GB2507044A

GB2507044A - Pipeline turbine with pressure and flow control

Info

Publication number: GB2507044A
Application number: GB201218534A
Authority: GB
Inventors: Luke Peter Fenn
Original assignee: MAY GURNEY Ltd
Current assignee: MAY GURNEY Ltd
Priority date: 2012-10-16
Filing date: 2012-10-16
Publication date: 2014-04-23
Also published as: GB201218534D0

Abstract

An electricity generator 10 comprises a pump as turbine 12 located within a mains water supply system. The generator serves the dual function of generating electricity and reducing water pressure. A pressure reducing valve (PRV) 44 maintains the correct flow rate to meet the downstream demand and the appropriate pressure drop across the electricity generator. There may also be a bypass line containing a parallel PRV 16 to allow flow when the required flow rate is outside the operating range of the pump as turbine 12. There may be inlet and outlet pressure transducers 24, 26, and flow meters 30, 32.

Description

Improvements in and relating to Pumps as Turbines

FIELD OF THE INVENTION

The present invention relates to an electricity generator including a pump as turbine within a pressurised fluid supply network and a method of generating electricity using a pump as turbine within a pressurised fluid supply network.

BACKGROUND OF THE INVENTION

Pump as turbines can be used to generate electricity from water pressure. The pump as turbine is effectively a water pump which runs in reverse such that the mechanical energy of the water pressure flowing through the pump as turbine is converted into electric power.

Pumps as turbines can be efficient and cost effective. In particular, mains water supply systems may have excess water pressure which needs to be reduced prior to the downstream supply. If a pump as turbine is used within a mains water supply system, the downstream flow and pressure should be protected and a valving arrangement could be provided around the pump as turbine in the event that the turbine fails.

Within a fluid supply system, the flow through the pump as turbine may vary as the upstream and downstream conditions change and the speed of the pump as turbine will similarly vary depending upon the operating conditions. The pump as turbine may include sophisticated adjustable impellers or a brake system in order to adjust the energy extracted by a pump as turbine and hence produce a required reduction in pressure. These methods may put the pump as turbine or the brake system under significant strains and they may interfere with the reliability of the pump as turbine and the whole fluid delivery network. Accordingly, the efficiency and output of the pump as turbine will be unpredictable and will depend upon the operating conditions. However, such a pump as turbine may function both as a "pressure reducing valve" and also an energy source for a power generator.

It is the aim of the present invention to overcome at least one problem associated with the prior art, whether referred to herein or otherwise.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention that there is provided an electricity generator for use in generating electricity from a fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the control means controls the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.

The fluid may comprise a liquid. Preferably the fluid comprises water and the fluid supply network may comprise a mains water supply network.

Preferably the fluid pressure reducing means is located downstream of the pump as turbine and more preferably is located immediately downstream of the pump as turbine (such that there are no fluid flow effecting components located therebetween).

Preferably the fluid pressure reducing means and the pump as turbine are arranged in series in a first flowline.

The pressure reducing means may comprise a pressure regulating device.

The pressure reducing means may comprise a pressure regulating valve. The pressure regulating device may comprise one or more actuated pilot valves. The or each actuated pilot valve may comprise an electronic actuated pilot valve. The or each actuated pilot valve may comprise a hydraulic actuated pilot valve.

The electricity generator may comprise a valve and preferably a motorised valve located upstream of the pump as turbine (and pressure reducing means) and the motorised valve may be located in the first flowline.

The electricity generator may comprise fluid flow measuring means and preferably comprises a flow meter located downstream of the pump as turbine (and pressure reducing means) and the flow meter may be located in the first flowline. The fluid flow measuring means may be arranged, in use, to measure the fluid flow rate along the first flowline.

The first flow line may comprise an isolation valve located downstream of the pump as turbine. Preferably the isolation valve is located downstream of the flow meter and more preferably is located downstream of all the components in the first flow line. The isolation valve may comprise a manual discharge isolation valve.

Preferably the electricity generator comprises outlet fluid pressure monitoring means which may comprise a fluid pressure transmitter connected to the fluid supply outlet.

Preferably the electricity generator comprises fluid pressure monitoring means which may comprise a fluid pressure transmitter connected to the fluid supply inlet.

The electricity generator may comprise a first fluid flow and a second fluid flow line. Preferably the first fluid flow line is in a parallel arrangement with the second fluid flow line.

The first fluid flow line may comprise a turbine flow line and the second fluid flow line may comprise a by pass flow line.

Preferably the fluid which flows through the first flow line flows through the pump as turbine (and the pressure reducing means) and preferably the fluid which flows through the second flow line does not flow through the pump as turbine (and the pressure reducing means).

The electricity generator may comprise fluid flow rate adjusting means. The fluid flow rate adjusting means may be located in the second flow line.

