CN1029564C - Improved low-temp and strong-alkali sulphurous acid method for refining process in cane sugar prodn. - Google Patents

Abstract

The present invention provides a new technological purification method with a high purification effect in order to improve the purification technology for producing sugar by a sulfurous acid method, which can obviously enhance the quality and the recovery rate of white granulated sugar produced by a sulfurous acid method. A procedure of impurity removal by strong alkali (the pH value is 11) and auxiliary clarification by phosphoric acid is added on the basis of the purification technology by a sulfurous acid method, two isoelectric points (the pH value is 11 and 7) are adopted, and the purpose of high-efficiency impurity removal is achieved by two times of separation of sink-float separation and precipitation separation. The technological procedure is implemented by adding equipment of a sink-float machine, etc. in the purification working stage of the original sulfurous acid method, and the investment is low. The method of the present invention has the purification effect that the average color value of clarified juice is 2154ICUMSA; the average turbidity is 737; the removing rate of colloid reaches 53.8%; the purity is enhanced by AP+3.64 and GP+2.73.

Description

Improved low-temp and strong-alkali sulphurous acid method for refining process in cane sugar prodn.

The invention belongs in the cane sugar manufacture industry, strengthen the novel method of sulfurous method cleaning technique.

Cane sugar manufacture industrial production arable land white sugar generally adopts two kinds of methods, i.e. carbonatation process and sulfurous method.The cleaning technique of carbonatation process is to utilize the high basicity of a carbon full charge to remove a large amount of non-sugars, two carbon full charges are removed CaO and nonsugar remaining in the sugarcane juice, be characterized in utilizing milk of lime and carbonic acid gas to make finings, with three iso-electric point (pH11, pH8.2-8.4 pH7) separates with twice whole-juice filtering.The White Sugar Quality that this method is produced is better, but complex process, facility investment height, consumes amount of lime and Duo ten times approximately than sulfurous method, has the problem of filter mud serious environment pollution.The cleaning technique of sulfurous method is to introduce SO on the basis of lime method ₂, utilize milk of lime and sulfurous gas to make finings, this method technology is simple, reduced investment, only with an iso-electric point (pH7) flash liberation (post precipitation filtration mud juice) removal of impurities.But non-sugared impurity and the pigment that can remove are few, and sugarcane juice purity improves little, are generally ± 0.5GP, the easy flavescence of color during commerieal sugar is stored, and the sugar part rate of recovery is low.For a long time, international and domestic all have many people seeking to improve the peace and quiet novel process of sulfurous method, but all different with the present invention, and do not see to drop into and use.

The present invention is low for remedying the sulfurous method purification effect, removes the weak shortcoming of organic impurity ability and to propose place's purification effect height, less investment, cost low, can obviously improve the White Sugar Quality that sulfurous method produces and the cleaning technique novel method of the rate of recovery.

The novel method of cleaning technique is to adopt the pH11 of carbonatation process sugaring cleaning technique, two iso-electric points of pH7 of sulfurous method sugaring cleaning technique, twice removal of impurity.On the sulfurous method basis, increase the auxiliary clarification of a high-alkali removal of impurities and phosphoric acid flow process, it is a kind of method of strengthening the sulfurous method cleaning technique.Owing to increased by one section flow process, also increased an essential equipment-floating device.Handle through pre-ash from the mixing juice that squeezing is come out, promptly add an amount of milk of lime control pH and be 7-8 and add in advance phosphoric acid 100-150ppm/(phosphoric acid amount to the sugarcane amount than) this mixing juice enters peace and quiet workshop through once being heated to 50-60 ℃, adding milk of lime after whisking machine is got blisters makes the pH value of mixing juice reach 11, in the phosphoric acid mixing tank, add phosphoric acid 100-200ppm(phosphoric acid amount afterwards to sugarcane amount ratio) and flocculation agent (using T type polyacrylamide) 3ppm, by entering floating device behind the static mixer, make the above-mentioned main lye that has reacted carry out dissolved air flotation, scum silica frost is drained by floating device top, isolated juice is gone into lower floor's sedimentation, settlement separate be clear juice once, the stove drying that once clear juice enters the sulfurous method cleaning technique then, neutralization, the subsider juice that second-heating obtains through precipitate and separate after 98-105 ℃ again is the clear juice of secondary.To drawing once, the clear juice of secondary is exactly the complete peace and quiet flow process of the present invention from the pre-grey mixing juice of handling of process.Be not difficult to find out that its technical characterictic is, has increased the auxiliary clarification of high-alkali (pH=11) removal of impurities and phosphoric acid flow process on the basis of sulfurous method cleaning technique.Two iso-electric point: pH11 and 7 have been adopted, through drifting along and precipitating twice and separate, to reach the purpose of efficient impurity removal.

