WO2016192272A1 - Integrated flue gas treatment device and method - Google Patents

Abstract

An integrated flue gas treatment device and method. The device comprises a flue gas treatment device, an ozone supply device, a hydrogen peroxide supply device, an evaporation and concentration device, a circulating sedimentation device, etc., wherein the flue gas treatment device comprises an ozone spray oxidation reaction layer (82), a hydrogen peroxide spray oxidation reaction layer (92), an absorption spraying area (6), a slurry circulation area and a dedusting and demisting area, both of the ozone spray oxidation reaction layer (82) and the hydrogen peroxide spray oxidation reaction layer (92) being arranged in the absorption spraying area (6); the dedusting and demisting area is located above the absorption spraying area (6); and both of the evaporation and concentration device and the circulating sedimentation device are arranged in the flue gas treatment device.

Description

Flue gas integrated processing device and method Technical field

The invention relates to a flue gas integrated processing device and method, in particular to a device and a method for simultaneously removing sulfur dioxide, nitrogen oxides, mercury and dust in flue gas and using the waste liquid thereof to produce magnesium sulfate magnesium nitrate by-product .

Background technique

The industrially emitted flue gas contains a large amount of harmful substances such as dust, sulfur dioxide (SO ₂ ) and nitrogen oxides (NO _X ), which are the main precursors and important sources of acid rain and smog. Elemental mercury (Hg ⁰ ) is the only toxic heavy metal that is gaseous at normal temperature and pressure. It has the ability to diffuse over long distances and is a global pollutant. Although the mercury content in industrial flue gas is very low, due to the large amount of flue gas, its environmental hazard cannot be ignored. Thus, control of industrial flue gas SO _2, NO _X, dust and mercury emissions in the field of air pollution control main task.

If the above-mentioned pollutants are separately removed, it is necessary to introduce multiple sets of equipment, which has high investment and large land occupation. Therefore, in recent years, various new control technologies for various pollutants of flue gas have emerged, such as simultaneous desulfurization and denitrification of one tower. In the removal of SO ₂ and NO _X in, the NO _X purification Removal of integrated multi-pollutant removal of flue gas SO ₂ than the more difficult, and therefore mainly from the viewpoint of removal of NO _X.

At present, the mainstream denitration technology is selective catalytic reduction denitration (SCR) or selective non-catalytic reduction denitration (SNCR). The SCR method has high denitration efficiency and low secondary pollution, but the equipment investment cost is large, and the catalyst is needed, and the operation and maintenance cost is high; while the SNCR method has less investment and operation cost, but the denitration efficiency is relatively low. The removal efficiency of the above two denitration technologies can reach the current national emission standards, but the process is complicated and controlled. The system is harsh, the investment and operation cost are high, and the floor space is large, which is not suitable for the transformation project. Under the circumstance of increasing emission standards, enterprises are increasingly spending more on denitrification. The denitrification work faces a dilemma: fewer optional technologies; the de-nitration technology that can be applied to actual projects has higher operating costs and construction costs.

Simultaneous desulfurization and denitrification of flue gas by using oxidant combined with wet desulfurization device is a new type of denitration technology. This method uses the principle of forced oxidation to oxidize NO with less solubility in flue gas to high valence state such as NO ₂ or N ₂ O ₅ . Nitrogen oxides (NO _x ) are then absorbed by water or alkaline substances. The oxidant combined with the wet desulfurization device for flue gas simultaneous desulfurization and denitration technology can make full use of the original desulfurization system, and has the advantages of low transformation cost, short cycle, small land occupation, simple process and strong adaptability.

CN103977682A, CN104056538A, CN203916431U disclose a flue gas simultaneous desulfurization and denitration method using O ₃ as an oxidant alone; CN102327735A discloses a flue gas simultaneous desulfurization and denitration method using H ₂ O ₂ as an oxidant; CN102343212A discloses a H ₂ The O ₂ and O ₃ synergistic oxidation combined with the desulfurization and denitration integration process of the wet desulfurization device. The above patent documents all add oxidant O ₃ and H ₂ O ₂ to the flue, and the environment at the flue cannot provide the optimal oxidation condition of the oxidant, so that the oxidation efficiency is lowered, the amount of the oxidant is increased, and the running cost is greatly improved.

Based on a simultaneous desulfurization and denitration technology, an oxidizing agent is used to oxidize NO into water-soluble high-valent oxides NO ₂ and N ₂ O ₅ , and an oxidizing agent can also be used to oxidize mercury (Hg) to high-valent mercury. Remove. Both CN103736373A and CN103480251A disclose a simultaneous desulfurization, denitrification and demercuration method. The boiler flue gas enters the flue after dust removal, and ozone is sprayed at a suitable position in the flue section. The flue gas is mixed with ozone, and then sent to the wet method. The absorption reaction is carried out in the desulfurization tower with the alkaline slurry. These patent documents also add an oxidizing agent to the flue, and thus are also exposed to ozone in a flue temperature environment of 120-160 ° C and a dust content of 50-200 mg/Nm ³ to decompose, adsorb dust and lose activity, resulting in low oxidation efficiency, ozone. The problem is that the consumption is too large and the running cost is increased.

With the concentration and frequent outbreak of smog weather, PM2.5 has been gradually paid attention to, and desulfurization, denitrification and mercury removal have not been able to meet increasingly stringent environmental requirements. The development of a process and device capable of simultaneous desulfurization, denitrification, dust removal and mercury removal has become the main research direction of the environmental protection industry.

CN203525547U discloses a wet-type integrated desulfurization, denitrification, mercury removal and dust removal tower, which realizes wet desulfurization, oxidative denitrification and mercury removal, and wet electricity dedusting from bottom to top on a column. The dust removal method adopts wet dust removal, which not only has high power consumption and large resistance, but also has the effect of removing dust, which is far from meeting the requirements of the new specification, especially the filtration of PM2.5; and the oxidant used in the denitration and mercury removal section is sodium hypochlorite, oxidation. Poor performance and low denitration efficiency.

In combination with the wet desulfurization device to realize a simultaneous desulfurization, denitrification, dehydration and dedusting flue gas treatment technology, the magnesium oxide wet desulfurization process and equipment have been gradually promoted and applied, and the market share has increased from less than 1% in 2005 to over 6 %, it can be seen that the wet magnesium oxide desulfurization technology has been recognized by more and more people. The magnesium oxide desulfurization process is adopted and the desulfurization waste liquid is prepared to form a magnesium sulfate by-product, which not only solves the problem of desulfurization gypsum treatment caused by the conventional calcium desulfurization, but also can offset the operation and maintenance cost of the partial desulfurization device through the sales of the magnesium sulfate by-product. Both technical and economic perspectives have greater market application advantages than traditional calcium methods.

Since the conventional magnesium oxide desulfurization waste liquid production technology uses steam as a medium for evaporation, crystallization, and drying, the method for producing magnesium sulfate by using the desulfurization waste liquid requires a large amount of steam, which directly increases the desulfurization operation cost. CN1733656A discloses a method for preparing magnesium sulfate heptahydrate by using boiler flue gas, wherein the magnesium sulfate solution is concentrated and crystallized, that is, crystallized by using magnesium sulfate at a temperature exceeding 60 ° C, and the high temperature crystallization method is required. Consuming more high-quality steam will cause frequent blockage of the slurry delivery line, making it difficult to achieve continuous and stable production of by-products. CN102745726A discloses a method for producing magnesium sulfate heptahydrate by using desulfurization waste liquid, and the crystallization method used is that the obtained waste liquid is sent to an evaporator for concentration, the evaporation temperature is 100-130 ° C, and the slurry discharged after concentration is 30~ Cooling crystallization at 45 ° C to obtain sulfur sulphate Magnesium acid. This evaporation and crystallization method requires high steam quality, such as increased consumption when using low grade steam. The process disclosed in the above patent document requires about 1.2 to 2 tons of steam to produce one ton of magnesium sulfate. The steam price is calculated at 80 yuan/ton, and the steam consumption cost of one ton of magnesium sulfate is about 160 yuan. Therefore, although the comprehensive cost of magnesium desulfurization is lower than that of the calcium method, there is still a waste of steam resources in the way of producing magnesium sulfate by a three-effect evaporation process outside the magnesium desulfurization tower, and the desulfurization operation cost is still high. Moreover, due to the influence of dust and other impurities in the flue gas, the method of directly producing magnesium sulfate in the tower generally produces a high content of magnesium sulfate impurities, and the later separation is difficult, which affects the quality of magnesium sulfate.

