U.S. patent application number 15/277139 was filed with the patent office on 2017-04-27 for process and installation for controlling the quantity of solid particles emitted by a combustion turbine.
The applicant listed for this patent is GE Energy Products France SNC. Invention is credited to Maher ABOUJAIB, Denis MARTIN, Ezio PENA, Matthieu VIERLING.
Application Number | 20170115007 15/277139 |
Document ID | / |
Family ID | 54979750 |
Filed Date | 2017-04-27 |
United States Patent
Application |
20170115007 |
Kind Code |
A1 |
ABOUJAIB; Maher ; et
al. |
April 27, 2017 |
PROCESS AND INSTALLATION FOR CONTROLLING THE QUANTITY OF SOLID
PARTICLES EMITTED BY A COMBUSTION TURBINE
Abstract
The invention concerns a method of controlling the quantity of
solid particles emitted by a combustion turbine (1), during the
combustion of a liquid fuel, by injecting a combustion catalyst
suitable for reducing the quantity of solid particles generated
during combustion. This method comprises the following steps:
Measuring the quantity of particles (Qsuies) emitted during
combustion; Injecting the combustion catalyst into the combustion
turbine (1) when the quantity of particles measured is higher than
a maximum threshold value; and Stopping the injection of the
catalyst when the measured quantity of particles is lower than a
minimum target value.
Inventors: |
ABOUJAIB; Maher; (Belfrot,
FR) ; VIERLING; Matthieu; (Belfort, FR) ;
PENA; Ezio; (Belfort, FR) ; MARTIN; Denis;
(CRAVANCHE, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE Energy Products France SNC |
Belfort |
|
FR |
|
|
Family ID: |
54979750 |
Appl. No.: |
15/277139 |
Filed: |
September 27, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02C 3/30 20130101; F23R
3/40 20130101; F02C 9/00 20130101; F05D 2270/08 20130101 |
International
Class: |
F23R 3/40 20060101
F23R003/40 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2015 |
FR |
1559155 |
Claims
1. A method of controlling the quantity of solid particles emitted
by a combustion turbine (1), during the combustion of a liquid
fuel, by injecting a combustion catalyst suitable for reducing the
quantity of solid particles generated during combustion,
characterized in, that it comprises the following steps: Measuring
the quantity of particles (Qsuies) emitted during combustion;
Injecting the combustion catalyst into the combustion turbine when
the concentration of particles measured is higher than a maximum
threshold value; and Stopping the injection of the catalyst when
the measured quantity of particles is lower than a minimum target
value.
2. The method according to the claim 1, in which the temperature of
the flame of the combustion turbine is more than or equal to
1363K.
3. The method according to one of the claims 1 and 2, in which the
catalyst is injected into a feed line (8) of the said liquid fuel
system, upstream of the combustion system of the combustion
turbine.
4. The method according to one of the claims 1 and 2, in which the
catalyst is injected into the combustion chambers (3) of a
combustion system of the combustion turbine.
5. The method according to one of the claims 1 to 4, in which the
maximum threshold value is a particle concentration range between
45 mg/Nm.sup.3 and 55 mg/Nm.sup.3.
6. The method according to one of the claims 1 to 5, in which the
minimum target value is a particle concentration range between 20
mg/Nm.sup.3 and 30 mg/Nm.sup.3.
7. The method according to one of the claims 1 to 6, in which the
combustion catalyst includes at least an element selected from iron
(III) oxides, cerium (III) oxides, cerium (IV) oxides and their
mixtures.
8. The method according to one of the claims 1 to 7, in which the
concentration of particles emitted is measured continuously.
9. A system for controlling the quantity of solid particles emitted
by a combustion turbine (1), during the combustion of a solid fuel,
comprising combustion catalyst injection means (10) suitable for
reducing the quantity of particles generated during the combustion,
characterized in, that it comprises measurement means (12) for
measuring the quantity of emitted particles and a central control
unit (11) suitable for activating the measurement means so as to
inject the combustion catalyst into the combustion turbine (1) when
the measured quantity of particles is higher than a maximum
threshold value and to stop the injection of the catalyst when the
measured quantity of particles is lower than a minimum target
value.
10. The installation of turbine gas type, characterized in, that it
comprises a system of control according to claim 9.
Description
[0001] The present invention concerns combustion turbines or gas
turbines, and concerns specifically the controlling of
concentration of solid particles emitted by gas turbines during the
combustion of a liquid fuel.