The fluid flow rate adjusting means may adjust the fluid flow rate through the pump as turbine.

The fluid flow rate adjusting means may comprise a second pressure regulating device.

The electricity generator may comprise a first pressure reducing device in series with the pump as turbine and a second pressure reducing means in parallel with the pump as turbine. Preferably the first pressure reducing means is located in the first flow line and the second pressure reducing means is located in the second flow line.

The electricity generator may comprise a first pressure regulating device in series with the pump as turbine and a second pressure regulating means in parallel with the pump as turbine. Preferably the first pressure regulating means is located in the first flow line and the second pressure regulating means is located in the second flow line.

The second flow line may comprise an inlet isolation valve and preferably comprises a manual inlet isolation valve.

The second flow line may comprise a discharge isolation valve and preferably comprises a manual discharge isolation valve.

Preferably the control means is arranged to increase or decrease the fluid flow rate through the first flow line whilst maintaining a required pressure drop across the electricity generator.

The control means may increase the fluid flow rate through the second flow line in order to decrease the fluid flow rate through the first flow line. The control means may decrease the fluid flow rate through the second flow line in order to increase the fluid flow rate through the first fluid flow line.

Preferably the control means is arranged to increase or decrease the fluid flow rate through the first flow line in order to operate the pump as turbine at a required efficiency and preferably to maintain the efficiency of the pump as turbine above a predetermined level. The control means may optimise the fluid flow rate through the pump as turbine to maximise the efficiency of the pump as turbine.

Preferably the electricity generator includes an inlet manifold in which the fluid inlet splits into a first fiowline and a second flowline.

Preferably the electricity generator includes an outlet manifold in which a first flowline and a second flowline merge into the fluid outlet.

Preferably the control means controls the proportion of fluid pressure dropped across the pump as turbine and the proportion of fluid pressure dropped across the fluid pressure reducing means to maintain the pressure dropped across the pump as turbine within a predetermined range for the fluid flow rate.

Preferably the control means maintains the pressure dropped across the pump as turbine at a set value for the specific fluid tlow rate.

Preferably the control means maintains the pressure dropped across the pump as turbine at a set value which equates to the maximum efficiency value for the pump as turbine for the fluid flow rate.

Preferably the control means is arranged to provide a set flow rate though the generator. Preferably the control means is arranged to provide a set flow rate though the generator and the control means is arranged to control a pressure reducing valve incorporating a solenoid. Preferably the control means enables a set point flow rate to be achieved.

Preferably the pump as turbine includes a fixed speed drive or a constant speed drive.

The pump as turbine may include a variable speed drive.

The pump as turbine may include a soft starter.

The pump as turbine may include a star delta (motor starter).

The pump as turbine may comprise a direct on line starter.

The pump as turbine may comprise a soft starter (or a star delta motor starter) working in conjunction with a direct on line starter.

The pump as turbine may be started using resistive starting.

Preferably, as the measured outlet fluid pressure drops below a predetermined minimum value, the control means increases the fluid flow rate through the electricity generator.

Preferably, as the measured outlet fluid pressure rises above a predetermined maximum value, the control means decreases the fluid flow rate through the electricity generator.

Preferably the fluid pressure reducing means is arranged in series with the pump as turbine.

The fluid pressure reducing means may be arranged in parallel with the pump as turbine.

Preferably the electricity generator is the sole means for reducing and/or regulating and/or controlling the downstream fluid pressure.

Preferably the electricity generator is the sole means for reducing and/or regulating and/or controlling the pressure drop between the fluid inlet and the fluid supply outlet.

Preferably the electricity generator is the sole means for reducing and/or regulating and/or controlling the pressure drop in the fluid supply network.

Preferably the electricity generator functions as the pressure reducing valve in the fluid supply network and more preferably function as the sole pressure reducing valve.

Preferably the control means regulates the proportion of fluid pressure dropped across the pump as turbine and the proportion of fluid pressure dropped across the fluid pressure reducing means such that the overall pressure dropped across the electricity generator remains stable (or is stable) for varying fluid flow rates through the electricity generator.

Preferably the control means regulates the proportion of fluid pressure dropped across the pump as turbine and the proportion of fluid pressure dropped across the fluid pressure reducing means such that the overall pressure dropped across the electricity generator remains stable (or is stable) for varying fluid flow rates through the electricity generator and maintains the downstream fluid pressure at a

stable level.

According to a second aspect of the present invention that there is provided an assembly comprising a fluid delivery network and an electricity generator for use in generating electricity from the fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the control means controls the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.

According to a third aspect of the present invention that there is provided a method of reducing pressure in a fluid delivery network comprising locating an electricity generator in the fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the method comprises controlling the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.

Preferably the method comprises replacing a pressure reducing valve in the fluid delivery network for an electricity generator wherein the electricity generator is in accordance with the first aspect of the present invention.

