RU2114185C1 - Reheating walking-beam furnace for heating of long metal articles - Google Patents

Abstract

FIELD: reheating furnaces with roof heating; may be used in metallurgy and mechanical engineering. SUBSTANCE: furnace is of continuous type and provided with body, walking beam with movable and immovable beams, lined heating sections with burners and nozzles located in roof, and knuckle between the second weld zone and soaking zone with installation of end-face burners of pipe-in-pipe type of high heat power located in one row across the furnace width, in middle part of furnace, above knuckle at an angle of 18-20 deg to horizon. Lower elevation of knuckle is +1200 mm, and upper elevation of zone is +3100 mm when measuring from furnace bottom. EFFECT: reduced specific consumption of fuel energy resources, uniform distribution of pressure field over furnace working space. 3 cl, 3 dwg

Description

 The invention relates to heating furnaces with vaulted heating and can be used in the metallurgical and engineering industries.

 Known heating furnace with a walking hearth and arch heating of the design tool "Steelproject" [1].

Furnace specifications:
Dimensions of heated billets, mm:
Diameter - 50 - 90
Length - 2000 - 6000
Heating temperature, ^o C - 1150 - 1250
Fuel Type - Natural Gas
Type of burner - Flat flame
Air heating temperature, ^o C - 250 - 350
Type of recuperator - Metal, whip
Specific heat consumption, mJ / kg - 2 - 2.1
The voltage of the active hearth, kg / (m ² • h) - up to 1350
The highest fuel consumption per furnace, m ³ / h - Up to 2650
Furnace productivity, t / h - Up to 50
The disadvantage of such furnaces is low productivity and high fuel consumption. Known methodical furnace for heating slabs, blooms, containing methodical, welding and tomilny zone. In the arch of the methodical furnace, burners are installed in the direction of metal movement at an angle of 35 - 45 ^o to the vertical axis, while the distance between the burners is 6 - 7 with the diameter of the nozzle of the burner, and the burners in the method zone are made high-speed. However, such furnaces are used for heating not very long metal products [2].

 The closest in technical essence to the proposed one is a walking hearth heating furnace for heating long metal products, comprising a housing, a vault, walking underneath with movable and fixed beams, lined welding and languishing zones with torches and nozzles placed in the vault, a vault pin installed between the welding zone and the torch zone, with end burners placed at an angle to the horizon to form a gas stream [3].

 The disadvantage of such heating furnaces is increased fuel consumption due to the uneven distribution of the pressure field over the working space of the furnace.

 The objective of the invention is to reduce the specific consumption of fuel and energy resources, the uniform distribution of the pressure field over the working space of the furnace.

The problem is solved in that the methodical furnace, comprising a casing walking under with movable and fixed beams, heating elements, lined heating sections with burners and nozzles placed in the roof, additionally contain a pinch in the welding zone with the installation of end-burners of the pipe-in-pipe type located in one row across the width of the furnace at an angle of 18 - 20 ^o to the horizon.

 In FIG. 1 shows the proposed methodological furnace; in FIG. 2 - methodical furnace to design, prototype; in FIG. 3 is a diagram of the pressure distribution over the working space of the furnace: a) methodical furnace before reconstruction (prototype), b) methodical furnace after reconstruction (new technical solution).

 The heating furnace consists of a housing 1, a vault 2, a walking hearth 3, vault burners 4, a pinch in the vault 5 and end burners 6 installed above it. The furnace has five heating zones, one of which is unheated 7, where metal is loaded; second zone 8 (first welding); third zone 9 (second welding); on the border between the second welding zone 9 and languid zone 10 is set vault pin 5; fourth zone 10 (languid); fifth zone 11 - zone of the issuance of metal. In the unheated zone of the furnace 7, a smoke collector 11 is equipped in its side wall.