[0002] A wide range of liquid fuels available for feeding the
combustion turbines. This mainly includes heavy fuel oils, crude
oils, heavy or light distilled oils, gas oils, kerosene, naphtha,
biodiesel, bioethanol, etc.
[0003] A heavy oil type fuel contains vanadium and other types of
contaminants, including sulfur, and consequently, its combustion
generates solid ash similar to solid particles.
[0004] Based on the performance of the combustion system in the
constitution of a combustion turbine, the liquid or gaseous fuels
may generate emissions of dust or ash, and generally, solid
particles, which are released to the atmosphere, through a
chimney.
[0005] Among the solid particles, soot corresponds to the organic
fraction of dust, and includes carbon, hydrogen and possibly,
oxygen and nitrogen, to a major extent.
[0006] The solid particles may also contain a mineral fraction,
generally consisting of alkali metals or heavy metals.
[0007] The regulations related to combustion turbines imposed
globally or locally across the countries set maximum limits for
emission of solid particles into the atmosphere.
[0008] For example, when a combustion turbine using a liquid fuel
is working at its rated speed, the maximum value of emission of
dust from a stationary combustion turbine to the atmosphere should
be 50 mg/Nm.sup.3.
[0009] In order to restrict the quantity of solid particles
emitted, a combustion catalyst is generally used.
[0010] There are different types of combustion catalysts that are
capable of reducing soot emissions in installations. The choice of
the combustion catalyst depends on the type of fuel, the type
installation used and the maximum concentration of solid particles
imposed by the regulations.
[0011] In the light of the foregoing, the present invention has the
objective of controlling the quantity of solid particles emitted by
a combustion turbine, regardless of the operating regimes of the
combustion turbine.
[0012] Thus, the invention has the primary objective of providing a
method of controlling the quantity of solid particles emitted by a
combustion turbine, during the combustion of a liquid fuel, by
injecting a combustion catalyst suitable for reducing the quantity
of solid particles generated during combustion.
[0013] This method comprises the following steps:
[0014] Measuring the quantity of particles emitted during
combustion;
[0015] Injecting the combustion catalyst into the combustion
turbine when the quantity of particles measured is higher than a
maximum threshold value;
[0016] Stopping the injection of the catalyst when the measured
quantity of particles is lower than a minimum threshold value.
[0017] These process steps allow to implement the cyclic phases,
keeping in view the hysteresis of injection of catalyst, thus
enabling a more precise control of the quantity of emitted
particles and/or optimizing the consumption of combustion
catalyst.
[0018] Advantageously, the temperature of the flame of the
combustion turbine is more than or equal to 1363 K (1090.degree.
C.).
[0019] For example, the catalyst is injected into a liquid fuel
system feed line upstream of the combustion system of the
combustion turbine.
[0020] Alternatively, the catalyst can be injected directly into
the combustion turbine unit.
[0021] Advantageously, the maximum threshold value of concentration
of particles is between 45 mg/Nm.sup.3 and 55 mg/Nm.sup.3. This
range of concentration relates to the maximum limit value of
emission of particles to the atmosphere imposed by the regulatory
authorities worldwide.
[0022] With respect to the minimum target value, this concentration
of particles is between 20 mg/Nm.sup.3 and 30 mg/Nm.sup.3.
[0023] Preferably, the combustion catalyst includes at least an
element selected from iron (III) oxides, cerium (III) oxides,
cerium (IV) oxides and their mixtures.
[0024] Preferably, the quantity of particles emitted is measured
continuously.
[0025] The invention also has the objective of controlling the
quantity of solid particles emitted by a combustion turbine, when
using a liquid fuel, including means to inject a combustion
catalyst suitable for reducing the quantity of particles generated
by the installation.
[0026] This system also includes the means of measurement of the
quantity of particles emitted and a central control unit suitable
for controlling the injection means so as to inject the combustion
catalyst into the combustion turbine when the measured quantity of
particles is higher than a maximum threshold value and to stop the
injection of the catalyst when the measured quantity of particles
reaches a minimum target value.
[0027] The invention also concerns a gas turbine installation
comprising a system of control as defined above.
[0028] Other objectives, characteristics and advantages of the
invention are provided in the following description, given only by
way of non-limiting example, and with reference to the drawings
attached, in which:
[0029] FIG. 1 is a synoptic diagram of the constitution of an
installation of gas turbine comprising a system of control
according to the invention; and
[0030] FIG. 2 shows the curves illustrating the successive phases
of injection of fuel and stopping of the injection.
[0031] First of all, please refer to FIG. 1 which illustrates the
structure of a combustion turbine system according to an embodiment
of the invention.
