JPS6116881B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method of operating a boiler device, and in particular, when hotbanking a boiler, it is possible to prevent the generation of steam in a economizer and increase the load control range of the boiler. Concerning how to operate a boiler.

As a method for recovering heat from various exhaust gases including exhaust gas generated by gas turbine power generation, there is a method of arranging a waste heat boiler in the exhaust gas flow and recovering heat. In this case, a single boiler may be placed in the exhaust gas stream, but it is more common to install a so-called mixed-pressure boiler that includes a high-pressure boiler and a low-pressure boiler in order to increase heat recovery efficiency.

However, in the above-mentioned waste heat recovery boiler, when the operating boiler is restarted after being temporarily stopped, steam is generated and accumulates in the economizer section of the boiler during the temporary stop, and this steam As a result, the applicant discovered that troubles such as water hammer occur when restarting the boiler, and the applicant is currently filing a proposal for a countermeasure for this problem in Japanese Patent Application No. 72898/1983.
The present invention relates to another means for solving the above problem. The specific contents of the present invention will be explained below with reference to the drawings.

FIG. 1 shows a mixed pressure type waste heat recovery boiler showing an embodiment of the present invention, in which water supplied in a deaerator 1 passes through a low pressure water supply pump 2 and a main water supply pipe 15 to reach a low pressure drum. Water is supplied to the low pressure drum 4 through a downcomer pipe 5 and an evaporator 6.
The generated steam is supplied as low-pressure steam _S1 to predetermined equipment such as a low-pressure turbine. Next, a portion of the water supply that has descended down down pipe 5 is transferred to pump 31 and pipe line 3.
0 to the high-pressure economizer 8, and after further increasing the temperature to a predetermined temperature, it passes through the outlet pipe 23 to the high-pressure drum 9.
leading to. The feed water in the high-pressure drum 9 circulates through the downcomer 10 and the evaporator 11, and the generated steam flows through the superheater 1.
In step 2, the temperature is further increased and the superheated steam _S2 is supplied to a predetermined device.

Of course, the operation of the boiler equipment described above is affected by the operating status of the equipment that generates waste heat, but when the boiler stops operating, maintenance must be carried out so that it can immediately respond to the next operation. There is a need. In other words, the feed water is stored in the boiler at a high temperature, resulting in so-called hot banking (hot banking).
banking) state. In this case, the temperature of the feed water in the economizer rises due to the amount of residual heat in the exhaust gas duct and the amount of heat held by the heat transfer surface to generate steam, and this steam stays in the economizer. If this steam is left as it is and the boiler is restarted, the water supply flow will become uneven, and the passage of the gas-liquid mixture will give a severe impact to the conductor tubes, causing the so-called water hammer phenomenon, and in severe cases. This will cause damage to the heat exchanger tubes.

For this reason, a method is adopted in which circulation pipes 32 and 33 are provided for both the low-pressure boiler and the high-pressure boiler, and the steam generated during hotbanking is barged to the boiler drum side using circulation pumps 34 and 35 provided in each pipe. Now, in the first embodiment, in addition to the low-pressure water supply pump 2 and the pump 31, the above-mentioned two pumps 34 and 35 are required, and a minimum of four pumps are required, which is uneconomical. In particular, the pump 31 and the circulation pumps 34 and 35 pass high-temperature, high-pressure drum water supply, so they must be special pumps, and special mechanical members are required to seal the rotating parts, further deteriorating economic efficiency. ing. Note that this problem also occurs in a waste heat single pressure recovery boiler in which only one high pressure boiler or one low pressure boiler is installed. The above problems in the embodiment shown in FIG. 1 can be solved by other embodiments of the present invention shown in FIGS. 2, 3 and 4 below.

FIG. 2 shows another embodiment of the invention, in which a waste heat recovery boiler is installed in the exhaust gas stream.
It is a single pressure type with only the base installed.
Normally, the valve 36 is open and the valve 37 is closed, and the water supply in the deaerator 1 is delivered to the energy saver 3a via the main water supply pipe 15 via the valve 36, the check valve 38, and the water supply pump 2a. The supplied water whose temperature has risen in the economizer 3a is passed through the economizer outlet pipe 19 and the valve 2.
0, flows into the boiler drum 4a, and flows into the downcomer pipe 5.
a, the vapor S is circulated through the evaporator 6a, and the vapor S generated during this period is taken out of the system and used.

Next, valve 36 is closed during hot banking of the boiler.
By opening the valve 37 and stopping the supply of water from the deaerator 1, and using the pump 2a as a circulation pump, the water supply (water) in the drum 4 is conserved via the circulation pipe 40a and the main water supply pipe 15. The steam generated in the coaler 3a is purged into the drum 4a. In this case, since the downstream part of the circulation pipe 40a is located upstream of the pump 2a installation part of the main water supply pipe 15, there is no need to separately install a pump in the circulation pipe 40a.
However, in order to circulate high-temperature boiler water, high-temperature sealing of rotating parts such as the pump shaft is required, so it is necessary to provide a special so-called immersion type pump to eliminate the difficulties caused by this sealing. During hot banking, the amount of circulating water may be small, so as shown in Figure 3, multiple water pumps (example 20) are used.
1a, 202a, 203a), one of which is 2
If 01a is an immersion type, the cost of the pump can be reduced.

