JPH0233869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a fuel gas supply device for supplying fuel gas to a gas combustion internal combustion engine, that is, a gas turbine and an engine.

"Prior Art" Generally, fuel gas in the gas-burning internal combustion engine is supplied to the internal combustion engine after increasing its pressure by a compressor.

FIG. 5 shows an example of a conventional fuel gas supply system, in which 1 is a compressor, 2 is a gas combustion internal combustion engine, 3 is a load connected to this internal combustion engine 2, 4 is a pressure control device, and 5 is a pressure control device. 6 is a cooler. In this example, compressed fuel gas supplied through pipe f and compressed by compressor 1 is controlled by pressure control device 4, and a predetermined amount of compressed fuel gas is supplied to internal combustion engine 2 via supply pipes a and c. The remaining compressed fuel gas is branched out from the pressure regulating valve 5 to a return pipe b, cooled by a cooler 6, mixed with the supplied fuel gas in a pipe d on the suction side of the compressor 1, and then led to the compressor 1 again. I was starting to feel depressed.

"Problems to be Solved by the Invention" In such a conventional example, the fuel gas discharged from the compressor 1 is heated to a high temperature by the compressor 1, but the pipe line between the compressor 1 and the internal combustion engine 2 The temperature of the fuel gas decreases due to heat radiation, and some of the gas components condense and liquefy, creating mist. This phenomenon is particularly noticeable when the outside temperature is low or when starting up an internal combustion engine, due to cold pipes. When the mist of the present invention is entrained, it clogs the fuel control system of the internal combustion engine, causing various troubles and malfunctioning of various valves for flow rate adjustment, shutdown, etc.

"Means for Solving the Problems" This invention was proposed to solve the above-mentioned conventional drawbacks, and is characterized by the fact that the compressed fuel gas supply pipe is located near the internal combustion engine and on the compressor suction side. a bypass pipe connecting the internal combustion engine, a valve that allows compressed fuel gas to flow from the compressed fuel gas supply pipe to the bypass pipe before starting the internal combustion engine, and a valve that flows from the bypass pipe or the bypass pipe branch on the compressor suction side. A fuel gas supply device for a gas combustion internal combustion engine includes a condensate separation means provided in a pipe line leading to the compressor.

"Function" Before starting the internal combustion engine, the compressed fuel gas compressed by the compressor is circulated from the compressed fuel gas supply line near the internal combustion engine to the compressor suction side via the bypass line. A part of the compressed fuel gas component is condensed and liquefied by heat radiation in the compressed fuel gas supply pipe to form a mist, but the mist is removed by the condensate separation means and the fuel gas is returned to the compressor. The compressed fuel gas supply line is heated by the compressed fuel gas.

When the compressed fuel gas supply pipe becomes warm and mist is no longer generated, the valve is switched, compressed fuel gas is supplied to the internal combustion engine, and the internal combustion engine is started.

This can prevent troubles in the fuel system when starting the internal combustion engine.

"Embodiment" An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 20 is a mist separator;
1 is a positive displacement type, turbo type, axial type, etc. compressor; 22
is a heat exchanger, 23 is an aftercooler, 2
4 is a drain separator, 25 is a filter, 26 is a gas combustion type internal combustion engine such as a gas turbine or gas engine, 27 is a load, and 28 is an auxiliary drain separator for use before starting the internal combustion engine. As shown by arrow A, the fuel gas supplied from the gas inlet 29 is piped so as to be sent through the mist separator 20, the compressor 21, the heat exchanger 22, the aftercooler 23, and the drain separator 4. The downstream pipe A of 24 is
A return pipe B returns to the mist separator 20, and a pipe C of the internal combustion engine system that is sent to the internal combustion engine 26 via the heat exchanger 22 and the filter 25 (of these, the upstream pipe C ₁ of the heat exchanger 22 and the downstream pipe C ₂ do)
There is branch piping. Moreover, the bypass pipe D in which the auxiliary drain separator 28 is interposed is
The pipe C ₂ is installed between the upstream side of the filter 25 and the upstream side of the mist separator 20 . At the branch point between this bypass pipe D and the above-mentioned pipe _C2 , fuel gas is connected from pipe _C2 to bypass pipe D.
There is a valve 34 on the downstream side of the branch point of pipe _C2 , and a valve 35 on the bypass pipe D.
is provided. In addition, the drain separator 24
A pressure control device 30 that detects the gas pressure and outputs a control signal in accordance with the pressure is installed in the downstream portion of the pipe A immediately before branching and the mist separator 20.
31 are respectively provided, and the pipe B is provided with a pressure regulating valve 32. This pressure regulating valve 32
is normally controlled by the pressure control device 30 of the pipe A, but is switched by the selection control device 33 when the pressure inside the mist separator 20 (i.e., the suction pressure of the compressor 21) drops abnormally. The mist separator 20 is operated by a control signal from a pressure control device 31 on the mist separator 20 side.

