Tag Archive waste heat recovery

Waste heat recovery from spray painting exhaust gas

Spray coating is a surface treatment method that sprays plastic powder onto parts, widely used in various fields such as automotive, electronic products, furniture and appliances, construction industry, machinery, and public facilities. The waste heat recovery plate heat exchanger for spray coating waste gas is an energy recovery device that can recover and utilize the heat energy generated during the high-temperature baking process of spray coating.


working principle:
The plate heat exchanger for waste heat recovery from spray coating waste gas transfers the heat from the dry waste gas to other media, such as fresh air or water, to achieve energy recovery and utilization. The device consists of a series of parallel arranged metal plates, and the gas from the heat source and cold source flows cross between the plates, achieving heat transfer through thermal conduction and convective heat transfer of the metal plates.
Application areas:
Spray painted waste gas heat recovery plate heat exchangers are widely used in industries that require a large amount of thermal energy, such as metallurgy, chemical industry, building materials, machinery, electricity, etc. In these industries, the exhaust and smoke exhaust of various smelting furnaces, heating furnaces, internal combustion engines, and boilers, as well as the residual heat of flue gas from industrial kilns, are the main objects of waste heat recovery.
Product advantages:
Efficient heat transfer: The plate type gas waste heat recovery heat exchanger adopts an efficient plate design with a high total heat transfer film coefficient, which can quickly and effectively transfer heat.
Compact structure: The equipment occupies a small area, is lightweight, and has a large heat exchange area per unit volume, making it suitable for situations with limited space.
Safe and reliable: The equipment adopts a fully welded form, and the manufacturing process strictly follows the enterprise standards. Multiple pressure testing procedures ensure that the equipment can be used for a long time without leakage.
Energy saving and environmental protection: By using heat exchange to cool down the waste heat flue gas, the heat recycling system achieves the goal of energy saving, improves the economic efficiency of the enterprise, and reduces operating costs.
matters needing attention:
When selecting and using spray coating waste gas heat recovery plate heat exchangers, it is necessary to design and install them according to specific spray coating process parameters and requirements. It is important to ensure that the selection of the heat exchanger is appropriate, the material is heat-resistant, and appropriate control measures are taken to ensure the stability and safety of the heat exchange process.

Drying waste heat recovery

The heat pump drying heat recovery system can be applied to the drying of food, medicinal materials, tobacco, wood, and sludge. It has the characteristics of good drying quality and high degree of automation, and is the best and preferred product for energy-saving, green, and environmental protection in the modern drying industry.

The unit utilizes the reverse Carnot principle and efficient heat recovery technology. Throughout the entire drying and dehumidification process, the humid air in the drying room is connected to the main unit through a return air duct. The sensible and latent heat of the humid air is recovered using a sensible heat plate heat recovery device for heat recovery and reuse, greatly improving the performance of the main unit, drying speed, and material quality.

Calculation method for waste heat recovery from exhaust gas

There are two main approaches to calculate the potential for waste heat recovery from exhaust gas:

1. Thermodynamic Approach:

This method uses the principles of thermodynamics to determine the theoretical maximum amount of heat that can be recovered. Here's what you need to consider:

  • Mass flow rate (ṁ) of the exhaust gas (kg/s) - This can be obtained from engine specifications or measured with a flow meter.
  • Specific heat capacity (Cp) of the exhaust gas (kJ/kg⋅K) - This value varies with temperature and needs to be obtained from tables or thermodynamic software for the specific gas composition of your exhaust.
  • Inlet temperature (T_in) of the exhaust gas (°C) - Measured with a temperature sensor.
  • Outlet temperature (T_out) of the exhaust gas after heat recovery (°C) - This is the desired temperature after heat is removed for your chosen application (e.g., preheating combustion air, generating hot water).

Heat recovery potential (Q) can be calculated using the following formula:

Q = ṁ * Cp * (T_in - T_out)

2. Simplified Approach:

This method provides a rough estimate and is easier to use for initial assessments. It assumes a specific percentage of the exhaust gas energy can be recovered. This percentage can vary depending on the engine type, operating conditions, and the chosen heat exchanger efficiency.

Estimated heat recovery (Q) can be calculated with:

Q = Exhaust gas energy content * Recovery factor

Exhaust gas energy content can be estimated by:

Exhaust gas energy content = Mass flow rate * Lower heating value (LHV) of the fuel

Lower heating value (LHV) is the amount of heat released during combustion when the water vapor formed condenses (available from fuel specifications).

Recovery factor is a percentage typically ranging from 20% to 50% depending on the engine type, operating conditions, and the chosen heat exchanger efficiency.

Important Notes:

  • These calculations provide theoretical or estimated values. The actual heat recovery may be lower due to factors like heat exchanger inefficiencies and piping losses.
  • The chosen outlet temperature (T_out) in the thermodynamic approach needs to be realistic based on the application and limitations of the heat exchanger.
  • Safety considerations are crucial when dealing with hot exhaust gases. Always consult with a qualified engineer for designing and implementing a waste heat recovery system.

Additional factors to consider:

  • Condensation: If the exhaust gas temperature drops below the dew point, water vapor will condense. This can release additional latent heat but requires proper condensate management.
  • Fouling: Exhaust gas can contain contaminants that can foul heat exchanger surfaces, reducing efficiency. Regular cleaning or choosing appropriate materials may be necessary.

By understanding these methods and factors, you can calculate the potential for waste heat recovery from exhaust gas and assess its feasibility for your specific application.

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