JPH0330046B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a spouted bed powder solid fuel gasifier, and in particular, the residence time of powder solid fuel particles in the furnace even when the load of the gasifier fluctuates. This invention relates to a powder solid fuel injection burner that can be easily maintained.

[Conventional technology]

Coal has the largest reserves among fossil fuel resources and is attracting attention as an energy alternative to oil. However, coal is solid and inconvenient to handle, and it also contains ash, sulfur, nitrogen, etc., and in order to expand its use, it is desirable to convert it into a clean energy source through liquefaction, gasification, etc. Currently, coal gasification is attracting attention as a promising method for turning coal into a clean fuel, and in particular, a coal gasification combined cycle system that uses clean gas produced from coal for power generation is attracting attention. Coal gasification technology is one of the key technologies that support the combined coal gasification combined cycle system, and as a gasifier for power generation, it has high gasification efficiency, operability and reliability that can respond to load fluctuations, and adaptability to a wide range of coal types. etc. are required.

As a coal gasifier that satisfies these conditions, spouted bed gasification, in which pulverized coal is reacted in an air stream, is promising.In the United States, Koppers-Totzek method,
The Texaco method, the CE method, etc. are being developed with the aim of increasing capacity and improving performance. We have developed a unique gasifier for the purpose of producing ammonia synthesis gas.

As a means of improving gasification efficiency, most of these furnaces focus on accelerating the gasification reaction by retaining solid fuel in the furnace as much as possible, and the burner installation position, angle, structure, etc.
In a cold test simulation furnace that simulates an actual gasification furnace, the residence time of each particle in the furnace is measured, and the furnace structure is determined by analyzing the flow of solid fuel inside the furnace. .

Among them, as shown in Figure 6, the effect of the ejection speed of fuel particles from the burner nozzle on the residence time of fixed fuel particles in the furnace is as follows: As the ejection speed from the nozzle becomes faster, the fuel particles It is known that the residence time of Conventionally,
When the load decreased, the amount of fuel injected, that is, the speed of ejection from the nozzle, decreased in proportion to the load, which reduced the swirling force of the fuel particles in the furnace, affecting the flow of particles, and causing unreacted particles to flow. The amount of scattering increased and the efficiency decreased. Therefore, it is essential for the above-mentioned reasons to maintain a certain constant fuel particle ejection speed even when the load fluctuates.

Conventional methods for maintaining a stable burner ejection speed are basically classified into the following two types.

(b) A method of mechanically adjusting the outlet diameter of the differential coal supply pipe and adjusting the jetting speed (described in JP-A-54-94126 and JP-A-55-17060);
(b) There is a method of adjusting the jetting speed by adjusting the amounts of the fuel conveying gas and the gasifying agent. (stomach)
The advantage of method (2) is that the outlet diameter of the pulverized coal supply pipe is determined by using mechanical means, so the jetting speed can be determined accurately.The advantage of method (2) is that the mechanism is simple and easy to operate. That's true.

[Problem that the invention seeks to solve]

In gasifying solid fuel, it is generally necessary to reduce the amount of fuel transport gas required to transport powdered solid fuel. Generally, inert gas (N ₂ or CO ₂ , etc.) is used as coal conveyance gas.
If the amount is large, it will suppress the rise in temperature inside the furnace.
adversely affects reaction. For this reason, it is necessary to reduce the amount of conveying gas, which inevitably increases the density of the powdered solid fuel in the multiphase flow. Therefore, if the above (a) is used, it is possible that the fuel supply pipe outlet diameter adjustment part may be rubbed. Further, since the outlet diameter adjusting rod is provided in the fuel supply pipe, it has a negative effect on the supply of solid fuel itself, and has the disadvantage that powdered solid fuel may accumulate in the supply pipe or block the outlet.

In the method (b) above, the mechanism is simple and the operation is easy, but if the flow rate is adjusted by the amount of conveying gas, there is a lower limit to the flow rate for conveying the powdered solid fuel, and if the flow rate is lower than this, the conveyance of the powdered solid fuel will be difficult. becomes impossible. Therefore, each method has a quantitative limitation and cannot cope with a wide range of load fluctuations.

SUMMARY OF THE INVENTION An object of the present invention is to provide a powder solid fuel injection burner suitable for maintaining a constant burner injection speed even when the load fluctuates by discharging powder solid fuel from a burner nozzle with a small diameter.

