 to 2.3:1.

22. The method of claim 16, wherein an inert gas content in the synthesis gas is selected from 0 vol. %, 5 vol. %, 10 vol. %, 15 vol. %, 20 vol. %, 25 vol. %, 30 vol. %, 35 vol. % and 40 vol. %.

23. The method of claim 16, wherein reactor temperatures in the first fixed-bed synthesis reactor and the second fixed-bed synthesis reactor are controlled to an equal value of from 200? C. to 240? C.

24. The method of claim 16, wherein reactor temperatures in the first fixed-bed synthesis reactor and the second fixed-bed synthesis reactor are controlled to an equal value of from 200? C. to 220? C.

25. The method of claim 16, wherein the first fixed-bed synthesis reactor is operated at a pressure of from 15 bar to 30 bar, and the second fixed-bed synthesis reactor is operated at a pressure of from 15 bar to 30 bar.

26. The method of claim 16, wherein the molar H.sub.2:CO ratio in the synthesis gas, the inert gas content in the synthesis gas, the weight ratio of the catalysts to each other, the pressure in the first fixed-bed synthesis reactor and the pressure in the second fixed-bed synthesis reactor are all kept constant.

27. The method of claim 16, wherein a product stream comprising hydrocarbons and leaving the second fixed-bed synthesis reactor is fed to a further product separation.

28. The method of claim 16, wherein one or both of the first and second fixed-bed synthesis reactors comprise two or more apparatuses connected in parallel.

29. The method of claim 16, wherein one or more further reaction stages comprising a fixed-bed synthesis reactor and a product separation are arranged serially downstream of the first and/or second reaction stage.

30. An installation, wherein the installation is suitable for carrying out the method of claim 16 and comprises: i) a first fixed-bed synthesis reactor comprising a cobalt-based Fischer-Tropsch catalyst, ii) a single- or multi-stage product separation arranged serially downstream of the first fixed-bed synthesis reactor and adapted to at least a) separate a fraction of hydrocarbons from a product stream leaving the first fixed-bed synthesis reactor, b) optionally, separate water in addition to the hydrocarbons, iii) a second fixed-bed synthesis reactor arranged serially downstream of the product separation and comprising the same catalyst as in the first fixed-bed synthesis reactor, and wherein the installation is configured such that synthesis gas addition is exclusively to the first fixed-bed synthesis reactor, a weight ratio of catalyst of first fixed-bed synthesis reactor to catalyst of second fixed-bed synthesis reactor being from 1.1:1 to 4.3:1.

31. The installation of claim 30, wherein the installation additionally comprises one or more of the following features: A) a further product separation arranged serially downstream of the second fixed-bed synthesis reactor, which is designed to separate a fraction of long-chain hydrocarbons from a product stream leaving the second fixed-bed synthesis reactor, B) each fixed-bed synthesis reactor comprises two or more apparatuses connected in parallel, C) one or more further reaction stages are arranged serially downstream of a first and/or second reaction stage and comprise a fixed-bed synthesis reactor and product separation.

32. A method for controlling the CO conversion in a multistage Fischer Tropsch syntheses in which synthesis gas is added only to a first synthesis reactor, to a value of from 40% to 90 mol %, wherein the method comprises continuous and simultaneous adjustment of reactor temperatures for all Fischer-Tropsch synthesis reactors to an equal value of from 180? C. and 250? C., a weight volume flow of the synthesis gas introduced into the first fixed-bed synthesis reactor being adjusted to a value and kept constant at this value during the process.

33. The method of claim 32, wherein the following parameters are set and kept constant during the synthesis process: molar H.sub.2:CO ratio in the synthesis gas of from 1.7:1 to 2.3:1, inert gas content in the synthesis gas from 0% and 40 vol. %, same cobalt-based Fischer-Tropsch catalyst in all reactors, weight ratio of amount of catalyst of first fixed-bed synthesis reactor to amount of catalyst of second fixed-bed synthesis reactor of from 1.2:1 to 4.3:1, pressure in the fixed-bed synthesis reactors 10 bar to 50 bar each, hydrogen conversion over all stages at most 99 mol %.

