CN103521061A - Method for decreasing emission of sulfur dioxide in thermal power plant by utilizing waste molasses - Google Patents
Method for decreasing emission of sulfur dioxide in thermal power plant by utilizing waste molasses Download PDFInfo
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- CN103521061A CN103521061A CN201210226004.2A CN201210226004A CN103521061A CN 103521061 A CN103521061 A CN 103521061A CN 201210226004 A CN201210226004 A CN 201210226004A CN 103521061 A CN103521061 A CN 103521061A
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Abstract
The invention provides a method for decreasing the emission of sulfur dioxide in a thermal power plant by utilizing waste molasses, which can be used for solving the problem in the prior art that the waste molasses cannot be effectively utilized. According to the technical scheme, the method comprises the following step: adding a saccharic acid accounting for 300ppm to 6000ppm of the weight of total molasses into a desulfurization tower of a thermal power plant, wherein the saccharic acid is obtained via the reaction between the waste molasses and an oxidizing agent. The saccharic acid oxidized by a chloric acid is directly taken as a desulfurization synergist, so that the desulfurization efficiency is improved by more than one percent; and the emission of the sulfur dioxide from the thermal power plant into atmosphere is reduced by 20% to 30% or so every year.
Description
Technical field
The invention belongs to the recycling of the waste material in sugar industry, specifically, relate to a kind of method that adopts molasses to reduce thermal power plant sulfur dioxide (SO2) emissions.
Technical background
In sugar industry, for example, from sugarcane, produce sucrose or from beet, produce the problem how molasses that sucrose can run into generation is processed.In the fructose isomery industry of starch-polysaccharide-glucose-fructose, also can often there is the generation of waste saccharide liquid.In the useless sugar producing in sucrose or beet technique, containing a large amount of carbohydrate, is mainly sucrose, is mainly fructose in fructose isomerization processes in the waste saccharide liquid producing.From grape or starch, produce in the waste liquid producing in glucose technique is mainly glucose.These carbohydrate account for the 20-60% of gross weight, are a kind of liquid of very thickness.Owing to lacking recycling means, these syrup are often stayed the fermentation of letting alone to rot in original place or useless sugar hole, not only produce around peculiar smell stink, and cause huge waste.
On the other hand, the requirement along with environmental protection at present improves constantly, and most of thermal power plants require further to improve desulfurization degree.
Summary of the invention
The invention provides a kind of method that adopts molasses to reduce thermal power plant sulfur dioxide (SO2) emissions, it can solve the molasses of prior art existence and fail effectively to utilize, and the problem of desulfurization degree is further improved in thermal power plant.
Technical scheme of the present invention is, a kind of method that adopts molasses to reduce thermal power plant sulfur dioxide (SO2) emissions, described method step is: to the saccharic acid that adds the 300ppm-6000ppm that accounts for total slurry weight in the desulfurizing tower in thermal power plant, described saccharic acid is to be obtained by molasses and oxidant reaction.
By molasses and oxidant, oxidation reaction in the situation that having catalyst to exist obtains described saccharic acid.
Oxidation reaction is used catalyst, and described catalyst is selected from following element or the compound that contains this element: manganese, iron, cobalt, vanadium, chromium, palladium or platinum, and described catalyst accounts for the 0.01-1.0% of syrup dry weight.
Described molasses is selected from following process and obtains:
In sucrose technique, extract sucrose remaining waste saccharide liquid later;
In beet technique, extract sucrose remaining waste saccharide liquid later;
Glucose becomes the waste saccharide liquid producing in fructose isomerization processes;
By starch, produce the waste saccharide liquid producing in glucose, maltose or dextrin technique.
Described oxidant is to select from following oxidant: oxygen, and manganese dioxide, nitric acid, potassium permanganate, hypochlorous acid or its salt, chlorine, chloric acid or its salt, perchloric acid or its salt, and the weight ratio of described oxidant and sugared dry weight is 1: 10-2: between 1.
Described oxidizing reaction temperature is at 25-110 ℃.
Described oxidation reaction, is attended by sugared oxidative decomposition, and the product of this decomposition reaction is 1 little carboxylic acids that contains 1 carbon to 5 carbon or micromolecular hydroxyl carboxylic acid.
