Performance comparison of the HT-L powder coal gasification process with advanced gasification technologies in the world today

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I. Technical characteristics of the HT-L powder coal gasification unit
Technical characteristics of the powder coal gasification unit:
– Dry coal powder feed: coal powder particles with a size of 20 to 90 microns;
– Inert gas for transportation: nitrogen or carbon dioxide;
– High-pressure gasification furnace: 2.0–4.0 MPaA.
Advantages:
1. High gasification efficiency due to dry coal powder feeding; strict control over the moisture content of the fed coal powder. Compared with the wet method, 1 Kg of water-coal slurry can reduce evaporation by 0.35 Kg of water, saving approximately 2600 KJ of energy, which is equivalent to 0.113 Kg of standard coal (5500 kcal/Kg), accounting for 17% of the total coal input. Powder coal gasification compared to water coal slurry gasification: cold gas efficiency increases by 10%, while oxygen consumption decreases by 15–25%. Effective gas production increased by 6%. ⒉The advanced and mature dense-phase transport technology for dry coal powder features a suspension speed of 7 to 10 m/s, a solid-gas ratio of 480 Kg/m3, and low carrier gas usage. ⒊Enhanced combustion increases the gas production rate per unit volume; the high gasification efficiency means that, at the same production capacity, compared to atmospheric-pressure furnaces, it requires smaller equipment dimensions, has a more compact structure, occupies less space, and offers improved combustion efficiency. Allowable operating temperature of the gasification furnace: 1400 ~ 1900°C. Advantages: 1. Wide range of coal types that can be used; a wide range of ash fusion points for coal (1250 ~ 1650°C), as well as a wide range of raw materials that can be used for gasification ； ⒉High carbon conversion rate and good quality of the crude syngas: the designed value for carbon conversion rate is ≥99.5% with low CH4 content; the volume of effective gases (CO+H2) in the outlet syngas is ≥90%, while the CH4 volume is ≤130 PPm. ⒊Increasing the reaction rate can shorten the reaction residence time; high temperature and high pressure increase the reaction rate. Compared to the water-coal slurry gasification process, it is easier to reach an equilibrium state. The average residence time in the furnace is 10 S. ⒋Combustion of dry coal powder in pure oxygen raises the temperature at the center of the flame; the center temperature of the flame in a short-flame burner is 1800–2150°C. Advantages of the single burner top-firing combined burner: 1. The combustion flame, the material flow pattern within the furnace, and the furnace structure are well matched; the distribution of the coal powder pyrolysis zone, flame combustion zone, flue gas jet zone, flue gas recirculation zone, and secondary reaction zone within the furnace is reasonable. The reaction residence time meets the requirements for gasification. 2. The combustion load has a wide adjustment range: 60%–120%. 3. The burner is designed reasonably and exhibits good combustion performance; the central oxygen mixes thoroughly with the swirl coal powder, ensuring complete combustion of the coal powder ； Good flame shape and stability ； ⒋It is easy to install, debug, and maintain. It integrates a high-energy electric ignition device, a liquefied gas (diesel) ignition nozzle, and a flame detector, features an independent external cooling water coil, and is convenient for disassembly, assembly, and maintenance. ⒌Advanced manufacturing processes are employed, with key materials being imported or specially manufactured domestic materials of equivalent quality. Welding and assembly procedures are carried out strictly in accordance with relevant standards, and overall heat treatment is used to eliminate thermal stress. ⒍The designed service life of the burner is **extended**; the water-cooled jacket design for the burner ensures its stable and reliable operation over extended periods of time. The design life is 20 years, with local maintenance of the burner head required every 6 months. Closed-coil water-cooled wall radiation chamber structure, with a design life of 20 years. Advantages: 1. Uniform water flow distribution – the “four inlets and four outlets” design ensures even flow resistance across the tubes. ⒉Control the vaporization rate of water in the coil, adjust the vaporization rate for thermal balance inside the furnace to 6.5%, with a steam output of ~22,000 Kg/H (at full load). ⒊The length of a single straight pipe with few coiled pipe weld joints can reach 12 meters. ⒋The axial thermal expansion of the coil is small; thermal stress analysis of the coil shows that the radial thermal expansion is 6 mm. ⒌Multiple sets of cooling water coils facilitate the maintenance and replacement of the burner coils; the slag outlet coils receive water separately, making them easy to adjust and replace. ⒍ The manufacturing process is well-developed, with specialized production lines for the hot bending, welding, assembly, and inspection of these coils. “\"Self-healing\" refractory material structure with reduced maintenance requirements: 1. The \"self-healing\" refractory material structure increases the service life of the materials; a stable layer of solid slag 3–5 mm thick can form outside the water-cooled walls, allowing the slag to protect against the erosion and wear caused by gases and molten slag. 2. The water-cooled walls help reduce the rate of erosion of the refractory materials, ensuring that the operating temperature of SiC materials remains below 1400°C and thus maintaining their high-temperature strength. 3. The combined structure of the refractory materials reduces heat loss from the furnace; inside the furnace, there is successively liquid slag, solid slag, SiC refractory materials, water-cooled walls, an inert gas protection layer, high-alumina unshaped refractory materials, and an outer insulation layer, resulting in minimal heat loss. 4. The refractory materials used have low porosity, high high-temperature strength, and good thermal stability. The maximum particle size of the unshaped refractory materials is less than 4 mm, with a high-temperature compressive strength of ≥85 N/mm² and a permanent thermal deformation of ≤0.73%, thanks to an effective design of their structural layout. 5. The refractory materials are easy to install, maintain, and replace, and they are also inexpensive. Quenching and water-bath cooling schemes for syngas offer good reliability: 1. The technical approach is mature and reliable; the Texaco process is well-established, and the results of theoretical analysis and simulation calculations match reality quite well. ⒉There is mature engineering experience and analytical data related to the quenching ring, as well as long-term research on its structure, which has led to the development of unique quenching ring technologies. ⒊Quenching of syngas significantly reduces its flow rate; maintaining a liquid film thickness helps with quenching. ⒋The effects of slag and ash removal are significant; the water bath ratio is more effective than spraying or gas cooling for removing the solid phases in syngas. 5. The saturated water present in the syngas can be used directly in the shift reaction process. Advantages include: 1. Both the efficiency of cold gas production and thermal efficiency are higher than those of the wet process. By controlling the water content in the coal powder feed, energy consumption is reduced; the efficiency of cold gas production is 10% higher than that of the wet process, while thermal efficiency is increased by 6%. 2. High-temperature gasification results in a higher carbon conversion rate compared to the wet process – the carbon conversion rate is ≥99.5%, which is 1% higher than that of the wet process, and this leads to reduced solid residue emissions. 3. Oxygen combustion reduces air emission losses compared to normal-pressure furnaces; the thermal efficiency under normal operating conditions is at least 95%. 4. The cooling water used in the coiled tubes generates medium-pressure steam, allowing for the recovery of 3–5% of the heat generated during combustion. 5. By controlling the amount of nitrogen entering the furnace, NOx emissions can be reduced. The solid-to-gas ratio can reach 12:1, resulting in less carrier gas being needed. 6. The wastewater contains very few harmful substances, and it can be discharged directly after biochemical treatment ； The solid residue is completely captured; it can be used as building material or buried deep, causing no further environmental pollution. Advantages of long continuous operation time and strong production adjustment capability: 1. A mature technological process is adopted, which makes full use of existing coal chemical processing technologies as well as proven techniques for pulverized coal boilers; this facilitates the establishment of the production process, thereby reducing investment risks and development timelines ； ⒉The key equipment boasts a large number of successful engineering applications; the burners, combustion devices, and water-cooled walls manufactured by the professional company Texaco have been localized for domestic use and are also employed in other similar industrial products, ensuring consistent product quality. 3. Coal-fired burners have a long service life – the cooling conditions at the burner tip are better than those in Texaco furnaces, and the cooling coils help reduce the local temperature at the burner tip, thereby extending the lifespan of the materials used. 4. Coal-fired burners are easy to replace and maintain. 5. Furnace operation is simpler compared to Shell furnaces; the ignition process, combustion load adjustment, and control systems for single burners are all more efficient than those in multi-burner systems. 6. The water-cooled walls extend the lifespan of refractory materials and make their replacement and maintenance easier. The technical advantages of the HT-L coal gasification process include high-temperature gasification, which results in high efficiency and energy savings. High carbon conversion rate (≥99%), high cold gas efficiency (≥82%), effective gas composition (≥90%); wide range of applicable coal types, possible use of diverse fuels, and the possibility of using locally sourced coal ； 􀁺 The control system features a high degree of automation and a comprehensive security interlock system; it has excellent environmental performance with low levels of pollutant emissions; it possesses independent intellectual property rights, its technology is mature and reliable, and all the key equipment is domestically produced ； Comparison of the HT-L powder coal gasification process with advanced gasification technologies in the world today