Next, the operation of the above-mentioned fuel gas supply device will be explained.

(1) First, before starting the internal combustion engine 26, close the valve 34 in front of the internal combustion engine 26, and close the auxiliary drain separator 2.
The valve 35 on the 8 side is opened and the compressor 21 is operated.

(2) The temperature of the fuel gas at the gas inlet 29 is normally room temperature and the pressure is 1.0 to 7.0 Kg/cm ² A (absolute pressure).

(3) The mist separator 20 allows the normal mist to
90% removed.

(4) At the suction port of the compressor 21, the pressure is usually about 0.2 to 0.2 to less than the pressure at the gas inlet 29 due to pressure loss in the mist separator 20 and piping system.
1.0Kg/ ^cm2 lower.

(5) On the discharge side of the compressor 21, the discharge pressure is normally
10 to 16 Kg/cm ² A (this is the discharge pressure equal to the required gas pressure of the internal combustion engine 26 plus the pressure loss of the piping system between the compressor 21 and the internal combustion engine),
The discharge temperature is 90-130°C.

Note that the discharge temperature is determined by the following equation.

However, in the case of reversible adiabatic compression (positive displacement compressor) However, in the case of polytropic compression (turbo compressor), Td: Discharge temperature (〓) Ts: Suction temperature (〓) Pd: Discharge pressure (Kg/cm ² A) Ps: Suction pressure (Kg/cm ² A) ) K: Gas constant ratio Cp/Cv Cp: Specific heat at constant pressure Cv: Specific heat at constant volume n: Index in case of polytropic change As is clear from the above equations () and (),
If the discharge pressure Pd of the compressor 21 is lowered, the discharge temperature
Td also decreases. And the discharge pressure of the compressor 21
Pd can be lowered by lowering the set value of the pressure control device 30.

(6) In the heat exchanger 22, the high-temperature compressed fuel gas discharged from the compressor 21 gives thermal energy to the low-temperature compressed fuel gas flowing through the pipe C of the internal combustion engine system to heat it. Note that this heat exchange phenomenon will be described in more detail later.

(7) The high temperature compressed fuel gas that has been slightly cooled in the heat exchanger 22 is cooled again to near room temperature in the aftercooler 23. At this time, some components contained in the compressed fuel gas are condensed and liquefied as the temperature decreases.

(8) The condensate entrained in the cooled compressed fuel gas is separated and removed by the drain separator 4. Note that, depending on the type of the cooler, this condensed liquid is discharged through a drain outlet of the cooler.

(9) Furthermore, from the gas inlet 29 to the drain separator 24
Compressed fuel gas corresponding to the capacity of the compressor 21 flows between the downstream pipe A and the pipe A.

(10) Detecting the pressure by the pressure control device 30,
The opening degree of the pressure regulating valve 32 is adjusted according to the detected pressure, and the pressure of the compressed fuel gas sent to the pipe C of the internal combustion engine system is kept constant, and the pipe C of the internal combustion engine system is distributed to the bypass pipe D. Only the amount of compressed fuel gas that flows flows.

The compressed fuel gas, which was in a saturated or supersaturated state before entering the heat exchanger 22, is heated by the heat exchanger 22 and becomes superheated compressed fuel gas, which flows through the pipe _C2 . While flowing through the pipe C ₂ , the compressed fuel gas warms the pipe C ₂ and a portion of the compressed fuel gas is condensed and liquefied to become mist. The compressed fuel gas accompanied by the mist flows into the bypass pipe from the pipe C ₂ , and after the mist is auxiliary removed by the auxiliary drain separator 28 , the gas inlet 29 upstream of the mist separator 20
Return to Then, the mist is further removed by the mist separator 20 and introduced into the compressor 21 again.

(11) As mentioned above, the compressed fuel gas sent to pipe C of the internal combustion engine system only flows in an amount corresponding to the amount flowing to bypass pipe D, so the remaining amount of compressed fuel gas is sent to pressure regulating valve 32 and return pipe B. and returns to the gas inlet 29.

