Method for preparing lime slurry from mixed waste liquid

Abstract

The invention relates to the technical field of waste gas treatment, and discloses a method for preparing lime slurry from mixed waste liquid, which comprises the following steps: high-salinity wastewater generated by a first-stage wet washing tower is introduced into a wastewater tank for storage, meanwhile, physicochemical triple-effect distillation effluent generated by evaporation and condensation of the high-salinity wastewater is stored in a water pool, and the water pool is connected with a lime slurry stirring tank through a pipeline; the method comprises the following steps: introducing high-salinity wastewater and physicochemical triple-effect distillation water into a lime slurry stirring tank, monitoring the mass percent through a flow meter, mixing the high-salinity wastewater and the physicochemical triple-effect distillation water to obtain mixed wastewater, and measuring the salinity, the pH value and the density of the mixed wastewater; adding lime into the mixed wastewater, and fully and uniformly mixing the lime and the mixed wastewater; the wet-process high-salinity wastewater is combined with the triple-effect distillation water to prepare the lime slurry, so that the problem of high treatment cost of the high-salinity wastewater generated by a wet process is solved, the phenomenon of a spray gun structure is avoided, the atomization effect is ensured, the physicochemical triple-effect distillation water can be utilized, waste is treated by waste, and energy conservation and environmental protection are realized.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment, in particular to a method for preparing lime slurry by mixing waste liquid. Background Art

[0002] The centralized disposal of hazardous waste in my country is one of the key projects promoted by the country. With the continuous advancement of industrialization, the amount of hazardous waste continues to increase, but the number of hazardous waste treatment companies has increased significantly, which indirectly leads to higher requirements for hazardous waste treatment.

[0003] In the hazardous waste incineration process system, the most important thing is to deal with the acidic gas generated during the combustion process to prevent the toxic and harmful components in the flue gas from being discharged into the atmosphere. Therefore, the flue gas deacidification technology is involved. Flue gas deacidification is mainly divided into semi-dry deacidification and wet deacidification. The semi-dry deacidification reaction is located in the quenching tower. The alkaline lime slurry waste liquid is used as the reagent. After high-pressure atomization, it is sprayed into the quenching tower to cool the flue gas and deacidify. The wet deacidification is the last step of flue gas deacidification. It is divided into two stages, with liquid alkali as the absorbent to absorb the last remaining acidic gas containing sulfur, chlorine and fluorine elements in the flue gas, and the deacidification efficiency is high.

[0004] Judging from the actual production situation, in the current process flow of flue gas deacidification, the treatment cost of high-salt wastewater generated after wet deacidification with liquid alkali is relatively high. In order to reduce costs and increase efficiency, lime slurry is prepared using high-salt wastewater, and the prepared lime slurry is used for semi-dry deacidification to achieve the effect of wastewater reuse in the quenching tower. However, due to the high salt content of high-salt wastewater, scaling will occur after fusion with lime, which will affect the atomization effect of the spray gun and cause the deacidification efficiency to deteriorate. Therefore, the distilled water produced by the three-effect evaporation in the physical and chemical workshop of the factory can be combined and mixed in a certain proportion to reduce the salt content and scaling in the prepared lime slurry, thereby achieving the effect of internal waste treatment.

[0005] Therefore, the present application proposes a method for preparing lime slurry with mixed waste liquid, which uses wet high-salt wastewater combined with triple-effect distilled water to prepare lime slurry to solve the problem of high treatment cost of high-salt wastewater produced by the wet process. The steps are simple and will not result in poor atomization effect of lime slurry due to excessive salt content. The use of scale inhibitors can reduce the disposal problem of physical and chemical triple-effect distilled water, implement the concept of treating waste with waste, and save energy and protect the environment. Summary of the invention

[0006] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a method for preparing lime slurry with mixed waste liquid, which has the advantages of simple preparation, environmental protection and energy saving, and solves the problems of high treatment cost of high-salt wastewater generated by the existing wet method and poor spray gun atomization effect.

[0007] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a method for preparing lime slurry by mixing waste liquid, comprising the following steps: Step 1, the high-salt wastewater generated by the primary wet scrubber is passed into a wastewater tank for storage, and at the same time, the physical and chemical triple-effect distilled water generated by evaporation and condensation of the high-salt wastewater is stored in a pool, and the pool is connected to the lime slurry mixing tank through a pipeline; Step 2: The high-salt wastewater and the physicochemical triple-effect distilled water are both passed into a lime slurry stirring tank, and the mass percentage is monitored by a flow meter. The two are mixed to obtain mixed wastewater, and the salinity, pH value and density thereof are determined; Step 3: Add lime to the mixed wastewater to mix the two thoroughly to obtain a lime slurry solution, and measure its salinity, pH value and density.

