A novel limestone-gypsum wet flue gas desulfurization additive and its preparation method

Abstract

The present invention relates to the technical field of wet flue gas desulfurization, and discloses a novel limestone-gypsum wet flue gas desulfurization additive and a preparation method thereof. The desulfurization additive includes the following components according to mass fraction: 2 to 20 parts of citric acid, 2 to 28 parts of sodium citrate, 36 to 560 parts of acetic acid, 60 to 720 parts of sodium acetate, 1.5 to 5 parts of potassium hydrogen phthalate, 3 to 35 parts of sodium hydroxide, 30 to 50 parts of magnesium hydroxide, 50 to 85 parts of fatty alcohols, and 30 to 50 parts of manganese dioxide. The desulfurization catalyst is prepared by vacuum freeze drying technology. The desulfurization additive of the present invention does not use heavy metals, precious metals and precious raw materials, is environmentally friendly and reliable, and has low cost; the pH range is stable, the desulfurization synergistic effect is good, and the synergistic time is long.

Description

Technical Field

[0001] The invention belongs to the technical field of wet flue gas desulfurization, and in particular relates to a novel limestone-gypsum wet flue gas desulfurization additive and a preparation method thereof. Background Art

[0002] Among the many desulfurization methods, limestone-gypsum wet desulfurization is widely used due to its mature process technology, high desulfurization efficiency, rich absorbent sources, and usable by-products. In my country, more than 85% of coal-fired units use limestone-gypsum wet desulfurization technology. However, due to the instability of my country's coal market at this stage, many coal-fired power plants have been burning coal types that exceed the sulfur content for a long time, resulting in a high sulfur content in the flue gas of power plant boilers, causing the wet desulfurization system to generally have high operating and maintenance costs, substandard efficiency, low gypsum quality, and serious scaling and clogging of subsequent equipment in the absorption tower.

[0003] There are three main solutions to the above problems: one is to control the sulfur content of coal; the second is to increase the capacity of desulfurization equipment; the third is to use desulfurization additives. Among them, controlling the sulfur content of coal will greatly increase fuel costs; the capacity increase and transformation of desulfurization equipment has a long cycle and high economic cost, and has poor adaptability to the sulfur content of coal. Therefore, the research and development of desulfurization additives has become an important way to solve the above problems and is becoming a research hotspot in the field of environmental protection.

[0004] The idea of ​​desulfurization additives on the market is basically to increase CaCO 3 solubility, enabling it to react with more SO 2 reaction, thereby improving the desulfurization efficiency and reducing SO 2 Based on this idea, all of these products are highly acidic (pH value between 1.0 and 3.0), and they have certain effects in temporary emergency situations, but they are seriously harmful in long-term use: the efficiency increase time is short, the efficiency is low, and it cannot meet the long-term environmental protection requirements of power plants; they are corrosive to local equipment in the desulfurization system and also cause slurry "poisoning"; during use, the slurry is prone to foaming, resulting in false liquid levels, etc., which affect the desulfurization performance or safe operation; some products have a strong odor, causing personal injury and polluting the environment.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to solve one of the above problems and provide a novel limestone-gypsum wet flue gas desulfurization additive and a preparation method thereof. The desulfurization additive has high desulfurization efficiency and safe operation when used together with limestone.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A novel limestone-gypsum wet flue gas desulfurization additive comprises the following components in parts by mass: 2-20 parts of citric acid, 2-28 parts of sodium citrate, 36-560 parts of acetic acid, 60-720 parts of sodium acetate, 1.5-5 parts of potassium hydrogen phthalate, 3-35 parts of sodium hydroxide, 30-50 parts of magnesium hydroxide, 50-85 parts of fatty alcohol, and 30-50 parts of manganese dioxide.

[0009] Furthermore, the desulfurization additive includes the following components in parts by mass: 5-15 parts of citric acid, 5-20 parts of sodium citrate, 150-450 parts of acetic acid, 200-600 parts of sodium acetate, 2-4 parts of potassium hydrogen phthalate, 10-30 parts of sodium hydroxide, 35-45 parts of magnesium hydroxide, 60-80 parts of fatty alcohol, and 35-45 parts of manganese dioxide.

