Method for producing methane hydrates using alcohol-containing wastewater as a water source

Abstract

The present application belongs to the technical field of natural gas storage and transportation, and particularly relates to a method for generating methane hydrate by using alcohol-containing sewage as water source. The specific process of the method comprises the following steps: in stage one, the phase equilibrium condition of alcohol-containing sewage for generating methane hydrate is determined; in stage two, a thermodynamic neutralizing component is added to adjust the phase equilibrium condition of the system; in stage three, a kinetic promoting component is added to adjust the hydrate generation rate and gas storage capacity of the system; and in stage four, the hydrate generation process of the system is observed, recorded and tested. The present application generates methane hydrate by using alcohol-containing sewage as water source, and further provides the medicaments of the thermodynamic neutralizing component and the kinetic promoting component. The thermodynamic neutralizing component is added in batches, and after the phase equilibrium pressure of pure water under the same condition is reached, the kinetic promoting component is added at one time to generate methane hydrate, so that the alcohol-containing sewage of the gas gathering station can be recycled and reused, and meanwhile, the industrial application of the new hydrate gas storage technology has important significance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of natural gas storage and transportation, and relates to the aspect of hydrate method for storing and transporting natural gas, in particular to a method for generating methane hydrate by using alcohol-containing sewage as water source. BACKGROUND

[0002] The storage and transportation of natural gas has always been a big problem in international natural gas trade and marginal oil and gas field development. The current natural gas transportation methods mainly include pipeline transportation of natural gas, compressed natural gas, liquefied natural gas and other transportation processes. For pipeline transportation of natural gas, the construction of the pipeline not only requires huge investment, but also has a huge impact on the ecological environment along the line. This is very unfavorable for long-distance transportation and the development of some small marginal oil and gas fields. Compressed natural gas and liquefied natural gas are the main methods for international natural gas trade and city distribution at present. However, the former needs to compress the gas to a very high pressure, which consumes a large amount of energy, and the high pressure also puts higher requirements on the storage container and brings huge safety hazards. The latter needs to cool the natural gas to a very low temperature for storage, which also consumes a large amount of energy. Natural gas solidification storage and transportation technology is a new natural gas storage process developed in recent years, which mainly stores and transports methane in the form of solid hydrate by forming hydrate.

[0003] The patent "Hydrate Promoter and Its Application in Preparing High Gas Storage Density Gas Hydrate" (Publication / Announcement No. CN104974713A) proposes to use aqueous solutions of different concentrations of amino acids to promote the formation of gas hydrate. The results show that it can shorten the hydrate formation induction time to a certain extent, increase the gas storage capacity and improve the gas storage density. The patent "Hydrate Formation Promoter and Its Application in Methane Storage" (Publication / Announcement No. CN111378515A) proposes that the hydrate formation promoter can efficiently and quickly generate methane hydrate under near-normal temperature conditions (25℃), and can remain stable at higher temperatures. However, this invention only tests the methane hydrate in pure water system and does not conduct related research on alcohol-containing sewage system.

[0004] The large amount of sewage, high alcohol content and high salinity of natural gas gathering stations in China have always restricted the possibility of on-site recycling. For example, a gathering station in Daniudi gas field produces 30-50m 3 of sewage per day, which needs to be transported by sewage tank trucks (20-30m 3The methane emitted from gas fields is transported daily to a purification plant for methanol recovery and other post-processing, resulting in high transportation and processing costs. Furthermore, the resource waste and environmental hazards caused by venting natural gas from gas fields are significant, making methane emission reduction an urgent necessity. Therefore, this patent innovatively proposes reusing wastewater from gas gathering stations as a source of water for hydrate formation, directly reacting with vented natural gas to form solid hydrates, thereby achieving effective recovery of methane from the vented natural gas. The solid hydrate method for storing and transporting natural gas utilizes the solid substance formed by natural gas and water to achieve the storage, transportation, and recovery of natural gas. Theoretically, 1 volume of solid hydrate can store and transport 150-180 volumes of natural gas molecules, thus showing broad application prospects. This method saves on the raw material cost of hydrates and achieves resource recovery and reuse. The hydrate method for storing and transporting natural gas has the advantages of high gas storage capacity, mild preparation conditions, and safety and environmental friendliness, thus attracting widespread attention from researchers. However, wastewater from gas gathering stations usually contains alcohols and salts that inhibit hydrate formation, significantly increasing the thermodynamic conditions for hydrate formation and severely limiting its potential as a source of water for hydrate formation. Therefore, the key to this technology is how to use hydrate inhibitors as a water source for hydrate generation in the presence of hydrate inhibitors in the system, and research in this area is relatively scarce. Summary of the Invention

[0005] The problem this invention aims to solve is to provide a method for generating methane hydrate using alcohol-containing wastewater as a water source. This invention employs a phased addition of thermodynamic neutralization components, followed by a single-phase addition of kinetic promoting components after reaching equilibrium pressure in the pure aqueous phase under the same conditions. This adjusts the thermodynamic and kinetic conditions of the hydrate in the alcohol-containing wastewater system, achieving the goal of rationally recovering and utilizing alcohol-containing wastewater from gas collection stations for methane gas storage and transportation. The adopted technical solution is as follows:

[0006] The method for generating methane hydrates using alcohol-containing wastewater as a water source includes the following specific steps:

[0007] Phase 1: Determine the phase equilibrium conditions for the formation of methane hydrate from alcohol-containing wastewater;

[0008] Phase Two: Thermodynamically neutralizing components are added to adjust the phase equilibrium conditions of the system;

[0009] Phase 3: Add kinetic-promoting components to regulate the hydrate formation rate and gas storage capacity of the system;

[0010] Phase four involves observing, recording, and testing the hydrate formation process of the system.

[0011] Preferably, the alcohol content of the alcohol-containing wastewater is not higher than 20 vol%.

