US5029535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of addition of conditioning agents to flue gas
Assignee: WEXFORD MANAGEMENT LLC
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Filing: 1990-05-14
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Granted: 1991-07-09
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Expires: 2010-05-14
Abstract
Abstract Additions of conditioning agents to a particulate-containing flue gas stream are controlled by a controller operating from feedforward and feedback signals received from sensors in the combustion and gas cleanup system, and, optionally, from the power consumption level of the electrostatic precipitator. The flow rates of the conditioning agents, such as sulfur trioxide and ammonia, are thereby balanced to achieve an optimal removal of particulate matter and also sulfur and sulfur compounds from the gas stream before it is exhausted to the atmosphere. A typical feedforward signal is the boiler loading, and typical feedback signals include residual sulfur trioxide and ammonia levels and stack gas opacity.
Inventors
- 👤 Henry V. Krigmont
- 👤 Everett L. Coe, Jr.
- 👤 Barry J. Southam
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:50
CPC Classifications
F; F23; F23J; F23J15/00; F23J15/02; B; B01; B01D; B01D53/00; B01D53/34; B01D53/346; B03; B03C; B03C3/00; B03C3/01; B03C3/013; Y; Y10; Y10S; Y10S55/00; Y10S55/30
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
208 words
Apparatus for controlling the addition of conditioning agents to a particulate-containing flue gas stream that passes through an air preheater and subsequently passes through a set of precipitation electrodes of an electrostatic precipitator before being exhausted to the atmosphere, comprising: means for adding at least two conditioning agents, which chemically interact with the particulate matter in the flue gas and with each other, to a stream of flue gas, at least one of the conditioning agents being added to the flue gas stream after the flue gas stream has passed through the air preheater but before it passes through the set of precipitation electrodes; a feedforward sensor that senses the flue gas and provides a feedforward signal indicative of the mass flow rate of particulate matter in the flue gas prior to the addition of the conditioning agents; a feedback sensor that senses the flue gas after the addition of the conditioning agents, and produces a feedback signal indicative of the physiochemical effect on the flue gas/particle stream of the addition of the conditioning agents; and a controller that receives the feedforward signal and the feedback signal, and adjusts the amounts of the conditioning agents added to the flue gas stream based upon the values of the signals.
Claim 2
Dependent Claim
208 words
Apparatus for controlling the addition of conditioning agents to a particulate-containing flue gas stream that passes through an air preheater and subsequently passes through a set of precipitation electrodes of an electrostatic precipitator before being exhausted to the atmosphere, comprising: means for adding at least two conditioning agents, which chemically interact with the particulate matter in the flue gas and with each other, to a stream of flue gas, at least one of the conditioning agents being added to the flue gas stream after the flue gas stream has passed through the air preheater but before it passes through the set of precipitation electrodes; a feedforward sensor that senses the flue gas and provides a feedforward signal indicative of the mass flow rate of particulate matter in the flue gas prior to the addition of the conditioning agents; a feedback sensor that senses the flue gas after the addition of the conditioning agents, and produces a feedback signal indicative of the physiochemical effect on the flue gas/particle stream of the addition of the conditioning agents; and a controller that receives the feedforward signal and the feedback signal, and adjusts the amounts of the conditioning agents added to the flue gas stream based upon the values of the signals.
Claim 3
Dependent Claim
31 words
The apparatus of claim 1, further including: a second feedback sensor that senses the flue gas after the addition of the conditioning agents, and produces a second feedback signal indicative thereof.
Claim 4
Dependent Claim
20 words
The apparatus of claim 1, wherein the feedforward sensor measures the volume of particulate matter carried by the flue gas.
Claim 5
Dependent Claim
16 words
The apparatus of claim 1, wherein the feedforward sensor measures the firing rate of the combustor.
Claim 6
Dependent Claim
15 words
The apparatus of claim 1, wherein the feedback sensor is a stack gas opacity monitor.
