Patent Application
20090000302
1. Field of the Invention
The invention is generally related to a system and method for delivering natural gas from a utility gas service to power generation equipment installed in or around a building.
2. Background
Office building tenants across the country are increasingly sensitive to the quality and reliability of their electric power. Most are dramatically expanding their investment in and reliance upon sophisticated computer and telecommunications equipment and networks that are increasingly vulnerable to grid-related power fluctuations and outages. To retain existing tenants and to attract new ones, office building owners need to establish a new standard of service that delivers power with reliability and quality that effectively addresses these growing concerns.
One approach for providing such a standard of service involves installing on-site power generation equipment. Such power generation equipment may include state-of-the-art, gas-fired, distributed generation units that produce reliable, high-quality, and environmentally-friendly power and supplemental thermal energy. Such systems can provide an efficient way for office property owners to provide the power, reliability, and quality that will keep their facilities state-of-the-art and a step ahead of their competition. One method for installing and operating such equipment in a manner that mutually benefits both the installer of the equipment and the building owner is described in commonly-owned, co-pending U.S. patent application Ser. No. 11/586,646, entitled “Method for Providing Energy to a Building Using Utility-Compatible Distributed Generation Equipment”, filed Oct. 26, 2006, the entirety of which is incorporated by reference herein.
Some power generation equipment operates on natural gas. When installing such equipment in an office building, several challenges arise. For example, gas-fired microturbines typically require natural gas to be supplied at some minimum volume of gas flow and some minimum level of gas pressure in order to operate. In some instances, the utility can provide the required volume of gas flow but cannot meet or maintain the required level of gas pressure. In other instances, although the utility can supply the required volume of gas flow and level of gas pressure, frictional loss associated with piping the gas from the utility interface to the power generation equipment can result in the gas being supplied to the equipment at less than the minimum pressure level.
Another challenge when installing on-site gas-fired power generation equipment is installing the requisite piping to deliver the natural gas between the utility gas service and the power generation equipment. For a variety of reasons, it is often desirable to use pipe having a relatively small diameter (e.g., a diameter of less than 4 inches) for this purpose. For example, the use of smaller pipe can substantially reduce installation costs as smaller pipe is less expensive and easier to install than larger pipe. Additionally, the building codes of some cities require that pipe above a certain diameter must be welded together during installation. In addition to being cost-prohibitive, such welding is time-consuming and generates unpleasant odors, which can be problematic when the building is already occupied by tenants.
Although the use of a smaller diameter pipe for the gas delivery line is desirable, it is also problematic in that it limits the volume of gas flow to the power generation equipment and increases frictional loss, which reduces gas pressure. As noted above, gas-fired microturbines typically require natural gas to be delivered at some minimum volume of gas flow and some minimum level of gas pressure in order to operate.
Finally, any natural gas delivery system installed in a multi-tenant building, such as an office building, will likely need to satisfy local building codes and stringent safety regulations and requirements. However, most commercially-available gas delivery systems, such as most commercially-available gas boosters, do not provide the requisite control system necessary to satisfy these codes, regulations and requirements.
What is needed then is a gas delivery system that is capable of delivering natural gas from a utility gas service to power generation equipment installed in or around a building in a manner that meets the minimum volume and pressure requirements of the power generation equipment. The desired gas delivery system should advantageously use pipe of a relatively small size for delivering gas to the power generation equipment, thereby substantially reducing installation costs and eliminating the need for a welded gas line. The desired gas delivery system should also provide a control system that facilitates close control over the gas flow and ensures compliance with local building codes and safety regulations and requirements.
A gas delivery system of the present invention includes a gas booster module for delivering natural gas from a utility gas service to power generation equipment installed in or around a building in a manner that meets the minimum volume and pressure requirements of the power generation equipment. In accordance with an embodiment of the present invention, the gas delivery system advantageously uses pipe of a relatively small size for delivering gas to the power generation equipment, thereby substantially reducing installation costs and eliminating the need for a welded gas line. In accordance with a further embodiment of the present invention, the gas delivery system also includes a control system that facilitates close control over the gas flow and ensures compliance with local building codes and safety regulations and requirements.
In particular, a gas booster module in accordance with an embodiment of the present invention includes a common supply pipe, a common discharge pipe, a first gas booster and a second gas booster. The first gas booster has an inlet connected to the common supply pipe and a discharge connected to the common discharge pipe. The second gas booster has an inlet connected to the common supply pipe and a discharge connected to the common discharge pipe. Each of the first and second gas boosters is independently operable to receive a flow of natural gas from the common supply pipe and to discharge the flow of natural gas to the common discharge pipe at an elevated gas pressure. Each of the first and second gas boosters is also controllable to increase or reduce the volume of the flow of natural gas received and discharged by that booster responsive to the requirements of power generation equipment connected to the gas booster module via the common discharge pipe.