[0012] Preferably, in stage one, the phase equilibrium conditions for the formation of methane hydrate from alcohol-containing wastewater are determined using a pressure search method, specifically as follows:

[0013] In the reactor, 10 ml of alcohol-containing wastewater is added, the temperature in the reactor is adjusted to a certain fixed value, when the temperature in the reactor reaches the preset value, the temperature in the reactor is kept unchanged, methane gas is introduced into the reactor, so that the pressure is higher than the phase equilibrium estimated value by 1 MPa, after a large amount of hydrate is generated in the reactor, the pressure is reduced to decompose the hydrate, when only a small amount of hydrate crystal exists in the reactor, the pressure and temperature in the reactor are kept unchanged, if the hydrate in the reactor can exist for 3-4 h, the temperature in the reactor is kept unchanged, the pressure is reduced by 0.05 MPa, and whether the hydrate is dissolved is observed, if not, it is continuously reduced by 0.05 MPa until the hydrate is completely dissolved, at this time the pressure in the reactor is the phase equilibrium pressure under the temperature condition;

[0014] If necessary, the temperature of the system is changed, and the above operation is repeated, so that the hydrate phase equilibrium pressure corresponding to different temperatures can be obtained.

[0015] Preferably, in the second stage, the phase equilibrium conditions of the alcohol-containing wastewater system are adjusted by adding a thermodynamic neutralizing component, so that the hydrate phase equilibrium pressure of the system is the same as the pressure of pure water under the same temperature condition, and the difference between the two phase equilibrium pressures and the amount of the added thermodynamic neutralizing component are obtained, which specifically includes the following sub-steps:

[0016] (1) Calculate the generation pressure of methane hydrate in pure water system under experimental temperature

[0017] According to the phase equilibrium condition data obtained in stage one, and the temperature and the pressure that the reactor can reach, a suitable experimental temperature is selected, and according to the Chen-Guo model, the hydrate phase equilibrium pressure of the pure water system under the temperature condition is calculated;

[0018] (2) Adjust the phase equilibrium conditions of the alcohol-containing wastewater system to be close to the pure water system

[0019] The alcohol-containing wastewater is added into the reactor, the experimental temperature is set to the temperature selected in sub-step (1), the experimental pressure is higher than the hydrate phase equilibrium pressure of the pure water system calculated in sub-step (1) by 1 MPa, the stirring is started, after the temperature and pressure are stable, a certain amount of thermodynamic neutralizing component is added into the system by using the injection pump, after waiting for 2 h, if a large amount of hydrate is not generated, the thermodynamic neutralizing component is continuously added; the single addition amount is 1.0%.

[0020] The above steps are repeated until a large amount of hydrate is generated in the system, that is, the addition amount of the thermodynamic promoter at this time can adjust the hydrate phase equilibrium pressure of the system to the level of the pure water system under the same temperature;

[0021] (3) Increase the temperature of the system, so that the hydrate in the reactor is completely decomposed.

[0022] Preferably, the temperature range of the experiment is 0-5℃ (i.e. 273.2-283.2K), and the pressure range is 0-8MPa.

[0023] Preferably, in the sub-step (2), the hydrate thermodynamic neutralizing component is one or more of tetrahydrofuran, cyclopentane, dioxolane, and tetrabutylammonium bromide.

[0024] Preferably, in the stage three, the kinetic promoting component is added at one time according to the water amount of the alcohol-containing wastewater.

[0025] Preferably, the kinetic promoting component is 0.05%-1.0% of the water amount of the alcohol-containing wastewater.

[0026] Preferably, the kinetic promoting component is compounded by a kinetic promoter and a stabilizer.

[0027] Preferably, the mass ratio of the kinetic promoter and the stabilizer is 1:0.05-2.

[0028] Preferably, the kinetic promoter is one or more of sodium dodecyl sulfate, p-toluenesulfonic acid, water-soluble hydroxyethyl cellulose polymer, and polyvinyl alcohol, wherein the polyvinyl alcohol has a molecular weight of 200-800, and the water-soluble hydroxyethyl cellulose polymer has a molecular weight of 70000-100000.

[0029] Preferably, the stabilizer is one or both of silicon dioxide and titanium dioxide.

[0030] Preferably, in the stage four, the hydrate generation process of the system is tested and verified, specifically as follows:

[0031] The temperature is lowered again to the temperature set in the stage two experiment, the stirring is kept on, and the hydrate generation is verified, so as to more accurately and effectively verify the thermodynamic and kinetic effects of the additive on the hydrate formation, and the pressure is adjusted to 6.5MPa in this stage.

[0032] After the hydrate starts to generate, the induction time and the pressure change are recorded.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] The present application generates the methane hydrate by using the alcohol-containing wastewater as the water source, adds the thermodynamic neutralizing component in batches, adds the kinetic promoting component at one time after the equilibrium pressure of the pure water under the same condition, adjusts the hydrate thermodynamic and kinetic conditions of the alcohol-containing wastewater system, makes it possible to use the alcohol-containing wastewater as the water source for the hydrate generation, explores the generation of the methane hydrate, and uses it for the storage and transportation of the methane.

[0035] The alcohol-containing sewage is used as the water source for hydrate generation, so that the sewage of the gas gathering station can be used as the water source for hydrate, the alcohol-containing sewage is recycled and reused, and the industrial application of the hydrate gas storage new technology has important significance.

[0036] The application also provides a medicament of a thermodynamic neutralizing component and a kinetic promoting component. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The flow chart of the application.

[0038] Figure 2 The temperature and pressure phase equilibrium diagram of the pure water system methane hydrate. DETAILED DESCRIPTION

[0039] The accompanying drawings are used only for illustrative purposes; in order to make the purposes, technical solutions and advantages of the application more clear, the application is further described in detail below in combination with specific examples. It should be understood that the specific examples described herein are only used to explain the application, and do not limit the application in any way. Unless otherwise specified, the reagents and equipment used in the application are conventional methods, reagents and equipment in the technical field, and the reagents and equipment can be obtained from commercial channels.

[0040] In the description of the present specification, the description of the terms 'one embodiment','some embodiments', 'illustrative embodiment', 'example','specific example' or'some examples' means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] In order to verify the feasibility of the method for generating methane hydrate by using alcohol-containing sewage as the water source, the sewage at the outlet of the gas-water separation tank of the gas gathering station is collected at different time periods, and is respectively named as No. 1 alcohol-containing sewage, No. 2 alcohol-containing sewage and No. 3 alcohol-containing sewage. The collection time is as follows.

