CN102567637B - Method for calculating fuel combustion and heat balance in O2/CO2 atmosphere - Google Patents

Abstract

The invention discloses a method for calculating fuel combustion and heat balance in O2/CO2 atmosphere. The method comprises the following steps of: (1) calculating fuel combustion; and (2) calculating the heat balance of a boiler. Related parameters and correlations in the traditional thermodynamic calculation method are changed, combustion calculation, flue gas characteristic calculation and flue gas enthalpy calculation in fuel combustion calculation are mainly researched, and heat balance calculation is also performed, so that a calculation formula is suitable for an O2/CO2 combustion mode under different oxygen concentrations. The solving result of the method can be used as the reference of researching the O2/CO2 combustion process in detail and designing the boiler by a combustion technology.

Description

O 2/ CO 2the lower fuel combustion reckoning of atmosphere burning and thermal equilibrium projectional technique

Technical field

The present invention relates to the field of boilers of Thermal Power Engineering, particularly the lower fuel combustion reckoning of O2/CO2 atmosphere burning and thermal equilibrium projectional technique.

Background technology

Carbon isolation processing is considered to reduce one of best approach of building up in an atmosphere of greenhouse gases.And the CO2 obtaining high concentration is the current prerequisite realizing carbon isolation, reduce discharging CO2.In the flue gas that regular air combustion system produces, the concentration of CO2 only has about 15%, reclaims CO2 and will pay high economic cost.In order to obtain the high concentration CO 2 without the need to being separated with lower expense, develop a kind of new combustion mode, i.e. O2/CO2 combustion technology from the angle of burning.This technology uses O2/CO2 mixed gas in combustion system, makes the CO2 concentration in flue gas rise to 95%.Adopt this combustion system can also reduce SO2 and NOx emission significantly, thus realize the cooperation-removal of the integration of pollutant.Clean as one, the efficient coal-fired power generator set of O2/CO2 combustion technology, has become worldwide study hotspot.

At present, the thermodynamic computing analytical approach of national and foreign standards is all formulate for the coal-burning boiler of routine, and comprise the standard of USSR (Union of Soviet Socialist Republics) and the ASME standard etc. of the U.S., these thermodynamic analysis methods draw according to large-scale power station combustion characteristics under air.And O2/CO2 combustion technology replaces air with O2 and CO2 in combustion system, compared with conventional combustion, smoke components has very big difference, heat transfer characteristic also will change, and flame temperature and stability during for burning under raising O2/CO2 atmosphere, the oxygen concentration in mixed combustion atmosphere generally need bring up to about 30%.

Summary of the invention

The object of the invention is the shortcoming and defect overcoming prior art, fuel combustion reckoning under providing O2/CO2 atmosphere to burn and thermal equilibrium projectional technique, solve and conventional heat computing method correlation parameter, correlation are changed, the O2/CO2 combustion system combustion system under making it be applicable to different oxygen concentration.

The technical solution adopted for the present invention to solve the technical problems is:

The lower fuel combustion reckoning of O2/CO2 atmosphere burning and thermal equilibrium projectional technique, comprise the steps:

(1) Calculating Fuelv combustion step

Calculating Fuelv combustion, based on the combustion amount of unit volume, comprising: burning calculates, flue gas characteristic calculates and flue gas enthalpy calculates, its step:

(1) O ₂/ CO ₂the calculating of atmosphere amount

$V^0=\frac{1.866}{x}(\frac{C_{\mathrm{ar}}}{100}+0.375\frac{S_{\mathrm{ar}}}{100})+\frac{5.598}{x}\frac{H_{\mathrm{ar}}}{100}-\frac{0.700}{x}\frac{O_{\mathrm{ar}}}{100}$

In formula, C _ar, H _ar, S _ar, O _arbe respectively carbon in fuel, hydrogen, sulphur, oxygen receive base unit weight; X is the oxygen concentration in O2/CO2 atmosphere, %;

(2) calculating of RO2 volume

$V_{{\mathrm{RO}}_2}^0=1.866(\frac{C_{\mathrm{ar}}}{100}+0.375\frac{S_{\mathrm{ar}}}{100})+{(1-x)}_{V^0}$

(3) calculating of N2 volume

$V_{N_2}=0.8\frac{N_{\mathrm{ar}}}{100}$

In formula, N _arbase unit weight is received for nitrogen in fuel;

