U.S. patent application number 13/542030 was filed with the patent office on 2014-01-09 for integrated thermosiphon reboiler-condensate pot system and process for use thereof.
This patent application is currently assigned to Chevron U.S.A. Inc.. The applicant listed for this patent is Nicholas Gerard Brancaccio, Robert Paul Hohmann, Les Leszek Jackowski, Robert William Whitsitt, Billy Ray Williams. Invention is credited to Nicholas Gerard Brancaccio, Robert Paul Hohmann, Les Leszek Jackowski, Robert William Whitsitt, Billy Ray Williams.
Application Number | 20140008034 13/542030 |
Document ID | / |
Family ID | 49877619 |
Filed Date | 2014-01-09 |
United States Patent
Application |
20140008034 |
Kind Code |
A1 |
Jackowski; Les Leszek ; et
al. |
January 9, 2014 |
INTEGRATED THERMOSIPHON REBOILER-CONDENSATE POT SYSTEM AND PROCESS
FOR USE THEREOF
Abstract
Disclosed is an integrated thermosiphon reboiler-condensate pot
which integrates a condensate collection volume into a thermosiphon
reboiler and avoids the need for an external condensate pot or
steam trap. Also disclosed are a method for operating the
integrated thermosiphon reboiler-condensate pot, a system including
the integrated thermosiphon reboiler-condensate pot and a method
for retrofitting an existing thermosiphon reboiler.
Inventors: |
Jackowski; Les Leszek;
(Concord, CA) ; Williams; Billy Ray; (Napa,
CA) ; Hohmann; Robert Paul; (El Cerrito, CA) ;
Brancaccio; Nicholas Gerard; (Walnut Creek, CA) ;
Whitsitt; Robert William; (Missouri City, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Jackowski; Les Leszek
Williams; Billy Ray
Hohmann; Robert Paul
Brancaccio; Nicholas Gerard
Whitsitt; Robert William |
Concord
Napa
El Cerrito
Walnut Creek
Missouri City |
CA
CA
CA
CA
TX |
US
US
US
US
US |
|
|
Assignee: |
Chevron U.S.A. Inc.
San Ramon
CA
|
Family ID: |
49877619 |
Appl. No.: |
13/542030 |
Filed: |
July 5, 2012 |
Current U.S.
Class: |
165/11.1 ;
165/104.21; 29/401.1 |
Current CPC
Class: |
F28D 7/16 20130101; F28D
15/00 20130101; Y10T 29/49716 20150115; F28F 2265/06 20130101 |
Class at
Publication: |
165/11.1 ;
165/104.21; 29/401.1 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. An integrated thermosiphon reboiler-condensate pot, comprising:
a. a plurality of tubes having upper ends and lower ends, the tubes
configured to contain a process fluid; b. an upper tubesheet having
a plurality of apertures to receive the upper ends of the plurality
of tubes; c. a lower tubesheet having a plurality of apertures to
receive the lower ends of the plurality of tubes; d. a channel head
adjacent and attached to the upper tubesheet such that the channel
head and the upper tubesheet together define a channel volume in
fluid communication with the tubes and having a vapor outlet; e. a
shell defining a shell volume surrounding the plurality of tubes
for containing a heating medium and having a heating medium inlet
in fluid communication with the shell volume; f. a floating head
cover adjacent and attached to the lower tubesheet such that the
floating head cover and the lower tubesheet together define a
floating head volume in fluid communication with the tubes; g. an
integrated condensate pot-shell cover attached to the shell wherein
the integrated condensate pot-shell cover and lower tubesheet
together define a condensate collection volume for collecting
heating medium condensate from the shell volume, the integrated
condensate pot-shell cover having a condensate outlet in fluid
communication with the condensate collection volume and a process
fluid inlet in fluid communication with the floating head volume;
and h. a process fluid conduit providing fluid communication
between the process fluid inlet and the floating head volume.
2. The integrated thermosiphon reboiler-condensate pot of claim 1,
wherein the integrated condensate pot-shell cover further comprises
fluid detectors in communication with a controller for controlling
the condensate level within the condensate collection volume.
