JPH0153719B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for starting a spouted bed type coal gasifier, in particular a jet flow suitable for shortening the startup time and ensuring safe operation without being restricted by the type of coal used. This article relates to a method for starting a bed coal gasifier.

As shown in FIG. 1, the spouted bed coal gasifier has a water-cooled wall tube group 2 provided inside a main body shell 1.
The space between the water-cooled tube group 2 and the main body shell 1 constitutes a sealing layer. This space contains _N2 gas3
is introduced and by balancing the pressure,
Gas in the furnace comes into direct contact with the main body shell 1 to prevent corrosion problems from occurring. The lower space 4 in the furnace is lined with a cable 5, and in the process in which the mixture 6 of pulverized coal and oxygen is partially oxidized at high temperature in the furnace to become coal gas, the ash content is melted. After falling from the nose 7 into the water chamber 8 and being rapidly cooled, it is discharged into the atmosphere through the slug lock hopper 9. Coal gas is introduced into the produced gas treatment system through the upper space 10 within the furnace. In this process, the water flowing through the water-cooled pipe group 2 is recovered as steam due to the heat retained in the coal gas.

When starting up such a spouted bed coal gasifier, the startup burner 11 warms the inside of the furnace, and the state in which the burner is ignited is sequentially switched to coal. In this case, if the coal gasification furnace is lined with extremely thick refractory bricks like a TEXACO furnace, if the inner surface of the refractory bricks is heated in advance, it will not be possible to start up the furnace even if the burner is turned off and switched to coal. There are no particular problems. However, in the spouted bed type coal gasifier with the structure shown in Figure 1, the lower part of the furnace is lined with a thin castable 5, and the other inner surface of the furnace is formed by a group of water-cooled tubes 2, so it is similar to a TEXACO furnace. It is not possible to use residual heat.

In addition, when the type of coal used for coal gasification is low-melting point coal, by heating the atmosphere inside the furnace with a starter burner and then switching to coal, it is possible to convert it into molten slag even when air is used as the fuel oxidation means. It is possible. However, if the type of coal is high melting point coal with a melting point of 1500°C or higher, it is difficult to convert it into molten slag using an air-fired start-up burner. Therefore, when starting with air combustion, it is possible to add a slag low melting point additive to the raw coal, but it is necessary to provide equipment to add the low melting point additive only for the startup operation. has practical problems.

The purpose of the present invention is to solve the above-mentioned problems of the prior art, to facilitate coal gasification and molten slag regardless of the type of coal used, to shorten start-up time, and to achieve stable operation. An object of the present invention is to provide a method for starting a jet coal gasifier.

In short, the present invention uses air or an oxidizing gas with a higher oxygen content than normal air as an oxidizing agent at startup, and after the inside of the furnace reaches a certain temperature, the combustion improver is switched to coal and the oxidizing gas is After reaching a sufficient combustion state by gradually increasing the oxygen content of the coal, the amount of coal input and the oxygen content of the oxidizing gas are increased, and the atmosphere inside the furnace is changed from an oxidizing atmosphere to a reducing atmosphere while increasing the temperature inside the furnace. By migrating, the above objective was achieved.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 shows, in block diagram form, a flow sheet for carrying out the present invention. In FIG. 3, when the jet coal gasification furnace 11 is started, oxygen 13 and nitrogen 14 generated from the oxygen production equipment 12 (air separation device) as oxidizers are passed through the mixer 15 to create an oxygen-nitrogen mixed gas 16, and the jet It is supplied to a type coal gasification furnace 11. On the other hand, fuel at startup is supplied from the fuel equipment 17 to the jet coal gasifier 11,
The temperature at which coal ash turns into slag inside the furnace is 1300℃.
Heat to ~3000℃. Coal is supplied from coal equipment 18 to jet coal gasifier 11 . The coal gas generated in the gasifier 11 passes through a dust collector 19, where pulverized coal in the coal gas is collected, and this pulverized coal is introduced into the gasifier 11 again. The gas that has passed through the dust collector 19 is supplied to desired equipment as generated gas. The slag 21 generated in the gasifier 11 is
It is discharged to the atmosphere through a water chamber and slug lock hopper as shown. Here, the oxygen concentration in the oxygen-nitrogen mixed gas is 25% to 80
It is desirable to set it as %. If the oxygen concentration in the mixed gas exceeds 80%, especially 100%, it is undesirable because troubles may occur due to temperature rises in the furnace internal structure and the burner during startup. Next, the preferred range of oxygen concentration in the oxygen-nitrogen mixed gas will be explained with reference to FIG. 4, which shows the relationship between oxygen concentration and combustion gas temperature. To prevent troubles such as misfires and gas explosions during startup, it is desirable to perform startup in the oxidizing atmosphere region shown in FIG. 4. However, if air is used as the oxidizing agent during startup, the temperature inside the furnace will only rise to about 1700 to 1800°C in an oxidizing atmosphere.
(1500℃ or higher), it becomes difficult to fluidize the ash as slag and extract it, leading to the problem of longer start-up times. On the other hand, if 100% oxygen gas is used as the oxidizing agent during startup, the temperature inside the furnace will exceed 3000°C, which poses problems regarding the structural materials of the equipment. Therefore, it is desirable to have an oxygen concentration of 25% to 80%, which provides a temperature sufficient to slag the ash and does not cause problems with the structural materials of the device. In addition, by adjusting the oxygen concentration in the oxygen-nitrogen mixed gas during startup within the range of 25% to 80% depending on the type of coal used, the startup operation is performed according to the type of coal used. be able to. Further, in the case of a mixed gas having the above oxygen concentration, the time required for startup can be shortened compared to the case of using air as an oxidizing agent. Furthermore, if air is used as an oxidizing agent during startup,
Switching the oxidizing agent from air to oxygen takes time and effort, and there is a risk of misfires, temperature drops, etc. at the time of switching. However, in this embodiment, such troubles can be prevented.

