CLEAN COAL CONVERSION INTO COKE AND ENERGY

 

Summary  

 

This business project is based on concept of co-production of energy and scarce coke products of metallurgic purpose from cheap energetic coal by using new TERMOKOKS technology which differs with low capital and operating costs, as well as ensures high level of ecological safety.

 

Resources of coking coal in the world have been considerably exhausted and their cost is growing steadily. It is unlikely that coke production would increase considerably in the world, because conventional plants need for significant investments and are ecologically dangerous. Especial characteristics of TERMOKOKS technology are utilization of non-coking coal, which was unavailable before in other methods of coke production, ecological safety and economic efficiency.

 

Feedstock is coal and air, while final products are medium temperature coke and fuel gas without any tar and poisonous substances.

 

Medium temperature coke is scarce product and ecologically clean smokeless fuel for municipal usage, metallurgy and various technologies. Price of such product in the European market (Germany, Norway, Great Britain etc.) is about 150 - 200 EUR/t, if the price of coal is 50 –70 EUR/t (Jan 2006).

 

Gas can be fired in gas turbine or boiler for electric and/or heat energy production. It can be used as fuel, for instance, for brick baking, as well as hydrogen source for fuel cells. Specific dangerous emission by burning this gas is lower than by using natural gas.

 

Because of co-production of several products (coke and fuel gas) the selling of more expensive coke compensates large part of general expenses. Therefore production cost of heat energy decreases and actually becomes beyond competition as compared with energy production from any other fuels.

 

TERMOKOKS technology diversifies energy production reducing considerably dependence on oil and gas prices.

 

TERMOKOKS is the easily scaling technology.  It allows constructing and operating the plant module by module.  On the other hand, it is possible to locate a number of separate modules close to individual customers.

 

TERMOKOKS technology is adapted to the processing of different types of coal: – lignites and subbituminous coals. In this case one can regulate the output of products by changing only technological parameters.

 

Investing in TERMOKOKS technology is profitable, has low risks and excellent economic indices:

 

 

This offer is addressed to potentially interested investors from different sectors: both heat/electricity production and non-coking coal conversion.

 

Perspectives of coal utilization

 

The share of coal in the world fuel balance is 30 %, particularly in the USA this share is 50 %, in China - 70 %, in Germany – 55 %, in Japan, which lacks its own coal, – more than 20 %, in Russia with enormous coal resources – only 18 %. The share of coal in Baltic countries is even much smaller.

 

Such disproportion was formed in 60-ies because of spreading of cheap natural gas, which resources have been overvalued. All countries of Eastern Europe and former Soviet Union became strictly dependent on gas supply.

 

The significance of coal in fuel balance of the majority of countries will be increasing in 21^st century. It is caused by the growing prices for oil and gas.  No doubt, this process is irreversible.

 

One of the fundamental advantages of TERMOKOKS technology is possibility of flexible diversification both coke and energy production, which not to be dependent on supply of customary type of fuel and its cost.

Technology review

 

Coal-fired power industry is the most “dirty” in comparison with utilization of other energy sources. As for the conventional coke production, it is a real ecological “bomb”. Therefore the prior task of world energy strategy is the creation of ecologically safe coal-based technologies.

 

There are several ways of developments of such technologies (for instance, program Clean Coal in USA):

 

The reducing of emissions by investing in appropriate purification installations. This inevitably leads to increase of capital costs.

 

The decreasing of specific fuel consumption per unit of energy or product. For instance, power generation in the so-called combined systems, linking the application of steam and gas turbines or increase of steam parameters in boiler. It also leads to increase of capital costs.

 

The creation of efficient coal technologies with suppressing of emission within the technological process itself.

 

The first two directions have been developed rather significantly, while the third one has not a single pilot plant with the exception of TERMOKOKS technology, what is described in the given project.

 

TERMOKOKS is a real technological revolution in coal utilization. There are no coal-based analogies in the world practice ensuring low emission thanks to technology itself.

 

At present TERMOKOKS technology has reached the level of industrial plant and is ready for wide commercial application.

 

 

TERMOKOKS technology description 

 

TERMOKOKS technology – production of medium temperature coke from non-coking coals – is absolutely free from main imperfections of conventional technologies and manufacturing high-quality products without any considerable harm to environment.

