JPS62255707A - Reheat steam-temperature control method - Google Patents

Abstract

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

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for controlling the temperature of reheated steam in a boiler, and in particular, the present invention relates to a method for controlling the temperature of reheated steam in a boiler, and in particular, the present invention relates to a method for controlling the temperature of reheated steam in a boiler, and in particular, The present invention relates to a reheat steam temperature control method that can increase the reheat steam temperature by 1III2D without affecting NOx control in exhaust gas in a system that reheats fuel in a boiler.

[Prior Art] A boiler plant is explained with reference to FIG. 5. A is a boiler, which consists of a furnace that forms a combustion chamber, and a heat transfer section C that is connected to the exhaust gas volume section of the furnace. A fuel economizer d, a heater e, and a superheater f are provided in the furnace and the heat transfer section C,
A reheater 9 is provided in the heat transfer section C.

The feed water passes through the energy saver d, the heater C1, and the superheater in that order, is heated, becomes main steam, and is supplied to the high-pressure turbine h.
After driving the pressure turbine h, the heat is supplied to the reheater q, where it is reheated and then supplied to the low pressure turbine i.

Conventionally, in order to control the temperature of reheated steam leaving the reheater Q, a part of the exhaust gas leaving the heat transfer section C is returned to the inlet side of the furnace using a circulation fan J, as shown in Fig. 3. In the GRF method (gas recirculation fan method), as shown in Fig. 4, the exhaust gas flow path of the heat transfer section C is partitioned into two, and a reheater 9 is provided in one of the flow paths. The parallel damper system in which the amount of exhaust gas flowing to the path Ct, Oz is controlled by the dampers kl, 2, and the above G,,l? There are methods such as combining the F method.

[Problems to be Solved by the Invention] However, when the exhaust gas leaving the heat transfer section C is returned to the furnace in order to control the reheated steam temperature in the reheater Q, combustion in the furnace is caused by circulating exhaust gas suspension. Affected by NOX (Nitrogen 11!
! Monster) There is a problem that the seedlings can't be controlled.

The present invention has been made in consideration of the above circumstances, and aims to provide a reheat steam temperature control method that does not affect the combustion in the boiler and can control the reheat steam temperature in the reheater. purpose.

[Means and effects for solving the problems] In order to achieve the above object, the present invention provides a reheater in the heat transfer section at the rear of the furnace of the boiler, and transfers the main steam generated in the boiler to the high-pressure turbine. In the reheating steam temperature control method in which the supplied and discharged steam is supplied to the reheater and reheated with exhaust gas from the furnace passing through the heat transfer section, the exhaust gas exiting the heat transfer section is A part of the above-mentioned furnace is circulated between the outlet of the furnace and the inlet of the heat transfer section. By circulating the exhaust gas exiting the heat transfer section in the upstream exhaust gas flow path, the reheated steam temperature in the reheater can be vI 1m, and since the exhaust gas is circulated downstream of the combustion section of the furnace, This allows NOx control and reheat steam temperature control to be performed separately and easily without affecting combustion.

[Example] Hereinafter, an example of the reheat steam i 1m tlJ 98 method according to the present invention will be described based on the accompanying drawings.

Fig. 1 shows an example in which the present invention is applied to the above-mentioned GIIF system. It consists of a heat transfer section 5 connected via a heat transfer section 4.

The furnace 2 and the heat transfer section 5 are provided with a coal saver 6, an evaporator 7, and a superheater 8, and the heat transfer section 5 is provided with a reheater 9.

A water supply pipe 10 is connected to the economizer 6, and a heater 7 and a superheater 8 are connected in this order from the economizer 6, and a pressure turbine 12 is connected to the superheater 8 via a main steam line 11. The steam exhaust line 13 is connected to the reheater 9, and the reheater 9
A reheat steam line 14 from the is connected to a low pressure turbine 15, and an exhaust line 16 is connected to the low pressure turbine 15.

The exhaust gas combusted in the lower part of the furnace 2 passes through the connection part 4 from the outlet part 3, passes through the reheater 9 in the heat transfer part 5 from the inlet part 5a of the heat transfer part 5, and is discharged from the exhaust gas line 17.

