JP2021514440A - Methods and systems for processing gas hydrate-containing slurries - Google Patents

Abstract

A method and system (42) for processing a gas hydrate-containing slurry (12) is provided, wherein the system contains a first level of gas hydrate that contains a higher level of gas hydrate compared to the slurry. A separator (422) configured to separate the stream (121) into a second stream (123) containing a lower level of gas hydrate compared to the slurry, and a first stream and a first stream. With a processing assembly (424) configured to process the two streams separately, the first stream either recovers the gas hydrate from the first stream or the gas hydrate of the first stream. The second stream is treated to recover gas from the gas hydrate of the second stream.

Description

The present invention relates to methods and systems for treating gas hydrate-containing slurries that can be obtained from the bottom of the water.

Methane (CH ₄ ) hydrates are occasionally formed from the release of methane gas along marine geological faults. In cold climates, and especially in deep or deep lakes, at least some of the methane gas forms hydrates on or near the seabed when in contact with cold water. Methane hydrate is considered a promising alternative energy source. One liter of methane hydrate solid will contain about 168 liters of methane gas at standard temperature and pressure (STP).

Attempts have been made to develop systems and methods for extracting methane from these hydrate deposits. Underwater hydrate mining methods include U.S. Patent No. 6,209,965, U.S. Patent Application No. US2003 / 0136585, International Patent Application No. WO98 / 44078, International Patent Application No. WO2010 / 092145 A1, and Chinese Patent Application No. It is known from CN101182771. WO2010 / 092145 A1 further describes a method for treating a hydrate-containing slurry obtained from the bottom of the water, where the slurry is discharged into a slurry separation assembly and separated into a methane gas stream and a tailing stream. The Tailings stream is pumped to the Tailings return conduit and returned to the bottom for disposal.

Despite this and other attempts, it is still necessary to develop improved systems and methods for treating gas hydrate-containing slurries obtained from the seabed. The treatment is preferably carried out in a more energy efficient and / or economically feasible manner.

U.S. Pat. No. 6,209,965 U.S. Patent Application Publication No. 2003/0136585 International Publication No. 98/44078 International Publication No. 2010/092145 Chinese Patent Application Publication No. 101182771 International Publication No. 2010/092145

Therefore, in one aspect of the present invention, a method for treating a slurry containing a gas hydrate is provided, and the method is described as.
-A step of separating the slurry into a first stream containing a higher level of gas hydrate compared to the slurry and a second stream containing a lower level of gas hydrate compared to the slurry. ,
-Processing the first and second streams separately, the first stream either recovers gas hydrate from the first stream or gas from the gas hydrate of the first stream. The second stream is processed to recover gas from the gas hydrate of the second stream.

In another aspect of the invention
A system for processing slurries containing gas hydrates is provided and the system
-Separate the slurry into a first stream containing a higher level of gas hydrate compared to the slurry and a second stream containing a lower level of gas hydrate compared to the slurry. With the configured separator,
-A processing assembly configured to process the first and second streams separately, where the first stream either recovers gas hydrate from the first stream or the first stream. Includes a processing assembly, which is processed to recover gas from the gas hydrate of the second stream and the second stream is processed to recover the gas from the gas hydrate of the second stream.

These and other features, embodiments and advantages of the systems and methods according to the invention are described in the following detailed description of the appended claims, abstracts, and non-limiting embodiments shown in the accompanying drawings. In their description, reference numbers are used to refer to the corresponding reference numbers shown in the drawings.

The present invention will be described in more detail and by way of example below with reference to the accompanying drawings.
FIG. 6 is a schematic representation of an exemplary system for underwater mining to which the systems and methods according to the invention apply. It is a schematic block diagram of the system for processing the gas hydrate-containing slurry obtained from the water bottom. FIG. 6 is a schematic block diagram of a heating module applied in a system for processing gas hydrate-containing slurries obtained from the bottom of the water. It is a flow chart of the method for processing the gas hydrate-containing slurry obtained from the seafloor sediment.

In drawings, similar reference numbers refer to similar / equivalent components, steps, or features.

The present invention may be embodied or implemented in a system for processing slurries containing gas hydrates. The slurry may be transported to the system under a first pressure, while at least a portion of the system is operated under a second pressure below the first pressure and above atmospheric pressure. The first pressure can be selected to suppress the dissociation of the gas hydrate and the second pressure can be selected to allow the dissociation of the gas hydrate.