3. The integrated thermosiphon reboiler-condensate pot of claim 1,
wherein the process fluid conduit providing fluid communication
between the process fluid inlet and the floating head volume
includes an expansion joint or tail pipe.
4. The integrated thermosiphon reboiler-condensate pot of claim 1,
wherein the integrated thermosiphon reboiler-condensate pot is
vertically oriented.
5. The integrated thermosiphon reboiler-condensate pot of claim 1,
wherein the integrated thermosiphon reboiler-condensate pot is one
of a once-through type reboiler and a recirculating type
reboiler.
6. A method for operating a thermosiphon reboiler comprising: a.
feeding a process fluid from a distillation column or reactor to
the process fluid inlet of the integrated thermosiphon
reboiler-condensate pot of claim 1; b. operating the integrated
thermosiphon reboiler-condensate pot to heat the process fluid
within the plurality of tubes to provide a fluid mixture which
results in a desired heat duty delivered to the column or reactor;
and c. delivering the fluid mixture to the distillation column or
reactor through the vapor outlet.
7. A system for supplying heat to a distillation column or reactor,
the system comprising: a. a distillation column or reactor; and b.
the integrated thermosiphon reboiler-condensate pot of claim 1
wherein the process fluid inlet of the integrated thermosiphon
reboiler-condensate pot is in fluid communication with a process
fluid stream outlet from the distillation column or reactor and the
vapor outlet of the integrated thermosiphon reboiler-condensate pot
is in fluid communication with a process fluid stream inlet to the
distillation column or reactor; wherein the integrated thermosiphon
reboiler-condensate pot is not connected to an external condensate
pot or steam trap.
8. A method for retrofitting an existing thermosiphon reboiler
having an existing shell cover attached to a shell containing a
shell volume and adjacent a lower tubesheet in which the shell
cover is connected to an external condensate pot or steam trap,
comprising: a. disconnecting the external condensate pot or steam
trap from the thermosiphon reboiler; b. disconnecting any lines
associated with external condensate pot or steam trap; c. detaching
the existing shell cover from the shell of the thermosiphon
reboiler; and d. attaching an integrated condensate pot-shell cover
to the shell adjacent the lower tubesheet such that the integrated
condensate pot-shell cover and lower tubesheet together define a
condensate collection volume for collecting heating medium
condensate from the shell volume wherein the integrated condensate
pot-shell cover has a condensate outlet in fluid communication with
the condensate collection volume and a process fluid inlet.
9. The method of claim 8, wherein the integrated condensate
pot-shell cover further comprises fluid detectors in communication
with a controller for controlling the condensate level within the
condensate collection volume.
Description
FIELD
[0001] The present disclosure relates to a thermosiphon reboiler
such as the type used to provide heat to industrial distillation
columns, and further relates to a thermosiphon reboiler having a
means for collecting condensate.
BACKGROUND
[0002] Thermosiphon reboilers, also referred to as thermosyphon
reboilers or calandrias, are commonly used as heat exchangers in
industrial processes. Thermosiphon reboilers are commonly used to
provide heat to distillation columns or reactors. For instance,
thermosiphon reboilers are designed to receive a liquid stream from
the column bottom. The liquid is heated to boiling whereupon lower
density vapor is generated, rises and is returned to the
distillation column to enhance separations within the distillation
process. The rising of the vapor creates natural recirculation of
the column bottoms from the column, through the reboiler and back
to the column without the need for a mechanical pump. Known
thermosiphon reboilers may be categorized as vertical or
horizontal, and as once-through or recirculating. Steam is
generally used as the heat transfer medium.
[0003] Condensate management systems typically used with
thermosiphon reboilers include steam traps, flooding reboiler tubes
with condensate and use of an external condensate pot. Known
systems using steam traps, as depicted in FIG. 2, are commonly
subject to failure of moving parts, and are therefore not
considered reliable. Another example of a condensate control system
used with thermosiphon reboilers is flooding reboiler tubes with
condensate to control the reboiler duty by changing an acting
surface area of the reboiler. Such systems commonly have reboiler
tube failures at the tube-condensate interface. Yet another example
of a condensate control system used with thermosiphon reboilers is
an external condensate pot or pressure vessel with a balancing or
equalizing line provided between the top of the condensate pot and
the steam line, as depicted in FIG. 1. This is generally the most
reliable of the known condensate control systems; however, such a
system requires plot space for the condensate pot, balancing line
and associated piping. Such space is not always available in a
process plant.
