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Author/Source: Xu Nian (Sinopec Baling Branch, Yueyang, Hunan 414003) Date: 2009-1-5 The Sinopec Baling Branch originally had a large-scale ammonia synthesis plant with a capacity of 1000 t/d. This device uses light oil as raw material and employs the Kellogg process. In recent years, due to rising oil prices, losses have been severe. In 2003, Sinopec partnered with Shell to build a new coal gasification unit along with associated purification facilities – the Baling \"coal instead of oil\" project – in order to address the issue of an unreasonable raw material structure and enhance the competitiveness of its products. The features of the project and the progress of the construction are briefly introduced as follows. ? 1 Project Overview? The project is carried out in two phases: the gasification and air separation unit built through a joint venture between Sinopec and Shell (hereinafter referred to as the “joint venture plant”) ； The construction of the supporting facilities and the expansion of the ammonia synthesis unit, carried out solely by Sinopec (under the project owner management system of the Baling Branch, hereinafter referred to as the “Project Department”). (1) The gasification unit of the joint venture plant has a design capacity of 2,000 tons of coal per day (for the designed coal type), and supplies 142,000 m3/h of effective syngas (H2+CO) to the Baling branch. Of this, 140,640 m3/h of syngas is used for ammonia synthesis and hydrogen supply to third parties, while the remaining portion is returned to the gasification unit for internal use after gas treatment. The normal oxygen production capacity from air separation is 48,000 m3/h, with a maximum of 52,000 m3/h. ? (2) The supporting facilities of the project department include: a carbon monoxide conversion unit, an acidic gas removal unit, a newly built methanation unit, newly installed refrigeration machines, modifications to the ammonia synthesis unit, as well as utility systems. The designed ammonia production capacity is 1,320 t/d, with 70 kt/a of liquid ammonia supplied externally, and 46,154 m3/h of hydrogen provided to the caprolactam plant. (3) Utility facilities include a newly built circulating water system with a design capacity of 25,000 m3/h, and a newly built sewage treatment plant with a treatment capacity of 80 m3/h. The torch unit is jointly built by the joint venture factory and the project department. ? 2 Main technical features? 2.1 Shell’s pressurized coal gasification technology and coal type selection? 2.1.1 Introduction to Shell’s pressurized coal gasification technology? Pulverized coal and limestone powder are fed into the four burners of the gasifier using high-pressure nitrogen; after mixing with oxygen and steam, they enter the gasifier where they react at temperatures of 1400–1700°C to produce crude syngas. At the exit of the gasifier, the syngas is cooled using recycled gas, reducing its temperature to around 900°C. Further heat recovery is achieved through boiler feedwater, generating medium-pressure steam. The syngas then reaches a temperature of around 300°C and enters the washing system, where it is cooled in a venturi washer. Dust is removed using high-temperature and high-pressure filters, and finally, HCl, hydrofluoric acid, and trace solids are removed in the washing tower. After washing, the syngas (160°C, 3.7 MPa) is divided into two streams: one is sent to the associated units for further treatment, while the other is used as circulating quench gas in the gasification section. The composition of raw gas is shown in Table 1. ? The slag removal system is responsible for cooling, granulating, and discharging the slag. The slag pool is installed at the bottom of the gasifier, and an annular nozzle is mounted on the top of the slag pool for continuous **. Based on the composition characteristics of the slag, it flows freely into the slag pool; the fine streams/droplets break apart upon impact with the cold water surface (quenching), and the resulting fragmented slag can be easily removed from the system. Table 1 Composition of raw gas from Shell coal gasification under pressure http://www.nmtech.com.cn/jishuwang/upload/0602151000036833.jpg? Note: A represents the raw gas coming out of the gasifier, while B represents the gas from the pre-conversion reactor. The wastewater from the washing system is sent to the sewage stripping and clarification system; the gases emitted are sent to a flare, while the clarified water is reused in the slag removal system. The excess amount is discharged into the sewage treatment system. ? 2.1.2 Characteristics of Shell’s pressurized coal gasification process? Compared with the water-coal slurry gasification process, Shell’s pressurized coal gasification has the following characteristics. ? (1) Dry feeding method, high gasification efficiency. ? (2) The high temperature during the gasification process results in a carbon conversion rate of up to 99%, with the effective components in the gas (CO + H2) accounting for over 90%. (3) Low oxygen consumption. ? (4) Pressurized operation, with high production capacity per furnace. ? (5) The gasification furnace has no refractory lining, no moving parts, a long operating cycle, and no need for a backup furnace. ? (6) The use of multiple burners improves operational reliability and production flexibility; the burner design ensures a service life of 8,000 hours. ? (7) Good environmental performance: The slag, after rapid cooling, becomes glass-like particles with stable properties, causing almost no impact on the environment. (8) The thermal efficiency is as high as 98%. ? 