JP4611373B2 - Gas turbine equipment, fuel gas supply equipment, and fuel gas calorie increase suppressing method - Google Patents

Description

  The present invention relates to a gas turbine facility, a fuel gas supply facility, and a fuel gas calorie increase suppressing method. More specifically, a fuel gas supply facility that supplies a gas whose calorific value (also referred to as calorie) fluctuates, such as low calorie gas, as fuel for the gas turbine, a gas turbine facility equipped with the fuel gas supply facility, and the gas The present invention relates to a method for suppressing an increase in calorific value of gas for turbine fuel.

In the field of iron making, for example, when pig iron is produced by the blast furnace method, a furnace top gas (Blast Purchase Gas, hereinafter referred to as BFG) is generated as a by-product gas from the blast furnace. Since the total calorific value of BFG reaches about half of the calorific value of the coke used, BFG is widely used in steelworks to reduce the cost of ironmaking. BFG is generated about 3000 Nm ³ per ton of input coke, and its composition is 10 to 18% by volume of carbon dioxide (CO ₂ ) (hereinafter simply referred to as%), 22 to 30% of carbon monoxide (CO), nitrogen _{(N 2)} is 52 to 60%, hydrogen _{(H 2)} is from 0.5 to 4%, methane (CH ₄₎ is about 0.5% to 3%.

Because BFG contains 2 to 10 g / Nm ³ of flue dusts in addition to this, after removal of up to about 0.01 g / Nm ³ in the dust collector so as calorific value 800 kcal / Nm ³ about the fuel gas, a hot air furnace, Used in coke ovens, heating furnaces, boilers, etc. In recent years, gas turbines can also be burned with low calorie gas due to improvements in technology, and the number of cases where power is generated using BFG as a gas turbine fuel is increasing. The low calorie gas mentioned here is defined as a gas having a calorific value of about 12 MJ / Nm ³ or less. As will be described later, the low calorie gas is not limited to blast furnace gas (BFG) but includes many other types of gases such as converter gas (LDG) and mixed gases thereof.

  On the other hand, in recent years, new iron-making processes other than the blast furnace method (for example, direct reduction iron methods such as FINEX and COREX) are being developed, and combustion methods that can be applied to the effective use of by-product gases generated from such new processes. Is waiting for development. In any steelmaking process, the characteristics (gas composition and calorie) of the by-product gas generated vary depending on the equipment and operation content. Even in the same facility, it changes from moment to moment according to the characteristics of each raw material and the reaction process, and does not become constant.

  Looking at calorie, which is the most important characteristic when using byproduct gas as gas turbine fuel, the upper limit of the allowable fluctuation range of calorie inherent to each gas turbine (for example, about + 10% of the average calorie value) When it exceeds, that is, when the calorie increases rapidly, the combustion temperature in the combustor of the gas turbine may suddenly become an abnormally high temperature. As a result, there is a possibility that the burner portion, the stationary blades and the moving blades of the turbine are damaged and the life is shortened. In this case, economical continuous operation of the gas turbine facility becomes difficult.

A technique of diluting with so-called pure nitrogen gas (N ₂ ) in order to suppress calorie fluctuation of by-product gas is known (see, for example, Patent Document 1 and Patent Document 2). However, when diluting the by-product gas with an inert gas such as N ₂ purified to a high purity, a large amount of an expensive inert gas such as N ₂ must be used depending on the variation value of calories. Moreover, it is very difficult to secure a large amount of inert gas continuously except for a special industrial field. Furthermore, it is necessary to extend a large amount of inert gas storage facilities and various equipment facilities for supplying gas including piping. For these reasons, purchasing and using pure inert gas reduces the economics of gas turbine power generation and hinders the technical advantages of gas turbines that advocate high efficiency.
JP 2002-155762 A JP 9-317499 A

  The present invention has been made to solve the above-described problems, and has a low equipment cost and an operating cost, and a fuel gas supply facility capable of reducing fluctuations in calories of fuel gas for a gas turbine, and the fuel gas supply facility. The object is to provide a gas turbine facility provided with the above and a method for suppressing an increase in the calorific value of gas for a gas turbine fuel.

For the above purpose, the fuel gas supply facility of the present invention comprises:
A fuel gas supply passage for supplying gas to the gas turbine as fuel;
A waste nitrogen supply passage connected to the fuel gas supply passage for supplying waste nitrogen generated in at least one of an oxygen production plant and a nitrogen production plant to the fuel gas supply passage;
A mixer for mixing the gas and the waste nitrogen;
A calorific value detection device for detecting a calorific value in the gas disposed in the fuel gas supply passage;
An oxygen concentration detection device for detecting the oxygen concentration in the gas, disposed in either one or both of the fuel gas supply passage and the waste nitrogen supply passage;
And a control device capable of controlling the waste nitrogen supply operation by the waste nitrogen supply passage based on the detection results of the calorific value detection device and the oxygen concentration detection device .

According to this invention, the calorific value of the gas and the oxygen content of the waste nitrogen or the oxygen content of the gas mixed with the waste nitrogen are detected, so that the flammability limit and the safety factor are based on the detected oxygen content. And calculating the maximum allowable mixing ratio of waste nitrogen taking into account and mixing the waste nitrogen with the maximum allowable mixing ratio as the upper limit based on the calorific value of the detected gas, and reducing the heat effect of the fuel gas Can be realized. Thus, the amount of waste nitrogen determined based on the calorific value of the gas and the oxygen content of the waste nitrogen or the gas mixed with the waste nitrogen is mixed with the gas (low calorie gas), so that the gas turbine The calorific value of the supplied fuel gas can be suitably controlled. Waste nitrogen generated as a by-product to be discarded in an oxygen production plant, and waste nitrogen produced in a nitrogen production plant but discarded because it contains trace amounts of oxygen, can be used as a diluent gas for fuel gas it can. By increasing the amount of nitrogen, which is a nonflammable gas, and diluting the fuel gas by mixing waste nitrogen that is extremely easy to procure and inexpensive, it is possible to suppress an increase in the calorie of the fuel gas. Here, the calorific value detection device includes not only a device that directly measures the calorific value of gas (for example, a so-called calorimeter) but also a device that measures the content of combustible components in the gas.

  When the maximum allowable caloric value of the gas supplied as fuel to the gas turbine is set and the caloric value of the fuel gas exceeds the maximum allowable caloric setting value, the control device generates waste nitrogen from the waste nitrogen supply passage. It can be configured to supply.

  A state where an inert gas supply passage for supplying an inert gas is connected to the fuel gas supply passage, and the control device supplies waste nitrogen to the fuel gas supply passage through the waste nitrogen supply passage The fuel gas supply facility is preferably configured to control the inert gas supply operation by the inert gas supply passage based on the detection result of the calorific value detection device. This is because if the supply of waste nitrogen is stopped or decreased, the dilution effect of the fuel gas can be supplemented by the high-purity inert gas when the suppression of the calorie increase of the fuel gas is insufficient.

  A storage tank for temporarily storing waste nitrogen supplied from at least one of an oxygen production plant and a nitrogen production plant can be disposed in the waste nitrogen supply passage. This is to maintain a stable supply of waste nitrogen.

