U.S. patent application number 17/286418 was filed with the patent office on 2022-06-02 for method for operating a chemical plant.
The applicant listed for this patent is Wolff Balthasar, Peter Koss. Invention is credited to Wolff Balthasar, Peter Koss.
Application Number | 20220170389 17/286418 |
Document ID | / |
Family ID | |
Filed Date | 2022-06-02 |
United States Patent
Application |
20220170389 |
Kind Code |
A2 |
Balthasar; Wolff ; et
al. |
June 2, 2022 |
METHOD FOR OPERATING A CHEMICAL PLANT
Abstract
A chemical plant and operating method therefor; the chemical
plant comprises a steam turbine having a shaft, a first pressure
turbine stage and a second pressure turbine stage, each being
arranged on the shaft and being connected in series in terms of the
steam process; steam for driving the steam turbine is obtained from
a reactor plant, said reactor plant producing a hydrogen-containing
substance from a carbon-containing energy-carrier stream; the steam
is heated in an overheating step before being supplied to the
second pressure turbine stage; the steam turbine has a third
pressure turbine stage which is arranged on the shaft and which is
connected between the first pressure turbine stage and the second
pressure turbine stage in terms of the steam process; and the steam
passes through the overheating step after exiting the third
pressure turbine stage.
Inventors: |
Balthasar; Wolff; (Ratingen,
DE) ; Koss; Peter; (Bad Homburg vor der Hohe,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Balthasar; Wolff
Koss; Peter |
Ratingen
Bad Homburg vor der Hohe |
|
DE
DE |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20210301685 A1 |
September 30, 2021 |
|
|
Appl. No.: |
17/286418 |
Filed: |
October 17, 2019 |
PCT Filed: |
October 17, 2019 |
PCT NO: |
PCT/EP2019/078232 PCKC 00 |
371 Date: |
April 16, 2021 |
International
Class: |
F01K 23/06 20060101
F01K023/06; F01K 11/02 20060101 F01K011/02; F01K 3/18 20060101
F01K003/18; F01K 7/22 20060101 F01K007/22; C01B 3/02 20060101
C01B003/02; C01C 1/04 20060101 C01C001/04; C07C 29/152 20060101
C07C029/152 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2018 |
EP |
18202126.1 |
Claims
1. A method comprising: operating a chemical plant, wherein the
chemical plant comprises a steam turbine defining a shaft and first
pressure turbine stage, a second pressure turbine stage, and a
third pressure turbine stage connected to the shaft in series,
wherein steam passing through the steam turbine successively passes
through the first pressure turbine stage, the third pressure
turbine stage and then the second pressure turbine stage; wherein
the operating step includes obtaining steam from a reactor plant
configured to produce a hydrogen-containing substance from a
carbon-containing energy-carrier flow; driving the steam turbine
with the steam; overheating the steam after it exits the third
pressure turbine stage; and supplying said overheated steam to the
second pressure turbine stage.
2. The method according to claim 2, further including the reactor
plant producing methanol and/or ammonia.
3. The method according to claim 16, further including generating
synthesis gas in a synthesis gas section of the reactor plant.
4. The method according to claim 3, wherein the step of generating
the synthesis gas includes supplying the carbon-containing
energy-carrier flow to the synthesis gas section; supplying an
oxygen-containing flow to the synthesis gas section; and generating
the synthesis gas through a catalytic partial oxidation using the
oxygen-containing flow.
5. The method according to claim 4, further including converting
the synthesis gas into the hydrogen-containing substance; and
generating heat from a reaction during the converting step; wherein
the overheating step includes heating the steam with the heat from
said reaction.
6. The method according to claim 5, wherein the reactor plant
includes a converting section defining a reactor including a
catalyst configured to at least partially convert the synthesis gas
into the hydrogen-containing substance.
7. The method according to claim 2, wherein the driving step
includes supplying a first saturated and overheated steam flow to
the first pressure turbine stage.
