CN117737631A - Quick hot dip galvanize belted steel production line - Google Patents

Abstract

A rapid hot galvanizing strip steel production line sequentially comprises the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; the central continuous post-treatment station sequentially comprises a jet direct fire preheating section or jet radiation composite heating section, a direct fire heating section, a radiant tube soaking section or jet radiation composite soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section; the jet direct-fired preheating device utilizes combustion waste gas of a direct-fired heating section to heat recycled nitrogen-hydrogen protective gas, the nitrogen-hydrogen protective gas is jetted to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange, and the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Description

Quick hot dip galvanize belted steel production line

Technical Field

The invention relates to the technical field of strip steel cold rolling post-treatment, in particular to a rapid hot galvanizing strip steel production line.

Background

The corrosion resistance of the automobile is directly related to the service life of the automobile. In order to improve corrosion resistance of a vehicle body, a hot dip galvanized steel sheet or an galvannealed steel sheet having a relatively low cost is generally selected for use as an automotive steel sheet. In recent years, along with the increasing aggravation of global environment deterioration and energy shortage problems, and the improvement of vehicle collision safety standards and automobile exhaust emission regulations in all countries in the world, the strong demands of the automobile industry in environmental protection, safety, energy conservation and the like are added, so that the automobile weight reduction becomes one of the main development directions of the automobile manufacturing industry. Considering the manufacturing cost, recovery and maintenance of automobiles comprehensively, high-strength steel, particularly ultrahigh-strength steel, is still the first choice material for the development of the automobile industry in the future. In combination with the improvement of the corrosion resistance requirement of the car body, the requirements of the automobile industry on hot-dip pure zinc and alloyed hot-dip galvanized high-strength strip steel are rapidly increased year by year.

Conventional hot dip pure zinc and galvannealed strip steel treatment lines generally comprise the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, intermediate looping, flattening, outlet looping, finishing and coiling, wherein a withdrawal and straightening station device is arranged between a flattening station and a finishing station of some treatment lines, a surface post-treatment station device such as passivation or fingerprint resistance is arranged between the flattening station and the finishing station of some treatment lines, and a withdrawal and straightening station device and a surface post-treatment station device such as passivation or fingerprint resistance are arranged between the flattening station and the finishing station of some treatment lines.

The central continuous post-treatment station generally comprises a common preheating section, a heating section, a soaking section, a slow cooling section, a quick cooling section, a balanced heat preservation section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section in sequence when the hot-dip pure zinc (GI) product is produced, as shown in figure 1. And a reheating section is arranged between the quick cooling section and the balanced heat preservation section, and an acid washing section and a reheating section are simultaneously arranged between the quick cooling section and the balanced heat preservation section by using other units. There are treatment lines with a movable post-plating quick-cooling section arranged within 10 meters above the air knife between the air knife section and the fixed post-plating cooling section (typically in the upper half of the APC tower). In the production of GA products, the central continuous post-treatment station typically comprises in sequence the equipment of a common preheating section-heating section-soaking section-slow cooling section-fast cooling section-balanced heat-preserving section-furnace nose section-zinc pot section-air knife section-alloying heating section-alloying soaking section-stationary post-plating cooling section and final water cooling section, as shown in fig. 2. And a reheating section is arranged between the quick cooling section and the balanced heat preservation section, and an acid washing section and a reheating section are simultaneously arranged between the quick cooling section and the balanced heat preservation section by using other units.

For the traditional hot-dip pure zinc and alloyed hot-dip galvanized strip steel treatment line and for the common preheating section and heating section, one common mode is direct fire heating, preferably clean natural gas is adopted for direct fire heating, unclean combustion waste gas is prevented from polluting the surface of the strip steel, the strip steel is directly preheated by the direct fire combustion waste gas, and the other common mode is heating by using a radiant tube, and the strip steel is preheated by the radiant tube combustion waste gas. The prior art has the following defects:

if the direct fire heating is adopted, the discharge temperature of the direct fire combustion exhaust gas after the strip steel is preheated is still higher, and is usually higher than 800 ℃, sometimes higher than 850 ℃, and when the discharge temperature exceeds 850 ℃, cold air is usually doped to control the exhaust gas discharge temperature to 850 ℃ or below so as to carry out secondary off-line utilization. The higher the exhaust gas temperature means more thermal energy is lost. According to the method, the primary online utilization rate of heat energy is low, and steam or hot water generated by secondary offline utilization cannot be completely consumed in the unit, so that the energy balance of the area is difficult; because the direct-fired waste gas directly contacts the strip steel and the contact time is longer, in addition, excessive fuel gas in the direct-fired waste gas needs to be subjected to secondary combustion in a preheating section, the secondary combustion flame is often an oxidizing flame, which necessarily limits the improvement of the preheating temperature of the strip steel, otherwise, an excessively thick oxide layer is easily formed on the surface of the strip steel, particularly for high-strength steel and ultra-high-strength steel, as the substrate is added with reinforced alloy elements such as Si, mn and the like, compared with a common strength product, the enrichment of the alloy reinforced elements is more easy to occur on the surface of the strip steel, the surface quality problem is caused, and therefore, the preheating temperature of the strip steel can only be preheated to about 250 ℃ generally, and the preheating effect is poor. If the radiant tube is adopted for heating, the discharge temperature of the combustion exhaust gas after preheating the strip steel is still higher, the temperature is usually higher than 350 ℃ when the high-temperature annealing material is produced, a boiler or a superheated water heating device is required to be added for secondary utilization of the waste heat of the combustion exhaust gas, the economic efficiency is obviously reduced, and the occupied area of equipment is large. In addition, the proportion of directly utilizing energy to the strip steel is low, namely a great amount of heat is still taken away by waste gas after the strip steel is preheated (the higher the temperature of the waste gas after the strip steel is preheated, the more heat is taken away), and the burnt heat is not fully transmitted to the strip steel (namely, the primary utilization rate of the energy is low). Also, the preheating of the strip is limited in temperature, and it is generally difficult to exceed 250 ℃.