A power generation system in accordance with an embodiment of the present invention includes power generation equipment and a gas delivery system configured to provide natural gas from a utility gas supply to the power generation equipment. The gas delivery system includes a gas booster module and a control system electrically connected to the gas booster module. The gas delivery system is operable to receive a flow of natural gas from the utility gas supply and to discharge the flow of natural gas to the power generation equipment at an elevated gas pressure. The control system is configured to control the volume of the flow of natural gas to and from the gas booster module responsive to the requirements of the power generation equipment.
A method for supplying natural gas to power generation equipment in accordance with an embodiment of the present invention includes a number of steps. First, a selected one of a first gas booster and a second gas booster receives a flow of natural gas from a utility gas supply. Second, the flow of natural gas is discharged at an elevated gas pressure from the selected gas booster to the power generation equipment. Third, the selected gas booster is controlled to increase or reduce the volume of the flow of natural gas received and discharged by that booster responsive to the requirements of the power generation equipment.
A method for supplying natural gas to power generation equipment in accordance with an alternate embodiment of the present invention also includes a number of steps. First, a flow of natural gas is received in a first gas booster from a utility gas supply. Second, the flow of natural gas is discharged at an elevated gas pressure from the first gas booster. Third, the flow of natural gas from the first gas booster is received in a second gas booster. Fourth, the flow of natural gas is discharged at a further elevated gas pressure from the second gas booster to the power generation equipment.
Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.
The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the relevant art(s) to make and use the invention.
The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.
As shown in
The power generation plant also includes a 30 kW standby generator 108 and an optional 1,000 kW standby generator 110, the function of which will be described in more detail herein. Like microturbines 112, both standby generators 108 and 110 also require a supply of natural gas to operate. Microturbines 112, standby generator 108, and optional standby generator 110 may be collectively referred to herein as “the power generation equipment”.
In the operating environment depicted in
As shown in
Power generation plant 100 of
As shown in
Main head valve 122 is a point of demarcation between the gas piping installed by the utility and gas piping to be installed by or on behalf of the building owner. When open, main head valve 122 allows natural gas supplied by the utility to flow to the duplex meter via an 8-inch diameter pipe. The natural gas flows from the 8-inch diameter pipe to one or both of revenue meters 124 and 126 along respective 6-inch diameter pipes, depending on the state of manual isolation valves associated with each of those meters, as shown in
From utility meter rig 102, natural gas flows via discharge pipe 128 to gas booster module 104. As noted above, gas booster module 104 ensures that gas received from the utility via the meter rig is delivered to the power generation equipment in a manner that meets all pressure and volume requirements of that equipment. In the example operating environment of
In addition to elevating the gas pressure to meet the minimum pressure requirements of the power generation equipment, gas booster module 104 must also elevate the gas pressure to compensate for the use of a 3-inch diameter pipe to carry the gas through the office building. The use of pipe having such a small diameter restricts the volume of gas flow to the power generation equipment and also increases frictional loss, which reduces gas pressure. The longer the 3-inch diameter pipe that is used, the greater the frictional loss.
However, the use of a 3-inch diameter pipe is desirable because smaller pipe is less expensive and easier to install than larger pipe, thereby allowing installation costs to be reduced. Additionally, in the example operating environment of
As shown in
In the implementation shown in
Natural gas is received by gas booster module 104 via an 8-inch diameter common supply pipe 132 and flows to either gas booster 129 or gas booster 130 along a respective one of two 8-inch diameter pipes, depending on which gas booster is currently operating. The gas flow through common supply pipe 132 can be controlled via an inlet valve 138, which is open during normal operation. The operating gas booster delivers a flow of natural gas at an increased gas pressure to a 4-inch diameter common discharge pipe 134.
As shown in
Check valves 142, 144 and 146 are used in gas booster module 104 to ensure that gas flows in one direction only. A flame arrestor 148 is provided along common discharge pipe 134 in order to comply with local regulatory requirements.
Natural gas discharged from gas booster module 104 flows through piping 114 to the power generation equipment installed on the rooftop of the building. As discussed above, piping 114 preferably comprises pipes of a relatively small diameter, such as 3-inch diameter pipe. At the rooftop, the natural gas passes through a gas filter 106, which removes undesired particulate matter from the natural gas before it is supplied to the power generation equipment. Such a gas filter may be purchased from any number of vendors and should be sized based on the volume of gas flow, the gas pressure, and the pipe size. As shown in
From the discharge of gas filter 106, natural gas flows to the power generation equipment, which includes microturbines 112, standby generator 108 and standby generator 110. Gas is delivered to the inlet of each microturbine 112 via a 2-inch diameter pipe and is delivered to the inlet of standby generator 108 via a 1.5-inch diameter pipe. As shown in
Standby generator 108 is a gas generator that can be used during a power outage to start the auxiliary systems necessary to run microturbines 112. In one operating environment, standby generator 108 is a 30 kW generator designed and supplied by Kohler Power Systems of Kohler, Wis., although many other gas generators may be used. In an alternative implementation, a battery-based uninterrupted power supply (UPS) system can be used instead of a gas generator, although UPS systems are typically more expensive to purchase and maintain.
