Gas energy-saving control method for cold-rolled continuous heating annealing furnace

Abstract

The present application relates to the field of strip annealing, and relates to a gas energy-saving control method for a cold-rolled continuous heating annealing furnace. The cold-rolled continuous heating annealing furnace comprises at least two series-connected horizontal continuous heating annealing furnaces, each of which comprises at least one heating zone, and all the heating annealing furnaces have M heating zones in total, the i-th heating zone has Ai natural gas burners, M is a natural number, i is a natural number less than or equal to M, the natural gas burners of each heating zone are arranged in an equal interval on the upper and lower sides of the furnace body, and the gas energy-saving control method for the cold-rolled continuous heating annealing furnace comprises the following steps: collecting basic parameters, calculating the product of the running speed and the thickness of the steel strip to be annealed, i.e. the TV value, calculating the target furnace temperature of each zone, and controlling the gas flow of the burners in each zone. The heating demand is determined according to the high and low temperatures of each zone, the higher the temperature, the greater the required heating load, and the more the distributed gas amount.

Description

Technical Field

[0001] This invention relates to the field of strip steel annealing, and in particular to a gas energy-saving control method for a cold-rolled continuous heating annealing furnace. Background Technology

[0002] The continuous annealing furnace for cold rolling is the core heat treatment equipment in the cold rolling production line. Cold-rolled strip steel (steel strip) passes through each process section of the furnace continuously at high speed, and completes heating, recrystallization, heat preservation, cooling, and over-aging under a nitrogen and hydrogen protective atmosphere. This process eliminates cold rolling work hardening and internal stress, regulates grain structure, and obtains the mechanical properties required for stamping and high-strength steel. Unlike bell-type annealing (intermittent coil annealing), it features high temperature and short time, fast production speed, and uniform performance.

[0003] In a horizontal continuous heating annealing furnace (horizontal type), the strip steel runs horizontally, the equipment height is low, and the investment is small; it is suitable for small-capacity cold rolling annealing of silicon steel and stainless steel.

[0004] Cold rolling continuous annealing furnaces typically consist of at least two horizontal continuous heating annealing furnaces connected in series. Each annealing furnace includes multiple heating zones, and each heating zone is equipped with multiple burners. The burners in each zone are arranged symmetrically and at equal intervals along the upper and lower sides of the furnace body. Natural gas is used as the core combustion medium, and the furnace is mainly used for the annealing of cold-rolled stainless steel strips, including 300 series and 400 series.

[0005] Existing energy-saving control technologies for annealing furnaces mostly focus on hardware improvements such as burner structure optimization and waste heat recovery, and have not formed an energy-saving control system based on the linkage of steel grade, strip width, thickness and TV value. Summary of the Invention

[0006] The technical problem to be solved by this invention is: how to provide an energy-saving method for precise control of gas consumption in a continuous heating annealing furnace for cold-rolled steel strip, taking into account the steel grade, strip width and thickness specifications and TV value.

[0007] The technical solution adopted in this invention is: a gas-saving control method for a cold-rolling continuous heating annealing furnace, comprising at least two series-connected horizontal continuous heating annealing furnaces, each heating annealing furnace including at least one heating zone, and a total of M heating zones in all heating annealing furnaces, wherein the i-th heating zone has Ai natural gas burners, where M is a natural number and i is a natural number less than or equal to M, and the natural gas burners in each heating zone are arranged at equal intervals on the upper and lower sides of the furnace body. The gas-saving control method for this cold-rolling continuous heating annealing furnace includes the following steps: Step 1: Basic parameter acquisition. Real-time acquisition of core process parameters of the steel strip to be annealed, including steel type G, strip thickness H, strip width W, and strip running speed V. Determine the target annealing plate temperature T of the steel strip to be annealed before annealing, in °C. Step 2: Calculate the TV value, which is the product of the running speed and thickness of the steel strip to be annealed; TV = V * H; Where V is the running speed of the steel strip to be annealed, in m / min, and H is the thickness of the steel strip to be annealed, in mm; Step 3: Calculate the target furnace temperature for each zone. The first heating zone to the Mth heating zone are arranged sequentially along the strip conveying direction. The target temperature of the strip in the Mth heating zone, i.e., the target annealing plate temperature T, is used as the temperature control benchmark. The target furnace temperature of the ith heating zone is Ti. Ti=T*K1*K2*(1+bi*TV / 100); Where K1 is the steel grade correction coefficient, K2 is the width correction coefficient, and bi is the TV value adjustment coefficient of the i-th heating zone; Step 4: Zoned control of burner gas flow. The furnace temperature of each zone is used as the basis for heating demand. The higher the furnace temperature, the greater the required heating load, and the more gas is allocated. The burner gas allocation ratio Si for the i-th heating zone is as follows: Si = Ti / ΣTi; The gas supply Qi to the burners in the i-th heating zone; Qi = Q_total * Si; Where ΣTi is the sum of the target furnace temperatures of all heating zones, Q_total is the total gas supply of the entire furnace, and the target temperature of the steel strip in the Mth heating zone is equal to the target furnace temperature of the Mth heating zone; the gas supply of each zone burner is equally distributed according to the number of burners in each zone.

