First, the introduction

The desulfurization spray tower is the main equipment for SO2 absorption and purification. The treatment of SO2 flue gas is considerable, and the flue gas is continuously and efficiently purified in an instant. Since the chemical reactions in which SO2 participates should be extremely fast, the values of the intra-membrane conversion coefficient are large, and the reaction takes place in the membrane. Therefore, an absorption tower having a continuous phase, a high degree of turbulence, and a large phase interface is selected as the desulfurization tower and Desulfurization dust collectors are more suitable. In general, spray towers, packed towers, spray towers, tray towers, venturi absorption towers, etc., can meet these requirements. Among them, the spray tower is one of the most widely used types of desulfurization towers. The spray tower has the advantages of simple structure and mature technology, and is widely used in large-scale power plants, small and medium-sized low-sulfur flue gas treatment; for high-sulfur flue gas treatment, The non-ferrous industry mainly consists of pneumatic emulsification desulfurization tower and multi-layer spray tower.

Second, the structure of the desulfurization spray tower

The wet flue gas desulfurization environmental protection technology (FGD) is widely used in various applications due to its high desulfurization rate, wide application range of coal quality, mature process technology, long stable operation cycle, small influence of load fluctuation and large flue gas treatment capacity. Large and medium-sized thermal power plants have become the leading technology for flue gas desulfurization of thermal power plants at home and abroad. However, due to the strong corrosiveness of the medium, the high temperature of the flue gas, the large solid content of the SO2 absorption liquid, and the large flushing property, the quality of the construction technology is relatively high. Therefore, the corrosion control of the desulfurization spray tower has always been one of the key issues affecting the long-term safe operation of the plant.

Our company's desulfurization anti-corrosion structure selection considers the following aspects:

(1) Anti-corrosion requirements in the environment of complex chemical conditions: the chemical environment is complex, the acid content of the flue gas is very high, and the condensation formed on the surface of the inner liner is highly corrosive to most building materials, so The lining material is required to have strong acid corrosion resistance;

(2) Temperature resistance requirements: The temperature difference of the smoke varies greatly. The temperature of the wet desulfurization flue gas is between 150 °C and 200 °C. The lining is required to have the ability to resist temperature change, requiring no cracking and durability;

(3) Good wear resistance: the flue gas contains a large amount of dust, and under the action of corrosive medium, the actual situation of wear may be more obvious, so the anti-corrosion material is required to have good wear resistance;

(4) It has good adhesion: anti-corrosion materials must have strong bonding strength, not only the bonding strength of the material itself is high, but also the bonding strength between the material and the substrate is high, and the material is not easy to be required. Cracking, delamination or peeling occurs, and adhesion and impact strength are good, thus ensuring good corrosion resistance. Usually we require the adhesion of the primer material to the steel structure base to be at least 10 MPa or more.

Combining the above factors and performance, the structural layer of our company's desulfurization spray tower is FRP anti-corrosion (four oil three cloth)-epoxy vinyl clay-granite; desulfurization spray tower production, suitable for local needs, can be made according to customer needs, can be integrated It can also be factory-packed by factory.

Third, the sodium alkali absorption mechanism

The sodium-alkali method uses Na2CO3 or NaOH solution as the absorption liquid to absorb and purify SO2 and part of the dust in the flue gas. The purified waste liquid flows into the circulating pool for precipitation, and the desulfurizing agent is added and sent back to the absorption tower for recycling.

SO2 dissolves SO2 (gas) - → SO2 (liquid)

SO2 (liquid) + H2O ===HSO3-+H+

HSO3-===H++SO32-

2NaOH+SO2===Na2SO3+H2O

Na2CO3+SO2===Na2SO3+CO2

Na2SO3+SO2+H2O===2NaHSO3

In this process, since sodium alkali is used as the absorption liquid, no sediment is generated in the absorption system. The main side reaction in this process is oxidation, which produces Na2SO4:

2NaHSO3+O2===2Na2SO4