As noted above, the power generation equipment of power generation plant 100 may also include an optional 1,000 kW gas-fired standby generator 110. Such a standby generator may be used to generate power for the building in the instance that one or more of microturbines 112 fail to operate. Alternatively or additionally, standby generator 110 may be operated in conjunction with microturbines 112 to provide an increased supply of power to the building. In implementations where standby generator 110 is operated concurrently with microturbines 112, gas booster module 104 must be configured to supply the requisite volume of gas flow and gas pressure necessary to operate both microturbines 112 and standby generator 110. In an implementation that does not include such a standby generator, a tap may nevertheless be provided along the gas line for the installation of future equipment.
In accordance with one implementation, when power generation plant 100 is fully operational, gas booster module 104 is capable of supplying a volume of gas flow of approximately 28,413 cubic feet per hour under standard operating conditions (Schf). Of this gas flow, it is anticipated that approximately 14,400 Scfh will be consumed by microturbines 112, approximately 13.0 Scfh will be consumed by standby generator 108, and roughly 14,000 Scfh will be consumed by optional standby generator 110.
B. Example Gas Booster Module in Accordance with an Embodiment of the Present Invention
The elements of gas booster module 200 will now be described. In
As shown in
From inlet pipe 202, natural gas flows to a common supply pipe 212 that is connected to a first gas booster 220 (denoted “GB1”) via a first gas booster inlet pipe 254 and to a second gas booster 238 (denoted “GB2”) via a second gas booster inlet pipe 256. For safety reasons, an electro-hydraulic gas safety valve 206 (denoted “GSV1”) is installed between inlet pipe 202 and common supply pipe 212 to control the flow of gas there between. Gas safety valve 206 is configured such that it will only open and remain open when 120 volts alternating current (VAC) of power is applied to the valve. However, if for any reason power is lost to the valve, it will shut. This permits the control system associated with gas booster module 200 to quickly close gas safety valve 206 in the event that an abnormal operating condition is detected, thereby shutting off the supply of natural gas to the building. Such an abnormal operating condition might include the detection of a ruptured gas line or the pressing of an emergency stop button provided as part of the control system.
As shown in
From common supply pipe 212, natural gas will flow to either first gas booster 220 via first gas booster inlet pipe 254 or to second gas booster 238 via second gas booster inlet pipe 256, depending on which gas booster is currently operating. This duplex configuration ensures that if one gas booster is taken off-line for inspection or service or fails unexpectedly, the other gas booster can be brought on-line (either manually or automatically) to perform the gas boosting function. In one implementation, gas boosters 220 and 238 are each single-stage gas boosters having a similar or identical design. For example, each gas booster 220 and 238 may be an HB-4628-10 hermetic gas booster designed and supplied by Eclipse, Inc. of Rockford, Ill. As noted above, these units are 10 horse power units capable of providing pressure boosts of approximately 35 inWC at gas flows of up to approximately 46,300 CFH.
The inlet of first gas booster 220 is connected to first gas booster inlet pipe 254 via a flexible connector 218 (denoted “FC2”) while the inlet of second gas booster 238 is connected to second gas booster inlet pipe 256 via a flexible connector 236 (denoted “FC4”). In a like manner, a flexible connector 228 (denoted “FC1”) is used to connect the discharge of first gas booster 220 to a first gas booster discharge pipe 258 and a flexible connector 246 (denoted “FC3”) is used to connect the discharge of second gas booster 238 to a second gas booster discharge pipe 260. These flexible connectors are intended to prevent the transmission of vibrational energy from the gas boosters to the respective inlet pipes and discharge pipes. The transmission of such energy is to be avoided as it can damage the piping of the gas delivery system, any equipment attached thereto, or the building itself.
A manual isolation valve 216 (denoted “V2”) is provided along first gas booster inlet pipe 254 while another manual isolation valve 232 (denoted “V1”) is provided along first gas booster discharge pipe 258. These manual isolation valves can be closed to stop the flow of gas to first gas booster 220, thereby allowing first gas booster 220 to be inspected, serviced or replaced. In a like manner, manual isolation valves 234 (denoted “V4”) and 250 (denoted “V3”) are provided along second gas booster inlet pipe 256 and second gas booster discharge pipe 260, respectively, and may be closed to allow second gas booster 238 to be inspected, serviced or replaced.
During operation, first gas booster 220 discharges a flow of pressure-boosted natural gas to a common discharge pipe 262 via first gas booster discharge pipe 258. In a like manner, during operation, second gas booster 238 discharges a flow of pressure-boosted natural gas to common discharge pipe 262 via second gas booster discharge pipe 260. The control system associated with gas booster module 200 drives each of the two gas boosters using a corresponding variable frequency drive, thereby allowing the control system to modulate the amount of gas flow through each gas booster. Such a capability is important to maintain better control of the gas flow during load-following operation.
