1 General Provisions
1.0.1 The code is formulated to implement national laws and regulations and relevant technical and economic policies for realization of technological advantages, economical rationality, safety and applicability in the design of the industrial furnace in Iron & steel works.
1.0.2 This code applies to design for reheating furnace, heat treatment furnace and the furnace for metal products of large and medium-sized iron and steel enterprises, either newly constructed, renovated or expanded.This code is not applicable to the design of smelting furnace.
1.0.3 Design of reheating furnace in iron and steel works shall actively adopt the latest proven and reliable technology at home and abroad, and vigorously develop the technology and equipment with independent intellectual property rights and core competitiveness, and shall comply with resource conservation, environmental protection requirements.
1.0.4 Apart from compliance with the current code, design of the furnace in iron and steel works, shall also comply with related regulations in current national standards and codes.
2 Terms
2.0.1
thermal load of furnace
it is the heat generated by the fuel or electricity in the furnace per unit time, the unit is kW.
2.0.2
reference billet/slab
the billet/slab used for either cold commissioning or hot commissioning to assess furnace performance; steel grade, size and other specifications are to be stipulated in the agreement (or contract) entered into by and between the seller and the buyer.
2.0.3
nominal production
reference billet/slab is charged to furnaces according to prescribed conditions, and heated to achieve the required discharging conditions, and then be fed to mill for continuous production for 6 hours.Nominal production is average of 4h continuous maximum production, the unit is t/h.
2.0.4
nominal specific consumption
it is the chemical energy of fuel charged to reheating furnace or the electrical energy for the electric resistance furnace under the nominal production, the unit is GJ/t.
2.0.5
thermal efficiency
it is the percentage of the energy billet/slab obtains from the energy supplied to industrial furnace.
2.0.6
scale loss rate
it is the proportion of mass loss of billet/slab caused by oxidation during heating compared to the mass before heating.
2.0.7
furnace hearth intensity
it is heating capacity of specific furnace hearth area above which billet travels in the furnace, the unit is GJ/t.
2.0.8
skid hearth rate
it is the proportion of the total outer surface area of the water cooling parts supporting the slabs in furnace as compared to furnace hearth area.
2.0.9
nominal state
it is the gas state when the temperature is 273.15K, and the pressure is 101.325kPa.
3 Reheating Furnace
3.1 General
3.1.1 The chapter applies to design of furnaces in the large and medium sized mill and forge shop either built newly or in continuous production.
3.1.2 The type of furnace and the level of technology and equipment shall match with the production scale of workshop and the level of rolling process equipment.The selected structure, material and equipment of furnace shall meet the requirements of transportation, construction and installation, maintenance and replacement.
3.1.3 Configuration of number of furnaces and capacity of each furnace shall be based on improving furnace efficiency; standby furnace for maintenance in turn shall be spared.But capacity for further play of rolling mill capacity shall be reserved.
3.1.4 Designed nominal specific consumption of newly-built reheating furnace fired by gas or oil shall reach the"advanced index" in Table 3.1.4; designed nominal specific consumption of gas fired or oil fired reheating furnace modified or expanded, shall reach the"average advanced index"in Table 3.1.4.
Notes:1 The nominal specific consumption in this table is the specific fuel consumption under the conditions that, reference structural carbon steel billet/slab is cold charged and heated to the set discharging temperature, insulation layer of the water-cooled (evaporated cooling) units in furnace is good, and specific fuel consumption of reheating furnace reaches that under nominal production.
2 The nominal specific consumption in this table is applicable to walking beam type reheating furnace and pusher type reheating furnace which are listed in the Table 3.2.3 in this Code.
3.1.5 The cooling system of water pipes in furnace shall adopt evaporated cooling, and the generated steam should be connected to the power pipeline network of the factory for running together.
3.2 Structural Steel, Bar and Wire Rod Reheating Furnace
3.2.1 Furnace type selection and main structure design should be in conformity with the following.
1 For reheating of billets for large and medium-sized structural steel rolling mill, walking-beam type reheating furnace with upper and lower heating section should be selected.
2 For the heating of small-sized billets with thickness equal or less than 130mm, walking-bottom type furnace should be adopted, while walking-beam type reheating furnace with upper and lower heating section should be applied for heating of big-sized billets with thickness more than 130mm.
3 Reheating furnaces of medium and small-sized structural steel rolling mill to process common carbon structural steel can be of pusher-type, and should be of walking-beam type while they are used to heat high quality steel.
4 For reheating of stainless steel and decarburized-easily steel, walking-beam type reheating furnace should be selected.
5 Bar and wire rod walking-beam type reheating furnace should adopt side charging and side discharging by cantilever roll table inside the furnace.A hydraulic pusher can be equipped at charging side。
6 Some measures against bend of billets after their entry into the furnace should be taken when bar and wire rod walking-beam type reheating furnace is used to heat cold billets.
7 A new bar and wire rod pusher-type reheating furnace should be designed with shorter billets discharging area for the purpose of side discharging by pusher.It can be designed with no water-cooled billet discharge channel.
8 Walking-beam type reheating furnace for structural steel rolling to be used to heat large billets can adopt end charging by pusher and charger and end discharging by billet withdrawal equipment.
3.2.2 Reheating furnace for high speed wire rod mill or continuous bar mill is better to be provided in one workshop.
3.2.3 Furnace hearth intensity should be economical and reasonable.For a new furnace, it should be in conformity with Table 3.2.3 below.
