Limestone powder reaction rate determination method and application for flue gas wet desulfurization

Abstract

The present application proposes a method for determining the reaction rate of limestone powder for wet flue gas desulfurization and its application, wherein the method for determining the reaction rate of limestone powder for wet flue gas desulfurization comprises the following steps: (1) titrating the reaction medium with acid, adjusting the pH of the reaction medium, and recording the amount of acid added at each first interval; (2) when the reaction medium reaches the target pH, continuing to drop the acid, and obtaining the amount of acid added within the second time; (3) if the amount of acid added within the second time does not change significantly, adding limestone powder, and continuing to titrate with acid; (4) setting the target conversion fraction of limestone powder, and obtaining the target amount of acid added required for limestone powder to reach the target conversion fraction and the reaction time required to reach the target addition amount according to the target conversion fraction. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization described in the present application can minimize the influence of the ion system on the activity of hydrogen ions.

Description

Technical Field

[0001] The present application relates to the technical field of flue gas treatment, and in particular to a method for comparing the reaction rates of limestone powder for desulfurization in different reaction media. Background Art

[0002] The industry standard DL / T 943 "Determination of reaction rate of limestone powder for wet flue gas desulfurization" introduces a method for determining the dissolution rate of limestone powder in 0.1mol / L calcium chloride solution. This method directly adds a certain amount of limestone powder to the calcium chloride solution, titrates with 0.1mol / L hydrochloric acid solution and maintains it to the target pH, and reflects the conversion of limestone powder with the amount of hydrochloric acid added. This method can obtain the reaction of limestone powder in 0.1mol / L calcium chloride solution. However, this standard has certain limitations: 0.1mol / L calcium chloride solution will affect the activity of hydrogen ions, so that part of the hydrochloric acid added cannot participate in the reaction with limestone powder, which will cause a large error in the measurement result. In addition, the slurry composition in the wet desulfurization system is very complex, and the reaction medium of limestone powder is complex and diverse. The DL / T 943 standard can only obtain the reaction of limestone powder in a single medium (0.1mol / L calcium chloride solution), which is not suitable for the reaction rate determination of limestone powder in multiple reaction media, and thus cannot compare the reaction rates in multiple reaction media. Summary of the invention

[0003] In view of this, an object of the present application is to provide a method for determining the reaction rate of limestone powder for wet flue gas desulfurization, by pre-titrating the reaction medium with acid and maintaining it to the target pH, and then adding a certain amount of limestone powder. At this time, the acid consumed is only used to react with the limestone powder, which can minimize the influence of the ion system on the activity of hydrogen ions.

[0004] Another object of the present application is to provide a method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media.

[0005] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a method for measuring the reaction rate of limestone powder for wet flue gas desulfurization, comprising the following steps:

[0006] (1) titrating the reaction medium with an acid to adjust the pH of the reaction medium, and recording the amount of acid added at each first time interval;

[0007] (2) when the reaction medium reaches the target pH, continue to drip the acid, obtain the dripping amount of the acid in the second time, and determine whether the dripping amount of the acid in the second time changes significantly;

[0008] (3) if the amount of the acid added during the second time period does not change significantly, then add limestone powder, continue titrating with the acid, and record the amount of the acid added at each interval of the third time period;

[0009] (4) setting a target conversion fraction of the limestone powder, and obtaining a target amount of acid required for the limestone powder to reach the target conversion fraction based on the target conversion fraction, and taking the reaction time required for the total amount of acid consumed by the limestone powder in step (3) to reach the target amount as an indicator of the reaction rate of the limestone powder in the reaction medium.

[0010] In some embodiments, in step (1), the method of titrating the reaction medium with an acid is: dripping the acid into the reaction medium at 45-55° C. and 400-800 r / min with stirring.

[0011] In some embodiments, in step (1), the concentration of the acid is 0.01-1 mol / L, and the first time is 10-90 s.

[0012] In some embodiments, in step (1), the acid is one of hydrochloric acid and sulfuric acid.

[0013] In some embodiments, in step (2), the target pH is between 4.5-6.0, and the second time is 3-10 min.

[0014] In some embodiments, in step (2), the method for determining whether the amount of the acid added during the second time period changes significantly is:

[0015] If the amount of the acid added during the second time is ≤ 1 wt % of the amount of the acid added during the second time to reach the target pH of the reaction medium, it is deemed that the amount of the acid added during the second time has not changed significantly;

[0016] If the amount of the acid added during the second time is greater than 1 wt % of the amount of the acid added to achieve the target pH of the reaction medium, it is considered that the amount of the acid added during the second time has changed significantly.

