CN109438207A - A kind of method of acetate starch production process recycling acetaldehyde - Google Patents
A kind of method of acetate starch production process recycling acetaldehyde Download PDFInfo
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- CN109438207A CN109438207A CN201811459094.3A CN201811459094A CN109438207A CN 109438207 A CN109438207 A CN 109438207A CN 201811459094 A CN201811459094 A CN 201811459094A CN 109438207 A CN109438207 A CN 109438207A
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Abstract
The present invention relates to a kind of methods of acetate starch production process recycling acetaldehyde, are included in starch conversion and keep vacuum in the process, extract the aldehydes gas that the volatilization that acetic acid esterified reaction generates is overflowed；It after esterification, adjusts under starch milk system to the subacidity of pH5.0 ~ 6.5, stirring is warming up to 40 DEG C ~ 45 DEG C, continues to extract the aldehydes gas that volatilization is overflowed under vacuum；The gas pump extracted from reaction kettle is toward absorption tower, and with buck condensed absorbent aldehydes gas therein, absorption tower guarantees that the temperature of buck absorbing liquid is not higher than 20.8 DEG C of boiling point of acetaldehyde with circulating chilled water；The gas come out from buck absorption tower, it is taken out again toward activated carbon adsorber or case and adsorbs the pernicious gases substances such as wherein remaining acetaldehyde, finally recycle acetaldehyde product, the air for giving off colorless and odorless cleaning, it is positive to keeping the discharge amount of good production environment, reduction acetate starch production process acetaldehyde organic volatile (Vocs) to have the function of.
Description
Technical field
In the production process that vinylacetate prepares acetate starch, the present invention relates to wherein acetaldehyde reaction products
A kind of method of recycling.
Background technique
Acetate starch is a kind of important converted starch, and acetate starch of the acetyl content less than 2.5% is the country
Allow in GB2760 standard using food additives, can be used as thickener, stabilizer and binder, if using certain
Crosslinking Treatment, application performance more preferably, are widely used in many industries such as food, papermaking and weaving.
It is certain with acetic anhydride or vinylacetate processing ative starch cream, effect under conditions of alkalinity and room temperature ~ 40 DEG C
After time, by processing steps such as washing purification, centrifugation, dry, crushing and sievings, the acetate starch of tasteless white can be obtained
Powder-product.Vinylacetate (CH2=CHOCOCH3) it is colourless liquid, the ether taste with sweet tea；Be slightly soluble in water, be dissolved in alcohol, acetone,
Benzene, chloroform.It is easy amylogenic acetate derivative with vinylacetate esterification starch, for industrial common method, it is logical
Parlkaline is catalyzed transesterification and generates acetylization reaction, main body reaction equation are as follows:
St-OH + CH2=CHOCOCH3 → St-O-COCH3 + CH3CHO
It reacts while releasing acetaldehyde (CH3CHO) product.Under alkalinity, the acetate starch (St-O- of above-mentioned reaction generation
COCH3) by alkali effect can be occurred hydrolysis, following hydrolytic side reactions can also occur for vinylacetate, generate sodium acetate and
The by-product of acetaldehyde, it should which the suitable process conditions of optimum choice inhibit the generation of vinylacetate hydrolytic side reactions as far as possible.
CH2=CHOCOCH3 + NaOH → CH3COONa + CH3CHO
So in the reaction system, vinylacetate is regardless of generating acetate starch with starch storage crop, or acts on and occurring with water
Hydrolytic side reactions, the vinylacetate for adding 1 mole (86g) will generate 1 mole acetaldehyde (46g) product.1 contains 10 tons of shallow lakes
The reaction kettle of powder [powder cream concentration is generally 35% ~ 40%(w/w)], the general dosage of vinylacetate are 5.0% pair of starch, then need
500 kilograms of vinylacetate are wanted, about 266.44 kilograms of acetaldehyde for reacting generation.Starch acetate after reaction, by washing
Purification is washed, the products such as these acetaldehyde, sodium acetate or pollutant enter sewerage depending mainly on mother liquor and washing lotion water together and carry out
Processing.
Acetaldehyde is a kind of aldehyde, is colourless mobile liquid, and relative density 0.785,20.8 DEG C of boiling point, has by -121 DEG C of fusing point
Penetrating odor can dissolve each other with water and ethyl alcohol, inflammable volatile, and steam and air can form explosive mixture.Though acetaldehyde is easy
It is dissolved in water, but its boiling point is only 20.8 DEG C, readily volatilized in the summer temp high period in time at sewage holding pond, shape
It is distributed everywhere at irritant gas, pollutes environment, influenced the physical and mental health of resident near enterprise personnel and enterprise, be current
Perplex an environmental issue of converted starch manufacturing enterprise.
