A system and method for increasing the temperature in the SCR zone of a boiler under low load

By installing a steam heater and flue gas damper at the economizer inlet and adjusting the economizer compartments and water volume, the problem of insufficient flue gas temperature at the SCR inlet under low load was solved, ensuring the normal operation of the SCR unit and the control of pollutant gas emissions.

CN119607867BActive Publication Date: 2026-04-07XIAN TPRI BOILER ENVIRONMENTAL PROTECTION ENG CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2025-01-20
Publication Date
2026-04-07

AI Technical Summary

Technical Problem

When a coal-fired power unit is operating at low load, the inlet flue gas temperature of the SCR denitrification unit is difficult to reach the activation temperature range of 310℃ to 400℃, which may lead to catalyst blockage and increased air preheater resistance, as well as an increased risk of SO3 condensation, thus affecting the denitrification effect.

Method used

A steam heater and a flue gas damper are installed at the economizer inlet of the boiler. The inlet water temperature of the economizer is controlled by adjusting the steam heater and the economizer inlet water flow regulating valve. Combined with the adjustment of the economizer sections and the flue gas damper, the inlet flue gas temperature of the SCR is ensured to be within the normal range.

Benefits of technology

It effectively increases the SCR inlet temperature under low load, ensuring the normal operation of the SCR unit, avoiding over-emission accidents, and achieving effective control of pollutant gases. It is suitable for a wide range of load conditions.

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Abstract

The present application belongs to the field of coal-fired boiler, and discloses a system and method for improving the temperature of SCR zone of a boiler under low load, which comprises a boiler, an economizer and an SCR denitration device, the economizer is arranged in the tail flue of the boiler; the inlet of the economizer is provided with an economizer inlet water flow regulating valve, and the inlet of the economizer is connected with a steam heater; the inlet of the steam heater is provided with a steam heater isolation valve, and the steam heater is correspondingly provided with a steam heater bypass, the two ends of the steam heater bypass are located upstream of the steam heater isolation valve and downstream of the outlet of the steam heater respectively, and the steam heater bypass is provided with a steam heater bypass isolation valve; the flue gas inlet of the SCR denitration device is connected with the tail flue, and the tail flue is provided with an SCR inlet flue temperature detection device. The present application can improve the SCR inlet temperature under the condition that the original unit is changed little, ensure the normal operation of the SCR, and effectively realize the emission control of the pollution gas under the low load of the coal-fired unit.
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Citation Information

Patent Citations

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  • Dual-reheating temperature adjusting device used for tower-type boiler

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  • Coal economizer capable of adjusting working medium flow

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