According to a fourth aspect of the present invention that there is provided a method of generating electricity from a fluid delivery network comprising locating an electricity generator in the fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the method comprises controlling the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, with reference to the drawings that follow, in which: Figure 1 is a piping and instrumentation diagram of a preferred embodiment of an electricity generator in accordance with the present invention.

Figure 2 is a piping and instrumentation diagram of a second embodiment of an electricity generator in accordance with the present invention.

Figure 3 is a piping and instrumentation diagram of an alternative second embodiment of an electricity generator in accordance with the present invention including a motorised valve but without flow meters.

Figure 4 is a piping instrumentation diagram of a further second embodiment of an electricity generator in accordance with the present invention including flow meters but without a motorised valve.

Figure 5 is a piping and instrumentation diagram of another second embodiment of an electricity generator in accordance with the present invention without flow meters and without a motorised valve.

Figure 6 is a piping and instrumentation diagram of a third embodiment of an electricity generator in accordance with the present invention.

Figure 7 is a piping and instrumentation diagram of an alternative third embodiment of an electricity generator in accordance with the present invention without flow meters but including a motorised valve.

Figure 8 is a piping and instrumentation diagram of a further third embodiment of an electricity generator in accordance with the present invention including flow meters but without a motorised valve.

Figure 9 is a piping and instrumentation diagram of another third embodiment of an electricity generator in accordance with the present invention without flow meters and without a motorised valve.

Figure 10 is a piping and instrumentation diagram of a fourth embodiment of an electricity generator in accordance with the present invention.

Figure 11 is a piping and instrumentation diagram of a fifth embodiment of an electricity generator in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in Figure 1, the preferred embodiment of an electricity generator 10 comprises a pump as turbine 12 located within a mains water supply system. The present invention seeks to utilise the energy generated from reducing the water pressure in a mains water distribution network. Accordingly, the present invention provides a dual function in that it provides a pressure reduction in the water supply whilst also efficiently generating electric power.

Whilst the preferred embodiments will be described with reference to a mains water supply it is appreciate that the present invention may be used with other fluids (preferably incompressible fluids) and could be used with a gas.

The preferred embodiment of the present invention includes a pump as turbine 12 located within a water flow path whilst water pressure control means are arranged to maintain the water flow through the pump as turbine 12 in accordance with maximum efficiency conditions for the pump as turbine 12. In some embodiments, the pump as turbine 12 therefore runs at the best efficiency point within its duty curve. For a specific flow rate, the pump as turbine 12 has an optimum pressure drop which will keep the pump as turbine 12 running at maximum efficiency.

The essential principle behind the present invention is that the flow rate through the electricity generator will be dictated by the operating conditions, i.e. the upstream water pressure will be set and the downstream demand will be set by user requirements. This user demand will change the downstream pressure such that an increase in demand will reduce the downstream pressure. The present invention will then seek to increase this downstream pressure by increasing the flow rate through the electricity generator. In other words, a greater downstream demand will decrease the downstream pressure since the flow rate through the electricity generator is set and this flow rate is not sufficient to supply the increased demand so it has decreased the downstream pressure. The control means of the electricity generator then seeks to increase the flow rate through the electricity generator in order to restore the downstream pressure. Accordingly, the control means opens the pressure reducing means in order to increase the flow therethrough. However, this increased flow through the electricity generator thereby increases the flow through the pump as turbine which results in the pressure drop across the pump as turbine increasing. Accordingly, the control means compensates for the increased pressure drop across the pump as turbine by adjusting the corresponding pressure drop across the pressure reducing means.

A pump as turbine generally has a set pressure drop for a given flow rate so the control means aims to set the remaining required pressure drop across the pump reducing valve for the required flow rate to maintain the correct downstream pressure.

As the control means maintains the correct flow rate to meet the downstream demand, the overall pressure drop across the electricity generator will vary and the flow rate through the electricity generator will vary depending on this downstream demand. The control means splits the proportion of pressure drop across the pump as turbine and the proportion of pressure drop across the pressure reducing means in order to provide the correct flow rate.

The water pressure control means may comprise a water pressure regulating device which may be arranged in parallel with the pump as turbine 12 or may be arranged in series with the pump as turbine 12. The aim of the water pressure regulating device is to maintain the water pressure and the water flow rate through the pump as turbine 12 within a set predetermined range such that the pump as turbine 12 operates at a fixed speed and there is no requirement for a variable speed drive mechanism. The present invention provides electric power which can be electrically connected to a distribution grid via a direct line. In one embodiment, a variable speed drive mechanism may be used, for example with relatively large pumps as turbines and this mechanism is to facilitate the grid connection and the pumps as turbines would still be operated at a tixed speed.

The valving system and the water pressure control means would also provide a protection function. The valve operation would enable the pump as turbine to be bypassed and to provide a continual downstream flow and pressure protection.

