MX2013015303A - Integral process for sweetening and drying sour natural gas using filtrating coils of hollow fiber. - Google Patents

Abstract

The present invention refers to the oil industry and consequently to the gas industry, particularly being related to a process for removing impurities contained in natural gas, including a design of an integral process that comprises filtrating coils of hollow fiber, the process comprising the following steps: 1. Separation of heavy hydrocarbons (C6+) from the sour natural gas by the combined effect of coalescence and filtration in a single step. 2. Selective physical separation of components present in the sour natural gas (H2S, CO2, HO and light hydrocarbons) by means of modules of filtration coils of hollow fiber. 3. Depuration of residual H2S with a hydrocarbon-based liquid sequestrant. 4. Recovery of light hydrocarbons, propane, butane and pentane present in the permeated stream, which are re-injected to process lines of sour natural gas. 5. Re-injection of heavy condensates and depleted sequestrant into the process lines of natural gas and/or oil. This process is intended to rem ove the H2S from the sour natural gas in a total manner.

Description

INTEGRAL PROCESS OF SWEETENING AND DRYING OF NATURAL GAS AMARGO WHICH USES HOLLOW FIBER FILTERING BOBBINS TECHNICAL FIELD OF THE INVENTION.

The present invention relates to the oil industry, and as part of this to the gas industry, particularly it is related to a process for the removal of impurities contained in natural gas, and with an integral process design comprising filter coils of hollow fiber. BACKGROUND OF THE STATE OF THE TECHNIQUE.

The gas obtained from oil wells usually contains impurities, which vary in nature and quantity according to the characteristics and location of the deposits from which the gas comes, this gas is known as natural gas. In addition, the most common impurities contained in natural gas are hydrogen sulphide, (H2S) and carbon dioxide (CO2), as well as the following: Mercaptans (RSH), Carbon Disulfide (CS2) or Carbonyl Sulfide (COS) ). H2S and C02 are known as acid gases, because in the presence of water they form sulfuric acid (H2S04) and carbonic acid (H2CO3) respectively; and a natural gas that possesses these pollutants is known as bitter natural gas. These gases can cause problems in the handling and processing of gas, which makes it necessary to reduce the content of the bitter gases at the levels established in the current regulations and those required by natural gas consumers.

The removal of hydrogen sulfide, (H2S) contained in gas streams is of particular importance for several reasons. For example, it has a corrosive effect on the transport of natural gas through pipes, and is extremely toxic even at low concentrations. Likewise, the CO2 content of hydrocarbon gases such as natural gas, usually has to be reduced significantly, since high concentrations of CO2 reduce the calorific value of the gas and can also cause pipe corrosion. and accessories.

For any use to which the gas is destined, it must first be treated to eliminate the impurities of H2S and C02. The gas that is extracted from oil wells is destined in a high percentage to its use as fuel; the impurities it contains are harmful to the combustion process, and for the environment, via the gases that are emitted into the atmosphere, so it is essential to eliminate the impurities contained in the gas.

Gas sweetening is the process used to remove H2S and C02 from natural gas. This process can be by chemical absorption, using amines and potassium carbonate, which is the most used; physical absorption, direct conversion processes in which the H2S is converted directly into sulfur and adsorption processes among others. The selection of a sweetening process, generally carried out within a context of cost-benefit, will depend on several factors: Type of contaminants to be removed.

Concentration of pollutants and degree of removal required.

Required selectivity.

Traditionally for the removal of hydrogen sulphide or carbon dioxide from natural gas, the chemical process of absorption with amines "Girbotol" has been used. In this process the amine is diluted in water to improve its efficiency and remains in large contact towers where the bitter natural gas is passed. The sweet gas produced by this process is a gas saturated with H2O that requires an additional process to remove H20 and be used as a fuel gas.

The process of sweetening with amines has the following disadvantages: Generation of by-products (CO2 emissions into the atmosphere, discharge of bitter water, disposal of spent amines as hazardous waste).

Amines are easily contaminated.

Corrosion due to the degradation of amines.

High consumption of reagents and supplies (electrical energy, amines, steam).

Complex operation due to the large number of dynamic and process equipment involved.

High initial investment.

High cost of operation Comprehensive maintenance (pumps, heat exchangers, compressors, burners).

Disposal of hazardous waste.

It only removes H2S and the produced sweet gas is humid, that is to say a sweet natural gas saturated with H2O is produced.

Auxiliary services are required for its operation.

Due to the dimensions and weight of a plant of this type, it requires a large area and height available for installation, in addition to requiring civil works and special structures to support the weight of it. The assembly of the components of this type of plants is done on site.

The process of the present invention solves all the problems described above.