[0032] As it can be seen, the combustion turbine, designated by the
general reference number 1, successively includes a compressor 2
which ensures the compression of the ambient air admitted at the
inlet of the combustion turbine, one or more combustion chambers 3
in which the compressed air from the compressor is mixed with a
fuel and ignited, and a turboexpander 4 in which the ignited gas is
expanded to produce mechanical energy for driving the compressor
and to provide the mechanical energy required for the application
implementing the combustion turbine.
[0033] At the outlet, gas is recovered by an exhaust system 5
connected to an energy recovery boiler 6 for evacuation to the
outside through a chimney 7.
[0034] The combustion chambers 3 are fed with fuel, in this case a
liquid fuel, through an inlet line 8 connected to a fuel source 9
and equipped with a flow regulator 10.
[0035] As indicated earlier, the combustion in the combustion
chambers 3 produce the solid particles, such as soot. These
particles pass through the turboexpander 4, the exhaust system 5,
the boiler 6, and are emitted to the outside by the chimney 7.
[0036] The combustion turbine system 1 includes injection means 10
to inject a combustion catalyst into the gas turbine in order to
reduce the quantity of solid particles, and more particularly the
concentration of solids generated during combustion.
[0037] The injection means 10 can be directly connected to the
combustion chambers 3 so as to inject the combustion catalyst into
the combustion chambers.
[0038] They can be also connected, as represented, to liquid fuel
feed line 8 so as to inject the combustion catalyst into the feed
line 8.
[0039] The injection means 10 comprise a central control unit 11, a
device 12 for measurement of the concentration of particles emitted
at the outlet of chimney 12 and a measurement device 13 for
measuring the liquid fuel flow in the feed line 8.
[0040] The central control unit 11 comprises a first controlling
stage 14 which includes a mapping 15 in which the reference flow
values of combustion catalyst Qrefcat are stored as a function of
reference flow values of fuel Qrefcomb. From the flow value of fuel
QF delivered by the measurement device 13, the first controlling
stage 14 retrieves a command catalyst flow value Ccat from the
mapping 15.
[0041] In other words, it concerns adapting the combustion catalyst
injection flow as a function of liquid fuel flow, which itself
depends on the charge level of the element driven by the combustion
turbine, for example an alternator.
[0042] The central control unit 11 also comprises a second
controlling stage 16 which receives the soot flow value Qsuies
provided by the measurement device 12. These measured values are
compared using comparators 17 and 18 with a maximum threshold value
and a minimum target value.
[0043] The output of the comparators 17 and 18 is provided to a
combined logic circuit, constituted, for example, by a RF rocker
whose output depends on the value of the concentration of soot with
respect to the threshold value.
[0044] The output of the RF rocker switches to a high level, if the
soot concentration Qsuies is higher than the maximum threshold
value and switches to a low level, if the soot concentration
reaches a minimum target value, and maintains its status, if the
soot concentration is between minimum target value and the maximum
threshold value.
[0045] The combustion catalyst injection means 10 comprise two
redundant catalyst injection lines L1 and L2, where one is an
injection line intended to be used during normal operation of the
installation and the other one is an optional emergency injection
line. The injection lines each are controlled by command signals
Cde1 and Cde2 coming from the combined logic circuit 7 through a
first component 19, a switch type, to control the operation or
shutdown of the two injection lines L1 and L2 and two components 20
and 21, also switch type, to selectively control the operation of
the injection lines L1 and L2.
[0046] Each of the injection lines L1 and L2 comprises a dosing
pump, respectively P1 and P2, fed from a combustion catalyst feed
system 22 and driven by an electric motor M, which itself is
powered by alternative sources, such as 23, through converters 24
receiving the command catalyst flow signal Ccat and driven by the
command signals Cde1 and Cde2. The output of each of the dosing
pumps P1 and P2 is connected to liquid fuel feed line 8 through
valves such as 25.
[0047] So, when the central control unit 11 detects that the soot
concentration measured by the measurement device 12 is higher than
the maximum threshold value, it commands the dosing pump by keeping
the command signal Cde 1 at the high level in order to power the
motor M so as to deliver a combustion catalyst flow Ccat retrieved
from the mapping 15 as a function of a fuel flow and a reference
catalyst flow.
[0048] If the concentration of solid particles becomes lower than
the minimum target value, then the injection of combustion catalyst
is stopped.
