The environmental impact assessment report for Ningxia Donglai Energy Chemical Co., Ltd.’s 250,000-ton coal-based ethylene glycol project has been officially approved

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The environmental impact assessment report for Ningxia Donglai Energy Chemical Co., Ltd.’s 250,000-ton coal-based ethylene glycol production project has been officially approved. Author/Source: Date: 2016-07-27. Views: 21. The project is located north of Road No. 3 in Area II of the Chemical New Materials Park in the Ningdong industrial zone, within the area enclosed by the circular road. The total land area for the project is 525,036 m2, with a total construction area of 226,379.98 m2. The facilities included will be gasification units, purification units, hydrocarbon separation units, DMO units, EG units, as well as auxiliary structures such as laboratories, fire protection systems, and storage areas. The project will enable an annual production of 250,000 tons of ethylene glycol, along with the storage of 70,000 tons of refined oil and heavy oil. The total investment for the project is 2,106 million yuan, of which 260.44 million yuan is allocated to environmental protection measures. These funds are primarily used for controlling dust during construction, as well as for managing noise, wastewater, and solid waste. This project uses coal supplied by the Ningdong Coal Chemical Industry Base in Ningxia as raw material, and employs a new WHG gasification technology to produce crude gas. After quenching and washing to remove dust, partial shift reaction is carried out; the shifted gas is then subjected to low-temperature methanol washing and deep cryogenic separation of H2/CO to produce hydrogen and carbon monoxide that meet the process requirements ； The resulting hydrogen and carbon monoxide are then used, along with oxygen and nitrogen produced by the air separation unit as feed gases, to produce industrial ethylene glycol via an indirect synthesis method. The process production unit area consists of a gasification unit, a CO conversion unit, low-temperature methanol washing and sulfur recovery units, a pressure swing adsorption unit, an air separation unit, and an ethylene glycol synthesis unit. The ethylene glycol synthesis plant mainly includes four steps: nitrite synthesis, oxalate synthesis, methyl nitrite regeneration, and oxalate hydrogenation. Environmental protection measures and actions: 1. Strictly implement the “three simultaneities” principle in environmental protection, which requires that environmental protection facilities for construction projects be designed, constructed, and put into use simultaneously with the main project. 2. The waste gas generated in the slag treatment process is mainly the air released from the high-pressure flash separation tank; this air contains small amounts of H2S and other substances, which are sent to a sulfur recovery unit for treatment and not discharged outside ； The vapor from the vacuum flash tank is condensed in a condenser and separated from the vacuum pump; it contains small amounts of hydrogen sulfide and ammonia, which are then released into the atmosphere. The condensed and desorbed gas generated during normal operation of the stripper in the conversion section contains a relatively high concentration of H2S; therefore, it is sent to the sulfur recovery unit for treatment ； The main components of the decarbonization off-gas are CO2 and N2, with trace amounts of methanol and hydrogen sulfide; it is emitted from a 30-m-high chimney ； The acidic gas containing H2S generated in the thermal regeneration tower is sent to a sulfur recovery unit for treatment, and is not discharged outside. The sulfur recovery unit processes acidic gases from low-temperature methanol washing, shift stripping gas, gasification high-pressure flash gas, and exhaust gases from the MN exhaust treatment process, using a two-stage Claus sulfur recovery + exhaust gas combustion process. The exhaust gas after sulfur recovery is discharged through a 50m tall chimney. The main component of the air released from the safety valves in the chiller unit is ammonia, which is sent to the flare system for combustion. The molecular sieve is used to adsorb the regenerated gas, as well as the nitrogen exhaust from the cold box and the methane exhaust from the cold box. The main components of the gas adsorbed by the molecular sieve are N2, with trace amounts of CO2 and CH3OH; this gas is emitted through a 30m tall chimney ； The nitrogen vent gas from the cold box and the methane vent gas from the cold box, which contain flammable components such as CH4 and CO, enter the fuel gas pipeline network. The off-gases from the regeneration tower in the DMO synthesis section, as well as those generated by the high-pressure separator, are discharged continuously and sent entirely to the exhaust gas treatment process for treatment ； The DMO distillation section absorbs the exhaust gas from the DMO exhaust tower, with continuous emission. Send it to the exhaust gas treatment process for processing ； The exhaust gas treatment process primarily receives and treats the exhaust gases emitted from the DMO synthesis and DMO distillation processes, as well as from nitric acid treatment tanks in the utility systems, sending them to the MN (methyl nitrite) recovery tower for treatment using low-temperature methanol washing. The