JP2009185089A - Hydrocarbon separation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrocarbon separation system can efficiently preventing piping from blocking, caused by the freezing of water content or formation of a gas hydrate. <P>SOLUTION: This hydrocarbon separation system 10 is provided by equipping at least a distillation device 51 separating a mixture containing at least water and a plurality of hydrocarbons to a low boiling component having its mass smaller than that of propane and a high boiling component having its mass of at least that of the propane by utilizing the difference of their boiling points and a water removal device 7 for removing the water content contained in the low boiling component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrocarbon separation system, and more particularly to a hydrocarbon separation system suitably used in a liquefied petroleum gas (LPG) refining process.

  Conventionally, in a purification process of LPG, etc., a low-boiling component whose mass is less than propane and a mass of propane or more by a distillation apparatus that separates a mixture containing a plurality of hydrocarbons using a difference in boiling points. Separation into certain high-boiling components has been carried out. FIG. 2 is a diagram for explaining a part of an example of a conventional LPG purification process. In FIG. 2, reference numeral 51 denotes a deethanizer (distillation device), reference numeral 52 denotes a condenser (cooling device), reference numeral 53 denotes a reflux drum, reference numeral 54 denotes a reflux pump, reference numeral 55 denotes a reboiler, and reference numeral 57 denotes a refrigerant. Reference numeral 9 denotes a valve, and reference numeral 8 denotes a control means.

  In FIG. 2, a mixed gas containing a plurality of hydrocarbons such as ethane, methane, propane and water vapor supplied from the gas supply line 6 a is mixed with a low-boiling component and a mass whose mass is less than propane by a deeerator 51. Is separated into high-boiling components that are higher than propane. The high boiling point component is discharged from the bottom of the deeerator 51 and recovered through the high boiling point component line 51b. Further, the low boiling point component is discharged from the top of the deeerator 51 and supplied to the capacitor 52 through the low boiling point component line 51a.

  The low boiling point component supplied to the capacitor 52 is cooled to a predetermined temperature and supplied to the reflux drum 53 via the low temperature low boiling point component line 52a. In the reflux drum 53, the condensed water generated by being cooled by the condenser 52 and the uncondensed component (gas component) are separated. The condensed water is discharged from the bottom of the reflux drum 53, pumped by the reflux pump 54, and returned to the top of the de-enerizer 51 at a predetermined flow rate through the reflux line 53b. Further, the gas component is discharged from the top of the reflux drum 53 and is discharged from the discharge port 6b through a gas discharge line 53a (illustrated).

However, the conventional LPG purification process shown in FIG. 2 has a problem in that the piping may be blocked due to freezing of water or generation of gas hydrate (gas hydrate).
As a method for preventing clogging of piping due to freezing of water or generation of gas hydrate, for example, there is a method of disposing a dehydrator on the upstream side of a distillation apparatus such as a deeternizer (for example, see Patent Document 1). .
JP 2006-175324 A

  However, even when a dehydrator is arranged on the upstream side of the detainer, piping may be blocked due to freezing of water or generation of gas hydrate. Specifically, for example, in the conventional LPG purification process shown in FIG. 2, even when the mixed gas dehydrated by the dehydrator is supplied from the gas supply line 6a, the low-temperature low boiling point cooled by the capacitor 52 is reduced. In the vicinity of the low-temperature low-boiling-point component line 52a through which the components pass or the discharge port 6b in the vicinity of the discharge port 6b where the pressure of the gas component flowing through the gas discharge line 53a decreases, the pipe may be blocked due to freezing of water or generation of gas hydrate. there were.

Further, in the conventional LPG purification process, when the piping is blocked, the purification process is temporarily stopped, and the low-temperature low-boiling component line 52a and the vicinity of the discharge port 6b, which are closed portions of the piping, are heated with a heater or the like to freeze the moisture. And a method of removing gas hydrate. However, this coping method has a problem that productivity is reduced because the purification process must be stopped once.
Also, by installing a heater in the vicinity of the low-temperature low-boiling component line 52a and the discharge port 6b, where the piping is likely to be blocked, the vicinity of the low-temperature low-boiling component line 52a and the discharge port 6b is always warmed, thereby freezing water and gas. A method for preventing the generation of hydrate is also conceivable. In this method, there is no problem of stopping the purification process, but there is a problem that the quality of the gas component discharged from the discharge port 6b is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydrocarbon separation system that can effectively prevent clogging of piping due to freezing of water or generation of gas hydrate.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and the moisture contained in the low boiling point component due to the azeotropic phenomenon with the low boiling point component in the distillation apparatus is the cause of the blockage of the moisture that causes the blockage of the pipe. It was found that it contributed to freezing and gas hydrate formation. And in order to prevent the clogging of the piping, the present inventors have arranged a moisture removing device downstream from the distillation device, and the distillation device contains the low boiling point component due to the azeotropic phenomenon with the low boiling point component. The present invention has been conceived by finding that it is effective to remove the generated water.