Summary of the invention
Acetaldehyde situation is led to the problem of acting on starch preparation production acetate starch as esterifying agent using vinylacetate,
The present invention provides a kind of method of acetate starch production process recycling acetaldehyde, and it is raw to can avoid or eliminate this puzzlement converted starch
Produce the environmental issue of enterprise.
The purpose of the present invention is achieved through the following technical solutions.
A kind of method of acetate starch production process recycling acetaldehyde, including size mixing, esterification, neutralization, washing, take off
Water, drying steps, in esterification and neutralization stage, the acetaldehyde product that vinylacetate reaction is generated, reaction system not
Same pH range is extracted starch milk as aldehydes gas, is then condensed on buck absorption tower using vacuum, temperature-rising method
It absorbs, the gas come out from buck absorption tower, then carries out adsorption treatment with active carbon adsorption equipment, realize clean emptying.
Further, the reaction kettle of converted starch is sealed pressure reaction kettle, is equipped with the aldehydes gas report of water proof and dust proof
Alert detector.
Further, the temperature needed in esterification stage, reaction temperature according to converted starch reaction, in vinyl acetate
Before ester stream adds, keep the vacuum degree of reaction kettle for 0.08 MPa or more, and the vacuum maintained like in entire esterification reaction process
Degree constantly detaches volatilization and spills into the aldehydes gas of reaction kettle upper space to buck absorption tower.
Further, the temperature needed in esterification stage, reaction temperature according to converted starch reaction, in vinyl acetate
Before ester stream adds, keeping the vacuum degree of reaction kettle is 0.08 MPa or more, with the progress of esterification, when the vacuum of reaction kettle
Degree is 0 or when having positive pressure, just opens vacuum pump and detaches volatilization and spills into the aldehydes gas of reaction kettle upper space to buck absorption
Tower.
Further, in neutralization stage, pH to 5.0-5.5 is neutralized with hydrochloric acid in starch milk, is warming up to 40 DEG C ~ 45 DEG C, is kept
The vacuum degree of reaction kettle is 0.08 MPa or more, stirs 0.5 ~ 1.0 hour, then with aqueous slkali tune pH to 5.5-6.55,40
DEG C ~ 45 DEG C of (preferably 43 DEG C ~ 45 DEG C) heat preservations, and keeping the vacuum degree of reaction kettle is 0.08 MPa or more, it stirs 0.4 ~ 0.6 hour,
Vacuum pump is kept it turning on, volatilization is detached and spills into the aldehydes gas of reaction kettle upper space to buck absorption tower.
Further, absorbing liquid used in absorption tower, is absorbed with water, but is absorbed with the alkaline water of pH9.5 ~ 10.5, is being inhaled
Suitable alkali is added during receiving.
Further, the operating temperature of absorbing liquid used in absorption tower, in entire absorption process, the temperature of buck absorbing liquid
At 20.0 DEG C hereinafter, being maintained at 10 DEG C ~ 15 DEG C by cooling.
Further, absorbing liquid quality quantity used in absorption tower be 5 times of quality quantity of the acetaldehyde that preparation absorbs with
On, preferably 10 times of quantity or more, assimilation effect is more preferable.
Further, the stainless steel of 500 ~ 800mm, the Pall ring or Raschig ring of ceramics or plastics material are set in absorption tower
Filler improves the absorbability of buck.Most handy ceramic Pall ring, dimensions are unlimited.
Further, the air finally to be come using activated carbon adsorption device equipment adsorption cleaning buck absorption tower, activity
Charcoal column, spherical and/or cellular active carbon, can be selected the activated carbon adsorber or adsorption box product of existing maturation.
In the industrial production, vinylacetate prepares the general technology process of acetate starch, such as Fig. 1.
