JP2018123993A - Boiler system, and method for operating boiler system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler system capable of reducing cost while improving boiler efficiency.SOLUTION: A boiler system includes: an air supply line for conveyance for supplying air for conveyance (primary air); an exhaust gas discharge line; an air preheater for preheating the air for conveyance flowing through in the air supply line for conveyance by the exhaust gas flowing in the exhaust gas discharge line; a detour line for connecting an upstream side and a downstream side of the air preheater in the air supply line for conveyance to cause the air for conveyance to detour the air preheater to flow; cold air amount adjustment means provided in the detour line to be able to adjust a flow amount of the air for conveyance flowing in the detour line; a mill device provided in the air supply line for conveyance; and temperature detection means for detecting at least one temperature of an exist temperature and an entrance temperature of the mill device. An opening of the cold air amount adjustment means is fixed to a prescribed intermediate opening in the case of a normal operation time with the temperature detected by the temperature detection means being within a prescribed temperature range.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a boiler system including a boiler, and more particularly, to temperature adjustment of primary air (transport air) for drying and transporting fuel.

  For example, a boiler system including a coal-fired boiler that uses coal as a fuel includes a mill device for pulverizing coal to obtain fine powder such as pulverized coal, and the pulverized fuel generated by the mill device is supplied to the mill device. The primary air (conveyance air) is conveyed to the boiler (burner) through the pulverized coal pipe. If moisture is contained in the coal and drying is insufficient, and moisture condensation occurs in the middle of transportation, it will cause pulverized coal to stick to the pulverized coal pipe, cause clogging, and affect combustion performance. May affect. For this reason, conventionally, the primary air introduced into the mill apparatus is preheated (preheated) by an air preheater (air heater) using the heat of the exhaust gas of the boiler, and the fuel is dried by the preheated air. More specifically, in the duct for supplying primary air to the mill device, a hot air damper that adjusts the flow rate of primary air (hot air) preheated by the air preheater, and a primary that is not preheated by bypassing the air preheater Adjusting the flow rate ratio of hot air and cold air by adjusting the opening degree of each cold air damper that adjusts the flow rate of air (cold air) and mixing them, the primary air that has reached the required temperature is mixed into the mill device (For example, refer to Patent Documents 1 to 3). In addition, about the water content in coal, it changes with coal types, and generally the primary air temperature supplied to a mill apparatus becomes high, so that the coal type with much moisture.

  Conventionally, the opening degree control of each of the cold air damper and the hot air damper described above is such that the temperature of the primary air at the outlet or the inlet of the mill device is constant so that the coal is properly dried by the primary air. It was performed to the target (for example, patent documents 1-2). For example, in Patent Document 1, in order to improve the heat exchange rate in the primary air preheater, the cold air damper is set to a certain value close to full closure, the flow rate of the cold air is reduced, and the outlet temperature of the mill device is constant. The opening of each damper is controlled with the goal of becoming. As a result, when the opening degree of the cold air damper is larger than the value close to the fully closed state, the amount of exhaust gas flowing into the primary air preheater is controlled in order to lower the temperature of the primary air supplied to the mill device. Reduce the opening of the gas damper. That is, the amount of energy recovered from the exhaust gas is reduced by reducing the amount of exhaust gas flowing into the primary air preheater. On the contrary, when the opening degree of the cold air damper is smaller than the value close to the fully closed state, the opening degree of the gas damper of the primary air preheater is increased in order to increase the temperature of the primary air supplied to the mill device. To do. As a result, it is possible to suppress the primary air (hot air) once preheated by the primary air preheater from being cooled with cold air, thereby improving the heat exchange efficiency in the primary air preheater and effectively using the heat quantity of the exhaust gas. It is supposed to be possible.

JP 60-105819 A Japanese Utility Model Publication No. 63-86545 JP-A-10-281453

  The temperature of the primary air at the outlet and inlet of the mill device (mill outlet temperature, mill inlet temperature) depends on the amount of water in the fuel such as coal described above, the amount of fuel supplied to the mill device, and the amount of primary air supplied. fluctuate. For this reason, in the method of adjusting the temperature of the primary air supplied to the mill device so that the mill outlet temperature becomes constant as in Patent Document 1, for example, when the types of fuel are various, the cold air described above is used. Not only the opening control of dampers, hot air dampers and gas dampers, but also the setting of the mill outlet temperature (target value) needs to be changed according to the type of fuel and the season. It becomes a cause. Also, in the environment where the temperature is low, such as in winter, the ratio of the flow rate of cold air is minimized when using the type of fuel with the largest amount of water in the fuel. If it is within the adjustment range, the flow rate of cold air increases with fuel with low moisture content, and the flow rate of primary air (hot air) passing through the air preheater decreases, so heat exchange with the air preheater The amount decreases and it is difficult to reduce the air preheater outlet gas temperature, which leads to an increase in heat loss. In addition, designing the system to ensure that the mill outlet temperature is constant under all the minimum and maximum conditions for moisture content in the fuel requires equipment that can handle a wide range of conditions. This also contributes to an increase in equipment costs and operating costs.

  In view of the above-described circumstances, at least one embodiment of the present invention aims to provide a boiler system capable of reducing cost while improving boiler efficiency.

(1) A boiler system according to at least one embodiment of the present invention includes:
A transfer air supply line for supplying transfer air for transferring fuel to the boiler;
An exhaust gas discharge line for discharging the exhaust gas generated by the combustion of the fuel inside the boiler to the outside;
An air preheater connected to each of the transfer air supply line and the exhaust gas discharge line, for preheating the transfer air flowing through the transfer air supply line with the exhaust gas flowing through the exhaust gas discharge line;
A bypass line for connecting the upstream side and the downstream side of the air preheater in the transfer air supply line, and for the transfer air to flow around the air preheater;
A cold air amount adjusting means provided in the bypass line and capable of adjusting a flow rate of the transfer air flowing through the bypass line;
A mill device for pulverizing the fuel to be supplied to the boiler, provided in the air supply line for conveyance;
Temperature detecting means for detecting the temperature of at least one of the outlet temperature or the inlet temperature of the mill device,
The opening degree of the cold air amount adjusting means is fixed to a predetermined intermediate opening degree during normal operation in which the temperature detected by the temperature detecting means is in a predetermined temperature range.

According to the configuration of (1) above, during normal operation, the opening degree of the cold air amount adjusting means provided in the detour line is fixed at a predetermined intermediate opening degree. During this normal operation, for example, ignition caused by an excessively high temperature of fuel (coal, etc.) in the mill device, or the fuel and the carrier air are too cold downstream of the mill device in the carrier air supply line. It is during normal operation when it is determined that there is no risk of abnormality related to the safety of the boiler system, such as condensation of moisture caused by this. As a result, for example, compared with the conventional method in which the opening degree of the cold air damper, the hot air damper, and the gas damper is controlled in accordance with the amount of water in the fuel and the amount of fuel supply so that the outlet temperature of the mill device becomes a set value. Thus, the configuration of the boiler system and its operation can be simplified.
Further, as the predetermined intermediate opening fixed at the time of normal operation is set to a closed side such as 30% or less of the fully opened state, the hot air passing through the air preheater in the carrier air (primary air) is more reduced. The ratio can be increased, and the amount of heat exchange in the air preheater can be increased.
Therefore, it is possible to reduce the cost by simplifying the configuration and operation of the boiler system while improving the boiler efficiency and reducing the associated fuel cost.