[0017] In some embodiments, in step (3), the amount of limestone powder added is (0.05-0.5) g of limestone powder per (100-500) mL of the reaction medium.

[0018] In some embodiments, in step (3), the third time is 10-90s.

[0019] In some embodiments, in step (4), the target conversion fraction is 50-90%.

[0020] In some embodiments, in step (4), the target drop amount is obtained according to formula ①:

[0021]

[0022] In formula ①:

[0023] X——target conversion fraction of limestone powder;

[0024] c——acid concentration, mol / L;

[0025] m——the target amount of acid required for the target conversion fraction of limestone powder, g;

[0026] W——mass of limestone powder, g;

[0027] ——The mass percentage of calcium carbonate in limestone powder is the measured value;

[0028] ——The mass percentage of magnesium carbonate in limestone powder is the measured value;

[0029] M(CaCO 3 )——the molecular weight of calcium carbonate, which is 100;

[0030] M(MgCO 3 )——The molecular weight of magnesium carbonate is 40.

[0031] Density of ρ-acid solution, g / mL.

[0032] In some embodiments, the reaction medium is a calcium chloride solution, or a mixture of magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil.

[0033] In some embodiments, when the reaction medium is a mixed solution comprising magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil, the concentration of each component is: magnesium chloride 7-65 g / L, magnesium sulfate 0.01-0.1 g / L, calcium chloride 10-45 g / L, aluminum nitrate 0.05-0.15 mmol / L, sodium fluoride 0.1-1 mmol / L, smoke 0.1-0.5 g / L, oil 0.01-0.1 g / L.

[0034] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media, comprising:

[0035] After the reaction rate of the limestone powder for wet flue gas desulfurization in the reaction medium is determined by the reaction rate determination method of the limestone powder for wet flue gas desulfurization in the embodiment of the present application, the reaction medium is replaced with other multiple reaction media in turn for determination;

[0036] By comparing the time required for limestone powder to reach the same target conversion fraction in different reaction media, the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media are compared.

[0037] In some embodiments, the other multiple reaction media all include: magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil.

[0038] The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to the embodiment of the present application can bring the following beneficial effects:

[0039] (1) By titrating the reaction medium with acid in advance and maintaining it to the target pH, a certain amount of limestone powder is added. At this time, the acid consumed is only used to react with the limestone powder, which can minimize the influence of the ion system on the hydrogen ion activity;

[0040] (2) It can be used to measure the reaction rate of limestone powder when the reaction medium is calcium chloride alone or with multiple components, and further compare the reaction rates of limestone powder in various reaction media.

[0041] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0043] Figure 1 This is a graph showing the relationship between the amount of hydrochloric acid added and time during the titration process of Example 1 of the present application.

[0044] Figure 2 The figure is a graph showing the relationship between the consumption of hydrochloric acid and time during the titration process of Comparative Example 1.

[0045] Figure 3 This is a graph showing the relationship between the amount of hydrochloric acid added and time during the titration process of Example 2 of the present application.

[0046] Figure 4 This is a graph showing the relationship between the amount of hydrochloric acid added and time during the titration process of Example 3 of the present application.

[0047] Figure 5 This is a graph showing the relationship between the amount of hydrochloric acid added and time during the titration process of Example 4 of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, but cannot be understood as limiting the present application.

[0049] Throughout the application, the disclosure of numerical ranges includes all values ​​within the entire range and disclosure of further subdivided ranges, including endpoints and subranges given within those ranges.

[0050] In the application, the raw materials, equipment, etc. involved, unless otherwise specified, are all raw materials and equipment that can be produced through commercial channels or known methods; the methods involved, unless otherwise specified, are all conventional methods.

[0051] The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to the embodiment of the present application comprises the following steps:

[0052] (1) titrating the reaction medium with an acid to adjust the pH of the reaction medium, and recording the amount of acid added at each interval;

[0053] (2) when the reaction medium reaches the target pH, continue to dropwise add the acid, and obtain the amount of the acid added during the second time, and determine whether the amount of the acid added during the second time changes significantly;

[0054] (3) If the amount of acid added during the second time period does not change significantly, limestone powder is added and the acid is continued to be titrated, and the amount of acid added is recorded at every third time interval;

[0055] (4) setting a target conversion fraction of the limestone powder, and obtaining a target amount of acid required for the limestone powder to reach the target conversion fraction based on the target conversion fraction, and taking the reaction time required for the total amount of acid consumed by the limestone powder in step (3) to reach the target amount as an indicator of the reaction rate of the limestone powder in the reaction medium.

