Adblue production process capable of effectively removing dirt of exhaust pipe

Abstract

The invention discloses an adblue production process capable of effectively removing dirt of an exhaust pipe. The adblue production process comprises the following steps: step 1, selection and culture of a biocatalyst; 2, pretreating a urea raw material; step 3, construction of a reaction system; step 4, implementation of urea synthesis; 5, separating and purifying a product; and 6, recycling waste and closing a system loop. The biocatalyst urease is used for urea synthesis, the reaction efficiency can be remarkably improved under the relatively mild condition, generation of by-products is reduced, the effectiveness of urea in an SCR system is ensured, and the application effect of urea in a diesel engine is improved; by adopting a biological catalysis process and an environment-friendly stabilizer, the stability of the urea solution is remarkably improved, and degradation and crystallization of urea in a high-temperature environment are reduced. The formation of sediments in the exhaust pipe is effectively reduced, and the maintenance and cleaning frequency is reduced, so that the overall efficiency of an exhaust system is improved, and the service life of the exhaust system is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle urea production, and particularly to a vehicle urea production process for effectively removing dirt from the exhaust pipe. Background Technique

[0002] With the improvement of environmental protection awareness and the strictness of vehicle emission regulations, the vehicle urea (selective catalytic reduction, SCR) technology has been widely applied in diesel engines. The urea solution can effectively reduce harmful emissions by reacting with nitrogen oxides in the exhaust gas. However, long-term use will cause urea to deposit in the exhaust pipe, forming dirt, which will affect the efficiency of the exhaust system and the performance of the engine. Currently, the main component of vehicle urea is a mixed solution of high-purity urea and deionized water, and its production process includes steps such as urea synthesis, dissolution, filtration, and filling. However, the traditional production process has problems such as insufficient urea purity, high production cost, and environmental impact. The dirt in the exhaust pipe is mainly caused by factors such as urea solution degradation, impurities in low-quality fuels, and exhaust gas temperature and flow rate. Therefore, there is an urgent need to improve the vehicle urea production process to improve the purity of urea, reduce production costs, and reduce environmental impact, while effectively preventing urea from depositing in the exhaust system, thereby reducing the formation of dirt in the exhaust pipe. Future research and development can focus on improving urea synthesis technology, optimizing the dissolution and filtration processes, introducing specific additives, and adopting environmentally friendly production methods, etc., to promote the development of more environmentally friendly, economical, and effective vehicle emission control technologies.

[0003] However, there are still significant deficiencies in the existing technologies, such as: In the traditional vehicle urea production process, the use of chemical catalysts often results in low synthesis efficiency of urea and low purity of the final product. Due to limitations of reaction conditions such as temperature and reaction time, various by-products may be generated, affecting the quality of urea. In addition, urea is easily affected by impurities during the reaction process, resulting in more non-urea components in the final product, affecting its effectiveness in the diesel engine SCR (selective catalytic reduction) system. At the same time, the degradation and instability of the urea solution will cause deposits to form in the exhaust pipe. These deposits not only affect the efficiency of the exhaust system, but may also lead to a decline in engine performance and excessive emissions. Urea is easily decomposed in a high-temperature environment, forming crystals and precipitates, increasing the maintenance and cleaning costs of the exhaust pipe. Summary of the Invention

[0004] The purpose of the present invention is to provide a vehicle urea production process for effectively removing dirt from the exhaust pipe to solve the problems raised in the above background technique.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A vehicle urea production process for effectively removing dirt from the exhaust pipe, comprising the following steps: Step 1: Selection and Cultivation of Biocatalyst; Step 2: Pretreatment of Urea Raw Materials; Step 3: Setup of Reaction System; Step 4: Implementation of Urea Synthesis; Step 5: Separation and Purification of Products; Step 6: Waste Recycling and System Closed-loop.

[0006] Preferably, the said Step 1: Selection and Cultivation of Biocatalyst specifically includes: Select urease as the biocatalyst: Urease can catalyze the synthesis of urea, and it has a wide range of sources and is easy to obtain.

