Reduce Operating Costs
Leaking or Blocked Steam Pipes and Valves
Steam is an efficient way to transport heat energy. The latent heat needed to transform water into the gaseous state, steam, is extremely large. This means that large amounts of heat energy can be transported with a minimum temperature differential to the environment. This equates into lower energy and insulation costs.
When steam arrives at the site where heat energy is needed, it condenses, thereby releasing the large latent heat it was carrying. The condensate formed by this process must be removed by the steam system and returned to the boiler where it is turned back into the steam and the cycle is repeated.
The steam trap performs this function; to hold back live steam while allowing gases and condensate to pass through. This allows more energy to be obtained from the steam, thus raising a steam system's overall efficiency.
Steam traps, like any mechanical device, eventually fail. Most are designed to fail in the open position to maintain steam system operation. When they fail in the open position, they "blow" live steam. This costs energy dollars which the steam trap was installed to conserve. Occasionally, steam traps fail in the closed position. This causes condensate back up in the steam system with potentially disastrous results.
Properly performed infrared thermography can identify steam traps that are blowing steam as well as those that may fail closed. Steam traps are sometimes located in inconvenient areas where they are hard to reach using other NDT technologies. This fact makes trap diagnosis by IR especially useful.
In a 100 psig system with production costs of R 56 / 1000 pounds, a ¼"leak will cost R 1 400 000 in one year and a ½" orifice would waste R 560 000 a year.
An oil refinery identified 14% of their traps were malfunctioning. By replacing or repairing these traps they saved approximately R 4 200 000 per year.
Furnaces and Refractory Material
A refractory material is basically a high temperature insulator. They are usually a non-metallic ceramic type of material and are commonly supplied in brick form. Refractory materials are used inside furnaces, ovens, boilers, hot storage tanks and other equipment that produces or contains extremely hot temperatures.
Using thermography to inspect refractory begins with the assumption that a uniform temperature inside a vessel will result in uniform warming of its exterior as heat is conducted to the vessel's walls.
An ideal vessel would have a perfectly uniform temperature on its external surface. If a crack, or other defective conditions existed in the insulating medium, the exterior surface would increase in temperature in direct proportion to and in the exact location of the defect. Thus, the defect would be obvious based on the non-uniform conductance of heat into the exterior surface. If the exterior metal is threatened or a safety hazard may exist, absolute temperature measurements of the hot areas become important.
In normal practice, there are other structural variations, which cause non-uniform heat patterns in addition to the defects; these include grid work, refractory type variations, portholes, catwalks, etc.
In the manufacture of cement the raw materials are ground together, the mixture is heated until it fuses into a clinker, and the clinker is ground into a fine powder. The heating is usually accomplished in rotary kilns which look like huge rotating pipes, sometimes hundreds of feet long. The kilns are slightly tilted from the horizontal, and the raw material is introduced at the upper end, either in the form of a dry rock powder or as a wet paste composed of ground-up rock and water. As the charge progresses down through the kiln, it is dried and heated by the hot gases from a flame at the lower end. After it leaves the kiln, the clinker is cooled quickly and ground, and then conveyed by a blower to packing machinery or storage silos.
The refractory lining of the kilns eventually wears out and must be replaced. If it is not, the steel shell can overheat and fail. Thermography is ideally suited for locating and measuring the temperature of areas where refractory has failed. Continuous tracking allows the kiln operators to maximize the amount of time they can operate until a shutdown for refractory repair is necessary.
Improve the Efficiency of a Process
Blower systems can be used to move materials through pipes from one process or location to another. An example might be a system to deliver coal dust to a boiler. The condition of the pipes and process itself can often be monitored with an infrared camera. Buildup of product debris in a pipe will usually show up as a temperature differential in a section of pipe. After the buildup has been removed, thermography can be used to verify that the work has been completed satisfactorily.
© Thermography Consulting 2008