treated exhaust gas exiting the top of the MN recovery tower is sent to the sulfur recovery unit via a separator. The exhaust gases emitted from units such as the methanol recovery tower, demethanization tower, dehydration tower, dealcoholization tower, ethylene glycol product tower, and ethylene glycol recovery tower in the ethylene glycol distillation section consist mainly of N2, with trace amounts of organic substances such as methanol, dimethyl ether, and ethylene glycol. After being washed in a vacuum pump-driven exhaust gas scrubber, these gases are discharged in compliance with regulatory standards ； The waste gas from air separation units is mainly polluted nitrogen gas, free of air pollutants, and can be discharged directly in compliance with standards. Oil and gas recovery units are installed in the heavy oil and refined oil storage tank areas; the exhaust gases generated during the large-scale breathing of the storage tanks are collected and sent to the condensate tank of these recovery units where they are condensed before being returned to the storage tanks. The recovery efficiency of these oil and gas recovery units is ≥95%. A bag filter is installed during the thiamine drying process to filter and collect dust. 3. For the gasification black water treatment process, after high-pressure and vacuum flashing, the water is settled in a sedimentation tank and reused as water for the scrubber; a small amount of this gray water is sent to the biological treatment plant. The process condensate produced by the conversion unit has a high ammonia nitrogen concentration; in the plant, it is stripped using a stripping tower before being reused as water for gasification. The methanol-containing wastewater discharged from the methanol-water separation tower in the low-temperature methanol washing unit is sent to a biochemical treatment plant for processing. For the high-nitrate wastewater generated by the DMO unit, the plant employs a membrane reverse osmosis separation process combined with a double-effect evaporation crystallization process; after the nitrate compounds are removed, the wastewater is sent for biological treatment. The washing wastewater from the vacuum pump exhaust gas scrubber in the ethylene glycol plant, the floor washing water, the wastewater from flares, and the wastewater from the air separation unit are sent to the biochemical treatment station for treatment. During the production process of this project, the wastewater from the circulating water station, the wastewater from the desalinated water station, and the effluent from the sewage treatment station are all sent back to the water reuse station for treatment. The capacity of this water reuse station is 450 m3/h; the treatment process employed at this station for reusing treated water involves ultrafiltration plus reverse osmosis. The treated water is reused in the circulating water station and not discharged outside. 4. By using low-noise equipment and implementing measures such as vibration reduction and sound insulation, the noise level at the factory boundary must meet the standard limits specified for Category 3 in the \"Emission Standards for Environmental Noise at the Boundaries of Industrial Enterprises\" (GB12348-2008). 5. Gasified ash is an excellent cement admixture that can be used as a raw material for cement, brick manufacturing, etc. For the ash and slag discharged in this project, comprehensive utilization is given priority. Meanwhile, a slag yard is provided in this project; when evacuation routes are limited, the slag is transported to the slag yard for storage. Waste catalysts, due to their content of precious metals, have high value for reuse; they are all recovered and processed by the suppliers, without being released into the environment. All the spent catalysts removed during each replacement are placed in sealed containers, with clear labels attached to their outer walls to prevent them from being mixed up with other solid wastes. If it cannot be transported out in a timely manner, the container must be stored temporarily in a hazardous waste storage area designated for storing catalysts. The crystalline waste salts from DMO wastewater are sent to the Solid Waste Disposal Center at the Ningdong Energy and Chemical Industry Base for disposal. Waste molecular sieves and waste adsorbents from air separation units are recycled and processed by the manufacturers. The sludge cakes generated by the sewage treatment plant are sent to the Solid Waste Disposal Center of the Ningdong Energy and Chemical Industry Base for disposal. 6. The main hazardous substances involved in the various raw materials, auxiliary materials, and production units of the project include gas, methanol, ethylene glycol, dimethyl oxalate, liquid ammonia, dilute nitric acid, refined oil, and heavy oil, among others. In strict compliance with relevant regulations such as the \"Regulations on the Safety Management of Hazardous Chemicals\" and the \"Technical Policies for the Prevention and Control of Hazardous Waste Pollution\", environmental risk management during the production, storage, and transportation phases of the project shall be strengthened. Before the project begins trial production, an emergency response plan for sudden environmental incidents must be submitted for approval, in order to prevent serious sudden environmental accidents and ensure environmental safety.