CN115046422A - Dew point corrosion prevention and control method for precooling heat exchanger of mixed refrigerant liquefaction system - Google Patents

Dew point corrosion prevention and control method for precooling heat exchanger of mixed refrigerant liquefaction system Download PDF

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Publication number
CN115046422A
CN115046422A CN202210810279.4A CN202210810279A CN115046422A CN 115046422 A CN115046422 A CN 115046422A CN 202210810279 A CN202210810279 A CN 202210810279A CN 115046422 A CN115046422 A CN 115046422A
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CN
China
Prior art keywords
dew point
natural gas
heat exchanger
mixed refrigerant
liquefaction system
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CN202210810279.4A
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Chinese (zh)
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袁淑霞
冀雪
樊玉光
许云凤
薛帅
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Xian Shiyou University
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Xian Shiyou University
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Priority to CN202210810279.4A priority Critical patent/CN115046422A/en
Publication of CN115046422A publication Critical patent/CN115046422A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
    • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
    • C10L3/10—Working-up natural gas or synthetic natural gas
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
    • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
    • C10L3/10—Working-up natural gas or synthetic natural gas
    • C10L3/101—Removal of contaminants
    • C10L3/106—Removal of contaminants of water
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors

Abstract

The invention relates to the field of dew point corrosion and corrosion prevention, and discloses a method for preventing and controlling dew point corrosion of a precooling heat exchanger of a mixed refrigerant liquefaction system, which is used for controlling heavy hydrocarbon C 8 And C 8 The mole fraction of the components in the natural gas is 0.04-0.1%. The invention provides a measure for preventing a precooling heat exchanger in the system from dew point corrosion from natural gas water and hydrocarbon dew point, and heavy hydrocarbon C is added into natural gas 8 And C 8 The components are used for firstly separating out liquid hydrocarbon during the cooling process to form a hydrocarbon dew point, and forming a water-in-oil state in a dew point solution without CO 2 The reaction is carried out, so that the problem of dew point corrosion of a precooling heat exchanger in a natural gas single-cycle mixed refrigerant liquefaction system is solved, the liquefaction efficiency of the natural gas is improved, and the theoretical significance and the practicability are certainFeasibility was practiced.

Description

Dew point corrosion prevention and control method for precooling heat exchanger of mixed refrigerant liquefaction system
Technical Field
The invention relates to the field of dew point corrosion and corrosion prevention, in particular to a method for preventing and controlling dew point corrosion of a precooling heat exchanger of a mixed refrigerant liquefaction system.
Background
The dew point of natural gas includes water dew point and hydrocarbon dew point, wherein the water dew point of natural gas refers to the temperature of first drop of water separated out from natural gas under a certain pressure condition, and the hydrocarbon dew point refers to the temperature of first drop of liquid hydrocarbon separated out from natural gas under a certain pressure condition. The natural gas is usually dehydrated before entering the liquefaction system, but when the dehydration of the natural gas is not complete, trace moisture in the natural gas is cooled under certain pressure and temperature conditions, and reacts with carbon dioxide in the natural gas to form acidic substances, so that related equipment in the natural gas liquefaction system is corroded.
The existing dew point corrosion protection measures mainly take flue gas dew point corrosion protection measures and hydrochloric acid dew point corrosion protection measures. The protection measures for the dew point corrosion of the flue gas mainly comprise the steps of optimizing the property of the fuel oil, reducing the sulfur content of the fuel, controlling the oxygen content of the heating furnace, controlling the water vapor content in the flue gas, increasing the temperature of the pipe wall of the equipment and the like. The hydrochloric acid dew point corrosion protection measures mainly comprise wet washing, dry steam washing, electric desalting, ammonia injection, water injection and corrosion inhibitor injection methods. Few studies are currently being made on the measures for protection against dew point corrosion of natural gas.
