Wednesday, April 29, 2015

Understanding Petroleum Refining to Better Support Process Control

Petroleum Refinery
The petroleum refining industry is a huge market for process control instrumentation, control valves, and process analyzers. Its important to have a basic understanding of the industry. Here is a great summary of the types of plants and processes.

Petroleum refineries produce liquefied petroleum gases (LPG), motor gasoline, jet fuels,  kerosene, distillate fuel oils, residual fuel oils, lubricants, asphalt (bitumen), and other products through distillation of crude oil or through re-distillation, cracking, or reforming of unfinished petroleum derivatives.

There are three basic types of refineries:
  • Topping refineries
  • Hydroskimming refineries
  • Upgrading refineries (also referred to as “conversion” or “complex” refineries). 
Topping refineries have a crude distillation column and produce naphtha and other intermediate products, but not gasoline. There are only a few topping refineries in the U.S., predominately in Alaska. 

Hydroskimming refineries have mild conversion units such as hydrotreating units and/or reforming units to produce finished gasoline products, but they do not upgrade heavier components of the crude oil that exit near the bottom of the crude distillation column. Some topping/hydroskimming refineries specialize in processing heavy crude oils to produce asphalt. 

The vast majority (approximately 75 to 80 percent) of the approximately 150 domestic refineries are upgrading/conversion refineries. Upgrading/conversion refineries have cracking or coking operations to convert long-chain, high molecular weight hydrocarbons (“heavy distillates”) into smaller hydrocarbons that can be used to produce gasoline product (“light distillates”) and other higher value products and petrochemical feedstocks.

Figure 1 provides a simplified flow diagram of a typical refinery. The flow of intermediates between the processes will vary by refinery, and depends on the structure of the refinery, type of crude processes, as well as product mix.

Figure 1
The first process unit in nearly all refineries is the crude oil or “atmospheric” distillation unit (CDU). Different conversion processes are available using thermal or catalytic processes, e.g., delayed coking, catalytic cracking, or catalytic reforming, to produce the desired mix of products from the crude oil. The products may be treated to upgrade the product quality (e.g., sulfur removal using a hydrotreater). 

Side processes that are used to condition inputs or produce hydrogen or by-products include crude conditioning (e.g., desalting), hydrogen production, power and steam production, and asphalt production. Lubricants and other specialized products may be produced at special locations.

Thursday, April 23, 2015

Handy Electric Heating Engineering Constants and OHMs Law

Here is a very handy "cheat-sheet" for calculating Ohm's Law and other engineering constants that come in very handy when calculating wattages, voltages and current draw of electric heating elements.

These equations are important when sizing any type of electric heating element including cartridge, band, immersion, or flexible heaters.

To calculate any wattage, voltage or current, you need to know two of the variables and refer to the diagram in the document to calculate the third.

Another important quick reference chart is Fahrenheit to Centigrade temperature conversion as shown below.

Monday, April 13, 2015

Intro to CEM (Continuous Emissions Monitoring)

Thermox CEM
O2 CEM courtesy of
Continuous emission monitoring systems (CEMs) are typically used to monitor flue gas emissions (the gas exiting to the atmosphere via a flue from an furnace, oven, or boiler).

CEM systems are used by plants and facilities to assure compliance with the EPA’s requirements to limit the amount of certain gasses (such as CO2) into the air. A CEM samples, measures, collects data, records and reports the gas emissions information. CEM systems can also measure and report gas flow, gas opacity and moisture content.

CEM system are made up of a sampling probe, a filter, a sampling line, a means to condition the gas being sampled, a gas used for calibration, and a group of gas analyzers geared toward the gases being monitored.

The most common gases measured are: carbon dioxide, carbon monoxide, airborne particulate, sulfur dioxide, volatile organics, mercury, nitrogen oxides, hydrogen chloride, and oxygen.

The EPA requires a data acquisition and handling system to collect and report the data, so the CEM must operate continually and provide data on an hourly basis.

For more information on CEM (continuous emissions monitoring), contact:

Belilove Company Engineers
P.O. Box 55936
21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999

Thursday, April 9, 2015

Introduction to Industrial Instrumentation

Here is a great chapter on the basics of industrial control and instrumentation from Tony Kuphaldt's Lessons in Industrial Instrumentation.

The chapter uses examples such as boiler water level control systems, wastewater disinfection, and chemical reactor temperature control to demonstrate uses for instrumentation. It also discusses indicators, recorders, transmitters and analytical instruments, and applies their use in level, temperature, pressure and flow control.

Chapter is presented in "flipbook" format, viewable on all devices. Click on image below to view.

Intro to Industrial Instruments
Click on image to open new window and read chapter.