8. The method according to claim 7, wherein the reactor plant
includes a fired heating device configured to overheat steam, and
wherein the step of supplying the first steam flow includes
obtaining steam from the reactor plant in a saturated condition;
and overheating said steam in a saturated condition using the fired
heating device.
9. The method according to claim 8, further including obtaining a
second steam flow from the reactor plant; and overheating the
second steam flow using the fired heating device; wherein the
driving step includes supplying the second steam flow to the third
pressure turbine stage.
10. The method according to claim 1, wherein the steam turbine
defines a condensing turbine, so that condensation forms in exhaust
steam therefrom.
11. The method according to claim 1, wherein the chemical plant
further comprises a generator configured to produce an electrical
turbine current, and the method further includes driving the
generator with the shaft.
12. The method according to claim 11, further including driving a
pump assembly with the turbine current, wherein the pump assembly
includes a boiler water pump configured to provide water for a
boiler of the reactor plant.
13. The method according to claim 11, further including driving a
compressor assembly with the turbine current, wherein the
compressor assembly includes a synthesis gas compressor configured
to increase pressure in the reactor plant.
14. The method according to claim 11, wherein the chemical plant
comprises a frequency converter configured to convert frequency of
the turbine current.
15. A chemical plant comprising: a steam turbine defining a shaft
and a first pressure turbine stage, a second pressure turbine
stage, and a third pressure turbine stage connected to the shaft in
series, wherein steam passing through the steam turbine
successively passes through the first pressure turbine stage, the
third pressure turbine stage and then the second pressure turbine
stage; a reactor plant configured to produce a hydrogen-containing
substance from a carbon-containing energy-carrier flow, wherein the
reactor plant is further configured to provide steam to drive the
steam turbine; and a heating assembly configured to heat the steam
subsequent to it exiting the third pressure turbine stage and prior
to it being supplied to the second pressure turbine stage.
16. The method according to claim 1, wherein the chemical plant
includes the reactor plant.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. national stage application of
international application no. PCT/EP2019/078232 filed Oct. 17,
2019, entitled "Method for Operating a Chemical Plant," claiming
priority under 35 U.S.C. .sctn. 119(a)-(d) to European application
no. EP18202126.1 filed Oct. 23, 2018, which are hereby expressly
incorporated by reference as part of the present disclosure.
FIELD OF THE INVENTION
[0002] The present disclosure relates to a method for operating a
chemical plant as well as to a chemical plant.
BACKGROUND
[0003] Power generation by means of steam turbines is well-known
from the prior art. As a rule, such a steam turbine has several
pressure turbine stages disposed on a common shaft, which in turn
drives a generator for power generation. The supplied and highly
pressurized steam now successively passes through the individual
pressure turbine stages for driving the shaft, the steam losing
pressure by passing through the individual stages.
[0004] Overheating the steam not only before it is supplied for the
first time to the steam turbine--and thus to the first pressure
turbine stage--but also between the first pressure turbine stage
and the one directly downstream thereof in order to improve in this
manner the degree of efficiency of the steam turbine is also known
from the prior art. Such an overheating process makes it possible
to achieve a condensation of the exhaust steam in the final
pressure turbine stage, by lowering the pressure almost to a
vacuum. Condensing turbine of this type achieve a very high degree
of efficiency, wherein up to 40% of the total output may result
from this final pressure turbine stage.
[0005] However, steam turbines are not only used in power plants
for power generation, where a single turbine generally generates a
very high output, but are also employed, in smaller sizes, in
plants of the chemical industry, which regularly produce process
steam that may be used in a steam turbine. In such chemical plants,
the steam turbine frequently drive mechanical devices directly,
without an intermediate power generation step.
