Alkali liquor spraying system for producing ethyl chloroformate

Abstract

The invention relates to the technical field of spraying systems, in particular to an alkali liquor spraying system for producing ethyl chloroformate, which comprises the following steps: S1, adding tetramethylammonium hydroxide into water, heating to room temperature, stirring until the tetramethylammonium hydroxide is completely dissolved, adding modified sodium metasilicate, ethylenediamine tetraacetic acid disodium salt and sodium lignin sulfonate, controlling the temperature, stirring, and filtering to obtain a solution A; alkali liquor is obtained; s2, turning on a power supply of the control system, ensuring normal operation of the control system, setting operation parameters of a spraying system, starting an alkali liquor pump, pumping alkali liquor out of the storage tank, conveying the alkali liquor to a spraying head through a pipeline, adjusting the output flow of the pump, starting intermittent and uniform spraying of the alkali liquor, and enabling sprayed waste liquor to flow into a precipitation tank through a pipeline for post-treatment. According to the alkali liquor spraying system, the purification efficiency of acid gas, heavy metal ions and organic pollutants in waste gas can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemical industry, in particular to an alkali solution spraying system for producing ethyl chloroformate. Background Art

[0002] Ethyl chloroformate is an important organic chemical raw material with the chemical formula C3H5ClO2. It is a colorless, transparent liquid with a pungent smell. Ethyl chloroformate is widely used in the fields of pesticides, medicines, spices and synthetic resins. With the rapid development of related industries, its market demand is growing year by year. In the production process of ethyl chloroformate, a certain amount of waste gas will be generated, which may contain pollutants such as sulfide and carbon dioxide. In order to effectively control and reduce the emission of these pollutants, the alkali spray system is widely used in the waste gas treatment process of ethyl chloroformate production. The working principle of the alkali spray system is to use alkaline liquid to spray into the exhaust gas pipeline, and the alkali liquid reacts chemically with the pollutants in the exhaust gas to convert them into salt substances that are difficult to volatilize, thereby reducing the concentration of pollutants in the exhaust gas and achieving the purpose of purifying the exhaust gas.

[0003] In the prior art, the alkali solution spraying system has the problem of uneven spraying, which causes some exhaust gas to fail to fully contact with the alkali solution, thus affecting the purification effect. In addition, the liquid-to-gas ratio of the spraying system is relatively low, and it may not be able to fully absorb the pollutants in the exhaust gas, especially when the exhaust gas concentration is high or the flow rate is large, the purification efficiency may be significantly reduced. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides an alkali solution spraying system for producing ethyl chloroformate.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A lye spraying system for producing ethyl chloroformate comprises the following steps:

[0007] S1. Add tetramethylammonium hydroxide to water, heat to room temperature, stir until completely dissolved, add modified sodium metasilicate, disodium ethylenediaminetetraacetate and sodium lignin sulfonate, control the temperature, stir for 30-60 minutes, and filter with a 0.45 μm filter to obtain an alkali solution;

[0008] S2. Turn on the power of the control system to ensure the normal operation of the control system, set the operating parameters of the spray system, start the alkali solution pump, extract the alkali solution from the storage tank, transport it to the spray head through the pipeline, adjust the output flow of the pump, and start intermittent and uniform spraying of the alkali solution. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0009] Furthermore, in step S1, the mass ratio of tetramethylammonium hydroxide, water, modified sodium metasilicate, disodium ethylenediaminetetraacetate and sodium lignin sulfonate is (2-3):1000:(1-1.5):(0.3-0.5):(0.2-0.3).

[0010] Furthermore, in step S1, the temperature is controlled to be 40-50° C. and the stirring speed is 50-100 rpm.

[0011] Furthermore, the modified sodium metasilicate in step S1 is prepared by the following steps:

[0012] Add sodium metasilicate into water, heat to 55-60°C, stir until completely dissolved, add acrylic acid, continue stirring for 30-40 minutes, add ammonium persulfate, adjust the pH value to 7-8, maintain 55-60°C in a constant temperature water bath, react for 4-6 hours, filter and wash after the reaction is completed to obtain modified sodium metasilicate.

