JPH04130186A - Method for partially oxidizing carbonaceous fuel - Google Patents

Abstract

PURPOSE:To increase the yields of H2 and CO by supplying carbonaceous fuel and steam to a combustion furnace after conversion of the water in an aqueous slurry of carbonaceous fuel into steam so that the fuel is partially oxidized. CONSTITUTION:In a method for partially oxidizing carbonaceous fuel wherein a solid carbonaceous fuel (e.g. coal, coke or petroleum coke) is partially oxidizing in a combustion furnace to generate gas containing at least CO, CO2, and H2, a slurry of the fuel is heated to give a mixture of a carbonaceous fuel powder and steam, and this mixture is supplied to the combustion furnace. According to this technique, since the carbonaceous fuel and steam are supplied to the combustion furnace after conversion of the water in the aqueous slurry of carbonaceous fuel into steam, the combustion energy of the carbonaceous fuel is not consumed as the heat of vaporization of water. As the result, less carbonaceous matter of the fuel will be oxidized into CO2 so that the yield of CO will be increased as much.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for partially oxidizing carbonaceous fuel to produce synthesis gas, reducing gas, fuel gas, etc. containing H2 and CO.

[Prior Art] A conventional method for partial oxidation of carbonaceous fuel involves burning solid carbonaceous fuel such as coal with oxygen in the presence of water vapor in a combustion furnace to generate gas containing Co, CO2, H2, etc. better known.

Co and C generated by this method of partial oxidation of carbonaceous fuel
Gas containing O2, H2, etc. is used as synthesis gas, reducing gas, fuel gas, etc.

Conventionally, as a method of supplying solid carbonaceous fuel such as coal to a combustion furnace, solid carbonaceous fuel is mixed with water slurry (e.g. coal/
There is a method of making water slurry (CWM) and supplying this slurry as it is to the combustion furnace. This wet feeding method allows carbonaceous fuel to be supplied to the combustion furnace using a pump, simplifying equipment and stabilizing the fuel supply.

[Problems to be Solved by the Invention] In a conventional partial oxidation method using a solid carbonaceous fuel slurry, thermal energy for evaporating water in the slurry is generated by oxidizing the carbonaceous fuel. Therefore, it is necessary to oxidize a portion of the carbonaceous fuel to Co2 to generate a large amount of thermal energy (heat of combustion). As a result, in the conventional partial oxidation method of solid carbonaceous fuel, CO
There was a problem that the amount of 2 produced was large and the yield of CO was small.

[Means for solving 11B] The present invention is an improved method for partially oxidizing carbonaceous fuel, in which carbonaceous fuel is partially oxidized in a combustion furnace to generate a gas containing at least Co, CO2 and H2. be.

In the present invention, a slurry of carbonaceous fuel is heated to form a mixture of carbonaceous fuel powder and steam, and this mixture is supplied to the combustion furnace.

In the present invention, when CWM is heated to steam,
The pressure of the steam is set to be higher than the sum of the pressure inside the combustion furnace and the burner pressure drop.

In the present invention, the carbonaceous fuel may be any solid fuel containing carbon, and examples thereof include coal, coal coke, petroleum coke, and the like.

When partially oxidizing this solid carbonaceous fuel, a water slurry of the solid carbonaceous fuel is prepared, heated, and fed into a combustion furnace as a mixture of carbonaceous fuel powder and steam. In this case, air, oxygen-enriched air or substantially pure oxygen is fed into the combustion furnace.

As a heating means for heating the water slurry of carbonaceous fuel to evaporate water, a heater using waste heat (evaporator) is suitable, and the heat source for this heater is the heat generated in this partial oxidation process. Preferably, waste heat is used. This heater first preheats the slurry to near its boiling point, then
Preferably, it is configured to be evaporated in an evaporator.

When sending carbonaceous fuel powder to a combustion furnace, nitrogen gas, hydrogen gas, carbon dioxide gas, -carbon oxide gas, etc. may be added as a carrier gas in addition to water vapor.

Through this partial oxidation, Co, CO2, H2CH4, H2
S, N2. Gas containing water vapor etc. is generated.

[Operation] According to the method of the present invention, the carbonaceous fuel and steam are supplied to the combustion furnace after the moisture in the water slurry of the carbonaceous fuel is turned into steam. Therefore, the combustion energy of this carbonaceous fuel is not consumed as heat of vaporization of water.

As a result, the amount of carbonaceous fuel that is oxidized to CO2 decreases, and the yield of CO increases by that amount.

[Example 1] Fig. 1 is a system diagram of an apparatus suitable for carrying out the method of the present invention.

In FIG. 1, carbonaceous fuel (coal in this example) and water are supplied to a mill 1 to form a slurry (CWM). This CWM is preheated to a temperature close to its boiling point via a slurry tank 2 and a slurry pump 3. After being heated in a vessel 4, water is evaporated in an evaporator 5. The steam and coal powder are sent to the burner 7 of the combustion furnace 6. Oxygen is also supplied to burner 7.

The upper part of the combustion furnace 6 is lined with a refractory material 8 to form a combustion chamber 9.
is formed. The lower part of the combustion furnace 6 is a gas cleaning chamber 10, and the combustion chamber 9 communicates with the gas cleaning chamber 10 via a throat portion 11.

