JPS6017626A - Purging of fuel - Google Patents

Abstract

PURPOSE:To reduce the amount of consumption of nitrogen gas by a method wherein the fuel, remaining in a fuel feeding pipe, is purged by remaining steam in a steam generator. CONSTITUTION:A steam pipe 11, sending steam from the heat transfer tube 10 of a waste heat boiler 7 to the immediately downstream of a fuel regulating valve 3 of the fuel sending pipe 9, and a steam stop valve 12 are provided in the system. The steam stop valve 12 is being closed during a normal operation and the steam is being flowed in the steam pipe 11. In such a device, when the operation is stopped, the fuel regulating valve 3 is closed but the fuel remains in the fuel sending pipe 9. Therefore, the steam stop valve 12 is opened immediately after the fuel regulating valve 3 is closed and combustion is stopped to send a part of the steam remaining in the waste heat boiler 7 into the fuel sending pipe 9 and discharge the fuel in the pipe 9 into a burner 4. When the necessary amount of steam to send the fuel is sent into the fuel sending pipe 9 and the purge of the fuel is finished, the steam stop valve 12 is closed and, thus, the purging is finished.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is a method for safely releasing fuel remaining in a fuel pipe after combustion of a fuel with a low calorific value per unit volume, such as coal gasified fuel, is stopped. It is about the method.

[Background of the invention]

FIG. 1 is a diagram showing the system of a typical coal gasification power plant. 1 is a coal gasification furnace, and 2 is a purification device for generated gas. Fuel purification device 2. The discharged gas passes through a fuel regulating valve 3 and is led to a combustor 4 of the gas turbine. 5 is a gas turbine compressor, and 6 is a turbine. High pressure air from the gas turbine compressor 5 enters the combustor 4 where it is mixed with gasified fuel and combusted to generate high temperature gas. The high-temperature gas enters the turbine 6, generates power, and then enters the waste heat recovery boiler 7, generates steam, and then is discharged from the chimney. Steam generated in the heat generating boiler 7 is guided to a steam turbine 8, where its energy is converted into power.

In such coal gasification power plants, the gas generated from the coal gasifier is either nitrogen gas in the air used as a coal gasifying agent or inert gases such as carbon dioxide generated by partial combustion of coal. Because of this, the calorific value per unit volume is 1/10 to 1/3 lower than that of high-calorie gases such as natural gas, making it a low-power or medium-calorie gas.

The table shows typical calorific values and volume values per unit calorific value of low-calorie gas generated by air oxidation in comparison with high-calorie natural gas.

In the case of a low-calorie gas, the volume per unit calorific value is about 10 times that of a high-calorie gas.

In a generator as shown in FIG. 1 which uses a fuel having a large volume per unit calorific value, the fuel delivery pipe 9 has a larger diameter than when natural gas is used. When the diameter of the delivery pipe increases in this way, when the fuel regulating valve is closed to stop the power plant, the amount of fuel remaining in the pipe from the regulating valve to the fuel nozzle is extremely small compared to the case of natural gas. There will be many.

Generally, the nozzle that burns gas fuel is always open, so a large amount of gas remaining in the fuel delivery pipe diffuses into the combustor through this opening, and the air inside the slope + 4 burner is reversed. It diffuses and mixes into the fuel delivery pipe. This creates a mixture of fuel and air, and that's it! It is a safety problem to leave it in a flooded space. For this reason, in such a combustion apparatus, it is common to use nitrogen gas immediately after the combustion apparatus is stopped to perform a purge process in which the residual fraction is forcibly lost into the combustor.

Only 1. As mentioned above, when coal gasified fuel is used, there are many residual fractions, so the amount of nitrogen gas used for purging is extremely large compared to when using natural gas.)
It becomes a necessary wave in 1i.

[Purpose of the invention]

The purpose of the present invention is to provide an economical purging method that reduces the amount of nitrogen gas used in purging such fuel delivery pipes.

[Eleven points of the invention] The present invention is based on %'! ', in a device that has a combustor that burns the fuel, a fuel delivery pipe that sends fuel to the combustor, and a valve that adjusts the two fuel flows; The fuel remaining in the delivery pipe that connects the combustor to the combustor is removed by residual steam from the steam generator connected to the combustor.

[Embodiments of the invention]

FIG. 2 is a diagram showing the purging method of the present invention.

3 is a fuel adjustment valve, 4 is a combustor, and 7 is a heat generating boiler connected to the combustor 4. Reference numeral 9 indicates a fuel delivery pipe, and 10 indicates a fuel nozzle.

A stop valve 12 is provided for sending steam from the heat transfer pipe 10 of the waste heat boiler 7 to just downstream of the fuel adjustment valve 3 of the fuel delivery pipe 9 to adjust the passage and stop of the steam.

In normal operation, gases generated in the combustor 4 are exhausted through a turbine (not shown) and a waste heat boiler 7. In the waste heat boiler 7, steam generated within the heat transfer tubes 10 is sent to a steam turbine (not shown) or the like. Steam stop valve 12
is closed during normal operation, and steam flows in the steam pipe ll.

In such a device, when the operation is stopped, the fuel adjustment valve 3 is closed, but fuel remains in the fuel delivery pipe 9. Therefore, when the fuel adjustment valve 3 is closed and the fuel arm is stopped, the steam stop valve 12 is opened. Fuel is discharged into the combustor 4.

Steam necessary for fuel delivery is sent to the fuel air pipe, and when the purge is completed, the steam 11 and valve 12 are closed to complete the purge.

〔Effect of the invention〕

According to the present invention, it is possible to effectively utilize the steam remaining in a heat generating boiler etc. after the operation is stopped, so compared to the case where nitrogen gas is used, special nitrogen storage and supply equipment is not required, and in addition, commercially available nitrogen can be used. This makes it possible to perform extremely economical purging.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a gasification power plant that gasifies coal to generate i'Q;, and FIG. 2 is a system diagram of an embodiment of the present invention. 3...Fuel adjustment valve, 4...Combustor, 7...Heating boiler, light (Figure 5T) Figure 2

Claims (1)

[Claims] 1. In a device having a combustor that burns fuel, a fuel delivery pipe that sends fuel to the combustor, and a valve that adjusts the fuel flow rate, the fuel that remains in the delivery pipe that connects the fuel adjustment valve and the combustor A fuel purging method characterized by purging with residual steam from a steam generator connected to a combustor.