water, since the clear Epsoin liquor has a gravity of 3.5O Baume and is only diluted to 25' Baiimb by tlie water necessary to wash the calciuin sulfate clean.
Tile 25' liauini. Epsoai solutioii is pumped t u a Iargc copper vaimnn evaporatm on 1.la top floor, w-liere it is concentratcd to 38' 13aumC at a h d i u g point of 130" F. and is then discharged iiito shallow stcel tanks about 2 feet deep. hi about two days this srilntion is completely cooled. The mother liquor is tiicn drained ofi and tire crystals are delivered liy conveyor into a h o p p r o ~ c ra 30-inch brass centrifugal. in nlrii:li tlie cryst,& arc dried us completely as possible and .d tlirringli two rotary drums for drying and cooling. The drying of Epsom i s a rather delicate operation, as too high a tcmperatnre will canse n dull appearance, and insutfcieiit drying will leave nioistnrc which will result in (,nkiiigi n tlie tiiinl packages. Epsmii is packed for d e iii 100-pnnd bags, 125-pound kegs, and :iWpound barrrls. The crystals are uf the white, needle vnric1.y and coinply with tlie U. S. P. purity test,. This piant is operat.ed npon strictly southern and local materials, llses of Epsom Salt arid Carbon Dioxide
Tlic Epsom is distriiioted tlirouglirrut the South through whulesale druzeists nnd the cariionic acid is used cxclusivelv for carbonating wntcr for bwcragc pnrposes. Althongh the Crystnl Carhonk 1,:iborntory is primarily iii the hnsiness of rnanufnetiiriiig c:irlwn dioxide for use i i i the beverage industry, tire qnantit,y of nmgnesium sulfate obtained as a by-product niilkcs this coinp est E:jinoni maiiiiStx%oiingcmicerris in tlie _ I
Pieuse 4~ ~ E p s o mCrynrallizi*ilp l'ankr and Conveyors
The ealcinm snlfate is discarded as there is no market Sor a smaII outpot of 4 or 5 tons pt.r day. -
-
High-Boiling Solvents from Natural-Gas Pentanes' Lee 1%.Clark SIIARPLBS S U L Y I L T S ConPoaATIoli, HUL,.B,
ATUIUJ, gas from botli the West Virginia and the midcont,inent fields contains a large percentage of pentanes, and there is a steadily increasing demand for high-boiling constituents for lacquer solvents. The connecting link betwecn these two conditions is the plant of the Sharpies Solvents Corporation a t Belle, W. Va., which represents the first coinrnercial venture in the use of petroleum hydrocarbons as the raw material for organic synthesis. Amyl alcohols are obtained from the pentanes by a process , 50d the corresponding of chlorination followed by hyrlrol amyl acetates are tiieir prepared as desired from tlie alcohols, while small amounts of amylene dichlorides, amylcnes, diamylene, and diamyl ether are recovcred as by-products. The present article is intended to give a concia: description of the operating processes of this plant.
N
Raw Materials The chief raw materials are pentanes, clilurine, caustic. and acetic acid. Sulfuric acid involved in the manufacturing processes is largely recovcred, but some make-up of this substance is required. The pentanes were originally obtained by fractionating natural-gas gasoline at the Belle plant, cutting out the 30 to 35 per cent. pentane content, and rehlending the lieads and tails for resale a.s gasoline. ilt present a pentane cut with 95 per cent boiling between 28" and 39" C. is supplied in tank cars to the Belle plant by the refiners of natural-gas gasoline. The supply is derived from both the West Vir*
Received March 11, 1930.
w. VA.