[0042] No. 1 alcohol-containing sewage: 10:00;

[0043] No. 2 alcohol-containing sewage: 14:00;

[0044] No. 3 alcohol-containing sewage: 16:00.

[0045] In addition, the terms "1st", "2nd", and the like are used only for descriptive purposes and should not be construed as indicating or implying relative importance or a specific number of the technical features indicated. Thus, the use of "1st", "2nd", and the like is only for the purpose of distinguishing, for ease of understanding. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0046] To illustrate the method of the present application in detail, specific reference is made to the following examples and drawings.

[0047] Example 1

[0048] As shown in Figure 1 , the object of this example is a 1st alcohol-containing wastewater sample.

[0049] Stage 1, determine the phase equilibrium conditions of the alcohol-containing wastewater to generate methane hydrate. As shown in Figure 2 , the determined phase equilibrium diagram of methane hydrate temperature and pressure of pure water system, where the temperature unit is K, the upper left area of the diagram is the temperature and pressure range that can generate hydrate.

[0050] Take 10 ml of the alcohol-containing wastewater sample 1st, adjust the temperature in the reaction kettle to 0.5℃, when the temperature of the reaction kettle reaches the preset value, keep the temperature of the reaction kettle unchanged, introduce methane gas into the reaction kettle to 5 MPa, and determine the phase equilibrium pressure of the sample at 0.5℃ by pressure search method, which is 3.65 MPa. According to the calculation of Chen-Guo model, the phase equilibrium pressure of methane hydrate of pure water at this temperature is 2.75 MPa, and the difference between the two is 0.90 MPa.

[0051] Stage 2, add thermodynamic neutralizing components to adjust the phase equilibrium conditions of the system.

[0052] In this example, the thermodynamic neutralizing components used are tetrahydrofuran and cyclopentane mixed in a volume ratio of 1:1.

[0053] According to the experimental results, there is a certain correspondence between the w% of the amount of thermodynamic neutralizing components added and the difference ΔP between the phase equilibrium pressure of the alcohol-containing wastewater at the same temperature and that of the pure water system, as shown in Table 1. When ΔP is too large, the appropriate amount of thermodynamic neutralizing components can be added at one time according to the table, and then 1% of the thermodynamic neutralizing components can be added in batches until a large amount of hydrate is generated.

[0054] Table 1 Correspondence between w% of the amount of thermodynamic neutralizing components added and the difference ΔP between the phase equilibrium pressure of the alcohol-containing wastewater at the same temperature and that of the pure water system

[0055] ΔP / MPa 0 < ΔΡ ≤ 0.5 0.5 < ΔΡ ≤ 1 1 < ΔΡ ≤ 2 2 < ΔΡ ≤ 3 3 < ΔΡ ≤ 3.5 3.5 < ΔΡ ≤ 4 4 < ΔP≤ 5 w％ 3 wt% 5 wt% 6 wt% 8 wt% 10 wt% 12 wt% 15 wt%

[0056] Take 10 ml of alcohol-containing sewage sample No. 1 into the reaction kettle, adjust the experimental temperature to 0.5°C, and the experimental pressure to 3.75 MPa. No hydrate is generated within two hours. Add 0.3 ml of thermodynamic neutralization component into the system through the injection pump. No hydrate is generated within two hours. Continue to add 0.1 ml. No hydrate is generated within two hours. Through observation of the reaction kettle, 36 min after the third addition of 0.1 ml, hydrate begins to appear in the reaction kettle. After 2 h, part of the methane hydrate is observed to be generated on the kettle wall and the gas-liquid interface, proving that the thermodynamic phase equilibrium condition of the system is successfully adjusted. Increase the temperature to decompose the methane hydrate.

[0057] Stage three, add a kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system.

[0058] In the kinetic promoting component used, the kinetic promoter SDS (sodium dodecyl sulfate) is mixed with the stabilizer SiO2 at a mass ratio of 1:0.5.

[0059] After the methane hydrate is completely decomposed, add 0.2 wt% of the kinetic promoting component into the reaction kettle through the injection pump at one time.

[0060] Stage four, set the experimental temperature to 0.5°C, and introduce methane gas to 6.5 MPa. Through observation of the reaction kettle, it is found that the induction time of methane hydrate generation is 6 min. The system pressures at the 30th min and the 120th min after the generation are 6084 kPa and 5552 kPa, respectively, and the gas storage capacity is 0.0659 mol / mol.

[0061] Example 2

[0062] The object of this example is alcohol-containing sewage sample No. 1

[0063] Stage one, determine the phase equilibrium condition of the alcohol-containing sewage for generating methane hydrate. The experimental process is the same as that in Example 1.

[0064] Stage two, add a thermodynamic neutralization component to adjust the phase equilibrium condition of the system.

[0065] In this example, the thermodynamic neutralization component used is tetrahydrofuran.

[0066] The object of this example is alcohol-containing sewage sample No. 1. A total of 0.6 ml of the thermodynamic neutralization component is added in four times. 25 min after the third addition, hydrate begins to appear in the reaction kettle. After 2 h, part of the methane hydrate is observed to be generated on the kettle wall and the gas-liquid interface, proving that the thermodynamic phase equilibrium condition of the system is successfully adjusted.

[0067] Stage three, add a kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system.

[0068] The kinetic promoter SDS, the hydroxyethyl cellulose polymer and the stabilizer SiO2 are mixed in a mass ratio of 1:0.5:0.5.

[0069] After the methane hydrate is completely decomposed, the kinetic promoter is added into the reactor through the injection pump at one time, and the amount is 0.3wt% of the water amount of the system.

[0070] In the fourth stage, it is found through the reactor observation that the induction time of the methane hydrate generation is 4.1min, the system pressures at the 30th min and the 120th min after the generation are 6147kPa and 5425kPa respectively, and the gas storage amount is 0.0724mol / mol.

[0071] The other places not mentioned are the same as those in Example 1.

[0072] Example 3

[0073] The object of this example is the No.1 alcohol-containing sewage sample.

[0074] In the first stage, the phase equilibrium condition of the alcohol-containing sewage for generating the methane hydrate is determined, and the experimental process is the same as that in Example 1.

[0075] In the second stage, the thermodynamic neutralization component is added to adjust the phase equilibrium condition of the system.