[0008] Gas flow rate of a single burner in zones 1-16 = (gas supply in each zone 1-16) / 14; Gas flow rate of a single burner in zones 17-18 = (gas supply in each zone 1-18) / 16.

[0009] Based on the gas flow rate of each burner in each heating zone, and based on the deviation between the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone and Ti, the gas flow rate of each burner in the upper and lower sides of the furnace body in the i-th heating zone is adjusted in real time; where Q_total is the total gas supply of the entire furnace.

[0010] When the steel strip to be annealed is a 300 series cold-rolled steel strip, the target annealing temperature T is 1020-1130℃; when the steel strip to be annealed is a 400 series cold-rolled steel strip, the target annealing temperature T is 750-900℃.

[0011] Steel type G is classified according to the different steel grades of the steel strip to be annealed, and a number is assigned to steel type G. The steel grade of the steel strip to be annealed can be determined by steel type G.

[0012] When the steel strip to be annealed is 400 series cold-rolled steel strip, the value of K1 is 1.0-1.012; when the steel strip to be annealed is 300 series cold-rolled steel strip, the value of K1 is 1.002-1.016.

[0013] K2 = (W - 1000) / 10000 + 0.95; W is the strip width, in mm.

[0014] Based on the deviation between the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone and Ti, the gas flow rate of the single burner on the upper and lower sides of the furnace body in the i-th heating zone is adjusted in real time. Specifically, the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone is T0, and the gas flow rate of the single burner on the upper and lower sides of the furnace body in the i-th heating zone is adjusted to Tj. Tj = Ti + Ti * (T0 - Ti) / T0; The deviation, i.e. (T0-Ti) / T0, is -5% to 5%.

[0015] The beneficial effects of this invention are as follows: This invention is the first to integrate the calculation formula for annealing furnace temperature control based on steel grade, strip width, and TV value, achieving precise matching between gas heating and the actual heat demand of the steel strip. It completely changes the traditional experience-based extensive control mode and achieves precise temperature control in zones for differentiated annealing processes of stainless steels such as 300 series and 400 series. Compared with the traditional control method, gas energy consumption is reduced by 12%-18%, resulting in significant energy-saving effects.

[0016] This invention addresses the burner layout characteristics of multi-zone horizontal series continuous annealing furnaces, enabling precise distribution of gas flow to each zone's burners. The flow deviation between the upper and lower burners is controlled within 5%, ensuring uniform furnace temperature and preventing gas waste caused by local overheating. Simultaneously, it guarantees a steel strip annealing plate temperature qualification rate of ≥99.5%.

[0017] This invention automatically corrects temperature control parameters based on real-time temperature detection data, adapting to continuous production of steel strips of different specifications and steel grades, and has strong versatility. Detailed Implementation

[0018] In this embodiment of the invention, two series-connected horizontal continuous heating annealing furnaces (heating furnaces) are used. The steel strip to be annealed passes sequentially through heating annealing furnace #1 and heating annealing furnace #2. The two heating annealing furnaces have a total of 18 heating zones (M=18). Heating annealing furnace #1 includes heating zones 1-8, and heating annealing furnace #2 includes heating zones 9-18. The two heating annealing furnaces are equipped with 256 natural gas burners. Zones 1-16 each have 16 burners, and zones 17-18 each have 18 burners. The burners in each zone are arranged symmetrically and at equal intervals along the upper and lower sides of the furnace body. When i is a natural number less than or equal to 16, Ai=16; when i=17 or 18, Ai=18.