The walking hearth furnace is designed to heat shaped and rectangular workpieces. The length of the furnace on the masonry is 35500 mm, the width on the masonry is 13804 mm, in the light 12644 mm. The furnace has five heating zones, four of them with regulation of fuel supply and combustion. The first zone in the course of loading is methodical, unheated 7. The second zone 8 (first welding) is equipped with 24 radiation flat flame vault burners of the GR 750 type. The third zone 9 (second welding) is equipped with eight end burners of the DVB 225/75 type. The burners are installed above the arch clamp with a height of 1900 mm, with the lower mark of the arch clamp +1200 mm, the upper mark of the additional zone +3100 mm, counting from the bottom of the furnace. The fourth zone 10 (languid) is equipped with 32 burners of the GR 500 type. The fifth zone 11 - the zone for the delivery of metal billets is equipped with 24 burners of the GR 750 type. All burners operate on cold gas and air heated to 400 ^o C (Fig. 1). The hearth of the furnace consists of two movable and three fixed beams. Between the beams along the entire length, girder gaps are made. Seal on the side of the hearth is made by hydraulic locks. The working space is lined with fireclay brick of class "A", the side walls on the outside - lightweight. Dross from the furnace hearth is removed through the descaler, discharged from the gutter, and washed off the gutter with water under the roller conveyor to the hydraulic discharge system. The billets enter the furnace through the live rolls. The pusher moves the workpiece into the furnace on the planer beams of the fixed beams, its stroke is regulated depending on the width of the workpiece and the pitch of the workpieces. In the furnace, the metal moves with the help of movable beams (back-up-forward-down). Combustion air is supplied by a VM-18A fan through a metal 2-loop recuperator installed in the furnace hog. The combustion products enter the exhaust chimney, enclosed in a metal casing and lined from the inside, then into a common smoke collector for all furnaces, which ends with a chimney. In addition, two chimneys of the waste heat boiler are embedded in a common smoke collector. The furnace is equipped with a water cooling system. Water-cooled elements are the beams of the ends of the issuance and loading, the beams under the smoke collector, the pinch beam. The furnace is equipped with control systems and automatic regulation of the thermal regime. All processes associated with the transportation of billets through the furnace and the maintenance of the furnace are fully mechanized and automated.

In the proposed design of the methodical furnace, the second welding zone is equipped with a pinch with end heating. To do this, install 8 two-wire burners of the DVB 225/75 type in one row horizontally at an angle of 18 - 20 ^o to the horizon. The composite pinch 5 is set at the boundary between the second welding zone 9 and the languilny zone 10. The lower mark of the arch pinch 5 is +1200 mm, and the height of the additional zone +3100 mm (counting from the hearth). As a result, the negative pressure zone shifts to the methodical zone, and in the remaining zones of the furnace, the pressure at the hearth level is 10.0 - 15.0 Pa (1.0 - 1.5 mm water column), which is close to optimal (Fig. 3).

 The invention is new, as there are no analogues from domestic and foreign sources of information. According to the information available to the applicant in the known solutions there are no signs similar to those that distinguish the claimed technical solution from the prototype, which allows us to conclude that it meets the criterion of "inventive step".

 Due to the fact that in the inventive design, the temperature in the working chamber of the furnace increases compared to the prototype, this provides a more intense heating of metal products throughout the section.

 A positive effect from the use of the inventive design of the furnace will be obtained due to the manifestation of a new technical solution, namely, that the second welding zone 9 is equipped with pinch 5 with additional end heating.

 An analysis of the thermal work data of the methodical furnace in comparison with the prototype showed that replacing part of the vaulted heating with end heating allowed reducing the equivalent fuel consumption from 72.0 to 54.0 kg / t and increasing the working space efficiency from 37.5 to 48.2%.

 The decrease in fuel consumption occurred mainly in the welding zones of the furnace.

Thanks to a new technical solution, the negative pressure zone at the bottom level shifted to the methodical zone, and thereby significantly reduced atmospheric air inflow into the furnace working space (see tab. 1-6; Fig. 4 gives a sketch of a DVB 225/75 burner) . The invention in comparison with the known technical solutions has the following advantages:
due to an increase in the temperature of the exhaust smoke, the temperature of the air heating rises;
by reducing fuel consumption in welding zones, the equivalent fuel consumption was reduced by 18 kg / t during pilot heating and in general by 8 - 12 kg / t, taking into account downtime and irregular operation of the mill;
reduced furnace operating costs and repair needs;
operating conditions of the furnace and sanitary conditions for servicing personnel are improved by reducing gas emissions into the atmosphere of industrial premises.

 Using a methodical furnace with a new technical solution in the conditions of OAO Nizhny Tagil Metallurgical Combine confirms the industrial applicability of the invention.

Claims (3)

1. A heating furnace with a walking hearth for heating long metal products, comprising a housing, a vault, walking under with movable and fixed beams, lined welding and languishing zones with torches and nozzles placed in the arch, a vault pin installed between the welding and languishing zones with end burners placed above the clamp at an angle to the horizon to form a gas stream, characterized in that the end burners are installed above the arch clamp at an angle of 18 - 20 ^o to the horizon.  2. The furnace according to claim 1, characterized in that the lower and upper parts of the vault pinch are located at a distance of 1200 and 3100 mm from the furnace bottom, respectively.  3. The furnace according to claim 1, characterized in that the end burners are made in the form of a “pipe in pipe”, are installed in one row along the width of the furnace above the arch clamp in the amount of eight burners.

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