CN100506353C - Techniques of flue gas desulpurizing through catalytic oxidation method and by-product polymerizing iron sulfate through catalytic method - Google Patents

Abstract

The invention discloses a process using catalyzing and oxidizing method on fume desulfurization and using catalyzing method on producing polyferric sulfate, a solvent containing ferric ion is used as the desulfurization absorption liquid, a sulfur dioxide in fume is absorbed and dissolved through the absorption liquid to convert into a sulfurous acid which can be oxidized into sulfuric acid by utilizing air base on the catalyzing and oxidizing effect of the ferric ion; when the concentration of the sulfuric acid in the desulfurization absorption liquid is between 3 percent and 10 percent, the desulfurization absorption liquid is introduced to the polymeric ferric sulfate synthesization system, simultaneously, ferrous sulfate and catalyzer are added, an oxidizing, hydrolyzing and polymerizing reaction occurs between ferrous sulfate, catalyzer and sulfuric acid of desulfurization absorption liquid, a desulfurization side product, polyferric sulfate is produced; so the invention can recycle the sulfur resource and get the high value-added desulfurization side product, the transportation fee is lower, the benefit from the desulfurization process is outstanding.

Description

The technology of a kind of catalytic oxidation flue gas desulfurization and catalysis method by-product polymerizing iron sulfate

Technical field

The invention belongs to the flue gases purification field, relate to the technology of a kind of catalytic oxidation flue gas desulfurization and catalysis method by-product polymerizing iron sulfate.

Background technology

The flue gas desulfurization of transition metal ions such as iron and manganese liquid phase catalytic oxidation can obtain the accessory substance based on dilute sulfuric acid, the dilute sulfuric acid process sulfur removal technology of Japan thousand Dai Tian companies exploitation, be to be absorption liquid with the dilute sulfuric acid that contains iron ion, in the presence of oxygen, redox cycle by iron ion has realized that the catalytic oxidation of sulfur dioxide absorbs, this technology is used for by-product gypsum with the sulfuric acid that produces, and with right obstruction and the scale problems that has solved in the lime method sweetening process, but the accessory substance added value is lower.

Added value and the purposes of some researchers in order to increase desulfurization product in the iron ion catalytic oxidation desulfurization, as desulfuration byproduct, realizes reclaiming the purpose of sulphur resource in the flue gas with bodied ferric sulfate.

Chinese patent (patent No. 00101556.7) utilizes iron filings as desulfurizing agent, at first obtain the ferrous sulfate crystal in the sweetening process, again the ferrous sulfate crystal is oxidized to solid ferric polysulfate in the oxidizing tower of high temperature, use this ferrous oxidation technology and one-step method to produce the resemble process of solid ferric polysulfate, do not need to add other oxidants, but may have the incomplete problem of ferrous ion oxidation.

Chinese patent (application number 96106432.3) is to be absorbent with the ferrous sulfate, with hydrogen peroxide, nitrogen dioxide or potassium chlorate (sodium) is oxidant, with iron or nitrogen oxide is catalyst, with NaOH is conditioning agent, under certain conditions, the oxygen sulfur compound reaction with coal-fired flue-gas generates efficient water treatment agent bodied ferric sulfate.Inferior sulfate radical and ferrous ion oxidation that this invention desulfurization produces all need oxidant to finish, so desulphurization cost is higher.

Above-mentioned technology has all obtained the accessory substance bodied ferric sulfate in desulfurization, but because the problem of product quality and operating cost makes its blemish in an otherwise perfect thing.

