Apparatus and method for controlling concentration of oxygen in heating furnace

Patent metadata

Field	Value
Publication number	US-11187463-B2
Application number	US-201716470732-A
Country	US
Kind code	B2
Filing date	Dec 20, 2017
Priority date	Dec 20, 2016
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

An apparatus for controlling the concentration of oxygen in a heating furnace according to one embodiment of the present invention may comprise: a first oxygen concentration bias setting unit for receiving a set first oxygen concentration bias; a second oxygen concentration bias calculation unit for, when a measured value of carbon monoxide in exhaust gas is out of an allowable carbon monoxide range, calculating a second oxygen concentration bias by using the measured value of carbon monoxide and the concentration of oxygen measured in the exhaust gas; an oxygen concentration bias providing unit for providing an oxygen concentration bias by using the first oxygen concentration bias and the second oxygen concentration bias; and an oxygen concentration set value correction unit for correcting a set value of the concentration of oxygen by using the oxygen concentration bias.

First claim

The invention claimed is:

1. An apparatus for controlling oxygen concentration in a heating furnace, the apparatus comprising:
a first oxygen concentration bias setting unit configured to receive a set first oxygen concentration bias;
a second oxygen concentration bias calculation unit configured to, when a measured value of carbon monoxide in exhaust gas is out of an allowable carbon monoxide range, calculate a second oxygen concentration bias based on the measured value of carbon monoxide and the concentration of oxygen measured in the exhaust gas;
an oxygen concentration bias providing unit configured to obtain and provide a third oxygen concentration bias by adding the first oxygen concentration bias and the second oxygen concentration bias; and
an oxygen concentration set value correction unit configured to correct an oxygen concentration set value by adding the third oxygen concentration bias to a predetermined oxygen concentration set value,
wherein the second oxygen concentration calculation unit comprises:
a carbon monoxide determination unit configured to
determine whether the measured value of carbon monoxide is out of the allowable carbon monoxide range;
a carbon monoxide calculation unit configured to calculate a moving average value of the measured value of carbon monoxide;
an oxygen change calculation unit configured to calculate an oxygen concentration change based on the moving average value of the measure value of carbon monoxide and the measured value of oxygen concentration; and
a second oxygen concentration bias calculation unit configured to calculate a second oxygen concentration bias based on the oxygen concentration change, and
the second oxygen concentration calculation unit is configured not to provide a second oxygen concentration bias when the measured value of carbon monoxide is not out of the carbon monoxide allowable range and configured to provide the second oxygen concentration bias when the measured value of carbon monoxide is out of the carbon monoxide allowable range.

2. The apparatus of claim 1 , wherein the carbon monoxide calculation unit is configured to calculate the moving average value of the measured value of carbon monoxide using an equation below,

COpv
,

avg
⁡

(
t
)

=

1

N
+
1

⁢

∑

i
=
t

t
-
N

⁢

⁢

COpv
⁡

(
i
)

where COpv,avg denotes a moving average value of the carbon monoxide measured value, N denotes a positive integer greater than or equal to 1, and t denotes a time variable.

3. The apparatus of claim 1 , wherein the oxygen change calculation unit is configured to calculate the oxygen concentration change using an equation below,

Δ
⁢

⁢

O
2

⁡

(
t
)

=

A
⁢

dO
2

⁢
pv

,
avg

dCOpv
,
avg

⁢
Δ
⁢

⁢

CO
⁡

(
t
)

+
B

where ΔO 2 (t) denotes an oxygen concentration change, A denotes a sensitivity coefficient, dO 2 pv,avg denotes a differential value of moving average of an oxygen concentration measured value, dCOpv,avg denotes a differential value of moving average of the carbon monoxide measured value, ΔCO(t) denotes a change of the carbon monoxide measured value COpv, and B denotes an offset for adjustment.

4. The apparatus of claim 1 , wherein the second oxygen concentration bias calculation unit is configured to calculate the second oxygen concentration bias using an equation below,
O 2_ bias2=O 2 ( t− 1)+ΔO 2 ( t )

where O 2_ bias 2 denotes a second oxygen concentration bias, ΔO 2 (t) denotes an oxygen concentration change at a point of time (t), and O 2 (T−1) denotes oxygen concentration at a point of time (t−1).

5. A method for controlling oxygen concentration of a heating furnace, the method comprising:
receiving a measured value of carbon monoxide in exhaust gas determining whether the measured value of carbon monoxide is out of an allowable carbon monoxide range;
calculating a second oxygen concentration bias based on the measured value of carbon monoxide and a measured value of oxygen concentration in the exhaust gas;
calculating a third oxygen concentration bias by adding the first oxygen concentration bias and the second oxygen concentration bias when the measured value of carbon monoxide is out of the allowable carbon monoxide range;
providing the first oxygen concentration bias as the third oxygen concentration bias when the measured value of carbon monoxide is not out of the allowable carbon monoxide range; and
correcting an oxygen concentration set value by adding the third oxygen concentration bias to a predetermined oxygen concentration set value,
wherein the calculating a second oxygen concentration bias comprises:
calculating a moving average value of the measured value of carbon monoxide;
calculating a carbon monoxide change based on the moving average value of the measured value of carbon monoxide;
calculating an oxygen concentration change based on the moving average value of the measured value of carbon monoxide, the measured value of the oxygen concentration, and the carbon monoxide change; and
calculating a second oxygen concentration bias of the oxygen concentration change.

6. The method of claim 5 , wherein in the calculating a moving av

Assignees

• Posco
• Res Inst Ind Science & Tech

Inventors

• Kim Young-Il

Classifications

• F27D19/00 Primary

  Arrangements of controlling devices · CPC title

• F27D21/04 Primary

  Arrangement of indicators or alarms · CPC title

• F27D2019/0028

  Regulation · CPC title

• F27D2019/0031

  through control of the flow of the exhaust gases · CPC title

• F27D2019/0043

  Amount of air or O2 to the burner · CPC title