Combined heat and power. your key to energy savings

Transcription

1 Combined heat and power your key to energy savings 1

2 Combined heat and power... your key to energy savings What is combined heat and power? Combined heat and power (CHP), or co-generation as it is sometimes known, is simply the simultaneous generation of heat and electricity. The generation of electricity produces a large amount of heat which, using conventional methods, is often wasted. CHP recovers this waste heat and converts it into a useful form - usually steam or hot water, which can then be used for a wide variety of process, heating, and sometimes cooling applications. CHP versus conventional electricity generation CHP everywhere CHP is not a new idea. Its vast benefits have been reaped by several areas of industry and commerce for many years. Losses % Conventional generation Electricity % Commercial buildings Industrial sites Public buildings Food, pharmaceuticals and paper are just a few examples of industrial applications for CHP, while the concept is equally suited to leisure complexes, public buildings and even royal palaces. Wherever there is a significant demand for electricity and thermal energy all year round, CHP is an option worth considering. The thermal energy does not have to be used for heating - it may be more appropriate to use it for a cooling application. Heat % Electricity % Losses % CHP generation By recovering the heat produced in the generation of electricity, the fuel conversion efficiency is increased substantially. Typically, conventional electricity generation plants operate at an efficiency of around 36 %. CHP plant will normally operate at an efficiency level well in excess of 75 %, sometimes even 90 %. When CHP is implemented as a retro-fit scheme, tremendous fuel and electricity cost savings can be achieved as a result of the increased efficiency levels. Photograph showing typical absorption chiller utilising steam. 2

3 CHP components Prime mover Fuel Electricity Generator Air Exhaust Heat recovery steam generator Steam to process Optional supplementary firing Simple cycle CHP Prime mover Fuel Generator Steam to process Electricity Air Exhaust Steam turbine Generator Heat recovery steam generator Optional supplementary firing Steam to process Combined cycle CHP At the heart of any CHP system is the prime mover. This plant can range from a small diesel engine to a large scale gas turbine. The 'engine' produces electricity by turning a generator. The engine also produces heat energy by virtue of its operation. The high temperature exhaust from the engine is commonly fed into a waste heat boiler where either steam or hot water is generated. If the heat is converted into steam, the waste heat boiler is termed a Heat Recovery Steam Generator (HRSG). The product of the HRSG can then be treated as conventional plant steam. This is known as Simple Cycle CHP. For larger plants it may prove economical to maximise the output of electricity by including a steam turbine to turn another generator. The pass-out from this turbine provides low pressure plant steam. This arrangement is called Combined Cycle CHP. CHP for the environment The environment benefits from the high efficiency of CHP plant. Carbon dioxide emissions are reduced in compliance with targets to stem the effect of global warming and fuel reserves are conserved as a result of their more efficient consumption. User benefits Reduced site energy bills. Increased control over utility supply. Flexible, making it suitable for many types of site. Environmental benefit from more efficient fuel consumption. 3

4 Spirax Sarco CHP and steam system specification Feedwater storage, Boiler level controls Boiler blowdown controls conditioning and supply and heat recovery 1 Feedtanks 6 Water level alarms 9 Auto TDS control systems 2 Deaerator heads 7 Modulating feedwater valves 10 Timed blowdown valves 3 Steam injection systems and controls 11 Blowdown vessels 4 Modulating feedwater valve controls 8 Feedpump check valves 12 Cooling water systems 5 Recirculating systems 13 Residual blowdown heat exchangers 14 Sample coolers 15 Vent heads Gas turbine 13 Exhaust Generator General layout only. Some detail has been omitted for clarity. Your local Spirax Sarco Engineer will be pleased to advise. 4

5 Steam start-up Process and pipeline Condensate recovery and equipment monitoring 16 Steam main start-up systems 20 Steam traps Mechanical and electric pumps* 17 Steam separators 21 Strainers 26 Condensate contamination detection 22 Air vents Metering Vacuum breakers* Heat recovery 18 Steam, fluid and gas meters Sight glasses* Plate heat exchangers* 23 Check valves Flash vessels* Pressure and temperature controls 24 Trap monitoring Pressure and temperature controls* 25 Isolation valves Humidification High temperature cut-off valve* Steam injection humidifiers* 19 Safety valves *Not shown in schematic