 

 

This technology is based on autothermal method of coal heating (without external heat carrier). In fact, TERMOKOKS is a variant of air-blown coal gasification in fixed bed. In this case the volatile matter of coal is gasified mainly while the solid carbon partially.  TERMOKOKS technology is designed on the effect of “inverse thermal wave” moving along the coal bed towards air stream (Fig.1). The pyrolisys zone in conventional processes of gasification is located behind of the combustion zone; therefore decomposed volatile matter (such as soot, tar, carcinogens, phenols and other toxic substances) is necessary part of the final fuel gas.  In the case of TERMOKOKS pirolisys zone is before combustion one and therefore all pirolisys products are burnt within thermal wave up to simplest components СО, H₂, CO₂ and H₂O.

 

TERMOKOKS technology has the following principle scheme. The coal bed in vertical apparatus is ignited from the top, while the air is supplied from the bottom. After that combustion front moves down from top towards the stream. Temperature in the combustion front is about 900˚C. Behind the combustion front carbonaceous matter – medium temperature coke - remains. At the exit of device we have fuel gas containing СО, H₂, CH₄ and ballast gases such as CO₂, H₂O, N₂. In fact, gas doesn’t contain any tar, benzpyrene and other toxins.

 

Figure 1.  Scheme of “inverse thermal wave”

 

Advantages of TERMOKOKS technology

 

Technological process TERMOKOKS has a lot of advantages in comparison with already known methods of thermal coal conversion:

 

1. Energy efficiency

 

The majority of existing technologies are based on coal heating with the external heat carrier, while in technology TERMOKOKS this process is autothermal. Co-product in technology TERMOKOKS – fuel gas – can be used for heat and electricity manufacturing. According to energy balance the initial heating value of coal is divided between final products in ratio: coke – about 60%, fuel gas – about 40%. Energy efficiency of coal conversion in useful products is near 96%. Commercial efficiency of the whole project depends on possibility to sell heat energy constantly all year-round without any breaks.

 

2. Ecological safety and no wastes

 

All organic compounds in the TERMOKOKS technology are splitting inside the gasifier and final gas doesn’t contain any tar substances. Since to low velocity of filtration small solid particles are not taken out from the bed, so gasifier works as grain filter.  Fuel gas is supplied into boiler or gas turbine without any preliminary purification. In this case specific emissions (NO_x, SO_x, CO and dust) are much lower in comparison with conventional coal-fired boiler or power station. They are two orders lower than in conventional coke production plant.

 

TERMOKOKS does not use any water for the coke cooling. Therefore this technology has no waste water with tar, phenols and other poisonous substances like in conventional coke production.

 

 TERMOKOKS has no such pollution as worked out heat carrier (flue gases). Therefore it does not need any flue gas purification systems. 

 

3. Simplicity of equipment and  advantage of one stage processing

 

Stages of drying, pyrolysis, thermal decomposition of volatile substances and cooling of final coke are combined in one apparatus. Therefore specific capital costs are lower than in any other technologies.

 

4. Mobility of technological equipment

 

For example, the cycle of leading out coke battery to stationary regime is 2-3 weeks, for TERMOKOKS gasifiers – about 1 hour.                       

 

5.       Flexibility of technology

 

TERMOKOKS technology allows to convert different coals (basically used for power production) into scarce products, as well as, changing only technological parameters, to regulate the quality of final products depending on requirements of consumers (to produce medium temperature coke or sorbent, to

Increase output of fuel gas etc.

 

 

6. Reliability of equipment

 

The major apparatus of TERMOKOKS technology (gasifier, gas-fired boiler) have no moving or rotating parts as in conventional coal-used technologies. That increases the reliability of operation.

 

 

7. Possibility of  TERMOKOKS technology application in separate small scale blocks

 

 

 

Figure 2.  Energy balance of technological process

 

 

 

 

Figure 3.  TERMOKOKS gasifiers in operating plant

 

Characteristics of main products

 

The major and the most expensive product TERMOKOKS technology is medium temperature coke. This coke is not absolute substitute of classic coke obtained from coking coal. But it can be used in large market segment and has large demand.

