What is The Benefits of Industrial Waste Water Heat Recovery

Waste water heat recovery systems are becoming increasingly important in industrial processes as a means of reducing fuel consumption and emissions. This can be achieved through a variety of methods, depending on the source of the waste and the purpose for which it is being used.

The energy content of wastewater is influenced by its temperature and flow rate. This determines the amount of waste heat that can be recovered by the system.

Reduction in Energy Consumption

Industrial waste water heat recovery offers a significant opportunity for energy efficiency improvement. As much as 80% of heat lost in manufacturing processes can be recovered. This can result in lower costs, increased productivity, and reduced maintenance costs.

Typical “energy audits” identify annual energy cost savings of about 5%, but systematic projects based on sound thermodynamic principles can yield energy savings of 10% to 20% and payback periods of 6 to 18 months for industrial facilities. This means that waste-heat recovery projects can be a major driver in energy savings for companies.

In addition to reducing energy costs, waste-heat recovery can also help reduce greenhouse gas emissions. This is particularly relevant in the US, where it has been estimated that industrial waste-heat recovery could substitute for 9% of the nation’s total energy use–or 1.4 quadrillion BTU–and serve to mitigate greenhouse gas emissions (Energetics and E3M 2004).

Wastewater from residential, industrial, commercial, and agricultural activities maintains considerable amounts of thermal energy after discharging into sewer systems. This thermal energy is often used to supply space-heating and hot-water demands in wastewater treatment plants (WWTPs).

 

The thermal capacity of a particular type of waste-water depends on its temperature and flow rate. The higher the flow rate, the greater the potential for heat recovery.

Low-temperature waste-heat sources such as sludge treatment, cooling water, and process loads can be used directly to preheat boiler feedwater or combustion air, and for heating industrial processes and equipment. However, this type of waste-heat recovery is relatively difficult, and requires a system that can rapidly raise the fluid’s temperature to a suitable level for distillation, evaporation, heating, and space heating.

Typically, this type of WWHR can be implemented using a heat pump to increase the fluid’s temperature and thus increase its energy availability. A heat pump system can recover a great deal of the fluid’s energy, and may even provide an alternative source of electrical power for a plant.

Besides supplying the space-heating and hot-water needs of WWTPs, this recovered heat can be used for low-temperature treatment processes like sequencing biological reactors (SBRs). Pochwala and Kotas (2007) presented an experimental study that demonstrated the use of wastewater-heat recovery to increase the temperature of a SBR from the raw wastewater’s discharge temperature to the desired process temperature.

Reduction in Emissions

Industrial waste water heat recovery is a great way to reduce the greenhouse gas emissions that are produced from industrial processes. The process involves recovering the energy contained in waste heat from industrial processes, and then using it to meet heating demands.

The energy recovered from the waste water can be used to preheat boiler feedwater, steam or air and can also be utilized for other purposes such as distillation, evaporation or even space heating. It can also help to reduce fuel consumption and lower operational costs for the facility.

There are a variety of different types of industrial waste water heat recovery systems that are available. These include high temperature, medium temperature and low temperature systems. The higher the temperature of the waste heat, the more likely it is to be recovered.

Most of the waste heat in industrial processes comes from the exhaust of combustion units, including gas turbines and steam boilers. Most of this is high temperature waste heat, although it can be recovered from some lower temperature sources as well.

Another significant source of waste heat is the by-products of chemical, petrochemical and food industries. These by-products are usually low in temperature and referred to as Low-Grade Waste Heat (LGWH).

 

This is an increasingly important resource for industrial facilities that can utilize it for heating, cooling and even electricity generation. This type of waste heat can be recovered at the component level, building level and sewer pipe network level.

The efficiency of these systems varies greatly depending on the type of waste and the location in which it is collected, but it can be recovered for a wide range of applications. In addition to the energy savings, these systems can be a cost-effective solution for many industrial facilities.

As energy prices are rising globally, and with the threat of climate change on the horizon, it is important to take advantage of any opportunity that can save the environment and reduce the greenhouse gas emissions produced by industrial processes. Incorporating industrial waste heat recovery into your facility can reduce energy costs, improve the operation of your industrial process and even help you qualify for governmental incentives and subsidies.

Increased Efficiency

Industrial waste water is a hot and abundant source of energy that can be recovered for a variety of purposes. Similar to the internal combustion engine of a regular car, the energy in wastewater can be converted into mechanical work or electricity through the use of a heat exchanger and/or a heat pump.

Typical waste-heat recovery systems can yield annual energy savings of 10% to 20% with paybacks in 6 to 18 months for industrial facilities, according to recent studies and reports. However, the potential energy savings could be even greater through the newest developments in waste-heat recovery technology.

In addition to providing a significant reduction in energy consumption, industrial waste water heat recovery can also increase efficiency. This can be achieved through the use of heat exchangers and/or heat pumps that facilitate the transfer of thermal energy between different fluids without mixing them.

For instance, a heat exchanger can be used to recover the thermal energy of raw wastewater before it is sent to a WWTP for treatment. The resulting hot water can be used to preheat incoming cold-water, as in domestic and commercial shower facilities, or to reheat low-temperature treatment fluids for use in a range of other applications.

The amount of recovered thermal energy can vary depending on the type and location of the system. This study provides a comprehensive review of the research on heat recovery from wastewater, identifying opportunities for improvement and application.

There are a number of different levels of industrial waste water heat recovery, each of which has its own benefits and disadvantages. These include cost, environmental impacts, and technical difficulty.

Level one is a system that uses a heat exchanger to extract the thermal energy of raw wastewater before it is pumped into the sewer system. This process can be carried out in two ways; the first is through a heat exchanger installed in the pipe bed, and the second is by installing an external system above ground.

In both cases, a portion of the wastewater will be screened before it is pumped into the heat exchanger. This will prevent coarse material from being sucked into the pipe bed, which can result in poorer performance.

Reduced Costs

Industrial waste water heat recovery (WWHR) can save companies and industry sectors significant amounts of money. It is an energy conservation measure that can reduce costs associated with operating equipment and generating electricity. This also has a positive impact on the environment.

Several industries and businesses are affected by rising energy prices. As such, it is important for them to be able to save as much as possible. In addition, this will help them reduce their carbon emissions as well.

Wastewater is an excellent resource for renewable heat generation. It contains thermal energy that can be used to heat up buildings or provide hot water for industrial uses.

WWHR can be incorporated in several different applications, including commercial kitchens, restaurants, hotels and laundromats. Depending on the application, the heat can be recovered through a heat exchanger or a heat pump.

The heat that is stored in the wastewater varies with the flow rate and the temperature of the wastewater. The higher the flow rate, the greater the thermal potential. In this regard, a potential energy recovery of 6000 GWh per year is estimated in Switzerland [5, 6].

In Germany, the amount of potential heat available in sewer pipes ranges between 1 and 3 TWh/yr. It is not surprising that the majority of heat sources for this renewable source are located in building sewers or at wastewater treatment plants (WWTPs).

However, the exploitation of these resources can present various challenges and obstacles. For example, the distance from the wastewater pipeline to the heat station may be too long or too close for economical use. In some cases, the existing piping infrastructure in a facility will have to be modified to accommodate the installation of the heat exchanger or the heat pump.

These obstacles can make it challenging to implement a sustainable industrial waste water heat recovery project. This is particularly true when retrofitting an existing building.

Despite these limitations, there is a potential to reduce energy consumption in industrial settings by using a heat pump. In addition, the reduced waste disposal will decrease the environmental burden of these facilities.