JPS60525B2 - Control equipment for exhaust gas utilization plants - Google Patents

Description

[Detailed description of the invention] The present invention relates to a control device for an exhaust gas utilization plant.

The thermal energy of the exhaust gas from a heat engine prime mover, such as an internal combustion engine or a gas turbine, which generates relatively high temperature exhaust gas during operation, is recovered into a steam turbine, and the steam turbine drives a generator and propeller to power the main engine. There are energy-saving plants that reduce load sharing.

The present invention relates to a steam turbine control device necessary for establishing such an energy-saving plant that utilizes exhaust gas.

A control device for a subordinate exhaust gas utilization plant will be explained with reference to FIG.

A speed governor is generally used to control steam turbines in exhaust gas utilization plants, and a rotation speed detector b
The detection signal obtained by detecting the rotation speed of the steam turbine c is sent to the speed governor a, and is compared with the set rotation speed from the rotation speed setting device d by the comparator n, and the steam is adjusted according to the deviation. The opening degree of a steam control valve f built into the steam inlet line e of the turbine c is adjusted to adjust the amount of steam supplied to the steam turbine c to maintain the rotation speed. However, in such a control mechanism, (i) if the rotational speed of the main engine and the set rotational speed of the steam turbine are different, the steam control valve will be fully open or fully closed, resulting in unstable operation.

That is, generally speaking, the horsepower generated by the main engine g is 5
Since the rotation speed of the steam turbine c during operation is approximately the same as the rotation speed of the main engine g, ``therefore, if the rotation speed of the main engine g decreases, the rotation speed of the steam turbine will also decrease. In an attempt to maintain the rotational speed at the set rotational speed, the steam control valve f is fully opened, and the steam turbine c generates the maximum output that it can produce.However, contrary to the above, the rotational speed of the main engine g increases and the rotational speed of the steam turbine c increases. When the rotation speed also increases, the steam control valve f is closed by the output from the speed governor a in an attempt to lower the rotation speed to the set rotation speed, and even if the steam control valve f is fully closed, the steam control valve f is closed as described above. Since the turbine c is rotated at an increased rotational speed that is approximately the same as the rotational speed of the main engine g, the steam turbine c is idling and cannot effectively utilize the steam from the exhaust gas economizer h, causing it to be unable to perform its power recovery function. In addition to the disadvantages, even during normal operation, the steam turbine c follows minute fluctuations in the rotational speed of the main engine g, so the steam control valve f repeats full opening and closing, and therefore the output of the steam turbine c also reaches its maximum output. The koto output is repeated, and a disturbance occurs in this system, making it inoperable.Also, due to fluctuations in the generated output of steam turbine c, the power to drive generator i is instantaneously transferred between main engine g and steam turbine c. This causes unstable driving.

ii) It is not possible to recover power proportional to the flow rate of steam generated from the exhaust gas economizer.

Now, if the flow rate of steam generated by the exhaust gas seconomizer h increases, the steam turbine inlet pressure will rise, the adiabatic heat drop, which is the energy available to the steam turbine, will increase, and the horsepower generated by the steam turbine will also increase. If the load of the main engine g and the horsepower generated by the main engine g are constant, then the steam turbine c
The rotational speed will increase, but when the rotational speed exceeds the set rotational speed, the steam control valve f' is closed by the output from the speed governor a, so the steam flow rate of the steam turbine c decreases.

Generally, when nozzle shut-off speed control is adopted, the horsepower generated by a steam turbine is expressed by the following formula: L=K×G×day L; generated horsepower G; steam flow rate day...adiabatic heat drop K; proportionality constant; If the adiabatic heat drop increases, the same horsepower can be generated even if the steam flow rate G is decreased, but if the rotation speed exceeds the set rotation speed, even if the steam flow rate generated from the exhaust gas economizer h is large. Regardless, the steam control valve f is closed and the difference between the generated steam flow rate and the amount consumed by the steam turbine, that is, the surplus steam, is dumped to the condenser j, so the entire generated steam flow rate is recovered by the steam turbine c. Therefore, it will not be an energy-saving plant.