In above-mentioned process, the stage (stage of step 3) that acetaldehyde is reacted in starch esterification starts to generate, with reaction into
Row is raw cumulative without stopping pregnancy, is dissolved in starch milk or is volatilized into the upper space that gas enters reaction kettle.As reaction kettle seals
Property it is bad, these volatilization aldehydes gas may also come out and pollute production environment.The present invention is according to vinylacetate system
The truths such as physicochemical characteristic, Producing reason and the position of appearance of the process flow of standby acetate starch and acetaldehyde are (in step
3 stage starts not stopping pregnancy life occur, is mainly gathered in step 4), on existing existing acetate starch production line, leads to
It crosses and increases certain technical equipment transformation such as cooling device, alkaline solution absorption tower, charcoal trap and storage tank, do not influence original
Acetate starch production, the method for having developed a kind of acetate starch production process recycling acetaldehyde product, process flow ginseng
See Fig. 2.
Specific and main step of the invention, is described below:
1, referring to the flow chart for comparing Fig. 1 and Fig. 2, the manufacturing and its operation of acetate starch of the invention and original phase
Than being basically unchanged, recycled primarily directed to the acetaldehyde product generated in Modified Starch Production system.Other starch
Size mixing, temperature adjustment, the process conditions for adjusting pH and acetate esterification and its (the vinylacetate dosage, reaction pH, temperature such as operation
Degree and time and agitating mode and intensity etc.), water-washing step 5 and its later processing step, can with it is original.
2, in the present invention, it is desirable that the reaction kettle for carrying out starch conversion should be autoclave pressure, and good airproof performance is equipped with emptying
The devices such as the aldehydes gas alarm detection instrument of valve, pressure vacuum gauge and water proof and dust proof.
3, it in the step 3 starch denaturalization stage of reaction, before stream plus vinylacetate start esterification, opens vacuum pump and takes shallow lake away
The air of reaction kettle headspace above powder cream, vacuum degree >=0.08 MPa；With the progress of esterification, especially in reaction temperature
It is higher, for example under 35 DEG C and/or temperatures above, acetaldehyde product will more be volatilized into gas, spill into starch milk to reaction kettle
Among the space on top, when the vacuum degree in reaction kettle is 0 or slightly (just) pressure pressure, opens vacuum pump and extract starch
(acetaldehyde) gas of reaction kettle headspace above cream, to subsequent alkaline solution absorption tower and the absorption tower equipped with active carbon or
The device of case etc. passes through cold buck liquid condensing and absorbs acetaldehyde therein, using the aldehydes gas of activated carbon adsorption remnants,
4, the step 4-1 and 4-2 after esterification is warming up to 40 DEG C ~ 45 DEG C, is stirred in dilute hydrochloric acid and pH5.0-5.5
It mixes 0.5 ~ 1.0 hour；Diluted alkaline is adjusted to pH5.5-6.5, is warming up to 40 DEG C ~ 45 DEG C, stirs 0.4 ~ 0.6 hour.In the mistake of step 4
Journey, always on vacuum pump will spill into (acetaldehyde) gas of reaction kettle headspace from starch milk volatilization, be drawn into alkaline solution
Absorption tower and absorption tower equipped with active carbon, pass through cold buck liquid condensing and absorb acetaldehyde therein, inhale using active carbon
The aldehydes gas of attached remnants；Or the pressure pressure condition of the gas in visual response kettle, vacuum pump is opened in due course extracts reaction
(acetaldehyde) gas in kettle is to absorption plant, and the operation of the unlatching pumping of such interval is more energy saving, but its efficiency for recycling acetaldehyde
It is slightly worse.
In step 4, the temperature for stirring system is higher, wherein the acetaldehyde volatilization dissolved also is easy, but starch passes through acetate
After esterification, gelatinization point is lower, if the temperature of system is higher, has such as been increased to 50 DEG C or more, acetate starch therein
Particle will be significantly swollen, and part is possibly even gelatinized, and influence the preparation production of acetate starch, therefore, system temperature control
System is at 40 DEG C ~ 45 DEG C, preferably 43 DEG C ~ 45 DEG C.
Acetaldehyde is soluble easily in water, in alkaline OH-Under the action of, it is easier to act on water.When acetaldehyde solution is in acetaldehyde boiling point
When temperature on 20.8 DEG C is stored, generally with the raising of acetaldehyde solution pH, acetaldehyde therein is more difficult to volatilize.Therefore esterification is anti-
After answering, step 4-1 in dilute hydrochloric acid and starch milk pH be 5.0-5.5, the higher temperature on acetaldehyde boiling temperature
(40 DEG C ~ 45 DEG C) carry out acetaldehyde volatilization removing work.But under the acidity of the pH value < 5.0 of system neutralization, although removing is waved
The rate for sending out acetaldehyde is very fast, but acts on 1.0 hours at 40 DEG C ~ 45 DEG C, the viscosity characteristics of Dichlorodiphenyl Acetate ester starch is generated undesirable
It influences, therefore selects pH for 5.0-5.5, most preferably 5.1 ~ 5.3.
