U.S. patent application number 11/927280 was filed with the patent office on 2008-09-11 for control system for gas turbine in material treatment unit.
This patent application is currently assigned to EarthRenew, Inc.. Invention is credited to Christianne Carin, Alvin W. Fedkenheuer, Brian N. Gorbell, John S. Jonasson, Alexander Starosud.
Application Number | 20080221772 11/927280 |
Document ID | / |
Family ID | 35597892 |
Filed Date | 2008-09-11 |
United States Patent
Application |
20080221772 |
Kind Code |
A1 |
Carin; Christianne ; et
al. |
September 11, 2008 |
CONTROL SYSTEM FOR GAS TURBINE IN MATERIAL TREATMENT UNIT
Abstract
This invention discloses systems and methods for control of a
gas turbine or a gas turbine generator, where the gas turbine is
connected to a dryer vessel in which gas turbine exhaust gases are
used to heat treat a material in the dryer vessel. The control
system comprises one or more sensors for temperature, moisture
and/or flow rate in the dryer vessel and/or of the material inside,
entering and/or exiting the dryer vessel and a controller
responsive to the sensor for controlling the fuel and/or air flow
into the gas turbine. This control system and method enables
providing the appropriate heat output from the gas turbine to meet
the process heat required for the desired material treatment.
Optionally, the gas turbine can be a liquid fuel turbine engine, or
a reciprocating engine can be substituted for the turbine
engine.
Inventors: |
Carin; Christianne;
(Priddis, CA) ; Gorbell; Brian N.; (Priddis,
CA) ; Carin; Christianne; (Priddis, CA) ;
Fedkenheuer; Alvin W.; (Calgary, CA) ; Jonasson; John
S.; (Tisdale, CA) ; Starosud; Alexander;
(Calgary, CA) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
EarthRenew, Inc.
Half Moon Bay
CA
|
Family ID: |
35597892 |
Appl. No.: |
11/927280 |
Filed: |
October 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10894875 |
Jul 19, 2004 |
|
|
|
11927280 |
|
|
|
|
Current U.S.
Class: |
701/100 |
Current CPC
Class: |
F26B 25/22 20130101;
F02C 9/00 20130101; F02C 6/04 20130101; Y02P 70/10 20151101; F26B
23/001 20130101; F26B 23/02 20130101; Y02P 70/405 20151101 |
Class at
Publication: |
701/100 |
International
Class: |
F02C 9/00 20060101
F02C009/00 |
Claims
1-35. (canceled)
36. A controller for a material treatment system, including a gas
turbine or reciprocating engine having its exhaust connected to a
dryer vessel which is adapted for treating material with heat from
the exhaust, comprising: a programmable computer adaptable for
processing information from sensors detecting preselected
conditions of the gas turbine operation, the dryer vessel operation
or the material before, during or after treatment in the dryer
vessel; for prioritizing sensor inputs for control and for
commanding actuators for combustion air or fuel flow to the gas
turbine.
37. A controller according to claim 36 further comprising a
programmable aspect for commanding actuators for material flow to
the dryer vessel.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/894,875, filed Jul. 19, 2004, entitled "Control System
for Gas Turbine in Material Treatment Unit", which is incorporated
herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to control systems for material
treatment equipment systems which comprise a gas turbine engine or
other internal combustion engine and a dryer vessel and which
utilizes the engine exhaust gases to heat treat various materials
in the dryer vessel.
BACKGROUND OF THE INVENTION
[0003] Gas turbine generator exhaust has been used for drying or
processing various materials, but existing control systems for such
equipment do not provide for efficient operation of such equipment.
Typically, gas turbine generators are controlled for optimum fuel
usage, water spray intake, engine life, electricity production or
profitability based on these and other factors. Examples of gas
turbine generator control systems are disclosed in U.S. Pat. Nos.
5,584,171 to Sato et al.; 6,125,633 and 6,173,508 to Strohmeyer;
6,748,743 to Foster-Pegg; U.S. Patent Applications 2004/0050069 by
Willems et al.; 2004/0060277 by Hatamiya et al.; and 2004/0103068
by Eker et al., the disclosures of which are incorporated herein by
reference in their entirety.
