desulfurization Structure and Principle

It mainly consists of Tube body, Spraying device, Sieve Plate, dehydrating and demisting device, spillway, cleaning hole and so on. Its working principle is: flue gas containing dust and sulfur oxides enters tube body from chimney intake. Alkaline absorbtion liquid containing [OH-] ion separately sprays from the top, middle and bottom of the tower by the spiral nozzle and then forms multistrand high-speed atomized water curtain against the flue gas. It increases the colliding rate between sulfur oxide and water. The speed of atomized liquid drip is used to cause high comparative speed between gas and liquid and this can assure the desulfurization and dust removing efficiency. At the same time, gas makes the liquid layer on the Sieve-Plate bubble. This increases surface area and turbulent condition of Gas-liquid Mass Transfer and raises the speed rate. Gas-liquid Mass Transfer happens between Sulfur dioxide and alkaline liquid and raises the effect of the deduster. Desulfurization compound flows to the bottom of tower with the water and then is discharged from the spillway. The bottom of the tube is sealed and water sealed tank is set to prevent the smoke leaking from the bottom. Cleaning hole is used to clean the ash at the bottom of the tube by hands (or automatically). The sewage after desulfurization will be discharged from the bottom spillway into sedimentation tank to be counteracted, precipitated regenerated and recycled (dual-alkali). The purified air will be discharged after demisted by the demister. Then the purpose of desulfurizating and desusting can be achieved.

Characteristics

LP follicle dedust desulfurization tower has the advantages of low price, small consistence, wear-resistance, corrosion-resistance, convenient installation and so on. It is an ideal desulfurizating and dedusting equipment.

1. The equipment adopts natural granite that is corrosion-resistant, wear-resistant and heat-resistant as the inner liner. The granite is shaped into round bending board. The whole structure of the product is smooth and even and the systemic resistance can be reduced.

2. The part of tube body has the structure of quick-installation. The joint of two sections is concave-convex. This quickens the installation speed. The seam is filled with acid resistant daub to make sure that it will not leak.

3. The reasonable combination of sieve plate and spraying form not only raises the desulfuration efficiency but also reduces the system resistance.

4. Sieve plate, nozzle and such components are made of 316L stainless steel of good quality. It is corrosion resistant and ensures the useful life and desulfuration effect.

5. The well designed demister can ensure high usability and good liquid removing effect.

Introduction to the principle of desulfurizing art

Good equipment should be supported with reasonable art so that effciency of raising desulfurizing effect and reducing the costs can be achieved to satisfy the principle that technological economy is the most important. At present, wet desulfurizing method is widely used and takes part of more than 85% of FGD equipments all over the world.

Natrium-Calcium dual-alkali method [Na₂CO₃��Ca(OH)₂]is a method combining with Natrium-alkali method on the basis of lime method and utilizing the identity that sodium salt is soluble in water. Natrium-Alkali is used to absorb SO₂ in the absorbing tower. The absorbed desulfurizing liquor regenerates in the regenerating pool by cheap lime. Natrium ion can be circularly absorbed and utilized. The basic principle can be divided as desulfurizing process and regeneration process:
1. Desulfurizing Process:

Na₂CO₃+SO₂--Na₂SO₃+CO₂ (1)

2NaOH+SO₂--Na₂SO₃+H₂O (2)

Na₂SO₃+SO₂+H₂O--2NaHSO₃ (3)

The three formulas above can vary according to the acidity and alkalinity of the absorption liquid: (1) formula is the starting absorbing reaction formula. When the alkalinity is high (pH>9), (2) formula is the major reaction. When the alkalinity reduced to neutral or acid
2. Regeneration Process

2NaHSO₃+Ca(OH)₂--2SO₃+CaSO₃+2H₂O (4)

Na₂SO₃+Ca(OH)₂--aOH+CaSO₃ (5)

After adding Ca(OH)₂ serum (Ca(OH)₂ has reached supersaturated condition) to the resulfurized absorption liquid, neutral (amphiprotic) NaHSO₃ quickly reacts with lime serosity of fixed quantity and makes the PH value of circulatory liquor rise. [HSO₃^1-] then will be neutralized to [SO₃^2-]. The afterward a part of generated [SO₃^2-] continues to react with Ca²⁺ in the lime serum. The hemihydrated calcium sulfite produced by the reaction precipitates slowly and will be discharged by the system. Ionic concentration in the absorption liquid can be kept balance. The absorption liquid recovers the absorbing ability to SO₂ and can be used circularly. A tiny amount of sulfate will be produced for the existence of oxygen.  

This art combines the features of lime method and Natrium-Alkali method and resolves the problem that the lime method is easy to make the tower scale. It also possesses the advantage of high absorbing efficiency of Natrium-Alkali method. It possesses prominent advantage of "double high, double low", which is high resulfurization efficiency, high running reliability, low investment, low running cost.

This art also possesses the following advantages.

1. The technology is mature and running reliability is high. The main equipments of the system seldom break down. So the safe operation of the boiler won't be influenced by the malfunction of the resulfurazing equipment.

2. The operational flexibility is good and the adaptation to different types of coal is strong. The follicle dedust desulfurization tower adopts very active natrium-alkali liquid as dedusting and desulfurizing agent which is of good absorbing effect and high utilization ratio. PH value and vapour-liquid ratio can be adjusted properly to assure the realization of desulfurizing ratio.

3. The regenerating and sedimentation are separated out of the tower. The scaling chance in the tower and pipe can be largely reduced.

4. Natrium-alkali can be used circularly. The consumption is little and running cost is low.

5. No sewage is discharged in the absorbing process under normal operation.

6. Natrium-Alkali absorbing agent is of high reactive activity and quick absorbing speed. Low vapor-liquid ratio can be adopted to reduce the running cost.

7. It costs little to use lime (actual consuming substance) as regenerating agent.

8. The resulfurating residue is non-toxic and of low solubility, which can be comprehensive utilized. No secondary pollution forms. The resulfurizing by-product is calcium sulfite or calcium sulphate (oxidized). A new composite material called Calcium Plastic can be produced when calcium sulfite combines with synthetic resin. Calcium sulfite can be oxidized to make gypsum. Or it can be blended with pulverized fuel ash to make the pulverized fuel ash more plastic. Then the strength of pulverized fuel ash as the bottom layer for paving can be raised. Compared with magnesia hydroxide method, calcium salt won't pollute and no secondary waste pollution forms.

Installation, Operational and Maintenance

LP follicle dedust desulfurization tower follows the consistent designing styles and features of our company and adopts the structure of modularization. It is prefabricated by the factory and assembled on the spot. Quick and high efficient installation can be realized and the installation can be finished in half a day. The time and money of customers can be saved. Because the tower equipment is not equipped with moving device and adopts corrosion resistant design, the working quantity of maintenance is very little. Maintenance can be performed at the same time of boiler checking every year. Corrosion and scaling conditions are mainly checked. If the art adopts automatic feedback system, the non-men operation of the equipment can be realized and the running costs can be saved.

LP follicle dedust desulfurization tower equipment is a desulfurization equipment of high efficiency, low pressure losses. As well as the function of dust removing.