Disclosure of Invention

The invention aims to provide a rapid hot galvanizing strip steel production line, which can realize the following purposes: when the direct fire heating is adopted, the waste heat of the waste gas generated by the direct fire combustion is fully utilized, the temperature of the strip steel can be quickly preheated to at least 350 ℃, and the waste gas generated by the direct fire combustion is prevented from directly contacting the strip steel in a preheating furnace for a long time, so that an excessively thick oxide layer is prevented from being generated on the surface of the strip steel; when the direct fire heating is not adopted, the novel heating technology is adopted, the waste heat of the combustion waste gas is fully utilized, the waste heat of the combustion waste gas is basically transmitted to the strip steel, the primary utilization rate of heat energy is improved, the combustion waste gas can be directly discharged after the strip steel is fully heated, a boiler or a superheated water heating device is not required to be added for secondary utilization, the investment is obviously reduced, and the occupied area is reduced.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

a rapid hot galvanizing strip steel production line sequentially comprises the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a preheating section, a heating section, a soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section;

The preheating section adopts a jet direct fire preheating device or a jet radiation composite heating device;

the heating section adopts a direct fire heating section and/or a radiant tube heating section;

the soaking section adopts a radiant tube soaking section or a jet-radiation composite soaking section;

and the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

The injection direct-fire preheating device heats the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange.

The jet-radiation composite heating section and the soaking section heat the strip steel by using the radiation of the radiation pipe, heat the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the radiation pipe, and jet the nitrogen-hydrogen protective gas to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

preferably, an alloying heating section and an alloying soaking section are arranged between the air knife section and the cooling section after plating; the hot dip galvanizing is alloying hot dip galvanizing.

Preferably, a movable post-plating quick cooling section capable of being switched on line/off line is arranged behind the air knife of the central continuous post-processing station, and the movable post-plating quick cooling section and the alloying heating section are arranged in parallel.

Preferably, a cleaning station is provided before the inlet looper station.

Preferably, the front and rear of the inlet looper station are respectively provided with a cleaning station.

Preferably, a central loop is provided before the levelling station and after the central continuous post-treatment station.

Preferably, a finishing station is arranged between the coiling station and the outlet looper station, and the strip steel is coiled after finishing.

Preferably, a withdrawal and straightening station is arranged between the flattening station and the outlet loop station, and the strip steel can be selectively withdrawn and straightened and then enter the outlet loop.

Preferably, a surface post-treatment station such as passivation or fingerprint resistance is arranged between the flattening station and the outlet loop station, and the strip steel can be subjected to surface treatment such as passivation or fingerprint resistance and then enter the outlet loop.

Preferably, a withdrawal and straightening station and a surface post-treatment station such as passivation or fingerprint resistance are arranged between the flattening station and the outlet loop station, and the strip steel can be selectively subjected to surface treatment such as withdrawal and straightening or/and passivation or fingerprint resistance and then enters the outlet loop.

For a hot-dip pure zinc unit for producing hot-dip pure zinc products, when direct fire heating is adopted, the rapid hot dip galvanized strip steel production line designed by the invention comprises the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; the central continuous post-treatment station sequentially comprises a jet direct fire preheating section, a direct fire heating section, a radiant tube soaking section or a jet-radiation composite soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section.

The injection direct-fire preheating section heats the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange.

And the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

When direct fire heating is not adopted, the rapid hot galvanizing strip steel production line designed by the invention comprises the following stations: uncoiling, welding, inlet looping, central continuous post-treatment, outlet looping, leveling and coiling; the central continuous post-treatment station sequentially comprises an air injection radiation composite heating section, a radiant tube soaking section or an air injection radiation composite soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section.

The jet-radiation composite heating section and the soaking section heat the strip steel by using the radiation of the radiation pipe, heat the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the radiation pipe, and jet the nitrogen-hydrogen protective gas to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

And the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

In the design of the production line of the invention:

for an alloying hot dip galvanizing unit for producing an alloying hot dip galvanizing product, when direct fire heating is used, the rapid alloying hot dip galvanizing strip steel production line designed by the invention comprises the following stations: uncoiling, welding, inlet looping, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a spraying direct fire preheating section, a direct fire heating section, a radiant tube soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, an alloying heating section, an alloying soaking section, a post-plating cooling section and a final water cooling section.

The injection direct-fire preheating section heats the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

When direct fire heating is not used, the rapid alloying hot dip galvanizing strip steel production line designed by the invention comprises the following stations: uncoiling, welding, inlet looping, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a jet-radiation composite heating section, a radiant tube soaking section, a slow cooling section, a high-hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, an alloying heating section, an alloying soaking section, a post-plating cooling section and a final water cooling section.

The jet-radiation composite heating section and the soaking section heat the strip steel by using radiation of a radiation pipe, heat the recycled nitrogen-hydrogen protective gas by using combustion waste gas of the radiation pipe, and jet the nitrogen-hydrogen protective gas to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

The soaking section adopts jet-radiation composite heating equipment to realize rapid adjustment of the soaking temperature of the strip steel when the working conditions such as thickness specification change, target temperature change, unit speed change and the like of the strip steel are changed.

Preferably, a hot-dip pure zinc station of a central continuous post-treatment station in the hot-dip pure zinc strip steel production line is provided with an optional movable post-dip quick cooling section after an air knife section and before a post-dip cooling section, the strip steel can be subjected to post-dip quick cooling after the movable post-dip quick cooling section is selected after the weight of a coating is controlled by air knife section equipment from zinc pot section hot dip galvanizing, or the movable post-dip quick cooling section can be not selected for natural cooling and then post-dip cooling, so that continuous production of hot dip galvanized high-strength strip steel is realized.

The alloying hot dip galvanized strip steel production line is characterized in that an optional movable post-plating quick cooling section is arranged in parallel with an alloying heating section after an air knife section of a central continuous post-treatment station, and if a hot dip galvanized pure zinc product is produced after the strip steel is hot dip galvanized from a zinc pot section and the coating weight is controlled by the air knife section, the movable post-plating quick cooling section is switched to be used on line, and the alloying heating section is off line; if the alloying hot dip galvanized product is produced, the fast cooling section is switched off after the mobile plating, and the alloying heating section equipment is switched on-line.