[0010] Furthermore, the desulfurization additive includes the following components in parts by mass: 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, and 40 parts of manganese dioxide.

[0011] Preferably, the desulfurization additive further comprises 10 to 15 parts by weight of aliphatic amide.

[0012] Furthermore, the mass ratio of citric acid, sodium citrate, acetic acid, sodium acetate, potassium hydrogen phthalate, sodium hydroxide and magnesium hydroxide in the desulfurization additive is 1:1.5:30:40:0.3:2:4.

[0013] Preferably, the desulfurization additive further comprises 10 to 15 parts by mass of aliphatic amide.

[0014] A method for preparing a novel limestone-gypsum wet flue gas desulfurization additive comprises the following steps:

[0015] (1) Weighing citric acid, sodium citrate, acetic acid, sodium acetate, potassium hydrogen phthalate, sodium hydroxide, magnesium hydroxide, fatty alcohol, and manganese dioxide according to mass fractions, adding water and stirring uniformly to prepare a composite solution I;

[0016] (2) pre-freezing the composite solution I to obtain a mixture II;

[0017] (3) The mixture II is placed in a vacuum freeze dryer for freeze drying to obtain a desulfurization additive.

[0018] Furthermore, the process of adding water and stirring is carried out on a heating device, and the heating temperature is 40-50°C.

[0019] Furthermore, in step (3), the vacuum degree in the vacuum freeze dryer is 20-30 Pa, and the freeze-drying time is greater than 24 hours.

[0020] Preferably, a method for preparing a novel limestone-gypsum wet flue gas desulfurization additive comprises the following steps:

[0021] (1) Weigh citric acid, sodium citrate, acetic acid, sodium acetate, potassium hydrogen phthalate, sodium hydroxide, magnesium hydroxide, fatty alcohol, manganese dioxide, and fatty amide according to mass fractions, add water and stir to obtain a composite solution;

[0022] (2) pre-freezing the composite solution I to obtain a mixture;

[0023] (3) placing the mixture in a vacuum freeze dryer for freeze drying to obtain a desulfurization additive.

[0024] Compared with the prior art, the present invention has the following main advantages:

[0025] 1. Compared with the existing desulfurization additives, the desulfurization additive of the present invention does not use heavy metals, precious metals and precious raw materials, is environmentally friendly and reliable, and has low cost.

[0026] 2. The limestone-gypsum wet flue gas desulfurization additive provided by the present invention includes three buffer systems: citric acid-sodium citrate, acetic acid-sodium acetate, and potassium hydrogen phthalate-sodium hydroxide. The pH gradient of the three buffer systems is coordinated, especially the presence of the potassium hydrogen phthalate-sodium hydroxide buffer system, which will increase the pH value of the system to above 3.5. It has low corrosiveness to the desulfurization system equipment and is not easy to be poisoned when added to the desulfurization slurry.

[0027] 3. The citric acid-sodium citrate system serves as a bridge between the other two buffer systems, making the overall buffer system of the additive stable, with a stable pH range, and can effectively dissolve calcium carbonate and SO 2 At the same time, combined with the timely oxidation of magnesium hydroxide and manganese dioxide, the dissolved sulfur is oxidized in time, the pH of the system does not drop and fluctuate significantly, and the slurry can be continuously and efficiently desulfurized. That is, the additive has a good synergistic effect and a long synergistic time. 4. The desulfurization additive of the present invention has a simple formula, high desulfurization efficiency, and the raw materials are cheap and easy to obtain. In addition, the addition of fatty alcohols and fatty amides can avoid the phenomenon of false liquid level caused by slurry foaming during actual operation, thereby ensuring the safe operation of the desulfurization process.

