Water Heat By Steam
There are many methods of heating water. Hot water produced through Solar and Heat Pump system is getting very popular all over GCC. Though these sources helps a big way of energy saving in a project, if the project has a full fledged laundry where fuel fired steam boiler to be used then heating water with steam isthe only economical way .
For example, if a 250 room hotel has a laundry which has a steam requirement of 2000 kg/hr, where it is required to install one duty and one standby boiler to meet the steam requirement. Hot water required for a 250 room hotel works out to a demand of 13,125 litres per hr. When 50% demand is kept as storage and 50% in recovery. Steam required to heat the water works out to 488 kg/hr. If a economizer is installed in flue gas chimney of a fuel fired boiler 80% of the energy required for heating hot water can be gained through economizer, which make the system more energy efficient and economical.
In this case if the steam boiler capacity is increased from 2000 kg/hr boiler to 2500kg/hr, cost difference between a 2000 kg/hr and 2500 kg/hr is a increase of 8-10% only, which is much lesser than Solar System or heat pump system. Further extra space is not required to keep Solar and heat pump equipment.
In the same project if we opt to use Solar or heat pump, then additional back up source to be provided either with steam or high temp hot water or with electric, which is making the entire system expensive of operation. If it’s with electric then additional expenditure for electrical wiring, transformer costs etc needs to be considered. Further if a economizer is installed in flue gas chimney of a boiler this can also produce hot water which can be a source of energy saving.
So it’s important to check the feasibility of the heating system that to be used in any project. Now a days it has become mandatory / fancy to use a Solar system or heat pump system and kept the entire load as backup where the purpose of energy saving is forgotten.
Saving Electricity Through Central Hot Water Heating System
Water heaters are required in each apartment for producing hot waters for daily use. Each water heater of 50 litre will using 1.5 KW of electric power. In a 200 apartment building almost 300 KW of heating power is required. Most of the cases buildings will not be having sufficient electrical load to meet this demand. In some cases, available 300 kW from the authorities will be very expensive.
In such cases we propose central hot water heating system. We calculate the total hot water required for the building and with higher recovery time and with increased storage volume electricity load can be reduced by more than 70%. Hot water supplied to each apartment can be measured through a water meter and charged accordingly.
Another option to reduce electricity is to use solar, heat pump or direct oil/gas fired system.
With solar system in apartments there are chances where spaces available to keep the solar panels will be very minimal. In those cases 50% load can be achieved through solar panel and 50% with electric load .
Air to water heat pumps can also be used for generating hot water. Heat pump does require electric load to run the Compressors inside the heat pump and storage tanks to be supplied with electric heating element as backup. Available electric load in the building to be considered before selecting the system.
If gas/oil is available, the Direct fired hot water system can be used. With this option no separate boiler is required for producing steam or high temperature hot water which is required for indirectly heating the water.
Advantages of Using Direct Fired Water Heaters :
- No extra boilers are required for producing steam or hot water which indirectly heat the water.
- Water produced in the water heater can be used directly.
- Primary Circulating pumps, Diverting Valves pipe works between boilers and calorifiers can be eliminated.
- Less space required.