CN116328531A - 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

Method for separating HCl and Hg

Technical Field

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

Background

The average mercury content in the coal in China is 0.15-0.22 mug/g, and the total mercury amount discharged from the coal to the atmosphere in each year in the world reaches more than 3000t due to huge consumption despite the low mercury content in the coal. Mercury has strong toxicity, strong volatility, bioaccumulation and environmental durability, and causes serious harm to ecological environment and human health. The accurate monitoring of mercury is the key to grasping the mercury emission of coal-fired power plants, judging whether the mercury emission exceeds the standard and developing mercury pollution control technology. Thus, it would be a necessary trend for each coal-fired power plant to conduct effective, accurate mercury emission monitoring.

Disclosure of Invention

The present invention has been made based on the findings and knowledge of the inventors regarding the following facts and problems:

the mercury online continuous monitoring is mainly to continuously monitor the mercury content in the flue gas through a gas-phase mercury online continuous monitoring system (Hg-CEMS). The current mercury porosimeter analysis technology can only be used for Hg ⁰ Monitoring, mercury morphological separation and conversion become one of the cores of Hg-CEMS technology development, but HCl in flue gas can affect the efficiency of mercury morphological separation and conversion. Therefore, the method for selectively separating HCl and Hg is significant in improving the service life of selective adsorbents, reducing agents and the like in Hg-CEMS mercury form separation and conversion modules and improving the monitoring precision of Hg-CEMS.

The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the embodiment of the invention provides a method for separating HCl and Hg, which can rapidly remove HCl in a 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.

The method for separating HCl and Hg comprises the steps of placing carbonate in a heating device, heating the heating device, and then introducing a gas mixture of HCl and Hg.

The method for separating HCl and Hg provided by the embodiment of the invention has the advantages and technical effects that 1, the method provided by the embodiment of the invention can realize rapid absorption of HCl in the mixture of HCl and Hg by heating carbonate, so as to achieve the purpose of separation; 2. the method provided by the embodiment of the invention has high removal efficiency on HCl, is beneficial to prolonging the service lives of the selective adsorbent, the reducing agent and the like in the Hg-CEMS mercury form separation and conversion module, and improves the monitoring precision of Hg-CEMS; 3. the method provided by the embodiment of the invention has the advantages of simplicity in operation, high efficiency and low cost, and is suitable for popularization and application in industrial production.

In some embodiments, the carbonate salt comprises Na ₂ CO ₃ 、K ₂ CO ₃ At least one of them.

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

In some embodiments, the carbonate has a particle size of 40 to 60 mesh.

In some embodiments, the temperature of the heating is 200 to 500 ℃.

In some embodiments, the temperature of the heating is 350 to 450 ℃.

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

Drawings

FIG. 1 is Na in example 1 ₂ CO ₃ Adsorption of Hg ⁰ Is a graph of (2);

FIG. 2 is Na in example 1 ₂ CO ₃ And activated carbon adsorption of Hg ²⁺ Is a histogram of (a);

FIG. 3 is Na in example 1 ₂ CO ₃ A graph of HCl adsorption;

FIG. 4 is a graph of the effect of HCl content on selective adsorbents in a Hg-CEMS mercury morphology separation and conversion module;

FIG. 5 is K in example 2 ₂ CO ₃ Adsorption of Hg ⁰ Is a graph of (2);

FIG. 6 is K in example 2 ₂ CO ₃ And activated carbon adsorption of Hg ²⁺ Is a histogram of (a);

FIG. 7 is K in example 2 ₂ CO ₃ Graph of adsorbed HCl.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

The method for separating HCl and Hg comprises the steps of placing carbonate into a heating device, heating the heating device, and then introducing a gas mixture of HCl and Hg.

According to the method for separating HCl and Hg, disclosed by the embodiment of the invention, the rapid adsorption of HCl in the mixture of HCl and Hg can be realized by heating carbonate, so that the purpose of separation is achieved; the removal efficiency of HCl is high, the service lives of selective adsorbents, reducing agents and the like in the Hg-CEMS mercury form separation and conversion module are prolonged, and the monitoring precision of Hg-CEMS is improved; simple operation, high efficiency and low cost, and is suitable for popularization and application in industrial production.

In some embodiments, preferably, the carbonate salt comprises Na ₂ CO ₃ 、K ₂ CO ₃ At least one of them. In the embodiment of the invention, the type of carbonate is optimized to be capable of rapidly reacting with HCl in HCl and Hg, and the removal efficiency is high; and the carbonate has low price, and can reduce the cost of separating HCl and Hg.

In some embodiments, preferably, the carbonate has a particle size of 10 to 100 mesh. Further preferably, the carbonate has a particle size of 40 to 60 mesh. In the embodiment of the invention, the granularity of the carbonate is optimized, so that the contact area of the carbonate and the mixture can be increased, and the separation efficiency can be improved.

In some embodiments, preferably, the temperature of the heating is 200-500 ℃. Further preferably, the heating temperature is 350 to 450 ℃. In the embodiment of the invention, the heating temperature is optimized, so that carbonate and HCl can be rapidly reacted, if the temperature is lower, the reaction rate is slow, the effective removal of HCl in the mixture cannot be ensured, if the temperature is too high, the decomposition of carbonate can be caused, and the reaction of carbonate and HCl cannot be normally carried out, namely the HCl in the mixture cannot be removed; in addition, carbonate can decompose into oxides, which not only react with bivalent mercury, reducing detection accuracy, but also are corrosive, increasing the risk of handling.