Described oxidation reaction is carried out under acid condition, pH value 1-2.
Described saccharic acid addition accounts for the 800-3000ppm of total slurry weight.
Described total slurry weight is water in desulfurizing tower and the gross weight of calcium carbonate or water and calcium hydroxide.
A kind of recycling method that the invention provides molasses, the method is: first the monose in molasses, polysaccharide is oxidized to saccharic acid, then the product of oxidation is used in lime stone or Wet Lime Desulfurization additive and is used as desulfurization synergistic additive.
The source of molasses mainly contains: in the fructose isomerization processes of starch-polysaccharide-glucose-fructose, produce the technique of producing sucrose in the technique of sucrose or beet in sugarcane.After white granulated sugar being extracted by methods such as crystallizations, in residual liquid, contain a large amount of sucrose and polysaccharide in sucrose or beet technique.Also the product that comprises some parts hydrolysis, i.e. glucose.These sugar contain the nitrogenous biomolecule of other sulfur-bearings toward contact.Because useless sugared viscosity is high, impurity is many, and darker in color, so be difficult to again purify.Molasses can be that the bleaching of sulfur dioxide place was managed, or through sulfur dioxide treatment, do not cross.Through bleaching.If through oxidizing sulfur dioxide, can be with sulfonic group on a part of glycan molecule.In general, at present molasses is not had to good treating method, be badly in need of a kind of process turning waste into wealth, find its new purposes.
On the other hand, the requirement along with environmental protection at present improves constantly, and most of thermal power plants have all configured wet desulphurization device.This device is worn into fine powder lime stone, then mix with water, the slurries that form are the spraying layer to desulfurizing tower differing heights with pump pump, former flue gas mixes with the lime white spraying from bottom to top, sulfur dioxide in former flue gas and limestone slurry reaction, remove sulfur dioxide, lime stone changes into calcium sulfite simultaneously, and then under the effect of oxygen, calcium sulfite is oxidized to calcium sulfate.For a common power plant, its desulfuration efficiency is generally at 85-95%.In order further to improve desulfuration efficiency, external a lot of power plant comprises that the Power Plants in China of wanting when quantity is all used desulfurization synergistic additive at present.Additive dissolves lime stone in advance, and the calcium ion compound water soluble of generation, in greatly having improved and SO
2ability.Because a large amount of ion complexes is dissolved in drop, the supplementary speed of neutralising capacity is also greatly accelerated simultaneously.PH value is declined slower, thereby make SO
2removal efficiency increase.In addition, additive has not only maintained the pH value of slurries, but also has accelerated the absorption of dissolution of calcium carbonate and sulfur dioxide.In a word, the use of additive can increase considerably the solubility of lime stone and sulfur dioxide, thereby directly improves desulfurized effect, and desulfurization degree is brought up to more than 95%.The active ingredient of most of sulfur-removing additives is the molecules that contain carboxyl, because the pH buffer capacity of carboxyl is strong, just can under the prerequisite that does not hinder calcium sulfite oxidation, accelerate the dissolving of lime stone.The organic carboxyl acid of general use comprises and contains one to the carboxylic acid of 12 carbon atoms, and contains zero to 4 two keys.For example, described organic carboxyl acid is the acid of a N unit, N=1-4.Specifically can be unit acid, or binary, ternary, tetra-atomic acid.Such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid etc.Because hydroxycarboxylic acid also belongs to carboxylic acid category, for example gluconic acid, can be used as sulfur-removing additives so glycosyloxy is changed into saccharic acid.
The main oxidation reaction being participated in by the aldose in syrup (as glucose, maltose) is that aldehyde radical is oxidized to carboxyl:
R-CHO+ oxidant-------RCOOH
The main oxidation reaction being participated in by the ketose in syrup (as fructose, sucrose) is often accompanied by decomposition reaction:
R
1-CO-CH
2oH+ oxidant----------------------R
1cOOH+HCOOH
In above two reactions, R, R
1, R
2, be the carbochain that contains hydroxyl.CO is carbonyl, and CHO is aldehyde radical, CH
2oH is the methylol groups of one end of fructose molecule.
