A waste heat recovery unit (WHRU) is an energy recovery heat exchanger that recovers heat from hot streams with potential high energy content, such as hot flue gases from a diesel generator or steam from cooling towers or even waste water from different cooling processes such as in steel cooling.
Waste heat found in the exhaust gas of various processes or even from the exhaust stream of a conditioning unit can be used to preheat the incoming gas. This is one of the basic methods for recovery of waste heat. Many steel making plants use this process as an economic method to increase the production of the plant with lower fuel demand.
How do I improve the power generation in a Waste Heat Recovery Boiler?
We can increase the power generation in waste heat recovery system by following some of these steps.
- We can add an additional power source like oil fired burner.
- Water tubes should be regularly cleaned and deposition of soot should not be allowed.
- distilled water with high purity to avoid scale formation in water tube
- Number of exhaust gas passes can be increased.
Advantages and disadvantages of waste heat recovery
These systems have many benefits which could be direct or indirect.
- Direct benefits: The recovery process will add to the efficiency of the process and thus decrease the costs of fuel and energy consumption needed for that process.
- Indirect benefits:
- Reduction in Pollution: Thermal and air pollution will dramatically decrease since less flue gases of high temperature are emitted from the plant since most of the energy is recycled.
- Reduction in the equipment sizes: As Fuel consumption reduces so the control and security equipment for handling the fuel decreases. Also, filtering equipment for the gas is no longer needed in large sizes.
- Reduction in auxiliary energy consumption: Reduction in equipment sizes means another reduction in the energy fed to those systems like pumps, filters, fans… etc.
- Capital cost: The capital cost to implement a waste heat recovery system may outweigh the benefit gained in heat recovered. It is necessary to put a cost to the heat being offset.
- Quality of heat: Often waste heat is of low quality (temperature). It can be difficult to efficiently utilize the quantity of low quality heat contained in a waste heat medium. Heat exchangers tend to be larger to recover significant quantities which increases capital cost.
- Maintenance of Equipment: Additional equipment requires additional maintenance cost.
- Units add addition size and mass to overall power unit. Especially a consideration on power units which are on vehicles.
Thermodyne Boilers provide waste heat recovery boiler i.e. WASTETHERM that is designed to recover heat from flue gases from DG exhaust, Furnace exhaust, Klin exhaust, incinerator exhaust etc. Recovered heat can be utilized to produce steam or hot water based on the requirement of the plant. There are NO FUEL BILLS to operate these and hence they offer handsome payback of investments.