High-ammonia loaded composite refrigerant carrier based on sodium thiocyanate as well as preparation method and application of high-ammonia loaded composite refrigerant carrier
The composite refrigerant carrier composed of sodium thiocyanate and other ingredients solves the problems of loading capacity and stability of ammonia carrier materials, realizes efficient and safe ammonia loading, and is suitable for the field of industrial cryogenic refrigeration.
Patent Information
- Application Number
- CN202511013705.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2025-09-23
AI Technical Summary
Existing ammonia carrier materials have defects such as low ammonia loading capacity, high desorption energy consumption, strong corrosiveness or insufficient stability, which limit the application of ammonia in the refrigeration field.
A composite refrigerant carrier composed of sodium thiocyanate, ethylenediamine, ionic liquid [BMIM][BF4], cerium nitrate, benzotriazole and nano-silica is used to load ammonia through chemical or physical adsorption, thereby improving the solubility and stability of ammonia, reducing the system operating pressure and preventing corrosion.
It significantly increases the loading capacity and solubility of ammonia, reduces system energy consumption and corrosiveness, is suitable for industrial cryogenic scenarios, solves the safety hazards when ammonia is directly used, and improves the safety and efficiency of the refrigeration system.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of refrigeration technology, and specifically relates to a high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, a preparation method thereof, and an application thereof. Background Art
[0002] Ammonia (NH3), a highly efficient and environmentally friendly natural refrigerant, has attracted significant attention in the refrigeration industry due to its zero ozone depletion potential (ODP) and extremely low global warming potential (GWP). However, direct use of ammonia poses challenges such as high toxicity, flammability, and high system pressures, limiting its widespread adoption in certain scenarios. Absorption refrigeration technology, which uses ammonia as a refrigerant carrier via chemical or physical adsorption, significantly reduces system operating pressure and improves safety, has become a research hotspot.
[0003] In the field of refrigeration technology, refrigerant carriers are key components of the refrigeration cycle, and their performance directly impacts the efficiency, stability, and environmental friendliness of the refrigeration system. Traditional ammonia carrier materials suffer from limitations such as low ammonia loading capacity, high desorption energy consumption, high corrosiveness, and insufficient stability. Therefore, developing a composite refrigerant carrier with high ammonia loading capacity, low corrosion resistance, and reasonable cost is crucial for promoting the practical application of ammonia absorption refrigeration technology. Summary of the Invention
[0004] To solve the above technical problems, the present invention provides a high-ammonia-load composite refrigerant carrier based on sodium thiocyanate, as well as a preparation method and application thereof, to improve ammonia loading capacity, low-temperature stability and corrosion resistance, thereby filling the technical gap in the field of industrial cryogenics, as follows: A high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, comprising the following components by mass ratio: Sodium thiocyanate (NaSCN) 50-55 parts; Ethylenediamine (EDA) 8-10 parts; 3-5 parts of ionic liquid [BMIM][BF4]; Cerium nitrate (Ce(NO3)3) 0.2-0.5 parts; Benzotriazole (BTA) 0.1-0.2 parts; Nano silicon dioxide (nano SiO2) 0.1-0.2 parts; Octanol (C8H 17 OH) 2-3 parts; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 50-60%.
[0005] Furthermore, a high ammonia load composite refrigerant carrier based on sodium thiocyanate comprises the following components in terms of mass ratio: 50 parts of sodium thiocyanate; 8 parts of ethylenediamine; 3 parts of ionic liquid [BMIM][BF4]; 0.2 parts of cerium nitrate; 0.1 part of benzotriazole; 0.1 parts of nano-silicon dioxide; 2 parts of octanol.
[0006] The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 50%.
[0007] Furthermore, a high ammonia load composite refrigerant carrier based on sodium thiocyanate comprises the following components in terms of mass ratio: 55 parts of sodium thiocyanate; 10 parts of ethylenediamine; 5 parts of ionic liquid [BMIM][BF4]; 0.5 parts of cerium nitrate; 0.2 parts of benzotriazole; 0.2 parts of nano silicon dioxide; 3 parts of octanol.
[0008] The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 60%.
[0009] Furthermore, a high ammonia load composite refrigerant carrier based on sodium thiocyanate comprises the following components in terms of mass ratio: 53 parts of sodium thiocyanate; 9 parts of ethylenediamine; 4 parts of ionic liquid [BMIM][BF4]; 0.3 parts of cerium nitrate; 0.15 parts of benzotriazole; 0.15 parts of nano silicon dioxide; 2.5 parts of octanol.
