The method of processing gas containing methane and at least one higher hydrocarbon and water

 

(57) Abstract:

The invention relates to the dehydration of natural gas. The processed gas is divided into two streams (1) and (2). Thread (2) is brought into contact with the recirculating liquid phase containing water and a solvent, to obtain aqueous liquid phase depleted in solvent, and gas phase containing the solvent, which is shared by the defense. The resulting aqueous phase is brought into contact with one of the two original gas streams that do not contain solvent, while the solvent is extracted from the depleted aqueous phase gas and the result is enriched solvent gas phase and the regenerated aqueous liquid phase. The gas flow (1) depleted solvent is mixed with the gas phase after phase contacting. The gas mixture is cooled from the partial condensation of the water phase containing the solvent and the hydrocarbon phase from the final treated gas from which you have removed the water and higher hydrocarbons. The aqueous phase containing the solvent, recycle in the system. The technical result is reached dehydration of natural gas with simultaneous separation of impurities higher hydrocarbons while reducing energozatratnogo methane, at least one higher hydrocarbon and water to remove water and extraction of higher hydrocarbons (higher hydrocarbons).

The method according to the invention allows optimal to processing natural gas dehydration and separation of at least part of the condensed hydrocarbons contained in natural gas, through a streamlined and integrated way.

Petroleum products and, in particular, natural guise, and the other containing a hydrocarbon gas, such as gases from refineries, contain products that are undesirable for their transportation and/or manipulation.

Of such products removed one of the main component is water, which is a promoter hydrate and promote corrosion, especially when the oil contains acid components, such as H2S and/or CO2. Hydrates can cause driving the transporting pipelines, and correlating the effects of acid gases contained in natural gas, leads to bad piping, processing equipment and impairment of natural gas to consumers.

These two phenomena leogardo.

The processing gas may further include a stage of extraction of higher hydrocarbons, such as liquid natural gas (LGN), containing fraction GPL and gasoline.wow fraction (5+). This stage aims at the establishment of such a dew point of hydrocarbons, eliminating condensation hydrocarbon fraction during transportation of gas, or the trapping of liquid hydrocarbon fraction LGN, more easily recyclable than the processed gas.

For the processing of natural gas in prior art describes various methods.

In French patent FR-B-2605241 described processing method using physical chilled solvent, allowing complex operations to natural gas processing: dehydration, separate or in combination with extraction of higher hydrocarbons and/or deoxidation of the specified gas in the case of a content of acid components.

In French patent FR-B-2636857 it is shown that if the process stage of separation of higher hydrocarbons (LGN) recovery of the solvent can be more effective through the use stage of leaching liquid hydrocarbons water formed by the dehydration of gas.

In the publication "Integrated Natural Gas Treatment: Gained Industrial Experience with IFPECSOL Process" (Full processing of natural gas: increased experience in industrial application of the process Ipicol), S. Patel, A. Mankinen, J. Lara and J. F. Levie presented on IGCR 95 in Cannes (France) in November 1995, describes in particular a method of water washing liquid hydrocarbon phase to remove at least part of the contained solvent.

The figure 1 shows the method described in the above publication and intended for processing gas containing methane, water, at least one condensed hydrocarbons and possibly acidic components. The method consists in the following.

Processed natural gas is delivered by pipeline 1. Part or all of this gas quantity is put in contact in the contact zone G1 formed, for example, a nozzle, with a mixture of solvent and water is supplied through pipe 2.

Solvent used may be selected from the set consisting of methanol, ethanol, propanol, methylpropional ether, ethylpropyl ether, dipropyl the applied solvent is methanol.

Solvent gas phase is removed at the head of the pipeline 3. In the lower part of the pipe 4 is devoting substantially freed from solvent aqueous phase.

It should be noted that the method of processing can be optimized by adaptation of part of the gas fed to the contact zone G1, and part of the gas leaving the contact zone, taking into account the composition of the treated gas and the required performance. This optimization is shown in figure 1 by the dotted line, you can directly mix the processed part coming through the pipeline 18 gas with the gas discharged via line 3 from the contact zone. Part of the gas is not coming in the contact zone can be, for example, from 0 to 50% of the number of processed gas.

