CN116328531A - A method for separating HCl and Hg - Google Patents

Abstract

The invention belongs to the technical field of coal-fired flue gas treatment, and particularly relates to a method for separating HCl and Hg. The invention provides a method for separating HCl and Hg, which comprises the steps of placing carbonate into a heating device, heating the heating device, and then introducing a gas mixture of HCl and Hg. The method can rapidly remove HCl in the mixture of HCl and Hg, achieves the purpose of separation, improves the monitoring precision of Hg-CEMS, has simple operation, high efficiency and low cost, and is suitable for popularization and application in industrial production.

Description

A method for separating HCl and Hg

technical field

The invention belongs to the technical field of coal-fired flue gas treatment, and in particular relates to a method for separating HCl and Hg.

Background technique

The average mercury content in coal combustion in my country is 0.15-0.22 μg/g. Although the mercury content in coal is very low, due to the huge consumption, the total amount of mercury emitted into the atmosphere from coal combustion in the world reaches more than 3000 tons every year. Mercury is highly toxic, highly volatile, bioaccumulative, and environmentally persistent, causing serious harm to the ecological environment and human health. Accurate monitoring of mercury is the key to mastering the mercury emissions of coal-fired power plants, judging whether they exceed the standard, and developing mercury pollution control technologies. Therefore, it will be an inevitable trend for coal-fired power plants to implement effective and accurate mercury emission monitoring.

Contents of the invention

The present invention is based on the inventor's discovery and recognition of the following facts and problems:

On-line continuous monitoring of mercury is mainly to continuously monitor the mercury content in the flue gas through the gas phase mercury on-line continuous monitoring system (Hg-CEMS). At present, the analytical technology of mercury measuring instruments can only monitor Hg ⁰ , and the separation and conversion of mercury forms has become one of the cores of the development of Hg-CEMS technology, but the HCl in the flue gas will affect the efficiency of mercury form separation and conversion. Therefore, it is of great significance to propose a method for selectively separating HCl and Hg to improve the service life of selective adsorbents and reducing agents in the Hg-CEMS mercury speciation separation and conversion module, and to improve the monitoring accuracy of Hg-CEMS.

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. For this reason, the embodiments of the present invention propose a method for separating HCl and Hg, which can quickly remove HCl in the mixture of HCl and Hg, achieve the purpose of separation, and improve the monitoring accuracy of Hg-CEMS. The utility model has high efficiency and low cost, and is suitable for popularization and application in industrial production.

A method for separating HCl and Hg of the present invention comprises placing the carbonate in a heating device, and feeding the gas mixture of HCl and Hg after the heating device is heated.

The advantages and technical effects brought by the method for separating HCl and Hg in the embodiment of the present invention, 1. In the method of the embodiment of the present invention, the HCl in the mixture of HCl and Hg can be quickly adsorbed only by heating the carbonate to achieve The purpose of separation; 2, the method of the embodiment of the present invention, the removal efficiency of HCl is high, helps to improve the service life of selective adsorbent, reductant etc. in Hg-CEMS mercury form separation and transformation module, improves Hg-CEMS 3. The method of the embodiment of the present invention has simple operation, high efficiency and low cost, and is suitable for popularization and application in industrial production.

In some embodiments, the carbonate includes at least one of Na ₂ CO ₃ , K ₂ CO ₃ .

In some embodiments, the carbonate has a particle size of 10-100 mesh.

In some embodiments, the particle size of the carbonate is 40-60 mesh.

In some embodiments, the heating temperature is 200-500°C.

In some embodiments, the heating temperature is 350-450°C.

In some embodiments, the gaseous mixture of HCl and Hg is flue gas from a coal-fired power plant.

