A coking inhibitor for non-phosphorus ethylene cracking furnace, its preparation method and application
By employing the physical shielding and chemical inhibition mechanisms of non-phosphorus ethylene cracking furnace coking inhibitors, the coking problem in ethylene cracking furnaces has been solved, achieving efficient coking suppression, long-cycle operation, and environmentally friendly and safe ethylene production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GANSU QINYU BIOTECHNOLOGY CO LTD
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-30
AI Technical Summary
The existing ethylene cracking furnaces suffer from severe coking, which leads to reduced heat exchange efficiency, narrowed fluid channels, equipment corrosion, and pollution of downstream products. Furthermore, the existing chemical inhibitors contain phosphorus compounds that are highly corrosive and have poor environmental performance.
A coking inhibitor for non-phosphorus ethylene cracking furnaces is adopted. The mixed solvent system, consisting of dimethyl dithioaminodiethyl ester, tributyl citrate, and dioctyl maleate, is continuously injected into the pipeline after the cracking feedstock is pretreated through physical shielding and chemical inhibition mechanisms to synergistically inhibit coking.
It significantly reduces coking, extends the operating cycle of cracking furnaces, reduces equipment corrosion and downstream catalyst poisoning risks, meets environmental protection standards, reduces production costs, and improves production safety and ethylene yield.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of ethylene production, and particularly to a coking inhibitor for non-phosphorus ethylene cracking furnaces, its preparation method, and its application. Background Technology
[0002] Ethylene is a core raw material in the petrochemical industry, and the ethylene cracking furnace is a key piece of equipment in the production process. Under high-temperature conditions, the cracking of hydrocarbon feedstocks leads to secondary reactions such as polymerization, generating coking substances that deposit on the inner wall of the furnace tubes, resulting in severe coking.
[0003] Coking can cause several problems: it increases thermal resistance, reduces heat exchange efficiency, and increases energy consumption; it narrows the fluid channel, increases fluid resistance, and affects reaction stability and ethylene yield; it contaminates downstream products and increases separation difficulty; and it requires shutdown for coking removal, increasing production costs and equipment wear.
[0004] Currently, methods for inhibiting coking in pyrolysis furnaces are mainly divided into three categories: surface coating methods, chemical inhibitors, and online pretreatment technologies. Among them, chemical coking inhibitors have become the mainstream due to their ease of use and low cost. However, most existing coking inhibitors contain phosphorus compounds, resulting in serious phosphorus residues, strong corrosiveness, and poor environmental performance. Summary of the Invention
[0005] The main objective of this invention is to propose and address the problems it aims to solve.
[0006] To address the above problems, the present invention proposes... A non-phosphorus ethylene cracking furnace coking inhibitor comprises the following components by mass percentage: 7-32% dimethyl dithioaminodiethyl ester, 25-45% tributyl citrate, 15-35% dioctyl maleate, 10-25% pentaerythritol tetraisostearate, 5-20% sorbitan monooleate, 3-15% dioctyl adipate, 1-10% butyl stearate, and the balance being an organic solvent, which is a mixed solvent system of ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, isopropanol, and n-butanol, and is completely free of phosphorus.
[0007] The acid values of dimethyl dithioaminodiethyl ester, tributyl citrate, and dioctyl maleate are all ≤0.2 mg KOH / g; the acid value of dioctyl adipate is ≤0.1 mg KOH / g; and the iodine value of butyl stearate is ≤1 g I2 / 100g.
[0008] The hydroxyl values of pentaerythritol tetraisostearate and sorbitan monooleate are both 150-170 mg KOH / g.
[0009] The organic solvent is a mixture of ethylene glycol ethyl ether and propylene glycol methyl ether, with a mass ratio of 1:1 to 3:1.
[0010] The organic solvent is a mixture of ethylene glycol ethyl ether and isopropanol in a mass ratio of 2:1 to 4:1.
[0011] The organic solvent is a mixture of propylene glycol methyl ether and isopropanol, with a mass ratio of 1:2 to 2:1.
[0012] The organic solvent is a mixture of ethylene glycol ethyl ether, propylene glycol methyl ether and isopropanol, with a mass ratio of 1:1:1 to 2:1:1.