(12) As mentioned above, when the compressed fuel gas is circulated to the compressor 21 via the compressor 21, the pipe C ₂ , the bypass pipe D and the mist separator 20 and the pipe C ₂ becomes warm, the valve 34 in front of the internal combustion engine 26 is closed. Open,
The valve 35 on the side of the auxiliary drain separator 28 is closed, and the superheated compressed fuel gas is supplied to the internal combustion engine 26. The internal combustion engine 26 is connected to the piping C of the internal combustion engine system.
The fuel gas is branched and sent in the amount required by the load.

Further, since the compressed fuel gas sent to the pipe C of the internal combustion engine system flows only in an amount corresponding to the load 27 of the internal combustion engine 26, the surplus compressed fuel gas returns to the gas inlet 29 via the pressure regulating valve 32 and the return pipe B. .

Note that the fuel gas returning from the return pipe B to the gas inlet 29 must pass through the aftercooler 23. This is because, even if the compressor 21 is a positive displacement type, the compression is not due to a complete reversible adiabatic change, but is actually heated excessively due to the frictional heat of the compressor, so the compressed high temperature Even if the gas is adiabatically expanded by the pressure regulating valve 32, the temperature of the supplied gas will not drop to the original supply gas temperature. This is because the temperature of the gas discharged from the compressor 21 increases, causing mechanical problems.

Further, the pressure control device 31 on the mist separator 20 side outputs a control signal in the same way as the pressure control device 30 in the pipe A downstream of the drain separator 24, and although it is normally ignored by the selection control device 33, When the amount of fuel gas supplied to the gas inlet 29 decreases and the suction pressure of the compressor 21 falls below a certain value, the selection control device 33 switches the pressure regulating valve 32 to the mist separator 20.
It is controlled only by the side pressure control device 31.
In this case, the pressure control device 30 of the pipe A is ignored, and the pressure regulating valve 32 is opened so as to return the compressed fuel gas on the discharge side of the compressor 21 to the suction side and prevent a pressure drop on the suction side of the compressor 21. The following control is performed. This is because if the suction pressure of the compressor 21 decreases, it will have an abnormal effect on the compressor 21 and cause it to malfunction. In other words, this is to prioritize protection of the compressor 21 over supply to the internal combustion engine 26. In this way, when the supply amount at the inlet 29 decreases and the pressure in the pipe C of the internal combustion engine system drops below a certain value, either switch to another fuel system (not shown) (usually liquid fuel) or stop the operation of the internal combustion engine 26. .

Next, the phenomenon of heat exchange in the heat exchanger 22 of this embodiment described in the above section (6) will be described.

Generally, the amount of heat exchanged Q in a heat exchanger is determined by the following equation.

Q = U × A × △tm ... () U: Overall heat transfer coefficient A: Heat transfer area (constant) △tm: Logarithm mean temperature difference △tm: △t ₁ −△t ₂ /loge△t ₁ /△ t ₂ ... () △t ₁ = T ₂ −t ₁ △t ₂ = T ₁ − _{t 2} T ₁ : Temperature of heating fluid at the inlet of the heat exchanger T ₂ : Temperature of the heating fluid at the exit of the heat exchanger t ₁ : Temperature of the heated fluid at the heat exchanger inlet t ₂ : Temperature of the heated fluid at the heat exchanger outlet When the flow rate of the heated fluid (i.e., the flow rate in pipe C of the internal combustion engine system) decreases and the gas flow rate decreases,
The overall heat transfer coefficient U decreases. Also, although the temperature t ₂ at the outlet of the heated fluid increases, the temperature difference between the heated fluid and the heated fluid, that is, T ₁ − t ₂ (=△t ₂ )
becomes smaller, and the numerical value of the numerator in equation () becomes larger, but the numerical value of the denominator becomes larger, so the logarithmic average temperature difference △tm becomes smaller (this means that mathematically, in equation (), (This is immediately derived by calculation). Therefore, as the flow rate G of the fluid to be heated decreases, the amount of heat exchange Q also decreases.

By the way, as the amount of heat transferred in a heat exchanger having a fixed heat transfer area, the temperature rise of the heated fluid is determined by the following equation.

△t = Q/G Since the exchange amount Q also becomes small, the temperature rise Δt of the heated fluid does not become so large.

In other words, even if the load on the internal combustion engine 26 decreases and the amount of gas flowing into the piping C of the internal combustion engine system decreases (the limit is generally about 40% of the flow rate at rated load).
%), the heat exchanger 22 will not overheat. In this way, in this embodiment, by using the fuel gas discharged from the compressor as the heating fluid of the heat exchanger 22, the heat exchanger 22
has a self-adjusting ability to prevent overheating, making it possible to keep the temperature rise of the fuel gas sent to the internal combustion engine 26 within an allowable value.