The oxidant that is suitable for oxidation reaction is to select from following oxidant: oxygen, manganese dioxide, nitric acid, potassium permanganate, hypochlorous acid or its salt, chlorine, chloric acid or its salt, perchloric acid or its salt.Also can be the mixture of above several oxidants.Because consider cost recovery, preferred oxidant is comparatively cheap hypochlorous acid and salt (bleaching powder) thereof, nitric acid, manganese dioxide, chloric acid.
These oxidants can be used alone, but also also mix together, the mixing of for example mixing of nitric acid and chloric acid, or hypochlorous acid and manganese dioxide.The amount aspect of using, the small molecular sugar of corresponding each mole, oxidant should provide the oxygen atom of at least one mole.For example, hypochlorous acid structure is HClO, and each hypochlorous acid can provide an oxygen atom, and chloric acid structure is HclO
3, each chloric acid can provide three oxygen atoms.Similar, each manganese dioxide molecule can provide an oxygen atom.So, the corresponding reaction that glucose oxidase is become to gluconic acid, the glucose of each mole needs the manganese dioxide of 1 mole, the hypochlorous acid of one mole, or the chloric acid of 1/3 mole, the perchloric acid of 1/4 mole.These are theoretical values, and in practical operation, oxidant often needs excessive 10-50%.
Reaction temperature generally need to be higher than room temperature, for example, be heated under the condition of 60 ℃.Generally speaking, heating-up temperature depends on the pressure that reaction vessel can bear, and in 15 atmospheric reaction vessels, can be warmed to 170 ℃.On the other hand, pressure reacting container must have safety valve, to prevent some oxidant decomposes, produces a large amount of gas and even explodes.Preferable reaction temperature is at 60 to 90 ℃.
Oxidation reaction can acceleration in the situation that catalyst exists, and such as noble metals such as palladium platinum, is comparatively classical catalyst.Many transition metal also can carry out catalysis to oxidation reaction, cobalt for example, nickel, iron, manganese etc.These metals can be with the form catalysis of the simple substance that disperses, such as palladium platinum etc., also can be with the form of compound, and cobalt chloride for example, nickel chloride, nickel nitrate, manganese nitrate etc.In general, the 100ppm that the consumption of catalyst accounts for sugared dry weight is to 10000ppm.In addition, of porous ceramics, make the load of catalyst, can save the use amount of catalyst.After every secondary response finishes, direct filtering recovering catalyst.
Reaction generally need to be carried out under acid condition, hypochlorous acid especially, clorox, chloric acid, sodium chlorate, manganese dioxide etc.Preferably pH value is between 0 to 7, optimum pH1-2.
The viscosity of considering syrup is very large, can before reaction, be diluted with water, and the principle of dilution is to be diluted to the solid content that is not less than 10%.Because if dilute excessively, can increase cost of transportation.
Syrup after oxidation can add according to the ratio of the 300-6000ppm of total slurry weight, preferably 800-3000ppm.Certainly, can add more than 3000 the even oxidation syrup of 10000ppm left and right, but from consider in price do not need to add so many.Total slurry weight refers to water in desulfurizing tower and the gross weight of calcium carbonate or water and calcium hydroxide.The present invention can be used in lime (calcium carbonate) or lime stone (calcium hydroxide) sulfur removal technology.
The specific embodiment
Molasses oxidation reaction condition one:
Dextrin solution is taken from the waste saccharide liquid in starch Enzymatic glucose technique, and in this liquid, containing glucose 35%, 15%, three of maltose polysaccharide more than sugar accounts for 7%.Before reaction, dilute with water is one times.
Oxidant adopts the porous ceramics that contains palladium, and the surperficial content of palladium accounts for 0.01 milligram every square centimeter.The mesoporous micropore gross area 80 square meters of porous ceramics.100 milliliters of reaction solution cumulative volumes, oxidant adopts air, and approximately 50 milliliters of flows are per minute.Whole reaction is heated in the water-bath of 60 ℃.Reaction time continues 12 hours.After 12 hours, take out sample, with the NaOH of 1M, be titrated to phenolphthalein variable color, determine the amount that carboxyl produces.Result confirms: after reacting 12 hours, glucose is 45% to the conversion ratio of gluconic acid.This solution is solution one.
