A method of liquefaction of natural gas

 

(57) Abstract:

Natural gas high pressure at a temperature of 270-300K divided into two streams, one of which (main) send in a preliminary heat exchanger, and the other in a vortex tube. Chilled in the preliminary heat exchanger main thread served in the recuperative heat exchanger where its temperature is additionally reduced due to heat exchange with return flow neskondensirovannyh gas, and then into the throttle. After throttling the resulting liquid phase is collected in the condensate, and gas after a recuperative heat exchanger combined with the flows coming out of the vortex tube. Introduction to the cycle of the vortex tube increases the coefficient of liquefaction in comparison with throttle cycle 28 - 46%. 2 Il.

The present invention relates to cryogenic engineering, in particular to a method of liquefaction of natural gas.

To obtain liquefied natural gas are widely used throttle liquefaction cycles with different methods of pre-cooling the natural gas (GHG) emissions.

Briey, these processes can be described as cycles open type with the use of regenerative heat exchangers, tunic fluid. After the heat exchanger the cold flow of high pressure gas is choked, the liquid phase of low pressure is removed from accumulator and netizenry gas low pressure (near atmospheric) after recovery of the cold in the heat exchanger are also derived from the installation.

The maximum ratio of liquefaction is achieved in cascade refrigeration circuits, where the external refrigerant for direct cooling of the gas stream used individual hydrocarbons or mixtures thereof. Due to the use of complex, costly and energy-intensive equipment such methods of liquefaction are profitable only when large-scale production, measured in the millions of tons/year. The same drawback (the necessity of using complex and expensive equipment) inherent in the installations of low and medium productivity using the technological scheme using the internal circulation of refrigerant circuits, which are based on the principle isoentropic extension part of the expected flow of gas between the expansion units (cycle of Galanta and its variants).

For facilities engaged in the reduction already predvaritel can be applied to the most simple process of liquefaction - classic butterfly cycle. Liquefaction in it based solely on regenerative waste direct flow of high pressure gas cold nscontainerframe part of the expected flow [1] (prototype). Technologically it is the cooling of gas in a regenerative heat exchanger, a throttling and separating the resulting liquid-vapor mixture in the condensate with the withdrawal of the vapors in the recuperative heat exchanger, and the fluid consumer.

The method has several advantages (low cost, ease of implementation, reliability), but is characterized by a low coefficient of liquefaction. The increase of the coefficient of liquefaction is usually achieved by introducing into a cycle of additional sources of cooling capacity.P CLASS="ptx2">

We propose a method of liquefaction of GHGs in the throttle loop using the internal cooling circuit, on the basis of the process energiesparende flow of GHGs in the vortex tube (VT) [2]. Operational and cost characteristics W much cheaper than between the expansion units and devices. Compared to the classic throttle cycle the inventive method allows to significantly increase the coefficient of liquefaction PG.

Principal), it is divided into two streams, flows, respectively, in the preliminary heat exchanger (main part) and in a vortex tube.

From the vortex tube cold gas component (point 3) reverse current is sent in a preliminary heat exchanger, and hot (point 4) is output from the setting circuit and combined with the cold component, last preliminary heat exchanger (point 1).

Chilled in the preliminary heat exchanger high-pressure gas (point 6) passes through the regenerative Teploobmennik, where its temperature is additionally reduced (point 7) due to heat exchange with return flow neskondensirovannyh (point 9) after throttling (point 8) gas.

Finally the residual cold of the reverse gas flow (point 10) utilizada in the preliminary heat exchanger in the heat exchange with the direct flow of high pressure gas.

The output parameters of the condensate liquid is characterized by a point (0).

To confirm the possibility of carrying out the invention below is its design rationale.

It is known [2] that the maximum of Qoreaches at a relative fraction of cold gas stream (), leaving Euby is:

i2+Q0=*i1+(1-)*i4(1)

where i1the enthalpy of the output stream of the pre-heat exchanger;

i2- enthalpy input stream into a vortex tube (VT);

i4the enthalpy of the output stream from WATTS.

Formally write equation (1) is being applied in W 1 kg of compressed gas.

The value of Qocan be calculated by the ratio:

Q0=*(i2-i3) =**andd(i2-i3s) (2)

where the expenditure ratio;

= 0.6 - cold stream;

(1 - ) = 0.4 - hot stream;

hell- factor approximation to the adiabatic process;

i3sthe enthalpy of the gas at constant entropy, obtained with PIand TI.

