A Complex Evaluation and Optimization Approach for Oxygen-Enriched Combustion Characteristics of Blended Fuels Based on Response Surface Methodology

Table 12

The confidence of the two equations for combustibility index.

Factor	Parameter estimation	Degree of freedom	Standard deviation	95% confidence interval lower control limit	95% confidence interval upper control limit	Significant factor
Value	3.25	1	0.55	2.26	4.58
Xiaolongtan lignite, A	−0.51	1	0.44	−1.32	0.63	1.00
Yiliang tobacco stem, B	−1.86	1	0.44	−2.58	−0.59	1.00
Fuyuan bituminous coal, C	−2.33	1	0.44	−3.02	−1.32	1.00
AB	0.61	1	0.63	−0.87	1.79	1.00
AC	2.52	1	0.63	0.99	3.58	1.00
BC	2.31	1	0.63	0.71	3.27	1.00
A^2	0.02	1	0.60	−1.37	1.54	1.01
B^2	−0.41	1	0.60	−1.65	1.22	1.01
C^2	2.67	1	0.60	1.24	3.76	1.01