The gas phase head part containing water and a solvent, most often, is in the saturation state. It is cooled in the heat exchanger E1 refrigerant so as to allow condensation of the aqueous phase of a solvent and a liquid hydrocarbon phase. Indicated that the amount of solvent entrained in the aqueous phase at the exit of the contact zone G1, may be sufficient to prevent difficulties SV is and to compensate for losses of solvent in the treated gas, in the liquid hydrocarbon fraction (LGN) and possibly in the water discharged through the pipeline 19. On the same pipe 19 may be effected by the descent of the stream in order to maintain a constant amount of solvent and water in the circuit.

The resulting mixture of gas and liquid phase is withdrawn from heat exchanger E1 via the pipeline 6. Both liquid phase and gaseous phase are separated in the vessel B1.

Dehydrated processed gas output from the specified container through the pipeline 7. Both the liquid phase resulting from the condensation are separated by settling in the bottom of the tank Bl.

The aqueous phase formed mainly of water and solvent, is withdrawn from the vessel Bl via the pipeline 8. Pump P1 allows the re-injection of the indicated aqueous phase through the pipeline 9 in the pipe 2, then the surface area of Gl.

The hydrocarbon phase formed mainly condensed hydrocarbons natural gas (Sz+) (containing possibly dissolved ethane and methane) and the solvent can be discharged through the pipeline 10 in the path of stabilization and washing. This redistribution can be carried out heat exchange between the gas received from contaet the supply of liquid hydrocarbons by pipeline 11 in column S1 stabilization. The purpose of this operation is to separate from the named liquid hydrocarbon phase is the most volatile component (C1and C2drawn from the process through the pipeline 12. The hydrocarbon phase with components having a molar mass of more than2, is sent through a pipeline 13 in the area of water washing G2 to remove the contained solvent.

The aqueous phase derived from the contact zone G1 in line 4 and purified at least in part on the solvent enters the pump P3. Part of this aqueous phase with a controlled flow is directed into the contact zone G2 through the pipeline 14. The other part is discharged through line 19.

In the specified contact zone G2 part of the aqueous phase, received on line 14, allows the washing of the hydrocarbon phase. The solvent is characterized by a great affinity with water than with the hydrocarbon phase, is captured at least partially in the aqueous phase at the end of this stage.

Liquid hydrocarbon phase, purified from the greater part of the solvent contained in it at the entrance to the contact area G2, is discharged through pipe 15.

Solvent liquid phase is removed from the contact areas of the AI solvent therein specified phase is served either in the contact zone G1 through the pipeline 17, or in the pipeline 2 for mixing with the aqueous phase coming from the vessel B1 through the pipeline 9.

Compared with previous methods, this method has significant advantages. It provides a significant gain in capitalstream, the dimensions and weight of the equipment, which is especially optimal for production of hydrocarbons at sea. In addition, the separation of water and solvent in contact with the treated gas eliminates the separation by distillation.

Object of the invention is a further reduction in capitalstream, size and weight equipment, as well as production costs for processing gas through the use of the method according to the invention.

Method and installation according to the invention are primarily designed for the dehydration of a gas, for example natural gas, which contains water and at least one high hydrocarbon, and to provide at least partial separation of condensed hydrocarbons.

In General, the method according to the invention can be considered as a method containing the following steps:

(a) the processed gas is divided into two streams (1) and (2). The hour is compulsory, to this number ranged from 30 to 50% of the total amount of gas;

b) at least stream (2) of the said gas is brought into contact with the recycled liquid phase containing both water and solvent, which are, as a rule, organic, non-hydrocarbon, normally liquid compound, which is water, is capable of at least partially mixed with water and subjected to distillation at a temperature below the temperature of distilled water. At this stage, the solvent is transferred mainly in the gas. At the exit of the contact zone receives water liquid phase depleted in solvent content in comparison with the recycled liquid phase and a gas phase with a solvent content;

C) share-depleted solvent content of an aqueous phase and solvent gas phase;

g) depleted content of the solvent the aqueous phase is brought into contact with the flow (1) of the processed gas that does not contain a solvent, in the contact zone, the residual solvent is extracted from the water depleted in the gas phase, at this stage formed by a gas phase rich in solvent content, and the regenerated aqueous liquid phase;

retell phase, formed in stage (b) or after stage (b) flow (2) gas, solvent free;

e) the gas phase mixture is cooled with the possibility of its partial condensation in aqueous and hydrocarbon phase, each of which contains a solvent, get treated gas from which you have removed at least partially water and higher hydrocarbons;

g) separate the aqueous phase and the hydrocarbon phase formed in stage (e) by sedimentation;

C) water-rich solvent phase, recyclery at stage (b) of the process.

