US2431634A

US2431634A - Recovery of juices from sugar muds

Info

Publication number: US2431634A
Application number: US527496A
Authority: US
Inventors: Diaz-Compain Jeronimo
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-04-12
Filing date: 1944-03-21
Publication date: 1947-11-25
Anticipated expiration: 1964-11-25

Description

v Nov. 25, 1947.

J. DlAZ-COMF'AIN RECOVERY OF JUICES FROM SUGAR -MUDS Filed March 2l, 1944 Y l Nov. 25, 1947. J. nlAz-coMPAlN RECOVERY OFVJ'UICES FROM SUGAR MUDS I 2 Sheets-Sheet 2 Filed March 2l,y 1944 Ql Qu Patented Nov. 25, 1947 rse is @Partnr @oer-ics 12,4311534 y Risco'visiti' 10F -JUIoEs IFROMsuene MUDs "Jernimo D'azLColnpain,/Centralisenado,E Cuba rotin-iis) f 114* claims. 41

"This invention "relates to "recovery'oi vjuices :fromsu'gar muds; and it comprises a process of `:treating sugars'cums or mudsj-suc'h as the mud "recovered from 'the usual clarifying units or the A'lter cake recovered from a continuous Yfilter operating onthe cl'arier mud; said process comprising 'alilllying' sucha mud to the bagasse blan- 'ketpass'ing through a -pluralit'y of cane grinding millsat-a"point between the nal mill and the yflast Vpoint at Which'anyeniaceration water is applied to the blanket, 'whereby washing away of f said lmud'with maeeratio'n water 'is avoided and thesug'ar juice/lcontainedin the mud is recoil,- ered;isaid process being preferably conducted by vforming twor separate ba'gasse blankets -from 'the 'bagasse passing through the mills, introducing "the mud between said Ablankets vand passing the resulting assembly through a 'final mill to extract juice therefrom; all as more fully hereinafter set forth and as claimed.

In 'the processor recovering juices from sugar '-.cane the cane islpassed Ythrough a series of crushing or :grinding YVmills.

The crushed cane forms 'what is known'as a'bagasse blanketduring its -passage through `the mills Zand this blanket is Vthereafter used in the furnaces to produce power for the 4sugar manufacturing operations. In the sugar processing operations, which are conducted `in the sugar house"-or boiling house, muds or scums areproduced For example the clarifying units -(clarier`s) Aproduce a mud known 1as cacha'za These mudsorscumsare conventionally treated for recovery of their sugar Values. Usually -they are passed. to a Vcontinuous rotary vacuum --filter Where `line bagasse, known as bagacill, is used as a lter aid.

Owing to the fact that most sugar cane factories have deficient lheat balances, that is, heat balances which require fuel in addition to that supplied by the ba'gas'se, it is frequently necessary to burn the fmuds or the lter cakes fromthe conventional Vcontinuous lters. The 'muds lrepresent about 3.2 per cent of the total cane and vhence, ifsuiiiciently dehydrated, constitute a valuab-le source of fuel. But rthe iilter cakes from the usual continuous `filters contain from 'about 75 to 85 per cent of moist-ure (Zfper cent sucrose). In contrast the bagasse blanket from the .grinding mills contains only `about v50 per cent moisture (3 per cent sucrose). directly to the bagasse blanket before the latter is sent to the `furnaces, as i'sfconventional in many sugar factories, the moisture content of the blan- -ket 4is increased'to about 53.5 per cent, which is,

of course, a decided disadvantage from a fuel standpoint.

