Method for preventing explosion of low-carbon hydrocarbons and its application

Abstract

The present invention relates to the field of safe production and discloses a method for preventing the explosion of light hydrocarbons. The method comprises: heating a mixed gas composed of oxygen and light hydrocarbons and measuring the autoignition induction time T0 of the light hydrocarbons at a first temperature and a first pressure; diluting the mixed gas with an inert gas to obtain n types of diluted reaction gases with different light hydrocarbon concentrations, and measuring the autoignition induction time T1-T2 of the light hydrocarbons in the n types of diluted reaction gases at the first temperature and a first pressure. n , respectively T1-T n Substitute into the formula T = a1m x The specific values of x, a1, b1 and c1 are obtained in T0+b1mT0+c1 to determine the relationship equation between the autoignition induction time T of light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of light hydrocarbons, where n is an integer ≥4 and m is the volume concentration of light hydrocarbons in the diluted reaction gas.

Description

Technical Field

[0001] The present invention relates to the field of safe production, and in particular to a method for preventing low-carbon hydrocarbons from burning and exploding, and an application thereof. Background Art

[0002] The autoignition induction time refers to the delay time it takes for a combustible gas to spontaneously ignite under certain initial temperature conditions. The autoignition induction time is one of the important parameters of a gas. In particular, with the advancement of the chemical industry in recent years, many industrial production processes involve the mixing and reaction of combustible gases at temperatures far higher than normal. Therefore, mastering and rationally utilizing the autoignition induction time of combustible gases will help improve the safety level of related process steps and ensure the safety of chemical processes. The autoignition process involves high temperatures and short times. Currently, the autoignition induction time of low-carbon hydrocarbons at different temperatures and pressures is mainly measured using fast compressors or shock tubes. However, after measuring the autoignition induction time of low-carbon hydrocarbons, there has been no research on how to extend the autoignition induction time to prevent the explosion of low-carbon hydrocarbons without changing their physical properties. By adding inert gas, the explosion of low-carbon hydrocarbons in the reactor can be avoided without changing the reaction properties of the low-carbon hydrocarbons, thereby preventing casualties.

[0003] To accurately measure the autoignition induction time of a combustible gas, the mixed gas must reach the specified high temperature and high pressure conditions in a very short time. The experimental apparatus should quickly provide a uniform, isothermal, and isobaric ignition or autoignition experimental environment. The test equipment must be able to simultaneously perform high-time resolution measurements and recordings to determine the start and end times of the autoignition induction process. In recent years, some researchers have used a rapid compressor to increase the temperature of the test gas and measure the autoignition induction time, but no measures have been proposed to extend the autoignition induction time. For example, CN205876692U discloses a sealing device for a fast press brake piston. The device includes a piston top and a matching brake cylinder rear end cover. The device is characterized in that the piston top is a conical brake piston top, the brake cylinder rear end cover is a conical groove brake cylinder rear end cover, the brake piston top is bolted to the brake piston body through reserved bolt holes, and the piston top is wrapped with a sealing rubber sleeve of matching size. The sealing rubber sleeve has holes at the bolt holes at the top of the conical cone to facilitate bolt connection and an opening at the bottom of the conical cone to facilitate installation of the sealing sleeve. This device only measures the autoignition induction time of low-carbon hydrocarbons, but does not propose effective measures to extend this time under different operating conditions. CN106089676A discloses a laboratory rapid compressor experimental platform, which includes a combustion chamber unit, a brake cylinder unit, and a drive cylinder unit; the brake cylinder unit includes a drive piston, and a second connecting rod is connected between the drive piston and the brake piston; and is equipped with multiple compression ratio adjustment gaskets that can be placed between the brake cylinder rear cover and the brake cylinder body. The above device can only measure the autoignition induction time of combustible gases under high temperature and high pressure, but does not propose effective measures to extend this time.