  An oxygen concentration fluctuation suppression tank that temporarily stores waste nitrogen supplied from at least one of an oxygen production plant and a nitrogen production plant is disposed in the waste nitrogen supply passage, and a gas inlet and a gas are provided in the oxygen concentration fluctuation suppression tank. It is preferable that an upstream side of the waste nitrogen supply passage is connected to the gas inlet, and a downstream side of the waste nitrogen supply passage is connected to the gas outlet. Waste nitrogen that has been supplied while the oxygen concentration fluctuates is mixed in the oxygen concentration fluctuation suppression tank, so that a small amount of oxygen concentration fluctuations, which are by-products contained in waste nitrogen, are made uniform, and waste nitrogen This is because the safety as a dilution gas is stabilized.

  In each of the above facilities, a tank for temporarily storing fuel gas is disposed in the fuel gas supply passage, and the tank has a gas inlet and a gas outlet. Preferably, the upstream side of the supply passage is connected, and the downstream side of the fuel gas supply passage is connected to the gas outlet. Since the fuel gas supplied through the fuel gas supply passage is temporarily stored in the tank and mixed therein, the width of the calorie fluctuation is reduced and the speed of calorie fluctuation is reduced. This is because calorie leveling control by dilution with waste nitrogen in the downstream portion of the tank is further facilitated. The calorific value detection device described above is installed in the fuel gas supply passage. However, in a facility in which a tank is installed in the fuel gas supply passage, these tanks also constitute the fuel gas supply passage. Installing in the gas supply passage includes installing in the tank.

  Two types of gas inlets are formed in the tank, one of the gas inlets is connected to the upstream side of the fuel gas supply passage, and the other gas inlet is connected to the downstream side of the fuel gas supply passage. A gas pressure feeding device that connects the passages and pumps the fuel gas toward the tank can be installed in the return passage.

  A return passage is connected between the fuel gas supply passage upstream of the tank and the fuel gas supply passage downstream of the tank, and the fuel gas is directed toward the fuel gas supply passage upstream of the tank. A gas pumping device for pumping can be installed.

  A tank for temporarily storing fuel gas is disposed in the fuel gas supply passage, and an outlet passage for returning the fuel gas from the tank to the fuel gas supply passage between the fuel gas supply passage and the tank; A fuel gas supply facility in which an upstream inlet passage for feeding fuel gas into the tank from the upstream side of the connection point with the outlet passage in the fuel gas supply passage is preferable. This is also because the fuel gas is mixed in the tank, whereby the width of the calorie fluctuation is reduced and the speed of calorie fluctuation is reduced.

  Note that any of the tanks described above may be a fixed-type tank whose internal volume does not change, and the internal volume used as a device (gas holder) for monitoring the gas supply-demand balance in a conventional gas turbine facility or the like. It may be a fluctuating tank. The internal volume variation type tank is a tank having an airtightly attached lid member that can move up and down according to the tank internal pressure, and a tank that can maximize the balance effect by positively moving the lid member up and down by a driving device. A tank or the like whose volume can be selected.

  Alternatively, with respect to this fuel gas supply facility, instead of the upstream inlet passage, or together with the upstream inlet passage, the downstream side from which fuel gas is fed into the tank from the connection point with the outlet passage in the fuel gas supply passage An inlet passage may be disposed, and a gas pressure feeding device that pumps fuel gas toward the tank may be disposed in the downstream side inlet passage.

  In the fuel gas supply facility having the tank, a return passage is connected between a downstream side from a connection point with the outlet passage in the fuel gas supply passage and an upstream side from a connection point with the inlet passage in the fuel gas supply passage. A gas pumping device that pumps fuel gas toward the upstream fuel gas supply passage can be installed in the return passage.

  It is preferable to install a stirring device for stirring the gas inside the tank described above.

The fuel gas supply passage further includes a return passage connected between an upstream portion and a downstream portion, and a part of the fuel gas flowing through the fuel gas supply passage is transferred from the downstream portion of the fuel gas supply passage to the return passage. It is preferable that a gas pumping device for pumping toward the upstream portion is provided. This is because the same operation as the operation by the tank is performed.
A gas turbine and a fuel gas supply facility for supplying gas as fuel to the gas turbine are provided, and this fuel gas supply facility is any one of the above-described fuel gas supply facilities.

The method for suppressing the rise in calories of fuel gas for gas turbine fuel of the present invention is as follows.
A calorie measuring step for measuring the calorific value of the gas supplied as fuel to the gas turbine;
A waste nitrogen mixing step of mixing waste nitrogen generated in at least one of the oxygen production plant and the nitrogen production plant into the fuel gas when the measurement result exceeds the set allowable caloric value.

  In addition, a calorie increase suppressing method that further includes a step of mixing an inert gas into the fuel gas when it is determined that the calorific value measurement result does not fall below the set allowable caloric value due to waste nitrogen supply.

According to the present invention, a facility for supplying a fuel gas that can fluctuate in calories, such as a process by-product gas, to a gas turbine is realized with low facility costs and operation costs. For example, when supplying a gas whose calorific value fluctuates, such as low calorie gas, in order to suppress the calorie rise of the gas, it is easy to dispose of the waste nitrogen occupied by the incombustible gas of N ₂ for most of its gas components. This is because it can be obtained in large quantities.

FIG. 1 is a piping diagram showing an outline of a gas turbine power generation facility including a low calorie gas supply facility according to an embodiment of the present invention. FIG. 2 is a piping diagram showing an outline of a gas turbine power generation facility including a low calorie gas supply facility according to another embodiment of the present invention. FIG. 3 is a graph showing an example of the relationship between the mixing ratio of low calorie gas and air and the flammability limit of the air-fuel mixture, with the horizontal axis representing the volume ratio of low calorie gas and the vertical axis representing temperature. FIG. 4 is a graph showing an example of a state in which the calorie fluctuation of the low calorie gas is alleviated by passing through the buffer tank in FIG. 1 or FIG. FIG. 5 is a graph showing another example of the state where the calorie fluctuation of the low calorie gas is alleviated by passing through the buffer tank. FIG. 6 is a graph showing still another example of a state where the calorie fluctuation of the low calorie gas is alleviated by passing through the buffer tank. FIG. 7 is a piping diagram showing another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. FIG. 8 is a piping diagram showing still another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. FIG. 9 is a piping diagram showing still another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. FIG. 10 is a graph showing an example of a state where the calorie fluctuation of the low calorie gas is alleviated by passing through the buffer tank of FIG. 8 or FIG. FIG. 11 is a piping diagram showing still another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. 12 is a piping diagram showing another example of calorie fluctuation suppressing means that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. FIG. 13 is a piping diagram showing still another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. FIG. 14 is a piping diagram showing still another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG. FIG. 15 is a piping diagram showing still another example of a buffer tank that can be installed in the gas turbine power generation facility of FIG. 1 or FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 .... Low calorie gas supply equipment 2 .... Gas turbine 3 .... Low calorie gas supply piping 4 .... Waste nitrogen supply piping 5 .... Mixer 6 .... Dust collector 7 ······································································································································································· 14 .... high pressure compressor 15 .... cooler 16 .... combustor 17 .... flow control valve 18 .... filter 19 .... generator 20 .... (disposal) Nitrogen supply source 21... Nitrogen storage tank 22... (Waste nitrogen) oxygen fluctuation suppression tank 23... Oxygen concentration meter 24 ... Fan 25 ... Check valve 26 .... Stop valve 27 ... Flow meter 28 ... Flow control valve 29 ... Stop valve 0 ... Non-return valve 31 ... Disposal nitrogen discharge pipe 32 ... Flow control valve 33 ... Low calorie gas supply equipment 34 ... Inert gas supply pipe 35 ... Stop Valve 36 ... Flow meter 37 ... Flow control valve 38 ... Common piping 39 ... Fan 40 ... Gas amount balance monitoring device 41 ... Communication tube 42 ... -Tank 43 ... Lid member 44 ... Adjusting weight 45 ... Upstream inlet piping 46 ... Gas quantity balance monitoring device 47 ... Tank 48 ... Pressure detection device 49... Return pipe 50... Downstream side inlet pipe 51... Stirring device 52.