34. A method for the compensation of catalyst deactivation in a multistage continuously operating Fischer-Tropsch synthesis in which synthesis gas is added only to a first synthesis reactor, wherein the method comprises continuous and simultaneous adjustment of reactor temperatures for all Fischer-Tropsch synthesis reactors to an equal value of from 180? C. and 250? C., and setting a weight volume flow of the synthesis gas introduced into the first fixed-bed synthesis reactor to a value and keeping it constant at this value during the process.

35. The method of claim 34, wherein the following parameters are set and kept constant during the synthesis process: molar H.sub.2:CO ratio in the synthesis gas of from 1.7:1 to 2.3:1, inert gas content in the synthesis gas of from 0% to 40 vol. %, same cobalt-based Fischer-Tropsch catalyst in all reactors, weight ratio of amount of catalyst of first fixed-bed synthesis reactor to amount of catalyst of second fixed-bed synthesis reactor of from 1.2:1 to 4.3:1, pressure in the fixed-bed synthesis reactors 10 bar to 50 bar each, hydrogen conversion over all stages at most 99 mol %, CO conversion in each stage of from 40 and 90 mol %.

Description

DESCRIPTION OF THE FIGURES

[0134] The present invention is explained in more detail below with reference to the drawings. The drawings are not to be construed as limiting and are not to scale. The drawings are schematic and furthermore do not contain all the features that conventional devices have, but are reduced to the features that are essential for the present invention and its understanding, for example, screws, connections etc. are not shown or not shown in detail.

[0135] Identical reference signs indicate identical features in the figures, the description and the claims.

[0136] FIG. 1:

[0137] A synthesis gas stream comprising H.sub.2 and CO 11 is fed at a constant weight volume flow into a first fixed-bed synthesis reactor 1, in which H.sub.2 and CO are catalytically converted to hydrocarbons. A product stream 12 leaving the first fixed-bed synthesis reactor 1 is fed into a (first) separation device 2, in which a fraction of long-chain hydrocarbons is separated 2a. The remaining fractions, comprising essentially short and shorter chain hydrocarbons, CO, CO.sub.2 and H.sub.2, as well as possibly residues of H.sub.2O 13, are fed into a second fixed-bed synthesis reactor 3, and catalytically converted to long chain hydrocarbons (>C.sub.25) 3a.

[0138] FIG. 2:

[0139] A synthesis gas stream comprising H.sub.2 and CO 11 is fed at a constant weight volume flow into a first fixed-bed synthesis reactor 1, in which H.sub.2 and CO are catalytically converted to hydrocarbons. A product stream 12 leaving the first fixed-bed synthesis reactor 1 is fed into a (first) separation device 2, in which a fraction of long-chain hydrocarbons, as well as an aqueous fraction is separated 2a. The remaining fractions, comprising essentially short and shorter chain hydrocarbons, CO, CO.sub.2 and H.sub.2 13 are fed into a second fixed-bed synthesis reactor 3, and catalytically converted to essentially long chain hydrocarbons. A product stream 3a of the second fixed-bed synthesis reactor 3 is fed to a second product separation 21, in which the fraction of long chain hydrocarbons 21a is separated from the fraction comprising short and shorter chain hydrocarbons (C.sub.1-C.sub.24), CO, CO.sub.2 and H.sub.2, 21c as well as an aqueous fraction 21b. The aqueous fraction 21b can be combined with the aqueous fraction from the first product separation 2b. The fraction of long-chain hydrocarbons 21a separated by means of the second product separation is combined with the fraction of long-chain hydrocarbons 2a from the first product separation.