It has heretofore been proposed topadd the muds or scums from the sugar house to the ybagasse blanket as it is passing through the rst lmil-l. of the series and vprior to. the-mill or `-rxri-l-ls If the muds are added -jblanket `and has time 'to cool.

supplied with masceration'water. If this p fo- A.practicalto add the'nludsto-thevbagas'se blanket prior to the maceration Water. AIfthis is done,

the top of-the'bagasse blanket becomes slimy and slippery and the grinding eiciency is substantially reduced. Moreover the maceration water, whichkis usually "hot, tends'to dissolve impurities -from the muds and to wash them through the bagasse blanket, 1resulting injucesfof considerably lower purity. This increases the clarication difliculties and Iresults in an inferior sugar of low keeping quality. V ,n I y I have `Adisr'zovneredrthat vthe above difficulties can be avoided by adding'the muds at a point between the nalvmill of the grinding unit and ythe last point at whichanyv maceration water is added. If the "maceraton Water is addedk to the blanket prior to the rnuds, it soaks intgthe When the blanket is then passed through the iinal mill, the macera- -tion water squeezed out does not flush over and wash away the muds `or dissolve the` impurities therefrom, as it does when it is sprayed on top of the muds. n 'Ihemuds are then dehydrated to a moisture content oi about 5G per cent and the jmoisture removed serves as r'e-maceration water in the last mill'to reduce the sucrose content of the bagasse blanket. A double advantage is hereby gained. Moreover the muds soak into the'bag'asse blanket and, Ysince they are not contacted directly with maceration water, they do not become slimy and slippery. The grinding efciencyv--of the grinding unit is not reduced appreciably. s

It is possible in my new process to apply the muds directly-as they arereceived `from the boiling house or 'after they have been dehydrated to a certain citent by'rn'eans oi a continuous filter. The viilter 'cake from rsuch a lter can be applied to the bagasse 'blanket prior to the last mill for example. Itis usually advantageous to mix the Vii-lter 'cake with -water before applying it to the ba'ga'fsls'e bl'zvt'nk'et.y The moisture content of the :filter cake, including"themud, is re ziuce `lto about u per cent, Aw-ll'ereby fits fuel value is greatly enhenbed .V

I'ffinaceration'water is applied at the third from "the Vlast millbut Vnot at thel'ast Aornext tothe last, thernuds can bey applied to the bagasse blanket 'at the intermediate carrier of thenext to last mill. The-moisture contained'in the muds is `then pressed 'ont in the last min and this serves to "macration vvirater `a vshort time to cool and tosoak the mud grinding mill.

into the bagasse blanket before the muds are applied thereto.

A more advantageous method of conducting the present invention is to provide a separate mill for grinding the muds. This mill can be of the conventional two or three-roll type. The bagasse I 4blanket coming from the last mill of the usual grinding unit can then be split in sections, one or two sections being directed to the mud grinding mill. The muds can be applied to one section of the blanket, which can then be passed directly through the mill, but preferably a second section of the bagasse blanket is superposed on top of the muds, whereby the muds are compressed between two bagasse blankets as they are passed through In this fashion no liquid can escape from the muds without passing through a bagasse blanket which serves as a highly eflicient filtering medium. The reincorporation of impurities obtained in this fashion is very in a higher recovery of sucrose, and the muds are dehydrated more efnciently, resulting in a higher j fuel value.

It is evident from the above that, when my method is used, the conventional rotary vacuum filter can be dispensed with. But if it is desired to employ such a filter, for example, when a filter is already installed, it is possible to pass the filter cake to the bagasse blanket directly or to mix it with water prior to such passage. mixed with the filter cake serves as maceration water, resulting in an increased recovery of sucrose.

The low-purity juices recovered from the mill which grinds the muds in accordance with my invention are advantageously recycled as remaceration juices. They can, of course, be treated specially or disposed of in other ways.

My invention can be explained with somewhat greater accuracy by reference to the accompanyl ing drawing in which the several figures constitute flow charts showing three modifications of my process.

In this showing Fig. 1 is a flow chart showing the muds applied at the intermediate carrier of the next to last mili,

Fig. 2v shows the muds applied to the bagasse `blanket between the two final mills, while y Fig. 3 shows my preferred process in which the l muds are introduced between two bagasse blankets passing through a mud grinding mill.