Accompanying drawing 1 is purification method setting drawing of the present invention, and Fig. 2 is a schema.

Among the figure: [2] well heaters of [1] mixed juice case [3] milk of lime buckets [4] whisking machines [5] phosphoric acid buckets [6] phosphoric acid mixing tanks [7] once clear juice case [12] stove drying neutralizer [13] second heater [14] settling bowl [15] subsider juice (the clear juice of secondary) case [16] scum silica frost mud juice thermotank [17] vacuum suction filter of tower [8] flocculation agent case [9] static mixer [10] floating device [11] that flocculates in advance.

Technology of the present invention is achieved in that the mixed juice that will squeeze out is (about 80Ap, 20 ° of BX) adding in advance earlier the pH value that milk of lime makes mixed juice in [1] reaches 7-8 and adds phosphatase 11 00ppm(phosphoric acid and sugarcane ratio) afterwards, be pumped into heater [2], once heat, temperature is 50-60 ℃. This temperature is lower than a heating-up temperature of former sulfurous method cleaning technique. Can cause a large amount of destroyed adverse consequences of reduced sugar under the pH11 highly basic condition so that the lower step will add milk of lime if the temperature that once heats is higher than 60 ℃, be difficult to absorb SO in the time of also can affecting stove drying₂; If once the temperature of heating is lower than 50 ℃, not only reaction speed is too slow but also Ca₃（PO ₄） ₂Precipitation is incomplete, and impurity-eliminating effect is poor, and causes the serious consequence of evaporator fouling; So the control temperature is take 55 ℃ as good. Hot mixed juice enters frothing machine [4], has two to add entrance in [4] import department; One is that main ash adds entrance, namely, milk of lime flows out from milk of lime bucket [3], [4] in the front adding sugarcane juice, control its addition, make mixed juice pH value bring up to 11, (pH11 is the best isoelectric point of removing non-sugar impurities in the sugarcane juice). Another mouthful adds entrance for compressed air, in order to add an amount of compressed air, increases sugarcane juice hollow tolerance, so that sugarcane juice enters the separation of fully floating in the floating device. Reach take floating as main, take heavy as auxiliary, the basic separation purpose of the combination of drifting along. Mixed juice, fully mixes in frothing machine [4] to pH11 and after adding an amount of compressed air at main ash. And the bubble that diameter is big chops up, to satisfy next step " needs of come-up. Be provided with a static phosphoric acid blender [6] at frothing machine [4] outlet conduit, the pH value is modulated comes out to 11 mixed juice (claiming main lye) from [4] to be pressed into 100-200ppm(to the sugarcane ratio by phosphoric acid bucket [5] before entering [6]) 20 times of industrial phosphoric acid (85%) industrial phosphoric acid dilute with waters), enter [6] and fully mix, continue afterwards to flow to pre-flocculation tower [7] purpose and be allowing main lye have certain reaction time to allow calcium phosphate fully precipitate and adsorb in a large number non-sugar impurity and pigment in the sugarcane juice as heavy clear agent. Then add 3ppm(to the sugarcane ratio by flocculant case [8] to liquid stream) flocculant, make the contaminant particles bridging in the sugarcane juice become the bigger agglomerate flocculate of volume, changed the volume of suspension particle, utilize the adhesion of bubble and particle to increase buoyancy lift, buoyance lift speed is beneficial to the separation of drifting along. Floating device [10] is the cylindrical open-top receptacle at a band cone end, is divided into three layers: the upper strata is the come-up layer, lower two-layer be settled layer. The liquid that flows out through static mixer [9] flow to into floating device [10] and thereon floating layer stopped about 15-20 minute. Scum silica frost is naturally gone up the removal of warp float scraper plate and is sent into scum silica frost mud juice thermotank [16] along the scum silica frost ring; Clear juice changes lower floor's sedimentation over to through level control box, and the mud juice of come-up layer bottom enters bottom and bottom mud juice from central downtake and puts in the lump scum silica frost mud juice thermotank [16] scum silica frost and mud juice and deliver to vacuum suction filter [17] with steam heated after to 85-95 ℃ in [16] and filter. Filtrate (filtered juice) pump is clear juice case [11] extremely once. In floating device [10] the lower floor settled layer clear liquid account for the mixed juice total amount 80% in [10] large and small endless tube of device drain into once clear juice case [11] and filtered juice (account for mixed juice total amount 15%) in the lump pump to Sulphitation and Neutralization device [12] carry out stove drying. Intensity of sulfitation is 18-25ml, makes it reach 7.0-7.3 with the pH value of the clear juice that neutralizes. The defeco-sulfitated juice that comes out through [12] is sent into sedimentation basin [14] again and is carried out precipitate and separate after after-heater [13] is heated to 98-105 ℃, defeco-sulfitated juice enters that [14] are front to add 1ppm(to the sugarcane ratio by [8]) flocculant. Sedimentation basin [14] bottom mud juice directly enters vacuum suction filter [17] and filters, and filtered juice is pumped to [11]. The multilayer size endless tube discharge of sedimentation basin supernatant liquid (the clear juice of secondary) in [14] sent into subsider juice case [15] and is pumped to next multiple-effect evaporation operation.