  That is, in the hydrocarbon separation system of the present invention, the difference between the boiling points of a mixture containing at least water and a plurality of hydrocarbons is divided into a low-boiling component having a mass of less than propane and a high-boiling component having a mass of propane or more. At least, and a water removing device for removing water contained in the low-boiling component.

  In the hydrocarbon separation system of the present invention, a cooling device for cooling the low-boiling-point component from which moisture has been removed by the moisture removing device is provided, and the cooling device can be an air-cooled heat exchanger. .

  Moreover, in the hydrocarbon separation system of this invention, the said water removal apparatus shall make a water | moisture content adsorb | suck to a crystalline zeolite.

  The hydrocarbon separation system of the present invention utilizes a difference in boiling point between a mixture containing at least water and a plurality of hydrocarbons, as a low-boiling component having a mass of less than propane and a high-boiling component having a mass of propane or more. And at least a water removal device for removing water contained in the low-boiling component, so that it was contained in the low-boiling component due to an azeotropic phenomenon with the low-boiling component in the distillation device. Moisture can be removed by a moisture removing device, and blockage of piping due to freezing of moisture or generation of gas hydrate can be effectively prevented.

“First Embodiment”
Hereinafter, an embodiment of a hydrocarbon separation system according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining a part of an example of a purification process of LPG using the hydrocarbon separation system of the present invention. In FIG. 1, the code | symbol 10 has shown the hydrocarbon separation system of this invention. The hydrocarbon separation system 10 includes a deethanizer (distilling device) 51, a moisture removing device 7, a filter 5, a condenser (cooling device) 52, a reflux drum 53, a reflux pump 54, A reboiler 55 and a refrigerant pipe 57 are provided.

  The deethanizer 51 is a mixture (a mixture) of a plurality of hydrocarbons such as ethane, methane, propane and water vapor supplied from the gas supply line 6a. The above high-boiling components are separated using the difference in boiling points. A reboiler 55 provided at the bottom of the detainer 51 gasifies the liquid stored at the bottom of the detainer 51 and supplies it again to the detainer 51.

  As shown in FIG. 1, the moisture removing device 7 includes a first dehydrator 2 and a second dehydrator 3. The first dehydrator 2 and the second dehydrator 3 are formed by filling a cylindrical container with a desiccant that adsorbs moisture. As the desiccant, molecular sieve (trade name) made of crystalline zeolite can be used. The crystalline zeolite is preferable because it can selectively adsorb and remove polar substances such as ethane having no polarity and water contained in methane.

  The first dehydrator 2 and the second dehydrator 3 are alternately used by switching between the two by opening and closing the valve 7b. Then, while the moisture is adsorbed to the desiccant of one of the first dehydrator 2 and the second dehydrator 3, the desiccant of the other dehydrator is regenerated. Therefore, the moisture removing device 7 can regenerate the desiccant without temporarily stopping the purification process, and can continuously adsorb moisture in the low-boiling components over a long period of time.

  The filter 5 is for removing the mixed desiccant when the desiccant is mixed in the low boiling point component that has passed through the moisture removing device 7.

The condenser 52 cools the low boiling point component separated by the de-enerizer 51. As shown in FIG. 1, the condenser 52 has a refrigerant pipe 57 through which a refrigerant for cooling the low boiling point component flows.
For example, a chiller or an air fin cooler can be used as the capacitor 52. In particular, the use of an air-cooled heat exchanger such as an air fin cooler is preferable because it can effectively prevent freezing of moisture in the low-boiling point component passing through the condenser 52 and generation of gas hydrate.

  The reflux drum 53 is for separating the condensed water generated by cooling the low boiling point component by the condenser 52 from the uncondensed component (gas component). The reflux pump 54 is for pumping the condensed water discharged from the bottom of the reflux drum 53 to the top of the deeerator 51 at a predetermined flow rate.

  In FIG. 1, a mixed gas containing a plurality of hydrocarbons such as ethane, methane, propane and water vapor supplied from the gas supply line 6a is mixed with a low-boiling component having a mass less than propane and a mass by a deethanizer 51. Is separated into high-boiling components that are higher than propane. Here, the water vapor contained in the mixed gas is contained not only in the high boiling point component but also in the low boiling point component due to the azeotropic phenomenon with the low boiling point component in the deethanizer 51. The separated high boiling point component is discharged from the bottom of the deeerator 51 and recovered through the high boiling point component line 51b. Further, the low boiling point component is discharged from the top of the deeerator 51 and is supplied to the moisture removing device 7 through the low boiling point component line 51a.

  It should be noted that the mixed gas supplied from the gas supply line 6a to the deaerator 51 is dehydrated in advance by a dehydrating device, thereby more effectively preventing moisture freezing and gas hydrate generation. Although it is preferable because it is possible, it may not be dehydrated.