[Means for solving problems]

The present invention provides a gasifier that gasifies powdered solid fuel by thermally decomposing it at high temperatures, a nozzle that supplies a mixture of the powdered solid fuel and a carrier gas to the gasifier, and a region around the nozzle outlet. a plurality of gasification agent supply pipes disposed in the supply pipes, flow path cutoff valves provided in at least two of the supply pipes, and driving the flow path valves of the supply pipes to control the supply amount of the gasification agent; The present invention relates to a gasification apparatus having means for.

The gasifier of the present invention includes means for detecting the amount of gasifying agent supplied to the gasifier, and means for opening and closing the flow path cutoff valve based on the detection signal, and controlling the amount of gasifying agent supplied. be able to.

[Effect]

The number of gasifying agent jet holes provided circumferentially around the powder solid fuel nozzle outlet can be controlled by adjusting the flow path cutoff valve installed at the gasifying agent supply port in front of the burner to adjust the amount of gasifying agent according to load fluctuations. By operating accordingly and increasing or decreasing the number of ejection holes, the gasifying agent ejection speed can be maintained constant. Powdered solid fuel is
The amount of ejection is reduced accordingly, and the ejection speed is reduced accordingly. After the powdered solid fuel particles whose ejection speed has been reduced are ejected from the powdered solid fuel outlet hole, they are driven by a gasifying agent whose ejection speed is constant and which is ejected from the gasifying agent ejection hole provided around the outlet hole. It is accelerated by the ejection speed of the curing agent. Therefore, the velocity of the powdered solid fuel particles is also maintained constant.

〔Example〕

This embodiment is an apparatus for supplying powdered coal to a high-pressure gasification furnace. This will be explained with reference to FIGS. 1 to 5.

The burner consists of a burner body and a gasifying agent supply device. The burner body is provided in the center,
A pulverized coal blowing nozzle 33 having a pulverized coal nozzle outlet hole 14 at one end, and two gasifying agent blowing holes 15 disposed around the pulverized coal blowing nozzle in parallel to the axial direction of the nozzle 33 . ~18
four gasifying agent supply pipes 19 to 22 with The cooling jacket 13 is provided in a shape and has cooling water inlet and outlet pipes 11 and 12. The gasifying agent supply device includes a flow rate control valve 30, a gasifying agent conveying pipe 23 connected to the flow rate controlling valve, gasifying agent branch pipes 24 to 27 branching from the conveying pipe 23, and gasifying agent branch pipes. flow path cutoff valves 2 to 5 connected to the flow path cutoff valves; and connected to the flow path cutoff valves;
The other end of the gasifying agent supply ports 6 to 9 is connected to the gasifying agent supply pipes 11 to 22 of the burner body, and the opening degree of the flow rate regulating valve is detected, thereby controlling the flow path cutoff valves 2 to 5. and a valve control device that controls the operation.

The pulverized coal blowing nozzle 33 has an outer diameter of 6 mm and an inner diameter of 4 mm, and the inner diameter of the pulverized coal nozzle outlet hole 14 is also 4 mm. The gasifying agent supply pipes 19 to 22 have an outer diameter of 8 mm and an inner diameter of 6 mm, and two gasifying agents each having an inner diameter of 1.0 mm are placed symmetrically with respect to the pulverized coal nozzle outlet hole 14 and on the same circumference. Spout hole 15
~18. The gasifying agent protection tube 10 has an outer diameter of 32
mm, the outer diameter of the cooling jacket is 48 mm, and the length is
It was set to 500mm.

The pulverized coal is supplied to the pulverized coal blowing nozzle as a multiphase flow with the conveying gas, and is ejected from the pulverized coal nozzle outlet hole 14 . The gasifying agent (air) passes through the flow rate control valve 30, passes through the gasifying agent conveying pipe 23, and is divided into four directions: gasifying agent branch pipes 24 to 27, flow path cutoff valves 2 to 5, and gasifying agent supply port. 6 to 9 to the gasifying agent supply pipes 19 to 22 of the burner body. The gasifying agent that has entered the gasifying agent supply pipe branches into two directions that are symmetrical with respect to the pulverized coal nozzle exit hole, and then is ejected from the gasifying agent jetting holes 15 to 18. This gasifying agent accelerates the pulverized coal ejected from the pulverized coal nozzle outlet hole 14, mixes it, and brings it into contact with the outside to gasify it. Cooling water is supplied from the cooling water inlet 11, cools the burner through the cooling water passage 29, and flows out from the cooling water outlet 12.