Summary of the invention

In order to overcome the deficiencies of the prior art, the present invention provides a method for synthesizing desulfurization, desulfurization, denitrification, dehydration, dedusting and demisting of flue gas by synergistic oxidation of ozone and hydrogen peroxide by means of a wet absorption desulfurization device, and using the waste liquid to produce magnesium sulfate magnesium sulfate. By-product devices and methods. Apparatus and method of the present invention is particularly suitable for coal-fired boilers, steel sintering machine, pellets, and other industrial furnace containing SO _2, the comprehensive management resource NO _X, Hg in the flue gas and dust and waste utilization.

The invention provides a flue gas integrated processing device, comprising:

The flue gas treatment equipment is internally provided with:

An ozone spray oxidation reaction layer and a hydrogen peroxide spray oxidation reaction layer for synergistic oxidation of low-cost nitrogen oxides and elemental mercury in the flue gas, and formation of high-priced nitrogen oxides and mercury oxide;

Absorbing a spray zone for absorbing sulfur dioxide and nitrogen oxides in the flue gas by using a magnesium oxide method, and collecting mercury oxide in the flue gas to form an absorption slurry;

a slurry circulation zone for receiving the absorption slurry from the absorption spray zone and delivering the absorption slurry to the absorption spray zone and the evaporation concentration device;

Dust removal and defogging area for dust removal and defogging of flue gas;

An evaporation concentration device for evaporating and concentrating the slurry delivered thereto to form a concentrated product Object

a circulating sedimentation device for receiving concentrated product from the evaporation concentration device and sedimenting the concentrated product to form a sedimentation product;

An ozone supply device for supplying ozone to an ozone spray oxidation reaction layer; and

a hydrogen peroxide supply device for supplying hydrogen peroxide to the hydrogen peroxide spray oxidation reaction layer;

Wherein the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer are both disposed in the absorption spray zone; the dust removal and defogging zone is located above the absorption spray zone; the evaporation concentration device and the cycle Settling devices are all disposed inside the flue gas treatment device.

According to the apparatus of the present invention, preferably, the absorption shower zone comprises at least three absorption spray layers, and the at least three absorption spray layers are not adjacent to each other, and the ozone spray oxidation reaction layer and The hydrogen peroxide spray oxidation reaction layers are spaced apart.

According to the apparatus of the present invention, preferably, the absorption shower zone comprises, in order from bottom to top, a first absorption spray layer, a second absorption spray layer and a third absorption spray layer; the ozone spray oxidation reaction layer is disposed at Between the first absorption spray layer and the second absorption spray layer; the hydrogen peroxide spray oxidation reaction layer is disposed between the second absorption spray layer and the third absorption spray layer.

According to the device of the present invention, preferably, the ozone spray oxidation reaction layer is 0.5 to 1.5 m from the first absorption spray layer; and the hydrogen peroxide spray oxidation reaction layer is 0.8 to 1.8 m from the second absorption spray zone. And from the third absorption spray layer 1 ~ 2.2m.

According to the apparatus of the present invention, preferably, the dust removal and defogging zone is 0.2 to 2.0 m from the absorption shower zone.

According to the device of the present invention, preferably, the dust removal and defogging area comprises a dust removal and defogging device, and the dust removal and defogging device is a rotary dust removal and mist eliminator.

According to the device of the present invention, preferably, the device further comprises:

a crystallization apparatus for crystallizing a sedimentation product from a circulating settling apparatus to form a mother liquor and a crystalline product;

a centrifugation apparatus for centrifugally separating a crystalline product from a crystallization apparatus to form a mother liquor and a magnesium sulfate, magnesium nitrate product;

A drying apparatus for drying the magnesium sulfate, magnesium nitrate product from the centrifuge equipment to the finished product.

The invention also provides a method for integrating flue gas treatment by using the above device, comprising the following steps:

Flue gas oxidation step: in the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, the ozone and hydrogen peroxide are used to synergistically oxidize the low-cost nitrogen oxides and elemental mercury in the flue gas, and form high-priced nitrogen oxides and oxidation. HG;

Wet absorption step: in the absorption spray zone, the magnesium oxide method is used to absorb sulfur dioxide and nitrogen oxides in the flue gas, and the mercury oxide in the flue gas is collected to form an absorption slurry;

a slurry circulation step: receiving an absorption slurry from the absorption spray zone in the slurry circulation zone, and conveying the absorption slurry to the absorption spray zone and the evaporation concentrated spray layer;

Evaporation concentration step: evaporating and concentrating the slurry delivered thereto in an evaporation concentration device, and forming a concentrated product;

a cycle sedimentation step: receiving a concentrated product from the evaporation concentration device in a circulating settling device, and sedimenting the concentrated product to form a sedimentation product;

Ozone supply step: supplying ozone to the ozone spray oxidation reaction layer by the ozone supply device;

Hydrogen peroxide supply step: supplying hydrogen peroxide to the hydrogen peroxide spray oxidation reaction layer by a hydrogen peroxide supply device;

Dust removal and defogging step: Dedusting and defogging is performed on the flue gas in the dust removal and defogging area.

According to the method of the present invention, preferably, in the flue gas oxidation step, the process conditions of the ozone spray oxidation reaction layer are: the flue gas temperature is 50-80 ° C, and the dust content is 30-50 mg/Nm ³ , The humidity is greater than 30%, the moisture content of the flue gas is 10% to 15%; the process conditions of the hydrogen peroxide spray oxidation reaction layer are: the flue gas temperature is 40-70 ° C, the water content is 10% to 13%, and the relative humidity is 30% to 40%.

According to the method of the present invention, preferably, the method further comprises:

Crystallization step: crystallizing the sedimentation product from the cycle settling device in a crystallization apparatus to form a mother liquor and a crystalline product;

Centrifugation step: centrifuging the crystallized product from the crystallization apparatus in a centrifugation apparatus to form a mother liquor and a magnesium sulfate, magnesium nitrate product;

Drying step: The magnesium sulfate, magnesium nitrate product from the centrifuge equipment is dried to the finished product in a drying apparatus.

The device and the method of the invention utilize the wet absorption desulfurization equipment, combined with the coordinated oxidation of ozone and hydrogen peroxide, realize the comprehensive treatment of flue gas simultaneous desulfurization, denitrification, demercuration, dedusting and demisting; meanwhile, the flue gas treatment waste liquid is used to produce magnesium sulfate magnesium sulfate. By-products, the resource utilization of flue gas treatment waste liquid is realized. According to a preferred technical solution of the present invention, the apparatus and method of the present invention can save more than 50% of ozone usage, have low operating cost, and have high economical efficiency compared with the conventional ozone oxidation desulfurization and denitrification integrated process. According to a further preferred embodiment of the present invention, the apparatus and method of the present invention have an increased amount of active radical hydroxyl radicals compared to the existing flue gas desulfurization and denitrification integrated process of adding ozone and hydrogen peroxide to the flue. From 100% to 150%, it effectively improves the removal efficiency of nitrogen oxides and elemental mercury. According to a further preferred technical solution of the present invention, the dust removing and defogging device of the present invention adopts a rotary dust removing and defogger, and the demisting effect is 150% higher than that of the flat defogger, which can reduce the flue gas water and save the process water. To achieve the purpose of saving water resources; its resistance is less than that of flat folding or roof demister; its production cost is low, only 50% of wet electrostatic precipitator, and its rotating blade group rotates by smoke flow Therefore, there is no power consumption, and the running cost is only the consumption cost of the dust removing liquid. According to a further preferred technical solution of the present invention, the apparatus and method of the present invention adopt a production process in a by-product tower, which can fully utilize the remainder in the flue gas. The heat is used to evaporate and crystallize the flue gas, which overcomes the problems of low evaporation and concentration efficiency, large steam consumption, high content of dust and impurities in the finished product, poor quality, high production cost per ton of ore and high operating cost of desulfurization. Furthermore, since the apparatus and method of the present invention do not require large-scale modification of the existing desulfurization equipment, the transformation cost is low, the cycle is short, the footprint is small, the process is simple, and the adaptability is strong.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a device according to a first embodiment of the present invention.

