JP2013024522A - Method for control of exhaust heat recovery equipment in sintered ore cooling machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for control of exhaust heat recovery equipment, capable of preventing the amount of generated steam from exceeding rated volume, by controlling the amount of steam generated in a boiler installed in the exhaust heat recovery equipment without changing the cooling capacity of a sintered ore cooling machine.SOLUTION: The sintered ore cooling machine 1 includes: a cooler pan 10 which moves sintered ore supplied onto an upper surface from an ore supply part toward an ore discharge part; an air blowing duct 11 which is located below the cooler pan 10 and supplies cooling gas; and an exhaust duct 12 which is located above the cooler pan 10 and recovers exhaust gas. The method is provided for controlling the exhaust heat recovery equipment 2, which exchanges heat of exhaust gas recovered by the exhaust hood 12 with water supplied from a water supply system and supplies the heat-exchanged exhaust gas as cooling gas to an air blowing duct 11 in the sintered ore cooling machine, and in which a boiler 20 for generating steam is installed. The method is characterized by controlling the amount of generated steam to below the rated capacity of the exhaust heat recovery equipment 2 by adjusting the pressure of the steam generated by the boiler 20.

Description

  The present invention relates to a method for controlling exhaust heat recovery equipment in a sinter cooler. Specifically, without changing the cooling capacity of the sinter cooler, the amount of steam generated by the boiler installed in the exhaust heat recovery facility can be controlled to prevent the steam generation from exceeding the rated capacity. The present invention relates to a method for controlling a heat recovery facility.

  A high-temperature sintered cake is discharged from a sintering machine used for producing the sintered ore, and this sintered cake is crushed by a crusher disposed downstream of the sintering machine to become a sintered ore. Since the sinter obtained in this way has a high temperature, a sinter cooler (hereinafter also simply referred to as “cooler”) is used to cool the sinter. As the cooler, a cooler pan that moves the sintered ore supplied to the upper surface from the supply portion to the discharge portion, a blower duct that is located below the cooler pan and supplies cooling gas, and a cooler pan A cooler provided with an exhaust hood that is located above and collects exhaust gas can be used.

  Such a cooler generally includes an exhaust heat recovery facility as an energy saving measure, and a boiler is installed in the exhaust heat recovery facility. In the boiler of the exhaust heat recovery facility, the temperature of exhaust gas from the cooler is lowered by heat exchange with water to form a cooling gas and steam is generated. The cooling gas lowered in temperature by the boiler is returned to the cooler again, and the generated steam is sent to the power generation turbine and used for power generation.

  However, the production volume of sintered ore has increased in accordance with the recent steel demand, and accordingly, the exhaust gas amount of the cooler has also increased. For this reason, in the boiler of the exhaust heat recovery facility, the amount of steam generated tends to increase to near the rated capacity of the exhaust heat recovery facility. As a result, when the production of sintered ore temporarily increases, the amount of steam generated may momentarily exceed the rated capacity.

  The generation of steam in the boiler exceeding the rated capacity of the exhaust heat recovery facility causes equipment failure and is also regulated by laws and regulations. On the other hand, if the amount of steam generated in the boiler is significantly lower than the rated capacity, the amount of power generated in the power generation turbine will be significantly reduced, so it is desirable that the amount of steam generated be as close to the rated capacity as possible. It is desirable that it is 90% or more with respect to the capacity, that is, near the rated capacity. Accordingly, a method for stably controlling the amount of steam generated near the rated capacity while preventing the generation of steam exceeding the rated capacity has been required in the exhaust heat recovery facility.

  In the production of sintered ore, various proposals have conventionally been made, for example, as shown in Patent Documents 1 and 2, regarding a method for controlling an exhaust heat recovery facility in which a boiler is installed. Patent Document 1 discloses a method of controlling the rotational speed of a blower installed for circulating a cooling gas in a sinter cooler. In the blower rotation speed control method disclosed in Patent Document 1, the blower is arranged in the path of the cooling gas from the boiler to the blower duct, and the blower is rotated according to the calculation result based on the actual rotation speed of the blower and the power cost. Control the number. According to the blower rotation speed control method described in Patent Document 1, it is possible to perform control that maximizes the recovery profit of the entire exhaust heat recovery facility.

  Patent Document 2 discloses a method for controlling exhaust heat recovery equipment in a sintering machine that manufactures a sintered cake. Patent Document 2 discloses a control method for exhaust heat recovery equipment that removes dust from exhaust gas exhausted from a sintering machine and exhaust gas that has passed through the boiler. In an exhaust heat recovery facility composed of an electrostatic precipitator, the amount of exhaust gas supplied to the boiler is controlled so that the exhaust gas temperature at the inlet of the electrostatic precipitator falls within a certain range. In Patent Document 2, the amount of exhaust gas supplied to the boiler is adjusted by providing a flow rate adjusting damper.

