JPH01167501A - Boiler device - Google Patents

Abstract

PURPOSE:To restrict a variation of a fluid enthalpy at an inlet of a gas-water separator by a method wherein a stopper valve is arranged in a main pipe passage over an over-heating thermal conducting part, and communication pipes communicating with the main pipe passage and the gas-water separator through a stopper valve at an outlet/inlet port are arranged at an upstream side and a downstream side of the stopper valve. CONSTITUTION:In case that there are a large amount of thermal absorption in an evaporating part (mainly, a furnace water pipe) during a circulating operation, a main pipe passage 20 and a gas-water separator 4 are connected by a first inlet communicating pipe 10 and a first outlet communicating pipe 11 arranged at an inlet port of a primary over-heater 5 (an over-heating thermal conducting part). In case that the amount of absorption of heat at the evaporating part is reduced due to a changing-over to a different type of fuel or an adhesion of ashes to a furnace thermal conducting surface and an enthalpy of fluid at an inlet port of the gas-water separator 4 is decreased, second inlet communicating pipe 14 and second outlet communicating pipe 15 arranged at an outlet port of the primary over- heater 5 are used and the gas-water separator 4 and the main pipe passage 20 are connected, and then the fluid is circulated from the main pipe passage 20 to the gas-water separator 4. In this case, the over-heater 5 may function as an evaporation heat conducting part, the amount of thermal absorption at the reduced evaporation part is accommodated and no reduction in the enthalpy of fluid at the inlet port of the gas-water separator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boiler device, and particularly to a boiler device suitable for adjusting the enthalpy of fluid at the inlet of a steam-water separator.

[Conventional technology]

Boilers that operate at intermediate loads must be designed with a low minimum operating load, but in general, as the load decreases in boilers, the flow rate in the tubes decreases, and in the case of wood tubes in furnaces, which are exposed to the severest heat load, the cooling effect of the tubes decreases. This is insufficient and the temperature of the tube wall tends to rise. Therefore, at high loads, once-through operation is performed, but below a certain load (minimum once-through load), circulation operation is performed in which the flow rate flowing through the furnace wood is kept constant (minimum flow rate). I will explain.

During circulation operation, the boiler feed water is heated in the evaporative heat transfer section such as the wood pipes 2 in the furnace, and then separated into steam and water in the steam separator 4. The steam is sent to the superheaters 5 to 7, and the water is sent to the circulation pump. 9 and returned to the entrance of the economizer 1.

It is operated to maintain the flow rate flowing into the furnace water pipe 2 at the minimum flow rate.

In order to smoothly perform this switching operation between circulation operation 8 and once-through operation, it is necessary to arrange the heat transfer surface so that the fluid at the inlet of the steam-water separator becomes saturated steam at the lowest once-through load, as shown in Figure 2. be.

By the way, the heat transfer surface of the boiler is divided into two parts, an evaporation part and a superheating part, by this steam-water separator, and the heat absorption ratio of the two parts varies greatly depending on the fuel used. For example, in the case of gas, the amount of heat absorbed by the superheating section is large, but in the case of oil, the amount of heat absorbed by the evaporation section is conversely large. In addition, in the case of one coal, the heat absorption rate in the superheating section and the evaporation section varies greatly depending on the degree of adhesion of ash to the heat transfer surface of the furnace or the difference in combustibility between brands of coal.

Therefore, in the conventional fluid path configuration shown in Fig. 3, if different fuels are used as described above, if the contamination state of the heat transfer surface changes during coal burning, or if a different brand of coal is used. When the combustibility changes, the enthalpy of the inlet fluid of the steam/water separator 4 changes significantly, making it difficult to switch between circulation operation and once-through operation.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology did not give sufficient consideration to the enthalpy fluctuation of the fluid at the inlet of the steam-water separator, and therefore had the following problems.

During once-through operation, if the evaporator absorbs a large amount of heat and the fluid at the inlet of the steam-water separator becomes superheated steam, the water cannot be separated in the steam-water separator, making it impossible to shift from once-through operation to circulation operation. On the other hand, if the amount of heat absorbed by the evaporator is small and the fluid at the inlet of the steam-water separator is a steam-water mixture with high humidity, it is possible to transition from 1 once-through operation to circulation operation in step 8, but the circulation pump must not be started during the transition. Then, the water is separated in the steam separator and the fluid at the steam water separator outlet becomes saturated steam, so the heat added in the superheater is not consumed for evaporation of water, but is directly used to increase the steam temperature, and the fluid at the boiler outlet There was a problem that the steam temperature rose rapidly.

For this reason, the operability of the plant has been restricted when using multiple types of fuels with significantly different heat absorption ratios in the evaporation section and the superheating section.

An object of the present invention is to suppress fluctuations in fluid enthalpy at the inlet of a steam/water separator even if the heat absorption ratio between the evaporating section and the superheating section varies.

[Measures to solve problems]

The above problem is solved by providing a stop valve across the superheating heat transfer section in a main pipe connecting a plurality of superheating heat transfer parts in series, and connecting a connecting pipe that communicates the main pipe with the steam/water separator via an inlet/outlet stop valve. This is achieved by a boiler device provided upstream and downstream of each of the stop valves.

[Effect]

The connecting pipe between the steam separator and the main pipeline was installed downstream of the stop valves installed at multiple locations across the overheating heat transfer section of the main pipeline, so that 1ffi of the multiple connecting pipes By selecting the connecting pipe, the ratio of the heat transfer surfaces on the upstream and downstream sides of the steam separator is changed, and the heat absorption rate of the evaporation heat transfer section and superheating heat transfer section changes due to the change in the inlet fluid of the steam water separator. enthalpy fluctuations are suppressed.

