JP2005241043A - Heat utilization system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat utilization system capable of preventing burnout of a superheater, in regard to a heat utilization system capable of reducing economic burden to be required to manufacture and maintenance of the superheater. <P>SOLUTION: The heat utilization system is provided with a boiler 5 for generating steam by utilizing the heat of the predetermined heat source, the superheater 6 for generating superheated steam by superheating the steam, a steam turbine 14 for generating power with the superheated steam, a heat load utilizing the heat of the steam, a first steam route R1 for leading a part of the steam generated in the boiler 5 into the heat load without passing through the superheater 6, and a second steam route R2 for directly leading at least one of the residual steam generated by the boiler 5 into the steam turbine 14 through the superheater 6. This heat utilization system has a first adjusting means 25 for adjusting quantity of the steam in the first steam route R1 and a monitor means 28 for monitoring quantity of the steam in the second steam route R2, and the first adjusting means 25 is controlled so that the quantity of the steam in the second steam route R is the predetermined quantity or more. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention uses a boiler that generates steam using heat of a predetermined heat source, a superheater that generates superheated steam by superheating the steam, a steam turbine that generates power using superheated steam, and the heat of the steam The present invention relates to a heat utilization system including a heat load.

  2. Description of the Related Art Conventionally, as an example of a heat utilization system, one that utilizes the heat of high-temperature exhaust gas generated from a garbage incinerator is known. In the case of a heat utilization system associated with a garbage incinerator, normally, steam generated from a boiler by the heat of exhaust gas is superheated by a superheater and then temporarily accumulated in a steam reservoir. And, a part of the steam superheated from the steam reservoir is a combustion air preheater for preheating air necessary for combustion of garbage in the garbage incinerator, an exhaust gas reheater for reheating exhaust gas, and an outside of the incineration facility Sent to heat utilization facilities such as greenhouses and house cultivation. The remainder of the superheated steam is sent to a steam turbine, and a part of the thermal energy of the exhaust gas is recovered in the form of electric energy by a generator connected to the steam turbine.

  On the other hand, the heat transfer part (usually composed of a tube group in which a large number of thin pipes are gathered together) constituting the heat energy input part of the superheater is high in temperature (such as around 600 ° C.) and has strong oxidizing power. In some cases, since it is exposed to an exhaust gas containing a corrosive gas, it is necessary to configure it with an expensive alloy material such as special stainless steel or Inconel having a particularly high heat resistance temperature such as Fire SUS310J1. For this reason, if the heat exchange capability required for the superheater is increased, it is necessary to increase the total area of the heat transfer surface. As a result, the initial cost required for production and the running cost for periodically replacing the heat transfer section corroded by the exhaust gas are increased, and the total economic burden is greatly increased, so a countermeasure has been desired.

  To solve the above problems, only the steam turbine needs superheated steam, so only the amount of steam used in the steam turbine is supplied to the superheater, and the remaining steam is supplied to the superheater. The heat utilization system (for example, refer patent document 1) sent to a combustion air preheater etc. without going through is examined. According to this heat utilization system, since the amount of steam supplied to the superheater is reduced, the heat exchange capacity of the superheater can be set low. For this reason, since the total area of the heat transfer surface of the superheater can be reduced as compared with the conventional one, the initial cost required for manufacturing the superheater and the running cost for maintenance can be reduced.

JP 2002-310401 A (page 2-4, FIG. 1)

  In the conventional heat utilization system, generally, steam generated from the boiler is preferentially sent to a combustion air preheater or the like in order to maintain the operation of the refuse incinerator, and only the remaining steam passes through the superheater. Sent to the turbine. For this reason, when the amount of steam used for the combustion air preheater or the like is large, or when the amount of steam generated from the boiler is small, the amount of steam sent to the steam turbine decreases. As a result, the superheater is exposed to high-temperature exhaust gas in a state where almost no steam is sent, and thus there is a problem of burning out. Therefore, although the conventional heat utilization system is intended to reduce the economic burden required for the production and maintenance of the superheater, as a result, the maintenance cost of the superheater is increased.

  The present invention has been made in view of the above problems, and in the heat utilization system that can reduce the economic burden required for the manufacture and maintenance of the superheater, a heat utilization system that can prevent the superheater from burning out. It is intended to provide.