In addition, the invention also provides a jet direct-fire preheating device, which comprises: a direct fire furnace and a preheating furnace; wherein,

the direct fire includes:

a furnace shell, the upper end and the lower end of which are respectively provided with a furnace top roller chamber and a furnace bottom roller chamber; steering rollers are respectively arranged in the furnace top roller chamber and the furnace bottom roller chamber; a plurality of direct-fire heating areas are arranged in the furnace shell along the height direction, and a plurality of direct-fire burners are arranged in the direct-fire heating areas; the side wall of the upper part of the furnace shell is provided with at least two through holes which are symmetrically arranged left and right;

The preheating furnace comprises:

the side wall of the upper part of the furnace body is provided with at least two connecting holes which are symmetrically arranged left and right and are respectively connected with the through holes on the upper part of the furnace shell of the direct-fired furnace through communicating pipes; the top end of the furnace body is provided with a furnace throat which corresponds to the furnace top roller chamber of the direct furnace and is used for the strip steel to pass through; the bottom of the furnace body is provided with a strip steel inlet, a corresponding sealing device and a corresponding steering roller; an upper partition plate with a through hole is arranged at the upper part in the furnace body to form an upper gas collection chamber of the direct-fire waste gas; a direct-fire combustion waste gas secondary combustion chamber is arranged below the upper gas collection chamber of the direct-fire waste gas, and at least one open-fire burner is arranged in the direct-fire combustion waste gas secondary combustion chamber; preferably, a combustion waste gas thermometer is further arranged in the direct-fired combustion waste gas secondary combustion chamber; a lower partition plate with a penetrating hole is arranged at the lower part in the furnace body to form a lower straight fire waste gas collecting chamber, and the lower straight fire waste gas collecting chamber is connected with a waste gas fan through a waste gas discharge pipeline; a control valve is arranged on the waste gas discharge pipeline;

the heat exchange and air injection bellows units are arranged on two sides below the direct-fired combustion waste gas secondary combustion chamber in the furnace body along the height direction of the furnace body, and a strip penetrating channel for strip steel to pass through is formed in the middle of the heat exchange and air injection bellows units; each heat exchange and air injection bellows unit comprises,

the air box body is vertically provided with a plurality of heat exchange tubes, and a plurality of nozzles are arranged on one side surface of the air box body, which is opposite to the threading channel; an exhaust gas secondary mixing chamber communicated with the heat exchange tube is arranged between the upper and lower bellows bodies; introducing nitrogen and hydrogen protective gas into the bellows body;

The port of the inlet pipeline of the circulating fan is arranged in the threading channel, and the port of the outlet pipeline of the circulating fan is positioned in the bellows body;

the sealing devices are respectively arranged at the upper and lower ports of the threading channel and the threading holes of the upper and lower partition plates; preferably, the sealing device is of a nitrogen sealing structure, a nitrogen sealing chamber is adopted, and a nitrogen injection pipeline is arranged on the sealing device.

The invention also provides a jet-radiation composite heating/soaking device, which comprises:

the furnace body is internally provided with a composite heating body along the height direction; the composite heating body comprises an insulation box body, wherein an insulation material is arranged on the inner wall of the shell; a mounting hole is arranged in the center of one side surface of the heat preservation box body;

the circulating fan is arranged at the mounting hole of the heat insulation box body, the air suction inlet of the circulating fan corresponds to the axis of the mounting hole, and the air outlet is arranged on the side surface of the shell;

the buffer cavity is arranged in the insulation box body at a position corresponding to the air suction opening of the circulating fan, the back surface of the buffer cavity is provided with a hot air outlet corresponding to the air suction opening of the circulating fan, and the front surface of the buffer cavity is provided with a hot air inlet; preferably, the buffer cavity and the high-temperature air injection bellows are of an integrated structure;

the two high-temperature air jet bellows are vertically and symmetrically arranged at two sides of a hot air inlet at the front side of the buffer cavity in the heat insulation box body to form a strip penetrating channel for strip steel to pass through; a plurality of rows of jet nozzles are arranged on one side surface of the two high-temperature jet bellows at two sides of the threading channel at intervals along the height direction, and a gap is arranged between n rows of jet nozzles, wherein n is more than or equal to 1; n=1, the radiant tubes are arranged in parallel above or below the row of jet nozzles; preferably, the diameter of the jet nozzle is 1/10-1/5 of the distance from the jet nozzle to the strip steel; more preferably, the jet nozzle adopts a round hole structure;

The radiant tubes are symmetrically arranged in the two high-temperature air injection bellows and comprise a connecting tube section for connecting a burner, a radiant tube section bent and extended from one end of the connecting tube section and a heat exchange tube section formed by extending and bending from one end of the radiant tube section; the radiant tube section corresponds to gaps arranged between n rows of jet nozzles in the high-temperature jet bellows, so as to form a jet-radiation alternating structure; preferably, the radiant tube section, the connecting tube section and the heat exchange tube section of the radiant tube are arranged in parallel.

The jet-radiation composite heating/soaking device adopts a composite heating technology, can organically combine a high-speed high-temperature jet-heating technology with a radiant tube heating technology, and fully plays technical advantages of the high-speed high-temperature jet-heating technology and the radiant tube heating technology. The structure of the radiant tube is optimally designed, the radiant tube is arranged in the high-speed high-temperature jet air box, heat generated by burning gas of the radiant tube is rapidly transferred to the strip steel through two modes of high-speed high-temperature jet and radiation, the rapid heating of the strip steel is realized, the highest average heating speed of the strip steel of 1mm is not lower than 40 ℃/s, the length of a heating furnace can be greatly shortened, the heating section of a unit with 30 ten thousand tons per year output is about 2 pass, and the thermal inertia of a furnace body is reduced;

Second, heat generated by the fuel gas is transferred to the circulating gas (N ₂ +H ₂ ) The heat-conducting material is taken away, so that the exhaust temperature of the radiant tube can be reduced, the exhaust temperature of the radiant tube can be reduced by about 100 ℃ under the same condition, the heat efficiency of the radiant tube is improved by about 5%, the average working temperature of the radiant tube can be reduced, and the service life of the radiant tube is prolonged;

and the temperature of the heated circulating gas is uniform, so that the temperature distribution of the strip steel in the width direction in the heating process is uniform, and the temperature distribution of the strip steel in the width direction in the actual heating process is controlled to be +/-5 ℃ according to the uniformity of the strip steel in the width direction, thereby realizing the stable operation of the unit. The high-speed air injection and radiation composite heating technology can obviously improve the productivity of the existing unit and solve the problem of insufficient heating capacity on the production line.