[0056] The method for determining the reaction rate of limestone powder for wet flue gas desulfurization in the embodiment of the present application can bring about the following beneficial effects: by pre-titrating the reaction medium with acid and maintaining it to the target pH, and then adding a certain amount of limestone powder, the acid consumed at this time is only used to react with the limestone powder, which can minimize the impact of the ion system on the activity of hydrogen ions.

[0057] In some examples, in step (1), the method of using acid to titrate the reaction medium is: the acid is dripped into the reaction medium under the conditions of stirring at 45-55°C and 400-800r / min. Specifically, a certain amount of the reaction medium can be heated to a constant temperature of 45-55°C, and then the reaction medium is continuously stirred at a stirring rate of 400-800r / min, and then the acid titration is performed. In some embodiments, the amount of the reaction medium includes but is not limited to 100mL, 150mL, 250mL or 500mL, etc., preferably 250mL; the constant temperature includes but is not limited to 45°C, 50°C or 55°C, etc., preferably 50°C; the stirring rate includes but is not limited to 400r / min, 500r / min, 600r / min, 700r / min or 800r / min, etc., preferably 600r / min or more.

[0058] In some embodiments, the acid titration in step (1) is performed using an automatic titrator, the acid concentration is 0.01-1 mol / L, and the first time is 10-90s; the acid includes but is not limited to one or more of hydrochloric acid, sulfuric acid, etc. As a non-limiting example, the acid is hydrochloric acid, and the acid concentration includes but is not limited to 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, etc., preferably 0.1 mol / L; during the acid titration process, the amount of acid added is accurately recorded every 10s, 30s, 60s or 90s (i.e., the first time).

[0059] In some embodiments, in step (2), the target pH is between 4.5 and 6.0, and the second time is 3 to 10 minutes. As a non-limiting example, the target pH includes but is not limited to 4.5, 5.0, 5.5 or 6.0, etc., preferably 5.5; the second time includes but is not limited to 3 minutes, 5 minutes, 8 minutes or 10 minutes, etc., preferably more than 5 minutes.

[0060] In some embodiments, in step (3), the amount of limestone powder added is (0.05-0.5) g of limestone powder per (100-500) mL of reaction medium. As a non-limiting example, the amount of limestone powder added is 0.05 g, 0.1 g, 0.15 g, 0.3 g or 0.5 g, etc., preferably 0.1 g or 0.15 g, per (100-500) mL of reaction medium.

[0061] In some embodiments, in step (3), the third time is 10-90 seconds. As a possible example, the third time is the same as the first time.

[0062] In some embodiments, the method for determining whether the amount of acid added during the second time period changes significantly is:

[0063] If the amount of acid added during the second time is ≤ 1 wt % of the amount of acid added during the second time required for the reaction medium to reach the target pH, it is deemed that the amount of acid added during the second time has not changed significantly;

[0064] If the amount of acid added during the second time is greater than 1 wt % of the amount of acid added to achieve the target pH of the reaction medium, it is considered that the amount of acid added during the second time has changed significantly.

[0065] In some embodiments, in step (4), the target conversion fraction is 50-90%, including but not limited to 50%, 60%, 70%, 80% or 90%, etc.

[0066] In some embodiments, in step (4), the target drop amount is obtained according to formula ①:

[0067]

[0068] In formula ①:

[0069] X——target conversion fraction of limestone powder;

[0070] c——acid concentration, mol / L;

[0071] m——the target amount of acid required for the target conversion fraction of limestone powder, g;

[0072] W——mass of limestone powder, g;

[0073] ——The mass percentage of calcium carbonate in limestone powder is the measured value;

[0074] ——The mass percentage of magnesium carbonate in limestone powder is the measured value;

[0075] M(CaCO 3 )——the molecular weight of calcium carbonate, which is 100;

[0076] M(MgCO 3 )——The molecular weight of magnesium carbonate is 40.

[0077] Density of ρ-acid solution, g / mL.

[0078] It should be noted that the time required for the limestone powder to reach the target conversion fraction in actual use is indirectly obtained according to formula ①. Specifically, the acid consumption can be calculated according to the set target conversion fraction of the limestone powder. Since the amount of acid added during the titration process is recorded at any time, the reaction time corresponding to the amount of acid added when the limestone powder reaches the target conversion fraction (that is, the amount of acid added consumed by the limestone powder) is the time required for the limestone powder to reach the target conversion fraction. The longer the time, the slower the reaction rate of the limestone powder in the reaction medium.

