Energy-saving type desulfurization and oxidation air system

Abstract

The utility model discloses an energy-saving type desulfurization oxidation air system which comprises a fan unit composed of a plurality of fans arranged in parallel, an oxidation air pipe, a central controller and a parameter monitoring instrument set, and each fan is provided with a frequency converter. An air supply outlet of each fan of the fan unit is connected with an air inlet of the oxidation air pipe through a pipeline; the parameter monitoring instrument group comprises an inlet flue gas flowmeter and an inlet sulfur dioxide concentration meter which are arranged at a flue gas inlet of the desulfurizing absorption tower, and an outlet sulfur dioxide concentration meter arranged at a flue gas outlet of the desulfurizing absorption tower; and the parameter monitoring instrument group, the fan and the frequency converter are electrically connected with the central controller. According to the method, the operation parameters of the desulfurization system can be effectively monitored, the air volume of the oxidation air can be accurately controlled, the desulfurization system can operate well and stably, and the energy consumption can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of desulfurization equipment, and in particular to an energy-saving desulfurization oxidation air system. Background Art

[0002] At present, most coal-fired power units in my country use wet desulfurization technology. Limestone wet desulfurization technology is relatively mature, with the characteristics of low cost and good effect. Limestone wet desulfurization technology is a desulfurization process that uses lime or limestone slurry to absorb sulfur dioxide in flue gas in an absorption tower to obtain a mixture of calcium sulfite and calcium sulfate, then introduces air to oxidize calcium sulfite, and finally refines the obtained calcium sulfate into (gypsum).

[0003] As my country attaches great importance to environmental protection issues, the installed capacity of new energy power generation such as photovoltaic and wind power has continued to increase in recent years, and the entire power industry has undergone tremendous changes. At present, many power plants in my country's power industry have the situation of parallel new energy power generation and coal-fired power generation. These power plants mainly use new energy power generation, and increase coal-fired power generation as a supplement during peak periods. This industry situation has led to large fluctuations in the power generation load of the coal-fired power units of the above-mentioned power plants, and they have been operating at a lower load for a long time.

[0004] The limestone wet desulfurization system has high energy consumption, generally accounting for about 2% of the high-load power generation of coal-fired power units. The existing desulfurization systems of coal-fired power units mostly adopt standardized designs and build systems based on full power generation load. When coal-fired units operate at low load for a long time, it will lead to a large waste of energy.

[0005] At present, the existing technology mainly reduces energy consumption and achieves the purpose of energy saving and consumption reduction by transforming the desulfurization oxidation air system of the desulfurization system. There are two main transformation methods: the first is to replace the Roots blower with a frequency conversion function, and set up a sulfite detection instrument in the absorption tower. According to the power generation load and sulfite detection data, the fan flow is adjusted by frequency conversion to achieve consumption reduction; the second is to replace the existing high-power blower with a unit composed of multiple parallel low-power blowers. According to the power generation load, all or part of the blowers are selected to achieve consumption reduction.

[0006] Although the above-mentioned transformation methods can reduce the energy consumption of the desulfurization system to varying degrees, they cannot accurately control the delivery rate of the oxidizing air. During actual operation, the sulfite concentration in the slurry is difficult to control at a low level, and the desulfurization efficiency of the system also fluctuates greatly. Summary of the invention

[0007] In order to solve at least one of the above technical problems, an oxidation air system is developed that can effectively monitor the operating parameters of the desulfurization system, accurately control the air volume of the oxidation air, enable the desulfurization system to operate better and more stably, and effectively reduce energy consumption. The present application provides an energy-saving desulfurization oxidation air system.