The radiant tube of the jet-radiation composite heating/soaking device has the functions of combustion radiation (namely, a high-temperature section of the radiant tube between two rows of nozzles) and a heat exchanger, and is used for heating circulating gas, so that the heat of the combustion gas in the radiant tube can be rapidly transferred to strip steel through forced heat exchange, the rapid heating of the strip steel is realized, the length of a heating furnace can be greatly shortened, and the thermal inertia of a large vertical continuous annealing furnace body is reduced.

The production line of the invention has the following different points or innovation points from the traditional continuous heat treatment line:

1. when the invention uses direct fire for heating, the jet direct fire preheating section is used for replacing the common preheating section, and the invention is characterized in that:

(1) the method has the advantages that compared with the traditional preheating method, the heat loss of a furnace shell and a protective gas channel is obviously reduced, the waste heat utilization of combustion waste gas is more complete, the heating efficiency is higher, and the heating rate is faster;

(2) in the jet direct fire jet preheating section, the combustion waste gas of the heating section passes through a heat exchanger chamber of the preheating section, and in the passing process, the combustion waste gas of the heating section and a heat exchanger in the heat exchanger chamber perform sufficient heat exchange to heat the nitrogen-hydrogen protective gas, so that the combustion waste gas of the heating section in the jet direct fire jet preheating section is not always in direct contact with strip steel (when the heating section adopts direct fire heating, the jet direct fire jet preheating section is only in short time in a high-temperature section and the waste gas belongs to a reducing atmosphere or a micro-oxidizing atmosphere at the moment), thereby avoiding the surface peroxidation of the strip steel;

(3) When the heating section adopts direct fire heating, insufficiently combusted fuel gas in the direct fire combustion waste gas is subjected to oxygen-enriched secondary combustion in a semi-sealing unit at the top of the air injection preheating section, but the combusting flame does not contact strip steel, so that the surface peroxidation of the strip steel is effectively avoided;

(4) the preheating temperature of the strip steel is higher, and when the heating section adopts direct fire heating, the high-temperature nitrogen-hydrogen protective gas is sprayed, the direct fire spraying and preheating heat exchange coefficient is high, the temperature of the preheated strip steel at least can reach 350 ℃ or above, and is at least 100 ℃ higher than that of the strip steel in the common preheating section;

(5) when the heating section adopts direct fire heating, the temperature of the direct fire combustion exhaust gas from the preheating section of the jet radiant tube is usually far lower than 750 ℃ (if the number of the high-speed jet preheating units is enough, the high-speed jet preheating units can be directly discharged below 200 ℃), and the secondary utilization outside the furnace or the secondary utilization is not needed at all by using cold air.

When the direct fire heating is not used, the jet-air radiation composite heating section equipment is used for rapidly heating the strip steel, besides the radiation pipe is used for radiation heating of the strip steel, the radiation pipe is used for burning waste gas to heat the recycled nitrogen-hydrogen protective gas, then the nitrogen-hydrogen protective gas is sprayed to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange, the heat exchange efficiency is high, the waste gas temperature can be directly utilized and then is lower than 250 ℃ to be discharged, and the combustion heat is basically completely transmitted to the heating of the utilized strip steel.

The use of direct-fire heating equipment can be used for pre-oxidation reduction treatment of high-strength steel, so that the platability of the high-strength steel is improved;

the rapid heating and rapid cooling annealing treatment of the high-strength steel is realized by the cooperation of the direct fire heating equipment or the jet-air radiation composite heating equipment and the high-hydrogen rapid cooling equipment, so that the strength of the high-strength steel can be improved;

the invention is provided with the secondary reheating section equipment, realizes the twice lifting of the temperature of the strip steel before the hot galvanizing treatment, can realize the rapid cooling of third-generation high-strength steel (QP steel) products to lower temperature, then rapidly heats the products to higher temperature to carry out long-time carbon redistribution treatment, and rapidly re-heats the products to the temperature of a hot galvanizing zinc-entering pot for the second time after the treatment is finished to carry out the galvanizing treatment;

the alloy hot dip galvanized high-strength steel production line can simultaneously produce hot dip galvanized products of two plating layers of hot dip galvanized pure zinc and alloy hot dip galvanized.

The invention has the beneficial effects that:

1) The temperature of the preheated strip steel is high, and the primary utilization rate of heat energy is high;

2) The strip steel has good platability when adopting the direct fire heating technical scheme;

3) The secondary reheating equipment is adopted, so that the temperature of the strip steel is raised twice before hot galvanizing treatment, the third-generation high-strength steel (QP steel) product can be cooled to a lower temperature quickly, then the product is heated to a higher temperature quickly to carry out long-time carbon redistribution treatment, and the product is heated to the hot galvanizing zinc-entering pot temperature quickly after the treatment is finished, and then the galvanization treatment is carried out;

4) The rapid heating and rapid cooling treatment of the strip steel are realized, and the strip steel products with high strength level can be produced;

5) When the jet-air radiation composite soaking is adopted, the soaking temperature of the strip steel can be quickly adjusted when the working conditions such as the thickness specification of the strip steel is changed, the target temperature is changed, the unit speed is changed and the like are changed, and the quality loss caused by inconsistent strip steel temperature can be reduced.

Drawings

FIG. 1 is a station layout of a conventional hot dip Galvanizing (GI) line;

FIG. 2 is a station layout of a conventional Galvannealed (GA) production line;

FIG. 3 is a layout of the production line of embodiment 1 of the present invention;

FIG. 4 is a layout of the production line in accordance with embodiment 2 of the present invention;

FIG. 5 is a station layout of the production line of example 3 of the present invention;

FIG. 6 is a station layout of the production line of example 4 of the present invention;

FIG. 7 is a layout of the production line of embodiment 5 of the present invention;

FIG. 8 is a layout of the production line of embodiment 6 of the present invention;

FIG. 9 is a station layout of the production line of example 7 of the present invention;

FIG. 10 is a station layout of the production line of example 8 of the present invention;

FIG. 11 is a schematic view of an embodiment of a jet direct-fire preheating device according to the present invention;

FIG. 12 is a schematic view of a preheating furnace in an embodiment of the jet direct-fire preheating device according to the present invention;

FIG. 13 is a schematic view of an embodiment of a jet-propelled radiant composite heating/soaking device according to the present invention 1;

FIG. 14 is a schematic view of an embodiment of a jet-propelled radiant composite heating/soaking device according to the present invention in the schematic view of FIG. 2;

fig. 15 is a schematic structural diagram of a composite heating body in an embodiment of the jet-propelled radiant composite heating/soaking device according to the present invention;

FIG. 16 is a partial perspective view of a high temperature jet bellows in an embodiment of a jet radiant composite heating/soaking apparatus according to the present invention;

fig. 17 is a perspective view of a radiant tube in an embodiment of the jet radiant composite heating/soaking device according to the present invention.

