KR20210047653A - MEG regeneration system and marine structure including the same - Google Patents

Abstract

The present invention relates to an MEG regeneration system for being applied to offshore structures and, more specifically, to an MEG regeneration system comprising: a pre-processing unit for receiving a rich MEG and removing hydrocarbons from the rich MEG; a rich MEG tank for storing the rich MEG discharged from the pre-processing unit; a salt removal membrane for precipitating and discharging salt components from the rich MEG discharged from the rich MEG tank; a distillation column for discharging water to the top of the column by distilling the rich MEG in which the salt component is deposited from the salt removal membrane, and for discharging the lean MEG to the bottom of the column; and a salt difference power generation unit in which the salt component precipitated and discharged from the salt removal membrane is injected in the form of a salt slurry, and to an marine structure having the MEG regeneration system. Accordingly, the MEG regeneration system and the marine structure including the same may generate energy using the salt slurry which occurs when removing salts to enhance salt removal efficiency.

Description

MEG regeneration system and marine structure including the same

The present invention relates to a MEG regeneration system and an offshore structure including the same.

In offshore structures for natural gas production, hydrates may be generated when the inside of the subsea production pipe reaches the hydrate production temperature and pressure conditions during natural gas production, which may cause clogging of the inside of the pipe.

A thermodynamic inhibitor may be used as a means for fundamentally inhibiting the formation of hydrate, and in general, Mono Ethylene Glycol (MEG) is widely used. Accordingly, in most offshore structures, MEG is injected into a well, a manifold, or a portion of a top-side system with a high possibility of hydrate formation in order to prevent clogging of subsea production pipes.

When MEG is injected into a submarine production pipe, the MEG retains water and forms a rich MEG, and the rich MEG also contains salts dissolved in the water. The used MEG may undergo a predetermined MEG regeneration process for reuse. The MEG regeneration process may include, for example, supplying rich MEG to a regeneration system installed on the top side to regenerate MEG, which includes a salt component reclamation and a water removal process. can do.

In the conventional process of removing salt components, a flash separator was used to separate MEG and water in a gas phase, and a salt component in a slurry form. At this time, the temperature of the rich MEG introduced into the separator is about 20 to 50°C, and the temperature required to remove the salt component is about 100 to 120°C. Therefore, a method of circulating the rich MEG by connecting a heater to the bottom of the separator is used to remove salt components. Even in this case, the flow rate required for circulation increases to increase the temperature of 50°C or higher, which is the height of the separator. Caused to increase.

When a flash separator is used to remove salt components, it occupies the largest volume in the gas treatment system, and a centrifuge for processing the salt component slurry discharged from the separator also occupies a large volume. have. In the case of offshore structures, as the space is narrow and the volume and weight of each process system increase, it becomes difficult to arrange and install in the platform, which is a problem that is directly related to the cost of the platform. Therefore, in the case of a MEG treatment system for application to offshore structures, not only a method of improving the efficiency of the system, but also a method of reducing the volume and weight of the system is drawing attention.

The present invention is to provide a MEG regeneration system and an offshore structure including the same to generate energy by using the salt slurry generated when the salt component is removed.

One aspect of the present invention is a MEG regeneration system, comprising: a pretreatment unit receiving a rich MEG and removing hydrocarbons from the rich MEG; A rich MEG tank for storing the rich MEG discharged from the pretreatment unit; A salt removal membrane that precipitates and discharges salt components from the rich MEG discharged from the rich MEG tank; A distillation column for distilling the rich MEG in which the salt component is deposited from the salt removal membrane to discharge water to the top of the column and discharge lean MEG to the bottom of the column; And it provides a MEG regeneration system comprising a salt difference power generation unit in which the salt component precipitated and discharged from the salt removal membrane is injected in the form of a salt slurry.

Another aspect of the present invention provides an offshore structure including the MEG regeneration system.

