A kind of control method of dissolved gas in boiler feed water

Abstract

The invention discloses a method for adjusting dissolved gases in boiler feed water. The steam of a boiler forms condensed water after the work of a steam turbine; the condensed water flows out of a condenser and enters a polishing apparatus through a condensed water pump; the condensed water is subjected to degassing or oxygenation treatment by a membrane degasser or membrane oxygenator, wherein the membrane degasser is connected with a vacuum pump, and the membrane oxygenator is connected with an oxygen bottle; the treated water enters the boiler through a low-pressure heater, a water feed pump and a high-pressure heater; and the membrane degasser and the membrane oxygenator are fiber membrane contactors. According to the adjusting method, a fiber membrane is adopted as a gas-liquid exchange interface; according to different water qualities, membrane degassing treatment is carried out in AVT (all-volatile treatment) working condition, and membrane oxygenation treatment is carried out in OT (oxygenated treatment) working condition; and the gas content of the boiler feed water can be quickly and accurately adjusted, the flow accelerated corrosion (FAC) is avoided, and the operation safety of the unit is improved.

Description

technical field [0001] The invention relates to the technical field of boiler feed water treatment, in particular to a control method for dissolved gas in boiler feed water. Background technique [0002] The main factor affecting safe production during the operation of the thermal system is equipment corrosion, in which dissolved oxygen and free CO 2 The resulting corrosion of the boiler water supply system can not only cause damage to the water supply pipes and related equipment, but also cause metal corrosion products to enter the boiler with the feed water and deposit on the evaporation surface, which can easily cause damage to the boiler tube. A small part of metal corrosion products is formed in the low-pressure and high-pressure heaters and in the deaerator, and most of them come from the condenser and the water supply system, so the dissolved oxygen and free CO in the water supply system are adjusted 2 It is a key measure to prevent boiler corrosion. [0003] At pre...

AI Technical Summary

Problems solved by technology

However, the degassing tower and other equipment used are large in size and high in investment costs, and the water needs to be heated to 104°C during operation, resulting in large steam loss and energy consumption

Chemical deoxidation mainly uses hydrazine, acetone oxime, dimethyl ketone oxime and other drugs. Although it has a good deoxygenation effect under certain conditions, hydrazine is poisonous, and it is easy to explode when mixed with air and exposed to open flames. Many boilers restrict their use. , while the cost of other oxygen scavengers is relatively high

[0004] It can be seen that the use of traditional AVT working conditions to remove oxygen and free CO 2 Sometimes there are problems such as poor environmental protection performance and serious waste of resources

When it is used on a supercritical unit, there are still the following problems: there is no anti-calcium magnesium scale; the Fe formed on the surface of the equipment 3 o 4 It is easy to dissolve, and the water supply system is prone to flow-accelerated corrosion (FAC); when the amount of ammonia added is large, it is easy to enrich in the evacuation area of ​​the condenser, causing ammonia corrosion of copper pipes; the depth of oxygen removal is poor, and the dissolved oxygen content of the treated water is 5 -7ppb or more

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