[0076] In this example, the thermodynamic neutralization component used is THF (tetrahydrofuran) and TBAB (tetrabutylammonium bromide) mixed in a mass ratio of 1:1.

[0077] The object of this example is the No.1 alcohol-containing sewage sample, and the thermodynamic neutralization component is added for three times with a total amount of 0.5ml. 25min after the third time of adding, the hydrate begins to appear in the reactor, and part of the methane hydrate is observed to be generated on the reactor wall and the gas-liquid interface after 2h, which proves that the adjustment of the thermodynamic phase equilibrium condition of the system is successful.

[0078] In the third stage, the kinetic promoter is added to adjust the hydrate generation rate and the gas storage amount of the system.

[0079] The kinetic promoter SDS, the polyvinyl alcohol and the stabilizer TiO2 are mixed in a mass ratio of 1:0.5:0.5.

[0080] After the methane hydrate is completely decomposed, the kinetic promoter is added into the reactor through the injection pump at one time, and the amount is 0.3wt% of the water amount of the system.

[0081] In the fourth stage, it is found through the reactor observation that the induction time of the methane hydrate generation is 3.5min, the system pressures at the 30th min and the 120th min after the generation are 6047kPa and 5485kPa respectively, and the gas storage amount is 0.0693mol / mol.

[0082] The other parts not mentioned are the same as in Example 1.

[0083] Example 4

[0084] The sample of the alcohol-containing wastewater used in this example is Sample No. 1.

[0085] Stage One: The phase equilibrium conditions for the formation of methane hydrate from the alcohol-containing wastewater were determined, and the experimental process was the same as in Example 1.

[0086] Stage Two: The phase equilibrium conditions of the system were adjusted by adding a thermodynamic neutralization component.

[0087] In this example, the thermodynamic neutralization component used was a mixture of THF and TBAB in a mass ratio of 1:2.

[0088] The sample of the alcohol-containing wastewater used in this example is Sample No. 1, and the thermodynamic neutralization component was added in batches, with a total of 0.4 ml. 58 minutes after the second addition, hydrate began to form in the reactor, and 2 hours later, some methane hydrate was observed to have formed on the reactor wall and at the gas-liquid interface, indicating that the adjustment of the thermodynamic phase equilibrium conditions of the system was successful.

[0089] Stage Three: The formation rate of hydrate and the gas storage capacity of the system were adjusted by adding a kinetic promotion component.

[0090] In the kinetic promotion component used, the kinetic promoter SDS, polyvinyl alcohol, and the stabilizer TiO2 were mixed in a mass ratio of 1:0.5:0.5.

[0091] After the methane hydrate was completely decomposed, the kinetic promotion component was added to the reactor in one batch through an injection pump, and the amount was 0.3 wt% of the water amount in the system.

[0092] Stage Four: It was found through observation of the reactor that the induction time for the formation of methane hydrate was 4.1 minutes, the system pressures at the 30th minute and the 120th minute after the formation of the hydrate were 5928 kPa and 5536 kPa, respectively, and the gas storage capacity was 0.0667 mol / mol.

[0093] The other parts not mentioned are the same as in Example 1.

[0094] Example 5

[0095] The sample of the alcohol-containing wastewater used in this example is Sample No. 1.

[0096] Stage One: The phase equilibrium conditions for the formation of methane hydrate from the alcohol-containing wastewater were determined, and the experimental process was the same as in Example 1.

[0097] Stage Two: The phase equilibrium conditions of the system were adjusted by adding a thermodynamic neutralization component.

[0098] The thermodynamic neutralizing component used in this embodiment is dioxolane and TBAB mixed at a mass ratio of 1:1.

[0099] The object of this embodiment is sample No. 1 of alcohol-containing wastewater, and the thermodynamic neutralizing component is added in batches, with a total of 0.5 ml. 46 min after the second addition, hydrates began to appear in the reactor, and 2 h later, part of the methane hydrates were observed to be generated on the reactor wall and the gas-liquid interface, proving that the thermodynamic phase equilibrium condition adjustment was successful.

[0100] Stage three, the kinetic promoting component is added to adjust the hydrate formation rate and gas storage capacity of the system.

[0101] The kinetic promoting component used in this embodiment is a mixture of kinetic promoter SDS, p-TSA (p-toluene sulfonic acid), and stabilizer TiO2 at a mass ratio of 1:1:0.1.

[0102] After the methane hydrates are completely decomposed, the kinetic promoting component is added to the reactor in one batch through the injection pump, and the amount is 0.8 wt% of the water amount of the system.

[0103] Stage four, through observation of the reactor, it is found that the induction time of methane hydrate formation is 4.5 min, and the system pressure is 6092 kPa and 5382 kPa at 30 min and 120 min after the formation, respectively, and the gas storage capacity is 0.0747 mol / mol.

[0104] Other places not mentioned are the same as in Example 1.

[0105] Example 6

[0106] The object of this embodiment is sample No. 2 of alcohol-containing wastewater.

[0107] Stage one, determine the phase equilibrium condition of the alcohol-containing wastewater to form methane hydrates.

[0108] Take 10 ml of alcohol-containing wastewater sample No. 2, adjust the temperature in the reactor to 2°C, and when the temperature in the reactor reaches the preset value, keep the temperature in the reactor unchanged, and introduce methane gas into the reactor to 7 MPa. The phase equilibrium pressure of the sample at 2°C is 6.30 MPa by pressure search method. According to the calculation of Chen-Guo model, the methane hydrate phase equilibrium pressure of pure water at this temperature is 2.75 MPa, and the difference between the two is 3.55 MPa.

[0109] Stage two, add the thermodynamic neutralizing component to adjust the phase equilibrium condition of the system.

[0110] The thermodynamic neutralizing component used in this embodiment is THF and TBAB mixed at a mass ratio of 1:1.

[0111] The object of this example is the No. 2 alcohol-containing sewage sample, and the thermodynamic neutralizing component is added in batches, a total of 1.2 ml, and 34 min after the third addition of 0.1 ml, hydrate begins to appear in the reaction kettle, and 2 h later, part of the methane hydrate is observed to be generated on the kettle wall and the gas-liquid interface, proving that the thermodynamic phase equilibrium condition adjustment is successful.