The present invention can control the salt removal efficiency from the rich MEG by using one or more salt removal membranes to remove the salt component of the rich MEG, thereby achieving the desired salt removal efficiency.

The present invention has a smaller volume compared to the conventional flash separator, and does not use a centrifuge for removing the salt component slurry, thereby providing an advantage in space arrangement.

The present invention may generate electricity by using a slurry containing a removed salt component, and use the generated electricity to provide energy required for a MEG regeneration system and an offshore structure including the same. Furthermore, there is no need to use a centrifuge that is used to reduce the generation of salt slurry, and energy required for the centrifuge can be saved.

In the present invention, by supplying the heat of water and lean MEG discharged from the distillation column to the rich MEG and heating it, energy required for removing salt components of the rich MEG can be reduced.

In the present invention, by injecting lean MEG into the rich MEG tank that stores the rich MEG, the heat energy of the lean MEG is utilized and the solubility of the salt component due to the increase in the MEG concentration in the tank is lowered, thereby improving the salt removal efficiency in the salt removal membrane It can be greatly improved.

1 shows a schematic diagram of a MEG playback system according to an embodiment of the present invention.
2 shows a schematic diagram of a MEG playback system according to another embodiment of the present invention.
3 shows a schematic diagram of a MEG playback system according to another embodiment of the present invention.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are only examples to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

The present invention provides a MEG reproduction system capable of efficiently reproducing MEG.

In detail, the present invention provides a MEG regeneration system, comprising: a pretreatment unit receiving a rich MEG and removing hydrocarbons from the rich MEG; A rich MEG tank for storing the rich MEG discharged from the pretreatment unit; A salt removal membrane that precipitates and discharges salt components from the rich MEG discharged from the rich MEG tank; A distillation column for distilling the rich MEG in which the salt component has been deposited from the salt removal membrane to discharge water to the top and discharge lean MEG to the bottom of the column; And it provides a MEG regeneration system comprising a salt difference power generation unit in which the salt component precipitated and discharged from the salt removal membrane is injected in the form of a salt slurry.

In this case, the rich MEG may be MEG recovered after injecting MEG to suppress and reduce the generation of gas hydrate during natural gas production, and the MEG regeneration system removes water and salt components from the rich MEG to remove MEG. It can be regenerated, and the regenerated MEG can again be used to produce the natural gas.

Furthermore, it is possible to increase the efficiency of the MEG regeneration process by recycling the removed water and salt components.

Hereinafter, the MEG playback system of the present invention will be described in detail with reference to the accompanying drawings.

The MEG regeneration system according to an embodiment of the present invention includes a pretreatment unit 100, a rich MEG tank 110, a salt component removal unit 120, a distillation column 130, and a salt difference power generation unit 140.

Valves (not shown) capable of adjusting the opening degree may be installed in each line of the present embodiment, and fluid flow such as rich MEG, salt slurry, water, and lean MEG may be adjusted according to the adjustment of the opening degree of each valve.

Rich MEG is supplied to the pretreatment unit 100, and the rich MEG processed by the pretreatment unit is stored in the rich MEG tank 110 and then supplied to the salt component removal unit 120 to remove the salt component. , It is moved to the distillation column (130).

Hereinafter, the individual configurations will be described in more detail.

Pretreatment

A rich MEG may be supplied to the preprocessor 100, for example, a rich MEG may be supplied from a rich MEG supply line. The rich MEG may be produced by injecting MEG into a well, a manifold, and the like, and may include gas and solids including MEG, water, and hydrocarbons. The temperature of the rich MEG supplied to the MEG regeneration system may be 5 to 30°C, and the pressure may be 3 to 7 bar.

The pretreatment unit 100 may be provided with a means for receiving the rich MEG and removing hydrocarbons contained in the rich MEG before undergoing a salt component removal and water removal process of the rich MEG.

