Application examples of supercritical boiler grids for anti-wear

       Grating anti-wear technology is an active anti-wear technology that is installed on the surface of the water-cooled wall along the horizontal and vertical directions to form a mesh grating, blocking the formation of high-speed wall flow, optimizing the flow field on the surface of the water-cooled wall, eliminating local vortex, reducing the velocity of gas-solid two-phase flow against the wall, reducing the cutting force of material particles on the water-cooled wall, and thus effectively controlling the wear of the water-cooled wall.

　　Application examples of supercritical boiler grill anti-wear

　　A new material company in Guangxi 3*350MW unit

　　Three supercritical 1240T/H CFB generating units were put into operation in 2018 to provide power support for 400,000 tons of electrolytic tanks as well as other large smelting equipment.

　　The demand for electricity is particularly huge during the operation of the electrolytic cells, and the power supply cannot be interrupted. Once there is a power interruption, the production line is shut down, which in serious cases can even lead to the destruction of the entire electrolytic cell, with losses amounting to hundreds of millions of dollars.

　　Long-term high load operation has led to 13 water-cooling wall wear and leakage accidents in a year for its three supercritical furnaces, causing great losses to the company's production.

　　Brief introduction of the unit.

　　Three 350MW supercritical CFB boilers, single blower plate single chamber, M-type arrangement, balanced ventilation, primary intermediate reheat, circulating fluidized bed combustion method, high temperature cooling cyclone separator

　　Front wall hanging screen distribution: 12 pieces of medium temperature superheater, 12 pieces of high temperature superheater, 6 pieces of high temperature reheater, 5 pieces of bulkhead water cooling wall;

　　Rear wall hanging screen distribution: 8 pieces of additional double heated surface water-cooled wall, membrane structure, vertical distribution;

　　Supercritical boiler wear analysis

　　The distribution pattern of wear-prone areas is as follows.

　　1. Water-cooled wall dense phase area;

　　2. Four corners of the furnace chamber area;

　　3. rear wall flue window area, cyclone area;

　　4. The area around the secondary air outlet;

　　5. Partition wall water-cooled screen and the front and rear wall water-cooled wall of the corner area;

　　6. Local projection of the heated surface and the front wall through the wall near the pipe, etc;

　　Supercritical boiler wear hazards

　　Supercritical circulating fluidized bed boiler furnace wear leakage occurs, because of the high steam pressure, compared with the low pressure level of the boiler, blowing damage is particularly serious.

　　Its characteristics are as follows.

　　1, the first burst mouth of the surrounding water-cooled wall blowing damage faster;

　　2, the blowing loss of a wider range, a larger surface, the loss of broken tube is also more serious.

　　Before doing the grille anti-wear, its successive anti-wear measures taken.

　　1. Anti-abrasive metal spraying;

　　2. Casting material anti-friction beam;

　　3. Alloy surface fusion welding;

　　According to the actual use effect, the anti-wear beam, metal spraying and surface welding have failed to solve the wear problem completely.

　　Considering the characteristics of supercritical boilers, which are fast blowing loss and serious damage when wear and leakage occurs, the requirements for water-cooled wall protection are more stringent.

　　The customer needs a safe and efficient anti-wear technology to ensure the safe and long-cycle operation of the boiler.

　　Supercritical boiler grill anti-wear application

　　For the characteristics of supercritical boilers, we have made a special optimized design.

　　1, specially designed new anti-dislodging and anti-wear grating to further improve safety;

　　2, optimized the grille anti-wear construction process;

　　3, according to the structure of the furnace chamber and wear characteristics, the design of targeted anti-wear solutions;

　　Construction node introduction.

　　July 2019, the first furnace 2 # boiler grille anti-wear construction;

　　September 2019, the second furnace 3 # boiler grille anti-wear construction;

　　October 2019, the third furnace 1 # boiler grille anti-wear construction;

　　Anti-friction effect.

　　From the operation of the three supercritical boiler grilles in the plant so far, none of the nearly 200,000 pieces of anti-wear plates installed in the three furnaces have fallen off, and their original wear and leakage problems have been fundamentally controlled.

　　In comparison with before and after the grille anti-wear transformation, the original wear-prone area has not seen any thinning, and the earliest transformed 2# furnace has been running smoothly for more than 16 months at high load.

　　After the grid anti-wear transformation, the three furnaces have been running without any water-cooled wall wear and leakage accident, which has greatly extended the boiler operating cycle.

　　The effectiveness and safety of the grid anti-wear technology has been well proven in supercritical boilers.