(2) In some embodiments, in the configuration of (1) above,
The predetermined intermediate opening is 30% or less of the opening when fully opened and greater than 0%.
According to the configuration of (2) above, during normal operation of the boiler system, the cold air amount adjusting means is fixed at a predetermined intermediate opening (α) on the closed side that is 30% or less and greater than 0%. (0% <α ≦ 30%). The smaller the predetermined intermediate opening, the smaller the flow rate of the cold air flowing through the bypass line. Therefore, during the normal operation of the boiler system, the predetermined intermediate opening degree is fixed to 30% or less (α ≠ 0) to maintain the flow rate of the cold air at a low level, as described above. The efficiency can be improved and the fuel cost can be reduced.

  Moreover, according to said structure, the opening side range (100- (alpha)%) which can be changed between the predetermined opening degree ((alpha)) and full opening (100%) and which can change the opening degree will be 70% or more. . Therefore, during abnormal operation on the high temperature side of the boiler system, the opening degree of the cold air amount adjusting means can be greatly changed to the open side, and the low temperature of the conveying air by the cold air that is increased according to the changed opening degree. Through the conversion, the temperature at the inlet and / or outlet of the mill device can be controlled appropriately. Furthermore, the opening degree of the cold air amount adjusting means can be changed in the range of 0 to α (0% <α ≦ 30%) even on the closed side. For this reason, at the time of abnormal operation on the low temperature side of the boiler system, by changing the opening degree of the cold air amount adjusting means to the closed side, the heat that increases with the cold air that is reduced according to the changed opening degree The temperature at the inlet and / or outlet of the mill apparatus can be appropriately controlled through the increase in temperature of the conveying air by air.

(3) In some embodiments, in the above configurations (1) to (2),
The apparatus further includes a control device that changes the opening degree of the cold air amount adjusting means from the predetermined intermediate opening degree when the temperature detected by the temperature detecting means is out of the temperature range.
According to the configuration of (3) above, the control device determines when the boiler system exit temperature or the inlet temperature is out of the predetermined temperature range in which normal operation can be determined. It is determined that there is an abnormal operation related to safety. Further, when the control device determines that the operation is abnormal, the control device determines the opening degree of the cold air amount adjusting means fixed at the predetermined intermediate opening degree so that the operation state of the boiler system becomes normal. Automatically change to open side or close side according to As a result, the flow rate of the cold air is increased or decreased, so that the temperature of the conveying air supplied to the mill device can be lowered or increased. Therefore, the temperature of the carrier air is adjusted in this way, and as a result, the outlet temperature and / or the inlet temperature of the mill device are adjusted so as to fall within the temperature range during normal operation. It is possible to return to the normal operation state from the boiler and to secure the safety of the boiler system.

(4) In some embodiments, in the configuration of (3) above,
When the temperature exceeds the upper limit of the temperature range, the control device makes the opening degree of the cold air amount adjusting means larger than the predetermined intermediate opening degree.
According to the configuration of (4) above, the control device determines the abnormal operation time on the high temperature side from the viewpoint of preventing ignition of the fuel based on the comparison with the upper limit of the temperature range for determining the normal operation time. At the same time, when the upper limit is exceeded, the opening degree of the cold air amount adjusting means fixed during normal operation is changed to the open side. As a result, the flow rate of the cold air can be increased, so that the temperature of the conveying air supplied to the mill device can be lowered, and the outlet temperature and / or the inlet temperature of the mill device can be set within the temperature range during normal operation. Can be lowered.

(5) In some embodiments, in the above configurations (3) to (4),
When the temperature falls below the lower limit of the temperature range, the control device makes the opening degree of the cold air amount adjusting means smaller than the predetermined intermediate opening degree.
According to the configuration of (5) above, the control device prevents condensation of water vapor contained in the conveying air downstream of the mill device, based on a comparison with the lower limit of the temperature range for determining normal operation. From this point of view, when the abnormal operation on the low temperature side is determined, and when the lower limit is exceeded, the opening degree of the cold air amount adjusting means fixed during normal operation is changed to the closed side. As a result, the flow rate of the cold air can be reduced, so that the temperature of the conveying air supplied to the mill apparatus can be increased by the hot air that increases with this, and the outlet temperature of the mill apparatus and / or The inlet temperature can be raised to the temperature range during normal operation.

(6) In some embodiments, in the configuration of (5) above,
A transfer air amount adjusting means for adjusting a flow rate of the transfer air supplied to the mill device provided in the transfer air supply line;
When the opening degree of the cold air amount adjusting means becomes a lower limit opening degree that is an opening degree smaller than the predetermined intermediate opening degree, the control device uses the conveying air amount adjusting means to Increase air flow.
According to the configuration of (6) above, if the temperature in the mill device does not fall within the temperature range during normal operation even when the cold air amount adjusting means is closed to the limit (lower limit opening), it is supplied to the boiler. The amount of air for conveyance determined according to the amount of fuel to be increased is increased. In this way, by increasing the total amount of transport air flowing through the air preheater by the transport air amount adjusting means, more air for transport (hot air) preheated by the air preheater is supplied to the mill device. Therefore, the temperature of the conveying air downstream of the mill device can be more reliably raised to a temperature higher than the lower limit of the temperature range during normal operation.

(7) In some embodiments, in the above configurations (1) to (6),
A combustion air supply line for supplying combustion air to the boiler;
The combustion air supply line is connected to the air preheater;
The air preheater simultaneously preheats the carrier air flowing through the carrier air supply line and the combustion air flowing through the combustion air supply line by the high-temperature exhaust gas flowing through the exhaust gas discharge line.
According to the configuration of (7), the boiler efficiency of the boiler system is improved in an air preheater that simultaneously preheats both the carrier air (primary air) and the combustion air (secondary air) in one place. Can be made.

(8) In some embodiments, in the configurations of (1) to (7) above,
The opening degree of the cold air amount adjusting means is fixed to the predetermined intermediate opening degree in the normal operation, even when the boiler is operated with a partial load.
According to the configuration of (8) above, the boiler efficiency of the boiler system can be improved regardless of the operation load of the boiler.

(9) A boiler system operation method according to at least one embodiment of the present invention includes:
The operation method of the boiler system according to any one of (1) to (8) above,
A mill temperature acquisition step of acquiring at least one of the outlet temperature of the mill device or the inlet temperature;
A normality determining step of determining whether or not the boiler system is in a normal operation depending on whether or not the temperature acquired in the mill temperature acquiring step is within a predetermined temperature range;
Provided in a bypass line for bypassing the air preheater that preheats the transport air flowing through the transport air supply line when the normal operation time is determined in the normality determination step. A cold air amount adjusting means that maintains the predetermined intermediate opening degree of the cold air amount adjusting means that is fixed at a predetermined intermediate opening degree when the boiler system is in normal operation. An opening maintaining step.
According to the configuration of the above (9), the same effect as the above (1) can be obtained.

(10) In some embodiments, in the configuration of (9) above,
The predetermined intermediate opening is 30% or less of the opening when fully opened and is greater than 0%.
According to the configuration of (10), the same effect as (2) can be obtained.

(11) In some embodiments, in the above configurations (9) to (10),
When the temperature exceeds the upper limit of the temperature range, it further includes an opening degree increasing step for making the opening degree of the cold air amount adjusting means larger than the predetermined intermediate opening degree.
According to the configuration of the above (11), the same effect as the above (4) can be obtained.

(12) In some embodiments, in the above configurations (9) to (11),
The control device further includes an opening degree narrowing step for making the opening degree of the cold air amount adjusting means smaller than the predetermined intermediate opening degree when the temperature falls below a lower limit of the temperature range.
According to the configuration of (12), the same effect as (5) can be obtained.

(13) In some embodiments, in the configuration of (12) above,
When the opening degree of the cold air amount adjusting means becomes a lower limit opening degree that is smaller than the predetermined intermediate opening degree, the cold air amount adjusting means is supplied to the mill device provided in the conveying air supply line. The method further includes a transfer air increasing step of increasing the flow rate of the transfer air using transfer air amount adjusting means for adjusting the flow rate of the transfer air.
According to the configuration of (13), the same effect as in (6) can be obtained.