The pump as turbine 12 is installed in-line of a distribution network and operates at a fixed speed. The valving around the complete set up allows the entire system to mimic a pressure reducing valve.

As shown in Figure 1, the electricity generator 10 includes a water inlet pipe 20 which is upstream and is arranged to supply mains water through the mains water distribution network. The electricity generator 10 includes a water outlet 22 which is downstream and supplies the water flow towards the end user.

In the preferred embodiment, the electricity generator 10 includes a pump as turbine 12 located in a turbine line together with a pressure reducing device 17 and a turbine bypass line 51 which is in parallel with the turbine line 50 and includes a pressure reducing device 16. In particular, the pressure reducing device 16 comprises a solenoid controlled pressure reducing valve 16. As previously mentioned, the electricity generator 10 also includes a second pressure reducing valve 17 with solenoid control which is arranged in series with the pump as turbine 12.

The electricity generator 10 includes an upstream pressure transmitter connected to the water inlet 20. Similarly, the electricity generator 10 includes a downstream pressure transmitter connected to the water outlet 22. Accordingly, the control means 14 monitors both the inlet water pressure and the outlet water pressure for the electricity generator 10. One aim of the control means is to maintain the downstream water pressure as measured by the downstream pressure transmitter 26.

The electricity generator 10 primarily uses the pressure reduction created by the pump as turbine 12 to maintain the downstream pressure at the desired level.

However, for greater pressure reductions the control means 14 will use the water pressure control means to supplement the pressure reduction. Alternatively, if the pressure reduction falls below a particular value at which the pump as turbine 12 would not be effective for being connected to an electricity supply network (e.g. the National Grid at 50Hz), then the pump as turbine 12 may be bypassed and the water pressure control means will solely provide the required pressure reduction.

Overall, the control means 14 monitors the required pressure reduction and the downstream pressure reading whilst maintaining the water flow speed through the pump as turbine 12 within the operating range of the pump as turbine 12.

The following explanation of the preferred embodiment shown in Figure 1 provides a specific example in which the pressures quoted are nominal values, as is the pump as turbine range.

In this example, the system is assumed to have a delivery pressure requirement at the site of 40m. This pressure is required to maintain adequate pressure in all parts of the supply system downstream of the site, at all flows.

The system is assumed to have a flow range from 601/s to 2001/s, with an average flow of 1301/s. The maximum flow through the pump as turbine 12 is 1501/s. The assumed inlet pressure is 150m head.

The specific arrangement shown in Figure 1 consists of an inlet system, an outlet system, a turbine system and a turbine bypass system.

The inlet system consists of the following equipment: a manual inlet isolation valve 40; an inlet pressure transducer 24 connected to the inlet pipe 20 through an isolation valve 25; and an inlet manifold 42, connected to a turbine line 50 and a turbine bypass lines 51.

The turbine system consists of the following equipment a turbine actuated inlet isolation valve 44; a pump as turbine 12; a solenoid controlled pressure reducing valve (PRV) 17; a flow meter 32 (e.g. a MagFlow meter); and a manual discharge isolation valve 46.

The turbine bypass system consists of the following equipment: a manual bypass line inlet isolation valve 60; a solenoid controlled PRV 16; a flow meter 30 (e.g. a MagFlow meter); and a manual discharge isolation valve 62.

The outlet system consists of the following equipment: an outlet manifold 64; a downstream pressure transducer 26 connected to the outlet pipe 22 through an isolation valve 27; and a manual outlet isolation valve 48.

The overall system is monitored and controlled by control means including a control panel 70.

In this specific example, the system 10 is designed to maintain 40m head of water pressure as measured by the downstream pressure transducer 26. The control means will undertake primary control, but the PRVs 16, 17 have piloted backup pressure control which will act as a back up and ensure the downstream pressure never raises above 50m head.

The bypass PVR 16 could be held in a fixed position slightly open (off its seat but only passing a small flow) (or driven to a fully closed position) if flows as measured on the turbine flow meter 32 are within the operating range of the pump as turbine 12 (e.g. between 801/s and 1501/s for this example). This flow through the bypass PVR 16 may be deemed to waste some of the available energy but it provides a safety mechanism for emergencies.

For all flows within the pump as turbine 12 operating range, the pump as turbine 12 and its associated PRV 17 control the downstream pressure.

For flows above the operating range of the pump as turbine 12, the turbine PRV 17 will remain open at a pre-set position and for flows below the turbine operating range the pump as turbine PRV 17 will close. For flows above and below the pump as turbine operating range, the bypass PRV 16 will take over the pressure control.

When the pump as turbine 12 and its associated PRV 17 are controlling flow, the PRV 17 will be controlled using a nudge and wait" system, with the wait time sufficient to allow the system to stabilise. An example of a control sequence has will be described shortly.