Conventional bodied ferric sulfate production process comprises direct oxidation method and catalytic oxidation.Direct oxidation method is that to adopt oxidant be ferric iron with ferrous oxidation directly, is hydrolyzed then, polymerization, and the oxidant that this method adopts has hydrogen peroxide, clorox and sodium chlorate strong oxidizers such as (potassium).Though direct oxidation method technology and production equipment are simple, and be easy and simple to handle, there be oxidant price height, problem that consumption is big, thereby be difficult in suitability for industrialized production, popularize and use.Catalytic oxidation be ferrous sulfate under catalyst action, be Fe by oxygen or airborne dioxygen oxidation ₂(SO ₄) ₃, and after hydrolysis, polymerisation obtain bodied ferric sulfate, catalyst commonly used is natrium nitrosum and nitric acid.Catalytic oxidation has production cycle length, course of reaction has shortcomings such as part noxious gas emission, but because this method production technology is simple, equipment investment is few, product stability is high, operating cost is cheap etc. characteristics make this method be most widely used in industry.

Desulfuration byproduct bodied ferric sulfate preparation process is introduced in the economy that the most general catalytic oxidation of application in the conventional bodied ferric sulfate production can improve flue gas desulfurization of iron ion liquid phase catalytic oxidation and by-product polymerizing iron sulfate technology undoubtedly, and can stable acquisition meets the desulfuration byproduct of national standard.

Catalytic oxidation ferrous ion oxidation reaction is slower, because catalytic reaction is the gas-liquid phase reaction, can be by increasing the contact method fast reaction speed of area of gas-liquid, Li Fengting etc. have proposed reaction tower method and atomization, realized large-scale production, cost reduces significantly, has obtained good economic benefit; Japan and United States Patent (USP) propose the gunite of circulation technology, and liquid is fully disperseed in gas phase, have improved reaction rate, have improved production efficiency greatly.According to the actual conditions at flue gas desulfurization scene, it is synthetic most suitable to select for use the reaction tower method to carry out the catalysis of desulfuration byproduct bodied ferric sulfate at normal temperatures and pressures.

Summary of the invention

The technology that the purpose of this invention is to provide a kind of catalytic oxidation flue gas desulfurization and catalysis method by-product polymerizing iron sulfate, be used for improving the reasonability and the operability of absorption method sulfur removal technology, reduce the addition of additive, reduce desulphurization cost, obtain the reliable quality byproduct.

Technical scheme of the present invention is as follows:

Being characterized as in (1) desulfurization absorption liquid circulation process that technology has comprises desulfurizing tower and oxidizing tower, the bodied ferric sulfate synthesis system is used to prepare bodied ferric sulfate, this system comprises circular response pond and catalysis synthetic tower, and the circular response pond is arranged on catalysis synthetic tower tower bottom or independent the setting; (2) with the copperas solution be the desulfurization absorption liquid, ferrous iron solution quantitatively joins the desulfurizing tower bottom and quantitatively replenishes in sweetening process and makes the concentration of iron ion between 0.1mol/L～1.0mol/L before device starts, sulfur dioxide in flue gas absorbs to dissolve through absorption liquid and is converted into sulfurous acid in desulfurizing tower, catalysed oxidn by means of iron ion, utilize air that part sulfurous acid is oxidized to sulfuric acid, absorption liquid enters oxidizing tower subsequently, by in tower, blasting the carrying out that air promotes that iron ion catalytic oxidation inferior sulfate radical reacts, make desulfurization be dissolved in inferior sulfate radical complete oxidation in the absorption liquid, when sulfuric acid concentration is between 3～10% in the desulfurization absorption liquid, the partial desulfurization absorption liquid is introduced in the circular response pond of bodied ferric sulfate synthesis system; (3) add natrium nitrosum or nitric acid in the technology as catalyst, in bodied ferric sulfate is synthetic, catalyst and ferrous iron solution constantly quantitatively join the circular response pond in time by the delivery pump that is provided with respectively, and in the circular response pond, carrying out air or industrial pure oxygen aeration, catalyst is finished the oxidation reaction of ferrous ion in catalysis synthetic tower and circular response pond; (4) dilute sulfuric acid of the ferric sulfate of ferrous sulfate oxidation generation and desulfurization generation is hydrolyzed and polymerisation in catalysis synthetic tower and circular response pond, obtains bodied ferric sulfate.