  According to at least one embodiment of the present invention, a boiler system capable of reducing costs while improving boiler efficiency is provided.

It is the schematic of the boiler system concerning one Embodiment of this invention. It is a flowchart which shows the operating method of the boiler system concerning one Embodiment of this invention.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  FIG. 1 is a schematic diagram of a boiler system 1 according to an embodiment of the present invention. As shown in FIG. 1, the boiler system 1 is a system including a boiler 2. As shown in FIG. 1, an exhaust gas discharge line Le connected to the boiler 2, an air supply line L1 for conveyance, and air preheating. The apparatus 3, the detour line Lb, the cold air amount adjusting means 4, the mill device 5, and the temperature detecting means 52 are provided. In the embodiment shown in FIG. 1, the boiler 2 is a coal-fired boiler using, for example, coal as a fuel F. However, in some other embodiments, the boiler 2 is other than coal, such as a biomass fuel. The boiler 2 which uses the solid fuel as the fuel F may be used. Below, the boiler system 1 provided with a coal burning boiler is demonstrated to an example.

  As shown in FIG. 1, in the boiler system 1, the boiler 2 is provided with a transfer air supply line L <b> 1 for supplying transfer air G <b> 1 (primary air) for transferring the fuel F to the boiler 2, and the fuel F Combustion air supply line L2 for supplying combustion air G2 (secondary air) for combustion to the boiler 2, and exhaust gas Ge generated by combustion of fuel F inside the boiler 2 outside (outside the system) Ducts such as an exhaust gas discharge line Le for exhausting are respectively connected. A primary air blower 81 (PAF: Primary Air Fan) is installed in the transfer air supply line L <b> 1, and the transfer air G <b> 1 is blown toward the boiler 2 by the primary air blower 81. On the other hand, the combustion air supply line L <b> 2 is provided with a forced draft fan (FDF), and the combustion air G <b> 2 is blown toward the boiler 2 by the forced blower 82. In the embodiment shown in FIG. 1, the primary air blower 81 is installed upstream of the branch position of the bypass line Lb in the transfer air supply line L1.

  Then, the boiler 2 supplies the mixture of the fuel F and the carrier air G1 via the carrier air supply line L1 and the combustion air G2 via the combustion air supply line L2 to the combustion chamber inside the boiler 2. Combustion is performed by blowing through a burner (not shown). The boiler 2 may be operated not only with a load of 100% but also with a partial load smaller than 100%. Further, the exhaust gas Ge generated by the combustion in the boiler 2 is discharged to the outside of the boiler system 1 through the chimney 91 through the exhaust gas discharge line Le. In this exhaust gas discharge line Le, an induction fan and an environmental device (for example, a denitration device that removes nitrogen oxides from exhaust gas, a dust collector that removes soot, a desulfurization device that removes sulfur oxides, etc.) are installed. There is a case. Usually, the boiler 2 is provided with a superheater (not shown), a reheater, a economizer, etc. for recovering the heat of the exhaust gas Ge. Heat exchange is performed with Ge and is configured to generate steam.

  As shown in FIG. 1, the carrier air supply line L <b> 1 is provided with a mill device 5 for pulverizing the fuel F supplied to the boiler 2. The mill device 5 is supplied with coal (fuel F), and the pulverized coal (fine powder) pulverized by the mill device 5 is a portion on the downstream side of the mill device 5 in the conveying air supply line L1 ( The pulverized coal pipe L1a) is supplied to the boiler 2 (burner) by being transferred by the transfer air G1. At this time, the amount of pulverized fuel (fuel F) supplied from the mill device 5 to the boiler 2 is determined according to the output command value of the boiler 2, and the primary air according to this output command value (amount of pulverized fuel). The flow rate of the conveying air G1 from the blower 81 is also determined.

  As shown in FIG. 1, the hot air amount control means 83 that can control the flow rate of the transfer air G1 supplied to the mill device 5 and the flow rate of the hot air Gh described later is a transfer air supply line L1. May be provided on the upstream side of the mill device 5. In the embodiment shown in FIG. 1, the hot air amount control means 83 is provided between a confluence of the transfer air supply line L1 and the detour line Lb and an air preheater 3 to be described later. The flow control based on a flow meter (not shown) installed between the mill device 5 and the hot air amount control means 83 in the supply line L1 is possible. In the present embodiment, the opening degree of the hot air amount control means 83 flows through the bypass line Lb, the flow rate of the cold air Gb adjusted by the cold air amount adjustment means 4 described later, and the transfer air supply line L1. The sum of the flow rate of the hot air Gh heated (preheated) by the air preheater 3 to be described later is determined to be the flow rate of the conveying air G1 according to the amount of the fuel F charged into the mill device 5. Also good. On the other hand, the flow rate control of the combustion air G2 blown by the forced air blower 82 is performed by setting the detected value of an oxygen measuring means (not shown) installed in the exhaust gas discharge line Le and capable of detecting the oxygen amount in the exhaust gas Ge to a set value. It may be performed by controlling the output of the pusher blower 82 so as to be. In the embodiment shown in FIG. 1, there is no gas damper (not shown) that can adjust the flow rate of exhaust gas Ge used for heat exchange via the air preheater 3 in the exhaust gas discharge line Le. In some other embodiments, the gas damper may be installed on the downstream side or the upstream side of the air preheater 3 in the exhaust gas discharge line Le.

  Here, the coal that is the fuel F of the boiler 2 has a characteristic that the amount of water contained varies depending on the type of coal and the rainfall, and after drying in the mill device 5, the coal powder L1a is pulverized by the conveying air. Through the boiler 2. If the drying is insufficient at this time, moisture condensation that occurs in the course of conveyance may cause pulverized coal to adhere to and clog the pulverized coal pipe L1a, or may affect the combustion performance. Therefore, the carrier air G1 is supplied to the mill device 5 after being preheated (preheated) by the air preheater 3 connected to each of the carrier air supply line L1 and the exhaust gas discharge line Le described above. Yes. That is, the conveying air G1 is heated by the heat of the relatively high temperature exhaust gas Ge through the air preheater 3, and the coal is dried by the heat. In some embodiments, as shown in FIG. 1, the air preheater 3 is connected to the combustion air supply line L2 in addition to the transfer air supply line L1 and the exhaust gas discharge line Le. Thus, the relatively low temperature combustion air G2 and the transfer air G1 may be preheated simultaneously by the relatively high temperature exhaust gas Ge flowing through the exhaust gas discharge line Le.

  Further, as shown in FIG. 1, a bypass line Lb (duct) for connecting the upstream side and the downstream side of the air preheater 3 in the transfer air supply line L1 is connected to the transfer air supply line L1. Has been. That is, the transfer air G1 can flow through the transfer air supply line L1 while bypassing the air preheater 3 without passing through the air preheater 3 by flowing through the bypass line Lb.

  As shown in FIG. 1, the bypass line Lb is provided with a cold air amount adjusting means 4 capable of adjusting the flow rate of the transfer air G1 flowing through the bypass line Lb. In the embodiment shown in FIG. 1, the cold air amount adjusting means 4 is a damper. The opening degree of the cold air amount adjusting means 4 is fixed to a predetermined intermediate opening degree α during normal operation of the boiler system 1. As will be described later, the opening degree of the cold air amount adjusting means 4 is changed so that the boiler system 1 is restored from the abnormal operation state to the normal operation state only during the abnormal operation that is not during normal operation. . In the embodiment shown in FIG. 1, the predetermined intermediate opening α is an opening on the aperture side such as 10% of the opening when fully opened.