[0004] There is a need in the art for improved systems and methods
for control of gas turbine and other engine operations in
conjunction with the use of engine exhaust gases for treatment of
materials.
SUMMARY OF THE INVENTION
[0005] In one aspect, this invention provides a material treatment
apparatus comprising a gas turbine having combustion air and fuel
inlets; a dryer vessel connected to and adapted for receiving
exhaust gases from the gas turbine and adapted for receiving
material for treatment in the dryer vessel with heat from the
exhaust gases; a temperature sensor for detecting the temperature
at a desired location in the dryer vessel; and a controller
responsive to the temperature sensor for controlling the combustion
air flow and/or the fuel flow to the turbine.
[0006] In another aspect, this invention provides a material
treatment apparatus comprising a gas turbine having combustion air
and fuel inlets; a dryer vessel connected to and adapted for
receiving exhaust gases from the gas turbine and adapted for
receiving material for treatment in the dryer vessel with heat from
the exhaust gases; a temperature sensor for detecting the
temperature of the heated material at a desired location in the
dryer vessel or at a desired location downstream of the dryer
vessel; and a controller responsive to the temperature sensor for
controlling the combustion air flow and/or the fuel flow to the
turbine.
[0007] In another aspect, this invention provides a method for
controlling a material treatment apparatus comprising a gas turbine
having a combustion air inlet and a fuel inlet and a dryer vessel
connected to the gas turbine and having a temperature sensor
therein and being adapted for receiving exhaust gases from the gas
turbine and adapted for receiving material for treatment therein
with heat from the exhaust gases, the method comprising: using the
sensed temperature for controlling the combustion air flow and/or
the fuel flow to the turbine.
[0008] In another aspect, this invention provides a method for
controlling a material treatment apparatus comprising a gas turbine
having a combustion air inlet and a fuel inlet; a dryer vessel
connected to the gas turbine and adapted for receiving exhaust
gases from the gas turbine and adapted for receiving material for
treatment in the dryer vessel with heat from the exhaust gases; and
a temperature sensor for sensing the temperature of the material at
a desired location in the dryer vessel or downstream of the dryer
vessel, the method comprising: using the sensed temperature for
controlling the combustion air flow and/or the fuel flow to the
turbine.
[0009] In all the above aspects, a reciprocating engine can be
substituted for the gas turbine.
[0010] In another aspect, this invention provides a gas turbine
engine comprising an exhaust connection adapted to transmit at
least a portion of the turbine exhaust gases into a dryer vessel
and adapted to substantially preclude introduction of outside air
into the dryer vessel with the exhaust gases.
[0011] In another aspect, this invention provides a gas turbine
engine comprising a fuel and/or combustion intake air controller
adapted to be responsive to a temperature sensor positioned to
sense the temperature at a desired location in a dryer vessel
connected to and receiving exhaust gases from the gas turbine.
[0012] In another aspect, this invention provides a gas turbine
engine comprising a fuel and/or combustion intake air controller
adapted to be responsive to a temperature sensor positioned to
sense the temperature at a desired location of material treated in
a dryer vessel connected to and receiving exhaust gases from the
gas turbine.
[0013] In another aspect, this invention provides a controller for
a material treatment system, including a gas turbine or
reciprocating engine having the exhaust connected to a dryer vessel
which is adapted for treating material with heat from the exhaust,
comprising: a programmable computer adaptable for processing
information from sensors detecting preselected conditions of the
gas turbine operation, the dryer vessel operation or the material
before, during or after treatment in the dryer vessel; for
prioritizing sensor inputs for control and for commanding actuators
for combustion air or fuel flow to the gas turbine.
[0014] In all of the above aspects, the turbine engine or
reciprocating engine can include an electric generator.
BRIEF DESCRIPTION OF THE DRAWING
[0015] The drawing is a schematic diagram illustration of an
embodiment of the control systems and components of the present
invention.
