Differences among various isothermal transformation techniques

(Jiang Xiaomao, reporter from Chemical Industry News; Li Jiangang, correspondent) On March 20, news came from Shandong Hualu Hengsheng Chemical Co., Ltd. Regarding the company’s projects for upgrading its traditional industries and implementing clean production practices, the controlled heat transfer conversion unit – which is used in conjunction with the 6.9MP water-coal slurry gasification process – was successfully put into operation on March 6. This conversion unit is capable of producing 500,000 tons of ethylene glycol, 338,400 tons of methanol, and 304,000 tons of synthetic ammonia per year. It represents the largest facility in China to utilize controlled heat transfer conversion technology. The conversion furnace meets all specified requirements: a dry basis gas flow rate of 326,000 Nm3/h, an outlet CO concentration of ≤0.40%, a temperature difference across the same circular surface of ≤5°C, and a bed resistance of ≤0.021 MPa. All these parameters meet or exceed the design values； Pan Desheng, Chief Engineer of Shandong Hualu Hengsheng Chemical Co., Ltd.: This set of controllable heat-transfer conversion units has achieved the desired objectives, and compared with traditional adiabatic conversion technologies, it offers the following distinct advantages: First, a single set of such conversion units can not only meet the operational requirements for an annual production of 500,000 tons of ethylene glycol, 338,400 tons of methanol, and 304,000 tons of synthetic ammonia, but also allow for adjustments to the production capacities of ethylene glycol, methanol, and ammonia based on fluctuations in their market prices. This enables companies to maximize profits. The adjustment process is simple, safe, and rapid, reflecting the comprehensive, safe, stable, practical, simple, and diversified characteristics of the device’s process design and control systems ； II. Compared with the traditional two-stage adiabatic shift process using 300,000 tons of synthetic ammonia per year, the adoption of controlled heat transfer shift technology reduces the CO content at the exit of the shift system from 1.5% to 0.4%. Without increasing the volume of feed gas, simply by improving the CO conversion rate, an additional 4,142 Nm3 of hydrogen can be produced per hour; this results in an annual increase in synthetic ammonia production of 16,680 tons. Just from this aspect, enterprises can earn a net profit of around 41.7 million yuan per year. Currently, there are nearly a hundred sets of adiabatic shift units for water-coal slurry pressurized gasification in China, and the successful application of controlled heat transfer shift technology will provide favorable conditions for these enterprises to save energy and improve efficiency ； III. The controllable heat transfer conversion technology primarily utilizes water contained within the heat transfer tube bundles embedded in the catalyst bed to remove the heat generated by the reactions. The temperature at the outlet of the catalyst bed remains constant. For water-coal slurry conversion units, this approach not only enables the production of superheated steam, allows for the recovery of high-quality thermal energy while minimizing the amount of low-quality thermal energy produced, ensures stable subsequent heat recovery, and reduces engineering costs, but it also helps to extend the service life of the catalysts in each reactor ； IV. The resistance of the first radial adiabatic catalyst bed is ≤0.036 MPa, and that of the second variable heat-transfer radial bed is ≤0.021 MPa. Although the conversion system is equipped with 4 stages of steam evaporators, the total system resistance remains ≤0.37 MPa, which represents a reduction of 0.13–0.18 MPa compared to traditional two-stage axial adiabatic conversion systems. The operation of the radial catalyst beds lays a solid foundation for scaling up the system as a single-unit installation ； V. The terminal reactor in this conversion unit is a controllably heat-transferred conversion reactor; during the production of hydrogen for ethylene glycol and synthetic ammonia, a single pass of the gas through this reactor ensures that the CO level at the exit of the conversion system is ≤0.40%. This eliminates any impact of the conversion unit on the startup time, thereby reducing the costs associated with startup procedures ； VI. Type V controllable heat transfer conversion reactor: the upper and lower spherical chambers serve as heat exchange tube bank manifolds, effectively addressing the problem of thermal stress arising from isothermal conditions on the water side and non-isothermal conditions on the gas side of the manifolds. This setup facilitates the installation of an insulating layer around the catalyst bed; it not only enables a balance between high temperatures on the outside and lower temperatures on the inside, thereby extending the catalyst’s service life and reducing operational energy consumption, but also helps to facilitate the removal of the catalyst ；

What are the advantages of having relatively low resistance drop control in the conversion unit?

Reduced transformation resistance can increase the load on the gasifier.