Recently, the heat pump energy-saving waste heat recovery retrofit project for the ammonia nitrogen wastewater treatment system undertaken by Cycle Columbus was successfully completed and put into service through close collaboration and joint witness of both teams.
The project has not only achieved a substantial reduction in system operating costs but also made breakthrough progress in carbon dioxide emission reduction. The overall energy-saving effect far exceeds the target expectation. It strongly supports the enterprise in simultaneously improving resource recycling efficiency and environmental benefits, further helping the enterprise clarify the implementation path of energy conservation and emission reduction in the future and set clear, quantifiable green development goals.
Project Overview
This project carries out energy-saving retrofit on the original ammonia stripping system, which was constructed by Zhongke Kanglun in 2018. Seven years later, our company performed energy optimization design on the existing foundation and introduced the MVR heat pump process to further improve thermal energy utilization efficiency, significantly cutting steam consumption, circulating water consumption and overall operating costs.
Wastewater source of the original ammonia stripping system: high-concentration ammonia nitrogen wastewater generated during the production of ternary precursor from battery recycling.
Treatment capacity: > 2,000 tons per day. The ammonia nitrogen concentration after treatment shall be ≤8 mg/L, and the concentration of recovered ammonia water for resource utilization ≥12%.
Performance assessment indicator: steam consumption saved by no less than 45% compared with pre-retrofit status, without impairing the performance of the original ammonia stripping system.
Project Highlight 1
The introduction of the MVR heat pump process enables energy optimization design for the ammonia stripping system. By upgrading the heat grade of overhead steam, the latent heat of vaporization of overhead steam is efficiently recovered. It reduces the heat supply at the tower bottom and cuts the energy consumption at the tower top, realizing efficient recovery and utilization of thermal energy as well as carbon emission reduction.
The MVR heat pump process features high coefficient of performance (COP), superior energy-saving performance and stable operation. The centrifugal steam compressor selected for this project has advantages of large flow rate, high efficiency, stable operation and clean gas, suitable for the working conditions of this project.
Project Highlight 2
Site survey revealed very limited space on site, bringing considerable challenges to site layout, equipment selection and field construction. To properly arrange all equipment, we negotiated with the owner to remove part of the original indoor equipment to free up space for reboiler installation. The reboiler was redesigned from vertical type to horizontal type to solve constraints of floor height and limited site area.
Project Highlight 3
The owner set stringent requirements on the overall project schedule. To accelerate progress and guarantee smooth execution, construction drawings were designed with 3D software. Clash detection was performed at the design stage to reduce drawing revisions, avoiding on-site pipeline clashes, increased construction difficulty and schedule delays caused by design defects.
Project Timeline
The project officially kicked off in early March this year. The design team raced against time and finished 3D construction drawing design within only 72 days. Afterwards, equipment arrived at site successively in June. With persistent efforts from the project team and overcoming harsh local weather including high temperature and heavy rain, equipment delivery, pipeline connection, equipment hoisting and on-site welding were completed in 55 days. After finishing overall installation in early August, commissioning commenced. System commissioning and handover were completed in late August. Following one month of stable system operation, the project passed acceptance smoothly at the end of September.
Project Significance
The annual wastewater treatment capacity of this project reaches 900,000 tons. Through the heat pump distillation energy-saving retrofit, steam consumption per ton of wastewater is slashed by 54%. Annual operating costs are reduced by more than 40%, with cost savings exceeding RMB 6.11 million. While delivering remarkable economic benefits, the environmental benefits are equally outstanding: annual carbon emissions drop by 44%, equivalent to a carbon reduction of 6,663,824.62 kg, which equals planting approximately 370,000 trees, marking prominent ecological contributions.
This retrofit delivers energy-saving results far beyond expectations and helps the client recover investment rapidly, successfully achieving the strategic goal of "cost reduction and efficiency improvement". Practice proves that the heat pump distillation technology has mature processes and considerable benefits. It is expected to lead a new round of technological innovation in the industrial energy-saving sector and inject strong momentum into green and low-carbon transition.