When the load on the gasifier changes, the amount of pulverized coal and gasification agent fed changes accordingly. The amount of gasifying agent fed is controlled by a flow control valve 30. The valve control device detects the opening degree of the flow control valve 30, and opens and closes the corresponding flow path cutoff valve in a predetermined order according to the opening degree.

The above-mentioned burner is connected to the gasification reaction part of the gasification furnace (inner diameter
300mm, height 750mm), four units were installed in the tangential direction near the upper stage. A load fluctuation test was conducted using this device under the following conditions.

A: The gasifying agent is air.

B: Pulverized coal supply amount is 30Kg/H at 100% load C: Ratio of air supply amount to pulverized coal supply amount (hereinafter referred to as AIR/
COAL ratio) is set to 4.

D: The operating pressure is 4Kg/cm ² G.

E: Investigate carbonization efficiency and cold gas efficiency by changing the pulverized coal supply amount while keeping the AIR/COAL ratio constant.F: Perform the same test using a conventional burner.

FIG. 7 is a diagram showing this result. When using a conventional burner, when the pulverized coal supply rate was 30 kg/h, the carbon gasification efficiency ηc was 92% and the cold gasification efficiency ηg was 57%, but with a constant AIR/COAL ratio, the load was reduced to 50%. When the load was reduced, both ηc and ηg decreased by about 3 to 5% compared to when the load was 100%. The cause is 50% load
If the flow rate is lowered to , the flow rate of the gasifying agent will be halved, and the gasifying agent jetting speed at the gasifying agent nozzle will be halved, so the residence time of pulverized coal particles in the gasifier will be shortened. This is thought to be due to an increase in the amount of chir scattering.

On the other hand, when using the burner of the present invention,
When the load was reduced to 50%, two of the four flow path cutoff valves installed at the gasifier supply port were closed, reducing the number of gasifier nozzles used from eight to four.
Therefore, the gasifying agent jetting speed at 50% load is approximately
At 214 m/s, the same ejection speed as at 100% load is obtained, and the gasification agent accelerates the pulverized coal particles whose ejection speed has decreased due to the reduced load, increasing the residence time in the gasifier to 100% load. It is said to be about the same level as the time. As a result, the carbon gasification efficiency ηc and cold gas efficiency ηg at 50% load were both almost the same as at 100% load, indicating that the present invention is effective against load fluctuations. There is.

[Effects of the Invention] According to the present invention, in a powder solid fuel gasifier, it is possible to maintain the efficiency of the gasifier even when the load fluctuates, which is effective in expanding the use of coal.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the powdered solid fuel injection burner according to the present invention, FIG. 2 is a perspective view showing the arrangement of the gasifying agent supply pipe in the embodiment of the present invention, and FIG. 4 is a diagram showing the arrangement of the powdered solid fuel outlet hole and the gasifying agent nozzle according to the embodiment of the present invention, and FIG. 5 is a system diagram of the embodiment of the present invention. Figure 6 is a diagram showing the influence of burner ejection speed on the residence time of solid fuel particles.
The figure is a diagram showing a comparison of the load fluctuation characteristics of a conventional burner and a burner according to the present invention. 2-5...Flow path cutoff valve, 14...Powdered solid fuel (pulverized coal) outlet hole, 15-18...Gasifying agent injection hole, 24-27...Gasifying agent supply pipe, 31...Valve control Device, 33... Powdered solid fuel (pulverized coal) blowing nozzle.

Claims (1)

[Claims] 1. A gasifier that gasifies powdered solid fuel by thermally decomposing it at high temperatures; a nozzle that supplies a mixture of the powdered solid fuel and a carrier gas to the gasifier; and the nozzle. a plurality of gasification agent supply pipes disposed around the outlet; a flow path cutoff valve provided in at least two of the supply pipes; and a flow path of the supply pipes for controlling the supply amount of the gasification agent. A gasifier comprising means for driving a valve. 2. The gasification device according to claim 1, further comprising means for detecting the amount of gasification agent supplied to the gasification furnace, and means for opening and closing the flow path cutoff valve based on the detection signal. Device.