  Embodiments of a fuel gas supply facility of the present invention, a gas turbine facility including the fuel gas supply facility, and a method for suppressing an increase in the calorific value of the fuel gas will be described with reference to the accompanying drawings.

FIG. 1 is a piping diagram showing an outline of a gas turbine facility including a low calorie gas supply facility 1 which is an embodiment of the fuel gas supply facility of the present invention. A gas turbine power generation facility is exemplified as the gas turbine facility. As described above, low calorie gas is defined as a gas whose calorific value is about 12 MJ / Nm ³ or less. Low calorie gas often has characteristics such as calorie variation.

  The low-calorie gas supply facility 1 includes a low-calorie gas supply pipe 3 that supplies by-product gas (hereinafter referred to as low-calorie gas) generated directly in the reduced iron facility S as fuel to the gas turbine 2, and the calorie rise of the low-calorie gas. In order to suppress it, a waste nitrogen supply pipe 4 for supplying waste nitrogen as a diluent gas to the low calorie gas supply pipe 3 and a control device 100 for controlling the operation of the low calorie gas supply equipment 1 are provided.

The reason why waste nitrogen is mixed in order to dilute low calorie gas and suppress its rise in calories is because waste nitrogen contains a large amount of N ₂ but does not contain combustible gas. Waste nitrogen is released from oxygen production plants used in direct reduction iron methods such as the blast furnace method, FINEX method, and COREX method, and oxygen discharged from nitrogen production plants attached to the oxygen production plant. Nitrogen containing trace amounts of nitrogen. In the case of a direct reduction iron method such as the FINEX method or the COREX method, oxygen is used as a reducing agent, so it is essential to install an oxygen production plant that produces a large amount of oxygen. Since oxygen is also used in the blast furnace method, an oxygen production plant is used even if there is a difference in scale. The oxygen production plant separates nitrogen from air to produce oxygen, and the nitrogen after the separation of oxygen is normally released to the atmosphere as waste nitrogen. On the other hand, a high-purity nitrogen is often produced by adding a nitrogen production plant to the oxygen production plant. Even in this case, nitrogen containing a small amount of oxygen is diffused into the atmosphere as waste nitrogen. Such waste nitrogen has a gas composition of about 95 to 98% nitrogen gas and about 2 to 5% oxygen, and is a very safe dilution gas from the viewpoint of the flammability limit of low calorie gas. If these large amounts of discarded nitrogen are recovered and used, the operating cost becomes extremely low.

  In the upstream portion of the mixer 5 of the low calorie gas supply pipe 3, a dust collector 6 for removing dust from the low calorie gas directly sent from the reduced iron facility S and a buffer tank 10 for temporarily storing the low calorie gas are provided. And are installed. The buffer tank 10 is formed with an inlet 10a to which the upstream low calorie gas supply pipe 3 is connected and an outlet 10b to which the downstream low calorie gas supply pipe 3 is connected. In the buffer tank 10 of FIG. 1, the inlet 10a and the outlet 10b are formed in the vicinity of the lower end of the peripheral wall of the tank, but are not particularly limited to these forming positions. For example, you may form in the middle part of a tank surrounding wall, an upper part, the bottom part of a tank, etc.

  The buffer tank 10 has a relatively large capacity, and low calorie gas that is stationed while changing calories from moment to moment is mixed inside the buffer tank 10. The effect will be described later. On the downstream side of the buffer tank 10, a calorific value detection device 7 for detecting the calorific value of the low calorie gas and a flow meter 8 for measuring the flow rate are installed. The installation position of the flow meter 8 is not limited to the upstream side of the mixer 5. It may be downstream of the mixer 5. For example, it may be between the high pressure compressor 14 and the combustor 16 described later.

  The installation position of the calorific value detection device 7 is not limited to the downstream side of the buffer tank 10 and may be, for example, the upstream side of the buffer tank 10. By detecting in advance the gas calorie fluctuation upstream of the buffer tank 10, the calorific value control using the mixer 5 can be performed more reliably. Further, a calorific value detection device is installed on both the upstream side and the downstream side of the buffer tank 10, and the gas calorie fluctuation suppressing effect of the buffer tank 10 is monitored by both the calorific value detection devices. The overall performance of the calorie fluctuation suppression system can be grasped. The calorific value detection device can be directly attached to the buffer tank 10. In addition to the heat generation amount detection device 7 in the low calorie gas supply pipe 3, another heat generation amount detection device may be attached to the buffer tank 10.

  Here, as the calorific value detection device 7, a so-called calorimeter that directly measures the calorific value of gas, a device that measures the content (concentration) of combustible components, or the like is used. When importance is attached to the detection speed, it is preferable to use a combustible gas concentration detector at present. Concentration detection that detects the concentration of the combustible component that is mainly contained in the low-calorie gas applied and the combustible component that causes the main concentration fluctuation (for example, CO is a by-product gas in the direct reduction iron method) A vessel may be used. In this specification, these calorific value detection devices as a whole are referred to as “calorimeters”.

  Since the portion of the low calorie gas supply pipe 3 downstream from the mixer 5 is sometimes sent to the gas turbine 2 in a state where the low calorie gas is mixed with waste nitrogen, the pipe in this range is referred to as a mixed gas supply pipe 9. . The mixed gas supply pipe 9 is provided with a calorimeter 11 and an oxygen concentration meter 12 for measuring the oxygen concentration in the mixed gas. A low pressure fuel gas compressor (hereinafter referred to as a low pressure compressor) 13 and a high pressure fuel gas compressor (hereinafter referred to as a high pressure compressor) 14 of the gas turbine 2 are installed on the downstream side of the oxygen concentration meter 12 in that order. ing. Between both the compressors 13 and 14, the cooler 15 for cooling the mixed gas which is fuel gas is arrange | positioned. A flow rate adjusting valve (hereinafter referred to as a flow control valve) 17 for adjusting the turbine output is installed in the fuel pipe 9 a connected from the high-pressure compressor 14 to the combustor 16 of the gas turbine 2. Reference numeral 18 denotes a filter installed in a pipe for supplying waste nitrogen to the combustor 16. A generator 19 is connected to the gas turbine 2.

  FIG. 1 shows a type in which both the compressors 13 and 14 are rotationally driven by the turbine 2. However, the present invention is not limited to this, and both the compressors 13 and 14 are not coaxially connected to the turbine 2. You may comprise so that it may drive with a motor for exclusive use.