[0028] 5. The desulfurization additive of the present invention is prepared by vacuum freeze-drying technology. The moisture of the material is directly sublimated at low temperature and low pressure, and the air is basically isolated. The material with reduced water content does not have the problem of surface hardening, and the mixing degree of the raw materials is improved.

[0029] 6. When the desulfurization additive of the present invention is used, the usage amount is low, the application cost is low, the desulfurization rate is basically greater than 95%, the initial 0.5h desulfurization rate is greater than 90%, and the continuous 10h desulfurization rate is greater than 90%, providing a new energy-saving and emission-reduction option for coal-fired enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the continuous desulfurization effect of the desulfurization additives of Examples 5 and 6 of the present invention and Comparative Examples 1-4 and the reference example. DETAILED DESCRIPTION

[0031] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. The present invention uses the methods and materials described herein; however, other suitable methods and materials known in the art may also be used. The materials, methods, and examples described herein are illustrative only and are not intended to be limiting. All publications, patent applications, patents, provisional applications, database entries, and other references mentioned herein are incorporated herein by reference in their entirety. In the event of a conflict, the present specification, including definitions, shall prevail.

[0032] As used herein, the term "includes" is equivalent to "comprising". As used herein, the terms "includes", "comprising", "having", "having", "containing" or any other variation thereof are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus comprising a list of elements is not necessarily limited to those elements but may also include other elements not expressly listed or inherent to the composition, process, method, article, or apparatus.

[0033] The term "comprising / including" is intended to include embodiments encompassed by the terms "consisting essentially of" and "consisting of." Similarly, the term "consisting essentially of" is intended to include embodiments encompassed by the term "consisting of."

[0034] When quantity, concentration or other numerical value or parameter is given with range, preferred range or a series of upper preferred value and lower preferred value, it should be understood that it specifically discloses all ranges formed by any pair of numerical values ​​of any larger range limit or preferred value and any smaller range limit or preferred value, regardless of whether the range is disclosed respectively. For example, when describing the range of "1 to 5", the described range should be understood to include the range of "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. Unless otherwise stated, where numerical range is described herein, the range is intended to include the range end value and all integers and fractions within the range.

[0035] When the terms "below" or "above" are used to describe a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

[0036] In addition, unless expressly stated to the contrary, "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following conditions applies to condition A "or" B: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0037] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention are intended to indicate that the number of occurrences (i.e., occurrences) of the elements or components is not limited. Therefore, "a" or "an" should be understood to include one or at least one, unless it is clearly indicated that the number is singular, otherwise the elements or components in the singular form also include the plural case.

[0038] Unless specifically stated, the materials, methods, and examples described herein are illustrative only and not limiting. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are still described herein.

[0039] The present invention is described in detail below.

[0040] A limestone-gypsum wet flue gas desulfurization catalyst comprises, by weight: 2-20 parts of citric acid, 2-28 parts of sodium citrate, 36-560 parts of acetic acid, 60-720 parts of sodium acetate, 1.5-5 parts of potassium hydrogen phthalate, 3-35 parts of sodium hydroxide, 30-50 parts of magnesium hydroxide, 50-85 parts of fatty alcohol, 30-50 parts of manganese dioxide, and 10-15 parts of aliphatic amide. When the weight of each component is lower than or higher than the above proportion, its synergistic performance is not good; only within the above proportion range, the desulfurization synergistic effect of the desulfurization additive is good and the synergistic time is long. The main buffer system proportion is acetic acid-sodium acetate, and the proportion of citric acid-sodium citrate system and potassium hydrogen phthalate-sodium hydroxide system is small, so that the additive cost is low and easy to obtain.

[0041] The flue gas here is coal-fired flue gas, or other flue gas that needs to be desulfurized. 2 The flue gas can be removed as long as the desulfurizer is not poisoned.

[0042] The fatty alcohol used in the present invention is preferably a fatty alcohol having a carbon number of 22 or less, and more preferably a fatty alcohol having a carbon number of 7 to 9. Low-carbon alcohols have better compatibility with slurry and are more suitable for defoaming in limestone-gypsum desulfurization systems.

