JPS5851984B2 - Heat treatment method for fine solid fuel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a comprehensive fuel processing technology, and more particularly to a method for thermally processing pulverized solid fuel.

The method of the invention comprises a transportable fuel comprising a synthetic liquid fuel;
Useful in the production of electrical power and in the production of chemical and industrial starting materials.

As a heat transfer agent for heating the fuel, a diameter of 10-121 rt heated by the fuel gas in the second chamber of the two-chamber reactor.
Methods of heat treating solid fuels using rIt corundum beads are known in the art.

In the second chamber, where a solid hot heat transfer agent is fed continuously from the top, heating of the pulverized solid fuel rises upward through a dense bed of heat transfer agent in a mixture of gas and steam, after which Steps such as drying, coking and partial gasification are carried out.

As commercial products, hot coke fines, resins and gases are obtained (A, L, Perepelitsa
et al, 'Use of Solid Heat T
Transfer Agent in Process
of Continuous Coking of I
rkutsk Field Coals (see “Field Coals”) 0 A suspended gas stream of solid fuel that is heated due to countercurrent heat moving below the hot solid heat transfer agent (sand, pellets, etc.) of larger particles that are immiscible with the solid fuel. Methods of heat treating upwardly fed solid fuels are known in the art.

Along with the solid fuel, steam is charged into the reactor, and at the same time as thermal decomposition, gasification of the coal also occurs.

The heat transfer agent is heated by a fuel gas that is immiscible with the pyrolysis and gasification products (USSR Inventor's Certificate Arashi 8249
(see 2).

This prior art method is characterized by dilution of the pyrolysis products with steam and water gases, thereby complicating the purification and utilization of the pyrolysis products and requiring the use of elaborate processing equipment. .

pre-drying the coal and heating it to 500'C with the heat of flue gas in a first pyrolysis zone to produce fine coke;
Then, feeding the fine coke to a second pyrolysis zone,
There, it was heated to 1,000 °C by a gaseous heat transfer medium to obtain the residual pyrolysis products, and then the pyrolysis products were separated for commercial production.

It is known that heat treatment of solid fuel, namely coal, including extraction as a product (USSR Inventor's Certificate A33
5267).

This prior art method is characterized by the fact that the fuel, namely the solid residue of fine coke resulting from pyrolysis and gasification, is generally used in the combustion chamber of the power plant boiler together with ash, thus eliminating harmful sulfur and nitrogen. They cause problems in the operation of power plants (boilers) by creating slag in the environment with oxides and ash particles and polluting the environment, and the yield of valuable organic products in the process is low; The product is diluted with useless contaminants.

The aim of the present invention is to increase the yield of the desired product and improve its quality, while at the same time increasing the efficiency and intensification of the heat treatment process.

Another object of the invention is to eliminate slag formation in power plant boilers and to prevent polluting the atmosphere with harmful waste gases.

The purpose is to perform drying of a pulverized solid fuel in a method for heat treating a pulverized solid fuel, which includes the steps of drying the pulverized solid fuel, performing two-stage pyrolysis of the solid fuel, and separating the produced gas-steam products. , by a portion of the heated fine coke, and at the same time further heating at least a portion of the remaining fine coke to 800-1,500° C. by gas and/or partial combustion of said fine coke, and then heating the fine coke. gas and gasification with water vapor produced by drying the fuel, then separating the resulting gasification product from fine coke and feeding this coke as a heat transfer medium to the first pyrolysis step. It is distantly related by the above-mentioned method.

The process according to the invention is characterized by high efficiency, i.e. it uses fine coke and has a high efficiency (up to 84-88
%) power e-efficiency
The advantage of the process according to the invention is also the comprehensive utilization of fuels in the chemical processes and in the production of power starting materials.

Furthermore, the method according to the invention makes it possible to use the heating capacity of the heat transfer medium rationally, so that
Process efficiency increases.