  Here, during normal operation of the boiler system 1, the temperature detection means 52 (for example, a thermometer) that detects at least one of the outlet temperature Td and the inlet temperature Tu of the mill device 5 (hereinafter, detected temperature T). ) Means a case where the detected temperature T detected in the above is within a predetermined temperature range R. That is, the predetermined temperature range R is an index for determining whether or not the operation of the boiler system 1 is normal, and is determined for safety reasons in the operation of the boiler system 1. More specifically, the upper limit Bu of the predetermined temperature range R is such that the fuel F may be ignited in the mill device 5 when the detected temperature T exceeds the upper limit Bu (T> Bu). Temperature. Specifically, in terms of the outlet temperature Td of the mill device 5, the upper limit Bu may be 90 ° C to 100 ° C. In terms of the inlet temperature Tu of the mill device 5, the upper limit Bu may be 320 ° C. or higher. On the other hand, the lower limit Bd of the predetermined temperature range R connects the mill device 5 and the boiler 2 in the conveying air supply line L1 when the detected temperature T is lower than the lower limit Bd (T <Bd). The temperature is such that there is a possibility that the fine fuel (fuel F) will condense in the portion where it will be. When the pulverized fuel is condensed, the transportation air supply line L1 is clogged with fuel. Specifically, in terms of the outlet temperature Td of the mill device 5, the lower limit Bd may be 50 ° C to 60 ° C. In terms of the inlet temperature Tu of the mill device 5, the lower limit Bd may be 150 ° C. or less.

  When both the outlet temperature Td and the inlet temperature Tu of the mill apparatus 5 are monitored, a predetermined temperature range R corresponding to each of the outlet temperature Td and the inlet temperature Tu is provided. The above temperature is merely an example, and does not limit the numerical range of the temperature range R described above.

  In a situation where the boiler system 1 is determined to be in normal operation, regardless of whether the boiler 2 is operated with a load of 100% or a partial load smaller than 100%. The boiler efficiency can be improved by fixing the opening of the cold air amount adjusting means 4 to a predetermined intermediate opening α. That is, the conveying air G1 (hereinafter referred to as cold air Gb) flowing through the detour line Lb is not preheated by the air preheater 3 and thus remains at a low temperature (for example, normal temperature). The low-temperature cold air Gb is combined with the carrier air supply line L1 downstream of the air preheater 3 by the bypass line Lb, so that the carrier air G1 (the temperature of which is increased by the preheating by the air preheater 3 ( Hereinafter, it has the effect of cooling the hot air Gh), and the conveying air G1 is determined by the amount of fuel F introduced into the mill device 5. For this reason, when the opening degree of the cold air amount adjusting means 4 is large, the flow rate of the cold air Gb increases accordingly, so that the hot air Gh decreases, the amount of heat exchange in the air preheater 3 decreases, and the exhaust gas Therefore, it is difficult to recover the heat from the air, so that it is difficult to reduce the temperature of the outlet gas of the air preheater 3 and the heat loss is increased.

  In this regard, as in the prior art, the cold air amount adjusting means 4 (cold air damper), the hot air amount control means 83 (hot air damper), and a gas damper (not shown) are set so that the detected temperature T described above becomes constant. If the detected temperature T becomes higher than the target, the flow rate of the cold air Gb is increased more than before, and the amount of hot air is reduced by that amount. As described above, the heat generated by the air preheater 3 is reduced. The exchange amount decreases. Alternatively, since the flow rate of the exhaust gas Ge is reduced by the gas damper, the recovery amount of the energy of the exhaust gas Ge in the air preheater 3 is reduced.

  However, in the present invention, as long as it is determined during normal operation, even if the detected temperature T increases or decreases, the cold air amount adjusting means 4, the hot air amount control means 83, the gas damper (non- The opening degree of the cold air amount adjusting means 4 is fixed at a predetermined intermediate opening degree α. As a result, as long as it is determined that the operation is normal, the flow rate of the cold air Gb is neither increased nor decreased, so the flow rate of the hot air Gh is not increased or decreased, and the heat exchange amount by the air preheater 3 decreases. There is nothing. That is, an increase in heat loss can be suppressed. Moreover, in the present invention, during normal operation, not only the opening degree adjustment of the cold air amount adjusting means 4 but also the control of the gas damper for making the above-described detected temperature T within the predetermined temperature range R is necessary. The operation of the boiler system 1 and the configuration of the boiler system 1 can be simplified. Further, as the predetermined intermediate opening α at which the cold air amount adjusting means 4 is fixed is set to the throttle side, the flow rate of the cold air Gb is reduced, and the flow rate of the hot air Gh is increased accordingly, and the heat from the exhaust gas is increased. Since the recovery amount increases, it is possible to improve the boiler efficiency during normal operation.

  According to said structure, the opening degree of the cold air amount adjustment means 4 provided in the detour line Lb is fixed to predetermined intermediate opening degree (alpha) at the time of normal driving | operation. Thereby, the structure of the boiler system 1 and its operation can be simplified. Further, the flow rate of the cold air Gb is decreased and the flow rate of the hot air Gh is increased as the predetermined intermediate opening α fixed during the normal operation is closed, for example, 30% or less of the fully opened state. Therefore, the amount of heat exchange in the air preheater 3 increases, and heat loss can be reduced. Therefore, it is possible to reduce the cost by simplifying the configuration and operation of the boiler system 1 while reducing the fuel cost.

  In some embodiments, the predetermined intermediate opening degree α to which the above-described cold air amount adjusting means 4 is fixed is 30% or less of the opening degree when fully opened and is larger than 0%. When the predetermined intermediate opening degree α is 30% or less of the opening degree when fully opened, as described above, the flow rate of the hot air Gh can be increased to improve the boiler efficiency during normal operation. Further, as will be described later, the opening degree of the cold air amount adjusting means 4 may be changed from the fixed predetermined intermediate opening degree α to the closed side during abnormal operation on the low temperature side. By changing the opening degree of the cold air amount adjusting means 4 to the closed side, the predetermined intermediate opening degree α reduces the flow rate of the cold air Gb and increases the flow rate of the hot air Gh accordingly. Therefore, the boiler efficiency can be further improved.

  Specifically, the predetermined intermediate opening degree α may be determined based on a desired boiler efficiency, and is 5 to 15 such as 5%, 10%, and 15% of the opening degree when the cold air amount adjusting means 4 is fully opened. You may determine suitably with the value of 30% or less, such as the range of%. For example, when the predetermined intermediate opening α is 10%, the predetermined intermediate opening α is 90% (= 100% −10%) between the predetermined intermediate opening α and fully open (100%). An open side range (100-α%) of an opening that can be changed from the intermediate opening α can be provided. For this reason, when the detected temperature T in the above-described mill device 5 exceeds the upper limit Bu (during abnormal operation on the high temperature side), the cold air amount adjusting means 4 is changed from the predetermined intermediate opening α to the open side, It is possible to control the outlet temperature and / or the inlet temperature of the mill device 5 to a temperature range determined to be during normal operation through lowering the temperature of the conveying air G1 generated by increasing the flow rate of the cold air Gb. On the other hand, in this case, a closed side range (0 to α%) that can be changed from a predetermined intermediate opening α to the closed side is provided on the closed side, such as 0% to 10%. For this reason, when the detected temperature T in the mill device 5 falls below the lower limit Bd (during abnormal operation on the low temperature side), the cold air amount adjusting means 4 is changed from the predetermined intermediate opening α to the closed side, It is also possible to control the outlet temperature and / or the inlet temperature of the mill device 5 to a temperature range determined to be during normal operation through increasing the temperature of the carrier air G1 generated by reducing the flow rate of Gb.