[0019] Example 1: This example uses 400 series cold-rolled steel strip as the steel strip to be annealed.

[0020] The energy-saving control method for gas in a cold rolling continuous heating annealing furnace includes the following steps: Step 1: Basic Parameter Acquisition. Real-time acquisition of core process parameters for the steel strip to be annealed, including steel type G, strip thickness H, strip width W, and strip running speed V. The target annealing plate temperature T for the steel strip is determined before annealing, in °C. Steel type G is categorized according to different steel grades and assigned a number. The steel type G determines the steel grade of the steel strip to be annealed. For example, in this invention, G=1 is set for cold-rolled steel strip of 400 series steel, G=2 for cold-rolled steel strip of 300 series steel, strip thickness H=2.0mm, strip width W=1250mm, strip running speed V=40m / min, and target annealing plate temperature T=820℃.

[0021] Step 2: Calculate the TV value, which is the product of the running speed and thickness of the steel strip to be annealed; TV = V * H = 40 * 2.0 = 80 m * mm / min; Where V is the running speed of the steel strip to be annealed, in m / min, and H is the thickness of the steel strip to be annealed, in mm.

[0022] Step 3: Calculate the target furnace temperature for each zone. The first heating zone to the Mth heating zone are arranged sequentially along the strip conveying direction. The target temperature of the strip in the Mth heating zone, i.e., the target annealing plate temperature T, is used as the temperature control benchmark. The target furnace temperature of the ith heating zone is Ti. Ti=T*K1*K2*(1+bi*TV / 100); Where K1 is the steel grade correction coefficient, K2 is the width correction coefficient, and bi is the TV value adjustment coefficient of the i-th heating zone; When the steel strip to be annealed is a 400 series cold-rolled steel strip, the value of K1 is in the range of 1.0-1.012. When the steel strip to be annealed is a 300 series cold-rolled steel strip, the value of K1 is in the range of 1.002-1.016. In this embodiment, K1=1.01.

[0023] K2 = (W - 1000) / 10000 + 0.95; W is the strip width, expressed in mm. In this embodiment, K2 = (1250 - 1000) / 10000 + 0.95 = 0.925.

[0024] The value of bi is determined based on experience. For heating zones 1-8, bi1-b8 is 0.004-0.006; for heating zones 9-16, bi9-b16 is 0.0022-0.003; and for heating zones 17-18, bi17-b18 is 0.001-0.002.

[0025] For heating zones 1-8, Ti = T * K1 * K2 * (1 + bi * TV / 100) = 820 × 1.01 × 0.925 × (1 + 0.005 × 80 / 100) = 820 × 1.01 × 1.025 × 1.004 ≈ 852℃; Using the same method, we calculated that for heating zones 9-16, Ti≈850℃, and for heating zones 17-18, Ti≈848℃.

[0026] Step 4: Zoned control of burner gas flow. The furnace temperature of each zone is used as the basis for heating demand. The higher the furnace temperature, the greater the required heating load, and the more gas is allocated. The burner gas allocation ratio Si for the i-th heating zone is as follows: Si = Ti / ΣTi; The gas supply Qi to the burners in the i-th heating zone; Qi = Q_total * Si; Where ΣTi is the sum of the target furnace temperatures of all heating zones, Q_total is the total gas supply of the entire furnace, and the target temperature of the steel strip in the Mth heating zone is equal to the target furnace temperature of the Mth heating zone; the gas supply of each zone burner is equally distributed according to the number of burners in each zone.

[0027] Gas flow rate of a single burner in zones 1-16 = (gas supply in each zone 1-16) / 14; Gas flow rate of a single burner in zones 17-18 = (gas supply in each zone 1-18) / 16.

[0028] Based on the deviation between the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone and Ti, the gas flow rate of the single burner on the upper and lower sides of the furnace body in the i-th heating zone is adjusted in real time; where Q is the total gas supply of the entire furnace.

[0029] In this embodiment, Q = 2500 Nm 3 / h (the air flow rate of the annealing furnace when producing this type of steel). 1-8 Heating zones, single burner flow rate 10 Nm 3 / h, the flow rate of a single burner in heating zone 9-16 is 9.9 Nm³ / h. 3 / h, the flow rate of a single burner in heating zone 17-18 is 8.6 Nm³ / h. 3 / h, the flow rate deviation between the upper and lower burners is controlled within 3%.