[0013] Furthermore, the operating parameters of the spray system in step S2 are specifically as follows: the spray flow rate of the alkali solution is 20-30 L / min, and the pressure of the spray system is 0.3-0.4 MPa.

[0014] Furthermore, in step S2, the output flow rate of the pump is 25-28 L / min.

[0015] Furthermore, the intermittent mode in step S2 is specifically as follows: the duration of each spraying is 10-15 minutes, and the interval time between two sprayings is 5 minutes.

[0016] Furthermore, the mass ratio of sodium metasilicate, water, acrylic acid and ammonium persulfate is (10-12):50:(2-4):(0.08-0.1).

[0017] Beneficial effects of the present invention:

[0018] 1. In the technical solution of the present invention, the alkali solution is composed of tetramethylammonium hydroxide (TMAH), water, modified sodium metasilicate, disodium ethylenediaminetetraacetate (EDTA-2Na) and sodium lignin sulfonate to form a stable suspension or solution. TMAH is completely ionized into tetramethylammonium ions and hydroxide ions in water, which serve as the main active ingredients of the neutralization reaction. The modified sodium metasilicate introduces carboxyl and hydroxyl groups through acrylic acid polymerization, which enhances its chelating ability and dispersing properties. EDTA-2Na forms a stable complex with metal ions with its strong chelating ability. Sodium lignin sulfonate, as a natural polymer surfactant, provides good dispersibility and wettability.

[0019] 2. In the technical solution of the present invention, the hydroxide ions provided by TMAH make the alkali solution have efficient neutralization ability, which can quickly react with the acidic substances in the exhaust gas to generate salt and water, thereby effectively reducing the concentration of acidic substances in the exhaust gas. Secondly, the strong chelating ability of EDTA-2Na ensures that the heavy metal ions in the exhaust gas can be effectively removed to form a stable complex to prevent them from accumulating in the environment. Furthermore, the functional groups such as carboxyl and hydroxyl groups of modified sodium metasilicate and sodium lignin sulfonate give the alkali solution excellent dispersibility and adsorption properties, which can transfer organic pollutants in the exhaust gas from the gas phase to the liquid phase and fix them on the surface of the alkali solution by adsorption. Finally, the synergistic effect between the components further improves the purification efficiency of the alkali solution. The neutralization reaction of TMAH creates favorable conditions for the adsorption and complexation of other components, and the removal of heavy metal ions by EDTA-2Na reduces interference with other components. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0021] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0022] Preparation Example 1

[0023] The modified sodium metasilicate is prepared by the following steps:

[0024] Add 10 kg of sodium metasilicate into 50 kg of water, heat to 55°C, stir until completely dissolved, add 2 kg of acrylic acid, continue stirring for 30 min, add 0.08 kg of ammonium persulfate, adjust the pH value to 7, maintain 55°C in a constant temperature water bath, react for 4 hours, and after the reaction is completed, filter and wash to obtain modified sodium metasilicate.

[0025] Preparation Example 2

[0026] The modified sodium metasilicate is prepared by the following steps:

[0027] Add 11 kg of sodium metasilicate into 50 kg of water, heat to 58°C, stir until completely dissolved, add 3 kg of acrylic acid, continue stirring for 35 min, add 0.09 kg of ammonium persulfate, adjust the pH value to 7.5, maintain 58°C in a constant temperature water bath, react for 5 h, filter and wash after the reaction to obtain modified sodium metasilicate.

[0028] Preparation Example 3

[0029] The modified sodium metasilicate is prepared by the following steps:

[0030] Add 12 kg of sodium metasilicate into 50 kg of water, heat to 60°C, stir until completely dissolved, add 4 kg of acrylic acid, continue stirring for 40 min, add 0.1 kg of ammonium persulfate, adjust the pH value to 8, maintain 60°C in a constant temperature water bath, react for 6 hours, filter and wash after the reaction to obtain modified sodium metasilicate.

