Questions about water deoxygenation
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What are the current methods for deoxygenating boiler water? Which method is better? What equipment are used?
Generally, a combination of physical and chemical deoxidation is used. Physical deoxidation uses the solubility of oxygen in water to decrease as the temperature increases. A deoxidation tank is used to heat the water with steam to deoxidize. Chemical deoxidation involves adding chemicals to the water. Here we add N2H4.
At present, the most commonly used method is thermal deaeration. If it is a small boiler, there are also many chemical deaeration methods (that is, adding deoxidation chemicals).
Sponge iron deaerator: Deoxygenation can be achieved at room temperature, and the incoming water does not need to be heated. ； The system can supply water at any time, and does not require preparation time or deaeration water tank. ； The oxygen removal effect is stable and reliable, and the dissolved content in the effluent is stable ≤0.05mg/L, which meets the low-pressure boiler water quality standards. ； There are no special requirements for installation, which overcomes the inconvenience that thermal and vacuum deoxygenation must be installed at a high level. ； The equipment can be arranged at a low position, the process is simple, and there is no excessive height requirement.
What are the current methods for deoxygenating boiler water? Which method is better? What equipment are used? Nowadays, there are many methods for deaeration of boiler feed water, including thermal deaeration, analytical deaeration, sponge iron deaeration, etc. Thermal deaeration has the following classification methods: 1. According to the thermal working process, it can be divided into hybrid deaerator and superheated deaerator. ； 2. According to the working pressure, it can be divided into vacuum deaerator, atmospheric deaerator and high pressure deaerator. ； 3. According to the structural form, it can be divided into water spray disc type, spray type, filler type, spray-filler type, spray-steam spray disc type, etc. Spray-packing atmospheric deaerators are commonly used in power plants. The equipment is relatively simple, which is the deaerator head, water tank and supporting instruments, meters and valve control devices.
Oxygen can be removed using heat. The equipment is a thermal deaerator. The working principle of the thermal deaerator is: The condensed water is directly heated to the saturation temperature under working pressure by steam, and the dissolved oxygen and other non-condensable gases in the water are removed, so that the feed water reaches the required water quality. There are two commonly used thermal deaerators: Membrane type (headed type) and spray type (usually built-in type or headless type).
Our company uses thermal deaeration, which heats the softened water to about 104 degrees to overflow the oxygen according to the solubility of oxygen in the water.； My company also used sponge iron to remove oxygen, but no longer uses it.
A microporous hydrophobic hollow fiber membrane contactor was used as a deaeration device. An aqueous solution of hydrazine hydrate or sodium sulfite is used as the reducing agent, but the reducing agent does not need to be added directly to the water. Let the raw water flow through the tube side of the membrane, and the reducing agent aqueous solution through the shell side of the membrane. The dissolved oxygen in the water is transferred to the micropores of the membrane and diffuses to the other side of the membrane to be absorbed by the reducing agent aqueous solution and reduced. By operating in this way, the concentration of oxygen in the raw water can be reduced to a very low level, and more than 99% can be removed. In this way, the raw water and the reducing agent are not in direct contact. Is this an advantage? The high process does not require high temperature, high pressure, negative pressure and vacuum operations. No heat consumption, very little power consumption, and limited chemical consumption. We can provide large industrial grade membrane contactors. Interested, please contact yjqin1@yahoo.com or yqin@chembrane.com This post was last edited by yjqin1 on 2009-3-14 13:47 ]