Liquid purification or separation – Processes – Chromatography
Reexamination Certificate
2002-01-31
2003-12-16
Therkorn, Ernest G. (Department: 1723)
Liquid purification or separation
Processes
Chromatography
C127S046200, C127S046300
Reexamination Certificate
active
06663780
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for the fractionation of molasses using a chromatographic simulated moving bed system comprising at least two chromatographic partial packing material beds.
Fractionation of molasses denotes fractionation of various vegetable-derived by-products of the food and fermenting industries, such as beet and cane molasses, stillage, vinasse, slop, wood molasses, corn steep water, wheat, barley and corn molasses (hydrolyzed C starch).
The simulated moving bed system (SMB) has been developed and introduced by UOP (United Oil Products), U.S.A., at, the beginning of the 1960's, initially for petrochemical applications (U.S. Pat. No. 2,985,589). Today several simulated moving bed methods for a number of different applications are known (U.S. Pat. Nos. 3,706,812, 4,157,267, 4,267,054, 4,293,346, 4,312,678, 4,313,015, 4,332,623, 4,359,430, 4,379,751, 4,402,832, 4,412,866, 4,461,649, 4,533,398 and 5,127,957, and published European application 0,279,946).
The simulated moving bed system enables separating performances that are many times higher, and dilution of the products (consumption of eluent) is lower than in the batch method.
The simulated moving bed method can be either continuous or sequential.
In a continuous simulated moving bed method, all flows are continuous. These flows are: feeding of feed solution and eluent liquid, recycling of liquid mixture and recovery of products (usually only two). The flow rate for these flows may be adjusted in accordance with the separation goals (yield, purity, capacity). Normally, 8 to 20 partial packing material beds are combined into a single loop. In accordance with the above-mentioned U.S. Pat. No. 4,402,832, the recycling phases have been applied to the recycling of e.g. non separated fraction and dilute fractions. The feed and product recovery points are shifted cyclically in the downstream direction. On account of the feed of eluent liquid and feed solution (and on account of recovery of products) and the flow through the packing material bed, a dry solids profile is formed. Ingredients having a lower migration rate in the packing bed are concentrated at the downstream end (back slope) of the dry solids profile, and respectively ingredients having a higher migration rate at the upstream end (front slope). Feeding points for feeding solution and eluent liquid and recovery points for product or products are shifted gradually at substantially the same rate at which the dry solids profile moves in the bed. The product or products are recovered substantially from the upstream and downstream end of the dry solids profile, and the feed solution is fed approximately to the maximum point of the dry solids profile and the eluent liquid approximately to the minimum point of the dry solids profile. Part of the separated product fraction is recycled on account of the continuous cyclic flow and as only part of the dry solids profile is removed from the packing material bed.
The cyclical shifting of the feed and recovery points can be performed by using feed and recovery valves disposed along the packing material bed at the upstream and downstream end of each partial packing material bed. If it is desired to recover product fractions of high purity, short phase times and a plurality of partial packing material beds must be employed (the apparatus has corresponding valves and feed and recovery equipment).
In a sequential simulated moving bed method, not all flows are continuous. In a sequential simulated moving bed method the flows can be: feeding of feed solution and eluent liquid, recycling of liquid mixture and recovery of products (two to four or more products; e.g. betaine as a third fraction in beet molasses separation and monosaccharides in cane molasses separation and lignosulphonates in spent liquor separation). The flow rate and the volumes of the different feeds and product fractions may be adjusted in accordance with the separation goals (yield, purity, capacity). The method comprises three basic phases: feeding, elution, and recycling. During the feed phase, a feed solution and possibly also an eluent liquid can be fed into predetermined partial packing material beds, and simultaneously two or even three product fractions can be recovered. During the eluting phase, eluent liquid can be fed into a predetermined partial packing material bed, and during said phases one or even two product fractions can be recovered in addition to the residue. During the recycling phase, no feed solution or eluent liquid can be fed into the partial packing material beds and no products can be recovered. The use of said phases is possible simultaneously in same or different beds.
Finnish Patent Application 882740 (U.S. Pat. No. 5,127,957) discloses a method for recovery of betaine and sucrose from beet molasses using a sequential simulated moving bed method, the chromatographic system therein comprising at least three chromatographic partial packing material beds connected in series, in which method betaine and sucrose can be separated during the same sequence comprising: a molasses feeding phase, in which a molasses feed solution can be fed into one of said partial packing material beds and in which eluent water can be fed substantially simultaneously into another partial packing material bed, a feeding phase of eluent water, and a recycling phase, these phases being repeated either once or several times during the sequence.
U.S. Pat. No. 4,631,129 discloses the separation of sugars and lignosulphonates from a sulphite spent liquor by a process comprising two chromatographic treatments with ion exchange resins in different ionic forms. In the first treatment, the sulphite spent liquor is introduced into a chromatographic column comprising a strong acid cation exchange resin used as column packing material in metal salt form; the metal ion is preferably a metal ion of the spent liquor, usually calcium or sodium. A substantially sugarless fraction rich in lignosulphonates and a fraction rich in sugars are obtained from this column by elution. The latter fraction is subjected to a softening treatment, and its pH is adjusted to be in the range 5.5 to 6.5, whereafter it is introduced into the second chromatographic column containing resin in monovalent form, and a second fraction rich in sugars and a second fraction rich in lignosulphonates and salts are obtained therefrom by elution. It is stated in this patent that the process is capable of recovering sugars, e.g. xylose contained in hardwood sulphite spent liquor, in a very high purity and high yields. However, a drawback of the method of U.S. Pat. No. 4,631,129 is that the dry solids profile, which has been formed in the first chromatographic treatment and in which the components are already partly separated can be destroyed in the softening treatment and pH adjustment and thus may not be effectively utilized in the second chromatographic treatment. The method of U.S. Pat. No. 4,631,129 can be also complicated by the steps of concentration and additional pumping to which the solution is subjected. All of these factors add to investment costs. Furthermore, the method of U.S. Pat. No. 4,631,129 and many prior art chromatographic separation methods are attended by the drawback that they are typically batch methods and are not suitable for fractionating solutions on an industrial scale.
U.S. Pat. Nos. 4,008,285 and 4,075,406 teach recovery of xylose by a chromatographic method. In this method, a pentosan-containing biomass, e.g. wood raw material, is hydrolysed, the hydrolysate is purified by ion exclusion and colour removal and the resultant solution is fractionated chromatographically to obtain a solution rich in xylose. The fractionating methods disclosed in these patents are also batch processes, and only two product fractions are disclosed to be obtained thereby.
It is known that sucrose and betaine are recoverable from molasses by chromatographic separation. U.S. Pat. No. 4,395,430 describes a chromatographic method for the recovery of betai
Heikkila Heikki
Hyoky Goran
Kuisma Jarmo
Lewandowski Jari
Monten Kaj-Erik
Danisco Finland Oy
Kenyon & Kenyon
Therkorn Ernest G.
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