[0004] There remains a need for a way to manage thermosiphon
reboiler condensate which would avoid the aforementioned
problems.
SUMMARY
[0005] In one aspect, an integrated thermosiphon
reboiler-condensate pot is provided. The integrated thermosiphon
reboiler-condensate pot includes a plurality of tubes configured to
contain a process fluid to be heated, the tubes being supported
between an upper tubesheet and a lower tubesheet, and a channel
head adjacent and attached to the upper tubesheet such that the
channel head and the upper tubesheet together define a channel
volume in fluid communication with the tubes and having a two-phase
(liquid and vapor) or vapor only outlet. The integrated
thermosiphon reboiler-condensate pot further includes a shell
defining a shell volume surrounding the plurality of tubes for
containing a heating medium and having a heating medium inlet. The
integrated thermosiphon reboiler-condensate pot includes an
integrated condensate pot-shell-cover attached to the shell and
adjacent the lower tubesheet such that the integrated condensate
pot-shell cover and lower tubesheet together define a condensate
collection volume for collecting heating medium condensate from the
shell volume and having a condensate outlet in fluid communication
with the condensate collection volume and a process fluid
inlet.
[0006] In another aspect, a method for operating the integrated
thermosiphon reboiler-condensate pot to deliver a fluid mixture
having a desired heat duty to a distillation column or reactor
through the vapor outlet is provided.
[0007] In another aspect, a system is provided including the
integrated thermosiphon reboiler-condensate pot and the
distillation column or reactor, wherein the integrated thermosiphon
reboiler-condensate pot is not connected to an external condensate
pot or steam trap.
[0008] In yet another aspect, a method for retrofitting an existing
thermosiphon reboiler is provided to result in the integrated
thermosiphon reboiler-condensate pot.
DESCRIPTION OF THE DRAWINGS
[0009] These and other objects, features and advantages of the
present invention will become better understood with reference to
the following description, appended claims and accompanying
drawings where:
[0010] FIG. 1 is a schematic diagram illustrating a thermosiphon
reboiler with an associated external condensate pot according to
the prior art.
[0011] FIG. 2 is a schematic diagram illustrating a thermosiphon
reboiler with an associated steam trap according to the prior
art.
[0012] FIG. 3 is a schematic diagram illustrating a thermosiphon
reboiler with integrated condensate pot according to an exemplary
embodiment.
DETAILED DESCRIPTION
[0013] A system including a thermosiphon reboiler 110 connected to
an external condensate pot 48, according to the prior art, is shown
in FIG. 1. The reboiler 110 includes a plurality of tubes 2 for
containing a process fluid to be heated. The upper ends 2a of the
tubes 2 are received and supported by apertures in an upper
tubesheet 4, and the lower ends 2b of the tubes 2 are received and
supported by apertures in a lower tubesheet 6. A shell 14 surrounds
the plurality of tubes 2 and defines a shell volume there within in
which is contained a heating medium for imparting heat to the
plurality of tubes 2. The shell 14 includes a heating medium inlet
16 through which heating medium can be introduced to the shell
volume. A heating medium line 17 delivers heating medium, e.g.
steam, from a heating medium source 70 to the heating medium inlet
16. The system can be provided with a control valve 62 for
controlling the delivery of heating medium to the heating medium
inlet 16.
[0014] A channel head 8, also referred to as a head, is attached to
the upper end of the shell 14. The channel head 8 is generally
attached to the shell 14 by way of bolts (not shown) through
flanges with the upper tubesheet 4 there between such that the
channel head 8 and the upper tubesheet 4 together define a channel
volume. Heated process fluid in the form of liquid and vapor or
vapor only rises from the tubes 2 into the channel volume. An
outlet 12 in the channel head 8 allows the liquid and vapor or
vapor only 68 to be returned to a column or reactor (not shown) to
which the reboiler-condensate pot is connected. The head can be any
known construction, e.g., a bonnet or channel type head.