[0112] Stage three, add the kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system.

[0113] Among the kinetic promoting components used, the kinetic promoter SDS, polyvinyl alcohol, and stabilizer TiO2 are mixed in a mass ratio of 1:0.5:0.5.

[0114] After the methane hydrate is completely decomposed, the kinetic promoting component is added to the reaction kettle in one batch through the injection pump, and the amount is 0.2wt% of the water amount of the system.

[0115] Stage four, through observation of the reaction kettle, it is found that the induction time of methane hydrate generation is 7.3 min, and the system pressure is 6147 kPa and 5639 kPa at 30 min and 120 min after generation, respectively, and the gas storage capacity is 0.0613 mol / mol.

[0116] Other places not mentioned are the same as in Example 1.

[0117] Example 7

[0118] The object of this example is the No. 2 alcohol-containing sewage sample.

[0119] Stage one, determine the phase equilibrium condition of the alcohol-containing sewage generating methane hydrate, and the experimental process is the same as in Example 6.

[0120] Stage two, add the thermodynamic neutralizing component to adjust the phase equilibrium condition of the system.

[0121] In this example, the thermodynamic neutralizing component used is a mixture of cyclopentane, dioxolane, and tetrahydrofuran in a mass ratio of 1:1:1.

[0122] The object of this example is the No. 2 alcohol-containing sewage sample, and the thermodynamic neutralizing component is added in batches, a total of 1.3 ml, and 63 min after the fourth addition, hydrate begins to appear in the reaction kettle, and 2 h later, part of the methane hydrate is observed to be generated on the kettle wall and the gas-liquid interface, proving that the thermodynamic phase equilibrium condition adjustment is successful.

[0123] Stage three, add the kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system.

[0124] Among the kinetic promoting components used, the kinetic promoter p-toluenesulfonic acid, polyvinyl alcohol, and stabilizer SiO2 are mixed in a mass ratio of 1:0.3:0.2.

[0125] After the methane hydrate was completely decomposed, the kinetic promoting component was added into the reactor by the injection pump at one time, and the amount was 0.3wt% of the water amount in the system.

[0126] In stage four, the reactor observation showed that the induction time of the methane hydrate formation was 6.7min, the system pressures at the 30th min and the 120th min after the formation were 6073kPa and 5614kPa respectively, and the gas storage amount was 0.0626mol / mol.

[0127] The other places not mentioned were the same as those in Example 1.

[0128] Example 8

[0129] The object of this example was the No.2 alcohol-containing sewage sample.

[0130] In stage one, the phase equilibrium condition of the alcohol-containing sewage for forming the methane hydrate was determined, and the experimental process was the same as that in Example 6.

[0131] In stage two, the thermodynamic neutralizing component was added to adjust the phase equilibrium condition of the system.

[0132] In this example, the thermodynamic neutralizing component used was the mixture of THF and TBAB with the mass ratio of 1:1.

[0133] The object of this example was the No.2 alcohol-containing sewage sample, and the thermodynamic neutralizing component was added in batches, and the total amount was 1.0ml. 44min after the second addition, the hydrate began to appear in the reactor, and part of the methane hydrate was observed to be formed on the reactor wall and the gas-liquid interface after 2h, which proved that the adjustment of the thermodynamic phase equilibrium condition of the system was successful.

[0134] In stage three, the kinetic promoting component was added to adjust the hydrate formation rate and the gas storage amount of the system.

[0135] In the kinetic promoting component used, the kinetic promoter SDS, polyvinyl alcohol and the stabilizer TiO2 were mixed with the mass ratio of 1:0.5:0.5.

[0136] After the methane hydrate was completely decomposed, the kinetic promoting component was added into the reactor by the injection pump at one time, and the amount was 0.5wt% of the water amount in the system.

[0137] In stage four, the reactor observation showed that the induction time of the methane hydrate formation was 5.4min, the system pressures at the 30th min and the 120th min after the formation were 6032kPa and 5583kPa respectively, and the gas storage amount was 0.0643mol / mol.

[0138] The other places not mentioned were the same as those in Example 1.

[0139] Example 9

[0140] The sample of the alcohol-containing wastewater used in this example was Sample No. 2.

[0141] Stage One: The phase equilibrium conditions for the formation of methane hydrate in the alcohol-containing wastewater were determined, and the experimental process was the same as that in Example 6.

[0142] Stage Two: The phase equilibrium conditions of the system were adjusted by adding a thermodynamic neutralization component.

[0143] In this example, the thermodynamic neutralization component used was a mixture of THF and TBAB in a mass ratio of 1:2.

[0144] The sample of the alcohol-containing wastewater used in this example was Sample No. 2, and the thermodynamic neutralization component was added in batches, with a total of 1.1 ml added. 26 minutes after the third addition, hydrate began to form in the reactor, and 2 hours later, some methane hydrate was observed to have formed on the reactor wall and at the gas-liquid interface, indicating that the adjustment of the thermodynamic phase equilibrium conditions of the system was successful.

[0145] Stage Three: The hydrate formation rate and gas storage capacity of the system were adjusted by adding a kinetic promoter.

[0146] In the kinetic promoter used, the kinetic promoter SDS, water-soluble hydroxyethyl cellulose, and stabilizer SiO2 were mixed in a mass ratio of 1:0.3:0.1.

[0147] After the methane hydrate was completely decomposed, the kinetic promoter was added to the reactor in one batch through an injection pump, with the amount being 0.8 wt% of the water in the system,

[0148] Stage Four: It was found through observation of the reactor that the induction time for the formation of methane hydrate was 4.3 minutes, and the system pressures at the 30th minute and the 120th minute after the formation of the hydrate were 5993 kPa and 5509 kPa, respectively, and the gas storage capacity was 0.0681 mol / mol.

[0149] Other aspects not mentioned were the same as in Example 1.

[0150] Example 10

[0151] The sample of the alcohol-containing wastewater used in this example was Sample No. 2.

[0152] Stage One: The phase equilibrium conditions for the formation of methane hydrate in the alcohol-containing wastewater were determined, and the experimental process was the same as that in Example 6.

[0153] Stage Two: The phase equilibrium conditions of the system were adjusted by adding a thermodynamic neutralization component.

