In the old-timey Fire Triangle, you have heat, fuel, and oxygen. Get these three together in the right quantities, and you get fire. What if the fuel provides its own heat? That’s spontaneous combustion, or spontaneous ignition. NFPA921 defines this as “initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.” Read More
This is a case study about an incident I investigated involving a major upset in a distillation column. This blog builds on the previous blogs about the Distributed Control System, DCS – Data is the Key.
Distillation is a method of separating mixtures of compounds with differing boiling points. Uncle Bill with his still on the hill separates ethanol, that boils at 173°F, from water that boils at 212°F. If the mixture is heated to above 173°F, but below 212°F, the ethanol will boil, the vapor will travel up out of the unit and then can be condensed and served over ice with an olive… Any mixture of two or more chemicals with different boiling points can be separated in this way. The distillation Read More
The Kraft paper process was invented in 1879 and produces a stronger finished product that other paper manufacturing methods. One of the waste streams is known as black liquor and is a mixture of solids and water. It contains lignin, hemicelluloses and chemicals used in the pulping process. The original process had no use for this harmful waste stream and it was dumped into nearby waterways, to their detriment!!! Mr. G.H. Tomlinson invented the recovery boiler in the early 1930’s. This development made the Kraft process the manufacturing method of choice, as explained below. Read More
Heat exchangers, as the name implies, are used to bring a process stream to a desired temperature. They can heat or cool either gases or liquids. They are fairly intricate in their construction, therefore not the cheapest piece of equipment to purchase. For that reason, facilities don’t keep “spare” exchangers lying around, so when they fail catastrophically, the entire manufacturing process goes down with them… and stays down until they are fixed or replaced. Ow!
When investigating an industrial incident, one piece of information I always ask for is the relevant P&ID’s for the process. P&ID stands for Piping and Instrumentation Diagram and is defined as “A schematic diagram of the relationship between instruments, controllers, piping, and system equipment.” A set of P&ID’s for an entire facility allows you to trace the entire manufacturing process from raw material unloading to finished product loadout, including utilities like steam, water, fuel, and air. That’s great information to have, but isn’t especially useful Read More
The Safety Hierarchy states that hazards should be mitigated first by engineering controls, secondly by guarding, and lastly by warning/training. When the first two, engineering controls and guards, fail in a manufacturing setting, a chemical release could occur. A forensic chemical engineer can help determine the root cause of that failure. Read More
Now that you know what ammonia is (see Part One here), how it behaves, and how to safely store it and work with it, let’s look at some areas in industry where it is used.
Anhydrous ammonia has a use in pollution control. Industrial boilers and power plants burn coal or natural gas to make steam and/or electricity. When the fuel is burned using air as the oxygen source nitrogen gets exposed to the heat as well because air is 79% nitrogen. The nitrogen gets oxidized and forms several compounds referred to as NOx (NO, NO2, NO3). NOx compounds are harmful to Read More
Ammonia is a compound consisting of one nitrogen atom and three hydrogen atoms and is denoted by the formula NH3. Its boiling point is -28°F at atmospheric pressure, so unless it is under pressure, it is gaseous at room temperatures. Therefore, pure ammonia is typically stored under pressure in a liquid form. Household ammonia is only 5-10% NH3, the remaining 90-95% is water. Ammonia is extremely soluble in water. It is often depicted like this: Read More
Wouldn’t it be great to have a built-in camera to let you see exactly what went wrong before an incident? In many manufacturing instances there is, chemical plants especially. The computer system that operates the plant is called a Distributed Control System (DCS) and it has the capacity to monitor thousands of process variables (flow rates, temperatures, pressures, levels, valve positions, pumps on/off) simultaneously. Read More
The thirty-thousand-foot view of manufacturing is raw material in, alter in an appropriate fashion, finished product out, by-product out. Since the finished product keeps a business in business, it gets the most attention. What about by-products or waste streams? Read More