The processes illustrated in the flow charts of the drawing are believed to be obvious from a In Fig. l, for example,

left side of the figure and the resulting bagasse is passed from mill to mill in the form of a blanket and finally to the furnace (not shown) at the right side of the figure. :the first two mills is conducted to the boiling house, while that from the last two mills is delivered to the first mill for re-maceration Maceration water is added at the intermediate carrier of the second mill, while mud from the boiling The juice expressed by house or from the filters is delivered on top of the bagasse blanket at the intermediate carrier of the *next to last mill.

In Fig. 2 the bagasse passesthrough the mills lasbefore but in 'this grinding unit maceration' Any water water is added at the next to the last mill. The muds are therefore added to the bagasse blanket `at a point between the. last two mills morder to avoid washing away of the mud and dissolving of impurities by the maceration water. The juice from the last two mills is separated, that from the last mill being delivered for re-maceration to the second mill, while that from the next to last mill is delivered for re-maceration to the first mill.

In Fig. 3 the bagasse passes through the first four mills as before but is divided into two or three sections after leaving the fourth mill. A fifth mud grinding mill is provided, which may be smaller than the other mills. At least one section of the bagasse is passed as a blanket to this mud grinding mill. The mud from the boiling house is passed to the vacuum filter and the resulting filter cake is first mixed with Water and then deposited on the bagasse blanket passing to the mud grinding mill. Alternatively the mud may bypass the filter, as indicated by dotted lines in the flow sheet. and be sent directly to the bagasse blanket. Preferably a second section of the bagasse blanket is superposed on top of the mud applied to the first section, so that the mud is enclosed between the two blankets as the assembly is passed through the mill. The juice from the next to last mill is used as re-maceration at the first mill. The bagasse blanket and dehydrated mud from the mud grinding mill is united with the remaining bagasse from the grinding unit and sent to the furnace at the right of the figure.

My tests show that my process, as shown in Figs. l and 2, can be applied to the grinding units in which 22 rolls are employed without any detectablereduction in grinding efficiency. In the case of the smaller'units, employing up to 17 rolls, a slight reduction in efficiency is obtained but this is so small that the advantages gained outweigh this slight disadvantage. When a separate mud grinding mill is employed the efficiency of the grinding unit is not affected, while the efficiency of the mud grinding mill is high even when only a single bagasse blanket is passed through this mill.

It is evident that the process as described has several important advantages among which are the following:

1. The mud after being treated by my process has substantially the fuel value of the usual bagasse blanket. The total fuel value of the blanket plus mud is sufficient in many cases to produce power in excess of that required in the sugar processing, and this excess power can be employed for other purposes.

2. The fuel Value of the mud treated by my process is substantially greater than that of the 'filter cake, including the mud, which is obtained from the usual vacuum filters.

3. More sucrose is recovered from the boiling house muds than can be recovered with the use of vacuum filters owing to the lower juice content (50 per cent moisture) of the mud processed in accordance with the present invention.

4. Additional sucrose is recovered from the bagasse blanket for the reason thatthe moisture expressed from the muds serves as maceration water. This is particularly true when the mud is mixed 'with maceration water before being applied to the bagasse blanket.

5. Sugars and nal molasses of better quality are obtained due to superior juice clarification,

since the solids and impurities in the muds adhere to the bagasse blanket.

6. The roll surfaces do not become glossy and slippery because mud solids remain inside the bagasse blanket and are not contacted with the rolls after being washed with maoeration water.

7. The usual rotary vacuum lter can be dispensed with, if desired, resulting in a substantial saving, especially in maintenance.

While I have described what I consider to be the most advantageous embodiments of my invention, it is obvious, of course, that many modifications can be made in the specic procedures described without departing from the purview of this invention. The recycling of the expressed juices to be used for re-maceration can be accomplished in several different ways, depending upon how many mills and how many rolls are employed. If a special mud grinding mill is employed, this can be located at any convenient position with respect to the other mill units. Conventional means can be used for removing bagasse from the bagasse blanket coming from the grinding mill unit, in order to form the blanket or blankets to be used lin the mud grinding mill. And it is possible to deposit the mud or lter cake on one bagasse blanket followed by enclosing this assembly between two additional bagasse blankets. The bagasse blankets passing to the mud grinding mill may be of the order of 4 inches thick while the layer of mud may have a thickness of approximately inch. Other modifications of my invention which fall within the scope of the following claims will be immediately evident to those skilled in the art.