[0006] There are a variety of chemical plants, particularly
synthesis plants, e.g. for the production of methanol or ammonia,
in which a hydrogen-containing substance, such as hydrogen or
synthesis gas, is produced from a carbon-containing energy-carrier
flow, such as natural gas. In turn, the ultimately desired chemical
substance can then be produced from such a synthesis gas, if
necessary. In particular, smaller steam turbines, with which pumps
and compressors of the chemical plant may then be driven, are also
used in these chemical plants. The large number of required pumps
and compressors results in the necessity of providing just as large
a number of steam turbines. Because the dimensions of these steam
turbines, owing to the smaller output required in each case, are
smaller compared with those of the power generation steam turbines
in power plants, they also have a smaller degree of efficiency in
comparison.
[0007] Catalytic partial oxidation, which is also referred to as
autothermic reforming, is a preferred manner of producing the
synthesis gas in chemical plants. However, in the catalytic partial
oxidation, the exiting synthesis gas, due to the supply of oxygen
to the process, has such a large carbon monoxide partial pressure
that a use of the synthesis gas for overheating the steam for the
supply to the steam turbine appears not to be feasible in light of
the current state of material sciences. For this high carbon
monoxide partial pressure would result in a rapid destruction of
the overheating device by metal dusting.
[0008] The consequence of this lack of an option for overheating by
means of the synthesis gas, which is sufficiently hot as such, is
that all the heat for overheating the steam has to be provided by a
heating device fired with the natural gas--which is also referred
to as a fired heater. In that case, the natural gas used for firing
cannot be used for the synthesis, which reduces the yield of the
plant.
SUMMARY
[0009] An object of the inventors was to develop a steam turbine in
a chemical plant and a method for operating such a chemical plant
in such a way that the steam turbine is able to provide its output
for overheating the steam with a smaller consumption of natural gas
or other energy carrier.
[0010] The inventors realized that, in a steam turbine in the
context of a chemical plant, overheating the steam again between
the pressure turbine stages--which process of repeated overheating
is also referred to as reheating--can not only be carried out in
the area of the high pressures, i.e. between the first two pressure
turbine stages, but also in the area of lower pressures between the
respectively subsequent pressure turbine stages. Though overheating
in the case of such a procedure results in a slightly lower degree
of efficiency than in the case of overheating at higher steam
pressures, internal process heat of the chemical plant may then be
used for overheating, so that the fired heating device is not
required at least for this overheating process.
[0011] As a result, such a reheating offers the possibility of
completely replacing in an economical manner the plurality of
smaller steam turbines of the chemical plant with a single,
correspondingly larger steam turbine for power generation, wherein
the previously purely mechanically driven pumps and compressors of
the chemical plant may then be driven electrically. The losses
arising due to the intermediate conversion into electrical energy
are then at least compensated by the improved degree of efficiency
of the steam turbine.
[0012] This summary is not exhaustive of the scope of the present
aspects and embodiments. Thus, while certain aspects and
embodiments have been presented and/or outlined in this summary, it
should be understood that the present aspects and embodiments are
not limited to the aspects and embodiments in this summary. Indeed,
other aspects and embodiments, which may be similar to and/or
different from, the aspects and embodiments presented in this
summary, will be apparent from the description, illustrations,
and/or claims, which follow.
[0013] It should also be understood that any aspects and
embodiments that are described in this summary and do not appear in
the claims that follow are preserved for later presentation in this
application or in one or more continuation patent applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other details, features, aims and advantages will become
apparent from the following description and with reference to the
FIGURE, which are understood not to be limiting.
[0015] FIG. 1 shows a schematic illustration of an embodiment of a
chemical plant.
DETAILED DESCRIPTION
[0016] In at least one aspect, a method serves for operating a
chemical plant illustrated in FIG. 1. The chemical plant has a
steam turbine 1 with a shaft 2 and with a first pressure turbine
stage 3 and a second pressure turbine stage 4. The first pressure
turbine stage 3 and the second pressure turbine stage 4 are each
disposed on the shaft 2 and connected in series in terms of the
steam process. The connection in series of the first pressure
turbine stage 3 and the second pressure turbine stage 4 in terms of
the steam process means that turbine steam flowing through the
steam turbine 1 for driving the shaft 2 first flows through the
first pressure turbine stage 3 and only then through the second
pressure turbine stage 4. In between, this turbine steam may in
principle pass through any number of further pressure turbine
stages of the steam turbine 1 or be supplied to another process. In
at least some embodiments, the steam turbine 1 has an electrical
maximum output of at least 30 MW, and in some embodiments an
electrical maximum output of between 50 MW and 200 MW.