LIST OF REFERENCE SIGNS

[0140] 1 first fixed-bed synthesis reactor [0141] 11 synthesis gas stream comprising H.sub.2 and CO [0142] 12 product stream of the first fixed-bed synthesis reactor [0143] 2 (first) product separation [0144] 2a fraction of separated hydrocarbons [0145] 2b aqueous phase [0146] 21 second product separation [0147] 21a fraction of separated hydrocarbons [0148] 21b aqueous phase [0149] 21c fraction comprising short and/or shorter chain hydrocarbons, CO, CO.sub.2 and H.sub.2 [0150] 13 fraction comprising short and/or shorter chain hydrocarbons, CO, CO.sub.2 and H.sub.2, as well as optionally H.sub.2O [0151] 3 second fixed-bed synthesis reactor [0152] 3a product stream of the second fixed-bed synthesis reactor (enriched with long chain hydrocarbons (>C.sub.25)).

EXAMPLES

[0153] The invention will now be further explained with reference to the following non-limiting examples.

Example 1

[0154] FTS was carried out with two reactors connected in sequence according to the invention, each using the same cobalt-based catalyst. In each case, temperature, target conversion, H.sub.2:CO ratio, inert gas content were set differently and the individual results were tabulated, wherein the values in the table indicate the required catalyst mass ratio of catalyst mass in the first fixed-bed synthesis reactor to catalyst mass in the second fixed-bed synthesis reactor in order to achieve the respective conversion as a function of temperature.

[0155] During the respective tests, a pressure of 22 bar prevailed in the first reactor and 20 bar in the second reactor and the weight volume flow of the synthesis gas stream added remained constant.

[0156] The following table shows a design matrix in which the experimental data of the process discussed above are entered. The matrix has been divided into several pages for better readability.

[0157] The temperature was outlined in steps of 200? C., 210? C., 220? C., 230? C. and 240? C. against the molar CO conversion in steps of 50 mol %, 60 mol %, 70 mol %, 80 mol %.

[0158] In each sub-table, the molar H.sub.2:CO ratio was outlined in steps of 1.8:1 1.9:1 2.0:1 2.1:1, 2.2:1, 2.3:1 against the inert gas fraction in steps of 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%.

[0159] Values marked with an asterisk (*) are values where the hydrogen conversion increased to above 99 mol %. If the values in the table are marked with 0*, this means that complete hydrogen conversion already took place in the first stage.

[0160] It can be seen here that the optimal ratio of the catalyst amounts is between 2.52:1 and 1.25:1.

[0161] In addition, it is easy to see that the reaction can be easily controlled by adjusting the temperature.

