Abstract:
An apparatus and process for treating a complex mixture of hydrocarbons containing undesirable olefinic compounds to remove the mono olefins and diolefins in two stages and separate a desirable key component from the mixture, by first treating the key component in a reactive distillation column under mild conditions to hydrogenate diolefins then separating the diolefin-depleted key component and any lighter materials from the heavier components and sending the diolefin-depleted key component and lighter materials to a second reactive distillation column where the lights are removed overhead and the diolefin-depleted key component is hydrogenated under more severe conditions to remove the mono olefins.

Description:
This is a division of application Ser. No. 09/262,251 filed on Mar. 4, 1997, now U.S. Pat. No. 6,284,104. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and process for improving the flexibility of operation of reactive distillation hydrogenation processes. 
     2. Related Art 
     The use of catalysts in a distillation column to concurrently carry out chemical reactions and separate the reaction products has been practiced for some time. Surprisingly, this use of a catalytic distillation column reactor lends itself particularly well for hydrogenations. See for example, U.S. Pat. Nos. 5,595,634; 5,599,997; 5,628,880; 5,773,670 and European Patent No. 0556025 B1. The combination is useful because the reactants in the liquid phase are quickly separated from the reaction products due to boiling point differences by fractional distillation. Thus further reaction is suppressed. 
     Several different arrangements have been disclosed to achieve the desired result. For example, British Patents 2,096,603 and 2,096,604 disclose placing the catalyst on conventional trays within a distillation column. A series of U.S. patents, including those listed above and more, particularly U.S. Pat. Nos. 4,443,559 and 4,215,011 disclose using the catalyst as part of the packing in a packed distillation column. The use of multiple beds in a reaction distillation tower is also known and illustrated, for example, in U.S. Pat. Nos. 4,950,834; 5,321,163; and 5,595,634. 
     In reactive distillations, such as catalytic distillation, as in any other distillation, there is no rigid cut off between the components. Reactions carried on in specified portions of the column using some constituents may leave undone other desirable treatment of other portions of the column constituents. 
     For example, mixed refinery streams often contain a broad spectrum of olefinic compounds. This is especially true of products from either catalytic cracking or thermal cracking processes (pyrolysis gas). These unsaturated compounds comprise ethylene, acetylene, propylene, propadiene, methyl acetylene, butenes, butadiene, amylenes, hexenes, etc. Many of these compounds are valuable especially as feed stocks for chemical products. Olefins having more than one double bond and the acetylenic compounds (having a triple bond) have lesser uses and are detrimental to many of the chemical processes in which the single double bond compounds are used, for example, polymerization. Sulfur and nitrogen compounds, among others, are frequently desirably removed also and they may be effectively removed from a portion of the column constituents, but because of different boiling points for other portions of the column constituents and the contaminants therein, not all of the contaminants may be removed. 
     Generally it is more difficult to remove both dienes and olefins than dienes alone. Diene-rich streams will hydrogenate at a higher volumetric rate under milder conditions than will a diene depleted olefinic stream. Sulfur in the several hundred ppm range is not uncommon for some feeds. Palladium hydrogenation catalysts are not able to handle such high sulfur levels, however, double-digit diene levels often present in these feeds overwhelm the sulfur impurities in their mutual competition for catalyst sites thereby providing reasonable rates notwithstanding. 
     In hydrotreating streams with high concentrations of dienes present (above 1000 ppm), there is a need to refrain from using high temperatures to avoid oligomerization. Generally, temperatures in the area of 170° F. or above are avoided. Such operating restraints create conditions which are unfavorable for exhaustive olefin conversion in the same unit in which the diene is eliminated. 
     The present invention provides apparatus and process to address the reactive distillation hydrogenation of feed streams having concentrations of both mono and di-olefins. 
     SUMMARY OF THE INVENTION 
     The present invention includes an apparatus for conducting reactive distillations comprising a first distillation column, a first primary catalyst bed for carrying out a hydrogenation of unsaturated compounds comprising diolefins, said first primary catalyst bed being positioned in said distillation column to provide a first reaction zone for diolefins in said first distillation column, and optionally, a first secondary catalyst bed above said first primary catalyst bed, said first secondary catalyst bed to provide a second reaction zone for diolefins remaining in said first distillation column after said first reaction zone, a first mixed saturated/unsaturated compound feed entry below said first primary bed, a hydrogen feed below said primary bed, a bottoms line and an overhead line connecting to a second distillation column comprising a second primary catalyst bed for carrying out hydrogenation of unsaturated compounds comprising mono olefins from said first distillation column, said second primary catalyst bed being positioned in said distillation column to provide a first reaction zone for unsaturated compounds in said second distillation column, and optionally, a second secondary catalyst bed below said second primary bed, said second secondary catalyst bed to provide a second reaction zone for mono olefins remaining in the second distillation column after said first reaction zone, said overhead line from said first distillation column connecting to said second distillation column above said second primary catalyst bed and a hydrogen feed below said second primary bed. 
     The process carried out in the apparatus is also part of the present invention. 
     There may be distillation structures or trays between the primary and secondary beds. Hydrogenation reactions liberate a significant heat of reaction (on the order of 50,000 or greater BTU/lb mole H 2  consumed). This released heat adds to vapor load in the column. Optionally, side condensers may be used to keep the uniformity of the vapor profile in the column within desired ranges. A secondary catalyst bed may be positioned in the distillation column, above or below the primary bed as heretofore described, to allow lighter or heavier boiling components to be exposed to additional catalyst and be purified or treated further. 
     The term “reactive distillation” is used to describe the concurrent reaction and fractionation in a column. For the purposes of the present invention, the term “catalytic distillation” includes reactive distillation and any other process of concurrent reaction and fractional distillation in a column regardless of the designation applied thereto. 