Water is filled in the gas cleaning chamber 10 to a halfway height.
A cylindrical dip tube 1 so that the lower end is submerged in this water.
2 and a draft tube 13 are provided coaxially.

Although not shown, a quench ring is provided for supplying water to the upper inner peripheral surface of the dip tube 12 and forming a water film on the inner peripheral surface.

The gas taken out from a gas outlet 14 provided in the combustion furnace 6 passes through a venturi scrubber 15 and a gas scrubber 16, and water is supplied from a settler 18 to the gas scrubber 16, which becomes a dedusted product gas. New water is added to the return water from the settler 18 as needed. The water extracted from the bottom of the gas scrubber 16 is transferred to the gas cleaning chamber 1o.
and the venturi scrubber 15.

Slag flows from the bottom of the gas cleaning chamber 10 into the lock hopper 17.
It is extracted after passing through. Further, particle-containing water is extracted into the settler 18, separated by sedimentation, and discharged outside the system.

In the carbonaceous fuel partial oxidation method configured as described above, the carbonaceous fuel, steam, and oxygen are supplied into the combustion furnace 6 through the combustion chamber 9, and the carbonaceous fuel is partially oxidized in the combustion chamber 9. It will be done. This partial oxidation reaction mainly consists of Co, H2゜CO2, with small amounts of H2S, N
2. Gas containing CH4, unburned carbon, and a trace amount of ash is generated. This gas is in the gas cleaning chamber 10.
After passing between the dip tube 12 and the draft tube 13 inside and undergoing carbon and ash removal treatment,
A venturi scrubber 15 further performs a dust removal process, and a gas scrubber 16 then removes any remaining traces of carbon.

Therefore, since the moisture supplied to the combustion furnace 6 is in the form of steam, the combustion heat of the carbonaceous fuel generated within the combustion furnace 6 is not consumed in vaporizing water. As a result, the amount of CO2 generated decreases and the CO yield increases.

Next, a specific operational example will be described.

Coal having the following composition (wt%) was used as the carbonaceous fuel.

C66, 8 (wt%) 8 5, 0 (wt%) N
1. 7 (wt%)3
4, 2 (wt%)0
7, 3 (wt%) ash content 15.0 (
wt%) Calorific value 6910 (kcal/kg) The amounts of coal and oxygen supplied were as follows. Note that the coal concentration in CWM is 55% as coal/(water in coal).

Coal 1000kg/h Oxygen 567Nm'/h The temperature inside the combustion furnace 6 is 1400°C and the pressure is 40k
g/cm”G.CWM was heated to 25
A coal particle-steam mixture was prepared at 0° C., and this was supplied to the burner 7.

As a result, the composition of the gas taken out from the combustion furnace 6 and the amount of each component gas were as shown in Table 1 below.

Contrary Example 2 Partial oxidation of coal was carried out in the same manner as in Example 1 except that the main operating conditions were as follows. The results are shown in Table 2.

Coal 1000kg/h Oxygen 542Nm’/h The CWM heating temperature was 400°C.

EXAMPLE 3 Nitrogen gas was added as a carrier gas to a coal-steam mixture at a rate of 104 kg/h. Partial oxidation of coal was carried out in the same manner as in Example 1 except that the main operating conditions were as follows. The results are shown in Table 3.

Coal 1000kg/h Oxygen 547Ngo/h The CWM heating temperature was 250° C., the same as in Example 1.

Force Table Comparative Example 1 In the apparatus shown in FIG. 1, the preheater 4 and heater 5 were omitted, and CWM was directly supplied to the combustion furnace 6.

Partial oxidation of coal was carried out in the same manner as in Example 1 except that the main operating conditions were as follows. The results are shown in Table 4.

Coal 1000kg/h Oxygen 642N rr? /h Table Embodiment 4 FIG. 2 shows that in the apparatus shown in FIG.
22 is a heat transfer tube provided across a radiant heat transfer cooler and a convection heat transfer cooler 20, and is capable of generating high-pressure steam. . In addition, gas scrubber 1
The entire amount of water extracted from the bottom of the tank 6 is sent to the settler 18 where it is separated by solid-liquid sedimentation. A portion of the separated water is returned to the gas scrubber 16.

A comparison was made between the yields of H2 and Co when the apparatus shown in FIG. 2 was operated in the same manner as in Example 1, and the yield of H2+co when CWM was directly introduced into the combustion furnace 6 (Comparative Example 1). In this example, the yield of H2 and Co is about 15
% more.

[Effects of the Invention] As is clear from the above embodiments, according to the method of the present invention, carbonaceous fuel slurry is heated to steam, and then the carbonaceous fuel and steam are supplied to the combustion furnace. H2,C
The yield of o is increased.

[Brief explanation of drawings]

1 and 2 are flow sheets of a method for partially oxidizing carbonaceous fuel. 4... Preheater, 5... Heater, 6... Combustion furnace.

Claims (1)

[Claims] (1) In a carbonaceous fuel partial oxidation method in which a solid carbonaceous fuel is partially oxidized in a combustion furnace to generate a gas containing at least Co, CO_2 and H_2, a carbonaceous fuel slurry is heated to produce a carbonaceous A method for partially oxidizing carbonaceous fuel, which comprises preparing a mixture of fuel powder and steam, and supplying this mixture to the combustion furnace.