The natural gas dew point control technology mainly comprises three methods of low-temperature separation, solid adsorption and solvent absorption, wherein the low-temperature separation method can simultaneously realize deoiling and dehydration, meets the control requirements of water dew points and hydrocarbon dew points, has simple flow, low investment and low operating cost, and is widely applied to the petrochemical industry. In the aspect of controlling the dew point of natural gas by a low-temperature separation method, Zhang Wen super in 2014 and the like, the low-temperature separation process is determined according to the gas quality characteristics of micro condensate oil in gas produced from a Scottish gas field and by combining the index requirements of product natural gas and the specific application of a natural gas dew point control process. And the UniSim Design software is utilized to analyze the determination method and process of the condensation temperature in detail, discuss the selection of key equipment such as a refrigeration process, a precooling heat exchanger, a low-temperature separator and the like, and finally determine that the low-temperature separation process taking propane as an external cold source is completely suitable for the natural gas dew point control of the Suliger gas field. In the aspect of a natural gas dew point control device, Sun Lei in 2017 optimizes the natural gas dew point control device of a certain gas field in Qinghai, a propane refrigeration system is adopted for cooling, dehydrating and dealkylating originally, but the device has high energy consumption, old equipment and poor economic benefit, so that the optimization is performed from the aspects of key equipment type selection, anti-freezing agent injection and the like. In the original device, a separator is not arranged behind a precooling heat exchanger, one-time injection is adopted according to needs for freezing prevention, and two-stage cooling and two-stage alcohol injection processes are adopted after optimization, so that the injection amount of ethanol is saved, and the regeneration energy consumption of ethylene glycol is reduced.
In conclusion, the current research on the dew point corrosion protection technology mainly focuses on the flue gas dew point corrosion protection and the hydrochloric acid dew point corrosion protection, and the research on the natural gas dew point corrosion protection technology is less. In many studies on the natural gas dew point control technology, the dew point of a specific device is controlled, and the pipeline natural gas dew point control technology is mainly studied. The natural gas single-cycle mixed refrigerant liquefaction system has the advantages of small equipment quantity, simple flow, low investment on liquefaction devices and the like, and can adapt to the physical property change of raw material gas by adjusting the composition of the mixed refrigerant in the cooling process. In the liquefaction process, the natural gas is mainly cooled step by step through compression, condensation, throttling and cooling, liquefaction, absorption gasification and the like of mixed refrigerant, and main heat exchange equipment of the natural gas comprises a precooling heat exchanger, an intercooling heat exchanger and a cryogenic heat exchanger.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for preventing and controlling dew point corrosion of a precooling heat exchanger of a mixed refrigerant liquefaction system.
The inventor finds that the heavy components i-C in the natural gas 5 、n-C 5 、C 6 、C 7 When the mole fraction is 0.02-0.1%, the dew point types of the natural gas are water dew pointsAnd the pH value of the dew point solution is small, so that dew point corrosion can be caused to related parts in the precooling heat exchanger; heavy component C in natural gas 8 And C 8 When the mole fraction of any one or combination of more than 0.04% of the above components is greater than or equal to 0.04%, the content of liquid heavy hydrocarbon in the dew point solution is far greater than that of liquid water, the dew point type is hydrocarbon dew point, the dew point solution presents a water-in-oil state, namely the liquid heavy hydrocarbon in the dew point solution is a continuous phase and the liquid water is a dispersed phase, at this time, although trace CO exists 2 Dissolved in the dew point solution, but does not cause dew point corrosion to relevant parts in the precooling heat exchanger.
By combining the research results, the invention adopts the following technical scheme:
a mixed refrigerant liquefaction system precooling heat exchanger dew point corrosion prevention and control method controls heavy hydrocarbon C 8 And C 8 The mole fraction of any one or the combination of more of the components in the natural gas is 0.04-0.1%.
Further, said C 8 The above components including C 9 、C 10 And C 11 。
Further, heavy hydrocarbon C is added to the natural gas before it begins to liquefy 8 And C 8 Any one or combination of more of the above components.
Further, containing heavy hydrocarbons C 8 And C 8 After the natural gas of any one or combination of a plurality of components is liquefied by the precooling heat exchanger, the liquefied natural gas is separated into gas phase natural gas, liquid heavy hydrocarbon and liquid water by the three-phase separator, wherein the gas phase natural gas, the liquid heavy hydrocarbon and the liquid water contain C 8 And C 8 The liquid heavy hydrocarbon of any one or combination of several of the components is recycled.
Further, the recovered C-containing 8 And C 8 The liquid heavy hydrocarbon of any one or combination of several of the above components is atomized by the heavy hydrocarbon atomizer and then directly returns to the natural gas transportation pipeline to be liquefied, and then enters the precooling heat exchanger again for liquefaction.
Further, the method is suitable for a natural gas mixed refrigeration liquefaction system.
In a preferred embodiment of the present invention, the method of the present invention is applied to a natural gas single cycle hybrid refrigeration liquefaction train.
