JPS5843305A - Mixed pressure type waste heat recovery boiler device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixed-pressure waste heat recovery boiler that prevents steaming of low-pressure and high-pressure economizers and also prevents mutual interference between low-pressure and high-pressure boiler drums.

A waste heat boiler is placed in the exhaust gas stream to recover heat from various types of exhaust gas, including the exhaust gas generated by gas turbine power generation.In this case, a high pressure boiler and a low pressure A mixed pressure boiler with an attached boiler may be installed. FIG. 1 shows an example of a conventional mixed pressure boiler. In the figure, the water stored in the deaerator l is pumped through a main water supply pipe 15 by a low-pressure water pump 2 to a low-pressure energy saver 3.
After being heated at , it is supplied to the low pressure drum 4.

The canned water in the low-pressure drum 4 circulates through the downcomer pipe 5 and the evaporator 6, and the generated steam is sent from the drum 4 to predetermined equipment such as a low-pressure turbine as low-pressure steam. On the other hand, a portion of the canned water that has descended through the water pipe 5 is transferred to the high pressure water supply pipe 16. High pressure water pump 7
, and reaches the high-pressure drum 9 via the high-pressure economizer 8. The canned water in the high-pressure drum 9 is the same as the canned water in the low-pressure drum 4.
The generated steam circulates through the evaporator 11 and is sent to the high pressure drum 9. It passes through the superheater 12 and is supplied to equipment such as a high-pressure turbine as high-pressure steam S2.

In this type of boiler, the flow rate of the water supplied to the low-pressure economizer 3 and the high-pressure economizer 8 is adjusted by the amount of water that passes through the main water supply pipe 15, so the valve 15
If a is throttled and the water supply flow rate is reduced in response to the drop in boiler load, the pressure will be low.

Steaming occurs in each high pressure economizer 3 and δ8. In other words, the heating medium passing through each hole is
．． =6 #y In order to prevent steaming during such a load drop, it is necessary to maintain the pressure inside the economizer at a level higher than the saturation pressure with respect to the water supply temperature within the economizer. However, since the flow control valve 15a shown in FIG. 1 is disposed on the inlet side of the low-pressure economizer 3, it is impossible to adjust the pressure of the low-pressure economizer 3, and steaming cannot be prevented. Similarly, since the flow control valve 16a for the high-pressure economizer 8 is also arranged on the inlet side of the economizer, it is impossible to prevent steaming inside the high-pressure economizer 8.

Also, the high pressure drum 9 and the low pressure drum 4 are connected to a downcomer pipe 5° and a high pressure water supply line 16. Since they are in a communicating state via the high-pressure economizer 16, when the level of the high-pressure drum 9 fluctuates, the amount of canned wood taken out of the low-pressure drum 4 changes, resulting in a level fluctuation of the low-pressure drum 4. In other words, mutual interference occurs between both drums, making it extremely difficult to maintain the levels of both drums at a constant level. If this is suspected, the low pressure drum 4 may be bypassed and a pipe line 17 may be provided, but in this case, if steaming occurs in the low pressure economizer, the gas-liquid mixture will flow directly into the high pressure water supply pump 7, so the pump 7 cavitation problem also occurs.

The purpose of this invention is to eliminate the problems of the prior art mentioned above,
To provide a mixed-pressure waste heat recovery boiler that can always prevent steaming of low-pressure and high-pressure economizers regardless of the boiler load and that does not cause mutual interference between low-pressure and high-pressure boiler drums. .

In short, this invention arranges a flow rate control valve in the pipeline connecting the high-pressure, low-pressure economizer internal pressure, and low-pressure drums to adjust the flow rate of water supplied to each drum, as well as the internal pressure of the economizer, and to adjust the high-pressure water supply. Installing the pipeline without going through the low-pressure boiler downcomer pipe 6: 1. Give each of you 25 yosu. It is constructed to prevent mutual interference between the drums during supply and independently.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 18 denotes a feed water recirculation pipe, which connects the low-pressure economizer 3 and the low-pressure drum 4 to a pipe (hereinafter referred to as "low-pressure economizer outlet pipe") 19 and the deaerator 1. Connect with.