From common discharge pipe 262, natural gas flows to the power generation equipment via a pipe or system of pipes (not shown in
High pressure switch 266 is a switch that is configured to close when the gas pressure in common discharge pipe 262 exceeds a predetermined maximum gas pressure, thereby cutting off the supply of natural gas to the power generation equipment. For example, in one embodiment, high pressure switch 266 is configured to close when the gas pressure in common discharge pipe 262 exceeds approximately 3 pounds per square inch (PSI). As shown in
Low pressure switch 268 is a switch that is configured to close when the gas pressure in common discharge pipe 262 drops below a predetermined minimum gas pressure, thereby cutting off the supply of natural gas to the power generation equipment. Low pressure switch 268 is installed to ensure that the gas delivery system is shut down when there is an unusually low pressure discharge from gas booster module 200, which could indicate a rupture in the gas delivery line running up through the building. As shown in
Analog pressure transmitter 270 is a sensor that measures the gas pressure within common discharge pipe 262 and provides the gas pressure measurement information as an analog input signal to the control system associated with gas booster module 200. The control system in turn displays the gas pressure measurement information to a user. This information can be monitored by the user or the control system itself to determine if gas booster module 200 is working properly and whether there is an unsafe condition based on the gas pressure within common discharge pipe 262 being too low or too high.
Furthermore, such gas pressure measurement information can be used to monitor whether or not gas booster module 200 is discharging natural gas at a level of pressure that is sufficient to meet the pressure requirements of the power generation equipment. In situations where gas booster module 200 is not discharging natural gas at the requisite level of pressure, the control system can be used to increase the speed of the variable frequency drive associated with first gas booster 220 or the variable frequency drive associated with second gas booster 238 to raise the gas pressure at the discharge of gas booster module 200. Conversely, if gas booster module 200 is discharging natural gas at a pressure level that exceeds that required to operate the power generation equipment, the control system can be used to decrease the speed of the variable frequency drive associated with first gas booster 220 or the variable frequency drive associated with second gas booster 238 to lower the gas pressure at the discharge of gas booster module 200 and thereby conserve cost. Depending upon the implementation, the monitoring of the gas pressure measurement information and corresponding adjustment of the speed of the variable speed drives can either be performed manually by a user or automatically by the control system itself.
Flame arrestor 272 is provided along common discharge pipe 262 in order to comply with local regulatory requirements. Flame arrestor 272 is designed to extinguish a flame that might be ignited within common discharge pipe 262 and thereby prevent the propagation of the flame through the piping system to the rooftop of the building.
As shown in
The above-described bypass system is provided in order to ensure that the volume of natural gas flowing through the operating gas booster is sufficient to cool the motor of that booster. If the flow of natural gas through a gas booster is reduced for some reason (e.g., a failure of one or more microturbines or the operation of only a single microturbine for testing purposes), then the gas booster motor windings and motor itself will begin to increase in temperature. Unchecked, this heating can result in damage to the motor and, ultimately, failure of the gas booster.
By monitoring the temperature of the natural gas flowing through gas booster module 200, the control system associated therewith can modulate the amount of gas that is recirculated through the bypass system via the controlled opening and closing of first motorized valve 276 as well as the amount of cooling applied to the recirculated gas through the controlled opening and closing of second motorized valve 280. As shown in
In order to monitor the temperature of natural gas flowing through gas booster module 200, the module includes a plurality of temperature sensors including a temperature sensor 214 (denoted “T4”), a temperature sensor 226 (denoted “T2”), a temperature sensor 244 (denoted “T3”) and a temperature sensor 264 (denoted “T1”). Each of these temperature sensors measures the temperature of the natural gas flowing through a pipe of gas booster module 200 and provides the gas temperature measurement information as an analog input to the control system associated with gas booster module 200. In particular, temperature sensor 214 measures the temperature of the gas flowing through common supply pipe 212, temperature sensor 226 measure the temperature of the gas being discharged by first gas booster 220 into first gas booster discharge pipe 258, temperature sensor 244 measures the temperature of the gas being discharged by second gas booster 238 into second gas booster discharge pipe 260, and temperature sensor 264 measures the temperature of the gas flowing through common discharge pipe 262. In one embodiment, each temperature sensor is implemented using a thermistor-type temperature sensor, although the invention is not so limited. Each temperature sensor may be mounted in a well within a pipe of gas booster module 200 for easy removal and replacement.
In one implementation of the present invention, a three-level control scheme is applied to respond to increased temperature information reported from one or more of the temperature sensors. In accordance with such a scheme, if the temperature of the natural gas increases into a first temperature range, motorized valves 276 and 280 are opened to recirculate natural gas through the bypass system and to cool the recirculated gas. If the temperature of the natural gas nevertheless increases into a second temperature range, then the gas booster that is currently operating is shut down and the other gas booster is brought on-line. After this, if the temperature of the natural gas increases into a third temperature range, the entire gas booster module is shut down, gas safety valve 206 is closed, and one or more alarms are optionally sounded. It is noted that this control scheme is provided by way of example only, and persons skilled in the art will readily appreciate that a wide variety of other control schemes may be used to monitor and respond to changing gas temperatures as reported by gas booster module 200.
