Ammonia-adding system for ammonia-based desulfurization device

• US 10,589,212 B2
• Filed: 04/08/2019
• Issued: 03/17/2020
• Est. Priority Date: 06/14/2017
• Status: Active Grant

• Current Assignee: Jiangnan Environmental Protection Group Inc.
• Original Assignee: Jiangnan Environmental Protection Group Inc.
• Inventors: Luo, Jing, Wang, Jinyong, Zhang, Jun
• Primary Examiner(s): Holecek, Cabrena
• Application Number:
  US16/377,497
• Publication Number:
  US 20190232214A1
• Time in Patent Office: 344 Days
• CPC Class Codes: B01D 2252/102 Ammonia
• CPC Class Codes: B01D 2252/103 Water
• CPC Class Codes: B01D 53/1412 Controlling the absorption process
• CPC Class Codes: B01D 53/1481 Removing sulfur dioxide or sulfur trioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/346 Controlling the process
• CPC Class Codes: B01D 53/50 Sulfur oxides B01D53/60 takes precedence
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

Ammonia-adding apparatus and methods for ammonia-based desulfurization use multi-stage control, calculate a theoretical amount of ammonia based on gas amounts provided by an inlet continuous emission monitoring system (CEMS) and an outlet CEMS of the ammonia-based desulfurization device or associated gas amounts, a SO₂ concentration provided by the inlet CEMS, and a predetermined SO₂ concentration of the outlet CEMS. The apparatus and methods calculate a corrected theoretical amount of ammonia using half of the ratio of the actual amount of added ammonia to the actual amount of removed sulfur dioxide as a correction coefficient for the theoretical amount of ammonia; add an ammonia absorbent equivalent to the corrected theoretical amount of ammonia to the ammonia-based desulfurization device through an ammonia metering means and an ammonia control valve, and automatically control the actual ammonia flow rate based on the actual SO₂ concentration and a change trend provided by the outlet CEMS.

Claims

1. Apparatus for adding ammonia to an absorption solution in a flue-gas desulfurization system, the apparatus comprising:

adding an emission monitoring system configured to provide a measure of an output sulfur dioxide characteristic;

valves configured to;

add ammonia to the absorption solution at a base rate that is proportional to;

a) a target sulfur dioxide removal rate defined as a difference between;

1) a product of;

 

a gas flow rate corresponding to an inlet of the desulfurization system and an inlet SO₂ concentration; and

2) a product of;

 

a gas flow rate corresponding to an outlet of the desulfurization system and a predetermined SO₂ outlet concentration; and

b) a correction coefficient that includes a ratio of cumulative ammonia added to cumulative sulfur dioxide removed; and

,

then, control ammonia addition to the absorption solution to a second rate based on the measure of the output sulfur dioxide characteristic; and

a distributed control system configured to;

receive a flue gas inlet flow rate corresponding to the inlet of the desulfurization system; and

calculate an amount of required ammonia based, at least partly, on the flue gas inlet flow rate,

wherein the gas flow rate corresponding to the inlet is evaluated as the flue gas inlet flow rate.

2. The apparatus of claim 1 wherein the valves include a main ammonia dispensing valve and an auxiliary ammonia dispensing valve, the auxiliary valve configured to dispense ammonia at a rate that is the base rate minus a rate at which ammonia is dispensed through the main valve.

3. The apparatus of claim 2 wherein the auxiliary valve is further configured to change its rate of dispensing ammonia based on the measure of the output sulfur dioxide characteristic.

4. The apparatus of claim 3 wherein:

the measure of the sulfur dioxide characteristic is a rate of change of sulfur dioxide emission rate at the outlet of the desulfurization system; and

the auxiliary valve is further configured to change its rate based on a predefined relationship between;

the rate of change of sulfur dioxide emission at the outlet; and

a fine adjustment value.

5. The apparatus of claim 4 wherein:

the valves being configured to add ammonia includes;

the main valve being configured to;

pass ammonia; and

be controlled with coarse control; and

the valves being configured to control ammonia addition includes;

the auxiliary valve being configured to;

pass ammonia; and

be controlled with fine control.

6. The apparatus of claim 1 wherein the correction coefficient is defined as:

one half of;

a ratio of actual molar number of added ammonia to actual molar number of removed sulfur dioxide.

7. The apparatus of claim 6 wherein the valves are further configured to regulate the base rate to be:

no less than 90% of a product of;

ammonia stoichiometrically required by the target sulfur dioxide removal rate; and

the correction coefficient; and

no more than 110% of the product.

8. The apparatus of claim 7 wherein:

the target sulfur dioxide removal rate depends on a predetermined outlet sulfur dioxide concentration; and

the ammonia stoichiometrically required is;

9. The apparatus of claim 8 wherein:

the gas amount corresponding to the inlet of the desulfurization system is received from an inlet continuous electronic monitoring instrument; and

the SO₂ concentration at the inlet of the desulfurization system is received from an inlet continuous electronic monitoring instrument.

10. The apparatus of claim 8, wherein the gas amount corresponding to the outlet of the desulfurization system is received from an outlet continuous electronic monitoring instrument.

11. The apparatus of claim 1 wherein the flue gas inlet flow rate is received from an inlet continuous emission monitoring system.