ginia and midcontinent ticlds, approximately half coining from each. Both the clilorine ani1 canstic required in manufacture come by pipe line from tlie Belle Alkali Company, which is directly adjacent to the plant. Acetic and sulfuric acids are snpplied trorn outside source^. Chlorination of Pentanes The pentaiie cnt contains botli normal and iso-pentane As indicated in the Aow shcct of Figure 1, it is pumped from storage to a mixing tank, where pentanes recovered from the systein are added and the niixtnre is thoroughly dehydrated. From the mixing tank the pent,anes are passed through a vaporizer. Clilorine is passed tlirough another vaporizer, and the two gas streams are combined in a mixing throat. Iprorn this they pass innnediatcly into gas-fired pipe st,ilI. Figure 2 shom the control board and the battery of pumps in the chlorination operatiom The exit gases from the pipe st,ill pass tlirougli pipe banks cooled rvitli a water spray and entrr the first of four continuous fractionating columns. This first column is operated to take off an overhead product containing only pentanes and the hydroclrloric acid produced in the chlorination. This product is returned to the niixing tank a t the start of the system, while the bottom prodnct, a mixture of amyl chlorides and unchlorinated pentancs, is pumped to the second continuous column. The pentane-rich overhead product from this column is returned to the feed of the first, column, while the bottom prodnct, low in pentanes and high in chlorides,
440
INDUSTRIAL AND ENGINEERING CHEMISTRY
Val. 22, xo. 5
C H L 0 Rl NATION
R E C O V E R Y HYDROCHLORIC A C I D Q f L N T A N E Figure I-Flowsheet
of Chlorination Process for Pentanes and Recovery of Hydrochloric Acid
passes to the third column. In this column the amyl dichlorides and more highly chlorinated substances are removed in the still liquor and sent to a separate discontinuous still, while the amyl chlorides are sent to the fourth column. Here a practically pure mixture of amyl chlorides is obtained as a bottom product, while the residual pentanes are taken off overhead together with some amyl chlorides and are returned to the feed of the first still. The dichlorides and polychlorides in the still liquor from the third column are worked up in batches in a caustic still, the dichlorides being recovered while the more chlorinated compounds are sent to waste.
operations. The neutral brine is returned to the chlorine manufacturer with an increased salt content. The scrubbed gases then pass through a condenser, are compressed and condensed, and the liquid pentanes are returned to the mixing tank, The 20" Baume acid obtained from the absorption system is run to storage and sold. Hydrolysis of Amyl Chlorides The various monochloro derivatives of the pentanes are produced in approximately the proportions shown in Table I. Table I-Mixed
Recovery of Hydrochloric Acid
For each atom of chlorine introduced into a pentane there is formed one molecule of hydrochloric acid. This hydrochloric acid, together with unchlorinated pentanes, constitutes the overhead product from the first continuous still, which is returned to the mixing tank a t the start of the chlorination system, as shown in Figure 1. Here it is introduced at the bottom, and the dry hydrochloric acid, bubbling up through the liquid pentanes, combines with any water present to form hydrochloric acid, which settles out at the bottom of the tank and is drawn off from time to time. Only a fraction of the hydrochloric acid is removed in this way, the rest being recovered in a continuous system which withdraws gas from the top of the mixing tank, passes it through a condenser to remove most of the pentanes, and then through a double countercurrent absorption system of fused silica, where the hydrochloric acid is taken up in water. The exit gases from the absorbing system are scrubbed with dilute caustic brine liquor from the subsequent hydrolysis
Amyl Chlorides Produced by Chlorination of Pentanes4 FORMULA P E R CENT O F MIXTURE 24 8
18 15
30 gZ:>CCl.CHz.CHs
5
Ninety-five per cent of the mixture boils between 85' and 107' C. The only impurities present are the amylenes. a
For the production of amyl alcohols this mixture of amyl chlorides is hydrolyzed with a caustic solution in the presence of a catalyst. The hydrolysis is carried out in a continuous system, shown in the flowsheet of Figure 3, consisting of two digesters connected in series with heaters in the circulating lines. A photograph of the lower floor of the digester unit is shown in Figure 4. The mixture of amyl chlorides and a 30 per cent caustic solution are fed to the first digester, which is maintained full, while the products of the reaction are removed from the vapor space of the second digester, which is maintained partially empty. The caustic solution is sup-
of the clilorides froin a dry iuixture of clilorkles arid alroliolil owing to the forination of a eoiistant-boiliiili solution. Wisfactory scpwation is, however, now ohtained. The vjct alcotiols from the base of t,he second colunm are dehydrated in a third c o l u r ~ ~ nwhich , retunis an oi-crliead mixturc of water and airolioli to tlrr second eoluirrii and
~ ~ g I ~ (:untroi r c BOBrd and Battery of Pumps for the
Chlorination of Penfanos
PiCvre 1 Lower Floor of the l>iCemter Unrf U ~ r fdo l the Ifydrolyda of Amyl Chioridea
pnxlric€r.cH,.c€I,oH
$p> CII.CH*.C€Iz
PER CINI. 08 MixTUItK
180.5
16
128
32
Teiiisiy amyl alcohol produced