Gas residence time is 3～15s in the desulfurizing tower, and flue gas desulfurization course liquid-gas ratio control range is at 1～20L/Nm ³Between, the time of staying of desulfurization absorption liquid in oxidizing tower is between 5～60min.

Fume desulfurizing tower, oxidizing tower and catalysis synthetic tower are a kind of of packed tower, spray column, bubble tower or sieve-plate tower.

The reaction pressure of controlling in fume desulfurizing tower, oxidizing tower, catalysis synthetic tower and the circular response pond is a normal pressure, and reaction temperature is 20～80 ℃.

The mol ratio of sulfuric acid amount is 1:0.2～1:0.45 in the addition of the synthetic middle ferrous sulfate of bodied ferric sulfate and the desulfurization absorption liquid of adding.

The time of staying of circular response liquid in the circular response pond was between 5～30min during bodied ferric sulfate was synthetic.

The mol ratio of catalyst addition and ferrous sulfate addition was 0.03:1～0.5:1 during bodied ferric sulfate was synthetic, and catalyst is 2～33 to the catalysis multiple of ferrous ion oxidation.

The air or the pure oxygen that feed during bodied ferric sulfate is synthetic are used as Fe ²⁺The oxidant of oxidation, adding the airborne oxygen content or the amount of adding pure oxygen and the mol ratio of ferrous sulfate addition is 0.25:1～1:1.

The desulfuration byproduct bodied ferric sulfate has for liquid, solid-state or two states.

Effect of the present invention and benefit are:

With thousand generation the field dilute sulfuric acid sulfur removal technology by-product gypsum compare, technology of the present invention is used to produce polymeric ferric sulfate flocculant with the dilute sulfuric acid that desulfurization produces, improved the added value of accessory substance, economic benefit is obvious, and the bodied ferric sulfate synthesis technique adopts catalyst and does not use oxidant, reduced the use amount of ferrous ion oxidation, reduced cost of material, made the technology of iron ion catalytic oxidation desulfurization and by-product polymerizing iron sulfate have more significantly economic benefit with additive.

The bodied ferric sulfate synthesis technique adopts equipment such as packed tower, spray column, has increased the gas-liquid contact area, has improved the oxidation rate of ferrous ion, and building-up process is carried out under normal pressure, and operating process is simple.

Description of drawings

Accompanying drawing is the process chart of catalytic oxidation flue gas desulfurization of the present invention and catalysis method by-product polymerizing iron sulfate.

Among the figure: 1 desulfurization blower fan; 2 desulfurizing towers; 3 demisters; 4 exhaust pass; 5 absorption liquid delivery pumps; 6 oxidizing towers; 7 Aeration fans; 8 absorption liquid circulating pumps; 9 circular response ponds; 10 polymerization ferrikinetics pumps; 11 catalysis synthetic towers; 12 catalyst storage tanks; 13 catalyst transport pumps; 14 ferrous sulfate preparation pond; 15 ferrous sulfate delivery pumps; 16 oxidation fans or oxygenerator; 17 gas circulators; 18 filter presses; 19 finished fluids storage pond; 20 spray dryers; 21 packing machines.

The specific embodiment

Be described in detail the specific embodiment of the present invention below in conjunction with technical scheme and accompanying drawing.

By the desulfurization blower fan 1 that is provided with in the technology flue gas is sent into desulfurizing tower 2 bottoms, initial desulfurization absorption liquid is a ferrous sulfate aqueous solution, the ferrous sulfate that ferrous sulfate aqueous solution is prepared ferrous sulfate in the pond 14 by ferrous sulfate delivery pump 15 quantitatively adds the absorption tower, flue gas and the absorption liquid counter current contacting that flows down by tower top in tower, sulfur dioxide in flue gas is absorbed dissolving, because the catalytic action of iron ion, the inferior sulfate radical that the dissolving of part sulfur dioxide produces is oxidized to sulfate radical, flue gas after being purified enters the demister 3 on desulfurizing tower top, remove in the flue gas enter the 4 back dischargings of fume emission passage behind the moisture of being with, control the certain time of staying of flue gas in desulfurizing tower, can obtain the desulfurization degree more than 90%.