On the other hand, when the flow rate of steam generated by the L exhaust gas seconomizer h decreases, the inlet pressure of the steam turbine decreases to Po
The adiabatic heat drop decreases from Ho to P, and the adiabatic heat drop accordingly decreases from Ho to Day. Therefore, the horsepower generated by the steam turbine decreases and the rotational speed decreases, so the output of the speed governor a causes the steam control valve f to decrease. The steam turbine is opened to increase the flow of steam to the steam turbine, increasing horsepower and maintaining the rotation speed of the steam turbine at the set rotation speed, but in this case, the heat recovery rate is poor only on △ days because the adiabatic heat drop is small. Therefore, it will not be an energy-saving plant.

Note that P2 in the figure indicates the turbine outlet pressure. (iiD
When the inlet pressure of the steam turbine fluctuates, the steam/water separation drum will cause carryover, and water droplets will enter the steam pipe, the exhaust gas seconomizer, and the steam turbine, easily damaging the equipment.

That is, rapid evaporation occurs from the gas phase of the steam/water separation drum k, and the gas-liquid mixture flows into the steam pipes 1, m, causing damage to the steam pipes, and further damaging the exhaust gas eco/misa h and the steam turbine c.
``There is dust that could damage these items.

There are various disadvantages such as.

The control device for an exhaust gas utilization plant of the present invention was made to solve the above-mentioned problems, and includes a heat engine prime mover that generates 9E gas and a steam turbine that utilizes the heat of the exhaust gas. In an exhaust gas utilization plant in which one or more driven machines driven by the heat engine prime mover and the steam turbine are provided in the middle of a transmission mechanism that connects the output shaft of the engine prime mover and the output shaft of the steam turbine, A steam control valve is provided in the steam flow path on the steam inlet side of the turbine, and a pressure detector detects the pressure upstream of the steam control valve in the steam flow path, and the signal from the pressure detector is compared with the signal from the pressure setting device. a comparator for detecting the rotation speed of the steam turbine; a rotation speed detector for detecting the rotation speed of the steam turbine; a comparator for comparing the signal from the rotation speed detector with a signal from the rotation speed setting device; Compare the signal from the low signal selector that selects the signal with the smaller output with the signal from the minimum steam flow rate setting device that sets the minimum steam flow rate necessary to prevent the steam turbine from idling. The present invention is characterized by comprising a signal selector for selecting the signal with the larger output and inputting the selected signal to the steam control valve.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

1' is a main engine; 3 is an exhaust gas economizer provided in a flow path through which the exhaust gas discharged from the main engine 1 flows; 9 is a steam turbine driven by the steam generated in the exhaust gas economizer 3; and the output shaft 39 of the steam turbine 9 are connected by a transmission mechanism (generally indicated by reference numeral 40) consisting of a power transmission shaft, a transmission gear, a clutch, etc.
A generator 10 and a propeller device 41 driven by the main engine 1 and the steam turbine 9 are provided in the middle of the transmission mechanism 40.

The propeller device 41 has a propeller 42 and a gear 43 attached to the propeller range 16, and the gear 43 is connected to the transmission mechanism 40.
A transmission gear 45 and a transmission mechanism 40 provided on a power transmission shaft 44 of
It is interposed between a transmission gear 46 provided on the auxiliary power transmission ball 22 and meshes with both transmission gears 45 and 46. The control device for the steam turbine 9, which is driven by the supply of steam generated in the exhaust gas economizer 3, consists of a speed governor control system and a front pressure (steam turbine inlet pressure) control system. Also, speed governing control is performed during startup and shutdown.To explain the above specifically, the rotation speed detection signal of the steam turbine 9 from the rotation speed detector 25 sent to the comparator 29 of the governor 26. is compared with the set number of times from the rotation speed setting device 28, and the steam control valve 2 installed in the steam inlet line 8 of the steam turbine 9 is operated according to the deviation signal.
7 and adjusts the amount of steam supplied to the steam turbine 9 to maintain the rotational speed and perform speed control control. The inlet pressure detection signal of the steam turbine 9 from the facing pressure detector 30 is compared with the set pressure from the pressure setting device 32, and the relationship of the steam control valve 27 is adjusted according to the deviation signal. Prepressure control is performed by maintaining the inlet pressure of the valve 27 at a set pressure. The two control threads are such that only one of the outputs from the two comparators 29 and 31 is selected by the low signal selector 33, so that only one of them can be operated. Number setter 28
If set above the rotation speed of the steam turbine 9 (normally the same as the rotation speed of the main engine 1), the comparator 29 will output a steam control valve full open signal during normal operation, so the low signal selector 33 will Only the selected front pressure control system with a low output level operates. - Therefore, even if the rotational speed of the main engine 1 changes during normal operation (during front pressure control), only the horsepower generated by the steam turbine 9 changes. The opening degree of the steam control valve 27 changes only slightly, and therefore, the unstable movement of the steam control valve, which is conventional, can be eliminated.