Preferably, the pretreatment unit 100 may separate and remove the remaining components excluding the MEG and salt components from the rich MEG and a part of the water contained in the rich MEG. For example, the pretreatment unit 100 may include a separation membrane (not shown) to remove a part of water and gases such as hydrocarbons contained in the rich MEG, and include a filter (not shown). Some or all of them can be removed. The solid content is a concept encompassing all materials in a solid state capable of flowing through a gas treatment system in a state not dissolved in rich MEG, water or lean MEG. The temperature inside the pretreatment unit 100 may be maintained at 20 to 50°C, and the pressure may be 1 to 2 bar.

The rich MEG from which hydrocarbons, water, solids, etc. are removed from the pretreatment unit 100 may be supplied to the rich MEG tank 110. In this case, the rich MEG discharged from the pretreatment unit 100 may be directly injected into the rich MEG tank 110, or the first heat exchanger 102 and the first heat exchanger 102 provided at the front end of the rich MEG tank 110 2 It may be heated while passing through the heat exchanger 103, and may pass through one or more pumps 101 for smooth transfer.

Additionally, the pretreatment unit 100 may include one or more discharge units (not shown) for discharging gas, water, solids, or a combination thereof, such as hydrocarbons separated from the rich MEG, to the outside of the MEG regeneration system. Gas may be discharged through one discharge unit (not shown) provided in the pretreatment unit 100, and water and solids may be discharged through another discharge unit (not shown). Gases such as hydrocarbons discharged from the pretreatment unit 100 may be stored separately and then supplied to a customer or discharged to the outside.

First heat exchanger and second heat exchanger

As shown in FIG. 2, the present invention may include a first heat exchanger 102 and a second heat exchanger 103.

The first heat exchanger 102 may heat the rich MEG discharged from the pretreatment unit 100 using water discharged to the top of the distillation column 130 to be described later. That is, heat exchange between the water discharged from the distillation column 130 and the rich MEG may occur in the first heat exchanger 102, and the discharged water may be at a higher temperature than the rich MEG. For example, the temperature of the rich MEG may be 20 to 50°C, and the temperature of water discharged from the distillation column 130 may be 80 to 90°C.

When the rich MEG is heated by heat exchange through the first heat exchanger 102, the temperature of the rich MEG may increase to 30 to 70°C, and may be preheated as a preheat for a salt component removal process to be described later. have. Energy required for preheating of the rich MEG may be reduced by heat exchange through the first exchanger 102.

The rich MEG discharged from the first heat exchanger 102 may be introduced into the second heat exchanger 103, and the water discharged from the first heat exchanger 102 may be discharged to the outside of the MEG regeneration system.

The second heat exchanger 103 may heat the rich MEG heat-exchanged in the first heat exchanger 102 using lean MEG discharged to the bottom of the distillation column 130 to be described later. That is, heat exchange between the rich MEG and the lean MEG may occur in the second heat exchanger 103, and the lean MEG may be at a higher temperature than the rich MEG. For example, the temperature of the rich MEG may be 20 to 50 °C, and the temperature of the lean MEG may be 70 to 90 °C.

When the rich MEG is heated by heat exchange through the second heat exchanger 103, the temperature of the rich MEG may increase to 30 to 80°C, and it is preheated as a preheat for a salt component removal process to be described later. I can. Energy required for preheating of the rich MEG may be reduced by heat exchange through the second heat exchanger 103.

The rich MEG discharged from the second heat exchanger 103 may flow into the rich MEG tank 110 and be stored, and the lean MEG discharged from the second heat exchanger 103 is a separate storage unit (not shown) for reuse. It can be stored in a) and supplied to a consumer.

Accordingly, the MEG regeneration system of the present invention includes: a first heat exchanger installed at the front end of the rich MEG tank and heating the rich MEG discharged from the pretreatment unit using water discharged to the top of the distillation column; And a second heat exchanger installed at the front end of the rich MEG tank and heating the rich MEG heat-exchanged in the first heat exchanger using the lean MEG discharged to the bottom of the distillation column.