  As a result, the exhaust heat recovery equipment control method disclosed in Patent Document 2 is such that the exhaust gas temperature at the inlet of the electrostatic precipitator falls within a certain range, and no ignition or condensation occurs in the electrostatic precipitator. It is said that it is possible to recover all the heat except for the amount of heat necessary to secure the exhaust gas temperature at the inlet of the gas within the control value.

  When the steam generation amount of the boiler installed in the exhaust heat recovery facility exceeds the rated capacity, as disclosed in Patent Document 1, if the rotation speed of the blower that circulates the cooling gas is controlled to be low, the boiler Since the amount of exhaust gas supplied to the boiler decreases, the amount of heat input to the boiler via the exhaust gas can be reduced. Further, as disclosed in Patent Document 2, the amount of heat input to the boiler via the exhaust gas can also be reduced by operating the flow rate adjusting damper to reduce the amount of exhaust gas supplied to the boiler. . Thus, by reducing the amount of exhaust gas supplied to the boiler and reducing the amount of heat input to the boiler via the exhaust gas, the amount of steam generated can be controlled below the rated capacity.

  However, if the amount of exhaust gas supplied to the boiler is reduced by controlling the number of rotations of the blower to lower the speed or operating the flow rate adjusting damper, the amount of cooling gas in the cooler is also reduced accordingly. For this reason, since the cooling capacity of the cooler is reduced and the sintered ore discharged is insufficiently cooled, the high-temperature sintered ore is discharged from the cooler and carried onto the subsequent belt conveyor. The risk of damage to the belt conveyor increases.

  In order to avoid the problem that the belt conveyor is damaged by the high temperature sintered ore, a method of forcibly cooling by spraying water on the high temperature sintered ore on the belt conveyor is conceivable. However, in this method, cracks and cracks are generated in the sintered ore due to stress concentration and increase in internal stress in the sintered ore rapidly cooled by water spray. As a result, the strength of the sintered ore is reduced, and the deterioration of the quality of the sintered ore becomes a problem.

JP-A-61-246329 Japanese Patent Application Laid-Open No. 64-68429

  As described above, in the waste heat recovery equipment of the sinter cooler, a method for stably controlling the amount of generated steam near the rated capacity while preventing the generation of steam exceeding the rated capacity has been required. However, like the conventionally disclosed control method of exhaust heat recovery equipment, adjusting the number of rotations of the blower or operating the flow rate adjustment damper can control the steam generation amount of the boiler below the rated capacity, Since the cooling gas amount is reduced by the cooler and the cooling capacity is lowered, a high temperature sintered ore is discharged from the cooler to cause a problem.

  The present invention has been made in view of such a situation, without changing the cooling capacity of the sinter cooler, to control the amount of steam generated in the boiler installed in the exhaust heat recovery equipment, An object of the present invention is to provide a method for controlling exhaust heat recovery equipment that can prevent the amount of steam generated from exceeding the rated capacity.

The present inventor conducted various tests in order to solve the above problems, and as a result of intensive studies, the inventors have obtained the knowledge shown in the following (a) and (b).
(A) Steam pressure generated in the boiler when the exhaust heat recovery equipment in the sinter cooler is in an aspect where the boiler steam generation exceeds the rated capacity due to an increase in the amount of sinter supply to the cooler To control the amount of steam generated by the boiler. Thereby, the amount of steam generation can be controlled below the rated capacity without changing the cooling capacity of the cooler.

(B) a water supply system to the boiler, from a deaerator for heating the water to remove the gas, a feed water preheating device for preheating the degassed water, and the water and deaerator supplied to the deaerator A water supply system is provided that includes a water supply recooler that exchanges heat with discharged water. Between the deaerator and the feed water preheater of this feed water system, a recooling line passing through the feed water recooler and a bypass line for directly supplying the water discharged from the deaerator to the feed water preheater are provided. In such a heat recovery system with a water supply system, the amount of water passing through the bypass line is adjusted when the amount of steam generated by the boiler exceeds the rated capacity due to an increase in the amount of sintered ore supplied to the cooler. . Thereby, the steam generation amount of the boiler can be controlled below the rated capacity without changing the cooling capacity of the cooler.

  The present invention has been completed on the basis of the above findings, and the gist of the control method of the exhaust heat recovery facility in the sinter cooler of the following (1) and (2).

(1) A cooler pan that moves the sintered ore supplied to the upper surface from the supply portion toward the discharge portion, a blower duct that is located below the cooler pan and supplies cooling gas, and the cooler pan In a sinter cooler equipped with an exhaust hood that is located above and collects exhaust gas,
The exhaust gas collected by the exhaust hood is heat-exchanged with water supplied from a water supply system and supplied to the air duct as a cooling gas, and exhaust heat recovery equipment in which a boiler for generating steam is installed is controlled. A method,
A method for controlling an exhaust heat recovery facility in a sinter cooler, wherein the pressure of steam generated by the boiler is adjusted to control a steam generation amount to be equal to or less than a rated capacity of the exhaust heat recovery facility.

