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Are ground torches used? I. General overview of the flare system and surface flares The flare system, as a facility for the safe and effective discharge of gases or liquids in refineries or petrochemical plants, is an essential part of the accident relief system. With technological advancements, torch systems have also undergone significant changes, evolving from originally only overhead torches to a combination of ground-based and overhead torches. Among them, ground torches are widely used abroad due to their small footprint, ease of maintenance, as well as good safety and environmental performance; however, they are less used in China at present. Therefore, currently torches come in different types based on various classification methods. Based on whether the burner is above or below the ground, they can be divided into ground torches and elevated torches; based on the design of the burner, they can be classified as single-point combustion torches or multi-burner torches. Ground torches usually refer to closed torches, but they also include ground multi-burner torches, with the choice being primarily based on the amount of material to be released in case of an accident. The former is mainly used in chemical plants with low discharge volumes, while the latter is primarily used in ethylene and natural gas projects with high discharge volumes. The components of an above-ground torch include, in addition to all the elements found in a regular torch such as burners, igniters along with their lighting devices and flame detectors, floating or velocity seals, gas-liquid separation tanks, detectors for flammable and explosive gases, liquid seals, pipes, smoke and dust removal control systems, and radiation protection equipment, enclosures and gas manifolds as well. The ground torch system ensures that the exhaust gases generated by the production units under various operating conditions – such as startup, shutdown, normal operation, and emergency situations – can be vented and burned in a timely, safe, and reliable manner. It also meets environmental protection requirements regarding thermal radiation and the emission levels of harmful gases. As a highly effective closed-type waste gas combustion system, the ground torch has the following characteristics: (1) It emits little thermal radiation in all directions; the thermal radiation level outside the enclosure can be kept below 1.6 kW/m2, which allows for a reduction in the size of the protective area. (2) It is easy to maintain; aside from the relatively high enclosure, all other facilities are on the ground level. (3) It minimizes air pollution, light pollution, and noise pollution in the surrounding environment, thereby enhancing the safety of torch operations. (4) It requires less floor space; since combustion occurs at the ground level, there is no risk of fire rain, and the fire protection distance is primarily determined based on calculations of radiant heat. II. Special Requirements 1. Safety distance between ground torches and installations Due to the limited use of ground torches in China at present, the Code for Fire Protection Design of Petrochemical Enterprises only sets requirements for the installation of elevated torches in Section 6 of Chapter 5; there are no regulations regarding ground torches in this code. In foreign countries, where ground flares are widely used, relevant flare specifications such as AP1521 \"Guidelines for Pressure Relief and Pressure Reduction Systems\" and AP1537 establish clear requirements for calculating the safety distance between ground flares and the facilities. 2. The design of the above-ground torch should be carried out by taking into account the geological conditions, meteorological conditions at the client’s site, as well as the required seismic resistance level. 3. The ground torch system should vent the gas such that the combustion flame remains completely contained within the radiation-proof insulation cover, so that the flame is not visible from the outside; this helps to minimize the impact of heat radiation and noise on the workers and surrounding equipment. 4. A safety barrier should be installed around the ground torch to prevent people from entering it and avoid any hazards ； In extreme situations where a torch experiences deflagration or explosion, it is able to withstand the impact of the explosion without being damaged, and it forces the explosion waves to dissipate upward, thereby preventing harm to people and equipment on the ground.