QUENCH WATER HYDROCYCLONE

Abstract

An apparatus for processing liquid from a quench water tower includes a first pipe for removing the liquid from the quench water tower; a hydrocyclone in fluid communication with the first pipe and in which the liquid is separated into particulate and liquid constituents by centrifugal force; and an oil-water separator downstream of and in fluid communication with a first outlet of the hydrocyclone. A related system and method are also provided.

Claims

1. A system for processing liquid from a quench water tower, comprising: a quench water tower; a first pipe for removing the liquid from the quench water tower; a hydrocyclone in fluid communication with the first pipe and in which the liquid is separated into particulate and liquid constituents by centrifugal force; and an oil-water separator downstream of and in fluid communication with a first outlet of the hydrocyclone.

2. The system of claim 1, further comprising a second pipe in fluid communication with a second outlet of the hydrocyclone and an inlet of the quench water tower through which the liquid constituent is returned to said quench water tower.

3. The system of claim 2, further comprising at least one cooling apparatus coacting with the second pipe for cooling the liquid constituent passing through said second pipe.

4. The system of claim 1, further comprising a pump in fluid communication with the first pipe for moving the liquid from the quench water tower through the first pipe to the hydrocyclone.

5. The system of claim 1, further comprising a third pipe in fluid communication with the oil-water separator for removing process water therefore.

6. The system of claim 5, further comprising a fourth pipe in fluid communication with the oil-water separator for removing heavy oil therefrom.

7. An apparatus downstream of and for processing liquid from a quench water tower, comprising: a first pipe for removing the liquid from the quench water tower; a hydrocyclone in fluid communication with the first pipe and in which the liquid is separated into particulate and liquid constituents by centrifugal force; and an oil-water separator downstream of and in fluid communication with a first outlet of the hydrocyclone.

8. A method of processing liquid from a quench water tower, comprising: removing the liquid from the quench water tower; exerting a centrifugal force on the liquid with a hydrocyclone for separating said liquid into particulate and liquid constituents; and further separating the particulate and liquid constituents downstream of the exerting centrifugal force.

9. The method of claim 8, further comprising returning the liquid constituent to the quench water tower, and directing the particular constituent to the further separating.

10. The method of claim 8, wherein the liquid comprises a waste stream from a chemical processing plant.

11. The method of claim 8, wherein the liquid comprises a waste stream from an ethylene plant.

12. The method of claim 8, further comprising venting any gas from an ullage above the liquid in said quench water tower and from said ullage for subsequent processing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of the present invention, reference may be had to the following description of exemplary embodiments considered in connection with the accompanying drawing Figures, of which:

[0013] FIG. 1 shows a schematic of a known quench water tower system to cool furnace effluent;

[0014] FIG. 2 shows a perspective view of a known hydrocyclone; and

[0015] FIG. 3 shows a schematic of a quench water hydrocyclone apparatus and system embodiment according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Before explaining the inventive embodiments in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, if any, since the invention is capable of other embodiments and being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

[0017] In the following description, terms such as a horizontal, upright, vertical, above, below, beneath and the like, are to be used solely for the purpose of clarity illustrating the invention and should not be taken as words of limitation. The drawings are for the purpose of illustrating the invention and are not intended to be to scale.

[0018] As used herein, the term ullage refers to an amount of a tank or container not being full.

[0019] Referring to FIG. 3, and in general, the total bottoms or the liquids 114 from the quench water tower 110, which include quench water, process water, heavy oils and solids, are delivered from an outlet 123 of the tower into a pipe 125 in fluid communication with a pump 140 and through a line 134 to the hydrocyclone 122 by a pump 140. The quench water tower resembles a tank or a vessel. The stream 50 moving through the line 134 contains the quench water, the process water and all heavy oils and solids, and is separated by centrifugal force in the hydrocyclone 122. The heavy stream 138 leaving an outlet of the hydrocyclone 122 contains all the process water, all heavy oils and solids, and is sent through a line 52 to the oil/water separator 118. The remaining water from the hydrocyclone 122 is the quench water, which is now free of heavy oils and solids and can therefore be recirculated through a line 56 as a quench water stream 54 to the heat exchanger 142 and thereafter to the quench water tower 110. The embodiment of FIG. 3 can be used for example in an ethane-cracking ethylene plant.

[0020] Separation of the liquid stream 50 in the hydrocyclone 122 into particulate and liquid constituents results in a particulate laden heavy stream 138 directed in the line 52 to the oil-water separator 118 from an outlet of the hydrocyclone, and the quench water stream 54 which is directed through a line 56 to the heat exchanger 142 and quench water tower 110.

[0021] At least one and in certain applications a plurality of quench water heat exchangers 142 or coolers coact with the line 56 to cool the quench water from the hydrocyclone 122 before the quench water is fed into the tower 110.

[0022] Cooled furnace(s) gases in the ullage space 111, which now have a reduced water content and are without solids and heavy hydrocarbons, are removed or exhausted from the upper portion of the column through a nozzle 58, for example. The gases from the ullage space 111 are delivered to a charge gas compressor 60 and then to an ethylene plant 62 for further processing.

[0023] The present embodiments can be applied to quench water towers that use multiple quench water loops. The hydrocyclones can serve to concentrate the heavy oils into the hotter sections of the loops to avoid fouling cooling exchangers.

[0024] Some gas crackers use either a separate vessel or the lowest section of the quench water tower 110 to saturate the incoming furnace effluent with water. The water used in these systems is separate from the quench water used to cool the furnace effluent. A large portion of the circulating water from the saturator is vaporized by the furnace effluent and is condensed by the circulating quench water. In these plants, a hydrocyclone could be used on the quench water. The hydrocyclone would remove heavy oils and solids from the quench water and return same, along with the condensed water from the saturator, to the saturator system. This would prevent fouling of quench water cooling exchangers.

[0025] While the quench water hydrocyclone 122 can be used in new constructions, it has advantages for use as a retrofit to an existing plant. For example, the process water effluent from the hydrocyclone can be sent to an oil/water separator 118 which is disposed at a remote location from the quench water tower. Most conventional plants place the oil/water separator next to the quench water tower so the separator can be fed by gravity.

[0026] The integration of a cyclone improves significantly the quench water quality because i) the quench water can be cooled without concern that the heavy oils will solidify and foul the exchangers, ii) the oil content is significantly reduced in the quench water bottoms, which reduces the possibility of fouling of the quench water tower bottoms, and iii) solids are voided which would otherwise foul the quench water coolers and the quench water tower.

[0027] It will be understood that the embodiments described herein are merely exemplary, and that a person skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described herein and defined in the appended claims. It should be understood that the embodiments described above are not only in the alternative, but can be combined.