     The catalyst beds as used in the present invention may be described as fixed, meaning positioned in a fixed area of the column and include expanded beds and ebulating beds of catalysts. The catalysts in the beds may all be the same or different so long as they carry out the function of hydrogenation as described. Catalysts prepared as distillation structures are particularly useful in the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The FIGURE is a simplified process flow diagram of one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is particularly useful for removal of mono olefins and diolefins from cracked gas streams. Thermally cracked gas streams have a particularly wide range of carbon numbers and compound types. Normally, compounds in one carbon number range (such as C 4 &#39;s in a C 4 /C 5  splitter) will function as the light key grouping in the column. Thus compounds one carbon number greater (such as C 5 &#39;s in a C 4 /C 5  splitter) will serve as the heavy key grouping for the column. 
     Hydrogenation is the reaction of hydrogen with a carbon-carbon multiple bond to “saturate” or partially saturate the compound. This reaction has long been known and is usually done at super atmospheric pressures and moderate temperatures using a large excess of hydrogen over a metal catalyst. Among the metals known to catalyze the hydrogenation reaction are platinum, rhenium, cobalt, molybdenum, nickel, tungsten and palladium. Generally, commercial forms of catalysts use supported oxides of these metals. The oxide is reduced to the active form either prior to use with a reducing agent or during use by the hydrogen in the feed. These metals also catalyze other reactions, most notably dehydrogenation at elevated temperatures. Additionally, they can promote the reaction of olefinic compounds with themselves or other olefins to produce dimers or oligomers as residence time is increased. 
     Selective hydrogenation of hydrocarbon compounds has been known for quite some time. Peterson et al in “The Selective Hydrogenation of Pyrolysis Gasoline,” presented to the Petroleum Division of the American Chemical Society in September of 1962, discusses the selective hydrogenation of C 4  and higher diolefins. Boitiaux et al in “Newest Hydrogenation Catalyst”,  Hydrocarbon Processing , March 1985, presents a general overview of various uses of hydrogenation catalysts. 
     FIRST COLUMN 
     The first column is operated with the catalyst located above the hydrocarbon feed. It is operated under conditions to reduce only dienes by hydrogenation. The column is operated to move a key component, for example C 5 , upward into the primary and any secondary beds under conditions of pressure and temperature to hydrogenate only the dienes, e.g., 150° F. to a top temperature of 170-200° F. at 10 to 75 psig. The exact upper temperature will depend on the diene makeup and other unsaturates such as the acetylenes and the stability of the particular mix of unsaturates to oligomerization. 
     The upflow of the key component operates the paradigm shift that keeps the catalyst clean and inhibits coking of the dienes. The faster reaction rates of the dienes compared to the mono olefins in hydrogenation allow short superficial vapor phase contact times in the range of 20-60 seconds. 
     The heaviest carbon-range number that is directed upward serves as the light-key carbon range for the column. Compounds of lower carbon number than this behave as the “lighter than light keys” of the system. These lighter compounds tend to equilibrate more into vapor than into liquid which makes reaction for the dienes in that carbon group much more difficult. However, use of a secondary reaction zone with catalyst (above at a lower temperature that the primary bed) allows the concentration of this lower carbon number fraction. Thus, the combined primary bed and the optional upper secondary bed together handle a wider boiling range than would otherwise be achievable. 
     SECOND COLUMN 
     The second column revives the diene depleted overhead from the first column and feeds it above the primary and any optional secondary beds where it is hydrogenated in the reactive distillation mode. In the near absence of dienes e.g. &lt;0.1 wt %, higher temperatures in the range of 200-325° F. are used at pressures in the range of 60-150 psig. Mono olefins-only systems tend to have less favorable hydrogen uptake than diene-rich streams. The superficial vapor phase contact time even under the more severe conditions is 50-90 second range. Note that the key component carbon numbers in the second column may be coincident with or separate from the key component carbon numbers in the first column depending on the objectives of the operation. 
     The key component builds up in the column liquid and favors the reaction on the key component. In contrast the heavier carbon-range fraction thins out in the downflowing liquid. However, inclusion of a bottoms secondary catalyst bed (which is lower in the column where the higher temperature causes more boil up of the heavies) can be used to concentrate the heaviest carbon-number range species and react the heavier olefins out more effectively also. As in any distillation there is a temperature gradient within the distillation column reactor. The temperature at the lower end of the column contains higher boiling material and thus is at a higher temperature than the upper end of the column. 
     The result of the operation of the process in the distillation column reactor is that lower hydrogen partial pressures (and thus lower total pressures) may be used. 
     It is believed that the present distillation column reaction is a benefit first, because the reaction is occurring concurrently with distillation and the initial reaction products and other stream components are removed from the reaction zone(s) as quickly as possible reducing the likelihood of side reactions. Second, because all the components are boiling, the temperature of reaction is controlled by the boiling point of the mixture at the system pressure. The heat of reaction simply creates more boil up, but no increase in temperature at a given pressure. As a result, a great deal of control over the rate of reaction and distribution of products can be achieved by regulating the system pressure. A further benefit that this reaction may gain from distillation column reactions is the washing effect, particularly in the downflow operation of the second column that the internal reflux provides to the catalyst thereby reducing polymer build up and coking. 
     Referring now to the FIGURE, a process flow diagram for the removal of unsaturates, primarily mono- and di-olefins from a full range pyrolysis gas. Such items as reboilers, compressors, pumps and the like have been omitted but their normal utilization is readily apparent to those in the art. 
     The feed, a pyrolysis gas as described in TABLE 1, enters the first column  10  via line  12 . 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Component 
                 Wt % 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 BD/C4Acetylene 
                 0.2 
               