  According to the above configuration, during normal operation of the boiler system 1, the cold air amount adjusting means is fixed to a predetermined intermediate opening degree α on the closed side that is 30% or less and larger than 0% ( 0% <α ≦ 30%). The smaller the predetermined intermediate opening α, the smaller the flow rate of the cold air Gb flowing through the detour line Lb. Therefore, during the normal operation of the boiler system 1, the flow rate of the cold air Gb is kept low by fixing the predetermined intermediate opening α to 30% or less (α ≠ 0) as described above. In addition, the boiler efficiency can be improved and the fuel F cost can be reduced.

  Moreover, according to said structure, the range (100- (alpha)%) of the opening side which can be changed between the opening degree provided between predetermined intermediate opening degree (alpha) and full open (100%) becomes 70% or more. Therefore, at the time of abnormal operation on the high temperature side of the boiler system 1, the opening degree of the cold air amount adjusting means 4 can be largely changed to the open side, and the conveyance by the cold air Gb increased according to the changed opening degree. Through lowering the temperature of the air G1, the inlet temperature and / or outlet temperature of the mill device 5 can be controlled within a temperature range that is determined to be during normal operation. Furthermore, the opening degree of the cold air amount adjusting means 4 can be changed in the range of 0 to α (0% <α ≦ 30%) on the closed side. For this reason, at the time of abnormal operation on the low temperature side of the boiler system 1, by changing the opening degree of the cold air amount adjusting means 4 to the closed side, the cold air Gb decreases according to the changed opening degree. It is also possible to control the outlet temperature and / or the inlet temperature of the mill device 5 to a temperature range determined to be during normal operation through the increase in the temperature of the conveying air G1 by the increasing hot air Gh.

Next, an operation method during abnormal operation of the boiler system 1 and a configuration for the operation method will be described.
In some embodiments, as shown in FIG. 1, in the boiler system 1, the detected temperature T detected by the temperature detecting means 52 deviates from the predetermined temperature range R described above for determining normal operation. In this case, the control device 6 further changes the opening degree of the cold air amount adjusting means 4 from a predetermined intermediate opening degree α. The control device 6 is configured by a computer and includes a CPU (processor) (not shown) and a memory (storage device) such as a ROM and a RAM. Then, the CPU operates (data calculation or the like) according to the instructions of the program loaded in the main storage device, thereby changing the opening degree of the cold air amount adjusting means 4 described later. In addition, the control apparatus 6 may be comprised with an independent computer, and may be comprised so that it may operate on a computer with the other program which controls the boiler system 1. FIG.

  In the embodiment shown in FIG. 1, the boiler system 1 detects the outlet temperature detection means 52 d (temperature detection means 52) for detecting the outlet temperature Td of the mill apparatus 5 and the inlet temperature Tu of the mill apparatus 5. The inlet temperature detection means 52u (temperature detection means 52) is provided. Each of the outlet temperature detecting means 52d and the inlet temperature detecting means 52u is configured to detect the outlet temperature Td and the inlet temperature Tu described above by being installed on the transfer air supply line L1. In the embodiment shown in FIG. 1, the outlet temperature detecting means 52d is installed in the pulverized coal pipe L1a downstream of the mill device 5 in the conveying air supply line L1, and the inlet temperature detecting means 52u is transported upstream of the mill device 5. It is installed on the working air supply line L1. The outlet temperature detection means 52d is installed in the pulverized coal pipe L1a of the mill device 5 in the transfer air supply line L1 to detect the temperature of the transfer air G1. However, the present invention is not limited to the present embodiment, and the outlet temperature detecting means 52d and the inlet temperature detecting means 52u may be installed at positions where the outlet temperature and the inlet temperature of the mill device 5 can be detected, respectively.

  The control device 6 is connected to the outlet temperature detecting means 52d and the inlet temperature detecting means 52u, respectively, and the outlet temperature Td detected by the outlet temperature detecting means 52d and the inlet temperature detected by the inlet temperature detecting means 52u. Both of the temperatures Tu are configured to be input. Similarly, the control device 6 is connected to the cold air amount adjusting means 4 and is configured to be able to change (adjust) the opening degree of the cold air amount adjusting means 4. Further, the control device 6 determines the boiler system 1 based on the information on the outlet side temperature range Rd for determining whether or not the operation state of the boiler system 1 is normal based on the outlet temperature Td and the inlet temperature Tu. Both the information of the inlet side temperature range Ru for determining whether or not the operation state is normal is held in a non-volatile memory or the like.

  With such a configuration, when the outlet temperature Td is input, the control device 6 determines whether the outlet temperature Td is in the outlet side temperature range Rd, and on the other hand, when the inlet temperature Tu is input. Then, it is determined whether the inlet temperature Tu is in the inlet side temperature range Ru. At this time, when it is determined that the outlet temperature Td is not in the outlet side temperature range Rd (the outlet temperature Td is out of the outlet side temperature range Rd), or the inlet temperature Tu is in the inlet side temperature range Ru. If any one of the cases where it is determined that the inlet temperature Tu is outside the inlet side temperature range Ru occurs, it is determined that the operation of the boiler system 1 is abnormal, and the cold air amount adjusting means 4 Is configured to change from a predetermined intermediate opening α.

  However, the present invention is not limited to this embodiment, and in some other embodiments, the boiler system 1 includes an outlet temperature detection means 52d (temperature detection means 52) or an inlet temperature detection means 52u (temperature detection means). 52) may be provided. In this case, the control device 6 may be provided with either one of the outlet side temperature range Rd or the inlet side temperature range Ru.

  According to the above configuration, the control device 6 detects a case where the detected temperature T of at least one of the outlet temperature Td or the inlet temperature Tu of the mill device 5 is out of the predetermined temperature range R in which normal operation can be determined. It is determined that there is an abnormal operation related to the safety of the boiler system 1. In addition, when the control device 6 determines the abnormal operation time, the opening degree of the cold air amount adjusting means 4 fixed at the predetermined intermediate opening degree α so that the operation state of the boiler system 1 becomes normal. Is automatically changed to open side or closed side according to the situation. As a result, the flow rate of the cold air Gb is increased or decreased, so that the temperature of the transfer air G1 supplied to the mill device 5 can be lowered or increased. Therefore, the outlet temperature Td and / or the inlet temperature Tu of the mill device 5 determined to have deviated from the predetermined temperature range by the temperature-adjusted carrier air G1 are included in the temperature range R during normal operation. Since the adjustment is made, the boiler system 1 can be returned from the abnormal operation state to the normal operation state, and the safety of the boiler system 1 can be secured.

  More specifically, the control device 6 determines that the outlet temperature Td detected by the temperature detection means 52 (52u, 52d) exceeds the upper limit Bu of the outlet side temperature range Rd (Td> Bu) and / or the inlet. When the temperature Tu exceeds the upper limit Bu of the inlet side temperature range Ru described above (Tu> Bu), the opening degree of the cold air amount adjusting means 4 is made larger than a predetermined intermediate opening degree α. As described above, the upper limit Bu is such a temperature that the fuel F may be ignited in the mill device 5 because the outlet temperature Td and the inlet temperature Tu are excessively high. Therefore, the control device 6 compares the outlet temperature Td with the upper limit Bu of the outlet side temperature range Rd and / or compares the inlet temperature Tu with the upper limit Bu of the inlet side temperature range Ru. As a result, the outlet temperature Td is When the outlet side temperature range Rd is larger than the upper limit Bu and / or when the inlet temperature Tu is larger than the upper limit Bu of the inlet side temperature range Ru, the opening degree of the cold air amount adjusting means 4 is set to a predetermined intermediate opening degree. The outlet temperature Td and / or the inlet temperature Tu of the mill device 5 is changed to the upper limit of each temperature range R through the lowering of the conveying air G1 generated by changing from α to the open side and increasing the flow rate of the cold air Gb. The upper limit Bu of the outlet side temperature range Rd and the upper limit Bu) of the inlet side temperature range Ru are set to be less than or equal to each other.