Reference numeral 20 denotes a flow rate control valve provided on the downstream side of the feedwater recirculation line branch of the low-pressure economizer outlet line 19. Reference numeral 21 denotes a flow control valve for adjusting the circulation amount, and the high-pressure water supply pipe 16 is connected to the feed water recirculation pipe 18 on the upstream side of the flow control valve 21, and is connected to the high-pressure energy saver 8 on the high-pressure boiler side as well. A high-pressure economizer outlet conduit 23 is disposed in the high-pressure drum, and a flow rate control valve 22 is provided for this conduit 23.

In the above boiler, the water stored in the deaerator 1 is stored in the low pressure feed water pump 2. Low pressure is saved through the main water supply pipe 15.

The feed water flowing into the boiler 3 and exiting the economizer 3 is transferred to the low pressure economizer outlet pipe 1 by adjusting the valve 20 according to the boiler load.
9, a predetermined amount is supplied to the boiler drum 4. In addition to adjusting the amount of water supplied to the drum 4, this flow rate regulating valve 20 also adjusts a part of the pressure inside the economizer due to water being sucked into the high-pressure water supply pipe 16, as will be described later, together with the valve 21. Prevents steaming in low pressure economizers. That is, steaming is prevented by adjusting the pressure within the low-pressure economizer and the amount of water that passes through the economizer.

The water supply reaching the low pressure drum 4 is fed to the downcomer pipe 5. The generated steam circulates through the evaporator 6 and is supplied to the low-pressure turbine as low-pressure steam S through the low-pressure drum 4. On the other hand, the water that has reached the high-pressure water supply pipe 16 is supplied to the high-pressure water supply pump 7.
After being pressurized at , it reaches the high-pressure economizer 8 . The amount of water supplied to the high-pressure drum 9 is adjusted by the high-pressure economizer outlet pipe 2.
Since this is done by adjusting the flow rate control valve 22 provided at 3, steaming within the high pressure economizer can be prevented. In other words, when the valve 22 is throttled, the amount of water that passes through the high-pressure economizer 8 decreases, and the temperature of the water supply increases, but since the valve 22 is located at the outlet of the economizer, the pressure inside the economizer also increases. death,
The economizer, ^1', maintains a pressure higher than the saturation pressure for the horse mackerel feed water temperature. In other words, if the discharge pressure of the high-pressure water supply pump 7 is appropriately adjusted, the water supply flow rate can be adjusted by the valve 22, and the internal pressure of the high-pressure economizer can be maintained at a level higher than the saturation pressure at all times.

As described above, the water that has reached the high-pressure drum 9 is supplied to the downcomer pipe 10 while preventing steaming. The generated steam is circulated through the evaporator 11 and sent to the high pressure drum 9. High pressure steam S passes through superheater 12
2 to the high pressure turbine.

FIG. 3 is a diagram showing the relationship between the outlet pressure of the economizer of the boiler according to the present invention and the outlet pressure of the conventional economizer.

In the figure, P works indicates the minimum pressure to prevent steaming of the economizer corresponding to each boiler load in the high pressure boiler.
If the pressure is lower than this, steaming will occur within the high-pressure economizer. P2 likewise indicates the minimum pressure of the steaming prevention reservoir in the low pressure boiler. 5. First, the high-pressure boiler; conventionally, the water supply control valve was placed on the inlet side of the economizer, so when the valve was throttled in response to a drop in the boiler load, the pressure inside the economizer decreased and steaming occurred. It becomes more likely to occur. P3 shows the relationship between the boiler load and the pressure inside the economizer according to the conventional method, and as is clear from this figure,
Steaming occurs when the load is less than about 75%.