[0008] The present application provides an energy-saving desulfurization oxidation air system, which includes a fan unit composed of multiple fans arranged in parallel, each of which is equipped with a frequency converter, and also includes an oxidation air duct, a central controller and a parameter monitoring instrument group; the air supply outlets of each fan of the fan unit are connected to the air inlet of the oxidation air duct through pipelines; the parameter monitoring instrument group includes an inlet flue gas flow meter and an inlet sulfur dioxide concentration meter arranged at the flue gas inlet of the desulfurization absorption tower, and an outlet sulfur dioxide concentration meter arranged at the flue gas outlet of the desulfurization absorption tower; the inlet flue gas flow meter, the inlet sulfur dioxide concentration meter and the outlet sulfur dioxide concentration meter, as well as the fan and the frequency converter, are all electrically connected to the central controller; the central controller controls the opening and closing of the fan and the frequency converter through the detection data of the inlet flue gas flow meter, the inlet sulfur dioxide concentration meter and the outlet sulfur dioxide concentration meter, thereby controlling the air supply volume of the fan unit.

[0009] Optionally, the parameter monitoring instrument group further includes a sulfite analyzer disposed in the absorption tower, and the sulfite analyzer is also electrically connected to the central controller.

[0010] Optionally, the fan unit is configured with 2 to 3 fans.

[0011] Optionally, the oxidation air duct is an annular tube provided with a plurality of nozzles.

[0012] Further optionally, the spacing between adjacent nozzles of the oxidation air duct is 300~600mm.

[0013] Optionally, the oxidation air duct adopts a mesh pipe structure, including a main pipe and branch pipes, the branch pipes are arranged in parallel and vertically connected to the main pipe; the air inlet is arranged on the main pipe, and a plurality of nozzles are arranged on the branch pipe.

[0014] Further optionally, the spacing between adjacent branch pipes is 300-600 mm.

[0015] Further optionally, the spacing between adjacent nozzles on the branch pipe is 300-600 mm.

[0016] Optionally, a plurality of sulfite analyzers are provided, which are evenly distributed in the area below the liquid level in the absorption tower.

[0017] Optionally, a plurality of inlet sulfur dioxide concentration meters are provided and evenly distributed at the flue gas inlet of the absorption tower.

[0018] In summary, the present invention includes at least one of the following beneficial technical effects:

[0019] 1. This application adopts a fan unit consisting of multiple fans connected in parallel as the air supply equipment of the oxidation air system, and each fan is equipped with a frequency converter, which can effectively improve the flexibility of controlling the air supply equipment. The number of fans to be turned on can be selected as needed, and the air volume of a single fan can be controlled by the frequency converter, which can achieve precise control of the air volume within a large range.

[0020] 2. The present application sets up a parameter monitoring instrument group, including an inlet flue gas flow meter and an inlet sulfur dioxide concentration meter arranged at the flue gas inlet of the desulfurization absorption tower, and an outlet sulfur dioxide concentration meter arranged at the flue gas outlet of the desulfurization absorption tower. The air volume required for theoretical oxidation can be calculated by the above parameters, and then the air volume required for actual oxidation can be calculated based on the calculation result, which can accurately control the oxidation air volume, thereby ensuring the normal and stable operation of the desulfurization system.

[0021] 3. The energy-saving desulfurization oxidation air system of the present application can accurately adjust the air supply volume of the oxidation air according to the power generation load of the coal-fired power unit, which can greatly reduce the operating energy consumption of the desulfurization system and reduce the system operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the energy-saving desulfurization oxidation air system for this application;

[0023] Figure 2 This is a schematic diagram of the control flow of the control part of the energy-saving desulfurization oxidation air system of this application;

[0024] Figure 3 This is a schematic diagram of the structure of the oxidation air duct of Example 1 of the present application;

[0025] Figure 4 This is a schematic diagram of the structure of the oxidation air duct of Example 2 of the present application;

[0026] In the figure: 1. Frequency converter; 2. Fan; 3. Oxidation air duct; 4. Slurry tank; 5. Slurry delivery pump; 6. Absorption tower; 61. Flue gas inlet; 62. Flue gas outlet; 7. Slurry circulation pump; 8. Slurry spray pipe; 9. Gypsum discharge pump; 10. Demister; 11. Inlet flue gas flow meter; 12. Inlet sulfur dioxide concentration meter; 13. Outlet sulfur dioxide concentration meter; 14. Sulfite analyzer. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0028] The present application designs an energy-saving desulfurization oxidation air system, which includes a fan unit composed of multiple fans 2 arranged in parallel, and each fan 2 is equipped with a frequency converter 1. By controlling the frequency converter 1, the speed of the fan 2 can be adjusted, thereby changing the operating power and output air volume of the fan 2.