Detailed Description

The invention is further illustrated by the following examples and figures: it should be noted that, by applying the inventive concept, various production lines can be derived and expanded, only some embodiments are given in this example, and other embodiments are given in the inventive ethnic patent, even if all ethnic patent examples are given only some embodiments, various combinations generated by selecting or not selecting stations or segments according to the inventive concept are within the scope of the present invention, and various production lines derived according to the inventive concept are also within the scope of the present invention. In addition, for conventional stations, such as cleaning stations comprising an alkali liquor spraying section, an alkali liquor brushing section, an electrolytic cleaning section, a hot water brushing or cold water abrasive particle roller brushing section and a hot water rinsing section, even the cleaning new technical equipment which is simplified and combined by adopting a high-pressure water jet brushing section, an ultrasonic cleaning section, a high-pressure cleaning section and the like is considered to be the production line of the invention, and the production line is also within the protection scope of the invention. As another example, finishing stations including trimming, oiling, etc., are also within the scope of the present invention.

Referring to fig. 3, the rapid hot dip galvanizing strip steel production line provided by the invention sequentially comprises the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a spraying direct fire preheating section, a direct fire heating section, a radiant tube soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section.

The injection direct-fire preheating section heats the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 4, an embodiment 2 of the present invention is shown, and in the embodiment 2, the rapid hot dip galvanized strip steel production line sequentially includes the following steps: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises an air injection radiation composite heating section, a radiant tube soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section.

The jet-air radiation composite heating section heats the strip steel by using radiation of a radiation pipe, heats the recycled nitrogen-hydrogen protective gas by using combustion waste gas of the radiation pipe, and then sprays the nitrogen-hydrogen protective gas onto the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 5, an embodiment 3 of the present invention is shown, and in the embodiment 3, the rapid hot dip galvanizing strip steel production line sequentially includes the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a spraying direct fire preheating section, a direct fire heating section, a radiant tube heating section, a spraying and radiating composite soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section.

The injection direct-fire injection preheating section is characterized in that the nitrogen-hydrogen protective gas which is circularly utilized is heated by using combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

And the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 6, an embodiment 4 of the present invention is shown, and in the embodiment 4, the rapid hot dip galvanizing strip steel production line sequentially includes the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a jet-radiation composite heating section, a radiant tube heating section, a jet-radiation composite soaking section, a slow cooling section, a high-hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section.

The jet-air radiation composite heating section and the soaking section heat the strip steel by using radiation of a radiation pipe, heat the recycled nitrogen-hydrogen protective gas by using combustion waste gas of the radiation pipe, and jet the nitrogen-hydrogen protective gas to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange.

And the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 7, which shows embodiment 5 of the present invention, in embodiment 5, the following stations are included: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

The central continuous post-treatment station sequentially comprises a spraying direct fire preheating section, a direct fire heating section, a radiant tube soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, an alloying heating section, an alloying soaking section, a post-plating cooling section and a final water cooling section.

The injection direct-fire injection preheating section is characterized in that the nitrogen-hydrogen protective gas which is circularly utilized is heated by using combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 8, the rapid alloying hot dip galvanized strip steel production line sequentially comprises the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a jet-radiation composite heating section, a radiant tube soaking section, a slow cooling section, a high-hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, an alloying heating section, an alloying soaking section, a post-plating cooling section and a final water cooling section.

The jet-air radiation composite heating section heats the strip steel by using radiation of a radiation pipe, heats the recycled nitrogen-hydrogen protective gas by using combustion waste gas of the radiation pipe, and then sprays the nitrogen-hydrogen protective gas onto the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 9, the rapid alloying hot dip galvanized strip steel production line sequentially comprises the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a spraying direct fire preheating section, a direct fire heating section, a radiant tube heating section, a spraying and radiating composite soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, an alloying heating section, an alloying soaking section, a post-plating cooling section and a final water cooling section.

The injection direct-fire injection preheating section heats the recycled nitrogen-hydrogen protective gas by using the combustion waste gas of the direct-fire heating section, and then the nitrogen-hydrogen protective gas is injected to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

And the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Referring to fig. 10, an embodiment 6 of the present invention is shown, and in the embodiment 6, the rapid alloying hot dip galvanized strip steel production line sequentially includes the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a jet-radiation composite heating section, a radiant tube heating section, a jet-radiation composite soaking section, a slow cooling section, a high-hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, an alloying heating section, an alloying soaking section, a post-plating cooling section and a final water cooling section.

The jet-radiation composite heating section and the soaking section heat the strip steel by using radiation of a radiation pipe, heat the recycled nitrogen-hydrogen protective gas by using combustion waste gas of the radiation pipe, and jet the nitrogen-hydrogen protective gas to the upper surface and the lower surface of the strip steel to realize forced convection heat exchange;

and the reheating section and the secondary reheating section both use longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

Preferably, an optional movable post-plating quick cooling section is further arranged behind the air knife section and in front of the post-plating cooling section of the central continuous post-processing station, the strip steel can be subjected to post-plating quick cooling by selecting the movable post-plating quick cooling section after the weight of the plating layer is controlled by the air knife section from the zinc pot section hot galvanizing, and the strip steel can be subjected to post-plating cooling after natural cooling without selecting the movable post-plating quick cooling section, so that continuous production of hot galvanized strip steel is realized.