[0008] Preferably, in step 2, the mass percentages of the high-salt wastewater and the water distilled from the physical and chemical triple-effect distillation are both 0-100%, and the mixing ratio of the high-salt wastewater and the water distilled from the physical and chemical triple-effect distillation is 5:0-0:5.

[0009] Preferably, the mass percentage of lime in step 2 is 1-3%, and the mass fraction of lime is 95%.

[0010] Preferably, the density of the mixed wastewater and the lime slurry solution is measured by a volumetric weight method, and the salinity of the mixed wastewater and the lime slurry solution is measured by a 180° C. drying weight method.

[0011] (III) Beneficial effects Compared with the prior art, the present invention provides a method for preparing lime slurry by mixing waste liquid, which has the following beneficial effects: The method for preparing lime slurry with mixed waste liquid uses wet high-salt wastewater combined with triple-effect distilled water to prepare lime slurry, solves the problem of high cost of treating high-salt wastewater produced by the wet process, has simple steps, avoids the phenomenon of spray gun structure as much as possible, ensures atomization effect, reduces the use of scale inhibitor, and at the same time, makes the physical and chemical triple-effect distilled water usable, thereby treating waste with waste, saving energy and protecting the environment. DETAILED DESCRIPTION

[0012] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] In this embodiment, a method for preparing lime slurry by mixing waste liquid includes the following steps: Step 1, the high-salt wastewater generated by the primary wet scrubber is passed into a wastewater tank for storage. At the same time, the physical and chemical triple-effect distilled water generated by evaporation and condensation of the high-salt wastewater is stored in a physical and chemical workshop pool, and the pool is connected to the lime slurry mixing tank through a pipeline; Step 2: The high-salt wastewater and the physicochemical triple-effect distilled water are both passed into a lime slurry stirring tank, and the mass percentage is monitored by a flow meter. The two are mixed to obtain mixed wastewater, and the salinity, pH value and density thereof are determined; Step 3: Add lime to the mixed wastewater to mix the two thoroughly to obtain a lime slurry solution, and measure its salinity, pH value and density.

[0014] In this embodiment, the mass percentages of high-salt wastewater and water distilled from the physical and chemical triple-effect distillation in step 2 are both 0-100%, the mixing ratio of high-salt wastewater and water distilled from the physical and chemical triple-effect distillation is 5:0-0:5, the mass percentage of lime in step 2 is 1-3%, and the mass fraction of lime is 95%.

[0015] In this embodiment, the density of the mixed wastewater and the lime slurry solution is measured by the volume weight method, and the salt content of the mixed wastewater and the lime slurry solution is measured by the 180° C. drying weight method.

[0016] Among them, salt content refers to soluble solid content, and its 180°C drying weight method is based on 5.2 of DZ / T 0064.9-2021; the mixed water samples of the mixed wastewater in step 2 are sampled and measured at irregular intervals to ensure the randomness of the measurement; the mass and volume of the mixed wastewater and the mixed lime slurry solution are measured respectively, and the density of the two is obtained by the volume weight method.

[0017] It should be noted that the high-salt wastewater is generated after primary wet deacidification, and the physicochemical triple-effect distillation water comes from the water distilled from the wastewater treated by the triple-effect evaporation in the physicochemical workshop.

[0018] Example 1 Table 1 shows the relationship between the density and pH of lime slurry and scaling time when 100% high-salt wastewater is added As shown in Table 1, 100% high-salt wastewater was added to the lime mixing tank, and the salt content and density were measured. 1%, 2%, and 3% of 95% lime were added and mixed to prepare lime slurry. The pH, density, and scaling time of the lime slurry were measured.

[0019] Example 2 Table 2 shows the relationship between the density and pH of lime slurry and scaling time when 80% high-salt wastewater and 20% physical and chemical triple-effect distilled water are added As shown in Table 2, 80% high-salt wastewater and 20% physical and chemical triple-effect distilled water were added to a lime mixing tank. After uniform mixing, the salt content and density of the mixed solution were measured. 1%, 2%, and 3% of 95% lime were added and mixed to prepare lime slurry. The pH, density, and scaling time of the lime slurry were measured.