By using a solid heat transfer agent in the pyrolysis, i.e. by fine coke cooled during gasification, the reduction of heat transfer agent under mild temperature conditions, i.e. in the first step of the pyrolysis Pyrolysis can be carried out with reduced temperatures, resulting in higher yields of the most valuable liquid products obtained with rapid pyrolysis.

Due to the fact that fine coke is fed to the gasification in excess (this is related to the heat balance of the water gas reactor), the water vapor is decomposed more highly and intensely, increasing the efficiency of water gas production. do.

In order to intensify and better control the heating of the fuel and its drying steps, these steps are carried out in a superheated steam stream and a portion of the gas separated from the heated fine coke is fed to the first pyrolysis step. It is a good idea to do so.

For the purpose of process intensification and increasing the yield of valuable steam-gas products from pyrolysis, solid fuels up to 1.5
It is advisable to mill to particles of size between;
Preferably, the gas fed to the first pyrolysis step contains at most 2% by volume of free oxygen.

The method according to the invention will become clearer from the following description with reference to the accompanying drawings.

A preferred flow sheet of the method according to the invention is shown therein.

According to the drawing, fine solid fuel with a particle size not exceeding 1.5 mounds is fed from bin 1 to shaft mill 2, into which part of the fine coke resulting from pyrolysis is fed for grinding and drying. is supplied from the inlet pipe 3 via channels 4 and 5, and steam is supplied to the shaft mill through a blower 6.

The gas suspension is fed via a path 7 to a cyclone 8 in which the dry fuel is separated and the superheated steam formed from the fuel moisture is transferred by a blower 6 via a path 9 through a grid 10 to a water gas It is fed to reactor 11 and a portion to mill 2.

However, the above drying and heating operations of the fuel can be carried out without the supply of water vapor.

Said dry fuel is fed via an intermediate bin distributor 12 to a first stage pyrolyzer 13 into which a heat transfer agent, namely fine coke or a mixed (solid and gaseous) heat transfer agent, is introduced via path 14. where the fuel is 500-800
heated to a temperature of °C.

The pyrolysis products are discharged into a cyclone 15 with accompanying dusty fine coke, where the fine coke is separated and sent to intermediate bins 16 and 17, where it can then be used as a heat transfer agent in pyrolysis or commercially transported. Used as a fuel product.

The vapor-gas mixture from cyclone 15 is withdrawn via line 18 to a refining and condensing system where valuable liquid commercial products and gases are produced.

A portion of the hot fine coke from pyrolyzer 13 is routed to path 4
and the remaining part of the fine coke is sent to a second stage pyrolyzer 19, where it is fed to a gas burner 20 operated with gas supplied with air via an inlet pipe 21. is heated to a temperature of 600 to 1,100°C.

Gas from the second stage pyrolyzer 19 and bin 17 is withdrawn from the outlet pipe via the gas duct 22.

A portion of the hot fine coke from the second pyrolyzer 19 is sent to a processing combustion chamber 23 that communicates with a cyclone 24 .

It is also possible to feed only a portion of the hot coke fines from the second pyrolyzer 19 to the processing combustion chamber 23, with the remaining portion of the fine coke being removed via line 33 as commercial product.

The main (second) part of the gaseous heating agent is in the burner 25 which is operated with gas supplied with air through the inlet pipe 26.
The heating agent heats the fine coke, that is, the solid heat transfer agent, and supplies the heating agent to the processing combustion chamber 23 through the
It serves to send the water to the cyclone 24 via the cyclone 24.

The fine coke separated in the cyclone 24 at a temperature between SOO and 1,500° C. is sent through an intermediate bin 27 to the water gas reactor 11 where the required predetermined portion of said fine coke is passed through a path 9 to a grid 10. It is gasified by the water vapor supplied through the fuel, which water vapor is produced from the water contained in the fuel, and if this water vapor is insufficient, water vapor is further introduced along path 28.