[0154] In this example, the thermodynamic neutralization component used was a mixture of THF and TBAB in a mass ratio of 1:2.

[0155] The object of this example is the 2nd alcohol-containing wastewater sample, which is added in batches with thermodynamic neutralizing components, a total of 1.2 ml, 46 min after the third addition, hydrates begin to appear in the reactor, and 2 h later, some methane hydrates can be observed on the reactor wall and the gas-liquid interface, proving that the system thermodynamic phase equilibrium condition adjustment is successful.

[0156] Phase three, add kinetic promoting components to adjust the hydrate formation rate and gas storage capacity of the system.

[0157] Among the kinetic promoting components used, the kinetic promoter polyvinyl alcohol, p-toluenesulfonic acid, and the stabilizer TiO2 are mixed in a mass ratio of 1:1:0.4.

[0158] After the methane hydrate is completely decomposed, the kinetic promoting components are added to the reactor in one batch through the injection pump, and the amount is 1.0 wt% of the water amount of the system.

[0159] Phase four, through observation of the reactor, it is found that the induction time of methane hydrate formation is 6.1 min, and the system pressure is 5984 kPa and 5502 kPa at 30 min and 120 min after the formation, respectively, and the gas storage capacity is 0.0685 mol / mol.

[0160] Other places not mentioned are the same as in Example 6.

[0161] Example 11

[0162] The object of this example is the 3rd alcohol-containing wastewater sample.

[0163] Phase one, determine the phase equilibrium condition of the alcohol-containing wastewater to form methane hydrate.

[0164] Take 10 ml of the alcohol-containing wastewater sample No. 3, adjust the temperature in the reactor to 3°C, when the temperature in the reactor reaches the preset value, keep the temperature in the reactor unchanged, introduce methane gas into the reactor to 6 MPa, and determine the phase equilibrium pressure of the sample at 2°C by pressure search method. The phase equilibrium pressure of pure water at this temperature is 2.75 MPa, and the difference between the two is 2.75 MPa.

[0165] Phase two, add thermodynamic neutralizing components to adjust the phase equilibrium condition of the system

[0166] In this example, the thermodynamic neutralizing components used are tetrahydrofuran and dioxolane mixed in a volume ratio of 2:1.

[0167] The object of this example is the No. 3 alcohol-containing sewage sample, and the thermodynamic neutralizing component is added in batches, with a total of 0.8 ml. 13 min after the third addition, hydrate began to appear in the reactor, and 2 h later, part of the methane hydrate was observed to be generated on the reactor wall and the gas-liquid interface, proving that the system's thermodynamic phase equilibrium condition adjustment was successful.

[0168] Phase three, add kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system.

[0169] Among the kinetic promoting components used, the kinetic promoter SDS, p-TSA, and stabilizer TiO2 are mixed in a mass ratio of 1:1:0.1.

[0170] After the methane hydrate is completely decomposed, the kinetic promoting component is added to the reactor in one batch through the injection pump, and the amount is 0.2wt% of the water amount of the system.

[0171] Phase four, through observation of the reactor, it is found that the induction time of methane hydrate generation is 7.7 min, and the system pressure is 6192 kPa and 5608 kPa at 30 min and 120 min after generation, respectively, and the gas storage capacity is 0.0630 mol / mol.

[0172] Other places not mentioned are the same as in Example 1.

[0173] Example 12

[0174] The object of this example is the No. 3 alcohol-containing sewage sample.

[0175] Phase one, determine the phase equilibrium condition of the alcohol-containing sewage to generate methane hydrate.

[0176] Phase two, add thermodynamic neutralizing component to adjust the phase equilibrium condition of the system.

[0177] In this example, the thermodynamic neutralizing component used is a mixture of tetrahydrofuran and cyclopentane in a volume ratio of 1:1.

[0178] The object of this example is the No. 3 alcohol-containing sewage sample, and the thermodynamic neutralizing component is added in batches, with a total of 0.7 ml. 46 min after the second addition, hydrate began to appear in the reactor, and 2 h later, part of the methane hydrate was observed to be generated on the reactor wall and the gas-liquid interface, proving that the system's thermodynamic phase equilibrium condition adjustment was successful.

[0179] Phase three, add kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system

[0180] Among the kinetic promoting components used, the kinetic promoter SDS, p-TSA, and stabilizer TiO2 are mixed in a mass ratio of 1:1:0.1.

[0181] After the methane hydrate is completely decomposed, the kinetic promoting component is added into the reactor by the injection pump at one time, and the amount is 0.3wt% of the water amount of the system.

[0182] In the fourth stage, it is found by the reactor observation that the induction time of the hydrate formation is 6.3min, the system pressure is 6045kPa and 5583kPa respectively at the 30th min and the 120th min after the formation, and the gas storage amount is 0.0643mol / mol.

[0183] The other places not mentioned are the same as those in Example 11.

[0184] Example 13

[0185] The object of this example is the No. 3 alcohol-containing sewage sample.

[0186] In the first stage, the phase equilibrium condition of the alcohol-containing sewage for forming the methane hydrate is determined.

[0187] In the second stage, the thermodynamic neutralizing component is added to adjust the phase equilibrium condition of the system.

[0188] In this example, the thermodynamic neutralizing component used is a mixture of tetrahydrofuran and TBAB with a mass ratio of 1:1.

[0189] The object of this example is the No. 3 alcohol-containing sewage sample, and the thermodynamic neutralizing component is added in batches, and a total of 0.8ml is added. 49min after the third addition, hydrate begins to appear in the reactor, and part of the methane hydrate is observed to be formed on the reactor wall and the gas-liquid interface after 2h, which proves that the adjustment of the thermodynamic phase equilibrium condition of the system is successful.

[0190] In the third stage, the kinetic promoting component is added to adjust the hydrate formation rate and the gas storage amount of the system.

[0191] In the kinetic promoting component used, the kinetic promoter SDS, the water-soluble hydroxyethyl cellulose and the stabilizer SiO2 are mixed with a mass ratio of 1:1:0.2.

[0192] After the methane hydrate is completely decomposed, the kinetic promoting component is added into the reactor by the injection pump at one time, and the amount is 0.5wt% of the water amount of the system.