Some inventions contained in patents and patent applications are described below, which refer to processes and devices for removing impurities from natural gas, as well as processes that use membranes for such purpose. APPLICATION WO1999002244. TITLE: COMPOSITION AND PROCESS FOR THE SELECTIVE PURIFICATION OF GASEOUS CURRENTS BASED ON AQUEOUS SOLUTIONS OF ALCANOLAMINES.

Aqueous solution composition of mixtures of two alkanolamines, characterized by a range of composition diethanolamine, methyldiethanolamine between 5 and 45 percent of diethanolamine and between 5 and 45 percent by weight of methyldiethanolamine, provided that the total weight percentage of the two alkanolamines is between 15 and 50 percent by weight and the difference with respect to 100 percent weight is water.

The process described in the patent application WO 1999002244 corresponds to the elimination of acid gases from natural gas, which uses a mixture of amines, therefore it has all the drawbacks described above. The process of the present invention is very different from that of the aforementioned patent application since it includes process steps that do not they are part of a process such as that described in said patent application, such as: a stage of selective physical separation of bitter gases, water and light hydrocarbons, as well as a stage of purification of the residual H2S with a liquid hydrocarbon base sequestrant.

US Patent 3,859,514. Title: ELIMINATION OF H2S FROM A GAS CURRENT CONTAINING H2S AND CO2.

H2S is removed from a gas stream containing C02 and H2S without essentially affecting the CO 2 content of the gas stream by contacting the gas stream, in an absorption zone, with an aqueous absorbent stream containing a sulfite compound soluble in water under the conditions of thiosulfate production, including a pH selected from the range of about 6 to about 7, selected to form a treated gas stream substantially reduced in H2S content and a stream rich in absorbent containing a thiosulfate compound and that is substantially free of elemental sulfur. A key feature of the described method involves the careful selection of the conditions in the washing step to avoid the formation of elemental sulfur and to allow the selective production of a thiosulfate product.

The process of the present invention is very different from that described in US Pat. No. 3,859,514, because it is not a selective process for the elimination of H2S, it also includes steps that are not part of a process as described in said patent application, such as: a stage of selective physical separation of bitter gases, water and light hydrocarbons, as well as a stage of purification of the residual H2S with a liquid hydrocarbon base sequestrant.

US 7,004,997. Title: METHOD FOR THE ELIMINATION OF ACID GASES FROM A GAS CURRENT. The removal of acid gases from a gas stream in which a stream of gas containing acid-gas in which the sum of the partial pressures of the acid gases does not exceed 1,500 mbar is brought into contact with an aqueous absorbent in a absorption step and an absorbent which is used contains methyldiethanolamine and piperazine at a concentration of at least 8% by weight of the absorbent, obtaining a stream of acid gas and depleted gas in an acid-charged gas absorber.

The process of the present invention is very different from that claimed in the patent US 7,004,997, due among other aspects to that it does not use an absorbent containing methyldiethanolamine and piperazine. Other differences are that it includes stages that are not part of a method as described in said United States patent, such as: a stage of selective physical separation of bitter gases, water and light hydrocarbons, as well as a step of purification of the residual H2S with a liquid hydrocarbon base sequestrant.

Patent US 5,407,466. Title: GAS TREATMENT PROCESS NATURAL AMARGO INCLUDING STEPS OF TREATMENT INCLUDING MEMBRANES AND WITHOUT MEMBRANES.

Improvement of processes for the treatment of gas streams containing hydrogen sulfide, carbon dioxide, water vapor and methane, particularly natural gas streams. The processes are based on the availability of two types of membrane, one of which has hydrogen sulfide / methane selectivity of at least about 40 when measured with high-pressure multi-component gas mixtures. Based on the different permeation properties of the two types of membranes, optimized separation processes can be designed. The membrane separation is combined with a non-membrane treatment of the waste and / or permeate streams.

The process of the present invention is very different from that described in US Pat. No. 5,407,466, because it comprises steps that are not described in the aforementioned patent, such as: Separation of heavy hydrocarbons (C6 +) from the bitter natural gas; Selective physical separation of components present in the bitter natural gas (H2S, CO2, H2O and light hydrocarbons) in modules of hollow fiber filter coils; purification of residual H2S with liquid hydrocarbon base sequestrant; recovery of light hydrocarbons present in the permeate stream by reinjection to natural gas lines from the process and reinjection of heavy condensates and exhausted sequestrant to natural gas and / or process oil lines.

Patent No. US 5,401,300. PROCESS FOR THE TREATMENT OF NATURAL GAS AMARGO INCLUDING DEHYDRATION OF GAS CURRENTS.

