JP2012052673A - Method and device for automatic blow control of boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overheat of a water tube during boiler combustion at a high load by successfully performing an automatic blow according to an operation state of a boiler having a variable load.SOLUTION: In automatic blow control of the boiler, two portions from the steam separator 2 of the boiler and from the lower header 3 of the boiler are formed as positions for extracting blow water from a boiler body 1, and the positions for extracting the blow water are selectively switched according to the operating state of the boiler. In this case, the positions for extracting the blow water are switched to blow extraction from the steam separator 2 from a high combustion (100%) load to an intermediate combustion (to 30%) load, and to blow extraction from the lower header 3 at a low combustion (30-10%) load.

Description

  The present invention relates to an automatic blow control method and apparatus for providing two positions for taking out blow water from a boiler body in automatic blow control of a boiler and changing the position for taking out blow water according to the operating load of the boiler.

  A general boiler has one blow-off position. In the once-through boiler of the applicant company as well, removal from the steam separator is the standard (in the case of other companies, many are taken from the return pipe from the steam separator to the main body). This is because the boiler can water is heated in the water pipe of the boiler body to become steam and concentrated boiler can water, which is led to the steam separator through the steam connecting pipe in a gas-liquid two-layer state. In the separator, it is separated into steam and concentrated drain, the steam is sent out of the boiler, and the concentrated drain water is accumulated in the steam-water separator.

  Thus, good automatic blow control becomes possible by taking out the fully concentrated can water. For this reason, it is supposed to take out blow water from the said part. Concentrated can water that has not been taken out as blow water is mixed with boiler feed water at the lower part of the steam separator and is supplied to the boiler body through a return pipe.

In response to recent needs for energy saving and CO ₂ reduction, there is an increasing need for boilers to increase the combustion turndown ratio (ratio between maximum combustion amount and minimum combustion amount). When the turndown ratio is increased, the boiler does not stop even when the steam load is reduced, and as a result, there is an advantage that energy loss due to ON-OFF of the boiler is reduced, leading to energy saving.

  However, on the boiler side, the ratio of the liquid layer of the gas-liquid two-layer flow supplied to the steam separator decreases as the boiler combustion load is lower. For this reason, a difference in concentration occurs between the boiler water in the steam separator and the boiler water pipe / headlet. Since this difference in concentration becomes larger as the amount of combustion in the boiler is smaller, it is difficult to manage the boiler can water with good concentration by taking out the blow from the steam separator. In other words, expansion of the boiler turndown ratio requires improvement of the boiler automatic blow control method.

  Although related patents were investigated, no patents were found that changed the location of the blow-out water taken out by the boiler load. A general once-through boiler supplies water to the lower header and takes out blow water from the return pipe. In addition, the combustion control is sufficiently supplied from the HI-LOW control with a turndown ratio of 2: 1 to the steam separator.

  Moreover, although patent applications for blow from the lower header (can low blow) are also seen, there is no relevance to automatic blow and no relation to boiler load. The main purpose is to prevent flashing and can overheating.

JP 2001-165403 A JP 2002-323202 A JP 10-61904 A

  The problem to be solved is that good automatic blow cannot be performed depending on the operating condition of the boiler whose load fluctuates.

  Therefore, in the present invention, a route for taking out the automatic blow water from the lower header is newly added. The boiler can water in the lower header is relatively less susceptible to changes in the can water concentration due to boiler low-load combustion. ing. However, when the blow water is taken out from the lower header, it becomes difficult to supply water to the boiler water pipe, and the water pipe may be overheated particularly during high-load combustion of the boiler.

  In consideration of these points, the present invention prepares two locations for taking out the blow water for the automatic blow control of the boiler, that is, the steam separator and the lower header, and the boiler according to the load condition of the boiler. The main feature is that automatic blow from the steam separator is performed as usual in the case of a load from the middle to the high load, and the automatic blow from the lower header is switched when the boiler load is low.

