1. a) No person shall cause or allow the emission of sulfur dioxide into the atmosphere in any one hour period from any fuel combustion emission source burning simultaneously any combination of solid, liquid and gaseous fuels to exceed the allowable emission rate determined by the following equation:

   E	=	SSHS + SdHd + SRHR

2. b) Symbols in the equation mean the following:

   E	=	allowable sulfur dioxide emission rate;
   SS	=	solid fuel sulfur dioxide emission standard which is applicable;
   Sd	=	distillate oil sulfur dioxide emission standard determined from the table in subsection (d);
   SR	=	residual fuel oil sulfur dioxide emission standard;
   HS	=	actual heat input from solid fuel;
   Hd	=	actual heat input from distillate fuel oil;
   HR	=	actual heat input from residual fuel oil.

3. c) That portion of the actual heat input that is derived:

   1. 1) From the burning of gaseous fuels produced by the gasification of solid fuels shall be included in H_S;
   2. 2) From the burning of gaseous fuels produced by the gasification of distillate fuel oil shall be included in H_d;
   3. 3) From the burning of gaseous fuels produced by the gasification of residual fuel oil shall be included in H_R;
   4. 4) From the burning of gaseous fuels produced by the gasification of any other liquid fuel shall be included in H_R; and
   5. 5) From the burning of by-product gases such as those produced from a blast furnace or a catalyst regeneration unit in a petroleum refinery shall be included in H_R.

4. d) Metric or English units may be used in the equation of subsection (a) as follows:

   Parameter	Metric	English
   E	kg/hr	lbs/hr
   SS, SR	kg/MW-hr	lbs/mmBtu
   Sd prior to January 1, 2017	0.46 kg/MW-hr	0.3 lbs/mmBtu
   Sd on and after January 1, 2017	0.0023 kg/MW-hr	0.0015 lb/mmBtu
   HS, Hd, HR	MW	mmBtu

(Source: Amended at 39 Ill. Reg. 16174, effective December 7, 2015)