Fuel gas supercharger-gas turbine integration for energy saving and operability optimization

Abstract

Fuel gas supercharger-gas turbine integration is disclosed for energy conservation and operability optimization. The fuel gas supercharger-gas turbine integration comprises an integrated system, and the integrated system comprises a fuel gas supercharger (10) based on a reciprocating compressor and a gas turbine (11). Wherein a flow and pressure control system (15) of the gas turbine and a pressure and capacity control system (20) of the fuel gas supercharger are synchronized to optimize the power consumption of the fuel gas supercharger or the power consumption of the fuel gas supercharger and the gas turbine set, the flow and pressure control system (15) of the gas turbine comprises at least one gas turbine fuel gas input control valve (14); and the control system (20) of the fuel gas supercharger comprises a gas turbine fuel gas input control valve position controller associated with the at least one gas turbine fuel gas input control valve (14) and a fuel gas supercharger capacity control device associated with the reciprocating compressor-based fuel gas supercharger (10).

Description

[0001] manual Technical Field

[0002] The present disclosure relates to thermodynamic systems and methods. The embodiments disclosed herein specifically relate to an integrated system, which includes a fuel gas booster based on a reciprocating compressor and a gas turbine, wherein the pressure and capacity control of the fuel gas booster is integrated with the flow and pressure control of the gas turbine to optimize the operation of the fuel gas booster based on the reciprocating compressor. According to the embodiments disclosed herein, the fuel gas booster based on the reciprocating compressor and the gas turbine system are automatically synchronized at the minimum absorbed power operating point, regardless of the pressure, temperature, and composition changes of the environment and the fuel gas. Background Art

[0003] Gas turbines require fuel gas at a certain pressure to combine it with pressurized air before combustion. Often, the gas pressure available from the pipeline is not sufficient to deliver it at the pressure required by the gas turbine. In fact, the gas pressure in the pipeline cannot be maintained at sufficiently high values, due to the increasingly high values ​​of gas pressure required for efficient gas turbines and the increasing demand for natural gas. This is especially true for gas turbines of the previous generation, which require fuel gas pressure values ​​even exceeding 30 bara, and during peak demand periods such as in summer or during the day, when the gas pressure in the pipeline can gradually decrease and even fluctuate.

[0004] In order to properly handle such fluctuating gas pressures from the pipeline while meeting the gas flow rate required by the gas turbine, a fuel gas compressor should be inserted between the pipeline and the gas turbine. This fuel gas compressor is usually called a fuel gas booster. Two variable conditions are most relevant to the fuel gas booster: suction pressure fluctuations and turbine load changes.

[0005] US6948919B2 discloses a fuel supercharger operable for compressing combustible fuel, the fuel supercharger includes a compressor accommodating a compression rotor and a sealing assembly coupled to a compressor housing. The fuel supercharger also includes a motor having a motor rotor and a motor stator. A variable frequency drive provides power to the motor to control the output pressure and / or flow rate of the compressor. During operation, one or more sensors monitor engine parameters (e.g., fuel pressure, fuel flow rate, power output, turbine outlet temperature, etc.). The speed of the compressor motor is controlled to maintain the engine parameters at a desired value. For example, a system monitors the fuel supercharger discharge pressure (fuel pressure) and changes the speed of the compressor motor to achieve the desired fuel pressure. If the pressure is too high, the speed of the compressor motor is reduced via the variable frequency drive. If the pressure is too low, the compressor motor speed is increased. In another configuration, the engine parameter is the fuel flow rate measured by a fuel flow meter (not shown) positioned downstream of the fuel supercharger. When the flow rate exceeds the desired value, the variable frequency drive reduces the frequency of the power provided to the compressor motor to reduce the speed and flow rate of the compressor motor. If the flow rate is too low, the compressor motor speed is increased by a variable frequency drive to increase the flow rate to a desired value. In yet another configuration, the turbine outlet temperature is measured directly or indirectly, and the compressor motor speed is controlled to maintain the desired turbine outlet temperature. The above system controls the output of the compressor without using a conventional slide valve.