[0049] For example, for a combustion turbine generating a rated
electrical power of 100 MW and consuming about 32 tonnes/hour of
liquid fuel, the ratio between the combustion catalyst flow and the
liquid fuel flow is preferably between 0.003% and 0.006%, which
represents between 1 and 2 kg/hour of combustion catalyst. The
central control unit 11 controls the dosing pump according to the
measured concentration level of soot particles.
[0050] Above the maximum concentration threshold value, for example
between 45 mg/Nm.sup.3 and 55 mg/Nm.sup.3, the central control unit
11 starts the dosing pump. Below the target value, for example
between 20 mg/Nm.sup.3 and 30 mg/Nm.sup.3, the central control unit
11 stops the dosing pump.
[0051] Preferably, the maximum threshold and target values will be
set at 50 mg/Nm.sup.3 and 25 mg/Nm.sup.3, respectively. Continuous
monitoring of the concentration level enables to restart the dosing
pump later.
[0052] As indicated earlier, in case of failure of the first
injection L1 line, the second injection L2 line is activated to
ensure catalyst injection based on the signals Cde2 and Ccat.
[0053] Now please refer to FIG. 2, which illustrates the operation
of the system of control described.
[0054] This figure illustrates the variation of concentration of
particles as a function of time (curve A) and shows the evolution
depending on the time of thickness D1, . . . , Dn, Dn+1 of a layer
of catalyst deposited on the inner wall of the turbine.
[0055] As it can be seen in FIG. 2, the phases of injection of
combustion catalyst are thus implemented in a cyclic manner during
the operation of the combustion turbine.
[0056] The interval between two cycles of combustion catalyst
injection is based on the configuration of the installation. The
duration between two cycles of consecutive injection (T1, T2, T3,
Tn-1, Tn, Tn+1, etc.) increases depending on the time of use of
installation. However, Tn corresponds to the maximum duration
between two cycles of combustion catalyst injection. Tn+1 is lower
than or equal to Tn.
[0057] However, it should be noted that the injected active
combustion catalyst particles adhere to the walls of the
installation forming layers of active agents of variable thickness
as a function of time, producing a catalytic effect of conversion
of the solid particles into CO.sub.2.
[0058] After the combustion catalyst injection is interrupted, the
active particles adhering to the walls continue their catalytic
conversion effect. When catalyst injection is interrupted, the
layers of active particles subjected to movement and/or propagation
of combustion gases tend to be gradually carried away toward the
chimney and simultaneously consumed. As a result, the consumption
of active particles is such that the catalytic effect disappears
when all the active particles have been consumed. It is at this
time that it is necessary to proceed to a new injection of the
combustion catalyst.
[0059] As this is being done, this effect allows to carry out
combustion catalyst injection sequences at intervals, whose
duration decreases with time, while the injection stopping
sequences increase inversely proportionately, up to a limit
corresponding to the saturation of active particles on the walls of
the installation. This saturation phenomenon is related to the
thickness of the layers of deposits and the speed of propagation of
the combustion gases. In other words, the layer of active particles
does not thicken indefinitely, since the deposits are destabilized
and tend to fall off from the walls under the effect of speed of
the combustion gas. The combustion catalyst injection interval
depends on the result of measurement of the particle concentration,
higher than 25 mg/Nm.sup.3 and lower than 50 mg/Nm.sup.3. The
duration of the intervals depends on the inner surface of the walls
of the combustion installation, the exhaust gas flow and the
temperature.
[0060] The fuel used for feeding the combustion chambers can have
various types. For example, we can use a heavy fuel oil, crude oil,
a heavy or light distilled, gas oil, kerosene, naphtha, biodiesel,
bioethanol. However, it should be noted that using other liquid
fuel types is not beyond the scope of the invention.
[0061] We can use cerium(III) oxide, cerium(IV) oxide or an iron
oxide or a mixture of these catalysts as the oxidation catalyst.
The chemical reactions of conversion of soot into carbon dioxide
are as below:
[0062] For cerium(IV) oxide, the reaction is as below:
4CeO.sub.2+C (suies).fwdarw.2Ce.sub.2O.sub.3+CO.sub.2.
[0063] For cerium (III), the reaction is as below:
Ce.sub.2O.sub.3+1/2O.sub.2.fwdarw.2 CeO.sub.2, and
4CeO.sub.2+C (suies).fwdarw.2 Ce.sub.2O.sub.3+CO.sub.2.
[0064] It should be noted that cerium(III) is converted into
cerium(IV) due to the presence of oxygen in the flames:
Ce.sub.2O.sub.3+1/2O.sub.2.fwdarw.2CeO.sub.2
* * * * *