[0029] The energy-saving desulfurization oxidation air system of the present application also includes an oxidation air duct 3, a central controller (not shown in the figure) and a parameter monitoring instrument group. The air supply ports of each fan 2 of the fan unit are connected to the air inlet of the oxidation air duct 3 through a pipeline. The parameter monitoring instrument group includes an inlet flue gas flow meter 11 and an inlet sulfur dioxide concentration meter 12 arranged at the flue gas inlet 61 of the desulfurization absorption tower 6, and an outlet sulfur dioxide concentration meter 13 arranged at the flue gas outlet 62 of the desulfurization absorption tower 6. The inlet flue gas flow meter 11, the inlet sulfur dioxide concentration meter 12 and the outlet sulfur dioxide concentration meter 13, as well as the fan 2 and the inverter 1, are all electrically connected to the central controller.

[0030] The central controller controls the opening and closing of the fan 2 and the frequency converter 1 through the detection data of the inlet flue gas flow meter 11, the inlet sulfur dioxide concentration meter 12 and the outlet sulfur dioxide concentration meter 13, thereby controlling the air supply volume of the fan unit.

[0031] The central controller of the present application may be a control computer, or various functional control chips available on the market.

[0032] The control principle of the present application is to calculate the relatively accurate air volume actually required for oxidation through a formula combined with detection data, and then control the inverter 1 and the opening and closing of the fan 2 to adjust the air supply volume to be consistent with the calculated air volume.

[0033] This application takes the desulfurization efficiency that needs to be achieved as the standard, and the theoretical oxidation air volume can be calculated using the following formula:

[0034] M (g / h) = Q 烟 (Nm 3 / h)×N SO2 (g / m 3 )×a (where M is the flow rate of SO2 to be removed, Q 烟 is the flue gas flow rate, N SO2 is the concentration of SO2 in the inlet flue gas, a is the desulfurization efficiency);

[0035] Q 空 (Nm 3 / h) = ((M / 128) × 22.4 × 10 -3 ) / 0.21 (where Q 空 is the air volume required for theoretical oxidation).

[0036] In the above calculation formula, the oxygen content in the air is set to 21%, the molar volume of oxygen is set to 22.4L / mol, the molecular weight of SO2 is set to 64g / mol, and the desulfurization efficiency can be determined according to the equipment operating parameters of different power plants.

[0037] The actual oxidation air volume of this application can be calculated using the following formula:

[0038] Q(Nm 3 / h)=Q 空 (Nm 3 / h)×θ (where Q is the air volume required for actual oxidation and θ is the supersaturation multiple).

[0039] According to the actual operating conditions, the applicant has conducted repeated experiments and found that when the oxidation air system of the present application is used, the air volume of air actually required for oxidation is 2 to 3 times the air volume of air theoretically required for oxidation, which can ensure the oxidation demand in the absorption tower and meet the operating standards of most desulfurization equipment. That is, the air volume of air actually required for oxidation is 2 to 3 times the air volume of air theoretically required for oxidation, which can be adjusted according to the actual equipment conditions.

[0040] According to the above calculation formula, the central controller of the present application can calculate the actual air volume required for oxidation according to the parameters measured by the parameter monitoring instrument group.

[0041] In order to more accurately obtain the actual air volume required for oxidation, the parameter monitoring instrument group of the present application may also include a sulfite analyzer 14 disposed in the absorption tower 6, and the sulfite analyzer 14 is also electrically connected to the central controller.