[0004] The paper [Effect of NO2 on the Ignition Characteristics of Methane, Ethane, and Natural Gas Using a Shock Tube] investigated the effect of NO2 on the ignition characteristics of CH4 using a shock tube test platform. Ignition delay times were measured at an equivalence ratio of 1 and at various NO2 concentrations (0%, 25%, 50%, and 75% of the fuel concentration). Adding NO2 significantly reduced the ignition delay time of CH4, and the reduction became more pronounced with increasing NO2 content. The effects of various NO2 concentrations (0%, 25%, 50%, and 75% of the C2H6 mixture concentration) on the ignition delay time of C2H6 at an equivalence ratio of 1 were investigated in a shock tube. The experimental results showed that compared to CH4, NO2 had only a slight promoting effect on C2H6, and the promoting effect at low temperatures was significantly greater than that at high temperatures. Based on a shock tube experimental platform, the effects of different NO2 concentrations (0%, 25%, 50%, and 75% of the CH4 / C2H6 mixture concentration) on the ignition characteristics of natural gas (CH4 / C2H6) were studied. The above study shows that the addition of NO2 and alkanes reduces the autoignition induction time of methane, proving that the addition of gas does not necessarily dilute the concentration of low-carbon hydrocarbons and thus prolong their autoignition induction time. Therefore, the study did not fundamentally propose to prolong the autoignition induction time of low-carbon hydrocarbons, nor did it propose measures to prevent the combustion and explosion of low-carbon hydrocarbons. The effects of alkanes and NO2 gas on the ignition delay time were studied. The experimental results show that the effect of added alkanes on the combustion of methane is based on the enhancement of chemical kinetics rather than the influence of calorific value. In other words, the addition of NO2 and alkanes reduces the autoignition induction time of methane. Therefore, the addition of gas does not necessarily dilute the concentration of low-carbon hydrocarbons and thus prolong their autoignition induction time. Summary of the Invention

[0005] The purpose of the present invention is to overcome the technical problems in the prior art of lacking effective measures to extend the spontaneous combustion induction time and prevent the explosion of low-carbon hydrocarbons, and the excessively high temperature and pressure after the explosion causing equipment damage and personal injury, and to provide a method for preventing the explosion of low-carbon hydrocarbons and its application.

[0006] According to prior art records, the autoignition induction time is linearly related to the concentration of light hydrocarbons, and it is believed that adding gas to dilute the concentration of light hydrocarbons can prolong the autoignition induction time of light hydrocarbons. However, the inventors of the present invention unexpectedly discovered in experiments that at the same temperature and pressure, the autoignition induction time T of light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of light hydrocarbons are related by the following equation E1, that is, T = a1m xT0+b1mT0+c1, that is, the autoignition induction time and the concentration of light hydrocarbons are linearly related only under specific conditions. Moreover, in actual use, at the same temperature and pressure, the volume concentration of light hydrocarbons in the reaction gas containing oxygen, light hydrocarbons, and inactive gas for the oxidation reaction is set to m', and m' is substituted into the relationship equation E1 obtained in step (2) to obtain the autoignition induction time T' of the light hydrocarbons in the reaction gas. It has been verified that under the same reaction system, if the oxidation reaction time is no longer than the autoignition induction time T', the light hydrocarbons will not explode. If it is longer than the autoignition induction time T', the light hydrocarbons will explode.

[0007] Therefore, in order to achieve the above-mentioned object, the present invention provides a method for preventing low-carbon hydrocarbons from exploding, the method comprising:

[0008] (1) heating a mixed gas consisting of oxygen and light hydrocarbons and measuring a self-ignition induction time T0 of the light hydrocarbons at a first temperature and a first pressure;

[0009] (2) Diluting a mixed gas of oxygen and light hydrocarbons with an inert gas to obtain n types of diluted reaction gases with different light hydrocarbon concentrations, and still at the first temperature and the first pressure, measuring the autoignition induction time T1-T of the light hydrocarbons in the n types of diluted reaction gases. n , respectively T1-T n Substitute into the formula T = a1m x The specific values of x, a1, b1, and c1 are obtained from T0+b1mT0+c1, thereby determining the relationship equation E1 between the autoignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of the light hydrocarbons, wherein n is an integer ≥ 4, and m is the volume concentration of the light hydrocarbons in the diluted reaction gas;

[0010] (3) The concentration of light hydrocarbons in the reaction gas containing oxygen, light hydrocarbons, and inert gas for the oxidation reaction is set to m', and m' is substituted into the relationship equation E1 obtained in step (2) to obtain the autoignition induction time T' of the light hydrocarbons in the reaction gas. The reaction gas containing oxygen, light hydrocarbons, and inert gas with a light hydrocarbon concentration of m' is subjected to an oxidation reaction under the conditions of a first temperature, a first pressure, and an oxidation reaction time not longer than T'.

[0011] The second aspect of the present invention provides the use of the above method in the preparation of olefins.

