 500KW燃气发电机组烟气余热回收设计使用特点

1. 余热应用原理

1. Application Principle of Waste Heat

The exhaust gas of a gas-fired generating unit carries a large amount of heat in the process of cleaning from the inside of the unit. The exhaust temperature is generally about 550 C and the flue gas flow rate is 7500-8000m3/h. The waste heat boiler is used to recover the heat from the exhaust gas of the unit, generating 0.6MPa steam for users to use (which can be adjusted according to customers'needs).

2. 设计范围

2. Design Scope

The design scope of this project's waste heat application system includes the design and layout of all pipelines, accessories and equipment of the whole waste heat recovery system from the inlet of the water tank to the steam outlet flange of the waste heat boiler in the power station. 3. 余热计算

3. Calculation of Waste Heat

1m3纯瓦斯热值为35.8MJ，500GFW发电机组热耗率为11MJ/kW·h，正常工作发电功率按500kW计算，单台机组瓦斯耗费量为：

The calorific value of 1 m3 pure gas is 35.8 MJ, and the thermal consumption of 500 GFW generating units is 11 MJ/kW.h. The normal power generation is calculated at 500 kW. The gas consumption of a single unit is:

Q1=500×11/（35.8·a）                              （1）

Q1 = 500*11/(35.8.a) (1)

Type: Q1 - gas consumption per unit (m3/h);

a —甲烷浓度（%），本工程用瓦斯甲烷浓度为20%；

A - methane concentration (%) and methane concentration of gas used in this project is 20%.

Gas consumption per unit: Q1 = 768.2 m3/h

Air flow rate is:

Q2= 10·Q1·a                                       （2）

Q2 = 10. Q1. a (2)

In formula: Q2 - air flow rate (Nm3/h);

a —甲烷浓度（%），本工程用瓦斯甲烷浓度为20%；

A - methane concentration (%) and methane concentration of gas used in this project is 20%.

The air consumption of a single unit is as follows:

Q2=1536.4 Nm3/h

Q2 = 1536.4 Nm3/h

The quality of flue gas discharged by a single unit is as follows:

Q= 0.7174×768.2×20%+[（768.2-768.2×20%）  +1536.4]×28.9/22.4=2885.3kg/h排烟的比热容按烟道气体计算，排烟温度取550℃，（烟道气体的成分CO2 13%，H20 11%，N2 76%，在100 ~600℃的均匀定压比热容为1.13kJ/kg·℃），经余热回收后的排烟温度约为170℃。

Q= 0.7174*768.2*20%+[(768.2-768.2*20%+1536.4]*28.9/22.4=2885.3 kg/h) specific heat capacity of flue gas is calculated according to flue gas. The exhaust temperature is 550 ((CO2 13%, H20 11%, N2 76%). The uniform constant pressure specific heat capacity is 1.13 kJ/kg (?) at 100-600 (?) and the exhaust temperature after waste heat recovery is about 170 kJ/kg (?) C.

The residual heat of exhaust gas can be applied to each unit as follows:

（550-170）×1.134×2885.3=1.2433×106kJ/h。

(550-170)*1.134*2885.3=1.2433*106 kJ/h.

0.6MPa饱和蒸汽温度158.8℃，比焓为2751.69kJ/kg；补给水20℃计算,比焓为84kJ/kg。

The saturated steam temperature of 0.6 MPa is 158.8 C, the specific enthalpy is 2751.69kJ/kg, and the specific enthalpy of recharge water is 84 kJ/kg calculated at 20 C.

Each unit can produce 0.6 MPa of saturated steam

1.2433×106×95%÷（2751.69-84）=442.76 kg/h

1.2433*106*95%(2751.69-84)=442.76 kg/h

It can be seen from the above that the waste heat of exhaust gas can be recovered by 1.2433 *106 kJ/h and the steam output of 0.6 MPa is 442.76 kg/h.