Since the main engine 1 compensates for the excess or deficiency of the total load in accordance with the change in the generated horsepower, the steam turbine 9 can recover power through an optimal adiabatic heat drop. Also, during normal operation (during prepressure control), if the flow rate of steam generated from the exhaust gas economizer 3 increases and the inlet pressure of the steam turbine 9 increases, the comparator 31 tries to maintain the set pressure.
As a result, the steam control valve 27 is opened and the flow of steam to the steam turbine 9 is further increased, so that the load on the main engine 1 required to drive the generator 10 or the propeller shaft 16 can be reduced within that range.

On the other hand, when the inlet pressure of the steam turbine 9 decreases due to a decrease in the flow rate of steam generated from the exhaust gas economizer 3, the steam control valve 27 is closed in an attempt to maintain the set pressure, and the horsepower generated by the steam turbine 9 decreases according to the steam flow rate. This shortage is compensated for by the main engine 1, but even in this case, the inlet pressure of the steam turbine 9 is maintained at the set pressure, so the optimum adiabatic heat drop is maintained, and the steam turbine 9 Since power can be effectively recovered in the process, energy savings can be achieved.

If the flow rate of steam generated from the exhaust gas economizer 3 becomes extremely low and the inlet pressure of the steam turbine 9 does not recover to the set pressure even if the steam control valve 27 is fully closed, the steam turbine 9 will be idled by the main engine 1. To prevent this, a high signal selector 34 and a minimum steam flow rate setting device 35 are provided between the low signal selector 33 and the steam control valve 27, so that the generated steam flow rate is extremely high. The structure is such that even if the temperature decreases to 1, the minimum amount of steam for cooling can be supplied to the steam turbine 9.

Therefore, even if the steam turbine inlet pressure drops extremely, the signal from the minimum steam flow rate setting device 35 is selected by the high signal selector 34, so the steam control valve 27 can maintain the minimum opening degree, and the steam The turbine 9 is guaranteed to be supplied with a minimum amount of steam, and overheating due to idle rotation can be prevented. Next, a method of operating a steam turbine in a control device for an exhaust gas utilization plant according to the present invention will be explained.

To start the steam turbine, first the main engine 1 and generator 1
0 clutch 23 is disengaged, the main engine 1 is started and the rotational speed is increased to the normal rotational speed, and then the steam turbine 9 is started and the generator 10 is raised to the normal rotational speed by speed control of the governor 26. Next, the rotation speed of the steam turbine 9 is adjusted to synchronize with the auxiliary power transmission shaft 22 of the main engine 1, the clutch 23 is made of iron, and at the same time, the rotation speed setting device 28 of the steam turbine 9 is set to a rotation speed higher than the normal rotation speed (for example, approximately 5% or more)
to shift from speed regulating control to front pressure control. Then, the governor of the generator 37 driven by the diesel engine 36 was adjusted to perform parallel operation with the main engine 1 and the steam turbine-driven generator 10, and the load A was transferred to the main engine 1 and the steam turbine-driven generator 10'. The generator 37 driven by the rear diesel engine is stopped. When the rotation speed and load A of the main engine 1 decrease, the decrease in the rotation speed of the main engine 1 is detected and the diesel engine-driven generator 37 is automatically started and operated in parallel with the main engine and the steam turbine-driven generator 10. , the load A is transferred to the generator 37 driven by the diesel engine.