In addition to using the temperature information provided by temperature sensors 214, 226, 244 and 264 to control the amount of gas that is recirculated through the bypass system as well as the amount of cooling that is applied to such recirculated gas, the control system can also monitor such temperature information to detect abnormal or unsafe operating conditions.
Gas booster module 200 includes other temperature switches and sensors for control and safety reasons. For example, first gas booster 220 and second gas booster 238 each include a motor temperature switch that is mounted in the windings of the motor of the gas booster. In particular, first gas booster 220 includes a motor temperature switch 224 (denoted “MTS3”) and second gas booster 238 includes a motor temperature switch 242 (denoted “MTS4”). In one implementation, each motor temperature switch is a thermal contact switch that opens if the windings of the motor reach or exceed a certain temperature (e.g., 240 degrees), thereby shutting down the gas booster. In such an implementation, each motor temperature switch provides a digital input signal to the control system associated with gas booster module 200 that indicates the state of the switch. In an alternate implementation, each motor temperature switch may be a temperature sensor that provides an analog input signal to the control system indicating the temperature of the motor of the gas booster. This temperature may be monitored by the control system to identify abnormal operating conditions and shut down the gas booster if necessary.
As shown in
As also shown in
Control panel 308 provides an interface between gas booster module 300 and a control system associated therewith, which will be described in more detail herein.
As shown in
As also shown in
Manual isolation valves are also provided at the inlet and discharge of each gas booster so that each gas booster may be taken off-line for inspection, servicing or replacement. In particular, a first six-inch flanged manual isolation valve 326 is located at the inlet to first gas booster 302 while a first four-inch flanged manual isolation valve 330 is located at the discharge thereof Likewise, a second six-inch flanged manual isolation valve 328 is located at the inlet to second gas booster 304 while a second four-inch flanged manual isolation valve 332 is located at the discharge thereof.
As further shown in
As shown in
C. Alternative Gas Booster Module in Accordance with an Embodiment of the Present Invention
As will be described in more detail below, gas booster module 400 is configured such that three modes of operation are possible: in a first mode of operation, only first gas booster 420 performs the gas boosting function, in a second mode of operation, only second gas booster 438 performs the gas boosting function, while in a third mode of operation first gas booster 420 and second gas booster 438 operate in series to perform the gas boosting function. In the first and second modes of operation, only a single gas booster is used at a time, in a like manner to the system discussed above in reference to
The direction of the flow of natural gas through gas booster module 400 during the various operating modes is indicated by black arrows. Check valve 410 (denoted “CV5”), check valve 433 (denoted “CV1”), check valve 452 (denoted “CV2”), check valve 480 (denoted “CV4”), check valve 486, and check valve 488 (denoted “CV3”) are installed along pipes of gas booster module 400 to ensure that natural gas flows in one direction only.
As shown in
From common supply pipe 412, natural gas can flow along one of three paths, depending upon the mode of operation of gas booster module 400. In a first mode of operation, the only gas booster that is operating is first gas booster 420. During this mode of operation, natural gas flows from common supply pipe 412 to first gas booster module 420 via a first gas booster inlet pipe 454. Pressure-boosted natural gas is then discharged from first gas booster 420 to a common discharge pipe 462 via a first gas booster discharge pipe 458 and a second gas booster bypass pipe 484.
In a second mode of operation, the only gas booster that is operating is second gas booster 438. During this mode of operation, natural gas flows from common supply pipe 412 to second gas booster module 438 via a first gas booster bypass pipe 482 and a second gas booster inlet pipe 456. Pressure-boosted natural gas is then discharged from second gas booster 438 to common discharge pipe 462 via a second gas booster discharge pipe 460.
In a third mode of operation, both gas boosters are operating. This mode of operation can optionally be used to achieve an increased level of gas pressure as compared to either the first or second operating modes. During this mode of operation, natural gas flows from common supply pipe 412 to first gas booster 420 via first gas booster inlet pipe 454. Pressure-boosted natural gas is then discharged from first gas booster 420 to the inlet of second gas booster 438 via first gas booster discharge pipe 458 and second gas booster inlet pipe 456. Pressure-boosted natural gas is then discharged from second gas booster 438 to common discharge pipe 462 via second gas booster discharge pipe 460.
In a like manner to the gas boosters of gas booster module 200, each of gas boosters 420 and 438 is connected to respective inlet and discharge pipes via flexible connectors. In particular, first gas booster 420 is connected to first gas booster inlet and discharge pipes 454 and 458 via flexible connector 418 (denoted “FC2”) and flexible connector 428 (denoted “FC1”), respectively, and second gas booster 438 is connected to second gas booster inlet and discharge pipes 456 and 460 via flexible connector 436 (denoted “FC4”) and flexible connector 446 (denoted “FC2”), respectively.
