In the steel rolling workshop, electricity consumption is the second-largest cost after raw materials. At every meeting, the boss would slam his fist on the table and ask, "Why did we exceed the target again?"

 

The first reaction of many workshop directors was: replace the variable frequency motors, implement waste heat recovery, and urge the workers to turn off the lights promptly.

 

In fact, these are just "surface efforts". The high electricity consumption of the rolling line often stems from the "rhythm" and "idle running". Today, let's talk about how to truly reduce the electricity consumption of the rolling line through optimizing the process rhythm and controlling the standby of equipment.

 

1. Process Rhythm Optimization: Reject "Using a Large Horse for a Small Cart"

 

Many operators have a habit: as long as the rolling machine is running, they want to push the speed to the maximum, thinking that this will lead to higher output and efficiency. However, an unreasonable rhythm is the biggest waste of electricity.

 

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1. Avoid "excessive gap" duration

 

From the heating furnace to entering the rolling mill, there is a period of idle time. If the rhythm is not properly arranged, the rolling mill will idle and roll the steel at high speed, and the electrical energy used during this period will be wasted.

 

Energy-saving measures:

 

Precisely match the rolling rhythm: Based on the steel output speed from the heating furnace, calculate the speed settings for each rolling mill in reverse. Make sure that the steel "just finishes the previous roll and the next roll just bites in", reducing the waiting time for the rolling mill to idle.

 

Optimize pass distribution: Avoid excessive reduction in a single pass, which can cause the motor to overheat. Reasonably distribute the load for each pass, so that each motor operates in the efficient zone instead of having a few motors "holding back" to do heavy work.

 

2. Eliminate "over-rolling"

 

As we discussed earlier, over-rolling is the root cause of wavy shapes. From an electrical consumption perspective, over-rolling is even more of an energy guzzler.

 

The greater the rolling force applied, the greater the torque required from the motor, and the current surges instantly. To correct the shape problems caused by over-rolling, additional straightening or leveling processes are needed, resulting in additional power consumption.

 

Energy-saving measures:

 

Scientifically set the roll gap: Based on the cross-section of the incoming material, accurately calculate the reduction amount for each pass. Replace "large reduction, strong impact" with "small deformation, multiple passes" to allow the motor to operate smoothly, with smaller current fluctuations, and naturally lower power consumption.

 

II. Equipment standby management: Seal off "idle oil leakage"

 

In many workshops, the rolling mills keep running 24 hours a day without changing rolls. But do you know? The idle running energy consumption during standby can account for more than 15% of the total power consumption.

 

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1. Implement "Just-in-Time" roller replacement

 

The traditional planned maintenance was "replace when the time comes", regardless of whether the rollers were still usable. As a result: good rollers were replaced prematurely, and bad rollers were not repaired in time, causing frequent start-stop of the rolling machine, and each start-up was accompanied by a huge current shock.

 

Energy-saving measures:

 

Condition monitoring roller replacement: Through an online monitoring system, real-time tracking of the bearing temperature and vibration of the rollers. Only when the data is abnormal or reaches the economic wear limit is the roller replaced, reducing unnecessary downtime and power consumption during restarts.

 

Centralized roller replacement, reducing start-stop frequency: Combine multiple tasks that require shutdown (such as roller replacement, cleaning of oxide scale, inspection of guides) into the same maintenance window to avoid repeated start-ups.

 

2. Strictly control the "long-illumination" of auxiliary equipment

 

The hydraulic stations, lubrication stations, and cooling water systems on the rolling line are often "electricity consumption black holes". Many workshops, for the sake of "insurance", keep these systems running at full power 24 hours a day, even if the rolling line has been stopped for half an hour.

 

Energy-saving measures:

 

Interlock control: Achieve the linkage between the main rolling machine and the auxiliary systems. When the main motor stops, it automatically shuts down the hydraulic pump and lubrication pump after a 5-minute delay; 30 seconds before the main motor starts, the auxiliary system is preheated and started in advance.

 

Frequency conversion transformation: Implement frequency conversion control for cooling water circulation pumps and hydraulic pumps, automatically adjusting the flow and pressure according to the rolling rhythm to avoid waste of "large flow, small demand".

 

 

 

【Conclusion】

 

Reducing electricity consumption is not achieved by saving it; it is achieved by managing it.

 

Optimize the process rhythm, make every watt of electricity used on the "bite into the steel billet" blade; control standby idling, plug every "long-illumination" and "idle pump" loophole. If these two aspects are done well, your rolling line's electricity consumption can be reduced by at least 10%, and the electricity saved in a year is enough to buy several sets of good bearings! 

 

Have you encountered any "electricity consumption black holes" on-site? Or do you have any exclusive energy-saving tips? Welcome to leave a comment to share, let's exchange and discuss together, and bring down the steel rolling cost!