(2) a cooler pan that moves the sintered ore supplied to the upper surface from the supply portion toward the discharge portion, a blower duct that is located below the cooler pan and supplies cooling gas, and the cooler pan In a sinter cooler equipped with an exhaust hood that is located above and collects exhaust gas,
The exhaust gas collected by the exhaust hood is heat-exchanged with water supplied from a water supply system and supplied to the air duct as a cooling gas, and exhaust heat recovery equipment in which a boiler for generating steam is installed is controlled. A method,
The water supply system is exhausted from a deaerator that superheats water to remove gas, a water supply preheating device that preheats the degassed water, water supplied to the deaerator, and the deaerator A water recooler that exchanges heat with water,
Provided between the deaerator and the feed water preheater are a recooling line that passes through the feed water recooler and a bypass line that directly supplies water discharged from the deaerator to the feed water preheater. ,
A method for controlling exhaust heat recovery equipment in a sinter cooler, wherein the amount of steam generated by the boiler is controlled to be equal to or less than a rated capacity of the exhaust heat recovery equipment by adjusting an amount of water passing through the bypass line. .

  The control method of the exhaust heat recovery facility of the present invention adjusts the pressure of steam generated by a boiler or the amount of water passing through the bypass line in a water supply system provided with a recooling line and a bypass line. As a result, the control method of the exhaust heat recovery facility of the present invention can be applied to the cooling machine even if the steam generation amount of the boiler exceeds the rated capacity due to an increase in the amount of sintered ore supplied to the cooling machine. Without changing the cooling capacity, the steam generation amount of the boiler can be controlled below the rated capacity.

It is a schematic diagram which shows the outline | summary of the waste heat recovery equipment of the sinter cooler which this invention makes object. It is a figure which shows the heat balance in the normal operation state of an Example. It is a figure which shows the heat balance in the state which changed the production amount of the sintered ore by the comparative example 1 of the Example. It is a figure which shows the heat balance in the state which changed the production amount of the sintered ore by the comparative example 2 of the Example. It is a figure which shows the heat balance in the state which changed the production amount of the sintered ore by this invention example 1 of the Example. It is a figure which shows the heat balance in the state which changed the production amount of the sintered ore by this invention example 2 of the Example.

  Below, the control method of the waste heat recovery equipment of this invention is demonstrated, referring drawings.

  FIG. 1 is a schematic diagram showing an outline of exhaust heat recovery equipment of a sinter cooler targeted by the present invention. The figure shows a sintering machine 4 that ignites a raw material layer formed on a moving hearth and produces a sintered cake 6 by a sintering action, and a crusher 5 that crushes the sintered cake 6 into a sintered ore 7. A cooler 1 that cools the high-temperature sintered ore 7, a waste heat recovery facility 2 that recovers heat from the high-temperature exhaust gas of the cooler 1, and a water supply system 3 that supplies water to the exhaust heat recovery facility 2 Indicates. Also, in the figure, the piping that supplies cooling gas or exhaust gas in the direction indicated by the arrow is indicated by a solid line arrow, the piping that supplies water in the direction indicated by the arrow is indicated by a one-dot chain line, and steam is supplied in the direction indicated by the arrow. The pipes for supplying are indicated by broken arrows.

  The cooler 1 includes a cooler pan 10 that moves the sintered ore 7 supplied to the upper surface from the supply portion 1a toward the discharge portion 1b, and an air duct that is positioned below the cooler pan 10 and supplies cooling gas. 11 and an exhaust hood 12 that is located above the cooler pan 10 and collects exhaust gas.

  A boiler 20 and a circulation fan 25 are installed in the exhaust heat recovery facility 2. The boiler 20 lowers the temperature of the high-temperature exhaust gas collected by the exhaust hood 12 by heat exchange with water supplied from the water supply system 3, supplies the cooling exhaust gas to the blower duct 11, and generates steam from the water.

  That is, the cooler 1 is fed with the high-temperature sintered ore 7, and while the sintered ore 7 moves on the cooler pan 10 from the feed unit 1a to the discharge unit 1b of the cooler (the hatching in the figure is performed). The cooling gas (usually air) is blown upward from below into the sintered ore 7 from the blower duct 11. Thereby, the high temperature sintered ore 7 is cooled and the cooling gas is heated. The heated cooling gas is recovered as exhaust gas by the exhaust hood 12 and then supplied to the boiler 20 through a pipe for exhaust heat recovery. Thereafter, the heated cooling gas is sent as cooling gas to the blower duct 11 by the circulation fan 25 for circulation use. Is done.