If the pump as turbine 12 is taken off line for any reason, the inlet actuated valve 44 and the downstream PRV 17 will both close. The flow control will transfer to the bypass PRV 16 with all flows passing through the bypass.

An example of a control sequence will now be provided with reference to the specific example shown in Figure 1.

In normal operation, stable conditions exist with flow of 1001/s through the pump as turbine 12 and 101/s through the bypass system. The inlet pressure as measured by the upstream pressure transducer 24 is 150m head and the outlet pressure as measured by the downstream pressure transducer 26 is 40m head. There is a 60m head drop across the pump as turbine 12 and 50m head dropped across the pump as turbine PRV 17. This thereby provides an overall pressure drop of 11 Om head.

If the downstream demand starts and increases then the downstream pressure may starts to drop. In this situation, the PRV 17 will be nudged open reducing pressure drop across it and the water flow will increase. This will cause the pressure drop across pump as turbine 12 to rise as the flow increases, resulting in the same overall pressure drop but at a higher flow. After a wait period, if the downstream pressure is still low this process will be repeated. If after the wait period the downstream pressure is above the set point the PRV 17 will be nudged closed.

For a flow of 1101/s though the pump as turbine 12, the pressure drops would be 65m across pump as turbine 12 and 45m across the PRV 17.

For a flow of 1301/s though the pump as turbine 12, the pressure drops would be 70m across turbine and 40m across the PRV17.

For a flow of 1501/s though the pump as turbine 12, the pressure drops would be lOOm across turbine and lOm across the PRV 17.

If demand starts to drop the reverse of the above process will occur. The deceased demand will cause an increase in the downstream pressure which can be reduced by the system. In particular, in this situation, the PRV 17 will be nudged closed increasing the pressure drop across it and the water flow will decrease. This will cause the pressure drop across pump as turbine 12 to decrease as the flow decreases, resulting in the same overall pressure drop but at a lower flow rate. After a wait period, if the downstream pressure is still high this process will be repeated. If after the wait period the downstream pressure is below the set point then the PRV 17 will be nudged open.

If at any particular time, the pump as turbine 12 is passing 1501/s and demand continues to rise, the bypass PRV 16 will be nudged open, reducing pressure drop across it to increase the flow. After the wait period if the downstream pressure is still low this process will be repeated. If after the wait period the downstream pressure is above the set point the bypass PRV will be nudged closed.

Accordingly, as can be seen, the system includes control means 14 which maintains the required downstream water pressure whilst maintaining the flow rate through the pump as turbine 12 within a preferred operating range. This is achieved by the control means 14 controlling a water flow regulating system which simultaneously increases or decreases the downstream water pressure towards the required amount whilst maintaining the water flow rate through the pump as turbine 12 within a desired range.

It is also possible for the control means 14 to increase the operating efficiency of the pump as turbine 12. In particular, a pump as turbine 12 will have an optimum efficiency at a particular flow rate. As described above, the flow rate through the pump as turbine 12 may be set by the downstream demand. However, the control means 14 can also control the flow through the bypass line 51 using the pressure regulating device 16. In particular, it the control means 14 increases the flow rate through the bypass line 51 then the flow rate through the turbine line 50 can be reduced (by the pressure regulating device 17). This means that the control means 14 can effectively select the flow rate through the pump as turbine 12 and, more specifically, can select a flow rate which enables the pump as turbine 12 to be operating at an optimum efficiency or within an efficient range. Overall, the use of the bypass line 51 incorporating a pressure regulating device 16 enables the control means 14 to set the flow rate through the pump as turbine 12 independent of the required demand. Some embodiments of the present invention (see Figure and Figure 11) do not have a bypass line 51 and, therefore, do not have the functionality for the flow rate though the pump as turbine 12 to be controlled in this manner.

The use of the bypass line 51 also allows flows below and above the range that the pump as turbine can handle. The electricity generator can then still reliably supply the mains water network.

The actuated valves associated with the respective pressure regulating devices 16, 17 may be directly linked and in communication or may be linked and in communication through the control means 14 such that the setting on one PRV 16, 17 directly or indirectly influences the setting of the other FRV 16, 17.

The electricity generator 10 also includes flow meters 30, 32 which enable the unit to control flow to a given set point. Accordingly, rather than demand and overall system pressure determining the flow, the system can be changed to control the flow rate. This is important addition as it covers a different field of operation and has many applications. This is achieved by using the pump as turbine PRV 17 to control the flow rate through the generator 10 to ensure that the set point flow is achieved. To achieve this, the FRV 17 includes an added solenoid valve to allow it to be driven by the control system.

-20 -A second embodiment of an electricity generator 10 in accordance with the present invention is shown in Figure 2. The specific arrangement shown in Figure 2 consists essentially of the previously described components. Again, the arrangement includes an inlet system, an outlet system, a turbine system and a turbine bypass system.