In step 4-2, system is adjusted to pH5.5-6.5 with diluted alkaline, refers to produce the pH physics and chemistry of acetate starch product quality
Target requirement, up to pH6.0 ~ 6.5, at this pH and 40 DEG C ~ 45 DEG C, then are stirred under vacuum 0.4 ~ 0.6 hour, further extract
Acetaldehyde in converted starch cream out.
Therefore, the present invention is mainly at two of pH9.0 ~ 10.0, the alkalescence that pH is 5.0 ~ 6.5 and subacidity to weakly acidic pH
Different pH ranges is higher than the method for acetaldehyde boiling point by system heating, and under vacuum, stirring promotes to dissolve the second in starch milk
Aldehyde is volatilized into gas, and is pulled out absorption recycling.
5, the structure on alkaline solution absorption tower is configured similarly to packed column, but is not provided with spray equipment, more simply.From reaction kettle
The gas containing acetaldehyde of top extraction by the pipeline and check valve of heat preservation, from the pipeline of the lower position on alkaline solution absorption tower into
Enter in tower, be finally the air-out apparatus of the inverted flat shower of form, gas is in the form of gas-liquid is steeped from air-out apparatus
Stomata overflow, then tiltedly walk to rise, 300 ~ 400 millimeters of air-out apparatus top place is packing support plate, be filled with 500 above ~
The Pall ring or Raschig ring filler of 800 millimeters high of stainless steel or ceramic material, buck absorbing liquid submerged carriers layer.If with modeling
Expect the Pall ring or Raschig ring filler of material, they can float on the upper layer of absorbing liquid, need to install filler again on packing layer top
Support plate pushes down the filler of floating.In terms of the various aspects such as cost performance and maintenance, select ceramic Pall ring filler best.Ceramic Bauer
Ring gauge lattice size all selects the ceramic Pall rings or Φ 38, Φ 50 each 50% of Φ 38 without special and specific prescribed requirement
Ceramic Pall ring etc., it is all feasible.1000 millimeters or more of buck absorbing liquid ullage are the cavity on absorption tower, on
Portion is gas outlet, and the gas of extraction is toward activated carbon adsorption device, then empties.
Due to being vacuum inside reaction kettle, alkaline solution absorption tower should be placed in the lower part of converted starch reaction kettle, avoid
Alkaline solution therein passes through the exhaust pipe suck-back of reaction kettle, is punched into reaction kettle.
The present invention is in alkaline solution absorption tower, and by selecting several aspects such as suitable absorbing liquid, operating temperature, condensation is inhaled
The aldehydes gas for spilling of volatilizing is withdrawn in reaction kettle.
(1) acetaldehyde is soluble easily in water, under alkaline condition, is easier to act on hydrone, balance forms acetaldehyde hyrate (a
Gem-diol), more stable at room temperature.Effect equation formula is as follows:
CH3CHO + H2O ≒ CH3CH(OH)2
Therefore, the absorbing liquid in alkaline solution absorption tower can be pure water, with sig water (sodium carbonate, sodium hydroxide) by the pH value of water
9.5 ~ 10.5 are adjusted to, the assimilation effect of such buck is more preferable.
(2) buck in absorption tower constantly absorbs acetaldehyde, and pH value will gradually decrease, and buck suction can be monitored frequently with pH meter
The variation of liquid pH value is received, decision adds suitable carbonic acid soda lye, the pH value of absorbing liquid is made to be maintained at 9.5 or more.
(3) buck in absorption tower constantly absorbs acetaldehyde, and acetaldehyde concentration will be increased constantly.When the acetaldehyde quality of absorbing liquid
Concentration continues the reduced capability for absorbing aldehydes gas close to 30%.When the acetaldehyde mass concentration of water absorbing liquid is near or above 20%,
All or part of absorbing liquid is discharged, replaces or supplement fresh buck.
(4) 20.8 DEG C of the boiling point under acetaldehyde normal pressure in converted starch reaction kettle (is more higher than by improving the temperature of system
The boiling temperature value of acetaldehyde), (vacuum degree >=0.08 MPa) as far as possible forces out acetaldehyde therein volatilization under vacuum.In alkaline solution
It is then that under normal pressure, the temperature by reducing absorbing liquid [is more lower than (0.0 DEG C or less of boiling temperature value of acetaldehyde in absorption tower
Also improper)], the easier condensation of aldehydes gas, namely be also easy to be absorbed by buck.