[0007] Cultivate urease: In a medium containing urea, ammonia water and mineral salts, carry out fermentation culture of urease, control the temperature at 30 - 37 °C, adjust the pH value to 6.5 - 7.5 to promote the efficient expression of urease, and the culture time is 48 hours.

[0008] Preferably, the said Step 2: Pretreatment of Urea Raw Materials specifically includes: Raw material selection: Select ammonia water and carbon dioxide as the main raw materials for urea.

[0009] Pretreatment of raw materials: Filter ammonia water to remove impurities and ensure the purity of raw materials. Dehydrate carbon dioxide to remove moisture and ensure the dryness of the gas during the reaction.

[0010] Preferably, the said Step 3: Setup of Reaction System specifically includes: Reactor selection: Select a stainless-steel reactor with a volume of not less than 500 liters, equipped with a temperature control system and a stirring device.

[0011] Reaction condition setting: Introduce urease into the reactor, set the temperature at 35 °C, the pH value at 7.0, and ensure uniform reaction by adjusting the stirring speed.

[0012] Preferably, the said Step 4: Implementation of Urea Synthesis specifically includes: Simultaneous feeding: Simultaneously feed the pretreated ammonia water and carbon dioxide into the reactor, maintaining the reaction ratio of ammonia water: carbon dioxide = 2:1 to optimize the reaction efficiency.

[0013] Reaction time control: The reaction lasts for 2 hours, and samples are taken regularly to detect the urea concentration to ensure that the reaction reaches at least 90% or more of the predetermined urea output.

[0014] Preferably, the said Step 5: Separation and Purification of Products specifically includes: Post-reaction treatment: After the reaction is completed, transfer the reaction mixture to a separation system and cool it down to 20 °C using a cooling system to reduce subsequent energy consumption.

[0015] Product separation: Separate the urease and unreacted raw materials by a centrifuge and collect the urea solution.

[0016] Urea purification: Subject the collected urea solution to multi-stage filtration and evaporation using a vacuum evaporator to remove water and small molecule impurities, and finally obtain the urea solution.

[0017] Preferably, Step 6: Waste recycling and system closed-loop specifically includes: Waste treatment: Recycle the separated urease and unreacted raw materials, and reintroduce the unreacted ammonia water and carbon dioxide into the reactor using special facilities to achieve efficient utilization of resources.

[0018] Environmentally friendly additive: Add a biodegradable stabilizer to the urea solution to improve the stability of urea in the exhaust pipe and reduce the formation of deposits.

[0019] Preferably, the stabilizer is a mixture of aloe extract, tea polyphenols, sodium alginate, gelatin, and citric acid.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. Using the biocatalyst urease for urea synthesis can significantly improve the reaction efficiency under relatively mild conditions and reduce the generation of by-products, which ensures the effectiveness of urea in the SCR system and improves its application effect in diesel engines; 2. By adopting a biocatalytic process and an environmentally friendly stabilizer, this solution significantly improves the stability of the urea solution and reduces the degradation and crystallization of urea in a high-temperature environment. This effectively reduces the formation of deposits inside the exhaust pipe, reduces the maintenance and cleaning frequency, and thus improves the overall efficiency and service life of the exhaust system; 3. This solution realizes the efficient recycling of raw materials by constructing a closed-loop production system, reduces resource waste. During the production process, using a biocatalyst not only reduces the dependence on chemical catalysts but also reduces the energy consumption and waste emissions required for production, meets modern environmental protection requirements, and improves the sustainability of the overall production. Description of the drawings

[0021] Figure 1 It is a schematic flow diagram of the present invention. Detailed implementation manners

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Please refer to Figure 1 , the present invention provides a technical solution: A vehicle urea production process for effectively removing dirt from the exhaust pipe, comprising the following steps: Step 1: Selection and cultivation of biocatalyst; Step 2: Pretreatment of urea raw materials; Step 3: Construction of the reaction system; Step 4: Implementation of urea synthesis; Step 5: Separation and purification of products Step 6: Waste recycling and system closed-loop.

[0024] Step 1: Selection and cultivation of biocatalyst, specifically including: Select urease as the biocatalyst: Urease can catalyze the synthesis of urea, and it has a wide range of sources and is easy to obtain.