  In addition, in order to monitor the leakage of blow water from the lower header, a temperature sensor that detects the flow rate is attached to the blow piping from the lower header, and the position where the blow water from the lower header is taken out is the thermal load of the boiler. Add features such as mounting on the low boiler exhaust gas outlet side.

  In the present invention, in the automatic blow control device for a boiler, two positions for taking out blow water from the boiler body are provided, and the position for taking out blow water is changed depending on the operation load state of the boiler. In this case, the blow pipes are joined in the middle, and the solenoid valve for automatic blow control, the blow cooler, and the orifice for adjusting the blow flow rate are shared.

  The boiler automatic blow control method of the present invention is the boiler automatic blow control method, wherein the blow water take-out position from the boiler body is provided at two locations, from the boiler water separator and from the boiler lower header, It is characterized by selecting and switching the position where the blow water is taken out depending on the operation status of the boiler.

  In this method, the blow water removal position is switched from the steam / water separator from high combustion (100%) load to intermediate combustion (~ 30%) load, and low combustion (30% to 10%). The load is taken out from the lower header.

  The boiler automatic blow control device of the present invention is the boiler automatic blow control device, in which the blow water extraction position from the boiler main body is provided at two locations, from the boiler water separator and from the boiler lower header, It is characterized in that the position for taking out blow water can be selected according to the operating condition of the boiler.

  In this device, the blow water removal position from the lower header is the farthest (opposite side) position relative to the inlet position of the return water flowing into the lower header via the return pipe from the steam separator. The position where the blow water is taken out from the lower header or the position where the blow water is taken out from the lower header is the position where the blow water is taken out from the lower header portion on the boiler exhaust gas outlet side where the heat load of the boiler water pipe is low.

  In these apparatuses, it is desirable that the blow pipes taken out from two locations are joined, and the blow pipe after joining is provided with a blow cooler, an automatic blow solenoid valve, and a flow rate adjusting orifice.

  In these devices, the blow pipe from the steam separator of the boiler and the blow pipe of the lower header are connected via a new blow pipe, and the connection point between the new blow pipe and the blow pipe of the steam separator It is desirable to provide a blow switching valve and a temperature sensor for monitoring blow leak from the lower header in the new blow pipe to ensure the safety of the boiler body.

  The method and apparatus of the present invention have the advantage that automatic blowing can be performed satisfactorily in accordance with the operating conditions of the boiler whose load varies. Moreover, the overheating at the time of high load combustion of a boiler can be prevented.

FIG. 1 is an explanatory diagram showing the configuration of an example of an automatic blow control device for a boiler according to the present invention. FIG. 2 is an example of a sectional view taken along line AA in FIG. FIG. 3 is another example of a sectional view taken along line AA in FIG.

  The purpose of performing the automatic blow in the boiler satisfactorily has been realized by making the blow-off water into two locations, the steam separator and the lower header.

  1 shows an embodiment of an automatic blow control device for a boiler according to the present invention, FIG. 2 shows an example of a cross section taken along the line AA in FIG. 1, and FIG. 3 shows a cross section taken along the line AA in FIG. Another example is shown. In the boiler automatic blow control device shown in FIG. 1, two locations for taking out the blow water from the boiler body 1 are provided, from the steam separator 2 of the boiler and from the lower header 3 of the boiler. The position where the blow water is taken out can be selected. 4 is an upper header and 5 is a boiler water pipe.

  As shown in FIG. 2, the take-off position of the blow water from the lower header 3 is the inlet of the return water flowing into the lower header via the return pipe 6 from the steam / water separator 2 to the lower header 3. The blow water is taken out from the lower header 3 (right side in FIG. 1) on the farthest side (opposite side) with respect to the position. 7 is a blow pipe from the lower header.

  In addition, as shown in FIG. 3, the blow water extraction position from the lower header 3 may be a position for extracting blow water from the lower header 3 portion on the boiler exhaust gas outlet 8 side where the boiler water pipe has a low thermal load. is there.