[0017] Steam 5 for driving the steam turbine 1 is obtained from a
reactor plant 6, which reactor plant 6 produces a
hydrogen-containing substance 7 from a carbon-containing
energy-carrier flow 8, and wherein the steam 5 is heated in an
overheating step prior to being supplied to the second pressure
turbine stage 4. In at least some embodiments, the chemical plant
includes the reactor plant 6. In this case, the overheating step
may basically have an arbitrary duration and cause the steam 5 to
be heated to a basically arbitrary temperature. In at least some
embodiments, the steam 5 is heated to a temperature above the
saturation temperature. The latter is the saturation temperature at
the pressure that the steam 5 has in the overheating step. Heating
may also take place in a basically arbitrary manner and fed by a
basically arbitrary energy source.
[0018] The steam 5 is already heated when it is being obtained from
the reactor plant 6, and thus prior to being supplied to the steam
turbine 1--e.g., prior to being supplied to the first pressure
turbine stage 3. In at least some embodiments, the steam 5 is
heated to a temperature above the saturation temperature of the
steam 5 prior to being supplied to the steam turbine 1--e.g., prior
to being supplied to the first pressure turbine stage 3. Therefore,
the heating prior to the supply to the second pressure turbine
stage 4, at which point in time the steam 5 has already been
supplied to the steam turbine 1, is a re-heating.
[0019] In the illustrated embodiment, the steam turbine 1 has a
third pressure turbine stage 9 disposed on the shaft 2, which third
pressure turbine stage 9 is connected between the first pressure
turbine stage 3 and the second pressure turbine stage 4 in terms of
the steam process. This means that turbine steam exiting the first
pressure turbine stage 3 first flows through the third pressure
turbine stage 9 before flowing through the second pressure turbine
stage 4. Again, the turbine steam may in principle pass through any
number of further pressure turbine stages or be supplied to another
process, in each case between the first pressure turbine stage 3
and the third pressure turbine stage 9, and between the third
pressure turbine stage 9 and the second pressure turbine stage
4.
[0020] The steam 5 passes through the overheating step after
exiting the third pressure turbine stage 9. Thus, the steam 5 is
heated in the overheating step prior to being supplied to the
second pressure turbine stage 4.
[0021] The chemical plant includes the steam turbine 1, which in
turn comprises the shaft 2, the first pressure turbine stage 3 and
the second pressure turbine stage 4, wherein the first pressure
turbine stage 3 and the second pressure turbine stage 4 are each
disposed on the shaft 2 and connected in series in terms of the
steam process.
[0022] The chemical plant further includes the reactor plant 6 for
producing the hydrogen-containing substance 7 from the
carbon-containing energy-carrier flow 8, wherein steam 5 for
driving the steam turbine 1 is obtained from the reactor plant 6.
The chemical plant also includes a heating assembly 6a for heating
the steam 5 prior to it being supplied to the second pressure
turbine stage 4. In principle, this heating assembly 6a may be any
device or group of devices of the chemical plant, which may
optionally also be included in the reactor plant 6.
[0023] In the chemical plant, the steam turbine 1 has a third
pressure turbine stage 9, which is disposed on the shaft 2 and
which is connected between the first pressure turbine stage 3 and
the second pressure turbine stage 4 in terms of the steam process.
In the chemical plant, the heating assembly 6a further heats the
steam 5 subsequent to it exiting the third pressure turbine stage
9. Thus, a heating process takes place between the third pressure
turbine stage 9 and the second pressure turbine stage 4.