Furthermore, even if the temperature rise exceeds the allowable value, the pressure of the compressor 21 can be reduced by lowering the discharge pressure within the pressure range required by the internal combustion engine 26 (usually approximately 8 to 14 kg/cm ² G (gauge pressure)). By lowering the discharge temperature, the temperature of the fuel gas sent to the internal combustion engine 26 can be kept within an allowable value. To explain this situation in detail, as is clear from the above-mentioned equations () and (), if the discharge pressure Pd of the compressor 21 is lowered, the discharge temperature Td will also be lowered. Since the discharge pressure Pd of the compressor 21 can be lowered by lowering the setting value of the pressure control device 30, the setting value of the pressure control device 30 can be lowered within the pressure range required by the internal combustion engine 26. By setting, the discharge temperature of the compressor 21 can be lowered, and as a result, the gas temperature in the pipe _C2 of the internal combustion engine system can be lowered.

The set value of the pressure control device 30 may be changed manually. Such a change in the set value is preferably performed when there is a significant difference in the temperature of the fuel gas supplied from the gas inlet 29 between summer and winter. Further, as shown in FIG. 2, a temperature control device 36 is installed in the pipe _C2 of the internal combustion engine system to detect the temperature and output a control signal according to the detected temperature.
By this control signal, the pressure control device 30 of pipe A
The setting value of the pressure control device 30 may be changed automatically by such cascade control.

As described above, superheated compressed fuel gas without mist can be supplied to the internal combustion engine 26 at a temperature within the permissible value.

In the embodiment shown in FIGS. 1 and 2 above, the compressed fuel gas supply line and the bypass line of the present invention are respectively constituted by pipes A and C and bypass pipe D, and the compressed fuel gas supply line and bypass line of the present invention Valves 34 and 35 are configured to allow the flow from the pipeline to the bypass pipeline.

Note that the auxiliary drain separator 28 provided in the bypass pipe D is unnecessary if the mist separator 20 has sufficient capacity.

FIG. 3 shows another specific example.
It supplies fuel to two gas turbines 40 and 40 with a rating of 2500kw. and suction pressure
Two-stage reciprocating compressors 41 and 42 are provided to compress from 1.033 Kg/cm ² A to a discharge pressure of 17.3 Kg/cm ² G, and an intermediate cooler 43 and an intermediate mist separator 44 are provided. The intermediate cooler 43 and the aftercooler 23 are air-cooled when the atmospheric temperature is at a maximum of 45°C. In addition, the capacity of the heat exchanger 22 is equivalent to two gas turbines with a rating of 2500kw, and is approximately
Heat transfer area 14 with exchange heat capacity of 10000kcal/H
A double pipe heat exchanger of m ² is used. In addition, the first
Portions common to those in the figures are designated by the same reference numerals, and description thereof will be omitted. The properties of the fuel gas used shall be as follows.

Component Molar ratio (%) at the inlet of the first stage compressor 41 Methane 15.82 Ethane 13.84 Propane 22.26 Isobutane 6.26 Normal butane 13.99 Normal pentane 5.50 Hexane 4.40 Heptane 3.69 Water vapor 3.14 Hydrogen sulfide 3.95 Nitrogen 0.87 Carbon dioxide 1.34 Total 100% Above fuel gas The results when using gas turbine 4 are as shown in each stage of Fig. 3.
It was possible to supply fuel gas at 65°C to 0.

In the above embodiment, the capacity of the aftercooler 23 can be reduced by the capacity of the heat exchanger 22, which is 10000 kcal/H, compared to the case where a heater 50 using an external heat source is used as shown in FIG. 4, which will be described later. It became.

Further, the amount of fuel gas supplied to the gas turbine 40 side is at its minimum when one gas turbine is in no-load operation, but the fuel gas sent to the gas turbine 40 at this time is heated to the maximum in the heat exchanger 22, and at that time The gas temperature was 77°C. This temperature is within an acceptable range for fuel gas sent to a gas turbine.

This also makes it possible to supply mist-free superheated fuel gas from the beginning of startup, which prevents troubles in the fuel system when starting up the gas turbine, and also helps reduce the timing of overhauling the gas turbine. There was no problem even if the amount of fuel was increased by about 10%, and the frequency of troubles during driving was reduced by about half.