In Fig. 1: 1 is a desulfurization tower, 2 is a slurry circulation tank, 21 is a hydrogen peroxide decomposition catalyst, 22 is a slurry circulation tank discharge pump, 23 is a first filter, 24 is a first absorption spray layer circulation pump, 25 For the second absorption spray layer circulation pump, 26 is the third absorption spray layer circulation pump, 3 is the circulation settling tank, 31 is the circulation settling tank discharge port, 32 is the overflow port, 33 is the second filter, 4 is Evaporation and concentration of the spray layer, 41 is the evaporation concentration pump, 42 is the mother liquid back evaporation concentrated spray layer circulation pump, 5 is the liquid accumulator, 6 is the absorption spray area, 61 is the first absorption spray layer, 62 is the second Absorbing the spray layer, 63 is the third absorption spray layer, 7 is the rotary dust removal demister, 8 is the ozone generator, 81 is the ozone transfer pump, 82 is the ozone spray oxidation reaction layer, and 9 is the hydrogen peroxide storage tank. 91 is a hydrogen peroxide injection pump, 92 is a hydrogen peroxide spray oxidation reaction layer, 10 is a crystallization tank, 11 is a centrifuge, 12 is a dryer, 13 is a packaging machine, 14 is a flue gas inlet, and 15 is a flue gas outlet. .

detailed description

The present invention will be further described below in conjunction with the drawings and specific embodiments, but the scope of the present invention is not limited thereto.

The "device" described in the present invention is a product, that is, a system collection of each device. In the present invention, "inlet" has the same meaning as "inlet", and both can be replaced. The "relative humidity" as used herein is expressed as a percentage. The "water content of flue gas" according to the present invention is absolutely Water rate, expressed as a percentage by weight.

In the present invention, the low-valent nitrogen oxides indicate that the nitrogen is a trivalent or lower (including trivalent) nitrogen oxide, including a low-valent nitrogen oxide (NO _X ) such as NO; and the high-priced nitrogen oxide indicates that the nitrogen is a tetravalent The above (including tetravalent) nitrogen oxides include high-valent nitrogen oxides (NO _X ) such as NO ₂ and N ₂ O ₅ .

The "monomeric mercury" as used in the present invention refers to zero-valent mercury (Hg ⁰ ) which exists in the form of a simple substance. The "oxidized mercury" according to the present invention includes HgO, and the mercury in HgO is a divalent oxidation state (Hg ²⁺ ).

The "wet absorption" or "magnesium oxide absorption" according to the present invention has the same meaning and can be used interchangeably, and refers to magnesium oxide as the main component of the desulfurization and denitration agent, but is not limited to adding any other component. Flue gas desulfurization and denitration process (such as calcium oxide, quicklime, etc.). In the "wet absorption" or "magnesium oxide absorption" process, the structure and composition of the desulfurization denitration agent may vary, and formulations or variations thereof are well known to those skilled in the art.

The "absorption slurry" as used in the present invention means a magnesium hydroxide slurry or a magnesium hydroxide slurry containing an absorption product. The "absorption slurry" is a magnesium hydroxide slurry which, when in contact with the flue gas, contains magnesium sulfite, magnesium sulfate, magnesium nitrite, magnesium nitrate, after contact with the flue gas. And absorption products such as oxidized mercury.

The "magnesium sulfate magnesium nitrate" or " magnesium sulfate magnesium nitrate by-product" described in the present invention has the same meaning and can be used interchangeably, and refers to filtering, concentration, crystallization, centrifugation, from the flue gas treatment waste liquid. A by-product of magnesium sulfate and magnesium nitrate as a main component produced by the steps of drying and the like.

The "settling product" as used in the present invention refers to a solid-liquid mixture of crystals and slurry after preliminary crystallization which is formed by sedimentation in a circulating settling apparatus.

The "crystalline product" or "crystal slurry" as used in the present invention has the same meaning and can be used interchangeably, and refers to the solid solution of crystals and slurry formed by crystallization in a crystallization apparatus. mixture.

"Substantially free" as used herein means a content of less than 1% by weight, preferably less than 0.5% by weight, more preferably 0% by weight.

<Fume gas integrated treatment device>

The flue gas integrated treatment device of the invention can realize the functions of flue gas desulfurization, denitrification, dehydration, dedusting, dedusting and demisting and producing magnesium sulfate magnesium nitrate. It includes the following devices: a flue gas treatment device, an ozone supply device, a hydrogen peroxide supply device, an evaporation concentration device, and a circulation sedimentation device. According to the apparatus of the present invention, the flue gas treatment device is internally provided with: an ozone spray oxidation reaction layer and a hydrogen peroxide spray oxidation reaction layer, an absorption spray zone and a slurry circulation zone, a dust removal and defogging zone, wherein the ozone spray The oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer are both disposed in the absorption spray zone, and the dust removal and defogging zone is disposed in an upper portion of the absorption spray zone. Optionally, the apparatus of the present invention also includes other dedusting equipment and packaging equipment.

The flue gas treating device of the present invention comprises an ozone spray oxidation reaction layer and a hydrogen peroxide spray oxidation reaction layer, which are all disposed in the absorption spray zone (rather than disposed in the flue) for synergistic oxidation of the low temperature in the flue gas. Nitrogen oxides (such as NO) and elemental mercury (Hg ⁰ ), and form high-priced nitrogen oxides (such as NO ₂ , N ₂ O _{5 ,} etc.) and oxidized mercury (HgO). Among them, the high-priced nitrogen oxides are easily absorbed by the alkaline slurry, which is easily trapped by the alkaline slurry. In the ozone spray oxidation reaction layer, ozone is sprayed downward through the ozone atomizing spray member. In the hydrogen peroxide spray oxidation reaction layer, hydrogen peroxide is sprayed downward through the hydrogen peroxide atomizing spray unit. The atomized spray member used in the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer is not particularly limited, and those well known in the art can be used. Preferably, the atomized spray member of the present invention is a corrosion-resistant atomized spray member, and more preferably an acid-resistant and alkali-resistant spray atomized spray member. According to an embodiment of the invention, the atomized spray component preferably comprises a stainless steel nozzle. Ozone sprayed by the ozone spray oxidation reaction layer and hydrogen peroxide sprayed by the hydrogen peroxide spray oxidation reaction layer are oxidized with low-valent nitrogen oxides and elemental mercury in the flue gas to form high-priced nitrogen oxides and mercury oxide. The main principles are as follows.

A. Ozone oxidation reaction steps:

1) Ozone as an oxidant to initiate oxidation:

O ₃ +NO→NO ₂ +O ₂

NO ₂ +O ₃ →NO ₃ +O ₂

NO ₂ +NO ₃ →2N ₂ O ₅

2) Ozone initiates a chain reaction in a suitable humidity and environment containing hydroxide ions:

O ₃ +OH ^- →HO ₂ ·+O ₂ ·

HO ₂ ·→O ₂ ^- ·+H ⁺

O ₃ +O ₂ ^- ·→O ₃ ^- ·+O ₂

O ₃ ^- ·+H ⁺ →HO ₃ ·

HO ₃ ·→HO·+O ₂ ·

3) The active substance hydroxyl radical reacts with nitrogen oxides in the flue gas:

HO·+NO→HONO

HO·+HONO→NO ₂ +H ₂ O

HO·+NO ₂ →HNO ₃

HO·+HONO→HNO ₃ +H·

HNO ₃ +OH ^- →NO ₃ ^- +HO ₂

B. Hydrogen peroxide reaction step:

1) Hydrogen peroxide is excited and reacts to form active substances:

H ₂ O ₂ →2·OH

H ₂ O ₂ +·OH→HO ₂ ·+H ₂ O

2) Oxidation of hydrogen peroxide with nitrogen monoxide and nitrogen dioxide at normal temperature:

H ₂ O ₂ (g) + NO (g) → NO ₂ (g) + H ₂ O (g) (relatively slow)

H ₂ O ₂ (g) + NO ₂ (g) → HNO ₃ (g) (faster)

3) Ozone activated hydrogen peroxide:

4) The active substance hydroxyl radical reacts with nitrogen oxides in the flue gas:

NO+·OH→NO ₂ +·H

NO+HO ₂ ·→NO ₂ +·OH

NO+·OH→HNO ₂

NO ₂ +·OH→HNO ₃

HNO ₂ +·OH→HNO ₃

Mg(OH) ₂ +2HNO ₂ →Mg(NO ₂ ) ₂ +2H ₂ O

Mg(OH) ₂ +HNO ₃ →Mg(NO ₃ ) ₂ +2H ₂ O

Mg(NO ₂ ) ₂ +O ₂ →Mg(NO ₃ ) ₂

5) Optionally, a hydrogen peroxide decomposition catalyst such as MnO ₂ is added to the alkaline slurry, and at this time, the hydrogen peroxide which has not been excited reacts to generate oxygen under the action of the hydrogen peroxide decomposition catalyst:

Wherein, the oxygen in the hydrogen peroxide oxidation reaction step 4) is derived from three parts: one part is oxygen contained in the original flue gas, and the other part is oxygen generated by the unexcited hydrogen peroxide generated by the hydrogen peroxide decomposition catalyst, and Part of the oxygen is supplied to the remaining unreacted gas source of the flue gas treatment equipment along with the generated ozone in the ozone supply equipment.