[0079] In some embodiments, the reaction medium can select calcium chloride solution. But in other embodiments, the reaction medium can also select a mixed solution comprising magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil. As a non-limiting example, when the reaction medium is a mixed solution comprising magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil, the concentration of each component is: magnesium chloride 7-65g / L, magnesium sulfate 0.01-0.1g / L, calcium chloride 10-45g / L, aluminum nitrate 0.05-0.15mmol / L, sodium fluoride 0.1-1mmol / L, smoke 0.1-0.5g / L, oil 0.01-0.1g / L. Wherein oil can be any kind of oil, including but not limited to one or more of vegetable oil, animal oil or mineral oil, etc., and smoke can be any kind of smoke, such as smoke from a thermal power plant, etc.

[0080] The method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media in the embodiment of the present application includes:

[0081] After the reaction rate of the limestone powder for wet flue gas desulfurization in the reaction medium is determined by the reaction rate determination method of the limestone powder for wet flue gas desulfurization in the embodiment of the present application, the reaction medium is replaced with other multiple reaction media in turn for determination;

[0082] By comparing the time required for limestone powder to reach the same target conversion fraction in different reaction media, the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media are compared.

[0083] In some embodiments, the other multiple reaction media all include: magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil, wherein the oil includes but is not limited to one or more of vegetable oil, animal oil or mineral oil, etc. As a non-limiting example, when the reaction medium and other reaction media all include a mixed solution of magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil, the concentration of each component is: magnesium chloride 7-65g / L, magnesium sulfate 0.01-0.1g / L, calcium chloride 10-45g / L, aluminum nitrate 0.05-0.15mmol / L, sodium fluoride 0.1-1mmol / L, smoke 0.1-0.5g / L, oil 0.01-0.1g / L, and in all reaction media including the reaction medium and other reaction media, the concentrations of at least three substances, magnesium chloride, magnesium sulfate and calcium chloride, are different, which serves as a standard for distinguishing different reaction media.

[0084] It should be noted that the method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media in the embodiments of the present application is to determine the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media using the method for determining the reaction rate of limestone powder for wet flue gas desulfurization in the embodiments of the present application. Except for changing the reaction medium, the selection of various process parameters should remain the same, such as the amount of limestone powder added, acid concentration, recording interval time, limestone target conversion fraction, etc.

[0085] The determination method and comparison method of the present application are explained below with reference to specific embodiments and comparative examples.

[0086] 1. Examples and Comparative Examples

[0087] Example 1

[0088] First, heat 250mL of 0.1mol / L calcium chloride solution to 50°C, then continue stirring at a stirring rate of 600r / min, and use an automatic titrator to titrate the above 250mL of 0.1mol / L calcium chloride solution with 0.1mol / L hydrochloric acid. During the titration process, accurately record the amount of hydrochloric acid added every 60s. When the pH of the calcium chloride solution is 5.5, continue to drip 0.1mol / L hydrochloric acid, judge whether the amount of hydrochloric acid added changes significantly within 5min, when it is found that the amount of hydrochloric acid added does not change significantly within 5min (the amount of hydrochloric acid added is 1wt% of the amount of hydrochloric acid used when the pH of the calcium chloride solution reaches 5.5), add 0.15g limestone powder, and continue titration with 0.1mol / L hydrochloric acid, and accurately record the amount of hydrochloric acid added every 60s during the titration process, afterwards according to formula ① indirectly obtain the target amount of 0.1mol / L hydrochloric acid required for limestone powder to reach a preset 80% conversion fraction is 22.42g, the reaction time when the total amount of hydrochloric acid consumed by the limestone powder reaches the target amount is 44min, and this reaction time is used as an index to characterize the reaction rate of limestone powder in 250mL 0.1mol / L calcium chloride solution.

[0089] Example 2

[0090] A mixed solution of magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke from a thermal power plant and No. 0 diesel was prepared, wherein the concentration of each component was: magnesium chloride 7.35 g / L, magnesium sulfate 0.02 g / L, calcium chloride 40.36 g / L, aluminum nitrate 0.1 mmol / L, sodium fluoride 0.5 mmol / L, smoke from a thermal power plant 0.2 g / L, and oil 0.05 g / L. The composition of smoke from a thermal power plant is shown in Table 1.

