Numerical Modeling and Multi-Objective Control of Air Pollutant Emissions from Natural Gas Internal Combustion Engines

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The energy, economic and environmental performance of the optimization point

Target function	Unit	Before optimization	After optimization
Cost	¥	6.52×108	6.45×108
HGTCC	%	56.31	56.82
ε	kg/(MW·h)	357.61	353.31

Optimized system and original system design parameters

Design parameter	Unit	Before optimization	After optimization
High pressure steam pressure value	MPa	9.921	12.568
Medium pressure vapor pressure value	MPa	2.13	2.05
Low pressure steam pressure value	MPa	0.38	0.27
High pressure steam temperature	°C	567.6	573.69
Reheat steam temperature	°C	576.6	576.98
Close temperature difference (high, medium, low pressure)	°C	15/15/15	17/8/8
Node temperature difference (high, medium, low pressure)	°C	8/8/8	5/9.5/5

The variation ranges of the design parameters

Design parameter	Variation range
High pressure steam pressure value	9.5MPa~12.5MPa
Medium pressure vapor pressure value	2.0MPa~2.6MPa
Low pressure steam pressure value	0.3 MPa ~0.9 MPa
High pressure steam temperature	<575.65°C
Reheat steam temperature	<575.65°C
Close temperature difference (high, medium, low pressure)	6~18°C
Node temperature difference (high, medium, low pressure)	10~22°C

Design parameters of the optimized points

Design parameter	Unit	Internal combustion turbine load rate
		100%	75%	50%	30%
High pressure steam pressure value	MPa	12.381	12.5	12.5	12.5
Medium pressure vapor pressure value	MPa	2.11	2.126	2.11	2.11
Low pressure steam pressure value	MPa	0.284	0.265	0.225	0.21
High pressure steam temperature	°C	576.36	571	571	558.56
Reheat steam temperature	°C	576.96	576.8	576.8	5573.879

Algorithm operation parameters

Item	value
Population size	150
Cross probability	0.8
Mutation probability	0.2
The number of individuals per generation	0.7

Comparison of the analog and actual data of the combustion chamber exit

Item	Analog value	Actual value	Error(%)
Combustion chamber outlet temperature(K)	1789.27	1796.57	0.41%
Mean NOx of combustion chamber exit(ppm)	24.08	24.52	1.79%
Maximum amplitude of pressure pulsation(kPa)	12.79	12.43	2.91%
Average flow rate of exit section(m/s)	115.58	120.61	4.17%
Mean CO of combustion chamber exit(ppm)	5.88	5.95	1.18%

Comparison of energy, economic, environment performance after optimization

Target function	Unit	Before optimization
		100%	75%	50%	30%
Cost	¥(×108)	6.52	5.62	4.45	3.61
HGTCC	%	56.31	53.38	50.37	45.98
ε	kg/MW·h	357.61	376.79	400.65	442.3
Target function	Unit	After optimization
		100%	75%	50%	30%
Cost	¥(×108)	6.45	5.52	4.36	3.24
HGTCC	%	56.82	54.36	51.87	47.66
ε	kg/MW·h	353.31	368.39	387.54	421.74