RU-2861458-C1 - METHOD FOR INCREASING EFFICIENCY OF METHANE HYDRATE SYNTHESIS IN HIGH-PRESSURE REACTOR

RU2861458C1RU 2861458 C1RU2861458 C1RU 2861458C1RU-2861458-C1

Abstract

FIELD: gas industry. SUBSTANCE: transportation of natural gas in the form of solid gas hydrates is a promising direction that allows the transport of combustible gas at lower energy costs, as well as with increased transportation safety. Another application is associated with the co-combustion of natural gas hydrate with oil refining waste and coal slurry. A method for increasing the efficiency of methane hydrate synthesis in a high-pressure reactor consists in placing in the high-pressure reactor an aqueous solution containing sodium dodecyl sulphate with a mass concentration of 0.1% and carbon nanotubes with a mass concentration of 0.1%. The solution is stirred using a magnetic stirrer rotating at a speed of 200 rpm for 30 minutes, then methane is supplied to the reactor. EFFECT: increasing the uniformity of the composition, reducing aggregates, and increasing the rate of methane hydrate synthesis. 1 cl, 1 dwg

Inventors

Misiura Sergei Iakovlevich
MOROZOV VLADIMIR SERGEEVICH

Dates

Publication Date: 20260505
Application Date: 20251001

Claims (1)

A method for increasing the efficiency of methane hydrate synthesis in a high-pressure reactor, characterized in that an aqueous solution containing sodium dodecyl sulfate with a mass concentration of 0.1% and carbon nanotubes with a mass concentration of 0.1% is placed in the high-pressure reactor, the solution is stirred using a magnetic stirring device rotating at a rotation speed of 200 rpm for 30 minutes, and then methane is fed into the reactor.

Description

Transporting natural gas in the form of solid gas hydrates is a promising approach, allowing for the transport of flammable gas with lower energy costs and increased safety of transportation both in large sea tankers and by land. Another application involves the co-combustion of natural gas hydrate with oil refining waste and coal sludge [K. Vinogrodskiy, P.S. Nagibin, S.Y. Misyura, V.S. Morozov, N.E. Shlegel, P.A. Strizhak, Methane hydrate regasification to intensify the combustion of low-rank coal fuels, Fuel 381 (2025) 133432]. The addition of gas hydrate improves combustion efficiency and reduces the concentration of harmful emissions. Increasing the rate of hydrate growth is important for reducing the cost of the entire fuel combustion cycle, from synthesis, mixing, and combustion in the furnace. Reducing the cost of synthesizing natural gas hydrate or methane hydrate (natural gas consists primarily of methane) is a key requirement for increasing the profitability of the entire technology. Currently, challenges remain in synthesizing gas hydrate in large-volume reactors. The resulting gas hydrate has a heterogeneous composition with fairly large aggregates, which reduces the methane concentration in the gas hydrate state. It is also necessary to reduce the time it takes to synthesize methane hydrate in a large-volume reactor. After the initial rapid synthesis in the reactor, a long period of synthesis with a flat pressure curve ensues, during which the resulting large aggregates (large pieces of gas hydrate) become coated with a gas hydrate crust, which impedes mass transfer and reduces the degree of water conversion to gas hydrate. To improve the efficiency of synthesis, surfactants were previously used in a static method (without mechanical stirring) [Lin W., Chen G.J., Sun C.Y., Guo X.Q., Wu Z.K., Liang M.Y., Chen L.T., Yang L.Y., Effect of surfactant on the formation and dissociation kinetic behavior of methane hydrate, Chem. Eng. Sci. 59 (2004), doi:10.1016/j.ces.2004.07.010], as well as the use of a stirrer [Sergey Misyura, Vladimir Morozov, Pavel Strizhak, Nikita Shlegel, Igor Donskoy, Effect of surfactants on the synthesis and dissociation of gas hydrates, Fire 7(7) (2024) 240, doi.org/10.3390/fire7070240]. However, these methods are not effective enough to ensure compositional homogeneity and high conversion rates. The proposed method, which combines a surfactant (SDS – sodium dodecyl sulfate), carbon nanotubes, and mechanical rotation of the liquid, improves compositional homogeneity, reduces gas hydrate aggregates, and increases the synthesis rate. A method and device for synthesizing gas hydrates are known (patent CN 114702995, 2022, B01J3/04; C10L3/10). The method closest in essential features to the claimed one is the method of accelerated formation of methane hydrate using a composite hydrogel based on carbon nanotubes (patent CN 112625769 A, 2020, C01B32/168 (CN); C10L3/108 (CN). The disadvantages of these solutions are that during gas hydrate synthesis, a non-uniform composition is formed due to the uneven supply of gas hydrate to the entire volume of liquid and a low degree of water conversion into gas hydrate, as well as the difficulty of scaling up gas hydrate synthesis to large working volumes in a high-pressure chamber (tens of liters). Technical result: increased homogeneity of composition, reduction of aggregates and increase in the rate of methane hydrate synthesis. The technical result is achieved by placing an aqueous solution containing sodium dodecyl sulfate with a mass concentration of 0.1% and carbon nanotubes with a mass concentration of 0.1% into a high-pressure reactor, the solution is stirred using a magnetic stirring device rotating at a rotation speed of 200 rpm for 30 minutes, and then methane is fed into the reactor. Fig. 1 shows a diagram for organizing the synthesis of methane hydrate (or natural gas hydrate), where: 1 - thermostat; 2 - liquid from the thermostat for cooling the walls of the reactor working chamber; 3 - high pressure gaseous methane; 4 - an aqueous solution containing sodium dodecyl sulfate and carbon nanotubes; 5 - pressure measuring device (analog-digital pressure meter with data transfer to a PC for controlling the pressure in the reactor); 6 - pressure gauge for visual observation; 7 - temperature measuring device (analog-digital temperature meter with data transfer to a PC for temperature control in the reactor); 8 - thermocouple (data from the thermocouple is sent to the converter (7); 9 - PC; 10 - high-pressure cylinder with gaseous methane; 11 - high-pressure reactor for methane hydrate synthesis; 12 - magnetic stirring device. Example of the method implementation After pouring an aqueous solution (4) into the working chamber of the reactor (11), the temperature of the coolant (2) in the thermostat (1) was set to -2 °C to maintain the water temperature in the reactor itself at 0 °C. Next, the electric motor was started, which drove the m