Meanwhile, as shown in FIG. 3, lean MEG discharged from the bottom of the distillation column 130 may be supplied to the rich MEG tank 110. Through this, the heat energy of the lean MEG itself is supplied to the rich MEG in the tank and the concentration of the MEG in the tank is increased, thereby lowering the solubility of the salt component in the rich MEG to remove the salt in the salt component removal unit 120 The efficiency can be greatly improved.

Accordingly, the MEG regeneration system of the present invention further includes a first heat exchanger installed at the front end of the rich MEG tank and heating the rich MEG discharged from the pretreatment unit using water discharged to the top of the distillation column, Lean MEG discharged to the bottom of the distillation column may be supplied to the rich MEG tank.

Rich MEG tank

The rich MEG tank 110 may provide a place for storing the rich MEG and the salt concentrate supplied from the salt component removal unit 120 to be described later. The salt concentrate may be in the form of a sludge in which a liquid phase and a solid phase are mixed by including salt, water, and MEG. The temperature of the salt concentrate may be 100 to 120°C, and as it flows into the rich MEG tank 110, it is mixed with the rich MEG so that the temperature inside the rich MEG tank 110 may be 50 to 90°C. . Preferably, the rich MEG tank 110 may further include a heating member (not shown) to maintain an internal temperature of 100 to 120°C. The rich MEG and salt concentrate may be partially vaporized as they flow into the rich MEG tank 110, and the pressure inside the rich MEG tank 110 may be 0.1 to 0.5 bar.

The rich MEG discharged from the rich MEG tank 110 may be supplied to the salt component removal unit 120, and preferably may be supplied through the thermal steam compressor 111.

Salt component removal unit

The salt component removal unit 120 may precipitate a salt component from the supplied rich MEG including one or more salt removal membranes 121, 123, 125, and separate and discharge the salt component in the form of a salt slurry.

The salt component may be one or more selected from the group consisting of monovalent salts such as sodium chloride, potassium chloride, sodium hydroxide, and potassium hydroxide, and divalent salts such as calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, and magnesium sulfate, but limited thereto. It doesn't work. The solubility of the salt component in the rich MEG may be inversely proportional to the temperature of the rich MEG, and when the temperature of the rich MEG increases, the divalent salt component may be more easily precipitated than the monovalent salt component.

The salt component removal unit 120 may operate under conditions of 100 to 120° C. and 0.1 to 0.5 bar. Additionally, when the rich MEG is supplied to the salt component removal unit 120, the salt removal efficiency of the salt component removal unit 120 may be further improved by passing through a thermal steam compressor 111 that injects heat steam.

When the salt-removing membranes 121, 123, 125 are composed of various polymers such as polysulfone, polyester sulfone, polypropylene, polyacrylonitrile, polycarbonate, polyphenylene oxide, or a combination thereof to pass the rich MEG The salt component contained in the rich MEG can be precipitated. The rich MEG from which the salt component has been removed while passing through the salt removal membrane may be supplied to the distillation column 130.

When the salt component removal unit 120 includes one or more salt removal membranes 121, 123, 125, the membranes may be arranged in a multistage structure. By controlling the number of the membranes and arranging them in a multi-stage structure, the salt removal efficiency can be controlled, thereby making it possible to avoid using a centrifuge, which will significantly reduce the volume occupied by the system compared to the case of employing a flash separator and a centrifuge. You will be able to.

Specifically, the rich MEG may be supplied to the salt component removal unit 120 and pass through the salt removal membrane 121 so that salt may be precipitated. The precipitated salt may still be mixed with water and a small amount of MEG, and the salt may be precipitated by passing through another salt removal membrane 123 after being pressurized through the pump 122. The precipitated salt may still be mixed with water and a trace amount of MEG, and the salt may be precipitated by passing through another salt removal membrane 125 after being pressurized through the pump 124. The precipitated salt may be mixed with water and a trace amount of MEG, and may be discharged to the outside of the salt component removal unit 120 in the form of a salt slurry. The rich MEG from which the salt component has been removed by passing through the salt removal membranes 121, 123, 125 may be supplied to the distillation column 130.

