JPS5869291A - Gasification of solid fuel and gas producer - Google Patents

Abstract

PURPOSE:To stably gasify solid fuel at a high thermal efficiency, by gasifying the solid fuel supplied through a feeding hole of a double-lid construction at the top of a kiln with a gasifying agent sent through an eccentrically rotating grate and withdrawing generated gas through two-level outlets. CONSTITUTION:A solid fuel such as coal or coke is supplied to a kiln by operating an outer lid 3 and an inner lid 4 at the top of the kiln. A gasifying agent is sent from a gasifying agent feeding hole 13 at the bottom of the kiln through an eccentrically rotating grate 9 to gasify the solid fuel. The generated gas is withdrawn through upper withdrawing holes 5 and 6 and an intermediate withdrawing hole 7 out of the kiln. The gas withdrawn through the hole 7 contributes little to combustion in the kiln, so that heat loss is reduced by withdrawing it through this hole. It is possible to control an amt. of steam generated by heat exchange by a jacket by controlling a proportion of the gases withdrawn at the top and intermediate parts, which makes it possible to decrease make-up water and surplus steam and to increase the thermal efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for turning solid fuel into scum and a gas generating furnace used in the process. An improved method for gasifying solid fuel with stable gas generation and high thermal efficiency, using air or steam, or lime kiln exhaust gas in addition to these, and its gas generating furnace;
It is related to.

Conventionally, in order to produce flammable gases for fuels and raw material gases for synthetic chemicals, solid fuels such as coal, anthracite, and coke are brought into contact with gasifying agents such as air, oxygen, and water vapor at high temperatures. Methods that utilize the various gases generated by the reactions described above have been known for a long time.

In other words, for volatile components such as coal and anthracite in the gas generating furnace, CmHn -1-mHi'o -) mco +"-E
YuH2-(1)CmHn +-02-+ mCO+-H
2-(2) Reactions like 2, carbon content such as coal and anthracite, and coke, C+02 →CO□ ・・(3)C+
+0□ →Co ,,, (4) C+CO2→2CO・・・(5) C+H20−+ CO×H2−(6) C+2H20→C02+2H2・(7) C+2H2→C
H4...(8) The following reaction proceeds.

Among the above reactions, formulas (1), (2), (5), (6) and (8) are the main gasification reactions; , (6), the reaction is promoted as the temperature inside the furnace increases, but as the temperature rises, the reaction in (8) is conversely suppressed. On the other hand, when the furnace pressure increases (
8) Contrary to the fact that the reaction of formula (1), (2),
On the contrary, equations (5) and (6) are suppressed. Therefore, in a gas generating furnace at normal pressure and a relatively high temperature, the generated gas is mainly carbon monoxide and hydrogen, with a small content of methane, whereas in a gas generating furnace under pressure and at a relatively low temperature, , a gas containing considerable amounts of methane is obtained.

In view of such reactions, various types of gas generating furnaces have been put into practical use depending on the required residue composition. For example, Kapper 7 is used to generate nitrogen-containing scum using air and water vapor as gasifying agents.
S-Kerpely) type gas generator, which uses air and small steam as the gasifying agent, but intermittent water gas generators and continuous water gas generators, which generate gas that does not contain nitrogen, use air as the gasifying agent. , using oxygen and water vapor,
A semi-aqueous gasifier to generate gas suitable for ammonia synthesis, or a methane-rich lurgi (Lu-
(rgi) type high-pressure gas generating furnaces have been put into practical use.

The present inventors have provided a solid fuel gasification method that allows solid fuel to be continuously supplied and generated ash to be easily and continuously discharged, and that also has stable gas generation and high thermal efficiency. As a result of extensive research into this device, we have developed a vertical gas generating furnace with a cooling jacket connected to a flash tank, with a double lid structure for the raw material input chamber at the top to continuously supply solid fuel into the furnace. As a result, there are no large fluctuations in gas temperature or gas concentration, and gas generation is stabilized.Also, the generated gas extraction ports are provided in two stages, one in the upper part of the furnace and the other in the middle, to reduce the amount of generated waste extracted from both parts. By adjusting the ratio, the amount of steam generated by heat exchange in the jacket can be reduced to a trickle, increasing thermal efficiency.In addition, a scraper can be installed under the rotating grate at the bottom of the furnace. By discovering a scale through which ash can be easily and continuously discharged outside the furnace, and by using the generated scum for a lime kiln, and using the exhaust gas from this kiln as part of the gasification agent, It was discovered that the thermal efficiency increased, and based on this knowledge, the present invention was completed.