Improved membranes and improvement of membrane processes for the treatment of gas streams containing hydrogen sulfide and methane, in addition to water vapor, carbon dioxide or both. The processes are based on the availability of two types of membrane, one of which has a high selectivity of hydrogen sulfide / methane and a high selectivity of water vapor / methane, when measured with mixtures of gas from multiple components to high pressures. Based on the different permeation properties of the two types of membranes, separation processes optimized can be designed. In favorable cases, the processes can simultaneously dehydrate the gas stream and remove the hydrogen sulfide at very low levels.

The process of the present invention is very different from that described in US Pat. No. 5,401,300, because it comprises steps that are not described in the aforementioned patent, such as: Separation of heavy hydrocarbons (C6 +) from the bitter natural gas; Selective physical separation of components present in the bitter natural gas (H2S, CO2, H2O and light hydrocarbons) in modules of hollow fiber filter coils; purification of residual H2S with liquid hydrocarbon base sequestrant; recovery of light hydrocarbons present in the permeate stream by reinjection to natural gas lines from the process and reinjection of heavy condensates and exhausted sequestrant to natural gas and / or process oil lines.

According to the above, there are notable differences between the present invention and the documents that are part of the state of the art.

It is therefore an object of the present invention to provide a process for the removal of high concentrations of H2S, in the bitter natural gas, using hollow fiber filter coils.

Another object of the present invention is to provide an integrated process for the treatment of bitter natural gas, from the separation of heavy hydrocarbons to the reinjection of heavy condensates to natural gas lines and / or process oil.

Another object of the present invention is to provide a process for the treatment of bitter natural gas streams that do not generate emissions to the atmosphere.

Another object of the present invention is to provide an integrated process for the treatment of bitter natural gas, using coils containing hollow filtering fibers.

Still another object of the present invention is to provide a modular process for the treatment of bitter natural gas streams.

In order to illustrate the present invention, the description is accompanied by the following figures.

Figure 1. Conventional membrane.

Figure 2. Conventional membrane in detail.

Figure 3. Hollow fiber filter coil.

Figure 4. Detail of the hollow fibers.

Figure 5. View of the gas flow in a filter coil. Figure 6. View of the gas flow in the fiber.

Figure 7. Detail view of the fibers of a coil.

Figure 8. Front view of the filter coil.

Figure 9. Process flow diagram.

DETAILED DESCRIPTION OF THE INVENTION.

The process of the present invention uses hollow fiber filter coils; as antecedent of these devices it has been that the use of the membrane technology for the processing of natural gas has been used extensively. Vitreous polymer membranes made from cellulose acetate, polyamides and polysulfones have been used for the elimination of CO2 and in limited cases for the dehydration of natural gas. This type of membranes are soluble or are affected by the presence of aggressive components in natural gas, such as high concentrations of aromatics or vapors of heavy aliphatic hydrocarbons. Additionally, they have to be protected from the condensation of hydrocarbons and water. That is why a thorough pretreatment is required to protect the membranes and ensure their proper functioning.

The membranes manufactured in rolled sheets or separation layers, are made of polymers and are used for the conditioning of fuel gas (extraction of C3 + hydrocarbons) and the elimination of the thickness of H2S, removal of H2S in percentage ranges. The most material common for the manufacture of these membranes are silicone-based polymers. These membranes are limited in their durability due to their thermo-mechanical properties, which is why these types of membranes have not been used successfully in the sweetening of bitter natural gas to eliminate H2S.

Figure 1 shows a view on its external part of a conventional membrane; in figure 2, a conventional membrane is shown in detail, in which the following parts are identified: membranes (1), with flow spacers of bitter natural gas (2), a perforated tube permeate gas collector (3), which indicates the flow of bitter natural gas (4) and the flow of the product (5) and a support of the membrane (6).

The process of the present invention is an INTEGRAL PROCESS OF SWEETENING AND DRYING NATURAL GAS AMARGO USING FILLETING COILS OF HOLLOW FIBER. The hollow fiber filter coils are different from the membranes because they consist of thousands of hollow fibers that are individually rolled, the material of the fibers is polyether ether ketone that is resistant to all liquids and components of natural gas. Hollow fiber filter coils have been used successfully for applications such as dehydration, CO2 removal, liquid extraction of natural gas, dewpoint control, improved oil recovery and reconcentration of depleted natural gas.

Figure 3 shows a view from the outside of a hollow fiber filter coil; Figure 4 corresponds to an approaching view of the fibers that make up the filter coil.

