Specify the conversion factor for hours to years

The software uses a specified number of operating hours per year to convert units of hours to years. You can set the number of operating hours in a year in the UOM Slate. This conversion factor applies to the following Variable Types and units of measure (UOMs):

• Mass Flow

  • kta

  • MTPA

• Currency and Time

  • k¤/yr

  • M¤/yr

• Emission Rate

  • kg/yr

  • t/yr

  • lb/yr

  • klb/yr

  • kta

By default, this value is the number of hours in a calendar year (8,760 hours, or 365 days at 24 hours per day). If you know that your process includes routine shutdowns (for example, maintenance shutdowns) or you expect a reduced number of operating hours per day, then you can update the operating hours per year to account for the hours that you expect your process plant to be down. This reduction gives you a more accurate value of the actual yearly production, feedstock consumption, and utility usage. More accurate yearly values are especially useful when you are evaluating the economics of your process.

Specify the conversion factor for hours to years

1. Open the UOM Manager.

2. Select the Slate dropdown arrow.

3. On the Open Slate submenu, select the UOM Slate that you want to change.

4. In the Hours Per Annum box, enter the number of operating hours in a year.

   

5. (Optional) Update the Description to indicate the new value for the number of operating hours in a year.

   Changes to the Hours Per Annum affect yearly mass flow, currency, and emission rate calculations throughout the entire simulation. We highly recommend that you update the Description to indicate the change so that future users are aware of the change.