2.1.3 Selection of coal type? After repeated comparison and analysis of Shell’s standards for coal used in design along with relevant standards, it is believed that Shell’s pressurized gasification process does not have very high requirements regarding the type of coal used. Foreign investors emphasize that the coal used for testing must be the designed coal type. For the coal used in production, the project team has initially decided to use coal from this province or a neighboring province, which is crucial for the economic viability of the entire project. ? 2.2 Air separation: A full-low-pressure refrigeration system using a Lindström molecular sieve adsorber and an expander with a booster is employed, with the patent holder providing on-site guidance for installation and commissioning. 2.3 CO conversion catalysts and related process equipment? (1) The syngas produced through joint ventures contains approximately 60% CO; the CO conversion units use sulfur-resistant conversion catalysts developed in China, which are said to exhibit good conversion activity at low temperatures, a wide operating temperature range, high tolerance to water vapor, as well as excellent resistance to sulfur and poisoning effects. ? (2) The design institute, suppliers, and project team jointly developed the \"pre-conversion + two-stage medium conversion + one-stage low conversion\" process flow. In the pre-conversion section, two reactors are connected in parallel, equipped with sulfur-resistant catalysts containing a low level of active components – catalyst protectants. These catalysts are used primarily to prevent solid impurities such as coal ash and carbon black from entering the system, to adsorb toxic substances like As and Cl-, while also facilitating moderate conversion reactions. After pre-transformation, the composition of the gas is close to that of the Texaco process. (3) Catalyst loading: 40.72 m3 for pre-conversion, 161.8 m3 for medium conversion, and 60.8 m3 for low conversion. Axial reactors are used for pre-transformation and low conversion, while axial-radial reactors are employed for medium conversion in order to reduce pressure drop losses. ? (4) The key to the shift reaction is controlling the water/dry gas ratio and the inlet temperature of the shift reactor; for this purpose, a well-developed control and alarm interlock system has been installed. For the first sulfidation of the catalyst, carbon disulfide combined with pre-sulfidation is planned to be used. ? (5) The separated process condensate is stripped and then filtered, to be used as boiler feedwater or quenching water; the excess is sent to the wastewater treatment facility. ? (6) Due to the lack of operational experience, the performance of this type of catalyst, the initial presulfidization process, and the shaft-radial reactor represent some of the challenges in this project; at the same time, they are also among the technical highlights of it. It is necessary to explore, summarize, and optimize this as soon as possible through practice. ? 2.4 Acid Gas Removal Unit? The low-temperature methanol washing process is employed; the LuChi process software package is purchased, with foreign experts providing on-site guidance for installation and commissioning. The designed gas processing capacity of this device is the highest among similar processes in China. ? 2.5 New methanation unit? It is basically the same as the old system, with only a ZnO desulfurizer of approximately 15.27 m3 installed at the top of the methanation reactor to remove trace amounts of sulfur. 2.6 Installing a new ice machine? Set up a new ice machine system to provide cooling for the air separation and acid removal units. ? 2.7 Expansion and renovation of ammonia synthesis capacity to 1320 t/d? (1) The pressure in the synthesis system is maintained at around 12.55 MPa; the amount of recycle gas fed into the tower is increased appropriately to ensure that key equipment such as the synthesis tower meets the required scale without the need for modifications. ? (2) High-pressure steam at 9.5 MPa and 520°C is used in place of the previous steam at 10.3 MPa and 460°C to drive the syngas compressor turbine (relevant modifications have already been made), thereby increasing the transport capacity; the high- and medium-pressure steam pipelines have also been modified accordingly. ? (3) An additional screw chiller is installed to address the issue of insufficient cooling capacity in the refrigeration system; the additional cooling capacity provided is approximately 17.56 GJ/h. ? (4) Calculate the heat exchange area; if it is insufficient, use parallel connection by adding more heat exchangers. ? 