RC Power Generation Subsystem
The primary technology for utilizing low and medium temperature waste heat for electricity generation internationally is the Organic Rankine Cycle (ORC) technology. The Organic Rankine Cycle (ORC) uses low-boiling-point organic working fluids to exchange heat with low and medium temperature heat sources, causing the latter to evaporate and produce organic steam at a higher pressure to drive a steam turbine for power generation.
Conventional steam turbines typically operate at temperatures above 150°C, whereas ORC systems can function within the 80-150°C range. ORC technology is an internationally industrialized mid-temperature and low-temperature power generation method, widely applied in industrial waste heat and new energy fields such as geothermal, solar, and biomass.
The Organic Rankine Cycle (ORC) power generation system is primarily composed of an evaporator, turbine, generator, condenser, working fluid pump, etc. The system structure is fully enclosed, and its thermodynamic cycle characteristics are similar to the reverse operation of an air conditioning system. The ORC power generation system is structurally simpler and more compact than a steam turbine system of the same power output.
The ORC power generation system boasts the following advantages:
Adaptable to a temperature range of medium to low temperatures (80-150°C), which is the area where ordinary steam cannot generate power.
No need for a power and water supply (water treatment) system, significantly reducing investment, shortening construction time, and simplifying operational procedures and maintenance costs.
The system can be manufactured using modular, standardized design and production, typically with individual units ranging from 0.02MW to 0.2MW, which can be paralleled in multiple unit modules. Each unit has a high redundancy, allowing operation within a range of +30% to -30% of the rated power.
The entire system only requires some customer-specific design in the heat collection section, with minimal on-site construction work needed. Civil engineering efforts are minimal, resulting in a shorter construction period.
The system operates fully automatically and can be unattended, with simple maintenance and low operation costs. The annual operating cost of the ORC waste heat recovery system is only about 1-3% of its purchase cost.
1. Introduction to Main Components of the System
Turbine
The ORC turbine is a critical component of the ORC system. This turbine boasts stable operation quality, adapts to various operating conditions, excellent sealing, and high efficiency (typically internal efficiency of 80-90%). It employs mechanical or magnetic sealing or integrated turbine-generator set sealing, ensuring superior system sealing performance. The Organic Rankine Cycle (ORC) system generally uses organic working fluids, which are prone to leakage when evaporating into a gaseous state. Should leakage occur, it not only severely affects system operation and leads to shutdown but also requires frequent topping up of working fluid, making the operation complex and costly. Our company's ORC turbine, due to its excellent sealing, is widely used internationally in ORC turbine technology. It offers high efficiency and a large power output, utilizes direct connection, is equipped with rectifier-inverter cabinets, automatic grid-connection cabinets, and generates electricity even during fluctuations in the heat source, resulting in overall higher electricity production.
Control System
Based on the process flow and operating characteristics of the ORC power station, the following control methods are adopted:
1. Utilizing centralized control, variable-frequency quality pump and rectifier-inverter grid-connection control are centrally located on-site or in a single control room. Depending on the conditions, the control room can be established within the existing two, or a control cabinet can be added.
2. The system is set up with remote I/O stations. Communication is established with the PLC via communication interfaces (or hard-wired connections), enabling centralized monitoring of the system conditions within the central control room.
3. Install industrial TV surveillance systems at key production stages or locations for direct monitoring.
The ORC system typically operates in an automated, closed-loop mode. In the event of a fault, only the heat source input needs to be addressed; simply switch the steam heat source to bypass.
Grid connection
The power generation capacity of this system is relatively small. According to general industrial practice, you can select a power switch station with a load greater than that of this system nearby and connect it independently. The specific connection method will be determined at the project implementation stage.
Site
For safety and other considerations, a simple color steel shed can be arranged, with specific dimensions to be confirmed based on the on-site conditions.
Although the site is not in a region prone to heavy rain, proper drainage should be ensured to prevent water intrusion. Additionally, as an ORC power generation system, it is necessary to appropriately isolate access by non-professionals; simple isolation facilities and warning signs can be set up.
Electricity supply
The auxiliary system of this system, such as the working fluid pump, condenser pump, and instruments, requires electricity and needs a power distribution facility, 380V, 3-phase, 50Hz.
The system has an electricity meter installed to measure its self-consumption. Alternatively, electricity meters can be set up according to the client's specifications and requirements. The system's power consumption and generation are separated into independent systems.
Project Implementation Schedule
The total working time for this system is approximately 4 months, including a preparation period of 1 month, a production period for the equipment of 2 months, and a 1-month installation and acceptance period.