That is, in the present invention, when solid fuel is brought into contact with a gasifying agent in a vertical gas generating furnace to turn the solid fuel into scum,
Solid fuel is supplied into the furnace from a fuel input chamber with a double lid structure at the top of the furnace, while a sludge agent is fed into the furnace from between the grates of an eccentric rotating grate installed at the bottom of the furnace to solidify the solid fuel. The fuel is gasified and the generated gas is extracted from the gas extraction ports provided in two stages at the top and middle of the furnace, while the ash produced by gasification of the solid fuel is sent to the eccentric rotating grate and below it. Cooling water is continuously discharged from the bottom of the furnace using the provided scraper blades, and the cooling water heated by heat exchange in the cooling jacket is led to a flash tank to be used as a flash tank. A solid fuel gasification method is characterized in that the solid fuel is fed into the furnace, and the furnace has a fuel input chamber at the top, an eccentric rotating grate at the bottom, a gasification agent inlet and an ash discharge port at the bottom, In a vertical gas generating furnace that has a generated gas outlet and a cooling jacket connected to the flat tank, (a) the fuel input chamber has a double-lid structure, and (b) the generated gas outlet is located in the upper and middle parts of the furnace. This relates to a gas generating furnace characterized in that (c) a scraper blade is provided under the eccentric rotating grate.

Next, the gasification method and gas generating furnace of the present invention will be explained in detail with reference to the drawings.

The figure is a schematic sectional view of the gas generating furnace of the present invention. In the figure, reference numeral 1 denotes a hopper for supplying solid fuel to the gas generating furnace, and 2 denotes a double lid structure comprising an upper outer cover 3 and a lower inner cover 4. 5.6 is an upper gas outlet for extracting generated gas to the outside of the furnace; 7 is an intermediate gas outlet; 8 is a 7-rush tank 12 for discharging cooling water heated by heat exchange. A cooling jacket 9 is connected to an eccentric rotating grate for uniformly pushing out the generated ash downward, and 10 is for collecting the ash pushed out from the rotating grate and discharging it out of the furnace from an ash extraction port 11. 13 is a gasifying agent inlet for feeding a sludge agent such as air or steam into the furnace, and 14 is a tank for supplying the steam generated by flashing in the flash tank 12 into the furnace. The steam supply pipe and 15 are gasifying agent supply pipes other than steam.

Solid fuel is introduced from a hopper 1 into a fuel input chamber 2 at the top of the furnace, and is supplied into the furnace by operating an upper outer cover 3 and a lower inner cover 4. This double lid structure makes it possible to continuously supply solid fuel into the furnace, and also plays the role of stabilizing gas generation by eliminating large fluctuations in gas temperature and gas concentration. Examples of the solid fuel used here include coal, anthracite, coke, and wood chips, and these may be used alone or in combination.

On the other hand, the gasifying agent is fed into the furnace through the gasifying agent inlet 13 at the bottom of the furnace, passing between the grates of the eccentric rotating grate 9 installed at the bottom of the furnace, and gasifying the solid fuel. . The generated gas is extracted out of the furnace through the upper extraction ports 5 and 6 and the intermediate extraction lower. The gas extracted from the intermediate extraction port makes little contribution to combustion within the furnace, and therefore, by extracting it from the intermediate portion, heat loss is reduced. In addition, by adjusting the ratio of the amount of gas removed from the upper and middle sections, the amount of water vapor generated by heat exchange in the jacket can be controlled, making it possible to reduce make-up water and the amount of excess water vapor. This increases thermal efficiency.

In the present invention, air or highly oxygen-containing air and water vapor are preferably used as the gasifying agent.

Further, the gas generated from the gas generating furnace of the present invention can be used for a lime kiln, and in this case, the exhaust gas discharged from the lime kiln with a carbon dioxide concentration of about 30 to 50% is used as a gasifying agent to By using it in the gas generating furnace of the present invention together with water vapor and steam, the thermal efficiency increases by about several percent.

On the other hand, the ash produced by gasification of solid fuel is separated, and the ash at the bottom of the furnace is extracted by the eccentric rotating grate 9 installed at the bottom of the furnace and the ash scraper IO installed below it.
1, it is easily and continuously discharged out of the furnace. At this time, since the gasifying agent is fed into the furnace from between the grates of the eccentric rotating grate, the lost ash is cooled by the gasifying agent, making it easy to handle without forming lumps.