[0013] A method for preparing a coking inhibitor for a non-phosphorus ethylene cracking furnace includes the following steps: 1) Weigh each component according to the mass percentage described in claim 1, and prepare the mixed solvent in advance according to the proportions described in the corresponding claims 4-7 and let it stand for 20-30 minutes; 2) Add each core component to the mixed solvent in sequence while stirring. The initial stirring speed is 80-100 r / min. 3) Raise the system temperature to 45-50℃, adjust the stirring speed to 150-250 r / min, and continue stirring for 2-3.5 hours until a homogeneous, stable, and transparent liquid is formed. Filter the liquid through a 1.5-2.5μm filter to obtain the finished product. The reaction vessels used in steps 1) and 2) are 316L stainless steel reactors with stirring paddles, and the stirring is carried out with double-end mechanical seals.
[0014] During normal operation of the ethylene cracking furnace, the inhibitor is continuously injected into the pipeline after pretreatment of the cracking feedstock or the dilution steam pipeline through a quantitative injection system. After injection, it is fully mixed through a static mixing pipeline of at least 5 meters in length. The quantitative injection system adopts a metering pump with a flow rate of 0.1-5 L / h and a pressure of 0.4-0.6 MPa. The flow control accuracy is ≤±1.5%, and the injection point is located 1-3 meters downstream of the feedstock preheater outlet.
[0015] The injection concentration is adjusted according to the tube wall temperature of the radiant section of the cracking furnace and the type of raw material: the continuous injection concentration is 80-150×10⁻⁶. -6 In cases of severe coking, the concentration can be temporarily increased to 150×10. -6 Approximately; naphtha feedstock injection concentration 80-120×10 -6 The concentration of light diesel fuel injected is 120-150×10. -6 The inner diameter of the static mixing pipe is the same as that of the raw material feed pipe, and it is equipped with 3-5 sets of SK-type mixing units made of Hastelloy C-276 material.
[0016] Beneficial effects: This invention employs a dual coking mechanism of "physical shielding + chemical inhibition," with each component working synergistically to achieve excellent coking inhibition effects on various pyrolysis feedstocks such as naphtha and light diesel oil. The coking amount is reduced by more than 60%, and the efficiency decays slowly over long-term use. Experimental verification shows that after using the inhibitor of this invention, the operating cycle of the pyrolysis furnace can be extended by more than 58%, significantly reducing the number of shutdowns for coking and improving production continuity.
[0017] The inhibitor of this invention is completely free of phosphorus, avoiding the downstream catalyst poisoning problem caused by phosphorus residue, and can maintain the activity rate of downstream catalysts at over 97%, reducing the product defect rate; the combustion products do not contain harmful gases such as POx, meet VOCs emission standards, and do not require additional desulfurization and dephosphorization equipment, reducing environmental treatment costs; the selected organic solvent has low volatility and high flash point, is safe to operate, and is non-irritating to the human body, improving the safety of the production process.
[0018] The inhibitor of this invention has no corrosive effect on the commonly used alloy materials such as HK-40 and HP-40 in cracking furnace tubes. After 1000 hours of dynamic corrosion test, the corrosion rate is ≤0.005mm / a, which is much lower than that of phosphorus-containing inhibitors (0.032mm / a), and can effectively extend the service life of furnace tubes. At the same time, the inhibitor has good compatibility with existing ethylene cracking processes, and no modification to existing equipment is required. Only a simple injection device needs to be added, which reduces the application cost.
[0019] The inhibitor of this invention does not separate or precipitate after 36 months of storage at -25 to 60°C, making it suitable for industrial storage environments. It is compatible with various light and heavy cracking feedstocks such as naphtha and light diesel oil, and is suitable for different types of ethylene cracking furnaces, with a wide range of applications.