The system separates into a first stream containing a higher level of gas hydrate compared to the slurry and a second stream containing a lower level of gas hydrate compared to the slurry. It may be equipped with a vessel. The separator separates the slurry into a first stream and a second stream based on at least one of the following properties of the solid material in the slurry: mass, size, density, wettability, or magnetic susceptibility: Can be configured to.

The system may include a processing assembly for processing the first flow and the second flow separately. The first stream is processed to recover the gas hydrate from the first stream or to recover the gas from the gas hydrate of the first stream. The second stream is processed to recover gas from the gas hydrate of the second stream. The gas recovered from the gas hydrate in the second stream may be used to power the system.

The processing assembly may include at least one heating module configured to provide heat to at least one of the first and second streams. The heating module
A first unit configured to expose the inflow to the first heating medium,
A second unit configured to separate the outflow of the first unit into a first flow and a second flow,
A third unit connected to the second unit and configured to expose only the first stream to the second heating medium.
It may include a fourth unit configured to merge the heated first stream with the second stream to obtain an outflow of the heating module.

The processing assembly may further comprise at least one dehydration unit configured to dehydrate the first stream and / or the second stream. The dehydration unit is preferably placed in front of the heating modules of the respective first and / or second streams. Dehydration of the first stream and / or the second stream is preferably performed before supplying each stream to the respective heating.

Processing the first stream may include grinding the first stream to reduce the size of solid material therein before feeding the first stream to the dehydration unit or heating module. Therefore, the system may further include a grinder configured to reduce the size of the solid material in the first stream.

A pretreatment assembly can be provided upstream of the separator. The pretreatment assembly may be configured to expose the slurry to pretreatment before it is sent to the separator. Pretreatment may include at least one of: grinding, preheating, and / or dehydration:

FIG. 1 shows an exemplary system for underwater mining. Specifically, System 1 is designed to excavate, lift, and process gas hydrates from seafloor sediments 11. The systems and methods for treating gas hydrate-containing slurry obtained from the bottom of the water according to the present invention can be used in this system to recover valuable gases such as methane, and other systems and methods are available. It is equally applicable to gas hydrates.

As shown in FIG. 1, the submarine excavator 10 hydrate excavates from the hydrate deposit 11 buried in the bottom 19, and contains the excavated solid state hydrate, particulate deposit, and seawater. The slurry 12 is transferred through the flexible hose 13 to a pump station 14 installed at a depth above the bottom 19. The pump station 14 increases the pressure of the slurry 12 and moves the slurry 12 upward through the slurry riser conduit 15 in a substantially turbulent state. In practice, if desired, multiple pumps can be distributed along the conduit 15 to maintain pressure across the vessel.

The slurry riser conduit 15 ends with a platform 2 floating on the water surface 21 where the slurry 12 enters the system 22 and is processed. Specifically, in system 22, the methane hydrate in the slurry 12 can dissociate into water and methane gas. Methane gas can be collected from the top of the system 22. The collected methane gas is further dried and pressurized or otherwise by a downstream system such as a compressed natural gas (CNG) system, a liquefied natural gas (LNG) system, or a pipeline export system. May be processed. The Tailings stream 23 containing residual water and sediment is drawn, for example, from the bottom of the system 22 into a Tailings return conduit 16 extending from platform 2 and returning to region 18 of the bottom 19, suitable for Tailings disposal. enter.

Applicants have found it important to keep gas hydrate in its (hydrate) stable region (field) of conduit 15. Preferably, the slurry 12 is transported to the first pressure (P ₁₎ system 22 under, P ₁ is to be selected to suppress the dissociation of the hydrate at a temperature in conduit 15, the slurry 12 The hydrate in it remains within its stable region as long as the slurry 12 is still in the conduit 15.

Preferably, at least a portion of the system 22 is operated under a _{second pressure (P2) selected to allow dissociation of gas hydrate.} For example, the slurry 12 may experience a pressure drop from P _{1 to P 2} as it exits the conduit 15 and enters the system 22. The gas hydrate in the slurry then exits its stable region and begins to dissociate. The second pressure P ₂ is preferably selected to be higher than atmospheric pressure. In one example, P ₂ is about 10 bar. By setting P _{2 above} atmospheric pressure, the energy required to repressurize the gas generated from the system 22 is reduced. This is especially useful when the recovered gas needs to be pressurized to form CNG or LNG, for example for storage and transport.