Molasses oxidation reaction condition two:
Dextrin solution is taken from the waste saccharide liquid in starch Enzymatic glucose technique, and in this liquid, containing glucose 25%, 13%, three of maltose polysaccharide more than sugar accounts for 11%.Before reaction, dilute with water is one times.
Reaction oxidant adopts the clorox of molal quantity excessive 30%, with hydrochloric acid, adjusts pH value to 1.0, and whole reaction is heated in the water-bath of 90 ℃.Reaction time continues 12 hours.After 12 hours, take out sample, with the NaOH of 1M, be titrated to phenolphthalein variable color, determine the amount that carboxyl produces.Result confirms: after reacting 12 hours, glucose is 35% to the conversion ratio of gluconic acid.This solution is solution two.
Molasses oxidation reaction condition three:
Dextrin solution is taken from the waste saccharide liquid in starch Enzymatic glucose technique, and in this liquid, containing glucose 25%, 13%, three of maltose polysaccharide more than sugar accounts for 11%.Before reaction, dilute with water is one times.Get 100 grams of solution.
Reaction oxidant adopts the clorox of molal quantity excessive 30%, with hydrochloric acid, adjusts pH value to 1.0, and whole reaction is heated in the water-bath of 95 ℃.Different from example 2, in reaction, counted the ferric trichloride that accounts for total solution weight 1%, the reaction time continues 12 hours.After 12 hours, take out sample, with the NaOH of 1M, be titrated to phenolphthalein variable color, determine the amount that carboxyl produces.The amount of the hydrochloric acid that titration results deduction adds.Result confirms: after reacting 12 hours, glucose is 63% to the conversion ratio of gluconic acid, and this example explanation catalyst, especially transition-metal catalyst are conducive to sugared oxidation.This solution is solution three.
Molasses oxidation reaction condition four:
Waste saccharide liquid is taken from sugarcane and is produced the waste saccharide liquid in sucrose technique, contains sucrose 35%, glucose 2.5%, fructose 6% in this liquid.Before reaction, dilute with water is one times.Get 100 grams of solution.
Reaction oxidant adopts the clorox of molal quantity excessive 30%, with hydrochloric acid, adjusts pH value to 1.0, and whole reaction is heated in the water-bath of 95 ℃.In addition be accelerated reaction, added the ferric trichloride that accounts for total solution weight 1% in reaction, the reaction time continues 24 hours.After 24 hours, take out sample, with the NaOH of 1M, be titrated to phenolphthalein variable color, determine the amount that carboxyl produces.The amount of the hydrochloric acid that titration results deduction adds.Result confirms: after reacting 24 hours, sucrose sugar is 43% to the conversion ratio of small molecular sugar acid, and this solution is solution four.Due to severe reaction conditions, and hypochlorous acid is strong oxidizer, and in reaction, a part of sugar is degraded to carbon dioxide.
Embodiment:
The desulfurized effect of useless saccharic acid after oxidation in practical sulphur removal.Solution two is produced to solution four amplification quantity in the reactor of 2 tons, and product neutralizes pH7.
Testing location is installed 500,000 kilowatts altogether at one No. two units of ，Gai power plant of Central China power plant, and inlet flue gas concentration is 1665-1834ppm, lime stone slurry density 1.18, and concentration approximately 20%, design calcium sulfur ratio is 1.05.
Waste saccharide liquid after oxidation adds in the melt pit of desulfurizing tower, according to effective solid saccharic acid composition, calculate the 1800ppm that the amount adding accounts for total slurry weight, adding the duration is two hours, after this every one hour, reads once to export flue gas data, gets the mean value of the first five hour.Outlet flue gas concentration in the absence of desulfurizing agent is 90ppm.The calculating of desulfurization degree is by exporting flue gas concentration divided by entrance concentration.
By above-mentioned explanation, can find out, with the saccharic acid of chloric acid oxidation, can directly be used for doing desulfurization synergistic agent, more than desulfuration efficiency is improved to one percentage point, for this power plant, this one percentage point correspondence the annual about 20-30% of sulfur dioxide (SO2) emissions that reduces.
The desulfurized effect of solution two to four and pure gluconic acid is relatively as table one.
