Guide for heat recovery from industrial treatment plants based on two cases
Food companies often have a very high water consumption and corresponding high wastewater volume due to demands for food and cleaning. Temperature of the wastewater can be high and therefore a potential for energy recovery. Barriers in the form of insecurity on the right solution and economy carries means that very few companies invest in solutions for heat recovery from wastewater.
The temperature of the wastewater is also important for the purification processes and too high or too low temperatures can lead to an unnecessarily high electricity consumption.
This project will through analysis of two industrial treatment plants identify the potential for energy savings by utilizing the waste heat for hot water or heating at the company and ensure proper temperature in the purification process using heat pumps.
The project includes:
- Measurements of temperatures and streams in the two treatment plants. Sampling and analysis.
- Analyses of the wastewater and temperature influence on the cleaning process.
- Analysis of the potential for heat recovery and improving the cleaning process.
- Development of a system solution with heat pump.
- Preparation and testing of the checklist and guide for energy consultants
- Dissemination of results of energy consultants and marketing solution to food companies.
The purpose of this project is to clarify the heat reclaim potential in wastewater from factories with their own wastewater treatment plant facility. In addition, to develop a guide for energy consultants to assist in analyzing energy consumption and heat reclaim potential.
For 3 factories there has been made a waste water analysis, Danpo, BHJ and HK Scan. For each factory the internal wasterwater processes has been analyzed together with the public wastewater treatment plant capacity.
On basis of these analysis there has been made recommendations where in the wastewater process it is possible to take out the potential energy.
Each factory were screened and analyzed to establish the potential for using the reclaimed heat internally and externally.
The internal setup for heat supply for each factory were analyzed and documented. The payback time for each case must include any rebuild of the heating systems. These costs are NOT included in this report.
The heat reclaim potential for each factory is calculated and can be seen in the below table:
|
Summer continous potential [kW] |
Winter continous potential [kW] |
Yearly energy reclaim potential in wastewater [MWh] |
Own energy consumption [MWh] |
Own consumption that can be covered [MWh] |
External possible consumption that can be covered [MWh] |
|
|
HK Scan |
1.400 |
1.000 |
11.600 |
5.800 |
4.700 |
5.800 |
|
Danpo |
1.450 |
1.450 |
10.500 |
5.800 |
4.900 |
4.700 |
|
Essentia |
490 |
490 |
3.900 |
- |
- |
3.900 |
Table 1 shows Energy reclaim potential for each factory.
In this project following tools were developed to be used by energy consultant advisers:
- Guide to help analyzing a factorys wastewater setup.
- Calculation tool to establish the reclaim energy potential for wastewater including a guide how to use the tool.
- Reports about the possibility for heat reclaim together with simple payback time for each factory.
For each factory the technical setup is very different, because both the temperature levels and need for heat is different for each factory. Common for all factories is that a heatpump is an available option. And that the heatpump can be used with any refrigerant.
Based on the reports made for each factory following table shows the available potential heat reclaim:
|
Essentia(BHJ) |
Danpo |
HK Scan |
|
|
Heat reclaim potential [MWh pr year] |
3.855 |
10.516 |
11.613 |
|
Surplus af 5 years [Kr] |
487.000 |
1.091.000 |
1.256.00 |
|
Comments |
Cannot use reclaimed heat internally. Could sell reclaimed heat externally. |
Here can be issues with temperature level of wastewater to surroundings, since local wastewater treatment plant is small. |
Table 2 shows the total heat reclaim potential and surplus for each factory in the project.
General comments:
- Rebuild of internal piping in factories can be a high cost and can prevent from a successful heat reclaim business case.
- Temperature levels for internal use of water can disturb business case.
- Composition of wastewater is extremely important for selecting heat exchangers.
Key figures
Category
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| Aqua Service A/S | ||
| VERDO A/S | ||
| DHI | ||
| BHJ A/S | ||
| DANPO |
