Fuel gas booster-gas turbine integration for energy saving and optimized operation

Abstract

A fuel gas booster-gas turbine integration for energy conservation and optimized operability is disclosed. The fuel gas booster-gas turbine integration comprises an integrated system including a reciprocating compressor-based fuel gas booster (10) and a gas turbine (11), wherein a gas turbine flow and pressure control system (15) and a fuel gas booster pressure and capacity control system (20) are synchronized to optimize fuel gas booster power consumption or fuel gas booster and gas turbine package power consumption, the gas turbine flow and pressure control system (15) including at least one gas turbine fuel gas input control valve (14), and the fuel gas booster control system (20) including 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 controller associated with the reciprocating compressor-based fuel gas booster (10).

Description

Technical Field

[0001] The present disclosure relates to thermodynamic systems and methods. Embodiments disclosed herein relate particularly to an integrated system comprising a reciprocating compressor-based fuel gas booster and a gas turbine, in which fuel gas booster pressure and capacity control and gas turbine flow rate and pressure control are integrated to optimize the operation of the reciprocating compressor-based fuel gas booster. According to embodiments disclosed herein, the reciprocating compressor-based fuel gas booster and gas turbine system are automatically synchronized to the minimum absorption power operating point regardless of changes in the pressure, temperature, and composition of the ambient and fuel gas.

Background Art

[0002] Gas turbines require fuel gas at a specific pressure to combine the fuel gas with pressurized air prior to combustion. Typically, the gas pressure available from a pipeline is not sufficient for delivery at the pressure required by the gas turbine. In fact, due to the increasing gas pressure required for high-efficiency gas turbines and the increasing demand for natural gas, the gas pressure in the pipeline cannot be maintained at a sufficiently high value. This is particularly true for recent generations of gas turbines (requiring fuel gas pressure values exceeding 30 bar absolute pressure), and also during peak demand such as in summer or daytime when the gas pressure in the pipeline can gradually decrease and even fluctuate.

[0003] In order to meet the gas flow rate required by the gas turbine and at the same time appropriately handle the fluctuations in the gas pressure from such a pipeline, a fuel gas compressor must be interposed between the pipeline and the gas turbine. This fuel gas compressor is generally referred to as a fuel gas booster. The two most relevant variable conditions for a fuel gas booster are the fluctuations in the suction gas pressure and the changes in the load of the turbine.

[0004] U.S. Patent No. 6,948,919 (B2) discloses a fuel booster operable to compress a combustible fuel, comprising a compressor housing, a compression rotor, and a seal assembly coupled to the compressor housing. The fuel booster 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 rotational speed of the compressor motor is controlled to maintain the engine parameters at desired values. For example, one system monitors the fuel booster discharge pressure (fuel pressure) and changes the speed of the compressor motor to achieve a 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 speed of the compressor motor is increased. In another configuration, the engine parameter is the fuel flow rate, measured by a fuel flow meter (not shown) located downstream of the fuel booster. If the flow rate exceeds a desired value, the variable frequency drive reduces the frequency of the power supplied to the compressor motor, thereby decreasing the compressor motor speed and flow rate. If the flow rate is too low, the variable frequency drive increases the compressor motor speed to increase the flow rate to the desired value. In yet another configuration, the turbine outlet temperature is measured directly or indirectly, and the compressor motor speed is controlled to maintain a desired turbine outlet temperature. The systems described above control the compressor output without using conventional slide valves.

[0005] U.S. Patent No. 4922710(A) discloses an integrated boost compressor / gas turbine control system in which a fuel gas boost compressor increases the fuel gas pressure before supplying fuel gas to gas turbine control valves, i.e., stop / speed ratio or pressure control valves and gas control or positive displacement valves, and then supplies fuel gas to the gas turbine. According to this disclosure, the pressure drop through the gas turbine control valves, and therefore the boost power requirements, are minimized by driving these valves to the fully open position under normal operating conditions and using the valves in their normal control mode during other operating conditions such as startup and sudden load shedding. Thus, after startup operation, the system control transitions to operation with minimal system pressure drop, utilizing the flow control of the boost compressor to control the gas turbine fuel flow rate, and therefore the gas turbine output.

[0006] While the system described above effectively controls the operation of the gas turbine, it has significant limitations due to the power consumption of the fuel gas booster, which can reach up to 10% of the gas turbine's total rated power.