Embodiment:

Carried out the continuous 8 days industrial experimentation of this technology on the 2000 ton per day scale series of 1990/1991 press for extracting juice Ji Zaijing bank sugar refinery.Increased floating device in the peace and quiet workshop of this factory (sulfurous method), whisking machine, static mixer, phosphoric acid neutralizer, the tower that flocculates in advance, scum silica frost mud juice well heater etc.From the pre-grey pH7.0 of mixing juice elder generation that squeezing machine comes out, preprocessing industry phosphoric acid compares 150ppm to sugarcane continuously, be pumped to peace and quiet workshop and once heat (50-60 ℃), and add milk of lime master ash to pH11, enter whisking machine, get blisters, mix through machinery, measure continuous processing industry phosphatase 11 50ppm/ to the sugarcane ratio with spinner-type flowmeter, after mixing, enter pre-flocculation tower, stop outflow in about 2 minutes, add flocculation agent (T type polyacrylamide) 3ppm/ again, after static mixer mixes, enter in the floating device the sugarcane ratio, stop about 40 minutes come-ups, settlement separate.Scum silica frost is scraped through the scum silica frost ring by scraper plate and is sent to scum silica frost mud juice thermotank, and mud juice is subjected to static pressure to be heated to 85-95 ℃ in the lump to scum silica frost mud juice thermotank, and filters toward vacuum suction filter from force feed.In the settling vessel effusive once clear juice and filtered juice all enter clearly the juice case in the lump pumping stove drying neutralizer carry out stove drying and neutralize.Intensity of sulfitation 20-22 milliliter, in and pH7.0-7.3, defeco-sulfitated juice directly is sent to settling tank again and carries out precipitate and separate after second-heating (98-105 ℃).Before settling tank, add flocculation agent 1ppm(to the juice ratio), average color value of clear juice is 2154ICUMSA after the settling tank secondary sedimentation, turbidity is 737, colloid clearance 53.8%, purity improves AP+3.64, GP+2.73.

" low temperature highly basic-improvement sulfurous method cleaning technique effect is tangible in employing.This method is utilized the high-alkali best iso-electric point of pH11 under 55 ℃ of lesser tempss, remove non-sugared impurity, especially colloid in a large number, organism.Colloidal organic matter is removed more than 50% in the clear juice after the separation of drifting along, and turbidity reduces significantly, from original 2000-3000.Reduce to about 500-1000, colour also has greatly improved, the commerieal sugar quality of producing is significantly improved, its physical and chemical index guarantees to reach the first sugar standard, near the top grade sugar level.The comparison of every technology quality index of technology of the present invention that following table is classified as and sulfurous method cleaning technique actual achievement: (table is seen the literary composition back)

Advantages such as it is obvious that the present invention has peace and quiet effect, easy and simple to handle, and it is few that low equipment investment, finings consumption increase expense, good in economic efficiency, thereby broad prospect for its application is arranged.

Index project unit sulfurous method is of the present invention

General actual achievement expectation index test actual achievement

Peace and quiet front and back purity difference AP ± 0.5 2 ± 0.5+2.78

St ° of 90-100 of subsider juice colour

2154

ICUMSA

The pure and impure degree millimeter of subsider juice ≈ 60 200 ± 20＞200

Subsider juice calcium salt content CaO%BX 0.4-0.6 0.5 0.43-0.52

Colloid clearance %=35＞50 53

Claims (2)

1, a kind of improved sulfurous method cane sugar manufacture purification method, comprise that mixing juice is through pre-ash, add phosphatase 11 00-150ppm/ to the sugarcane ratio, once heating, the stove drying neutralization, second-heating, the precipitate and separate step, it is characterized in that a Heating temperature is 50-60 ℃, add milk of lime afterwards and make mixing juice pH value rise to 11, and add phosphatase 11 00-200ppm/ to sugarcane than and flocculation agent 3ppm/ to the sugarcane ratio, fully react then and the separation of drifting along, obtain once clear juice and mud juice respectively, once clear then juice is finished peace and quiet process with grade in stove drying.

2, a kind of for implementing the custom-designed floating device of the described method of claim 1, it is characterized in that floating device is the cylindrical open container that conical bottom is arranged, be divided into three layers, the upper strata is made up of scraper plate, level control box, central downtake except that vessel space for the come-up layer, two-layer down is settled layer, has a plurality of endless tubes to be used to drain juice clearly in the settled layer.

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