In figure 5 the gas flow through the filter coils is illustrated, showing that the coil has in its side part a bitter natural gas inlet (7); when the gas enters the coil, it comes into contact with the hollow filter fibers (8); Figure 6 shows a view with the increased size of a fiber (8), in which the flow of bitter natural gas is seen, the fiber filters the impurities, such as H2S, CO2, H2O, which flow through the internal part of the fiber (9), and the passage of natural gas flows through the external part (10) of the fiber (8), which is clearly seen in figure 8 where a fiber in enlarged size is shown. In figure 5, the outlet of the impurities (9) is seen, at one end (11) of the coil and at the other end (12), the outlet of the permeate natural gas. Figure 7 shows a set of fibers (8) that are part of the filter coil In the present invention a new use has been developed for these filter coils, which consists of the elimination of H2S, CO2 and water, among other impurities, contained in the bitter natural gas, in the quantities and high concentrations described in the present application. .

As described above, the material of the hollow fiber filter coils is, Polyether ether ketone, having the following general formula: It is a high performance material (HPM) that has the following outstanding properties: High mechanical resistance, rigidity and hardness, with a tensile strength of approximately 14.1 kpsi.

High service temperature, from approximately 250 ° C to 310 ° C.

Outstanding resistance to chemical corrosion and hydrolysis.

High resistance to wear.

The operating advantages that have been developed with the use of these filter coils in the treatment of bitter natural gas are: Pre-treatment Minimum, completely resistant to all the components present in Natural Gas, such as: Water, Aromatic Hydrocarbons, Amines, Solvents and NGL (Natural Gas Liquids); they produce a minimum pressure drop and have a high level of productivity.

The filter coils simultaneously remove contaminants such as H2O, H2S, and CO2.

Below is shown in TABLE 1, a comparison between the PEEK material and other materials used in the manufacture of membranes, in this table the mechanical strength of the PEEK material with higher values over the other materials is evident.

TABLE 1.

The separation process with filtering coils according to the use that has been developed according to this invention, has its greatest application potential in the removal of contaminants in percentage ranges, limiting its efficiency when treating pollutants in ppmv ranges. Even though the removal of H2S with filtering coils is 97-99.5%, the remaining H2S in the gas is of concentration between 600-100 ppmv. For this reason, the gas is fed to a final purification stage in which a sequestrant is used, which allows the final concentration of H2S to be brought to the conditions required in the sweet natural gas, which are described later.

The filter coils according to the new use that has been developed and with the process of the present invention, are organized in Physical Separation Units which are assembled in modular arrangements that can be isolated individually and that allow flexibility in the production, is say the treatment of bitter gas flow in the quantities that are required; the replacement of separation modules and / or equipment maintenance, without affecting the production of sweet natural gas.

The integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils of the present invention comprises the following steps: 1. - Separation of heavy hydrocarbons (C6 +) from the bitter natural gas by combined effect of coalescence and filtering in a single step. 2. - Selective physical separation of components present in the bitter natural gas (H2S, CO2, H2O and light hydrocarbons) through the use of modules of hollow fiber filter coils. 3. - Debug H2S residual with liquid hydrocarbon base sequestrant. 4. - Recovery of light hydrocarbons, propane, butane, and pentane present in the permeate stream, which are re-injected to process bitter natural gas lines. 5. - Reinjection of heavy condensates and exhausted sequestrant to natural gas lines and / or process oil.

The whole process of sweetening and drying of bitter natural gas using hollow fiber filter coils of the present invention, constituted as a package, does not generate emissions to the atmosphere and is instrumented with on-line analyzers that allow to monitor the quality of the gas in different points at all times.

The following describes in detail each of the stages of the integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils. 1. - SEPARATION OF HEAVY HYDROCARBONS (C6 +) FROM NATURAL GAS AMARGO BY COMBINED EFFECT OF COALESCENCE AND FILTERED IN A SINGLE STEP.

For the integral sweetening process to be efficient, it is necessary to eliminate all those compounds that interfere with, inhibit or block the mass transfer process in the physical and chemical separation involved, mainly solid particles and heavy hydrocarbons that are in a state from the bitter natural gas. liquid in the bitter natural gas stream feeding the integral process. For this purpose a pre-treatment is included in which the pressure of the bitter natural gas is regulated, if necessary when there is a higher pressure, the pressure is regulated to values between 17.0 kg / cm2 and 64.0 kg / cm2. Bitter natural gas is fed to a dual-purpose coalescent filter: coalescent-particles, which means that solid particles up to 0.1 microns in size are retained in the same filter; coalescence in the same filter, is the effect that the drops of consensuses come together to form larger droplets that finally fall by gravity and collect in the lower part of the filter. Through these filters, particles up to 0.1 miera are retained and fats and oils (heavy hydrocarbons C6 +) They are trapped by coalescence in the internal cartridges by sending them to the heavy condensate recovery line, avoiding condensation in the filter coils.