Furthermore, a manual isolation valve 416 (denoted “V2”) is provided along first gas booster inlet pipe 454 while another manual isolation valve 432 (denoted “V1”) is provided along first gas booster discharge pipe 458. These manual isolation valves can be closed to stop the flow of gas to first gas booster 420, thereby allowing first gas booster 420 to be inspected, serviced or replaced. In a like manner, manual isolation valves 434 (denoted “V4”) and 450 (denoted “V3”) are provided along second gas booster inlet pipe 456 and second gas booster discharge pipe 460, respectively, and may be closed to allow second gas booster 238 to be inspected, serviced or replaced.
From common discharge pipe 462, natural gas flows to power generation equipment via a pipe or system of pipes (not shown in
Like gas booster module 200 described above in reference to
By monitoring the temperature of the natural gas flowing through gas booster module 400, the control system associated therewith can modulate the amount of gas that is recirculated through the bypass system via the controlled opening and closing of motorized valve 476. In addition, in the implementations of mechanical cooling system 478 depicted in
Gas booster module 400 includes other temperature switches and sensors for control and safety reasons. For example, first gas booster 420 and second gas booster 438 each include a motor temperature switch that is mounted in the windings of the motor of the gas booster. In particular, first gas booster 420 includes a motor temperature switch 424 (denoted “MTS1”) and second gas booster 438 includes a motor temperature switch 442 (denoted “MTS2”). These switches operate in a similar fashion to motor temperature switches 224 and 242 described above in reference to
As also shown in
In one implementation, both first gas booster 420 and second gas booster 438 are units capable of providing pressure boosts of approximately 35 inWC at gas flows of up to approximately 46,300 CFH. It should be noted, however, that running first and second gas boosters 420 and 438 in series will not result in a total pressure boost of 75 inWC. Rather, due to the fact that the pressure-boosted gas being supplied from the discharge of first gas booster 420 to the inlet of second gas booster 438 has an increased temperature and volume, second gas booster 438 will not operate at full efficiency. Consequently, the amount of pressure boost provided by second gas booster 438 in this mode of operation will be less than 35 inWC, and will likely be in the range of approximately 15-20 inWC, yielding a total pressure boost of approximately 50-55 inWC. Nevertheless, this total pressure boost resulting from serial operation of first gas booster 420 and second gas booster 438 still exceeds the pressure boost resulting from the operation of one unit alone.
As shown in
D. Gas Booster Module Having Single-Stage and Multi-Stage Gas Boosters in Accordance with an Embodiment of the Present Invention
As discussed above, gas booster module 200 of
By using a combination of a single-stage gas booster and a multi-stage gas booster, operation of the gas booster module can be adapted to support different load conditions. Thus, using power generation plant 100 of
As will be appreciated by persons skilled in the art, like gas booster module 200 of
E. Control System in Accordance with an Embodiment of the Present Invention
A gas delivery system in accordance with the present invention includes a control system that is configured to receive information from the gas booster module as well as other system components, and automatically perform actions in response to that information. Such actions may include but are not limited to increasing or decreasing gas flow through the gas booster module, increasing or decrease an amount of gas recirculated through a bypass system of the gas booster module and/or the amount of cooling applied to such recirculated gas, turning on or off one or more gas boosters, shutting off the flow of gas to or from the gas booster module, or generating one or more alarms.
As will be discussed in more detail herein, components of gas delivery system 600 other than gas booster module 606 that communicate with control system 602 may include without limitation a temperature sensor, flame detector, and methane gas detector located in the same room as gas booster module 606, an exhaust fan located near gas booster module 606, one or more emergency power off buttons electrically connected to gas booster module 606, a building fire alarm system, utility gas meters, and an annunciator control panel.
As shown in
The analog input signals received by controller 700 include a gas booster module (GBM) enclosure temperature signal 702 (denoted “AI-1”), a GBM discharge gas pressure signal 704 (denoted “AI-2”), a GBM discharge gas temperature signal 706 (denoted “AI-3”), a first gas booster (GB1) discharge gas temperature signal 708 (denoted “AI-4”), a second gas booster (GB2) discharge gas temperature signal 710 (denoted “AI-5”), a GBM suction gas temperature signal 712 (denoted “AI-6”), a chilled water return (CHWR) temperature signal 714 (denoted “AI-7”), a chilled water supply (CHWS) temperature signal 716 (denoted “AI-8”) and a GBM room temperature signal 718 (denoted “AI-9”).
GBM enclosure temperature signal 702 is an analog signal provided by a temperature sensor located within the gas booster module enclosure and is indicative of the temperature within that enclosure. GBM room temperature signal 718 is an analog signal provided by a temperature sensor located in the room within which the gas booster module has been installed.