The system for processing a slurry containing a gas hydrate according to the present invention is further described in detail with reference to FIGS. 2-5.

FIG. 2 is a schematic block diagram of a system 22 for processing a gas hydrate-containing slurry obtained from the bottom of the water. This system 22 may be applied in the system 1 shown in FIG. 1 for processing the slurry 12. The system 22 mainly comprises a separator 222 and a processing assembly 224. In one example, the slurry 12 reaching the system 12 may contain: seawater, solid state hydrates, solid state deposits: The slurry 12 should be pretreated before being sent to the separator, as the system 22 may include a pretreatment assembly (not shown) installed upstream of the separator, as described below. Can be done.

In the example shown in FIG. 2, the separator 222 receives the slurry 12 and is lower than the slurry 12 with a first stream 121 containing a higher level of gas hydrate compared to the slurry 12. Separate into a second stream 123 containing a level of gas hydrate.

In one example, this is because the weight ratio of the gas hydrate of the first stream 121 is higher than that of the slurry 12, and the weight ratio of the gas hydrate of the second stream 123 is lower than that of the slurry 12. It is embodied by.

System 22 can benefit from separation for at least the following reasons:
1) Applicants have found that the size of hydrates should be as small as possible to allow fast dissociation, especially if the goal is to recover the gas instead of solid gas hydrates. For that purpose, it is preferable (but optional) to grind the gas hydrate to reduce the size of the hydrate. However, the slurry also contains rock and sediment mass, which operators do not want to spend energy on crushing. By separating the slurry into two streams, the need to grind rocks or sediments for energy saving purposes can be avoided.
2) Applicants have also found that heating (and even repeated heating) may be required to completely dissociate the hydrates contained in the slurry. By separating the slurry into a hydrate-rich but sediment-rich first stream and a hydrate-poor but sediment-rich second stream, operators can get more hydrate. It makes it possible to apply only additional heating to the first stream containing. Otherwise, this is more energy efficient because in the absence of separation, the hydrates are mixed in it and the system has to heat a significant amount of sediment and rocks. ..

Applicants have found that pure hydrates in solid state, pure deposits in solid state, and mixtures thereof typically have at least one of the following properties: mass, size, density, wettability, and magnetic susceptibility: We found that they differed from each other in two respects. Therefore, the separator 222 can separate the slurry 12 into a first stream 121 and a second stream 123 according to at least one of these properties. For example, the separator 222 can perform, for example, centrifugation utilizing a density that distinguishes between sediments and gas hydrates.

The first flow 121 and the second flow 123 are transferred to the processing assembly 224. The processing assembly 224 processes the first flow 121 and the second flow 123 separately. Specifically, the first flow 121 is processed to recover gas from the gas hydrate of the first flow 121 or to recover the gas hydrate from the first flow. The second stream 123 is processed to recover gas from the gas hydrate of the second stream 123. In various examples, processing assembly 224 can process the two streams differently, as described below.

In one example, the separator 222 and processing assembly is operated at a second pressure P ₂ lower suitable dissociation of gas hydrate. Part of the gas hydrate is dissociated in separator 222 and the rest is dissociated in processing assembly 224. The residual flow obtained by treating the first flow 121 to increase the recovery rate does not have to form part of the Tailings flow 125 directly, instead the residual flow is in another round. It can be sent back to processing assembly 224 for processing to ensure that as much gas hydrate as possible is dissociated.

The gas released from the dissociation is collected for further processing such as drying and repressurization. Without loss of generality, the gas recovered from the processing of the second stream 123 can be used to power the system 22 or even the entire platform 1 shown in FIG. The pressure at which the elements of the system 22 are manipulated can be selected by taking into account the following: i) maximizing the driving force (relative to the hydrate stable curve) to increase the hydrate dissociation rate, ii. ) Meet the highest possible gas export pressure requirements.

In another example, the separator 222, may not need to operate at a second pressure P ₂ lower, instead, the pressure in the separator 222, the gas hydrate does not dissociate in the separator 222 , Can be set high enough so that no gas is released. Gas hydrate leaving the separator 222, the pressure drop (e.g., reduced to P ₂₎ is exposed to, the downstream unit / module, e.g., the first crusher, or treatment assembly as described later below It may stimulate the dissociation of hydrates in the stream and / or the second stream.

