Managing the energy crisis

 

Energy prices continue to rise, driven by increasing demand, political events in oil producing countries and the move away from cheaper fossil fuels. This inevitably puts pressure on manufacturers to cut costs, so there has never been a better time to consider ways of reducing your energy consumption. 

As energy costs rise, manufacturers are struggling to adjust their pricing, a difficult task for those with fixed price contracts or who have energy intensive processes. Implementing plans to reduce energy costs will allow organisations to reduce the impact of sudden changes in energy prices. 

Energy plan

The first stage in getting to grips with energy costs is to create and implement an energy reduction plan. By doing this, organisations not only prepare themselves for fluctuations in energy prices, they reduce their bottom-line costs and improve their overall stability. 

Although many larger organisations are implementing energy reduction strategies, it is time that smaller organisations followed suit. The best place to start is to establish the carbon dioxide (CO2) footprint of your business, looking at all activities that can generate CO2, in both the business itself and its supply chain. 

Although not a simple task, it makes it possible to set meaningful targets and look at the technologies available to meet these targets.

 

Choose equipment 

Although there is a range of energy saving technologies on the market, none offer the kind of saving achievable with a variable-speed drive (VSD). VSDs offer manufacturers the ability to reduce energy consumption by up to 50% and can be used on virtually any motor-driven application, particularly variable-torque loads such as pumps, fans and compressors. They work by adjusting the speed of the motor to exactly meet the needs of the application at any given time. 

With VSDs capable of substantially reducing energy use, we might expect manufacturers to be clamouring to use them. Unfortunately, of the 11 million motors running in the UK, only 10% have VSDs. While many motors are fixed speed or drive constant-torque loads, there are many more variable-torque loads that can benefit from VSDs.

Many manufacturers are still unaware of the savings they can achieve with VSDs, preferring such methods as changing supplier or switching off unused lights. 

Saving £250,000 a year

One company that is seeing success with VSDs is Tata Steel in Rotherham. A project was carried out on the fume extraction plant at the Aldwarke bloom caster complex. ABB systems integrator Drives and Automation replaced existing fixed speed direct-on-line motors in the plant with low voltage motors, controlled by four ABB low harmonic variable-speed drives, two at 400kW and two at 570kW. The turnkey project included the supply of transformers, a Form 4 distribution panel, inverter cubicles, electrical and mechanical installation, plant room ventilation and integration of a PLC /SCADA with the existing plant control system.

The extraction plant is used to remove fumes produced by the two casting machines and two ladle arc furnaces within the Aldwarke Bloom Caster complex. The fumes are then passed through a filter system where the particles are removed and discarded. 

The original installation used four 3.3kV motors: two 650kW and two 410kW. The two large motors were used as the primary extraction motors, with the smaller motors used to provide additional extraction as required. 

Due to motor limitations the fans were restricted to four starts per hour, as additional starts would risk damaging the windings. This meant the motors would be forced to run-on for 15 minutes even if demand for extraction was reduced, wasting a lot of energy.

Several of the motors also suffered multiple failures. The company was spending around £3000 a year in motor repairs, with downtime becoming a major problem. Each failure took up to six weeks to rectify, during which Tata had to cut back production to ensure it was within environmental limits for fume and dust levels. They could incur fines for not meeting the required environmental standards and there was a risk that production workers in the area could suffer from dust inhalation. Fume extraction is a vital part of the process and without it Tata simply cannot work to full capacity.

Another issue was that the motors were 3.3 kV, so any maintenance on them required special permits to work. 

The company aimed to save in the region of £240,000 a year on energy costs for the extraction plant by more closely matching the speed of the motors to the dust extraction demand. It also anticipated that using VSDs would cut maintenance by reducing wear and tear on the motors and strain on the duct work, as well as making for a less noisy environment. 

Complete package

Several companies were invited to make presentations on energy saving products that could be used to improve the fume extraction system and the solution offered by Drives and Automation was selected as it offered a turnkey package at a competitive price. This package included hardware supply, a ventilation system, electrical and mechanical installation works, commissioning and integration with the existing plant control system. One advantage came with the ABB inverter cabinet drives utilised that came ready assembled and factory tested, saving many hours of panel building time.

Drives and Automation completed the job over the shutdown period with no effect on production in the New Year.

The major benefit for Tata Steel was the energy saving produced by the drives applications: The company is well on target to achieve the projected savings of £250,000 with a payback time of three years. 

Another benefit for Tata is the ability the drives give to ‘fine tune’ the extraction capacity to match demand, due to the infinite variable extraction control they offer. Tata is continually looking at the plant’s request for extraction and reducing the fan motor speeds still further, whilst still achieving good fume extraction.

Free appraisal 

With all the uncertainty around energy prices, now is definitely the time to consider VSDs as part of any plant upgrade. The equipment is simple to fit into new applications and can just as easily be retrofitted into an existing application. A free, no obligation energy appraisal is available from ABB providing detailed evidence on how much energy you could save.