  The waste nitrogen supply facility will be described. The waste nitrogen supply pipe 4 extends from the oxygen production plant (or nitrogen production plant) 20 which is a waste nitrogen supply source to the mixer 5. The waste nitrogen supply pipe 4 is provided with a nitrogen storage tank 21 and an oxygen concentration fluctuation suppression tank 22. Any of these tanks 21 and 22 may be installed upstream (downstream).

  The nitrogen storage tank 21 temporarily stores the waste nitrogen from the supply source 20, so that even in an emergency situation where the supply of waste nitrogen from the supply source 20 suddenly stops or significantly decreases, the predetermined time is not exceeded. It is installed for the purpose of continuing to supply waste nitrogen. Moreover, the fluctuation | variation of the internal pressure of the waste nitrogen supply piping 4 can also be relieved. The nitrogen storage tank 21 may be connected to the waste nitrogen supply pipe 4 by only one communication pipe, and an inlet and an outlet are formed and connected to the upstream side and the downstream side of the waste nitrogen supply pipe 4 respectively. Also good.

  The oxygen concentration fluctuation suppression tank 22 is installed for the purpose of suppressing fluctuations in oxygen concentration in the waste nitrogen. If the fluctuation of the oxygen concentration is negligible, the oxygen concentration fluctuation suppressing tank 22 need not be installed. The oxygen concentration fluctuation suppression tank 22 has an inlet 22a and an outlet 22b, and 22a and 22b are connected to the waste nitrogen supply pipe 4 by an inlet pipe and an outlet pipe, respectively. With this configuration, all of the waste nitrogen supplied by the waste nitrogen supply pipe 4 flows into the oxygen concentration fluctuation suppression tank 22 and is mixed. As a result, even if there is a fluctuation in oxygen concentration in the supplied waste nitrogen, the fluctuation range of the oxygen concentration of waste nitrogen coming out from the outlet 22b of the oxygen concentration fluctuation suppression tank 22 is reduced, and the fluctuation speed is reduced. . That is, the fluctuation of the oxygen concentration is greatly relaxed (suppressed). When the oxygen concentration is relaxed in this way, safety as a dilution gas of waste nitrogen is stably exhibited.

  The oxygen concentration fluctuation suppression tank 22 can also be used as the nitrogen storage tank 21. In this case, it is not necessary to install the nitrogen storage tank 21 in the figure, and only the oxygen concentration fluctuation suppression tank 22 may be installed.

  The waste nitrogen supply pipe 4 is branched into two on the downstream side of the oxygen concentration fluctuation suppression tank 22 for the convenience of maintenance, etc., and the waste nitrogen is sucked from the supply source 20 and directed toward the fuel gas supply pipe 3. A fan 24 is installed as a gas pumping device for pumping the inside of the supply pipe 4. This fan 24 is not required when the pressure of waste nitrogen when generated at the source 20 is sufficiently high.

  A check valve 25 is disposed on the downstream side of each fan 24 to prevent backflow to the fan 24 side. The waste nitrogen supply pipe 4 is integrated again on the downstream side of both check valves 25. A stop valve 26, a flow meter 27, a flow control valve 28, an oxygen concentration meter 23, a stop valve 29, and a check valve 30 are installed in the portion of the waste nitrogen supply pipe 4 downstream from the integration point. The supply pipe 4 is connected to the mixer 5. The installation position of the oxygen concentration meter 23 is not particularly limited to the illustrated position, and can be installed at any position on the waste nitrogen supply pipe 4. When the oxygen concentration meter 23 is used in the calorie fluctuation suppression control of the low calorie gas, it is not necessary to use the oxygen concentration meter 12 of the mixed gas supply pipe 9 for the control. The check valve 30 is for preventing the low calorie gas from flowing back into the waste nitrogen supply pipe 4. The nitrogen storage tank 21 and the oxygen concentration fluctuation suppression tank 22 described above may be installed between the check valve 25 and the stop valve 26, respectively.

  Between the stop valve 26 and the flow meter 27 of the waste nitrogen supply pipe 4, a waste nitrogen discharge pipe 31 for releasing the waste nitrogen to the atmosphere is disposed. A flow control valve 32 is installed in the waste nitrogen discharge pipe 31.

  Next, an example of operation control of this facility by the control device 100 will be described. First, the low calorie gas is pumped toward the gas turbine 2 while monitoring the calorimeter 7 and the flow meter 8 of the low calorie gas supply pipe 3. At this time, in the waste nitrogen supply pipe 4, the stop valve 26 is already opened, the flow control valve 28 is closed, and the fan 24 is operating with the flow control valve 32 of the waste nitrogen discharge pipe 31 opened. That is, waste nitrogen is sucked and discharged from the waste nitrogen discharge pipe 31 to the atmosphere. The other stop valve 29 is open.

In the control device 100, an allowable calorie range for use of the fuel gas of each gas turbine 2 is set. That is, the reference calorie value (for example, 1600 kcal / Nm ³ ) and the fluctuation range (for example, ± 10% of the reference calorie value). Then, the flow control valve 28 of the waste nitrogen supply pipe 4 is opened so that the calorie value of the low calorie gas does not exceed the upper limit calorie value (for example, + 10%, 1760 kcal / Nm ³ ) of this allowable variation, and the waste nitrogen release The flow control valve 32 of the pipe 31 is adjusted in the valve closing direction. In this way, waste nitrogen is mixed with low calorie gas so that the calorie value falls within an allowable range. When supplying waste nitrogen and supplying N ₂ which will be described later, the calorimeter 11 of the mixed gas supply pipe 9 is monitored together with the monitoring of the calorimeter 7 and the flow meter 8 in order to determine the appropriateness of the final caloric value. To do. When supplying waste nitrogen, the oxygen concentration of the supply waste nitrogen is monitored by the oxygen concentration meter 23 of the waste nitrogen supply pipe 4 as described later, or the waste nitrogen is mixed by the oxygen concentration meter 12 of the low calorie gas supply pipe 3. After that, the oxygen concentration of the fuel gas is monitored.

  Next, the point that the waste nitrogen can be released to the atmosphere from the waste nitrogen supply pipe 4 through the waste nitrogen discharge pipe 31 will be described. The supply amount of waste nitrogen is normally controlled by the flow control valve 28. When the detected value of the calorimeter 7 of the low calorie gas supply pipe 3 is suddenly decreased (the caloric value of the low caloric gas is suddenly lowered), the response by the control by the flow control valve 28 may become a problem. In such a case, the flow control valve 32 of the waste nitrogen discharge pipe 31 is opened to dissipate a part of the waste nitrogen to the atmosphere, thereby rapidly reducing the supply amount of the waste nitrogen to cope with the sudden decrease in the caloric value. To do.

FIG. 2 shows a different form of the low calorie gas supply facility. This low calorie gas supply facility 33 is obtained by adding an inert gas supply facility to the low calorie gas supply facility 1 of FIG. Since other configurations are the same as those of the low calorie gas supply facility 1 in FIG. 1, the same components are denoted by the same reference numerals and detailed description thereof is omitted. The inert gas supply facility of FIG. 2 includes an inert gas supply pipe 34 for supplying a high-purity inert gas to the low calorie gas supply pipe 3. This is because when the oxygen production plant (nitrogen production plant) 20 which is a supply source of the waste nitrogen described above is stopped for some reason or the generation amount of the waste nitrogen is greatly reduced, the dilution gas is stably supplied. It was set up for this purpose. In the present embodiment, nitrogen gas (N ₂ ) is used as an inert gas, so this inert gas supply pipe is referred to as an N ₂ supply pipe 34. The inert gas is not limited to N ₂ and may be CO ₂ or helium (He).