  The boiler 20 shown in the figure is composed of an evaporator 21 and a superheater 22, and the boiler 20 is provided with a steam drum 23. The water supplied to the boiler from the water supply system 3 is temporarily stored in the steam drum 23 and then supplied to the evaporator 21 and becomes steam by heat exchange with the exhaust gas. The generated steam is supplied to the steam drum 23 to separate the remaining water, and only the steam is supplied to the superheater 22. The steam supplied to the superheater 22 is secondarily superheated by heat exchange with the exhaust gas, and the temperature rises to become high-temperature steam. Thus, the steam generated in the boiler 20 is sent to a power generation turbine (not shown) and used for power generation.

  In the exhaust heat recovery facility 2 shown in the figure, a pressure regulating valve 24 is provided on the outlet side of the boiler 20 (superheater 22), and the pressure of the steam generated in the boiler 20 is adjusted by operating the pressure regulating valve 24. Is possible.

  A water supply system 3 shown in the figure is discharged from a water supply pit 30 for storing water, a deaerator 31 for overheating water to remove gas, and water supplied to the deaerator 31 and the deaerator 31. A feed water recooler 33 for exchanging heat with water and a feed water preheater 32 for preheating the degassed water. In this water supply system 3, a recooling line passing through the feed water recooler 33 and water discharged from the deaerator 31 are directly connected between the deaerator 31 and the feed water preheater 32. And a bypass line for supplying to 32 is provided.

  In such a water supply system 3, the water in the water supply pit 30 is supplied to the deaerator 31 and a part of the steam generated in the boiler 20 is supplied via the steam drum 23. Thereby, the water supplied from the water supply pit 30 is overheated to about 130 ° C., for example, and dissolved gas in the water is removed. The water deaerated in this way is supplied to the feed water preheater 32 and heated, and then supplied to the steam drum 23 provided in the boiler 20.

  At this time, the water recooler 33 is supplied with water superheated by the deaerator 31, and is supplied with normal temperature water from the water supply pit 30. For this reason, in the feed water recooler 33, the water superheated in the deaerator 31 is cooled by heat exchange, and is supplied to the feed water preheater 32 at about 50 ° C., for example. The temperature is raised and supplied to the deaerator 31.

  Further, a bypass line is provided between the deaerator 31 and the feed water recooler 33, and a part of the degassed water is directly reheated without being recooled by the feed water recooler 33. The structure can be supplied to the container 32. The bypass line is provided with a water amount adjusting valve 34, and by operating the water amount adjusting valve 34, the amount of water passing through the bypass line can be adjusted.

  In the feed water preheater 32 shown in the figure, degassed water is supplied via a recooling line or a bypass line, and is recovered by an exhaust hood 12 arranged on the side of the cooler 1 on which the mineral is removed. Exhaust gas is supplied. If water thus deaerated and a part of the exhaust gas are supplied to the feed water preheater 32 and the water is superheated by heat exchange, the water can be preheated while recovering heat from the exhaust gas of the cooler 1. it can. Thus, in the exhaust heat recovery facility, by providing the feed water preheater 32, heat exchange between the exhaust gas and water, which is mainly performed in the boiler, can be assisted.

  In the water supply system 3 shown in the figure, a water supply recooler 33 is provided. In this case, the degassed water is supplied to the feed water preheater 32 and the boiler 20 after being cooled by heat exchange in the feed water recooler 33. For this reason, the temperature difference between the heat exchange object in the feed water preheater 32 and the boiler 20, that is, the exhaust gas of the cooler, and the water supplied to the feed water preheater 32 and the boiler 20 becomes large. Thereby, the heat quantity can be efficiently recovered from the exhaust gas of the cooler by the feed water preheater 32 and the boiler 20. In addition, by using the feed water recooler to raise the temperature of the water supplied from the feed pit and supplying it to the deaerator, it is possible to reduce the amount of steam used for heating to about 130 ° C. with the deaerator.

  However, there is an exhaust heat recovery facility where the water supply system is not equipped with a water recooler. If the amount of heat that can be recovered by the boiler is relatively large relative to the amount of heat of the exhaust gas of the cooler, that is, if the total area of the heat exchange section of the boiler is large, the amount of heat of the exhaust gas of the cooler can be sufficiently recovered by the boiler. When such a boiler is used, it is not necessary to increase the temperature difference between the water and the exhaust gas of the cooler in the boiler, so the feed water recooler is not necessarily required. When the feed water recooler is not equipped, the degassed water is directly supplied to the feed water preheater 32, and after heat exchange with the exhaust gas of the cooler, the heat of the exhaust gas is recovered and heated, and then the boiler Supplied to the steam drum.

  With the exhaust heat recovery equipment in such a cooler, the steam generation rate is stabilized near the rated capacity while preventing the generation of steam exceeding the rated capacity of the exhaust heat recovery equipment by the control method of the exhaust heat recovery equipment of the present invention. The method of controlling automatically will be described below.