The temperature of the gas at the inlet of the coalescing filter is within the range of about 25 ° C to 45 ° C and the pressure is within the range of about 17.0 kg / cm2 to 64.0 kg / cm2. These values are maintained for the output currents that are: heavy hydrocarbons and bitter natural gas with lower content of heavy hydrocarbons, C6 +, likewise smaller amounts of butane and pentane are eliminated; wherein the% elimination is approximately: Butane 4 to 15%, pentane approximately 9 to 28% and C6 + approximately 19 to 47%.

As an example, the dual-purpose coalescer-particles filter is a carbon steel tower with dimensions: 32.38 cm outside diameter and 2.66 m high. The tower has internal preparations to house the coalescent-particle filter cartridges, with dimensions: 12.7 cm outside diameter and 91.44 cm high. These cartridges are intended for the separation or capture of very small liquid particles in fluids: drops of water or oil in gases / water droplets (mists) in oil, which when they reach the right size are released by gravity (coalescence).

The coalescing filter tower is instrumented with level sensors, automatic valves and alarms, controlled by a logic controller (PLC) processor mounted on a local control board, with possibilities to link to the central control room. 2. - SELECTIVE PHYSICAL SEPARATION OF PRESENT COMPONENTS IN THE NATURAL GAS AMARGO (H2S, CO2, H2O AND LIGHT HYDROCARBONS) THROUGH THE USE OF FILTERING BOBBIN MODULES.

Bitter natural gas free of heavy condensates is fed to the separation unit with filter coils. The filter coils have one input and two outputs. The input corresponds to the supply of a current of bitter natural gas, while the outputs are: a sweet gas stream out of specification, rich in methane, high pressure and another current of very low pressure, approximately between 1 and 2 kg / cm2, which is identified as permeate gas, rich in C02, H2S and humidity, drags light condensates, which are propane, butane, pentanes and hexanes of high economic value. This current is reincorporated into the line of conduction of bitter natural gas through a mechanism of recovery of light condensates, It consists of a Compressor-Ejector, which uses a high pressure current to incorporate a low pressure current without the need for dynamic equipment: This Compressor-Ejector has the operating principle of a Venturi tube. The sweet gas out of specification is fed to the next stage of the process, identified as post-treatment or final purification stage.

In the stage of selective physical separation, a modular arrangement with hollow fiber filter coils is used. Each coil is housed in a coil holder, made of carbon steel with one inlet and two flanged outlets. The coil is made of polymer material PEEK (for its acronym in English Poliether ether ketone), with characteristics of high chemical and mechanical resistance, which allow the selective physical removal of H2S, CO2 and H2O.

It is important to note that in this stage the selective physical removal of H2S, C02 and H2O, particularly H2S, is carried out, which corresponds to a relevant aspect of the present invention.

Regarding the operating conditions of this stage, the temperature of the gas at the inlet of the filter coil module is approximately 25 ° C to 42 ° C, and the pressure is approximately 17 kg / cm2 to 63.5 kg / cm2, the Sweet gas temperature outside specification is from about 13 ° C to 22 ° C, and the pressure is from 16 kg / cm2 to 62 kg / cm2. The temperature of the permeate gas is about 15 ° C to 32 ° C and the pressure is about 1 kg / cm2 to 2 kg / cm2.

The percentage of H2S removal in the filter coils is about 96 to 99.99%, which is a very high value that can only be obtained with the process of the present invention; the percentages of elimination of the other compounds are the following: Elimination% Propane 31-63% Butane 43-78% Pentane 67-95% C6 + 79-98% co2 45-79% N2 3 .8 -11. 0% H2O 97-100% 3. - DEPOSITION OF H2S RESIDUAL WITH SECQUESTING LIQUID BASE HYDROCARBON.

To comply with the specifications of H2S content, the sweet gas out of specification, is fed to tanks Contactors where it is passed through a liquid column of hydrocarbon base sequestering product. In this stage, the residual H2S is removed from the natural gas by chemical reaction and absorption in the purifying liquid, delivering a gas with the specifications required in the industry, which is < 10 ppmv.

The purification tower is instrumented with level sensors, automatic valves and alarms controlled by a logic controller (PLC) processor mounted on a local control board, with the possibility of linking to the central control room.

As regards the final purification, the chemical sequestrant used in the process of the present invention is a triazine, hydrocarbon-based product, which prevents the dry gas product of stage 2 from being saturated with H2O.

The scrubbing product, hydrocarbon base liquid sequestrant, has been used by injecting it directly into the gas line. However, its efficiency is low and therefore the cost is high for an application such as natural gas sweetening. In the sweetening process of natural gas of the present invention, this sequestering liquid product is used as part of the final purification and the contact of the sequestrant with the gas is made in towers purifiers, where the liquid remains stationary and the gas flows through it. The design of the scrubber towers includes diffusers and a demister, which allows to maximize the efficiency of the scrubber product.

