Obiettivo To demonstrate the feasibility of reducing energy consumption in the reheating of forgings and to improve forging quality by the replacement of electric and conventional gas-fired furnaces, by a new gas-fuelled rapid heating furnace incorporating and combining known technical features : these will considerably reduce energy consumption and advance the engineering design of conventional gas-fired reheating furnaces.The project is comprised at 3 phases : Work began on phase 1 (Jan.1985). In this phase of the project the principal technical details of the furnace are investigated, for example the charge transportation through the furnace and experimental burner tests.Apart from the experimental work, theoretical work was undertaken to develop a model for the numeric simulation of the transient behaviour of the furnace during heat-up.The aim of this numeric simulation is to specify the furnace lengths. The effective furnace length obtained by these calculations for the entire furnace is 3 m.The delivery of the new gas-fuelled rapid heating furnace by W. Brinkmann GmbH to Gaswaerme-Institut marked the completion of the design and fabrication phase of the demonstration project. Gaswaerme-Institut have now commission the plant and review major plant operating data.The second phase will involve detailed tests to optimize operation in terms of energy, conservation, scale formation and even charge testing. Test parameters will include control zone distribution, fuel/air ratios, temperatures in the various zones and the temperature to which the combustion air is preheated.Following incidents during the commissioning work, some constructive modifications were made. The changes to the furnace design insure that furnace operation at the forging shop will be reliable. The results of the second phase of the project are in the following :- the charge transfer by a walking-beam transporting system works trouble-free- staged combustion minimizes NOx output (less then 200 mg/m3)- the CO formattion is less then 100 ppm by an air factor of 0.65 in the fuel-rich heated soaking zone.- scale formation could be minimized (metal loss between 0,25 and 0,38 %)- less decarburization by an air factor of 0.65 in the fuel-rich heated soaking zone.- uniform reheating of the forging pieces could be demonstrated (small temperature differences between the core and the surface of the charge)- the specific energy consumption depends on the material throughput and the forging tempeature- these value ranges from 580 kWh/tonne to 690 kWh/tonne by a forging temperature between 1150 deg.C and 1250 deg.C.The final phase involves field testing at a forging shop to confirm design and to demonstrate furnace operation in practise.In this phase it was possible to work out the running conditions of the furnace in order to optimize the quality of the forging pieces.The main results of the second phase could be confirmed. Except the forging temperature of 1250 deg.C. As far as the character of the skin is concerned the furnace must run with a forging temperature of about 1310 deg.C. In this case the specific energie consumption increased from 690 kWh/tonne to 740 kWh/tonne.Nevertheless the gas fuelled rapid heating furnace runs cheaper then an inductive furnace. These inductive furnaces are operated by a secondary source of energy (electricity) and are therefore expensive to operate.Rapid heating furnaces are often installed in forging shops to treat small forgings. It is important to heat the forging rapidly and evenly and to minimize scale formation.The object of this research is to produce a micro-structure to eliminate the need for further heat treatment. The advantage of an inductive, over a conventional gas-fuelled furnace is the low level of scale formation due to the brief furnace dwell time. On the other hand, inductive furnaces are operated by a secondary source of energy (electricity) and are therefore expensive to operate. In addition, temperature distribution in a charge heated by a conventional furnace is unsatisfactory. The furnace to be designed, installed and operated for the project is a gas fuelled rapid heating installation using natural gas as the primary energy source.Charge heating will be in 3 zones (soaking, heating-up and preheating) to reheat the charge. As in the case of pusher type furnaces, charge and atmosphere movement will be countercurrent. In order to minimize scale formation, the soaking zone will be fired in the fuel-rich mode, while the heating-up zone will be fuelled by a fuel-lean gas and air mixture, burning uncombusted gases from the soaking zone. Staged combustion minimizes NO output and environmental impact. Fuel-rich soaking zone operation necessitates tests to establish combustion air preheat temperature, the acceptability of the fuel/air system with respect to sooting and safety aspects associated with CO formation.Forgings will be charged in transverse mode and a recuperator incorporated in the furnace for combustion air preheating : the furnace control system will feature high precision fuel/air ration controllers for heating-up and soaking zones. Each controller is capable of maintaining an air factor of between 0.5 and 1.5 to allow exact adjustment of the fuel/air ratio and to minimize scaling. An optical control system monitors the temperature of the charge leaving the furnace. Fuel gas flow is adjusted by temperature controller as a function of the difference between temperature as measured by the optical system and setpoint temperature. When fuel gas flow is adjusted, combustion air flow will also be adjusted by the fuel/air ratio control system. A shop function is also incorporated in the furnace control system : this is capable of lowering gas flow to between to 10-30 per cent of rated flow.For this purpose the control system will immediately reduce gas flow if furnace operation is switched to idle mode. Simultaneously, setpoint temperature will be lowered to determined level : walking-beam operation will be switched to idle. Since, on start-up, the furnace must be heated to operating temperature quickly as possible, a heating-up function is incorporated in the control system. When heated to working temperature, furnace temperature will be increased to the idle temperature level and from this to operating temperature. Programma(i) ENG-ENALT 2C - Programme (EEC) of demonstration projects relating to the exploitation of alternative energy sources and to energy saving and the substitution of hydrocarbons, 1983-1985 Argomento(i) 3.2 - INDUSTRY Invito a presentare proposte Data not available Meccanismo di finanziamento DEM - Demonstration contracts Coordinatore GASWAERME-INSTITUT E. V. Contributo UE Nessun dato Indirizzo Hafenstrasse 101 ESSEN Germania Mostra sulla mappa Costo totale Nessun dato
