Commonly used methods for estimating boiler flue gas volume

Burning one ton of coal produces 1600 × S% kg of SO2, 10,000 cubic meters of waste gas, and 200 kg of soot.

Burning one ton of diesel fuel produces 2000 × S% kg of SO2, 12,000 cubic meters of waste gas, and 1 kg of soot.

Burning one ton of heavy oil produces 2000 × S% kg of SO2, 16,000 cubic meters of waste gas, and 2 kg of soot.

Large power plants, with good soot control (removal rate exceeding 98%), emit 3-5 kg of soot per ton of coal burned.

Ordinary enterprises, with treatment facilities, emit 10-15 kg of soot per ton of coal burned.

Brick and tile production emits 40-80 kg of soot and 12-18 kg of sulfur dioxide per 10,000 bricks.

Large-scale cement plants emit 3-7 kg of dust and 1 kg of sulfur dioxide per ton of cement produced.

Small township cement plants emit 12-20 kg of dust and 1 kg of sulfur dioxide per ton of cement produced.

Material balance formulas:

SO2 produced by burning 1 ton of coal = 1600 × S kg; S has a sulfur content of generally 0.6-1.5%. If the sulfur content of the coal is 1%, then burning 1 ton of coal emits 16 kg of SO2.

SO2 produced by burning 1 ton of fuel oil = 2000 × S kg; S has a sulfur content of generally 1.5-3% for heavy oil and 0.5-0.8% for diesel. If the sulfur content is 2%, burning 1 ton of oil emits 40 kg of SO2.

Emission coefficients: Burning one ton of coal emits 0.9-1.2 million standard cubic meters of combustion exhaust gas; power plants can use a lower value, while other small plants can use a higher value. Burning one ton of oil emits 1.2-1.6 million standard cubic meters of exhaust gas; diesel uses a lower value, and heavy oil uses a higher value.

**Urban Drainage Conversion Factor:** 0.7-0.9, representing 70-90% of water consumption.

**Domestic Sewage Discharge Factor:** Uses the measured factor for this region.

**COD Generation Factor in Domestic Sewage:** 60g/person/day. Alternatively, use the measured factor for this region.

**Ammonia Nitrogen Generation Factor in Domestic Sewage:** 7g/person/day. Alternatively, use the measured factor for this region. When using these factors for calculations, the population generally refers to the urban population; in areas with a large migrant population, the permanent resident population or the migrant population can be used.

[Emissions of Smoke and Dust from Domestic Use and Other Sources] Calculated using different coefficients for burning domestic briquettes and raw coal:

Domestic Briquettes: 1-2 kg of smoke and dust per ton of briquettes

Raw Coal: 8-10 kg of smoke and dust per ton of raw coal

I. Calculation of Total Industrial Waste Gas Emissions

1. Measurement Method

When waste gas emissions are measured, the following formula is used for calculation:

Q_year = Q_hour × B_year / B_hour / 10000

Where

Q_year—Annual waste gas emissions, 10,000 standard m³/a;

Q_hour—Hourly waste gas emissions, standard m³/h;

B_year—Annual fuel consumption (or clinker production), kg/a;

B_hour—Hourly fuel consumption (or clinker production) under normal operating conditions, kg/h.

2. Coefficient Estimation Method

Calculation of Boiler Combustion Exhaust Gas Emissions

① Calculation of Theoretical Air Requirement (V0)

a. For solid fuels, when the base volatile matter Vy > 15% (bituminous coal), the calculation formula is: V0 = 0.251 × QL/1000 + 0.278 [m3(standard)/kg]

When Vy < 15% (lean coal or anthracite), V0 = QL/4140 + 0.606 [m3(standard)/kg]

When QL < 12546 kJ/kg (low-quality coal), V0 = QL//4140 + 0.455 [m3(standard)/kg]

b. For liquid fuels, the calculation formula is: V0 = 0.203 × QL/1000 + 2 [m3(standard)/kg]

c. For gaseous fuels,

when QL < 10455 kJ/(standard)m3, V0 = 0.209 × QL/1000[m³/m³]

When QL > 14637 kJ/(standard)m³, V0 = 0.260 × QL/1000 - 0.25[m³/m³]

Where: V0—Theoretical air required for fuel combustion, m³(standard)/kg or m³/m³;

QL—Lower heating value of fuel on an application basis, kJ/kg or kJ/(standard)m³.