Referring to fig. 11 and 12, the injection direct-fire preheating device according to the present invention includes: a direct burner 1 and a preheating furnace 2; wherein,

the direct burner 1 comprises:

a furnace shell 11, the upper and lower ends of which are respectively provided with a furnace top roller chamber 101 and a furnace bottom roller chamber 102; the furnace top roller chamber 101 and the furnace bottom roller chamber 102 are respectively provided with steering rollers 12 and 12'; a plurality of direct-fire heating areas 111 are arranged in the furnace shell 11 along the height direction, and a plurality of direct-fire burners 13 are arranged in the direct-fire heating areas 111; the side wall of the upper part of the furnace shell 11 is provided with two through holes which are symmetrically arranged left and right;

the preheating furnace 2 includes:

the furnace body 21 is provided with two connecting holes on the side wall of the upper part, is symmetrically arranged left and right, and is respectively connected with the through holes on the upper part of the furnace shell 11 of the direct-fired furnace 1 through the communicating pipe 22; the top end of the furnace body 21 is provided with a furnace throat 211 which corresponds to the furnace top roller chamber 101 of the direct furnace 1 and is used for the strip steel to pass through; the bottom of the furnace body 21 is provided with a strip steel inlet and a corresponding sealing device 212 and a steering roller 23; an upper partition plate 213 with a through hole is arranged at the upper part in the furnace body 21 to form a direct-fire waste gas upper gas collection chamber 201; a direct-fire combustion waste gas secondary combustion chamber 202 is arranged below the direct-fire waste gas upper gas collection chamber 201, and at least one open-fire burner 24 is arranged in the direct-fire combustion waste gas secondary combustion chamber 202; a lower partition plate 214 with a penetrating hole is arranged at the lower part in the furnace body 21 to form a lower straight fire waste gas collecting chamber 203 and is connected with a waste gas fan 25 through a waste gas discharge pipeline 215;

A plurality of heat exchange and air injection bellows units 26 which are arranged at two sides below the direct-fire combustion waste gas secondary combustion chamber 202 in the furnace body 21 along the height direction of the furnace body 21, and a penetrating channel 204 for the strip steel to pass through is formed in the middle; each heat exchange and air injection bellows unit 26 includes,

a bellows body 261, in which a plurality of heat exchange tubes 262 are vertically arranged, and a plurality of nozzles 263 are arranged on one side surface of the bellows body 261 opposite to the threading channel 204; an exhaust gas secondary mixing chamber 205 communicated with the heat exchange tube 262 is arranged between the upper and lower bellows bodies 261; introducing nitrogen and hydrogen protective gas into the bellows 261;

a circulating fan 264, the inlet of which is arranged in the threading channel 204, and the outlet of which is arranged in the bellows 261;

a plurality of sealing devices 27, 27', 27″ for the strip steel to pass through are respectively arranged at the upper and lower ports of the strip passing channel 204 and at the strip passing holes of the upper and lower partition plates 213, 214.

Preferably, a combustion exhaust gas thermometer 28 is also disposed in the direct-fired combustion exhaust gas secondary combustion chamber 202.

Preferably, the sealing devices 27, 27', 27″ are nitrogen sealing structures, and nitrogen sealing chambers are adopted, on which nitrogen injection pipelines are arranged.

Preferably, a control valve 216 is provided on the exhaust gas discharge pipe 215.

The strip steel 100 is turned to upwards run by a turning roll in front of the direct fire furnace, enters the preheating furnace 2 for preheating after being sealed by a preheating furnace inlet sealing device, then enters a furnace top roll chamber of the direct fire furnace 1 for direct fire heating after being turned by the turning roll, then enters a furnace bottom roll chamber of the direct fire furnace 1 for continuous running after being turned by the turning roll.

The temperature of the waste gas is reduced after the nitrogen-hydrogen protective gas is heated by the direct-fire combustion waste gas through the heat exchange pipeline (the nitrogen-hydrogen protective gas is blown to the upper surface and the lower surface of the strip steel to preheat the strip steel under the action of the circulating fan), and the nitrogen-hydrogen protective gas after the temperature reduction is sucked into the bellows by the circulating fan 264 on the two sides of the working side (WS side) and the driving side (DS side) of the preheating furnace to exchange heat with the heat exchange pipeline; the direct-fired combustion waste gas sequentially passes through the heat exchange and air injection bellows unit from top to bottom, is subjected to secondary utilization of the waste heat of the combustion waste gas outside the furnace through the waste heat boiler 400 under the suction of the variable-frequency waste gas fan 25 and enters the chimney 500 for final discharge.

Referring to fig. 13 to 17, the jet-radiation composite heating/soaking device according to the present invention includes:

a furnace body 4 in which a composite heating body 5 is arranged in the height direction; the composite heating body 5 comprises a metal sheet and a metal sheet,

A heat-insulating box 51, the inner wall of which is provided with a heat-insulating material; a mounting hole is arranged in the center of one side surface of the heat preservation box body 51;

the circulating fan 52 is arranged at the mounting hole of the heat insulation box body 51, the air suction inlet 521 of the circulating fan corresponds to the axis of the mounting hole, and the air outlet 522 is arranged on the side surface of the casing;

the buffer cavity 53 is arranged in the insulation box 51 at a position corresponding to the air suction opening of the circulating fan 52, the back surface of the buffer cavity 53 is provided with a hot air outlet corresponding to the air suction opening of the circulating fan 52, and the front surface of the buffer cavity is provided with a hot air inlet;

the two high-temperature air jet bellows 54, 54' are vertically and symmetrically arranged at two sides of the hot air inlet at the front side of the buffer cavity 53 in the heat insulation box body 51 to form a strip penetrating channel 200 for the strip 100 to penetrate through; a plurality of rows of jet nozzles 55, 55 'are arranged on one side surface of the two high-temperature jet bellows 54, 54' positioned on two sides of the threading channel 100 at intervals along the height direction, and a gap 300 is arranged between n rows of jet nozzles, wherein n is more than or equal to 1;

the plurality of radiant tubes 56, 56 'are symmetrically arranged in the two high-temperature jet bellows 54, 54', and the radiant tubes 56 (radiant tubes 56 are exemplified by the same below) comprise a connecting tube section 561 for connecting with a burner, a radiant tube section 562 which is bent and extended from one end of the connecting tube section 561, and a heat exchange tube section 563 which is formed by extending and bending from one end of the radiant tube section 562; the radiant tube sections 562 correspond to the gaps 300 provided between the n rows of jet nozzles in the high temperature jet bellows 54 to form an alternating jet and radiant configuration.

Preferably, the buffer cavity and the high-temperature air injection bellows are of an integrated structure.

Preferably, the diameter of the jet nozzle is 1/10-1/5 of the distance from the jet nozzle to the strip steel.

Preferably, the jet nozzle adopts a round hole structure.

Preferably, the radiant tube adopts a space four-stroke structure to form four sections of tube sections which are arranged in parallel, wherein one of the tube sections is a radiant tube section, and the rest is a connecting tube section and a heat exchange tube section.