[0010] The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 55%.
[0011] Furthermore, the ionic liquid [BMIM][BF4] is partially replaced by a choline-urea deep eutectic solvent (DES), and the replacement ratio does not exceed 50% of the total amount of [BMIM][BF4].
[0012] In a second aspect, the present invention provides a method for preparing a high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, comprising the following steps: Step 1: Heat deionized water to 70±2°C, slowly add sodium thiocyanate under nitrogen protection, and stir at 80-120 rpm until completely dissolved; Step 2: Cool the solution to 35±2°C, add ethylenediamine dropwise at a rate of 1 mL / min, and disperse with ultrasonic waves for 8-15 minutes. Step 3: Maintaining 35±2°C, add ionic liquid [BMIM][BF4] and nano-silica, and disperse by ultrasonication for 10-20 minutes; Step 4: Dissolve cerium nitrate in 4-6 mL of deionized water, filter, add the solution obtained in step 1, and introduce CO2 to form a cerium carbonate Ce2(CO3)3 anticorrosive film; Step 5: Dissolve benzotriazole in 4-6 mL of ethanol and add it to the solution obtained in step 3. Disperse for 5-15 minutes, then add octanol dropwise and stir until there is no foam. Step 6: Add deionized water to a total salt concentration of 50-60% to obtain a high ammonia-loaded composite refrigerant carrier.
[0013] Furthermore, in step 2 and step 3, the frequency of ultrasound is 35-45 kHz; and the particle size of nano-silica is 15-25 nm.
[0014] Furthermore, in step 4, carbon dioxide gas at a pressure of 0.1 MPa is introduced into the solution for 25-35 minutes.
[0015] Furthermore, in step 4, the temperature of adding the cerium nitrate solution is controlled at 35-45°C.
[0016] In a third aspect, the present invention provides an application of a high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, which is used as an absorbent for refrigerant ammonia in an ammonia absorption refrigeration cycle and forms a working fluid pair with the refrigerant ammonia.
[0017] Furthermore, for industrial refrigeration or domestic refrigeration, the refrigerant ammonia is ammonia (Refrigerant 717, R717).
[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. When the composite refrigerant carrier provided by the present invention is used as an absorbent in an ammonia absorption refrigeration cycle, it can achieve refrigeration in a wide temperature range of -50°C to 10°C, filling the technical gap of absorption refrigeration in the field of industrial cryogenics.
[0019] 2. Traditional sodium thiocyanate-based ammonia carriers used as refrigerant absorbents have a low solubility in ammonia, about 20-25% by mass, resulting in a small system cooling capacity and the need for a larger volume of solution circulation. The composite refrigerant provided by the present invention has a significantly increased ammonia loading capacity, which can be as high as 38-42% by mass, saving a large amount of resources and floor space.
[0020] 3. The high-ammonia-loaded composite refrigerant carrier provided by the present invention comprises the following components by mass ratio: 50-55 parts of sodium thiocyanate (NaSCN); 8-10 parts of ethylenediamine (EDA); 3-5 parts of ionic liquid [BMIM][BF4]; 0.2-0.5 parts of cerium nitrate (Ce(NO3)3); 0.1-0.2 parts of benzotriazole (BTA); 0.1-0.2 parts of nano-silicon dioxide (nano-SiO2); 0.1-0.2 parts of octanol (C8H 17 OH) 2-3 parts; the rest is ionized water, the total salt concentration of the high ammonia loaded composite refrigerant carrier is 50-60%; in the high ammonia loaded composite refrigerant carrier, the amino group in the EDA molecule can form a strong hydrogen bond complex with ammonia, increasing the ammonia solubility from 20-25% of the traditional NaSCN solution to 35-40%, Na + With SCN - The hydrogen bonds between ammonia molecules are destroyed, and EDA captures free ammonia through hydrogen bonds, forming a "dissolution-complexation" dual mechanism; the hydrophobic imidazole ring of [BMIM][BF4] can reduce the competitive adsorption of ammonia by water, further improving the ammonia loading efficiency; nano-silica can prevent the volatilization of organic amines and the stratification of the solution, improve the cycle stability, and reduce the loss of working fluid; the use of this high ammonia load composite refrigerant carrier can reduce the solution circulation volume, reduce pump power consumption, and improve the system COP by 10-15%; EDA forms a low eutectic mixture with water and ammonia, Inhibits ice and salt crystallization. Traditional NaSCN solution crystallizes at -10°C. Moreover, this high-ammonia-loaded composite refrigerant carrier remains a uniform liquid without crystallization at -50°C to -60°C. [BMIM][BF4] reduces solution viscosity, improves fluidity below -50°C, and avoids pipeline blockage, making it suitable for industrial cryogenic scenarios such as cold chain logistics or chemical refrigeration. At the same time, this carrier can also prevent the evaporation of ammonia carried by the water solvent when NaSCN is heated, resulting in loss of working fluid, effectively inhibiting ammonia corrosion on pipelines and ensuring ammonia desorption efficiency.
