PRODUCTION OF LIQUID FUEL AND COKE FROM LONG – FLAMED, FIERY AND HARD COALS WITH UTILISED POLYETHENE
Today’s scientists estimate the world oil stocks on the level of 100 – 120 milliard tons, which will run out in about 70 years. In the same time the world stock of coals is more than 100 trillion tons, and will not run out for more than 500 years. Due to the above, analytics consider coals as the future of energetics, and the relevance of modern technology for transforming coals into liquid and gaseous fuels in more than ever.
In beginning of the twentieth century the method of “gasification of coal”, by an incomplete oxidation of coal by air in an isolated reactor with reception of so-called
“generating gas” was developed. This gas consists of carbonic oxide and nitrogen, and has been industrially mastered. The caloric content of such gas is quite low. Then water was added to the air and “water gas” was received, with structure of 27,5 % of carbonic oxide, 9,5 % of hydrogen, 4 % of carbonic gas and 59 % of nitrogen. The method requires a process of periodical cleaning of the reactor from slag and still inherits the low thermal ability of the gas. In recent years it became possible to lift the temperature in the reactors up to 800C and to receive slag in a liquid form, which facilitates the unloading of a reactor, however there were difficulties with loading of coals into the reactor which is under pressure up to 700ATM. Now the majority of power stations in the USA, Canada and the Europe burn preliminary gasificated coals – then emissions to the atmosphere contain less ashes, and slag – less unburned coals. Nevertheless, gasification of coals does not solve the basic problem – manufacture of fuel for transport.
The most perspective direction in coal gasification is the method of heating young coals with donors of hydrogen to temperatures above 450C at atmospheric pressure. Using special solvents provides conditions for carrying out the process and an output of the liquid products practically identical to natural oil. Also in this process gas is produced, suitable for comprimation and use on transport. Moreover, this process produces coke. An output of coke from young coals is 50-55 %, oil of 35 % and 10%-15% of gas. A furnace of an original design allows using bad quality – cheap coals, provides high efficiency – 100 thousand tons a year, and most importantly – quality of products and profitability of manufacture. Coke is suitable for domain production.
Ukraine extracts about 150 million tons of different marks of coals and still imports 5 milliontons of coked coals annually. If a part of power coals would be directed to preliminary processing using the above-stated method, it would be possible to get from the above – 20 million tons oil and 45 billion cubes of gas (in recalculation to natural), which is enough the needs of the country. Germany, Great Britain, USA, Canada and other countries also have coal resources for maintenance that could render them independent on oil import.
On the other hand, in recent years the world has become flooded with polyethylene products, mainly plastic bags and bottles. This problem is currently being addressed in almost every country, and with little success. The main problem in polyethylene recycling is the inability of burning. If one attempts to burn such products, numerous toxic gasses would be released into the atmosphere.
Attempts to use pyrolysis techniques on polyethylene have been made, a method that would allow capturing the toxic gasses, however, these were also unsuccessful due to uncontrollable reactions that occurred in the pyrolysis chamber. Several attempts ended in explosions.
Now days, governments force the coke manufacturers to use polyethylene in furnaces. This process does get rid of part of polyethylene products, but in the same time it damages the quality of produced coke.
The above method of coal gasification uses a special solvent produced from polyethylene. This solvent, not only gets rid of the polyethylene products, but in the same time increases the percentage of young coals in coke production.
At this time an industrial scale prototype of the technology was constructed by our company. The prototype produces small quantities of powder, which than are used in cock production of small scales.
Tests that were carried out in chemical laboratories show that the produced powered – solvent increases the level of produced cock by several present. The powder may be produced from almost any type of plastic and polyethylene.
Conclusions based on the results of testing the polymer solvent, produced from polymer wastes that were carrying out in the Ukrainian Institute of Coal Chemistry are as follows:
1. The polymeric solvents decrease the content of sulfur in coke by 0,17 – 0,19 absolute percent, which increases the price of coke.
2. 25% of solvent mass transform into coke, 75% – into volatile matter. Thus the application of the solvent to coal charge leads the production of additional quantity of coke per one ton of spent coal and an increase in liquid and gaseous products.
3. When adding up to 3% of solvent, there is no noticeable decrease in coke strength.