C, oxidation step of elemental mercury:

Hg+O ₃ →HgO+O ₂

H ₂ O ₂ +Hg→HgO+H ₂ O

HgO+2HNO ₃ →Hg(NO ₃ ) ₂ +H ₂ O (weak reaction)

In the apparatus of the present invention, in the ozone spray oxidation reaction layer, the flue gas temperature may be 50 to 80 ° C, preferably 60 to 70 ° C; and the dust content may be 30 to 50 mg / Nm ³ , preferably 35 to 45 mg / Nm. ³ ; the relative humidity may exceed 30%, preferably exceed 40%; the moisture content of the flue gas may be 10% to 15%, preferably 12% to 13%. Under the conditions, the ozone is slowly decomposed, and the spray layer slurry is alkaline to provide hydroxide ions. The humidity, temperature and hydroxide ion content are particularly suitable for decomposing more hydroxyl radicals, and the hydroxyl radicals are A substance that is more oxidizing than ozone can oxidize nitrogen monoxide to nitrogen dioxide more quickly, thereby saving ozone. Further, the hydroxyl radical reacts with nitrogen oxides in the flue gas to form nitric acid and nitrous acid.

In the apparatus of the present invention, in the hydrogen peroxide spray oxidation reaction layer, the flue gas temperature may be 40 to 70 ° C, preferably 50 to 60 ° C; the flue gas moisture content may be 10% to 13%, preferably 11%. ～12%; the relative humidity may be 30% to 40%, preferably 35% to 38%. Under the conditions described, hydrogen peroxide can be excited to excite more active hydroxyl radicals (·OH and · O ₂ H). The reaction rate of the active material hydroxyl radical and nitrogen monoxide is 300% of the reaction speed of hydrogen peroxide and nitric oxide, which can accelerate the oxidation of nitric oxide and improve the efficiency of oxidative denitration. Optionally, the flue gas treating apparatus of the present invention is further provided with another ozone spray oxidation reaction layer and a hydrogen peroxide spray oxidation reaction layer, the number of which is not particularly limited, depending on the oxidation.

The flue gas treating apparatus of the present invention further includes an absorption shower zone for absorbing sulfur dioxide and nitrogen oxides in the flue gas by a magnesium oxide method and trapping oxidized mercury in the flue gas to form an absorption product. Among them, the main reaction principle of the magnesium oxide absorption of nitrogen oxides has been mentioned in the previous description of the oxidation oxidation reaction step, and the main reaction principle of the magnesium oxide absorption sulfur dioxide is as follows.

D, sulfur dioxide wet absorption steps:

Mg(OH) ₂ +SO ₂ →MgSO ₃ +H ₂ O

MgSO ₃ +H ₂ O+SO ₂ →Mg(HSO ₃ ) ₂

Mg(HSO ₃ ) ₂ +1/2O ₂ →MgSO ₃

Wherein, the source of oxygen is the same as the source of oxygen in step 4) of the hydrogen peroxide oxidation step.

In the absorption spray zone of the flue gas treating apparatus of the present invention, the magnesium oxide method is used to absorb sulfur dioxide and nitrogen oxides in the flue gas. The absorption spray zone of the present invention preferably comprises at least one absorption spray layer located below the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, which is capable of absorbing most of the sulfur dioxide by the magnesium oxide method to form magnesium sulfite and In addition to the absorption slurry of magnesium sulfate, part of the dust in the flue gas can be removed to prevent the dust from directly entering the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, thereby affecting the oxidation activity of the active material hydroxyl radical. More preferably, the absorption shower zone comprises at least three absorption spray layers, and the three absorption spray layers are not adjacent to each other, and are interposed between the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer. Separated. Wherein at least one absorption spray layer located under the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, in addition to being capable of absorbing most of the sulfur dioxide by the magnesium oxide method, forming an absorption slurry containing magnesium sulfite and magnesium sulfate. In addition, it is also possible to remove some of the dust in the flue gas.

According to an embodiment of the present invention, the absorption spray zone includes a first absorption spray layer, a second absorption spray layer and a third absorption spray layer in order from bottom to top; the ozone spray oxidation reaction layer is disposed in the first absorption Between the spray layer and the second absorption spray layer; the hydrogen peroxide spray oxidation reaction layer is disposed between the second absorption spray layer and the third absorption spray layer. In this embodiment, the ozone in the ozone spray oxidation reaction layer can flow back into the hydrogen peroxide spray oxidation reaction layer with the flue gas, and this part of ozone can also act as an activator of hydrogen peroxide, thereby exciting Hydrogen peroxide produces more active hydroxyl radicals. Preferably, the ozone spray oxidation reaction layer is disposed between the first absorption spray layer and the second absorption spray layer in the flue gas treatment device, and is 0.5 to 1.5 m, preferably 0.7 to 1.0 from the first absorption spray layer. Position of m; the hydrogen peroxide spray oxidation reaction layer is disposed between the second absorption spray layer and the third absorption spray layer in the flue gas treatment device, and is 1.0 to 2.2 m away from the third absorption spray layer, preferably 1.5 to 2.0 m, a distance from the second absorption shower layer of 0.8 to 1.8 m, preferably 1.0 to 1.5 m. According to an embodiment of the present invention, the spacing between the first spray layer and the second absorption spray layer in the flue gas denitration device is 1.5 to 3.5 m, preferably 1.8 to 2.5 m; and the flue gas denitration device is in the first The spacing between the second spray layer and the third absorption spray layer is increased from the original 1.8 to 2.5 m to 2.8 m to 3.5 m, preferably 2.8 to 3.0 m.

The flue gas treating apparatus of the present invention further comprises a slurry circulation zone for receiving the absorption slurry (containing absorption products such as magnesium sulfite, magnesium sulfate, magnesium nitrite, magnesium nitrate and oxidized mercury) from the absorption spray zone, and absorbing The slurry is transferred to an absorption spray zone and an evaporation concentration device. According to an embodiment of the present invention, the slurry circulation zone is connected to the absorption spray zone via a circulation pump for conveying the absorption slurry (magnesium hydroxide slurry or magnesium hydroxide slurry containing absorption products) to the absorption spray zone. At the same time, the slurry circulation device is connected to the evaporation concentration device via a discharge pump and a filter for filtering the absorption slurry (magnesium hydroxide slurry containing the absorption product) through a filter and then transporting it to an evaporation concentration device for evaporation concentration. The type of the filter is not particularly limited, and those well known in the art can be used. Preferably, the absorbent slurry from the absorption spray zone enters the slurry circulation zone via the accumulator. According to an embodiment of the invention, the liquid reservoir is disposed between the evaporation concentration device and the absorption shower zone. The material of the liquid eliminator may be a fiber reinforced composite plastic FRP, and preferably has a temperature resistance range of 50 to 95 ° C; however, it is not limited to the above materials, and a facility capable of collecting the slurry can be used. According to one embodiment of the invention, a hydrogen peroxide decomposition catalyst is added to the slurry in the slurry circulation zone. In this embodiment, the hydrogen peroxide that has not been excited reacts into the slurry storage area and contacts the hydrogen peroxide decomposition catalyst in the slurry to decompose. In the absence of secondary pollution of water and oxygen, the generated oxygen then oxidizes sulfites and nitrites into sulfates and nitrates. The type of the hydrogen peroxide decomposition catalyst is not particularly limited, and those well known in the art can be used. Preferably, the hydrogen peroxide decomposition catalyst comprises ferric chloride, ferric oxide, manganese dioxide, copper oxide, etc., and those disclosed in CN101252991A, CN103272615A, CN104307520A, CN104289228A may also be used. Preferably, the hydrogen peroxide decomposition catalyst of the present invention is manganese dioxide. The amount of the hydrogen peroxide decomposition catalyst to be used is also not particularly limited and may be determined depending on the actual situation. If the slurry is well oxidized, the hydrogen peroxide decomposition catalyst may not be added to the slurry in the slurry circulation zone.