TABLE-US-00001 temperature 200? C. 210? C. 1.8 1.9 2.0 2.1 2.2 2.3 1.8 1.9 2.0 2.1 2.2 2.3 conversion 50% 0 2.0 1.9 1.9 1.8 1.7 1.7 0 2.0 1.9 1.9 1.8 1.8 1.7 CO 5 1.9 1.8 1.8 1.7 1.7 1.6 5 1.9 1.8 1.8 1.7 1.7 1.6 10 1.8 1.7 1.7 1.6 1.6 1.5 10 1.8 1.7 1.7 1.6 1.6 1.6 15 1.7 1.6 1.6 1.6 1.5 1.5 15 1.7 1.6 1.6 1.6 1.5 1.5 20 1.6 1.6 1.5 1.5 1.5 1.4 20 1.6 1.6 1.5 1.5 1.5 1.4 25 1.5 1.5 1.5 1.4 1.4 1.4 25 1.5 1.5 1.5 1.4 1.4 1.4 30 1.5 1.4 1.4 1.4 1.4 1.3 30 1.5 1.4 1.4 1.4 1.4 1.3 35 1.4 1.4 1.3 1.3 1.3 1.3 35 1.4 1.4 1.4 1.3 1.3 1.3 40 1.3 1.3 1.3 1.3 1.3 1.2 40 1.3 1.3 1.3 1.3 1.3 1.3 60% 0 2.7 2.5 2.4 2.2 2.1 2.0 0 2.7 2.5 2.4 2.2 2.1 2.0 5 2.4 2.3 2.2 2.1 2.0 1.9 5 2.4 2.3 2.2 2.1 2.0 1.9 10 2.2 2.1 2.0 1.9 1.8 1.8 10 2.2 2.1 2.0 1.9 1.9 1.8 15 2.0 1.9 1.9 1.8 1.7 1.7 15 2.0 1.9 1.9 1.8 1.8 1.7 20 1.9 1.8 1.7 1.7 1.6 1.6 20 1.9 1.8 1.8 1.7 1.7 1.6 25 1.7 1.7 1.6 1.6 1.6 1.5 25 1.7 1.7 1.7 1.6 1.6 1.5 30 1.6 1.6 1.5 1.5 1.5 1.5 30 1.6 1.6 1.6 1.5 1.5 1.5 35 1.5 1.5 1.5 1.4 1.4 1.4 35 1.5 1.5 1.5 1.5 1.4 1.4 40 1.5 1.4 1.4 1.4 1.4 1.3 40 1.5 1.4 1.4 1.4 1.4 1.3 70% 0 0.0* 3.5 3.2 2.9 2.7 2.5 0 0.0* 3.5 3.2 2.9 2.7 2.5 5 0.0* 3.0 2.8 2.6 2.4 2.3 5 0.0* 3.0* 2.8 2.6 2.4 2.3 10 0.0* 2.6 2.4 2.3 2.2 2.1 10 0.0* 2.5* 2.5 2.3 2.2 2.1 15 0.0* 2.3 2.2 2.1 2.0 1.9 15 0.0* 2.3* 2.2 2.1 2.0 2.0 20 0.0* 2.1 2.0 1.9 1.9 1.8 20 0.0* 0.0* 2.0 1.9 1.9 1.8 25 0.0* 1.9* 1.8 1.8 1.7 1.7 25 0.0* 0.0* 1.9 1.8 1.8 1.7 30 0.0* 1.9* 1.7 1.7 1.6 1.6 30 0.0* 0.0* 1.7 1.7 1.6 1.6 35 0.0* 1.7* 1.6 1.6 1.5 1.5 35 0.0* 0.0* 1.6 1.6 1.5 1.5 40 0.0* 0.0* 1.5 1.5 1.4 1.4 40 0.0* 0.0* 1.5 1.5 1.5 1.4 80% 0 0.0* 0.0* 5.0 4.2 3.7 3.3 0 0.0* 0.0* 0.0* 4.3 3.7 3.4 5 0.0* 0.0* 3.8* 3.4 3.1 2.8 5 0.0* 0.0* 0.0* 3.4 3.1 2.9 10 0.0* 0.0* 3.2* 2.9 2.7 2.5 10 0.0* 0.0* 0.0* 2.9 2.7 2.5 15 0.0* 0.0* 2.5* 2.5 2.3 