Example 1

A production line arrangement is shown in figure 3, the strip steel with the main chemical composition (mass%) of 0.1 percent C-0.50 percent Si-1.95 percent Mn is uncoiled, welded, passed through an inlet loop and cleaned, then preheated to 360 ℃ by adopting jet straight fire, heated to 680 ℃ by adopting straight fire, then heated to 800 ℃ by adopting a radiant tube, soaked for 50 seconds by the radiant tube at 800 ℃, slowly cooled to 670 ℃ and cooled to 470 ℃ by high hydrogen, and then immersed into a zinc pot through a reheating section (the reheating function is not needed), a balanced heat-preserving section and a secondary reheating section (the secondary reheating function is not needed), plated and cooled after plating after controlling the plating weight through an air knife, finally cooled to room temperature, flattened, fed into an outlet loop and coiled to finish production. The yield strength of the final product strip steel is 365MPa, the tensile strength is 685MPa, and the breaking elongation is 26%.

Example 2

A production line arrangement is shown in figure 4, the strip steel with the main chemical composition (mass%) of 0.18 percent C-1.7 percent Si-2.3 percent Mn is uncoiled, welded, passed through an inlet loop and cleaned, then is heated to 670 ℃ by jet radiation in a compounding way, then is heated to 850 ℃ by a radiation pipe, is soaked for 80 seconds by the radiation pipe, is slowly cooled to 675 ℃, is cooled to 230 ℃ by high hydrogen, is heated to 400 ℃ again, is uniformly insulated at 400 ℃, is immersed in a zinc pot after being secondarily heated to 455 ℃ and is hot-galvanized after the plating weight is controlled by an air knife, is cooled after being plated, is finally cooled to room temperature by water, is leveled and then enters an outlet loop, and is coiled to finish production. The final product band steel has the yield strength of 726MPa, the tensile strength of 1058MPa and the breaking elongation of 19 percent.

Example 3

A hot dip galvanized strip steel is prepared through such steps as uncoiling the strip steel whose main chemical composition (mass%) is 0.11-0.46-2.0% Mn, welding, passing entrance loop, washing, spraying straight fire, preheating to 355 deg.C, heating to 675 deg.C, heating to 795 deg.C, spraying air at 795 deg.C, radiating for 60 seconds, slow cooling to 675 deg.C, cooling high hydrogen to 475 ℃, immersing a zinc pot through a furnace nose for hot galvanizing through a reheating section (the reheating function does not need to be input), a balanced heat preservation section and a secondary reheating section (the secondary reheating function does not need to be input), cooling after plating after controlling the weight of a coating through an air knife, finally cooling to room temperature through water, leveling, entering an outlet loop, and coiling to finish production. The yield strength of the final product strip steel is 398MPa, the tensile strength is 696MPa, and the breaking elongation is 28%.

Example 4

A preparation method of hot dip galvanized strip steel comprises the steps of uncoiling, welding, passing an inlet loop through and cleaning strip steel with the main chemical component (mass%) of 0.17% C-1.75% Si-2.2% Mn, adopting jet radiation to heat to 705 ℃, then heating a radiant tube to 855 ℃, carrying out jet radiation to soak for 80 seconds, slowly cooling to 670 ℃, cooling high hydrogen to 230 ℃, then heating to 395 ℃, carrying out balanced heat preservation at 395 ℃, then carrying out secondary reheating to 457 ℃, immersing in a zinc pot through a furnace nose for hot dip, carrying out cooling after plating by an air knife to control the weight of a plating layer, finally carrying out water cooling to room temperature, entering an outlet loop after leveling, and then coiling to finish the production. The yield strength of the final product strip steel is 715MPa, the tensile strength is 1036MPa, and the breaking elongation is 21%.

Example 5

A hot dip galvanized strip steel is prepared through uncoiling, welding, passing through inlet loop, washing, preheating to 350 deg.C, heating to 670 deg.C, heating to 810 deg.C, immersing in radiant tube for 60 seconds, slow cooling to 670 deg.C, cooling to 465 deg.C, reheating, immersing in zinc pot for hot dip galvanizing, alloying and heating to 500 deg.C, alloying and immersing in water for 18 seconds, cooling to room temperature, coiling, and cooling. The yield strength of the final product strip steel is 550MPa, the tensile strength is 837MPa, and the breaking elongation is 19%.

Example 6

A preparation method of hot dip galvanized strip steel comprises the steps of uncoiling, welding, passing an inlet loop through and cleaning strip steel with the main chemical component (mass%) of 0.165% C-1.8% Si-2.25% Mn, heating to 670 ℃ by adopting jet radiation in a combined mode, heating to 855 ℃ by using a radiation pipe, carrying out jet radiation in a combined mode for 90 seconds, slowly cooling to 670 ℃, cooling to 220 ℃ by high hydrogen, then heating to 410 ℃ for balanced heat preservation, carrying out secondary reheating to 460 ℃, immersing the strip steel in a zinc pot through a furnace nose for hot dip, carrying out alloying heating to 515 ℃ after the weight of a coating is controlled by an air knife, carrying out alloying soaking for 22 seconds at 510 ℃, cooling after plating, carrying out final water cooling to room temperature, flattening, entering an outlet loop, and coiling to finish production. The yield strength of the final product strip steel is 732MPa, the tensile strength is 1028MPa, and the elongation at break is 18%.

Claims (9)

1. The rapid hot galvanizing strip steel production line is characterized by sequentially comprising the following stations: uncoiling, welding, inlet looping, cleaning, central continuous post-treatment, outlet looping, leveling and coiling; wherein,

the central continuous post-treatment station sequentially comprises a preheating section, a heating section, a soaking section, a slow cooling section, a high hydrogen cooling section, a reheating section, a balanced heat preservation section, a secondary reheating section, a furnace nose section, a zinc pot section, an air knife section, a post-plating cooling section and a final water cooling section;

The preheating section adopts a jet direct fire preheating device or a jet radiation composite heating device;

the heating section adopts a direct fire heating section and/or a radiant tube heating section;

the soaking section adopts a radiant tube soaking section or a jet-radiation composite soaking section;

and the reheating section and the secondary reheating section adopt longitudinal magnetic induction heating equipment to rapidly heat the strip steel.