In another example, the processing assembly 224 is not configured to recover gas from the gas hydrate of the first stream 121 by heating or other means. Instead, the processing assembly 224 is configured to process the first stream 121 to obtain a relatively pure gas hydrate, which is preferably dry. To that end, a dehydration module (described later) can be included in the processing assembly 224 to process the first stream 121 and remove seawater from it. The first stream 121 may be sent back to the separator 222 before or after processing in the processing assembly to remove more deposits from the first flow 121. Therefore, the outflow 127 obtained by treating the first stream 121 may contain a dry gas water hydrate suitable for storage and / or transport. The pressure and temperature within the elements / modules in the processing assembly 224 assigned to process the separator 222 and the first flow 121 are carefully controlled to keep the gas hydrate in the first flow in its stable region. Should be.

The processing assembly 224 produces a tailling flow 125 as a result of processing the first flow 121 and the second flow 123. Tailing stream 125 contains mainly water and sediment and is returned to a suitable location at the bottom 19.

As briefly stated, there are two main different methods for processing the first flow, depending on the products expected from the processing of the first flow 121. In the first example, both first streams 121 are not exposed to heating or large pressure drops that promote the dissociation of gas hydrates. Instead, in processing assembly 224, the first stream is dehydrated (or dried) to remove the liquid water and separate to obtain a relatively pure dry hydrate that is later exported as a product of system 22. The deposit may be taken out from the vessel 222 repeatedly supplied. To that end, other elements such as the separator and the dehydration module assigned to the first stream 121 are operated under pressure suitable to keep the gas hydrate of the first stream from dissociating. It can be important to ensure. The temperature of the separator and the dehydration module assigned to the first stream 121 should also be kept low enough not to promote dissociation. To produce gas hydrates instead of gas from the first stream, optionally, a grinding process as described later with reference to FIG. 3 can be used.

The gas recovered from the processing of the second flow 123 can be used to power the system 22 or even the entire platform 2.

FIG. 3 is a schematic block diagram of a system 32 for processing a slurry containing gas hydrate. Comparing the system 32 with the system 22, the main difference is that the system 32 further includes a grinder 326 located downstream of the separator 322 and upstream of the processing assembly 324. The crusher 326 is configured to receive and crush the first stream 121, thereby reducing the size of solid material, especially the hydrate digging debris of the first stream 121. By reducing the size of the solids in the first stream 121, especially the hydrates therein, the hydrates in the first stream are provided with a larger surface area that can facilitate their dissociation. Other suitable means can be used instead of the crusher to reduce the size of the hydrate digging in the first stream 121.

The grinder 326 may be operated under pressure to promote dissociation of the gas hydrate, and the gas may be partially recovered and collected from the first stream 121 in the grinder 326.

The outflow 327 from the crusher 326 formed by reducing the size of the solid material in the first flow 121 is a process in which the outflow 327 and the second flow 123 are treated separately for gas recovery. Provided to assembly 324.

It should be noted that the grinder 326 is optional.

The example of FIG. 3 has a variant in which the treatment of the first stream 121 is performed to recover gas hydrate instead of gas. A similar example is detailed with reference to FIG.

FIG. 4 is a schematic block diagram of a system 42 for processing a slurry 12 containing gas hydrate. System 42 is a further development based on system 32 shown in FIG. 3 and provides more details about the processing assembly.

As will be similarly described with reference to FIGS. 2-3, in the system 42, the separator 422 will combine the suction slurry 12 with a first stream 121 having a higher hydrate level compared to the slurry 12. It is set to separate into a second stream that has a lower hydrate level compared to the slurry 12. The first stream 121 then passes through a crusher 426 in which the size of the solid material in the first stream 121 is reduced.

The processing assembly 424 comprises a heating module 4242a and a reaction vessel 4244a (or reaction tube) arranged in order to process the outflow 427 of the crusher 426. The processing assembly 424 further comprises a heating module 4242b and a reaction vessel 4244b (or reaction tube) configured to receive and process the second flow 123. In this way, the first stream 427 and the second stream 123 after grinding are treated separately and, if necessary, differently.

