CN-121971968-A - Control method for ozone escape in flue gas ozone denitration process

CN121971968ACN 121971968 ACN121971968 ACN 121971968ACN-121971968-A

Abstract

The invention relates to the technical field of flue gas purification, and particularly discloses a control method for ozone escape in a flue gas ozone denitration process, which is used for comparing a NOx concentration value in flue gas at an outlet of a denitration system obtained by real-time monitoring with a preset emission standard value to judge whether a denitration efficiency state reaches or exceeds a standard; comparing the ozone concentration value in the flue gas at the outlet of the denitration system, which is monitored in real time, with a preset ozone emission standard, judging that the ozone escape state is up to standard or exceeds standard, adjusting and increasing the ozone adding amount if the NOx concentration value exceeds standard, adjusting the running state of an ozone destruction device connected with the denitration system according to the ozone concentration value, and adjusting and reducing the ozone adding amount and adjusting the running state of the ozone destruction device if the NOx concentration value reaches standard and the ozone concentration value exceeds standard at the same time. The invention can optimally control the safety risk of escaping ozone on the premise of ensuring the standard emission of pollutants.

Inventors

YAN XUEFANG
DU WENTAO
FU YUANHANG
ZHUANG YUANFA
DENG YI
LI LINGJUN

Assignees

东方电气集团东方锅炉股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260115

Claims (10)

1. A control method for ozone escape in flue gas ozone denitration process is characterized in that, Comparing the NOx concentration value in the outlet flue gas of the denitration system obtained by real-time monitoring with a preset emission standard value, judging whether the denitration efficiency state reaches the standard or exceeds the standard, and comparing the ozone concentration value in the outlet flue gas of the denitration system obtained by real-time monitoring with the preset ozone emission standard, and judging that the ozone escape state reaches the standard or exceeds the standard; if the concentration value of NOx exceeds the standard, adjusting and increasing the ozone adding amount, and adjusting the running state of an ozone destruction device connected with the denitration system according to the concentration value of ozone; And if the concentration value of the NOx reaches the standard and the concentration value of the ozone exceeds the standard, adjusting and reducing the ozone adding amount, and adjusting the running state of the ozone damage device.
2. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 1, wherein a calculation formula of the ozone addition amount is as follows: ; Wherein, the The ozone adding amount is; F is the flow of flue gas at the inlet end of the denitration system under the standard dry state and the standard oxygen content; k is an adjustment coefficient; M O3 is the relative molecular weight of ozone; m NOx is the relative molecular weight of NOx; C NOx is the NOx concentration value of the flue gas at the outlet of the denitration system in a standard dry state under the standard oxygen content; C Standard of is the standard dry state and the standard NOx emission of the flue gas at the outlet of the denitration system under the reference oxygen content.
3. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 2, wherein the ozone adding amount is increased when a calculation result calculated by a calculation formula is a positive value, and the ozone adding amount is decreased when a calculation result calculated by a calculation formula is a negative value.
4. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 1, wherein if the concentration value of NOx exceeds the standard, the ozone adding amount is adjusted and increased, and the running state of an ozone destruction device connected with a denitration system is adjusted according to the concentration value of ozone, specifically comprising: When the concentration value of NOx exceeds the standard and the concentration value of ozone exceeds the standard, increasing the ozone adding amount, and starting an ozone emergency destruction device to run at full load; And when the concentration value of NOx exceeds the standard and the concentration value of ozone reaches the standard, increasing the ozone adding amount.
5. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 1, wherein if the concentration value of NOx reaches the standard and the concentration value of ozone exceeds the standard, the ozone adding amount is adjusted and reduced, and the running state of the ozone destruction device is adjusted, specifically: If the NOx concentration value reaches the standard and the ozone concentration value exceeds the standard at the same time, comparing the ozone concentration value with a preset primary concentration threshold value, a preset secondary concentration threshold value and a preset tertiary concentration threshold value, and judging whether the escape ozone risk level is primary early warning, secondary early warning or tertiary early warning; if the risk level of escaping ozone is primary early warning, reducing the ozone addition amount; If the risk level of escaping ozone is a secondary early warning, reducing the ozone adding amount, and starting an ozone emergency destruction device to operate at a low level; If the risk level of escaping ozone is three-level early warning, reducing the ozone adding amount, and starting the ozone emergency destruction device to operate at a high level.
6. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 5, wherein the low level operation specifically means that the ozone emergency destruction device is operated under 10-50% load.
7. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 5, wherein the high-level operation is specifically that the ozone emergency destruction device is operated under 50-100% load.
8. The method for controlling ozone slip in a flue gas ozone denitration process according to claim 1, wherein if the NOx concentration value and the ozone concentration value reach standards, diagnosing the process parameters: If the technological parameters are abnormal, outputting early warning information; if the process parameters are normal, the current state is maintained.
9. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 8, wherein the process parameters comprise ozone addition amount, flow rate of flue gas at the inlet of a denitration reaction system, temperature of flue gas at the inlet of the denitration reaction system, oxygen content of flue gas at the inlet of the denitration reaction system, and NOx concentration of flue gas at the inlet of the denitration reaction system.
10. The method for controlling ozone escape in a flue gas ozone denitration process according to claim 1, wherein a first monitoring component for monitoring flow, NOx concentration value, temperature, pressure, water content and oxygen content of flue gas entering the denitration reaction system in real time and a second monitoring component for monitoring NOx concentration value, temperature, pressure, water content, oxygen content and ozone concentration in flue gas at an outlet end of the denitration reaction system in real time are arranged at an inlet end of the denitration reaction system.