The inlet system consists of a manual inlet isolation valve 40, an inlet pressure transducer 24 connected to the inlet pipe 20 through an isolation valve 25 and an inlet manifold 42, connected to a turbine line 50 and a turbine bypass lines 51.

The turbine system consists of a turbine actuated inlet isolation valve 44, a pump as turbine 12, a solenoid controlled pressure reducing valve (PRV) 17 including a pressure regulating valve 82, a flow meter 32 (e.g. a MagElow meter) and a manual discharge isolation valve 46.

The turbine bypass system consists of a manual bypass line inlet isolation valve 60, a solenoid controlled PRV 16 including a pressure regulating valve 80, a flow meter 30 (e.g. a MagFlow meter), and a manual discharge isolation valve 62.

The outlet system consists of an outlet manifold 64, a downstream pressure transducer 26 connected to the outlet pipe 22 through an isolation valve 27 and a manual outlet isolation valve 48.

As above, the overall system is monitored and controlled by control means 14 including a control panel 70.

Again, this embodiment enables the flow rate of the fluid through the pump as turbine 12 to be controlled and to be largely independent of the downstream demand.

-21 -Accordingly, the second embodiment essentially includes the same components as the first embodiment but also includes pressure regulating valves 80, 82 on the pressure reducing valves 16, 17.

In an alternative version of the second embodiment, as shown in Figure 3, the electricity generator 10 does not include any flow meters 30, 32. The control means is still able to efficiently control the system through the readings provided by the upstream pressure transmitter 24 and the downstream pressure transmitter 26.

In a further version of the second embodiment, as shown in Figure 4, the electricity generator 10 does not include the motorised turbine actuated inlet isolation valve 44. This further version does include the flow meters 30, 32 In another version of the second embodiment, as shown in Figure 5, the electricity generator 10 does not include the flow meters 30, 32 or the motorised turbine actuated inlet isolation valve 44.

A third embodiment of an electricity generator 10 in accordance with the present invention is shown in Figure 6. The specific arrangement shown in Figure 2 consists essentially of the previously described components. Again, the arrangement includes an inlet system, an outlet system, a turbine system and a turbine bypass system.

The turbine system consists of a turbine actuated inlet isolation valve 44, a pump as turbine 12, a pressure regulating device 91, a flow meter 32 (e.g. a MagFlow meter) and a manual discharge isolation valve 46.

-22 -The turbine bypass system consists of a manual bypass line inlet isolation valve 60, a pressure regulating device 90, a flow meter 30 (e.g. a MagFlow meter), and a manual discharge isolation valve 62.

Accordingly, the third embodiment essentially includes the same components as the first embodiment but includes pressure regulating devices 90, 91 rather than pressure reducing valves 16, 17. The pressure regulating devices 90, 91 may be directly linked to each other. For example, the pressure regulating devices 90, 91 may be physically linked to each other and may be electronically or hydraulically connected.

In an alternative version of the second embodiment, as shown in Figure 7, the electricity generator 10 does not include any flow meters 30, 32. The control means is still able to efficiently control the system through the readings provided by the upstream pressure transmitter 24 and the downstream pressure transmitter 26.

In a further version of the second embodiment, as shown in Figure 8, the electricity generator 10 does not include the motorised turbine actuated inlet isolation valve 44. This further version does include the flow meters 30, 32 In another version of the second embodiment, as shown in Figure 9, the electricity generator 10 does not include the flow meters 30, 32 or the motorised turbine actuated inlet isolation valve 44 -23 -A fourth embodiment of an electricity generator 10 in accordance with the present invention is shown in Figure 10. This fourth embodiment primarily concerns a series arrangement rather than the previously described parallel arrangements.

The specific arrangement shown in Figure 10 includes an inlet system, an outlet system and a turbine system but does not include a turbine bypass system.

The inlet system consists of a manual inlet isolation valve 40 and an inlet pressure transducer 24 connected to the inlet pipe 20 through an isolation valve 25.

The outlet system consists of a downstream pressure transducer 26 connected to the outlet pipe 22 through an isolation valve 27 and a manual outlet isolation valve 48.

As above, the overall system is monitored and controlled by control means 14 including a control panel 70. This embodiment does not include a bypass line and a set forward pressure/flow is given.

A fifth embodiment of an electricity generator 10 in accordance with the present invention is shown in Figure 11. This fifth embodiment is essentially an alternative of the fourth embodiment and, again, concerns a series arrangement without a bypass line.

The specific arrangement shown in Figure 11 includes an inlet system, an outlet system and a turbine system but does not include a turbine bypass system.

-24 -The inlet system consists of a manual inlet isolation valve 40 and an inlet pressure transducer 24 connected to the inlet pipe 20 through an isolation valve 25.