In this embodiment, the N ₂ supply pipe 34 is connected to the waste nitrogen supply pipe 4, and the common pipe 38 of waste nitrogen and N ₂ is connected up to the low calorie gas supply pipe 3. The common pipe 38 is connected to the low calorie gas supply pipe 3 by the mixer 5. When it is considered that this inert gas and waste nitrogen are mixed and supplied to the low calorie gas supply pipe 3, both gases are mixed in the connection portion between the N ₂ supply pipe 34 and the waste nitrogen supply pipe 4. You may install the mixer.
The waste nitrogen supply pipe 4 and the N ₂ supply pipe 34 may be directly connected to the mixer 5 without merging, but in order to reduce the equipment cost, as shown in FIG. Are preferably connected in advance. The N ₂ supply pipe 34 has a stop valve 35, a flow meter 36 and a flow control valve 37 in order from the upstream side. The common pipe 38 is provided with a stop valve 29 and a check valve 30 in order from the upstream side, similarly to the waste nitrogen supply pipe 4 of the low calorie gas supply facility 1 of FIG.

When the controller 100 determines from the measurement result of the calorimeter 11 of the mixed gas supply pipe 9 that the calorie value cannot be maintained within the allowable range even by the supply of waste nitrogen, the controller 100 monitors the flow meter 36 of the N ₂ supply pipe 34. By adjusting the flow control valve 37 so as to open, the N ₂ is mixed with the low calorie gas and the calorie value is controlled to be within the allowable range.

  Since the waste nitrogen generated in oxygen production plants and nitrogen production plants contains about 2 to 5% oxygen, if the waste nitrogen is mixed with low calorie gas, the oxygen content (oxygen concentration) of this mixed gas is small. But it rises. When a predetermined ratio of oxygen is contained in the combustible gas, the combustible gas theoretically enters the combustible range at a predetermined temperature. In order to study the case where waste nitrogen containing about 2 to 5% oxygen is mixed with low calorie gas, it may be based on the allowable maximum mixing ratio of air containing relatively high oxygen to low calorie gas.

  That is, since air contains oxygen in a certain volume ratio (which is unchanged at about 21%), the flammability limit of the mixture of air and low calorie gas is determined for the volume ratio of low calorie gas or air, and the allowable air capacity is determined from this. It is convenient to set a maximum mixing ratio and calculate and set the maximum allowable mixing ratio of waste nitrogen based on this data and the ratio of oxygen content. For example, the allowable maximum mixing ratio of air is multiplied by the ratio between the oxygen content of air (21%) and the oxygen content of waste nitrogen employed (about 2 to 5%). This will be described below.

  For reference, FIG. 3 shows the combustible range of a mixed gas of low calorie gas and air in relation to the volume ratio of low calorie gas and the temperature. A curve connected with black circles on the left side of the figure shows the minimum volume ratio of low calorie gas (maximum volume ratio of air) in the combustible range of the mixed gas. The curve connected with the black square mark on the right side shows the maximum volume ratio of low calorie gas (minimum volume ratio of air) in the combustible range of the mixed gas. The range between the two curves is the combustible range. Since the caloric value of low calorie gas fluctuates, both the above curves also fluctuate. Therefore, based on such data, if air is considered as a dilution gas, for example, the maximum allowable mixing volume ratio of air is 20% in volume ratio considering the safety factor (80% volume ratio of low calorie gas). ) This is a ratio (20%) that is even smaller than the minimum volume ratio of air indicated by the curve connecting the black square marks on the right side. However, this numerical value is an example.

  Here, the ratio of the oxygen content of air and waste nitrogen is 21/5. The oxygen content of waste nitrogen is about 2 to 5%, but the safety side is 5%. Since the maximum allowable mixing volume ratio of air is 20%, the maximum allowable mixing volume ratio of waste nitrogen is 20% × 21 / 5≈84%. The maximum allowable mixing volume ratio of these waste nitrogen is set in the controller 100, and these are the maximum allowable mixing volume ratio derived from the flammability limit of the mixed gas. In practice, waste nitrogen is not mixed into low calorie gas until 84%.

  The above control is performed based on the detection results of the flow meter 8 of the low calorie gas supply pipe 3 and the flow meter 27 of the waste nitrogen supply pipe 4. Further, both the oxygen concentration of the mixed gas and the oxygen concentration of waste nitrogen are constantly monitored by the oxygen concentration meter 23 (or 12). This is to cope with unexpected fluctuations in oxygen concentration.

Next, the function and effect of the buffer tank 10 shown in FIG. 1 or 2 will be described. As described above, all of the low caloric gas sent flows into the buffer tank 10. The buffer tank has a large volume. For example, a low-calorie gas supply pipe 3 having a diameter of about 2 to 3 m is generally installed with a volume of about 20000 to 200000 m ³ . The low caloric gas sent while the calorie fluctuates every moment is mixed in the buffer tank. The mixing of gas in the tank in this specification means mixing of time difference. That is, the low calorie gas that has flowed into the buffer tank 10 at the same time is distributed from a portion that flows out of the outlet 10b relatively early to a portion that stays in the buffer tank 10 from late. On the other hand, since new gas continuously flows in from the inlet 10a, the gas that has flowed in the past and the gas that has flown in the past are constantly mixed. This is called time difference mixing.

  As a result of this time difference mixing, the fluctuation range of the calorie of the low calorie gas exiting from the outlet 10b of the buffer tank 10 is reduced, and the fluctuation speed is reduced. That is, calorie fluctuation is greatly reduced (suppressed). Thus, if the calorie fluctuation | variation is eased in advance, the suppression control of the calorie rise by dilution of waste nitrogen etc. will become very easy downstream. The above phenomenon will be described with reference to FIGS.

FIG. 4 shows a simulation of the relaxation (suppression) state of calorie fluctuation when low-calorie gas that fluctuates in calories is supplied at a flow rate of 500,000 Nm ³ / hr when the volume of the buffer tank 10 in FIG. 1 or 2 is 200000 m ^3. It is a graph which shows a result. The horizontal axis represents time (minutes), and the vertical axis represents the gas calorie value (kcal / Nm ³ ), which is the calorific value of low calorie gas. Moreover, the curve shown with a broken line in the figure has shown the calorie fluctuation | variation (original fluctuation | variation) of the low calorie gas sent to the buffer tank 10. FIG. This is an actually measured sample. A curve represented by a solid line indicates a calorie fluctuation (a fluctuation after suppression) of the low calorie gas exiting from the buffer tank 10. As shown, the calorie of the low caloric gas before entering the buffer tank 10 varies from about 1530 kcal / Nm ³ to about 2360 kcal / Nm ³ . That is, it has a fluctuation range of about ± 21% of the average value (1945 kcal / Nm ³ ). According to the result of theoretical calculation of the calorie fluctuation of the low calorie gas exiting from the buffer tank 10, it is 1780 kcal / Nm ³ to 1960 kcal / Nm ³ and the fluctuation range is about ± 5% of the average value (1870 kcal / Nm ³ ). It is suppressed until. As shown in the figure, the short-cycle component and the medium-cycle component are greatly suppressed for the fluctuation cycle. This effect tends to become more prominent as the volume of the buffer tank increases with respect to the low calorie gas supply flow rate. If the fluctuation range of the original fluctuation is small, it is effective to reduce the volume of the buffer tank from the viewpoint of economy.

