Sino-China Chemical HT-L has been operating stably for 68 days in a row, using coal from the Matihao mine as the raw material

Thread Content

Zhongxin Chemical’s HT-L unit has been operating stably for 68 days consecutive, using coal from the Matihao mine as the feedstock for the first time. Author/Source: Zhongxin Chemical; Date: May 13, 2022; Clicks: 10. As of May 12, Zhongxin Chemical had been using Matihao coal as the main feedstock in the HT-L pressurized coal gasification furnace for 68 days in a stable manner, with the residual carbon content in the filter cake remaining at around 25%. This approach enabled the methanol production facility to achieve a daily output of 1,326 tons of crude methanol, with a monthly output of 39,262 tons – a significant achievement. By analyzing the data from various components of the current facility, and by using coal from the Matheihao mine as the primary coal source for combustion, it was possible to make progress in utilizing the group’s key mines as sources of raw coal. This approach led to numerous innovations; it reduced production costs, and at the same time enhanced the adaptability of the aerospace coal gasification process to different types of coal, resulting in a significant improvement in the performance of the facility. Since the commissioning of the methanol plant, a stable supply of raw coal and the suitability of the coal types have been key factors determining the plant’s ability to operate over long periods of time. To overcome these bottlenecks and maximize the production capacity of the 750 t/d-scale furnace, the company has continued to explore various options; more than a dozen different types of raw coal have been tested, including typical types such as Shenmu coal, Yulin coal, and Gansu coal. Although production levels have increased compared to before, the consumption of coal remains high. How to make full use of existing coal resources, allocate different types of coal reasonably, and achieve high productivity with low consumption is a practical challenge faced by our company. Currently, the raw coal used in gasification units in this industry is mostly high-calorific-value coal from the Shenmu region; this has led to a strong dependence on such coal types. On the other hand, the limited supply channels for raw coal result in high production costs, which in turn affects a company’s ability to control its expenses. To overcome the challenge of using coal with low calorific value in pulverized coal pressurized gasification units, the company’s leadership focused on the production-related difficulties. After conducting extensive research on the gasification properties of the coal from the Matihao mine, they acquired thorough knowledge of parameters such as the ash composition of the coal, ash viscosity, and grindability index. By taking into account the actual conditions of the company’s operations, they broke with conventional approaches and decided to use coal from the Matihao mine as the primary fuel for the gasification units. Based on the performance of the gasification furnaces, they established corresponding operational measures: first, they strengthened the monitoring of coal quality before it was fed into the furnaces, and in line with the requirements for industrial analysis during coal type changes, they increased the frequency of such analyses, particularly those related to the composition of the raw coal, in order to provide data support for operational adjustments ； Secondly, it is necessary to carry out all the necessary preparatory work before switching to a different coal type. The time at which the new coal type will be introduced into the gasifier is calculated based on the operating load and coal consumption rate of the gasifier; the operating conditions are adjusted to stabilize in advance, and the operating temperature is determined using the viscosity-temperature curve. Through the practical application of the Mathei Coal variety, it has been possible, on the one hand, to maintain the dry-base gas production of the gasification furnace, while simultaneously using various methods to control methane levels and reduce the CO2 content in the gas produced. This has further increased the proportion of useful gases, resulting in a consumption of 0.633 tons of raw coal per ton of methanol produced. Thus, the goals of reducing consumption and increasing output have been achieved ； On the other hand, given the high sulfur content in the coal used as raw material for Mathegou coal, an increase in the volume of acidic gases processed by low-temperature methanol washing was carried out alongside an increase in overall load, resulting in the production of sulfur by-products rising from 3 t/d to 6 t/d, a 50% increase on a month-on-month basis. Taking advantage of the high market price of sulfur at 3,600 yuan per ton, the company continues to work toward improving both its production capacity and profitability by pursuing steady progress.