[0091] Table 1 Composition of smoke from thermal power plants

[0092]

[0093] First, heat 250 mL of the mixed solution to 50°C, then continue stirring at a stirring rate of 750 r / min, and use an automatic titrator to titrate the mixed solution with 0.1 mol / L hydrochloric acid. During the titration process, accurately record the amount of hydrochloric acid added every 60 seconds (i.e., the first time). When the pH value of the mixed solution is 5.5, continue to drip 0.1mol / L hydrochloric acid, and judge whether the amount of hydrochloric acid added changes significantly within 5min. When it is found that the amount of hydrochloric acid added does not change significantly within 5min (i.e. the second time) (the amount of hydrochloric acid added is 1wt% of the amount of hydrochloric acid used when the pH value of the mixed solution reaches 5.5), add 0.15g limestone powder, and continue titration with 0.1mol / L hydrochloric acid, and accurately record the amount of hydrochloric acid added every 60s (i.e. the third time) during the titration process. Afterwards, according to formula ①, indirectly obtain the target amount of 0.1mol / L hydrochloric acid required for the limestone powder to reach a preset conversion fraction of 80%, which is 22.42g. The reaction time when the total amount of hydrochloric acid consumed by the limestone powder reaches the target amount is 77min. This reaction time is used as an indicator to characterize the reaction rate of the limestone powder in 250mL of the mixed solution.

[0094] Example 3

[0095] A mixed solution of magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke from a thermal power plant and No. 0 diesel was prepared, wherein the concentrations of the components were: 20.28 g / L of magnesium chloride, 0.03 g / L of magnesium sulfate, 33.3 g / L of calcium chloride, 0.1 mmol / L of aluminum nitrate, 0.5 mmol / L of sodium fluoride, 0.2 g / L of smoke from a thermal power plant, and 0.05 g / L of oil. The composition of the smoke from the thermal power plant was the same as that in Example 2.

[0096] First, heat 250 mL of the mixed solution to 50°C, then continue stirring at a stirring rate of 600 r / min, and use an automatic titrator to titrate the mixed solution with 0.1 mol / L hydrochloric acid. During the titration process, accurately record the amount of hydrochloric acid added every 60 seconds. When the pH value of the mixed solution is 5.5, continue to drip 0.1mol / L hydrochloric acid, and judge whether the amount of hydrochloric acid added changes significantly within 5min. When it is found that the amount of hydrochloric acid added does not change significantly within 5min (the amount of hydrochloric acid added is 1wt% of the amount of hydrochloric acid used when the pH value of the mixed solution reaches 5.5), add 0.15g limestone powder, and continue titration with 0.1mol / L hydrochloric acid, and accurately record the amount of hydrochloric acid added every 60s during the titration process. Afterwards, the target amount of 0.1mol / L hydrochloric acid required for the limestone powder to reach a preset conversion fraction of 80% is indirectly obtained according to formula ①, which is 22.42g. The reaction time when the total amount of hydrochloric acid consumed by the limestone powder reaches the target amount is 61min. This reaction time is used as an indicator to characterize the reaction rate of the limestone powder in 250mL of the mixed solution.

[0097] Example 4

[0098] A mixed solution of magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke from a thermal power plant and No. 0 diesel was prepared, wherein the concentrations of the components were: 60.8 g / L of magnesium chloride, 0.09 g / L of magnesium sulfate, 11.1 g / L of calcium chloride, 0.1 mmol / L of aluminum nitrate, 0.5 mmol / L of sodium fluoride, 0.2 g / L of smoke from a thermal power plant, and 0.05 g / L of oil. The composition of the smoke from the thermal power plant was the same as that in Example 2.

[0099] First, heat 250 mL of the mixed solution to 50°C, then continue stirring at a stirring rate of 600 r / min, and use an automatic titrator to titrate the mixed solution with 0.1 mol / L hydrochloric acid. During the titration process, accurately record the amount of hydrochloric acid added every 60 seconds. When the pH value of the mixed solution is 5.5, continue to drip 0.1mol / L hydrochloric acid, and judge whether the amount of hydrochloric acid added changes significantly within 5min. When it is found that the amount of hydrochloric acid added does not change significantly within 5min (the amount of hydrochloric acid added is 1wt% of the amount of hydrochloric acid used when the pH value of the mixed solution reaches 5.5), add 0.15g limestone powder, and continue titration with 0.1mol / L hydrochloric acid, and accurately record the amount of hydrochloric acid added every 60s during the titration process. Afterwards, the target amount of 0.1mol / L hydrochloric acid required for the limestone powder to reach a preset conversion fraction of 80% is indirectly obtained according to formula ①, which is 22.42g. The reaction time when the total amount of hydrochloric acid consumed by the limestone powder reaches the target amount is 23min. This reaction time is used as an indicator to characterize the reaction rate of the limestone powder in 250mL of the mixed solution.