[0020] The preparation method of this invention does not require high temperature and high pressure conditions, the reaction conditions are mild, the operation is convenient, and it is easy to carry out large-scale industrial production. The mixed solvent can be recycled and reused, and the production cost is reduced by 15-20% compared with phosphorus inhibitors. After taking into account the costs of decoking, catalyst replacement and environmental treatment, the total cost is reduced by 20-30%, which has significant economic benefits. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a flowchart of the preparation method of the non-phosphorus ethylene cracking furnace coking inhibitor of the present invention; Detailed Implementation
[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0024] To achieve the above-mentioned objectives, the present invention provides A non-phosphorus ethylene cracking furnace coking inhibitor comprises the following components by mass percentage: 7-32% dimethyl dithioaminodiethyl ester, 25-45% tributyl citrate, 15-35% dioctyl maleate, 10-25% pentaerythritol tetraisostearate, 5-20% sorbitan monooleate, 3-15% dioctyl adipate, 1-10% butyl stearate, and the balance being an organic solvent, which is a mixed solvent system of ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, isopropanol, and n-butanol, and is completely free of phosphorus.
[0025] The acid values of dimethyl dithioaminodiethyl ester, tributyl citrate, and dioctyl maleate are all ≤0.2 mg KOH / g; the acid value of dioctyl adipate is ≤0.1 mg KOH / g; and the iodine value of butyl stearate is ≤1 g I2 / 100g.
[0026] The hydroxyl values of pentaerythritol tetraisostearate and sorbitan monooleate are both 150-170 mg KOH / g.
[0027] The organic solvent is a mixture of ethylene glycol ethyl ether and propylene glycol methyl ether, with a mass ratio of 1:1 to 3:1.
[0028] The organic solvent is a mixture of ethylene glycol ethyl ether and isopropanol in a mass ratio of 2:1 to 4:1.
[0029] The organic solvent is a mixture of propylene glycol methyl ether and isopropanol, with a mass ratio of 1:2 to 2:1.
[0030] The organic solvent is a mixture of ethylene glycol ethyl ether, propylene glycol methyl ether and isopropanol, with a mass ratio of 1:1:1 to 2:1:1.
[0031] A method for preparing a coking inhibitor for a non-phosphorus ethylene cracking furnace includes the following steps: 1) Weigh each component according to the mass percentage described in claim 1, and prepare the mixed solvent in advance according to the proportions described in the corresponding claims 4-7 and let it stand for 20-30 minutes; 2) Add each core component to the mixed solvent in sequence while stirring. The initial stirring speed is 80-100 r / min. 3) Raise the system temperature to 45-50℃, adjust the stirring speed to 150-250 r / min, and continue stirring for 2-3.5 hours until a homogeneous, stable, and transparent liquid is formed. Filter the liquid through a 1.5-2.5μm filter to obtain the finished product. The reaction vessels used in steps 1) and 2) are 316L stainless steel reactors with stirring paddles, and the stirring is carried out with double-end mechanical seals.
[0032] During normal operation of the ethylene cracking furnace, the inhibitor is continuously injected into the pipeline after pretreatment of the cracking feedstock or the dilution steam pipeline through a quantitative injection system. After injection, it is fully mixed through a static mixing pipeline of at least 5 meters in length. The quantitative injection system adopts a metering pump with a flow rate of 0.1-5 L / h and a pressure of 0.4-0.6 MPa. The flow control accuracy is ≤±1.5%, and the injection point is located 1-3 meters downstream of the feedstock preheater outlet.
[0033] The injection concentration is adjusted according to the tube wall temperature of the radiant section of the cracking furnace and the type of raw material: the continuous injection concentration is 80-150×10⁻⁶. -6 In cases of severe coking, the concentration can be temporarily increased to 150×10. -6 Approximately; naphtha feedstock injection concentration 80-120×10 -6 The concentration of light diesel fuel injected is 120-150×10. -6 The inner diameter of the static mixing pipe is the same as that of the raw material feed pipe, and it is equipped with 3-5 sets of SK-type mixing units made of Hastelloy C-276 material. Example 1
[0034] A coking inhibitor for a non-phosphorus ethylene cracking furnace comprises the following components in the indicated mass percentages: 10.5% dimethyl dithioaminodiethyl ester, 25.0% tributyl citrate, 15.0% dioctyl maleate, 10.0% pentaerythritol tetraisostearate, 5.0% sorbitan monooleate, 3.0% dioctyl adipate, 1.0% butyl stearate, with the balance being a mixed solvent (a mixture of ethylene glycol ethyl ether and propylene glycol methyl ether in a mass ratio of 1:1).