Contactor tanks comprise the following parts: A) Diffuser, refers to a device whose function is to disperse the gas in bubbles of small size (size established in the design of the treatment tower).

B) Demister refers to a metal mesh in which the liquid particles coalesce and get trapped and then fall by gravity.

The design of the sewage tower allows recovering the spent sequestering product, containing the H2S, to reinject it to lines of bitter natural gas and / or process oil. This is possible because it is a hydrocarbon based product that is compatible to be mixed, constituting as an advantage of the process of the present invention of zero discharges to the environment. 4. - RECOVERY OF LIGHT, PROPANE, BUTANE, AND PENTANE HYDROCARBONS PRESENT IN THE PERMEATED CURRENT, WHICH ARE REINJECTED TO NATURAL GAS LINES BITTER PROCESS.

The permeate gas stream at low pressure, between 1 and 2 kg / cm2, which is one of the streams that comes out of the filter coils, drains light condensates, propane, butane, and pentane, of high economic value, which according to the process of the present invention is reincorporated into the line of conduction of bitter natural gas through a condensate recovery mechanism: Heater and Eductor JET-COMPRESSOR, used to incorporate the permeate into the process line.

The Eductor uses a line derived from the main line of compressed bitter natural gas as recompression motive gas. To prevent cavitation or malfunction of the eductor mechanism, a pre-heater is included to raise the temperature of the permeate gas between 8 and 10 ° C using the same compressed bitter natural gas stream of higher temperature for heat exchange. 5. - REINJECTION OF HEAVY CONDENSATES AND SEQUESTRANT SOLDERED TO NATURAL GAS LINES AND / OR PROCESS OIL.

Additionally, the process includes an eductor for the reincorporation of spent sequestering product and high pressure liquid condensates.

All streams of products and by-products generated in the process are managed in isolated pipelines and do not represent a problem of environmental contamination.

The equipment that carries out the process of separation with package coils, is mounted on skids ready to operate at any time and place that is required.

All the equipment necessary to carry out the process of the invention are assembled and fixed on a carbon steel structure, in such a way that the bitter natural gas treatment plant is transported armed and with the necessary preparations for its interconnection at the site. where will it operate? The main application of the integral process of sweetening and drying of bitter natural gas that uses hollow fiber filter coils, is the removal of H2S from the bitter natural gas, as well as reducing the concentration of contaminants such as propane, butane, pentane, C6 +, CO2, N2 and H2O.

The process can also be used for the dehydration of natural gas, extraction of natural gas liquids, dew point control of natural gas and improved oil recovery.

The separation process with filter coils of the present invention is successfully used in plants gas processors for both natural gas sweetening and for applications such as dehydration, elimination of QO2, extraction of liquids from natural gas, dewpoint control, improved oil recovery and recovery of depleted natural gas, among others.

In order to illustrate the separation process with filtering coils of the present invention, in the flow chart of Figure 1, the different stages of said process are shown in detail. Next, a description of the process of the invention is made based on said diagram.

With No. (1), the start of the separation process with filtering coils is shown, which corresponds to the supply of bitter natural gas, which circulates through the pipe (2), and passes through the pressure regulating valve (3) and enters the dual-purpose filter (4) in which stage 1 of the process is carried out, which involves the separation of heavy hydrocarbons (C6 +) from the bitter natural gas by combined effect of coalescence and filtering in a just step, this stage was described in detail in stage 1 of the process; through the upper part of the filter (4), a current of bitter natural gas circulating through the pipe (5) is obtained; through the bottom of the double filter purpose (4), heavy hydrocarbons C6 + are obtained, which circulate through the pipe (6) and are sent to the condesados pipeline, not shown because this condensate pipe is part of the installation of the site.

The current flowing through the pipe (5) becomes the supply to the separation unit with hollow fiber filter coils (7), in which stage 2 of the process consisting of the selective physical separation of the fiber is carried out. components present in the bitter natural gas (H2S, CO2, H2O and light hydrocarbons) through the use of filtering coil modules containing fourth generation PEEK fibers, the details of this stage were described in detail in stage 2 of the process; of the separation unit (7), a current (8) rich in C02, H2S and humidity, of very low pressure, which is identified as pern eted, is obtained. The gas flow permeated at low pressure approximately between 1 and 2 kg / cm2, drags light condensates, which are propane butane, pentanes and hexanes of high economic value. From the separation unit (7), a sweet gas stream outside specification (9) is obtained, which is fed to a final purification stage; the gas stream (9) circulates through the pipeline (10), to stage 3 of the process.

