A method for vulcanizing a mercury removal agent

Abstract

The application provides a sulfuration method of a mercury removal agent, comprising the following steps: dry immersion sulfuration of a mercury removal agent precursor by using an ammonium sulfide solution; drying treatment of the sample after the dry immersion sulfuration by using hydrogen sulfide gas; dry sulfuration of the sample during the drying process, so as to obtain the sulfuration mercury removal agent. The sulfuration method is a rapid sulfuration method, the ammonium sulfide solution is used as a sulfuration agent for wet sulfuration, then the hydrogen sulfide gas is used for continuous sulfuration during the drying process until the sulfuration is completed, and the sulfuration method has the advantages of short sulfuration time and high efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of natural gas purification, in particular to a sulfidation method of a mercury removal agent. BACKGROUND

[0002] Natural gas is a new clean energy with a huge demand market. There is mercury in almost all natural gas fields, which mainly exists in the form of mercury. Mercury has strong migration, corrosion and biological toxicity, which can corrode processing equipment, poison catalysts, harm human health and pollute the environment in the process of natural gas development and transportation. The most effective protection measure is to remove mercury from natural gas at the source.

[0003] Currently, metal sulfide mercury removal agents generally use copper as the active metal and alumina as the carrier, and need to be sulfided to have mercury removal activity. For example, patent CN104475009A discloses a method for preparing a mercury removal agent, which uses a sulfur-containing gas to sulfide the mercury removal agent precursor to obtain the mercury removal agent. When using a sulfur-containing gas such as hydrogen sulfide for sulfidation, since the sulfidation reaction is a strong exothermic reaction, in order to prevent the mercury removal agent and equipment from burning, the sulfur content in the gas cannot be too high, and the sulfur content needs to be controlled at about 1%, which leads to a long sulfidation time, usually more than 50 hours. Wet sulfidation using ammonium sulfide solution is generally required to be excessive in order to be completely sulfided, but the concentration of ammonium sulfide solution needs to be about 8-10%. If the copper content of the mercury removal agent precursor is high, the amount of ammonium sulfide solution used during sulfidation needs to be greater than that used during dry immersion. Since ammonia is generated during the sulfidation process, if the solution is excessive, the generated ammonia is easy to form copper-ammonia complex with the copper ions loaded on the mercury removal agent and dissolve in the excessive liquid, resulting in the loss of copper ions. In order to overcome the above-mentioned sulfidation problems of the mercury removal agent, a new sulfidation method needs to be developed. Based on this, the present application provides a new sulfidation method of a mercury removal agent. SUMMARY

[0004] Based on the above description, the present application provides a sulfidation method of a mercury removal agent to improve the sulfidation process of the mercury removal agent to overcome the defects of long sulfidation time or incomplete sulfidation of the existing mercury removal agent.

[0005] The technical solution of the present application to solve the above technical problems is as follows:

[0006] The present application provides a sulfidation method of a mercury removal agent, comprising:

[0007] Step 1: dry immersion sulfidation of the mercury removal agent precursor using ammonium sulfide solution;

[0008] Step 2: drying treatment of the sample after dry immersion sulfidation in step 1 using hydrogen sulfide gas;

[0009] Step 3: dry sulfidation of the sample during the drying process in step 2 to obtain the sulfided mercury removal agent.

[0010] On the basis of the above technical solutions, the application can be further improved as follows.

[0011] Further, the step 1 specifically comprises:

[0012] Mix the normal-temperature ammonium sulfide solution with the mercury removal agent precursor, and dry-immerse the mercury removal agent precursor in the sulfuration reactor for 1-2 hours.

[0013] Further, the amount of the normal-temperature ammonium sulfide solution is 80-95% of the amount required for complete sulfuration of the mercury removal agent precursor.

[0014] Further, the mass percentage concentration of the ammonium sulfide solution is 8-10%.

[0015] Further, the step 2 specifically comprises:

[0016] Use hot nitrogen gas to circulate and purge the bed layer;

[0017] Cool the hot nitrogen gas coming out of the sulfuration reactor to collect the aqueous ammonia solution.