The flue gas treating device of the present invention further comprises a dust removing and defogging zone for dusting and defogging the flue gas, wherein the dust removing and defogging zone is located above the absorption showering zone and the distance from the absorption showering zone It is preferably 0.2 m to 2.0 m, more preferably 0.5 m to 1.5 m, and most preferably 0.5 m to 0.8 m. The dust removal and defogging zone of the present invention comprises a dust removal and defogging device. The dust removing and defogging device of the present invention preferably employs a rotary dust removing and mist eliminator. The rotary dust removing and mist eliminator can adopt those disclosed in CN201195093Y. The rotary dust eliminator can replace the existing demister and wet electrostatic precipitator, and its dust removal and defogging effect is better than the combination of the two. According to an embodiment of the present invention, the rotary dust removing and mist eliminator used is internally provided with a spraying device in which the atomized dust removing liquid is sprayed. The atomized dust removing liquid is in contact with the flue gas from the absorption spray area, and can collect the fine dust in the flue gas, and at the same time, can interact with the mist in the flue gas to achieve the flocculation effect, and increase the quality of the mist drop to cause it to fall. . The dust-removing liquid carrying the smoke dust and the mist droplets re-condenses into large droplets during the process of dust removal and de-fogging, falls into the liquid accumulator, and is recycled after being collected. The formulation of the dust removing liquid is not particularly limited, and those well known in the art can be used. The flue gas dust content of the flue gas treated by the dust removing and defogging device of the present invention is preferably less than 10 mg/Nm ³ , more preferably less than 5 mg/Nm ³ , and the droplet content thereof is preferably less than 40 mg/Nm ³ , more preferably Less than 25mg/Nm ³ .

Optionally, the apparatus of the present invention also includes other dust removal equipment located in the flue gas inlet Any position before the flue gas treatment equipment to remove dust entrained in the flue gas. The type and process conditions of the dust removing device are not particularly limited, and dust removing devices and processes well known in the art can be used.

The ozone supply device of the present invention is for supplying ozone to an ozone spray oxidation reaction layer. Since ozone is easily decomposed and difficult to store, it is usually used on site for on-site use. According to an embodiment of the invention, the ozone supply device comprises an ozone generator. The type of the ozone generator is not particularly limited, and those well known in the art can be used. In an ozone generator, oxygen molecules in a gas source are converted to ozone molecules by physical and/or chemical reactions. The gas source of the ozone generator may be selected from liquid oxygen, gaseous oxygen or a source of air, preferably liquid oxygen. The liquid oxygen used as the gas source of the ozone generator preferably has a purity of 90% or more, more preferably 99.5%. The concentration of ozone in the product of the ozone generator (which may also be referred to as a supply) is preferably from 2% by weight to 12% by weight, more preferably from 5% by weight to 10% by weight. According to an embodiment of the present invention, ozone in the ozone supply device is delivered to the ozone spray oxidation reaction layer through the ozone transfer pump and the ozone transfer line. The number and arrangement of the ozone transfer pump and the ozone delivery line are not particularly limited, and a pump and piping design well known in the art can be used.

The hydrogen peroxide supply device of the present invention is for supplying hydrogen peroxide to a hydrogen peroxide spray oxidation reaction layer. According to an embodiment of the invention, the hydrogen peroxide supply device comprises a hydrogen peroxide storage tank in which hydrogen peroxide is stored. The type of the hydrogen peroxide storage tank is not particularly limited, and those well known in the art can be used. The hydrogen peroxide in the hydrogen peroxide supply device is preferably present in the form of an aqueous solution (supply) in view of storage safety and ease of use, and its concentration is preferably from 3 wt% to 35 wt%, more preferably from 10 wt% to 27.5 wt%. According to an embodiment of the invention, the hydrogen peroxide in the hydrogen peroxide storage tank is sent to the hydrogen peroxide spray oxidation reaction layer through a hydrogen peroxide delivery line through a syringe pump. The number and arrangement of the hydrogen peroxide delivery lines are not particularly limited, and piping designs well known in the art can be used.

The apparatus of the present invention further includes an evaporation concentration apparatus for performing a circulating evaporation concentration of the slurry (a slurry containing magnesium sulfate of magnesium sulfate) delivered thereto, and forming a concentrated product. Preferably, the evaporation concentration device is disposed inside the flue gas treatment device. More preferably, the evaporation concentration device is disposed inside the flue gas treatment device and is located below the absorption spray zone. Preferably, the evaporation concentration device comprises an evaporation concentrated spray layer. According to an embodiment of the present invention, in the evaporation concentrated spray layer, the slurry (slurry containing magnesium sulfate and magnesium nitrate) sprayed from the evaporation concentrated spray layer is in contact with the flue gas carrying the residual heat, and the waste heat of the flue gas Evaporation and concentration are carried out under the action, and the formed concentrated product falls into the circulating sedimentation device by its own gravity.

The apparatus of the present invention also includes a cyclic settling apparatus for receiving the concentrated product from the evaporation concentration apparatus and allowing the concentrated product to settle to form a sedimentation product (including a preliminary crystallization process). Preferably, the circulation settling device is disposed inside the flue gas treatment device. More preferably, the circulation settling device is disposed inside the flue gas treatment device and is located below the evaporation concentration device. Further preferably, the circulating settling device is located below the flue gas inlet. The circulating settling device of the present invention preferably employs a circulating settling tank. Depending on the operating conditions, the cyclic settling device can be configured as a single layer settling, double layer settling or multiple layer settling. The material of the circulating sedimentation equipment is preferably FRP, special steel or ordinary steel material plus anti-corrosion treatment. According to an embodiment of the present invention, an upper portion of the circulating settling device is provided with an overflow port that communicates with the evaporating and concentrating device via a filter for overflowing the slurry (substantially crystal-free slurry) from the upper portion of the circulating settling device The mouth overflows and is filtered through the filter and then sent to the evaporation concentration device; the bottom of the circulation sedimentation device is provided with a discharge port which communicates with the crystallization device for discharging the sedimentation product at the bottom of the circulating sedimentation device from the discharge port to the crystallization device in. The sedimentation product formed in the circulating settling apparatus preferably has a solid content of more than 25% by weight, more preferably more than 30% by weight, wherein the magnesium sulfate and magnesium nitrate crystals contained have a particle size of more than 0.05 mm, more preferably more than 0.10 mm.

Preferably, the apparatus of the present invention further comprises crystallization equipment for receiving the settled product in the circulating settling apparatus and further crystallizing it to obtain a mother liquor and a crystalline product. In order to prevent grain sedimentation, a stirring device is preferably arranged in the crystallization device, and the stirring device can be air-stirred. Device or electric stirring device, etc. According to one embodiment of the invention, the crystallization apparatus of the present invention employs a cooled crystallization settling tank. Preferably, the cooling crystallization settling tank has an automatic cooling system with a water cooling ring device, and the cold source may be normal temperature water or chilled water, or a cooling tower such as a cooling water tower may be separately provided. The crystalline product (crystallized) formed in the crystallization apparatus preferably has a solid content of more than 35 wt%, more preferably more than 40 wt%, wherein the magnesium sulfate magnesium nitrate crystals contained have a particle size of more than 0.15 mm, more preferably more than 0.20 mm. Preferably, the crystallization apparatus is in communication with the evaporation concentration apparatus for conveying the mother liquor formed by the crystallization apparatus to an evaporation concentration apparatus for evaporation concentration.

Preferably, the apparatus of the present invention further comprises a centrifugation apparatus for centrifuging the crystalline product (crystall) from the crystallization apparatus to form a mother liquor and a magnesium sulfate, magnesium nitrate product. The type of the centrifugal device is not particularly limited, and those well known in the art can be used. According to an embodiment of the present invention, the centrifugation device is connected to the evaporation concentration device via a mother liquor back evaporation concentration device circulation pump for re-delivering the mother liquid formed by centrifugation to an evaporation concentration device for evaporation concentration. The magnesium sulfate, magnesium nitrate product formed in the centrifuge apparatus preferably has a water content of less than 10% by weight, more preferably less than 5% by weight, most preferably less than 2% by weight.