[0021] 4. Based on absorption refrigeration technology, the present invention provides a composite refrigerant carrier that loads ammonia by adsorption, which can significantly reduce the system operating pressure, improve the safety of the refrigeration system, and solve the safety hazard caused by the high pressure of the system when ammonia is directly used, which is conducive to the promotion and application of ammonia in more scenarios. DETAILED DESCRIPTION
[0022] Example 1 A high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, comprising the following components by mass ratio: 50 parts of sodium thiocyanate; 8 parts of ethylenediamine; 3 parts of ionic liquid [BMIM][BF4]; 0.2 parts of cerium nitrate; 0.1 part of benzotriazole; 0.1 parts of nano-silicon dioxide; Octanol (C8H 17 OH) 2 parts; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 50%.
[0023] Moreover, the preparation method thereof comprises the following steps: Step 1: Heat deionized water to 68°C, slowly add sodium thiocyanate under nitrogen protection, and stir at 80 rpm until completely dissolved; Step 2: Cool the solution to 33°C and add ethylenediamine dropwise at a rate of 1 mL / min. Disperse the mixture with ultrasonic waves for 8 minutes. Step 3: Maintaining 33°C, add ionic liquid [BMIM][BF4] and nano-silica, and disperse by ultrasonication for 10 minutes; Step 4: Dissolve cerium nitrate in 4 mL of deionized water, filter, add the solution obtained in step 1, and introduce CO2; Step 5: Dissolve benzotriazole in 4 mL of ethanol and add it to the solution obtained in step 3. Disperse for 5 minutes, then add octanol dropwise and stir until there is no foam. Step 6: Add deionized water to a total salt concentration of 50% to obtain a high ammonia-loaded composite refrigerant carrier.
[0024] Moreover, in step 2 and step 3, the frequency of ultrasound is 35 kHz; and the particle size of nano-silica is 15 nm.
[0025] Furthermore, in step 4, carbon dioxide gas at a pressure of 0.1 MPa was introduced into the solution for 25 minutes.
[0026] Moreover, in step 4, the adding temperature of the cerium nitrate solution is controlled at 35°C.
[0027] Example 2 A high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, comprising the following components by mass ratio: 55 parts of sodium thiocyanate; 10 parts of ethylenediamine; 5 parts of ionic liquid [BMIM][BF4]; 0.5 parts of cerium nitrate; 0.2 parts of benzotriazole; 0.2 parts of nano silicon dioxide; Octanol (C8H 17 OH) 3 parts; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 60%.
[0028] Moreover, the preparation method thereof comprises the following steps: Step 1: Heat deionized water to 72°C, slowly add sodium thiocyanate under nitrogen protection, and stir at 120 rpm until completely dissolved; Step 2: Cool the solution to 37°C and add ethylenediamine dropwise at a rate of 1 mL / min. Disperse the mixture with ultrasonic waves for 15 minutes. Step 3: Maintaining 37°C, add ionic liquid [BMIM][BF4] and nano-silica, and disperse by ultrasonication for 20 minutes; Step 4: Dissolve cerium nitrate in 6 mL of deionized water, filter, add the solution obtained in step 4, and introduce CO2; Step 5: Dissolve benzotriazole in 6 mL of ethanol and add it to the solution obtained in step 3. Disperse for 15 minutes, then add octanol dropwise and stir until there is no foam. Step 6: Add deionized water to a total salt concentration of 60% to obtain a high ammonia-loaded composite refrigerant carrier.
[0029] Moreover, in step 2 and step 3, the frequency of ultrasound is 45 kHz; and the particle size of nano-silicon dioxide is 25 nm.
