U.S. patent application number 09/992748 was filed with the patent office on 2002-06-20 for waste heat boiler for cooling hot syngas.
Invention is credited to Brucher, Peter.
Application Number | 20020073937 09/992748 |
Document ID | / |
Family ID | 7667123 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020073937 |
Kind Code |
A1 |
Brucher, Peter |
June 20, 2002 |
Waste heat boiler for cooling hot syngas
Abstract
A waste heat boiler for cooling hot syngas in heat exchange with
water under boiling pressure, consists of an outer pressure shell
(1) having a water space (2) filled with boiling water up to a
predetermined fluid level (4) and a steam space (3) above it. In
the water space (2), heat exchanger tubes (5) are arranged, through
which the syngas to be cooled flows. Downstream from the heat
exchanger tubes (5) is a superheater for superheating the saturated
steam generated by the boiling water. This superheater is
positioned at least partially in the steam space (3) above the
fluid level (4) and has straight tubes (7), through which the
syngas coming from the heat exchanger tubes (5) flows and around
which the steam exiting from the water space (2) circulates.
Inventors: |
Brucher, Peter;
(Oranienburg, DE) |
Correspondence
Address: |
Thomas S. Baker, Jr.
1371 West 3rd Avenue
Columbus
OH
43212
US
|
Family ID: |
7667123 |
Appl. No.: |
09/992748 |
Filed: |
November 16, 2001 |
Current U.S.
Class: |
122/406.1 |
Current CPC
Class: |
F22B 1/1838 20130101;
F22B 1/1884 20130101 |
Class at
Publication: |
122/406.1 |
International
Class: |
F22D 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2000 |
DE |
100 62 320.4 |
Claims
1. Waste heat boiler for cooling hot syngas in heat exchange with
water under boiling pressure, consisting of an outer pressure shell
(1) having a water space (2) filled with boiling water up to a
predetermined fluid level (4) and a steam space (3) above it, of
heat exchanger tubes (5), through which the syngas to be cooled
flows, arranged in the water space (2), and of a superheater for
superheating the saturated steam generated by the boiling water,
installed downstream from the heat exchanger tubes (5) and arranged
within the pressure shell (1), characterized in that the
superheater is positioned at least partially in the steam space (3)
above the fluid level (4), and that the superheater is provided
with straight tubes (7), through which the syngas coming from the
heat exchanger tubes (5) flows and around which the steam exiting
from the water space (2) circulates.
2. Waste heat boiler according to claim 1, characterized in that
the tubes (7) of the superheater are tightly inserted into a lower
tube sheet (8) and an upper tube sheet (9) and are surrounded by a
conductive shell (11), that the lower tube sheet (8) delimits at
the top a gas inlet chamber (10), into which the heat exchanger
tubes extend, and that the lower tube sheet (8) is located,
together with the gas inlet chamber (10), in the water space (2)
below the fluid level (4).
3. Waste heat boiler according to claim 1 or 2, characterized in
that the upper part of the superheater projects from the pressure
shell (1) and that the conductive shell (11) is tightly connected
to the pressure shell (1) at the penetration point of the
superheater
4. Waste heat boiler according to one of claims 1 through 3,
characterized in that the conductive shell (11) extends almost to
the lower tube sheet (8), that the lower tube sheet (8) is
connected to a collar (18), which surrounds the conductive shell
(11) over a partial length of the superheater, forming an annulus
(19) at a radial distance, and that the collar (18) extends into
the steam space (3).
5. Waste heat boiler according to one of claims 1 through 4,
characterized in that a droplet separator (6) extends across the
steam space (3) between the collar (18) and the pressure shell
(1).
6. Waste heat boiler according to one of claims 1 through 4,
characterized in that the lower tube sheet (8) is penetrated,
between the rows of tubes (7), by cross holes (17) open toward the
water space (2).
Description
[0001] The invention relates to a waste heat boiler for cooling hot
synthesis gas (syngas) according to the characterizing portion of
claim 1.