[0006] US4922710A discloses an integrated booster compressor / gas turbine control system in which a fuel gas booster compressor boosts fuel gas pressure before supplying the fuel gas to the gas turbine control valves (i.e., the stop / speed ratio or pressure control valve and the gas control or volume valve), which in turn provides the fuel gas to the gas turbine. According to the present disclosure, by driving these valves to a fully open position under normal operating conditions and using these valves in their normal control mode during other operating conditions (such as startup and sudden load rejection), it is possible to minimize the pressure drop across the gas turbine control valves and thus minimize the boost power requirement. Therefore, after the startup operation, the system control utilizes the booster compressor flow control to transition to the minimum system operating pressure drop in order to control the gas turbine fuel flow and thus control the gas turbine output power.

[0007] The aforementioned system effectively controls the operation of the gas turbine, but has important limitations due to the power consumption of the fuel gas booster, which can be even as high as 10% of the total gas turbine rated power.

[0008] Furthermore, these limitations are also evident in the case of fuel gas boosters based on reciprocating compressors, which are the preferred class of compressors for the typical size range (<500kW) applied to fuel gas boosters. In fact, reciprocating compressors allow operation without lubricants, necessary to avoid oil contamination of the combustion chamber, and have very high compression efficiencies compared to competing rotary technologies (e.g. screw compressors).

[0009] Therefore, improved systems and methods for operating reciprocating compressor based fuel gas boosters and gas turbines to solve the absorption power problems of the prior art would be beneficial and would be welcomed in the art. More generally, it would be desirable to provide suitable methods and systems to more effectively solve the problems caused by the need to increase fuel gas pressure and at the same time bring important energy and operating cost savings. Summary of the invention

[0010] In one aspect, the subject matter disclosed herein relates to a system wherein, when a reciprocating compressor-based fuel gas booster is used, integration between pressure and capacity control of the fuel gas booster and flow and pressure control of the gas turbine allows the operation and power consumption of the fuel gas booster and the gas turbine unit to be optimized or the operation and power consumption of the fuel gas booster to be minimized.

[0011] In another aspect, the subject matter disclosed herein relates to a control concept that automatically synchronizes a reciprocating compressor based fuel gas booster and a gas turbine train at a minimum absorbed power operating point regardless of ambient and fuel gas pressure, temperature, composition variations. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete understanding of the disclosed embodiments of the present invention and many of its attendant advantages will be readily obtained by reference to the following detailed description when considered in conjunction with the accompanying drawings, which likewise become better understood, wherein:

[0013] Figure 1 A schematic diagram of an integrated system including a reciprocating compressor based fuel gas booster and a gas turbine according to one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0014] According to one aspect, the present subject matter is directed to an integrated system including a reciprocating compressor based fuel gas booster and a gas turbine, wherein pressure and capacity control of the fuel gas booster and flow and pressure control of the gas turbine are controlled to optimize the reciprocating compressor based fuel gas booster operation.

[0015] According to one aspect, a fuel gas booster based on a reciprocating compressor is integrally connected to a gas turbine casing, and the booster compressor boosts the pressure and gas fuel. It is used to increase internal energy and generate more power with a smaller gas fuel flow rate.

[0016] According to one aspect, a fuel gas booster control system and a gas turbine control system are integrated to automatically synchronize a reciprocating compressor-based fuel gas booster and a gas turbine train at a minimum absorbed power operating point regardless of ambient and fuel gas pressure, temperature, and composition variations.

[0017] According to certain aspects, in the event that the gas turbine control system sets the gas turbine control valve in a less than fully open position in order to optimize gas turbine operation, the fuel gas booster control system is operated to reduce capacity. As a result of the reduction in fuel gas booster capacity, the fuel gas from the reciprocating compressor-based fuel gas booster has a lower pressure, thereby allowing the gas turbine control system to set the gas turbine control valve in a fully open position, thereby reducing the pressure drop across the gas turbine control valve.