[0012] The method for preventing the explosion of light hydrocarbons provided by the present invention can prolong the auto-ignition induction time of light hydrocarbons by adding an inert gas, such as at least one of carbon dioxide, water vapor, a gas of a Group 0 element, and nitrogen, to a mixture of light hydrocarbons and oxygen. In addition, through fitting a large amount of data, it is found that the auto-ignition induction time T of light hydrocarbons in a diluted reaction gas with different light hydrocarbon concentrations and the concentration of the light hydrocarbons have the following relationship equation E1, that is, T = a1m x T0+b1mT0+c1, where T0 is the autoignition induction time of light hydrocarbons at this temperature and pressure, and x, a1, b1, and c1 are fixed constants under the conditions of temperature, pressure, and light hydrocarbon concentration, thereby guiding the control of the oxidation reaction time of olefins, extending the oxidation reaction time, and avoiding the occurrence of explosion, thereby avoiding equipment damage and personal injury caused by excessive temperature and pressure after explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the system structure for testing the auto-ignition induction time of light hydrocarbons according to one embodiment of the present invention.

[0014] Description of Reference Numerals

[0015] 1- low carbon hydrocarbon feed pipeline, 2- premixing device, 3- inactive gas feed pipeline, 4- pump, 5- low carbon hydrocarbon combustion and explosion test device, 6- oxygen feed pipeline. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0017] One aspect of the present invention provides a method for preventing low-carbon hydrocarbons from exploding, the method comprising:

[0018] (1) heating a mixed gas consisting of oxygen and light hydrocarbons and measuring a self-ignition induction time T0 of the light hydrocarbons at a first temperature and a first pressure;

[0019] (2) Diluting a mixed gas of oxygen and light hydrocarbons with an inert gas to obtain n types of diluted reaction gases with different light hydrocarbon concentrations, and still at the first temperature and the first pressure, measuring the autoignition induction time T1-T of the light hydrocarbons in the n types of diluted reaction gases. n , respectively T1-T n Substitute into the formula T = a1m xThe specific values of x, a1, b1, and c1 are obtained from T0+b1mT0+c1, thereby determining the relationship equation E1 between the autoignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of the light hydrocarbons, wherein n is an integer ≥4 (e.g., an integer ≥5, ≥6, ≥7, ≥8, ≥9, ≥10), and m is the volume concentration of the light hydrocarbons in the diluted reaction gas;

[0020] (3) The concentration of light hydrocarbons in the reaction gas containing oxygen, light hydrocarbons, and inert gas for the oxidation reaction is set to m', and m' is substituted into the relationship equation E1 obtained in step (2) to obtain the autoignition induction time T' of the light hydrocarbons in the reaction gas. The reaction gas containing oxygen, light hydrocarbons, and inert gas with a light hydrocarbon concentration of m' is subjected to an oxidation reaction under the conditions of a first temperature, a first pressure, and an oxidation reaction time not longer than T'.

[0021] In some embodiments of the present invention, preferably, when m is 0.1-0.2, x is 2-3. Preferably, when 0.2<m<0.5, x is 1-1.9. Preferably, when m is 0.5-0.99, x is 0.1-0.99. The above relationship between m and x proves that the autoignition induction time is not linearly related to the concentration of low-carbon hydrocarbons in all cases, thereby providing a basis for adding other gases to extend the autoignition induction time of low-carbon hydrocarbons, and preventing the addition of too little inert gas resulting in too little change in the autoignition induction time and the occurrence of combustion and explosion.

[0022] In some embodiments of the present invention, the method may further include:

[0023] (a) preheating a mixed gas consisting of oxygen and light hydrocarbons;

[0024] (b) heating the mixed gas preheated in step (a) to the first temperature.

[0025] In some embodiments of the present invention, the preheating conditions are such that the temperature of the mixed gas is preferably 480-550°C.

[0026] In some embodiments of the present invention, the heating rate is preferably 10-50°C / min, more preferably 20-30°C / min.

[0027] In some embodiments of the present invention, the first temperature is preferably in the range of 800-1000°C.

[0028] In some embodiments of the present invention, the first pressure is preferably in the range of 1-20 bar.

[0029] In some embodiments of the present invention, the number of carbon atoms of the lower hydrocarbon is preferably 1-5, more preferably 1-3.