[0043] The aliphatic amide used in the present invention is preferably an aliphatic amide having a carbon number of less than 12. Low-carbon amides are more soluble in low-carbon alcohols and can assist low-carbon alcohols in further suppressing and eliminating foam.

[0044] A preparation method of a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze drying technology. Because of the presence of potassium hydrogen phthalate-sodium hydroxide system, the water system will generate some heat by itself, so the external heat required for adding water and stirring evenly can be reduced, and the water bath can be heated at a temperature below 50°C. Freeze drying can prevent the additive particles from growing and affecting the synergistic effect. A vacuum of 20 to 30 Pa ensures that the additive is not oxidized.

[0045] The vacuum freeze dryer is a freeze dryer produced by Beijing Sihuan Scientific Instrument Factory Co., Ltd., model LGJ-10C.

[0046] Example 1

[0047] (1) Weigh 2 parts of citric acid, 2 parts of sodium citrate, 36 parts of acetic acid, 60 parts of sodium acetate, 1.5 parts of potassium hydrogen phthalate, 3 parts of sodium hydroxide, 30 parts of magnesium hydroxide, 50 parts of fatty alcohol, and 30 parts of manganese dioxide according to mass, add water, and heat and stir in a 40° C. water bath to prepare a composite solution I;

[0048] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0049] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 30Pa. After maintaining it for 24 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0050] Example 2

[0051] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0052] (1) Weigh 20 parts of citric acid, 28 parts of sodium citrate, 560 parts of acetic acid, 720 parts of sodium acetate, 5 parts of potassium hydrogen phthalate, 35 parts of sodium hydroxide, 50 parts of magnesium hydroxide, 85 parts of fatty alcohol, and 50 parts of manganese dioxide according to mass, add water, and heat and stir in a 40° C. water bath to prepare a composite solution I;

[0053] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0054] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 28 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0055] Example 3

[0056] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0057] (1) Weigh 5 parts of citric acid, 5 parts of sodium citrate, 150 parts of acetic acid, 200 parts of sodium acetate, 2 parts of potassium hydrogen phthalate, 10 parts of sodium hydroxide, 35 parts of magnesium hydroxide, 60 parts of fatty alcohol, and 35 parts of manganese dioxide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0058] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0059] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 24 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0060] Example 4

[0061] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0062] (1) Weigh 15 parts of citric acid, 20 parts of sodium citrate, 450 parts of acetic acid, 600 parts of sodium acetate, 4 parts of potassium hydrogen phthalate, 30 parts of sodium hydroxide, 45 parts of magnesium hydroxide, 80 parts of fatty alcohol, and 45 parts of manganese dioxide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0063] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0064] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 28 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0065] Example 5

[0066] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0067] (1) Weigh 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, and 40 parts of manganese dioxide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0068] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0069] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0070] Example 6

[0071] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0072] (1) Weigh 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, 40 parts of manganese dioxide, and 10 parts of fatty amide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0073] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0074] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0075] Example 7

[0076] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0077] (1) Weigh 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, 40 parts of manganese dioxide, and 15 parts of fatty amide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0078] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0079] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0080] Comparative Example 1

[0081] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0082] (1) Weigh 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, 40 parts of manganese dioxide, and 10 parts of fatty amide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0083] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0084] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0085] Comparative Example 2

[0086] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0087] (1) Weigh 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, 40 parts of manganese dioxide, and 10 parts of fatty amide according to mass, add water, and heat and stir in a 40° C. water bath to obtain a composite solution I;

[0088] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0089] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0090] Comparative Example 3

[0091] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0092] (1) Weigh 10 parts of citric acid, 15 parts of sodium citrate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of manganese dioxide, 70 parts of fatty alcohol, and 10 parts of fatty amide according to mass, add water, and heat and stir in a 40° C. water bath to prepare a composite solution I;

[0093] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0094] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0095] Comparative Example 4

[0096] A method for preparing a limestone-gypsum wet flue gas desulfurization catalyst adopts vacuum freeze-drying technology.