(4) calculating of water capacity

Under the status of criterion, the density of dry O2/CO2 atmosphere is:

${\mathrm{\ρ}}_g=\frac{32}{22.4}\×x+\frac{44}{22.4}\×(1-x)$

The steam vapour amount that then O2/CO2 atmosphere is brought is:

$d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g$

In formula, d is the quality of water vapour contained in the O2/CO2 atmosphere of 1kg, kg/kg;

Therefore water vapor volume is:

$V_{H_{2}O}^0=11.1\frac{H_{\mathrm{ar}}}{100}+1.24\frac{W_{\mathrm{ar}}}{100}+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g\×V^0$

In formula, W _arfor moisture in fuel;

(5) calculating of wet flue gas amount

$V_y^0=V_{H_{2}O}^0+V_{{\mathrm{RO}}_2}^0+V_{N_2}$

(6) calculating of actual wet flue gas amount

$V_y=V_y^0+(\mathrm{\α}-1)V^0+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g(\mathrm{\α}-1)V^0$

In formula, α is the average excessive oxygen rich air coefficient of heating surface outlet;

(7) volume flying dust concentration

μ＝10A _arα _th/V _y

In formula, A _arfor the ash content of fuel; α _thfor flying dust share;

(8) flue gas mass

$m_y=1-\frac{A_{\mathrm{ar}}}{100}+{\mathrm{\ρ}}_s\mathrm{\α}{V}^0$

In formula, ρ _sfor the density of wet O2/CO2 atmosphere;

${\mathrm{\ρ}}_s={\mathrm{\ρ}}_g+2.24d\×\frac{18}{22.4}$

(9) enthalpy of wet O2/CO2 atmosphere

${\left(\mathrm{c\θ}\right)}^0=(1-x){\left(\mathrm{c\θ}\right)}_{C_{2}O}+x{\left(\mathrm{c\θ}\right)}_{O_2}+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_{g{\left(\mathrm{c\θ}\right)}_{H_{2}O}}$

$h^0=V^0{\left(\mathrm{c\θ}\right)}^0$

In formula, 1m3 carbon dioxide in flue gas, oxygen, the enthalpy of water vapor when temperature θ DEG C respectively;

(10) enthalpy of flue gas

$h_y^0=V_{{\mathrm{RO}}_2}^0{\left(\mathrm{c\θ}\right)}_{{\mathrm{RO}}_2}+V_{N_2}{\left(\mathrm{c\θ}\right)}_{N_2}+V_{{\mathrm{HO}}_2}^0{\left(\mathrm{c\θ}\right)}_{H_{2}O}$

In formula, the enthalpy in flue gas when temperature θ DEG C respectively;

Due to and both specific heat capacities are close, therefore get

(11) actual flue gas enthalpy

$h_y=h_y^0+(\mathrm{\α}-1)h^0+h_{\mathrm{fh}}$

Wherein, h _fhfor flying dust enthalpy, be calculated as follows

$h_{\mathrm{fh}}=\frac{A_{\mathrm{ar}}}{100}{\mathrm{\α}}_{\mathrm{fh}}{\left(\mathrm{c\θ}\right)}_h$

In formula, (c θ) _hthe enthalpy of 1kg ash when temperature θ DEG C.

(2) boiler heat balance calculates

(1) boiler thermal output

η＝100-q ₂-q ₃-q ₄-q ₅-q ₆

In formula: q ₂, q ₃, q ₄, q ₅, q ₆be respectively heat loss due to exhaust gas, the incomplete thermal loss of gas, machinery not exclusively thermal loss, radiation loss, heat loss due to sensible heat in slag;

(2) heat loss due to exhaust gas

$q_2=(h_{\mathrm{py}}-{\mathrm{\α}}_{\mathrm{py}}{V}^0\left(\mathrm{ct}\right))\left(\frac{100-q_4}{Q_r}\right)$

In formula, h _pyfor the enthalpy of flue gas under exhaust gas temperature;

Wherein, α _pyfor the excess air coefficient of smoke evacuation place, be calculated as follows:

${\mathrm{\α}}_{\mathrm{py}}=\frac{x}{x-(1-x)\×\frac{O_{2y}-0.5C{O}_y}{100-({\mathrm{RO}}_{2y}+O_{2y}+{\mathrm{CO}}_y)}}$

In formula, O _2y, CO _y, RO _2yfor oxygen, carbon monoxide, RO in smoke evacuation ₂volume share, %.

