Several problems in the construction of magnesium oxide desulfurization process

1. Construction of pipelines

    Magnesium oxide causticization is a slow and complex process. During the process of transporting the magnesium hydroxide slurry from the causticization tank to the magnesium hydroxide storage tank and to the desulfurization tower, the slurry is a state in which the particles and the liquid coexist, and it is easy to cause blockage of the pipe diameter, elbow, valve, etc., The system poses a great safety hazard, which requires careful attention to avoid system safety hazards caused by poor construction during construction.

    Usually there are four places where the pipeline is blocked, one is the tee with the valve; the other is the elbow with the climbing pipe; the third is the nozzle; the fourth is the outlet of the pump to the check gate.

The three-way valve with the valve is blocked because the residual slurry has a dead point when it is different from one pipe, and cannot be completely eliminated. The magnesium oxide crystallizes due to changes in external temperature and the like, eventually blocking the pipe. It is best to solve this problem during construction. The valve should be as short as possible without affecting the loading and unloading bolts. Occasionally, residual liquid can also be brought into the slurry under the flushing of the slurry.

    The pipeline for conveying the slurry should minimize the climbing pipeline. If it is unavoidable, it is better to install the drain valve below the low-side pipeline and the flushing pipeline at the high-end pipeline, but the isolation gates at both locations must be very close to the opening point;

Slurry nozzle clogging is difficult to handle. The best way is to reduce the number of sprinklers, increase the number of perforated plates or increase the liquid plate.

In addition, pipeline construction generally uses steel-lined rubber or glass-reinforced steel pipelines as slurry conveying pipelines. These two pipelines are expensive. Recently, some manufacturers use rubber pipelines as slurry conveying slurry pipelines. This pipeline has low cost, convenient maintenance and direct replacement. The time is short, and there is no need to wait for the rubber to be lined up like a rubber-lined pipe, but there are many pipe supports.

    2. Chimney and desulfurization tower

    Because the development of desulfurization in China is very late, many power plants are carrying out the expansion of existing boilers and the installation of desulfurization equipment at the same time. It is often impossible to install equipment due to the tightness of the site.

The combination of a chimney and a desulfurization tower is a good choice, reducing both floor space and investment. Moreover, if the existing boiler is upgraded to increase the desulfurization device, the "smoke tower integration" method is adopted, and the original chimney and the horizontal flue are also disposed of. Our company successfully designed the magnesia desulfurization project of chimney and desulfurization tower

    3. Anti-corrosion of magnesium oxide desulfurization tower

    Anti-corrosion is an important part of desulfurization. The anti-corrosion of desulfurization tower directly affects the safe operation and desulfurization efficiency of the desulfurization system. In terms of the current anti-corrosion of FRP scales, the links that must be paid attention to during construction are as follows:

1) Polishing of the weld. The grinding of the weld directly affects the adhesion of the scales. The thickness must not exceed 2 mm of the wall, and the weld and the tower wall must be too slow.

2) Sandblasting. Many construction teams do not pay much attention to this part of sand blasting. It is often that this link does not cause a large area of glass flakes to fall off, causing corrosion of the entire desulfurization tower. Sandblasting must use quartz sand, the particles are about 2mm, if you do not use quartz sand, you need to use sand. The slab after blasting has a metallic luster, and the imprint of the sand does not exceed 1.5 mm.

    4, the installation of the defogger

    The installation of the mist eliminator directly affects the emission quality of the flue gas. The defogger not only has the effect of removing moisture and impurities in the flue gas, but also directly affects the desulfurization efficiency.

The quantity and uniformity of the flushing water is very important. The amount of flushing water is small. The impurities contained in the defogger are hung on the defogger, which affects the efficiency of the defogger. The demister can be blocked seriously, causing the pressure in the tower to be too high. The flue gas temperature is high, the desulfurization efficiency is reduced, and even the demister is damaged; the uneven flushing water will also cause the above problems. Therefore, the defogger must be equipped with a flushing water system.

The height (thickness) of the mist eliminator should be moderate. Too high and too long will cause the flue gas outlet temperature to be low, the pressure inside the tower to be high; too short (thin), poor defogging effect, high outlet pressure, smoke The temperature is too high.

    5, summary

    In the process of magnesium oxide desulfurization process, it must be combined with the actual use situation and the site situation. If it is considered, it can meet the design requirements and ensure safe and convenient operation and improve the actual use efficiency.