[0193] In the fourth stage, it is found by the reactor observation that the induction time of the hydrate formation is 4.2min, the system pressure is 6011kPa and 5458kPa respectively at the 30th min and the 120th min after the formation, and the gas storage amount is 0.0707mol / mol.

[0194] The other places not mentioned are the same as those in Example 11.

[0195] Example 14

[0196] The sample of this example is the No. 3 alcohol-containing wastewater sample.

[0197] Stage one, determine the phase equilibrium conditions of the alcohol-containing wastewater for generating methane hydrate.

[0198] Stage two, add the thermodynamic neutralizing component to adjust the phase equilibrium conditions of the system.

[0199] In this example, the thermodynamic neutralizing component used is a mixture of tetrahydrofuran and TBAB in a mass ratio of 1:2.

[0200] The sample of this example is the No. 3 alcohol-containing wastewater sample, and the thermodynamic neutralizing component is added in batches, with a total of 0.9 ml. 31 min after the fourth addition, hydrate began to appear in the reactor, and 2 h later, part of the methane hydrate was observed to be generated on the reactor wall and the gas-liquid interface, proving that the thermodynamic phase equilibrium conditions of the system were successfully adjusted.

[0201] Stage three, add the kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system

[0202] In the kinetic promoting component used, the kinetic promoter p-toluenesulfonic acid, polyvinyl alcohol, and stabilizer SiO2 are mixed in a mass ratio of 1:1:0.1.

[0203] After the methane hydrate is completely decomposed, the kinetic promoting component is added to the reactor in one batch through the injection pump, and the amount is 0.8 wt% of the water amount of the system.

[0204] Stage four, through the observation of the reactor, it is found that the hydrate generation induction time is 3.3 min, and the system pressures at the 30th min and the 120th min after generation are 5934 kPa and 5386 kPa, respectively, and the gas storage capacity is 0.0745 mol / mol.

[0205] Other places not mentioned are the same as in Example 11.

[0206] Example 15

[0207] The sample of this example is the No. 3 alcohol-containing wastewater sample.

[0208] Stage one, determine the phase equilibrium conditions of the alcohol-containing wastewater for generating methane hydrate.

[0209] Stage two, add the thermodynamic neutralizing component to adjust the phase equilibrium conditions of the system.

[0210] In this example, the thermodynamic neutralizing component used is a mixture of dioxolane and cyclopentane in a mass ratio of 1:1.

[0211] The example object is a 3# alcohol-containing sewage sample, and the thermodynamic neutralizing component is added in batches, a total of 0.9ml, 46min after the fourth addition, hydrate begins to appear in the reactor, and 2h later, part of the methane hydrate is observed to be generated on the reactor wall and the gas-liquid interface, proving that the system thermodynamic phase equilibrium condition adjustment is successful.

[0212] Stage three, add kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system

[0213] The kinetic promoting component used is a mixture of kinetic promoter SDS, polyvinyl alcohol and stabilizer SiO2 in a mass ratio of 1:0.5:0.1.

[0214] After the methane hydrate is completely decomposed, the kinetic promoting component is added to the reactor in one batch through the injection pump, and the amount is 1.0wt% of the water amount of the system.

[0215] Stage four, through the observation of the reactor, it is found that the hydrate generation induction time is 3.1min, and the system pressures at 30min and 120min after generation are 5931kPa and 5337kPa respectively, and the gas storage capacity is 0.0770mol / mol.

[0216] Other places not mentioned are the same as in Example 11.

[0217] Comparative Example 1

[0218] This comparative example uses the same device as in the above examples to evaluate the performance, 10ml of deionized water is prepared, the experimental pressure is 6.5MPa, the experimental temperature is 0.5℃, the temperature of the reactor is kept constant, and methane gas is introduced into the reactor to 6.5MPa, through the reactor, it is found that the induction time of hydrate is 6.3min.

[0219] From the appearance of hydrate particles in the system, the system pressures at 30min and 120min are 6288kPa and 5727kPa respectively, and the gas storage capacity is 0.0568mol / mol.

[0220] Comparative Example 2

[0221] Take 10ml of 1# alcohol-containing sewage sample and add it to the reactor, adjust the experimental temperature to 0.5℃, and the experimental pressure to 3.75MPa, no hydrate is generated within two hours.

[0222] Increase the experimental pressure to 6.5MPa, and through the observation of the sapphire reactor, it is found that the induction time of hydrate generation is 27min, the system pressures at 30min and 120min are 6349kPa and 6043kPa respectively, and the gas storage capacity is 0.0401mol / mol.

[0223] Comparative Example 3

[0224] Take 10ml of 2 alcohol-containing sewage sample into the reaction kettle, adjust the experimental temperature to 0.5℃, the experimental pressure is 3.75MPa, no hydrate is generated within two hours.

[0225] Adjust the experimental pressure to 6.5MPa, through the sapphire reaction kettle observation found that no hydrate is generated within 12 hours, comparative example 4

[0226] Take 10ml of 3 alcohol-containing sewage sample into the reaction kettle, adjust the experimental temperature to 0.5℃, the experimental pressure is 3.75MPa, no hydrate is generated within two hours.

[0227] Adjust the experimental pressure to 6.5MPa, through the sapphire reaction kettle observation found that the hydrate generation induction time is 53min, the system pressure is 6372kPa and 6203kPa respectively at the 30min and 120min, the gas storage capacity is 0.0316mol / mol.

[0228] Comparative analysis of the examples and comparative examples, the comparative results of examples 1-5, 6-10, 11-15 and comparative examples 1-4 are shown in table 2.

[0229] Table 2 is the results of examples and comparative examples

[0230]

[0231] From table 2, according to the hydrate induction time and hydrate gas storage capacity of examples 1-5, 6-10, 11-15, it can be seen that with the increase of the amount of kinetic promoting component, the hydrate generation induction time is shortened, and the hydrate gas storage capacity is increased within 2h. The sewage system using the method also has certain improvement compared with the pure water system.