  One embodiment of the control method of the exhaust heat recovery facility of the present invention includes a cooler pan 10 that moves the sintered ore supplied to the upper surface from the supply section toward the exhaust section, and a position below the cooler pan 10. Then, in the sintered ore cooler 1 provided with the blower duct 11 for supplying the cooling gas and the exhaust hood 12 that is located above the cooler pan 10 and collects the exhaust gas, the exhaust gas collected by the exhaust hood 12 is In this method, heat is exchanged with water supplied from the water supply system 3 and supplied to the air duct 11 as cooling gas, and the exhaust heat recovery equipment 2 in which the boiler 20 for generating steam is installed is controlled. The amount of steam generated is controlled to be equal to or less than the rated capacity of the exhaust heat recovery facility by adjusting the pressure of the steam generated in the above. Hereinafter, this embodiment is also referred to as a “first control method”.

  In the boiler 20, when the temperature of water rises by heat exchange with the exhaust gas from the cooler 1 and reaches a temperature determined by the pressure, boiling starts and steam is generated. The temperature and pressure at which this boiling starts are referred to as saturation temperature (boiling point) and saturation pressure, respectively.

  In the first control method of the present invention, the saturation pressure is varied by adjusting the saturation pressure of the boiler by adjusting the pressure of the steam generated in the boiler 20. As a result, the steam generation amount of the boiler 20 increases and decreases, and the steam generation amount is controlled below the rated capacity by the first control method of the present invention without reducing the cooling gas amount supplied to the cooler. Can do. For example, the steam generation amount is adjusted by adjusting the pressure of steam generated in the boiler 20 according to the amount of sintered ore supplied to the cooler 1, the steam generation amount of the boiler 20, and the heat amount of the exhaust gas of the cooler 1. Can be controlled below the rated capacity of the exhaust heat recovery facility.

  In the exhaust heat recovery facility in the cooler shown in FIG. 1, the pressure of steam generated in the boiler 20 can be adjusted by operating the pressure regulating valve 24 provided on the outlet side of the boiler 20 (superheater 22). When the amount of steam generation exceeds the rated capacity due to an increase in the amount of sintered ore supplied to the cooler 1, etc., adjustment is performed to increase the pressure of the steam generated by the boiler 20 by operating the pressure adjustment valve 24. This increases the saturation temperature of the boiler 20 and increases the amount of heat necessary for generating steam, so the amount of steam generated in the boiler 20 can be reduced, and the amount of cooling gas supplied to the cooler can be reduced. The generation of steam exceeding the rated capacity can be prevented without decreasing.

  On the other hand, when the amount of steam generated by the boiler appears to be significantly lower than the rated capacity due to a decrease in the amount of sintered ore supplied to the cooler 1, the pressure adjustment valve 24 is operated to generate the boiler 20 (superheater 22). Make adjustments to reduce the pressure of the steam. As a result, the amount of heat required to generate steam by lowering the saturation temperature of the boiler 20 decreases, so the amount of steam generated by the boiler 20 can be increased, and the amount of cooling gas supplied to the cooler can be reduced. The steam generation amount can be controlled in the vicinity of the rated capacity without being reduced.

  The pressure of the steam generated by the boiler 20 (superheater 22) should be adjusted within the range between the upper limit determined by the equipment specifications and the lower limit of the pressure at which the generated steam can be used in power generation and each factory. Is preferred.

  Another embodiment of the control method of the exhaust heat recovery facility of the present invention includes a cooler pan 10 that moves the sintered ore supplied to the upper surface from the supply section toward the exhaust section, and a position below the cooler pan. Then, in the sintered ore cooler 1 provided with the blower duct 11 for supplying the cooling gas and the exhaust hood 12 that is located above the cooler pan 10 and collects the exhaust gas, the exhaust gas collected by the exhaust hood 12 is A method of controlling the exhaust heat recovery equipment 2 in which a boiler 20 for generating steam is supplied to the air duct 11 through heat exchange with water supplied from the water supply system 3 and supplied as a cooling gas. 3 is discharged from the deaerator 31 that superheats water to remove gas, the feed water preheater 32 that preheats the degassed water, and the water supplied to the deaerator 31 and the deaerator 31 Water supply re-exchanges heat with water And a recooling line that passes through the feed water recooler 33 and water discharged from the degasser 31 directly to the feed water preheater 32. A supply bypass line is provided, and the amount of steam generated in the boiler 20 is controlled to be equal to or less than the rated capacity of the exhaust heat recovery facility by adjusting the amount of water passing through the bypass line. Hereinafter, this embodiment is also referred to as a “second control method”.

  The water preheater 32 and the boiler 20 are supplied with water that has passed through the recooling line and water that has passed through the bypass line. In the second control method of the present invention, by adjusting the amount of water passing through the bypass line, the water supplied to the feed water preheater 32 and the boiler 20 and the water passing through the bypass line and the water passing through the bypass line are adjusted. Change the ratio.

  Here, the water that has passed through the bypass line is heated to about 130 ° C. by the deaerator, and the water that has passed through the re-cooling line is re-cooled by the heat exchange in the feed water re-cooler and lowered in temperature. . For this reason, the temperature of the water supplied to the feed water preheater 32 and the boiler 20 can be changed by adjusting the amount of water passing through the bypass line. When the temperature of the water supplied to the feed water preheater 32 and the boiler 20 varies, the amount of steam generated in the boiler 20 increases or decreases according to the variation.