The turbine system consists of a turbine actuated inlet isolation valve 44, a pump as turbine 12, a pressure regulating device 91, a flow meter 32 (e.g. a MagElow meter) and a manual discharge isolation valve 46.

As above, the overall system is monitored and controlled by control means 14 including a control panel 70. This embodiment does not include a bypass line and a set forward pressure/tlow is given.

As discussed, the present invention allows the pump as turbine 12 to be installed in-line within a water main. The additional valving around the unit allows the product to mimic the same operation downstream of the installation as a standard water industry pressure reducing valve (PRy).

Accordingly, the present invention provides a pump as turbine solution which can enable power generation at a fixed best efficiency point within the duty curve of the pump as turbine, with the surrounding PRV's and Gate Valves operating to control the pressure and flow downstream of the unit as previously described.

The pressure reducing valves around the pump as turbine 12 are utilised to mimic the action of a pressure reducing valve (PRV) within a water distribution network to enable accurate pressure control downstream of the installation point and for power to be generated from the pump as turbine.

The PRV valving solution around the pump as turbine 12 provides a set pressure and flow across the pump as turbine unit, which then enables the pump as turbine -25 - 12 to operate at its most efficient point along its power generation curve, as well within a set speed to enable the unit to connected by either Direct on Line (DOL) or via a Variable Speed Drive (VSD) method to provide a 50Hz connection to the National grid.

The use of a VSD or Soft Start (or star delta motor starter) may be used in some installations to enable the electricity generator 10 to be connected to the National Grid when the energy generated by the electricity generator 10 is over a set kW rating to facilitate smooth electrical grid connection.

The package design solution for the electricity generator 10 may use two PRy's one placed downstream of the pump as turbine 12 to control the set flows and pressures through the pump as turbine 12 and one which will be installed within a bypass leg around the pump as turbine 12 which will operate to send higher (or lower flows should the turbine not be connected to the grid) around the pump as turbine 12 into the distribution network. At higher flows this will result in the pump as turbine 12 staying in operation at its optimum point on the curve and allow the overall package solution to mimic the operation of a standard PRV.

The bypass PRV will also act as an emergency bypass surge protection valve should a G59 grid connection be called for. Should the turbine go off line or lose grid connection then the turbine will go into free-spin while the downstream PRV operates to close the flows down through the pump as turbine 12, with the bypass PRV operating to open and send flows through the bypass. At all times the downstream pressure will be protected to its commissioned set points.

The present invention enables power to be generated by a standard fixed speed (50 Hz) pump as turbine, while still providing downstream pressure and flow regulation within the distribution network. This results in the electricity generator 10 capturing existing embedded energy from the water distribution networks and exporting the energy to the National Grid.

-26 -The present invention utilises a pump which is run in reverse at a set point along its reversed pump curve to generate electrically, the system is designed to run at its most optimum range along this reversed generation curve.

The electricity generator 10 is designed for all forms of distribution networks for both in-line and end of line solutions which require accurate pressure / flow control at the downstream point.

The present invention may use one of a variety of suitable the different starting techniques which may be of particular benefit when connecting the pump as turbine 12 to the mains grid. The present invention can connect to the grid and reduce G59 trips and smooth starting techniques. In particular, the electricity generator 10 may use direct on line, variable speed drive, soft start (star delta motor starter) drive working in conjunction with the direct on line starting method, or finally resistive starting.

Claims

-27 -CLAIMS1. An electricity generator for use in generating electricity from a fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the control means controls the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.
2. An electricity generator for use in generating electricity from a fluid supply network according to Claim 1 in which the fluid comprises water and the fluid supply network comprises a mains water supply network.
3. An electricity generator for use in generating electricity from a fluid supply network according to Claim 1 or Claim 2 in which the fluid pressure reducing means is located immediately downstream of the pump as turbine.
4. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the fluid pressure reducing means and the pump as turbine are arranged in series in a first flowline.
5. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the pressure reducing means comprises a pressure regulating device.

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6. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator comprises a motorised valve located upstream of the pump as turbine and pressure reducing means and the motorised valve is located in the first flowline.
7. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator comprises fluid flow measuring means located downstream of the pump as turbine and pressure reducing means and the flow meter is located in the first fiowline.
8. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the first flow line comprises an isolation valve located downstream of the pump as turbine.
9. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator comprises outlet fluid pressure monitoring means which comprises a fluid pressure transmitter connected to the fluid supply outlet.
10. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator comprises inlet fluid pressure monitoring means which comprises a fluid pressure transmitter connected to the fluid supply inlet.
11. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator comprises a first fluid flow and a second fluid flow line.
12. An electricity generator for use in generating electricity from a fluid supply network according to Claim 11 in which the first fluid flow line is in a parallel arrangement with the second fluid flow line.