Preferably, the apparatus of the present invention further comprises drying means for drying the magnesium sulfate, magnesium nitrate product from the centrifugation apparatus to the finished product. The type of the drying device is not particularly limited, and those well known in the art can be used.

Optionally, the apparatus of the present invention further includes packaging equipment for packaging the finished product from the drying apparatus. The type of packaging apparatus is not particularly limited, and those well known in the art can be used.

In addition, the "discharge" described in the present invention (for example, discharging sedimentation products from a circulating sedimentation apparatus, discharging crystalline products from a crystallization apparatus, discharging magnesium sulfate and magnesium nitrate crystals from a centrifugal apparatus, etc.) may use a discharge apparatus in a specific In an embodiment, the discharge device is a discharge pump.

<Method of integrated treatment of flue gas>

The method for integrating the flue gas by using the above device of the present invention is a method for simultaneous desulfurization, denitrification, demercuration, dedusting and demisting of flue gas and producing magnesium nitrate magnesium sulfate. It comprises the following steps: a flue gas oxidation step, a wet absorption step, a slurry circulation step, an ozone supply step, a hydrogen peroxide supply step, a dust removal and defogging step, an evaporation concentration step, and a cycle sedimentation step. Optionally, the method of the invention also includes other dust removal steps and packaging steps.

The method of the present invention comprises a flue gas oxidation step for synergistically oxidizing low-cost nitrogen oxides and elemental mercury in the flue gas by using ozone and hydrogen peroxide in the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, and Formation of high-priced nitrogen oxides and mercury oxide. Preferably, the flue gas oxidation step of the present invention comprises: in the ozone spray oxidation reaction layer, the ozone is sprayed downward by the ozone atomizing spray member; and in the hydrogen peroxide spray oxidation reaction layer, the atom spray is sprayed by hydrogen peroxide. The shower unit sprays hydrogen peroxide downward. The atomization spray process employed in the flue gas oxidation step is not particularly limited, and those well known in the art can be used. According to an embodiment of the invention, the flue gas oxidation step preferably uses a stainless steel nozzle to spray ozone and hydrogen peroxide. The principle of synergistic oxidation of ozone and hydrogen peroxide is as described above. According to an embodiment of the present invention, the flue gas oxidation step comprises sequentially passing the flue gas through the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer from bottom to top. In this embodiment, the unreacted ozone ejected from the ozone spray oxidation reaction layer rises into the hydrogen peroxide spray oxidation reaction layer with the flue gas to further activate hydrogen peroxide. According to another embodiment of the present invention, the flue gas oxidation step comprises sequentially passing the flue gas through the hydrogen peroxide spray oxidation reaction layer and the ozone spray oxidation reaction layer from bottom to top. In this embodiment, the unreacted ozone ejected from the ozone spray oxidation reaction layer enters the hydrogen peroxide spray oxidation reaction layer to further activate hydrogen peroxide. Optionally, the flue gas oxidation step of the present invention further comprises passing the flue gas through the other ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, the amount of which is not particularly limited, depending on the oxidation. Ozone spray oxidation reaction layer process conditions, hydrogen peroxide The process conditions for spraying the oxidation reaction layer are as described above and will not be described again here.

The method of the present invention further includes a wet absorption step for absorbing sulfur dioxide and nitrogen oxides in the flue gas using a magnesium oxide method and trapping oxidized mercury in the flue gas to form an absorption product.

According to an embodiment of the present invention, the wet absorption step comprises sequentially passing the flue gas from the bottom to the top through the first absorption spray layer, the ozone spray oxidation reaction layer, the second absorption spray layer, and the hydrogen peroxide spray oxidation reaction layer. And a third absorption spray layer.

Optionally, the wet absorption step of the present invention further comprises passing the fumes through other absorbent spray layers, the amount depending on the amount of sulfur dioxide and nitrogen oxides in the flue gas.

The method of the present invention further includes a slurry recycling step for receiving an absorption slurry (containing an absorption product such as magnesium sulfite, magnesium sulfate, magnesium nitrite, magnesium nitrate, and oxidized mercury) from the absorption shower zone, and delivering the absorption slurry to Absorb the spray zone and the evaporation concentration unit. According to an embodiment of the present invention, in the slurry circulation step, the absorption slurry (magnesium hydroxide slurry or the magnesium hydroxide slurry containing the absorption product) is transported to the absorption spray zone by a circulation pump, and at the same time, the absorption slurry is absorbed ( The magnesium hydroxide slurry containing the absorption product is filtered through a filter and sent to an evaporation concentration device for concentration by evaporation. Preferably, the absorbent slurry from the absorption spray zone is passed through the effluent into the slurry circulation zone. According to an embodiment of the present invention, in the slurry circulation step, a hydrogen peroxide decomposition catalyst is added to the slurry in the slurry circulation zone. The type and amount of the hydrogen peroxide decomposition catalyst are as described above and will not be described herein.

The method of the present invention further includes an ozone supply step for supplying ozone to the ozone spray oxidation reaction layer by the ozone supply device. According to an embodiment of the present invention, ozone is generated from a gas source in an ozone generator, and the generated ozone is sent to an ozone spray oxidation reaction layer by an ozone transfer pump. The gas source of the ozone generator is selected from the group consisting of liquid oxygen, gaseous oxygen or a source of air, preferably liquid oxygen. The liquid oxygen used as the gas source of the ozone generator preferably has a purity of 99.5%. The ozone generator generates an ozone concentration of preferably 2% by weight to 12% by weight, more preferably 5% by weight to 10% by weight.

The method of the present invention further includes a hydrogen peroxide supply step for supplying hydrogen peroxide to the hydrogen peroxide spray oxidation reaction layer from the hydrogen peroxide supply device. According to an embodiment of the invention, the hydrogen peroxide is stored in the form of an aqueous solution in a hydrogen peroxide storage tank, and the aqueous hydrogen peroxide solution in the hydrogen peroxide storage tank is sent to the hydrogen peroxide spray through the hydrogen peroxide delivery line through a syringe pump. Oxidation reaction layer. The concentration of the aqueous hydrogen peroxide solution in the hydrogen peroxide storage tank is preferably from 3% by weight to 35% by weight, more preferably from 10% by weight to 27.5% by weight.

The method of the invention further comprises the steps of dust removal and demisting, wherein the dust removal and defogging device is used in the dust removal and defogging area to perform dust removal and defogging on the smoke. According to an embodiment of the present invention, in the dust removing and defogging step, the flue gas is dedusted and defogged by a rotary dust removing and defogging device, and a spray device is disposed inside the spray device, and the atomized dust removing liquid is sprayed in the spray device. In the embodiment, the atomized dust removing liquid is in contact with the flue gas from the absorption spray area, and collects fine dust in the flue gas, and simultaneously acts with the mist in the flue gas to achieve a flocculation effect and aggravate the fog. The drop quality makes it fall. The dust-removing liquid carrying the smoke dust and the mist droplets re-condenses into large droplets during the process of dust removal and de-fogging, falls into the liquid accumulator, and is recycled after being collected. The flue gas dust content after the dust removal and defogging step treated by the dust removal and defogging step of the present invention is preferably less than 10 mg/Nm ³ , more preferably less than 5 mg/Nm ³ , and the droplet content thereof is preferably less than 40 mg/Nm ³ , more preferably Less than 25mg/Nm ³ .

Optionally, the method of the present invention further includes additional dust removal steps for removing dust entrained in the flue gas before it enters the flue gas treatment facility. The process conditions of the dust removing step are not particularly limited, and a dust removing process well known in the art can be used.

The method of the present invention further includes an evaporation concentration step for concentrating the slurry (slurry containing magnesium sulfate magnesium sulfate) delivered thereto in an evaporation concentration apparatus to form a concentrated product by circulating evaporation. Preferably, in the evaporation concentration step, the spray layer is concentrated by evaporation to concentrate. According to an embodiment of the present invention, in the evaporation concentration step, the slurry sprayed from the evaporation concentrated spray layer (the slurry containing magnesium sulfate magnesium sulfate) is contacted with the flue gas carrying the residual heat, and is concentrated by evaporation under the residual heat of the flue gas. The concentrated product formed falls into the circulating sedimentation device by its own gravity.