In stage 3, where the residual H2S is cleaned with hydrocarbon-based liquid sequestrant, the sweet gas stream is fed out of specification (9), which flows through the pipe (10) to a contactor tank (11); in the contactor (11) the sweet gas stream out of specification is passed through a liquid column of hydrocarbon base sequestering product. In this stage the residual H2S is removed from the natural gas by chemical reaction and absorption in the purifying liquid, obtaining by the pipe (12) a gas with the specifications required in the industry, which is 0-10 ppmv, the gas circulating through the pipeline (12) it is delivered as a product for the uses that are required.

The sequestering product is contained in a tank of sequestrant solution (13); through the bottom of the tank (13), the sequestrant is conducted through the pipe (14) and fed to the contactor tank (11). The purification tower is instrumented with level sensors, automatic valves and alarms controlled by a logic controller (PLC) processor mounted on a local control board, with the possibility of linking to the central control room. Stage 4 of the whole process of sweetening and drying of bitter natural gas using fiber filter coils hollow, includes the recovery of light hydrocarbons, propane, butane, and pentane present in the permeate stream (8), these compounds are reinjected into natural gas lines bitter process, the above is done with its reincorporación to the line of conduction of bitter natural gas for recovery of light condensates (15), by means of a jet compressor (16), where the pressure of the permeate gas is 1 kg / cm2 at 2 kg / cm2 and the pressure of the natural gas pipeline Bitter process is from 17.7 kg / cm2 to 63.8 kg / cm2.

Stage 5 of the process consists of the reinjection of heavy condensates and sequestrant to natural gas lines and / or process oil, the aforementioned is carried out when the sequestering product is exhausted. Stage 5 is carried out by removing the sequestering product from the tank (17), which is a tank for loading and unloading the sequestering product, which is done through the lower part of said tank.; the exhausted sequestrant stream and other tank compounds (13) are sent to a jet compressor eductor (18), for the reinjection of spent sequestering product and high pressure liquid condensates, which are sent to secondary processes of natural gas bitter.

According to the process of the present invention, the number of each of the units shown in each of the stages of the process is increased according to the treatment needs, that is to say to the amount of bitter gas that must be treated.

It has been found that the process of the present invention is up to about 65% more economical than the traditional amines treatment process mentioned above.

Following are examples of application of the integral process of sweetening and drying of bitter natural gas that uses hollow fiber filter coils, in which bitter natural gas is treated.

In the application examples described below, 3 different streams of bitter natural gas are processed, for which corresponding analyzes are provided, these 3 different feed streams are treated in the process of the present invention to always obtain sweet gas within the specifications of the petroleum industry and complying with the Official Mexican Standard NOM-001-SECRE-2010 regarding the specifications of sweet natural gas Table 2 below provides the analysis of the bitter natural gas streams that were used in the following 3 examples: TABLE 2 Example 1. The bitter natural gas of stream 1, whose analysis is shown in Table 2, was fed to the process of the present invention, obtaining the following results: TABLE 3 COALESCENCE AND FILTERED IN Cond. Of op. At the entrance.

SWEET NATURAL GAS (PRODUCT) Exit conditions. 2 The bitter natural gas of gas stream No. 2, whose analysis is shown in table 2, is fed to the process of the present invention, in which the operating conditions have been modified, with the following results: TABLE 4 COALESCENCE AND FILTERED IN Cond. Of op. At the entrance. ONE STEP Temperature: 42 ° C Stage 1. Pressure: 51.0 Kg / cm2 Example 3 The bitter natural gas of stream No.3, whose analysis is shown in table 2, is fed to the process of the present invention, in which the operating conditions have been modified, with the following results: TABLE 5 According to the results of the previous examples it is shown that even with the feeding of bitter natural gas streams having different concentration of H2S, the process of the present invention has the capacity and flexibility to produce sweet natural gas with final H2S values of 0 to 4 ppm, as well as the elimination of approximately 89% of the CO2 contained in the natural gas feed streams.

Additionally it is shown that the process of the present invention is integral, that is to say that it does not produce any contaminating element in the atmosphere or water.

In the previous examples a single filtering coil was used, the number of filtering coils that are required according to the expenditure of bitter gas to be treated can be used, examples of expenditure values are from approximately 3.00 million ft3 std / day to 250 million ft3 std / day.