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

The technical scheme of the present invention is described in detail below with reference to specific embodiments and drawings.

Example 1

(1) 100mg of Na ₂ CO ₃ Placed on a fixed bed adsorption experiment table, wherein Na ₂ CO ₃ The granularity of the catalyst is 40-60 meshes, and the inner diameter of the quartz tube reactor is 10mm;

(2) After the temperature of the fixed bed adsorption experiment table is increased to 350 ℃, introducing mixed gas of HCl and Hg, wherein the total gas flow is 1L/min, and continuously introducing for 1h; wherein the inlet Hg ⁰ The concentration is 70+/-2 mug/m ³ 、Hg ²⁺ The concentration is about 120. Mu.g/m ³ The HCl concentration was 150ppm.

Detection of sodium carbonate versus Hg ⁰ 、Hg ²⁺ And adsorption capacity of HCl, wherein sodium carbonate to Hg is obtained by using activated carbon as reference ²⁺ As shown in fig. 1, 2 and 3, respectively, it can be seen from fig. 1 that Na is present at 350 °c ₂ CO ₃ Substantially no Hg adsorption ⁰ (wherein the primary cut is when Hg ⁰ After the flow of the mixture is stable, the mixture is introduced into a main path containing sodium carbonate); as can be seen from fig. 2, na ₂ CO ₃ For Hg ²⁺ The adsorption rate is only about 3%; as can be seen from FIG. 3, na is present within 60 minutes ₂ CO ₃ The removal rate of HCl is 100%.

Calculated, and Hg in the mixed gas at the outlet is removed after sodium carbonate adsorption ⁰ Is basically unchanged in concentration of Hg ²⁺ Is 116.4. Mu.g/m ³ Only about 3% decrease and the HCl concentration is 0. From this, na at 350 ℃ ₂ CO ₃ Has strong HCl adsorption capacity without adsorbing Hg ⁰ And Hg of ²⁺ HCl in the HCl and Hg gas mixture can be selectively removed.

In order to verify the effect of HCl content in flue gas on selective adsorbents in Hg-CEMS mercury morphology separation and conversion modules, the following experiments were performed:

the simulated smoke component is high-purity N ₂ The total flow of the gas is 1L/min, wherein the mercury-carrying N ₂ The flow rate was 200mL/min, the HCl concentrations were set to 0, 20, 40 and 80ppm as gamma-Al ₂ O ₃ The usage amount of the selective adsorbent taking the carrier and the calcium oxide as active components is 100mg, the particle size is 20-40 meshes, the reaction temperature is 150 ℃, and the continuous feeding is carried out for 60 minutes, as shown in the result of fig. 4, the effect of the concentration of HCl on the selective adsorbent is larger, the adsorption rate of the adsorbent on the HCl is reduced along with the increase of the concentration of the HCl, and the service life of the selective adsorbent can be effectively prolonged by selectively removing the HCl in the flue gas.

Example 2

The processing method of this example is the same as that of example 1, except that: in step (1), 100mg of potassium carbonate was used as an adsorbent.

Detection of Potassium carbonate versus Hg ⁰ 、Hg ²⁺ And adsorption capacity of HCl, wherein the adsorption capacity of Hg by potassium carbonate is obtained by using activated carbon as reference ²⁺ As shown in fig. 5, 6 and 7, respectively, it can be seen from fig. 5 that K is lower than 350 ℃ ₂ CO ₃ Substantially no Hg adsorption ⁰ The method comprises the steps of carrying out a first treatment on the surface of the As can be seen from fig. 6, K ₂ CO ₃ For Hg ²⁺ The adsorption rate is only about 5%; as can be seen from FIG. 7, K is within 60 minutes ₂ CO ₃ The removal rate of HCl is 100%.

Calculated, and Hg in the mixed gas at the outlet is removed after potassium carbonate adsorption ⁰ Is basically unchanged in concentration of Hg ²⁺ Is 114. Mu.g/m ³ Only about 5% decrease, the HCl concentration was 0. From this, it was found that K at 350 ℃ ₂ CO ₃ Has strong HCl adsorption capacity without adsorbing Hg ⁰ And Hg of ²⁺ HCl in the HCl and Hg gas mixture can be selectively removed.

For purposes of this disclosure, the terms "one embodiment," "some embodiments," "example," "a particular example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While the above embodiments have been shown and described, it should be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the invention.

Claims (7)

1. A method of separating HCl and Hg comprising placing carbonate in a heating device, heating the heating device and introducing a gaseous mixture of HCl and Hg.

2. The method of separating HCl and Hg according to claim 1, wherein the carbonate includes Na ₂ CO ₃ 、K ₂ CO ₃ At least one of them.

3. The method of separating HCl and Hg according to claim 1 or 2, wherein the carbonate has a particle size of 10-100 mesh.

4. A method of separating HCl and Hg according to claim 3, wherein the carbonate has a particle size of 40-60 mesh.

5. The method of separating HCl and Hg according to claim 1, wherein the heating is at a temperature of 200-500 ℃.

6. The method of separating HCl and Hg according to claim 5, wherein the heating is at a temperature of 350-450 ℃.

7. The method of separating HCl and Hg according to claim 1, wherein the gas mixture of HCl and Hg is flue gas of a coal-fired power plant.

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