For example, in some embodiments, the control device 6 may change the opening degree of the cold air amount adjusting means 4 from the predetermined intermediate opening degree α described above to full opening (opening degree 100%). As a result, the flow rate of the cold air Gb becomes maximum, so that the detected temperature T can be returned to the predetermined temperature range R corresponding to the normal operation by the cold air Gb having the maximum flow rate. That is, the outlet temperature Td can be returned to the outlet side temperature range Rd, and the inlet temperature Tu can be returned to the inlet side temperature range Ru.
Alternatively, in some other embodiments, the control device 6 sets the opening degree of the cold air amount adjusting means 4 to a predetermined intermediate amount by an amount corresponding to the difference between the detected temperature T and the upper limit Bu of the predetermined temperature range R. The opening degree α may be changed to the open side. That is, the opening degree of the cold air amount adjusting means 4 is changed according to the difference between the outlet temperature Td and the upper limit Bu of the outlet side temperature range Rd and / or the difference between the inlet temperature Tu and the upper limit Bu of the inlet side temperature range Ru. . Specifically, the control device 6 determines the difference between the detected temperature T and the above upper limit Bu (the difference between the outlet temperature Td and the upper limit Bu of the outlet side temperature range Rd and / or the difference between the inlet temperature Tu and the inlet side temperature range Ru. Open side change information indicating the relationship between the difference between the upper limit Bu and the opening amount of the cold air amount adjusting means 4 or the opening amount of the cold air adjusting means 4 is held in the memory. Then, the difference (same as above) between the detected temperature T input from the temperature detecting means 52 and the upper limit Bu is calculated, and the opening degree of the cold air amount adjusting means 4 to be set is calculated from the calculation result and the open side change information. Or the change amount of the opening degree to the opening side which should be changed may be acquired, and the opening degree of the cold air amount adjustment means 4 may be changed based on the acquired information. Accordingly, it is possible to suppress a decrease in boiler efficiency caused by increasing the flow rate of the cold air Gb more than necessary.

  According to the above configuration, the control device 6 compares the upper limit Bu of the temperature range R (the upper limit Bu of the outlet side temperature range Rd and / or the upper limit Bu of the inlet side temperature range Ru) for determining normal operation. Based on the above, when the abnormal operation on the high temperature side where there is a risk of ignition of the fuel F is determined and the upper limit is exceeded, the opening degree of the cold air amount adjusting means 4 fixed during normal operation is determined. Change to open side. Thereby, since the flow rate of the cold air Gb can be increased, the temperature of the conveying air G1 supplied to the mill device 5 can be lowered, and the outlet temperature Td and / or the inlet temperature Tu of the mill device 5 can be reduced. The temperature range during normal operation can be reduced.

On the other hand, when the detected temperature T detected by the temperature detecting means 52 (52u, 52d) falls below the lower limit Bd of the temperature range R, the control device 6 reduces the opening degree of the cold air amount adjusting means 4 to a predetermined intermediate level. The opening is made smaller than α. That is, when the outlet temperature Td falls below the lower limit Bd of the outlet side temperature range Rd and / or when the inlet temperature Tu falls below the lower limit Bd of the inlet side temperature range Ru (Tu <Bd), the cold air amount adjusting means The opening degree of 4 is made smaller than a predetermined intermediate opening degree α. As described above, the lower limit Bd is such that the detected temperature T (the outlet temperature Td and / or the inlet temperature Tu) is excessively low, so that the mill device 5 and the boiler 2 in the transfer air supply line L1 The temperature at which the water evaporated during the drying process is likely to condense in the portion connecting the two. Therefore, the control device 6 compares the detected temperature T with the lower limit Bd. As a result, when the detected temperature T is smaller than the lower limit Bd, the opening degree of the cold air amount adjusting means 4 is changed from a predetermined intermediate opening degree α. Change to closed side. That is, the outlet temperature Td is compared with the lower limit Bd of the outlet side temperature range Rd. As a result, when the outlet temperature Td is smaller than the lower limit Bd, the opening degree of the cold air amount adjusting means 4 is changed as described above. To do. And / or the inlet temperature Tu is compared with the lower limit Bd of the inlet side temperature range Ru, and when the inlet temperature Tu is smaller than the lower limit Bd, the opening degree of the cold air amount adjusting means 4 is changed as described above. . As a result, the temperature of the fuel F and the conveying air G1 downstream of the mill device 5 is increased through increasing the temperature of the conveying air G1 generated by reducing the cold air Gb according to the changed opening.
To do.

For example, in some embodiments, the control device 6 may change the opening degree of the cold air amount adjusting unit 4 from the predetermined intermediate opening degree α to the fully closed state (opening degree 0%). As a result, the flow rate of the cold air Gb becomes a minimum, for example, 0. Therefore, the detected temperature T is reduced to the predetermined temperature range R corresponding to the normal operation by reducing the degree of cooling of the hot air Gh by the cold air Gb. Can be returned.
Alternatively, in some other embodiments, the control device 6 may detect the difference between the detected temperature T and the lower limit Bd of the predetermined temperature range R (the difference between the outlet temperature Td and the lower limit Bd of the outlet side temperature range Rd and / or The opening degree of the cold air amount adjusting means 4 may be changed from the predetermined intermediate opening degree α to the closing side by an amount corresponding to the difference between the inlet temperature Tu and the lower limit Bd of the inlet side temperature range Ru). good. Specifically, the control device 6 shows the relationship between the difference between the detected temperature T and the lower limit Bd (same as above) and the amount of change in the opening degree of the cold air amount adjusting means 4 or the opening degree to the closing side. Close side change information is held in memory. Then, the difference (same as above) between the detected temperature T input from the temperature detecting means 52 and the lower limit Bd is calculated, and the opening degree of the cold air amount adjusting means 4 to be set is calculated from the calculation result and the closing side change information. Or the change amount of the opening degree to the closing side which should be changed may be acquired, and the opening degree of the cold air amount adjustment means 4 may be changed based on the acquired information.

  According to said structure, the control apparatus 6 is in the air for conveyance in the downstream (pulverized coal pipe L1a) of the mill apparatus 5 based on comparison with the minimum Bd of the temperature range R for determining the time of normal operation. When the abnormal operation on the low temperature side such as condensation from the viewpoint of preventing condensation of water vapor contained in the water is determined and below the lower limit, the amount of the cold air amount adjusting means 4 fixed during normal operation is determined. Change the opening to the closed side. As a result, the flow rate of the cold air Gb can be reduced, so that the temperature of the conveying air G1 supplied to the mill device 5 can be increased by the hot air Gh that increases accordingly. The outlet temperature Td can be raised to the temperature range during normal operation.