[0030] Example 2: This example uses 300 series cold-rolled steel strip as the steel strip to be annealed.

[0031] The energy-saving control method for gas in a cold rolling continuous heating annealing furnace includes the following steps: Step 1: Basic Parameter Acquisition. Real-time acquisition of core process parameters for the steel strip to be annealed, including steel type G, strip thickness H, strip width W, and strip running speed V. The target annealing plate temperature T of the steel strip to be annealed is determined before annealing, in °C. Steel type G is classified according to different steel grades and assigned a number. The steel type G determines the steel grade of the steel strip to be annealed. For example, in this invention, G=1 is set for cold-rolled steel strip of 400 series steel, G=2 is set for cold-rolled steel strip of 300 series steel, strip thickness H=1.5mm, strip width W=1500mm, strip running speed V=60m / min, and target annealing plate temperature T=1080℃.

[0032] Step 2: Calculate the TV value, which is the product of the running speed and thickness of the steel strip to be annealed; TV = V * H = 60 * 1.5 = 90 m * mm / min; Where V is the running speed of the steel strip to be annealed, in m / min, and H is the thickness of the steel strip to be annealed, in mm.

[0033] Step 3: Calculate the target furnace temperature for each zone. The first heating zone to the Mth heating zone are arranged sequentially along the strip conveying direction. The target temperature of the strip in the Mth heating zone, i.e., the target annealing plate temperature T, is used as the temperature control benchmark. The target furnace temperature of the ith heating zone is Ti. Ti=T*K1*K2*(1+bi*TV / 100); Where K1 is the steel grade correction coefficient, K2 is the width correction coefficient, and bi is the TV value adjustment coefficient of the i-th heating zone.

[0034] When the steel strip to be annealed is a 400 series cold-rolled steel strip, the value of K1 is in the range of 1.0-1.012. When the steel strip to be annealed is a 300 series cold-rolled steel strip, the value of K1 is in the range of 1.002-1.016. In this embodiment, K1=1.014.

[0035] K2 = (W - 1000) / 10000 + 0.95; W is the strip width, expressed in mm. In this embodiment, K2 = (1500 - 1000) / 10000 + 0.95 = 0.975.

[0036] The value of bi is determined based on experience. For heating zones 1-8, bi1-b8 is 0.004-0.006; for heating zones 9-16, bi9-b16 is 0.0022-0.003; and for heating zones 17-18, bi17-b18 is 0.001-0.002.

[0037] For heating zones 1-8, Ti = T * K1 * K2 * (1 + bi * TV / 100) = 820 × 1.01 × 0.925 × (1 + 0.005 × 80 / 100) = 1080 × 1.014 × 0.975 × (1 + 0.0026 × 90 / 100) = 1080 × 1.014 × 0.975 × 1.0234 ≈ 982℃; Using the same method, we calculated that for heating zones 9-16, Ti≈1098℃, and for heating zones 17-18, Ti≈1070℃.

[0038] Step 4: Zoned control of burner gas flow. The furnace temperature of each zone is used as the basis for heating demand. The higher the furnace temperature, the greater the required heating load, and the more gas is allocated. The burner gas allocation ratio Si for the i-th heating zone is as follows: Si = Ti / ΣTi; The gas supply Qi to the burners in the i-th heating zone; Qi = Q_total * Si; Where ΣTi is the sum of the target furnace temperatures of all heating zones, Q_total is the total gas supply of the entire furnace, and the target temperature of the steel strip in the Mth heating zone is equal to the target furnace temperature of the Mth heating zone; the gas supply of each zone burner is equally distributed according to the number of burners in each zone.

[0039] Gas flow rate of a single burner in zones 1-16 = (gas supply in each zone 1-16) / 14; Gas flow rate of a single burner in zones 17-18 = (gas supply in each zone 1-18) / 16.

[0040] Based on the deviation between the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone and Ti, the gas flow rate of the single burner on the upper and lower sides of the furnace body in the i-th heating zone is adjusted in real time; where Q is the total gas supply of the entire furnace.

[0041] In this embodiment, Q = 3500 Nm 3 / h (the air flow rate of the annealing furnace when producing this type of steel).