Claim 7
Dependent Claim
15 words
The apparatus of claim 1, wherein the feedback sensor is a residual sulfur trioxide monitor.
Claim 8
Dependent Claim
14 words
The apparatus of claim 1, wherein the feedback sensor is a residual ammonia monitor.
Claim 9
Dependent Claim
17 words
The apparatus of claim 1, wherein the feedback sensor measures the power utilized by the electrostatic precipitator.
Claim 10
Dependent Claim
12 words
The apparatus of claim 1, wherein the controller is a digital microcomputer.
Claim 11
Dependent Claim
27 words
The apparatus of claim 9, wherein the microcomputer includes an instruction set that controls the total flow rate of conditioning agents added responsive to the feedforward signal.
Claim 12
Dependent Claim
26 words
The apparatus of claim 10, wherein the microcomputer includes an instruction set that controls the relative amounts of conditioning agents added responsive to the feedback signal.
Claim 13
Dependent Claim
24 words
The apparatus of claim 1, wherein the controller adjusts the flow of at least one of the conditioning agents to be an intermittent flow.
Claim 14
Dependent Claim
14 words
The apparatus of claim 12, wherein the conditioning agent that flows intermittenly is ammonia.
Claim 15
Dependent Claim
14 words
The apparatus of claim 1, wherein one of the conditioning agents is sulfur trioxide.
Claim 16
Dependent Claim
13 words
The apparatus of claim 1, wherein one of the conditioning agents is ammonia.
Claim 17
Dependent Claim
171 words
A process for controlling the addition of conditioning agents to a stream of a flue gas containing particulate matter in a flue gas cleanup system having a conditioning agent injector, an electrostatic precipitator to which the flue gas passes after the conditioning agent is added, and an exhaust from the electrostatic precipitator, comprising the steps of: adding at least two conditioning agents, which chemically interact with the particulate matter in the flue gas and with each other, to the flue gas stream; sensing the flue gas prior to the addition of the conditioning agents, and providing a feedforward signal indicative of the mass flow rate of particulate matter in the flue gas; sensing the flue gas after the addition of the conditioning agents, and providing a feedback signal indicative of the physiochemical effect on the flue gas/particulate stream of the addition of the conditioning agents; and controlling the amounts of the conditioning agents added to the flue gas stream based upon the values of the feedforward signal and the feedback signal.
Claim 18
Dependent Claim
171 words
A process for controlling the addition of conditioning agents to a stream of a flue gas containing particulate matter in a flue gas cleanup system having a conditioning agent injector, an electrostatic precipitator to which the flue gas passes after the conditioning agent is added, and an exhaust from the electrostatic precipitator, comprising the steps of: adding at least two conditioning agents, which chemically interact with the particulate matter in the flue gas and with each other, to the flue gas stream; sensing the flue gas prior to the addition of the conditioning agents, and providing a feedforward signal indicative of the mass flow rate of particulate matter in the flue gas; sensing the flue gas after the addition of the conditioning agents, and providing a feedback signal indicative of the physiochemical effect on the flue gas/particulate stream of the addition of the conditioning agents; and controlling the amounts of the conditioning agents added to the flue gas stream based upon the values of the feedforward signal and the feedback signal.
Claim 19
Dependent Claim
29 words
The process of claim 16, wherein the step of sensing the flue gas prior to the addition of the conditioning agent includes the step of measuring the boiler load.
Claim 20
Dependent Claim
38 words
The process of claim 16, wherein the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the opacity of the flue gas after it has left the electrostatic precipitator.
Claim 21
Dependent Claim
41 words
The process of claim 16, wherein the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the residual sulfur trioxide content in the flue gas after it has left the electrostatic precipitator.
Claim 22
Dependent Claim
32 words
The process of claim 16, wherein the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the power consumption of the electrostatic precipitator.
Claim 23
Dependent Claim
48 words
The process of claim 16, wherein the step of sensing the flue gas prior to the addition of the conditioning agent includes the step of measuring the boiler load, and in the step of controlling, the total flow rate of conditioning agents is dependent upon the feedback signal.