Cost of energy generated by burning it is much lower than in any conventional method of energy production due to compensation of large part of expenses by coke selling.

In TERMOKOKS technology any non-caking coals can be used and a wide range of carbonaceous products can be manufactured: medium temperature coke, smokeless fuel for boilers, sorbents (active carbon), coal-based ionitesand carburizers.

 

 

Figure 4.  Range of TERMOKOKS technology products

 

 

 

                       

Medium temperature coke

 

Medium temperature coke is a hard, carbonaceous material manufactured from coal by thermal treatment at temperature 1000 - 1200 K. It is characterized by low volatile content (V^daf less than 6 %), high caloric value (more than 27 MJ/kg), high reactivity and low electric conductivity.

 

This coke can be used as the metallurgical fuel (excepting the blast-furnace production, where there is the need for high strength lump coke and therefore the classic coke is used), agglomerative and technological fuel, carburizer, adsorbent, smokeless fuel for house heating, component for conventional coke production etc.

 

The most perspective is of medium temperature coke with low content of sulphur, phosphorus and other poisonous substances. It can be used in electrometallurgy (production of silicon, ferro-alloys, phosphorus etc.), where high reactivity and high electric resistance is important.

 

There is a stable interest for medium temperature coke as fuel for power generation in developed countries, since poisonous emissions significantly decrease by burning it. In some publications medium temperature coke is called as “solid natural gas”, “fuel of future” etc.

 

The wide utilization of medium temperature coke is restricted by the lack of ecologically safe technologies of its manufacturing. The attempts to adapt the conventional plants to present-day environment regulations turned out to be of low efficiency. The reason is large the large capital extra-costs for gas and water purification units.

 

TERMOKOKS technology is ecologically safe and there is no special need for any additional investments in nature preservation.

Basic qualitative indices of medium temperature coal coke:

 

Medium temperature lignite coke

It can be utilized in electrometallurgy and environmental technologies. At present medium temperature lignite coke (as adsorbent) is used for preparation and purification of natural, waste and return water from oils, dissolved organic matters and heavy metals, advanced treatment of drinking water, as well as for purification of aspiration emission, steam and gas. At present lignite coke ABG (trade-mark in Russia) is supplied to many enterprises in Russia and for export. The largest consumers are RAO “United energy systems of Russia”, GMK “Norilsk Nickel”, factories for refuse utilization and water treatment plants.

 

Basic qualitative indices of medium temperature lignite coke:

Some special properties of lignite coke are differing from classic and medium temperature coke ones. And it is favorable for a lot of technological processes:

ü       High reactivity due unformed lattice in lignite coke and high specific surface;

ü       High adsorption activity;

ü       Low content of phosphorous, sulphur and other poisonous substances.

 

Fuel gas

 

In TERMOKOKS process the volatile substances of raw coal are gasified converting in fuel gas. 1 ton of raw coal is generating approximately 1400-1800 Nm³ of fuel gas with heating value in the range of 700-1000 Kcal/ Nm³ depending on the regime of thermal treatment.

 

According to energy balance of the process up to 40 % of coal heating value is transformed into energy of fuel gas. Since partial gasification of coal is done on airflow basis, then basic component of this gas is nitrogen (about 50%). The combustible components are hydrogen and carbon oxide (H₂ and CO). There are also insignificant quantities of combustion products CO₂ and H₂O. There are no any hydrocarbons, except small addition of methane. Content of hydrogen sulphide (H₂S) depends on the presence of sulphur in raw coal. 

 

Approximate composition of dry gas:

 

 

Heating value of raw gas is about 3, 5 MJ/m³, dry gas - 4 MJ/m³.

 

Fuel gas at the exit of gasifier has temperature up to 300^оС. Due to low velocity of filtration it does not contain volatile ash and dust, so coal bed works as grain filter. Fuel gas without any purification can be burnt in gas turbine or boiler.

 

 

Gas from coal can be used not only for energy production. It is valuable technological fuel and chemical feedstock for many technological processes:

 

ü       Single-stage methanol synthesis with following energetic use of unconverted gas.

ü       Gas for direct reduction of iron and other metals.