Similarly, in a low pressure boiler, steaming occurs at about 70% load as shown in diagram P4.

Next, P indicates the discharge pressure of the high-pressure feed water pump of the boiler according to the present invention, and as the boiler load decreases, the flow rate control valve on the high-pressure economizer outlet side is throttled, so the discharge pressure increases. P
6 shows the high-pressure economizer outlet pressure corresponding to each boiler load, and as shown in the figure, the diagram is similar to diagram P6, and the pressure at each boiler load is reduced by the system loss.

Even if the high-pressure economizer outlet pressure P6 is always high, steaming occurs in the high-pressure economizer.Next, P8 indicates the low-pressure water pump discharge pressure, and P8 indicates the low pressure 7 economizer outlet pressure. In this case, there is no worry of steaming because the pressure in the diagram P8 is maintained higher than that in P2 over the entire boiler load range. In addition, in a low-pressure boiler, the rate of increase in the outlet pressure of the economizer when the boiler load decreases is smaller than in the case of a high-pressure boiler, but this is because part of the feed water that has passed through the low-pressure economizer 3 is 18 or to flow into the high-pressure water supply pipe 16. For this reason, a sufficient amount of feed water is always ensured through the low-pressure economizer 3 regardless of the boiler and load, and the feed water temperature is kept relatively low.In reality, the ship will be lower at each boiler load than in the case shown in the figure. Therefore, the differential pressure between P8 and each boiler load becomes larger than in the illustrated case.

By carrying out this invention, the feed water flow rate control valve is placed on the outlet side of each economizer, so it is possible to adjust the flow rate of the feed water and also adjust the pressure inside the economizer. The internal pressure can be maintained above the saturation pressure with respect to the water supply temperature of the economizer, and there is no risk of steaming.

Furthermore, since the high-pressure water supply system is installed to bypass the low-pressure drum, there is no possibility of mutual interference between the high-pressure drum and the low-pressure drum.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a conventional mixed pressure type waste heat recovery boiler, Figure 2 is a system diagram of a mixed pressure type waste heat recovery boiler according to the present invention, and Figure 3 is a system diagram of a conventional mixed pressure type waste heat recovery boiler.
The figure is a diagram showing the relationship between economizer outlet pressure and boiler load. 2...Low pressure water pump 3...Low pressure energy saver 4...Low pressure drum 7...High pressure water pump 8...High pressure energy saver Container 9... High pressure drum 16... High pressure water supply pipe 18... Water supply recirculation pipe 19... Low pressure economizer outlet pipes 20, 22 ...Flow rate control valve 23 ...High pressure energy saver 'Kame former pipeline agent patent attorney
Oka 1) Gobe

Claims (1)

[Claims] 1. In a system in which a water supply pump is installed on the water supply inlet side of a low-pressure economizer and a high-pressure economizer, the low-pressure economizer and the low-pressure drum are connected by the low-pressure economizer outlet pipe, The high-pressure economizer and the high-pressure drum are connected by a high-pressure economizer outlet pipe, and the low-pressure economizer outlet pipe and the high-pressure economizer outlet pipe have a flow rate of -
Arrangements are made to maintain the drum water level by adjusting the amount of water supplied to each high-pressure and low-pressure drum using these flow control valves, and also to reduce the pressure inside each high-pressure and low-pressure economizer over the entire boiler load range. A mixed pressure type waste heat recovery boiler device characterized in that the internal pressure of the coal boiler is maintained at a temperature higher than the saturation pressure. 2. Connect the upstream side of the flow control valve installation part of the low-pressure economizer outlet conduit and the deaerator with a feed water recirculation conduit, and supply water to the high-pressure economizer through this feed water recirculation conduit. 2. The mixed pressure waste heat recovery boiler device according to claim 1, wherein the high pressure boiler and the low pressure boiler are connected to each other to enable independent operation of the high pressure boiler and the low pressure boiler.