[0018] According to one aspect, the fuel gas booster is a reciprocating compressor-based fuel gas booster comprising a plurality of cylinders, each cylinder comprising at least one cylinder effect, and the capacity of the fuel gas booster is controlled by equipping each cylinder effect with a cylinder valve unloader that allows effective step control (for example, a 4-cylinder compressor with 2 effects per cylinder can be managed by a step adjustment of 12.5% ​​capacity).

[0019] According to one aspect, capacity control of a fuel gas supercharger may be achieved through additional variable lash pockets that can manage capacity changes by increasing and decreasing individual cylinder lash pockets using actuators.

[0020] According to other aspects, other means may be used to manage the opening and closing of the compressor valve in a manner that manages effective capacity control.

[0021] Alternatively, to manage the capacity of a reciprocating compressor based fuel gas booster, the motor driving the compressor may be equipped with a variable speed system.

[0022] Other fuel gas booster pressure and capacity control devices may be used and the technical and commercial effectiveness of different solutions needs to be evaluated based on the specific service of the individual reciprocating compressor based fuel gas booster.

[0023] According to another aspect, the fuel gas booster control system is configured as a slow control system in order to minimize any disturbance to the gas turbine control system. Thus, by driving these valves to a fully open position under normal operating conditions, the pressure drop across the gas turbine control valves and thus the boost power requirement can be minimized, and the gas turbine control valves are still used to regulate gas turbine operation in their normal control mode.

[0024] According to certain aspects, a gas turbine control valve is used to regulate gas turbine operation during startup and sudden load dumping.

[0025] According to another aspect, optimization of reciprocating compressor based fuel gas booster operation can result in significant energy and operating cost savings.

[0026] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by explaining the present disclosure rather than limiting the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the scope or essence of the present disclosure. The reference to "one embodiment" or "embodiment" or "some embodiments" throughout this specification means that the specific features, structures or characteristics described in conjunction with the embodiments are included in at least one embodiment of the disclosed subject matter. Therefore, the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" that appear in multiple places throughout the specification do not necessarily refer to the same embodiment. In addition, in one or more embodiments, specific features, structures or characteristics may be combined in any suitable manner.

[0027] When introducing elements of various embodiments, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0028] Now referring to the accompanying drawings, Figure 1A schematic diagram of an exemplary integrated system is shown, which includes a reciprocating compressor-based fuel gas booster 10 and a gas turbine 11, a fuel gas feed line 12 connecting the inlet of the reciprocating compressor-based fuel gas booster 10 to a fuel gas pipeline (not shown), and a compressed fuel gas line 13 connecting the outlet of the fuel gas booster 10 to the inlet of the gas turbine 11. A gas turbine control valve 14 is arranged on the compressed fuel gas line 13 to regulate the gas turbine inlet fuel gas pressure and flow. The gas turbine control valve 14 is operated by a gas turbine control system 15 through a gas turbine control system output line 16. The input of the gas turbine control system 15 includes a pressure indicator 17, which is arranged on the compressed fuel gas line 13, upstream of the gas turbine control valve 14, and connected to the gas turbine control system 15 through a pressure indicator line 18. The input of the gas turbine control system 15 also includes a gas turbine flow demand line 19.

[0029] There is also a fuel gas booster control system 20, the inputs to which include a gas turbine control valve position indicator line 21. The fuel gas booster control system 20 controls the capacity of the reciprocating compressor based fuel gas booster 10 by means of a specific pressure and capacity control device selected for the specific service, such as a cylinder valve unloader of any cylinder effect of the multiple cylinders of the reciprocating compressor, an additional variable clearance pocket capable of managing capacity changes by increasing and decreasing individual cylinder clearance pockets with an actuator, a reciprocating compressor inlet valve, or a variable frequency drive motor 23, which is connected to the fuel gas booster control system 20 via a fuel gas booster control system output line 22.