               
                   
                 Butylenes 
                 0.1 
               
               
                   
                 Butanes 
                 0.0 
               
               
                   
                 C5 Saturates 
                 1.0 
               
               
                   
                 C5 Olefins 
                 4.2 
               
               
                   
                 C5 Diolefins 
                 13.0 
               
               
                   
                 C6 Saturates 
                 2.7 
               
               
                   
                 C6 Olefins 
                 2.3 
               
               
                   
                 C6 Diolefins 
                 7.0 
               
               
                   
                 C7 Saturates 
                 1.5 
               
               
                   
                 C7 Olefins 
                 1.1 
               
               
                   
                 C7 Diolefins 
                 3.4 
               
               
                   
                 C8 Saturates 
                 0.5 
               
               
                   
                 C8 Olefins 
                 0.4 
               
               
                   
                 C8 Diolefins 
                 1.2 
               
               
                   
                 Benzene 
                 18.7 
               
               
                   
                 Toluene 
                 17.4 
               
               
                   
                 EthylBenzene 
                 2.1 
               
               
                   
                 Xylenes 
                 7.6 
               
               
                   
                 Styrene 
                 2.6 
               
               
                   
                 Heavier 
                 12.9 
               
               
                   
                 Total 
                 100.0 
               
               
                   
                   
               
             
          
         
       