  In order to achieve the above object, a first characteristic configuration of a heat utilization system according to the present invention includes a boiler that generates steam by using heat of a predetermined heat source, and a superheater that superheats the steam to generate superheated steam. A steam turbine that generates electric power using the superheated steam, a heat load that uses the heat of the steam, and a first part that introduces a portion of the steam generated in the boiler into the heat load without passing through the superheater. A heat utilization system comprising: a steam path; and a second steam path for directly introducing at least a part of the remaining steam generated in the boiler into the steam turbine via the superheater, wherein the first steam path The first adjustment means for adjusting the amount of steam in the second steam passage and the monitoring means for monitoring the amount of steam in the second steam path, the first adjustment so that the steam amount in the second steam path is equal to or greater than a predetermined amount. There is a point to control the stage.

  That is, according to this configuration, by controlling the amount of steam sent to the heat load, it is possible to secure a predetermined amount or more of the amount of steam in the second steam path, that is, the amount of steam passing through the superheater. For this reason, burning of the superheater can be prevented. By extending the life of the superheater, not only the initial cost required for manufacturing the superheater but also the running cost for maintenance can be reduced.

  The second characteristic configuration of the heat utilization system according to the present invention is a third steam path for branching the superheated steam from the second steam path and introducing it into the heat load, and a steam amount in the third steam path is adjusted. And a second adjusting means for controlling the second adjusting means so that a total amount of the steam introduced into the heat load and the superheated steam is equal to or greater than a predetermined amount.

  That is, according to this configuration, a predetermined amount or more of steam can be preferentially sent to a heat load such as a steam reservoir or a combustion air preheater that temporarily accumulates steam. For this reason, the operation of the heat utilization system can be continued while securing a predetermined amount or more of steam passing through the superheater to prevent burning.

  A third characteristic configuration of the heat utilization system according to the present invention includes a boiler that generates steam using heat of a predetermined heat source, a steam reservoir that accumulates the steam generated in the boiler, and superheats the steam. A superheater that generates superheated steam, a steam turbine that generates power using the superheated steam, a heat load that uses the heat of the steam, and a part of the steam that has accumulated in the steam reservoir without passing through the superheater A first steam path for introducing into the heat load; a second steam path for introducing at least a part of the remaining steam accumulated in the steam reservoir into the steam turbine via the superheater; and the first steam path. Adjusting means for adjusting the steam amount in the second steam path and monitoring means for monitoring the steam amount in the second steam path, and controlling the adjusting means so that the steam quantity in the second steam path is equal to or greater than a predetermined amount. There is a point.

  That is, according to this configuration, by controlling the amount of steam sent to a heat load other than the steam reservoir that temporarily accumulates all the steam generated in the boiler, it is possible to secure a predetermined amount or more of steam that passes through the superheater. it can. For this reason, burning of the superheater can be prevented. Furthermore, since a predetermined amount or more of steam can always be sent to the steam turbine, power can be generated continuously.

Hereinafter, the case where it applies to a refuse incinerator as one embodiment of the heat utilization system concerning the present invention is explained with reference to drawings.
As shown in FIG. 1, the refuse incinerator 1 according to the present embodiment is a hopper 2 for putting in garbage as an incineration object, and injecting the introduced garbage through respective steps of drying, combustion and post-combustion And a combustion chamber 3 that performs. A flue 4 that guides high-temperature exhaust gas generated in the combustion chamber 3 toward the chimney 11 at the final stage extends from the upper part of the combustion chamber 3. Exhaust gas discharged further downstream from the flue 4 is sent to a dust collecting bag filter 8 via a downstream side flue 4 a provided with a economizer 7, and a denitration device 9 using activated carbon and exhaust gas recirculation. The air is emitted from the chimney 11 through the heating device 10. A waste heat boiler 5 that generates steam by heat of exhaust gas flowing through the flue 4 is disposed above the flue 4. The economizer 7 is for preheating water supplied to the waste heat boiler 5, and the exhaust gas reheating device 10 is for reheating the exhaust gas in order to increase the adsorption rate of nitrogen in the exhaust gas by activated carbon. .