[0018] Further, the step 3 specifically comprises:

[0019] When the temperature of the bed layer is raised to 118-125℃ by the hot nitrogen gas, hydrogen sulfide gas is introduced into the circulating nitrogen gas; the temperature of the bed layer is continuously raised to 146-155℃ by the hot nitrogen gas, and the bed layer is cooled after 2-3 hours of reaction.

[0020] Further, after the hydrogen sulfide gas is introduced into the circulating nitrogen gas, the concentration of hydrogen sulfide in the mixed gas is controlled to be 3-5%.

[0021] Further, the space velocity of the circulating nitrogen gas is 300-500h -1 .

[0022] Compared with the prior art, the technical solutions of the application have the following beneficial technical effects:

[0023] The sulfuration method of the mercury removal agent provided by the application adopts mixed wet and dry sulfuration, saves sulfuration time, reduces from more than 70 hours of the original traditional sulfuration method to tens of hours, and improves production efficiency; meanwhile, sulfuration at room temperature with an ammonium sulfide solution is adopted, because the liquid heat capacity is much higher than the gas heat capacity, the problem of easy flying temperature of the mercury sulfide bed layer due to large heat release of the reaction of hydrogen sulfide and metal oxide in the gas phase dry sulfuration is avoided, and production safety is improved. Further, dry immersion sulfuration with the ammonium sulfide solution is adopted, because there is no excess liquid when the mercury removal agent precursor is immersed, it can be ensured that the copper ions are not taken away and lost after being dissolved by the generated ammonia, the heat generated by the sulfuration reaction is used to heat the mercury removal agent bed layer, ammonia is more easily escaped, and the drying energy consumption is saved. Moreover, the residual copper that is not sulfured is further sulfured with hydrogen sulfide gas in the drying process, so that the sulfuration of the mercury removal agent precursor is more complete, the sulfur content in the mercury removal agent is high, and the problems of easy flying temperature of the bed layer and long sulfuration time when the dry sulfuration is used at the beginning are avoided. Therefore, the sulfuration method is a rapid sulfuration method, the ammonium sulfide solution is used as a sulfuration agent for wet sulfuration, and then the hydrogen sulfide gas is used for continuous sulfuration in the drying process until the sulfuration is completed, so that the sulfuration method has the advantages of short sulfuration time and high efficiency. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present application, the embodiments of the present application are further described in detail below in combination with examples, and the following examples are used to illustrate the present application but cannot be used to limit the scope of the present application.

[0025] At present, the mercury removal technologies used at home and abroad mainly include low-temperature separation method, chemical adsorption method, solution absorption method, anion resin and membrane separation method, etc. Among them, the chemical adsorption method has high mercury removal precision, large treatment capacity, wide application range and low price, so at present, most of the natural gas mercury removal processes adopt the chemical adsorption method as the main mercury removal method. Usually, a fixed bed provided with a mercury removal agent is used for adsorption, the elemental mercury in the natural gas reacts with the active substances in the adsorbent to generate mercury compounds which are fixed on the mercury removal agent, so as to be separated from the natural gas. This method has a relatively simple process flow, requires less equipment, and has a small occupied area.

[0026] The commonly used mercury removal agents include sulfur-loaded activated carbon, sulfur-loaded aluminum oxide, metal sulfide and metal halide mercury removal agents. Compared with each other, the metal sulfide mercury removal agent has the characteristics of high mercury removal efficiency, large mercury capacity and flexible operation, and is currently widely used for natural gas mercury removal. For example, the CMC273 mercury removal agent of the Axens company is prepared by taking CuS as the active component and Al2O3 particles as the carrier, and this mercury removal agent has been used for domestic natural gas treatment plant Hg removal.

[0027] However, the current metal sulfide mercury removal agent generally uses copper as the active metal and alumina as the carrier, and needs to be sulfided to have the mercury removal activity. As stated in the background art, the current sulfidation methods have certain defects. Based on this, the application provides a sulfidation method of a mercury removal agent, which comprises the following steps:

[0028] Step 1: dry impregnation sulfidation of the mercury removal agent precursor is carried out using an ammonium sulfide solution.

[0029] Specifically, the normal-temperature ammonium sulfide solution is mixed with the mercury removal agent precursor, and the mercury removal agent precursor is dry-impregnated in the sulfidation reactor for 1-2 hours. The amount of the normal-temperature ammonium sulfide solution is 80-95% of the amount required for complete sulfidation of the mercury removal agent precursor; and the mass percentage concentration of the ammonium sulfide solution is 8-10%.