  The low boiling point component supplied to the moisture removing device 7 passes through the container of the first dehydrator 2 or the second dehydrator 3, so that moisture is adsorbed by the desiccant filled in the container and dried. . The dried low-boiling component passes through the filter 5 disposed in the dry low-boiling component line 7a, and after the desiccant mixed in the low-boiling component is removed, the dried low-boiling component is supplied to the capacitor 52.

  The low boiling point component supplied to the capacitor 52 is cooled to a predetermined temperature and then supplied to the reflux drum 53 through the low temperature low boiling point component line 52a. In the reflux drum 53, the condensed water generated by being cooled by the condenser 52 and the uncondensed component (gas component) are separated. The condensed water is discharged from the bottom of the reflux drum 53, pumped by the reflux pump 54, and returned to the top of the de-enerizer 51 at a predetermined flow rate through the reflux line 53b. The gas component is discharged from the top of the reflux drum 53 and discharged from the discharge port 6b through the gas discharge line 53a.

  In FIG. 1, the opening and closing of the valve 9 is controlled by the control means 8 based on signals from a temperature sensor, a flow rate sensor, a pressure sensor, etc., so that the refrigerant pipe 57, the gas discharge line 53a, and the reflux line 53b. The flow rate is controlled.

  The hydrocarbon separation system 10 of the present embodiment has a difference in boiling point between a mixture containing at least water and a plurality of hydrocarbons, a low-boiling component having a mass of less than propane and a high-boiling component having a mass of propane or more. Is provided with a deethanizer 51 that separates by using a low-boiling point component and a moisture removing device 7 that removes moisture contained in the low-boiling point component. The moisture contained in the components can be removed by the moisture removing device 7, and the blockage of the piping due to the freezing of moisture and the generation of gas hydrate can be effectively prevented.

  Further, in the hydrocarbon separation system 10 of the present embodiment, the condenser 52 that cools the low-boiling-point component from which moisture has been removed by the moisture removing device 7 is provided, and when the condenser 52 is an air-cooled heat exchanger, The low boiling point component can be cooled while effectively preventing the freezing of water in the low boiling point component that has passed through the condenser 52 and the generation of gas hydrate, and the condensed water can be taken out from the low boiling point component.

In addition, this invention is not limited to embodiment mentioned above.
For example, in the embodiment described above, the moisture removing device 7 is disposed between the de-energizer 51 and the capacitor 52. However, the moisture removing device 7 is designed to remove the moisture contained in the low boiling point component. The disposition of the moisture removing device 7 is not limited to the above-described example as long as it is provided downstream of the nizer 51. For example, the moisture removing device 7 may be disposed between the condenser 52 and the reflux drum 53, or may be disposed in the vicinity of the discharge port 6b of the gas discharge line 53a. In addition, the installation position of the moisture removing device 7 may be only one place, or may be two or more places. You may install between the capacitor | condenser 52 and the reflux drum 53, or the discharge port 6b vicinity.

  Further, as shown in the above-described embodiment, when the condenser 52 for cooling the low boiling point component from which the moisture has been removed by the moisture removing device 7 is provided, the condensed water can be taken out from the low boiling point component, Although it is preferable because the quality of the gas component discharged from the discharge port can be improved, the capacitor may not be provided.

FIG. 1 is a diagram for explaining a part of an example of a purification process of LPG using the hydrocarbon separation system of the present invention. FIG. 2 is a diagram for explaining a part of an example of a conventional LPG purification process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... 1st dehydrator, 3 ... 2nd dehydrator, 5 ... Filter, 6a ... Gas supply line, 6b ... Discharge port, 7 ... Moisture removal apparatus, 7a ... Dry low boiling point component line, 7b, 9 ... Valve, 8 ... Control means 51 ... Dietizer (distillation device) 51a ... Low boiling point component line 52 ... Condenser (cooling device) 52a ... Low temperature low boiling point component line 53 ... Reflux drum 53a ... Gas discharge line 53b Reflux line 54 Reflux pump 55 Reboiler 57 Refrigerant pipe 10 Hydrocarbon separation system

Claims (3)

A distillation apparatus for separating a mixture containing at least water and a plurality of hydrocarbons into a low-boiling component having a mass of less than propane and a high-boiling component having a mass of propane or more by utilizing a difference in boiling points;
A hydrocarbon separation system comprising at least a moisture removing device for removing moisture contained in the low boiling point component. A cooling device for cooling the low-boiling point components from which moisture has been removed by the moisture removing device;
The hydrocarbon separation system according to claim 1, wherein the cooling device is an air-cooled heat exchanger.   3. The hydrocarbon separation system according to claim 1, wherein the moisture removing device adsorbs moisture on the crystalline zeolite. 4.

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