2.8 Measures and methods for the treatment of waste materials? Shell attaches great importance to project safety and environmental protection, and Sinopec is also actively implementing the \"HSE\" management system adopted by Shell; as a result, the waste materials generated in this project are properly treated. ? (1) During normal operation of the gasification unit and associated facilities in this project, the waste gases generated, as well as those emitted during startup/shutdown and in emergency situations, are all sent to a flare for combustion. The foul-smelling substance H2S, the irritating gas NH3, as well as H2 and CO are converted into SO2, NOX, and CO2 through combustion in a flare, before being released into the atmosphere. The removal efficiency for CO is 99.6%, and the levels of the other pollutants also meet the relevant emission standards. (2) The economic efficiency of torch combustion is an issue that deserves attention; the foreign party requires a calorific value of 8360 GJ for complete combustion. Therefore, a large amount of liquefied gas needs to be burned, resulting in costs in the tens of millions per year. The project team, in collaboration with a supplier, developed a low-calorific-value torch tip that is said to be capable of completely burning gases with a calorific value of 3344 MJ, thereby **reducing the amount of liquefied gas needed for combustion or the hydrogen required, to acceptable levels. The torch head is divided into a cold torch head and a main torch head. Under normal conditions, only the cold torch maintains three continuously burning flames, with a gas consumption of approximately 7.5 m3/h. Under abnormal conditions, the maximum consumption of liquefied gas is about 2 t/h. For torches and similar devices, dual-path dual-ignition high-altitude igniters as well as long-range explosion-proof UV-infrared flame detectors are used to ensure safety. The project department is currently organizing trial firing tests. The specific performance still needs to be further evaluated through future test runs and pilot production. ? (3) The wastewater contains pollutants such as ammonia-nitrogen, cyanides, and solid suspended particles; the CASS treatment process is used, and the treated wastewater meets the relevant environmental discharge standards. ? (4) The waste materials mainly consist of about 100 kt of waste from the gasification unit per year and 30 kt of dry ash; these are sent out for external treatment to be used as building or road construction materials. ? (5) Build a new sulfuric acid plant to treat the hydrogen sulfide-containing exhaust gas emitted by the acidic gas removal unit, converting it into sulfuric acid for use within the branch company. ? 2.9 Characteristics of project construction and operation? (1) The air separation and gasification units were built through a joint venture between Sinopec and Shell, with each party contributing 50% of the investment. Sinopec Ningbo Design Institute General Contracting (ERP). The supporting facilities and the renovation of the ammonia synthesis plant with a capacity of 1,320 t/d were designed by Ningbo Design Institute and the design institute of Baling Branch Company (Baili Company). Baling Company established a coal-substitution for oil project team to carry out owner management. ? In (2), Sinopec is responsible for providing the raw materials and utility services necessary for the joint venture plant, and it receives all the outputs from the plant; the joint venture plant charges a fee for the processing of syngas. Shell sent its general manager, operations manager, and other key management personnel. ? (3) The Shell powder gasification pressurization process is being introduced in China for the first time. The core components of the Baling \"coal instead of oil\" project were developed through joint ventures, which helped to mitigate technical risks to a large extent. However, this approach meant that the Chinese side assumed significant operational risks. Moreover, the segmented approach to project construction and management led to conflicts between Chinese and foreign management styles and concepts, as well as a range of new issues related to design, production coordination, measurement, and accounting across different stages of the project, thereby increasing the difficulties in managing it. ? (4) Given the current market conditions, if the load is low in the first year of operation, the project may struggle to achieve the expected profitability; therefore, high standards are required for project construction and production preparation work. ? 3 Project progress? (1) Sinopec requires that certain components of the project be delivered by \"9·30\". Testing and feeding in at the end of the year. As of the end of June, 99% of the design work was completed, 92% of procurement tasks were finished, 96.5% of civil engineering and construction work was done, and 37.5% of installation work was completed; the overall progress of the project is 73.5%. The project team should be able to meet the CCCC goals set for September 30th on schedule. ? (2) The arrival of the joint venture gasifier is delayed by 2 months, and due to other factors, the conditions for starting up the plant may not be met until February next year. ? (3) Currently, the project team and the joint venture partner are drafting the overall commissioning plan. It is estimated that the conditions for official commissioning and operation will be met in January or February next year. ? 4 Conclusion? The \"coal instead of oil\" project in Baling will completely change the unreasonable structure of raw materials used in Baling’s fertilizer production facilities. It also creates conditions for Baling Company to optimize the structure of its main products and to start producing carbon-based chemicals; it is thus a \"hope project\" for Baling Company. The project has received great attention from Sinopec, as well as strong support from the local authorities. Included as a key project in Hunan Province, under Sinopec. At present, the entire company, along with the design and construction units as well as the joint venture partners, are making every effort to overcome difficulties and work diligently to ensure the smooth progress of the project, striving to turn this \"coal instead of oil\" project into a \"model project\" and a \"high-quality project\" for Sinopec.