The heating module 4242a is configured such that it provides heat to the stream 427 and thus promotes the dissociation of the gas hydrate in it. The gas released from the dissociation is collected from the gas outlet (not shown) of the heating module 4242a, and the outflow 429a from the heating module 4242a is provided to the reaction vessel 4244a installed downstream of the heating module 4242a. .. The effluent 429a typically contains residual water produced from the dissociation generated in the heating module 4242a, seawater and sediments first carried in the first stream 427 after crushing. Those skilled in the art will appreciate that if it is expected to process the first stream to recover gas hydrate instead of gas, the heating module 4242a and reaction vessel 4244a can be omitted and replaced by a dehydration module. Will do. Similar examples are described with reference to FIGS. 2 and 3.

The heating module 4242b is configured to provide heat to the second stream 123 to promote the dissociation of gas hydrates therein. The gas released from the dissociation is collected from the gas outlet (not shown) of the heating module 4242b, and the outflow 429b from the heating module 4242b is supplied to the reaction vessel 4244b. The outflow 429b from the heating module 4242b typically contains residual water produced from the dissociation that occurred in the heating module 4242b, seawater and deposits initially carried in the second stream 123.

Reaction vessels 4244a and 4244b can be formed by large tanks, respectively. In each large tank, the inflow (429a or 429b) enters from the top and exits from the bottom. In each of the reaction vessels 4244a and 4244b, the gas hydrate remaining in the inflow is dissociated to achieve a high recovery rate, i.e. sufficient to dissociate as much hydrate as possible within the system 42. May have time. Since the first stream is rich in gas hydrate, the stream 425a may be sent back to the heating module 4242a for another round of heating to ensure a high dissociation rate. In this way, additional heating is provided to the first stream containing a higher level of gas hydrate than the incoming slurry in order to increase the recovery rate of the gas.

Reaction vessels 4244a and 4244b generate tailling streams 425a and 425b, respectively, which can be pumped back to the bottom 19 in a suitable manner.

As mentioned, each reaction vessel may be replaced by a reaction tube through which the inflow can flow and the remaining gas hydrate in the inflow can dissociate.

The reaction vessel 4244b can be optional, in which case the outflow of the heating module 4242b may be taken as a tailing stream and returned to the bottom 19.

FIG. 5 shows a system 52 for processing a slurry containing gas hydrate. System 52 can be considered as a further development based on System 42 shown in FIG. Compared to system 42, system 52 further includes a dehydration function, as further described below.

The separator 522, crusher 526, heating modules 5242a and 5242b, reaction vessels 5244a and 5244b are similar to those described with reference to FIGS. 2-4.

In the system 52, dehydration is preferably performed before the first stream and the second stream are heated by their respective heating modules. It is assumed that 50% of the water is removed from each stream in this dehydration facility, and no deposits are removed. If it occurs, it only has a positive effect. Dehydration can reduce the flow rate of each stream.

The effect of dehydrating the first stream 527 and the second stream 123 after grinding by adding dehydration modules 5246a and 5246b is that less water needs to be heated. In addition, if the same equipment is used, the flow velocity will decrease and the amount of heat transported with the seawater will increase. As a result, it is estimated that the total power supplied to the heating module can be reduced by about 35%.

To ensure a high recovery of gas from the gas hydrate of the first stream, the outflow 525a of the reaction vessel 5244a is sent back to the dehydration module 5246a or the heating module 5242a and the residual hydrate left there. The rate may be further dehydrated and heated. Returning the stream 525a to the dehydration module 5246a may be preferable as it removes residual water from the stream 525a which does not need to be heated.

According to the modification of the example shown in FIG. 5, the dehydration module 5246b and / or the reaction vessel 5244b can be optional. In other words, the second stream 123, which contains a lower level of hydrate compared to the slurry 12, may be sent directly to the heating module 5252b.

Tailing streams 525a and 525b are formed as a result of processing the first and second streams by the processing assembly 524.

The example of FIG. 5 has a modification in which the heating module 5242a and the reaction vessel 5244a are omitted, whereby the dry gas hydrate is recovered by processing the first stream. Similar examples are described with reference to FIGS. 2-4.

All of the examples shown in FIGS. 2-5 can be modified by adding any pretreatment assembly (not shown) upstream of the separator. Pretreatment may include at least one of the following: preheating, dehydration, grinding.

FIG. 6 shows an exemplary block diagram of the heating module 6 according to an embodiment of the present invention.

As shown, the first unit 601 has an inflow 611 of a heating module 6 which can be a slurry 12, a first stream or a second stream, as shown in any of FIGS. 2-5. receive. The first unit 601 also receives a first heating medium 616 introduced to heat the inflow 611 in the first unit 601. The first heating medium 616 is, for example, seawater that is warmer than a cold slurry. In one example, the first unit 601 is mounted by a multi-tube heat exchanger. As shown in FIG. 6, methane can be partially recovered from the heating process in the first unit 601.