[0031] Example 1

[0032] A lye spraying system for producing ethyl chloroformate comprises the following steps:

[0033] S1, add 2kg of tetramethylammonium hydroxide to 1000kg of water, heat to room temperature, stir until completely dissolved, add 1kg of modified sodium metasilicate prepared in Preparation Example 1, 0.3kg of disodium ethylenediaminetetraacetate and 0.2kg of sodium lignin sulfonate, control the temperature to 40°C, stir at a speed of 50rpm for 30min, filter with a 0.45μm filter to obtain an alkali solution;

[0034] S2. Turn on the power of the control system to ensure the normal operation of the control system, set the operating parameters of the spray system, the spray flow rate of the alkali solution is 20-30L / min, the pressure of the spray system is 0.3MPa, start the alkali solution pump, extract the alkali solution from the storage tank, and transport it to the spray head through the pipeline. Adjust the output flow rate of the pump to 25L / min, and start intermittent and uniform spraying of the alkali solution. The duration of each spray is 10min, and the interval time between two sprays is 5min. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0035] Example 2

[0036] A lye spraying system for producing ethyl chloroformate comprises the following steps:

[0037] S1, add 2.2kg of tetramethylammonium hydroxide to 1000kg of water, heat to room temperature, stir until completely dissolved, add 1.1kg of modified sodium metasilicate obtained in Preparation Example 2, 0.32kg of disodium ethylenediaminetetraacetate and 0.22kg of sodium lignin sulfonate, control the temperature to 42°C, stir at a speed of 50rpm for 35min, filter with a 0.45μm filter to obtain alkali solution;

[0038] S2. Turn on the power of the control system to ensure the normal operation of the control system, set the operating parameters of the spray system, the spray flow rate of the alkali solution is 22L / min, the pressure of the spray system is 0.31MPa, start the alkali solution pump, extract the alkali solution from the storage tank, and transport it to the spray head through the pipeline. Adjust the output flow rate of the pump to 25.5L / min, and start intermittent and uniform spraying of the alkali solution. The duration of each spray is 12min, and the interval time between two sprays is 5min. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0039] Example 3

[0040] A lye spraying system for producing ethyl chloroformate comprises the following steps:

[0041] S1, add 2.5kg of tetramethylammonium hydroxide to 1000kg of water, heat to room temperature, stir until completely dissolved, add 1.2kg of modified sodium metasilicate prepared in Preparation Example 3, 0.34kg of disodium ethylenediaminetetraacetate and 0.23kg of sodium lignin sulfonate, control the temperature to 45°C, stir at a speed of 60rpm for 40min, filter with a 0.45μm filter to obtain an alkali solution;

[0042] S2. Turn on the power of the control system to ensure the normal operation of the control system, set the operating parameters of the spray system, the spray flow rate of the alkali solution is 25L / min, the pressure of the spray system is 0.34MPa, start the alkali solution pump, extract the alkali solution from the storage tank, and transport it to the spray head through the pipeline. Adjust the output flow rate of the pump to 26L / min, and start intermittent and uniform spraying of the alkali solution. The duration of each spray is 13min, and the interval time between two sprays is 5min. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0043] Example 4

[0044] A lye spraying system for producing ethyl chloroformate comprises the following steps:

[0045] S1, add 2.6kg of tetramethylammonium hydroxide to 1000kg of water, heat to room temperature, stir until completely dissolved, add 1.4kg of modified sodium metasilicate prepared in Preparation Example 1, 0.4kg of disodium ethylenediaminetetraacetate and 0.28kg of sodium lignin sulfonate, control the temperature to 45°C, stir at a speed of 80rpm for 45min, filter with a 0.45μm filter to obtain an alkali solution;

[0046] S2. Turn on the power of the control system to ensure the normal operation of the control system, set the operating parameters of the spray system, the spray flow rate of the alkali solution is 25L / min, the pressure of the spray system is 0.37MPa, start the alkali solution pump, extract the alkali solution from the storage tank, and transport it to the spray head through the pipeline. Adjust the output flow rate of the pump to 27L / min, and start intermittent and uniform spraying of the alkali solution. The duration of each spray is 14min, and the interval time between two sprays is 5min. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0047] Example 5