[0025] The advantages of selecting urease as the biocatalyst are: Mild catalytic conditions: Urease can effectively catalyze the synthesis of urea under relatively mild conditions, i.e., 30 - 37 °C, avoiding the need for high temperature and high pressure, thereby reducing energy consumption and equipment costs.

[0026] Wide sources: Urease can be extracted from a variety of microorganisms such as Escherichia coli and thermophilic bacteria, is relatively easy to obtain, and has high biological safety.

[0027] High catalytic efficiency: Urease can efficiently convert ammonia and carbon dioxide into urea, with high reaction selectivity, reducing the generation of by-products, thereby improving the purity of urea.

[0028] Cultivate urease: In a medium containing urea, ammonia water, and mineral salts, ferment and cultivate urease, control the temperature at 30 - 37 °C, adjust the pH value to 6.5 - 7.5 to promote the efficient expression of urease, and the cultivation time is 48 hours.

[0029] Preparation of the medium: Prepare the medium: Prepare a medium containing ammonia water (0.5%), urea (1%), phosphate buffer solution (pH 7.0), and appropriate mineral salts such as MgSO 4 , CaCl 2 as the nutrient source for microbial growth.

[0030] Sterilization: Subject the culture medium to autoclaving at 121°C for no less than 15 minutes to ensure aseptic conditions.

[0031] Inoculation and Cultivation: Inoculation: Inoculate the sterilized culture medium with microorganisms from the source of urease, with an inoculation amount of 5% of the volume of the culture medium. For example, inoculate 5 ml into 100 ml of the culture medium.

[0032] Cultivation Conditions: Place the culture flask in a constant temperature shaker, set the temperature to 30°C, and the shaking speed to 200 rpm to ensure uniform cultivation.

[0033] Monitor Growth: Monitor the growth of microorganisms every 6 hours using a spectrophotometer (OD600) until the OD600 value reaches 0.6 - 0.8.

[0034] Extraction of Urease: Centrifugal Separation: After the cultivation is completed, transfer the culture solution to a centrifuge, set the rotation speed to 4000 rpm, and centrifuge for 10 minutes to separate the cell precipitate and the culture medium.

[0035] Urease Collection: Collect the urease dissolved in the supernatant and perform further purification operations (such as dialysis) to remove impurities.

[0036] Compared with traditional chemical catalysts, the reaction catalyzed by urease proceeds at room temperature, significantly reducing the energy consumption and equipment costs during the production process. Using a biocatalyst means fewer chemical reagents and by-products, conforming to the concept of green chemistry, reducing the impact on the environment. By selecting and cultivating highly efficient biocatalysts, the efficiency of the urea synthesis process can be ensured. The use of urease not only increases the synthesis rate of urea but also helps to reduce the reaction time and cost, and improve the utilization rate of resources throughout the production process.

[0037] Step 2: Pretreatment of Urea Raw Materials, specifically including: Raw Material Selection: Select ammonia water and carbon dioxide as the main raw materials for urea.

[0038] Pretreatment of Raw Materials: Filter the ammonia water to remove impurities and ensure the purity of the raw materials. Dehydrate the carbon dioxide to remove moisture and ensure the dryness of the gas during the reaction.

[0039] Select high-purity ammonia water and carbon dioxide. Select ammonia water with a concentration higher than 99% to ensure the purity of ammonia and reduce the interference of impurities in the reaction. Select purified industrial-grade carbon dioxide with a purity of over 99.9% to ensure the efficiency of the reaction and the quality of the reaction products.

[0040] Pretreatment of Ammonia Water: Filter the ammonia water using a 0.22-micron filter membrane to remove possible solid impurities and particles. Monitor the pH value of the filtered ammonia water to ensure it remains within the required range, usually 11 - 12.

[0041] Removal of volatiles: In a well-ventilated environment, gently heat the ammonia water to no more than 35 °C to remove volatile impurities and ensure the purity of the ammonia water.

