Initial results achieved from the technical upgrade for the transfer of ash water from the third phase of Weihua’s gasification project in Shaanxi

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Initial Results Achieved from the Technical Upgrade for the Transfer of Ash Water from the Gasification Process at Shaanxi Weihua’s Phase III Facility / Author/Source: Compiled and published by the Nitrogen Fertilizer and Methanol Technology Network of Shaanxi Weihua; Date: 2019-06-05; Clicks: 117. On June 2, after more than half a month of intensive construction and process preparation, the technical upgrade project aimed at transferring ash water from the gasification process in the Shuangjia workshop – specifically the project to connect heat exchanger E7404B with ash water heat exchanger E7406 – was put into operation, and initial results have been achieved. Throughout, due to the high load on the gas treatment section and the large volume of ash water, coupled with the limited heat exchange capacity of the external ash water heat exchanger E7406, the temperature of the external ash water has remained high, staying at around 44°C for an extended period of time. With summer approaching, the temperature of the wastewater sent out is about 2–4 degrees Celsius higher than usual. Operation at such high temperatures remains stable, yet the volume of wastewater to be sent out cannot be reduced, which puts significant pressure on the water supply and drainage systems. In severe cases, this can lead to the shutdown of the entire Phase 3 facility. Even minor carelessness may violate environmental regulations, thereby increasing the operational difficulties in the water supply and drainage workshops as well as in the Dimethylamine workshops; load adjustments are also restricted, posing considerable challenges to daily production operations. Faced with this situation, the staff of Workshop 21 worked together, pooled their ideas, and explored the potential of the existing equipment. They ultimately proposed that, while meeting the daily start-up and shutdown requirements, heat exchanger E7404B No. 2 be integrated into the ash water discharge system, thereby effectively reducing the temperature of the discharged ash water and ensuring that the load on the gasification ash water system met the needs of normal production. On June 2, the construction of the technical improvement plan was completed and the system was put into use. On-site tests showed clear improvements as a result of these changes: the temperature of the graywater dropped significantly, from 44°C to around 35°C, meeting the requirements for external discharge. This also reduced the pressure on the wastewater reception system in the water supply and drainage workshop. The technical upgrades have already shown initial results; based on the operational conditions, the workshop is accelerating the process of applying for a new heat exchanger. It is planned to add additional heat exchanger units during the major maintenance period, and once the new heat exchanger is in place, it will be put into use immediately to completely resolve the issue of excessively high temperatures in the wastewater sent outside.