From the decimated next aldehydes gas of converted starch reaction kettle, temperature is 20 DEG C ~ 45 DEG C.In step 4-1 and 4-2
Stage, the gas temperature of extraction are 40 DEG C ~ 45 DEG C, are higher than 20.8 DEG C, and the alkaline solution in absorption tower absorbs acetaldehyde therein, also can
The heat for absorbing acetaldehyde condensation heat therein etc., leads to the temperature rise of absorbing liquid, further absorbs effect so as to influence absorbing liquid
Fruit, therefore the temperature of the alkaline solution in absorption tower should relatively be far below 20.8 DEG C, at 15 DEG C or less.In absorption process, pass through
Circulating chilled water constantly takes away heat, and keeping the operating temperature of buck absorbing liquid to be 10 DEG C ~ 15 DEG C is advisable, and has both guaranteed good acetaldehyde
The effect of condensed absorbent, and the too many energy is not consumed.The control of the operating temperature of absorption tower buck absorbing liquid is particularly important.
(4) (acetaldehyde) gas extracted from reaction kettle, is entered in buck absorption tower by check valve, from inverted flower
Spill mouth to enter in tower, then by 500 ~ 800 millimeters of high Pall ring fillers, (acetaldehyde) gas will fully be connect with alkaline solution
Touching, under buck comparatively fresh and the lower situation of temperature, acetaldehyde therein 100% can almost be absorbed by buck, few remaining meeting
Spill into the top on alkaline solution absorption tower.
If the quality of buck absorbing liquid is much larger than the quality (vinyl acetate of stream plus 1 mole of 86g for the acetaldehyde that preparation absorbs
Ester will generate the acetaldehyde product of 1 mole of 46g, and by the quality of the reaction vinylacetate of addition, prepared absorption can be calculated
Acetaldehyde quality), such as 15 times or more；Buck absorbing liquid temperature control it is lower, such as 13 DEG C or hereinafter, if reaction kettle extracting
Aldehydes gas out will be absorbed by 100% on alkaline solution absorption tower, and spill into the gas at the top of alkaline solution absorption tower, be free of
The harmful thing such as acetaldehyde, it is not necessary to further be purified, can be directly emptied by charcoal trap again.
6, after the alkaline solution low temperature absorption that the gas extracted from reaction kettle passes through absorption tower, spilling rises to alkaline solution absorption
The gas of tower upper space, wherein the quality or concentration of the acetaldehyde of not condensed absorption should very little, then take out toward passing through active carbon
Absorption plant equipment adsorbs acetaldehyde therein, and the clean air of colorless and odorless is discharged.
Active carbon preferably with high-quality sawdust, coconut husk etc. for raw material, through crushing, mixing, extruding, molding, drying, charcoal
Change, activate and the active carbon or cellular active carbon of manufactured wooden column or ball shape.Its product pore-size distribution closes
Reason reaches maximum adsorption and desorption, and ash is low, impurity is few, Gas Phase Adsorption value, CTC have comparative advantage, and service life is longer.Separately
Outside, relative to the Powdered Activated Carbon for being usually used in sugaring decoloration, column, form of spherical particles or cellular mode of appearance are absorbing
Ta Neiyi filling, substantially without carbon dust, when (containing acetaldehyde) air filtration passes through activated carbon adsorption layer, resistance is also smaller.
7, alkaline solution absorption tower is according to the quantity of the alkaline solution used, after running several strokes, when acetaldehyde concentration therein
When higher, discharge pump to storage tank, storage tank is kept for 25 DEG C or less.
Compared with prior art, the invention has the advantages that and technical effect: in original existing vinylacetate system
In the production process of standby acetate starch, acetaldehyde product is in non-treated situation, if ambient temperature is high, then in mother liquor washing water
Acetaldehyde be easy everywhere volatilization distribute and pollute environment, occur endangering the bad of physical and mental health of environment and execute-in-place employee etc.
The problem of.The present invention has not only obtained acetate starch product by above-mentioned technological transformation and treatment process, but also recycles
Most of acetaldehyde that vinylacetate generates, the pure air of colorless and odorless is finally given off from active carbon adsorption equipment, can be kept away
Exempt from or eliminate the bad problem that existing technological process of production acetaldehyde generates, also has to the discharge amount for reducing acetaldehyde organic volatile
Positive meaning.