[0030] In some embodiments of the present invention, preferably, the low-carbon hydrocarbon is at least one of methane, ethane, ethylene, propylene and acetylene.

[0031] In some embodiments of the present invention, the light hydrocarbon is preferably a mixture of at least two light hydrocarbons.

[0032] In some embodiments of the present invention, preferably, the inert gas is at least one of carbon dioxide, water vapor, a Group 0 element gas, and nitrogen.

[0033] In some embodiments of the present invention, the method may further include: changing the type of inert gas in steps (2) and (3), repeating steps (2) and (3) to test and obtain the relationship equation E2 between the auto-ignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations under different inert gases and the concentration of the light hydrocarbons.

[0034] In some embodiments of the present invention, the method may further include: changing the first temperature in steps (1)-(2), repeating steps (1) and (2) to test and obtain the relationship equation E3 between the auto-ignition induction time T of the low-carbon hydrocarbons in the diluted reaction gas with different low-carbon hydrocarbon concentrations at different first temperatures and the concentration of the low-carbon hydrocarbons.

[0035] In some embodiments of the present invention, the method may further include: changing the first pressure in steps (1)-(2), repeating steps (1) and (2) to test and obtain the relationship equation E4 between the autoignition induction time T of the low-carbon hydrocarbons in the diluted reaction gas with different low-carbon hydrocarbon concentrations under different first pressures and the concentration of the low-carbon hydrocarbons.

[0036] In the present invention, one relational equation corresponds to the same inert gas, temperature, or pressure. Due to the wide variety of inert gases, temperatures, and pressures available, those skilled in the art will appreciate that there are multiple relational equations E2-E4. That is, E1-E4 constitute a library of relational equations between the autoignition induction time T and the concentration of light hydrocarbons under various conditions. In practical applications (oxidation reactions), the method of step (3) can be referred to, and the relational equation for the corresponding condition can be found in the library. The equation is then substituted into the library to calculate the autoignition induction time T', and the oxidation reaction can be performed under the condition that the oxidation reaction time is no longer than T'.

[0037] In some embodiments of the present invention, in step (1) or (2), the molar ratio of oxygen to light hydrocarbons is preferably in the range of 1:1-5. The molar ratios of oxygen to light hydrocarbons in each step are substantially the same. More preferably, the absolute value of the difference between the molar ratios of oxygen to light hydrocarbons in steps (1) to (3) is 0.01-0.05, and further preferably 0.

[0038] In some embodiments of the present invention, the reaction time in step (3) is substantially close to T', and the absolute value of the difference between the reaction time in step (3) and T' is preferably 0.01-0.05 ms, more preferably 0. When the reaction time in step (3) is equal to T', the present invention prolongs the oxidation reaction time to the greatest extent, thereby increasing the yield of the product without causing explosion.

[0039] In some embodiments of the present invention, the first temperatures involved in each step are substantially the same, and the absolute value of the difference between the first temperatures in steps (1) to (3) is preferably 0.01-1°C, more preferably 0.

[0040] In some embodiments of the present invention, the first pressures involved in each step are substantially the same, and the absolute value of the difference between the first pressures in steps (1) to (3) is preferably 0.01-0.05 bar, more preferably 0.

[0041] In some embodiments of the present invention, preferably, the inert gases in steps (1) to (3) are of the same type.

[0042] In some embodiments of the present invention, preferably, m and m' are each independently in the range of 0.1-0.99.

[0043] In some embodiments of the present invention, preferably, n is preferably 4-10, and in step (2), dilution is performed in a gradient decreasing manner to obtain n types of diluted reaction gases with different low-carbon hydrocarbon concentrations, and the absolute value of the difference between the concentrations of low-carbon hydrocarbons in the diluted reaction gases of adjacent concentrations is in the range of 0.1-0.2.

[0044] In the present invention, in steps (1) and (2), the test of the self-ignition induction time of the light hydrocarbons is carried out in a gas explosion device.