Absorption liquid is discharged by the desulfurizing tower bottom, send into oxidizing tower 6 by absorption liquid delivery pump 5, in oxidizing tower, by the control certain absorption liquid time of staying, remaining inferior sulfate radical is sulfate radical by the iron ion catalysed oxidn by complete oxidation in the absorption liquid, and because O ₂Oxidation, when absorption liquid left oxidizing tower, the ratio that is trivalent in the absorption liquid in the iron ion did not have significant change, by Aeration fan 7 aeration in tower, provided catalytic oxidation excessive O in the technology ₂Amount, absorption liquid is squeezed into desulfurizing tower top by absorption liquid circulating pump 8 and is recycled.

By above-mentioned technical process, sulfur in smoke constantly is removed, desulfurization produces the amount of sulfuric acid and is on the increase in time, after sulfuric acid reaches finite concentration in the absorption liquid, taking-up partially absorbs liquid and enters circular response pond 9, by catalyst transport pump 13 catalyst in the catalyst storage tank 12 is quantitatively added the circular response pond, the ferrous sulfate of ferrous sulfate being prepared in the pond 14 by ferrous sulfate delivery pump 15 quantitatively adds the circular response pond, by oxidation fan or oxygenerator 16 oxidation air or industrial oxygen is sent into the circular response pond.

Reaction liquid is sent into catalysis synthetic tower 11 by polymerization ferrikinetics pump 10 and is carried out the ferrous ion catalytic oxidation, constantly circulation repeatedly between catalysis synthetic tower and circular response pond of reaction liquid, ferrous ion is constantly oxidized, ferrous sulfate constantly joins in the whole system in time, hydrolysis and polymerisation can take place between sulfuric acid that desulfurization produces and the ferric sulfate that produces by the ferrous sulfate oxidation, the control certain reaction time, can obtain liquid polymeric ferric sulfate primary product.

The catalytic gas that contains nitrogen oxide and oxygen can constantly circulate in the catalysis synthetic tower by gas circulator 17 and participate in the oxidizing process of ferrous ion, when the catalysis multiple of catalyst oxidation ferrous ion reaches certain value, can be discharged into desulfurizing tower, the part nitrogen oxide that copperas solution discharges in can complex catalysis gas in desulfurizing tower, reduce the discharge capacity of nitrogen oxide in the flue gas on the one hand, again bring this part nitrogen oxide into reaction that the circular response pond participates in iron protoxide ion once more by copperas solution on the other hand, improve the utilization ratio of catalyst.

Primary product are handled by the filter press 18 that is provided with in the technology, remove cigarette ash dust and impurity that sweetening process and the raw material process of adding are brought into, obtain the normal fluid polyaluminum sulfate iron product that insolubles content meets the national product quality, send into finished fluid storage pond 19 subsequently.

For ease of Product transport, liquid polymeric ferric sulfate obtains the solid ferric polysulfate product by dry run, prepare solid ferric polysulfate by liquid polymeric ferric sulfate and select centrifugal spray dryer 20 for use, utilize the superheated steam of power plant to do thermal source, electric heater heating by setting up in the system when temperature does not reach drying and requires, perhaps directly utilize coal-fired hot-blast stove to come the dry liquid product for drying device provides high temperature air, the desulfurizing byproduct solid ferric polysulfate is collected by drying tower bottom discharge port and cyclone separator, dried hot gas turns back in the preceding former flue of desulfurization, the small amount of solid accessory substance that carries in the hot gas can reenter in the desulphurization system along with processed flue gas, reduce the accessory substance loss, make desulfurizing agent ferrous sulfate utilization rate 〉=95%, solid product warehouse-in or sale after packing machine 21 packings.

