Production method of submarine supercritical carbon dioxide conveying pipeline steel

Abstract

The invention discloses a production method of submarine supercritical carbon dioxide conveying pipeline steel. The steel comprises the following chemical components in percentage by mass: 0.03%-0.05% of C, 0.10%-0.30% of Si, 0.75%-0.95% of Mn, less than or equal to 0.008% of P, less than or equal to 0.0015% of S, 0.020%-0.050% of Alt, 0.040%-0.050% of Nb, 0.20%-0.50% of Cr, 0.010%-0.020% of Ti, 0.10%-0.15% of Mo, 0.001%-0.006% of Ce and the balance of Fe and inevitable impurities. The pipeline steel which is low in internal stress, good in plate shape, high in strength, good in low-temperature toughness and good in corrosion resistance can be obtained through combination of low-carbon and Ce alloying component design and a reasonable TMCP cooling process, and the impact at the temperature of-60 DEG C is larger than or equal to 100 J; the 15.6 MPa supercritical carbon dioxide corrosion resistance of the steel plate is more than 1.2 times that of the same-grade common pipeline steel, and the seawater corrosion resistance of the steel plate is more than 1.3 times that of the same-grade common pipeline steel.

Description

Technical Field

[0001] The invention belongs to the technical field of special-purpose pipeline steel production, and relates to a method for producing pipeline steel for supercritical carbon dioxide transportation on the seabed. Background Art

[0002] Carbon capture and storage (CCS) technology refers to the process of separating CO2 from industrial or related energy sources, transporting it to a storage site, and isolating it from the atmosphere for a long time. CCS is an important way to deeply reduce CO2 emissions, but the capture and storage potential, implementation difficulty, and socio-economic benefits of different methods vary greatly. With the development of CCS technology and the deepening of understanding, China first proposed CCUS technology at the Beijing Xiangshan Conference in 2006 and introduced CO2 resource utilization technology. CCUS technology purifies the captured CO2 and puts it into a new production process for recycling, turning CO2 into a resource, which can not only achieve carbon emission reduction, but also generate economic benefits, so it is more realistic and operational. After years of development, CCUS technology has been accepted and used worldwide. The phase state of CO2 transportation can be gaseous, supercritical, liquid or solid according to specific conditions, which is more complex than the phase state of natural gas transportation. When the CO2 pressure is higher than the critical pressure of 7.38MPa and the temperature is higher than the critical temperature of 31.1℃, it is in a supercritical state. Supercritical CO2 has a density close to that of liquid and a viscosity close to that of gas, and has the characteristics of high density and low viscosity. When the entire pipeline transportation process is in a supercritical state, transportation is most efficient. Compared with ship transportation, laying pipelines on the seabed has huge advantages.

[0003] Pipes are the basis for ensuring safe transportation of pipelines. In the total investment of pipeline construction, the cost of pipes is relatively high. Affected by factors such as corrosion and third-party damage, the pipe wall may become thinner or fail, and various accidents may occur in serious cases. China's existing CO2 pipelines have the characteristics of gaseous transportation, small pipe diameter, and short transportation distance. There is no precedent for the construction and operation of large-diameter supercritical carbon dioxide pipelines. Therefore, in view of the current status of engineering construction for submarine supercritical carbon dioxide pipeline transportation, it is urgent to develop special steel plates and supporting technologies for submarine supercritical carbon dioxide pipeline transportation. Summary of the invention

[0004] The present invention aims to provide a method for producing submarine supercritical carbon dioxide transportation pipeline steel, especially X65MC, to solve the key technology of steel plates for supercritical carbon dioxide transportation. In addition to the mechanical properties of conventional pipeline steels, the steel plates also have good low-temperature resistance, low-temperature crack arrest performance and high-pressure carbon dioxide and seawater corrosion resistance: -60°C impact ≥100J; the steel plate's 15.6MPa supercritical carbon dioxide corrosion resistance is more than 1.2 times that of ordinary pipeline steels of the same level, and its seawater corrosion resistance is more than 1.3 times that of ordinary pipeline steels of the same level.