[0002] Hot syngases such as those generated in oil or residue
gasification plants, are cooled in a syngas waste heat boiler
downstream from the gasification rector. The thermal energy of the
syngas is recovered, producing high-pressure saturated steam. In
order to serve a subsequent useful purpose, this saturated steam
usually has to be superheated.
[0003] Syngas waste heat boilers for generating high-pressure
saturated steam may consist of spiral-coiled tubes, for instance,
or a bundle of straight or U-shaped tubes that form the
heat-exchange surface. The hot snygas flows through these
spiral-coiled tubes or tube bundles and releases its heat to the
water, which is under boiling pressure and surrounds the
spiral-coiled tubes or tube bundles inside a pressure shell.
[0004] The saturated steam is superheated in a separate superheater
downstream from the waste heat boiler. Also known are steam
superheaters integrated into syngas waste heat boilers, which
superheaters consist of spiral-coiled tubes installed downstream
from the waste heat boiler coiled tubes, and in which the syngas
flows through the coiled tubes in the same way it does in the waste
heat boiler. As a rule, the superheater coiled tubes have a smaller
tube diameter than the waste heat boiler coiled tubes. The
saturated steam is conducted around the superheater coiled tubes,
being superheated in the process. This design has the following
serious disadvantages: It is inherently expensive and complex; it
can only be inspected and repaired with considerable expenditures.
The snygas flowing through the superheater coiled tube can cause
deposits to form inside the coiled tube that lead to clogging,
making the superheater ineffective. Due to the relatively small
tube diameter, these occlusions are almost impossible to remove or
only with great difficulty.
[0005] Furthermore, coiled-tube steam superheaters, integrated into
syngas waste heat boilers, are known (Chem.-Ing.-Techn.56, 1984,
Issue 5, pp. 356-360), in which the syngas is conducted around the
coiled tubes, and the saturated steam to be superheated, through
the coiled tubes. This integrated steam superheater is also
expensive and complex and can only be inspected and repaired with
considerable effort and expenditures. In addition, at least in the
case of gasification of liquid feedstock, the flow channels between
the coiled tubes become clogged by sediments from the syngas. These
sediments cannot be removed and, after a certain period of time,
render the superheater ineffective.
[0006] The goal of the invention is to integrate the superheater
into the waste heat boiler in such a way as to create a simple and
cost-effective design, where the superheater is relatively easy to
inspect, to clean and to repair.
[0007] According to the invention, this goal is achieved in the
case of a generic waste heat boiler by the characterizing portion
of claim 1. Advantageous embodiments of the invention are the
subject of the dependent claims.
[0008] The invention and its advantages are explained below, based
on an embodiment shown in the drawing. The drawing is a schematic
cross-section of the upper part of a waste heat boiler for cooling
syngas.
[0009] The waste heat boiler for cooling syngas is a heat exchanger
of vertical design. It is made up of a pressure shell 1 enclosing a
water space 2 and a steam space 3 above it. Water space 2 is filled
with water under high boiling pressure up to fluid level 4. At the
lower part (not shown) of pressure shell 1, there is a connection
piece for admitting the water that is used as the heat exchange
medium.
[0010] In water space 2, heat exchanger pipes 5 are arranged
through which the syngas to be cooled flows. The heat exchanger
pipes 5 are designed as single or multipass spiral-shaped coiled
tubes.
[0011] During the heat exchange with the hot syngas, the water
surrounding heat exchanger tubes 5 partially evaporates and enters
steam space 3 at fluid level 4 in the form of saturated steam.
Above fluid level 4, there is a droplet separator 6 inside steam
space 3 for drying the saturated steam.
[0012] Downstream from heat exchanger tubes 5, which serve as an
evaporator, there is a superheater that cools the syngas further
while superheating the dried saturated steam. The superheater lies,
at least partially, within pressure shell 1 and is thus integrated
into the waste heat boiler. The superheater contains a
vertically-aligned bundle of straight tubes 7, arranged next to one
another in several rows and tightly inserted into a lower tube
sheet 8 and an upper tube sheet 9. Lower tube sheet 8 forms the
upper part of a hood-shaped gas inlet chamber 10, into which heat
exchanger tubes 5 extend.