Detailed description of the invention
Fig. 1 is the production technological process of existing acetate starch.
Fig. 2 is that the production of acetate starch of the invention has both the process flow chart of acetaldehyde recovery.
Specific embodiment
Specific implementation of the invention is described further below in conjunction with attached drawing and example, if it is noted that having below
Not especially detaileds description process or parameter, be those skilled in the art can refer to the prior art understand or realization, such as
In the case where being not particularly illustrated, stirring generally is required to precipitate starch not.
Embodiment 1
(1) it sizes mixing: being 30m in volume3Reaction kettle in, be added 14m3Drinkable water, with the sodium carbonate liquor tune of 10%(w/w)
PH to 10.4 ± 0.1 is saved, 10 tons of dried starch is weighed, stirring is added to the water, and is eventually adding the water and sodium carbonate liquor of surplus, uses
The concentration that concentration meter detection adjusts starch milk is 40.0%(w/w), the pH that pH meter measurement adjusts starch milk is 9.8 ± 0.2, temperature
30±1.0℃。
(2) esterification: after starch milk stable system, starting vacuum pump, takes the air of reaction kettle upper space away, maintains
Then 0.08 MPa of vacuum degree starts balanced stream plus 750 kilograms of vinylacetate, stream adds complete in 0.5 ~ 0.6 hour；Simultaneously
Stream plus 10%(w/w) sodium carbonate liquor, keeping system pH is 9.8 ± 0.2,30 ± 1.0 DEG C of temperature, then react 1.5 hours.Upper
The esterification process stated, vinylacetate stream add 0.5 hour after finishing, and open vacuum pump, constantly take reaction kettle top sky away
Between gas to alkaline solution absorption tower.
(3) neutralize and acetaldehyde removal: after esterification, with the pH of 8.0%(v/v) hydrochloric acid solution regulation system be 5.1 ±
0.1, it is heated up with hot water circuit, stirring is warming up to 44 ± 1.0 DEG C, and always on vacuum pump maintains 0.08 MPa of vacuum degree, constantly
The gas of reaction kettle upper space is taken away to alkaline solution absorption tower, the time 1.0 hours, then uses 10%(w/w) sodium carbonate liquor tune
Saving pH is 6.2 ± 0.2, and equally to 44 ± 1.0 DEG C, always on vacuum pump maintains 0.08 MPa of vacuum degree, constantly takes away anti-
Answer the gas of kettle upper space to alkaline solution absorption tower, the time 0.6 hour.
(4) washing purification etc.: the acetate starch lotion after abstraction acetaldehyde product is pumped to rear end process, according to original
The production technology of acetate starch carries out the operation of the routine such as washing purification, centrifugal dehydration, drying, crushing, sieving and packaging.
(5) buck of aldehydes gas absorbs: alkaline solution absorption tower is the absorption tower of cylinder shape belt interlayer, diameter of phi
1500mm, height 3000mm are up and down 30 ° of triangle cone lids of slope angle, are tightly connected with flange.Three above absorption tower
Angle cone top is stamped gas outlet and buck feed inlet, triangle cone bottom cover below in addition to liquid outlet, what returning apparatus was tiltedly worn
Small blender and temperature measuring point.Air inlet duct is in the position of absorption tower 200mm eminence, and caliber Φ 50mm, gas outlet is straight
The disk of diameter Φ 600 is uniformly spudded in below there are many aperture of Φ 1mm, similar inverted Shower head with large water output coverage.Above admission line
Packing support plate is arranged in the place of the horizontal position of 300mm eminence, above the ceramic Bauer of the Φ 38 for being filled with 500mm high at random
Ring, is put into the buck of pH9.5, and height 1200mm can be totally submerged packing layer.
When alkaline solution absorption tower is run, circulating chilled water and small blender are opened, keeping the temperature of absorbing liquid is 15.0 ± 1.0
DEG C, and 10.0 L concentration 10.0%(w/w are added at the end of esterification) sodium carbonate liquor, abundant condensed absorbent acetaldehyde therein
Gas.
(6) activated carbon adsorption: while taking out the air above alkaline solution absorption tower toward active carbon adsorption equipment.It selects existing
It is mature [1020(long) × 1100(wide) × 1100(high)] activated carbon adsorber case, with 0.2 m of carbon amounts3, 2 m of adsorption area,2, handle 3000 m of air quantity3/h.Gas is after activated carbon adsorption purifies, and the non-hazardous gaseous matter of colorless and odorless can be direct
Emptying.