[0100] The method for determining the reaction rate of limestone powder for wet flue gas desulfurization in Example 5-20 is basically the same as that in Example 2, except that some parameters are designed differently, as shown in Table 2.

[0101] Table 2 Partial parameter design of the method for determining the reaction rate of limestone powder for wet flue gas desulfurization of Examples 5-20

[0102]

[0103]

[0104] Embodiment 21

[0105] This embodiment is substantially the same as embodiment 1, except that: the target conversion fraction of the limestone powder is 50%, the target drop amount of 0.1 mol / L hydrochloric acid required for the limestone powder to reach a preset conversion fraction of 50% is indirectly obtained according to formula ①, and the reaction time when the total drop amount of hydrochloric acid consumed by the limestone powder reaches the target drop amount is 17 min, and this reaction time is used as an indicator to characterize the reaction rate of the limestone powder in 250 mL 0.1 mol / L calcium chloride solution.

[0106] Embodiment 22

[0107] This embodiment is basically the same as Example 2, except that: the target conversion fraction of the limestone powder is 60%, the target drop amount of 0.1 mol / L hydrochloric acid required for the limestone powder to reach the preset 60% conversion fraction indirectly obtained according to formula ① is 16.82 g, and the reaction time when the total drop amount of hydrochloric acid consumed by the limestone powder reaches the target drop amount is 30 min, and this reaction time is used as an indicator to characterize the reaction rate of the limestone powder in 250 mL of the mixed solution.

[0108] Embodiment 23

[0109] The method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media of this embodiment includes the following steps:

[0110] (1) preparing a first reaction medium, a second reaction medium and a third reaction medium, wherein the first reaction medium, the second reaction medium and the third reaction medium are all a mixture of magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke from a thermal power plant and No. 0 diesel, wherein the concentrations of the components of the first reaction medium are: magnesium chloride 7.35 g / L, magnesium sulfate 0.02 g / L, calcium chloride 40.36 g / L, aluminum nitrate 0.1 mmol / L, sodium fluoride 0.5 mmol / L, smoke from a thermal power plant 0.2 g / L, and oil 0.05 g / L; and the second reaction medium The concentration of each component of the medium is: magnesium chloride 20.28g / L, magnesium sulfate 0.03g / L, calcium chloride 33.3g / L, aluminum nitrate 0.1mmol / L, sodium fluoride 0.5mmol / L, thermal power plant dust 0.2g / L, oil 0.05g / L; the concentration of each component of the third reaction medium is: magnesium chloride 60.8g / L, magnesium sulfate 0.09g / L, calcium chloride 11.1g / L, aluminum nitrate 0.1mmol / L, sodium fluoride 0.5mmol / L, thermal power plant dust 0.2g / L, oil 0.05g / L. Among them, the composition of thermal power plant dust in the first reaction medium, the second reaction medium and the third reaction medium is the same as that in Example 2.

[0111] (2) 250 mL of the first reaction medium was heated to 50° C., and then continuously stirred at a stirring rate of 600 r / min. The first reaction medium was titrated with 0.1 mol / L hydrochloric acid using an automatic titrator. During the titration process, the amount of hydrochloric acid added was accurately recorded every 60 seconds.

[0112] (3) When the pH value of the mixed solution is 5.5, continue to add 0.1 mol / L hydrochloric acid to determine whether the amount of hydrochloric acid added changes significantly within 5 minutes. When it is found that the amount of hydrochloric acid added does not change significantly within 5 minutes (the amount of hydrochloric acid added is 1 wt% of the amount of hydrochloric acid used when the pH value of the mixed solution reaches 5.5), add 0.15 g of limestone powder and continue to titrate with 0.1 mol / L hydrochloric acid. During the titration process, accurately record the amount of hydrochloric acid added every 60 seconds (i.e., the third time).

[0113] (4) According to formula ①, the target drop amount of 0.1 mol / L hydrochloric acid required for the limestone powder to reach a preset conversion fraction of 80% is 22.42 g. The reaction time when the total drop amount of hydrochloric acid consumed by the limestone powder reaches the target drop amount is used as an indicator to characterize the reaction rate of the limestone powder in 250 mL of the first reaction medium.

[0114] (5) Replace the first reaction medium with a second reaction medium and repeat steps (2) to (4).

[0115] (6) Replace the first reaction medium with a third reaction medium and repeat steps (2) to (4).