  A part of the steam taken out from the waste heat boiler 5 is superheater 6 as steam used in the combustion air preheater 20, the exhaust gas reheater 10, or a heat utilization facility such as a greenhouse or house cultivation outside the incineration facility. Without passing through the first steam path R <b> 1 connecting the waste heat boiler 5 and the high pressure steam reservoir 12 to the high pressure steam reservoir 12. Most of the heat held by the steam sent to the combustion air preheater 20 is consumed for preheating the primary combustion air to be put into the combustion chamber 3 of the incinerator 1. The water cooled and condensed by the combustion air preheater 20 is guided to the deaerator 18, and returned from the deaerator 18 to the waste heat boiler 5 through the economizer 7. The high-pressure steam reservoir 12, the combustion air preheater 20, the exhaust gas reheater 10, and a heat utilization facility such as a greenhouse outside the incineration facility or house cultivation are examples of “heat load”.

  A low pressure steam reservoir 13 is connected to the high pressure steam reservoir 12 via a pressure reducing valve 22. The heat held by the steam accumulated in the low-pressure steam reservoir 13 is taken out by the heat exchanger 19 and sent to a heat utilization facility such as a greenhouse or house cultivation outside the incineration facility for use. The steam itself sent from the low-pressure steam reservoir 13 is condensed in the heat exchanger 19 and returned to the condensate tank 16. The low-pressure steam reservoir 13 and the heat exchanger 19 are also examples of “heat load”.

  The remainder of the steam taken out from the waste heat boiler 5 is sent to the superheater 6 in the flue 4 via the second steam path R2a (R2) connecting the waste heat boiler 5 and the superheater 6. The steam sent to the superheater 6 is superheated by the heat of the exhaust gas flowing from the combustion chamber 3 to become superheated steam, and is sent to the steam turbine 14 via the second steam path R2b (R2). The thermal energy of the superheated steam is converted into electric energy by a generator 21 connected to the steam turbine 14. Further, the expanded steam discharged from the steam turbine 14 is condensed by the condenser 15 and accumulated in the open-type condensate tank 16. The water stored in the condensate tank 16 is guided to the deaerator 18 through a pump 17 provided in the return flow path. The second steam path R2a and the second steam path R2b constitute a second steam path R2 that connects the waste heat boiler 5 and the steam turbine 14 via the superheater 6. A second steam path R2b connecting the superheater 6 and the steam turbine 14 is provided with a third steam path R3 for introducing the superheated steam into the high-pressure steam reservoir 12.

  The first steam path R1 is provided with a first adjustment valve 25 for adjusting the amount of steam sent from the waste heat boiler 5 to the heat load, and the second steam path R2 includes a second adjustment valve 26 and a steam amount sensor. 28 are provided. The second regulating valve 26 is for keeping the steam pressure of the superheated steam introduced from the superheater 6 to the steam turbine 14 at a set value or higher, and can be replaced with a pressure valve in the steam turbine 14. The steam amount sensor 28 monitors the amount of steam passing through the second steam path R2. When the steam amount sensor 28 detects that the amount of steam passing through the second steam path R2 is less than a predetermined amount, the heat utilization system according to the present embodiment adjusts the first adjustment valve 25 to adjust the first steam path. The amount of steam passing through R1 is controlled. Although the steam amount sensor 28 is provided in the second steam path R2b in FIG. 1, the installation position is not limited as long as the amount of steam flowing through the superheater 6 can be monitored, and it may be provided at an arbitrary position. it can.

  The third steam path R3 is provided with a third control valve 27 that adjusts the amount of steam introduced from the second steam path R2 into the high-pressure steam reservoir 12. The high-pressure steam reservoir 12 is provided with a vapor pressure sensor 29 to monitor the vapor pressure of the high-pressure steam reservoir 12. Then, by adjusting the first adjustment valve 25 as described above, when the amount of steam sent from the first steam path R1 to the steam reservoir 12 decreases and the steam pressure decreases, this is detected, and the third adjustment valve 27 is detected. Is controlled to adjust the amount of steam sent from the third steam path R3 to keep the steam pressure constant. Note that the third steam path R3 and the third regulating valve 27 are not necessarily provided, and the object of the present invention can be achieved without providing them. However, the provision of the third steam path R3 and the third regulating valve 27 always prevents the superheater from burning out. It becomes possible to secure a predetermined amount or more of steam in the heat load, and the heat utilization system of this embodiment can be operated continuously.