[0005] The technical solution of the present invention: A method for producing submarine supercritical carbon dioxide transmission pipeline steel, wherein the chemical composition of the steel is C=0.03%~0.05%, Si=0.10%~0.30%, Mn=0.75%~0.95%, P≤0.008%, S≤0.0015%, Alt=0.020%~0.050%, Nb=0.040%~0.050%, Cr=0.20%~0.50%, Ti=0.010%~0.020%, Mo=0.10%~0.15%, Ce=0.001%~0.006%, and the balance is Fe and unavoidable impurities, wherein Cr+60(Ce-0.001%)=0.50%; the key process steps include: (1) Steelmaking: The converter adopts double slag method for dephosphorization, and the steel tapping is controlled at P≤0.006%; the refining adopts LF+VD combination, and the temperature is quickly raised to make slag after entering LF, the LF station time is ≥80min, the calcium feeding line is ≥150m, and the outlet S is ≤0.0015%; the VD vacuum maintenance time is ≥12min, and the soft blowing is ≥15min; (2) Heating: heating temperature 1200~1220℃, heating time 220~280min; (3) Rolling: The first stage rolling end temperature is 950~1050℃, the second stage rolling end temperature is 820~900℃, rolling is 7~9 times, and the finishing cumulative reduction is ≥60%; (4) Cooling: The starting cooling temperature is 810~860℃, the cooling rate is 8~20℃ / s, and the final cooling temperature is 480~540℃. The continuous water convexity method is adopted to make the edge temperature more uniform, in which the upper and lower water ratio is between 1.5~1.8, and the edge cavity water ratio is between 0.4~0.8.

[0006] The present invention has the following advantages: the composition design adopts low carbon + Ce alloying and ultra-low phosphorus and sulfur composition design to ensure that the central segregation is controllable; the TMCP process is adopted, the production cost is low, the delivery cycle is short, and both the cost and delivery have competitive advantages; the continuous water convexity method is adopted during cooling control to make the edge temperature more uniform. The seabed supercritical carbon dioxide transmission pipeline steel requires welding and corrosion resistance. The Cr element can improve the corrosion resistance, but the increase in Cr content will increase the difficulty of welding and increase the cost. In order to save costs and obtain good corrosion resistance and weldability at the same time, Ce alloying is used to replace part of the Cr element, but too high Ce elements will increase the difficulty of smelting, so Cr+60(Ce-0.001%)=0.50% is required. The seabed supercritical carbon dioxide transmission pipeline steel plate produced according to the invention has a banded structure of 0.5 level and below, few inclusions, and the organization is ferrite+acicular ferrite+a small amount of pearlite. The strength and toughness are well matched, and the steel plate performance is uniform and stable. In addition to meeting the mechanical properties of conventional pipelines, the -60℃ impact is ≥100J, the steel plate's corrosion resistance to 15.6MPa supercritical carbon dioxide is more than 1.2 times that of ordinary pipeline steel of the same level, and its seawater corrosion resistance is more than 1.3 times that of ordinary pipeline steel of the same level. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is the metallographic structure diagram of the steel plate. DETAILED DESCRIPTION

[0008] The present invention is further described below with reference to the embodiments.

[0009] Example 1: Production of 16 mm pipeline steel X65MC A method for producing X65MC steel for submarine supercritical carbon dioxide transmission pipeline, wherein the chemical composition of the steel is as follows: C=0.03%, Si=0.17%, Mn=0.81%, P=0.006%, S=0.0008%, Alt=0.030%, Nb=0.040%, Ti=0.015%, Cr=0.20%, Mo=0.10%, Ce=0.006%, and the remainder is Fe and unavoidable impurities. The properties of the steel are shown in Table 1. The process steps are as follows: (1) Steelmaking: The converter adopts the double slag method, and the steel tapping P=0.006%; the refining adopts the LF+VD combination, and the temperature is quickly raised to make slag after entering the LF. The LF station time is 95 minutes, the calcium feeding line is 180 meters, and the station S=0.0011%; the VD vacuum maintenance time is 17 minutes, and the soft blowing is 19 minutes; (2) Heating: heating temperature 1210°C, heating time 250 min; (3) Rolling: The first stage rolling end temperature is 965°C, the second stage rolling end temperature is 840°C, 7 rolling passes, and the finishing cumulative reduction is 75%; (4) Cooling: The starting cooling temperature is 835°C, the cooling rate is 12°C / s, and the final cooling temperature is 520°C. The continuous water convexity method is used during cooling to make the edge temperature more uniform, with the upper and lower water ratio being 1.6 and the edge cavity water ratio being 0.6.