A circulation fan (GRF) is connected to this exhaust gas line 17.
18 is connected, and the recirculation line 1 is connected to the circulation fan 18.
The lower part of the furnace 2 is connected through the two. Further, a reheat line 20 is connected to the circulation fan 18, and the reheat line 20 is connected 8 to an arbitrary point between the outlet section 3 of the furnace 2 and the inlet section 58 of the heat transfer section 5. A damper 21 is provided in the recirculation line 19 and the reheat line 20 to control the exhaust gas flow rate, respectively.
．． 22 are connected.

In the above, the feed water is heated while passing through the economizer 6, the heater 7, and the superheater 8, becomes main steam, enters the ^-pressure turbine 12 from the main steam line 11, rotates the high-pressure turbine 12, and generates electricity. Steam discharged from the high-pressure turbine 12 is supplied to the reheater 9 through a steam line 13, reheated by exhaust gas passing through the heat transfer section 5, and supplied to the low-pressure turbine 15 through a reheat steam line 14.

The temperature of the reheated steam supplied to the low pressure turbine 15 is controlled by a damper 21 so that the NOx temperature does not change by 11 degrees from the circulation fan 18 through the recirculation line 19 with respect to the boiler load.
At the same time, the opening degree of the damper 22 of the reheat line 2o is controlled, and the exhaust gas circulating to the reheater 9 is controlled to control the reheat steam temperature tII+.

In this case, the exhaust gas from the recirculation line 19 is mainly No.
The exhaust gas from the reheat line 20 can be used as a circulation layer to control the reheating temperature, so the reheat steam temperature can be controlled while controlling the NOx 13 degrees. Easy to control.

FIG. 2 shows another embodiment of the present invention, in which the present invention is applied to the GRF method and the parallel damper method.

In this example, the heat transfer section 5 is partitioned into two flow paths 24a and 24b by a partition wall 23, one of the flow paths 24a is provided with a reheater 9, and both flow paths 24a and 24b are provided with a reheater 9. Dampers 25a and 25b are provided to control the exhaust gas flow rates in the flow paths 24a and 24b.

In this example as well, one circulation fan is connected to the exhaust gas outlet section 5b of the heat transfer section 5 by branching into the exhaust gas line 17.
A recirculation line 19 that circulates exhaust gas to the furnace 2 is connected to the circulation fan 18, and a reheat line 20 that circulates the exhaust gas between the outlet section 3 of the furnace 2 and the inlet section 58 of the heat transfer section 5.
are connected to each line 19.20, and a damper 21.2 is connected to each line 19.20.
2 is connected.

In the embodiment shown in FIG. 2, the damper 25a of the heat transfer section 5
, 25b can control the amount of exhaust gas flowing into each flow path 24a, 24b, and can control the amount of exhaust gas circulating to the reheat im 9 through the reheat line 20, allowing more accurate reheat temperature control.

[Effects of the Invention] As is clear from the above detailed description, the present invention exhibits the following excellent effects.

(1) In order to control the reheated steam temperature in the reheater of the heat transfer section, the exhaust gas discharged from the heat transfer section is circulated between the outlet of the furnace and the input section of the heat transfer section. Therefore, the reheat steam temperature can be controlled without affecting combustion in the furnace.

(2) Even if the reheat steam temperature is controlled, combustion in the furnace is not affected, so the NOXvIllil can be easily achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the present invention, FIG. 2 is a diagram showing another embodiment of the present invention, FIG. 3 is a diagram showing a conventional example, and FIG. 4 is a diagram showing another conventional example. Figure 5 shows the third
It is an overall view of the boiler plant shown in the figure. In the figure, 1 is a boiler, 2 is a furnace, 3 is an outlet part, 5 is a heat transfer part, 5a is an inlet part, 9 is a reheater, 12 is a high-pressure turbine,
17 is an exhaust gas line, 18 is a circulation 11 fan, and 2o is a reheat line. Patent Applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Representative Patent Attorney: Nobuo Kinuya Figure 3 Figure 4

Claims (1)

[Claims] A reheater is installed in the heat transfer section behind the furnace of the boiler, and the main steam generated in the boiler is supplied to the high-pressure turbine, and the exhausted steam is supplied to the reheater and reheated with exhaust gas from the heat transfer section. A reheat steam temperature control method characterized in that a part of the exhaust gas exiting the heat transfer section is guided between an outlet section of the furnace and an inlet section of a heat transfer section at the rear of the furnace. Control method.