CN-121988160-A - Energy-saving optimization device based on double-tower double-circulation desulfurization system and control method thereof

CN121988160ACN 121988160 ACN121988160 ACN 121988160ACN-121988160-A

Abstract

The application relates to the technical field of flue gas purification of coal-fired power plants, in particular to an energy-saving optimization device based on a double-tower double-circulation desulfurization system and a control method thereof. The device comprises a bypass flue, a baffle door module, a unit DCS control module and an SO 2 concentration monitoring module, wherein the inlet end of the bypass flue is connected to the connection position of an outlet flue of a first-stage absorption tower and an inlet flue of a second-stage absorption tower, the outlet end of the bypass flue is connected to the connection position of an outlet flue of the second-stage absorption tower and an inlet flue of a clean chimney, the baffle door module comprises a plurality of baffle doors, the unit DCS control module and the SO 2 concentration monitoring module, and the DCS intelligent control system is respectively and electrically connected with the baffle door module and the unit DCS control module in communication with the SO 2 concentration monitoring module and automatically controls the opening and closing of each baffle door of the baffle door module and the opening and closing of the second-stage absorption tower according to acquired unit load information and SO 2 concentration information. The problems of high energy consumption, increased corrosion and abrasion of equipment, increased maintenance cost and the like caused by forced operation of the secondary absorption tower during low load are effectively solved.

Inventors

QU LITAO
WANG DEXIN
QI XIAOHUI
WANG MINGXUAN
YU HONGHAI
DU JIA
LI CHAO
HE FENGYUAN

Assignees

华电电力科学研究院有限公司

Dates

Publication Date: 20260508
Application Date: 20260330

Claims (10)