[0045] According to a preferred embodiment of the present invention, Figure 1 , low-carbon hydrocarbons enter the premixing device 2 from the low-carbon hydrocarbon feed pipeline 1, and oxygen enters the premixing device 2 from the oxygen feed pipeline 6. The mixed gas composed of oxygen and low-carbon hydrocarbons is heated and transported to the low-carbon hydrocarbon combustion and explosion test device 5 through a pump 4 for measurement at a first temperature and a first pressure to measure the autoignition induction time T0 of the low-carbon hydrocarbons. Then, the inert gas feed pipeline 3 enters the premixing device 2 to dilute the mixed gas of oxygen and low-carbon hydrocarbons with an inert gas to obtain n types of diluted reaction gases with different low-carbon hydrocarbon concentrations. The mixed gas is still transported to the low-carbon hydrocarbon combustion and explosion test device 5 through a pump 4 for measurement at the first temperature and the first pressure to measure the autoignition induction time T1-T of the low-carbon hydrocarbons in the n types of diluted reaction gases. n , respectively T1-T n Substitute into the formula T = a1mx The specific values of x, a1, b1 and c1 are obtained from T0+b1mT0+c1, so as to determine the relationship equation E1 between the autoignition induction time T of light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of light hydrocarbons, wherein n is an integer ≥4, and m is the volume concentration of light hydrocarbons in the diluted reaction gas.

[0046] The second aspect of the present invention provides the use of the above method in the preparation of olefins.

[0047] In the present invention, pressure is gauge pressure.

[0048] The present invention will be described in detail below through examples.

[0049] Example 1

[0050] First, methane is introduced into the buffer tank through a feed pipeline, and oxygen is introduced into the buffer tank through a feed pipeline, wherein the molar ratio of oxygen to methane is 1:2. After the temperature in the buffer tank is raised to about 500°C, the mixture is pumped into the gas explosion test device through a plunger pump. The temperature of the explosion test device is raised to 800°C and the pressure is 1 bar at a heating rate of 10°C / min. The gas explosion test device is passed through to obtain 1 bar. At 800°C, the autoignition induction time of methane gas is T0. Then, N2 is flushed into the flash tank through the gas distribution feed pipeline. According to the amount of nitrogen flushed, the methane volume concentration is diluted to 0.9, 0.8, 0.7, 0.6, and 0.5, respectively. Then, a series of methane and N2 mixtures with concentration gradients are respectively introduced into the gas explosion test device through a plunger pump to obtain the autoignition induction times T1, T2, T3, T4, and T5 of methane at different volume concentrations at 800°C. Then according to the formula T=a1m x The coefficients of x, a, b, and c are obtained by fitting T0+b1mT0+c1, thereby obtaining the relationship equation between the autoignition induction time T of methane in the diluted reaction gas with different methane concentrations and the methane concentration.

[0051] Furthermore, under the same conditions, by changing the temperature of the gas explosion device to 900°C and 1000°C respectively, while keeping other conditions unchanged, we can obtain the relationship equation of the change of methane self-ignition induction time with methane concentration at different temperatures and different concentrations.

[0052] Furthermore, at a fixed temperature and under the same conditions, the pressure of the gas explosion device is changed to 5 bar, 10 bar, and 20 bar respectively, while other conditions remain unchanged. The relationship equation between the spontaneous combustion induction time of methane at different concentrations and the change of methane concentration at different pressures can be obtained.

[0053] Furthermore, by changing the type of gas introduced, replacing N2 with argon, adjusting the methane volume concentration to 0.9, 0.8, 0.7, 0.6, or 0.5, and changing the temperature or pressure, the equation for the relationship between the spontaneous combustion induction time of methane at different concentrations and the change in methane concentration can be obtained when the inert gas is argon.

[0054] Furthermore, by changing the type of gas introduced, replacing N2 with water vapor, adjusting the methane volume concentration to 0.9, 0.8, 0.7, 0.6, and 0.5, and changing the temperature or pressure again, the equation for the relationship between the spontaneous combustion induction time of methane at different concentrations and the change in methane concentration can be obtained when the inert gas is water vapor.

[0055] Furthermore, by changing the type of gas introduced, replacing N2 with helium, adjusting the methane volume concentration to 0.9, 0.8, 0.7, 0.6, or 0.5, and again changing the temperature or pressure, we can obtain the equation for the relationship between the spontaneous combustion induction time of methane at different concentrations and the change in methane concentration when the inert gas is helium.

[0056] Furthermore, by changing the type of gas introduced, replacing N2 with a mixture of N2, water vapor, helium, and argon, adjusting the methane volume concentration to 0.9, 0.8, 0.7, 0.6, and 0.5, and changing the temperature or pressure again, the equation for the relationship between the spontaneous combustion induction time of methane at different concentrations and the change in methane concentration is obtained when the inert gas is a mixture of N2, water vapor, helium, and argon.