[0035] The following are the component specifications: Dimethyl dithioaminodiethyl ester acid value 0.15 mg KOH / g; Tributyl citrate acid value 0.18 mg KOH / g; Dioctyl maleate acid value 0.16 mg KOH / g; Pentaerythritol tetraisostearate hydroxyl value 160 mg KOH / g; Sorbitan monooleate hydroxyl value 165 mg KOH / g; Dioctyl adipic acid ester acid value 0.08 mg KOH / g; Butyl stearate iodine value 0.8 g I2 / 100g.
[0036] The preparation method is as follows: 1) Weigh each component according to the above mass percentages. The mixed solvent should be prepared in advance at a mass ratio of 1:1 and allowed to stand for 25 minutes to ensure uniform mixing. 2) Add the mixed solvent to a 316L stainless steel reactor, and then add dimethyl dithioaminodiethyl ester, tributyl citrate, dioctyl maleate, pentaerythritol tetraisostearate, sorbitan monooleate, dioctyl adipate, and butyl stearate in sequence while stirring. The initial stirring speed is 90 r / min. 3) Slowly heat the reactor to 48°C, adjust the stirring speed to 200 r / min, and continue stirring for 2.5 hours to form a uniform and stable transparent liquid; filter through a 2.0 μm filter to obtain a non-phosphorus ethylene cracking furnace coking inhibitor.
[0037] Application Testing: Processing naphtha (density 0.72 g / cm³) in an SRT-III type cracking furnace 3 The inhibitor (initial boiling point 65℃) is continuously injected into the feed preheater outlet at a depth of 2 meters using a metering pump. The metering pump flow rate is 0.5 L / h, the pressure is 0.5 MPa, and the injection concentration is controlled at 100 × 10⁻⁶. -6 After injection, it passes through a 6-meter-long static mixing pipe (containing 4 sets of SK-type mixing units, made of Hastelloy C-276). After 30 days of operation, the coking amount in the furnace tubes was measured to be 12 g / m². 2 Compared with the blank group (35g / m 2 The corrosion rate of the furnace tube was reduced by 65.7%; the corrosion rate of the furnace tube was 0.0035 mm / a; the downstream catalyst activity retention rate was 97.5%; the ethylene yield was stable at 32.8%; and the inhibitor showed no stratification or precipitation after being stored at -25℃ for 36 months. Example 2
[0038] A coking inhibitor for a non-phosphorus ethylene cracking furnace comprises the following components in the indicated mass percentages: 24.9% dimethyl dithioaminodiethyl ester, 35.0% tributyl citrate, 29.5% dioctyl maleate, 18.0% pentaerythritol tetraisostearate, 12.0% sorbitan monooleate, 9.0% dioctyl adipate, and 5.5% butyl stearate, with the balance being a mixed solvent (a mixture of ethylene glycol ethyl ether and isopropanol in a mass ratio of 3:1).
[0039] The following are the component specifications: Dimethyl dithioaminodiethyl ester acid value 0.19 mg KOH / g; Tributyl citrate acid value 0.17 mg KOH / g; Dioctyl maleate acid value 0.18 mg KOH / g; Pentaerythritol tetraisostearate hydroxyl value 155 mg KOH / g; Sorbitan monooleate hydroxyl value 158 mg KOH / g; Dioctyl adipic acid ester acid value 0.09 mg KOH / g; Butyl stearate iodine value 0.9 g I2 / 100g.
[0040] The preparation method is as follows: 1) Weigh each component according to the above mass percentages. The mixed solvent should be prepared in advance at a mass ratio of 3:1 and allowed to stand for 20 minutes to ensure uniform mixing. 2) Add the mixed solvent to a 316L stainless steel reactor, and then add dimethyl dithioaminodiethyl ester, tributyl citrate, dioctyl maleate, pentaerythritol tetraisostearate, sorbitan monooleate, dioctyl adipate, and butyl stearate in sequence while stirring. The initial stirring speed is 80 r / min. 3) Slowly heat the reactor to 45°C, adjust the stirring speed to 150 r / min, and continue stirring for 3.5 hours to form a uniform and stable transparent liquid; filter through a 1.5 μm filter to obtain a non-phosphorus ethylene cracking furnace coking inhibitor.