[0024] In at least some embodiments, the steam 5 has a temperature
of at least 450.degree. C. prior to being supplied to the steam
turbine 1--e.g., prior to being supplied to the first pressure
turbine stage 3. Thus, the steam 5 is overheated. In at least some
embodiments, the steam 5 may have a temperature of between
450.degree. C. and 600.degree. C. prior to being supplied to the
steam turbine 1--e.g., prior to being supplied to the first
pressure turbine stage 3. Accordingly, in at least some embodiments
the steam 5 is heated in the overheating step to at least the
temperature of the steam 5 prior to being supplied to the steam
turbine 1--e.g., prior to being supplied to the first pressure
turbine stage 3. In other words, the steam 5 is heated in the
overheating step to a temperature of at least 450.degree. C., and
particularly to a temperature of between 450.degree. C. and
650.degree. C. With respect to the chemical plant, in at least some
embodiments, the heating assembly 6a heats the steam 5 to a
temperature of at least 450.degree. C., and in some such
embodiments to a temperature of between 450.degree. C. and
650.degree. C. Also, in at least some embodiments, the steam 5 has
a pressure of between 1 bar and 20 bars when it is supplied to the
second pressure turbine stage 4. In some such embodiments, the
steam 5 may have a pressure of between 2 bars and 8 bars when it is
supplied to the second pressure turbine stage 4.
[0025] Since the pressure of the steam 5 drops when it successively
flows through the pressure turbine stages 3, 4, 9, the first
pressure turbine stage 3 may also be referred to as a high-pressure
turbine stage, the third pressure turbine stage 9 connected
downstream of the first pressure turbine stage 3 may be referred to
as a medium-pressure turbine stage, and the second pressure turbine
stage 4 may be referred to as a low-pressure turbine stage. Thus,
the steam 5 may, for instance, have a pressure of between 80 bars
and 300 bars, e.g., between 100 bars and 200 bars, prior to flowing
through the first pressure turbine stage 3. It is also the case in
some embodiments that the steam 5, after flowing through the first
pressure turbine stage 3 and prior to flowing through the third
pressure turbine stage 9, has a pressure of between 30 bars and 100
bars, and finally a pressure of between 0.01 and 0.1 bars after
flowing through the second pressure turbine stage 4. The steam
overheated, upstream of the first pressure turbine stage 3 and
upstream of the second pressure turbine stage 4, to a temperature
of in this case more than 500.degree. C. still has a temperature
of, for example, between 15.degree. C. and 40.degree. C., or
between 20.degree. C. and 30.degree. C., when exiting the second
pressure turbine stage 4. It is also the case in some embodiments
that the steam has a temperature of at least 280.degree. C. or of
substantially 280.degree. C. when exiting the first pressure
turbine stage 3.
[0026] In principle, the hydrogen-containing substance 7 may be any
such substance. For example, the hydrogen-containing substance 7
may be hydrogen. The hydrogen-containing substance 7 may also be
synthesis gas including carbon oxides and hydrogen. The
hydrogen-containing substance 7 may also be a hydrogen-containing
compound. In at least some embodiments, the reactor plant 6
produces methanol and, alternatively or additionally, ammonia.
Accordingly, the hydrogen-containing substance 7 may be methanol or
ammonia.
[0027] The reactor plant 6 may be divided into several sections
with different functions in each case. Here, in at least some
embodiments, synthesis gas 11, e.g., including hydrogen and carbon
oxides, is obtained in a synthesis gas section 10 of the reactor
plant 6. In at least some embodiments, the obtained synthesis gas
11 is supplied to a converting section 12 of the reactor plant 6
downstream of the synthesis gas section 10, in which converting
section 12 the obtained synthesis gas 11 is converted into the
hydrogen-containing substance 7. The synthesis gas 11 may include
hydrogen and carbon oxides, or substantially consists thereof. In
addition, the synthesis gas 11 may also contain nitrogen and
smaller contents of noble gases, or contain hydrogen, carbon
oxides, nitrogen and noble gases. In at least some embodiments, the
synthesis gas 11 is converted in the converting section 12 into
methanol and/or ammonia. For this conversion, other starting
materials may also be supplied to the converting section 12, e.g.
nitrogen for the production of ammonia. This may take place
particularly if the synthesis gas 11 does not contain a sufficient
amount of nitrogen.