Embodiment 2
(1) it sizes mixing: being 30m in volume3Reaction kettle in, be added about 14m3Drinkable water, with the sodium carbonate liquor of 10%(w/w)
PH to 10.4 ± 0.1 is adjusted, 10 tons of dried starch is weighed, stirring is added to the water, it is eventually adding the water and sodium carbonate liquor of surplus,
Being detected with concentration meter and adjusting the concentration of starch milk is 40.0%(w/w), the pH that pH meter measurement adjusts starch milk is 9.8 ± 0.2, temperature
30 ± 1.0 DEG C of degree.
(2) esterification: after starch milk stable system, starting vacuum pump, takes the air of reaction kettle upper space away, maintains
Then 0.085 MPa of vacuum degree starts balanced stream plus 300 kilograms of vinylacetate, stream adds complete in 0.5 ~ 0.6 hour；Together
Shi Liujia 10%(w/w) sodium carbonate liquor, keeping system pH is 9.6 ± 0.2,30 ± 1.0 DEG C of temperature, then react 1.2 hours.?
Above-mentioned esterification process, vinylacetate stream add 1.0 hours after finishing, and open vacuum pump, constantly take reaction kettle top away
The gas in space is to alkaline solution absorption tower.
(3) neutralize and acetaldehyde removal: after esterification, with the pH of 8.0%(v/v) hydrochloric acid solution regulation system be 5.1 ±
0.1, it is heated up with hot water circuit, stirring is warming up to 44 ± 1.0 DEG C, and always on vacuum pump maintains 0.085 MPa of vacuum degree, no
The disconnected gas for taking reaction kettle upper space away the time 1.0 hours, then uses 10%(w/w to alkaline solution absorption tower) sodium carbonate liquor
Adjusting pH is 6.2 ± 0.2, and equally to 44 ± 1.0 DEG C, always on vacuum pump maintains 0.085 MPa of vacuum degree, constantly takes out
The gas of reaction kettle upper space is walked to alkaline solution absorption tower, the time 0.6 hour.
(4) washing purification etc.: the acetate starch lotion after abstraction acetaldehyde product is pumped to rear end process, according to original
The production technology of acetate starch carries out the operation of the routine such as washing purification, centrifugal dehydration, drying, crushing, sieving and packaging.
(5) buck of aldehydes gas absorbs: alkaline solution absorption tower is the absorption tower of cylinder shape belt interlayer, diameter of phi
1500mm, height 3000mm are up and down 30 ° of triangle cone lids of slope angle, are tightly connected with flange.Three above absorption tower
Angle cone top is stamped gas outlet and buck feed inlet, triangle cone bottom cover below in addition to liquid outlet, what returning apparatus was tiltedly worn
Small blender and temperature measuring point.Air inlet duct is in the position of absorption tower 200mm eminence, and caliber Φ 50mm, gas outlet is straight
The disk of diameter Φ 600 is uniformly spudded in below there are many aperture of Φ 1mm, similar inverted Shower head with large water output coverage.Above admission line
The place of the horizontal position of 300mm eminence, be arranged packing support plate, above the ceramic Pall ring at random for being filled with 800mm high, Φ
38 and Φ, 50 specification respectively accounts for 50%, is put into the buck of pH10.5, and height 1500mm can be totally submerged packing layer.
When alkaline solution absorption tower is run, circulating chilled water and small blender are opened, keeping the temperature of absorbing liquid is 12.0 ± 1.0
DEG C, and 2.0 L concentration 10.0%(w/w are added at the end of esterification) sodium carbonate liquor, abundant condensed absorbent acetaldehyde gas therein
Body.
Using the vinylacetate of 300 kg, the acetaldehyde of 160.4651 kg can produce.This example uses the relatively highly basic of pH10.5
Property buck, dosage is more than that 2650 L(do not count the buck that absorption tower lower part triangle circular cone bottom cover is contained), for preparation absorb
16 times or more of acetaldehyde quality；Secondly, buck height 1500mm, the more a height of 800mm of packing layer, and the Bao of 50 specification of Φ 38 and Φ
You respectively account for 50% by ring, compared with the Pall ring that 50 specification of Φ is applied alone, there is bigger contact specific area；The temperature of last buck absorbing liquid
Control at lower 12.0 ± 1.0 DEG C, therefore, the aldehydes gas extracted from reaction kettle under the action of the buck absorption tower,
Adequately it will be condensed and be absorbed, and spill into the gas of tower body upper cavity after absorption is handled in buck absorption tower, it is several
It can direct emission without the adsorption treatment using active carbon without harmful gaseous matter.