ü       Fuel gas for brick backing, for agglomeration processes, for roasting of cement, limestone, alumina and other ores.

ü       Production of hydrogen (gas contains about 20–25% of H₂) as perspective energy carrier in nearest future. It can be used in fuel cell for direct electricity manufacturing and in internal combustion engines for automobiles.

 

The conception of “hydrogen energetics” is based on hydrogen producing by water electrolysis or reforming of hydrocarbons. The first method is energy ineffective, the second – oriented on raw materials of limited resources and which price is will be growing irreversibly. The great problem of “hydrogen energetics” is the lack of cheap hydrogen in large volumes.

 

TERMOKOKS technology can provide the cheapest source of hydrogen with practically unlimited feedstock, based on enormous resources of coal.

 

Heat and electric energy

 

The profit of heat and electricity production depends on price of raw fuel. On other hand, the selling price of energy is limited by paying capacity of customers.

TERMOKOKS technology significantly reduces the cost of energy products, providing the cheapest fuel gas.  In this case the energy producer will be low depending on prices of gas and oil.

 

While prices of oil and natural gas are growing, price of coal lately has even decreased. At least, the price of coal is growing much slower than prices of natural gas and oil.

 

Figure 5. Scheme of co-production of medium temperature coke and heat energy

 

 

 

 

Figure 6. Scheme of combined production of medium temperature coke production,

heat and electricity (boiler + steam turbine)

 

 

In TERMOKOKS technology net efficiency of gasification (relation between heating values of fuel gas and raw coal) is controlled parameter.

It can vary from 0, 3 in coke production regime up to 0, 8 in full gasification regime.

 

 

Market analysis of products and perspectives

 

Ferrous metallurgy in whole world shows significant increase of production. Main coke supplier and consumer in the world – China – reduces coke supplies to world market because of rapid development of its own industry.

 

In many regions, including Russia, resources of more valuable types of coking coal are running out. The price of coking coal is increasing even more than oil price. Several years ago price of coking coal was around 50 EUR/t, while at present - more than 100 EUR/t.

The average price of different cokes in Russia and in foreign countries has increased 3 times – from 70-120 up to 300-350 EUR/t in 2004. This tendency will be stable up to 2010 when the operational resource of many coking batteries will be worked out.

 

TERMOKOKS technology is continuously developing. The nearest goal is the manufacturing of foundry and metallurgical coke. Their market price is much higher.

 

Consumers of TERMOKOKS technology products can be divided into several groups:

 

Group A – Consumers which are ready to prefer medium temperature coke to a using fuel. This is because of its high reactivity and high electric resistance. Such coke is improving the economic efficiency of whole process. This group is presented by the plants of electro-metallurgy (mainly ferrous metallurgy).

 

Group B – Consumers using medium temperature coke in conditions of deficit and expensiveness of classic coke and high quality coal.

 

Group C – Consumers using the medium temperature coke:

ü       Enterprises of ferrous metallurgy for direct blowing into blast-furnaces;

ü       The processes of roasting different raw material (limestone, alumina), agglomeration of ores, cement production etc.;

ü       Enterprises requiring technological fuel with high heating value, small volatile content and poisonous substances –sulphur, phosphorous etc.

 

Group D – Consumers requiring ecologically safe and cheap heat and electricity manufacturing from low-grade coals.

ü       Boilers and power stations;

ü       Enterprises consuming lot of heat energy: city house heating, ports, green houses etc.

 

Group D – Consumers and enterprises requiring cheap hydrogen. This is very fast increasing sector.

      At present there are two industrial methods of hydrogen producing:

ü       Water electrolysis (the most expensive one).

ü       Conversion of natural gas on catalysts. It is also expensive method, due to high price of feedstock.

 

The co-generation effect of TERMOKOKS technology allows obtaining the critically cheap feedstock for hydrogen manufacturing.  Therefore in this case the H₂-cost will be the lowest among all present-day technologies.

 

There are various long time ago developed technologies for bacteria cultivation on hydrogen (fodder protein producing etc.). During last years the bio-decomposing polymers manufacture technology based on hydrogen bacteria have been developing. The humanity is needed it very much to stop the pollution of environment by polyethylene bags. At present these technologies have rather low economic efficiency due to high price of hydrogen, obtaining by abovementioned methods.