A part of the salt slurry discharged from the salt component removal unit 120 may be resupplied to the rich MEG tank 110 in the form of a salt concentrate, and the remaining part may be discharged to the outside of the MEG regeneration system. At this time, the slurry may be transferred using the pump 126 for smooth circulation and discharge of the salt slurry.

Salinity difference power generation department

The salt difference power generation unit 140 may supply energy required for the MEG regeneration system by using a salt slurry containing a salt component discharged from the salt component removal unit 120.

The salt difference power generation unit 140 may generate energy by using the salt slurry and fresh water discharged from the salt component removal unit 120, and the fresh water may have a lower salt concentration than the salt slurry. Accordingly, the salt difference power generation unit 140 may be generated by a difference in concentration between the salt slurry and fresh water having a lower salt concentration than the salt slurry.

At this time, the salinity difference power generation unit 140 includes a semi-permeable separation membrane 141, and the salt slurry and fresh water supplied to the saline difference power generation unit 140 flow through the semi-permeable separation membrane 141, osmotic pressure. As a result, the water of the freshwater flow unit 142 passes through the semi-permeable separation membrane 141 and moves to the salt slurry flow unit 143 having a high salt concentration. The flow rate and pressure of the salt slurry flow unit 143 are increased by the permeated water, and the salt slurry having the increased flow rate and pressure is supplied to the turbine 144 to generate electricity. Meanwhile, some of the salt slurry moves to the pressure exchange unit 145 to increase the pressure of the salt slurry supplied to the salt slurry flow unit 143.

Therefore, the salt difference power generation unit 140 may be applied with a pressure retarded osmosis (PRO) method in which the osmotic pressure due to the difference in concentration between the salt slurry and fresh water is converted into mechanical energy as described above, but is not limited thereto. , For example, reverse electrodialysis (RED) can be applied using an electrochemical potential due to a difference in concentration between salt slurry and fresh water.

The energy generated by the salt difference power generation unit 140 as described above may be used in a configuration that may require a heating device, such as a rich MEG tank or a salt component removal unit of the MEG regeneration system, or used in a pump in the MEG regeneration system. Can significantly reduce the consumption of energy used in the MEG regeneration system.

Distillation tower

The distillation column 130 may distill the rich MEG supplied from the salt component removal unit to discharge water to the top and discharge lean MEG to the bottom of the column. The distillation column 130 may distill water from the rich MEG using a point where the boiling point of water is about 100°C and the boiling point of MEG is about 200°C under normal pressure conditions. Lean MEG discharged to the bottom of the distillation column 130 may contain 80% by weight or more of MEG. Preferably, the lean MEG may contain 80 to 99.99% by weight of MEG.

Part or all of the water discharged from the top of the distillation column 130 may be supplied to the first heat exchanger 102 and provided as a heat medium for heating the rich MEG, and the water used for the heat exchange may be transferred to the outside of the MEG regeneration system. Can be discharged.

The water discharged from the top of the distillation column 130 in a high-temperature steam state can be condensed through a condenser 131, and a part or all of the condensed water condensed in the condenser 131 is the above-described first heat exchanger 102. ) Can also be supplied. By providing some or all of the water discharged from the top of the distillation column 130 as a heat medium for the first heat exchanger 102 as described above, the capacity of the condenser 131 can be reduced.

The rest of the water discharged to the top of the distillation column 130 that is not supplied to the first heat exchanger 102 may be discharged to the outside of the MEG regeneration system.