[0030] Furthermore, in step 4, carbon dioxide gas at a pressure of 0.1 MPa was introduced into the solution for 35 minutes.
[0031] Moreover, in step 4, the adding temperature of the cerium nitrate solution is controlled at 45°C.
[0032] Example 3 A high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate, comprising the following components by mass ratio: 53 parts of sodium thiocyanate; 9 parts of ethylenediamine; 4 parts of ionic liquid [BMIM][BF4]; 0.3 parts of cerium nitrate; 0.15 parts of benzotriazole; 0.15 parts of nano silicon dioxide; Octanol (C8H 17 OH) 2.5 parts; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 55%.
[0033] Moreover, the preparation method thereof comprises the following steps: Step 1: Heat deionized water to 70°C, slowly add sodium thiocyanate under nitrogen protection, and stir at 100 rpm until completely dissolved; Step 2: Cool the solution to 35°C and add ethylenediamine dropwise at a rate of 1 mL / min. Disperse the mixture with ultrasonic waves for 10 minutes. Step 3: Maintaining 35°C, add ionic liquid [BMIM][BF4] and nano-silica, and disperse by ultrasonication for 15 minutes; Step 4: Dissolve cerium nitrate in 5 mL of deionized water, filter, add the solution obtained in step 4, and introduce CO2; Step 5: Dissolve benzotriazole in 5 mL of ethanol and add it to the solution obtained in step 3. Disperse for 10 minutes, then add octanol dropwise and stir until there is no foam. Step 6: Add deionized water to a total salt concentration of 55% to obtain a high ammonia-loaded composite refrigerant carrier.
[0034] Moreover, in step 2 and step 3, the frequency of ultrasound is 40 kHz; and the particle size of nano-silicon dioxide is 20 nm.
[0035] Furthermore, in step 4, carbon dioxide gas at a pressure of 0.1 MPa was introduced into the solution for 30 minutes.
[0036] Moreover, in step 4, the adding temperature of the cerium nitrate solution is controlled at 40°C.
[0037] Example 4 In order to reduce costs, based on Example 3, the ionic liquid [BMIM][BF4] was replaced with a choline-urea deep eutectic solvent (DES), and the replacement ratio was 50% of the total amount of [BMIM][BF4].
[0038] Example 5 The composite refrigerant carrier prepared in Example 3 is loaded with ammonia to form a refrigerant for use in a refrigeration system.
[0039] Comparative Example 1 The difference between this comparative example and Example 3 is that no ethylenediamine is added to the high ammonia-loaded composite refrigerant carrier.
[0040] Comparative Example 2 The difference between this comparative example and Example 3 is that no ionic liquid [BMIM][BF4] is added to the high ammonia-loaded composite refrigerant carrier.
[0041] Comparative Example 3 The difference between this comparative example and Example 3 is that no cerium nitrate is added to the high ammonia-loaded composite refrigerant carrier.
[0042] Comparative Example 4 The difference between this comparative example and Example 3 is that no nanosilica is added to the high ammonia-loaded composite refrigerant carrier.
[0043] Comparative Example 5 The difference between this comparative example and Example 3 is that when preparing the high-ammonia-loaded composite refrigerant carrier, CO2 is not introduced in step 4.
[0044] Experimental part The high-ammonia-loaded composite refrigerant carriers provided in Example 1 and Comparative Examples 1-5 were placed in a sealed container, and ammonia gas was introduced to an equilibrium pressure (0.5 MPa). The ammonia solubility at different pressures was recorded. The saturated ammonia solutions were then placed in separate groups at -10°C, -20°C, -30°C, -40°C, and -50°C for 24 hours, and the presence of crystallization or precipitation was recorded. Carbon steel and copper sheets were then immersed in each of these saturated ammonia solutions (60°C for 7 days), and their corrosion rates were calculated using the weight loss method. The results are shown in Table 1.
[0045] As shown in Table 1, the ammonia-loaded composite refrigerant carrier provided by the present invention achieves an ammonia solubility of 41.5% at 0.5 MPa, significantly higher than that of the comparative example. Furthermore, the ammonia-loaded composite refrigerant carrier provided by the present invention remains a homogeneous liquid at -50°C, making it suitable for cryogenic applications. It also exhibits reduced corrosion to pipelines compared to the comparative example.