  As shown in FIG. 1, a blow pipe 10 from a boiler steam separator 2 and a blow pipe 7 from a lower header 3 are connected via a new blow pipe 11. A blow switching valve 12 (a three-way valve as an example) is provided at a location where the water separator 2 is connected to the blow pipe 10, and a temperature sensor 13 for monitoring blow leak from the lower header 3 is attached to the new blow pipe 11. It is configured to ensure the safety of the boiler body. This temperature sensor 13 is connected to a control panel (not shown). Reference numeral 14 denotes a controller.

  As described above, the blow pipes taken out from two places are joined together, and the blow cooler 16, the automatic blow solenoid valve 17, and the flow orifice blow orifice 18 are provided in the blow pipe 15 after joining. 20 is a water supply pump, 21 and 22 are water supply pipes, 22 is a drain valve, 24 and 25 are stop valves, 26 is a steam communication pipe, 27 is a burner, and 28 is an air duct.

  As described above, in the configuration in which the blow water extraction position from the boiler body 1 is provided at two locations, from the boiler air / water separator 2 and from the boiler lower header 3, the blow water is discharged depending on the operation status of the boiler. Select the position to take out and switch. As an example, the blow water take-out position is switched from the high water (100%) load to the intermediate combustion (~ 30%) load by taking out the blow from the steam / water separator 2 and low combustion (30% to 10%). The load is taken out from the lower header 3.

  Depending on the operating condition of the boiler whose load fluctuates, automatic blow can be performed satisfactorily, and in particular, overheating of the water pipe during high load combustion of the boiler can be prevented.

1 Boiler body 2 Air / water separator 3 Lower header 4 Upper header 5 Boiler water tube 6 Return pipe 7 Blow piping from lower header 8 Boiler exhaust outlet 10 Blow piping from steam / water separator 11 New blow piping 12 Blow switching Valve 13 Temperature sensor 14 Controller 15 Blow piping after merging 16 Blow cooler 17 Automatic blow solenoid valve 18 Blow orifice for flow control 20 Water supply pump 21, 22 Water supply pipe 23 Drain valve 24, 25 Stop valve 26 Steam communication pipe 27 Burner 28 Air duct

Claims (7)

  In the automatic blow control method of the boiler, there are two locations for taking out the blow water from the boiler body, from the boiler's steam separator and from the bottom of the boiler. An automatic blow control method for a boiler characterized by selecting and switching.   2. The automatic blower for a boiler according to claim 1, wherein the blow water take-out position is switched from a steam / water separator from a high combustion load to an intermediate combustion load and from a lower header at a low combustion load. Control method.   In the automatic blow control device for boilers, two locations for taking out blow water from the boiler body are provided, one from the boiler's steam separator and the other at the bottom of the boiler. An automatic blow control device for a boiler, characterized in that it can be selected.   Blow water is taken out from the lower header farthest from the inlet position of the return water flowing into the lower header via the return pipe from the steam separator as the position for taking blow water from the lower header. The automatic blow control device for a boiler according to claim 3, wherein the automatic blow control device is located.   The automatic blow control device for a boiler according to claim 3, wherein the blow water is taken out from the lower header as a position for taking out blow water from a lower header portion on the boiler exhaust gas outlet side where the heat load of the boiler water pipe is low.   The automatic blow control device for a boiler according to claim 3, 4 or 5, wherein blow pipes taken out from two places are joined, and a blow cooler, an automatic blow solenoid valve, and a flow rate adjusting orifice are provided in the blow pipe after joining.   Connect the blow pipe from the boiler's steam / water separator and the blow pipe of the lower header through the new blow pipe, and connect the blow switch valve to the connection point between the new blow pipe and the blow pipe of the steam / water separator. An automatic blow control device for a boiler according to any one of claims 3 to 6, further comprising a temperature sensor for monitoring blow leak from the lower header in the new blow pipe to secure the safety of the boiler body. .

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