Los sistemas de fluidos térmicos proporcionan un control de temperatura preciso y uniforme, un aumento de la producción y la calidad del producto, un bajo mantenimiento, seguridad humana, seguridad medioambiental y años de un servicio eficaz. Los sistemas de aceite caliente proporcionan ventajas significativas en casi todas las categorías.
Eficacia
Los fabricantes de calentadores de fluidos térmicos indican que la eficacia puede ser de un 5% a un 8% mayor que en sistemas de vapor convencionales.
Y si se considera la pérdida de inflamación de un sistema de vapor típico (incluyendo pérdidas de la trampa) de un 6% a un 14%, la pérdida de purga de hasta un 3% y pérdida en el aparato de aeración de otro 2%, la diferencia en la eficacia es muy pronunciada.
Los sistemas de fluidos térmicos no sufren ninguna de estas pérdidas y como resultado pueden llegar a ser un 31% más eficaces, excluyendo un calentador adicional y la eficacia del generador de vapor.
Operadores con Licencia
En muchas zonas del país, la ley exige que los ingenieros a tiempo completo con licencia de operación supervisen el funcionamiento de los sistemas de alta presión de vapor. El coste anual por ingeniero está muy por encima de los $60.000.
A diferencia de los sistemas de vapor, la mayoría de los sistemas de fluidos térmicos operan a presión atmosférica y son ventilados a la atmósfera en el depósito de expansión. La presión en estos sistemas está limitada a la descarga de la bomba necesaria para mantener el fluido en un flujo turbulento mientras las tuberías superan la resistencia de fricción. Las típicas descargas de presión de la bomba pueden ir desde 35 psi a 65 psi con presiones algo más altas que se requieren para grandes sistemas. Debido a la operación segura, sin presión, los sistemas de aceite térmico rara vez, si alguna vez, exigen operadores con licencia.
Corrosión
Steam systems are well known for corrosion problems. Air in combination with hot water, salts and other reactive contaminants presents an extraordinary potential for metal corrosion. Steam is abrasive and has virtually no lubricity. Add scale and deposits from minerals found in most all water supplies, and system problems quickly compound.
Paratherm fluids are completely non-corrosive. 100% derived from natural U.S. feedstocks, they provide the same high degree of metal surface protection as the finest light lubricating oils.
Maintenance
Steam systems require constant, unending maintenance — maintenance that is focused on steam traps, valves, condensate return pumps, expansion joints and water analysis and treatment. And when the power fails in a cold climate, steam systems are subject to freezing, burst pipes and damaged components.
Thermal fluid systems require no traps, condensate return, blowdown or water additives – and if the proper fluid is specified, can be shut down even in sub-zero conditions with no worry of freezing. If Paratherm fluids are cooled below their pour points, they contract upon solidifying, presenting no danger of burst pipes. Hot oil systems have proven to operate quietly, safely and efficiently for years with minimal maintenance.
Environmental Safety
The water in a steam system must be chemically treated to reduce corrosion, among other things. The chemicals cannot be discharged into sewers, as they present considerable environmental hazard. In addition, the temperature of discharge water is often regulated by law. Special provisions for cooling are required if water is to be drained into sewers (in many localities, water hotter than 140°F cannot be discharged.)
Thermal fluid systems require no blowdown, and unlike steam systems, are not subject to continual leakage. Should Paratherm fluids escape from the system, cleanup is handled using the same simple procedures followed for spills of light lubricating oil. And unlike heavily treated boiler feed water, Paratherm heat transfer fluids offer safe, easy disposal. They can be combined with spent lube oils, sent to the local motor oil recycler and processed into another useful product.
Safety
To deliver the kind of heat required in most process operations, steam systems would have to operate at exceptionally high pressures. At 600°F for example, a saturated steam system develops about 1600 psi. Even at 400°F, the pressure is still high — about 235 psi.
In contrast, most thermal fluid systems are vented to atmosphere. Pump discharge pressure is just high enough to overcome frictional drag from piping and components while maintaining turbulent flow. The vapor pressures of Paratherm fluids are fractions of atmospheric, even at their maximum operating temperatures of 600°F.
Temperature Control
Steam systems rely on the control of pressure to control temperature. With this dependence on delicate pressure balance, accuracy is generally limited to swings of ±10°F or so at best. Worse, as the system ages and corrosion takes its toll, control of temperature degrades.
Uniformity of heating can also be a problem due to varying rates of condensation and condensate removal in the heat user. And this is before taking the negative effects of metal surface corrosion and plating-out into consideration.
In comparison, thermal fluid equipment manufacturers report the ability to regulate temperature swings to ±1.5°F or less. This precision is accomplished by the metering and mixing of cooler return fluid with warmer fluid from the supply line. Adding high-velocity turbulent fluid flow to the equation, precision and uniformity of temperature control across the entire user surface is assured.
Thermal fluid systems not only provide efficient, uniform heat, but efficient, uniform cooling as well. And some fluids can provide efficient heating from over 400°F to cooling at -40°F and below.
System Cost
Purchase cost of steam systems can be less than thermal fluid systems. With less-complex thermal fluid systems however, there are paybacks: decreased operating costs, maintenance costs, and environmental concerns — and increased production and product quality resulting from better control of heating and cooling.
Combine these with improved safety and reduced manpower cost, and the overall economy of thermal fluid systems will far surpass steam. |