Claims (10)
1. a method that adopts molasses to reduce thermal power plant sulfur dioxide (SO2) emissions, it is characterized in that, described method step is: to the saccharic acid that adds the 300ppm-6000ppm that accounts for total slurry weight in the desulfurizing tower in thermal power plant, described saccharic acid is to be obtained by molasses and oxidant reaction.
2. method according to claim 1, is characterized in that: by molasses and oxidant, oxidation reaction in the situation that having catalyst to exist obtains described saccharic acid.
3. method according to claim 2, it is characterized in that: oxidation reaction is used catalyst, described catalyst is selected from following element or the compound that contains this element: manganese, iron, cobalt, vanadium, chromium, palladium or platinum, and described catalyst accounts for the 0.01-1.0% of syrup dry weight.
4. method according to claim 1, is characterized in that, described molasses is selected from following process and obtains:
In sucrose technique, extract sucrose remaining waste saccharide liquid later;
In beet technique, extract sucrose remaining waste saccharide liquid later;
Glucose becomes the waste saccharide liquid producing in fructose isomerization processes;
By starch, produce the waste saccharide liquid producing in glucose, maltose or dextrin technique.
5. method according to claim 2, it is characterized in that, described oxidant is to select from following oxidant: oxygen, manganese dioxide, nitric acid, potassium permanganate, hypochlorous acid or its salt, chlorine, chloric acid or its salt, perchloric acid or its salt, and the weight ratio of described oxidant and sugared dry weight is 1: 10-2: between 1.
6. method according to claim 2, is characterized in that: described oxidizing reaction temperature is at 25-110 ℃.
7. method according to claim 2, is characterized in that: described oxidation reaction, be attended by sugared oxidative decomposition, and the product of this decomposition reaction is 1 little carboxylic acids that contains 1 carbon to 5 carbon or micromolecular hydroxyl carboxylic acid.
8. method according to claim 2, is characterized in that: described oxidation reaction is carried out under acid condition pH value 1-2.
9. method according to claim 1, is characterized in that: described saccharic acid addition accounts for the 800-3000ppm of total slurry weight.
10. according to method described in any one claim in claim 1-9, it is characterized in that: described total slurry weight is water in desulfurizing tower and the gross weight of calcium carbonate or water and calcium hydroxide.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111607208A (en) * | 2020-06-16 | 2020-09-01 | 福建师范大学福清分校 | Preparation method of desulfurized fly ash/unsaturated resin composite material |
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| US4626418A (en) * | 1985-09-26 | 1986-12-02 | Dravo Corporation | Removal of SO2 from SO2 -containing gases |
| US5635150A (en) * | 1995-09-26 | 1997-06-03 | Coughlin; Robert W. | Sorption of acidic gases by solid residue from sugar refining |
| CN1403184A (en) * | 2002-09-30 | 2003-03-19 | 华南理工大学 | Gas adsorbent produced with filter mud of sugar refinery and its application in treating boiler fume |
| WO2011031277A1 (en) * | 2009-09-14 | 2011-03-17 | Barry Hugghins | Method for wet flue gas desulfurization |
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2012
- 2012-07-02 CN CN201210226004.2A patent/CN103521061A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4626418A (en) * | 1985-09-26 | 1986-12-02 | Dravo Corporation | Removal of SO2 from SO2 -containing gases |
| US5635150A (en) * | 1995-09-26 | 1997-06-03 | Coughlin; Robert W. | Sorption of acidic gases by solid residue from sugar refining |
| CN1403184A (en) * | 2002-09-30 | 2003-03-19 | 华南理工大学 | Gas adsorbent produced with filter mud of sugar refinery and its application in treating boiler fume |
| WO2011031277A1 (en) * | 2009-09-14 | 2011-03-17 | Barry Hugghins | Method for wet flue gas desulfurization |
Non-Patent Citations (1)
| Title |
|---|
| 李翠莲: "《化学》", 31 May 2002, 中国农业出版社, article "单糖的性质", pages: 219 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111607208A (en) * | 2020-06-16 | 2020-09-01 | 福建师范大学福清分校 | Preparation method of desulfurized fly ash/unsaturated resin composite material |
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Application publication date: 20140122 |