Obiettivo The aim of the project is to reduce process cycle by an original method of electric heating. By this method, unusually high power can be used, with reduction in the energy usages in the furnace and of the heat-up and process times.The project forecasts an increase in production capacity of between 46 and 64%. The expected energy savings are 10% due to lining, 9-18% due to high temperature processing, depending on case depth. In a furnace of 62 kW power, the expected energy saving corresponds to 62 toe-year.The measurements of standing losses and of recovery times allow performance of the furnace in its original form and after conversion to be compared.Standing loss: Temperature original form after conversion Gas consumption therms-hour electricity consumption kw 800 1,463 17,07 850 1,710 18,49 900 1,909 20,11 950 2,186 21,79 975 2,288 23,38Recovery times for a gross load of 278,5 Kg Temperature original form after conversion 800 1 h 01 min 12 s 31 min 52 s 850 1 h 09 min 23 s 35 min 05 s 900 1 h 18 min 51 s 37 min 25 s 950 1 h 30 min 36 s 39 min 17 s 975 1 h 38 min 43 s 40 min 07 sOther interesting results are presented below:Heat up time from cold to 800 c is 4 h 33 min 03 s with an energy consumption of 163,35 kwh (low power); heat up time from 800 c to 975 c is 16 min 35 s with an energy consumption (high power) of 24,72kwh.The optimum process parameters have been established for carburizing production loads at a number of temperatures: for comparison the treatment time used prior to this project is also given. The times quoted are for the active part of the treatment cycle and do not include times for temperature recovery after loading or for quenching.. Furnace Specified Boost Diffuse Total time temperature case depth time time h,min C mm h,min h,min 925* 0,79 4,00 ---- 4,00 925 0,79 2,52 0,23 3,15 950 0,79 2,30 0,15 2,45 975 0,79 1,45 0,15 2,00The use of oxygen probes for atmosphere measurements, linked to computer or microprocessor control systems has led to the use of optimized control parameters which give significantly reduced cycle times at 925 c, the limiting factor now being the diffusion rate of carbon in steel, which is directly related to the treatment temperature. The next logical step in reducing cycle times is therefore to increase the process temperature.This is difficult to achieve efficiently in a conventional gas-fired furnace, therefore the work involved in this project was to convert a furnace to a novel electrical heating method. The gas-fired radiant tubes and associated burner equipment was recovered and replaced with silicon carbide rod heating elements of a much smaller diameter. This allows a layer of low thermal mass insulation to be applied to the internal walls of the furnace chamber, with a consequent reduction in heat losses. It is possible to apply much more power than has in the past been practicable, thus shortening the heat-up times. A further reduction in the recovery times to higher temperatures has been achieved due to the phase-angle fired thyristors used to control power input, which being constant current devices, will apply more power at higher temperatures, where the element resistance increases. At these increased treatment temperatures, where carbon diffusion is extremely rapid and treatment times correspondingly shortened, it is imperative that accurate control of the furnace atmosphere carbon potential should exist. This role is best suited to oxygen-probe control systems which have a very rapid response time and can be used to control the carburizing cycle to computer optimized treatment parameters.The phases of the project are:1) monitor performance in terms of energy consumption and production of the furnace in the original form2) reconstruction of the furnace and control system in accordance with requirements of high temperature carburizing3) monitor performance of furnace after conversion4) operation of furnace under production conditions to confirm energy savings and increased productivity5) publication of results. Programma(i) ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984 Argomento(i) 1.6 - INDUSTRY Invito a presentare proposte Data not available Meccanismo di finanziamento DEM - Demonstration contracts Coordinatore LUCAS RESEARCH CENTRE Contributo UE Nessun dato Indirizzo SHIRLEY, SOLIHULL B90 JJ WEST MIDLANDS Regno Unito Mostra sulla mappa Costo totale Nessun dato