6 Spirax Sarco in combined heat and power plant For more than 85 years Spirax Sarco has been the leader in improving plant efficiency, providing knowledge, high quality products and packaged systems to fluid plant in all branches of industry, including CHP. We understand the specific needs of CHP, and that each CHP application has its own special requirements. Whilst our key speciality lies with steam systems we also provide technical support for other fluid systems, including hot water. Steam distribution Heat recovery from HRSG Steam control and management Condensate management The complete system From factories to hospitals it is essential that the steam from the recovery boiler or steam turbine is conditioned to ensure optimum operation and maximum efficiency. To achieve this it is necessary to consider the design and operation of the complete steam and condensate system. The type of connected plant, the local environment and the different processes being served must all be taken into account. Consideration should also be given to future expansion and plans to upgrade existing production plant. 6

7 Steam generation Level control High integrity self-monitoring level controls enable the boiler to operate on a completely automated basis therefore ensuring round-the-clock optimised operation. TDS control Automatic TDS controls ensure that ideal water conditions are maintained within the boiler, thus creating steam of the highest quality for process or heating requirements. Steam distribution Steam pipeline equipment Control equipment including steam traps, separators, strainers and bellows sealed isolation valves all make for an energy efficient steam system whose operation and maintenance is very simple. Automatic performance monitoring Steam traps can be automatically monitored on a continuous basis to ensure that they are performing at their optimum. Such automated monitoring systems can be linked to existing energy management systems. Their installation reduces maintenance downtime to an absolute minimum. Temperature, pressure and flow control Control equipment Electronic and pneumatic control equipment provides close control of temperature, pressure or flow. This equipment is ideally suited to the efficient operation of de-superheaters and plate heat exchanger packages. Flowmetering equipment Flowmetering equipment suitable for saturated steam, superheated steam, liquids and gases enables monitoring of the chosen heating medium or fuel used in the CHP application. Condensate management Condensate removal It is essential that condensate is drained from the steam system quickly and effectively by use of an appropriate steam trap. Condensate contamination A simple automatic system can be installed which will allow the quality of condensate to be assessed prior to return to the feedtank. Any contamination will be detected and the condensate discharged to drain. Condensate recovery Condensate is a valuable asset, and should be returned to the boiler for reuse where possible. Under certain circumstances, electrical or mechanical pumps may be required to help in the return of this condensate. 7

8 Spirax Sarco provides knowledge, service and products worldwide for the control and efficient use of steam and other industrial fluids associated with CHP plant. As your business partner, Spirax Sarco will provide you with:- Worldwide support from a team of dedicated employees. Local access to Spirax Sarco's expertise and products through 35 group companies in 30 countries. Valuable information, advice and interchange of ideas from customer training courses held in any of our 32 training centres worldwide. A comprehensive range of the highest quality products. Spirax Sarco locations Europe Austria Vienna Belgium Zwijnaarde Czech Republic Prague Denmark Copenhagen Finland Helsinki France Trappes Germany Konstanz Hungary Budapest Ireland Dublin Italy Milan Netherlands Maarn Norway Oslo Poland Warsaw Portugal Lisbon Russia St. Petersburg Spain Barcelona Sweden Stockholm Switzerland Zurich - Zollikon United Kingdom Cheltenham Australasia Australia Sydney New Zealand Auckland Americas Argentina Buenos Aires Brazil São Paulo Canada Toronto Mexico Monterrey USA Allentown Africa Kenya Nairobi Nigeria Lagos South Africa Johannesburg Asia & Middle East China Shanghai Hong Kong lndia Poona Indonesia Jakarta Japan Tokyo Korea Seoul Lebanon Beirut Malaysia Kuala Lumpur Pakistan Karachi Philippines Manila Singapore Taiwan Taipei Thailand Bangkok A further 46 agencies operate throughout the world. If you have difficulty finding a local contact please fax us at the number shown below. CHP Spirax-Sarco Limited, Charlton House, Cheltenham, Gloucestershire, GL53 8ER UK. Tel: +44 (0) Fax: +44 (0) enq@spiraxuk.attmail.com Internet: Copyright 1996 Spirax Sarco is a registered trademark of Spirax-Sarco Limited 8 SB-GCM-14 CM Issue 1