In addition, the water vapor generated by guiding the cooling water heated by heat exchange in the cooling jacket 8 to the flash tank 12 and flashing it is sent to the gas generating furnace through the steam supply pipe 14 as a gasifying agent. do.

The gas generation furnace of the present invention can be used to gasify solid fuel, is easy to continuously supply solid fuel and continuously discharge ash, is stable in gas generation, and is thermally efficient. Furthermore, the generated gas can be used for a lime kiln, and in this case, by using the dregs discharged from the lime kiln as part of the gasification agent in the gas generating furnace of the present invention,
Thermal efficiency increases further.

Next, the present invention will be explained in more detail with reference to Examples.

In addition, the value of thermal efficiency in an Example was calculated by the formula shown below.

[Example] In the scum generating furnace of the present invention, four types of solid fuels were coke, anthracite, coal, and wood chips + coke.
Solid fuel was gasified according to the gasification method of the present invention using air and water vapor as scum forming agents. However, the ratio of the amount of generated waste extracted from the furnace upper gas outlet and the intermediate gas outlet was 67:33.

The results are shown in Table 1 along with the physical properties and particle size distribution of the solid raw material, the amount and temperature of the air fed, and the amount of steam fed.

Note that the amount of air fed, the amount of steam fed, and the amount of produced air in the table are values per ton of solid fuel.

Example 2 A solid fuel was produced in the same manner as in Example 1, using the same coke as the coke in N[L] in Example 1 as the solid fuel, and replacing part of the steam with lime kiln waste as a gazing agent. The fuel was gasified.

The results are shown in Table 2 along with the amount and temperature of the air to be fed, the amount of steam to be fed, and the amount of exhaust gas to be fed.

Note that the amount of air fed, the amount of steam fed, the amount of exhaust gas fed, and the amount of produced air in the table are values per 1 ton of solid fuel. Moreover, the CO2 concentration in the lime kiln waste is 32 to 37%.

Table 2 From Table 2, when lime kiln furnace exhaust gas is used as a gasification agent in place of a portion of steam, the thermal efficiency increases by 3% compared to when exhaust gas is used (Example) -Nα1). It turns out that it does.

[Brief explanation of the drawing]

The figure is a schematic sectional view of the gas generating furnace of the present invention, in which reference numeral 1 is a hopper, 2 is a fuel input chamber, 3 is an upper outer cover, 4 is a lower inner cover, 5 and 6 are upper waste removal ports, and 7 is an intermediate gas extraction port, 8 is a cooling jacket, 9 is an eccentric rotating grate, ]0 is an ash scraper, 11 is an ash extraction port, 12
13 is a flash tank, 13 is a gasifying agent inlet, 14 is a water vapor supply pipe, and 15 is a gas stopper supply pipe other than water vapor. Patent applicant Akira Agata, agent of Okutama Kogyo Co., Ltd.

Claims (1)

[Claims] 1. In a vertical gas generating furnace, when solid fuel is brought into contact with a gasifying agent to gasify the solid fuel, the solid fuel is introduced into the fuel input chamber having a double lid structure at the top of the furnace. On the other hand, the solid fuel is fed into the furnace between the grates of an eccentric rotating grate installed in the lower part of the furnace, and the generated gas is sent to the upper and middle parts of the furnace. On the other hand, the ash produced by gasification of the solid fuel is continuously discharged from the bottom of the furnace using an eccentric rotating grate and scraper blades installed below it. , ~ A solid fuel characterized by further leading the cooling water heated by heat exchange in the cooling jacket to a flash tank and flashing it, and sending the emitted water vapor into the furnace as part of the gasifying agent. 2. The gasification method according to claim 1, wherein the gasifying agents are air, steam, and lime kiln gas. 3. The furnace has a fuel input chamber at the top and an eccentric rotating grate at the bottom. ,
In a vertical generator furnace that has a gasifying agent inlet and an ash outlet at the bottom, and a cooling jacket connected to the generated gas outlet and the flattened tank, (a) the fuel input chamber has a double lid structure; (b) A gas generating furnace is characterized in that waste removal outlets are provided in two stages at the upper and middle parts of the furnace, and (c) scrapers are provided below the eccentric rotating grate.