[0057] Test Experiment

[0058] In a mixture of methane, oxygen, and nitrogen, the volume concentration of methane is 0.55. The relationship between the autoignition induction time T of methane and the concentration of methane at 800°C and 1 bar pressure obtained by the above fitting method is: T = a1m x T0+b1mT0+c1, the self-ignition induction time of methane in the mixed gas is obtained to be 150ms. Then, under the conditions of 800℃ and pressure of 1bar, the volume concentration of methane in the mixed gas of methane, oxygen and nitrogen is controlled to be 0.55. At this time, x is 0.8. The test found that when the oxidation reaction time was 120ms, 125ms, 130ms, 135ms, 140ms, and 145ms, no combustion or explosion occurred. When the oxidation reaction time was controlled to 150ms, combustion and explosion occurred.

[0059] Example 2

[0060] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by ethane.

[0061] Test Experiment

[0062] In a mixture of ethane, oxygen, and nitrogen, the volume concentration of ethane is 0.15. The relationship between the autoignition induction time T of ethane and the concentration of ethane at 800°C and 1 bar pressure obtained by the above fitting method is: T = a1m x T0+b1mT0+c1, the self-ignition induction time of ethane in the mixed gas is obtained to be 130ms. Then, under the conditions of 800℃ and pressure of 1bar, the volume concentration of ethane in the mixed gas of ethane, oxygen and nitrogen is controlled to be 0.15. At this time, x is 2.15. The test found that no combustion or explosion occurred when the oxidation reaction time was 110ms, 115ms, 120ms and 125ms, but combustion and explosion occurred when the oxidation reaction time was controlled to 130ms.

[0063] Example 3

[0064] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by ethylene.

[0065] Test Experiment

[0066] In a mixture of ethylene, oxygen, and nitrogen, the volume concentration of ethylene is 0.18. The relationship between the autoignition induction time T of ethylene and the concentration of ethylene at 800°C and 1 bar obtained by the above fitting method is: T = a1m x T0+b1mT0+c1, the self-ignition induction time of ethylene in the mixed gas is obtained to be 120ms. Then, under the conditions of 800℃ and pressure of 1bar, the volume concentration of ethylene in the mixed gas of ethylene, oxygen and nitrogen is controlled to be 0.18. At this time, x is 2.52. The test found that no combustion or explosion occurred when the oxidation reaction time was 100ms, 105ms, 110ms and 115ms, but combustion and explosion occurred when the oxidation reaction time was controlled to 120ms.

[0067] Example 4

[0068] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by acetylene.

[0069] Test Experiment

[0070] In a mixture of acetylene, oxygen, and nitrogen, the volume concentration of acetylene is 0.11. The relationship between the autoignition induction time T of acetylene and the concentration of acetylene at 800°C and 1 bar pressure obtained by the above fitting method is: T = a1m xT0+b1mT0+c1, the self-ignition induction time of acetylene in the mixed gas is obtained to be 160ms. Then, under the conditions of 800℃ and pressure of 1bar, the volume concentration of acetylene in the mixed gas of acetylene, oxygen and nitrogen is controlled to be 0.11. At this time, x is 2.75. The test found that no combustion or explosion occurred when the oxidation reaction time was 130ms, 135ms, 140ms, 145ms, 150ms and 155ms. When the oxidation reaction time was controlled to 160ms, combustion and explosion occurred.

[0071] Example 5

[0072] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by propylene.

[0073] Test Experiment

[0074] In a mixture of propylene, oxygen, and nitrogen, the volume concentration of propylene is 0.25. The relationship between the autoignition induction time T of propylene and the concentration of propylene at 800°C and 1 bar pressure obtained by the above fitting method is: T = a1m x T0+b1mT0+c1, the self-ignition induction time of propylene in the mixed gas is obtained to be 180ms. Then, under the conditions of 800℃ and pressure of 1bar, the volume concentration of propylene in the mixed gas of propylene, oxygen and nitrogen is controlled to be 0.25. At this time, x is 1.7. The test found that when the oxidation reaction time was 150ms, 155ms, 160ms, 165ms, 170ms and 175ms, no combustion or explosion occurred. When the oxidation reaction time was controlled to 180ms, combustion and explosion occurred.

[0075] Example 6

[0076] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by propane.