[Example] Figure 1 shows the fluid path of a boiler that is an example of the present invention. In this example, there are connections connecting the steam separator and the main pipe in two places, which are the fluid path upper fittings. A tube is provided.

Energy saver 1, furnace water pipe 2, evaporator 3, and primary superheater 5
, the secondary superheater 6, and the tertiary superheater 7 are connected in this order through a main pipe 20. Secondary superheater 6 and tertiary superheater 7
A desuperheater 8 is provided between the two, and a spray water pipe 21 branched from the main pipe 20 at the entrance of the economizer 1 is connected to the desuperheater 8. Further, stop valves 18 and 19 are provided between the evaporator 3 and the primary superheater 5 and between the primary superheater 5 and the secondary superheater 60, and on the upstream and downstream sides of the stop valve 18, First population stop valve 12 and first outlet stop valve 1
The first artificial communication pipe 10 and the first outlet communication pipe 11 that communicate the main pipe line 20 and the steam/water separator 4 via the second artificial stop valve 16 are provided on the upstream and downstream sides of the stop valve 19, respectively. and a second artificial communication pipe 14 and a second outlet communication pipe 1 that communicate the main pipe line 20 and the steam water separator 4 via the second outlet stop valve 17.
5 is provided. A circulation pump 9 is provided in a circulation path 22 that connects the steam separator 4 and the main pipe 20.

During once-through operation, the feed water is heated in the energy saver 1, the furnace water pipe 2, and the evaporator 3, and then passes through the stop valve 18, 19, and is transferred to the primary superheater 5, secondary superheater 6, and tertiary superheater. It is superheated at 7 and sent to a turbine (not shown). The desuperheater 8 installed between the secondary superheater 6 and the tertiary superheater 7 suppresses fluctuations in the steam temperature at the boiler outlet by appropriately injecting the feed water extracted from the energy saver 1 as spray water to maintain the specified temperature. It has the function of supplying water to the turbine.

During circulation operation, the stop valve 18 or 19 is fully closed,
Fluid is sent to the steam-water separator 4 through the inlet connecting pipe 10 or 14 to separate steam and water.The separated steam is sent to the superheater through the outlet connecting pipe 11 or 15. On the other hand, the separated water is pressurized by the circulation pump 9 and then returned to the economizer 1, which has the function of keeping the flow rate of water supplied to the wood pipes of the furnace at the minimum flow rate.

In addition, when extracting artificial fluid from the steam/water separator 4 at the primary superheater 5, the fluid path is configured by fully opening the stop valve 18, the second exit stop valve 16, and the second outlet stop valve 17. On the contrary, 1
When taking out the fluid at the outlet of the next superheater 5, a stop valve 19;
The first stop valve 12 and the first outlet stop valve 13 are fully closed to form a fluid path.

During circulation operation, if the amount of heat absorbed by the evaporator section (mainly the furnace water pipe) is large, the main pipe 20 and the steam-water separator are connected to the main pipe 20 and the first outlet connecting pipe provided on the primary superheater 5 side. In this case, the primary superheater functions as a superheating heat transfer section as per its original function. If the amount of heat absorption in the evaporator section decreases due to switching to a different type of fuel or adhesion of ash to the heat transfer surface of the furnace, and the enthalpy of the fluid at the inlet of the steam-water separator decreases, the outlet of the primary superheater 5 2nd person outlet connecting pipe 14 installed on the side
．． 15 is used to connect the steam separator and the main line 20 to circulate fluid from the main line to the steam separator.

In this case, since the primary superheater 5 functions as an evaporative heat transfer section, the decreased heat absorption amount of the evaporator section is compensated for, and a decrease in the fluid enthalpy at the inlet of the steam/water separator is prevented.

In other words, in the case of this embodiment, the -order superheater has two functions as an original superheating heat transfer section and an evaporation heat transfer section, and can be used as an arbitrary function depending on the increase or decrease in the heat absorption amount of the boiler evaporation section (mainly the furnace water tube). By making the switch possible, fluctuations in the fluid enthalpy at the inlet of the steam/water separator can be suppressed.

〔Effect of the invention〕

According to the present invention, since the outlet from the main pipe for the steam/water mixed fluid to be introduced into the steam/water separator is provided at a plurality of locations, the range of the heat transfer section that functions as the evaporation heat transfer section can be changed to allow evaporation. It is now possible to suppress fluctuations in the enthalpy of the fluid at the inlet of the steam-water separator due to fluctuations in the amount of heat absorbed by the heat transfer section, allowing the use of different types of fuels, such as heavy oil and gas, on the heat transfer surface without restricting the operability of the boiler. It is effective in burning lime of different brands with different adhesion characteristics.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the present invention, Fig. 2 is a pressure-enthalpy diagram showing an example of heat absorption characteristics of a boiler, and Fig. 3 is a system diagram showing an example of a conventional boiler. It is a diagram. 4...Steam water separator. 5... Superheating heat transfer section (primary superheater). 6... Superheating heat transfer section (secondary superheater), 7... Superheating heat transfer section (tertiary superheater), 10.11... Communication pipe (first population, outlet communication pipe). 12.13... Inlet/outlet stop valve (first port, outlet stop valve), 14.15... Connecting pipe (second port, outlet connecting pipe)
, 16.17... Entrance/exit stop valve (second population, exit stop valve), 18.19... Stop valve, 20... Earthen pipe.

Claims (1)

[Claims] (1) A stop valve is provided in a main pipe connecting a plurality of superheating heat transfer parts in series across the superheating heat transfer part, and a connecting pipe is provided that communicates the main pipe with the steam/water separator via the inlet/outlet stop valve. A boiler device provided on the upstream side and downstream side of each of the stop valves.