FIG. 5 shows an attenuation state of calorie fluctuation when the flow rate of the low calorie gas is set to 500,000 Nm ³ / hr and the volume of the buffer tank 10 is set to 100000 m ³ which is half of the above. Calorie variance in this case also is suppressed in a range from 1700kcal / Nm ³ to 2040kcal / Nm ³ by the buffer tank 10, the variation width of about ± 9% of the average value (1970kcal / Nm ^3).

FIG. 6 shows an attenuation state of calorie fluctuation when the volume of the buffer tank 10 is set to 50000 m ³ in the facility in which low calorie gas is supplied at a flow rate of 200000 Nm ³ / hr. Calorie variance in this case also is suppressed in a range from 1740kcal / Nm ³ to 2010kcal / Nm ³ by the buffer tank 10, the variation width of about ± 7.2% of the average value (1875kcal / Nm ^3).

Although not shown, when the volume of the buffer tank 10 is set to 25000 m ³ which is half of the above in the facility where low calorie gas is supplied at a flow rate of 200000 Nm ³ / hr as described above, the fluctuation range is an average value (1875 kcal / Nm ³ ) Of about ± 12%.

As shown in FIG. 7, in a facility where low calorie gas is supplied at a flow rate of 200000 Nm ³ / hr, two buffer tanks 10 with a volume of 25000 m ³ are installed in parallel, and both are used during normal operation. It can be devised that only one of the tanks is used only for an unsteady situation such as inspection or malfunction.

  In this way, the calorie fluctuation of the low calorie gas is greatly suppressed without providing active control only by providing the buffer tank. As a result, control of mixing waste nitrogen and inert gas downstream is very easy. For example, when the calorie fluctuation range of the fuel gas of the gas turbine 2 is set to be ± 10% of the reference calorie value (average value), the average value of the calorie that fluctuates downstream of the buffer tank is expressed as the gas turbine 2. In order to match with the reference calorie value set to, it is only necessary to provide a buffer tank having a volume that can meet the specifications and to supply a certain ratio of waste nitrogen downstream. Regarding the supply operation of waste nitrogen, it is not necessary to consider the state of calorie fluctuation of low calorie gas.

  In an extreme case, if the average calorific value of the low caloric gas after passing through the buffer tank 10 is substantially equal to the reference caloric value set in the gas turbine 2, waste nitrogen supply equipment or inert gas supply Equipment is no longer needed. Even when both facilities are provided, the facilities may be operated with the stop valve 29 of the waste nitrogen supply pipe 4 in FIG. 1 and the stop valve 29 of the common pipe 38 in FIG. 2 closed. Of course, when the caloric fluctuation of the generated low caloric gas is not large, it is not necessary to install a buffer tank, and it can be sufficiently handled only by the waste nitrogen supply facility and the inert gas supply facility.

  FIG. 8 shows another buffer tank 42. This buffer tank 42 may be used in conventional gas turbine equipment, and is included in the device 40 for monitoring the gas amount balance. This gas amount balance monitoring device 40 is for balancing the amount of low calorie gas sent from the upstream side with the amount of gas consumed required by the gas turbine. When there are fluctuations in the supply gas amount and load changes in the gas turbine, it is necessary to balance the supply amount and the consumption amount. When the supply amount is unexpectedly excessive, it is diffused into the atmosphere. When the supply amount is insufficient, the load of the gas turbine is reduced or some operations are stopped.

  This gas amount balance monitoring device 40 has a tank 42 whose outlet 42b is connected to the low calorie gas supply pipe 3 by a communication pipe 41, an upper end opening of the tank 42 is hermetically closed, and the inside of the tank can be moved up and down. And the adjustment weight 44 installed on the lid member 43, for example. The lid member 43 moves up and down in the tank by a balance of the total of its own weight, the weight of the weight 44 and the push-down force due to the atmospheric pressure, and the push-up force caused by the internal pressure of the tank 42. Therefore, the lid member 43 moves up and down according to a change in the balance between the supply amount and consumption amount of the low calorie gas. While monitoring the vertical movement of the lid member 43, measures such as atmospheric gas diffusion and turbine load reduction are taken.

  The buffer tank of FIG. 8 uses this gas amount balance monitoring device 40 for suppressing calorie fluctuation. In addition to the communication pipe 41, the tank 42 is newly connected with the communication pipe 41 in the low calorie gas supply pipe 3 and an upstream inlet pipe 45 that connects the upstream side of the connection position and the tank inlet 42a. Yes. The upstream inlet pipe 45 is provided with a fan 39 for sending low calorie gas into the tank 42. Since the upstream side inlet pipe 45 is connected to the upstream side of the low calorie gas supply pipe 3 with respect to the communication pipe 41, the fan 39 can be omitted by piping design taking pressure loss into consideration. The same applies to the upstream side inlet pipe 45 shown in FIGS. Part of the low caloric gas supplied flows into the tank 42 through the upstream inlet pipe 45, the low calorific gas is mixed in the tank 42, and the same amount of gas passes through the communication pipe 41 from the tank 42. Return to the supply pipe 3. In this case, the communication pipe 41 can also be called an outlet pipe. The buffer tank 42 is connected to an upstream side inlet pipe 45 and a communication pipe 41 that constitute a bypass pipe of the low calorie gas supply pipe 3, so to speak, is installed in parallel to the low calorie gas supply pipe 3.

  Also in the buffer tank 42, the low calorie gas sent through the upstream side inlet pipe 45 is mixed in the buffer tank as in the buffer tank 10 described above. As a result, the fluctuation range of the calorie of the low calorie gas exiting from the outlet 42b of the buffer tank 42 is reduced, and the fluctuation speed is reduced. That is, calorie fluctuation is greatly reduced (suppressed).

  Furthermore, a stirring device 51 such as a fan is installed in the tank 42 to stir the gas. This is to promote gas mixing in the tank, thereby realizing more effective calorie fluctuation suppression. As an installation form of the stirring device 51, it is preferable from the viewpoint of effective mixing of the gas that the gas is allowed to flow from the vicinity of the tank outlet 42b toward the inside of the tank in the vicinity of the outlet 42b. The stirring device 51 is not limited to the tank 42 shown in FIG. 8, and can be installed in the tanks 10, 42, and 47 shown in other drawings and other tanks that can exert a calorie suppressing effect. . In addition, it is preferable to install the electric motor 51a etc. as a rotational drive machine of the stirring apparatus 51 outside the tank.

  FIG. 9 shows another gas amount balance monitoring device 46 that can be used as calorie fluctuation suppressing means. The gas amount balance monitoring device 46 has a more economical configuration and includes an airtight tank 47 communicated with the low calorie gas supply pipe 3 by a communication pipe 41. A pressure detector 48 is installed in the tank 47, and the internal pressure of the tank 47 is constantly monitored. When the detected pressure reaches the upper limit range, the control device 100 issues a command to increase the gas consumption in the facility, and balances the gas supply and demand. The other structure is the same as that of the above-described apparatus 40 (FIG. 8). An upstream inlet pipe 45 is connected to the inlet 47a of the tank 47, and an outlet pipe 47b is connected to the outlet 47b. This tank 47 can also be sufficiently used as a calorie fluctuation suppressing means.