By the way, since the opening degree of the cold air amount adjusting means 4 is originally fixed to the closed side such as 10%, the cold air amount adjusting means 4 is fully closed (opening degree 0%) during abnormal operation on the low temperature side. However, depending on the situation, there may be a case where the temperature of the transfer air G1 supplied to the mill device 5 cannot be sufficiently increased.
For this reason, in some embodiments, the boiler system 1 has a flow rate (flowing through the transfer air supply line L1 provided in the transfer air supply line L1 and the inlet of the mill device 5) provided in the transfer air supply line L1. Further, a transfer air amount adjusting means 7 for adjusting the flow rate of the transfer air G1 reaching the position (1) is further provided. The control device 6 adjusts the air amount for conveyance when the opening degree of the cold air amount adjusting means 4 is an opening degree smaller than the predetermined intermediate opening degree α, for example, a lower limit opening degree B0 such as 0%. The means 7 is used to increase the flow rate of the conveying air G1. That is, even if the cold air amount adjusting means 4 is closed to the limit (lower limit opening B0), if the detected temperature T in the mill device 5 does not fall within the temperature range R during normal operation, it is supplied to the boiler 2. The total amount of the transfer air G1 (hot air Gh) flowing through the air preheater 3 is increased by temporarily increasing the amount of the transfer air G1 that is normally determined according to the amount of the fuel F.

  In the embodiment shown in FIG. 1, the transfer air amount adjusting means 7 is the hot air amount control means 83 described above, and the flow rate of the transfer air G1 that is the sum of the cold air Gb and the hot air Gh is the mill device 5. The opening degree is determined so as to be an amount determined by the amount of fuel F input to the. As shown in FIG. 1, the control device 6 is connected to the hot air amount control means 83, and can control the opening degree of the hot air amount control means 83. Specifically, the control device 6 transmits a command signal for increasing the opening degree to the hot air amount control means 83. When the hot air amount control means 83 receives the command signal for increasing the opening degree, the opening degree of the hot air amount control means 83 increases. As a result, the flow rate of the air blown toward the mill device 5 (the flow rate of the conveying air G1) increases. In some other embodiments, the transfer air amount adjusting means 7 may be a primary air blower 81 (PAF). In some other embodiments, the transfer air amount adjusting means 7 may be both the hot air amount control means 83 and the primary air blower 81. In this case, even if the hot air amount control means 83 is fully opened, if the detected temperature T in the mill device 5 still does not fall within the temperature range R during normal operation, the control device 6 causes the primary air blower 81 to operate. (PAF) may be configured to transmit a command signal for increasing the opening.

  According to said structure, more hot air can be supplied to the mill apparatus 5 by increasing the total amount of the conveyance air G1 which flows through the air preheater 3 with the conveyance air quantity adjustment means 7, The temperature of the conveying air G1 downstream of the mill device 5 (pulverized coal pipe L1a) can be more reliably raised to a temperature higher than the lower limit Bd of the temperature range during normal operation.

Hereinafter, the operation method of the boiler system 1 mentioned above is demonstrated using FIG.
FIG. 2 is a flowchart showing an operation method of the boiler system 1 according to the embodiment of the present invention. As shown in FIG. 2, the operation method of the boiler system 1 includes a mill temperature acquisition step (S1), an operation normality determination step (S2), and an intermediate opening degree maintaining step (S4). An operation method of the boiler system 1 including these steps will be described according to the flow of FIG. 2 may be executed by the control device 6 described above or may be executed manually. Further, the flow of FIG. 2 is repeatedly executed continuously, for example.

  In step S1 of FIG. 2, a mill temperature acquisition step is executed. The mill temperature acquisition step (S1) is a step of acquiring at least one temperature (detected temperature T) of the outlet temperature Td or the inlet temperature Tu of the above-described mill device 5 (see FIG. 1). In the next step S2, an operation normality determination step is executed. The operation normality determination step (S2) determines whether or not the boiler system 1 is in normal operation depending on whether or not the detected temperature T acquired in the mill temperature acquisition step (S1) is within a predetermined temperature range R. It is a step to do. As described above, when the detected temperature T is within the predetermined temperature range R, it is determined as normal. Conversely, when the detected temperature T is out of the predetermined temperature range R, it is determined that there is an abnormality.

  If it is determined in step S3 that the normal operation is being performed in the operation normality determining step (S2), an intermediate opening degree maintaining step is executed in step S4. In the intermediate opening degree maintaining step (S4), when it is determined that the operation is normal by the operation normality determining step (S2) (Yes in step S3), the above-described transfer air flowing through the transfer air supply line L1 When the boiler system 1 is in a normal operation in the cold air amount adjusting means 4 provided in the bypass line Lb for bypassing the air preheater 3 for preheating G1 (primary air) and flowing the carrier air G1. In this step, the opening degree of the cold air amount adjusting means 4 fixed at the predetermined intermediate opening degree α is maintained at the predetermined intermediate opening degree α. That is, the intermediate opening degree maintaining step (S4) is a step that does not change the opening degree of the cold air amount adjusting means 4 that is fixed at the predetermined intermediate opening degree α during normal operation. As described above, the predetermined intermediate opening α may be 30% or less, such as 10% of the opening when fully opened. Thus, by fixing the opening of the cold air amount adjusting means 4 to a predetermined intermediate opening α during normal operation, as described above, the boiler efficiency is improved and the fuel cost associated therewith is reduced. Moreover, the cost can be reduced by simplifying the configuration and operation of the boiler system 1. Further, as the predetermined intermediate opening α is smaller, the flow rate of the cold air Gb can be reduced and the hot air Gh can be increased. Therefore, the heat exchange amount in the air preheater 3 is increased, and the heat loss is reduced. Therefore, it is possible to improve boiler efficiency and reduce fuel costs.

  As shown in FIG. 2, in some embodiments, the operation method of the boiler system 1 is such that when the detected temperature T exceeds the upper limit Bu of the temperature range R, the cold air amount adjusting means 4 is used. An opening degree increasing step (S6) for making the opening degree larger than a predetermined intermediate opening degree α may be further provided. That is, this opening degree increasing step (S6) is performed when the outlet temperature Td is larger than the upper limit Bu of the outlet side temperature range Rd and / or when the inlet temperature Tu is larger than the upper limit Bu of the inlet side temperature range Ru. Executed. In the embodiment shown in FIG. 2, when the boiler system 1 is determined to be abnormal in step S3 described above (No in step S3), the detected temperature T is the upper limit Bu of the temperature range R in step S5. It is determined whether or not it has exceeded. That is, it is determined in step S5 whether or not the outlet temperature Td has exceeded the upper limit Bu of the outlet side temperature range Rd and / or whether or not the inlet temperature Tu has exceeded the upper limit Bu of the inlet side temperature range Ru. The opening degree increasing step (S6) is executed when it is determined in step S5 that the detected temperature T has exceeded the upper limit Bu of the temperature range R (Td> Bu). That is, the opening degree increasing step (S6) is executed when the outlet temperature Td exceeds the upper limit Bu of the outlet side temperature range Rd and / or when the inlet temperature Tu exceeds the upper limit Bu of the inlet side temperature range Ru. Is done. By executing the opening degree increasing step (S6), the flow rate of the cold air Gb flowing through the detour line Lb can be increased. That is, as already described, the temperature of the transfer air G1 supplied to the mill device 5 can be further lowered by the increased cold air Gb, so that the detected temperature T (exit temperature Td and / or It is possible to avoid the occurrence of ignition or the like by lowering the inlet temperature Tu).

  As shown in FIG. 2, in some embodiments, the operation method of the boiler system 1 is such that when the acquired detected temperature T falls below the lower limit Bd of the temperature range R, the cold air amount adjusting means 4. There may be further provided an opening degree narrowing step (S7) for making the opening degree smaller than a predetermined intermediate opening degree α. That is, this opening degree narrowing step (S7) is performed when the outlet temperature Td is lower than the lower limit Bd of the outlet side temperature range Rd and / or when the inlet temperature Tu is lower than the lower limit Bd of the inlet side temperature range Ru. Executed. In the embodiment shown in FIG. 2, when it is determined in step S5 described above that the detected temperature T does not exceed the upper limit Bu of the temperature range R, the detected temperature T is within the predetermined temperature range R. In this case, the value falls below the lower limit (lower limit Bd) (when the temperature is lower than the lower limit Bd of the outlet side temperature range Rd and / or when the inlet temperature Tu is lower than the lower limit Bd of the inlet side temperature range Ru). In step S7, the opening degree narrowing step is executed. By executing the opening throttle step (S7), the flow rate of the cold air Gb flowing through the detour line Lb can be reduced. Accordingly, as already described, the temperature of the conveying air G1 supplied to the mill device 5 can be further increased, so that the temperature of the mill device 5 and the conveying air G1 downstream thereof can be raised and conveyed. It is possible to prevent the condensation of moisture evaporated in the drying process downstream of the mill device 5 in the air supply line L1.