Description

Control method for ozone escape in flue gas ozone denitration process Technical Field The invention relates to the technical field of flue gas purification, in particular to a method for controlling ozone escape in a flue gas ozone denitration process. Background The ozone denitration technology is a multi-pollutant synergistic removal technology with potential, is especially suitable for treating medium-low temperature flue gas, and has the core principle that the strong oxidizing property of ozone (O 3) is utilized to oxidize water-insoluble Nitric Oxide (NO) in the flue gas into high-valence nitrogen oxides which are easy to dissolve in water, and then the high-efficiency removal is realized in an absorption tower through an alkaline absorbent. However, the technology faces a key challenge in practical engineering application that uncertainty exists in ozone addition control and reaction process, and unreacted ozone (i.e. escaping ozone) can enter downstream equipment and a chimney along with the flue gas if the ozone is excessively added or insufficiently mixed with the flue gas for reaction. The following disadvantages exist: (1) Safety and environmental risk that ozone is a strong oxidizing toxic gas, its escaping emissions violate environmental regulations and constitute a direct threat to the surrounding ecological environment and personnel health, forming a secondary pollution source. (2) Equipment corrosion, namely, the corrosion of a downstream flue and a chimney can be accelerated by the strong oxidizing property of ozone, so that the maintenance cost is greatly increased. (3) The control strategy is isolated and contradictory, the existing process control strategy mainly adjusts the ozone addition amount by single-objective (denitration efficiency) optimization according to the inlet and/or outlet NOx concentration, and independent monitoring and disposal of escaping ozone are omitted. When pursuing high denitration efficiency (ozone needs to be added) and the goal of guaranteeing operation safety (ozone escape needs to be reduced) conflict, the system lacks collaborative decision-making capability, and the denitration efficiency of the system is not up to standard or safety risks are accumulated. (4) The monitoring means is lack that the existing industrial flue gas Continuous Emission Monitoring System (CEMS) is not generally provided with an on-line monitoring instrument for escaping ozone, so that operators cannot know the risk state of ozone escaping. Disclosure of Invention The technical problem to be solved by the invention is to provide a control method for ozone escape in a flue gas ozone denitration process, by introducing real-time monitoring and risk classification of escaping ozone, establishing a cooperative control logic based on judgment of NOx concentration value and ozone concentration value state, and realizing optimal control of safety risk of escaping ozone on the premise of ensuring standard emission of pollutants; The invention solves the technical problems by adopting the following solution: A control method for ozone escape in flue gas ozone denitration technology specifically comprises the following steps: Comparing the NOx concentration value in the outlet flue gas of the denitration system obtained by real-time monitoring with a preset emission standard value, judging whether the denitration efficiency state reaches the standard or exceeds the standard, and comparing the ozone concentration value in the outlet flue gas of the denitration system obtained by real-time monitoring with the preset ozone emission standard, and judging that the ozone escape state reaches the standard or exceeds the standard; if the concentration value of NOx exceeds the standard, adjusting and increasing the ozone adding amount, and adjusting the running state of an ozone destruction device connected with the denitration system according to the concentration value of ozone; And if the concentration value of the NOx reaches the standard and the concentration value of the ozone exceeds the standard, adjusting and reducing the ozone adding amount, and adjusting the running state of the ozone damage device. In some possible embodiments, the calculation formula of the ozone addition amount is: ; Wherein, the The ozone adding amount is; F is the flow of flue gas at the inlet end of the denitration system under the standard dry state and the standard oxygen content; k is an adjustment coefficient; M O3 is the relative molecular weight of ozone; m NOx is the relative molecular weight of NOx; C NOx is the NOx concentration value of the flue gas at the outlet of the denitration system in a standard dry state under the standard oxygen content; C Standard of is the standard dry state and the standard NOx emission of the flue gas at the outlet of the denitration system under the reference oxygen content. In some possible embodiments, the operation for increasing the ozone addition is performed when th