If necessary, the hydrocarbon liquid phase can be stabilized and/or removed the solvent. With this purpose, the liquid hydrocarbon phase is directed to the stabilization column. When carrying out the stage of stabilization of the most volatile components (C1C2) hydrocarbon liquid phase removed from the process. The hydrocarbon phase with a content of higher connections than WITH2that is then in contact with the aqueous solvent phase, which may be fully or partially water formed in stage (g). At the end of the probe, which may be, for example, in a static mixer, not the content the fat phase is drained, and the aqueous phase contains a solvent recyclery to the step (b) and/or stage (g).

The invention in more detail is shown in the embodiments without leaving the scope of the invention, and not restrictive, and related to the processing of natural gas, with reference to the attached drawings.

In Fig. 1 shows the method according to the prior art.

In Fig. 2 and 3 schematically shows the method according to the invention, in particular, the improvement of the method known from the prior art, allowing to reduce the cross section and/or the height of the contact zone G1 due to the use in the installation of the mixer and separator, placed above the contact zone G1, and provides the initial exchange between the solvent-water solution and the whole amount or part of the treated gas.

Figure 2 shows the application of the method according to the invention.

Solvent-aqueous phase coming from the vessel B1 on line 8, is moved by the pump P1 through the pipe 9 into the mixer M21, also designed for bypass gas is supplied through pipe 18. During mixing of the gas is saturated with solvent. The two phases, water and gas, time is Truboprovod 21, mixed with gas from the contact zone G1, then sent via line 3 into the heat exchanger El.

Coming from the vessel B21 aqueous phase is purified from a portion of the solvent present therein at the outlet from the tank B1. It is fed by line 22 to the head portion of the contact zone G1. The concentration of solvent in the aqueous phase, circulating through the pipe 22, is significantly lower than the same concentration in the solution circulating through the pipe 9. Thanks for such a low concentration of cross-section and/or the height of the contact zone G1 is significantly reduced in comparison with the cross section and height, which are necessary for the method-analogue. In the case where the method comprises a stage of leaching high hydrocarbons, the aqueous phase formed during the washing and received via the pipe 17 may be filed in the contact zone G1 or mixed with the aqueous phase in the pipeline 22. The choice of the injection point of the aqueous phase is determined by the solvent content.

Because a smaller amount of solvent should move from the aqueous phase into the gas being in contact zone G1, dimensions of equipment for such contact is substantially reduced.

The following describes another variant is westline all the amount of produced gas, submitted by pipelines 3 and 18, is fed into the mixer M22. All the gas is mixed in the mixer M22 with water containing solvent solution coming from the vessel B1 and circulating through the pipe 9. Coming from the separation vessel B22 pipeline 23 gas is fed directly into the heat exchanger E1, and the aqueous phase coming from the vessel B22 pipeline 24, is pressed into the contact zone G1. As described above, in the case where the method comprises the stage of leaching high hydrocarbon, aqueous phase, formed during the washing and received via the pipe 17 may be submitted if necessary, in the contact zone G1 or mixed with the aqueous phase in the pipeline 24.

The solvent used in the method according to the invention may be selected from the set consisting of methanol, ethanol, propanol, methylpropional ether, ethylpropyl ether, DIPROPYLENE ether, ether metaltronica butyl, dimethoxymethane, dimethoxyethane and methoxyethanol. Most commonly used methanol.

The following example 1 illustrates the method is similar, examples 2 and 3 illustrate two separate variants of the method according to the invention.

Example 1. In this example, acts 6 MPa, temperature - 50oWith the composition shown in the table, gas vodonosen (water content at the input of the process is about 6000 ppm/mol). Its consumption is 108 t/h, which corresponds to 3.0 M standards. m3a day.