DESCRIPTION OF THE INVENTION
[0016] The present invention provides new technology and systems
for the control of material treatment processes, apparatus and
systems that comprise internal combustion engines, preferably gas
turbine engines, connected to dryer vessels for treatment and/or
conversion of material feedstocks to produce useful, recyclable or
environmentally acceptable materials and products. In particular,
these material treatment processes, apparatus and systems employ
the combination of such engines and dryer vessels adapted such that
the engine exhaust gases are directed into the dryer vessel to dry
and/or heat treat a material introduced into and processed in the
dryer vessel. Such processes, apparatus and systems and their uses
are the subject matter of and are disclosed in commonly assigned
U.S. Pat. No. 7,024,796, which issued Apr. 11, 2006 and U.S. Pat.
No. 7,024,800, which issued Apr. 11, 2006, the disclosures of which
are incorporated herein by reference in their entirety.
[0017] In the operation of the above material treatment systems, an
efficient and preferred way of providing the hot gases for contact
with the material feedstock treated in the dryer vessel is the
exhaust from a gas turbine, and preferably from a gas turbine
electric generator. The gas turbine is fueled from locally
available conventional fuel sources, and the electricity produced
from the gas turbine generator is preferably sold back into the
local power grid as a revenue source for the operation. The
electricity can be used internally in the operation of the material
treatment system or in other nearby operations as a supplemental
source of power. It is preferable and more efficient in the
operation of the system to sell the electric power produced to the
local power grid. This enables varying the operation of the
material treatment process and equipment systems in the most
efficient and effective manner for treatment of the material
feedstock to produce the desired quality and quantity of products
without concern for or being constrained by any particular minimum
or necessary level of electricity output or the need for an
unchanging level of electricity output.
[0018] An optional and preferred aspect of the above systems is
that the gas turbine and the dryer vessel receiving the exhaust gas
from the gas turbine are connected together such that induction of
outside air into the dryer vessel is precluded and the dryer vessel
preferably receives the exhaust gases directly from the gas
turbine. It is preferred that 100% of the gas turbine exhaust gases
are passed into the dryer vessel and, for most efficient operation,
preferably without passing through any intervening heat exchanger,
silencer or other equipment in order that the dryer vessel receives
the maximum heating from the gas turbine exhaust. In this
arrangement, the dryer vessel also serves as a silencer for the gas
turbine, and efficient operation is achieved by not heating
additional outside air along with the material being treated. But,
it is recognized that excess exhaust gases not needed for the dryer
vessel operation can be diverted to provide heat required in other
steps in the material treatment systems or in other nearby
operations.
[0019] The terms "material for treatment," "treated material,"
"material feedstock" and the like are used herein to mean and
include the matter which is prepared for, fed into or processed in
the dryer vessel forming a part of a material treatment process,
apparatus or system referred to above, as more fully disclosed and
described in the above-referenced commonly assigned U.S. patents.
The material is processed in the dryer vessel by contact with the
engine exhaust gases or by heat provided from the engine exhaust
gases.
[0020] The term "gas turbine" is used herein to mean and include
any turbine engine having a compressor turbine stage, a combustion
zone and an exhaust turbine stage that is capable of producing
exhaust gas temperatures of at least 500.degree. F., preferably at
least about 700.degree. F., more preferably at least about
900.degree. F. and most preferably greater than about 1,000.degree.
F. Gas turbines are the heat source preferred for use with the
dryer vessel in the material treatment systems because of their
efficient operation and high heat output. The gas turbine generator
is further preferred for use due to the production of energy by the
generator, which energy can be utilized or sold to improve the
economics of the material treatment operation. The generator will
typically be an electric generator due to the convenience of using
and/or selling the electricity produced. However, the generator can
be any other type of energy generator desired, such as a hydraulic
pump or power pack that can drive hydraulic motors on pumps,
augers, conveyors and other types of equipment in the material
treatment systems or equipment in other nearby operations. The heat
requirements and the material treatment system economics will
determine whether a gas turbine or gas turbine generator is used.