[0042] The sulfite analyzer 14 of the present application is arranged in the area below the liquid level line in the absorption tower 6 to detect the concentration data of sulfite. In order to make the detection result more accurate, multiple sulfite analyzers 14 can be set, evenly distributed in the area below the liquid level in the absorption tower 6.

[0043] In specific implementation, the supersaturation multiple θ can be adjusted within a set range according to the control standard of sulfite concentration set by each power plant and the difference between the detected sulfite concentration data and the control standard, thereby more accurately calculating the actual air volume required for oxidation.

[0044] In view of the comprehensive equipment cost and the adjustment requirements of the present application, it is appropriate to configure 2 to 3 fans 2 of the fan unit.

[0045] The following are examples of the present application: Example

[0046] The energy-saving desulfurization oxidation air system of this embodiment has three fans 2 of the fan unit, and no sulfite analyzer 14 is provided.

[0047] The oxidation air duct 3 of this embodiment is an annular tube, provided with a plurality of nozzles, and the spacing between adjacent nozzles is 500 mm.

[0048] This embodiment is configured in a coal-fired unit of a power plant to calculate the energy saving rate.

[0049] The specific parameters of the power plant unit are as follows: 640MW supercritical coal-fired unit, equipped with electrostatic precipitator and standard limestone wet desulfurization device, the sulfur content of the coal used is about 1.0%, the desulfurization efficiency is set at 98.6%, and the outlet SO2 concentration is less than 35mg / m 3 .

[0050] According to the parameters of the unit and the standard limestone wet desulfurization device supporting the unit, the equipment parameters of the energy-saving desulfurization oxidation air system of this embodiment are designed. The rated air volume of fan 2 is 8000m 3 3 fans with a capacity of / h and 1 frequency converter.

[0051] The unit equipped with the energy-saving desulfurization oxidation wind system of this embodiment and another standard unit with the same parameters were started up and operated for 9 days, and operated for 3 days at 50% power generation load, 70% power generation load and 100% power generation load, and then the energy consumption of the oxidation wind system was compared.

[0052] By comparison, the energy consumption of the oxidation air system of the unit using the energy-saving desulfurization oxidation air system of the present application is reduced by more than 20%.

[0053] The concentration of calcium sulfite in the desulfurization slurry of the two units was tested by sampling. The calcium sulfite concentration of the unit using the system of this embodiment was within 0.49%, while the calcium sulfite concentration of the other unit was 1.02%. It can be seen that the oxidation effect of this system is better. Example

[0054] The energy-saving desulfurization oxidation air system of this embodiment has two fans 2 of the fan unit, and is provided with four sulfite analyzers 14 , which are evenly distributed in the area below the liquid level line in the desulfurization absorption tower 6 .

[0055] In this embodiment, three inlet sulfur dioxide concentration meters 12 are provided, which are evenly distributed at the flue gas inlet 61 of the absorption tower 6. The measured inlet sulfur dioxide concentration is averaged to improve the measurement accuracy.

[0056] The oxidation air duct 3 of this embodiment adopts a mesh pipe structure, including a main pipe and a branch pipe, the branch pipes are arranged in parallel and vertically connected to the main pipe, the air inlet is set on the main pipe, and the branch pipe is provided with a plurality of nozzles. The spacing between adjacent branch pipes is 400mm; on the branch pipe, the spacing between adjacent nozzles is 450mm.

[0057] This embodiment is configured in a coal-fired unit of a power plant to calculate the energy saving rate.

[0058] The specific parameters of the power plant unit are as follows: 640MW supercritical coal-fired unit, equipped with electrostatic precipitator and standard limestone wet desulfurization device, the sulfur content of the coal used is about 1.0%, the desulfurization efficiency is set at 98.6%, and the outlet SO2 concentration is less than 35mg / m 3 .