Next, an example of the starting method of the present invention will be explained in more detail based on FIG. 5. In Fig. 5, the steps at startup are conveniently shown as Step 1 to Step 7.
I will explain it separately. In step 1, start the burner to convert LPG or oil to air equivalent or oxygen concentration.
Combustion is performed using approximately 25% oxidizing gas, and the temperature inside the furnace is raised to A at normal pressure. The furnace temperature A only needs to be maintained at a temperature necessary for igniting the coal, and there is no need to melt the ash. In step 2, LPG is switched to coal (pulverized coal) while the furnace temperature is constant from A to B, and the oxygen concentration in the oxidizing gas is increased.

Through these operations, the temperature inside the furnace is gradually raised, and a complete oxidizing atmosphere at point G is confirmed (steps 3 and 4). The amount of coal input is increased to a level higher than the oxygen addition rate, the coal is transferred to a reducing atmosphere at a pressure level G sufficiently lower than the set value, and the stage of producing flammable gas, which is coal gasification, begins (step 5). Next, the oxidizing gas is changed to 100% oxygen, and the final pressure and temperature are measured to reach the final molten slag formation temperature C (step 6). After confirming the molten slag formation temperature C, increase the furnace pressure (I)
and the coal input load (F) are set (Step 7).

In the above embodiment, since air is not used as an oxidizing agent during startup, equipment for feeding air into the jet coal gasifier is not required, and the number of equipment can be reduced. In the above embodiment, an oxygen production plant (air separator) is used as an oxidizing agent during startup.
However, in the present invention, oxygen produced from an oxygen production plant is mixed into the air as an oxidizing agent during startup, and an oxidizing gas with an oxygen concentration of 25 to 80% is used. It can also be used with sexual gases.

As described above, according to the present invention, at startup,
By adjusting the oxygen concentration in the oxidizing gas, a sufficient temperature inside the furnace can be obtained, so coal gasification and ash molten slag can proceed without any problems, and the time required for startup can be shortened. It is also possible to convert the coal into molten slag regardless of the type of coal used. Also, unlike the conventional method,
Since there is no need to switch to 100% oxygen gas, troubles such as misfires that occur during the switching process can be prevented.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram showing the structure of a jet coal gasifier, Fig. 2 is a cross-sectional view taken along line A-A' in Fig. 1, and Fig. 3 is a block diaphragm showing an example of the present invention. Figure 4 shows the oxygen concentration in the oxidizing agent and oxidation,
FIG. 5, which is a diagram showing the relationship between reducing atmospheres, is an explanatory diagram showing an example of the starting method of the present invention. DESCRIPTION OF SYMBOLS 1...Main shell, 2...Water-cooled wall tube group, 5...Castable, 8...Water chamber, 9...Slug lock hopper, 11...Jet type coal gasifier, 12
...Oxygen production equipment (air separation equipment), 13...Oxygen,
14... Nitrogen, 15... Mixer, 17... Fuel equipment, 1
8... Coal supply equipment, 19... Dust collector.

Claims (1)

[Scope of Claims] 1 The temperature inside the jet coal gasifier is raised by a combustion improver and normal air or an oxidizing gas with a higher oxygen content than this air, and after the inside of the furnace reaches a certain temperature. ,
The combustion improver is changed to coal, and the oxygen content in the oxidizing gas is gradually increased. After reaching a sufficient combustion state, the amount of coal input and the oxygen content in the oxidizing gas are further increased, and the oxygen content in the oxidizing gas is increased. A method for starting a jet coal gasification furnace, which is characterized by shifting the atmosphere in the furnace from an oxidizing atmosphere to a reducing atmosphere while heating the furnace. 2. The method for starting a jet coal gasifier according to claim 1, wherein the oxidizing gas is a mixed gas of oxygen and nitrogen. 3. The method for starting a jet coal gasifier according to claim 2, wherein the oxygen and nitrogen are generated in an oxygen production plant.