2.2 15 0.0* 0.0* 0.0* 2.5 2.4 2.3 20 0.0* 0.0* 2.6* 2.2 2.1 2.0 20 0.0* 0.0* 0.0* 2.3 2.1 2.1 25 0.0* 0.0* 0.0* 2.0 1.9 1.9 25 0.0* 0.0* 0.0* 2.0 2.0 1.9 30 0.0* 0.0* 0.0* 1.8 1.8 1.7 30 0.0* 0.0* 0.0* 1.9 1.8 1.7 35 0.0* 0.0* 0.0* 1.7 1.6 1.6 35 0.0* 0.0* 0.0* 1.7 1.7 1.6 40 0.0* 0.0* 0.0* 1.6 1.5 1.5 40 0.0* 0.0* 0.0* 1.6* 1.6 1.5 temperature 200? C. 210? C. 1.8 1.9 2.0 2.1 2.2 2.3 1.8 1.9 2.0 2.1 2.2 2.3 conversion 50% 0 2.0 1.9 1.9 1.8 1.8 1.7 0 2.0 1.9 1.9 1.8 1.8 1.7 CO 5 1.9 1.8 1.8 1.7 1.7 1.6 5 1.9 1.8 1.8 1.7 1.7 1.7 10 1.8 1.7 1.7 1.7 1.6 1.6 10 1.8 1.8 1.7 1.7 1.6 1.6 15 1.7 1.7 1.6 1.6 1.5 1.5 15 1.7 1.7 1.6 1.6 1.6 1.5 20 1.6 1.6 1.5 1.5 1.5 1.5 20 1.6 1.6 1.6 1.5 1.5 1.5 25 1.5 1.5 1.5 1.5 1.4 1.4 25 1.6 1.5 1.5 1.5 1.4 1.4 30 1.5 1.4 1.4 1.4 1.4 1.4 30 1.5 1.5 1.4 1.4 1.4 1.4 35 1.4 1.4 1.4 1.4 1.3 1.3 35 1.4 1.4 1.4 1.4 1.4 1.3 40 1.4 1.3 1.3 1.3 1.3 1.3 40 1.4 1.4 1.3 1.3 1.3 1.3 60% 0 2.7 2.5 2.4 2.3 2.2 2.1 0 2.6 2.5 2.4 2.3 2.2 2.1 5 2.4 2.3 2.2 2.1 2.0 1.9 5 2.4 2.3 2.2 2.1 2.0 2.0 10 2.2 2.1 2.0 1.9 1.9 1.8 10 2.2 2.1 2.0 2.0 1.9 1.8 15 2.0 2.0 1.9 1.8 1.8 1.7 15 2.0 2.0 1.9 1.8 1.8 1.7 20 1.9 1.8 1.8 1.7 1.7 1.6 20 1.9* 1.8 1.8 1.7 1.7 1.7 25 1.8 1.7 1.7 1.6 1.6 1.6 25 1.7* 1.7 1.7 1.7 1.6 1.6 30 1.6 1.6 1.6 1.5 1.5 1.5 30 1.7* 1.6 1.6 1.6 1.5 1.5 35 1.6 1.5 1.5 1.5 1.4 1.4 35 0.0* 1.6 1.5 1.5 1.5 1.4 40 1.5* 1.5 1.4 1.4 1.4 1.4 40 0.0* 1.5 1.5 1.4 1.4 1.4 70% 0 0.0* 0.6* 3.2 3.0 2.8 2.6 0 0.0* 0.0* 3.2 3.0 2.8 2.6 5 0.0* 0.5* 2.8 2.6 2.5 2.3 5 0.0* 0.0* 2.8 2.6 2.5 2.4 10 0.0* 1.1* 2.5 2.4 2.2 2.1 10 0.0* 0.0* 2.5 2.4 2.3 2.2 15 0.0* 0.0* 2.3 2.1 2.1 2.0 15 0.0* 0.0* 2.3 2.2 2.1 2.0 20 0.0* 0.0* 2.1 2.0 1.9 1.8 20 0.0* 0.0* 2.1 2.0 1.9 1.9 25 0.0* 0.0* 1.9 1.8 1.8 1.7 25 0.0* 0.0* 1.9* 1.9 1.8 1.8 30 0.0* 0.0* 1.8 1.7 1.7 1.6 30 0.0* 0.0* 1.8* 