[0041] Application Testing: Processing light diesel oil (density 0.83 g / cm³) in a KTI-type pyrolysis furnace 3 (Distillation range 200-350℃) The inhibitor is continuously injected into the dilution vapor line via a metering pump with a flow rate of 2.0 L / h and a pressure of 0.4 MPa. The injection concentration is controlled at 130 × 10⁻⁶. -6 After injection, it passes through a 5-meter-long static mixing pipe (containing 3 sets of SK-type mixing units, made of Hastelloy C-276). After 30 days of operation, the coking amount on the furnace tubes was measured at 15 g / m². 2 Compared with the blank group (42g / m 2 The corrosion rate of the furnace tube was reduced by 64.3%; the corrosion rate of the furnace tube was 0.004 mm / a; the downstream catalyst activity retention rate was 97.2%; the ethylene yield was stable at 32.2%; and the inhibitor showed no stratification or precipitation after being stored at 60℃ for 36 months. Example 3
[0042] A non-phosphorus ethylene cracking furnace coking inhibitor is composed of the following components in the indicated mass percentages: 32.0% dimethyl dithioaminodiethyl ester, 45.0% tributyl citrate, 35.0% dioctyl maleate, 25.0% pentaerythritol tetraisostearate, 20.0% sorbitan monooleate, 15.0% dioctyl adipate, 10.0% butyl stearate, with the balance being a mixed solvent (a mixture of propylene glycol methyl ether and isopropanol in a mass ratio of 2:1).
[0043] The following are the component specifications: Dimethyl dithioaminodiethyl ester acid value 0.20 mg KOH / g; Tributyl citrate acid value 0.20 mg KOH / g; Dioctyl maleate acid value 0.20 mg KOH / g; Pentaerythritol tetraisostearate hydroxyl value 170 mg KOH / g; Sorbitan monooleate hydroxyl value 170 mg KOH / g; Dioctyl adipic acid ester acid value 0.10 mg KOH / g; Butyl stearate iodine value 1.0 g I2 / 100g.
[0044] The preparation method is as follows: 1) Weigh each component according to the above mass percentages. The mixed solvent should be prepared in advance at a mass ratio of 2:1 and allowed to stand for 30 minutes to ensure uniform mixing. 2) Add the mixed solvent to a 316L stainless steel reactor, and then add dimethyl dithioaminodiethyl ester, tributyl citrate, dioctyl maleate, pentaerythritol tetraisostearate, sorbitan monooleate, dioctyl adipate, and butyl stearate in sequence while stirring. The initial stirring speed is 100 r / min. 3) Slowly heat the reactor to 50°C, adjust the stirring speed to 250 r / min, and continue stirring for 2 hours to form a uniform and stable transparent liquid; filter through a 2.5 μm filter to obtain a non-phosphorus ethylene cracking furnace coking inhibitor.
[0045] Application Testing: Processing light diesel oil (density 0.86 g / cm³) in a CBL-III pyrolysis furnace 3 (Aromatics 28%, Sulfur 120ppm) The inhibitor is continuously injected into the pipeline after raw material pretreatment via a metering pump. The metering pump flow rate is 5.0L / h, the pressure is 0.6MPa, and the injection concentration is controlled at 150×10⁻⁶. -6 After injection, it passes through an 8-meter-long static mixing pipe (containing 5 sets of SK-type mixing units, made of Hastelloy C-276). After 70 days of operation, the coking amount on the furnace tubes was measured at 18 g / m². 2 Compared with the control group (60g / m 2 The yield was reduced by 70%; the highest surface temperature of the furnace tubes remained stable at 870℃; the ethylene yield at the end of the period still reached 27.0%; the coke bed hardness (Shore D) was 35, making it easy to clean; the downstream product defect rate was 2%; and the unit energy consumption was 620 kg of standard oil / ton of ethylene, which was 9% lower than the blank group. Example 4
[0046] A non-phosphorus ethylene cracking furnace coking inhibitor is composed of the following components in the indicated mass percentages: 7.0% dimethyl dithioaminodiethyl ester, 30.0% tributyl citrate, 25.0% dioctyl maleate, 15.0% pentaerythritol tetraisostearate, 10.0% sorbitan monooleate, 7.0% dioctyl adipate, 3.0% butyl stearate, with the balance being a mixed solvent (a mixture of ethylene glycol ethyl ether, propylene glycol methyl ether, and isopropanol in a mass ratio of 2:1:1).