In the above embodiment, an example was shown in which the heat exchanger 22 uses the discharged fuel gas of the compressor 21 as the heating fluid, but instead of this, an external heat source using heating fluid such as steam or electricity as the heat source is used. You can also use it.

FIG. 4 shows an embodiment in which a heater 50 using an external heat source is used as the heating means. Note that parts common to those in FIG. 1 are denoted by the same reference numerals, and explanations thereof will be omitted.

In FIG. 4, the fuel gas supplied from the gas inlet 29 as indicated by arrow A flows into the mist separator 2.
0, the compressor 21, the aftercooler 23, and the drain separator 24, and the pipe A downstream of the drain separator 24 is connected to the return pipe B returning to the mist separator 20.
and a pipe C of the internal combustion engine system that is sent to the internal combustion engine 26 via the heater 50. Also,
A bypass pipe D is provided between the pipe C near the internal combustion engine 26 and the upstream side of the mist separator 20. Furthermore, a pressure control device 30 is provided in the pipe C between the branch point of the pipe A downstream of the drain separator 24 and the heater 50.
A temperature control device 51 is provided in the pipe C between the two.

This temperature control device 51 constantly detects the temperature of the fuel gas sent to the internal combustion engine 26 and controls the flow rate adjustment valve 53 provided in the heating fluid supply pipe 52 such as steam of the heater 50, thereby controlling the temperature of the superheated fuel gas without mist. Gas is supplied to the internal combustion engine 26, but since the pipe C is cold in the initial stage of startup, mist is inevitably generated. Therefore, before starting the internal combustion engine 26, the valve 34 in front of the internal combustion engine 26 is closed, the valve 35 of the bypass pipe D is opened, the compressor 21 is operated, the fuel gas is circulated, and the pipe C is warmed. When piping C warms up and no mist is generated, valve 3
4 is opened, the valve 35 is closed, and the internal combustion engine 26 is opened.
Start up and enter normal operation. The degree of overheating after normal operation varies depending on the length of the pipe C from the heater 50 to the internal combustion engine 26 and the outside temperature, but in general, if the fuel gas is heated to 5 to 20 degrees Celsius above the dew point of the supplied fuel gas. It is enough. The heating of the heater 50 prevents mist from flowing into the internal combustion engine 26, so that the combustion state of the internal combustion engine can be stabilized for a long period of time.

Note that 54 is a return pipe for heating fluid.

In the above embodiment, a case was described in which a means for heating the fuel gas was provided downstream of the compressor.
It goes without saying that the present invention may be applied to the conventional fuel gas supply device without fuel gas heating means shown in FIG.

"Effects of the Invention" As explained above, according to the fuel gas supply device of the present invention, a bypass pipe connecting the vicinity of the internal combustion engine of the compressed fuel gas supply pipe and the compressor suction side and a compressed fuel gas a valve that allows the compressed fuel gas to flow from the compressed fuel gas supply pipe to the bypass pipe, and a condensate separator provided in the bypass pipe or a pipe from the bypass pipe branch on the compressor suction side to the compressor. Because we have provided means, even when starting up,
Even if the compressed fuel gas supply pipe is cold and some of the fuel gas turns into mist, the fuel gas is circulated through the bypass pipe and can warm the compressed fuel gas supply pipe, so it will not flow into the internal combustion engine. There is no mist in the fuel gas, which completely eliminates fuel system troubles when starting an internal combustion engine, and has the remarkable effect of reducing the need to clean fuel nozzles and other parts during periodic inspections, reducing the need to replace parts. .

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention;
Fig. 2 is a system diagram showing another embodiment, Fig. 3 is a system diagram showing yet another embodiment, Fig. 4 is a system diagram showing still another embodiment, and Fig. 5 is a conventional fuel gas supply. FIG. 2 is a system diagram of the device. 20...mist separator (condensate separation means),
21...Compressor, 26...Internal combustion engine, 29...Gas inlet (compressor suction side), 34, 35...Valve (valve), A, C...Piping (compressed fuel gas supply pipe).

Claims (1)

[Claims] 1. In a fuel gas supply device that compresses fuel gas and sends it to an internal combustion engine, a bypass pipe connects the vicinity of the internal combustion engine of the compressed fuel gas supply pipe and the compressor suction side, and a bypass pipe connects the compressed fuel gas to the compressed fuel gas before starting the internal combustion engine. a valve that allows flow from the supply pipeline to the bypass pipeline;
A fuel gas supply device for a gas-burning internal combustion engine, characterized in that a condensate separation means is provided in the bypass pipe or a pipe from the bypass pipe branch on the compressor suction side to the compressor. .