10, in a facility where the low calorie gas varying calorific is supplied at a flow rate 500,000 nm ³ / hr, and 200000M ³ the volume of the tank 42 (47) shown in FIG. 8 or FIG. 9, by the fan 39 of 500,000 nm ³ / hr The state of mitigation of calorie fluctuation when 200,000 Nm ³ / hr of the flow rate is sent to the tank 42 (47) is shown. The curve shown with a broken line in the figure shows the calorie fluctuation (original fluctuation) of the low calorie gas sent directly from the reduced iron facility S. This is the actual measurement sample described above. A curve represented by a two-dot chain line indicates a simulation result of calorie fluctuation (transient fluctuation) of the low caloric gas that leaves the tank 42 and passes through the communication pipe 41. The curve shown by the solid line shows the calorie fluctuation (the fluctuation after suppression) of the gas that reaches the mixer 5 through the low calorie gas supply pipe 3 part downstream from the communication pipe 41. As before, the calorie of the low calorie gas before entering the tank 42 (47) has a fluctuation range of about ± 21% of the average value (1945 kcal / Nm ³ ). However, the calorie fluctuation of the gas after joining from the tank 42 (47) through the communication pipe 41 to the low calorie gas supply pipe 3 is from 1690 kcal / Nm ³ to 2100 kcal / Nm ³ , and the fluctuation range is an average value (1895 kcal). / Nm ³ ) of about ± 11%. This number is an example.

  In this way, it is also possible to suppress fluctuations in gas calorie using existing equipment having the tank 42 (47). Further, the low calorie gas can be easily diluted with waste nitrogen downstream. In FIG. 8 and FIG. 9, the upstream inlet pipe 45 for feeding the low calorie gas into the tank 42 (47) is connected to the upstream side of the outlet pipe 41 in the low calorie gas supply pipe 3, but it is not particularly limited to this configuration. Alternatively, the outlet pipe 41 may be connected downstream (see FIG. 14). A plurality of both the tubes 41 and 45 may be provided.

  The buffer tank 42 shown in FIG. 11 is the same buffer tank 42 for the gas amount balance monitoring device 40 as shown in FIG. The difference is the mode of piping connecting the low calorie gas supply piping 3. The piping mode of FIG. 11 removes the portion from the connecting portion with the upstream inlet piping 45 to the connecting portion with the communication pipe 41 in the low calorie gas supply piping 3 of FIG. 39 is removed. That is, the low-calorie gas supply pipe 3 on the upstream side is connected to the inlet 42a, and the low-calorie gas supply pipe 3 on the downstream side is connected to the outlet 42b. In other words, the buffer tank 10 shown in FIGS. 1 and 2 is replaced with the tank 42 for the gas amount balance monitoring device 40. Such a pipe is a mode that can be easily modified when the existing gas amount balance monitoring device 40 is also used as a gas calorie fluctuation suppressing device.

  FIG. 12 shows another calorie fluctuation suppressing means. This means is a return pipe 49 disposed in the low calorie gas supply pipe 3 for returning a part of the low calorie gas to the upstream side of the low calorie gas supply pipe 3. The return pipe 49 is provided with a fan 39 for pumping low calorie gas upstream. The illustrated return pipe 49 is configured to return to the original low-calorie gas supply pipe 3 even if branched from a single suction section into a plurality of branch pipes 49a, but may also be configured from a single return pipe. Good. In addition, one return pipe may be provided in each of a plurality of different parts of the low calorie gas supply pipe 3.

  Also by such means, the low calorie gas is mixed with the newly supplied low calorie gas when returned to the upstream side of the low calorie gas supply pipe 3, and the calorie fluctuation is alleviated. In order to increase this effect, the return pipe 49 may be lengthened and the volume ratio of the return gas amount to the supply gas amount may be increased.

  FIG. 13 also shows a buffer tank 42 installed in parallel to the low calorie gas supply pipe 3 as in the tank of FIG. As shown in the figure, between the tank 42 and the low calorie gas supply pipe 3, an upstream side inlet pipe 45 having a fan 39 and the communication pipe 41 as an outlet pipe are connected. That is, the upstream side inlet pipe 45 is connected to the inlet 42a of the tank 42, and the outlet pipe 41 is connected to the outlet 42b. However, a further inlet 50 a is formed in the tank 42, and a downstream inlet pipe 50 connected to the downstream side of the connection portion with the outlet pipe 41 in the low calorie gas supply pipe 3 is connected to the inlet 50 a. The downstream inlet pipe 50 is provided with a fan 39 for sending low calorie gas into the tank 42. As shown in the figure, the connection positions (inlet 42a, 50a) of the upstream side inlet pipe 45 and the downstream side inlet pipe 50 to the tank 42 are close to each other.

  According to this configuration, a part of the low calorie gas is pumped into the tank 42 from the upstream side of the low calorie gas supply pipe 3 through the upstream side inlet pipe 45, and at the same time, from the downstream side of the low calorie gas supply pipe 3 through the downstream side inlet pipe 50. A part of the low calorie gas is pumped, mixed and flows out from the outlet 42b to the communication pipe. That is, since a part of the low calorie gas in which the calorie fluctuation is suppressed circulates, mixing for a long time is realized in the tank. The longer the length of the downstream inlet pipe 50, the longer the residence time of the gas to be mixed, and the more preferable mixing is realized. The downstream inlet pipe 50 is connected from the downstream side of the low calorie gas supply pipe 3 to the inlet 50a of the tank 42. From the downstream side, the upstream side of the connecting part with the upstream inlet pipe 45 of the low calorie gas supply pipe 3 is connected. You may connect to.

  FIG. 14 also shows a buffer tank 42 installed in parallel to the low calorie gas supply pipe 3. As illustrated, between the tank 42 and the low calorie gas supply pipe 3, the communication pipe 41 as the outlet pipe and the downstream side inlet pipe 50 are connected. The downstream inlet pipe 50 is provided with a fan 39 for sending low calorie gas into the tank 42.

  According to such a configuration, even if the downstream inlet pipe 50 is connected to the downstream side from the connection portion with the communication pipe 41 in the low calorie gas supply pipe 3, the low calorie gas passes through the downstream inlet pipe 50 from the fan 39 into the tank 42. Is mixed and flows out from the outlet 42b to the communication pipe. That is, since a part of the low calorie gas in which the calorie fluctuation is suppressed circulates, effective mixing is performed. As the length of the downstream side inlet pipe 50 is increased, mixing for a longer time is realized in the tank.

  The tank 42 shown in FIG. 15 has two types of inlets 42a and 52a. The upstream low calorie gas supply pipe 3 is connected to one inlet 42a, the downstream low calorie gas supply pipe 3 is connected to the outlet 42b, and the downstream low calorie gas supply pipe 3 is connected to the other inlet 52a. A return pipe 52 is connected. The two inlets 42a and 52a are formed close to each other. The return pipe 52 is provided with a fan 39 for sending low calorie gas into the tank.