[0077] Test Experiment

[0078] In a mixture of propane, oxygen, and nitrogen, the volume concentration of propane is 0.43. The relationship between the autoignition induction time T of propane and the propane concentration at 800°C and 1 bar pressure obtained by the above fitting method is: T = a1m xT0+b1mT0+c1, the self-ignition induction time of propane in the mixture is obtained to be 300ms. Then, under the conditions of 800℃ and pressure of 1 bar, the volume concentration of propane in the mixture of propane, oxygen and nitrogen is controlled to be 0.43. At this time, x is 1.5. The test found that when the oxidation reaction time was 270ms, 275ms, 280ms, 285ms, 290ms and 295ms, no combustion or explosion occurred. When the oxidation reaction time was controlled to 300ms, combustion and explosion occurred.

[0079] Example 7

[0080] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by propyne.

[0081] Test Experiment

[0082] In a mixture of propyne, oxygen, and nitrogen, the volume concentration of propyne is 0.35. The relationship between the autoignition induction time T of propyne and the concentration of propyne at 800°C and 1 bar obtained by the above fitting method is: T = a1m x T0+b1mT0+c1, the self-ignition induction time of propyne in the mixed gas is obtained to be 180ms. Then, under the conditions of 800℃ and pressure of 1bar, the volume concentration of propyne in the mixed gas of propyne, oxygen and nitrogen is controlled to be 0.35. At this time, x is 1.86. The test found that when the oxidation reaction time was 150ms, 155ms, 160ms, 165ms, 170ms and 175ms, no combustion or explosion occurred. When the oxidation reaction time was controlled to 180ms, combustion and explosion occurred.

[0083] Example 8

[0084] The natural induction time test of light hydrocarbons was carried out according to the method of Example 1, except that methane was replaced by a mixture of methane, ethane, ethylene and acetylene, wherein the volume ratio of methane, ethane, ethylene and acetylene was 1:1:1:1.

[0085] Test Experiment

[0086] In a mixture of methane, ethane, ethylene, acetylene, oxygen and nitrogen, the total volume concentration of the four light hydrocarbons of methane, ethane, ethylene and acetylene is 0.98. The relationship between the autoignition induction time T of light hydrocarbons and the concentration of light hydrocarbons at 800°C and 1 bar pressure obtained by the above fitting method is: T = a1m xT0+b1mT0+c1, the self-ignition induction time of low-carbon hydrocarbons in the mixed gas is obtained to be 130ms. Then, under the conditions of 800℃ and pressure of 1 bar, the volume concentration of low-carbon hydrocarbons in the mixed gas of methane, ethane, ethylene, acetylene, oxygen and nitrogen is controlled to be 0.98. At this time, x is 0.93. The test found that when the oxidation reaction time was 110ms, 115ms, 120ms and 125ms, no combustion or explosion occurred. When the oxidation reaction time was controlled to 130ms, combustion and explosion occurred.

[0087] In summary, through a large amount of data fitting, it is found that the autoignition induction time T of light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of light hydrocarbons have the following relationship equation E1, that is, T=a1m x T0+b1mT0+c1, where T0 is the autoignition induction time of light hydrocarbons at this temperature and pressure, and x, a1, b1, and c1 are fixed constants under the conditions of temperature, pressure, and light hydrocarbon concentration, thereby guiding the control of the oxidation reaction time of olefins, extending the oxidation reaction time, and avoiding the occurrence of explosion, thereby avoiding damage to equipment and personal injury caused by excessive temperature or pressure after explosion.

[0088] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preventing low-carbon hydrocarbons from exploding, characterized in that: The method includes: (1) heating a mixed gas consisting of oxygen and light hydrocarbons and measuring a self-ignition induction time T0 of the light hydrocarbons at a first temperature and a first pressure; (2) Diluting a mixed gas of oxygen and light hydrocarbons with an inert gas to obtain n types of diluted reaction gases with different light hydrocarbon concentrations, and still at the first temperature and the first pressure, measuring the autoignition induction time T1-T of the light hydrocarbons in the n types of diluted reaction gases. n , respectively T1-T n Substitute into the formula T = a1m x The specific values of x, a1, b1, and c1 are obtained from T0+b1mT0+c1, thereby determining the relationship equation E1 between the autoignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations and the concentration of the light hydrocarbons, wherein n is an integer ≥ 4, and m is the volume concentration of the light hydrocarbons in the diluted reaction gas; (3) The concentration of light hydrocarbons in the reaction gas containing oxygen, light hydrocarbons, and inert gas for the oxidation reaction is set to m', and m' is substituted into the relationship equation E1 obtained in step (2) to obtain the autoignition induction time T' of the light hydrocarbons in the reaction gas. The reaction gas containing oxygen, light hydrocarbons, and inert gas with a light hydrocarbon concentration of m' is subjected to an oxidation reaction under the conditions of a first temperature, a first pressure, and an oxidation reaction time not longer than T'.