Description of drawings

Fig ^{. 1 is the curve diagram of Na CO adsorption Hg O} _{in embodiment} 1;

Fig. 2 is the column diagram of _Na2CO3 and gac adsorption Hg ²⁺ in embodiment 1 _;

Fig. 3 is Na in embodiment ₁ CO The graph that adsorbs _HCl ;

Fig. 4 is the graph of the influence of the content of HCl on Hg-CEMS mercury speciation separation and the selective adsorbent in conversion module;

Fig. 5 is the graph of K in embodiment _{2 CO} adsorption Hg ⁰ ;

Fig. 6 is the column diagram of K ₂ CO ₃ and active carbon adsorption Hg ²⁺ in embodiment 2;

FIG. 7 is a graph of adsorption of HCl by K ₂ CO ₃ in Example 2. FIG.

Detailed ways

Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

A method for separating HCl and Hg according to an embodiment of the present invention includes placing the carbonate in a heating device, heating the heating device and feeding a gas mixture of HCl and Hg.

The method for separating HCl and Hg in the embodiment of the present invention only needs to heat the carbonate to realize the fast adsorption of HCl in the mixture of HCl and Hg to achieve the purpose of separation; the removal efficiency of HCl is high, which is beneficial to increase the Hg - The service life of selective adsorbents and reducing agents in the CEMS mercury form separation and conversion module improves the monitoring accuracy of Hg-CEMS; the operation is simple, the efficiency is high, and the cost is low, which is suitable for popularization and application in industrial production.

In some embodiments, preferably, the carbonate includes at least one of Na ₂ CO ₃ and K ₂ CO ₃ . In the embodiment of the present invention, it is preferred that the type of carbonate can quickly react with HCl in HCl and Hg, and the removal efficiency is high; and the price of this type of carbonate is low, which can reduce the cost of separating HCl and Hg.

In some embodiments, preferably, the particle size of the carbonate is 10-100 mesh. Further preferably, the particle size of the carbonate is 40-60 mesh. In the embodiment of the present invention, the particle size of the carbonate is optimized, which can increase the contact area between the carbonate and the mixture and improve the separation efficiency.

In some embodiments, preferably, the heating temperature is 200-500°C. Further preferably, the heating temperature is 350-450°C. In the embodiment of the present invention, the heating temperature is preferred, which can make the carbonate and HCl react quickly. If the temperature is low, the reaction rate will be slow, and it cannot be guaranteed that the HCl in the mixture will be effectively removed. If the temperature is too high, it will cause carbon The reaction between carbonate and HCl cannot be carried out normally, that is, the HCl in the mixture cannot be removed; in addition, the carbonate will decompose into oxides, and the oxides will not only react with divalent mercury, which will reduce the detection accuracy, but also Corrosive and increases the risk of handling.

In some embodiments, preferably, the gas mixture is flue gas from a coal-fired power plant.

The technical solutions of the present invention will be described in detail below in conjunction with specific embodiments and accompanying drawings.

Example 1

(1) Place 100 mg of Na ₂ CO ₃ on a fixed bed adsorption test bench, wherein the particle size of Na ₂ CO ₃ is 40-60 mesh, and the inner diameter of the quartz tube reactor is 10 mm;

(2) After raising the temperature of the fixed-bed adsorption test bench to 350°C, feed the mixed gas of HCl and Hg with a total gas flow rate of 1 L/min for 1 hour; the concentration ^{of Hg} at the inlet is 70±2 μg/ m ³ , Hg ²⁺ concentration is about 120 μg/m ³ , and HCl concentration is 150 ppm.

The adsorption capacity of sodium carbonate to Hg ⁰ , Hg ²⁺ and HCl was detected, and the adsorption rate data of sodium carbonate to Hg ²⁺ was obtained with activated carbon as a reference. The results are shown in Figure 1, Figure 2 and Figure 3 respectively. 1, it can be seen that Na ₂ CO ₃ basically does not adsorb Hg ⁰ under the condition of 350°C (cutting the main path refers to passing the mixed gas into the main path with sodium carbonate after the flow of Hg ⁰ is stabilized) It can be seen from Figure 2 that the adsorption rate of Na ₂ CO ₃ to Hg ²⁺ is only about 3%; it can be seen from Figure 3 that the removal rate of Na ₂ CO ₃ to HCl is 100% within 60 minutes.