[0116] (7) By comparing the reaction time required for the limestone powder to reach a conversion fraction of 80%, the reaction rates of the limestone powder for wet flue gas desulfurization in the first reaction medium, the second reaction medium and the third reaction medium are compared.

[0117] It should be noted that the process of determining the reaction rates of limestone powder in the first reaction medium, the second reaction medium and the third reaction medium in this embodiment is equivalent to the aforementioned embodiments 1, 2 and 3.

[0118] Comparative Example 1

[0119] This comparative example adopts the method of DL 943-2015 "Determination of reaction rate of limestone powder for wet flue gas desulfurization" to measure the reaction rate of limestone powder in 250mL 0.1mol / L calcium chloride solution. At the beginning, the limestone powder is put into 250mL 0.1mol / L calcium chloride solution, and then titration with 0.1mol / L hydrochloric acid is started and maintained to pH=5.5. During the titration process, the consumption of hydrochloric acid is accurately recorded, and the time required for the limestone powder to reach the preset 80% conversion fraction is calculated.

[0120] 2. Test Results

[0121] 1. Comparison of acid consumption

[0122] The relationship between the consumption of hydrochloric acid and time during the titration of Example 1 and Comparative Example 1 is shown in Figures 1 and 2. Figure 1 and Figure 2 As shown,

[0123] from Figure 2 It can be seen that the time required for 80% conversion of limestone powder in Comparative Example 1 is 30 minutes. Figure 1 It can be seen that 5.08 g of 0.1 mol / L hydrochloric acid is needed to make 250 mL of 0.1 mol / L calcium chloride solution dropwise to pH=5.5, indicating that the calcium chloride solution can strongly reduce the activity of hydrogen ions, proving that the method provided by the DL 943 standard (i.e., comparative example 1) has serious errors (if there is no interference of calcium chloride solution on the activity of hydrogen ions, adding 5.08 g of 0.1 mol / L hydrochloric acid can reduce the pH of the solution to about 2.7). According to the method provided in the present application, the amount of hydrochloric acid required for 80% conversion of limestone powder is the sum of the hydrochloric acid consumed in the early titration to make the pH of the calcium chloride solution reach 5.5 and the hydrochloric acid consumed by the subsequent titration of the limestone powder at pH = 5.5, that is, 5.08 + 22.42 = 27.5g. At this time, the total time is 58min, of which the time used for hydrochloric acid to titrate the calcium chloride solution to pH 5.5 before adding limestone powder and the sum of the second time is 14min. Therefore, the time required for the limestone powder to reach 80% conversion is 58-14 = 44min.

[0124] The relationship between the consumption of hydrochloric acid and time during the titration of Example 2, Example 3 and Example 4 is shown in Figures 1 and 2. Figure 3 , 4 , 5. From Figure 3 It can be seen that in Example 2, the mixed solution was added dropwise to pH = 5.5 and kept stable, the amount of hydrochloric acid consumed was 13.84g, the total amount of hydrochloric acid required for 80% conversion of limestone powder was 13.84+22.42=36.36g, and the time required for limestone powder to reach 80% conversion was 77min; Figure 4 It can be seen that in Example 3, the mixed solution was added dropwise to pH = 5.5 and kept stable, the amount of hydrochloric acid consumed was 11.85g, the total amount of hydrochloric acid required for 80% conversion of limestone powder was 11.85+22.42=34.27g, and the time required for limestone powder to reach 80% conversion was 61min; Figure 5It can be seen that in Example 4, the mixed solution was added dropwise to pH = 5.5 and kept stable, the amount of hydrochloric acid consumed was 2.92 g, the total amount of hydrochloric acid required for 80% conversion of limestone powder was 2.92 + 22.42 = 25.34 g, and the time required for the limestone powder to reach 80% conversion was 23 min.

[0125] 2. Comparison of reaction rates of limestone powder in different media when the conversion fraction reaches 80%

[0126] The reaction times when the conversion fraction of limestone powder in the first reaction medium, the second reaction medium and the third reaction medium in Example 23 reaches 80% are shown in Table 3.