[0097] (1) Weigh 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 70 parts of fatty alcohol, and 10 parts of fatty amide according to mass, add water, and heat and stir in a 40° C. water bath to prepare a composite solution I;

[0098] (2) pre-freezing the composite solution I in a -20°C freezer for 4 h to obtain a mixture II;

[0099] (3) Seal the mouth of the beaker bottle of mixture II with a sealing film, poke a few holes in the sealing film at the mouth of the bottle, and then place it on the tray rack of the vacuum freeze dryer. After fixing it, cover it with a plexiglass cover, turn on the compressor and wait until the temperature reaches -40°C, turn on the vacuum pump and vacuum machine, and the vacuum degree reaches 20Pa. After maintaining it for 26 hours, first release the air, then turn off the vacuum system and the compressor, take out the sample, and obtain a desulfurization additive with a water content of less than 0.1%.

[0100] After the desulfurization additives in Examples 1-7 and Comparative Examples 1-4 were compounded into finished products, they were added into a desulfurization absorption tower (containing limestone slurry). After the desulfurization system was running for 0.5 h, the concentration of sulfur dioxide at the smoke outlet was counted and compared with the desulfurization rate when the additives described in the above embodiments were not added (control group). The statistical results are shown in Table 1.

[0101] Table 1

[0102]

[0103] According to the desulfurization rate data of the embodiments, comparative examples and control groups in Table 1, the desulfurization rate is greater than 94% when the components of the desulfurization additive are in the range of 2-20 parts of citric acid, 2-28 parts of sodium citrate, 36-560 parts of acetic acid, 60-720 parts of sodium acetate, 1.5-5 parts of potassium hydrogen phthalate, 3-35 parts of sodium hydroxide, 30-50 parts of magnesium hydroxide, 50-85 parts of fatty alcohol and 30-50 parts of manganese dioxide according to the mass fraction, which significantly improves the desulfurization rate compared with the control group. Sulfur rate; further optimize the content of each component of the desulfurization additive. When the mass fraction of each component is within the range of 5-15 parts of citric acid, 5-20 parts of sodium citrate, 150-450 parts of acetic acid, 200-600 parts of sodium acetate, 2-4 parts of potassium hydrogen phthalate, 10-30 parts of sodium hydroxide, 35-45 parts of magnesium hydroxide, 60-80 parts of fatty alcohol, and 35-45 parts of manganese dioxide, the desulfurization rate is greater than 95%; the desulfurization rate is significantly reduced if any of the buffer systems is missing. The desulfurization rate is not particularly high if there is only a multi-buffer system but no manganese dioxide oxidant.

[0104] The continuous desulfurization effects of the desulfurization additives of Examples 5 and 6, Comparative Examples 1-4 and the control group were statistically analyzed. The statistical results are as follows: Figure 1 As shown. Figure 1 It can be seen from Examples 5 and 6 and the comparative examples and control groups that the addition of the desulfurization synergist in the technical solution of the present invention can achieve more than 95% of the desulfurization effect when the limestone-gypsum wet desulfurization process is carried out for 0.5 hours, and its high desulfurization effect can be continuously sustained for more than 10 hours, with a long action time and a small amount, which reduces production energy consumption and saves costs to a certain extent. The addition of aliphatic amides can improve the synergistic effect of the desulfurization additive and can maintain a long-term synergistic desulfurization effect. The combination of the three buffer systems makes the additive synergistic time long, and the desulfurization effect will be discounted if any one system is missing. However, there are three buffer systems, but without the support of manganese dioxide, the synergistic effect of the desulfurization additive decreases rapidly in the later stage. Since the control group has no buffer system to maintain the pH value of the limestone slurry, the slurry desulfurization effect quickly begins to fail, and the desulfurization effect is not good.

[0105] The above description is intended to be illustrative rather than restrictive, and those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure. Moreover, the above examples (or one or more of them) may be used in combination with each other, and it is contemplated that these embodiments may be combined with each other in various combinations or permutations.