1. Energy-conserving optimizing apparatus based on two circulation desulfurization systems of twin tower, two circulation desulfurization systems of twin tower include one-level absorption tower, second grade absorption tower and clean chimney, its characterized in that, energy-conserving optimizing apparatus includes: The inlet end of the bypass flue is connected to the connection position of the outlet flue of the primary absorption tower and the inlet flue of the secondary absorption tower, and the outlet end of the bypass flue is connected to the connection position of the outlet flue of the secondary absorption tower and the inlet flue of the clean chimney; the baffle door module comprises a plurality of baffle doors which are respectively arranged at the inlet end side of the bypass flue, the inlet flue and the outlet flue of the secondary absorption tower and the inlet flue of the clean chimney and used for realizing the on-off of each flue; the unit DCS control module is used for monitoring the load condition of the unit; The SO 2 concentration monitoring module is used for monitoring the concentration of the inlet SO 2 and the concentration of the outlet SO 2 ; And the DCS intelligent control system is respectively and electrically connected with the baffle door module, the unit DCS control module and the SO 2 concentration monitoring module, and is used for automatically controlling the opening and closing of each baffle door of the baffle door module and the start and stop of the secondary absorption tower according to the acquired unit load information and SO 2 concentration information.
2. The energy saving optimizing device according to claim 1, wherein, The inner diameter of the bypass flue is consistent with the inner diameter of the outlet flue of the primary absorption tower and the inner diameter of the inlet flue and the outlet flue of the secondary absorption tower, and/or The bypass flue adopts a carbon steel lining flake resin flue, the inner wall of the bypass flue adopts vinyl ester flake resin material for lining corrosion prevention, the thickness of the lining is 2.0 mm-4.0 mm, and/or The inside of bypass flue is provided with the guide plate, its and the axis contained angle of bypass flue is 15~ 30.
3. The energy saving optimizing device according to claim 1, wherein, The baffle door module further comprises a plurality of independent sealing fans, the gas distribution bag is communicated with the sealing cavities of the baffle doors through stainless steel pipelines respectively and used for providing sealing media for the baffle door modules so as to form positive pressure sealing for isolating smoke leakage, and each sealing cavity is provided with a pressure transmitter for monitoring wind pressure in real time.
4. The energy saving optimizing device according to claim 1 or 3, wherein, The baffle door adopts a double-seal shutter type baffle door, and a nitrile rubber strip is inlaid on a sealing surface.
5. The energy saving optimizing device according to claim 1, wherein, The SO 2 concentration monitoring module comprises an inlet SO 2 analyzer which is respectively arranged at an inlet flue of the primary absorption tower and an outlet SO 2 analyzer which is arranged at an inlet flue of the clean chimney.
6. An energy-saving optimization control method based on a double-tower double-circulation desulfurization system, which is characterized by being applied to the energy-saving optimization device based on the double-tower double-circulation desulfurization system as claimed in any one of claims 1 to 5, and comprising the following steps: S10, data acquisition, namely acquiring unit load condition information in real time through a unit DCS control module, and acquiring the inlet SO 2 concentration of an inlet flue of a primary absorption tower and the outlet SO 2 concentration of an inlet flue of a clean chimney in real time through an SO 2 concentration monitoring module; S20, the DCS intelligent control system judges the type of the current working condition according to the unit load information and the SO 2 concentration information received in real time, and automatically controls and executes a corresponding operation mode, and the method comprises the following steps: S21, if the normal working condition is judged, executing a normal series mode, wherein the normal series mode comprises the following steps: Closing a baffle door of a bypass flue, opening baffle doors of an inlet flue and an outlet flue of the secondary absorption tower, starting a slurry circulating pump and an oxidation fan of the secondary absorption tower, sequentially flowing through the primary absorption tower and the secondary absorption tower, discharging, and maintaining the pH value of the primary absorption tower at 4.8-5.0; S22, if the low-load or low-sulfur working condition is judged, executing a bypass energy-saving mode, wherein the bypass energy-saving mode comprises the following steps: And stopping the slurry circulating pump and the oxidation fan of the secondary absorption tower, closing the baffle doors of the inlet flue and the outlet flue of the secondary absorption tower, opening the baffle door of the bypass flue, discharging the flue gas through the bypass flue, and improving the pH value of the primary absorption tower to 5.0-5.2.
7. The energy-saving optimization control method according to claim 6, wherein, When the unit load is greater than 60% of rated load or the inlet SO 2 concentration is greater than 800mg/m < 3 >, judging the normal working condition, and executing a normal series mode; and when the unit load is less than or equal to 60% of rated load and the concentration of the inlet SO 2 is less than or equal to 800mg/m < 3 > for more than 300 seconds, judging that the unit load is a low-load or low-sulfur working condition, and switching to a bypass energy-saving mode.
8. The energy-saving optimization control method according to claim 7, wherein, In step S22, further including: S221, in the bypass energy saving mode, when the concentration of the SO 2 at the outlet is detected to be more than 35mg/m 3 continuously for at least 10 minutes or the sealing wind pressure is detected to be less than 450Pa, executing the emergency recovery mode, wherein the emergency recovery mode comprises the following steps: the secondary absorber was immediately turned on and immediately switched back to the conventional series mode within 1 minute.
9. The energy-saving optimization control method according to claim 8, wherein, In step S22, further including: S222, in a bypass energy-saving mode, when the concentration of the inlet SO 2 fluctuates between 600-800 mg/m 3 to increase the concentration of the outlet SO 2 , adopting a step-type transition adjustment step: a. firstly, the pH value of a primary absorption tower is raised, the pH value is raised by 0.1 each time, and the process is carried out at intervals of 30 seconds each time; b. If the concentration of the SO 2 at the outlet is still more than 25mg/m 3 , increasing the number of circulating pumps for starting the first-stage absorption tower, and starting two circulating pumps to three circulating pumps; c. If the outlet SO 2 concentration continues to rise above 800mg/m 3 , the slurry circulation pump of the secondary absorber is started, ready for resuming the normal series mode.
10. The energy-saving optimization control method according to claim 6, wherein, Before step 10, the method further comprises the steps of equipment installation and debugging: a. after the bypass flue is installed, performing an air tightness test and a pressure loss test to confirm that the sealing is good, and then performing a ventilation test to confirm whether the design requirement standard is met; b. The baffle door module is installed and debugged, so that the wind pressure of each sealing chamber of each baffle door is stabilized to be higher than the smoke pressure in the flue under the normal working condition, and a positive pressure sealing barrier is formed; c. the DCS intelligent control system is in communication connection and debugging, at least 3 times of operation mode switching tests are carried out, the switching response time is measured to be within 1 minute, the leakage rate detection value after the baffle door is closed is less than or equal to 0.3%, and the design requirement standard is met.