Furthermore, the invention can also be applied to a propane precooling mixed refrigerant liquefaction system, a double-circulation mixed refrigerant liquefaction system and the like.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a measure for preventing a precooling heat exchanger in the system from dew point corrosion from natural gas water and hydrocarbon dew point, and heavy hydrocarbon C is added into natural gas 8 And C 8 Any one or combination of several of the components is adopted to solve the dew point corrosion problem of the precooling heat exchanger in the natural gas single-cycle mixed refrigerant liquefaction system, so that the natural gas single-cycle mixed refrigerant liquefaction system is favorable for improving the liquefaction efficiency of the natural gas, and has certain theoretical significance and practical feasibility.
(2) The invention also realizes C by adding related equipment 8 And C 8 Any one or combination of more of the above components can be recycled.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 shows the mass flow rate of each component in the dew point solution as a function of temperature, wherein (a) the mass flow rate of each component in the dew point solution as a function of temperature, and (b) CO in the dew point solution 2 Mass flow rate variation with temperature;
FIG. 2 shows the variation of the pH value of the dew point solution with the mass flow of the dew point solution
FIG. 3 shows the dew point temperature of natural gas, dew point type a and pH value b of dew point solution as a function of i-C 5 Change in mole fraction;
FIG. 4 shows the dew point temperature of natural gas, the dew point type a and the pH value b of a dew point solution with n-C 5 Change in mole fraction;
FIG. 5 shows the dew point temperature of natural gas, dew point type a, and pH b of dew point solution as a function of C 6 Change in mole fraction;
FIG. 6 shows natural gas dew point temperature, dew point typea and dew point solution pH b with C 7 Change in mole fraction;
FIG. 7 shows the dew point temperature and dew point type of natural gas as a function of C 8 Change in mole fraction;
FIG. 8 is C 8 The mass flow of each component in the natural gas dew point solution with the mole fraction of 0.04 percent is changed along with the temperature;
FIG. 9 is C 9 The mass flow of each component in the natural gas dew point solution with the mole fraction of 0.04 percent is changed along with the temperature;
FIG. 10 is C 10 The mass flow of each component in the natural gas dew point solution with the mole fraction of 0.04 percent is changed along with the temperature;
FIG. 11 is C 11 The mass flow of each component in the natural gas dew point solution with the mole fraction of 0.04 percent is changed along with the temperature;
FIG. 12 is a schematic view of an apparatus system for carrying out the method of the present invention (note: all intersecting lines are not connected).
Reference numerals: 1 is a gas-liquid separating tank; 2, a natural gas precooling heat exchanger; 3 is a three-phase separator; 4 is a gas-liquid separating tank; 5 is a natural gas intercooling heat exchanger; 6 is a natural gas cryogenic heat exchanger; 7 is an LNG flash tank; 8 is a refrigerant mixer; 9 is a refrigerant mixer; 10 is a heavy hydrocarbon atomizer.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Taking a natural gas single-cycle mixed refrigerant liquefaction system as an example, the existing liquefaction process has the problems that trace water or liquid hydrocarbon is cooled out in the process of cooling gaseous natural gas in a precooling heat exchanger, and the natural gas contains trace CO 2 Under certain pressure and temperature conditions, CO 2 Will dissolve in liquid water to form high-concentration acid solutionThe liquid causes dew point corrosion to related equipment in the precooling heat exchanger, not only can cause adverse effect to the service life of the precooling heat exchanger, but also can seriously threaten the safety production of natural gas enterprises.
Through related researches, when the natural gas consists of the light components shown in the following table 1, the mass flow of each component in the dew-point solution changes with the temperature after the dew-point temperature is reached are shown in the left side of the following figure 1, and after the dew-point temperature is reached, CO 2 The mass flow of the liquid phase component is greatly different from the mass flow of other components in the natural gas, so that CO is introduced 2 The mass flow of the liquid phase component is described below on the right side of FIG. 1.
Table 1 light component natural gas
Components C 1 C 2 C 3 i-C 4 n-C 4 CO 2 H 2 O
Raw material gas (mol%) 92.00 4.00 0.75 0.12 0.12 3.00 0.01
The dew point temperature of the natural gas in the precooling heat exchanger in the natural gas single-cycle mixed refrigerant liquefaction system is-6.4 ℃, and the dew point solution mainly comprises liquid water, namely the dew point type is water dew point, and CO is obtained by the figure 1 2 Dew point corrosion occurs upon dissolution in a dew point solution and asAs can be seen from fig. 2, the pH value of the dew point solution in the precooling heat exchanger does not change with the increase of the mass flow of the dew point solution, the pH value of the dew point solution between-6 ℃ and-7 ℃ is 0.8, which causes dew point corrosion to the equipment, and as the temperature decreases, the mass flow of the dew point solution increases, that is, the mass flow of the acidic solution increases, and the corrosion degree to the equipment also gradually increases.