     
     In this illustration the tower  10  is operated under conditions to take the C 6  fraction upward (bottoms −394° F. top −212° F. at 60 psig.) The C 7  and heavier carbon atom components are removed via line  34  for other processing. The C 6  fraction contains some C 7  and heavier but is comprised of predominantly C 6  and lighter carbon number components. 
     C 6  components contain principally alkanes, benzene, 5 to 12% mono olefins and 15 to 35% dienes. Similarly, the lighter components contain a wide distribution of species including dienes and mono olefins. Hydrogen is added via line  14  at a rate to provide an excess stoichiometric amount to the dienes present in the C 6  and higher fraction. In bed  16  a hydrogenation catalyst is provided in the form of distillation structure. Under the conditions of temperature and pressure described there is both a vapor and liquid phase comprised principally of the C 6  components and as a result the C 6  dienes are substantially eliminated. 
     The higher components under these conditions are principally vaporous in bed  16 . However, the temperature in bed  18 , also a hydrogenation catalyst as a distillation structure, is lower because of temperature gradient in the column. The secondary bed  18  allows the lower boiling components to undergo the same type of two phase contact as the C 6  fraction in bed  16  thereby allowing a concentration of this higher portion with the dienes substantially eliminated. A side draw  44  is used to remove a portion of the lights diene-depleted concentrate and diene-depleted C 6  into collector  40 . A portion of the collected material can be returned via line  42  (dotted line) to the column  10  to maintain the vapor load on the column. Otherwise the material from side draw  44  is fed to the second column  48  via line  46 . 
     An overhead  20  also containing mostly diene-depleted C 5 , C 6  and lighter material goes through condenser  22  into collector  24 . The non-condensibles are removed for recycle to the hydrogen feed  14  or for disposal via line  26 . A portion of the condensed material is returned as reflux  36  to column  10  and the remainder fed via  38  to line  46  into column  48 . 
     The feed from column  10  is characterized as having almost all of the diene and greater unsaturates (acetylenes) removed by hydrogenation with little formation of oligomers. The olefins are substantially untouched because of the restricted operating temperature. 
     In column  48  the operating conditions are more severe in order to hydrogenate the mono olefins (bottoms −338° F., top −251° F. at 100 psig). The feed enters above primary catalyst bed  50  which is a hydrogenation catalyst prepared as a distillation structure. Again, the conditions are such that the key component, the C 6  constituents, is moved downward. The lighter components, primarily C 5 +, exit via overhead line  54  through condenser  52  into collector  58 . The non-condensibles are removed either for disposal via line  56  or recycle via line  60  to hydrogen feed  62 . A small portion of the liquid in collector  58  is removed via line  78  and the remainder returned via line  76  to column  48  as reflux. 
     A collector  66  is located on side draw  64  which removes hydrogenated product via line  74 . A portion may be returned via line  68  to control the vapor load on the column. Alternatively the side draw stream  64  may be recovered as a vapor (elimination of the collector  66 ), which, although it will result in an energy penalty, will provide other benefits, namely (a) further retention of the heavy olefins in the secondary bed  72  and (b) a greater increase in the temperature of bed  72  relative to the primary bed  50 , both of which enhance the performance of the secondary bed. 
     Secondary bed  72  contains a hydrogenation catalyst as a distillation structure and any heavier fraction remaining is concentrated and given a polishing hydrogenation and recovered via line  70  for combination with the side draw stream  74  into product stream  80 . 
     Table 2 shows the temperature profile and distribution of the materials in the column  10 . The conditions in the secondary catalyst bed  18  (corresponds to trays 4-16) and the primary bed  16  (corresponds to trays 17-30) are represented by the blocked out areas. The other trays are denoted by number. Tray  48  is the reboiler. 
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 PRESS- 
                 LI- 
                   
                   
                 PRO- 
               
               
                   
                 TEMP 
                 URE 
                 QUID 
                 VAPOR 
                 FEED 
                 DUCT 
               
               
                 TRAY 
                 ° F. 
                 PSIA 
                 LBM/H 
                 LBM/H 
                 LBM/H 
                 LBM/H 
               
               
                   
               
             
             
               
                 1C 
                 101.4 
                 74.7 
                 3510 
                   
                   
                 290.6 vap. 
               
               
                   
                   
                   
                   
                   
                   
                 140.2 liq. 
               
