Denitrification system and replacement method of catalyst layers thereof

Abstract

The invention discloses a denitrification system and a replacement method of catalyst layers thereof. The replacement method comprises the following steps: S10: in an SCR (selective catalytic reduction) reactor, sequentially arranging a first mounting position, a second mounting position and a third mounting position for mounting the catalyst layer in the flow direction of flue gas; S20: mounting the catalyst layers on the first mounting position and the second mounting position, and emptying the third mounting position; S30: monitoring outlet flue gas; S40: if the outlet flue gas is not up to standard, detaching the catalyst layer on the first mounting position and mounting the catalyst layer on the third mounting position; S50: monitoring outlet flue gas; S60: if the outlet flue gas is not up to standard, detaching the catalyst layer on the second mounting position and mounting the catalyst layer on the first mounting position; S70: monitoring outlet flue gas; S80: if the outlet flue gas is not up to standard, detaching the catalyst layer on the third mounting position, mounting the catalyst layer on the second mounting position and executing the step S30. By the replacement method, a nitrogen oxide emission index is met, the internal resistance of the system is reduced, dust accumulation in the reactor and corrosion to downstream equipment are reduced, and the catalyst replacing expense is reduced.

Description

technical field [0001] The invention relates to a method for replacing a catalyst layer in an SCR denitration system, in particular to a denitration system and a method for replacing a catalyst layer. Background technique [0002] The principle of Selective Catalytic Reduction (SCR) is that under the action of a catalyst, the reducing agent NH 3 Selectively convert NO and NO at 290-400°C 2 reduced to N 2 , while NH hardly occurs 3 with O 2 oxidation reaction, thereby increasing the N 2 selectivity, reducing the NH 3 consumption. [0003] In order to meet the long-term stability of the NOx concentration at the outlet of the denitrification SCR device ≤ 50mg / Nm 3 According to the environmental protection requirements, it is the most common practice to add a spare layer catalyst. However, although the addition of a spare layer catalyst can improve the denitrification efficiency, it also brings many adverse effects. After adding a spare layer catalyst, due to the increa...

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Problems solved by technology

However, although the addition of a spare layer catalyst can improve the denitrification efficiency, it also brings many adverse effects

After adding a spare layer catalyst, due to the increase in the total thickness of the catalyst layer, the resistance of the SCR denitrification system will increase by about 200Pa. The increase in resistance will lead to an increase in the power consumption of the induced draft fan and increase the operating cost. At the same time, the original two-layer catalyst The degree of mechanical wear increases and the reproducibility decreases; after layering, SO 2 / SO 3 The conversion rate of the reactor will increase, which will easily lead to corrosion of the downstream air preheater; and the adaptability of the flow field in the reactor will be worse after adding layers, which will easily cause dust deposition

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