In this case, the solvent was methanol.

Half of the produced gas (50%) shall be sent through the pipeline 1 in the contact zone G1, the second half (50%) in the head part of the contactor through the pipeline 18. Contactor G1 contains structured nozzle. Recycled aqueous solution of methanol is pumped into the head portion of the contactor through the pipeline 2 at a temperature of -25oC. At the end of stage contact depleted solvent content water solution discharged from the contactor through the pipeline 4. The methanol content in this solution is 160 ppm weight. Its consumption is 245 kg/h; this flow rate corresponds approximately to the amount of water originally contained in the 108 t/h of treated gas.

Containing methanol gas is directed into the heat exchanger E1 via line 3. Pipeline 5 in it is the addition of methanol in the amount of 40 kg/h At the outlet of the heat exchanger E1, its temperature is -25oC. Capacity B1 allows to split yet 10,5 kg/M standards. m3;

the water content of methanol in the amount of 616 kg/h, recyclery in the contact zone G1;

- the flow is concentrated hydrocarbon phase (LGN) in the amount of 8400 kg/h, which if necessary can be stabilized, and then washed to remove solvent, before disposal.

Example 2. In this example, natural gas, at his place of receipt, has pressure, temperature, flow rate and composition as specified in example 1, but is treated by the method according to the invention, shown in Fig. 2. Additionally, the solvent used here is methanol.

In this example, the bypass gas from the pipeline 18 is brought into contact with an aqueous phase containing the solvent and from the separation vessel B1 via the pipeline 8 to the mixer M21. During this stage, the mingling of the gas filled with solvent.

The two phases, water and gas are separated in the separation vessel B21.

The gas containing the solvent and coming from the vessel B21 through the pipeline 21 is mixed with the gas flowing from the contact zone G1, then sent via line 3 into the heat exchanger El.

The aqueous phase from the tank B21 partially cleared from the solvent, S="ptx2">

In the initial contact between a gas and a rich solvent solution in the mixer M21 concentration of solvent in the aqueous solution is reduced by 2.5 times compared to the solution circulating through the pipeline 9.

Under other equal conditions performance characteristics identical to those described in example 1, obtained using the contact columns G1 reduced size. Indeed, the contacting aqueous solution, partially depleted in solvent content, with 44% of the processed gas is sufficient for the depletion of the solution.

When vipasyana 56% of the gas concentration of methanol in water, is withdrawn from the contactor through line 4, is 160 ppm weight. as described in example 1.

The depletion of the solution is achieved by using a column with a diameter reduced by 6% compared with the previous example. Weight reduction of steel elements as a result of such reduction of the diameter varies depending on the magnitude of the decrease.

The amount of required nozzles consequently also reduced by 12%; however, the tip height identical to the height of the nozzle in example 1.

Example 3. In this example, the natural gas at the location obtained the invention, presented in figure 3. In addition, the solvent used here is methanol.

According to this example, the portion of the processed gas is fed into contact zone G1 through the pipeline 1. As mentioned, gas, filled with solvent after contact, goes from G1 through the pipeline 3. It is mixed with the bypass gas, solvent in the pipeline 18. All the amount of gas mixed with recycled water-containing solvent solution in the mixer M22. The mixture is directed into the separation tank B22.

From the separation vessel B22 out in two phases:

gas content of the solvent is sent to a pipe 23 to the heat exchanger E1,

partially depleted aqueous solvent is supplied through pipe 24 in the contact zone G1.

In the initial contact between a gas and a rich solvent solution in the mixer M22 concentration of solvent in the aqueous solution is reduced by 3.5 times compared to the solution circulating through the pipeline 9.

Under other equal conditions performance characteristics identical to those described in example 1, obtained using the contact columns G1 reduced size. De is " gas is sufficient for the depletion of the solution.

When vipasyana 69% of the gas concentration of methanol in water, is withdrawn from the contactor through line 4, is 160 ppm weight. as described in example 1.

The depletion of the solution is ensured thanks to the use of columns with a diameter reduced by 21% compared with example 1. Weight reduction of steel elements as a result of such reduction of the diameter varies depending on the magnitude of the decrease.