[0028] In at least some embodiments, the carbon-containing
energy-carrier flow 8 is supplied to the synthesis gas section 10
for obtaining the synthesis gas 11, that an oxygen-containing flow
13 is supplied to the synthesis gas section 10, and that the
synthesis gas 11 is obtained in the synthesis gas section 10
through a catalytic partial oxidation--which may also be referred
to as autothermic reforming--by means of the oxygen-containing flow
13. As is shown in FIG. 1, the oxygen-containing flow 13 may
substantially consist of oxygen and be obtained from an air
separation device 14 of the reactor plant 6.
[0029] In at least some embodiments, the steam 5 is heated in the
overheating step by means of heat from a reaction during the
conversion of the obtained synthesis gas 11 into the
hydrogen-containing substance 7, e.g., into methanol and/or
ammonia. For example, the reactions for forming methanol from
synthesis gas 11 are exothermic, as is the reaction for obtaining
ammonia from hydrogen and nitrogen, whereby the heat for heating
the steam can thus be obtained. FIG. 1 shows that the steam 5 is
guided from the steam turbine 1 to the converting section 12 for
heating--e.g., to a reactor 15 of the converting section 12--and
then back to the steam turbine 1. Accordingly, the reactor 15 in
this case forms the heating assembly 6a. According to the
illustration of FIG. 1, a product treatment unit 15a of the
converting section, which obtains the hydrogen-containing substance
7 from the substance flow 16 exiting the reactor 15, is connected
downstream of the reactor 15. In at least some embodiments, the
product treatment unit 15a may be configured for obtaining the
hydrogen-containing flow 7 from the substance flow 16 by purifying
the substance flow 16.
[0030] In at least some embodiments, the converting section 12 has
the reactor 15 with a catalyst for at least partially converting
the synthesis gas 11 into the hydrogen-containing substance 7. The
converting section 12 may also have a heat exchanger--not shown in
FIG. 1 herein--for cooling the substance flow 16 from the reactor
15. The substance flow 16 can include a raw-product flow with the
hydrogen-containing substance 7 and possibly non-reacted synthesis
gas. In at least some embodiments, the steam 5 is heated in the
overheating step by heat from the reactor 15 or the heat
exchanger.
[0031] In at least some embodiments, the steam 5 supplied to the
first pressure turbine stage 3 is already overheated and saturated.
Therefore, a first saturated and overheated steam flow 17 may be
supplied to the first pressure turbine stage 3 for driving the
steam turbine 1. In principle, this first steam flow 17 may have
any relationship with the steam 5. For example, the first steam
flow 17 may be separate from the steam 5. However, the steam flow
17 may also include the steam 5 or consist thereof.
[0032] The overheating of the steam 5 for the first pressure
turbine stage 3 may have a higher temperature than the downstream
overheating between the third pressure turbine stage 9 and the
second pressure turbine stage 4. Therefore, the exemplary
embodiment shown here in FIG. 1 provides that the reactor plant 6
has a fired heating device 18, which overheats the steam 5, which
is obtained in a saturated condition from the reactor plant 6, for
obtaining the first steam flow 17. Apart from this overheating of
the steam 5, the fired heating device 18 may also have further
functions.
[0033] The heating device 18 may be fed by the carbon-containing
energy-carrier flow 8. In at least some embodiments, the steam 5 is
obtained in a saturated condition from the synthesis gas section
10. The steam 5 may be obtained from a process of draining water
from the synthesis gas section 10, for example.