Claims

1. A novel limestone-gypsum wet flue gas desulfurization additive, characterized in that: The desulfurization additive comprises the following components in terms of mass fraction: 2-20 parts of citric acid, 2-28 parts of sodium citrate, 36-560 parts of acetic acid, 60-720 parts of sodium acetate, 1.5-5 parts of potassium hydrogen phthalate, 3-35 parts of sodium hydroxide, 30-50 parts of magnesium hydroxide, 50-85 parts of fatty alcohol, and 30-50 parts of manganese dioxide.

2. A novel limestone-gypsum wet flue gas desulfurization additive according to claim 1, characterized in that: The desulfurization additive comprises the following components in terms of mass fraction: 5-15 parts of citric acid, 5-20 parts of sodium citrate, 150-450 parts of acetic acid, 200-600 parts of sodium acetate, 2-4 parts of potassium hydrogen phthalate, 10-30 parts of sodium hydroxide, 35-45 parts of magnesium hydroxide, 60-80 parts of fatty alcohol, and 35-45 parts of manganese dioxide.

3. The novel limestone-gypsum wet flue gas desulfurization additive according to claim 1, characterized in that: The desulfurization additive includes the following components in terms of mass fraction: 10 parts of citric acid, 15 parts of sodium citrate, 300 parts of acetic acid, 400 parts of sodium acetate, 3 parts of potassium hydrogen phthalate, 20 parts of sodium hydroxide, 40 parts of magnesium hydroxide, 70 parts of fatty alcohol, and 40 parts of manganese dioxide.

4. A novel limestone-gypsum wet flue gas desulfurization additive according to claim 1 or 2, characterized in that: The mass ratio of citric acid, sodium citrate, acetic acid, sodium acetate, potassium hydrogen phthalate, sodium hydroxide and magnesium hydroxide in the desulfurization additive is 1:1.5:30:40:0.3:2:

4.

5. A novel limestone-gypsum wet flue gas desulfurization additive according to any one of claims 1, 2 and 3, characterized in that: The desulfurization additive also includes 10 to 15 parts by mass of aliphatic amide.

6. A novel limestone-gypsum wet flue gas desulfurization additive according to claim 4, characterized in that: The desulfurization additive also includes 10 to 15 parts by mass of aliphatic amide.

7. A method for preparing a novel limestone-gypsum wet flue gas desulfurization additive as claimed in any one of claims 1, 2 and 3, characterized in that: The steps include: (1) Weigh citric acid, sodium citrate, acetic acid, sodium acetate, potassium hydrogen phthalate, sodium hydroxide, magnesium hydroxide, fatty alcohol, and manganese dioxide according to their mass fractions, add water and stir evenly to prepare composite solution I; (2) pre-freezing the composite solution I to obtain a mixture II; (3) The mixture II is placed in a vacuum freeze dryer for freeze drying to obtain a desulfurization additive.

8. The method for preparing a novel limestone-gypsum wet flue gas desulfurization additive according to claim 7, characterized in that: The process of adding water and stirring is carried out on a heating device, and the heating temperature is 40~50℃.

9. The method for preparing a novel limestone-gypsum wet flue gas desulfurization additive according to claim 7, characterized in that: In step (3), the vacuum degree in the vacuum freeze dryer is 20-30 Pa, and the freeze-drying time is greater than 24 hours.

10. The method for preparing a novel limestone-gypsum wet flue gas desulfurization additive according to claim 5, characterized in that: The steps include: (1) Weigh citric acid, sodium citrate, acetic acid, sodium acetate, potassium hydrogen phthalate, sodium hydroxide, magnesium hydroxide, fatty alcohol, manganese dioxide, and fatty amide according to their mass fractions, add water and stir evenly to prepare a composite solution; (2) pre-freezing the composite solution I to obtain a mixture; (3) The mixture is placed in a vacuum freeze dryer for freeze drying to obtain a desulfurization additive.

Images