[0046] Table 1 Comparison of performance of high ammonia loaded composite refrigerant carriers
Claims
1. A high ammonia load composite refrigerant carrier based on sodium thiocyanate, characterized in that: According to the mass ratio, it includes the following ingredients: 50-55 parts of sodium thiocyanate; 8-10 parts of ethylenediamine; 3-5 parts of ionic liquid [BMIM][BF4]; 0.2-0.5 parts of cerium nitrate; 0.1-0.2 parts of benzotriazole; Nano silicon dioxide 0.1-0.2 parts; 2-3 parts of octanol; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 50-60%.
2. The high ammonia load composite refrigerant carrier based on sodium thiocyanate according to claim 1, characterized in that: According to the mass ratio, it includes the following ingredients: 50 parts of sodium thiocyanate; 8 parts of ethylenediamine; 3 parts of ionic liquid [BMIM][BF4]; 0.2 parts of cerium nitrate; 0.1 part of benzotriazole; 0.1 parts of nano-silicon dioxide; 2 parts of octanol; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 50%.
3. The high ammonia load composite refrigerant carrier based on sodium thiocyanate according to claim 1, characterized in that: According to the mass ratio, it includes the following ingredients: 55 parts of sodium thiocyanate; 10 parts of ethylenediamine; 5 parts of ionic liquid [BMIM][BF4]; 0.5 parts of cerium nitrate; 0.2 parts of benzotriazole; 0.2 parts of nano silicon dioxide; 3 parts of octanol; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 60%.
4. The high ammonia load composite refrigerant carrier based on sodium thiocyanate according to claim 1, characterized in that: According to the mass ratio, it includes the following ingredients: 53 parts of sodium thiocyanate; 9 parts of ethylenediamine; 4 parts of ionic liquid [BMIM][BF4]; 0.3 parts of cerium nitrate; 0.15 parts of benzotriazole; 0.15 parts of nano-silicon dioxide; 2.5 parts of octanol; The rest is ionized water; the total salt concentration of the high ammonia loaded composite refrigerant carrier is 55%.
5. The high ammonia load composite refrigerant carrier based on sodium thiocyanate according to claim 1, characterized in that: The ionic liquid [BMIM][BF4] is partially replaced by a choline-urea deep eutectic solvent, and the replacement ratio does not exceed 50% of the total amount of the ionic liquid [BMIM][BF4].
6. The method for preparing a high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Heat deionized water to 70±2°C, slowly add sodium thiocyanate under nitrogen protection, and stir at 80-120 rpm until completely dissolved; Step 2: Cool the solution to 35±2°C, add ethylenediamine dropwise at a rate of 1 mL / min, and disperse with ultrasonic waves for 8-15 minutes. Step 3: Maintaining 35±2°C, add ionic liquid [BMIM][BF4] and nano-silica, and disperse by ultrasonication for 10-20 minutes; Step 4: Dissolve cerium nitrate in 4-6 mL of deionized water, filter, add the solution obtained in step 4, and introduce CO2; Step 5: Dissolve benzotriazole in 4-6 mL of ethanol and add it to the solution obtained in step 3. Disperse for 5-15 minutes, then add octanol dropwise and stir until there is no foam. Step 6: Add deionized water to a total salt concentration of 50-60% to obtain a high ammonia-loaded composite refrigerant carrier.
7. The method for preparing a high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate according to claim 6, characterized in that: In step 2 and step 3, the frequency of ultrasound is 35-45 kHz; and the particle size of nano-silicon dioxide is 15-25 nm.
8. The method for preparing a high-ammonia-loaded composite refrigerant carrier based on sodium thiocyanate as claimed in claim 6, wherein in step 4, carbon dioxide gas at a pressure of 0.1 MPa is introduced into the solution for 25-35 minutes; and the temperature for adding the cerium nitrate solution is 35-45°C.
9. The use of a high ammonia load composite refrigerant carrier based on sodium thiocyanate according to any one of claims 1 to 5, characterized in that: The absorbent used for refrigerant ammonia in the ammonia absorption refrigeration cycle forms a working fluid pair with the refrigerant ammonia.
10. The use of a high ammonia load composite refrigerant carrier based on sodium thiocyanate as claimed in claim 9, characterized in that: Used for industrial refrigeration and freezing or civil air conditioning refrigeration, the refrigerant ammonia is code-named R717.