Embodiment 1

The coal-fired thermal power boiler of a 75t/h, flue gas flow are 100,000 Nm ³/ h, SO ₂Content is 1500mg/Nm ³, flue-gas temperature is 130 ℃, according to technology of the present invention, and when leaving desulfurizing tower, SO in the desulfidation tail gas ₂Content 150mg/Nm ³, flue-gas temperature is 50 ℃, desulfuration efficiency 90%.

Desulfurizing tower is a packed tower, and diameter is 7m, and height is 28m, and filler is a cascade ring, RPP material, nominal diameter 50mm

The desulfurizing tower gas residence time is 13s

The desulfurizing tower liquid-gas ratio is 10L/Nm ³, absorption liquid flow 1000m ³/ h

Oxidizing tower is a bubble tower, and liquid residence time is 20min

The catalysis synthetic tower is a packed tower, and diameter is 3.5m, and height is 6m, and filler is a cascade ring, RPP material, nominal diameter 50mm

The reaction pressure of desulfurizing tower, catalysis synthetic tower and the control of circular response pond is a normal pressure, and reaction temperature is 50 ℃

The circular response pond absorption liquid time of staying is 5min

Copperas solution initial concentration 20%, magnitude of recruitment are 4.28m ³/ h

Catalyst is a natrium nitrosum, and initial concentration solution is 10%, and magnitude of recruitment is 437L/h

The mol ratio that the addition of natrium nitrosum and system add the ferrous sulfate amount is 1:15

The mol ratio that removes sulfur dioxide in flue gas amount and ferrous sulfate addition is 0.3:1

Remove 972 tons/year of sulfur dioxide in flue gas amounts

15639 tons/year of the ferrous sulfate heptahydrate demands of 90% purity

237.65 tons/year of the industrial sodium nitrite demands of catalyst 98% purity

Bodied ferric sulfate output: 14922 tons/year of 25773 tons/year of fluid products or solid products

Embodiment 2

The coal-fired thermal power boiler of a 220t/h, flue gas flow are 250,000 Nm ³/ h, SO ₂Content is 1500mg/Nm ³, flue-gas temperature is 130 ℃, according to technology of the present invention, and when leaving desulfurizing tower, SO in the desulfidation tail gas ₂Content 150mg/Nm ³, flue-gas temperature is 50 ℃, desulfuration efficiency 90%.

Desulfurizing tower is a packed tower, and diameter is 9.5m, and height is 32m, and filler is a cascade ring, RPP material, nominal diameter 50mm

The desulfurizing tower gas residence time is 13s

The desulfurizing tower liquid-gas ratio is 10L/Nm ³, absorption liquid flow 2500m ³/ h

Oxidizing tower is a bubble tower, and liquid residence time is 20min

The catalysis synthetic tower is a packed tower, and diameter is 5m, and height is 7m, and filler is a cascade ring, RPP material, nominal diameter 50mm

The reaction pressure of desulfurizing tower, oxidizing tower and the control of circular response pond is a normal pressure, and reaction temperature is 50 ℃

The circular response pond absorption liquid time of staying is 5min

Copperas solution initial concentration 20%, magnitude of recruitment are 10.69m ³/ h

Catalyst is a natrium nitrosum, and initial concentration solution is 10%, and magnitude of recruitment is 1092L/h

The mol ratio that the addition of natrium nitrosum and system add the ferrous sulfate amount is 1:15

The mol ratio that removes sulfur dioxide in flue gas amount and ferrous sulfate addition is 0.3:1

Remove 2430 tons/year of sulfur dioxide in flue gas amounts

39094 tons/year of the ferrous sulfate heptahydrate demands of 90% purity

594.1 tons/year of the industrial sodium nitrite demands of catalyst 98% purity

Bodied ferric sulfate output: 37303 tons/year of 64431 tons/year of fluid products or solid products.