2. The rapid hot dip galvanized strip steel production line according to claim 1, wherein an alloying heating section and an alloying soaking section are arranged between the air knife section and the cooling section after plating; the hot dip galvanizing is alloying hot dip galvanizing.

3. The rapid hot-dip galvanized strip steel production line according to claim 1 or 2, characterized in that the air knife section of the central continuous post-treatment station is provided with a movable post-plating rapid cooling section which can be switched on line/off line, and the movable post-plating rapid cooling section is arranged in parallel with the alloying heating section.

4. A rapid hot dip galvanised strip steel production line according to any one of claims 1 to 3 characterised in that a cleaning station is provided before the inlet looper station or before and after the inlet looper station.

5. The rapid thermal galvanization strip steel production line of any of claims 1 to 4, wherein a central loop is provided before the levelling station and after the central continuous post-treatment station.

6. The rapid thermal galvanization strip steel production line of any one of claims 1 to 5, wherein a finishing station is provided between the coiling station and the outlet looper station.

7. The rapid thermal galvanization strip steel production line according to any one of claims 1 to 6, characterized in that a withdrawal and straightening station is arranged between the flattening station and the outlet looper station; or, a passivation or fingerprint-resistant surface post-treatment station is arranged between the leveling station and the outlet looper station; or, a withdrawal straightening station and a surface post-treatment station such as passivation or fingerprint resistance are arranged between the flattening station and the outlet looper station.

8. A spray direct-fire preheating device for a rapid thermal galvanization strip steel production line according to any one of claims 1 to 7, characterized by comprising: a direct fire furnace and a preheating furnace; wherein, the direct fire includes:

a furnace shell, the upper end and the lower end of which are respectively provided with a furnace top roller chamber and a furnace bottom roller chamber; steering rollers are respectively arranged in the furnace top roller chamber and the furnace bottom roller chamber; a plurality of direct-fire heating areas are arranged in the furnace shell along the height direction, and a plurality of direct-fire burners are arranged in the direct-fire heating areas; the side wall of the upper part of the furnace shell is provided with at least two through holes which are symmetrically arranged left and right;

The preheating furnace comprises:

the side wall of the upper part of the furnace body is provided with at least two connecting holes which are symmetrically arranged left and right and are respectively connected with the through holes on the upper part of the furnace shell of the direct-fired furnace through communicating pipes; the top end of the furnace body is provided with a furnace throat which corresponds to the furnace top roller chamber of the direct furnace and is used for the strip steel to pass through; the bottom of the furnace body is provided with a strip steel inlet, a corresponding sealing device and a corresponding steering roller; an upper partition plate with a through hole is arranged at the upper part in the furnace body to form an upper gas collection chamber of the direct-fire waste gas; a direct-fire combustion waste gas secondary combustion chamber is arranged below the upper gas collection chamber of the direct-fire waste gas, and at least one open-fire burner is arranged in the direct-fire combustion waste gas secondary combustion chamber; preferably, a combustion waste gas thermometer is further arranged in the direct-fired combustion waste gas secondary combustion chamber; a lower partition plate with a penetrating hole is arranged at the lower part in the furnace body to form a lower straight fire waste gas collecting chamber, and the lower straight fire waste gas collecting chamber is connected with a waste gas fan through a waste gas discharge pipeline; a control valve is arranged on the waste gas discharge pipeline;

the heat exchange and air injection bellows units are arranged on two sides below the direct-fired combustion waste gas secondary combustion chamber in the furnace body along the height direction of the furnace body, and a strip penetrating channel for strip steel to pass through is formed in the middle of the heat exchange and air injection bellows units; each heat exchange and air injection bellows unit comprises,

the air box body is vertically provided with a plurality of heat exchange tubes, and a plurality of nozzles are arranged on one side surface of the air box body, which is opposite to the threading channel; an exhaust gas secondary mixing chamber communicated with the heat exchange tube is arranged between the upper and lower bellows bodies; introducing nitrogen and hydrogen protective gas into the bellows body;

The port of the inlet pipeline of the circulating fan is arranged in the threading channel, and the port of the outlet pipeline of the circulating fan is positioned in the bellows body;

the sealing devices are respectively arranged at the upper and lower ports of the threading channel and the threading holes of the upper and lower partition plates; preferably, the sealing device is of a nitrogen sealing structure, a nitrogen sealing chamber is adopted, and a nitrogen injection pipeline is arranged on the sealing device.

9. A jet-radiation composite heating/soaking apparatus for a rapid thermal galvanization strip steel production line according to any one of claims 1 to 7, characterized by comprising:

the furnace body is internally provided with a composite heating body along the height direction; the composite heating body comprises an insulation box body, wherein an insulation material is arranged on the inner wall of the shell; a mounting hole is arranged in the center of one side surface of the heat preservation box body;

the circulating fan is arranged at the mounting hole of the heat insulation box body, the air suction inlet of the circulating fan corresponds to the axis of the mounting hole, and the air outlet is arranged on the side surface of the shell;

the buffer cavity is arranged in the insulation box body at a position corresponding to the air suction opening of the circulating fan, the back surface of the buffer cavity is provided with a hot air outlet corresponding to the air suction opening of the circulating fan, and the front surface of the buffer cavity is provided with a hot air inlet; preferably, the buffer cavity and the high-temperature air injection bellows are of an integrated structure;

The two high-temperature air jet bellows are vertically and symmetrically arranged at two sides of a hot air inlet at the front side of the buffer cavity in the heat insulation box body to form a strip penetrating channel for strip steel to pass through; a plurality of rows of jet nozzles are arranged on one side surface of the two high-temperature jet bellows at two sides of the threading channel at intervals along the height direction, and a gap is arranged between n rows of jet nozzles, wherein n is more than or equal to 1; preferably, the diameter of the jet nozzle is 1/10-1/5 of the distance from the jet nozzle to the strip steel; more preferably, the jet nozzle adopts a round hole structure;

the radiant tubes are symmetrically arranged in the two high-temperature air injection bellows and comprise a connecting tube section for connecting a burner, a radiant tube section bent and extended from one end of the connecting tube section and a heat exchange tube section formed by extending and bending from one end of the radiant tube section; the radiant tube section corresponds to gaps arranged between n rows of jet nozzles in the high-temperature jet bellows, so as to form a jet-radiation alternating structure; preferably, the radiant tube section, the connecting tube section and the heat exchange tube section of the radiant tube are arranged in parallel.