[0042] Pretreatment of carbon dioxide: Dehydration treatment: Use desiccants such as molecular sieves or calcium chloride to dehydrate carbon dioxide, ensuring that the desiccant has strong moisture absorption capacity to remove moisture in the carbon dioxide.

[0043] Ensure that the dehydrated carbon dioxide is moisture-free, and verify through a gas analyzer whether its humidity content is lower than the specified standard, such as less than 50 ppm.

[0044] Gas filtration: Use activated carbon or other appropriate filtering materials to filter carbon dioxide gas to remove possible odors and impurities to ensure the purity of the gas.

[0045] By selecting high-purity ammonia water and dehydrated carbon dioxide, the interference of impurities during the reaction can be significantly reduced, thereby improving the yield and purity of urea. The removal of impurities can ensure that the reaction proceeds under optimal conditions, reduce the reaction time, reduce waste of resources, and improve the overall production efficiency. Through effective pretreatment, it can ensure the stability of ammonia water and carbon dioxide during the reaction, reduce reaction fluctuations, and enhance the reliability of urea synthesis.

[0046] Step three: Setup of the reaction system, specifically including: Selection of the reactor: Select a stainless-steel reactor with a volume of not less than 500 liters, equipped with a temperature control system and a stirring device.

[0047] Setting of reaction conditions: Introduce urease into the reactor, set the temperature at 35 °C and the pH value at 7.0, and ensure uniform reaction by adjusting the stirring speed.

[0048] Select a 500-liter stainless-steel reactor, which is suitable for large-scale production and can meet the daily urea production demand. Stainless steel has good corrosion resistance and mechanical strength, and can withstand the chemical substances and pressure that may be generated during the reaction. Configure an efficient temperature control device such as a water bath or a heat exchanger to ensure that the reaction temperature is stable at 35 °C, improving the controllability of the reaction. Equip an adjustable-speed stirrer to ensure full mixing of the reactants and promote uniform reaction; Add the cultured urease solution to the reactor, ensuring that the concentration of urease is appropriate to achieve the best catalytic effect. Adjust the temperature of the reactor to 35°C, which is the optimal working temperature of urease and can improve its catalytic activity. Use a pH meter to monitor the pH value of the reaction mixture, with the target set at 7.0, and adjust it using a buffer such as phosphate buffer to maintain the stability of the reaction environment. Set the stirring speed to 150 rpm to ensure the uniform distribution of reactants, enhance the contact between ammonia, carbon dioxide and urease, and increase the reaction rate. Through precise temperature control and pH adjustment, it can be ensured that urease works under optimal conditions, thereby improving the synthesis efficiency and quality of urea. An effective stirring system ensures the uniform mixing of reactants, avoids too fast or too slow local reactions, and increases the overall reaction rate.

[0049] Step 4: Implementation of urea synthesis, specifically including: Simultaneous feeding: Pre-treated ammonia water and carbon dioxide are simultaneously fed into the reactor, maintaining a reaction ratio of ammonia water: carbon dioxide = 2:1 to optimize the reaction efficiency.

[0050] Reaction time control: The reaction lasts for 2 hours, and samples are taken regularly to detect the urea concentration to ensure that the reaction reaches the predetermined urea yield, at least over 90%.

[0051] Ensure that before feeding, ammonia water and carbon dioxide are pretreated through the above steps to reach the required high purity. Ammonia water and carbon dioxide are simultaneously fed into the reactor, ensuring that the feeding is carried out according to the specified ratio of ammonia water: carbon dioxide = 2:1. This ratio optimization design is based on the reaction mechanism to ensure that ammonia and carbon dioxide react fully in the reaction and maximize the urea yield. The entire reaction process lasts for 2 hours to ensure that urea synthesis is maximized within this time. Samples are taken from the reactor every 30 minutes, and the concentration of urea is detected using spectrophotometry or other analytical methods to ensure the reaction process. According to the sampling data, the generation of urea is monitored in real time, and reaction conditions such as stirring speed and temperature are adjusted to ensure the effectiveness of the reaction. The method of simultaneous feeding can ensure that the reactants are fully mixed and reacted in the shortest time, reduce the reaction time, and increase the urea production rate. Through precise feeding ratio and real-time monitoring, ammonia water and carbon dioxide can be utilized to the maximum extent, reducing the waste and cost of raw materials. The real-time feedback mechanism for monitoring the urea concentration ensures that the reaction reaches the predetermined urea purity of at least 90%, improving the consistency of product quality. Through simultaneous feeding and reaction time control, the overall reaction process is more efficient, ensuring high yield in a short time while maintaining the high purity of urea. Real-time monitoring of the urea concentration provides data support for adjusting reaction conditions, enhancing the controllability of the production process, and reducing the risk of fluctuations in production.