[0030] Step 2: dry treatment of the sample after dry impregnation sulfidation in step 1 is carried out using hydrogen sulfide gas.

[0031] Specifically, the bed layer is purged using hot nitrogen gas circulation; and the hot nitrogen gas coming out of the sulfidation reactor is cooled to collect the aqueous ammonia solution.

[0032] Step 3: dry sulfidation of the sample is carried out during the drying process in step 2, and the sulfided mercury removal agent is obtained.

[0033] Specifically, when the temperature of the bed layer is raised to 118-125℃ by the hot nitrogen gas, the hydrogen sulfide gas is introduced into the circulating nitrogen gas (the space velocity of the circulating nitrogen gas is 300-500h -1 -1), and the concentration of hydrogen sulfide in the mixed gas is controlled to be 3-5%; the temperature of the bed layer is continuously raised to 146-155℃ by the hot nitrogen gas, and the bed layer is cooled after 2-3 hours of reaction.

[0034] The sulfidation method of the mercury removal agent is further introduced in combination with specific examples.

[0035] Example

[0036] The example provides a sulfidation method of a mercury removal agent.

[0037] Step S1: 100 kg of mercury removal agent precursor with a bulk specific gravity of 750 kg / m 3 , a pore volume of 0.65 cm 3 / g and a copper content of 15 w% is taken into a sulfidation reactor, 65 kg of ammonium sulfide solution containing 10 w% of sulfur is pumped into the bed layer of the mercury removal agent precursor, and after all the ammonium sulfide solution is pumped in, it is left for 1 hour to allow the ammonium sulfide to fully react.

[0038] Step S2: after the reaction, the bed layer is heated by circulating nitrogen gas at a space velocity of 400h -1 -1, so that the temperature of the bed layer reaches 120℃, and at the same time, the nitrogen gas at the outlet of the bed layer is cooled to collect the aqueous ammonia.

[0039] Step S3: hydrogen sulfide gas was introduced into the circulating nitrogen, the hydrogen sulfide content at the bed inlet was controlled at about 3%, and the bed temperature was increased to 150°C, and reacted for 2h. When the hydrogen sulfide content was unchanged, the introduction of hydrogen sulfide was stopped, heating was stopped, nitrogen continued to circulate, and the bed began to cool down. When the sulfidation was completed, the desulfurizer was obtained. The entire sulfidation process took a total of 11 hours.

[0040] Comparative Example 1

[0041] The comparative example provides a sulfidation method of a desulfurizer.

[0042] Step S1: 100 kg of desulfurizer precursor with a bulk specific gravity of 750 kg / m 3 , a pore volume of 0.65 cm 3 / g, and a copper content of 15 w% was placed in a sulfidation reactor. 80 kg of ammonium sulfide solution containing 10 w% sulfur was pumped into the desulfurizer precursor bed. After all the ammonium sulfide solution was pumped in, it was left to stand for 6h to allow the ammonium sulfide to fully react.

[0043] Step S2: After the reaction, the excess residue was discharged, the bed was heated by circulating nitrogen to make the bed temperature reach 150°C, and ammonia water was collected by cooling the nitrogen gas at the bed outlet. After drying for 2h, the bed began to cool down, and the desulfurizer was obtained. The entire sulfidation process took a total of 14 hours.

[0044] Compared with the example, the comparative example does not include the dry sulfidation process of step 3 in the example.

[0045] Comparative Example 2

[0046] The comparative example provides a sulfidation method of a desulfurizer.

[0047] 100 kg of desulfurizer precursor with a bulk specific gravity of 750 kg / m 3 , a pore volume of 0.65 cm 3 / g, and a copper content of 15 w% was placed in a sulfidation reactor. The bed was heated by circulating nitrogen at a space velocity of 500h -1 -1, and the bed temperature reached 150°C. Then hydrogen sulfide gas was introduced into the circulating nitrogen, the hydrogen sulfide content at the bed inlet was controlled at about 3%, and the bed temperature was increased to 150°C, and reacted for 2h. When the hydrogen sulfide content was unchanged, the introduction of hydrogen sulfide was stopped, heating was stopped, nitrogen continued to circulate, and the bed began to cool down. When the sulfidation was completed, the desulfurizer was obtained. The entire sulfidation process took a total of 11 hours.