2. The method according to claim 1, wherein The method further comprises: (a) preheating a mixed gas consisting of oxygen and light hydrocarbons; (b) heating the mixed gas preheated in step (a) to the first temperature.

3. The method according to claim 2, wherein: The preheating conditions make the temperature of the mixed gas be 480-550°C.

4. The method according to claim 2 or 3, wherein: The heating rate is 10-50°C / min.

5. The method according to claim 4, wherein The heating rate is 20-30°C / min.

6. The method according to claim 1 or 2, wherein: The first temperature is in the range of 800-1000° C.; and / or the first pressure is in the range of 1-20 bar.

7. The method according to claim 1 or 2, wherein: The carbon number of the low-carbon hydrocarbon is 1-5; And / or, the inert gas is at least one of carbon dioxide, water vapor, a Group 0 element gas, and nitrogen.

8. The method according to claim 7, wherein: The carbon number of the low-carbon hydrocarbon is 1-3; And / or, the low-carbon hydrocarbon is at least one of methane, ethane, ethylene, propylene and acetylene.

9. The method according to claim 1 or 2, wherein: The light hydrocarbon is a mixture of at least two light hydrocarbons.

10. The method according to claim 1 or 2, wherein: The method further comprises: changing the type of the inert gas in step (2), repeating step (2) to test and obtain a relationship equation E2 between the auto-ignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations under different inert gases and the concentration of the light hydrocarbons.

11. The method according to claim 1 or 2, wherein: The method further includes: changing the first temperature in steps (1)-(2), repeating steps (1) and (2) to test and obtain a relationship equation E3 between the autoignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations at different first temperatures and the concentration of the light hydrocarbons.

12. The method according to claim 1 or 2, wherein: The method further includes: changing the first pressure in steps (1)-(2), repeating steps (1) and (2) to test and obtain a relationship equation E4 between the autoignition induction time T of the light hydrocarbons in the diluted reaction gas with different light hydrocarbon concentrations under different first pressures and the concentration of the light hydrocarbons.

13. The method according to claim 1 or 2, wherein: In steps (1) to (3), the molar ratio of oxygen to light hydrocarbon is in the range of 1:1-5.

14. The method according to claim 13, wherein The absolute value of the difference between the molar ratios of oxygen and light hydrocarbons in steps (1) to (3) is 0.01 to 0.

05.

15. The method according to claim 14, wherein The absolute value of the difference between the molar ratios of oxygen and lower hydrocarbons in steps (1) to (3) is 0.

16. The method according to claim 1 or 2, wherein: The absolute value of the difference between the reaction time in step (3) and T' is 0.01-0.05 ms; and / or, the absolute value of the difference in the first temperature in steps (1)-(3) is 0.01-1° C.; and / or, the absolute value of the difference between the first pressures in steps (1)-(3) is 0.01-0.05 bar; and / or, the inert gases in steps (1)-(3) are of the same type; and / or, m and m' are each independently in the range of 0.1-0.99; And / or, n is 4-10, and in step (2), n types of diluted reaction gases with different low-carbon hydrocarbon concentrations are obtained by dilution in a gradient decreasing manner, and the absolute value of the difference between the concentrations of low-carbon hydrocarbons in the diluted reaction gases of adjacent concentrations is in the range of 0.1-0.

2.

17. The method according to claim 16, wherein The absolute value of the difference between the reaction time in step (3) and T' is 0; and / or, the absolute value of the difference in the first temperature in steps (1)-(3) is 0; And / or, the absolute value of the difference between the first pressures in steps (1)-(3) is 0.

18. The method according to claim 1, wherein When m is 0.1-0.2, x is 2-3.

19. The method according to claim 17, wherein When 0.2<m<0.5, x is 1-1.

9.

20. The method according to claim 17, wherein When m is 0.5-0.99, x is 0.1-0.

99.

21. Use of the method according to any one of claims 1 to 20 in the preparation of olefins.

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