[0059] According to the parameters of the unit and the standard limestone wet desulfurization device supporting the unit, the equipment parameters of the energy-saving desulfurization oxidation air system of this embodiment are designed. The rated air volume of fan 2 is 8000m 3 2 fans with a capacity of / h, equipped with 1 frequency converter.

[0060] The unit equipped with the energy-saving desulfurization oxidation wind system of this embodiment and another standard unit with the same parameters were started up and operated for 9 days, and operated for 3 days at 50% power generation load, 70% power generation load and 100% power generation load, and then the energy consumption of the oxidation wind system was compared.

[0061] By comparison, the energy consumption of the oxidation air system of the unit using the energy-saving desulfurization oxidation air system of the present application is reduced by more than 24%, and the concentration of calcium sulfite in the desulfurization slurry can be stably maintained within 0.5%.

[0062] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An energy-saving desulfurization oxidation air system, characterized in that: The oxidation air system comprises a fan unit consisting of a plurality of fans (2) arranged in parallel, each of the fans (2) being equipped with a frequency converter (1), and also comprising an oxidation air duct (3), a central controller and a parameter monitoring instrument group; the air supply ports of the fans (2) of the fan unit are connected to the air inlet of the oxidation air duct (3) via a pipeline; the parameter monitoring instrument group comprises an inlet flue gas flow meter (11) and an inlet sulfur dioxide concentration meter (12) arranged at the flue gas inlet (61) of the desulfurization absorption tower (6), and a central controller (13) arranged at the flue gas inlet (61) of the desulfurization absorption tower (6). 6) at the flue gas outlet (62); the inlet flue gas flow meter (11), the inlet sulfur dioxide concentration meter (12) and the outlet sulfur dioxide concentration meter (13), as well as the fan (2) and the inverter (1), are all electrically connected to the central controller; the central controller controls the opening and closing of the fan (2) and the inverter (1) through the detection data of the inlet flue gas flow meter (11), the inlet sulfur dioxide concentration meter (12) and the outlet sulfur dioxide concentration meter (13), thereby controlling the air supply volume of the fan unit.

2. The energy-saving desulfurization oxidation air system according to claim 1 is characterized in that: The parameter monitoring instrument group further comprises a sulfite analyzer (14) arranged in the absorption tower (6); the sulfite analyzer (14) is also electrically connected to the central controller.

3. The energy-saving desulfurization oxidation air system according to claim 1 is characterized in that: The fan unit is equipped with 2 to 3 fans (2).

4. The energy-saving desulfurization oxidation air system according to claim 1 is characterized in that: The oxidation air duct (3) is an annular tube and is provided with a plurality of nozzles.

5. The energy-saving desulfurization oxidation air system according to claim 4 is characterized in that: The spacing between adjacent nozzles of the oxidation air duct (3) is 300-600 mm.

6. The energy-saving desulfurization oxidation air system according to claim 1 is characterized in that: The oxidation air duct (3) adopts a mesh pipe structure, comprising a main pipe and branch pipes, wherein the branch pipes are arranged in parallel and vertically connected to the main pipe; the air inlet is arranged on the main pipe, and a plurality of nozzles are arranged on the branch pipe.

7. The energy-saving desulfurization oxidation air system according to claim 6 is characterized in that: The spacing between adjacent branch pipes is 300-600 mm.

8. The energy-saving desulfurization oxidation air system according to claim 7 is characterized in that: On the branch pipe, the spacing between adjacent nozzles is 300-600 mm.

9. The energy-saving desulfurization oxidation air system according to claim 2 is characterized in that: A plurality of sulfite analyzers (14) are provided, which are evenly distributed in the area below the liquid level in the absorption tower (6).

10. The energy-saving desulfurization oxidation air system according to claim 1 is characterized in that: The inlet sulfur dioxide concentration meter (12) is provided in plurality and is evenly distributed at the flue gas inlet (61) of the absorption tower (6).

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