GBM discharge gas pressure signal 704 is a signal provided by an analog pressure transmitter located along the common discharge pipe of the gas booster module, such as analog pressure transmitter 270 of
GBM discharge gas temperature signal 706 is an analog signal provided by a temperature sensor mounted at the common discharge pipe of the gas booster module, such as temperature sensor 264 of
Each of signals 706, 708, 710 and 712 provides an indication of the temperature of the natural gas flowing through a certain part of the gas booster module. In addition to being monitored for information and safety purposes, as noted above in reference to
CHWS temperature signal 716 is an analog signal provided by a temperature sensor mounted along the pipe that is used to supply chilled water to the mechanical cooling system located along the bypass path of the gas booster module. CHWR temperature signal 714 is an analog signal provided by a temperature sensor mounted along the pipe that is used to return the chilled water from the mechanical cooling system. For example, in
The digital input signals received by controller 700 include a GBM low inlet gas pressure switch signal 720 (denoted “DI-1”), a gas safety valve (GSV1) proof of closure switch signal 722 (denoted “DI-2”), a first gas booster (GB1) high temperature switch signal 724 (denoted “DI-3”), a first gas booster (GB1) motor temperature switch signal 726 (denoted “DI-4”), a second gas booster (GB2) high temperature switch signal 728 (denoted “DI-5”), a second gas booster (GB2) motor temperature switch signal 730 (denoted “DI-6”), a GBM high pressure switch signal 732 (denoted “DI-7”), a GBM low pressure switch signal 734 (denoted “DI-8”), a GBM flame detection signal 736 (denoted “DI-9”), a first gas booster (GB1) run status signal 738 (denoted “DI-10”), a first gas booster (GB1) fault status switch signal 740 (denoted “DI-11”), a second gas booster (GB2) run status switch signal 742 (denoted “DI-12”), a second gas booster (GB2) fault status switch signal 744 (denoted “DI-13”), a GBM exhaust fan status signal 746 (denoted “DI-14”), an annunciator control panel (ACP) test LED button signal 748 (denoted “DI-15”), an alarm reset button signal 750 (denoted “DI-16”), emergency power off (EPO) status signals 752 (denoted “DI-17”, “DI-18”, “DI-19” and “DI-20”), a methane detector status signal 754 (denoted “DI-21”), a GBM exhaust fan status signal 756 (denoted “DI-22”), a building fire alarm status signal 758 (denoted “DI-23”), a gas meter number 1 pulses signal 760 (denoted “DI-24”), a gas meter number 2 pulses signal 762 (denoted “DI-25”) and spare digital input signals 764 (denoted “DI-26” and “DI-27”).
GBM low inlet gas pressure switch signal 720 is a digital signal provided by a low pressure switch, such as low pressure switch 204 of
GSV1 proof of closure switch signal 722 is a digital signal provided by a proof of closure (POC) switch, such as POC switch 208 of
GB1 high temperature switch signal 724 is a digital signal provided by a temperature switch, such as temperature switch 222 of
GB1 motor temperature switch signal 726 is a digital signal provided by a motor temperature switch, such as motor temperature switch 224 of
GBM high pressure switch signal 732 is a digital signal provided by a high pressure switch, such as high pressure switch 266 of
GBM flame detection signal 736 is a digital signal provided by a sensor that is mounted in the room within which the gas booster module is installed. The sensor utilizes ultraviolet and infrared technology to detect a flame appearing on or around the gas booster module. This situation may occur where natural gas has escaped from a breach in the gas booster module and is ignited.
GB1 run status signal 738 and GB1 fault status signal 740 are digital signals provided by the variable frequency drive associated with the first gas booster of the gas booster module. These signals respectively indicate whether or not the drive associated with the first gas booster is running and whether or not the drive is in a fault state. Likewise, GB2 run status signal 742 and GB2 fault status signal 744 are digital signals provided by the variable frequency drive associated with the second gas booster of the gas booster module. These signals respectively indicate whether or not the drive associated with the second gas booster is running and whether or not the drive is in a fault state.
GBM exhaust fan status signal 746 and GBM exhaust fan status signal 756 are digital signals provided by a mechanical exhaust fan that is used to ventilate the room in which the gas booster module is installed. Each signal 746 and 756 indicates whether the exhaust fan is on or off.
ACP test LED button signal 748 is a digital signal provided by an annunciator control panel located somewhere within the building within which the power generation plant is located, such as in the lobby. The annunciator control panel includes a plurality of LEDs which can be selectively activated by controller 700 to indicate the status of a corresponding element of the gas delivery system. The annunciator control panel also includes a test LED button, which, when activated by a user, generates signal 748. Upon receipt of signal 748, controller 700 sends digital signals to activate the plurality of LEDs. If one of the LEDs does not light up in response to activation of the test LED button, then the user will know that the LED and/or the logic and circuitry associated therewith, needs to be repaired or replaced. The annunciator control panel provides for enhanced local monitoring and control of the gas delivery system and may be necessary to comply with local safety regulations and requirements.