If it is desired to have higher temperature exhaust gases and
higher heat output from a given smaller size gas turbine, it may be
desired to use a gas turbine instead of a similar size gas turbine
generator. Compared to the gas turbine, the gas turbine generator
further expands and cools the exhaust gases in absorbing energy to
drive the generator, where in a gas turbine that energy is
contained in higher temperature gases available for use in the
dryer vessel of this invention. This can be an option when it is
economically more important to have small portable high temperature
material treatment units than to have the revenue stream or
economic benefit of the electricity production.
[0021] The gas turbine or gas turbine generator useful in the
material treatment system can be fueled from any available source
with any suitable fuel for the particular gas turbine and for the
process equipment employed. The preferred and conventional fuels
are sweet natural gas, diesel, kerosene and jet fuel because the
gas turbines are designed to run most efficiently on good quality
fuels of these types and because of their common availability,
particularly at remote agricultural operations, where the material
treatment units are often located. However, other fuels that can be
used to fuel the gas turbine include methane, propane, butane,
hydrogen and biogas and bioliquid fuels (such as methane, oils,
diesel and ethanol).
[0022] Examples of commercially available gas turbines and gas
turbine generators useful in the material treatment systems include
the following (rated megawatt (MW) outputs are approximate): [0023]
Rolls Royce Gas Turbine Engines Allison 501-KB5, -KB5S or -KB7
having a standard condition rated output of 3.9 MW [0024] European
Gas Turbines Tornado having rated output of 7.0 MW [0025] Solar
Mars 90 having rated output of 9.4 MW and Solar Mars 100 having
rated output of 10.7 MW [0026] Solar Tarus 60 having rated output
of 5.5 MW and Solar Tarus 70 having rated output of 7.5 MW For a
nominal product output capacity of 2.5 metric tons/hr. (2,500
kg/hr) a gas turbine generator size of about 4 MW can be used,
depending on the heat insulation and heat recovery efficiencies
designed into the overall system. For small single semitrailer or
truck systems, the units may be scaled smaller. For smaller product
output systems, such as an 0.3 metric ton/hr product output, small
gas turbines, such as Solar Saturn 0.8 MW, Solar Spartan 0.2 MW or
Capstone 0.5 MW or 0.3 MW generators, can be used depending on
system efficiencies and required heat input ranges. It will be
recognized that the material treatment systems can also be designed
to utilize the exhaust gas heat from reciprocating engines, such as
gasoline or diesel engines, with or without electric
generators.
[0027] The dryer vessel employed in the material treatment systems
can be any type or configuration that is suitable for drying the
material feedstock available and that can be adapted for receiving
the gas turbine exhaust gases and receiving the material feedstock,
preferably without allowing a significant amount of outside air to
enter the drying chamber in the dryer vessel where the exhaust
gases contact the material feedstock. A preferred design of the gas
turbine exhaust connection to the dryer vessel is to preclude any
significant outside air from entering the dryer vessel thereby
preventing any significant oxidation of the material feedstock.
Alternate sources of hot gases other than a gas turbine can be used
and connected to the dryer vessel, such as the exhaust from
conventional oil or gas burners and reciprocating engines. Such an
alternate and additional source of hot gases can optionally be
connected to the dryer vessel and be used to supplement the exhaust
output of the gas turbine in order to provide additional heat input
capacity for the dryer vessel, if needed for start up, shut down or
surge load conditions or for backup in the event the gas turbine
goes off line.
