AMMONIA-ADDING SYSTEM FOR AMMONIA-BASED DESULFURIZATION DEVICE

• US 20180361308A1
• Filed: 04/16/2018
• Published: 12/20/2018
• 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, Jingyong, Zhang, Jun
• Granted Patent: US 10,159,929 B1
• Time in Patent Office: 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:

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; 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 sulfur dioxide concentration at an outlet of the desulfurization system; and

set the correction coefficient to a different value in response to the sulfur dioxide concentration.

27. 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.

28. The apparatus of claim 27 wherein the auxiliary valve is further configured to change its rate of dispensing ammonia based on the measure of the output sulfur dioxide characteristic.

29. The apparatus of claim 28 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.

30. The apparatus of claim 29 wherein:

the valves configured to add ammonia includes;

the main valve being configured to;

pass ammonia; and

be controlled with coarse control; and

the valves configured to control ammonia addition includes;

the auxiliary valve being configured to;

pass ammonia; and

be controlled with fine control.

40. 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.

41. The apparatus of claim 40 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 sa lfaar dioxide removal rate and the correction coefficient; and

no more than 110% of the product.

42. The apparatus of claim 41 wherein:

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

the ammonia stoichiometrically required is;

43. The apparatus of claim 42 wherein the gas amount corresponding to the inlet of the desulfurization system is received from an inlet continuous electronic monitoring instrument.

44. The apparatus of claim 42 wherein the SO₂ concentration at the inlet of the desulfurization system is received from an inlet continuous electronic monitoring instrument.

45. The apparatus of claim 42 wherein the gas amount corresponding to the outlet of the desulfurization system is received from an outlet continuous electronic monitoring instrument.

47. The apparatus of claim 30 further configured to:

measure at least one of;

a gas amount corresponding to an 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.

48. The apparatus of claim 47 wherein the other one is subject to a gas amount correction calculation based, at least partly, on a gas flow characteristic.

49. The apparatus of claim 48 wherein the flow characteristic is temperature.

50. The apparatus of claim 48 wherein the flow characteristic is pressure.

51. The apparatus of claim 48 wherein the flow characteristic is water content.

2-26. -26. (canceled)

31-39. -39. (canceled)

46. (canceled)

52. (canceled)

53. 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; 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 (“

DCS”

) configured to calculate an amount of required ammonia;

wherein the DCS uses a processor to calculate the amount, the processor configured to calculate the amount based on;

characteristics of gases associated with 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.

54. The apparatus of claim 53 wherein the characteristics include boiler activity characteristics from a boiler with which the desulfurization system is operated.

55. The apparatus of claim 54 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.

56. The apparatus of claim 55 wherein the auxiliary valve is further configured to change its rate of dispensing ammonia based on the measure of the output sulfur dioxide characteristic.

57. The apparatus of claim 56 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.

58. The apparatus of claim 57 wherein:

the valves configured to add ammonia includes;

the main valve being configured to;

pass ammonia; and

be controlled with coarse control; and

the valves configured to control ammonia addition includes;

the auxiliary valve being configured to;

pass ammonia; and

be controlled with fine control.

59. 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; 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 (“

DCS”

) configured to calculate an amount of required ammonia;

wherein the DCS uses a processor to calculate the amount, 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.

60. The apparatus of claim 59 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.

61. The apparatus of claim 60 wherein the auxiliary valve is further configured to change its rate of dispensing ammonia based on the measure of the output sulfur dioxide characteristic.

62. The apparatus of claim 61 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.

63. The apparatus of claim 61 wherein:

the valves configured to add ammonia includes;

the main valve being configured to;

pass ammonia; and

be controlled with coarse control; and

the valves configured to control ammonia addition includes;

the auxiliary valve being configured to;

pass ammonia; and

be controlled with fine control.

64. 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 steam generation rate from a boiler that produces the flue gas; and

calculate an amount of required ammonia based, at least partly, on the steam generation rate,

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

65. The apparatus of claim 64 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.

66. The apparatus of claim 65 wherein the auxiliary valve is further configured to change its rate of dispensing ammonia based on the measure of the output sulfur dioxide characteristic.