[0015] A shell cover 40 is attached to the lower end of the shell
14. The shell cover 40 is generally attached to the shell 14 by way
of bolts through flanges. The shell cover 40, the lower tubesheet
6, and the space between the lower tubesheet 6 and condensate
outlet 42 define a condensate collection volume. During use,
condensate from the shell volume collects in the condensate
collection volume within the shell cover 40 and the space between
the lower tubesheet 6 and condensate outlet 42. A condensate outlet
42 is installed typically in the shell 14. In some instances, the
condensate outlet 42 may be installed in the shell cover 20 below
the lower tubesheet 6. The condensate is sent to an external
condensate pot 48 via line 43.
[0016] Condensate pot 48 is equipped with fluid detectors 50a and
50b connected with a level controller 30 for controlling the
condensate level within the condensate pot 48 such that the level
is maintained between 50a and 50b. The level controller 30 can be
connected to a control valve 32 via a signal line 31 which can be
used to control the condensate level in the condensate pot 48 and
direct condensate to a condensate header 64. Reboiler-condensate
pot pressure equalizing line 52 is often provided. As shown, this
equalizing line 52 can be tied into the heating medium line 17.
Alternatively, the equalizing line may be connected to the heating
medium inlet 16 or the shell 14 directly.
[0017] A process fluid inlet 46 is provided in the shell cover 40
through which process fluid 66 is fed from the column or reactor to
which the reboiler is connected. The process fluid inlet 46 is in
fluid communication with a line, also referred to as process fluid
conduit 26, running between the process fluid inlet 46 and the
plurality of tubes 2.
[0018] The lower tubesheet 6 is attached to a floating head cover
18 (typically by bolting the floating head cover 18 to a ring
flange 19) such that the floating head cover 18 and the lower
tubesheet 6 together define a floating head volume in fluid
communication with the plurality of tubes 2. The floating head
cover 18 acts as a transition between the tubes 2 and the process
fluid inlet 46, as channel head 8 acts as a transition between the
tubes and outlet 12. The process fluid conduit 26 may include an
expansion joint 38 which allows for relative movement due to
thermal expansion of the shell 14 relative to the tubes 2 caused by
the temperature difference between process fluid and heating
medium. Alternatively, a tail pipe with a packing gland may be used
in lieu of the expansion joint, as would be apparent to one skilled
in the art.
[0019] The shell cover 40 can also include a drain 44 which can be
used for draining condensate from the reboiler for the purposes of
shutdown, cleaning and the like.
[0020] The reboiler also includes a vent 41 located in the shell 14
for venting vapor or non-condensable gases from the reboiler.
[0021] A similar system according to the prior art utilizing an
external steam trap 54 in place of an external condensate pot 48 is
shown in FIG. 2.
[0022] An integrated thermosiphon reboiler-condensate pot 10, also
referred to interchangeably as the integrated reboiler-condensate
pot and the reboiler-condensate pot, according to one embodiment,
is shown in FIG. 3. Like reference numerals refer to like
elements.
[0023] An integrated condensate pot-shell cover 20 is attached to
the lower end of the shell 14. The integrated condensate pot-shell
cover 20 is generally attached to the shell 14 by way of bolts
through flanges. The integrated condensate pot-shell cover 20 and
the lower tubesheet 6 together define a condensate collection
volume. During use, condensate from the shell volume collects in
the condensate collection volume within the integrated condensate
pot-shell cover 20. The integrated condensate pot-shell cover 20
acts as a condensate pot integrated with the reboiler. A condensate
outlet 22 is provided in the integrated condensate pot-shell cover
20 through which condensate can be sent to a condensate header (not
shown) where condensate is collected, and may be further used to
generate steam. A process fluid inlet 46 is provided in the
integrated condensate pot-shell cover 20 through which process
fluid 66 is fed from the column or reactor to which the
reboiler-condensate pot is connected. The process fluid inlet 46 is
in fluid communication with a line, also referred to as the process
fluid conduit 26, running between the process fluid inlet and the
plurality of tubes 2.