[0030] The integrated system of the present invention operates as follows. The fuel gas booster control system 20 continuously detects the position of the gas turbine control valve 14. When the gas turbine control system 15 sets the gas turbine control valve 14 to a less than fully open position in order to optimize gas turbine operation, the fuel gas booster control system 20 reduces the capacity of the fuel gas booster through one of the capacity control devices selected for the particular service. After the capacity of the reciprocating compressor-based fuel gas booster 10 is reduced, the fuel gas from the reciprocating compressor-based fuel gas booster 10 has a lower pressure, thereby allowing the gas turbine control system 15 to set the gas turbine control valve 14 to a fully open position, thereby reducing the pressure drop across the gas turbine control valve 14. Therefore, the power absorbed by the reciprocating compressor-based fuel gas booster 10 is reduced without reducing the operability of the gas turbine.

[0031] In particular, if the pressure and / or flow rate of the fuel gas from the reciprocating compressor-based fuel gas booster 10 is higher than the pressure and flow rate actually required by the gas turbine 11, for example due to high ambient temperature or reduced turbine load, the gas turbine control system 15 operates the gas turbine control valve 14 to a less than fully open position. The partial closure of the gas turbine control valve 14 causes a pressure drop of the fuel gas before the fuel gas from the reciprocating compressor-based fuel gas booster 10 reaches the gas turbine inlet. This means that part of the compression of the fuel gas operated by the reciprocating compressor-based fuel gas booster 10 is lost, and from a different perspective, the compression of the fuel gas operated by the reciprocating compressor-based fuel gas booster 10 is excessive relative to the pressure required by the gas turbine 11. At the same time, the reciprocating compressor-based fuel gas booster 10 absorbs an excess amount of power relative to the requirement. According to the present disclosure, by allowing the reciprocating compressor-based fuel gas booster 10 to compress the fuel gas at the pressure required by the gas turbine and to minimize any possible subsequent pressure drop, the capacity of the reciprocating compressor-based fuel gas booster 10 is reduced, thereby saving such amount of absorbed power. In fact, within certain limits, the reduction in the fuel gas pressure at the inlet of the gas turbine 11 does not negatively affect the operability of the gas turbine 11, especially under reduced load or high temperature conditions. Typically, the fuel gas booster is designed to operate at 30 bara, but can also operate at lower pressures (down to about 26 bara to 27 bara) when the temperature is higher (usually in the summer) or the load is lower.

[0032] Importantly, according to the present disclosure, since the fuel gas booster control system 20 is used as an additional control system relative to the gas turbine control system 15, care must be taken to avoid interference between the systems, which can cause instability. In this regard, the fuel gas booster control system 20 is configured as a slow control system, while the gas turbine control system 15 is a fast control system. More specifically, the regulator of the fuel gas booster control system 20 is a proportional regulator or a proportional integral regulator with a low proportional gain value. Therefore, the gas turbine operation and transient conditions are still controlled by the gas turbine control system 15 without any interference from the fuel gas booster control system 20, while the fuel gas booster control system 20 is only used to adjust the capacity of the reciprocating compressor-based fuel gas booster 10.

[0033] In particular, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to the present disclosure may be used to automatically synchronize a reciprocating compressor based fuel gas booster and gas turbine train at a minimum absorbed power operating point.

[0034] Optionally, integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to the present disclosure may be used to minimize the fuel gas booster absorbed power operating point.

[0035] In particular, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to the present disclosure can be used to reduce the shutdown stabilization pressure of the closed loop in the thermodynamic system after the boosting equipment (such as the compressor) is shut down to facilitate the startup of the system.