 

The TERMOKOKS-products are potentially in great demand abroad.

 

Market of medium temperature coke only in CIS countries is valued more than 5 million ton a year. And this demand does not depend on seasonality and is regular all the year round.

 

After the merging of Germany in 90-s the factories of medium temperature coking in Eastern Germany were closed due to ecological reasons. Eastern Germany was the basic supplier of carbonaceous reducers in Europe. At present the metallurgic enterprises of Germany, Switzerland, Norway and Great Britain are in deficit of high reactivity reducers. Only Norway demand is more than 300 thousands tons a year.

 

Therefore there are favorable conditions for large-scale application of TERMOKOKS technology at present:

 

There is the crucial deficit of high-quality carbonaceous materials, primarily, in electro-metallurgy – production of ferroalloys, silicon and steel-foundry.  This is because of operation stop of large coking enterprises in Russia and Eastern Germany in 90-s. The reasons were in physical wear of rather old equipment. Medium temperature coking furnaces in Germany were constructed in 30-40-ties. Some of them were moved out from Germany in Russia after the Second World War by reparation. The coke production in these furnaces everywhere was finished due to wear and ecological danger.

 

The deficit of metallurgical coke stimulates increasing of its price. In last two years the average price of different cokes in world market has increased several times. This tendency will grow because of the following reasons:

1.             Physical wear of many European and Russian coking batteries.

2.             Resources of more valuable types of coking coal are decreasing substantially.

3.             China (the largest participant in coke market) has increased its own coke consumption and is decreasing the export quotas.

 

 

Description of process and choice of site for the plant

 

Choice of site for the plant

 

By choosing the place for the plant disposition it is necessary to take into account the existence of closely disposed consumers of fuel gas or heat energy. These products can not be delivered for a long distance due to economic reasons.

 

The plant needs a territory about 2 ha taking into account disposition of buildings of gasificator blocks, air-blast station, coke storehouse and transportation galleries, internal auto roads for servicing. It is necessary to have a possibility to load the coke in railway wagons. The plant needs an electricity source with capacity about 1000 KW.

 

TERMOKOKS technology allows increasing the efficiency of capital investments by constructing the plant module by module. Each of these modules can start its operation separately not depending upon the other ones. In this case it is possible to start getting income before completing the whole plant construction.

  

Description of the process

Technological process of medium temperature coke production consists of the following steps:

ü       Receiving (unloading), preparation and feeding of the coal;

ü       Coal gasification;

ü       Coke screening;

ü       Loading of coke;

ü       Utilization of fuel gas.

 

Coal is supplied to coal storage by wagons, after that by auto transport (see figure 8) or by loader from coal storage – to coal receiving hopper (position 1). From this hopper coal is supplied to crusher (position 3) by conveyer (position 2) for crushing till (–) 50 mm and to screening unit (position 4), where the sizing in two classes (–) 10 mm и (+) 10 mm is done. Coal (-) 10 mm is feed to storing hopper (position 6) by elevator (position 5) and by auto transport moves to separate stack in coal storage for loading to consumers. Class 10-50 mm is supplied to storing hopper (position 8) by belt conveyer (position 7) for the following feeding in technological process of medium temperature coke producing. From storing hopper (position 8) coal is supplied to loading mechanism of gasifier (position 10)  by conveyer screw (position 9).

 

Crushing and screening stages are missing when using sorted coal. In this case the coal is supplied directly to storing hopper.

 

Partial coal gasification (oxidizing pyrolisys) is carried out in cylindrical apparatus (gasifiers) with the periodic operation.

 

Gasifier operates in the following way. 10-50 mm-coal is loaded into gasifier with the help of special loading equipment. The air is supplied into gasifier from the bottom. To start the process the coal bed is ignited from above by special electric device. Some time later the formed heating wave starts its moving down towards to air stream. It moves with the constant velocity, leaving behind itself the layer of hot coke.

Such coal gasification process is known as the scheme with “inverse heating wave”.

 

Figure 8. Technological scheme of medium temperature coke production