The lean MEG discharged from the bottom of the distillation column 130 may be supplied to the above-described second heat exchanger 103 and provided as a heat medium for additional heating of the rich MEG heat-exchanged in the first heat exchanger 102, Lean MEG used for heat exchange can be recovered through a separate recovery line.

Alternatively, by supplying the lean MEG discharged from the bottom of the distillation column 130 to the above-described rich MEG tank 110, the thermal energy of the lean MEG itself is supplied to the rich MEG in the tank and at the same time, the concentration of the MEG in the tank is By increasing the solubility of the salt component in the rich MEG, the salt removal efficiency in the salt component removal unit 120 can be greatly improved.

The lean MEG may smoothly discharge the lean MEG and transfer the lean MEG from the bottom of the distillation column 130 through the vacuum pump 132.

The MEG regeneration system of the present invention heats the rich MEG by using the water discharged from the water removal process of the rich MEG and the waste heat of the lean MEG, thereby reducing the thermal energy required when removing salt components and improving the salt removal efficiency. , By adopting the salt removal membranes 121, 123, 125 in the salt component removal unit 120, the salt removal efficiency can be adjusted, and the advantage of space arrangement through a reduction in volume compared to flash separators and centrifuges can be provided. have.

On the other hand, the present invention provides an offshore structure including the MEG regeneration system of the present invention.

The offshore structure encompasses all ships, gas platforms, and offshore floats capable of producing natural gas at sea, and the MEG regeneration system of the present invention can also be applied to onshore gas plants that require suppression of hydrate generation.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical spirit of the present invention described in the claims. It will be obvious to those of ordinary skill in the field.

100: pretreatment unit 101, 122, 124, 126: pump
102: first heat exchanger 103: second heat exchanger
110: rich MEG tank 111: thermal steam compressor
120: salt component removal unit 121, 123, 125: salt removal membrane
130: distillation column 131: condenser
132: vacuum pump 140: salt difference power generation unit
141: semi-permeable membrane 142: freshwater flow section
143: salt slurry flow unit 144: turbine
145: pressure exchange unit

Claims (8)

In the MEG playback system,
A pretreatment unit receiving the rich MEG and removing hydrocarbons from the rich MEG;
A rich MEG tank for storing the rich MEG discharged from the pretreatment unit;
A salt removal membrane that precipitates and discharges salt components from the rich MEG discharged from the rich MEG tank;
A distillation column for distilling the rich MEG in which the salt component is deposited from the salt removal membrane to discharge water to the top and discharge lean MEG to the bottom of the column; And
A salt difference power generation unit in which the salt component precipitated and discharged from the salt removal membrane is injected in the form of a salt slurry;
Containing, MEG playback system.
The method of claim 1,
A first heat exchanger installed at the front end of the rich MEG tank and heating the rich MEG discharged from the pretreatment unit using water discharged to the top of the distillation column; And
The MEG regeneration system further comprises a second heat exchanger installed at the front end of the rich MEG tank and heating the rich MEG heat-exchanged in the first heat exchanger using the lean MEG discharged to the bottom of the distillation column.
The method of claim 1,
Further comprising a first heat exchanger installed at the front end of the rich MEG tank and heating the rich MEG discharged from the pretreatment unit using water discharged to the top of the distillation column,
Lean MEG discharged to the bottom of the distillation column is supplied to the rich MEG tank, MEG regeneration system.
The method of claim 1,
The salt removal membrane is a multi-stage structure, MEG regeneration system.
The method of claim 1,
Lean MEG discharged to the bottom of the distillation column contains 80 to 99.99% by weight of MEG, MEG regeneration system.
The method of claim 1,
The salt difference power generation unit is generated by the difference in concentration of the salt slurry and fresh water having a lower salt concentration than the salt slurry, MEG regeneration system.
The method of claim 1,
The salinity difference power generation unit pressure delay osmosis method is applied, MEG regeneration system.
A marine structure comprising the MEG regeneration system of claim 1.

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