Claims (8)

1, the technology of a kind of catalytic oxidation flue gas desulfurization and catalysis method by-product polymerizing iron sulfate is characterized in that:

(1) comprise desulfurizing tower and oxidizing tower in the desulfurization absorption liquid circulation process, the bodied ferric sulfate synthesis system is used to prepare bodied ferric sulfate, and this system comprises circular response pond and catalysis synthetic tower, and the circular response pond is arranged on catalysis synthetic tower tower bottom or independent the setting;

(2) with the copperas solution be the desulfurization absorption liquid, ferrous iron solution quantitatively joins the desulfurizing tower bottom and quantitatively replenishes in sweetening process and makes the concentration of iron ion between 0.1mol/L～1.0mol/L before device starts, sulfur dioxide in flue gas absorbs to dissolve through absorption liquid and is converted into sulfurous acid in desulfurizing tower, catalysed oxidn by means of iron ion, utilize air that part sulfurous acid is oxidized to sulfuric acid, absorption liquid enters oxidizing tower subsequently, by in tower, blasting the carrying out that air promotes that iron ion catalytic oxidation inferior sulfate radical reacts, make desulfurization be dissolved in inferior sulfate radical complete oxidation in the absorption liquid, when sulfuric acid concentration is between 3～10% in the desulfurization absorption liquid, the partial desulfurization absorption liquid is introduced in the circular response pond of bodied ferric sulfate synthesis system;

(3) add natrium nitrosum or nitric acid in the technology as catalyst, in bodied ferric sulfate is synthetic, catalyst and ferrous iron solution constantly quantitatively join the circular response pond in time by the delivery pump that is provided with respectively, and in the circular response pond, carrying out air or industrial pure oxygen aeration, catalyst is finished the oxidation reaction of ferrous ion in catalysis synthetic tower and circular response pond;

(4) dilute sulfuric acid of the ferric sulfate of ferrous sulfate oxidation generation and desulfurization generation is hydrolyzed and polymerisation in catalysis synthetic tower and circular response pond, obtains bodied ferric sulfate.

2, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate is characterized in that gas residence time is 3～15s in the desulfurizing tower, and flue gas desulfurization course liquid-gas ratio control range is at 1～20L/Nm ³Between, the time of staying of desulfurization absorption liquid in oxidizing tower is between 5～60min.

3, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate is characterized in that fume desulfurizing tower, oxidizing tower and catalysis synthetic tower are a kind of of packed tower, spray column, bubble tower or sieve-plate tower.

4, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate, it is characterized in that the reaction pressure of controlling in fume desulfurizing tower, oxidizing tower, catalysis synthetic tower and the circular response pond is a normal pressure, reaction temperature is 20～80 ℃.

5, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate, it is characterized in that bodied ferric sulfate synthetic in the desulfurization absorption liquid of the addition of ferrous sulfate and adding the mol ratio of sulfuric acid amount be 1:0.2～1:0.45.

6, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate is characterized in that the synthetic middle time of staying of circular response liquid in the circular response pond of bodied ferric sulfate is between 5～30min.

7, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate, the mol ratio that it is characterized in that synthetic middle catalyst addition of bodied ferric sulfate and ferrous sulfate addition is 0.03:1～0.5:1, and catalyst is 2～33 to the catalysis multiple of ferrous ion oxidation.

8, the technology of a kind of catalytic oxidation flue gas desulfurization according to claim 1 and catalysis method by-product polymerizing iron sulfate is characterized in that synthetic middle air or the pure oxygen that feeds of bodied ferric sulfate is used as Fe ²⁺The oxidant of oxidation, adding the airborne oxygen content or the amount of adding pure oxygen and the mol ratio of ferrous sulfate addition is 0.25:1～1:1.