[0052] Step Five: Separation and Purification of the Product, specifically including: Post-reaction Treatment: After the reaction is completed, transfer the reaction mixture to the separation system and cool it down to 20°C using the cooling system to reduce subsequent energy consumption.

[0053] Product Separation: Separate the urease and unreacted raw materials through a centrifuge and collect the urea solution.

[0054] Urea Purification: Perform multi-stage filtration and evaporation on the collected urea solution using a vacuum evaporator to remove water and small molecule impurities, and finally obtain a urea solution.

[0055] After the reaction is completed, carefully transfer the reaction mixture to the separation system, ensuring no air or other contaminants are introduced, and use the cooling system to quickly cool the mixture to 20°C. The purpose of this step is to reduce energy consumption during subsequent processing and at the same time reduce the activity of the reactants, which is crucial for subsequent separation and purification; Place the cooled mixture in a centrifuge and separate the urease and unreacted raw materials such as excess ammonia water and carbon dioxide from the urea solution by centrifugal force. After centrifugation is completed, layer and collect the upper-layer urea solution to ensure that the lower-layer solids and unreacted substances are effectively removed; Perform multi-stage filtration on the collected urea solution, using filter membranes with different pore sizes to remove water and small molecule impurities. This step helps to further improve the purity of urea. Concentrate the filtered urea solution using a vacuum evaporator to remove excess water and further increase the concentration of urea. The vacuum environment helps to evaporate water at a lower temperature and prevent thermal decomposition of urea. After the above steps, a high-purity urea solution with a concentration reaching or exceeding 32.5% is finally obtained; Using the cooling system for temperature reduction can effectively reduce energy consumption during subsequent purification. Compared with traditional methods, it has better economy. Through centrifugal separation technology, unreacted raw materials and urease can be removed quickly and efficiently, reducing product loss and increasing the final yield of urea. The combination of multi-stage filtration and vacuum evaporation significantly improves the purity of urea and reduces the content of small molecule impurities, ensuring that the final product meets the quality standards.

[0056] Step Six: Waste Recycling and System Closed-loop, specifically including: Waste Treatment: Recycle the separated urease and unreacted raw materials, and use special facilities to reintroduce the unreacted ammonia water and carbon dioxide into the reactor to achieve efficient utilization of resources.

[0057] Environmentally Friendly Additive: Add a biodegradable stabilizer to the urea solution to improve the stability of urea in the exhaust pipe and reduce sediment formation.

[0058] Collect the urease and unreacted raw materials such as ammonia water and carbon dioxide obtained during the separation process, and use special equipment and facilities such as gas treatment systems and liquid recovery systems to treat the unreacted ammonia water and carbon dioxide to ensure that their purity meets the reuse standards. Then reintroduce the treated ammonia water and carbon dioxide into the reactor to achieve efficient recycling of resources, reduce raw material consumption and waste emissions. Add stabilizers to the urea solution to improve the stability of urea in the exhaust pipe. The addition of stabilizers can significantly reduce the decomposition of urea at high temperatures and the formation of deposits, ensuring the effectiveness and durability of urea during use. The stabilizer is a mixture of aloe vera extract, tea polyphenols, sodium alginate, gelatin, and citric acid.