[0127] Table 3 Reaction time when limestone powder reaches 80% conversion fraction in different reaction media in Example 23

[0128] Reaction medium Time required for limestone powder to reach 80% conversion fraction / min The first reaction medium 77 The second reaction medium 61 The third reaction medium 23

[0129] It can be seen from Table 3 that, when the concentrations of other components are the same and the magnesium sulfate concentrations are not much different, the higher the calcium chloride concentration and the lower the magnesium chloride concentration, the longer the time required for the limestone powder to reach an 80% conversion fraction, and vice versa. The time required for the limestone powder to reach an 80% conversion fraction is inversely proportional to the reaction rate. The longer the time required, the slower the reaction rate. That is, when the concentrations of other components are the same and the magnesium sulfate concentrations are not much different, the higher the calcium chloride concentration and the lower the magnesium chloride concentration, the slower the reaction rate of the limestone powder to reach an 80% conversion fraction, and vice versa.

[0130] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0131] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for determining the reaction rate of limestone powder for wet flue gas desulfurization, characterized in that: The following steps are involved: (1) titrating the reaction medium with an acid to adjust the pH of the reaction medium, and recording the amount of acid added at each first time interval; (2) when the reaction medium reaches the target pH, continue to drip the acid, obtain the dripping amount of the acid in the second time, and determine whether the dripping amount of the acid in the second time changes significantly; (3) if the amount of the acid added during the second time period does not change significantly, then add limestone powder, continue titrating with the acid, and record the amount of the acid added at each interval of the third time period; (4) setting a target conversion fraction of the limestone powder, and obtaining a target amount of acid required for the limestone powder to reach the target conversion fraction according to the target conversion fraction, and taking the reaction time required for the total amount of acid consumed by the limestone powder in step (3) to reach the target amount of acid as an indicator of the reaction rate of the limestone powder in the reaction medium; In step (2), the method for judging whether the amount of the acid added during the second time period changes significantly is as follows: If the amount of the acid added during the second time is ≤ 1 wt % of the amount of the acid added during the second time to reach the target pH of the reaction medium, it is deemed that the amount of the acid added during the second time has not changed significantly; If the amount of the acid added during the second time is greater than 1 wt % of the amount of the acid added during the second time to reach the target pH of the reaction medium, it is considered that the amount of the acid added during the second time has changed significantly; In step (4), the target drop amount is obtained according to formula ①: In formula ①: X——target conversion fraction of limestone powder; c——acid concentration, mol / L; m——the target amount of acid required for the target conversion fraction of limestone powder, g; W——mass of limestone powder, g; ——The mass percentage of calcium carbonate in limestone powder is the measured value; ——The mass percentage of magnesium carbonate in limestone powder is the measured value; M (CaCO3) – the molecular weight of calcium carbonate, which is 100; M (MgCO3) – the molecular weight of magnesium carbonate, which is 84; ρ-acid solution density, g / mL; The reaction medium is a calcium chloride solution, or a mixed solution containing magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil.

2. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to claim 1, characterized in that: In step (1), the method of titrating the reaction medium with an acid is as follows: dripping the acid into the reaction medium at 45-55° C. and stirring at 400-800 r / min.

3. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to claim 1, characterized in that: In step (1), the concentration of the acid is 0.01-1 mol / L, and the first time is 10-90 s; And / or, in step (1), the acid is hydrochloric acid.

4. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to claim 1, characterized in that: In step (2), the target pH is between 4.5 and 6.0, and the second time is 3 to 10 minutes.

5. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to claim 1, characterized in that: In step (3), the amount of limestone powder added is (0.05-0.5) g of limestone powder per (100-500) mL of the reaction medium; And / or, in step (3), the third time is 10-90s.

6. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to claim 1, characterized in that: In step (4), the target conversion score is 50-90%.

7. The method for determining the reaction rate of limestone powder for wet flue gas desulfurization according to claim 1, characterized in that: When the reaction medium is a mixed solution containing magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil, the concentration of each component is: magnesium chloride 7-65 g / L, magnesium sulfate 0.01-0.1 g / L, calcium chloride 10-45 g / L, aluminum nitrate 0.05-0.15 mmol / L, sodium fluoride 0.1-1 mmol / L, smoke 0.1-0.5 g / L, oil 0.01-0.1 g / L.

8. A method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media, characterized in that: include: After determining the reaction rate of the limestone powder for wet flue gas desulfurization in the reaction medium by using the reaction rate determination method for limestone powder for wet flue gas desulfurization according to any one of claims 1 to 7, the reaction medium is replaced with other multiple reaction media in sequence for determination; By comparing the reaction time required for limestone powder to achieve the same target conversion fraction in different reaction media, the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media are compared.

9. The method for comparing the reaction rates of limestone powder for wet flue gas desulfurization in different reaction media according to claim 8, characterized in that: The other various reaction media all include: magnesium chloride, magnesium sulfate, calcium chloride, aluminum nitrate, sodium fluoride, smoke and oil.

Images