Then, the turbine-driven generator 10 becomes unloaded and the steam turbine 9 supplies output to the propeller shaft 16 via the auxiliary power transmission shaft 22 while maintaining the front pressure control. Next, the rotational speed of the main engine 1 is reduced, the clutch 23 is disengaged, and the steam turbine 9 is stopped. Further, when the steam turbine 9 breaks down, the shutoff valve is closed and the clutch 23 is disengaged at the same time.

At this time, the generator 10 is stopped, and the diesel engine-driven generator 37 is automatically driven instead. Although FIG. 3 shows an example in which the front pressure control and speed control of the steam turbine are performed using one set of governor and steam control valve, as shown in FIG. It is also possible to use the valves 27a and 27b so that one performs front pressure control and the other performs speed control control. Fig. 3 shows an example in which a propeller and a generator are used as driven devices for the prime mover (main engine), but it is also possible to use other equipment such as a compressor, refrigerator, pump, etc. It goes without saying that various changes and modifications can be made without departing from the gist of the present invention.

As described above, the control device for the exhaust gas utilization plant of the present invention is capable of controlling the prepressure during normal operation, so even if the rotational speed of the main engine changes during normal operation, the opening degree of the steam control valve will be small. Therefore, it is possible to stably recover power proportional to the steam flow rate from the exhaust gas economizer without changing the amount of exhaust gas, and to maintain the steam turbine inlet pressure at the set pressure in response to changes in the amount of exhaust gas or changes in rotational speed. Because it can be controlled quickly, the steam turbine can always be operated under optimal steam conditions, that is, with the optimal adiabatic heat drop, and highly efficient power recovery can be achieved. Because it can hold steam pipes with carry bar,
Damage to the exhaust gas economizer or steam turbine can be prevented, and during normal operation, the main engine performs speed governing control and the steam turbine does not perform speed governing control but performs front pressure control, so there is no damage between the main engine and the steam turbine. There is no mutual interference regarding rotation speed.
In addition, when prepressure control and speed control are performed using a single set of governor and steam control valve, the structure and operation are simple, and clutch iron disengagement and generator load sharing can be performed using conventional technology, making this an ideal solution. The device is easy to operate and there are no problems with practical application, and since it is equipped with a device that maintains the minimum steam flow rate to the steam turbine, it is possible to prevent overheating due to idling of the steam turbine, thereby preventing damage to the steam turbine, etc. It is possible to achieve various effects such as no

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional control device for an exhaust gas utilization plant, FIG. 2 is an explanatory diagram of the heat recovery rate in a steam turbine, and FIG. 3 is a circuit diagram of a control device for an exhaust gas utilization plant according to the present invention. FIG. 4 is a circuit diagram showing another embodiment. 1 is the main engine, 3 is the exhaust gas economizer, 8 is the steam inlet line, 9 is the steam turbine, 10 is the generator; 25 is the rotation speed detector, 26, 26a, 26b are the governors, 27, 27a
, 27b is a steam control valve, 28 is a rotation speed setting device, 29, 3
1 is a comparison calculator, 3 pressure detectors, 32 is a pressure setting device, 33 is a low signal selector, 34 is a high signal selector, 35 is a steam flow rate setting device, 36 is a diesel engine, and 37 is a generator shows. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. The heat engine prime mover is provided with a heat engine prime mover that generates exhaust gas and a steam turbine that utilizes the heat of the exhaust gas, and that the heat engine prime mover is installed in the middle of a transmission mechanism that connects the output shaft of the heat engine prime mover and the output shaft of the steam turbine. In an exhaust gas utilization plant equipped with one or more driven machines driven by a steam turbine, a steam control valve is provided in a steam flow path on the steam inlet side of the steam turbine, and a steam control valve in the steam flow path is provided. A pressure detector that detects upstream pressure, a comparator that compares the signal from the pressure detector with a signal from the pressure setting device, a rotation speed detector that detects the rotation speed of the steam turbine, and a signal from the rotation speed detector. A comparator that compares the signal from the rotation speed setter with the signal from the speed setting device, a low signal selector that compares the signals output from both comparators and selects the signal with the smaller output, the minimum required to prevent the steam turbine from idling. A high signal selector that compares a signal from a minimum steam flow rate setting device for setting the steam flow rate with a signal from the low signal selector, selects a signal with a larger output, and inputs the selected signal to the steam control valve. A control device for an exhaust gas utilization plant, characterized by: