Marine urea solution and its preparation and use

Abstract

The application discloses a low-temperature marine urea solution which is mainly prepared from the following raw materials: urea 30-38 parts, alanine 5-30 parts and deionized water 40-60 parts. The super-low-temperature urea solution has simple composition, low price and convenient preparation, and the freezing point of the low-temperature marine urea solution is lower than-25 DEG C, so that the low-temperature marine urea solution is suitable for being used in winter in the northern cold region where ships travel, and has high application prospect and application value.

Description

Technical Field

[0001] This invention belongs to the field of marine engine exhaust gas treatment, specifically relating to a low-temperature marine urea solution. Background Technology

[0002] In recent years, with the booming development of the maritime transport industry, environmental pollution caused by ships has become increasingly serious, and most countries in the world have put forward relatively strict requirements on the emission of pollutants from ships. Among the control technologies for reducing nitrogen oxide emissions from ships, selective catalytic reduction (SCR) is currently the most recognized method, which can reduce nitrogen oxide emissions by 90% or even higher. Ships operating in some strictly regulated sea areas basically adopt this method.

[0003] Selective catalytic reduction (SCR) utilizes a series of chemical reactions between an aqueous urea solution and nitrogen oxides in diesel engine exhaust at high temperatures. The products are harmless to humans and the environment. At temperatures of 300-400℃, ammonia, acting as a reducing agent, selectively reacts with nitrogen oxides in the gas, removing harmful NO. X It is converted into harmless nitrogen and water vapor without reacting with oxygen.

[0004] Currently, there are various automotive urea products on the market for treating ship exhaust gases. Marine urea solution (also known as marine nitrogen oxide reducing agent) is directly obtained by mixing 40% urea and 60% deionized water, with a freezing point of around -11°C. This makes it prone to icing when ships are docked in colder northern regions or colder countries, making it unsuitable for cold northern weather. Some companies have produced low-temperature marine urea suitable for northern weather, but these require more types of additives, are more expensive, and are difficult to produce. Therefore, developing a marine urea solution with fewer components, lower cost, and low-temperature resistance is particularly important. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature marine urea solution.

[0006] This invention provides a low-temperature marine urea solution that effectively reduces the emissions of marine urea solution without increasing emissions, while maintaining excellent product stability and meeting the quality standards of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agents AUS40 Part 1. The technical solution of this invention is as follows: a low-temperature marine urea solution, composed of the following weight percentages: 30-38% urea, 10-20% alanine, and 40-60% deionized water. The specific preparation steps of the low-temperature marine urea solution are as follows: deionized water is heated to 30°C, and then the aforementioned percentages of urea and alanine are added to it, allowing it to dissolve completely, and then stored at 30°C for 90 minutes. The deionized water is obtained through single distillation, deionization, ultrafiltration, or reverse osmosis processes to meet the corresponding grade of water. The urea must meet the technical requirements for special urea in GB35176.1-2017 Marine Nitrogen Oxide Reducing Agents AUS40 Part 1. The deionized water must meet the technical requirements for water in GB35176.1-2017 Marine Nitrogen Oxide Reducing Agents AUS40 Part 1 Quality Standard. The alanine substance is a product of analytical grade or higher. The ultra-low temperature urea solution of this invention has a simple composition and is easy to prepare. The freezing point of the ultra-low temperature urea solution is below -25℃, which is fully applicable to use in northern winters and has high application value.

[0007] This invention provides an ultra-low temperature urea solution that is inexpensive. The freezing point of this marine urea solution is below -25°C, making it suitable for use by ships navigating in cold northern winters, and it has high application prospects and practical value. This product is suitable for selective catalytic reduction (SCR) systems used in the treatment of exhaust gases from marine engines and / or boilers. Detailed Implementation

[0008] Example 1:

[0009] Synthesis of a low-temperature marine urea solution (by weight): 56.07 parts of deionized water are selected, heated to 30°C, and then 38 parts of urea and 5.93 parts of alanine are added to dissolve the solution. The solution is then kept at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of the present invention.

[0010] Tests showed that the low-temperature marine urea solution has a freezing point of -27℃, is odorless, clear and transparent in appearance, and has a density of 1.132 g / cm³. 3 The biuret content is 0.33%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and the performance indicators are all qualified.

[0011] Example 2: Synthesis of a low-temperature marine urea solution (by weight): 54.1 parts of deionized water were selected, heated to 30°C, and then 37 parts of urea and 8.9 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -26°C, be odorless, clear and transparent in appearance, and have a density of 1.145 g / cm³. 3 The biuret content is 0.15%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and the performance indicators are all qualified.

[0012] Example 3: Synthesis of a low-temperature marine urea solution (by weight): 52.13 parts of deionized water were selected, heated to 30°C, and then 36 parts of urea and 11.87 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -27°C, be odorless, clear and transparent in appearance, and have a density of 1.145 g / cm³. 3 The biuret content is 0.15%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and the performance indicators are all qualified.

[0013] Example 4: Synthesis of a low-temperature marine urea solution (by weight): 50.17 parts of deionized water were selected, heated to 30°C, and then 35 parts of urea and 14.83 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -29°C, be odorless, clear and transparent in appearance, and have a density of 1.141 g / cm³. 3 The biuret content is 0.25%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and the performance indicators are all qualified.

[0014] Example 5: Synthesis of a Low-Temperature Marine Urea Solution (by weight): 48.20 parts of deionized water were selected, heated to 30°C, and then 34 parts of urea and 17.80 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -28°C, be odorless, clear and transparent in appearance, and have a density of 1.115 g / cm³. 3 The biuret content is 0.37%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and all performance indicators are qualified.

[0015] Example 6: Synthesis of a Low-Temperature Marine Urea Solution (by weight): 46.23 parts of deionized water were selected, heated to 30°C, and then 33 parts of urea and 20.77 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -28°C, be odorless, clear and transparent in appearance, and have a density of 1.115 g / cm³. 3 The biuret content is 0.37%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and all performance indicators are qualified.

[0016] Example 7: Synthesis of a Low-Temperature Marine Urea Solution (by weight): 44.27 parts of deionized water were selected, heated to 30°C, and then 32 parts of urea and 23.73 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -27°C, be odorless, clear and transparent in appearance, and have a density of 1.140 g / cm³. 3 The biuret content is 0.21%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After two months of sealed storage at room temperature (25℃), there are no sensory-perceptible changes in appearance or odor, and all performance indicators are qualified.

[0017] Example 8: Synthesis of a Low-Temperature Marine Urea Solution (by weight): 42.3 parts of deionized water were selected, heated to 30°C, and then 31 parts of urea and 26.7 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -26°C, be odorless, clear and transparent in appearance, and have a density of 1.140 g / cm³. 3 The biuret content is 0.21%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After two months of sealed storage at room temperature (25℃), there are no sensory-perceptible changes in appearance or odor, and all performance indicators are qualified.

[0018] Example 9: Synthesis of a Low-Temperature Marine Urea Solution (by weight): 40.33 parts of deionized water were selected, heated to 30°C, and then 30 parts of urea and 29.67 parts of alanine were added to dissolve the solution. The solution was maintained at 30°C for 90 minutes to obtain the ultra-low temperature urea solution of this invention. The low-temperature marine urea solution was measured to have a freezing point of -26°C, be odorless, clear and transparent in appearance, and have a density of 1.128 g / cm³. 3 The biuret content is 0.16%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agents AUS40 Part 1 Quality Standard. After two months of sealed storage at room temperature (25℃), there are no sensory-perceptible changes in appearance or odor, and all performance indicators are qualified. Comparative Example 1: Synthesis of a low-temperature marine urea solution: 58.03 parts of deionized water were selected, heated to 30℃, and then 39 parts of urea and 2.97 parts of alanine were added to dissolve the solution. The solution was kept at 30℃ for 90 minutes to obtain the ultra-low temperature urea solution of the present invention. The low-temperature marine urea solution has a freezing point of -23℃, is odorless, clear and transparent in appearance, and has a density of 1.143 g / cm³. 3 The biuret content is 0.57%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and the performance indicators are all qualified, but the freezing point is slightly high.

[0019] Comparative Example 2: Synthesis of a low-temperature marine urea solution: 38.36 parts of deionized water were selected, heated to 30°C, and then 29 parts of urea and 32.64 parts of alanine were added to dissolve the solid. It was found that the solid could not be completely dissolved.

[0020] Comparative Example 3: Synthesis of a low-temperature marine urea solution (by weight): 56.07 parts of deionized water were selected, and at room temperature of 20°C, 38 parts of urea and 5.93 parts of alanine were added and dissolved to obtain the ultra-low temperature urea solution of the present invention.

[0021] Tests showed that the low-temperature marine urea solution has a freezing point of -24℃, is odorless, clear and transparent in appearance, and has a density of 1.132 g / cm³. 3 The biuret content is 0.33%, and the content of metal elements and other impurities meets the requirements of GB35176.1-2017 Marine Nitrogen Oxide Reducing Agent AUS40 Part 1 Quality Standard. After being sealed and stored at room temperature (25℃) for two months, there are no sensory changes in appearance or odor, and the performance indicators are all qualified, but the freezing point is slightly high.

[0022] Comparative Example 4: Synthesis of a low-temperature marine urea solution (by weight): 42.3 parts of deionized water were selected, heated to 30°C, and then 31 parts of urea and 26.7 parts of alanine were added to dissolve the solution. The solution was kept at 30°C for 60 minutes. The solid substances in the solution were not completely dissolved.

[0023] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-temperature marine urea solution, characterized in that, It is made by mixing the following raw materials in parts by weight: 30-38 parts urea, 5.93-30 parts alanine, and the remainder is deionized water. The total of urea, alanine and deionized water is 100 parts.

2. The low-temperature marine urea solution according to claim 1, characterized in that: The raw materials used, urea and alanine, are both of analytical grade with a purity of over 99.5%.

3. A method for preparing a low-temperature marine urea solution as described in any one of claims 1-2, characterized in that: Includes the following steps: (1) First, adjust the temperature of the deionized water to 25-35℃; (2) Add urea and alanine to the deionized water in step (1), stir and mix well, and keep at 25-35℃ for 80-100 min to obtain a mixed solution, which is a low-temperature marine urea solution.

4. An application for preparing a low-temperature marine urea solution as described in any one of claims 1-2, which can be used in an environment with an ambient temperature of -25 to -29°C, and is a low-temperature marine urea solution.