12. The apparatus of claim 1 wherein the distributed control system uses a processor to calculate the amount of required ammonia, the processor configured to calculate the amount based on:

characteristics of flue gas, the characteristics provided by an inlet continuous emission monitoring system (“

CEMS”

) and an outlet CEMS of the desulfurization system;

an SO2 concentration provided by the inlet CEMS; and

a predetermined SO2 concentration of the outlet CEMS.

13. The apparatus of claim 1 further configured to measure the flue gas inlet flow rate.

14. The apparatus of claim 1 further configured to:

measure at least one of;

a gas amount corresponding to the inlet of the desulfurization system; and

a gas amount corresponding to the outlet of the desulfurization system; and

substitute the at least one measured one of the gas amount corresponding to the inlet and the gas amount corresponding to the outlet for the other one of the gas amount corresponding to the inlet and the gas amount corresponding to the outlet.

15. The apparatus of claim 14 wherein the other one is subject to a gas amount correction calculation based, at least partly, on a gas flow characteristic.

16. Apparatus for adding ammonia to an absorption solution in a flue-gas desulfurization system, the apparatus comprising:

an emission monitoring system configured to provide a measure of an output sulfur dioxide characteristic;

valves configured to;

add ammonia to the absorption solution at a base rate that is proportional to;

a) a target sulfur dioxide removal rate defined as a difference between;

1) a product of;

 

a gas flow rate corresponding to an inlet of the desulfurization system and an inlet SO₂ concentration; and

2) a product of;

 

a gas flow rate corresponding to an outlet of the desulfurization system and a predetermined SO₂ outlet concentration; and

b) a correction coefficient that includes a ratio of cumulative ammonia added to cumulative sulfur dioxide removed; and

,

then, control ammonia addition to the absorption solution to a second rate based on the measure of the output sulfur dioxide characteristic; and

a distributed control system configured to;

receive a flue gas outlet flow rate corresponding to the outlet of the desulfurization system; and

calculate an amount of required ammonia based, at least partly, on the flue gas outlet flow rate,

wherein the gas flow rate corresponding to the outlet is evaluated as the flue gas outlet flow rate.

17. The apparatus of claim 16 wherein the valves include a main ammonia dispensing valve and an auxiliary ammonia dispensing valve, the auxiliary valve configured to dispense ammonia at a rate that is the base rate minus a rate at which ammonia is dispensed through the main valve.

18. The apparatus of claim 17 wherein the auxiliary valve is further configured to change its rate of dispensing ammonia based on the measure of the output sulfur dioxide characteristic.

19. The apparatus of claim 18 wherein:

the measure of the sulfur dioxide characteristic is a rate of change of sulfur dioxide emission rate at the outlet of the desulfurization system; and

the auxiliary valve is further configured to change its rate based on a predefined relationship between;

the rate of change of sulfur dioxide emission at the outlet; and

a fine adjustment value.

20. The apparatus of claim 19 wherein:

the valves being configured to add ammonia includes;

the main valve being configured to;

pass ammonia; and

be controlled with coarse control; and

the valves being configured to control ammonia addition includes;

the auxiliary valve being configured to;

pass ammonia; and

be controlled with fine control.

21. The apparatus of claim 16 wherein the correction coefficient is defined as:

one half of;

a ratio of actual molar number of added ammonia to actual molar number of removed sulfur dioxide.

22. The apparatus of claim 21 wherein the valves are further configured to regulate the base rate to be:

no less than 90% of a product of;

ammonia stoichiometrically required by the target sulfur dioxide removal rate; and

the correction coefficient; and

no more than 110% of the product.

23. The apparatus of claim 22 wherein:

the target sulfur dioxide removal rate depends on a predetermined outlet sulfur dioxide concentration; and

the ammonia stoichiometrically required is;

24. The apparatus of claim 23 wherein:

the gas amount corresponding to the inlet of the desulfurization system is received from an inlet continuous electronic monitoring instrument; and

the SO₂ concentration at the inlet of the desulfurization system is received from an inlet continuous electronic monitoring instrument.

25. The apparatus of claim 23 wherein the gas amount corresponding to the outlet of the desulfurization system is received from an outlet continuous electronic monitoring instrument.

26. The apparatus of claim 16 wherein the flue gas outlet flow rate is received from an outlet continuous emission monitoring system.

27. The apparatus of claim 16 wherein the distributed control system uses a processor to calculate the amount of required ammonia, the processor configured to calculate the amount based on:

characteristics of flue gas, the characteristics provided by an inlet continuous emission monitoring system (“

CEMS”

) and an outlet CEMS of the desulfurization system;

an SO2 concentration provided by the inlet CEMS; and

a predetermined SO2 concentration of the outlet CEMS.

28. The apparatus of claim 16 further configured to measure the flue gas outlet flow rate.

29. The apparatus of claim 16 further configured to:

measure at least one of;

a gas amount corresponding to the inlet of the desulfurization system; and

a gas amount corresponding to the outlet of the desulfurization system; and

substitute the at least one measured one of the gas amount corresponding to the inlet and the gas amount corresponding to the outlet for the other one of the gas amount corresponding to the inlet and the gas amount corresponding to the outlet.

30. The apparatus of claim 29 wherein the other one is subject to a gas amount correction calculation based, at least partly, on a gas flow characteristic.