To solve the above problems, the inventors studied the heavy components i-C in natural gas 5 、n-C 5 、C 6 、C 7 、C 8 The effect of mole fraction on the dew point type of the natural gas and the corrosion status of the pre-cooling heat exchanger, where the composition of the natural gas is as shown in table 2 below:
table 2 natural gas with heavies
Components C 1 C 2 C 3 i-C 4 n-C 4 i-C 5 、n-C 5 、C 6 、C 7 、C 8 CO 2 H 2 O
Raw material gas (mol%) 91.98~91.90 4.00 0.75 0.12 0.12 0.02~0.1 3.00 0.01
The dew point temperature, the dew point type and the pH value of a dew point solution of the natural gas are obtained by research along with the heavy components i-C in the natural gas 5 、n-C 5 、C 6 、C 7 、C 8 The change in mole fraction is shown in FIGS. 3 to 7.
As can be seen from FIGS. 3 to 6, heavy components i-C in natural gas 5 、n-C 5 、C 6 、C 7 When the mole fraction is 0.02% -0.1%, the dew point types of the natural gas are all water dew points, and the pH value of the dew point solution is 0.84, so that the dew point corrosion can be caused to relevant parts in the precooling heat exchanger. As can be seen from FIG. 7, heavy component C in natural gas 8 When the mole fraction of (C) is 0.04-0.1%, the dew point type of the natural gas at that time is hydrocarbon dew point, the variation of the mass flow rate of each component in the dew point solution with the temperature is shown in FIG. 8, and C is added to the natural gas 8 In the above recombination, the dew point type of the natural gas is also the hydrocarbon dew point.
As can be seen from FIGS. 8 to 11, heavy component C in natural gas 8 And C 8 When the mole fraction of the components is 0.04%, the content of liquid heavy hydrocarbon in the dew point solution is far greater than that of liquid water, the dew point type is hydrocarbon dew point, the dew point solution presents a water-in-oil state, namely the liquid heavy hydrocarbon in the dew point solution is a continuous phase, the liquid water is a disperse phase, and at the moment, although trace CO exists 2 The natural gas is dissolved in the dew-point solution, but does not cause dew-point corrosion to related parts in the precooling heat exchanger, thereby influencing the liquefaction efficiency of the natural gas.
Combining the research results, the invention adds proper content of heavy hydrocarbon C in natural gas 8 And C 8 The components are used for preventing the precooling heat exchanger from generating dew point corrosion, and heavy hydrocarbon C is added 8 And C 8 After the natural gas with the components is liquefied by the precooling heat exchanger, the liquefied natural gas is separated into gas-phase natural gas, liquid heavy hydrocarbon and liquid water by a three-phase separator, wherein the gas-phase natural gas, the liquid heavy hydrocarbon and the liquid water contain C 8 And C 8 The liquid heavy hydrocarbon of the components directly returns to a natural gas transportation pipeline to be liquefied after being atomized by a heavy hydrocarbon atomizer, and enters precooling heat exchange againLiquefaction in a vessel, C 8 And C 8 The existence of the components can prevent the generation of water dew points in the precooling heat exchanger, further prevent the dew point corrosion of related components in the precooling heat exchanger, and improve the liquefaction efficiency of the natural gas single-cycle mixed refrigerant liquefaction system.