[0048] Compared with the example, the comparative example does not include the dry sulfidation process of step 3 in the example.

[0049] The above sulfurized mercury removal agent is evaluated and analyzed, and the test results are shown in Table 1.

[0050] Table 1 Test results of mercury removal agent of examples and comparative examples

[0051] Sample Cu content w% S content w% Demercuration agent precursor 14.85 0.05 Example 14.44 7.25 Comparative Example 1 13.98 7.02 Comparative Example 2 14.46 7.24

[0052] In combination with Table 1, it can be seen that the sulfur contents of the examples and comparative example 2 are equivalent, and both have good vulcanization effects, but only 11 hours are used in the examples, while 50.5 hours are used for vulcanization in the comparative example, and the vulcanization efficiency of the examples of the present application is higher; the sulfur content of the examples is higher than that of comparative example 1, and the vulcanization time is also shorter than that of comparative example 1, so compared with the comparative examples, the examples of the present application have better vulcanization effects.

[0053] In summary, the vulcanization method of the mercury removal agent prepared by the present application uses mixed wet and dry vulcanization, which saves the vulcanization time, reduces it from more than 70 hours of the original traditional vulcanization method to tens of hours, and improves the production efficiency; at the same time, the ammonium sulfide solution is used for vulcanization at room temperature, because the liquid heat capacity is much higher than the gas heat capacity, the problem of easy flying temperature of the bed layer due to large heat release of hydrogen sulfide and metal oxide reaction in the gas phase dry vulcanization is avoided, and the production safety is improved. Further, the ammonium sulfide solution is used for dry immersion vulcanization, because there is no excess liquid when the mercury removal agent precursor is immersed, the copper ions can be ensured not to be dissolved and carried away by the generated ammonia, and the heat generated by the vulcanization reaction is used to heat the mercury removal agent bed layer, so that the ammonia is more easily escaped and the drying energy consumption is also saved. Moreover, in the drying process, the residual copper that has not been vulcanized is further vulcanized by using hydrogen sulfide gas, so that the mercury removal agent precursor is more completely vulcanized, the sulfur content in the mercury removal agent is high, and the problems of easy flying temperature of the bed layer and long vulcanization time in the beginning of dry vulcanization are avoided. Therefore, the vulcanization method is a rapid vulcanization method, which uses ammonium sulfide solution as a vulcanizing agent for wet vulcanization, and then uses hydrogen sulfide gas for further vulcanization during the drying process until the vulcanization is completed, and has the advantages of short vulcanization time and high efficiency.

[0054] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for vulcanizing a mercury removal agent, characterized by, The method comprises the following steps: The dry impregnation sulfuration is performed on the mercury removal agent precursor by using an ammonium sulfide solution; Specifically, the ammonium sulfide solution is mixed with the mercury removal agent precursor, and the dry impregnation of the mercury removal agent precursor is performed in a sulfuration reactor for 1-2 hours; the dosage of the ammonium sulfide solution at normal temperature is 80-95% of the dosage required for completely sulfurizing the mercury removal agent precursor; the mass percentage concentration of the ammonium sulfide solution is 8-10%; The bed layer is circularly purged by using hot nitrogen gas, and the sample after the dry impregnation sulfuration is dried by using hydrogen sulfide gas; the hot nitrogen gas out of the sulfuration reactor is cooled, and an aqueous ammonia solution is collected; The sample is dry sulfurized in the process of the drying treatment, and the sulfurized mercury removal agent is obtained. The drying treatment and the dry vulcanization specifically include: when the temperature of the bed layer is raised to 118-125 DEG C by the hot nitrogen, hydrogen sulfide gas is introduced into the circulating nitrogen, and then the concentration of hydrogen sulfide in the mixed gas is controlled to be 3-5%, the space velocity of the circulating nitrogen is 300-500h -1 ; the temperature of the bed layer is continuously raised to 146-155 DEG C by the hot nitrogen, and the bed layer is cooled after reacting for 2-3h.