The outflow 612 from the first unit 601 is led to a second unit 602, which, in one example, splits the outflow 612 into two streams 613 and 615, eg, a liquid cyclone or a Y-joint. Can be a means of The flow 613 can be a small portion of the outflow 612 (eg, 20%, 10%, or less).

The flow 613 is supplied to, for example, a third unit 603 that is further heated by the second heating medium 617. A part of the gas in the gas hydrate contained in the flow 613 is recovered by this third unit 603. In one example, the third unit 603 is mounted by a spiral heat exchanger and the second heating medium 617 is heated water. The heated water can be heated by waste heat and / or additional heat, or by burning a previously recovered gas, for example, by treating a second stream.

After processing the flow 613 in the third unit 603, an outflow 614 is generated and fed to the fourth unit 604, which may be another Y-joint where the outflow 614 and the main flow 615 rejoin. Confluence 616 is provided, for example, in the reaction vessel as previously described for further processing.

In an alternative example, the second unit 602 may be implemented by a hydrocyclone in which smaller hydrate particles (eg, fine particles) are separated from larger hydrate particles (eg, curser particles). A stream 613 carrying smaller hydrate particles is fed to a third unit 603, which can be carried out by a plate heat exchanger or some parallel plate heat exchangers, and is heated by heating water from waste heat or additional heat. Will be done. The stream 615 carrying the larger hydrate particles is optionally exposed to further heating in multi-tube heat exchange with seawater. These two streams merge together at the fourth unit 604 after passing through the heat exchanger.

In the reaction vessel, the hydrate has time to dissociate. When all hydrates are dissociated and gas is discharged, water and soil are returned to the seabed.

In another alternative, the first unit 601 may be implemented by several spiral heat exchangers arranged in parallel.

With reference to FIG. 6, a heating module 6 is described that separates the inflow into two streams 613 and 615 and processes the two streams. Alternatively, the heating module may be implemented by a preheater and a main heater arranged in sequence. For example, a multi-tube heat exchanger may be used as a preheater for preheating the inflow with seawater. This heating is performed, for example, by injecting steam. After steam injection, an outflow of heating module is formed and all gas hydrates are fed to the dissociating reaction vessel.

The operating conditions of these and other modules, units and components of the system can be well tuned by using mathematical models that explain the dynamics of hydrate dissociation.

Specific examples of systems according to the invention are described with reference to drawings in which building blocks (units, modules) are arranged in a particular order. Those skilled in the art will appreciate that the invention is not limited to these examples. For example, at least some of those building blocks may be reordered and / or placed in a ring or parallel.

According to the configuration modifications shown in the figure, the slurry may be pretreated prior to separation. For example, a pretreatment assembly for preheating the slurry may be installed upstream of the separator to preheat the slurry with warm seawater. The heating module shown in FIG. 6 can be used for this purpose.

In another variant, the dehydration module may be installed upstream of the separator to dehydrate the slurry before it is fed to the separator. This dehydration module does not need to replace at least one dehydration module in the processing assembly, in one example dehydration is performed before separation and within the processing assembly.

In another variant, the crusher may be installed upstream of the separator. This can result in additional energy consumption by grinding the non-hydrated components of the slurry, and at least part of the processing assembly can still benefit from being placed downstream of the separator.

FIG. 7 shows an exemplary flowchart of a method for treating a gas hydrate-containing slurry obtained from the bottom of the water according to a preferred embodiment of the present invention. The various steps of this method reflect the functionality of the units, modules, and assemblies of systems 22, 34, 42, and 52 described with reference to FIGS. 2-5. Therefore, the method can already be described by reference to the description provided in connection with FIGS. 2-5.

In a basic embodiment of the method reflecting system 22 shown in FIG.
(I) The slurry is separated into a first stream containing a higher level of gas hydrate compared to the slurry and a second stream containing a lower level of gas hydrate compared to the slurry. Steps and
(Ii) By treating the first flow and the second flow separately, the first flow either recovers the gas hydrate from the first flow or the gas hydrate of the first flow. It comprises a step of processing, which is processed to recover the gas from the second stream, and the second stream is processed to recover the gas from the gas hydrate of the second stream.

