Process control systems

Description

Automation of a facility to switch off equipment when it is not needed.

Technical description

Automation of a manufacturing facility involves the design and construction of a process control system, requiring sensors, instruments, computers and the application of data processing. It is widely recognised that automation of manufacturing processes is important not only to improve product quality and workplace safety, but also to increase the efficiency of the process itself and contribute to energy efficiency. More information on process control systems can be found in the ENE BREF [ 132, COM 2009 ].

Many measures can be taken through process control systems, such as switching off equipment, such as compressors and lighting. Pumps and fans that circulate cold air, chilled water or an antifreeze solution generate heat, contributing most of the power they consume to the cooling load, so switching them off when not required saves energy. This is also true for lights in a coldstore or cooled room, as they contribute most of the power they consume to the cooling load.

The switching can be timed according to a fixed programme or schedule. Conditions can be monitored to detect high or low temperatures for example and switch off motors when they are not needed. The load of a motor can be sensed, so that the motor is switched off when idling.

Achieved environmental benefits

Reduced energy consumption.

Food, Drink and Milk Industries 83 Cross-media effects

See process control systems in the ENE BREF [ 132, COM 2009 ].

Technical considerations relevant to applicability

Widely applicable in the FDM sector.

Economics

See process control systems in the ENE BREF [ 132, COM 2009 ].

Driving force for implementation

Reduced energy costs.

Example plants

This technique is commonly reported in all FDM sectors [ 193, TWG 2015 ].

Reference literature

[ 39, Environment Agency of England and Wales 2001 ],[ 132, COM 2009 ],[ 193, TWG 2015 ]

2.3.2.1.4 Combined heat and power generation

Description

Use of a heat engine or power station to generate electricity and useful heat at the same time.

Technical description

Information on different cogeneration applications can be found in the ENE BREF [ 132, COM 2009 ].

Achieved environmental benefits

Reduced energy consumption and emissions to air, e.g. NOX, CO2 and SO2.

Environmental performance and operational data

The energy efficiency of CHP can be as high as 90 %. This optimises the use of fossil fuels and reduces the production of CO2. New CHP installations save at least 10 % of the fuel otherwise

used in the separate production of heat and electricity. Furthermore, gas-fired CHP schemes can eliminate SO2 emissions and NOX can be controlled to meet environmental legislation. Modern

CHP equipment is likely to require less effort to operate and maintain than many older boiler systems, as it is equipped with automatic control and monitoring systems.

It is reported that most of the energy required in sugar manufacturing is obtained by burning gas, heavy fuel oil or coal in a boiler house, which converts it, by means of CHP equipment, into steam and electricity. In this sector, the overall fuel utilisation factor of CHP exceeds 70 % and is typically above 80 %. This fuel conversion efficiency greatly exceeds that of any design of commercial power stations whose steam is not used further, including even the latest generation of combined cycle gas turbines, which are around 55 % efficient. Excess electricity produced may be sold to other users [ 192, COM 2006 ].

Cross-media effects

See cogeneration in the ENE BREF [ 132, COM 2009 ].

Technical considerations relevant to applicability

Widely applicable.The applicability of CHP very much depends on several technical aspects. Although CHP is a well-established and technically mature technique, it is vital that the right design decisions are made. The main factors to consider are the consumption pattern of electricity and heat in the installation and the ratio between electricity and heat consumption.

Additional important factors are whether the installation is running continuously and whether large variations in processes occur. A simple rule of thumb is that the site needs to have a simultaneous demand for heat and electricity for at least 4 000 hours a year.

Economics

A decision on whether to implement CHP based on investigation of the economic aspects will take account of the price of gas and electricity. A balance of relatively expensive gas or other fuels and cheap electricity mitigates against the selection of CHP. For example, if electricity prices fall or gas prices rise, the financial return from CHP will decrease. This is possible in a free energy market. One option, which is sometimes applied, is to design the CHP installation on the basis of heat consumption with excess electricity being sold to the public grid. Whether this is an attractive option very much depends on the price obtained for the excess electricity that is sold.

With regard to financing of the CHP installation, the tendency is for companies to not finance it themselves. Sometimes joint ventures with energy suppliers are formed and sometimes third parties completely finance the CHP installation. A contract for delivery of electricity and heat by the CHP installation normally runs for 10 to 15 years.

In the UK, it has been found that CHP can now reduce the total energy bills of an installation by 20 %. In the example brewery, the savings in energy costs were 16.2 %.

Example plants

Applied in sugar manufacturing installations, dairies, breweries and distilleries.

Driving force for implementation

The introduction of measures and procedures to promote cogeneration installations is supported by Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency.

Reference literature

[ 53, COM 2002 ], [ 132, COM 2009 ], [ 192, COM 2006 ]