Description

Energy-saving optimization device based on double-tower double-circulation desulfurization system and control method thereof Technical Field The application relates to the technical field of flue gas purification of coal-fired power plants, in particular to an energy-saving optimization device based on a double-tower double-circulation desulfurization system and a control method thereof. Background The double-tower double-circulation desulfurization system has the advantage of 'stage desulfurization and deep removal', and becomes a main flow technical route for ultra-low emission reconstruction of a high-sulfur coal motor group, and the core principle is that a primary absorption tower primarily removes 60% -70% of SO 2 in flue gas through limestone slurry, a secondary absorption tower further removes residual SO 2, and the outlet concentration is finally less than or equal to 35mg/m 3. However, under the background of accelerating construction of a novel power system, a coal motor unit is always in a low-load (namely 30% -60% of rated load) or low-sulfur coal combustion working condition (namely the sulfur content of coal in a furnace is less than or equal to 0.8%, and the concentration of SO 2 in an inlet is less than or equal to 800mg/m 3) for a long time due to factors such as peak shaving of a power grid, fluctuation of fuel quality and the like, and at the moment, the continuous operation of a secondary absorption tower exposes various technical bottlenecks, and the concrete steps are as follows: 1. The energy consumption redundancy problem is prominent. The plant power consumption of the desulfurization system accounts for 8% -12% of the total plant power consumption of the coal motor group, wherein a slurry circulating pump and an oxidation fan of the secondary absorption tower are core energy consumption equipment, the power of a single slurry circulating pump is 315-630 kW, the power of a single oxidation fan is 110-220 kW, the power consumption accounts for 50% -65% of the total power consumption of the desulfurization system, and the economy is poor; 2. Equipment wear and corrosion are aggravated, and maintenance cost is high. Under the low-load working condition, although the flow rate of the flue gas is reduced, the slurry sprayed out of the spraying layer of the secondary absorption tower still flushes equipment at the rated flow rate, gypsum particles (the particle size is 10-50 mu m) contained in the slurry can continuously abrade the impeller of the slurry pump and the inner wall of a pipeline, SO that the service life of the impeller is shortened; 3. The system resistance is stiff, and the induced draft fan needs to maintain high wind pressure to overcome the fixed resistance, so that extra power consumption is caused. The existing double-tower double-circulation desulfurization system is normally used regardless of the change of working conditions, smoke flows through spraying layers and demisters of the first-stage tower and the second-stage tower, the total resistance of the system is maintained at 1200-1500 Pa, and when the load is low, a draught fan needs to maintain high wind pressure to overcome fixed resistance, so that the current falling amplitude of the induced fan is far lower than the load falling amplitude, and extra power consumption is caused. In order to solve the above problems, at low load, some power plants try to optimize by adjusting the slurry circulation pump combination mode, for example, a "3+3" mode (i.e. 3 slurry circulation pumps of a primary absorption tower and 3 slurry circulation pumps of a secondary absorption tower) is changed into a "3+2" mode or a "2+3" mode, and at least 1 circulation pump needs to be reserved to maintain slurry disturbance, but the scheme can only reduce the load of part of equipment of the secondary absorption tower, the secondary absorption tower still continuously operates, and the problems of the bottlenecks caused by continuous operation of the secondary absorption tower at low load, particularly the problems of high energy consumption, cannot be thoroughly solved, and the practical energy saving effect is far lower than expected. Another solution attempts to optimize energy conservation by reducing the rotation speed of the slurry circulation pump, but the reduction in rotation speed can result in reduced spray coverage, causing the risk of exceeding the concentration of the outlet SO 2. Disclosure of Invention The application aims to provide an energy-saving optimization device based on a double-tower double-circulation desulfurization system and a control method thereof, so as to solve the technical problems of high energy consumption, increased equipment corrosion and abrasion, increased maintenance cost and the like caused by forced operation of a secondary absorption tower under low load. In a first aspect, the present application provides an energy-saving optimization device based on a dual-tower dual-cycle desulfurizatio