Construction of Zhejiang LNG Cold Energy Utilization (Power Generation) Project Begins
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On the morning of August 30, with the commencement of work on the pile foundations and the modification of the propane transfer pipelines, the Zhejiang LNG Cryogenic Energy Utilization (Power Generation) project officially entered the construction phase. Building on the split-flow vaporizer (IFV) already installed in the second phase of Zhejiang’s LNG receiving station, this project involves constructing a 5MW cold energy power generation unit. It enables the use of cold energy for inducing changes in the state of matter of certain media, thereby driving the generator to produce electricity, all without increasing energy consumption; it is thus an excellent project for energy savings and emission reduction. Upon completion of the project, the annual net amount of electricity generated will be 23.145 million kWh, resulting in a reduction of CO2 emissions by approximately 18,775 tons per year.
The core turbine expansion generator set of the project is a scientific research project under the group company’s “Three New Developments and Three Modernizations” initiative; during its implementation, research on the domestic application of propane-cold energy-based turbine expansion generator sets for power generation will be carried out simultaneously. This not only leads the way in domestic research on propane-based cold energy generation turbine expansion units for IFVs, but also plays a significant role in promoting the engineering application of cold energy generation and cold energy utilization technologies at various receiving stations. The construction of the Zhejiang LNG cold energy utilization (power generation) project not only enhances the efficiency of hierarchical utilization of LNG cold energy and promotes the development of the cold chain industry, but also demonstrates Zhejiang LNG’s active compliance with the energy conservation and emission reduction policies set by various levels of authorities. It is in line with China National Offshore Oil Corporation’s goals of achieving technological self-reliance and sustainable, low-carbon development.
Power generation using cold energy: Generating power from the cold energy of LNG is a relatively novel method of energy utilization; the technology is fairly mature, allowing for large-scale use of LNG’s cold energy. The systems that utilize LNG cold energy for power generation mainly include: the direct expansion method, the secondary refrigerant method, and the combined method. 1. Direct expansion method. The LNG in the storage tank is extracted and pressurized, then heated and vaporized using seawater as a heat source; thereafter, it is sent to an expansion engine to generate work, thereby producing electricity. The natural gas coming out of the expander has its temperature and pressure adjusted as required, before being delivered to the natural gas users. The direct expansion method is simple in principle and requires low investment, but its utilization efficiency of LNG’s cooling energy is very low, at only around 24%. Therefore, this method is mainly used in combination with other cold energy utilization schemes. 2. Secondary refrigerant method. The secondary refrigerant method utilizes a Rankine cycle with an intermediate refrigerant to recover the cold energy of LNG for power generation. The cooling capacity of low-temperature LNG is transferred to the refrigerant, which undergoes a steam power cycle driven by the temperature difference, thereby generating work and electricity. The key to generating power using the secondary refrigerant method lies in the selection of the refrigerant. Commonly used refrigerants mainly include single-component substances such as methane, ethane, and propane, and mixtures of these can also be used. This method offers a higher efficiency in utilizing LNG cooling energy compared to the direct expansion method. 3. Combined method. The combined method integrates the direct expansion method with the secondary refrigerant method, which can **improve the utilization rate of cooling energy, typically maintaining it at around 50%. Most LNG-based cooling power generation projects put into practical use in Japan adopt this method. Cryogenic power generation is an emerging, pollution-free method of power production. Its efficiency in recovering the cold energy from LNG is very low, accounting for only 5% of the energy required to produce LNG. However, it offers advantages such as a short process flow, small land footprint, low investment costs, ease of implementation, and no pollution. Therefore, when other methods of utilizing cold energy are not feasible, cryogenic power generation should be given priority.
【Ten Years of Rapid Development in Chemical Engineering Equipment】All 4 17-megawatt compressors at the Shenyang Liaoluo Compressing Station, built between 2008 and 2022, are of domestic manufacture. https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=3579871 (Source: Haichuan Network – Chemical Industry Forum)