[0013] The bundle of tubes 7 of the superheater is enclosed by a
conductive shell 11, which extends almost to lower tube sheet 8,
forming a passage between the lower edge of conductive shell 11 and
lower tube sheet 8. The superheater projects from pressure shell 1.
At the point of exit of the superheater, conductive shell 11 is
tightly connected to pressure shell 1. Outside of pressure shell 1,
an outlet pipe connection 12 is attached to conductive shell
11.
[0014] Above upper tube sheet 9, there is a hood-shaped gas outlet
chamber 13. Gas outlet chamber 13 and conductive shell 11 are each
equipped with a ring flange 14, 15. Upper tube sheet 9 is clamped
between these two ring flanges 14, 15.
[0015] Inside conductive shell 11, baffle plates 16, serving as
baffles for the medium flowing around tubes 7, are arranged offset
against each other and transverse to tubes 7.
[0016] The superheater is arranged inside pressure shell 1 such
that gas inlet chamber 10 together with lower tube sheet 8 is
located in water space 2 below fluid level 4. Therefore, gas inlet
chamber 10 is well cooled from the water side, preventing
overheating of materials.
[0017] Between the rows of tubes 7, cross holes 17, which are open
at both ends toward water space 2, pass through lower tube sheet 8.
Cross holes 17 therefore are filled with water, which cools lower
tube sheet 8.
[0018] A collar 18 is tightly connected to the outer edge of lower
tube sheet 8. This collar 18 surrounds the lower portion of
conductive shell 11 and forms annulus 19. The upper edge of collar
18 extends upward into steam space 3, beyond fluid level 4. Between
collar 18 and pressure shell 1, droplet separator 6 extends across
steam space 3.
[0019] The waste heat boiler described here works as follows. The
hot syngas to be cooled, such as from a gasification reactor, is
fed to the coils of heat exchanger tubes 5, passes through these
heat exchanger tubes 5 and enters gas inlet chamber 10. Gas inlet
chamber 10 distributes the syngas to tubes 7 of the superheater.
After passing through tubes 7 of the superheater, the syngas enters
gas outlet chamber 10[sic], from where it is carried off.
[0020] Pressure shell 1 of the waste heat boiler is filled with as
much water, under high pressure, as necessary to maintain fluid
level 4 at a predetermined height. The water present in water space
2 and surrounding heat exchanger tubes 5, partially evaporates
during heat exchange with the hot syngas and enters in the form of
saturated steam, into steam space 3 at fluid level 4. In passing
through droplet separator 6, the wet saturated steam is dried. From
there, the dried saturated steam flows downward into annulus 19
between collar 18 and conductive shell 11, and enters the interior
space enclosed by conductive shell 11 via the passage between the
lower edge of conductive shell 11 and lower tube sheet 8. At this
point, the superheating of the saturated steam begins: The dried
saturated steam is conducted along tubes 7 of the superheater to
outlet pipe connection 12, with frequent deflection by baffle
plates 16, thereby absorbing the thermal energy of the syngas
flowing through tubes 7. The superheated steam is carried off
through outlet pipe connection 12.
[0021] Collar 18, which is tightly connected to the outer edge of
tube sheet 8, prevents the flooding of the superheater with boiling
water.
[0022] The fact that the entire lower portion of the superheater,
consisting of collar 18, lower tube sheet 8 and gas inlet chamber
10, as well as heat exchanger tubes 5, are submerged in the boiling
water in water space 2, makes for a very effective and cooling of
these parts that are in contact with the hot syngas.
[0023] This type of waste heat boiler with integrated superheater,
as described here, is conceptually simple and can be built
cost-effectively. The entire superheater tube bundle can be removed
from the waste heat boiler in one piece, is easy to inspect, to
clean and to repair. It is easy to mechanically rid the interior of
the superheater's straight tubes 7 of deposits, during which
operation the superheater can remain installed in the syngas waste
heat boiler. Only gas outlet chamber 13 must be removed to make
superheater tubes 7 accessible from the top.
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