The method of the present invention also includes a cycle settling step for receiving the concentrated product from the evaporation concentration apparatus in a circulating settling apparatus and sedimenting the concentrated product to form a sedimentation product (including a preliminary crystallization process). Preferably, in the cyclic settling step, sedimentation is carried out using a circulating settling tank. According to an embodiment of the present invention, the slurry (the substantially crystal-free slurry) in the upper portion of the circulating settling device overflows from the overflow port and is filtered through the filter and then sent to the evaporation concentration device; the sedimentation product at the bottom of the circulating sedimentation device is The discharge port is discharged and sent to the crystallization apparatus. The sedimentation product formed by the cyclic sedimentation step preferably has a solid content of more than 25% by weight, more preferably more than 30% by weight, wherein the magnesium sulfate and magnesium nitrate crystals contained have a particle size of more than 0.05 mm, more preferably more than 0.10 mm.

Preferably, the method of the present invention further comprises a crystallization step for receiving the settled product in the circulating settling apparatus in a crystallization apparatus and further crystallizing it to obtain a crystalline product. According to one embodiment of the invention, in the crystallization step, crystallization is carried out using a cooled crystallization settling tank. The crystalline product (crystallized) formed by the crystallization step preferably has a solid content of more than 35 wt%, more preferably more than 40 wt%, wherein the magnesium sulfate and magnesium nitrate crystals contained have a particle size of more than 0.15 mm, more preferably more than 0.20 mm. Preferably, the crystallization step further comprises conveying the mother liquor formed by the crystallization step to an evaporation concentration device for evaporation concentration.

Preferably, the method of the present invention further comprises a centrifugation step for centrifuging the crystalline product (crystall) from the crystallization apparatus in a centrifugation apparatus to form a mother liquor and a magnesium sulfate, magnesium nitrate product. According to an embodiment of the present invention, in the centrifugation step, the mother liquor formed by centrifugation is re-delivered to an evaporation concentration apparatus for evaporation concentration. The magnesium sulfate, magnesium nitrate product formed by the centrifugation step preferably has a water content of less than 10% by weight, more preferably less than 5% by weight, most preferably less than 2% by weight.

Preferably, the method of the present invention further comprises a drying step for drying the magnesium sulfate, magnesium nitrate product from the centrifuge device to the finished product in a drying apparatus. The type of the drying device is not particularly limited, and those well known in the art can be used.

Optionally, the method of the invention further comprises a packaging step for pairing in the packaging device The finished product of the drying equipment is packaged. The process conditions of the packaging step are not particularly limited, and a packaging process well known in the art can be used.

The invention will be described in more detail below with reference to the accompanying drawings.

The raw materials used in the following examples of the invention are as follows:

The H ₂ O ₂ solution is an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 27.5 wt%;

The O ₃ product has an ozone concentration of 10% by weight;

The hydrogen peroxide decomposition catalyst is manganese dioxide.

Example 1

Fig. 1 is a view showing the apparatus of Embodiment 1 of the present invention. As can be seen from the figure, the flue gas integrated treatment apparatus of the present invention comprises a desulfurization tower 1, an ozone generator 8, a hydrogen peroxide storage tank 9, and a rotary dust removing demister 7. The desulfurization tower 1 includes an ozone spray oxidation reaction layer 82, a hydrogen peroxide spray oxidation reaction layer 92, an absorption spray zone 6, a slurry circulation tank 2, an evaporation concentrated spray layer 4, and a circulation settling tank 3, wherein the ozone spray oxidation reaction layer 82 and hydrogen peroxide spray oxidation reaction layer 92 are disposed in the absorption spray zone 2; the rotary dust removal demister 7 is located above the absorption spray zone 6; the evaporation concentrated spray layer 4 and the circulation settling tank 3 are both set in the desulfurization Inside the tower 1. The absorption shower zone 6 includes a first absorption spray layer 61, a second absorption spray layer 62, and a third absorption spray layer 63. The ozone spray oxidation reaction layer 82 is located between the first absorption shower layer 61 and the second absorption shower layer 62. The hydrogen peroxide spray oxidation reaction layer 92 is located between the second absorption shower layer 62 and the third absorption shower layer 63. The ozone spray oxidation reaction layer 82 is 1.0 m from the first absorption shower layer 61; the hydrogen peroxide spray oxidation reaction layer 92 is 1.6 m from the third absorption shower layer 63 and 1.5 m from the second absorption shower layer 62. The ozone generator 8 communicates with the ozone spray oxidation reaction layer 82 via an ozone transfer pump 81 and an ozone delivery line. The hydrogen peroxide storage tank 9 communicates with the hydrogen peroxide spray oxidation reaction layer 92 through a hydrogen peroxide delivery line through a hydrogen peroxide injection pump 91. Rotary dust removal and defogging The device 7 is located above the absorption shower zone 6 and is 0.6 m from the absorption shower zone 6. The evaporation concentrated spray layer 4 is located below the absorption spray layer 6 and above the flue gas inlet 14. An accumulator 5 is disposed between the absorption shower zone 6 and the evaporative concentration spray layer 4. The slurry circulation tank 2 is located below the evaporation concentrated spray layer 4. A hydrogen peroxide decomposition catalyst 21 is added to the slurry in the slurry circulation tank 2. The slurry in the slurry circulation tank 2 is respectively sent to the first absorption spray through the slurry absorption pipeline through the first absorption spray layer circulation pump 24, the second absorption spray layer circulation pump 25, and the third absorption spray layer circulation pump 26. The layer 61, the second absorption shower layer 62 and the third absorption shower layer 63. The absorption slurry in the slurry circulation tank 2 is sent to the evaporation concentrated spray layer 4 through the slurry circulation tank discharge pump 22, the first filter 23, and the evaporation concentration pump 41. The circulating settling tank 3 is located above the slurry circulating tank 2 and is located below the flue gas inlet 14. A circulation settling tank discharge port 31 is provided at the bottom of the circulating settling tank 3, and communicates with the crystallization tank 10. An overflow port 32 is disposed in an upper portion of the circulating settling tank 3, and communicates with the evaporative concentrated spray layer 4 via a second filter 33 and an evaporative concentration pump 41. The crystallization tank 10 is connected to the centrifuge 11, the dryer 12, and the packaging machine 13 in this order. The crystallization tank 10 is connected to the evaporation concentrated spray layer 4 via a mother liquid back evaporation concentrated spray layer circulation pump 42. The centrifuge 11 is connected to the evaporative concentrated spray layer 4 via a mother liquor back to the concentrated concentration spray layer circulation pump 42. A flue gas outlet 15 is provided at the top of the desulfurization tower 1.

The process flow of Embodiment 1 of the present invention is:

a. The flue gas enters the desulfurization tower 1 from the flue gas inlet 14 of the desulfurization tower 1, passes through the first absorption spray layer 61, and enters the evaporative concentration spray layer 4, and enters the ozone spray oxidation reaction layer after being cooled and initially absorbed. 82. The second absorption spray layer 62, the hydrogen peroxide spray oxidation reaction layer 92 and the third absorption spray layer 63 perform desulfurization, denitrification, mercury removal, oxidation absorption reaction, and finally enter the rotary dust removal and mist eliminator 7 for dust removal and defogging. The top chimney flue gas outlet 15 is directly discharged;

b, from the ozone spray oxidation reaction layer 82, the first absorption spray layer 61, the second absorption spray layer 62 and the third absorption spray spray layer 63 of the absorption slurry through the liquid collector 5 into the slurry circulation tank 2;

c, the absorption slurry in the slurry circulation tank 2 is discharged into the first filter 23 through the slurry circulation tank discharge pump 22, filtered, and sent to the evaporation concentrated spray layer 4 by the evaporation concentration pump 41 for cyclic evaporation concentration;

d. The slurry overflowing from the overflow port 32 of the circulating settling tank 3 is filtered by the second filter 33 to form a filtered supernatant, and the filtered supernatant is sent to the evaporation concentrated spray layer via the evaporation concentration pump 41. 4 performing recycling crystallization;

e. discharging a solid-liquid mixture containing magnesium sulfate and magnesium nitrate crystals having a solid content of more than 30% by weight and containing a particle size of more than 0.1 mm from the circulation settling tank discharge port 31 at the bottom of the circulating settling tank 3, and feeding the solid-liquid mixture into the crystallization tank 10 Further, in the crystallization tank 10, a magnesium sulfate or a magnesium nitrate crystal having a crystal grain larger than 0.2 mm is further formed by cooling, and a crystallizing device is provided with a stirring device in the crystallization tank;

f, the solid-liquid mixture entering the crystallization tank 10 from the circulating settling tank 3 is separated in the crystallization tank 10, and the mother liquid is evaporated back to concentrate the spray layer 4 to further circulate and crystallize, and the crystal slurry having a solid content of more than 40% by weight is sent to the centrifuge 11 for separation and centrifugation. The mother liquor is evaporated back to concentrate the spray layer 4, and the magnesium sulfate and magnesium nitrate having a water content of less than 2% by weight are sent to the dryer 12 for further drying until the finished product is fed into the packaging machine 13.