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13. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the fluid which flows through the first flow line flows through the pump as turbine and the pressure reducing means and the fluid which flows through the second flow line does not flow through the pump as turbine and the pressure reducing means.
14. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator may comprise fluid flow rate adjusting means.
15. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the fluid flow rate adjusting means is located in the second flow line.
16. An electricity generator for use in generating electricity from a fluid supply network according to Claim 14 or Claim 15 in which the fluid flow rate adjusting means adjusts the fluid flow rate through the pump as turbine.
17. An electricity generator for use in generating electricity from a fluid supply network according to any one of Claim 14 to Claim 16 in which the fluid flow rate adjusting means comprises a second pressure regulating device.
18. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the electricity generator comprises a first pressure reducing device in series with the pump as turbine and a second pressure reducing means in parallel with the pump as turbine.
19. An electricity generator for use in generating electricity from a fluid supply network according to Claim 18 in which the first pressure reducing means is located in a first flow line and the second pressure reducing means is located in a second flow line.

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20. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the second flow line comprises an inlet isolation valve.
21. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the second flow line comprises a discharge isolation valve.
22. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means is arranged to increase or decrease the fluid flow rate through the first flow line whilst maintaining a required pressure drop across the electricity generator.
23. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means increases the fluid flow rate through the second flow line in order to decrease the fluid flow rate through the first flow line and the control means decreases the fluid flow rate through the second flow line in order to increase the fluid flow rate through the first fluid flow line.
24. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means is arranged to increase or decrease the fluid flow rate through the first flow line in order to operate the pump as turbine at a required efficiency.
25. An electricity generator for use in generating electricity from a fluid supply network according to Claim 24 in which the control means optimises the fluid flow rate through the pump as turbine to maximise the efficiency of the pump as turbine.
26. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means controls the -31 -proportion of fluid pressure dropped across the pump as turbine and the proportion of fluid pressure dropped across the fluid pressure reducing means to maintain the pressure dropped across the pump as turbine within a predetermined range for the fluid flow rate.
27. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means maintains the pressure dropped across the pump as turbine at a set value which equates to the maximum efficiency value for the pump as turbine for the fluid flow rate.
28. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means is arranged to provide a set flow rate though the generator.
29. An electricity generator for use in generating electricity from a fluid supply network according to Claim 28 in which the control means is arranged to provide a set flow rate though the generator and the control means is arranged to control a pressure reducing valve incorporating a solenoid.
30. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the pump as turbine includes a fixed speed drive.
31. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which, as the measured outlet fluid pressure drops below a predetermined minimum value, the control means increases the fluid flow rate through the electricity generator.
32. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which, as the measured outlet fluid pressure rises above a predetermined maximum value, the control means decreases the fluid flow rate through the electricity generator.

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33. An electricity generator tor use in generating electricity from a fluid supply network according to any preceding claim in which the control means regulates the proportion of fluid pressure dropped across the pump as turbine and the proportion of fluid pressure dropped across the fluid pressure reducing means such that the overall pressure dropped across the electricity generator remains stable (or constant) for varying fluid flow rates through the electricity generator.
34. An electricity generator for use in generating electricity from a fluid supply network according to any preceding claim in which the control means regulates the proportion of fluid pressure dropped across the pump as turbine and the proportion of fluid pressure dropped across the fluid pressure reducing means such that the overall pressure dropped across the electricity generator remains stable (or constant) tor varying fluid flow rates through the electricity generator and maintains the downstream fluid pressure at a stable level.
35. An assembly comprising a fluid delivery network and an electricity generator for use in generating electricity from the fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the control means controls the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.
36. A method of reducing pressure in a fluid delivery network comprising -33 -locating an electricity generator in the fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the method comprises controlling the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.
37. A method of generating electricity from a fluid delivery network comprising locating an electricity generator in the fluid supply network, the electricity generator comprising: a pump as turbine; fluid pressure reducing means; a fluid inlet for connection to a fluid supply; a downstream fluid supply outlet; control means for controlling the fluid flowing through the pump as turbine and the fluid pressure reducing means; wherein the electricity generator provides a fluid pressure drop between the fluid inlet and the fluid outlet; and wherein the method comprises controlling the fluid pressure dropped across the fluid pressure reducing means to control the fluid flow rate through the electricity generator in order to control the pressure dropped across the electricity generator.
38. An electricity generator for use in generating electricity from a fluid supply -34 -network substantially as herein described, with reference to, and as shown in, any of the accompanying Figures.
39. An assembly comprising a fluid delivery network and an electricity generator for use in generating electricity from the fluid supply network substantially as herein described, with reference to, and as shown in, any of the accompanying Figures.
40. A method of reducing pressure in a fluid delivery network substantially as herein described, with reference to, and as shown in, any of the accompanying Figures.
41. A method of generating electricity from a fluid delivery network substantially as herein described, with reference to, and as shown in, any of the accompanying Figures.