[0024] In one embodiment, the lower tubesheet 6 is attached to a
floating head cover 18 (typically by bolting the floating head
cover 18 to a ring flange 19) such that the floating head cover 18
and the lower tubesheet 6 together define a floating head volume in
fluid communication with the plurality of tubes 2. The process
fluid conduit 26 may include an expansion joint 38 or a tail pipe
as would be apparent to one skilled in the art.
[0025] In one embodiment, the integrated condensate pot-shell cover
20 is equipped with fluid detectors 28a and 28b connected with a
controller 30 for controlling the condensate level within the
condensate collection volume such that the level is maintained
between 28a and 28b. The level controller 30 can be connected to a
control valve 32 connected to the condensate outlet 22. The control
valve 32 can be opened to reduce the condensate level in the
condensate collection volume.
[0026] The integrated condensate pot-shell cover 20 of the
integrated thermosiphon reboiler-condensate pot 10 can also include
a drain 34 which can be used for draining condensate from the
apparatus for the purposes of shutdown, cleaning and the like.
[0027] The integrated thermosiphon reboiler-condensate pot 10 also
includes a vent 41 located in the shell 14 for venting vapor or
non-condensable gases from the integrated thermosiphon
reboiler-condensate pot.
[0028] The integrated thermosiphon reboiler-condensate pot can be
either horizontally or vertically oriented. The integrated
thermosiphon reboiler-condensate pot can be either a once-through
type reboiler or a recirculating type reboiler.
[0029] In one embodiment, a method for operating the integrated
thermosiphon reboiler-condensate pot 10 is provided. A process
fluid, such as column bottoms, from a distillation column or
reactor is fed to the process fluid inlet 46 of the integrated
thermosiphon reboiler-condensate pot 10. The heating medium, such
as steam or any other suitable heating medium, is fed through the
heating medium inlet 16, thereby heating the process fluid in the
plurality of tubes 2 to form a fluid mixture which results in a
desired heat duty delivered to the column or reactor, such as a
fluid mixture including vapor. The fluid mixture is delivered to
the column or reactor through the outlet 12.
[0030] In one embodiment, a system is provided including the
integrated thermosiphon reboiler-condensate pot 10 and a
distillation column or reactor (not shown) without the need for an
external condensate pot or steam trap connected to the
reboiler-condensate pot, with associated foundation, piping, and
pressure equalizing line. Such a system offers advantages of
reduced space requirements, lower capital cost by eliminating one
vessel with foundation and piping, lower maintenance cost by
eliminating a vessel, and greater simplicity and reliability.
[0031] According to the present disclosure, the column or reactor
can be any equipment which a reboiler is known to supply,
including, but not limited to, distillation columns, regenerators,
evaporators, batch reactors, continuous stirred tank reactors, and
the like. Exemplary distillation unit applications include, but are
not limited to, crude stabilizers, naphtha stabilizers, naphtha
splitters, de-ethanizers, de-butanizers, de-propanizers,
de-pentanizers, amine regenerators, sour water strippers,
hydrocracker fractionators, lube oil fractionators and styrene
recovery columns.
[0032] In one embodiment, a method for retrofitting an existing,
conventional thermosiphon reboiler connected to an external
condensate pot or steam trap is provided. In this method, the
external condensate pot or steam trap is disconnected from the
reboiler, as well as any lines associated with the external
condensate pot or steam trap. The shell cover of the existing
reboiler is then detached from the shell of the thermosiphon
reboiler, and replaced with an integrated condensate pot-shell
cover as described above such that the integrated condensate
pot-shell cover and lower tubesheet together define a condensate
collection volume for collecting condensate.
[0033] Where permitted, all publications, patents and patent
applications cited in this application are herein incorporated by
reference in their entirety; to the extent such disclosure is not
inconsistent with the present invention.
[0034] Unless otherwise specified, the recitation of a genus of
elements, materials or other components, from which an individual
component or mixture of components can be selected, is intended to
include all possible sub-generic combinations of the listed
components and mixtures thereof Also, "comprise," "include" and its
variants, are intended to be non-limiting, such that recitation of
items in a list is not to the exclusion of other like items that
may also be useful in the materials, compositions, methods and
systems of this invention.
[0035] From the above description, those skilled in the art will
perceive improvements, changes and modifications, which are
intended to be covered by the appended claims.
* * * * *