System Description

Ammonia addition system for water in thermal power plant's thermal system, automatically injecting ammonia into the steam-water system through a dosing pump that tracks the changes in the steam-water quality, ensuring optimal system conditions and safe operation of the unit.

Dissolved oxygen in the boiler's water-steam system is a primary factor causing corrosion in thermal equipment and threatening the safe operation of the boiler. Adding hydrazine to the feed water is a chemical method to further strengthen deaeration after the deaerator. The dosing amount of hydrazine in the addition unit must be strictly controlled; insufficient dosage cannot guarantee deaeration effectiveness, thus failing to prevent boiler corrosion and ensure the safe and economic operation of the power plant; conversely, excessive dosage not only leads to unnecessary waste but also causes environmental pollution. By using an automatic hydrazine dosing unit, the dosage of hydrazine can be automatically adjusted based on the actual operating conditions of the boiler, maintaining the concentration of hydrazine in the feed water within the specified range.

Process Overview

The ammonia dosing unit consists of a solution tank, a mixer, a metering pump, an electrical control cabinet, a level gauge, a safety valve, a pulsation damper, various valves, pipes, etc. It can be manually controlled on-site or automated. The automatic control is achieved by the variable frequency unit receiving signals from the flow, oxygen content, and turbidity meter.

Feature Highlights

Function Introduction of Automatic Control System: In automatic control mode, the system adjusts the speed and stroke of the metering pump based on flow and turbidity sensor signals processed by PLC, supervisory computer, or DCS. The flow adjustment range of the metering pump is 0~. The speed control input signal for the variable-frequency inverter is a standard 4~20mA signal, with the feedback signal also being a 4~20mA signal. The status and fault signals of all metering pumps and agitators can be remotely transmitted to the DCS or supervisory computer as required, and the DCS or supervisory computer can remotely start or stop the dosing pump as needed.

Electrical control cabinets can be equipped with various functions such as local manual control, semi-automatic control, and full-automatic control, depending on different technical requirements.

The solution tank can be made of materials such as 316 stainless steel and 304 stainless steel, depending on different corrosion resistance requirements.