1. Structure Introduction

The DZH2-1.25-T steam boiler is a single drum vertical water fire tube shell boiler, and the combustion equipment is a movable grate. The water cooled walls on the left and right sides of the furnace are radiative heating surfaces, and the two wings of the furnace are convective heating surfaces. Threaded smoke pipes are arranged inside the drum（ φ fifty-seven × 3.5) For the convective heating surface, the furnace wall is built with refractory bricks, and the part is made of heat-resistant concrete pouring and ramming technology. The outer side of the boiler host is a three-dimensional protective plate shell.

The overall structure of the boiler body adopts an upper boiler drum, with water cooled wall pipes and headers arranged symmetrically on the left and right sides. Drum made of φ one thousand and two hundred × 12 cylinder and φ one thousand and two hundred × The front and rear tube plates of 12 are welded together. The water-cooled wall pipe is φ fifty-one × 3.5 boiler tubes with header φ one hundred and fifty-nine × 6 boiler tubes, the descending tube is φ one hundred and thirty-three × 6 Boiler tubes.

This type of boiler adopts the latest scientific research achievements, such as arched tube plates, threaded smoke pipes, etc., to solve the problems of bulging in the lower part of the shell of the boiler, cracking in the tube plates, low thermal efficiency, and insufficient output.

2. Combustion process

The fuel enters the furnace and is burned on the grate. The generated smoke enters the two wing convection tube bundles along the bottom of the drum through the outlet smoke windows on the octagonal wall, enters the threaded smoke tube through the front smoke box, passes through the economizer and dust collector, and is drawn by the induced draft fan and discharged into the atmosphere through the chimney.

3. Technical characteristics

(1) The boiler drum is composed of an arched tube plate and a threaded smoke pipe, which changes the structure of the boiler drum from a quasi rigid body to a quasi elastic body, eliminates the tension support in the tube plate area, and reduces stress. The smoke tube inside the tube plate has been changed from two returns to a single return, solving the problem of tube plate cracks.

(2) The lower part of the drum is equipped with an ascending tube bank, which eliminates the stagnant water area at the bottom of the drum, making it difficult for sludge to deposit. The high-temperature area of the drum can be well cooled, preventing bulging at the lower part of the drum.

(3) The use of efficient heat transfer threaded smoke pipes has achieved enhanced heat transfer effects, achieving the characteristics of fast boiler temperature rise and pressure rise, and improving the thermal efficiency of the boiler.

(4) Compact in structure, compared to similar boilers, it has a smaller overall size and saves investment in boiler room infrastructure.

(5) Stable operation, convenient adjustment, and sufficient output.

(6) The heat transfer coefficient and thermal efficiency are improved by using threaded smoke pipe to enhance heat transfer, because the smoke has a disturbing effect in the pipe. The smoke pipe is not prone to dust accumulation and plays a self-cleaning role.

(7) The octagonal wall inside the furnace and the outlet smoke window have a certain dust reduction effect. The original dust concentration of the boiler is controlled below the standard, ensuring that the smoke and dust emissions of the boiler meet the national environmental protection regulations.

(8) The unique double layer secondary air design improves the ignition conditions of biomass fuel, adopts an independent air chamber, achieves reasonable air distribution, and forms an aerodynamic field conducive to combustion in the furnace, resulting in high combustion temperature and high combustion efficiency.

2、 Main specifications and design parameters of boilers

1. Boiler evaporation 2.0 t/h

2. Steam pressure 1.25MPa

3. Steam temperature 194 ℃

4. Hydrostatic test pressure 1.65 MPa

5. Feed water temperature 20 ℃

6. Smoke exhaust temperature 149.33 ℃

7. Design thermal efficiency 77.25%

8. Design fuel biomass particles

9. Fuel consumption 680.35kg/h

10. Radiated heating area 10.42m2

11. Convective heating area 45.26m2

12. Economizer heating area 26.4m2

13. Grate area 3.36m2

14. The steel consumption of the boiler body is 3.89t, and the steel consumption of the economizer is 0.918t,

Steel structure steel consumption 4.224t, grate steel consumption 0.764t

15. Total weight of boiler 16.15t

16. Excess air coefficient 1.625

17. Boiler water volume 4.6m3

18. Large transportation weight 12.74t

19. Total power consumption 20.2KW

20. Transportation size of large boiler parts 5140 × two thousand and four hundred × 3200mm

21. Overall dimensions of the boiler host after installation 5140 × three thousand and forty × 4235mm

22. Chimney height φ three hundred and fifty × 30000mm