NB/T 47060-2017The rotary air preheater (English PDF)

1.1

This standard specifies the requirements for model and parameters, materials, design, manufacturing, inspection and acceptance, painting, packaging and marking, transportation, lifting and storage, site installation and performance test of rotary air preheater.

1.2

This standard is applicable to rotary air preheater with flue gas inlet temperature lower than or equal to 450°C and rotor diameter greater than 4,000mm and less than or equal to 24,000mm.

3.1 Model

3.1.1 Model preparation method

The model of rotary air preheater consists of four parts, i.e. manufacturer code, category code, model code and section number, which are connected by dash in the following form:

3.1.2 Model preparation example

For a rotating-rotor air preheater manufactured by ××, which has a production model code of 24.0, section number of III, it's model is ××-H-24.0-III.

3.2 Parameters

See Table 1 for model code and common parameter series of rotary air preheater.

Table 1 Model code and common parameter series

S.N. Model code Reference section number Rotor diameter reference value/mm

1 19.0 24 4,200

2 19.5 24 4,350

3 20.0 24 4,550

4 20.5 24 4,800

5 21.0 24 5,000

6 21.5 24 5,200

7 22.0 24 5,500

8 22.5 24 5,800

9 23.0 24 6,100

10 23.5 24 6,300

11 24.0 36, 48 6,600

12 24.5 36, 48 6,900

13 25.0 36, 48 7,200

14 25.5 36, 48 7,600

15 26.0 36, 48 7,900

16 26.5 36, 48 8,300

17 27.0 36, 48 8,650

18 27.5 36, 48 9,000

19 28.0 36, 48 9,500

20 28.5 36, 48 10,000

21 29.0 48 10,400

22 29.5 48 11,000

23 30.0 48 11,300

24 30.5 48 11,800

25 31.0 48 12,400

26 31.5 48 13,000

27 32.0 48 13,500

28 32.5 48 14,300

29 33.0 48 15,000

30 33.5 48 15,700

31 34.0 48 16,400

32 34.5 48 17,300

33 35.0 48, 60 18,100

34 35.5 48, 60 19,000

35 36.0 48, 60, 96 19,900

36 36.5 48, 60, 96 21,000

37 37 48, 60, 96 22,000

38 37.5 48, 60, 96 23,000

39 38 48, 60, 96 24,000

4.2

Where the flue gas temperature at inlet of rotary air preheater is higher than 430°C, the members at hot end shall be made of low alloy steel (Grade Q345), and the heat transfer element frame at cold end shall be made of corrosion-resistant low alloy steel based on the characteristics of fuel and flue gas.

4.3

The base material of enamelled heat transfer elements shall meet the requirements of GB/T 13790.

4.4

The raw materials may not be used for manufacturing until passing the factory acceptance, and shall be marked and transplanted according to relevant requirements so as to prevent mixing use of materials. Material substitution shall be approved according to standard procedures.

5.1

The design of rotary air preheater shall include the following basic conditions:

a) altitude for installation;

b) flow, temperature and pressure of flue gas inlet;

c) inlet temperature, outlet flow and outlet pressure of primary and secondary air;

d) flow and mixing temperature of primary air entering into the coal mill;

e) number and arrangement mode (vertical or horizontal) of rotary air preheaters and number of sections (generally, section II, III or IV) equipped for each boiler;

f) limit requirements for parameters of rotary air preheater: smoke exhaust temperature (without air leakage correction), side resistance of flue gas and air leakage rate of rotary air preheater under assessment conditions;

g) data of industrial analysis, elemental analysis and ash characteristic analysis on design and check fuel, coefficient of excess air at the flue gas inlet of rotary air preheater, or the composition of flue gas entering into rotary air preheater;

h) protection means adopted for cold end of rotary air preheater, such as steam air heater or hot air recirculation.

When necessary, SO2/SO3 conversion rate of denitrification system, ammonia escape concentration and inlet flow field distribution of flue gas and air of air preheater shall also be considered.

5.2

Type selection design of rotary air preheater shall be carried out based on the basic conditions to determine parameters such as diameter, heat exchange area, waveform of heat transfer element and height of enamelled heat transfer elements at cold end.

5.3

Structural design of rotary air preheater shall be carried out on the basis of type selection design to determine the overall dimension, driving or transmission mode and control system of air preheater.

5.4

Where a boiler is equipped with two rotary air preheaters, the output of a single rotary air preheater shall reach 60% the maximum continuous load of the boiler.

5.5

Central driving mode or shroud band transmission may be adopted for the rotary air preheater. The driving device of each rotary air preheater includes a set of main motor and a set of auxiliary motor, and soft start mode is adopted. The power of driving motor shall be provided with allowance and shall not be overloaded. When the main motor operates, the auxiliary motor shall not operate. When the main motor is out of operation, the auxiliary motor shall come into service through interlocking; when the main motor or auxiliary motor fails, the alarm device shall give an alarm.

5.6

The rotor of rotary air preheater shall be of modular compartment structure. Heat storage assemblies should be made into smaller ones for maintenance and replacement, and the influence of denitration shall be considered for heat storage assemblies at cold end.

5.7

The rotary air preheater shall be equipped with radial, axial and circumferential sealing systems.

5.8

The design of rotary air preheater shall meet the requirements that the heat transfer elements will not condense or clogged under various working conditions, and an effective soot blowing device shall be provided. The temperature of soot blowing steam source should be 300~350°C, and the steam flow of single barrel is generally greater than or equal to 5t/h; the outlet pressure of high-pressure water is generally 10~30MPa, and the water flow of a single barrel is generally 8~10t/h.

5.9

The rotary air preheater shall be equipped with hand-barring. A pneumatic motor may be configured as required by the user, and the noise at 1m away from the transmission device shall not exceed 85dB.

5.10

The rotary air preheater shall be provided with lighting peephole, effective and reliable fire alarm device, shutdown alarm device, fire-fighting system and cleaning system, and may also be equipped with dew point measuring device.

5.11

When the rotary air preheater is shut down, measures shall be taken to prevent deformation and smoke leakage. In case of double-row arrangement, isolation baffles shall be arranged in appropriate positions at the inlet of flue gas and air side, and the baffle shall be moved flexibly and reliably.