  As described above, the second control method of the present invention controls the amount of steam generated below the rated capacity without reducing the amount of cooling gas supplied to the cooler by adjusting the amount of water passing through the bypass line. be able to. For example, the steam generation rate is rated by adjusting the amount of water passing through the bypass line according to the amount of sintered ore supplied to the cooler 1, the steam generation amount of the boiler 20, and the heat amount of the exhaust gas of the cooler 1. It can be controlled below the capacity.

  In the exhaust heat recovery facility in the cooler shown in FIG. 1, the amount of water passing through the bypass line can be adjusted by operating the water amount adjustment valve 34 provided in the bypass line. When the amount of steam generation exceeds the rated capacity due to an increase in the amount of sintered ore supplied to the cooler 1, etc., adjustment is made to reduce the amount of water passing through the bypass line by operating the water amount adjustment valve 34. As a result, the water supplied to the feed water preheater 32 and the boiler 20 increases in the proportion of water that has been re-cooled through the re-cooling line and the proportion of water that has been overheated through the bypass line. Since it decreases, the temperature of the water supplied to the feed water preheater 32 and the boiler 20 falls. As a result, since the amount of heat necessary for generating steam increases, the steam generation amount of the boiler 20 can be reduced, and the rated capacity is exceeded without reducing the amount of cooling gas supplied to the cooler. Steam generation can be prevented.

  On the other hand, when the amount of steam generated by the boiler is substantially below the rated capacity due to a decrease in the amount of sintered ore supplied to the cooler 1, the water amount adjustment valve 34 is operated to increase the amount of water passing through the bypass line. Make adjustments. As a result, the water supplied to the feed water preheater 32 and the boiler 20 has a reduced ratio of water that has been re-cooled through the re-cooling line and a ratio of water that has been overheated through the bypass line. Since it increases, the temperature of the water supplied to the feed water preheater 32 and the boiler 20 rises. As a result, the amount of heat necessary for generating steam is reduced, so that the amount of steam generated in the boiler 20 can be increased, and the steam near the rated capacity can be reduced without reducing the amount of cooling gas supplied to the cooler. The amount generated can be controlled.

  As described above, in the control method of the exhaust heat recovery facility of the present invention, both the first and second control methods are charged into the boiler 20 through the exhaust gas without reducing the amount of the cooling gas supplied to the cooler 1. The steam generation amount of the boiler 20 can be controlled with the same amount of heat being generated. For this reason, the control method of the exhaust heat recovery equipment of the present invention can control the steam generation amount of the boiler 20 without changing the cooling capacity of the cooler 1. Therefore, the control method of the exhaust heat recovery facility of the present invention does not cause problems such as insufficient cooling of the sintered ore exhausted from the cooler and deterioration of the quality of the sintered ore forcedly cooled by water spray.

  In order to verify the effect of the control method of the exhaust heat recovery facility of the present invention, the following test was performed.

[Test method]
In this test, the exhaust heat recovery equipment in the cooler shown in Fig. 1 changes the amount of sintered ore production (the amount of ore supplied to the cooler) from the normal operating state, and balances after the change. The heat balance at the time of the state was investigated. The rated capacity of the exhaust heat recovery equipment used in this test was 34.0 t / h.

FIG. 2 is a diagram showing a heat balance in a normal operation state. In the figure, portions that are not particularly necessary when explaining the heat balance are omitted. As shown in the figure, in a normal operation state (sintered ore production amount is 270 t / h), the temperature of the sintered ore discharged from the cooler 1 is 70 ° C., and the cooling gas amount of the cooler is 380. , 000 Nm ³ / h, the pressure of steam generated by the boiler was 0.7 MPa, and the amount of water passing through the bypass line was 17.0 t / h. In this state, the steam generation amount of the boiler 20 was 34.0 t / h, which was a value equal to the rated capacity. From this normal operating state, the production of sintered ore was changed to 280 t / h in this test.

In Comparative Example 1, in order to maintain the temperature of the sintered ore discharged from the cooler 1 at 70 ° C., the cooler according to the production amount of the sintered ore (the amount of the ore supplied to the cooler) The amount of the cooling gas was adjusted and changed from 380,000 Nm ³ / h to 410,000 Nm ³ / h. Further, in Comparative Example 2, in order to prevent the steam generation amount of the boiler 20 from exceeding the rated capacity by keeping the amount of heat input to the boiler 20 through the exhaust gas constant, the cooling gas amount of the cooler is set to 380,000 Nm. ³ / h was maintained, and the amount of cooling gas relative to the amount of sintered ore supplied was reduced.