  The garbage incinerator 1 according to the present embodiment is configured as described above. Hereinafter, an example of the control will be described with reference to FIGS. 2 and 3. In the present embodiment, the control of the first adjustment valve 25 and the control of the third adjustment valve 27 are performed independently, and FIG. 3 shows the flow chart of the control of the first adjustment valve 25. In addition, the following description is description about control of the amount of steam when the steam taken out from the waste heat boiler 5 is introduced into the heat load and the steam turbine 14, and other controls and operations are the conventional ones. It is the same as the device.

  When the waste incinerator 1 is operated, steam generated by the heat of the exhaust gas is taken out from the waste heat boiler 5 and introduced into the first steam path R1 and the second steam path R2. Normally, the first adjustment valve 25 is in a fully open state. The steam taken out from the waste heat boiler 5 is preferentially introduced into the first steam path R1 and used for heat load so that the high-pressure steam reservoir 12 maintains a constant steam pressure. The remaining steam is introduced into the second steam path R2, is sent to the steam turbine 14 via the superheater 6, and is used for power generation. While only the amount of steam from the first steam path R1 is sufficient to keep the steam pressure of the high-pressure steam reservoir 12 constant, the third regulating valve 27 is in a completely closed state.

  The steam amount sensor 28 monitors the amount of steam in the second steam path R2b, that is, the amount of steam passing through the superheater 6, and remains as it is while maintaining a predetermined value or more (# 1: Yes). maintain. When the steam amount sensor 28 detects that the steam amount in the second steam path R2b that has passed through the superheater has become lower than a predetermined value (# 1: No), the first regulating valve 25 is closed by one step (# 2) Thus, the amount of steam introduced into the first steam path R1 is reduced and the amount of steam introduced into the second steam path R2 is increased. When the steam amount sensor 28 checks the steam amount again and does not reach the predetermined value (# 3: No), it further closes the first regulating valve 25 (# 2), and the steam in the second steam path R2 The first adjustment valve 25 is adjusted until the amount reaches a predetermined value (# 2 to # 3).

  While the amount of steam in the second steam path R2b is maintained at a predetermined value (# 4: predetermined value), monitoring is continued, and the amount of steam taken out from the waste heat boiler 5 is changed. When the steam amount is less than the predetermined value (# 4: less than the predetermined value), the process returns to # 2, and the adjustment of the first adjustment valve 25 is repeated (# 2 to # 3). If the steam amount is larger than the predetermined value (# 4: larger than the predetermined value), the first adjustment valve 25 is opened one step (# 5). Thus, when the steam amount reaches a predetermined value (# 6: Yes), the process returns to # 4 again, and the same control is repeated while monitoring the steam amount by the steam amount sensor 28. When the steam amount does not reach the predetermined value (# 6: No), it is checked whether or not the first adjustment valve 25 is fully opened (# 7). When the steam amount is not fully opened (# 7: No). Returning to # 5, the first adjustment valve 25 is further opened, and the same adjustment is repeated (# 5 to # 7). When the first regulating valve 25 is fully open (# 7: Yes), the flow returns to the normal state (# 1) and the steam amount is monitored.

  The third regulating valve 27 in the third steam path R3 is normally closed, but during this time, when the vapor pressure of the high pressure steam reservoir 12 becomes lower than the set value due to the operating condition of the first regulating valve 25, The third regulating valve is opened to introduce steam into the high-pressure steam reservoir 12 from the third steam path R3, and the third regulating valve 27 is adjusted until the vapor pressure reaches a set value. And when the vapor pressure of the high-pressure steam reservoir 12 reaches a set value, it is assumed that the steam used for the heat load is sufficient, and that state is maintained. When the vapor pressure becomes higher than the set value, the third adjustment valve 27 is closed to adjust the vapor pressure.

  In the heat utilization system of the present embodiment, the amount of steam introduced into the heat load is monitored by the vapor pressure sensor 29 in the high pressure reservoir 12, but is not particularly limited. It is also possible to monitor and control the amount of steam in the third steam path R3 and the amount of steam introduced into the combustion air preheater 20, which is one of the heat loads. Furthermore, without monitoring the amount of steam introduced into the heat load, when the first adjustment valve is closed, it is detected that the amount of steam introduced into the heat load has decreased, and the third adjustment valve 27 is opened and closed. It is also possible to adopt a configuration. At this time, if the steam is preferentially introduced into the steam reservoir 12 rather than the steam turbine 14 at the branch point from the second steam path R2 to the third steam path R3, the third regulating valve 27 is strictly It is also possible to perform only simple opening / closing control without performing any control.