Claims (14)

1. - Integral process of sweetening and drying of bitter natural gas that uses hollow fiber filter coils, characterized because it is comprised of 5 stages, which are: 1.- Separation of heavy hydrocarbons (C6 +) of the bitter natural gas by combined effect of coalescence and filtered in one step; 2.- selective physical separation of components present in the bitter natural gas (H2S, CO2, H2O and light hydrocarbons), through the use of filtering coil modules; 3.- purification of residual H2S with liquid hydrocarbon base sequestrant; 4.- recovery of light hydrocarbons, propane, butane and pentane, present in the permeate stream, which are reinjected to process natural gas lines; 5.- reinjection of heavy condensates and exhausted sequestrant to natural gas lines and / or process oil.

2. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that in step 2, the separation of H2S, C02, H20 and light hydrocarbons, is carried out by using of filtering coils, where the separation takes place in each of the fibers contained in each filter coil module.

3. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that in stage 1, the operating conditions are: temperature approximately from 25 ° C to 42 ° C and pressure approximately 17 to 60.0 Kg / cm2.

4. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that in step 2, selective physical separation of components present in the bitter natural gas, through the use of modules of filtering coils, the operating conditions are: temperature approximately from 25 ° C to 42 ° C and pressure approximately from 17.2 to 60.0 Kg / cm2 and the range of removal of H2S is from approximately 96% to 99.9%; Propane from approximately 31% to 62.5%; Butane approximately 43% to 78.4%; Pentane approximately 67% to 95.4%; C6 + approximately 79% to 98.7%; CO2 approximately 45% to 79.1%; N2 approximately 3.8% to 10.9% and H2O approximately 97% to 100%.

5. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that in the stage 3, purification of residual H2S with liquid hydrocarbon base sequestrant, the operating conditions are: temperature approximately from 20 to 32 ° C and pressure approximately from 16.7 to 59.3 Kg / cm2, where the range of H2S removal is approximately 99 % to 100%

6. - Integral process of sweetening and drying of bitter natural gas that uses hollow fiber filter coils, according to claim 5, characterized in that the liquid sequestrant is triazine.

7. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that in stage 4, recovery of light hydrocarbons, propane, butane and pentane, present in the permeate stream , these hydrocarbons are re-injected to process bitter natural gas lines, by means of a jet compressor, where the permeate gas pressure is from 1 kg / cm2 to 2 kg / cm2 and the pressure of the natural gas pipeline process is from 17.7 kg / cm2 to 63.8 kg / cm2.

8. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that in step 5, the heavy condensates are reinjected and the spent sequestrant to bitter natural gas lines and / or process oil, by means of a jet compressor, where the pressure of the heavy condensates and the spent sequestrant is about 16.7 kg / cm2 at 60 kg / cm2 and the pressure of the pipeline Conduction of bitter natural gas and / or process oil is approximately 17.7 kg / cm2 to 63.8 kg / cm2.

9. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that the sweet gas obtained has the following composition: H2S approximately 0-4 ppm; N2 approximately 0.65 to 2.50% Mol, CO2 approximately 0.96 to 2.6% Mol; Methane approximately 72.0 to 88.0% Mol; Ethane approximately 6.5 to 15.3% Mol; Propane from about 2.6 to 7.0% Mol; Butane from about 0.8 to 2.0% Mol; Pentane approximately from 0.07 to 0.27% Mol and C6 + approximately from 0.01 to 0.13% Mol.

10. - Integral process of sweetening and drying of bitter natural gas using hollow fiber filter coils, according to claim 1, characterized in that the flow values of the bitter gas that it processes are a function of the number of filter coil modules used, where the treatment capacity of the process is adapted to the needs of treatment of bitter natural gas.

11. - Use of hollow fiber filter coils in the elimination of impurities contained in the bitter natural gas, where these impurities are: H2S, CO2 and H2O.

12. - Use of hollow fiber filter coils in the elimination of impurities contained in the bitter natural gas, according to claim 11, characterized in that the fibers packed in the coils, filter the impurities, H2S, C02, H20, which flow through the internal part of the fiber and natural gas flows on the external part of the fiber towards the exit of the impurities at one end of the coil and on the other end the natural gas comes out.

13. - Use of hollow fiber filter coils in the removal of impurities contained in the bitter natural gas, according to claim 11, characterized in that a modular arrangement with hollow fiber filter coils is used, each coil is housed in a coil holder, with one entrance and two exits. The coils have thousands of hollow fibers that wind individually are made of polyether-ether-ketone polymer material, and perform the selective physical removal of H2S, C02 and H20.

14. - Use of hollow fiber filter coils in the elimination of impurities contained in the bitter natural gas, according to claim 11, characterized in that the filtering coils are organized in physical separation units, which are assembled into modular arrays that are isolated individually and that allow flexibility in the expenditure of bitter gas that is processed, the replacement of separation modules and / or equipment maintenance, without affecting the production of sweet natural gas.