Above-mentioned example is the preferable embodiment of the present invention, but embodiments of the present invention are not by the limit of above-described embodiment
System, other any changes made without departing from the spirit and principles of the present invention, modification, substitution, combination or simplified,
It should be equivalent substitute mode, be included within the scope of the present invention.
Claims (10)
1. a kind of method of acetate starch production process recycling acetaldehyde, including size mixing, esterification, neutralization, washing, dehydration,
Drying steps, it is characterised in that in esterification and neutralization stage, the acetaldehyde product that vinylacetate reaction is generated is reacting
The different pH range of system extracts starch milk as aldehydes gas, then on buck absorption tower using vacuum, temperature-rising method
Be condensed absorption, the gas come out from buck absorption tower, then carries out adsorption treatment with active carbon adsorption equipment, realizes clean row
It is empty.
2. according to the method described in claim 1, it is characterized in that the reaction kettle of converted starch is sealed pressure reaction kettle, assembly
There is the aldehydes gas alarm detection instrument of water proof and dust proof.
3. according to the method described in claim 1, it is characterized in that reaction temperature is according to converted starch in esterification stage
The temperature needed is reacted, before vinylacetate stream adds, keeping the vacuum degree of reaction kettle is 0.08 MPa or more, and in entire ester
Change the vacuum degree that maintains like of reaction process, constantly detaches volatilization and spill into the aldehydes gas of reaction kettle upper space to buck suction
Receive tower.
4. according to the method described in claim 1, it is characterized in that reaction temperature is according to converted starch in esterification stage
The temperature needed is reacted, before vinylacetate stream adds, keeping the vacuum degree of reaction kettle is 0.08 MPa or more, with esterification
The progress of reaction, when the vacuum degree of reaction kettle is 0 or has positive pressure, just unlatching vacuum pump detaches volatilization and spills into reaction kettle top
The aldehydes gas in space is to buck absorption tower.
5. according to the method described in claim 1, it is characterized in that pH is neutralized with hydrochloric acid to 5.0- in starch milk in neutralization stage
5.5,40 DEG C ~ 45 DEG C are warming up to, keeping the vacuum degree of reaction kettle is 0.08 MPa or more, stirs 0.5 ~ 1.0 hour, then uses
Aqueous slkali tune pH to 5.5-6.55,40 DEG C ~ 45 DEG C heat preservations, keeps the vacuum degree of reaction kettle for 0.08 MPa or more, and stirring 0.4 ~
0.6 hour, vacuum pump is kept it turning on, volatilization is detached and spills into the aldehydes gas of reaction kettle upper space to buck absorption tower.
6. according to the method described in claim 1, it is characterized in that absorbing liquid used in absorption tower, is absorbed with water, but using pH9.5
~ 10.5 alkaline water absorbs, and suitable alkali is added in absorption process.
7. according to the method described in claim 1, it is characterized in that the operating temperature of absorbing liquid used in absorption tower, is entirely inhaling
Receipts process, the temperature of buck absorbing liquid is at 20.0 DEG C hereinafter, being maintained at 10 DEG C ~ 15 DEG C by cooling.
8. according to the method described in claim 1, it is characterized in that absorbing liquid quality quantity used in absorption tower is that preparation absorbs
5 times or more of quality quantity of acetaldehyde.
9. according to the method described in claim 1, it is characterized in that be arranged in absorption tower the stainless steel of 500 ~ 800mm, ceramics or
The Pall ring or Raschig ring filler of plastic material.
10. according to the method described in claim 1, it is characterized in that finally using activated carbon adsorption device equipment adsorption cleaning alkali
The air that water absorption tower comes, active carbon column, spherical and/or cellular active carbon.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113335022A (en) * | 2021-06-30 | 2021-09-03 | 上海启津测试技术有限公司 | Intelligent automatic automobile atomization detection processing method and system |
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| CN105418777A (en) * | 2015-12-19 | 2016-03-23 | 陈虹 | Synthetic process of acetylated starch |
| CN107042054A (en) * | 2017-03-27 | 2017-08-15 | 南京工业大学 | A kind of processing method of aldehydes waste gas |
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| CN113335022A (en) * | 2021-06-30 | 2021-09-03 | 上海启津测试技术有限公司 | Intelligent automatic automobile atomization detection processing method and system |
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