[0020] Example 3 Table 3 shows the relationship between the density and pH of lime slurry and scaling time when 60% high-salt wastewater and 40% physical and chemical triple-effect distilled water are added. As shown in Table 3, 60% high-salt wastewater and 40% physical and chemical triple-effect distilled water were added to a lime mixing tank. After uniform mixing, the salt content and density of the mixed solution were measured. 1%, 2%, and 3% of 95% lime were added and mixed to prepare lime slurry. The pH, density, and scaling time of the lime slurry were measured.

[0021] Example 4 Table 4 shows the relationship between the density and pH of lime slurry and scaling time when 40% high-salt wastewater and 60% physical and chemical triple-effect distilled water are added As shown in Table 4, 40% high-salt wastewater and 60% physical and chemical triple-effect distilled water were added to a lime mixing tank. After uniform mixing, the salt content and density of the mixed solution were measured. 1%, 2%, and 3% of 95% lime were added and mixed to prepare lime slurry. The pH, density, and scaling time of the lime slurry were measured.

[0022] Example 5 Table 5 shows the relationship between the density and pH of lime slurry and scaling time when 20% high-salt wastewater and 80% physical and chemical triple-effect distilled water are added As shown in Table 5, 20% high-salt wastewater and 80% physical and chemical triple-effect distilled water were added to a lime mixing tank. After uniform mixing, the salt content and density of the mixed solution were measured. 1%, 2%, and 3% of 95% lime were added and mixed to prepare lime slurry. The pH, density, and scaling time of the lime slurry were measured.

[0023] Example 6 Table 6 shows the relationship between the density and pH of lime slurry and scaling time when 100% physical and chemical triple-effect distilled water is added As shown in Table 6, 100% physical and chemical triple-effect distilled water was added to a lime mixing tank, and 1%, 2%, and 3% of 95% lime were added. The mixture was mixed to prepare lime slurry, and the pH, density, and scaling time were measured.

[0024] In summary, when 1% lime is added by mass fraction, the alkalinity requirement of the lime slurry cannot be met in Examples 1, 2, 3, 4, and 5; when 2% lime is added, Examples 4 and 5 meet the alkalinity requirement of the lime slurry, and no scaling or pipe clogging occurs; when 3% lime is added, Examples 2, 3, 4, and 5 all meet the requirements, but the lime slurry will coagulate, scale, and block the pipe within a short time.

[0025] Therefore, the higher the proportion of high-salt water in the lime slurry, the more obvious the scaling phenomenon of the lime slurry. Therefore, it can be judged that adding 2% lime to prepare the lime slurry in Example 4 is the optimal condition to ensure the atomization effect of the spray gun. At the same time, it can quickly consume the physical and chemical triple-effect distilled water, treat high-salt wastewater, reduce the cost of waste gas treatment, treat waste with waste, and save energy and protect the environment.

[0026] It should be noted that according to the density of lime slurry before and after adding, it can be judged that for every 1% increase in lime concentration, the density of lime slurry can increase by 0.004-0.005kg / cm 3 , the lime slurry concentration can be determined in real time.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing lime slurry by mixing waste liquid, characterized in that: The following steps are involved: Step 1, the high-salt wastewater generated by the primary wet scrubber is passed into a wastewater tank for storage, and at the same time, the physical and chemical triple-effect distilled water generated by evaporation and condensation of the high-salt wastewater is stored in a pool, and the pool is connected to the lime slurry mixing tank through a pipeline; Step 2: The high-salt wastewater and the physicochemical triple-effect distilled water are both passed into a lime slurry stirring tank, and the mass percentage is monitored by a flow meter. The two are mixed to obtain mixed wastewater, and the salinity, pH value and density thereof are determined; Step 3: Add lime to the mixed wastewater to mix the two thoroughly to obtain a lime slurry solution, and measure its salinity, pH value and density.

2. The method for preparing lime slurry from mixed waste liquid according to claim 1, characterized in that: In the step 2, the mass percentages of the high-salt wastewater and the water distilled from the physical and chemical triple effect are both 0-100%, and the mixing ratio of the high-salt wastewater and the water distilled from the physical and chemical triple effect is 5:0-0:

5.

3. The method for preparing lime slurry from mixed waste liquid according to claim 1, characterized in that: The mass percentage of lime in step 2 is 1-3%, and the mass fraction of lime is 95%.

4. The method for preparing lime slurry from mixed waste liquid according to claim 1, characterized in that: The density of the mixed wastewater and the lime slurry solution is measured by a volumetric weight method, and the salt content of the mixed wastewater and the lime slurry solution is measured by a 180° C. drying weight method.

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