[0034] On the one hand, the steam turbine 1 may be operated such
that all its pressure turbine stages 3, 4, 9 are operated
substantially only by the steam 5 that is already being supplied to
the first pressure turbine stage 3. However, it is also
possible--as is shown in FIG. 1--to supply the pressure turbine 1
with additional steam downstream of the first pressure turbine
stage 3. Accordingly, in at least some embodiments, a second, in
particular saturated, steam flow 19 is obtained from the reactor
plant 6, e.g., from the converting section 12, which is overheated
by the heating device 18 and which is supplied to the third
pressure turbine stage 9 for driving the steam turbine 1. As is
shown in FIG. 1, that steam 5 exiting the first pressure turbine
stage 3 is supplied to the third pressure turbine stage 9 for
driving the steam turbine 1. Accordingly, the second steam flow 19
may be merged with the first steam flow 17 after the first steam
flow 17 has exited the first pressure turbine stage 3. Pressures
lower than those in the synthesis section 10 may occur in the
converting section 12. Therefore, the second steam flow 19 from the
converting section 12, which has a lower pressure compared with the
first steam flow 17, may be merged with the first steam flow 17 if
the first steam flow 17 has already lost some pressure by flowing
through the first pressure turbine stage 3.
[0035] Also, a process steam flow, which may be a partial flow of
the steam 5, may also be extracted after exiting from the first
pressure turbine stage 3 or from the third pressure turbine stage
9. In at least some embodiments, the process steam flow is
extracted prior to the supply to the third pressure turbine stage 9
of prior to the supply to the second pressure turbine stage 4. Such
an extracted process steam flow is in at least some embodiments,
supplied to the reactor plant 6. In at least some embodiments, the
extracted process steam flow may be supplied to the reactor plant
6, and in at least some embodiments, to the synthesis gas section
10 or the converting section 12, and in the illustrated embodiment
to the product treatment unit 15a. For example, the product
treatment unit 15a may comprise distillation columns for product
treatment. The latter regularly require greater steam quantities,
which can accordingly be provided by the extracted process steam
flow. The extracted process steam flow may be supplied as a heating
medium and/or as a reaction medium in a chemical process.
[0036] Then, the process steam flow may be mixed with a process
flow of the reactor plant 6. Alternatively, the process steam flow
may be used as a heating medium in a reboiler of the chemical
plant. In at least some embodiments, the process steam flow
condensates in the process and is supplied as a condensate to the
condensed water from the condenser 25--which is described in more
detail below. As a consequence, the extracted process steam flow
can no longer be returned to the steam turbine 1.
[0037] As is shown in FIG. 1, the steam turbine 1 may be a
condensing turbine, so that condensation arises in the exhaust
steam of, in particular, the second pressure turbine stage 4.
Accordingly, in at least some embodiments, the second pressure
turbine stage 4 relaxes the steam 5 supplied to it to form a wet
steam 20. This permits achieving a very high degree of efficiency
with the steam turbine 1.
[0038] Also in accordance with the illustration in FIG. 1, the
chemical plant comprises a generator 21 for producing an electrical
turbine current, which generator 21 is driven by the shaft 2. If,
as in the present case, a steam turbine 1, and in particular a
condensing turbine, is operated with several pressure turbine
stages 3, 4, 9, then enough electrical power can be provided with
it--and thus with a single steam turbine 1--in order to operate
all, or at least vital, electrical consumers of the reactor plant
6. Possibly, excess electrical power generated by the generator 21
may even be provided to other consumers outside the reactor plant
6. In that case, it is no longer necessary to use a plurality of
steam turbines with, in each case, lower power.
[0039] In principle, the turbine current may be used for an
arbitrary purpose. In at least some embodiments, however, that the
turbine current drives the air separation device 14 of the reactor
plant 6. Also, the turbine current may drive a compressor assembly
26 and/or a pump assembly 22 of the reactor plant 6.
[0040] For example, it may also be advantageous that the air
separation device 14 is powered electrically and that it can be
operated additionally or exclusively with power from a power grid.
