Dashiqiao Hongkai Refractories Co., Ltd.
Contact number: +86-13841720502
Zip code: 115100
Site: Nanlou Economic Development Zone, Dashiqiao City, Liaoning Province
Office Address: Building No. 5, Fenghua Yihe Village, Dashiqiao City, 105
1 Design Principle
Medium-grade magnesia adopts mature and reliable coagulation and sedimentation treatment technology to ensure that all indexes of treated water meet the first-class drainage standard of the National Comprehensive Wastewater Discharge Standard GB8978-1996. Sewage treatment facilities should have small occupied area, low investment, low energy consumption and low treatment cost, and be suitable for thermal power plant transformation projects. Vibration reduction and reduction of supporting equipment should be fully considered in design. Noise and other measures to avoid secondary pollution.
2 process flow
The slurry discharged from the desulfurization tower contains 15% solid, and the main solid component is magnesium sulfite. The slurry discharged must be dehydrated before it can be further treated to obtain the desired by-products. In this project, the dehydration system includes dehydration supply tank, dehydration supply pump, centrifugal dehydrator, dryer and other related equipment.
The desulphurization slurry in the desulphurization tower is discharged from the slurry and pumped to the dehydration supply tank. The desulphurization by-product after concentration is conveyed to the hot air dryer by a screw conveyor through a centrifugal dehydrator. The byproduct with about 10% water at the outlet of the dryer flows into a storehouse of by-product. The wastewater from the whole process enters the treatment system and is discharged after meeting the standard. This project desulfurization wastewater treatment process: neutralization, sedimentation, flocculation, clarification.
Neutralization: The acidic wastewater produced by flue gas desulfurization is elevated from the wastewater pump of the cyclone separator to the neutralizing box. The pH regulating system is set up in the neutralizing box. The dosage of lime milk is controlled by the control valve and frequency conversion device to maintain the pH value of the wastewater in the neutralizing box (8.8-9.0). At this time, a large number of heavy metal ions (such as Zn2+, Mg2+) in the original wastewater are precipitated in the form of hydroxides, in order to make the wastewater more stable The wastewater can be evenly mixed in the neutralizer, and a stirring motor is set up.
Settlement: The gravity of the wastewater in the neutralization tank flows to the settling tank, where a large amount of Mg and other heavy metals in the wastewater are precipitated from the wastewater in the form of very fine hydroxides and complexes. At the same time, in order to ensure the precipitation of other trace heavy metal ions in wastewater, organic sulfides were added into the settling tank to react with other heavy metal ions and sulfur ions to form insoluble metal sulfides. Owing to the fine particles of hydroxides and metal sulfides formed, it is not easy to settle down in wastewater. Therefore, the fine particles in wastewater can form flocculants by adding complex iron. In order to mix evenly, a stirring motor is installed in the settling tank, and the wastewater is flowed into the flocculation tank through gravity.
Flocculation: The flocculant (PAM) is added to the flocculator to form a larger flocculant by stirring fine alum flowers to ensure solid-liquid separation in the clarifier. A stirring motor is arranged in the flocculation box.
Clarification: Wastewater from flocculation tank is separated from solid and liquid in clarification tank. Because the amount of wastewater is very small (5m3/n), the clarification tank adopts vertical flow sedimentation tank which is easy to install and maintain. It runs stably and reliably, and saves a set of mechanical equipment (rotary scraper). The clarifier forms concentrated sludge under the action of gravity concentration. The sludge is discharged by sludge screw pump. Clear water flows into the outlet tank from the surrounding outlet triangular weir. Sludge concentration meter is installed in clarifier to detect sludge discharge regularly.
Because of the high pH in wastewater (8.8-9.0), stirring motors are installed in the outlet tank, and the pH regulating system is equipped. The pH regulating system controls the installation of HC1 metering pumps to ensure that the water quality in the outlet tank reaches the discharge standard (pH=6-9), and the outlet water is discharged outside the desulfurization island through the sanitary flushing pipe.