[0047] The following are the component specifications: Dimethyl dithioaminodiethyl ester acid value 0.16 mg KOH / g; Tributyl citrate acid value 0.19 mg KOH / g; Dioctyl maleate acid value 0.17 mg KOH / g; Pentaerythritol tetraisostearate hydroxyl value 150 mg KOH / g; Sorbitan monooleate hydroxyl value 150 mg KOH / g; Dioctyl adipic acid ester acid value 0.07 mg KOH / g; Butyl stearate iodine value 0.7 g I2 / 100g.
[0048] The preparation method is the same as in Example 1. Application testing was conducted by treating naphtha in an SRT-III type cracking furnace, with the injected concentration controlled at 80 × 10⁻⁶. -6 After 45 days of operation, the coking rate was reduced by 70.5%, the furnace tube corrosion rate was 0.0038 mm / a, the downstream catalyst activity retention rate was 97.8%, and the ethylene yield remained stable at 33.0%.
[0049] Comparative Example 1 (Comparison with Phosphorus Inhibitors) Commercially available phosphorus-containing coking inhibitors (main component is triphenyl phosphate, phosphorus content is 20%, solvent is toluene) were used under the same experimental conditions as in Example 1 (SRT-III type cracking furnace, naphtha feedstock, injection concentration 100×10⁻⁶). -6 Application testing was conducted. After 30 days of operation, the coking amount on the furnace tubes was measured at 22 g / m². 2 The coking reduction rate was only 42.9%; the furnace tube corrosion rate was 0.032 mm / a, which was 9.1 times that of Example 1; the downstream catalyst activity retention rate was 72%; and the POx emission in the exhaust gas was 120 mg / m³. 3 An additional dephosphorization device is required; the inhibitor precipitates phosphide crystals after being stored at -5°C for 6 months; the ethylene yield is stable at 30.8%, which is 2.0 percentage points lower than that in Example 1.
[0050] Comparative Example 2 (Blank Control) Without adding any coking inhibitors, and operating under the same test conditions as in Example 1 (SRT-III type cracking furnace, naphtha feedstock) for 30 days, the test results showed that the coking amount in the furnace tubes was 35 g / m. 2 Furthermore, localized overheating occurred in the furnace tubes (reaching a maximum temperature of 930°C); the ethylene yield continued to decline, reaching only 28.5% at the end; the downstream product defect rate was 8%; and the unit energy consumption was 680 kg of standard oil / ton of ethylene, which was 9.7% higher than in Example 1.
[0051] Comparative summary Comparative examples and comparative examples show that the non-phosphorus ethylene cracking furnace coking inhibitor of the present invention is significantly superior to existing phosphorus-containing inhibitors in terms of coking efficiency, equipment corrosion resistance, downstream compatibility, environmental friendliness, and storage stability. Compared with the blank control, it can effectively extend the cracking furnace operating cycle, stabilize ethylene yield, reduce energy consumption and downstream product defect rate, verifying its excellent technical effect and practicality.
[0052] Meanwhile, the inhibitor of the present invention is completely free of phosphorus, which solves the core problems of existing phosphorus-containing inhibitors such as phosphorus residue, catalyst poisoning, and environmental pollution. Moreover, the preparation process is simple and low-cost, and no modification to existing equipment is required for application. It is compatible with various cracking feedstocks and operating conditions, which better meets the development needs of modern ethylene plants for "long cycle, low pollution, and high efficiency", and has broad industrial application prospects.