[0042] The flow rate of a single burner in heating zones 1-8 is 104.6 Nm. 3 / h, 9-16 heating zone single burner flow rate 117Nm 3 / h, the flow rate of a single burner in heating zone 17-18 is 24.9 Nm³ / h. 3 / h, the flow rate deviation between the upper and lower burners is controlled within 3%.

Claims

1. A gas-saving control method for a cold-rolling continuous heating annealing furnace, comprising at least two series-connected horizontal continuous heating annealing furnaces, each heating annealing furnace including at least one heating zone, all heating annealing furnaces having a total of M heating zones, the i-th heating zone having Ai natural gas burners, where M is a natural number and i is a natural number less than or equal to M, the natural gas burners in each heating zone being evenly spaced on the upper and lower sides of the furnace body, characterized in that: The energy-saving control method for the gas in the cold rolling continuous heating annealing furnace includes the following steps: Step 1: Basic parameter acquisition. Real-time acquisition of core process parameters of the steel strip to be annealed, including steel type G, strip thickness H, strip width W, and strip running speed V. Determine the target annealing plate temperature T of the steel strip to be annealed before annealing, in °C. Step 2: Calculate the TV value, which is the product of the running speed and thickness of the steel strip to be annealed; TV = V * H; Where V is the running speed of the steel strip to be annealed, in m / min, and H is the thickness of the steel strip to be annealed, in mm; Step 3: Calculate the target furnace temperature for each zone. The first heating zone to the Mth heating zone are arranged sequentially along the strip conveying direction. The target temperature of the strip in the Mth heating zone, i.e., the target annealing plate temperature T, is used as the temperature control benchmark. The target furnace temperature of the ith heating zone is Ti. Ti=T*K1*K2*(1+bi*TV / 100); Where K1 is the steel grade correction coefficient, K2 is the width correction coefficient, and bi is the TV value adjustment coefficient of the i-th heating zone; Step 4: Zoned control of burner gas flow. The furnace temperature of each zone is used as the basis for heating demand. The higher the furnace temperature, the greater the required heating load, and the more gas is allocated. The burner gas allocation ratio Si for the i-th heating zone is as follows: Si = Ti / ΣTi; The gas supply Qi to the burners in the i-th heating zone; Qi = Q_total * Si; Where ΣTi is the sum of the target furnace temperatures of all heating zones, Q_total is the total gas supply of the entire furnace, and the target temperature of the steel strip in the Mth heating zone is equal to the target furnace temperature of the Mth heating zone; the gas supply of each zone burner is equally distributed according to the number of burners in each zone.

2. The method for energy-saving control of gas in a cold-rolling continuous heating annealing furnace according to claim 1, characterized in that: When the steel strip to be annealed is a 300 series cold-rolled steel strip, the target annealing temperature T is 1020-1130℃; when the steel strip to be annealed is a 400 series cold-rolled steel strip, the target annealing temperature T is 750-900℃.

3. The method for energy-saving control of gas in a continuous heating annealing furnace for cold rolling according to claim 1, characterized in that: Steel type G is classified according to the different steel grades of the steel strip to be annealed, and a number is assigned to steel type G. The steel grade of the steel strip to be annealed can be determined by steel type G.

4. The gas energy-saving control method for a cold-rolling continuous heating annealing furnace according to claim 1, characterized in that: When the steel strip to be annealed is 400 series cold-rolled steel strip, the value of K1 is 1.0-1.012; when the steel strip to be annealed is 300 series cold-rolled steel strip, the value of K1 is 1.002-1.

016.

5. The method for energy-saving control of gas in a cold-rolling continuous heating annealing furnace according to claim 1, characterized in that: K2 = (W - 1000) / 10000 + 0.95; W is the strip width, in mm.

6. The method for energy-saving control of gas in a cold-rolling continuous heating annealing furnace according to claim 1, characterized in that: Based on the deviation between the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone and Ti, the gas flow rate of the single burner on the upper and lower sides of the furnace body in the i-th heating zone is adjusted in real time. Specifically, the real-time temperature detection data of the upper and lower sides of the furnace body in the i-th heating zone is T0, and the gas flow rate of the single burner on the upper and lower sides of the furnace body in the i-th heating zone is adjusted to Tj. Tj = Ti + Ti * (T0 - Ti) / T0; The deviation, i.e. (T0-Ti) / T0, is -5% to 5%.