  As shown in FIG. 2, in some embodiments, the operation method of the boiler system 1 is such that when the opening degree of the cold air amount adjusting means 4 becomes the lower limit opening degree B0, the conveying air supply line A transfer air increasing step (S9) for increasing the flow rate of the transfer air G1 using the transfer air amount adjusting means 7 for adjusting the flow rate of the transfer air G1 supplied to the mill device 5 provided in L1. Further, it may be provided.

  In the embodiment shown in FIG. 2, in the transfer air increasing step (S9), the opening degree of the cold air amount adjusting means 4 is set to the lower limit opening degree B0 (for example, opening degree 0%) by the opening degree reducing step (S7) described above. Even when the temperature reaches the value, it is executed when the detected temperature T is below the lower limit (lower limit Bd) of the temperature range R (Yes in step S8). Specifically, in step S8, when the opening degree of the cold air amount adjusting means 4 is the lower limit opening degree B0 and the detected temperature T is lower than the lower limit Bd of the temperature range R (the cold air amount adjusting means 4 When the opening degree = the lower limit opening degree B0 and T <Bd (Td <Bd of Rd and / or Tu <Ru Bd)), a transfer air increasing step is executed in step S9. By executing the transfer air increasing step (S9), by increasing the total amount of the transfer air G1 flowing through the air preheater 3, more hot air Gh can be supplied to the mill device 5, and the mill device 5 The temperature of the carrier air G1 supplied to the heater is more reliably increased to a temperature higher than the lower limit Bd of the temperature range R during normal operation (the lower limit Bd of the outlet side temperature range Rd and / or the lower limit Bd of the inlet side temperature range Ru). can do.

  The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

DESCRIPTION OF SYMBOLS 1 Boiler system 2 Boiler 3 Air preheater 4 Cold air quantity adjustment means 5 Mill apparatus 52 Temperature detection means 52d Outlet temperature detection means 52u Inlet temperature detection means 6 Controller 7 Conveyance air quantity adjustment means 81 Primary air blower 82 Pushing blower 83 Hot air quantity control means 91 Chimney

L1 Conveying air supply line L1a Pulverized coal pipe L2 Combustion air supply line Lb Detour line Le Exhaust gas discharge line G1 Conveying air G2 Combustion air Gb Cold air Gh Hot air Ge Exhaust gas F Fuel (fine powder fuel)

T Detection temperature Td Mill device outlet temperature Tu Mill device inlet temperature R Predetermined temperature range Rd Outlet side temperature range Ru Inlet side temperature range Bd Lower limit of temperature range (lower limit)
Bu Upper temperature range (upper limit)
B0 Lower limit opening

Claims (13)

A transfer air supply line for supplying transfer air for transferring fuel to the boiler;
An exhaust gas discharge line for discharging the exhaust gas generated by the combustion of the fuel inside the boiler to the outside;
An air preheater connected to each of the transfer air supply line and the exhaust gas discharge line, for preheating the transfer air flowing through the transfer air supply line with the exhaust gas flowing through the exhaust gas discharge line;
A bypass line for connecting the upstream side and the downstream side of the air preheater in the transfer air supply line, and for the transfer air to flow around the air preheater;
A cold air amount adjusting means provided in the bypass line and capable of adjusting a flow rate of the transfer air flowing through the bypass line;
A mill device for pulverizing the fuel to be supplied to the boiler, provided in the air supply line for conveyance;
Temperature detecting means for detecting the temperature of at least one of the outlet temperature or the inlet temperature of the mill device,
The opening degree of the cold air amount adjusting means is predetermined when the temperature detected by the temperature detecting means is in a normal operation where the temperature is within a predetermined temperature range set for each of the outlet temperature and the inlet temperature. Boiler system characterized by being fixed at an intermediate opening of   The boiler system according to claim 1, wherein the predetermined intermediate opening is 30% or less of the opening when fully opened and greater than 0%.   The apparatus further comprises a control device that changes the opening degree of the cold air amount adjusting means from the predetermined intermediate opening degree when the temperature detected by the temperature detecting means is out of the temperature range. The boiler system according to claim 1 or 2.   The said control apparatus makes the opening degree of the said cold air amount adjustment means larger than the said predetermined intermediate opening degree, when the said temperature exceeds the upper limit of the said temperature range. Boiler system.   The said control apparatus makes the opening degree of the said cold air amount adjustment means smaller than the said predetermined intermediate opening degree, when the said temperature falls below the minimum of the said temperature range. The boiler system described in A transfer air amount adjusting means for adjusting a flow rate of the transfer air supplied to the mill device provided in the transfer air supply line;
When the opening degree of the cold air amount adjusting means becomes a lower limit opening degree that is an opening degree smaller than the predetermined intermediate opening degree, the control device uses the conveying air amount adjusting means to The boiler system according to claim 5, wherein the flow rate of air is increased. A combustion air supply line for supplying combustion air to the boiler;
The combustion air supply line is connected to the air preheater;
The air preheater simultaneously preheats the transfer air flowing through the transfer air supply line and the combustion air flowing through the combustion air supply line with the high-temperature exhaust gas flowing through the exhaust gas discharge line. The boiler system according to any one of claims 1 to 6.   The opening degree of the cold air amount adjusting means is fixed to the predetermined intermediate opening degree when the boiler is operated with a partial load in the normal operation. The boiler system according to any one of Items 1 to 7. The operation method of the boiler system according to any one of claims 1 to 8,
A mill temperature acquisition step of acquiring at least one of the outlet temperature of the mill device or the inlet temperature;
A normality determining step of determining whether or not the boiler system is in a normal operation depending on whether or not the temperature acquired in the mill temperature acquiring step is within a predetermined temperature range;
Provided in a bypass line for bypassing the air preheater that preheats the transport air flowing through the transport air supply line when the normal operation time is determined in the normality determination step. A cold air amount adjusting means that maintains the predetermined intermediate opening degree of the cold air amount adjusting means that is fixed at a predetermined intermediate opening degree when the boiler system is in normal operation. And a step of maintaining the opening degree.   The boiler system operation method according to claim 9, wherein the predetermined intermediate opening is 30% or less of the opening when fully opened and greater than 0%.   The opening degree increasing step of making the opening degree of the cold air amount adjusting means larger than the predetermined intermediate opening degree when the temperature exceeds the upper limit of the temperature range is further provided. The operation method of the boiler system of 9 or 10.   The control device further includes an opening degree throttle step for reducing an opening degree of the cold air amount adjusting means to be smaller than the predetermined intermediate opening degree when the temperature falls below a lower limit of the temperature range. The operation method of the boiler system according to any one of claims 9 to 11, wherein the boiler system is operated.   When the opening degree of the cold air amount adjusting means becomes a lower limit opening degree that is smaller than the predetermined intermediate opening degree, the cold air amount adjusting means is supplied to the mill device provided in the conveying air supply line. The boiler system according to claim 12, further comprising a transfer air increasing step of increasing the flow rate of the transfer air using a transfer air amount adjusting unit that adjusts the flow rate of the transfer air. how to drive.

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