1. technical name

Low-rank coal regenerative downcomer rapid pyrolysis process

2. scope of application

The coal processing and cogeneration industries conduct clean and efficient pyrolysis and utilization of low-rank coal with high volatile content (mainly lignite and low-grade bituminous coal).

3. technical content

3.1 technical principle

The core heating element regenerative radiant tubes are used to couple with the descending bed to form a regenerative descending bed rapid pyrolysis reactor. There is no rotating equipment in the furnace, and the system operation is reliable; the radiant tubes arranged in a staggered manner in the furnace can realize strong mixing and rapid heat transfer of materials, and achieve rapid pyrolysis of middle and low-level pulverized coal below 6mm within 6 seconds to 9 seconds; The temperature field in the furnace can be flexibly controlled within the range of 500℃~ 950℃. The oil and gas quality is high, and the volatile extraction rate, energy conversion efficiency and system thermal efficiency are high; the modular combination process is adopted, which is easy to project scale-up, and the scale of a single pyrolysis furnace can reach 1.2 million tons/a; for thermal power generation, boiler efficiency can be improved and coal consumption for power generation can be reduced.

3.2 main innovations

(1) The "Low-rank Coal Regenerative Downflow Bed Rapid Pyrolysis Process" adopts regenerative combustion-radiant tube heating technology to process low-rank pulverized coal below 6mm, solving the problem of small processing scale and internal heating pyrolysis processes in the traditional external-heat pyrolysis process. At the same time, due to the lack of rotating machinery, the system operation reliability is high; The flue gas system is isolated from the high-temperature pyrolysis oil and gas system, which is conducive to the cooling, separation and recovery of pyrolysis products. The pyrolysis gas and pyrolysis tar are of high quality; the regenerative radiant tube can utilize cheap low-calorific value fuel gas

As fuel, the exhaust gas temperature of combustion flue gas can be as low as 150 ° C, the thermal efficiency of the combustion system is greater than 93%, and the thermal efficiency of the rapid pyrolysis furnace reaches more than 88%. Using a modular combined process, a million-ton process data package has been completed. The designed rapid pyrolysis furnace has a compact overall layout and a small floor area.

(2) The temperature field of the regenerative downward-bed rapid pyrolysis furnace is adjustable in the range of 500℃ to 950℃, with a wide range of coal types, high oil and gas quality, flexible adjustment of yield, and energy conversion efficiency of more than 82%.

4. Energy conservation and greenhouse gas emission reduction effects

(1) Compared with traditional coking process: Taking the single-series 1.2 million t/a Chifeng Daban Project in Inner Mongolia as an example, the comprehensive energy consumption of rapid pyrolysis is 90.69kgce/t, which is lower than that of existing steel companies and independent coking enterprises or the comprehensive energy consumption value of newly built/expanded coke production equipment. Compared with the comprehensive energy consumption of newly built coke production equipment of 91.5 kgce/t, using the regenerative downcomer rapid pyrolysis process can save 972 tons of standard coal every year, equivalent to reducing carbon dioxide emissions by 2390 tons.

(2) Comparison of traditional thermal power generation processes: Taking Jiangxi Jiangneng Shenwu Pingxiang Coal, Electricity and Oil Polygeneration Project as an example for calculation and comparison, the construction scale of the project is a 2× 1 million tons fast pyrolysis coupled 2×660MW pulverized coal boiler. The boiler fuel uses 45% pyrolysis semi-coke +55% Pingxiang raw coal. After the boiler burns the mixed fuel, the boiler efficiency is increased by 0.75%(A rough calculation can reduce the power supply coal consumption by 2.34g, estimated based on the national power supply coal consumption of 312g/ kW·h in 2016.) If the sensible heat recovery of high-temperature hot semi-coke is further considered, the average heat delivery temperature of pyrolysis semi-coke is calculated at 400℃, the power supply coal consumption can be reduced by 2.66g/ kW·h, and the power supply coal consumption can be reduced by 5 g standard coal/kW·h in total. Based on the annual utilization of 5500 hours, 34485 tons of standard coal can be saved every year, equivalent to reducing carbon dioxide emissions by 84795 tons, and the carbon trading income is 4.8681 million yuan. After being upgraded by pyrolysis, medium and low-rank coal is upgraded at high temperatures

Coal can be used as a clean fuel for boilers instead of thermal coal and directly burned in boilers, with significant economic and environmental benefits.

5. Technology demonstration

The 700,000 t/a ethylene glycol cascade utilization project of coal quality in Baarin Right Banner, Inner Mongolia is located in the Daban Industrial Park of Baarin Right Banner, Chifeng City, Inner Mongolia. Project scale: 3× 1.2 million t/a coal rapid pyrolysis unit, 2×750t/d water-coke slurry gasification unit, 700,000 t/a ethylene glycol unit, and at the same time, a 4×670t/h circulating fluidized bed boiler +3 × 60MW back-pressure turbo-generator set power station, as well as supporting public works and auxiliary facilities, storage and transportation facilities, environmental protection facilities, production facilities and front area of the plant for the project.

6. investment estimation

Taking the single-series 1.2 million t/a Chifeng Daban Project in Inner Mongolia as an example, it is estimated that the investment in key equipment is 158 million yuan, and the operation and maintenance cost is 35,000 yuan/year.

7. investment recovery period

Taking the rapid pyrolysis of low-rank coal regenerative downer in a single series of 1.2 million t/a Chifeng Daban Project in Inner Mongolia as an example, the total investment of the project is 559.56 million yuan, the financial internal rate of return after tax is 14.37%, and the project investment income tax net present value is 61.88 million yuan, the loan repayment period is 4.41 years (excluding the construction period), and the static investment payback period is 5.83 years (excluding the construction period). The total investment return rate is 12.42%, the profitability of the project meets industry requirements, and the project has good economic benefits.

8. Prospects for transformation and promotion of technological achievements

Currently, more than 90% of my country's low-grade coal is used for direct combustion of power generation, industrial boilers and civil fuels, which causes a series of serious ecological and environmental pollution problems and wastes the oil, gas and chemicals contained in low-grade coal. Resources. The pulverized coal pyrolysis coupled power generation and polygeneration technology route can maximize the utilization of low-rank coal resources and is an important way to achieve clean and efficient utilization of low-rank coal in classification and quality.