[0053] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
Claims
1. A coking inhibitor for a non-phosphorus ethylene cracking furnace, characterized in that, It is composed of the following components by mass percentage: 7-32% dimethyl dithioaminodiethyl ester, 25-45% tributyl citrate, 15-35% dioctyl maleate, 10-25% pentaerythritol tetraisostearate, 5-20% sorbitan monooleate, 3-15% dioctyl adipate, 1-10% butyl stearate, and the balance being an organic solvent, which is a mixed solvent system of ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, isopropanol, and n-butanol, and is completely free of phosphorus.
2. The coking inhibitor for non-phosphorus ethylene cracking furnaces according to claim 1, characterized in that, The acid values of dimethyl dithioaminodiethyl ester, tributyl citrate, and dioctyl maleate are all ≤0.2 mg KOH / g; the acid value of dioctyl adipate is ≤0.1 mg KOH / g; and the iodine value of butyl stearate is ≤1 g I2 / 100g.
3. The coking inhibitor for non-phosphorus ethylene cracking furnaces according to claim 1, characterized in that, The hydroxyl values of pentaerythritol tetraisostearate and sorbitan monooleate are both 150-170 mg KOH / g.
4. The coking inhibitor for non-phosphorus ethylene cracking furnaces according to claim 1, characterized in that, The organic solvent is a mixture of ethylene glycol ethyl ether and propylene glycol methyl ether, with a mass ratio of 1:1 to 3:
1.
5. The coking inhibitor for non-phosphorus ethylene cracking furnaces according to claim 1, characterized in that, The organic solvent is a mixture of ethylene glycol ethyl ether and isopropanol, with a mass ratio of 2:1 to 4:
1.
6. The coking inhibitor for non-phosphorus ethylene cracking furnaces according to claim 1, characterized in that, The organic solvent is a mixture of propylene glycol methyl ether and isopropanol, with a mass ratio of 1:2 to 2:
1.
7. The coking inhibitor for non-phosphorus ethylene cracking furnaces according to claim 1, characterized in that, The organic solvent is a mixture of ethylene glycol ethyl ether, propylene glycol methyl ether and isopropanol, with a mass ratio of 1:1:1 to 2:1:
1.
8. A method for preparing a non-phosphorus ethylene cracking furnace coking inhibitor according to any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Weigh each component according to the mass percentage described in claim 1, and prepare the mixed solvent in advance according to the proportions described in the corresponding claims 4-7 and let it stand for 20-30 minutes; 2) Add each core component to the mixed solvent in sequence while stirring. The initial stirring speed is 80-100 r / min. 3) Raise the system temperature to 45-50℃, adjust the stirring speed to 150-250r / min, and continue stirring for 2-3.5 hours until a homogeneous, stable, and transparent liquid is formed. Filter the mixture through a 1.5-2.5μm filter to obtain the finished product. The reaction vessels used in steps 1) and 2) are 316L stainless steel reactors with stirring paddles, and the stirring is carried out with double-end mechanical seals.
9. A method for applying the coking inhibitor for a non-phosphorus ethylene cracking furnace according to any one of claims 1 to 7, characterized in that, During normal operation of the ethylene cracking furnace, the inhibitor is continuously injected into the pipeline after pretreatment of the cracking feedstock or the dilution steam pipeline through a quantitative injection system. After injection, it is fully mixed through a static mixing pipeline of at least 5 meters in length. The quantitative injection system adopts a metering pump with a flow rate of 0.1-5 L / h and a pressure of 0.4-0.6 MPa. The flow control accuracy is ≤±1.5%, and the injection point is located 1-3 meters downstream of the feedstock preheater outlet.
10. The application method according to claim 9, characterized in that, The injection concentration is adjusted according to the tube wall temperature of the radiant section of the cracking furnace and the type of raw material: the continuous injection concentration is 80-150×10⁻⁶. -6 In cases of severe coking, the concentration can be temporarily increased to 150×10. -6 Approximately; naphtha feedstock injection concentration 80-120×10 -6 The concentration of light diesel fuel injected is 120-150×10. -6 The inner diameter of the static mixing pipe is the same as that of the raw material feed pipe, and it is equipped with 3-5 sets of SK-type mixing units made of Hastelloy C-276 material.