Common in desulfurization system of main equipment for the absorber, the flue, chimneys, desulphurization pump, blower fan, such as the main equipment, the ka wah technology in desulphurization pump, absorber, the flue, chimney parts such as corrosion resistance, wear effect is remarkable, are described respectively.
Absorption tower, chimney application.
Wet flue gas desulfurization (FGD) environmental protection technology because of its high desulfurization rate, coal quality, wide applicable technology mature and stable operation cycle is long, small load change, characteristics of flue gas treatment ability, is widely used in each big, medium-sized coal-fired power plants, become the dominant technology of flue gas desulfurization in thermal power plants at home and abroad. But the process also have strong corrosive medium, high flue gas temperature, SO2 absorption liquid solid content big, strong wear resistance, equipment corrosion protection area, high quality demand of the construction technology and corrosion failure difficult maintenance, etc. Therefore, the corrosion control of the device has been one of the key problems in the long cycle safety operation of the device.
The selection of anti-corrosion materials for flue gas desulphurization tower and chimneys must be considered in the following aspects:
(1) meet the conditions of complex chemical environment of anti-corrosion requirements: chemical environment is complex, in the chimney flue gas acid content is very high, in the lining surface condensation, for most building materials have very strong corrosive, so the lining material requirements have strong acid corrosion resistance;
(2) heat resistance requirements: flue gas temperature difference is big, after wet desulfurization of flue gas temperature, between 40 ℃ ~ 80 ℃ in the desulfurization system maintenance or not run and unit operation condition, inside the chimney flue gas temperature is between 130 ℃ ~ 150 ℃, then asked lining has the ability to resist temperature changing, frequent change in temperature environment is not cracking and durable;
(3) the wear-resisting performance is good: smoke contains a large amount of dust, while under the effect of corrosive medium, the actual situation of wear may be more obvious, so request anticorrosive material with good abrasion resistance;
(4) has certain flexural performance: due to high altitude characteristics of considering some of the chimneys, including is the movement of the earth itself, earthquake and wind loads, and so on and so forth, especially high chimney site may occur rocking Angle deflection or deviation, and chimney might occur in the process of installation and transportation some uncontrollable mechanical function, etc., so request anticorrosive material has certain flexural performance;
(5) has a good bond: anti-corrosion material must have a strong bond strength, not only refers to the bond strength of material itself is higher, and the bonding strength between material and base material, also asked that the material is not easy to produce cracks, delamination or stripping, better adhesion and impact strength, to ensure good corrosion resistance. Usually we require that the adhesion of the base coating material and the steel structure can reach at least 10MPa.
Application of desulfurization pump.
Desulfurization slurry circulating pump is the relay desulfurization system after the heat exchanger, blower fan of large equipment, usually adopts the centrifugal, it directly from the bottom makes a cycle of slurry is largest in desulfurization process flow and use of the most demanding conditions of pump, corrosion and abrasion often lead to the failure. Its features include:
(1) strong abrasion.
The slurry in the desulfurization tower has a large number of solid particles, mainly fly ash and desulfurization medium particles, and the particle size is generally 0 ~ 400µ. M, more than 90% is 20 ~ 60µ M, the concentration is 5% ~ 28% (mass ratio), and these solid particles (especially Al2O3 and SiO2 particles) have strong abrasion resistance.
(2) strong corrosiveness
In a typical limestone (lime) - gypsum desulphurization process, general bottom slurry pH value for 5 ~ 6, after joining desulfurizer pH value of 6 ~ 8.5 (circulating pump slurry pH value and the operating conditions of desulfurization tower and desulfurizer join points); Cl- can be enriched with over 80000mg/L, which will produce strong corrosivity under the condition of low pH value.
In the desulphurization system, a certain amount of gas is often found in the slurry transported by circulating pump. In fact, the slurry transported by centrifugal circulation pump is gas-solid liquid multiphase flow, and the effect of solid relative pump performance is continuous and even, while the influence of gas relative pump is far more complicated and more difficult to predict than solid phase. When the pumped liquid contains gas, the flow rate, lift and efficiency of the pump decrease, and the greater the gas content, the faster the efficiency decreases. With the increase of gas content, additional noise vibration of the pump can cause damage of pump shaft, bearing and seal. Pump suction at the entrance and the place such as blade on the back of the gathered will lead to gas flow resistance increase resistance and even flow, which in turn worsen condition, must be increased cavitation, gas density is small, large volume, large compressibility, rheology, centrifugal force is small, energy conversion performance difference is the main cause of pump working condition deteriorated. The test shows that when the volume of air in the liquid reaches about 3%, the performance of the pump will be reduced. When the inlet gas reaches 20% ~ 30%, the pump is completely cut off. The centrifugal pump allows the limit of air volume (volume ratio) to be less than 5%.
The main advantages of the field application of polymer composite materials are: normal temperature operation, avoid thermal stress deformation caused by traditional technology such as welding, and avoid secondary damage to parts; In addition, the construction process is simple, and the repair process can be repaired by site operation or partial disassembly of equipment. It is the most ideal application technology to solve this problem.