[0028] The types of dryer vessels that can be used in the material
treatment systems includes, for example, the following: [0029]
Rotary drum with or without internal scrapers, agitation plates
and/or paddles [0030] Stationary "porcupine" drum dryer with or
without scrapers and/or agitator plates and/or paddles [0031]
Triple pass stepped drying cylinder or rotary drum dryer systems
with or without scrapers and/or agitator plates and/or paddles
[0032] Rotary drum dryer systems with or without steam tubes and
with or without scrapers and/or agitator plates and/or paddles
[0033] Turbo-dryer or turbulizer systems [0034] Conveyor dryer
systems with or without scrapers and/or agitator plates and/or
paddles [0035] Indirect or direct contact dryer systems with or
without scrapers and/or agitator plates and/or paddles [0036] Tray
dryers [0037] Fluid bed dryers [0038] Evaporator systems [0039]
Baking ovens
[0040] Examples of commercially available dryer vessels useful in
or that can be adapted for use in the material treatment systems
include: [0041] Scott AST Dryer.TM. Systems [0042] Simon Dryer
Ltd.--Drum dryers [0043] Wyssmont Turbo Dryer systems [0044] Duske
Engineering Co., Inc. [0045] Energy Unlimited drying systems [0046]
The Onix Corporation dehydration systems [0047] International
Technology Systems, Inc. direct or indirect dryer systems [0048]
Pulse Drying Systems, Inc. [0049] MEC Company dryer systems Further
examples of dryer vessels useful in or that can be adapted for use
in the material treatment systems are disclosed in U.S. Pat. Nos.
5,746,006 to Duske et al. and 5,570,517 and 6,367,163 to Luker, the
disclosures of which are incorporated herein by reference in their
entirety.
[0050] The term "dryer vessel" is not limited to a drying function
and the "dryer vessel" equipment does not necessarily always
function primarily as a dryer by removing moisture from the
material being treated. In addition to or instead of drying or
moisture removal, the dryer vessel also functions as the thermal
treatment/conversion/alteration vessel or oven in which the
material feedstock is heated to sufficient temperatures for
sufficient times to produce the conversion to desired final
materials and products. In addition, the dryer vessel need not
provide direct contact of the turbine exhaust gases or other heat
source and the material feedstock, but can provide indirect heating
of the material feedstock to achieve the drying and/or thermal
treatment/conversion/alteration desired. Various configurations of
gas turbines and dryer vessels can be used in the material
treatment systems. For example, two dryer vessels can be operated
in series where a high water content material feedstock is dried in
the first dryer vessel then the output from the first dryer vessel
is thermally treated in the second dryer vessel to achieve the
desired chemical or physical conversion or alteration. In such an
arrangement, the exhaust gases can be supplied from a single gas
turbine exhaust split between the two dryer vessels, or can be
supplied by two separate gas turbines. From this example it can be
seen that the material treatment processes, apparatus and systems
can be adapted to operate various equipment components in series or
in parallel to perform various processing functions desired to
achieve the effective and economic operation of the material
treatment system.
[0051] Another aspect of the dryer vessel adapted for use in the
material treatment system is that the dryer vessel preferably also
functions as the silencer for the gas turbine or other engine
providing the hot exhaust gases. It is well known that gas turbines
(essentially jet aircraft engines) produce a high level of noise
impact on the nearby environment. Stationary gas turbines used for
electric power production or other purposes are usually required by
local, state and federal regulations to have silencers installed to
muffle the noise of the exhaust of the gas turbine to acceptable
levels. Such silencers have the economic disadvantages of cost and
creating back pressure on the gas turbine exhaust, which reduces
the efficiency of the gas turbine operation. Due to the connection
between the gas turbine exhaust and the dryer vessel preferably
being closed to outside air, is that the dryer vessel functions
effectively as a silencer for the gas turbine. This is at least in
part a result of the internal configuration construction of the
dryer vessel acting in combination with the presence of the high
water content material feedstock, which combination is effective in
absorbing and muffling the gas turbine exhaust noise. This is also
due to the downstream end of the dryer also being closed to the
atmosphere, because the steam and off gases from the dryer vessel
are collected for condensation, cleaning, recycling and for heat
recovery in the downstream processing in a closed system before
being vented to the atmosphere. In addition, due to the closed
system, the dryer vessel and downstream equipment can be operated
at reduced pressure to eliminate the back pressure on the gas
turbine exhaust.