[0007] Furthermore, these limitations are also evident in the case of reciprocating compressor-based fuel gas boosters, which are the preferred type of compressor applied to fuel gas boosters in a typical size range (less than 500 kW). In practice, reciprocating compressors allow for lubrication-free operation, which is essential to avoid oil contamination of the combustion chamber, and offer significantly higher compression efficiencies compared to competing rotary technologies (e.g., screw compressors).

[0008] Therefore, to address the challenges of power absorption in current technology, improved systems and methods for operating reciprocating compressor-based fuel gas boosters and gas turbines would be beneficial and welcome in this technology. More generally, it is desirable to provide methods and systems adapted to more effectively address the problems caused by the need to increase fuel gas pressure, while simultaneously leading to significant energy and operating cost savings. [Overview of the project]

[0009] In one embodiment, the subject matter disclosed herein is a system that enables the optimization of fuel gas booster and gas turbine package operation and power consumption or fuel gas booster operation and power consumption to a minimum value when a reciprocating compressor-based fuel gas booster is used, by integrating fuel gas booster pressure and capacity control with gas turbine flow rate and pressure control.

[0010] In another embodiment, the subject matter disclosed herein relates to a control principle for automatically synchronizing a fuel reciprocating compressor-based gas booster and gas turbine package to a minimum absorbed power operating point, regardless of changes in ambient and fuel gas pressure, temperature, and composition. [Brief explanation of the drawing]

[0011] A complete understanding of many of the disclosed embodiments of the present invention and their associated advantages will be more readily obtained by referring to the following embodiments for carrying out the invention, in conjunction with the accompanying drawings. [Figure 1] A schematic diagram illustrating an integrated system comprising a reciprocating compressor-based fuel gas booster and a gas turbine according to one embodiment of the present disclosure is illustrated. [Modes for carrying out the invention]

[0012] In one embodiment, the subject matter aims to provide an integrated system comprising a reciprocating compressor-based fuel gas booster and a gas turbine, wherein the fuel gas booster pressure and capacity control and the gas turbine flow rate and pressure control are controlled to optimize the operation of the reciprocating compressor-based fuel gas booster.

[0013] In one embodiment, a reciprocating compressor-based fuel gas booster is integrally connected to a gas turbine casing, and the booster compressor increases the pressure and gaseous fuel. This is used to increase internal energy and generate more power with a smaller gaseous fuel flow rate.

[0014] In one embodiment, the fuel gas booster control system and gas turbine control system are integrated to automatically synchronize the reciprocating compressor-based fuel gas booster and gas turbine package to the minimum absorbed power operating point, regardless of changes in ambient and fuel gas pressure, temperature, and composition.

[0015] In certain embodiments, if the gas turbine control system sets the gas turbine control valve to a non-fully open position to optimize the operation of the gas turbine, the fuel gas booster control system operates to reduce its capacity. As a result of the reduced capacity of the fuel gas booster, the fuel gas from the reciprocating compressor-based fuel gas booster has a lower pressure, which allows the gas turbine control system to set the gas turbine control valve to the fully open position and reduce the pressure drop through the gas turbine control valve.

[0016] According to one embodiment, the fuel gas booster is a reciprocating compressor-based fuel gas booster comprising a plurality of cylinders, each cylinder having at least one cylinder effect, wherein the fuel gas booster capacity is controlled by each cylinder effect having a cylinder valve unloader that enables efficient step control (for example, a four-cylinder compressor having two effects per cylinder can be controlled by a 12.5% ​​capacity step adjustment).

[0017] According to one embodiment, fuel gas booster capacity control can be achieved through additional variable clearance pockets, which can manage capacity fluctuations by increasing and decreasing individual cylinder clearance pockets using actuators.

[0018] In another embodiment, the compressor valve can be controlled using other devices to manage efficient capacity control.

[0019] Alternatively, to manage the fuel gas booster capacity of a reciprocating compressor-based system, the motor driving the compressor may be equipped with a variable speed system.

[0020] Other fuel gas booster pressure and capacity control devices can be used, but the technical and commercial effectiveness of different solutions must be evaluated depending on the specific service of each reciprocating compressor-based fuel gas booster.