The air separation device 14 may also produce, at least
temporarily, oxygen for the oxygen-containing flow 13 and a surplus
of oxygen beyond that. In other words, the air separation device 14
then produces more oxygen than is required by the chemical plant
and particularly the synthesis gas section 10. In at least some
embodiments, the oxygen surplus is then stored temporarily in a
suitable storage unit, particularly in a liquid form.
[0041] This makes it possible for power from the power grid to be
additionally consumed for the air separation device 14 specifically
at those times or times of day when the price of electricity is low
or even negative, while the reactor plant 6, and thus also the
chemical plant, can continue to be operated. In times of higher
electricity prices, the intermediately stored oxygen surplus can
then be used to reduce the oxygen separation power and thus the
power consumption of the air separation device 14. Thus, a power
surplus is produced in the generator 21 which can be released to
the power grid. A chemical plant equipped in this way can therefore
take on the task of a buffer, also referred to as a peak shaver,
which helps compensating the production and load fluctuations of a
power grid as they may occur due to the integration of the
regenerative power sources wind and photovoltaics. Comparatively
large energy quantities can be stored in the form of oxygen in the
manner described herein. This energy can then be returned in a
targeted manner to the power grid by reducing the load of the air
separation device 14.
[0042] With respect to the pump assembly 22, the pump assembly 22
may have a boiler water pump 23 for providing water for a boiler 24
of the reactor plant 6. This boiler 24 may be included in the
converting section 12. According to the illustration of FIG. 1, the
boiler water pump 23 may be supplied with water from the condenser
25 of the chemical plant, which condenser 25 is supplied with the
wet steam 20.
[0043] With regard to the compressor assembly 26 the compressor
assembly 26 may have a synthesis gas compressor for increasing the
pressure in the reactor plant 6. As shown in FIG. 1, the compressor
assembly 26, and also the synthesis gas compressor, may serve for
increasing the pressure of the synthesis gas 11, i.e. particularly
prior to being supplied to the reactor 15.
[0044] The compressors of a compressor assembly 26 and the pumps of
a pump assembly 22 may be driven by electric motors. If the power
from the electrical power supply grid is fed to the latter,
adjusting their rotation speed becomes difficult. For the rotation
speed of an electric motor first depends on the frequency of the
current, which in the power supply grid is fixed at 50 Hz, for
example. Providing a mechanical transmission for adjusting the
respective rotation speed is expensive and requires a design which
is both complex and laborious to maintain.
[0045] Therefore, in order to drive the compressor assembly 26 and
the pump assembly 22 effectively, the chemical plant may have a
frequency converter assembly 27 which, with a power electronic
system of the frequency converter assembly 27, converts the turbine
current, e.g., for driving the compressor assembly 26 and/or the
pump assembly 22. In at least some embodiments, the chemical plant
may have a frequency converter assembly 27 with an adjustable
output frequency. In this case, the frequency converter assembly 27
may also have a plurality of individual frequency converters, e.g.
at least one individual frequency converter is provided for each of
the compressor assembly 26, the pump assembly 22 and for the air
separation device 14. Thus, mechanical transmissions for these
devices become dispensable. It was found that, due to progress in
the field of frequency converters, this solution ultimately is
economically more advantageous compared with mechanical
transmissions, despite existing electrical losses and high
costs.
[0046] Providing the frequency converter assembly 27 further
permits the operation of the frequency converter assembly, and thus
also of the compressor assembly 26, the pump assembly 22 and/or the
air separation device 14, with power from the power supply grid
when starting up the reactor plant 6, i.e. when steam 5 from the
reactor plant 6 is not yet provided to a sufficient extent for
operating the steam turbine 1.
[0047] While the above describes certain embodiments, those skilled
in the art should understand that the foregoing description is not
intended to limit the spirit or scope of the present disclosure. It
should also be understood that the embodiments of the present
disclosure described herein are merely exemplary and that a person
skilled in the art may make any variations and modification without
departing from the spirit and scope of the disclosure. All such
variations and modifications, including those discussed above, are
intended to be included within the scope of the disclosure.
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