The water vapor in the water gas reactor 11 is converted into high-calorie gas, which is a valuable chemical feedstock and fuel.

The gaseous suspension of water gas and fine coke from the water gas reactor 11 is sent to a cyclone 29 where the fine coke is separated from the water gas and used as a heat transfer agent in the bin 3.
0 to path 14 where it is mixed with a portion of the gas effluent from cyclone 24.

The main part of the gas is removed via line 31, purified and supplied to the power plant.

In the above mixing of the solid heat transfer agent and the gaseous portion, the resulting mixed heating agent is sent to the first stage pyrolyzer 13.

Thus, in the process according to the invention, a closed cycle of pyrolysis, gasification and drying is provided, so that harmful emissions into the atmosphere are removed.

This is because the purified pyrolysis gas, water gas and mixed gas are sent to the combustion chamber of the power plant.

Therefore, the height and overall dimensions of the boiler of the power plant can be minimized, and the operation of the boiler can be substantially simplified.

Furthermore, in the method according to the invention no additional fuel is required, since steam is used for the gasification and this steam is produced by drying the fuel.

This increases the power efficiency of fuel utilization by 3-5%.

The water gas (primarily hydrogen and carbon oxides) from cyclone 29 is sent via path 32 to purification and then to usage equipment.

Equipment used may include power plants, including gas turbines, or chemical reactors for the production of hydrogen, synthesis gas, methanol, and other products.

The method according to the invention makes it possible to produce water gas at a very low cost.

For example, the excess amount of fine coke in the water gas reactor 11 ensures high decomposition of water vapor (80-95%) and high power efficiency, while simplifying the overall system.

Automatic control of the production of the required amount of water gas, the processing temperature and the amount of circulating solid heating agent, i.e. fine coke, from the process via the intermediate bin 17, taking into account possible changes in the amount of fuel and the operating conditions of the power plant. This is done by varying the amount of fine coke taken off via path 33 and by supplying steam to the water gas reactor 11.

The necessary control valves for the corresponding flows of water vapor, gas, gas suspension and solid particles are not shown.

A very important feature of the new method is that the heating chamber of the power plant is fed with gas, from which sulfur, solid fuel and ash have been completely removed by purification, thus converting the boiler into a gas-heated boiler, with no slag on the heating surfaces. What happens is that it is removed.

This method resulted in high economic parameters of the process for peat-like fuels including high water content peat.

The dimensions of the entire boiler installation are substantially reduced.

The temperature conditions of pyrolysis and gasification are also controlled by varying the amount and temperature of the gaseous heating agent produced in gas burners 20 and 25 and process combustion chamber 23.

A large amount of low-calorie gas generated in the processing combustion chamber 23 and the burners 20 and 25 is supplied to the combustion chamber of the power plant together with the gas, so that the combustion temperature in the combustion chamber of the power plant is reduced and the gas from the power plant is reduced. The harmful nitrogen oxide content in the effluent is determined by both the external oxides (formed during nitrogen combustion in the combustion chamber) and the internal oxides (formed from the fuel nitrogen) formed during the processing of the above fuels in the power plant. significantly reduced.

This not only ensures a large comprehensive utilization of the fuel in the power plant, but also in terms of the gaseous components (oxides of sulfur and nitrogen) and solid components (ash particles) released into the atmosphere. Contamination of the environment with equipment waste gases is virtually completely eliminated.

The method of the present invention also allows the use of low grade power liquid fuels by introducing them into the process combustion chamber or into the water gas reactor depending on the ultimate use of the produced water gas.

In order to provide a better understanding of the present invention, a method for heat treatment of fine solid fuel will be explained by the following specific example.

Example 1 This example describes the operation of a power process plant (PPP) with thermal treatment of coal.

The capacity of one unit is 500 tons crude coal/hour.

The annual capacity of the plant is 50 million coal (min)
ton, and the power consumption of the plant is 32 pillion (bl).
n, ) kW, hour 7 years.