[0052] Another advantage provided by these material treatment
systems results from the contact of the gas turbine exhaust gas
with the material feedstock in the confined space of the dryer
vessel without significant outside air present. The NO.sub.X and
SO.sub.X emissions, and to some extent CO and CO.sub.2 emissions,
in the gas turbine exhaust are substantially reduced, and in some
cases reduced to zero, by absorbing or complexing of the NO.sub.X
and SO.sub.X components into the material feedstock as it is
treated, where they remain absorbed, complexed or fixed in the
dried or treated material exiting the dryer vessel and in the
product after processing into granular, pellet or prill or other
form. This provides the advantage, e.g., when a fertilizer product
is being produced, of both lowering or eliminating the emissions of
NO.sub.X and SO.sub.X (and CO/CO.sub.2) into the atmosphere and
adding the nitrogen, sulfur and carbon components to the nutrient
value of the product produced by the material treatment system.
[0053] The typical turbine exhaust gas temperature entering the
dryer vessel will be in the range of about 500.degree. F. to about
1,500.degree. F., depending on moisture and other content of the
material feedstock and the desired condition of the treated
material product output from the dryer vessel. In smaller systems
with smaller engines, the dryer vessel inlet exhaust gas
temperature can be as low as about 300.degree. F. or about
350.degree. F. A preferred range is from about 600.degree. F. to
about 1200.degree. F., and it is more preferred that the inlet
temperature be at least about 650.degree. F. and most preferably at
least about 700.degree. F. The temperature and flow rate of the gas
entering the dryer vessel will depend in part on the moisture
content and other properties of the material feedstock. Higher
moisture content will obviously generally require higher inlet gas
temperatures to reduce the moisture content. An additional process
efficiency is achieved in the material treatment systems where high
moisture content material feedstock is contacted with high
temperature exhaust gases. Such contact causes the formation,
sometimes instantly, of superheated steam as the moisture comes out
of the material feedstock, then that superheated steam heats and
drives the moisture out of adjacent material feedstock. It is
believed that this mechanism is responsible for quick drying of the
material feedstock to a low moisture content so that the remaining
residence time of the material feedstock in the dryer vessel
contributes to the desired thermal treatment/conversion/alteration
or "cooking" of the material to achieve the desired product. Some
material feedstocks may require lower temperatures but longer
residence time to achieve the conversion or "cooking" needed to
produce a product having desired properties. The temperature of the
material exiting the dryer vessel will typically be in the range of
about 150.degree. F. to about 450.degree. F. and preferably between
about 200.degree. F. and about 350.degree. F. In some operations,
the dryer vessel exit temperature of the material should be at
least about 175.degree. F. and preferably at least about
200.degree. F.
[0054] The material feedstock typically will have a moisture
content between about 50% and about 90% by weight, preferably
between about 60% and about 80% by weight and most preferably
between about 65% and about 75% by weight. (Percent by weight, as
used herein, is in reference to percent of the component in
question based on the total weight of the mixture referred to.)
Although material feedstock of lower moisture content, for example,
as low as about 40% by weight or even 30% by weight can be
processed in the treatment systems. The preferred material
feedstock has a moisture content of at least about 50% by weight,
more preferably at least about 60% and most preferably at least
about 70% by weight. The temperature of the material feedstock will
typically be ambient, i.e., in the range of about 30.degree. F. to
about 100.degree. F., but can be lower than 30.degree. F., provided
that any frozen agglomerations do not interfere with the feedstock
preparation or the operation of the dryer vessel and feedstock
feeder equipment. The material feedstock may be used at any
temperature direct from a manufacturing facility or from a process
unit, which may be at an elevated temperature. The economics of the
systems of this invention are usually improved if the material
feedstock is at an elevated temperature or is preheated prior to
introduction into the dryer vessel.