[0010] Example 2: Production of 16 mm pipeline steel X65MC A method for producing X65MC steel for supercritical carbon dioxide transmission pipeline for submarine, wherein the chemical composition of the steel is as follows: C=0.03%, Si=0.17%, Mn=0.81%, P=0.006%, S=0.0008%, Alt=0.030%, Nb=0.040%, Ti=0.015%, Cr=0.50%, Mo=0.10%, Ce=0.001%, and the remainder is Fe and unavoidable impurities. The properties of the steel are shown in Table 1. The process steps are as follows: (1) Steelmaking: The converter adopts the double slag method, and the steel tapping P=0.006%; the refining adopts the LF+VD combination, and the temperature is quickly raised to make slag after entering the LF. The LF station time is 95 minutes, the calcium feeding line is 180 meters, and the station S=0.0011%; the VD vacuum maintenance time is 17 minutes, and the soft blowing is 19 minutes; (2) Heating: heating temperature 1210°C, heating time 250 min; (3) Rolling: The first stage rolling end temperature is 965°C, the second stage rolling end temperature is 840°C, 7 rolling passes, and the finishing cumulative reduction is 75%; (4) Cooling: The starting cooling temperature is 835°C, the cooling rate is 12°C / s, and the final cooling temperature is 520°C. The continuous water convexity method is used during cooling to make the edge temperature more uniform, with the upper and lower water ratio being 1.6 and the edge cavity water ratio being 0.6.

[0011] Comparative example: Production of 16 mm ordinary pipeline steel X65M The common production method of 16 mm pipeline steel has the following chemical composition percentages: C = 0.03%, Si = 0.17%, Mn = 0.81%, P = 0.006%, S = 0.0008%, Alt = 0.030%, Nb = 0.040%, Ti = 0.015%, Cr = 0.40%, Mo = 0.10%, and the remainder is Fe and unavoidable impurities. The properties of the steel are shown in Table 1. The process steps are as follows: (1) Steelmaking: The converter adopts the double slag method, and the steel tapping P=0.006%; the refining adopts the LF+VD combination, and the temperature is quickly raised to make slag after entering the LF. The LF station time is 95 minutes, the calcium feeding line is 180 meters, and the station S=0.0011%; the VD vacuum maintenance time is 17 minutes, and the soft blowing is 19 minutes; (2) Heating: heating temperature 1210°C, heating time 250 min; (3) Rolling: The first stage rolling end temperature is 965°C, the second stage rolling end temperature is 840°C, 7 rolling passes, and the finishing cumulative reduction is 75%; (4) Cooling: starting cooling temperature 835°C, cooling rate 12°C / s, final cooling temperature 520°C.

[0012] Table 1 Performance test results of X65MC and ordinary X65M steel produced in the embodiment .

Claims

1. A method for producing steel for submarine supercritical carbon dioxide transmission pipeline, characterized in that: The chemical composition of steel is as follows: C = 0.03% ~ 0.05%, Si = 0.10% ~ 0.30%, Mn = 0.75% ~ 0.95%, P ≤ 0.008%, S ≤ 0.0015%, Alt = 0.020% ~ 0.050%, Nb = 0.040% ~ 0.050%, Cr = 0.20% ~ 0.50%, Ti = 0.010% ~ 0.020%, Mo = 0.10% ~ 0.15%, Ce = 0.001% ~ 0.006%, the remainder is Fe and unavoidable impurities, of which Cr + 60 (Ce-0.001%) = 0.50%; The key process steps include: (1) Steelmaking: The converter adopts double slag method for dephosphorization, and the steel tapping is controlled at P≤0.006%; the refining adopts LF+VD combination, and the temperature is quickly raised to make slag after entering LF, the LF station time is ≥80min, the calcium feeding line is ≥150m, and the outlet S is ≤0.0015%; the VD vacuum maintenance time is ≥12min, and the soft blowing is ≥15min; (2) Heating: heating temperature 1200~1220℃, heating time 220~280min; (3) Rolling: The first stage rolling end temperature is 950~1050℃, the second stage rolling end temperature is 820~900℃, rolling is 7~9 times, and the finishing cumulative reduction is ≥60%; (4) Cooling: The starting cooling temperature is 810~860℃, the cooling rate is 8~20℃ / s, and the final cooling temperature is 480~540℃. The continuous water convexity method is used during cooling to make the edge temperature more uniform, where the upper and lower water ratio is between 1.5~1.8, and the edge cavity water ratio is between 0.4~0.

8.

2. The method for producing submarine supercritical carbon dioxide pipeline steel according to claim 1, characterized in that: The chemical composition of the steel in percentage by mass is C=0.03%, Si=0.17%, Mn=0.81%, P=0.006%, S=0.0008%, Alt=0.030%, Nb=0.040%, Ti=0.015%, Cr=0.20%, Mo=0.10%, Ce=0.006%, and the balance is Fe and unavoidable impurities.

3. The method for producing X65MC steel for submarine supercritical carbon dioxide transmission pipeline according to claim 1, characterized in that: The chemical composition of the steel in mass percentage is C=0.03%, Si=0.17%, Mn=0.81%, P=0.006%, S=0.0008%, Alt=0.030%, Nb=0.040%, Ti=0.015%, Cr=0.40%, Mo=0.10%, Ce=0.001%, and the balance is Fe and unavoidable impurities.

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