  According to such a configuration, a part of the low calorie gas whose calorie fluctuation is suppressed in the tank 42 is returned to the tank 42 and mixed again, so that more preferable mixing is realized. The longer the length of the return pipe 52, the longer the residence time of the mixed gas. The return pipe 52 is connected to the inlet 52a of the tank 42 from the downstream side of the low calorie gas supply pipe 3, but may be connected to the upstream side of the tank in the low calorie gas supply pipe 3 from the downstream side.

In the embodiment described above, the by-product gas generated by the direct reduction iron manufacturing method is exemplified as the low calorie gas to be used. However, the present invention is not limited to this. Low calorie gas includes blast furnace gas (BFG), converter gas (LDG), coal bed gas contained in the coal bed (Coal mines gas, expressed as CMG), by-product gas generated by smelting reduction iron making process, GTL (Gas-to-Liquid) Tail gas generated in the process, by-product gas generated from the oil sand during the oil refining process, gas generated by incineration of dust using plasma, general waste containing garbage Methane gas (Landfill gas) generated in the process of fermentation and decomposition in the landfill, and low calorie gas such as by-product gas generated by chemically reacting other similar raw materials. Of course, the gas includes not only the gas alone but also a gas whose calorific value is about 12 MJ / Nm ³ or less as a result of mixing a plurality of different gases such as a mixed gas of BFG and LDG.

  According to the present invention, low-calorie gas whose calorie changes from moment to moment is diluted with low-concentration waste nitrogen, which is easy to collect, and suppresses an abnormal increase in combustion temperature, thereby continuing stable combustion. Can be made. That is, the above-described effect can be obtained by low equipment cost and operation cost. Furthermore, nitrogen gas generated in an oxygen production plant or the like that has been disposed of in the past can be effectively utilized.

Claims (16)

A fuel gas supply passage for supplying gas to the gas turbine as fuel;
A waste nitrogen supply passage connected to the fuel gas supply passage for supplying waste nitrogen generated in at least one of an oxygen production plant and a nitrogen production plant to the fuel gas supply passage;
A mixer for mixing the gas and the waste nitrogen;
A calorific value detection device for detecting a calorific value in the gas disposed in the fuel gas supply passage;
An oxygen concentration detection device for detecting the oxygen concentration in the gas, disposed in either one or both of the fuel gas supply passage and the waste nitrogen supply passage;
A fuel gas supply facility comprising: a control device capable of controlling a waste nitrogen supply operation by a waste nitrogen supply passage based on a detection result of the calorific value detection device and the oxygen concentration detection device . When the above control device sets the maximum allowable calorie value of the gas supplied as fuel to the gas turbine, and the caloric value of the fuel gas exceeds the maximum allowable calorie set value, it is discarded from the waste nitrogen supply passage. 2. The fuel gas supply facility according to claim 1 , wherein the fuel gas supply facility is configured to supply nitrogen. An inert gas supply passage for supplying an inert gas is connected to the fuel gas supply passage,
In the state where the control device supplies waste nitrogen to the fuel gas supply passage through the waste nitrogen supply passage, the control device controls the inert gas supply operation by the inert gas supply passage based on the detection result of the calorific value detection device. It constructed comprising claim 1 fuel gas supply system according to. 2. The fuel gas supply facility according to claim 1, further comprising a storage tank that temporarily stores waste nitrogen supplied from at least one of an oxygen production plant and a nitrogen production plant that communicates with the waste nitrogen supply passage. An oxygen concentration fluctuation suppression tank that temporarily stores waste nitrogen supplied from at least one of an oxygen production plant and a nitrogen production plant is disposed in the waste nitrogen supply passage,
2. The oxygen concentration fluctuation suppressing tank has an inlet and an outlet, the upstream side of the waste nitrogen supply passage is connected to the inlet, and the downstream side of the waste nitrogen supply passage is connected to the outlet. Fuel gas supply equipment. A tank for temporarily storing fuel gas is disposed in the fuel gas supply passage,
2. The fuel gas supply according to claim 1, wherein the tank has an inlet and an outlet, the upstream side of the fuel gas supply passage is connected to the inlet, and the downstream side of the fuel gas supply passage is connected to the outlet. Facility. Two types of gas inlets are formed in the tank,
The upstream side of the fuel gas supply passage is connected to one of the gas inlets,
A return passage is connected between the other gas inlet and the downstream side of the fuel gas supply passage,
7. The fuel gas supply equipment according to claim 6, wherein a gas pumping device for pumping the fuel gas toward the tank is installed in the return passage. A return passage is connected between the fuel gas supply passage upstream of the tank and the fuel gas supply passage downstream of the tank,
7. The fuel gas supply facility according to claim 6, wherein a gas pumping device for pumping the fuel gas toward the fuel gas supply passage upstream of the tank is installed in the return passage. A tank for temporarily storing fuel gas is disposed in the fuel gas supply passage,
Between the fuel gas supply passage and the tank, the upstream side from which the fuel gas is fed into the tank from the upstream side of the connection point between the outlet passage for returning the fuel gas from the tank to the fuel gas supply passage and the outlet passage in the fuel gas supply passage The fuel gas supply facility according to claim 1, further comprising an inlet passage. A tank for temporarily storing fuel gas is disposed in the fuel gas supply passage,
Between the fuel gas supply passage and the tank, an outlet passage for returning the fuel gas from the tank to the fuel gas supply passage, and a downstream side for sending the fuel gas to the tank from the downstream side of the connection point of the outlet passage in the fuel gas supply passage And an entrance passage.
The fuel gas supply equipment according to claim 1 or 9, wherein a gas pumping device for pumping fuel gas toward the tank is disposed in the downstream inlet passage. A return passage is connected between the downstream side from the connection point with the outlet passage in the fuel gas supply passage and the upstream side from the connection point with the inlet passage in the fuel gas supply passage,
The fuel gas supply facility according to claim 9, wherein a gas pumping device for pumping fuel gas toward the upstream fuel gas supply passage is installed in the return passage. The fuel gas supply equipment according to claim 6 or 9, wherein a stirring device for stirring gas is installed in the tank. A return passage connected between the upstream portion and the downstream portion of the fuel gas supply passage,
2. The fuel gas supply equipment according to claim 1, wherein a gas pumping device for pumping a part of the fuel gas flowing through the fuel gas supply passage from the downstream portion to the upstream portion of the fuel gas supply passage is disposed in the return passage. . A gas turbine,
A fuel gas supply facility for supplying gas as fuel to the gas turbine,
A gas turbine facility, wherein the fuel gas supply facility is the fuel gas supply facility according to any one of claims 1 to 13 . A calorie measuring step for measuring the calorific value of the gas supplied as fuel to the gas turbine;
An oxygen concentration measurement step for measuring the oxygen concentration of waste nitrogen generated in at least one of the oxygen production plant and the nitrogen production plant;
When the measurement result of the calorific value of the gas exceeds a set allowable caloric value, the waste nitrogen is converted into a fuel gas as a dilution gas based on the measurement result of the calorific value of the gas and the measurement result of the oxygen concentration. A method for suppressing calorie increase in fuel gas for gas turbine fuel, comprising a waste nitrogen mixing step to be mixed. 16. The calorie increase suppressing method according to claim 15 , further comprising a step of mixing an inert gas into the fuel gas when it is determined that the calorific value measurement result does not fall below a set allowable caloric value even when waste nitrogen is supplied.

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