3,560 k per combustible wind, containing 36% moisture, 6.5% ash and 48% volatiles by weight
Crude coal having a caloric capacity of cal/kg is heat treated.

Coal from bin 1 is fed to drying mill 2 and passes through inlet pipe 3 at temperatures of 780°C and 58°C, respectively, per 100 kg of coal.
A circulating mixture consisting of 120 kg of fine coke (solid heating agent) heated to 0° C. and 80 kg of steam is introduced into the mill.

The product obtained after drying i.e. 64-
dusty dry coal (residue on 100 micron sieve is 1
0% by weight) and 36- is sent along with the heating agent to cyclone 8 where the coal and fine coke are separated from the steam.

36 kg of water vapor was introduced into the water gas reactor 11, and 80 kg of water vapor was introduced into the water gas reactor 11.
ky for circulation to mill 2.

If the 18 kg of coal produces an excess amount of steam in this example, it can be fed to the combustion chamber of the power plant.

64 kg of dry coke, 250'C fine coke (
120 kg) is fed to the first stage pyrolyzer 13 through the intermediate bin 12, and then to the treatment combustion chamber 23 and the water gas reactor 1.
Heating to 680°C with a mixed heating agent (fine coke at 850°C and gas not exceeding 1% by volume of free oxygen at 1,050°C) supplied from each of the four cyclones 24.29.

The first stage pyrolyzer 13 is fed with 160 kg of fine coke and 32.5 kg of gaseous heating agent.

The thermal decomposition of the coal is completed at 780° C. in the second stage thermal decomposer 19.

Excess gas is withdrawn via line 31, purified and supplied to the power plant.

With the increased circulation ratio of fine coke, its feed to the pyrolyzer is 203 kg, while the gaseous heating agent is all taken off via path 31.

In the pyrolysis machine, from 64.0 kg of dry coal and circulating fine coke, 29.5 kg of steam-gas mixture (VG
M) and 35.2 kg of fine coke are produced.

The fine coke is separated from the VGM and the VGM is sent to the refining and condensing system.

Apart from the commercial fine coke, the above pyrolysis and heating of the coal produces 18.0 kg of pyrolysis gas (pyrog).
as) 8.6 kg of resin and gas naphtha, 2.
9 kg of pyrolysis water
) and a heating agent are obtained.

The pyrolysis gas has a caloric capacity of 4.840 kcal/m3 and has the following composition (% by volume): CO2-2
2, C0-27, H2-20, CH4-21, other hydrocarbons - 10,81,000kcal or 23% of the potential coal heat is converted into pyrolysis gas, 67.500kc
al, or 19% of the potential coal heat, is converted to resin and gas naphtha.

63% of the potential coal heat or 58% of the heat supplied to the unit is converted into fine coke obtained from the pyrolysis of coal.

An embodiment of the plant in which the entire amount of half-gas obtained after the treatment combustion chamber 23 is fed to the power plant via line 31 and with it the rate of feed of the solid heating agent, i.e. fine coke, to the pyrolyzer is increased by the same weight. is possible.

Commercial fine coke contains 12 kg of carbon and 0,2
Produced in an amount of 14.4 kg containing kg of hydrogen.

In the second stage pyrolyzer and treatment chamber, two parts of fine coke are
．． 2 kg and 8.3 kg are converted to gas and half gas respectively.

6.5 to 9 fuel ash is removed along with fine coke and slag.

The fine coke heated to 1,050° C. in the treatment combustion chamber 23 is separated from the gaseous heating agent and fed to the water gas reactor 11, where superheated steam (18 ky) and dusty fine coke (166 to 9 ), 24 kg of water gas are produced as a result of the reaction of H20 and C.

In Cyclone 29, the water gas was fine coke (160 kg).
, temperature 850° C.) and discharged via path 32, after cooling, it undergoes purification and is used in power plants and as a commercial product for the production of hydrogen, reducing gas or synthesis gas.