Claim 24
Dependent Claim
14 words
The process of claim 16, wherein the conditioning agents are sulfur trioxide and ammonia.
Claim 25
Dependent Claim
147 words
The process of claim 22, wherein the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the residual sulfur trioxide content in the flue gas after it has left the electrostatic precipitator, the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the opacity of the flue gas after it has left the electrostatic precipitator, the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the power consumption of the electrostatic precipitator, and in the step of controlling, the flow rate of ammonia conditioning agent added is dependent upon the opacity of the flue gas, and the flow rate of sulfur trioxide conditioning agent added is dependent upon the power consumption of the electrostatic precipitator and the residual sulfur trioxide.
Claim 26
Dependent Claim
79 words
The process of claim 22, wherein the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the opacity of the flue gas after it has left the electrostatic precipitator, and in the step of controlling, the flow rate of ammonia conditioning agent added is dependent upon the opacity of the flue gas, and the flow rate of sulfur trioxide is determined as a constant times the flow rate of ammonia.
Claim 27
Dependent Claim
134 words
The process of claim 22, wherein the step of sensing the flue gas prior to the addition of the conditioning agent includes the step of measuring the boiler load, the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the residual sulfur content in the flue gas after it has left the electrostatic precipitator, the step of sensing the flue gas after the addition of the conditioning agent includes the step of measuring the power consumption of the electrostatic precipitator, and in the step of controlling, the total flow rate of conditioning agents is dependent upon the boiler load signal, and the flow rate of sulfur trioxide conditioning agent added is dependent upon the power consumption of the electrostatic precipitator and the residual sulfur trioxide.
Claim 28
Dependent Claim
16 words
The process of claim 16, wherein at least one of the conditioning agents is added intermittently.
Claim 29
Dependent Claim
15 words
The process of claim 26, wherein the conditioning agent that is added intermittently is ammonia.
Claim 30
Dependent Claim
162 words
A process for controlling the addition of conditioning agents to a stream of a flue gas containing particulate matter, comprising the steps of: adding at least two conditioning agents, which chemically interact with the particulate matter in the flue gas and with each other, to the flue gas stream at a location after the flue gas has left a boiler; sensing the flue gas prior to the addition of the conditioning agents, and providing a feedforward signal indicative of the mass flow rate of particulate matter in the flue gas; sensing the flue gas after addition of the conditioning agents, and providing a feedback signal indicative of the physiochemical effect on the flue gas/particulate stream of the addition of the conditioning agents; and controlling the amounts of the conditioning agents added to the flue gas by establishing the total flow of the conditioning agents responsive to the feedforward signal, and establishing the ratio of the conditioning agents responsive to the feedback signal.
Claim 31
Dependent Claim
162 words
A process for controlling the addition of conditioning agents to a stream of a flue gas containing particulate matter, comprising the steps of: adding at least two conditioning agents, which chemically interact with the particulate matter in the flue gas and with each other, to the flue gas stream at a location after the flue gas has left a boiler; sensing the flue gas prior to the addition of the conditioning agents, and providing a feedforward signal indicative of the mass flow rate of particulate matter in the flue gas; sensing the flue gas after addition of the conditioning agents, and providing a feedback signal indicative of the physiochemical effect on the flue gas/particulate stream of the addition of the conditioning agents; and controlling the amounts of the conditioning agents added to the flue gas by establishing the total flow of the conditioning agents responsive to the feedforward signal, and establishing the ratio of the conditioning agents responsive to the feedback signal.
Claim 32
Dependent Claim
14 words
The process of claim 28, wherein the conditioning agents are sulfur trioxide and ammonia.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-07-08 | 1995-01-07 | 1995-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-08 | 1999-01-07 | 1999-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-08 | 2003-01-07 | 2003-07-09 | $7700.00 | Window Closed / Lapsed |