QL value comparison table for various fuel types (unit: kJ/kg or kJ/standard m³)

Table of QL values for different fuel types (unit: kJ/kg or kJ/standard m³)

② Calculation of actual flue gas volume

a. For anthracite, bituminous coal, and lean coal:

Qy = 1.04 × QL/4187 + 0.77 + 1.0161(α-1) V0 [m³(standard)/kg]

When QL < 12546 kJ/kg (low-quality coal), Qy = 1.04 × QL/4187 + 0.54 + 1.0161(α-1) V0 [m³(standard)/kg]

b. For liquid fuels:

Qy = 1.11 × QL/4187 + (α-1) V0 [m³(standard)/kg]

c. For gaseous fuels,

When QL < 10468 kJ/(standard) m³: Qy = 0.725 ×QL/4187+1.0+(α-1) V0(m3/m3)

When QL>10468 kJ/(standard)m3, Qy=1.14 ×QL/4187-0.25+(α-1) V0(m3/m3)

Where: Qy—actual flue gas volume, m3(standard)/kg;

α—excess air coefficient, α = α0+Δα

Furnace excess air coefficient

Boiler type Bituminous coal Anthracite Oil Gas

Hand-fired and blast furnace coal-fired boilers 1.40 1.65 1.20 1.106

Chain grate boilers 1.35 1.40

Pulverized coal boilers 1.20 1.25

Fluidized bed boilers 1.25 1.25

Note: For other mechanically combusted boilers, regardless of the fuel, α0 is taken as 1.31. Leakage coefficient Δα value

Leakage location Furnace Convection tube bundle Superheater

Economizer Air preheater Dust collector Steel flue (per 10 meters) Brick flue (per 10 meters Δα 0.1 0.15 0.05 1.65 0.1 0.05 0.01 0.05

③ Calculation of total flue gas volume Qtotal = B × Qy

Where: Qtotal—total flue gas volume, m3 (standard)/y;

B—fuel consumption;

Qy—actual flue gas volume, m3 (standard)/kg.

2) Calculation of flue gas volume discharged from cement rotary kiln: s0

① The flue gas volume discharged from cement rotary kiln is generally selected according to the following empirical data:

a. Wet rotary kiln 3.5~4m3 (standard)/kg clinker

b. Dry rotary kiln 2.4m3 (standard)/kg clinker

c. Single-pass vertical wave kiln 5 m³ (standard)/kg clinker

d. Secondary pass through vertical wave kiln: 4 m³ (standard)/kg clinker, of which 3 m³ (standard)/kg clinker is before the hot exhaust fan

e. Vertical preheating kiln: 2.4 m³ (standard)/kg clinker

f. Cyclone preheating kiln: 2.3 m³ (standard)/kg clinker

② Estimation of cement vertical kiln exhaust gas volume! Calculation formula:

n9 X(vQ/year = M × Qa × K1 × K2 Where: Q_year—Annual waste gas emission from vertical kiln, m³ (standard)

M—Annual clinker production from vertical kiln, kg

V—Standard coal conversion table for various fuels

Qa—Waste gas generation per unit of clinker, m³ (standard)/kg (clinker), generally 1.6~2.0 m³ (standard)/kg (clinker);

K1—Production unevenness coefficient, K1=1.0 for mechanized vertical kiln, K1=1.3~1.5 for ordinary vertical kiln;

K2—Air leakage coefficient, K2=1.15~1.25 for mechanized vertical kiln, K2=1.3~1.4 for ordinary vertical kiln

③ Calculation of waste gas from non-clinker burning in cement production

In the cement production process, in addition to cement clinker burning, a certain amount of waste gas is also generated during raw material crushing, drying, packaging, grinding, etc. Generally, 1.5 kilograms of clinker emit this type of waste gas. m3 (standard).

Note: Standard coal is an equivalent concept based on a specific calorific value. The lower heating value of 1 kg of standard coal is defined as 7000 kcal or 29274 kJ. If the lower heating value of the fuel is unavailable, the coefficients in the table above can be used for calculation. If the lower heating value Q is available, it can be calculated using the following formula:

Standard coal quantity = Fuel consumption * Q / 7000 (Lower heating value in kcal)

Standard coal quantity = Fuel consumption * Q / 29274 (Lower heating value is calculated in kilojoules)

Calculation of Solid Waste (S)

Calculation of Fly Ash and Slag Production

S is the solid matter formed by coal combustion. The solid matter collected from the dust collector is called fly ash, and the solid matter discharged from the furnace is called slag. The amount of ash and slag produced by boiler combustion is related to the ash content of the coal and the incomplete combustion conditions of the boiler.

The amount of ash and slag produced is often calculated using the ash and slag balance method. The following calculation formula can be derived from the ash and slag balance formula:

Boiler Slag Production (GZ):

Boiler Fly Ash Production (Gf):

Where: B—Boiler coal consumption, t/a

A—Application-based ash content of coal;

η—Dust removal efficiency, % CZ and Cf represent the percentage of combustible matter in slag and fly ash, respectively. Generally, CZ = 10%~25%, and 0~5% for pulverized coal suspension burners; Cf = 15%~45%, and 4%~8% for fly ash in thermal power plants. CZ and Cf can also be selected based on boiler heat balance data or obtained from laboratory tests.

Tdz and dfh represent the percentage of ash in slag and fly ash in the total ash content of the coal, respectively. dz = 1 - dfh. When burning coking bituminous coal, lignite, or coal slime, the dfh value can be lower, while it should be higher when burning anthracite.