[0021] In another embodiment, the fuel gas booster control system is configured as a low-speed control system to minimize any interference with the gas turbine control system. As a result, the pressure drop through the gas turbine control valves, and therefore the boost power requirements, are minimized by driving these valves to the fully open position under normal operating conditions, and the gas turbine control valves are still used to regulate the operation of the gas turbine in normal control mode.

[0022] In one particular embodiment, a gas turbine control valve is used to regulate the operation of a gas turbine during startup and during sudden load shedding.

[0023] In another embodiment, optimizing the operation of a reciprocating compressor-based fuel gas booster leads to significant energy and operating cost savings.

[0024] Reference will now be made in detail to embodiments of the present disclosure. One or more of these examples are illustrated in the figures. Each example is provided by way of explanation of the present disclosure and not as a limitation thereof. It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the scope or spirit of the present disclosure. References throughout this specification to "one embodiment" or "an embodiment" or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with one embodiment is included in at least one embodiment of the disclosed subject matter. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Also, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0025] When presenting elements of various embodiments, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of those elements. The terms "comprising," "including," and "having" are intended to be non-exclusive and mean that additional elements other than the listed elements may exist.

[0026] Referring here to the drawings, Figure 1 shows a schematic diagram of an exemplary integrated system comprising a reciprocating compressor-based fuel gas booster 10 and a gas turbine 11, a fuel gas supply 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 located on the compressed fuel gas line 13 to regulate the pressure and flow rate of the fuel gas at the gas turbine inlet. 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 to the gas turbine control system 15 includes a pressure indicator 17 located upstream of the gas turbine control valve 14 on the compressed fuel gas line 13 and connected to the gas turbine control system 15 through a pressure indicator line 18. The input to the gas turbine control system 15 also includes a gas turbine flow demand line 19.

[0027] A fuel gas booster control system 20 is also present, and the input to the fuel gas booster control system 20 is provided by 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 specific pressure and capacity control devices selected for a particular service, such as a cylinder valve unloader for the cylinder effect of any of the multiple cylinders of the reciprocating compressor, an additional variable clearance pocket that can manage capacity fluctuations by increasing and decreasing individual cylinder clearance pockets by actuators, a reciprocating compressor inlet valve or a variable frequency drive motor 23 connected to the fuel gas booster control system 20 through a fuel gas booster control system output line 22.

[0028] 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 position that is not fully open in order to optimize the 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 a specific service. After the reduction in the capacity of the reciprocating compressor-based fuel gas booster 10, the fuel gas from the reciprocating compressor-based fuel gas booster 10 has a lower pressure, which enables the gas turbine control system 15 to set the gas turbine control valve 14 to the fully open position and reduce the pressure drop through the gas turbine control valve 14. As a result, the power absorbed by the reciprocating compressor-based fuel gas booster 10 is reduced without degrading the operability of the gas turbine.

[0029] In particular, if, for example, the ambient temperature is high or the turbine load is reduced, and the fuel gas pressure and / or flow rate from the reciprocating compressor-based fuel gas booster 10 is higher than the pressure and flow rate actually required by the gas turbine 11, the gas turbine control system 15 operates the gas turbine control valve 14 to a position that is not fully open. Partial closure of the gas turbine control valve 14 causes a pressure drop in the fuel gas before it reaches the gas turbine inlet from the reciprocating compressor-based fuel gas booster 10. This means that some 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 reciprocating compressor-based fuel gas booster 10 operates to overcompress the fuel gas for the pressure required by the gas turbine 11. At the same time, the reciprocating compressor-based fuel gas booster 10 is absorbing an excessive amount of power for what is needed. According to this disclosure, the amount of power absorbed is saved by reducing the capacity of the reciprocating compressor-based fuel gas booster 10, thereby enabling the reciprocating compressor-based fuel gas booster 10 to compress the fuel gas to the required pressure by the gas turbine and minimizing any subsequent possible pressure drop. In practice, within certain limits, reducing the pressure of the fuel gas at the inlet of the gas turbine 11 does not adversely affect the operability of the gas turbine 11, especially in the case of reduced load or high temperature. Generally, fuel gas boosters are designed to operate at 30 bar absolute pressure, but can also operate at lower pressures (down to about 26-27 bar absolute pressure) when the temperature is high (typically in summer) or the load is low.