[0048] A lye spraying system for producing ethyl chloroformate comprises the following steps:

[0049] S1, add 3kg of tetramethylammonium hydroxide to 1000kg of water, heat to room temperature, stir until completely dissolved, add 1.5kg of modified sodium metasilicate prepared in Preparation Example 2, 0.5kg of disodium ethylenediaminetetraacetate and 0.3kg of sodium lignin sulfonate, control the temperature to 50°C, stir at a speed of 100rpm for 60min, filter with a 0.45μm filter to obtain an alkali solution;

[0050] S2. Turn on the power of the control system to ensure the normal operation of the control system, set the operating parameters of the spray system, the spray flow rate of the alkali solution is 30L / min, the pressure of the spray system is 0.4MPa, start the alkali solution pump, extract the alkali solution from the storage tank, and transport it to the spray head through the pipeline. Adjust the output flow rate of the pump to 28L / min, and start intermittent and uniform spraying of the alkali solution. The duration of each spray is 15min, and the interval time between two sprays is 5min. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that tetramethylammonium hydroxide is not added, and the remaining steps are the same as those in Example 1.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 2 is that modified sodium metasilicate is not added, and the remaining steps are the same as those in Example 2.

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 3 is that disodium ethylenediaminetetraacetate is not added, and the remaining steps are the same as those in Example 3.

[0057] Comparative Example 4

[0058] The difference between this comparative example and Example 4 is that sodium lignin sulfonate is not added, and the remaining steps are the same as those of Example 4.

[0059] Comparative Example 5

[0060] The difference between this comparative example and Example 5 is that 30% sodium hydroxide solution is used instead of alkali solution, and the remaining steps are the same as those in Example 5.

[0061] Chemical analysis methods were used to determine the concentrations of acidic gases, heavy metal ions, and organic pollutants in the waste gas before and after treatment in Examples 1-5 and Comparative Examples 1-5. A gas chromatograph was used to determine the acidic gas concentration. An atomic absorption spectrometer was used to determine the heavy metal ion concentration. A high performance liquid chromatograph was used to determine the organic pollutant concentration. The purification efficiency of each embodiment and comparative example was calculated, purification efficiency = (concentration before treatment - concentration after treatment) / concentration before treatment × 100%. The results are shown in Table 1:

[0062] Table 1. Purification efficiency results of Examples 1-5 and Comparative Examples 1-5

[0063]

[0064]

[0065] As can be seen from Table 1, the acidic gas purification efficiency of Examples 1-5 is generally high, all above 90%. This may be due to the synergistic effect of tetramethylammonium hydroxide and modified sodium metasilicate in the alkali solution. Tetramethylammonium hydroxide is a strong base that can effectively neutralize acidic gases, while modified sodium metasilicate may increase the adsorption and reaction capacity of alkali solution to acidic gases through its special chemical structure. In Comparative Example 1, tetramethylammonium hydroxide is not added, and the purification efficiency decreases (85.7%). This shows that tetramethylammonium hydroxide has a significant neutralizing effect on acidic gases in an alkaline system. In Comparative Example 2, modified sodium metasilicate is not added, and the purification efficiency also decreases (87.4%). This shows that modified sodium metasilicate plays an important role in enhancing the purification capacity of alkali solution to acidic gases. Although the purification efficiency of Comparative Examples 3-5 is slightly lower than that of the embodiment, they are all higher than Comparative Examples 1 and 2, indicating that components such as disodium ethylenediaminetetraacetate and sodium lignin sulfonate also contribute to the purification of acidic gases to a certain extent, but not as significant as tetramethylammonium hydroxide and modified sodium metasilicate.