[0055] The output from the dryer vessel comprises a gas phase
comprising steam, water vapor, combustion gases and a solids phase
comprising the treated material dried and/or thermally treated and
converted to desired forms. Typical dryer vessel outlet
temperatures of the gases and/or solids will normally range from
about 200.degree. F. to about 350.degree. F., but lower or higher
temperatures may be selected and/or desired for economic, product
quality and/or process efficiency reasons. The outlet temperatures
can be from at least about 110.degree. F. to at least about
500.degree. F., preferably at least about 180.degree. F. and more
preferably at least about 200.degree. F. It is generally desired
that the solids material exiting the dryer vessel will generally
have a moisture content between about 10% and about 15% by weight,
but can range from about 5% to about 25% by weight. Again, lower
(near zero) or higher moisture content of the dryer vessel output
solids may be selected and/or desired for similar reasons. The
steam, water vapor and combustion gases exiting the dryer vessel
will normally be routed through heat exchangers (for recovery of
process heat usable downstream in granulating or pelletizing
operations or upstream in feedstock or turbine intake air
preheating), condensers (for recovery of process water for upstream
or downstream use, for industrial application or for disposal),
scrubbers, filters or cyclones (for recovering solids entrained in
gases or liquids and rendering gases and liquids environmentally
acceptable for release) and other conventional process
equipment.
[0056] The present invention comprises the combination of material,
process and equipment condition sensors deployed in the above
material treatment systems and a controller for the gas turbine
engine. The sensors useful in this invention are primarily
temperature, moisture content and flow rate sensors, but can also
include other sensors, such as pressure, pH and chemical (e.g., CO,
CO.sub.2, etc.) sensors. The sensors are primarily deployed to
measure conditions of the material being treated and conditions of
or inside the equipment used in the material treatment systems, but
can also include other sensors, such as ambient air temperature and
wind velocity, fuel temperatures, etc. The types of sensors to be
used will be apparent to one skilled in the art and include
mechanical, infrared, magnetic, electric, piezoelectirc and other
conventional and state of the art sensors available for measuring
the desired conditions at the desired points in the system. The
sensors can communicate with the controllers mechanically,
electrically, remotely by RF or infrared or in other conventional
ways.
[0057] The controllers useful in this invention are primarily for
the gas turbine engine combustion air intake and fuel flow, but can
also include controllers for intake water injection, such as water
mist injection conventionally used in gas turbine engine intake,
stator vane or guide vane angle adjustment, air or fuel preheaters
and other parameters that control the running conditions of the gas
turbine engines and/or the power output and exhaust gas
temperatures and volumes. As noted above the sensors and
controllers are adapted to communicate as appropriate so that the
controllers respond to the sensors and sensed conditions as needed
for process control according to this invention. While the
controllers are discussed and illustrated with respect to gas
turbine engines, it will be apparent to one skilled in the art to
apply and adapt same to reciprocating engine control.
[0058] This invention is further illustrated in reference to the
drawing, which shows by example gas turbine generator 101/102 with
fuel, air and water inlets producing exhaust gas that is directed
into dryer vessel 200 and electricity. Dryer vessel 200 also has
inlet for the material feedstock from feedstock flow controller
300. The control system and methods of this invention are
illustrated by controller 400 which controls actuators for the
fuel, air and water feed to the gas turbine and which communicates
with and is selectively responsive to the various temperature
sensors, T, moisture content sensors, M, and/or flow rate sensors,
F. The controller preferably comprises a programmable computer of
the type conventionally used in process plant control systems
wherein the control priorities and input/output criteria can be set
and changed as appropriate for different equipment, different
material feedstock, different material treatment desired and other
variables. For example, the controller can be set to control the
air and fuel (and optionally water) feed to the gas turbine in
response to the temperatures T.sub.D1 or T.sub.D2 in the dryer
vessel so that as feedstock load increases and the temperature
drops, the controller increases the air and fuel to the gas turbine
to increase the temperature and/or volume of exhaust gas entering
the dryer vessel. Alternatively, the controller can be set to
respond to the temperature Tsp of the solid phase treated material
output from the dryer vessel. In such case, the sensor inputs from
T.sub.D1 or T.sub.D2 may be used for upper limit control so the
dryer vessel does not overheat. Similarly the gas turbine exhaust
gas temperature T.sub.EG can be used for upper limit safety and
equipment protection control. One objective of the control system
of this invention is to have the gas turbine operation singularly
or primarily responsive to the heat requirements in the dryer
vessel to provide the desired heating for desired treatment by
drying and/or conversion of the feedstock material being
processed.