[0030] Importantly, as described herein, the fuel gas booster control system 20 is used as an additional control system to the gas turbine control system 15, and therefore care must be taken to avoid system-to-system interference that could cause instability. In this regard, the fuel gas booster control system 20 is configured as a low-speed control system, while the gas turbine control system 15 is a high-speed control system. More specifically, the regulator of the fuel gas booster control system 20 is a proportional regulator or proportional-integral regulator with a low proportional gain value. As a result, the operation and transient conditions of the gas turbine 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 used solely to adjust the capacity of the reciprocating compressor-based fuel gas booster 10.

[0031] In particular, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to this disclosure can be used to automatically synchronize a reciprocating compressor-based fuel gas booster and gas turbine package to the minimum absorbed power operating point.

[0032] Alternatively, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to this disclosure can be used to minimize the fuel gas booster absorbed power operating point.

[0033] In particular, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 according to this disclosure can be used to reduce the settle-out pressure of closed circuits in the thermodynamic system after the shutdown of a booster such as a compressor, thereby facilitating system startup.

[0034] According to a specific implementation of the integration of the fuel gas booster control system 20 and the gas turbine control system 15 of this disclosure, two fuel gas boosters can be used, and the fuel gas boosters are designed to provide pressure and flow rates lower than those required by the gas turbine, and even up to 50% of the pressure and flow rates required by the gas turbine. This configuration ensures increased availability and reliability under specific conditions without adversely affecting the system under normal operating conditions. For example, in summer, the gas turbine can be operated at full load with reduced fuel gas pressure from the reciprocating compressor-based fuel gas booster, so that only one of the redundant reciprocating compressor-based fuel gas boosters can be used while the other is maintained.

[0035] Finally, the integration of the fuel gas booster control system 20 and the gas turbine control system 15 as disclosed herein enables power savings of up to 30% (location-dependent) for the fuel gas booster, increased reliability and availability for minimum load operation of the reciprocating compressor-based fuel gas booster in all conditions, and automatic tracking of the ambient and fuel gas booster conditions.

[0036] While aspects of the present invention have been described in relation to various specific embodiments, it will be apparent to those skilled in the art that many modifications, changes, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless otherwise specified herein, the order or arrangement of any process or method steps may be changed or rearranged according to alternative embodiments.

Claims

1. It is an integrated system, A reciprocating compressor-based fuel gas booster (10), A gas turbine (11) connected to the fuel gas booster (10) by a compressed fuel gas line (13), At least one gas turbine fuel gas input control valve (14) is located on the compressed fuel gas line (13), A gas turbine flow rate and pressure control system (15) that operates the at least one gas turbine fuel gas input control valve (14), A fuel gas booster pressure and capacity control system (20) controls the capacity of the reciprocating compressor-based fuel gas booster (10), Equipped with, The fuel gas booster pressure and capacity control system (20) is synchronized to optimize fuel gas booster power consumption or fuel gas booster and gas turbine package power consumption by reducing the fuel gas booster capacity when the at least one gas turbine fuel gas input control valve (14) is set to a position other than fully open, an integrated system.

2. The system according to claim 1, wherein the fuel gas booster pressure and capacity control system (20) is selected from among a cylinder valve unloader related to 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 fuel gas booster pressure and capacity control system (20) is a low-speed control system.

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

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

6. The system according to claim 1, wherein the gas turbine flow rate and pressure control system (15) is a high-speed control system.

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

8. The system according to claim 1, comprising two reciprocating compressor-based fuel gas boosters.

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

11. A method for controlling the operation of an integrated reciprocating compressor-based fuel gas booster and gas turbine system according to claim 1, - A step of controlling the position of at least one gas turbine fuel gas input control valve, If the aforementioned position is not open to a set value (depending on the gas turbine), A method comprising the step of reducing the fuel gas booster capacity.

12. The method according to claim 11, wherein the step of reducing the fuel gas booster capacity is performed gradually.

13. When two reciprocating compressor-based fuel gas boosters are used, If the required fuel gas pressure from the fuel gas booster is less than or equal to the pressure that can be provided by each of the two reciprocating compressor-based fuel gas boosters, The method according to claim 11, wherein only one reciprocating compressor-based fuel gas booster is used.

14. The method according to claim 13, wherein while one reciprocating compressor-based fuel gas booster is in use, the other is maintained.

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