For most of vortex tubes (tubes Wound) coefficient valuehellis in the range 0.4-0.45.

In further calculations we will assume it ishell= 0.45.

Under the assumed conditions, according to equation (2) is easy to calculate the value of the enthalpy of the gas at the point 3, and to determine and temperature of gas leaving W - T3.

i3= i2-*andd(i2-i3s) (3)
him heat balance calculation of the heat exchanger core.

Assuming it is served G kg main stream of compressed gas.

Accept also that the temperature at point 6 on the value of the 5ohigher values of the temperature of the cold gas at the outlet of BT - point 3.

T6=T3 + 5 (4)

It is easy to find the absolute value of the enthalpy of the compressed stream at a point 6 - i6.

Assuming the equality of the temperatures at the points T10and T6have:

< / BR>
where GWthe liquid fraction formed from a stream of compressed gas when the throttle (ideal throttle cycle).

Then

< / BR>
The absolute value of G can be found by solving the equation of heat balance of work preliminary heat exchanger, recorded somewhat differently than it was considered earlier (equation 1).

G*(i2-i6) =*(i1-i3)+(G-GW)*(i1-i10). (7)

Taking into account the fact that the vortex tube we conventionally was sent to 1 kg of the working gas, the total amount of compressed gas received in the liquefaction system is determined by the equation:

G = 1+g (8)

Then the overall ratio of liquefaction GHG installation can be calculated by the ratio:

< / BR>
Weighting is obtained by the equation (9) is the energy efficiency of the proposed circuit designs liquefaction process GHG:

< / BR>
where

< / BR>
On the basis of the equation (10) integral assessment of the effectiveness of the proposed scheme liquefaction depending on the basic technological parameters of the gas at the entrance to the installation (inlet pressure and temperature), illustrated by the graph shown in Fig. 2.

From this it follows that in the range of input pressures from 6 to 3 MPa and temperatures of the gas from 270 to 300K proposed scheme liquefaction provides an appreciation of the real factor liquefaction PG against the ideal throttle cycle is not less than 28 - 46%.

The greatest efficiency is achieved in the case of "high" (290 - 300K) temperature of gas at the entrance to the installation.

References

1. Ivantsov O. M., Dvoirys A. D. Low-temperature gas. M., Nedra, 1980, S. 207 - 209

2. Dyskin L. M. Eddy thermostats and air. NNSU, N. Novgorod, 1991.

A method of liquefaction of natural gas, which consists in cooling the gas in the regenerative heat exchanger is not condensed in the cycle of natural gas, its throttling and separating the resulting liquid-vapor mixture in the condensate, characterized in that the source of the natural gas stream at a temperature of 270-300K divided into two parts, one of quuu pipe, where the resulting cold stream is sent to a preliminary heat exchanger for further cooling the main part of the expected stream of natural gas.

 

Same patents:

The invention relates to methods and devices that use the cooling effect of the gas during its expansion for gas liquefaction

The invention relates to cryogenic equipment, i.e

The invention relates to cryogenic technique and can be used for the liquefaction of natural and other gases, as well as in all cases where you want to obtain low temperatures in the presence of compressed gas

The invention relates to cryogenic equipment, in particular, to the liquefaction of gases emitting components of the stream, and in all cases where you want to liquefy gas and to separate multicomponent stream

The invention relates to the field of cryogenic engineering and most can be effectively used in liquefaction of nitrogen in large production

The invention relates to refrigeration, and is intended for the effective use of a vortex effect in the vortex tubes

The invention relates to a rotary apparatus for sharing media with inhomogeneous field densities and with different molecular weight components, which is carried out in accordance with the law of freely rotating vortex flow with inhomogeneous field densities and with different molecular weight components, open the author in 1994, and can be used for its intended purpose to highlight the combustible component of the air, and it is also possible to use the installation for its implementation in different variants constructive installation for the separation of environments in a vortex flow in various industries, particularly the chemical industry, thermal and nuclear energy, oil and gas production and processing industry and many industries

The invention relates to the separation media with inhomogeneous field densities and with different molecular weight components in the vortex units whose work is carried out in accordance with the law freely rotating vortex flow with inhomogeneous field densities and with different molecular weight components, open the author in 1994, and can be used for its intended purpose to highlight the combustible component of air, it is also possible to use the installation for implementation at different variants of constructive installation for the separation of environments in a vortex flow in the various branches of production, in particular, chemical industry, thermal and nuclear energy, oil and gas production and processing industry and many other industries

Vortex tube // 2052736
The invention relates to refrigeration, and in particular to installations using a vortex effect split the gas into hot and cold streams, and can be used in air-conditioning systems and drying of air and other gases

FIELD: mechanical engineering.