The main process parameters are detailed in Table 1.

Table 1

Serial number	parameter	unit	Numerical value
1	Device inlet flue gas volume (condition)	m 3 /h	320000
2	Device inlet smoke temperature	°C	120～180
3	Average inlet sulfur dioxide concentration	Mg/m 3	1500
4	Average inlet nitrogen oxide concentration	Mg/m 3	450
5	Average inlet dust concentration	Mg/m 3	98

6	Average inlet mercury concentration	Gg/m 3	10
7	Sulphur to magnesium ratio	Mol/mol	1.02
8	O 3 molar ratio to NO X	O 3 /NO X	0.3
9	H 2 O 2 and NO X molar ratio	H 2 O 2 /NO X	0.5
10	Oxidation time	s	0.5
11	Average outlet sulfur dioxide concentration	Mg/m 3	17
12	Average export NOx concentration	Mg/m 3	43
13	Average outlet dust concentration	Mg/m 3	3
14	Average export mercury concentration	Gg/m 3	0.01
15	Export fog content	Mg/m 3	20
16	Highest desulfurization efficiency	%	98.9
17	Maximum denitration efficiency	%	90.4
18	Highest dust removal efficiency	%	96.9
19	Highest mercury removal efficiency	%	99.9
20	Magnesium sulfate, magnesium nitrate output	t/h	1.41

It can be seen from the implementation effects of the above embodiments that the desulfurization efficiency of the flue gas desulfurization, denitrification, dehydration, dedusting, dedusting and defogging integrated device and method of the invention can reach more than 98%, the denitration efficiency can reach over 90%, O ₃ and NO _{X .} value molar ratio of only 0.3, _X molar ratio of H ₂ O ₂ and NO only 0.5, saving nearly 50% of the amount of ozone to achieve the desulfurization, denitrification, comprehensive treatment of mercury removal, dust, defogging, byproducts generated It can offset a considerable part of the operating costs, can meet the environmental requirements of ultra-low emissions while reducing investment and operating costs.

The present invention is not limited to the above-described embodiments, and any variations, modifications, and alterations that may be conceived by those skilled in the art are intended to fall within the scope of the present invention without departing from the spirit of the invention.

Claims (10)

1. A flue gas integrated processing device, comprising:

   The flue gas treatment equipment is internally provided with:

   An ozone spray oxidation reaction layer and a hydrogen peroxide spray oxidation reaction layer for synergistic oxidation of low-cost nitrogen oxides and elemental mercury in the flue gas, and formation of high-priced nitrogen oxides and mercury oxide;

   Absorbing a spray zone for absorbing sulfur dioxide and nitrogen oxides in the flue gas by using a magnesium oxide method, and collecting mercury oxide in the flue gas to form an absorption slurry;

   a slurry circulation zone for receiving the absorption slurry from the absorption spray zone and delivering the absorption slurry to the absorption spray zone and the evaporation concentration device;

   Dust removal and defogging area for dust removal and defogging of flue gas;

   An evaporation concentration device for evaporating and concentrating the slurry delivered thereto to form a concentrated product;

   a circulating sedimentation device for receiving concentrated product from the evaporation concentration device and sedimenting the concentrated product to form a sedimentation product;

   An ozone supply device for supplying ozone to an ozone spray oxidation reaction layer; and

   a hydrogen peroxide supply device for supplying hydrogen peroxide to the hydrogen peroxide spray oxidation reaction layer;

   Wherein the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer are both disposed in the absorption spray zone; the dust removal and defogging zone is located above the absorption spray zone; the evaporation concentration device and the cycle Settling devices are all disposed inside the flue gas treatment device.
2. The apparatus according to claim 1, wherein said absorption shower zone comprises at least three absorption spray layers, and said at least three absorption spray layers are not adjacent to each other and are subjected to said ozone spray oxidation reaction The layer and the hydrogen peroxide spray oxidation reaction layer are spaced apart.
3. The apparatus according to claim 2, wherein said absorption spray zone comprises, in order from bottom to top, a first absorption spray layer, a second absorption spray layer and a third absorption spray. The ozone spray oxidation reaction layer is disposed between the first absorption spray layer and the second absorption spray layer; and the hydrogen peroxide spray oxidation reaction layer is disposed between the second absorption spray layer and the third absorption spray layer.
4. The apparatus according to claim 3, wherein the ozone spray oxidation reaction layer is 0.5 to 1.5 m from the first absorption shower layer; and the hydrogen peroxide spray oxidation reaction layer is 0.8 to 2 from the second absorption shower zone. 1.8m, and 1 to 2.2m from the third absorption spray layer.
5. The apparatus according to any one of claims 1 to 4, wherein the dust removal and defogging zone is 0.2 to 2.0 m from the absorption shower zone.
6. The device according to claim 5, wherein the dust removal and defogging area comprises a dust removal and defogging device, and the dust removal and defogging device is a rotary dust removal and mist eliminator.
7. The device of claim 1 wherein said device further comprises:

   a crystallization apparatus for crystallizing a sedimentation product from a circulating settling apparatus to form a mother liquor and a crystalline product;

   a centrifugation apparatus for centrifugally separating a crystalline product from a crystallization apparatus to form a mother liquor and a magnesium sulfate, magnesium nitrate product;

   A drying apparatus for drying the magnesium sulfate, magnesium nitrate product from the centrifuge equipment to the finished product.
8. A method for performing integrated flue gas treatment using the apparatus according to any one of claims 1-7, comprising the steps of:

   Flue gas oxidation step: in the ozone spray oxidation reaction layer and the hydrogen peroxide spray oxidation reaction layer, the ozone and hydrogen peroxide are used to synergistically oxidize the low-cost nitrogen oxides and elemental mercury in the flue gas, and form high-priced nitrogen oxides and oxidation. HG;

   Wet absorption step: in the absorption spray zone, the magnesium oxide method is used to absorb sulfur dioxide and nitrogen oxides in the flue gas, and the mercury oxide in the flue gas is collected to form an absorption slurry;

   a slurry circulation step: receiving an absorption slurry from the absorption spray zone in the slurry circulation zone, and conveying the absorption slurry to the absorption spray zone and the evaporation concentrated spray layer;

   Evaporation concentration step: evaporating and concentrating the slurry delivered thereto in an evaporation concentration device, and forming a concentrated product;

   a cycle sedimentation step: receiving a concentrated product from the evaporation concentration device in a circulating settling device, and sedimenting the concentrated product to form a sedimentation product;

   Ozone supply step: supplying ozone to the ozone spray oxidation reaction layer by the ozone supply device;

   Hydrogen peroxide supply step: supplying hydrogen peroxide to the hydrogen peroxide spray oxidation reaction layer by a hydrogen peroxide supply device;

   Dust removal and defogging step: Dedusting and defogging is performed on the flue gas in the dust removal and defogging area.
9. The method according to claim 8, wherein in the step of oxidizing the flue gas, the process conditions of the ozone spray oxidation reaction layer are: a flue gas temperature of 50 to 80 ° C and a dust content of 30 to 50 mg / Nm ³ The relative humidity is greater than 30%, the moisture content of the flue gas is 10% to 15%; the process conditions of the hydrogen peroxide spray oxidation reaction layer are: the flue gas temperature is 40-70 ° C, and the water content is 10% to 13%, relative The humidity is 30% to 40%.
10. The method of claim 8 further comprising:

    Crystallization step: crystallizing the sedimentation product from the cycle settling device in a crystallization apparatus to form a mother liquor and a crystalline product;

    Centrifugation step: centrifuging the crystallized product from the crystallization apparatus in a centrifugation apparatus to form a mother liquor and a magnesium sulfate, magnesium nitrate product;

    Drying step: The magnesium sulfate, magnesium nitrate product from the centrifuge equipment is dried to the finished product in a drying apparatus.

Images