[0232] Comparative examples 1-4 are not added with thermodynamic neutralizing component and kinetic promoting component during preparation. Comparative example 1 is pure water without the action of reagent, the hydrate generation condition, the hydrate induction time is relatively long, and the hydrate gas storage capacity is not as much as examples 1-15. Comparative examples 2-4 are respectively using 1, 2 and 3 alcohol-containing sewage, but without adding thermodynamic neutralizing component and kinetic promoting component, the hydrate induction time is very long, and even cannot be realized, even if the induction is successful, the hydrate gas storage capacity is also very low. It is shown that without using the method provided by the application, the sewage system cannot generate or can only generate a small amount of hydrate slowly. It is further shown that the method provided by the application, examples 1-15, with the addition of thermodynamic neutralizing component and kinetic promoting component, the hydrate generation level basically reaches or even exceeds the pure water level.

[0233] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0234] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the spirit of the present application should also be within the scope of the present application.

Claims

1. A method for producing methane hydrates using alcohol-containing wastewater as a water source, characterized by, The specific process includes: Stage one, determining the phase equilibrium conditions of the alcohol-containing wastewater for generating methane hydrate; Stage two, adding a thermodynamic neutralizing component to adjust the phase equilibrium conditions of the system; by adding a thermodynamic neutralizing component to adjust the phase equilibrium conditions of the alcohol-containing wastewater system, the hydrate phase equilibrium pressure of the system is made to be the same as the pressure of pure water under the same temperature condition, and the difference between the two phase equilibrium pressures and the amount of the added thermodynamic neutralizing component are obtained; the hydrate thermodynamic neutralizing component is one or more of tetrahydrofuran, cyclopentane, dioxolane, and tetrabutylammonium bromide; Stage three, adding a kinetic promoting component to adjust the hydrate generation rate and gas storage capacity of the system; the kinetic promoting component is compounded from a kinetic promoter and a stabilizer; the kinetic promoter is one or more of sodium dodecyl sulfate, p-toluenesulfonic acid, water-soluble hydroxyethyl cellulose polymer, and polyvinyl alcohol; Stage four, observing, recording, and testing the hydrate generation process of the system.

2. The method of claim 1, wherein the alcohol-containing wastewater is used as a water source to produce methane hydrates. The alcohol-containing rate of the alcohol-containing wastewater is not higher than 20 vol%.

3. The method of claim 2, wherein the alcohol-containing wastewater is used as a water source to produce methane hydrates. In the stage one, the phase equilibrium conditions of the alcohol-containing wastewater for generating methane hydrate are determined by using a pressure search method, and the specific method is as follows: 10 ml of alcohol-containing wastewater is added to a reaction kettle, the temperature in the kettle is adjusted to a certain fixed value, when the temperature in the reaction kettle reaches the preset value, the temperature in the reaction kettle is kept unchanged, methane gas is introduced into the kettle so that the pressure is higher than the estimated phase equilibrium value by 1 MPa, after a large amount of hydrate is generated in the reaction kettle, the pressure is reduced to decompose the hydrate, when only a small amount of hydrate crystal exists in the reaction kettle, the temperature in the reaction kettle is kept unchanged, the pressure is reduced by 0.05 MPa, whether the hydrate is dissolved or not is observed, if not, the pressure is continuously reduced by 0.05 MPa until the hydrate is completely dissolved, at this time, the corresponding pressure is the phase equilibrium pressure under the temperature condition; The hydrate phase equilibrium pressure corresponding to different temperatures can be obtained.

4. The method of claim 2, wherein the alcohol-containing wastewater is used as a water source to produce methane hydrates. In the stage two, the following sub-steps are specifically included: (1) calculating the generation pressure of methane hydrate in a pure water system under the experimental temperature According to the phase equilibrium condition data obtained in the stage one, and the temperature and the loadable pressure of the reaction kettle, a suitable experimental temperature is selected, and according to the Chen-Guo model, the hydrate phase equilibrium pressure of the pure water system under the temperature condition is calculated; (2) adjusting the phase equilibrium conditions of the alcohol-containing wastewater system to be close to those of the pure water system The alcohol-containing wastewater is added to the reaction kettle, the experimental temperature is set to the temperature selected in the sub-step (1), the experimental pressure is higher than the hydrate phase equilibrium pressure of the pure water system calculated in the sub-step (1) by 1 MPa, the stirring is started, after the temperature and pressure are stable, a certain amount of thermodynamic neutralizing component is added to the system by using a dosing pump, after 2 h, if a large amount of hydrate is not generated, the thermodynamic neutralizing component is continuously added; The above steps are repeated until a large amount of hydrate is generated in the system, which means that the amount of the added thermodynamic neutralizing component has adjusted the hydrate phase equilibrium pressure of the system to the level of the pure water system under the same temperature; (3) increasing the temperature of the system to completely decompose the hydrate in the reaction kettle.

5. The method of claim 4, wherein the alcohol-containing wastewater is produced from the fermentation of biomass. The temperature range of the experiment is 0-5℃, and the pressure range is 0-8MPa.

6. The method of claim 2, wherein the alcohol-containing wastewater is generated from a fermentation process. In the third stage, the kinetic promoting component is added according to the water content of the alcohol-containing wastewater in the system.

7. The method of claim 6, wherein the alcohol-containing wastewater is generated from a source of wastewater containing alcohol. The kinetic promoting component is 0.05%-1.0% of the water content of the initial alcohol-containing wastewater in the system.

8. The method of claim 1, wherein the alcohol-containing wastewater is generated from a source of alcohol-containing wastewater. The mass ratio of the kinetic promoter and the stabilizer is 1:0.05-2.

9. The method for generating methane hydrate using alcohol-containing wastewater as a water source according to claim 1, characterized in that, Among them, The molecular weight of the water-soluble hydroxyethyl cellulose polymer is 90000.

10. The method for generating methane hydrate using alcohol-containing wastewater as a water source according to claim 1, characterized in that, The stabilizer is one or both of silicon dioxide and titanium dioxide.

11. The method of claim 2, wherein the alcohol-containing wastewater is generated from a source of alcohol-containing wastewater. In the fourth stage, the hydrate formation process of the system is tested and verified, specifically: Recooling to the temperature set in the second stage experiment, keeping the stirring open, verifying the hydrate formation, in order to more accurately and effectively verify the thermodynamic and kinetic effects of the additive on the hydrate formation, the pressure is adjusted to 6.5MPa in this stage; After the hydrate starts to form, record the induction time and pressure change.

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