[0036] According to the specific implementation of the integration of the fuel gas booster control system 20 and the gas turbine control system 15 disclosed in the present invention, two fuel gas boosters can be used, which are designed to provide a pressure and flow rate lower than the pressure and flow rate required by the gas turbine, even as low as 50% of the pressure and flow rate required by the gas turbine. This configuration ensures increased availability and reliability under specific conditions without negatively affecting the system under normal operating conditions. For example, since the gas turbine can be operated at full load in the summer, the pressure of the fuel gas from the reciprocating compressor-based fuel gas booster is reduced, so only one reciprocating compressor-based fuel gas booster can use a redundant configuration, while the other reciprocating compressor-based fuel gas booster is under maintenance.

[0037] Finally, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to the present disclosure allows for fuel gas booster electrical power savings of up to 30% (depending on the location) and increased reliability and availability of the minimum load of the reciprocating compressor based fuel gas booster operating under every condition and automatically tracking environmental and fuel gas booster conditions.

[0038] Although various aspects of the present invention have been described in terms of various specific embodiments, it will be apparent to those skilled in the art that many modifications, variations, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless otherwise indicated herein, the order or sequence of any process or method steps may be changed or reordered according to alternative embodiments.

Claims

1. An integrated system, the integrated system comprising a reciprocating compressor based fuel gas booster (10) and a gas turbine (11), wherein a flow and pressure control system (15) of the gas turbine and a pressure and capacity control system (20) of the fuel gas booster are synchronized to optimize the power consumption of the fuel gas booster or the power consumption of the fuel gas booster and gas turbine unit, and wherein the flow and pressure control system (15) of the gas turbine comprises at least one gas turbine fuel gas input control valve (14), and the pressure and capacity control system (20) of the fuel gas booster comprises a gas turbine fuel gas input control valve position controller associated with the at least one gas turbine fuel gas input control valve (14) and a fuel gas booster capacity control device associated with the reciprocating compressor based fuel gas booster (10).

2. The system of claim 1, wherein the fuel gas booster capacity control device is selected from a cylinder valve unloader associated with each cylinder effect of the reciprocating compressor based fuel gas booster (10), an additional variable clearance pocket for each individual cylinder clearance pocket, a reciprocating compressor inlet valve or a variable frequency drive motor (23).

3. The system according to claim 1 or 2, wherein the pressure and volume control system (20) of the fuel gas booster is a slow control system.

4. The system of claim 3, wherein the fuel gas booster pressure and volume control system (20) is a proportional control system.

5. The system of claim 3, wherein the fuel gas booster pressure and volume control system (20) is a proportional-integral control system.

6. The system according to claim 1, wherein the flow and pressure control system (15) of the gas turbine is a fast control system.

7. The system of claim 1, wherein the reciprocating compressor based fuel gas booster (10) is integrally connected to a gas turbine casing.

8. The system of claim 1 comprising two reciprocating compressor based fuel gas boosters.

9. The system of claim 8, wherein each reciprocating compressor based fuel gas booster is designed to provide at least the pressure and capacity required by the gas turbine.

10. The system of claim 8, wherein each reciprocating compressor-based fuel gas booster is designed to provide a pressure and capacity lower than the pressure and capacity required by the gas turbine, and the total pressure and capacity of the reciprocating compressor-based fuel gas boosters is at least equal to the pressure and capacity required by the gas turbine.

11. A method of controlling the operation of the integrated system of a reciprocating compressor-based fuel gas booster and a gas turbine according to claim 1, the method comprising the steps of: -Control the position of the gas turbine fuel gas input control valve; as well as If the opening of the position is less than the set value (depending on the gas turbine), then - Reducing the capacity of the fuel gas booster.

12. The method of claim 11, wherein the step of reducing the capacity of the fuel gas booster is slowly actuated.

13. The method according to claim 11, wherein: In the case of two fuel gas boosters based on reciprocating compressors, If the required fuel gas pressure of the fuel gas booster is equal to or lower than the pressure that can be provided by each of the two reciprocating compressor based fuel gas boosters, Then only a fuel gas booster based on a reciprocating compressor is used.

14. The method of claim 13, wherein when only one reciprocating compressor based fuel gas booster is in use, the other reciprocating compressor based fuel gas booster is under maintenance.

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