[0059] Aloe vera extract has good adhesion and stability, can effectively reduce the degradation of urea, and has natural anti-corrosion properties. Tea polyphenols have antioxidant properties and can delay the decomposition of urea to improve stability. Sodium alginate has good gelling properties, can form a protective film to prevent the rapid decomposition of urea, and is biodegradable. Gelatin can form a stable complex with urea to extend its effectiveness in a high-temperature environment. Citric acid, as a natural organic acid, can help maintain the stability of urea and slow down the hydrolysis rate of urea at high temperatures. Through the waste recycling and reuse system, the purchase cost of raw materials and environmental pollution have been significantly reduced, the economic benefits and environmental friendliness of production have been enhanced. The use of biodegradable additives reduces the impact on the environment, avoids the use of chemically synthesized additives, and improves the environmental protection attributes of urea products.

[0060] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for producing automotive urea for effectively removing dirt from exhaust pipes, characterized in that: The steps include: Step 1: Selection and cultivation of biocatalysts; Step 2: pretreatment of urea raw materials; Step 3: Construction of reaction system; Step 4: Implementation of urea synthesis; Step 5: Separation and purification of products; Step 6: Waste recovery and system closing.

2. The process for producing automotive urea for effectively removing exhaust pipe dirt according to claim 1, characterized in that: The step 1: selection and cultivation of biocatalysts, specifically includes: Urease is selected as the biocatalyst: urease can catalyze the synthesis of urea and is widely available and easy to obtain; Cultivation of urease: Fermentation culture of urease is carried out in a culture medium containing urea, ammonia water and mineral salts. The temperature is controlled at 30-37°C and the pH value is adjusted at 6.5-7.5 to promote the efficient expression of urease. The culture time is 48 hours.

3. The process for producing automotive urea for effectively removing exhaust pipe dirt according to claim 2, characterized in that: The step 2: pretreatment of urea raw materials specifically includes: Raw material selection: Ammonia and carbon dioxide are selected as the main raw materials of urea; Pretreatment of raw materials: Filter the ammonia water to remove impurities to ensure the purity of the raw materials, and dehydrate the carbon dioxide to remove moisture to ensure that the gas is dry during the reaction.

4. The process for producing automotive urea for effectively removing exhaust pipe dirt according to claim 3 is characterized in that: The step three: building a reaction system, specifically includes: Reactor selection: Choose a stainless steel reactor with a volume of no less than 500 liters, equipped with a temperature control system and a stirring device; Reaction condition setting: connect urease into the reactor, set the temperature at 35°C and the pH value at 7.0, and ensure that the reaction proceeds evenly by adjusting the stirring speed.

5. The process for producing automotive urea for effectively removing dirt from exhaust pipes according to claim 1 is characterized in that: The step 4: implementation of urea synthesis specifically includes: Synchronous feeding: pre-treated ammonia and carbon dioxide are added to the reactor at the same time, maintaining the reaction ratio of ammonia: carbon dioxide = 2:1 to optimize the reaction efficiency; Reaction time control: The reaction lasts for 2 hours, and samples are taken regularly to test the urea concentration to ensure that the reaction reaches the predetermined urea yield, at least 90%.

6. The process for producing automotive urea for effectively removing dirt from exhaust pipes according to claim 1, characterized in that: The step 5: separation and purification of the product specifically includes: Post-reaction treatment: After the reaction is completed, the reaction mixture is transferred to the separation system and cooled to 20°C using a cooling system to reduce subsequent energy consumption; Product separation: Separate urease and unreacted raw materials through a centrifuge and collect urea solution; Urea purification: The collected urea solution is subjected to multi-stage filtration and evaporation using a vacuum evaporator to remove moisture and small molecular impurities, and finally obtain a urea solution.

7. The process for producing automotive urea for effectively removing exhaust pipe dirt according to claim 1, characterized in that: The step six: waste recovery and system closure, specifically includes: Waste treatment: The separated urease and unreacted raw materials are recycled and treated, and the unreacted ammonia and carbon dioxide are reintroduced into the reactor using special facilities to achieve efficient utilization of resources; Environmentally friendly additives: Biodegradable stabilizers are added to the urea solution to improve the stability of urea in the exhaust pipe and reduce deposit formation.

8. The process for producing automotive urea for effectively removing dirt from exhaust pipes according to claim 7 is characterized in that: The stabilizer is a mixture of aloe extract, tea polyphenols, sodium alginate, gelatin and citric acid.

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