  Furthermore, in the heat utilization system of the present embodiment, the amount of steam introduced into the superheater 6 is controlled to maintain a predetermined value. However, the present invention is not limited to the above control, and the state is maintained when the amount of steam exceeds a predetermined value. Simple control for monitoring only so as not to become less than a predetermined value can also be adopted. Note that the predetermined value and set value to be controlled in the present embodiment vary depending on the type of the refuse incinerator 1 and the superheater 6 and can be arbitrarily determined depending on the heat utilization system to be applied.

(Another embodiment)
In the above embodiment, in order to keep the refuse incinerator 1 in operation, the steam is used for “heat load”, particularly the supply to the combustion air preheater 20 is maintained. The utilization system can also be applied to facilities whose main purpose is power generation as shown in FIG. That is, in this embodiment, the first high-pressure steam reservoir 12 that temporarily accumulates all the steam taken out from the waste heat boiler 5 is introduced into the heat load from the high-pressure steam reservoir 12 without passing through the superheater 6. A steam path R1 and a second steam path R2 introduced from the high-pressure steam reservoir 12 to the steam turbine 14 via a superheater are provided.

  The first steam path R1 is provided with an adjusting valve 30 that controls the steam quantity of the second steam path by adjusting the steam quantity of the first steam path, and the steam sensor 31 is provided in the second steam path R2. Is provided. The steam sensor 31 adjusts the regulating valve 30 so that the steam amount sensor 28 has a steam amount passing through the second steam path R2 equal to or greater than a predetermined value. With this configuration, even if the amount of steam taken out from the waste heat boiler 5 fluctuates, a predetermined amount of steam can be secured in the steam turbine 14, so that it is possible to continuously generate power. Other configurations, control, and the like are the same as those in the above embodiment.

  The heat utilization system of the present invention can be applied not only to an incinerator for garbage etc., but also to a heat utilization system using various heat sources.

Schematic of an incineration facility equipped with the heat utilization system of the present invention Schematic diagram of heat utilization system of this embodiment Control flow diagram of this embodiment Schematic of heat utilization system of another embodiment

Explanation of symbols

1 Waste incinerator 3 Combustion chamber 4 Flue 5 Waste heat boiler 6 Superheater 10 Exhaust gas reheater (heat load)
12 High pressure steam reservoir (heat load)
13 Low pressure steam reservoir (heat load)
14 Steam turbine 20 Combustion air preheater (heat load)
25 1st adjustment valve 26 2nd adjustment valve 27 3rd adjustment valve 28 Steam quantity sensor 29 Steam pressure sensor R1 1st steam path R2 (R2a, R2b) 2nd steam path R3 3rd steam path

Claims (3)

A boiler that generates steam by using heat of a predetermined heat source, a superheater that generates superheated steam by superheating the steam, a steam turbine that generates power using the superheated steam, and heat that uses heat of the steam A load, a first steam path for introducing a part of the steam generated in the boiler into the heat load without passing through the superheater, and at least a part of the remaining steam generated in the boiler in the superheater. A heat utilization system comprising a second steam path directly introduced into the steam turbine via
A first adjusting unit that adjusts the amount of steam in the first steam path; and a monitoring unit that monitors the amount of steam in the second steam path; A heat utilization system for controlling the first adjusting means.   A third steam path for branching the superheated steam from the second steam path and introducing it into the thermal load; and a second adjusting means for adjusting the amount of steam in the third steam path; 2. The heat utilization system according to claim 1, wherein the second adjustment unit is controlled so that a total amount of the steam and the superheated steam is equal to or greater than a predetermined amount.   A boiler that generates steam using the heat of a predetermined heat source, a steam reservoir that accumulates the steam generated in the boiler, a superheater that generates superheated steam by overheating the steam, and power generation using the superheated steam A steam turbine that performs heat, a heat load that uses the heat of the steam, a first steam path that introduces a portion of the steam accumulated in the steam reservoir into the heat load without passing through the superheater, and the steam A second steam path for introducing at least a part of the remaining steam accumulated in the reservoir into the steam turbine via the superheater; an adjusting means for adjusting the amount of steam in the first steam path; and the second steam A heat utilization system that controls the adjustment unit so that the amount of steam in the second steam path is equal to or greater than a predetermined amount.

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