The present invention solves and changes conventional heat computing method correlation parameter, correlation, the O2/CO2 combustion system combustion system under making it be applicable to different oxygen concentration.

Embodiment

Below in conjunction with the description calculating of certain boiler domestic being made to more project to the present invention.The rated capacity of this boiler is 220t/h, and with 80% load operation, feed temperature is 215 DEG C, superheated vapor pressure 9.8MPa DEG C, and superheat steam temperature is 540 DEG C, and environment temperature is 20 DEG C, and exhaust gas temperature is 133 DEG C.

1, O ₂/ CO ₂fuel combustion reckoning under atmosphere burning and thermal equilibrium projectional technique, is characterized in that comprising the steps:

(1) Calculating Fuelv combustion step

Calculating Fuelv combustion, based on the combustion amount of unit volume, comprising: burning calculates, flue gas characteristic calculates and flue gas enthalpy calculates, its step:

(1) O ₂/ CO ₂the calculating of atmosphere amount

$V^0=\frac{1.866}{x}(\frac{C_{\mathrm{ar}}}{100}+0.375\frac{S_{\mathrm{ar}}}{100})+\frac{5.598}{x}\frac{H_{\mathrm{ar}}}{100}-\frac{0.700}{x}\frac{O_{\mathrm{ar}}}{100}$

In formula, C _ar, H _ar, S _ar, O _arbe respectively carbon in fuel, hydrogen, sulphur, oxygen receive base unit weight; X is the oxygen concentration in O2/CO2 atmosphere, %;

(2) calculating of RO2 volume

$V_{{\mathrm{RO}}_2}^0=1.866(\frac{C_{\mathrm{ar}}}{100}+0.375\frac{S_{\mathrm{ar}}}{100})+{(1-x)}_{V^0}$

(3) calculating of N2 volume

$V_{N_2}=0.8\frac{N_{\mathrm{ar}}}{100}$

In formula, N _arbase unit weight is received for nitrogen in fuel;

(4) calculating of water capacity

Under the status of criterion, the density of dry O2/CO2 atmosphere is:

${\mathrm{\ρ}}_g=\frac{32}{22.4}\×x+\frac{44}{22.4}\×(1-x)$

The steam vapour amount that then O2/CO2 atmosphere is brought is:

$d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g$

In formula, d is the quality of water vapour contained in the O2/CO2 atmosphere of 1kg, kg/kg;

Therefore water vapor volume is:

$V_{H_{2}O}^0=11.1\frac{H_{\mathrm{ar}}}{100}+1.24\frac{W_{\mathrm{ar}}}{100}+d\×\frac{\text{1}}{0.804}\×{\mathrm{\ρ}}_g\×V^0$

In formula, W _arfor moisture in fuel;

(5) calculating of wet flue gas amount

$V_Y^0=V_{H_{2}O}^0+V_{{\mathrm{RO}}_2}^0+V_{N_2}$

(6) calculating of actual wet flue gas amount

$V_y=V_y^0+(\mathrm{\α}-1)V^0+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g(\mathrm{\α}-1)V^0$

In formula, α is the average excessive oxygen rich air coefficient of heating surface outlet;

(7) volume flying dust concentration

μ＝10A _arα _fh/V _y

In formula, A _arfor the ash content of fuel; α _fhfor flying dust share;

(8) flue gas mass

$m_y=1-\frac{A_{\mathrm{ar}}}{100}+{\mathrm{\ρ}}_s\mathrm{\α}{V}^0$

In formula, ρ _sfor the density of wet O2/CO2 atmosphere;

${\mathrm{\ρ}}_s={\mathrm{\ρ}}_g+2.24d\×\frac{18}{22.4}$

(9) enthalpy of wet O2/CO2 atmosphere

${\left(\mathrm{c\θ}\right)}^0=(1-x){\left(\mathrm{c\θ}\right)}_{C_{2}O}+x{\left(\mathrm{c\θ}\right)}_{O_2}+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g{\left(\mathrm{c\θ}\right)}_{H_{2}O}$

h ⁰＝V ⁰(cθ) ⁰

In formula, 1m3 carbon dioxide in flue gas, oxygen, the enthalpy of water vapor when temperature θ DEG C respectively;