What I claim is:

1. In the process of recovering juices from sugar muds, wherein sugar cane is passed through a series of cane grinding mills in the form of a bagasse blanket, the step which comprises depositing a sugar mud on said bagasse blanket before the blanket passes through the last mill of said series but subsequent to the application of any maoeration water to said blanket.

2. The process of claim 1 wherein said mud is applied on said bagasse blanket at the intermediate carrier of a mill receiving no maceration water, said blanket being then passed through the nal mill.

3. The process of claim 1 wherein maceration water is added to the next to last mill of the series while the mud is applied to said bagasse blanket at a point between the last two mills.

4. The process of claim 1 wherein said mud is the lter cake from a filter operating on a sugar mud and wherein said lter cake is mixed with maoeration water prior to deposition on said bagasse blanket.

5. In the process of recovering juices from sugar muds, wherein sugar cane is passed through a series of cane grinding mills in a grinding unit, the cane being formed into a bagasse blanket during said passage, the improvement which comprises dividing the bagasse blanket from said grinding unit into at least two sections, passing one of said sections in the form of a bagasse blanket through a mud grinding mill and depositing a sugar mud on said last mentioned bagasse blanket before it passes through said mud grindmaceration water to the blanket.

6. The process of claim 5 wherein said sugar vmud is cachaza derived from a boiling house clarifier.

'7. The process of claim 5 wherein said sugar mud is a lter cake from a filter operating on a boiling house sugar mud.

8. The process of claim 5 wherein said sugar mud is a filter cake from a filter operating on a boiling house sugar mud and wherein said lter cake is mixed with maoeration water prior to deposition on said bagasse blanket.

9. In the process of recovering juices from sugar muds, wherein sugar cane is passed through a series of cane grinding mills in a grinding unit, the cane being formed into a bagasse blanket dur-V ing said passage, the improvement which comprises dividing said bagasse blanket into at least two sections, depositing a sugar mud on top of one of said sections, applying a second section on top of said mud, and then passing the resulting assembly through a mud grinding mill to express the juices and any added Water from said mud.

10. The process of claim 9 wherein said sugar mud is cachaza derived from a boiling house clarier.

11. The process of claim 9 wherein said sugar mud is a lter cake from a filter operating on a boiling house sugar mud.

12. The process of claim 9 wherein said sugar mud is a filter cake from a filter operating on a boiling house sugar mud and wherein said filter cake is mixed with maoeration water prior to passage through said mud grinding mill,

13. The process of claim 9 wherein juices recovered from said mud grinding mill are used for re-maceration, being passed to a mill in front of a mill receiving maoeration water.

14. In the process of recovering juices from sugar muds, wherein sugar cane is passed through a series of cane grinding mills in a grinding unit, the cane being formed into a bagasse blanket during said passage, the improvement which comprises dividing the bagasse blanket from said grinding unit into at least two sections, passing one of said sections in the form of a bagasse yblanket through a mud grinding mill, depositing a sugar mud on said last mentioned bagasse blanket before it passes through said mud grinding mill and subsequent to the application of any macerating water to the blanket, and recycling the low-purity juice recovered from said mud grinding mill as re-maceration juice to a mill in front of said mud grinding mill.

JERNIMO DAZ-COMPAIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,266,882 Thomas et al. May 21, 1918 1,528,501 Morrisson Mar. 3, 1925 1,688,184 Hartmanns Oct. 16, 1928 1,824,875 Copp Sept. 29, 1931 1,911,246 Spaulding May 30, 1933 2,027,422 Fortier Jan. 14, 1936 2,054,556 Copp Sept. 15, 1936