               
                 2 
                 211.6 
                 74.7 
                 4912 
                 3940 
               
               
                 3 
                 215.8 
                   
                 4902 
                 5343 
               
               
                 BED 
                 217.7 
                 75.1 
                 4851 
                 5332 
               
               
                 18 
                 219.5 
                 75.3 
                 4794 
                 5282 
               
               
                   
                 221.3 
                 75.5 
                 4730 
                 5225 
               
               
                   
                 223.3 
                 75.7 
                 4658 
                 5161 
               
               
                   
                 225.6 
                 75.9 
                 4577 
                 5089 
               
               
                   
                 228.4 
                 76.1 
                 4485 
                 5008 
               
               
                   
                 231.9 
                 76.3 
                 4385 
                 4916 
               
               
                   
                 236.0 
                 76.5 
                 4278 
                 4815 
               
               
                   
                 240.6 
                 76.7 
                 4170 
                 4709 
               
               
                   
                 245.7 
                 76.9 
                 4064 
                 4601 
               
               
                   
                 250.8 
                 77.1 
                 3962 
                 4495 
               
               
                   
                 255.9 
                 77.3 
                 3863 
                 4392 
               
               
                   
                 260.8 
                 77.5 
                 3266 
                 4294 
                   
                 503.8 Liq 
               
               
                 BED 
                 265.6 
                 77.7 
                 3184 
                 4201 
               
               
                 16 
                 269.4 
                 77.9 
                 3113 
                 4118 
               
               
                   
                 272.4 
                 78.1 
                 3050 
                 4047 
               
               
                   
                 274.6 
                 78.3 
                 2995 
                 3985 
               
               
                   
                 276.2 
                 78.5 
                 2945 
                 3930 
               
               
                   
                 277.3 
                 78.7 
                 2898 
                 3879 
               
               
                   
                 278.1 
                 78.9 
                 2852 
                 3832 
               
               
                   
                 278.7 
                 79.1 
                 2808 
                 3787 
               
               
                   
                 279.2 
                 79.3 
                 2764 
                 3743 
               
               
                   
                 279.7 
                 79.5 
                 2719 
                 3698 
               
               
                   
                 280.2 
                 79.7 
                 2672 
                 3653 
               
               
                   
                 281.0 
                 79.9 
                 2621 
                 3606 
               
               
                   
                 282.2 
                 80.1 
                 2563 
                 3555 
               
               
                   
                 284.3 
                 80.3 
                 2489 
                 3497 
               
               
                 31 
                 288.1 
                 80.5 
                 2376 
                 3423 
               
               
                 32 
                 296.2 
                 80.7 
                 3532 
                 3311 
                 1206.2 liq. 
               
               
                   
                   
                   
                   
                   
                  237.0 vap. 
               
               
                 33 
                 310.2 
                 80.9 
                 3645 
                 3023 
               
               
                 34 
                 315.3 
                 81.1 
                 3648 
                 3136 
               
               
                 35 
                 319.7 
                 81.3 
                 3645 
                 3139 
               
               
                 36 
                 324.1 
                 81.5 
                 3639 
                 3136 
               
               
                 37 
                 328.7 
                 81.7 
                 3632 
                 3131 
               
               
                 38 
                 333.6 
                 81.9 
                 3626 
                 3124 
               
               
                 39 
                 338.7 
                 82.1 
                 3621 
                 3117 
               
               
                 40 
                 343.8 
                 82.3 
                 3618 
                 3112 
               
               
                 41 
                 348.7 
                 82.5 
                 3616 
                 3110 
               
               
                 42 
                 353.2 
                 82.7 
                 3613 
                 3108 
               
               
                 43 
                 357.5 
                 82.9 
                 3608 
                 3105 
               
               
                 44 
                 361.6 
                 83.1 
                 3597 
                 3099 
               
               
                 45 
                 366.1 
                 83.3 
                 3575 
                 3088 
               
               
                 46 
                 371.6 
                 83.5 
                 3532 
                 3066 
               
               
                 47 
                 379.8 
                 83.7 
                 3450 
                 3023 
               
               
                 48R 
                 393.5 
                 83.9 
                   
                 2941 
                   
                 508.7 liq. 
               
               
                   
               
             
          
         
       
     
     Table 3 shows the temperature profile and distribution of materials in column  48 . The conditions in the secondary catalyst bed  72  (corresponds to trays 38-46) and the primary bed  50  (corresponds to trays 19-31) are represented by the blocked out areas. The other trays are denoted by number. Tray  49  is the reboiler. 
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                 TEMP 
                 PRESSURE 
                 LIQUID 
                 VAPOR 
                 FEED 
                 PRODUCT 
               
               
                 TRAY 
                 ° F. 
                 PSIA 
                 LBM/H 
                 LBM/H 
                 LBM/H 
                 LBM/H 
               
               
                   
               
             
             
               
                 1C 
                 131.2 
                 114.7 
                 1504 
                   
                   
                 134.1 vap. 
               