| Parameter | HT–L | Shell Texaco GSP |
|-----------|------|-----------------|
| Oxygen consumption (Nm3/KNm3) | 330–360 | 330–360 | 410–430 | 330–360 |
| Effective gas composition (CO+H2, %) | 89–91 | 89–93 | 78–81 | 89–91 |
| Carbon conversion rate (%): >99 | >99 | >98 | >99 |
| Cold gas efficiency (%) | 80–83 | 80–83 | 71–76 | 80–83 |
| Heat efficiency of coal gasification (%) | ~95 | 96–86 | ~90 |

**Form of raw coal transportation:** Dry powder, gas transportation; Dry powder, gas transportation; Slurry, pump-driven; Dry powder, gas transportation.

**Burner lifespan:** 10 years, with head maintenance every 6 months; 10 years, with head maintenance every 1.5 years; Head maintenance every 1.5 months; 10 years, with head maintenance every 6 months.

**Lifespan of water-cooled walls or refractory bricks:** The water-cooled wall has a simple structure, being of the cylindrical coil type; its water circuit is simple, making it easy to manufacture, with a lifespan of >10 years, and it produces medium-pressure saturated steam as a by-product. The water-cooled wall consists of multiple vertical tubes, resulting in a complex water circuit; it is made of alloy steel, making it difficult to manufacture, with a lifespan of >10 years, and it produces medium-pressure saturated steam and superheated steam as by-products. Expensive refractory bricks can only be used for one year and do not produce steam. The water-cooled wall has a simple structure, being of the cylindrical coil type; its water circuit is simple, making it easy to manufacture, with a lifespan of >10 years, but it only produces low-pressure steam as a by-product.

**Adaptability to different types of raw coal:** The HT-L process can handle almost all types of coal, from lignite to anthracite, allowing for local sourcing of raw coal. It can also handle almost all types of coal from lignite to anthracite, enabling local sourcing of raw coal. High requirements are imposed on the type of coal used (ash melting point below 1250 degrees, good slurry-forming properties); local sourcing of raw coal is not possible. The HT-L process can handle almost all types of coal from lignite to anthracite, allowing for local sourcing of raw coal.

**Electric power consumption:** Low. Due to the need for quenching air compressors and backflow air compressors, electric power consumption is relatively high.