FIG. 4 shows another embodiment, which is implemented in a so-called mixed pressure boiler having a high pressure drum 9 and a low pressure drum 4. The upstream side of the pump 2 a installation part of the main water supply pipe 15 that supplies water to the low pressure economizer 3 of the low pressure boiler and the lower end of the downcomer pipe 5 are connected by a low pressure circulation pipe 40 having a valve 37 . The upstream side of the valve 20 installation part of the outlet conduit 19 of the low-pressure economizer 3 and the inlet of the high-pressure economizer 8 are connected by a high-pressure water supply conduit 41. 42 is a control valve, 43 is a check valve, and 44 is a pump. 4
Reference numeral 5 denotes a high-pressure circulation pipe that connects the upstream side of the pump 44 installation part of the high-pressure water supply pipe 41 and the lower end of the downcomer pipe 10. Further, reference numeral 46 is a valve provided in the same pipe.

In the above device, during steady operation of the boiler, the valves 36, 20, 42, and 48 are open, and the valves 37 and 48 are open.
Valve 46 is kept closed. As a result, the water supplied in the deaerator 1 passes through the valve 36, the check valve 38, and the pump 2a, flows into the low-pressure economizer 3 through the main water supply pipe 15, and after being further heated to a predetermined temperature, the water is fed into the outlet pipe 19. , valve 20
to the low-pressure drum 4, downcomer pipe 5, and evaporator 6.
The generated steam is discharged as low pressure steam _S1 . On the other hand, a part of the water supply that has exited the low-pressure economizer 3 flows into the high-pressure water supply pipe 41 by adjusting the valves 20 and 42, passes through the pump 44, and then flows into the high-pressure economizer 8.
After reaching a predetermined temperature, it flows into the high-pressure drum 9 via the outlet pipe 47. Furthermore downcomer pipe 1
0, the steam generated during this period circulates through the evaporator 11, passes through the superheater 12, becomes superheated steam _S2 , and is discharged outside the system. In this case, the valves 20 and 48 adjust the pressure inside the low-pressure economizer 3 and the high-pressure economizer 8 by adjusting their opening degrees, so that the water supply is controlled by each economizer 3 and 8.
It also functions to prevent water from evaporating within the tank and to adjust the water levels in the low-pressure drum 4 and high-pressure drum 9.

Next, during boiler hot banking, valves 36 and 42
is closed, and valves 37 and 46 are opened. As a result, in the low-pressure boiler, the iron water circulates and flows in the order of the downcomer pipe 5, the low-pressure circulation pipe 40, the main water supply pipe 15, the pump 2a, the low-pressure economizer 3, the outlet pipe 19, and the low-pressure drum 4, thereby saving energy. The steam generated in the vessel 3 is barged to the low pressure drum 4 side. Similarly, in a high-pressure boiler, the boiler internal boiler water is circulated in the order of downcomer pipe 10, high-pressure circulation pipe 45, high-pressure water supply pipe 41, pump 44, high-pressure economizer 8, outlet pipe 47, and high-pressure drum 9. The steam generated in the coalizer 8 is barged to the high pressure drum 9 side.

In addition, when the boiler load increases during steady operation of the boiler, in addition to the water supplied from the deaerator 1 in the case of a low-pressure boiler, and in addition to the water supplied from the low-pressure economizer 3 in the case of a high-pressure boiler, It is also possible to cope with the increase in load by supplying the iron water in the low-pressure and high-pressure drums 4 and 9 through the respective circulation pipes 40 and 45 to increase the amount of circulating water. Note that the water supply pumps 2a and 44, which are also used for boiler water circulation, are a parallel operation type of multiple pumps shown in Figure 3, and one of them is a special pump such as an immersion pump to reduce costs. I can do it.

By implementing this invention, it is possible to prevent steam from accumulating in the economizer during hot banking, and it is possible to eliminate obstacles such as water hammer during restart. Also, Figures 2, 3, and 4
In the embodiment of the present invention shown in the figure, there is no need to install a pump in the circulation pipe, so if one boiler is installed, only one pump is installed, and even if a mixed pressure boiler is installed, two pumps are installed. This is sufficient, and even special pumps can be made smaller and have a smaller capacity by arranging them in parallel.

Further, when it is desired to increase the boiler load, the circulation pipe can also be used as a water supply pipe, so the boiler's load response range can be widened.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a waste heat recovery boiler with low-pressure and high-pressure drums showing the first embodiment of the present invention;
Fig. 3 is a system diagram of a waste heat recovery boiler showing a second embodiment of the present invention, Fig. 3 is a pipe system diagram of a water pump connected in parallel, and Fig. 4 is a system diagram of a waste heat recovery boiler according to the invention. be. 2a, 44...Pump, 3...Low pressure economizer, 3a...
Economizer, 4...Low pressure drum, 5, 5a, 10...Down pipe, 8...High pressure economizer, 9...High pressure drum, 15...Water supply pipe line, 19...Low pressure economizer outlet pipe, 20,3
6, 37, 46, 48...Valve, 40...Low pressure circulation pipe, 41...High pressure water supply pipe, 45...High pressure circulation pipe.

Claims (1)

[Claims] 1. When hotbanking a boiler in which feed water is supplied to the economizer via a pump and heated, and the heated feed water is supplied to a boiler drum that has an evaporator pipe and a downcomer pipe and communicates with each, An operating method for hot banking of a boiler, characterized in that canned water from the boiler drum is supplied to the inlet of the economizer through a circulation pipe and circulated to the boiler drum.