Refractory materials for the lining of circulating fluidized bed boiler have experienced five stages successively:

The first stage is shaped refractory products;

The second stage is clay bonded castable;

The third stage is high alumina refractory castable with phosphoric acid, polyphosphate, water glass, pure calcium aluminate cement as binder;

Although the wear-resistant and refractory materials in the fourth stage have improved their performance compared with the first two, due to the high CaO content in the binder and the high content of impurities in the high aluminum raw materials, it is difficult to guarantee the construction performance, which leads to high porosity, low strength and poor wear-resistance of the refractory materials under high temperature;

The fifth stage is to successfully develop corundum series wear-resistant castables (vibration castables and gravity castables) with low cement, ultra-low cement and no cement based on the above materials

What are the necessary conditions for starting the boiler lining?

1. In principle, the following conditions shall be met when the refractory materials are formally delivered for construction:

(1) The installation of steel structures, heating surfaces, furnace wall metal parts, external protective steel plates and other devices at each construction position has passed the acceptance, including the smooth grinding of welds, qualified air tightness inspection, qualified hydrostatic test, etc;

(2) All steel frame platforms and ladders have been installed, and the conditions for material transportation and installation have been met;

(3) All temporary components and supports installed on the steel structure have been removed;

(4) The door hole, air hole, process instrument, ignition device and expansion joint of each construction part have been installed in place;

(5) Each construction point has water and electricity access;

(6) The construction site shall be provided with a place for storage of moisture-proof, rainproof and sun proof refractory materials;

(7) It is specially required that the construction water for refractory material pouring must meet the basic requirements of pH 6.0-8.0. It is strictly prohibited to use seawater, alkaline water and non drinking water containing organic floating objects.

2. Before construction, the construction organization design document shall be carefully prepared according to the design requirements, which mainly includes: project overview, organization, labor plan, equipment configuration, comprehensive project schedule, project quality and safety assurance/control measures, civilized construction management, etc.

3. Before construction, relevant personnel shall be organized to carefully read and get familiar with the drawings and relevant technical data, and go to the site to check the elevation and size of the relevant fasteners/hangers/anchors, brick supports, air holes, instrument holes, igniters and auxiliary combustion devices, door holes, expansion joints, etc. of the boiler, and actively take corresponding measures; Timely put forward improvement suggestions for problems that will affect lining construction and future equipment operation in design and body installation, and work with relevant units and departments to study and properly solve them.

4. Prepare materials and construction in advance according to the construction organization design and relevant technical requirements, and take technical measures such as damp proof, rain proof, sun protection, cold proof and warm keeping or cooling and heat relieving according to seasonal characteristics and ambient temperature.

5. Ensure "three supplies and one leveling", and determine the water source, power supply, transportation and material stacking place. The construction water shall be clean and meet the specified requirements.

To ensure that the service life of the boiler lining exceeds 3 years, it is not only necessary to select a good lining material, but also requires the construction personnel to control the furnace building process, such as the production of hanging parts, the reservation of expansion joints, the support of mold plates, and the drying of the furnace after construction. If there is no good professional furnace building construction team, no matter how good the materials are, it is difficult to ensure that CFB boilers will not have quality problems.

1. The required materials shall be transported to the construction site, stacked by category and marked.

2. Clean the forced mixer and vibrator, install them in place and operate normally.

3. After cleaning the forced mixer, install the anchors to be used, and use fire-resistant fiber felt, light insulating refractory brick or light castable as the thermal insulation layer.

4. The formwork shall be set according to the thickness of lining. The inner surface of the wooden formwork shall be lined with felt paper. The steel formwork shall be oiled to remove the formwork and ensure smooth lining. The formwork height of furnace wall shall not be greater than 1m.

5. The mixture must be carried out in a forced mixer. According to the requirements of mixing proportion, put the mixture into the mixer for dry mixing for 1 minute, and then add clean water or chemical agent with good density into the mixture for mixing for 2-3 minutes. For phosphate refractory castables, 1/2 of the binder shall be added to the wet mix at the same time. After 24 hours, the remaining adhesive is used for wet mixing.

6. Pour the mixture into the formwork and concentrate the cloth. The thickness of the material layer is 300~400mm. A 3mm wide expansion joint shall be placed every 2-3 meters, and plastic sealant shall be inserted. The mixed material shall be used within 1 hour.

7. Plug in vibrator or plate vibrator shall be used for pouring. During the vibration of the insertion layer, the rod shall be continuously pulled, but cannot be anchored, insulated and formwork. After the surface returns to the slurry, slowly pull out the vibrating rod.

8. When vibrating again, the vibrating rod shall be inserted into the vibrating material layer for about 100mm to make the upper and lower layers form a whole.

9. The construction shall be carried out continuously, but the expansion joints of the lining shall allow longer intervals.

10. Manual vibration shall be used when pouring light refractory castables on the furnace top.

11. The metal part of the hanging brick must be exposed and the insulation must not be buried. After the initial solidification of the cement castable, the straw bag shall be covered with water, and the cement, chemical materials, clay shall be kept in a natural state after being combined with the refractory castable, and water spraying is not allowed.

12. The thickness of the lining shall not exceed 5mm of the fixing pin

13. The oven must be operated according to the requirements of the oven curve. The baking time is about 7 days. It shall be heated slowly before 600 ℃ and once at 150 ℃, 350 ℃ and 600 ℃. When the moisture content in the lining is basically eliminated, the temperature is slowly dried from 600 ℃ to the temperature. The ambient temperature of the building shall not be lower than 5 ℃.

14. A batch of samples shall be formed every day and placed near the kiln for protection, so as to be ready for quality inspection.