1.7 1.7 1.7 35 0.0* 0.0* 1.6 1.6 1.6 1.5 35 0.0* 0.0* 1.7* 1.6 1.6 1.6 40 0.0* 0.0* 1.5 1.5 1.5 1.5 40 0.0* 0.0* 0.0* 1.5 1.5 1.5 80% 0 0.0* 0.0* 0.7* 4.3 3.8 3.4 0 0.0* 0.0* 0.0* 4.3 3.9 3.5 5 0.0* 0.0* 0.0* 3.5 3.2 2.9 5 0.0* 0.0* 0.0* 3.6* 3.2 3.0 10 0.0* 0.0* 0.0* 3.0 2.8 2.6 10 0.0* 0.0* 0.0* 3.2* 2.8 2.6 15 0.0* 0.0* 0.0* 2.6* 2.4 2.3 15 0.0* 0.0* 0.0* 2.7* 2.5 2.4 20 0.0* 0.0* 0.0* 2.3* 2.2 2.1 20 0.0* 0.0* 0.0* 0.0* 2.2 2.1 25 0.0* 0.0* 0.0* 2.2* 2.0 1.9 25 0.0* 0.0* 0.0* 0.3* 2.0 2.0 30 0.0* 0.0* 0.0* 1.6* 1.8 1.8 30 0.0* 0.0* 0.0* 2.6* 1.9 1.8 35 0.0* 0.0* 0.0* 1.6* 1.7 1.7 35 0.0* 0.0* 0.0* 0.0* 1.8* 1.7 40 0.0* 0.0* 0.0* 0.0* 1.6 1.6 40 0.0* 0.0* 0.0* 0.0* 1.7* 1.6 temperature 240? C. 1.8 1.9 2.0 2.1 2.2 2.3 conversion 50% 0 2.0 1.9 1.9 1.8 1.8 1.7 CO 5 1.9 1.9 1.8 1.8 1.7 1.7 10 1.8 1.8 1.7 1.7 1.6 1.6 15 1.7 1.7 1.6 1.6 1.6 1.6 20 1.6 1.6 1.6 1.6 1.5 1.5 25 1.6 1.5 1.5 1.5 1.5 1.4 30 1.5 1.5 1.5 1.4 1.4 1.4 35 1.4 1.4 1.4 1.4 1.4 1.4 40 1.4 1.4 1.4 1.3 1.3 1.3 60% 0 2.5 2.5 2.4 2.3 2.2 2.1 5 2.3 2.3 2.2 2.1 2.0 2.0 10 1.8* 2.1 2.1 2.0 1.9 1.9 15 0.6* 2.0 1.9 1.9 1.8 1.8 20 1.3* 1.9 1.8 1.8 1.7 1.7 25 0.3* 1.8 1.7 1.7 1.6 1.6 30 0.2* 1.7 1.6 1.6 1.6 1.5 35 0.1* 1.6 1.5 1.5 1.5 1.5 40 0.0* 1.5 1.5 1.5 1.4 1.4 70% 0 0.0* 0.1 3.2 3.0 2.8 2.7 5 0.0* 0.0* 2.8 2.7 2.5 2.4 10 0.0* 0.0* 2.5* 2.4 2.3 2.2 15 0.0* 0.0* 2.3* 2.2 2.1 2.1 20 0.0* 0.0* 0.0* 2.0 2.0 1.9 25 0.0* 0.0* 0.0* 1.9 1.9 1.8 30 0.0* 0.0* 0.0* 1.8 1.7 1.7 35 0.0* 0.0* 0.0* 1.7 1.6 1.6 40 0.0* 0.0* 0.0* 1.6* 1.5 1.5 80% 0 0.0* 0.0* 0.0* 0.0* 3.9 3.5 5 0.0* 0.0* 0.0* 0.0* 3.3 3.1 10 0.0* 0.0* 0.0* 0.0* 2.9 2.7 15 0.0* 0.0* 0.0* 0.0* 2.5 2.4 20 0.0* 0.0* 0.0* 0.0* 2.4* 2.2 25 0.0* 0.0* 0.0* 0.0* 2.3* 2.0 30 0.0* 0.0* 0.0* 0.0* 2.1* 1.9 35 0.0* 0.0* 0.0* 0.0* 0.1* 1.7 40 0.0* 0.0* 0.0* 0.0* 0.0* 1.6*