航天炉"点煤成金"：从我国第一台自主粉煤加压气化炉到零碳负碳技术转型The Space Furnace 'Turns Coal into Gold': From China's First Independently Developed Pressurized Coal Gasification Furnace to the Transformation to Zero-Carbon and Negative-Carbon Technology

Fertilizer is the 'food' of grains. Affected by the international crude oil and natural gas supply situation, at the beginning of this year, many countries around the world continuously faced the urgent situation of 'applying available fertilizer' during the spring plowing season, sounding the alarm for global food security. During the same period, prices of agricultural products such as fertilizers in China remained relatively stable and supply was sufficient. One important reason is that, unlike many countries that produce fertilizers mainly from oil and gas, China primarily uses coal to produce fertilizers, and decades ago it had already planned the development of coal chemical technology and industry.

It's not just fertilizers—coal chemical products, from small mineral water bottles to large car tires and bumpers, have penetrated all aspects of production and daily life. How can coal be transformed into countless forms? Coal gasification technology and equipment are known as the 'magician turning coal into gold'; it can 'break down' coal into the 'universal raw materials' for all coal chemical products—carbon monoxide and hydrogen.

The characteristics of China's energy structure are abundant coal, scarce oil, and limited gas. Achieving clean and efficient use of coal resources is not only necessary for industrial development but also concerns national energy security. In 2004, the State Council approved the "Medium- and Long-Term Energy Development Plan (2004-2020)" (draft), which for the first time included large-scale coal gasification technology as a national strategic priority. The following year, a group of aerospace engineers who had been researching rocket engines resolutely embarked on a path of cross-disciplinary transformation.

Some of the professional fundamentals of rocket engines are consistent with those of the coal gasification field. Jiang Congbin, Chairman of Aerospace Changzheng Chemical Engineering Co., Ltd. (hereinafter referred to as 'Aerospace Engineering Company'), recalled that at the time, advanced clean coal gasification technology was monopolized abroad, and equipment such as pulverized coal gasifiers and special valves all relied on imports, which were expensive and had poor after-sales service. 'It was unpleasant to be dependent on others.' After more than three years of relentless effort, the first aerospace furnace developed by Aerospace Engineering Company (HT-L pulverized coal pressurized gasifier) successfully ignited coal at the feed point, becoming the first domestically independently developed pulverized coal pressurized gasifier in China. In the nearly 20 years that followed, Aerospace Engineering Company successively developed 1,000-ton, 2,000-ton, 3,000-ton, and 4,000-ton gasification units, with a carbon conversion rate exceeding 99%, gradually growing into the leading force in China’s coal gasification technology and industry.

When talking about the 'secret' to success, Jiang Congbin introduced that from the very beginning, the company has adhered to an innovative model of 'mechanism research and pilot testing.' One aspect of this is conducting coal quality mechanism research, which to date has covered over 500 types of coal samples. China has a wide distribution of coal resources and many varieties. Different types of coal react differently in a gasifier, so to fully 'extract' the potential of various coals, it is necessary to thoroughly study the 'food' fed into the furnace. Technological advancements combined with breakthroughs in coal quality mechanism research have given the aerospace furnace an excellent 'appetite.' Even low-quality coal, such as lignite and high-ash, high-sulfur, high-phosphorus coal, can be 'digested' without issue, allowing coal chemical enterprises to use local coal and significantly reduce transportation and procurement costs. Additionally, the aerospace furnace is equipped with an 'intelligent nutritionist' — intelligent coal blending technology — which can automatically calculate the optimal configuration based on coal inventory, quickly 'prepare meals,' improve operational efficiency, and ensure the aerospace furnace can operate stably for extended periods.

When the gasifier operates and the internal temperature exceeds 1400℃, how to maintain the furnace running efficiently for a long time under safe and stable conditions, the aerospace furnace has overcome two important hurdles. The first hurdle was developing a reliable burner. The burner is the "throat" of the aerospace furnace, where coal powder and oxygen are sprayed into the fiery interior of the furnace. It is the core component that undergoes the "trial by fire" first and directly determines the operational status of the entire system. Jiang Congbin said that initially the team tried to transplant rocket nozzle technology onto the gasifier burner, but it was burnt out within a few days. After a series of technical breakthroughs, they finally succeeded.

The second hurdle is to weave an 'armor' that can automatically repair itself: traditional gasification furnaces mostly use refractory brick walls, which are prone to damage under long-term high-temperature erosion, affecting the continuous operation of the device. The aerospace furnace innovatively uses a membrane water-cooled wall structure. Its surface refractory materials can withstand temperatures of 400°C, while the internal temperature of the furnace exceeds 1400°C. The team cleverly applied the 'fighting slag with slag' principle, using water cooling to allow the high-temperature molten ash in the coal to evenly adhere to the furnace wall surface, forming a dense and stable protective slag layer. This isolates the high-temperature flame from the metal structure of the furnace body, significantly reducing high-temperature erosion losses.

From a 1,000-ton level to a 4,000-ton level iteration upgrade, from a single coal type to all-coal application, from conventional gasification to semi-waste and full-waste furnace technology breakthroughs, the aerospace furnace has continuously broken the records for uninterrupted operation, with the longest duration reaching 763 days, far exceeding the industry average. Jiang Congbin stated that currently the aerospace furnace has achieved a yearly planned shutdown once a year, with accidental shutdowns basically disappearing. Aerospace Engineering Company is attempting to introduce intelligent control and other technologies, striving to achieve the goal of 'one shutdown per year, one maintenance every three years.'

In 2020, at the moment when the "dual carbon" goals were proposed, Aerospace Engineering Company began to diversify a series of technologies from the aerospace furnace to adapt to the new market demands. Jiang Congbin believes that "researchers working on applied technologies must be close to the market," innovation is the best marketing, and the source of technological progress is market demand. Facing the reality that landfilling or open-air disposal poses enormous environmental pressure and that waste incineration for power generation faces significant market pressure after the tapering of policy subsidies, the company, based on aerospace furnace technology, has developed a full-chain biomass gasification technology to convert biomass into chemical raw materials or green fuel. He gave an example: using Aerospace Engineering Company's waste gasification technology, a certain international airport in China could synthesize green aviation kerosene that meets standards from its own waste, which would both meet the rigid demand for green fuel from international flights and reduce waste emissions.

Nowadays, aerospace engineering companies are comprehensively expanding non-fossil energy technology routes, breaking through zero-carbon and negative-carbon technologies such as water electrolysis hydrogen production, biomass gasification, solid waste molten gasification, and industrial waste salt disposal, and achieving industrial applications. At the same time, they are promoting the advancement of core high-end equipment into new fields such as petrochemicals, the nuclear industry, and green hydrogen, embarking on a path of green transformation.

[Source: Guangming Daily]

[Editor: Xiao Neng]