It can be calculated that after the adsorption and removal of sodium carbonate, the concentration of Hg ⁰ in the mixed gas at the outlet is basically unchanged, the concentration of Hg ²⁺ is 116.4μg/m ³ , only decreased by about 3%, and the concentration of HCl is 0. It can be seen that at 350°C, Na ₂ CO ₃ has a strong HCl adsorption capacity, but does not adsorb Hg ⁰ and Hg ²⁺ , and can selectively remove HCl in the gas mixture of HCl and Hg.

In order to verify the influence of the content of HCl in the flue gas on the selective adsorbent in the Hg-CEMS mercury speciation separation and conversion module, the following experiments were carried out:

The simulated flue gas component is high-purity N ₂ , the total gas flow rate is 1L/min, the mercury-loaded N ₂ flow rate is 200mL/min, the HCl concentration is set at 0, 20, 40 and 80ppm, and γ-Al ₂ O ₃ is used as The amount of carrier and selective adsorbent with calcium oxide as the active component is 100 mg, the particle size is 20-40 mesh, the reaction temperature is 150 ° C, and the continuous feeding is 60 min. The results are shown in Figure 4. It can be seen from the figure that The concentration of HCl has a great influence on the selective adsorbent. With the increase of HCl concentration, the adsorption rate of the adsorbent to HCl decreases, and the selective removal of HCl in the flue gas by the present invention can effectively improve the selectivity The service life of the adsorbent.

Example 2

The processing method of this embodiment is identical with embodiment 1, and difference is only: in step (1), the potassium carbonate of 100mg is used as adsorbent.

The adsorption capacity of potassium carbonate to Hg ⁰ , Hg ²⁺ and HCl was detected, and the adsorption rate data of potassium carbonate to Hg ²⁺ was obtained with activated carbon as a reference. The results are shown in Fig. 5, Fig. 6 and Fig. 7 respectively, from It can be seen from Figure 5 that K ₂ CO ₃ basically does not adsorb Hg ⁰ under the condition of 350°C; it can be seen from Figure 6 that the adsorption rate of K ₂ CO ₃ to Hg ²⁺ is only about 5%; from Figure 7 It can be seen that within 60 min, the removal rate of HCl by K ₂ CO ₃ is 100%.

It can be obtained by calculation that after adsorption and removal of potassium carbonate, the concentration of Hg ⁰ in the mixed gas at the outlet is basically unchanged, the concentration of Hg ²⁺ is 114 μg/m ³ , only decreased by about 5%, and the concentration of HCl is 0. It can be seen that at 350°C, K ₂ CO ₃ has strong HCl adsorption capacity, but does not adsorb Hg ⁰ and Hg ²⁺ , and can selectively remove HCl in the gas mixture of HCl and Hg.

As used herein, the terms "one embodiment," "some embodiments," "example," "specific examples," or "some examples" mean specific features, structures, materials, or features described in connection with the embodiment or example. A feature is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the above-mentioned embodiments have been shown and described, it can be understood that the above-mentioned embodiments are exemplary, and should not be construed as limitations on the present invention. Changes, modifications, substitutions and variations made by those skilled in the art to the above-mentioned embodiments All within the protection scope of the present invention.

Claims (7)

1. A method for separating HCl and Hg, characterized in that comprising placing the carbonate in a heating device, and feeding the gas mixture of HCl and Hg after the heating device is heated. 2. The method for separating HCl and Hg according to claim 1, characterized in that the carbonate comprises at least one of Na ₂ CO ₃ and K ₂ CO ₃ . 3. The method for separating HCl and Hg according to claim 1 or 2, characterized in that the particle size of the carbonate is 10-100 mesh. 4. The method for separating HCl and Hg according to claim 3, characterized in that the particle size of the carbonate is 40-60 mesh. 5. The method for separating HCl and Hg according to claim 1, characterized in that the heating temperature is 200-500°C. 6. The method for separating HCl and Hg according to claim 5, characterized in that the heating temperature is 350-450°C. 7. The method for separating HCl and Hg according to claim 1, characterized in that the gas mixture of HCl and Hg is flue gas from a coal-fired power plant.

Images