               
                   
                   
                   
                   
                   
                   
                 208.7 Liq. 
               
               
                 2 
                 251.1 
                 114.7 
                 2247 
                 1846 
               
               
                 3 
                 255.4 
                 114.9 
                 2268 
                 2590 
               
               
                 4 
                 257.3 
                 115.1 
                 2265 
                 2611 
               
               
                 5 
                 259.0 
                 115.3 
                 2258 
                 2607 
               
               
                 6 
                 260.6 
                 115.5 
                 2250 
                 2601 
               
               
                 7 
                 262.4 
                 115.7 
                 2240 
                 2593 
               
               
                 8 
                 264.3 
                 115.9 
                 2228 
                 2583 
               
               
                 9 
                 266.5 
                 116.1 
                 2214 
                 2570 
               
               
                 10 
                 268.7 
                 116.3 
                 2198 
                 2556 
               
               
                 11 
                 271.2 
                 116.5 
                 2182 
                 2541 
               
               
                 12 
                 273.8 
                 116.7 
                 2165 
                 2525 
               
               
                 13 
                 276.4 
                 116.9 
                 2149 
                 2508 
               
               
                 14 
                 279.1 
                 117.1 
                 2132 
                 2492 
               
               
                 15 
                 281.8 
                 117.3 
                 2116 
                 2475 
               
               
                 16 
                 284.4 
                 117.5 
                 2099 
                 2458 
               
               
                 17 
                 287.0 
                 117.7 
                 2974 
                 2442 
                 643.9 liq. 
               
               
                 18 
                 289.9 
                 117.9 
                 2936 
                 2673 
               
               
                 BED 
                 292.0 
                 118.1 
                 2891 
                 2635 
               
               
                 50 
                 293.9 
                 118.3 
                 2846 
                 2590 
               
               
                   
                 295.6 
                 118.5 
                 2802 
                 2545 
               
               
                   
                 297.2 
                 118.7 
                 2758 
                 2501 
               
               
                   
                 298.6 
                 118.9 
                 2715 
                 2457 
               
               
                   
                 299.8 
                 119.1 
                 2671 
                 2413 
               
               
                   
                 301.0 
                 119.3 
                 2628 
                 2370 
               
               
                   
                 302.1 
                 119.5 
                 2585 
                 2327 
               
               
                   
                 303.1 
                 119.7 
                 2541 
                 2284 
               
               
                   
                 304.0 
                 119.9 
                 2497 
                 2240 
               
               
                   
                 305.0 
                 120.1 
                 2452 
                 2196 
               
               
                   
                 306.0 
                 120.3 
                 2406 
                 2151 
               
               
                   
                 307.2 
                 120.5 
                 2358 
                 2105 
               
               
                 32 
                 308.6 
                 120.7 
                 1981 
                 2056 
                   
                 326.2 liq. 
               
               
                 BED 
                 310.2 
                 120.9 
                 1968 
                 2006 
               
               
                 72 
                 312.2 
                 121.1 
                 1955 
                 1993 
               
               
                   
                 314.4 
                 121.3 
                 1941 
                 1980 
               
               
                   
                 316.7 
                 121.5 
                 1928 
                 1966 
               
               
                   
                 319.1 
                 121.7 
                 1916 
                 1953 
               
               
                   
                 321.4 
                 121.9 
                 1906 
                 1941 
               
               
                   
                 323.5 
                 122.1 
                 1899 
                 1931 
               
               
                   
                 325.4 
                 122.3 
                 1894 
                 1924 
               
               
                   
                 326.9 
                 122.5 
                 1890 
                 1919 
               
               
                   
                 328.1 
                 122.7 
                 1888 
                 1915 
               
               
                   
                 329.0 
                 122.9 
                 1887 
                 1913 
               
               
                   
                 329.7 
                 123.1 
                 1886 
                 1912 
               
               
                   
                 330.2 
                 123.3 
                 1886 
                 1911 
               
               
                   
                 330.7 
                 123.5 
                 1886 
                 1911 
               
               
                 47 
                 331.0 
                 123.7 
                 1876 
                 1911 
                 108.5 vap. 
               
               
                 48 
                 338.0 
                 123.9 
                 1925 
                 1792 
               
               
                 49R 
                 338.3 
                 124.1 
                   
                 1841 
                   
                 83.4 liq.