  In the present invention example 1, in order to control the steam generation amount of the boiler 20 in the vicinity of the rated capacity, the pressure regulating valve 24 is operated according to the production amount of sintered ore, and the pressure of the steam generated by the boiler is reduced from 0.7 MPa. Increased to 0.9 MPa. Further, in the present invention example 2, in order to control the steam generation amount of the boiler 20 in the vicinity of the rated capacity, the water amount adjustment valve 34 is operated according to the production amount of the sintered ore, and the amount of water passing through the bypass line is reduced to 17.0 t. / H to 10.0 t / h.

  In both the inventive example and the comparative example, when the temperature of the sintered ore exhausted from the cooler exceeds 70 ° C., the belt conveyor into which the exhausted sintered ore is carried is prevented from burning out. The discharged ore was forcedly cooled to 70 ° C. or less by watering.

[Evaluation criteria]
The obtained sintered ore was allowed to cool to room temperature, and the cold strength of the sintered ore was evaluated using the rotational strength TI (+5 mm) defined in JIS M 8712.

[Test results]
3-6 is a figure which shows the heat balance in the state which changed the production amount of the sintered ore, FIG. 3 is the comparative example 1, FIG. 4 is the comparative example 2, FIG. 5 is this invention example 1, FIG. Indicates the heat balance of Example 2 of the present invention. In FIGS. 3-6, the part which is not especially required when demonstrating a heat balance was abbreviate | omitted.

Table 1 shows normal operating conditions, test conditions and results of Comparative Examples 1 and 2 and Invention Examples 1 and 2, respectively. The test conditions and test results shown in Table 1 show the generation amount (t / h), temperature (° C.), pressure (MPa), and saturation temperature (° C.) at the pressure for the steam generated in the boiler. In addition, regarding the cooler, the production amount of sintered ore (t / h), the amount of cooling gas (Nm ³ / h) and the amount of exhaust gas (Nm ³ / h), as well as the supply section and exhaust section of the cooler Shows the temperature (° C) of the sintered ore.

  For the boiler, the temperature of the supplied exhaust gas (° C), the temperature of the discharged cooling gas (° C), the amount of water supplied (t / h), the amount of water passed through the recooling line (t / h), and the bypass line The amount of water passed (t / h), the temperature of water supplied to the boiler (° C.), and the pressure of the steam drum (MPa) are shown. Furthermore, about the sintered ore discharged | emitted from the cooler, the presence or absence of forced cooling by watering and cold strength TI (%) are shown.

3 to 6 and Table 1, in Comparative Example 1, the cooling gas amount of the cooling machine was adjusted according to the production amount of the sintered ore and changed from 380,000 Nm ³ / h to 410,000 Nm ³ / h. . As a result, the temperature of the sintered ore exhausted from the cooler was maintained at 70 ° C., but the amount of heat supplied to the boiler via the exhaust gas increased, so the steam generation amount of the boiler was 36.0 t. / H and exceeded the rated capacity.

In Comparative Example 2, since the amount of steam generated in the boiler 20 is controlled below the rated capacity by making the amount of heat input to the boiler 20 through exhaust gas constant, the amount of cooling gas in the cooler is 380,000 Nm ³ / The amount of the cooling gas with respect to the supply amount of the sinter was decreased. As a result, the steam generation amount of the boiler was 34.0 t / h, which was below the rated capacity, but the temperature of the sintered ore discharged from the cooler exceeded 70 ° C. and became 90 ° C.

  For this reason, forced cooling by watering was performed on the sintered ore discharged from the cooler, and as a result, the cooling strength TI of the sintered ore was 76.5%. As shown in Table 1, in the normal operating state, Comparative Example 1, Invention Example 1 and Invention Example 2, without forced cooling by watering, the cooling strength TI of the sintered ore is 78%. From these results, it was confirmed that the strength of the sintered ore was reduced when forced cooling by watering was performed.

In Example 1 of the present invention, the pressure of the steam generated in the boiler was increased from 0.7 MPa to 0.9 MPa. As a result, the steam saturation temperature of the boiler increased from 160 ° C. to 170 ° C., and the steam generation amount of the boiler became 34.0 t / h, thereby preventing the rated capacity from being exceeded. At this time, in order to secure the cooling capacity of the cooler, similarly to Comparative Example 1, the amount of cooling gas of the cooler was adjusted according to the production amount of sintered ore, and from 380,000 Nm ³ / h to 410,000 Nm ³ / H. As a result, the temperature of the sintered ore discharged from the cooler could be maintained at 70 ° C., and forced cooling by watering was not performed.

  Here, in Example 1 of the present invention, the conditions regarding the amount of water in the feed water recooler, the recooling line, and the bypass line are not changed from the normal operation state. For this reason, even if it is the waste heat recovery equipment which is not equipped with the feed water recooler, it is considered that the same effect as Example 1 of the present invention can be obtained by applying the first control method of the present invention. It is done.