[0059] As will be apparent to one skilled in the art applying the
control system this invention to the material treatment system and
equipment, an intelligent, anticipatory or predictive control
program can be used. In order to reduce the lag time from sensing
heat requirements, for example from T.sub.SP, the control system
can integrate all available data regarding incoming feedstock
temperature T.sub.FS in order to anticipate what the heat
requirement will be in the dryer vessel for that feedstock and
adjust the gas turbine power settings to anticipate the heat
requirement when the desired volume feedstock enters the dryer
vessel. Similarly other sensor inputs, comprising the exhaust gas
flow rate F.sub.EG, the moisture level at any point in the dryer
vessel M.sub.D, the flow rate of the treated solids product
F.sub.SP and the temperature T.sub.GP, moisture content M.sub.GP
and flow rate F.sub.GP of the gas phase exiting the dryer vessel,
can be used for integrated, predictive process control or merely as
operating limits for safety, product quality, efficiency or other
consideration. Other inputs can be used as well to achieve desired
or optimum overall system efficiency and profitability, including
fuel prices, electricity prices, seasonal product demand and
pricing and the like. For example, spot fuel and electricity
pricing can vary during the day or from day to day. The controller
of this invention can provide system operation at minimum fuel cost
times and maximum electricity price times to maximize
profitability, because the material to be treated can often be
stockpiled then processed and treated at the most economically
favorable times.
[0060] In a most preferred embodiment controller 400 will also
communicate with and act as secondary control of the feedstock flow
controller 300 to achieve balanced operation. While the feedstock
flow will normally be set manually to a desired production
throughput of the material treatment system, it will be
advantageous to have controller 400 adjust controller 300 toward
the desired throughput while keeping the system balanced to provide
desired temperatures and desired material treatment conditions in
the system.
[0061] As described above, various other sensor input sources not
shown on the drawing can be utilized to further enhance the
anticipatory or predictive function of the control system of this
invention, such as ambient air temperature and wind velocity,
rainfall monitor, etc., which may affect heat load requirement in
the material treatment system. The electricity production F.sub.KW
is illustrated in the drawing, but will not normally be an
operating input parameter or limit. However, the controller can
monitor F.sub.KW for revenue source from electricity sales and, in
the event the material treatment system is off line but electricity
generation is desired, the gas turbine generator 101/102 can be
controlled by the controller 400 in a conventional manner based on
F.sub.KW.
[0062] Finally, it will be recognized that in the control system of
this invention the gas turbine need not be controlled for optimum
gas turbine operation, such as for minimum NO.sub.X and SO.sub.X
emissions in some material treatment operations, because the
NO.sub.X and SO.sub.X will be captured and absorbed in the treated
material. However, in other operations, it may be imperative to
minimize NO.sub.X and SO.sub.X in the gas turbine exhaust because
it is undesirable or not permitted to have NO.sub.X and SO.sub.X
absorbed in the treated product. The control system of this
invention can be operated to meet all of these requirements and
others. Similarly, fuel efficiency of the gas turbine may not be
important compared to the heat or other requirements of the
material treatment system operation or compared to the overall
economics of the material treatment system. The control system of
this invention can be operated to prioritize any desired aspect or
operational parameters of the material treatment system.
[0063] As will be apparent to one skilled in the art, the material
treatment system can comprise multiple gas turbines, other engines
and/or burners of the same or varying types and sizes can be
manifolded together to feed multiple dryer vessels of the same or
varying types and sizes in a single installation. This can be done
to not only provide increased feedstock processing capacity but
also to provide operational flexibility for processing varying
feedstock loads and for performing equipment maintenance without
shutting down the operation. The control system of the present
invention can be adapted to control multiple engines in response to
sensors measuring conditions in and resulting from material
treatment in multiple dryer vessels.
[0064] While we have illustrated and described various embodiments
of this invention, these are by way of illustration only and
various changes and modifications may be made within the
contemplation of this invention and within the scope of the
following claims.
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