Like ACP test LED button signal 748, alarm reset button signal 750 is also a digital signal provided by the annunciator control panel. In particular, the annunciator control panel includes an alarm reset button, which, when activated by a user, generates signal 750. Upon receipt of signal 750, controller 700 will reset an alarm that was previously activated within the building by controller 700 or some other entity.
EPO status signals 752 are digital signals provided by corresponding emergency power off buttons located at various locations in the building within which the power generation plant is installed. For example, an emergency power off button may be installed in the room within which the gas blower module is installed, in the lobby, and on the rooftop. Each of these emergency power off buttons may be activated by a user in order to shut down the power generation plant. For example, activation of these emergency power off buttons may result in both gas boosters of the gas booster module being shut down and closure of the gas safety valve that controls the flow of natural gas into the gas booster module. Each of signals 752 indicates a state of a corresponding emergency power off button.
Methane detector status signal 754 is a digital signal provided by a device installed in the room within which the gas booster is installed. This device is designed to detect the presence of methane gas, which might indicate a breach in the gas delivery system. Signal 754 indicates whether or not methane has been detected.
Building fire alarm status signal 758 is a digital signal that may be provided from a firm alarm system installed in the building within which the power generation plant is installed. This signal indicates if a fire alarm has been triggered. Controller 700 may be configured to automatically shut down the gas delivery system upon receipt of this signal.
Gas meter number 1 pulses signal 760 and gas meter number 2 pulses signal 762 are digital signals that are provided by respective gas meters in a utility meter rig that is installed between the gas utility service and the gas delivery system (see, e.g., utility meter rig 102 of
Spare digital input signals 764 are digital inputs that are currently unused by controller 700 but have been provided in case the number of digital input signals needs to be expanded at some future time.
The analog output signals generated by controller 700 include a first gas booster (GB1) speed signal 766 (denoted “AO-1”), a second gas booster speed signal 768 (denoted “AO-2”), a bypass modulation signal 770 (denoted “AO-3”), a chilled water (CHW) modulation signal 772 (denoted “AO-4”), and spare analog output signals 774 (denoted “AO-5” and “AO-6”).
GB1 speed signal 766 is an analog output signal that controls the speed of the variable frequency drive associated with the first gas booster of the gas booster module. GB2 speed signal 768 is an analog output signal that controls the speed of the variable frequency drive associated with the second gas booster of the gas booster module. In one implementation, each signal may vary from 0-10 VDC as selectively determined by controller 700. As discussed above, by controlling the speed of the variable frequency drives, controller 700 can modulate the amount of gas that flows through each gas booster of the gas booster module.
Bypass modulation signal 770 is an analog output signal that controls the extent to which a motorized valve, such as motorized valve 276 of
Spare analog output signals 774 are analog outputs that are currently unused by controller 700 but have been provided in case the number of analog output signals needs to be expanded at some future time.
The digital output signals generated by controller 700 include a start/stop first gas booster (GB1) signal 776 (denoted “DO-1”), a start/stop second gas booster (GB2) signal 778 (denoted “DO-2”), an open/close gas safety valve (GSV1) signal 780 (denoted “DO-3”), a start/stop GBM exhaust fan signal 782 (denoted “DO-4”), a start/stop GBM heat rejection signal 784 (denoted “DO-5”), ACP LED signals 786 (denoted “DO-6” through “DO-17”), DDC controls lockout signal 788 (denoted “DO-18”), building fire alarm interconnect signal 790 (denoted “DO-19”), gas blower control panel (GBCP) light signals 792 (denoted “DO-20” through “DO-27”) and spare digital output signals 794 (denoted “DO-28”, “DO-29” and “DO-30”).
Start/stop GB1 signal 776 is a digital output signal that is used to start or stop operation of the first gas booster of the gas booster module. Start/stop GB2 signal 778 is a digital output signal that is used to start or stop operation of the second gas booster of the gas booster module. Open/close GSV1 signal 780 is a digital output signal that is used to open or close the gas safety valve, such as gas safety valve 206 of
ACP LED signals 786 are digital output signals that are used to activate respective LEDs located on an annunciator control panel associated with the control system. As noted above, each of the plurality of LEDs can be selectively activated by controller 700 to indicate the status of a corresponding element of the gas delivery system.
DDC controls lockout signal 788 is a digital output signal of controller 700. When activated, signal 778 triggers a relay that closes the gas safety valve that controls the flow of gas into the gas booster module and places the gas safety valve in a state where it must be manually reset before it can be re-opened.
Building fire alarm interconnect signal 790 is a digital output signal that can be used to provide an indication to the building's fire alarm system that there is a problem with the gas delivery system.
GBCP light signals 792 are digital output signals that are used to control the state of LEDs that are located on the gas booster control panel (see, e.g., control panel 308 of
Spare digital output signals 794 are digital outputs that are currently unused by controller 700 but have been provided in case the number of digital output signals needs to be expanded at some future time.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be understood by those skilled in the relevant art(s) that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. Accordingly, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