As shown in FIG. 12, in a natural gas single-cycle mixed refrigerant liquefaction system, natural gas (natural gas throughput 2800kmol/h, pressure 5MPa, temperature 40 ℃) was added with heavy hydrocarbon C before the natural gas began to liquefy 8 Of heavy hydrocarbons C 8 Relative to the content of heavy hydrocarbons C 8 The mole fraction of the natural gas is 0.04%, the natural gas is cooled to-70 ℃ through a precooling heat exchanger 2, the natural gas enters a three-phase separator 3 to be separated into gas-phase natural gas, liquid heavy hydrocarbon and liquid water, wherein the gas-phase natural gas is cooled to-137.5 ℃ through an intercooling heat exchanger 5, then is cooled to-162 ℃ through a cryogenic heat exchanger 6, finally is cooled to-160.2 ℃ through a throttle valve, is conveyed to an LNG flash tank 7, the flash gas is conveyed to a fuel gas mixing unit, and the LNG product is conveyed to an LNG storage tank. The heavy hydrocarbon separated by three-phase separator 3 is atomized by heavy hydrocarbon atomizer 10 before entering the natural gas pipeline to be liquefied, and will contain C 8 The heavy hydrocarbon is carried into the precooling heat exchanger again for liquefaction to realize C 8 The pre-cooling heat exchanger dew point corrosion is prevented from occurring. In the whole liquefaction process, the mixed refrigerant firstly enters a gas-liquid separation tank 1 to separate a gas phase and a liquid phase, both the gas phase and the liquid phase enter a precooling heat exchanger 2 to be cooled to-70 ℃, and the cooled liquid phase is mixed with the mixed refrigerant from an intercooling heat exchanger 5 to provide cold energy for the precooling heat exchanger 2; the cooled gas phase enters a gas-liquid separation tank 4 to be separated into a gas phase and a liquid phase again, and enters an intercooling heat exchanger 5 to be cooled to-137.5 ℃, wherein the cooled liquid phase is mixed with the mixed refrigerant from the cryogenic heat exchanger 6 to provide cold energy for the intercooling heat exchanger 5; the cooled gas phase enters the cryogenic heat exchanger 6 to be continuously cooled to-162 ℃, and then enters the cryogenic heat exchanger 6 through a throttle valve to provide cold energy for the cryogenic heat exchanger 6, so that the circulation of the mixed refrigerant is completed.
Those skilled in the art can understand that the method is not only applicable to a natural gas single-cycle mixed refrigeration liquefaction system, but also applicable to other natural gas mixed refrigerant refrigeration liquefaction systems, such as a propane pre-cooling mixed refrigerant liquefaction system, a dual-cycle mixed refrigerant liquefaction system and the like.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims (8)

1. A mixed refrigerant liquefaction system precooling heat exchanger dew point corrosion prevention and control method is characterized by controlling heavy hydrocarbon C 8 And C 8 The mole fraction of any one or the combination of more of the components in the natural gas is 0.04-0.1%.
2. The method for preventing and controlling dew point corrosion of a pre-cooling heat exchanger of a mixed refrigerant liquefaction system of claim 1, wherein C is 8 The above components including C 9 、C 10 And C 11 。
3. The mixed refrigerant liquefaction system precooling heat exchanger dew-point corrosion prevention and control method as recited in claim 1, wherein heavy hydrocarbon C is added to the natural gas before liquefaction is started 8 And C 8 Any one or combination of more of the above components.
4. The method for preventing and controlling dew point corrosion of the precooling heat exchanger of the mixed refrigerant liquefaction system according to any one of claims 1 to 3, wherein the mixed refrigerant liquefaction system contains heavy hydrocarbon C 8 And C 8 After the natural gas of any one or combination of a plurality of components is liquefied by the precooling heat exchanger, the liquefied natural gas is separated into gas phase natural gas, liquid heavy hydrocarbon and liquid water by the three-phase separator, wherein the gas phase natural gas, the liquid heavy hydrocarbon and the liquid water contain C 8 And C 8 The liquid heavy hydrocarbon of any one or combination of several of the components is recycled.
5. The mixed refrigerant liquefaction system according to claim 4The method for preventing and controlling the dew point corrosion of the system precooling heat exchanger is characterized in that the recycled C-containing gas 8 And C 8 The liquid heavy hydrocarbon of any one or combination of several of the above components is atomized by the heavy hydrocarbon atomizer and then directly returns to the natural gas transportation pipeline to be liquefied, and then enters the precooling heat exchanger again for liquefaction.
6. The method for preventing and controlling the dew point corrosion of the precooling heat exchanger of the mixed refrigerant liquefaction system according to any one of claims 1 to 3, which is suitable for a natural gas mixed refrigeration liquefaction system.
7. The method for preventing and controlling the dew point corrosion of the precooling heat exchanger of the mixed refrigerant liquefaction system according to any one of claims 1 to 3, which is suitable for a natural gas single-cycle mixed refrigeration liquefaction system.
8. The method for preventing and controlling the dew point corrosion of the pre-cooling heat exchanger of the mixed refrigerant liquefaction system according to any one of claims 1 to 3, wherein the method is suitable for a propane pre-cooling mixed refrigerant liquefaction system and a dual-cycle mixed refrigerant liquefaction system.
CN202210810279.4A 2022-07-11 2022-07-11 Dew point corrosion prevention and control method for precooling heat exchanger of mixed refrigerant liquefaction system Pending CN115046422A (en)

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