[0066] The heavy metal ion purification efficiency of Examples 1-5 is relatively high, and with the increase in the amount of modified sodium metasilicate (Examples 1-5), the purification efficiency has a slight upward trend, which may be because the special structure of modified sodium metasilicate has a strong adsorption capacity for heavy metal ions. In Comparative Example 2, modified sodium metasilicate is not added, and the purification efficiency is significantly reduced (81.2%), indicating that modified sodium metasilicate plays a key role in the purification of heavy metal ions. Although the purification efficiency of other comparative examples is slightly lower than that of the examples, they are all higher than that of Comparative Example 2, indicating that ingredients such as tetramethylammonium hydroxide, disodium ethylenediaminetetraacetic acid, and sodium lignin sulfonate also contribute to the purification of heavy metal ions.

[0067] The purification efficiency of organic pollutants in Examples 1-5 increases with the increase in the amount of modified sodium metasilicate used, especially in Example 4, where it reaches the highest (84.7%). This may be because modified sodium metasilicate not only has a purification effect on acidic gases and heavy metal ions, but also has a certain adsorption or degradation ability for organic pollutants. In Comparative Example 4, no sodium lignin sulfonate is added, and the purification efficiency decreases (77.1%). Sodium lignin sulfonate may enhance the dispersion and degradation ability of alkali solution on organic pollutants through its surface activity. Comparative Example 5 uses 30% sodium hydroxide solution instead of alkali solution, and the purification efficiency is the lowest (70.9%). This shows that the alkali solution designed in this experiment is significantly better than a single strong alkali solution in purifying organic pollutants.

[0068] In summary, the alkali solution spraying system of Examples 1-5 can significantly improve the purification efficiency of acidic gases, heavy metal ions and organic pollutants in waste gas.

[0069] In the description of the specification, the description with reference to the terms "embodiment", "various embodiments" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or preparation example are included in at least one embodiment or preparation example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or preparation example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or preparation examples in a suitable manner.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An alkali solution spraying system for producing ethyl chloroformate, characterized in that: The following steps are involved: S1. Add tetramethylammonium hydroxide to water, heat to room temperature, stir until completely dissolved, add modified sodium metasilicate, disodium ethylenediaminetetraacetate and sodium lignin sulfonate, control the temperature, stir for 30-60 minutes, and filter with a 0.45 μm filter to obtain an alkali solution; S2. Start the alkali solution pump, extract the alkali solution from the storage tank, transport it to the spray head through the pipeline, adjust the output flow of the pump, and start to spray the alkali solution intermittently and evenly. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

2. A lye spray system for producing ethyl chloroformate according to claim 1, characterized in that: In step S1, the mass ratio of tetramethylammonium hydroxide, water, modified sodium metasilicate, disodium ethylenediaminetetraacetate and sodium lignin sulfonate is (2-3):1000:(1-1.5):(0.3-0.5):(0.2-0.3).

3. A lye spray system for producing ethyl chloroformate according to claim 1, characterized in that: In step S1, the temperature is controlled to be 40-50° C. and the stirring speed is 50-100 rpm.

4. A lye spray system for producing ethyl chloroformate according to claim 1, characterized in that: The modified sodium metasilicate in step S1 is prepared by the following steps: Add sodium metasilicate into water, heat to 55-60°C, stir until completely dissolved, add acrylic acid, continue stirring for 30-40 minutes, add ammonium persulfate, adjust the pH value to 7-8, maintain 55-60°C in a constant temperature water bath, react for 4-6 hours, filter and wash after the reaction is completed to obtain modified sodium metasilicate.

5. A lye spray system for producing ethyl chloroformate according to claim 1, characterized in that: The specific operating parameters of the spray system in step S2 are: the spray flow rate of the alkali solution is 20-30 L / min, and the pressure of the spray system is 0.3-0.4 MPa.

6. A alkali solution spraying system for producing ethyl chloroformate according to claim 1, characterized in that: The output flow rate of the pump in step S2 is 25-28 L / min.

7. A lye spray system for producing ethyl chloroformate according to claim 1, characterized in that: The intermittent method in step S2 specifically includes: the duration of each spraying is 10-15 minutes, and the interval time between two sprayings is 5 minutes.

8. A alkali solution spraying system for producing ethyl chloroformate according to claim 4, characterized in that: The mass ratio of sodium metasilicate, water, acrylic acid and ammonium persulfate is (10-12):50:(2-4):(0.08-0.1).

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