(10) enthalpy of flue gas

$h_y^0=V_{{\mathrm{RO}}_2}^0{\left(\mathrm{c\θ}\right)}_{{\mathrm{RO}}_2}+V_{N_2}{\left(\mathrm{c\θ}\right)}_{N_2}+{V_{\mathrm{HO}}^0}_2{\left(\mathrm{c\θ}\right)}_{H_{2}O}$

In formula, the enthalpy in flue gas when temperature θ DEG C respectively;

Due to and both specific heat capacities are close, therefore get

(11) actual flue gas enthalpy

$h_y=h_y^0+(\mathrm{\α}-1)h^0+h_{\mathrm{fh}}$

Wherein, h _fhfor flying dust enthalpy, be calculated as follows

$h_{\mathrm{fh}}=\frac{A_{\mathrm{ar}}}{100}{\mathrm{\α}}_{\mathrm{fh}}{\left(\mathrm{c\θ}\right)}_h$

In formula, (c θ) _hthe enthalpy of 1kg ash when temperature θ DEG C.

(2) boiler heat balance calculates

(1) boiler thermal output

η＝100-q ₂-q ₃-q ₄-q ₅-q ₆

In formula: q ₂, q ₃, q ₄, q ₅, q ₆be respectively heat loss due to exhaust gas, the incomplete thermal loss of gas, machinery not exclusively thermal loss, radiation loss, heat loss due to sensible heat in slag;

(2) heat loss due to exhaust gas

$q_2=(h_{\mathrm{py}}-{\mathrm{\α}}_{\mathrm{py}}{V}^0\left(\mathrm{ct}\right))\left(\frac{100-q_4}{Q_r}\right)$

In formula, h _pyfor the enthalpy of flue gas under exhaust gas temperature;

Wherein, α _pyfor the excess air coefficient of smoke evacuation place, be calculated as follows:

${\mathrm{\α}}_{\mathrm{py}}=\frac{x}{x-(1-x)\×\frac{O_{2y}-{0.5\mathrm{CO}}_y}{100-({\mathrm{RO}}_{2y}+O_{2y}+{\mathrm{CO}}_y)}}$

In formula, O _2y, CO _y, RO _2yfor oxygen, carbon monoxide, RO in smoke evacuation ₂volume share, %.

As mentioned above, just the present invention can be realized preferably.

Above-described embodiment is only the present invention's preferably embodiment; but embodiments of the present invention are not restricted to the described embodiments; other are any do not deviate from Spirit Essence of the present invention and principle under do change, modification, substitute, combine, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (1)

1.O ₂/ CO ₂the lower fuel combustion reckoning of atmosphere burning and thermal equilibrium projectional technique, is characterized in that comprising the steps:

(1) Calculating Fuelv combustion step

Calculating Fuelv combustion, based on the combustion amount of unit volume, comprising: burning calculates, flue gas characteristic calculates and flue gas enthalpy calculates, its step:

(1) O ₂/ CO ₂the calculating of atmosphere amount

$V^0=\frac{1.866}{x}(\frac{C_{\mathrm{ar}}}{100}+0.375\frac{S_{\mathrm{ar}}}{100})+\frac{5.598}{x}\frac{H_{\mathrm{ar}}}{100}-\frac{0.700}{x}\frac{O_{\mathrm{ar}}}{100}$

In formula, C _ar, H _ar, S _ar, O _arbe respectively carbon in fuel, hydrogen, sulphur, oxygen receive base unit weight; X is O ₂/ CO ₂oxygen concentration in atmosphere, %;

(2) RO ₂the calculating of volume

$V_{{\mathrm{RO}}_2}^0=1.866(\frac{C_{\mathrm{ar}}}{100}+0.375\frac{S_{\mathrm{ar}}}{100})+{(1-x)}_{V^0}$

(3) N ₂the calculating of volume

$V_{N_2}=0.8\frac{N_{\mathrm{ar}}}{100}$

In formula, N _arbase unit weight is received for nitrogen in fuel;

(4) calculating of water capacity

Under the status of criterion, dry O ₂/ CO ₂the density of atmosphere is:

${\mathrm{\ρ}}_g=\frac{32}{22.4}\×x+\frac{44}{22.4}\×(1-x)$

Then O ₂/ CO ₂the steam vapour amount that atmosphere is brought is:

$d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g$

In formula, d is the O of 1kg ₂/ CO ₂the quality of water vapour contained in atmosphere, kg/kg;

Therefore water vapor volume is:

$V_{H_{2}O}^0=11.1\frac{H_{\mathrm{ar}}}{100}+1.24\frac{W_{\mathrm{ar}}}{100}+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g\×V^0$

In formula, W _arfor moisture in fuel;

(5) calculating of wet flue gas amount

$V_y^0=V_{H_{2}O}^0+V_{{\mathrm{RO}}_2}^0+V_{N_2}$

(6) calculating of actual wet flue gas amount

$V_y=V_y^0+(\mathrm{\α}-1)V^0+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g(\mathrm{\α}-1)V^0$

In formula, α is the average excessive oxygen rich air coefficient of heating surface outlet;

(7) volume flying dust concentration

μ＝10A _arα _fh/V _y

In formula, A _arfor the ash content of fuel; α _fhfor flying dust share;

(8) flue gas mass

$m_y=1-\frac{A_{\mathrm{ar}}}{100}+{\mathrm{\ρ}}_s\mathrm{\α}{V}^0$

In formula, ρ _sfor wet O ₂/ CO ₂the density of atmosphere;

${\mathrm{\ρ}}_s={\mathrm{\ρ}}_g+2.24d\×\frac{18}{22.4}$

(9) wet O ₂/ CO ₂the enthalpy of atmosphere

${\left(\mathrm{c\θ}\right)}^0=(1-X){\left(\mathrm{c\θ}\right)}_{{\mathrm{CO}}_2}+X{\left(\mathrm{c\θ}\right)}_{O_2}+d\×\frac{1}{0.804}\×{\mathrm{\ρ}}_g{\left(\mathrm{c\θ}\right)}_{H_{2}O}{h}^0{=V}^0{\left(\mathrm{c\θ}\right)}^0$

In formula, 1m in flue gas respectively ³carbon dioxide, oxygen, water vapor are in temperature time enthalpy;

(10) enthalpy of flue gas

$h_y^0=V_{{\mathrm{RO}}_2}^0{\left(\mathrm{c\θ}\right)}_{{\mathrm{RO}}_2}+V_{N_2}{\left(\mathrm{c\θ}\right)}_{N_2}+V_{H_{2}O}^0{\left(\mathrm{c\θ}\right)}_{H_{2}O}$

In formula, 1m in flue gas respectively ³dioxide, nitrogen is in temperature time enthalpy;

Due to and both specific heat capacities are close, therefore get

(11) actual flue gas enthalpy

$h_y=h_y^0+(\mathrm{\α}-1)h^0+h_{\mathrm{fh}}$

Wherein, h _fhfor flying dust enthalpy, be calculated as follows

$h_{\mathrm{fh}}=\frac{A_{\mathrm{ar}}}{100}{\mathrm{\α}}_{\mathrm{fh}}{\left(\mathrm{c\θ}\right)}_h$

In formula, that 1kg ash is in temperature time enthalpy;

(2) boiler heat balance calculates

(1) boiler thermal output

η＝100-q ₂-q ₃-q ₄-q ₅-q ₆

In formula: q ₂, q ₃, q ₄, q ₅, q ₆be respectively heat loss due to exhaust gas, the incomplete thermal loss of gas, machinery not exclusively thermal loss, radiation loss, heat loss due to sensible heat in slag;

(2) heat loss due to exhaust gas

$\begin{array}{cc}{q}_2=(h_{\mathrm{py}}-{\mathrm{\α}}_{\mathrm{py}}{V}^0\left(\mathrm{ct}\right))& \left(\frac{100-q_4}{Q_r}\right)\end{array}$

In formula, h _pyfor the enthalpy of flue gas under exhaust gas temperature;

Wherein, α _pyfor the excess air coefficient of smoke evacuation place, be calculated as follows:

${\mathrm{\α}}_{\mathrm{py}}=\frac{x}{x-(1-x)\×\frac{O_{2y}-0.5{\mathrm{CO}}_y}{100-({\mathrm{RO}}_{2y}+O_{2y}+{\mathrm{CO}}_y)}}$

In formula, O _2y, CO _y, RO _2yfor oxygen, carbon monoxide, RO in smoke evacuation ₂volume share, %.