The fine coke containing the heating agent passes through the bin 30 to the path 14.
where the gas from cyclone 24 (half gas)
This mixture is then sent to a first stage pyrolyzer for pyrolysis and the process plan is terminated, ie, no harmful emissions are released to the atmosphere in the process or power plant.

Example 2 This example describes an embodiment of the process of the invention where production of commercial fine coke is undesirable due to increased ash, sulfur content and other reasons.

The method is carried out on crude coal of the same composition as in Example 1.

In the water gas reactor, twice the amount of water vapor (36 kg) is decomposed which evaporates from 100 kg of coal and reacts with 12.6 to 9 fine coke.

48 kg of water gas, 8.5 kg of gasoline and resin, pyrolysis gas at 18.3 hours, 3 kg of pyrolysis liquid (pyr
1 quart) 6.5 kg of ash and slag, 105 ky of half gas.

All moisture in the fuel used (36 to 9 per 100 g of lime)
) is gasified in this embodiment of the process according to the invention.

In other words, it is converted into water gas.

This provides an economical efficiency of approximately 6% coal heat savings, thus increasing coal processing and utilization efficiency.

If there is a shortage of steam due to possible changes in practice and due to the moisture content and composition of the coal or the reduced activity of the carbon, a controlled amount of steam is supplied to the device from the outside via line 28.

If necessary, the coal drying step can be carried out without supplying steam, ie only by supplying a solid heating agent to the mill 2.

Example 3 This example describes an embodiment of the process of the invention in which the fine coke is characterized by low reactivity with water vapor or by a specific composition of ash content.

In this case, the heating agent has a high starting temperature just such that the fine coke reacts with the steam.

Coal of the same composition as in Example 1 is treated.

The moisture content of the coal is 27% and the ash content is 21.9%.

The treatment combustion chamber is supplied with air heated to 700'C by the gas released via path 31, raising the temperature of said treatment combustion chamber to 1,500-1,600'C and converting the ash to liquid slag. Let it be released.

The product obtained is the same as in example 2, namely: 36k
y water gas, 6.4 ky resin and gasoline, 13
．． 7 kg of pyrolysis gas, 2.3% by volume of pyrolysis liquid (py
29.9 kg of ash and slag are obtained.

This allows complete conversion of coal into liquid and gaseous products and eliminates the release of ash and sulfur oxides into the atmosphere.

[Brief explanation of the drawing]

The drawing is a preferred flow sheet of the method. 2...Shaft mill, 8...Cyclone, 11...Water gas reactor, 13...
・First step pyrolyzer, 15...Cyclone, 1
9... Second step pyrolyzer, 20... Gas burner, 23... Treatment combustion chamber, 24...
...Cyclone, 29...Cyclone.

Claims (1)

[Claims] 1. A method characterized by including the following steps (a) to (g):
Heat treatment method for fine solid fuel. (a) a step of drying the fine solid fuel; (b) a step of subjecting the dried fine solid fuel to two-step pyrolysis, and then separating the produced steam-gas product from the fine coke; (c) one of the fine coke. part to a drying step and at least a part of the remaining fine coke to 800% by partial combustion of gas and/or said fine coke.
(b) separating the heated fine coke from the gas supplied to the first step of pyrolysis; (e) adding the heated fine coke to the above-mentioned fuel. (f) separating the fine coke from the gasified product; (g) supplying the fine coke as a heat transfer agent to the first step of pyrolysis. 2. The method according to claim 1, wherein finely divided solid fuel is used, the particle size of which does not exceed 1.5 mm. 3. A method according to claim 1, wherein the drying of the fuel is carried out in a superheated steam stream. 4. Process according to claim 1, wherein a part of the gas separated from the heated fine coke is fed to the first stage of pyrolysis. 5 Gas supplied to the first step of pyrolysis is up to 2% by volume
5. A method according to claim 4, characterized in that free oxygen of