In the example shown in FIG. 7, the suction slurry pulled up from the bottom of the water in step 701 (reflecting the function of the separator as described) is compared to the slurry by the separator (322, 422, 522). It is separated into a first stream containing a higher level of gas hydrate and a second stream containing a lower level of gas hydrate as compared to the slurry.

The slurry is transported to the separator under a first pressure, the separator may be operated under a second pressure, and the first pressure is selected to prevent the dissociation of the gas hydrate. At least some of the steps of the method can be operated in a first lower than the pressure, and the second pressure P ₂ lower which is selected to be higher than atmospheric pressure in order to dissociate the gas hydrate .. In other words, at least part of the system is operated under a second pressure chosen to be lower than the first pressure and higher than the atmospheric pressure to dissociate the gas hydrate. Alternatively, as previously described, the pressure drop can occur after separation.

In step 702, the first stream is crushed, thereby reducing the size of the solid material in the first stream, especially the gas hydrate in the solid state.

In step 703, the first stream (after grinding) and the second stream are dehydrated, respectively.

In step 704, the dehydrated stream is heated using the respective heating modules as previously described.

In step 705, the heated stream is fed to each reaction vessel where the remaining gas hydrate is further dissociated until the gas is sufficiently recovered from the slurry.

As mentioned earlier, the second stream may or may not need to be dehydrated and exposed to the reaction vessel. In other words, the second stream may be sent directly for heating for gas recovery, and the outflow generated after heating may be taken as a tailing stream and sent for disposal.

Embodiments of step 704 may include the following processes that reflect the heating module 6 described with reference to FIG.
-Expose the inflow of the heating module to the first heating medium to obtain a preheated flow;
-Separating the preheated stream into a first stream and a second stream;
-Exposing only the first stream to the second heating medium; and-Merge the heated first stream with the second stream to obtain the outflow of the heating module.

The method may further comprise the step (not shown) of exposing the slurry to at least one of the following processes before the slurry is sent to the separator:
grinding;
Preheating;
dehydration.

This optional step reflects the pretreatment assembly described with reference to FIGS. 2-5.

In the modification of the method shown in FIG. 7, the first steam is not heated and is not exposed to the reaction vessel. Instead, the first stream is primarily dehydrated to remove water from it. The first stream after dehydration may be sent back to the separator to enhance separation and remove more sediment from the first stream. Such variants have already been detailed with reference to FIGS. 2-5.

Although specific embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. The embodiments described herein may be embodied in various other embodiments. Moreover, various omissions, substitutions, and modifications in the embodiments described herein can be made without departing from the scope of the invention. The appended claims and their equivalents are intended to include such forms or modifications as are within the scope of the invention.

Claims (5)

A method for processing slurries containing gas hydrates.
The slurry is divided into a first stream containing the gas hydrate at a higher level than the slurry and a second stream containing the gas hydrate at a lower level than the slurry. To separate and
Including processing the first flow and the second flow separately.
The first stream is treated to recover gas hydrate from the first stream or to recover gas from the gas hydrate of the first stream.
A method in which the second stream is treated to recover gas from the gas hydrate of the second stream. The slurry is transported to the system under a first pressure, the first pressure being selected to prevent dissociation of the gas hydrate, the method.
Further comprising dissociating the gas hydrate by operating at least a portion of the system under a second pressure selected to be below the first pressure and above atmospheric pressure. , The method according to claim 1. The heating step further comprises heating at least one of the first stream and the second stream by at least one heating module.
To obtain a preheated flow by exposing the inflow of the heating module to a first heating medium,
Separating the preheated stream into a first stream and a second stream,
Exposing only the first stream to the second heating medium and
The method according to any one of claims 1 and 2, comprising merging the heated first stream with the second stream to obtain an outflow of the heating module. Before the slurry is sent to the separator, the slurry is pretreated as follows:
grinding,
Preheating,
The method according to any one of claims 1 to 3, further comprising performing at least one of dehydration. A system for processing slurries containing gas hydrate,
The slurry is divided into a first stream containing the gas hydrate at a higher level than the slurry and a second stream containing the gas hydrate at a lower level than the slurry. With a separator configured to separate,
A processing assembly configured to process the first flow and the second flow separately.
The first stream is treated to recover gas hydrate from the first stream or to recover gas from the gas hydrate of the first stream.
A system in which the second stream is processed to recover gas from the gas hydrate of the second stream.

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