SUBSTANCE: proposed volute has body with spiral passage formed by spiral wall terminating in edge. One part of body where volute spiral is located is lesser than other part where inlet passage is located.

EFFECT: improved energy separation process; enhanced operational efficiency.

1 dwg

FIELD: power engineering; heat and power generation; temperature variation of liquid or gas flow.

SUBSTANCE: additional electrical energy picked off electromagnetic windings is produced by conversion of energy of liquid flow in vortex tube. Electromagnetic windings are disposed on case. The latter is grounded and is made of insulating material whose dielectric constant is higher than that of liquid.

EFFECT: enhanced operating effectiveness and enlarged functional capabilities of vortex tube.

16 cl, 1 dwg

FIELD: compression refrigeration systems.

SUBSTANCE: method comprises supplying gas tangentially to the surface of the chamber for energy separation, generating axial flow, and inducing rarefaction in the aperture of the cold end due to force generated in its rotation. The vortex pipe has accelerating device made of, e.g., a tangential nozzle with scroll casing, separation chamber, throttle, and aperture of the cold end. The aperture is mounted on bearings for permitting rotation.

EFFECT: enhanced efficiency.

7 cl, 3 dwg

FIELD: processes or apparatus for liquefying.

SUBSTANCE: method comprises flowing gas through one or two recuperative heat exchangers connected in series where the gas cools and low-boiling components are condensed and frozen, flowing the gas through a gas-expansion machine and/or an air throttle to the cold receiver. A part of the straight gas flow is branched into the cold and hot flows inside the energy separator made of, e.g., a two-flow vortex pipe. The cold flow is mixed with the return flow at the inlet to the heat exchanger. The hot flow is directed to the straight passage of the nonoperating recuperative heat exchanger-freezer.

EFFECT: enhanced efficiency.

2 cl, 3 dwg

FIELD: refrigeration industry; methods of operation of the vortex refrigerator.

SUBSTANCE: the invention is pertaining to the field of refrigeration industry, in particular to the method of operation of the vortex refrigerator and to the vortex refrigerator. The method of operation of the vortex refrigerator provides for feeding of a compressed gas into a vortex pipe and the gas separation for a cold stream and a hot stream. The cold stream is again feed back into the vortex pipe through an additional connecting pipe located in a choke of the hot end and directed along the axis of the chamber of the power separation opposite to the hot stream of the vortex pipe. The compressed gas is fed into the vortex pipe give from an outside source. The vortex refrigerator contains a vortex pipe with the inlet cold and hot connecting pipes, and also a choke of the hot end. The cold connecting pipe is connected to the additional connecting pipe located in the choke of the hot end and directed along the axis of the chamber of the power separation opposite to the hot stream of the vortex pipe. Usage of the invention allows to simplify the design of the vortex refrigerator.

EFFECT: the invention ensures simplification of the design of the vortex refrigerator.

3 cl, 2 dwg

FIELD: refrigeration industry; a method of operation of a temperature transformer.

SUBSTANCE: the invention is pertaining to the field of refrigeration industry, in particular, to the method of operation of the temperature transformer. The method of operation of the temperature transformer provides for a swirling of a gas stream, feeding of the swirled stream into the energy exchange chamber, formation of an axial stream due to feeding of a cooled stream in the channel of the axial stream and provision of the energy exchange of the swirled stream with the axial stream. The cooling conduct in the chamber of the energy exchange due to evaporation of the liquid through the porous wall located coaxially to the chamber of the energy exchange. Realization of the invention will allow to raise efficiency of the temperature transformer.

EFFECT: the invention ensures an increased efficiency of the temperature transformer.

9 cl, 2 dwg, 2 tbl

Up!