In Example 2 of the present invention, the amount of water passing through the bypass line is reduced from 17.0 t / h to 10.0 t / h, and accordingly, the amount of water passing through the recooling line is changed from 17.0 t / h to 24.0 t / h. Increased. As a result, the temperature of the water supplied to the feed water preheater is lowered from 90 ° C. to 70 ° C., and the temperature of the water supplied to the boiler is lowered from 110 ° C. to 90 ° C. As a result, the steam generation amount is reduced to 34.0 t. / H. At this time, in order to secure the cooling capacity of the cooler, similarly to Comparative Example 1, the amount of cooling gas of the cooler was adjusted according to the production amount of sintered ore, and from 380,000 Nm ³ / h to 410,000 Nm ³ / H. As a result, the temperature of the sintered ore discharged from the cooler could be maintained at 70 ° C., and forced cooling by watering was not performed.

  That is, in the present invention example 2, by reducing the amount of water passing through the bypass line, the amount of water supplied to the feed water recooler (the amount of water passing through the recool line) is increased, and the water supplied to the feed water preheater and the boiler is increased. Decrease the temperature. As a result, the calorific value of the exhaust gas recovered by the feed water preheater and the boiler is increased as the calorific value of the exhaust gas of the chiller increases as the production of sintered ore increases. It was possible to prevent the generated amount from exceeding the rated capacity.

  From these, the first and second control methods of the present invention control the amount of steam generated in the boiler installed in the exhaust heat recovery facility without changing the cooling capacity of the sinter cooler, It became clear that the generation amount can be prevented from exceeding the rated capacity.

  The control method of the exhaust heat recovery facility of the present invention adjusts the pressure of steam generated by a boiler or the amount of water passing through the bypass line in a water supply system provided with a recooling line and a bypass line. As a result, the control method of the exhaust heat recovery facility of the present invention can be applied to the cooling machine even if the steam generation amount of the boiler exceeds the rated capacity due to an increase in the amount of sintered ore supplied to the cooling machine. Without changing the cooling capacity, the steam generation amount of the boiler can be controlled below the rated capacity.

  Therefore, if the control method of the exhaust heat recovery equipment of the present invention is applied to the production of sintered ore, it is possible to prevent the steam generation amount from exceeding the rated capacity while responding to the change in the production amount of the sintered ore. As a result, it is possible to prevent the exhaust heat recovery equipment from malfunctioning beyond the rated capacity, or the high temperature sintered ore from being discharged from the cooler and the equipment to be burned out. Can be manufactured. Such a control method for exhaust heat recovery equipment of the present invention is useful for the production of sintered ore.

1: Sinter cooler, 10: Cooler pan, 11: Air duct,
12: exhaust hood, 1a: supply section, 1b: exhaust section, 2: exhaust heat recovery equipment,
20: Boiler, 21: Evaporator, 22: Superheater, 23: Steam drum,
24: Pressure regulating valve, 25: Circulating fan, 3: Water supply system, 30: Water supply pit,
31: Deaerator, 32: Feed water preheater, 33: Feed water recooler, 34: Water quantity adjustment valve,
4: Sintering machine, 5: Crusher, 6: Sintered cake, 7: Sinter ore, 8: Steam

Claims (2)

A cooler pan that moves the sintered ore supplied to the upper surface from the supply section toward the discharge section, a blower duct that is positioned below the cooler pan and supplies cooling gas, and is positioned above the cooler pan In a sinter cooler equipped with an exhaust hood that collects exhaust gas,
The exhaust gas collected by the exhaust hood is heat-exchanged with water supplied from a water supply system and supplied to the air duct as a cooling gas, and exhaust heat recovery equipment in which a boiler for generating steam is installed is controlled. A method,
A method for controlling an exhaust heat recovery facility in a sinter cooler, wherein the pressure of steam generated by the boiler is adjusted to control a steam generation amount to be equal to or less than a rated capacity of the exhaust heat recovery facility. A cooler pan that moves the sintered ore supplied to the upper surface from the supply section toward the discharge section, a blower duct that is positioned below the cooler pan and supplies cooling gas, and is positioned above the cooler pan In a sinter cooler equipped with an exhaust hood that collects exhaust gas,
The exhaust gas collected by the exhaust hood is heat-exchanged with water supplied from a water supply system and supplied to the air duct as a cooling gas, and exhaust heat recovery equipment in which a boiler for generating steam is installed is controlled. A method,
The water supply system is exhausted from a deaerator that superheats water to remove gas, a water supply preheating device that preheats the degassed water, water supplied to the deaerator, and the deaerator A water recooler that exchanges heat with water,
Provided between the deaerator and the feed water preheater are a recooling line that passes through the feed water recooler and a bypass line that directly supplies water discharged from the deaerator to the feed water preheater. ,
A method for controlling exhaust heat recovery equipment in a sinter cooler, wherein the amount of steam generated by the boiler is controlled to be equal to or less than a rated capacity of the exhaust heat recovery equipment by adjusting an amount of water passing through the bypass line. .

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