The amount of required nozzles consequently also reduced by 38%; however, the tip height identical to the height of the nozzle in example 1.

Comparison of example 1 for the method-analogue, on the one hand, with examples 2 and 3 for the method according to the invention on the other hand, makes it obvious that the method according to the invention considerably reduces the contact section of the column and, as a consequence, the dimensions and weight equipment, as well as the amount of nozzles required for the processing gas.

The method according to the invention is characterized by the advantage due to lower capitalstream compared to the one described in prior art methods, a twofold decrease of the cross section of the contactor and the volume of the nozzle required for operations.

1. what about the it contains the following stages: a) the processed gas is divided into two streams (1) and (2); b) at least stream (2) of the said gas is brought into contact with the recycled liquid phase containing both water and solvent, which are, as a rule, organic non-normally liquid compound, which is water, is capable of at least partially mixed with water and subjected to distillation at a temperature below the temperature of distillation of water, with aqueous liquid phase depleted in solvent content in comparison with the recycled liquid phase and a gas phase containing solvent; C) share depleted content of the solvent is an aqueous phase and a solvent gas phase; g) depleted content of the solvent the aqueous phase is brought into contact with the flow (1) of the specified gas, solvent, while in the contact zone of residual solvent is extracted from the water-depleted phase of the processed gas and at this stage receive gas rich solvent phase and a regenerated aqueous liquid phase; d) rich solvent gas phase formed in stage (g), mixed with either gas containing solvent phase formed in stage (b) or after stage (b) since p is a possibility of its partial condensation in aqueous and hydrocarbon phase, each of which contains a solvent, and get treated gas from which you have removed at least partially water and higher hydrocarbons; and (g) water and hydrocarbon phase formed in stage (e), separated by sedimentation; C) water-rich solvent phase recyclery in stage (b).

2. The method according to p. 1, characterized in that in stage (a) the volume of gas in the stream (2) exceeds the amount of gas flow (1).

3. The method according to p. 1 or 2, characterized in that formed in stage (g) gas-rich solvent phase is mixed with the formed in stage (b) of the process gas rich solvent phase.

4. The method according to p. 1, characterized in that at the end stage of contact (in) all the amount of processed gas is brought into contact at the stage (b) with a rich solvent content of recycled water phase.

5. The method according to one of paragraphs. 1-4, characterized in that at the end stages of contact (b) and (g) in the gas phase is injected additive solvent to prevent the formation of hydrates at the stage of cooling (e) compensate for the loss of solvent in the treated gas.

6. The method according to one of paragraphs. 1-5, characterized the rum, ethylpropyl ether, DIPROPYLENE ether, ether methyltricyclo butyl, dimethoxymethane, dimethoxyethane and methoxyethanol.

7. The method according to p. 6, wherein the solvent is methanol.

8. The method according to one of paragraphs. 1-7, characterized in that recycled into stage (b) rich solvent content water phase contains 50 to 95 weight. % solvent.

9. The method according to one of paragraphs. 1-8, characterized in that the temperature of the gas phase at the end of stage (e) is from -15 to -80oWith and that the resulting gas at the end of stage (d) purified from most of the propane contained in the beginning of the process.

10. The method according to one of paragraphs. 1-9, characterized in that the volume of gas passed through the contact area on the stage (d) is 25 to 95% of the number of processed gas.

11. The method according to one of paragraphs. 1-9, characterized in that the volume of gas passed through the contact area on the stage (d) is 30 - 50% of the number of processed gas.

12. The method according to one of paragraphs. 1-11, characterized in that the hydrocarbon liquid phase formed at the stage (W), is subjected to the stabilization order to remove volatile components.

13. The method according to one of spruce extract from it solvent.

14. The method according to p. 13, characterized in that the rinsing liquid hydrocarbon phase is regenerated aqueous phase formed in stage (g), from which is formed the drain flow with the possibility of maintaining the quantity of solvent and water in the circuit at substantially a constant level.

15. The method according to p. 13, characterized in that the stage of washing liquid hydrocarbon phase is performed by a mixer-settlers.

16. The method according to p. 13, characterized in that the stage of washing liquid carbon phase is carried out by contact in the column.

 

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