Detail of travelling screen installation at Clifton Maybank.

The maximum abstraction flow rate at Clifton Maybank being 0.104 m3/sec. , with a required screen mesh size of 3mm, and a maximum approach velocity requirement of 0.25 m/s would normally be a relatively simple solution, but with a non-standard shape inlet structure for a mechanical screen and low water levels would prove to be more of a challenge.

Existing non-standard inlet on site.

Design of new travelling screen

The inlet chamber at Clifton Maybank did not lend itself to the fitting of a mechanical screen due to its angled walls, with internal penstock and overhead power lines, ruling out the use of a crane for installation.

The standard GoFlo screen design incorporates a pivoting guide frame to simplify installation into the channel: This could not be used at this location due to height restrictions, so a lifting frame and guide rail system was designed to facilitate the installation and removal from the channel without the need of a crane.

Section showing screen in chamber.

Section showing screen lifted out of chamber.

3D model of complete installation.

Installation

Screen guide frame in position.
Note white rollers at the top: These allow the screen to pivot smoothly from horizontal to installed position and vice versa.

GoFlo travelling screen showing white rollers.

Left side of screen: Filler plate between edge of screen guide frame and wall had to be contoured to fit.

Right side of screen: Two-part filler plates needed to follow the penstock steelwork with less than 3 mm gap (although most of the panels fitted with less than 2 mm!)

No crane required! A porta-gantry was used to raise one end of the screen  off the trailer so it could be lowered onto the first set of rollers. With the screen resting on the rollers, the porta-gantry could be disconnected and relocated at the other end of the screen, lifted and moved forward until the whole screen was resting on the rollers.

Travelling screen showing crane used for installation.

Pivot blocks are bolted into position.

Lifting and pivoting the screen.

Travelling screen in its operating position.

Travelling screen detail.

Completed screen and debris trough. The trough incorporates a removable centre section to allow the screen to be lifted out the chamber with minimum disassembly.

The post Clifton Maybank – Wessex Water appeared first on Goflo.

The Why

Springfield Surface Water Abstraction (SWA) is situated on the banks of the river Medway in Maidstone, Kent and moves water to Eccles Lake.

With new Eel regulations coming into effect across the country, Springfield had to upgrade its water intake systems to be compliant.

Juvenile ‘Glass Eels’ were at risk of entering the system which prevented them from moving upstream and completing their complex lifecycle. Before the GoFlo screens were installed, it had a timber fender and coarse bar screens to protect the pumps from large debris meaning smaller debris could still enter and eels could still get through.

This is when GoFlo were bought in to install a state-of-the-art water intake screen to combat all of the above issues.

Springfield Surface Water Abstraction's GoFlo Intake screen

GoFlo 3D CAD model of the proposed screens, Intake Box and Walkways

The Numbers

GoFlo had a bit of a challenge when it came to this site; it is in constant use 24/7 and the pumping station could not be turned off for more than 8 hours because this would impact on the operation of the water treatment works that the river supplies.

In addition to this, the site could not be de-watered meaning it would take a technical team of divers to install in water that is 4.5 metres deep.

The post Springfield Case Study appeared first on Goflo.

Intake location (under water) with surrounding timber fender

The picture above is before any works started. There are two coarse bar screens, one in front of each opening and a fixed timber boom in the river in front of the intake to deflect large debris. The flow travels approximately 25 metres by gravity into the pump house building, then is pumped to Eccles Lake and from there under gravity to Burham Water Supply Works.

To comply with The Eel Regulations, Southern Water had to upgrade the intake so that the maximum bar-spacing on the intake was 2 mm and the velocity of the water approaching the screen did not exceed 0.25 m/s. This is to prevent juvenile ‘glass eels’ from being sucked into the intake which would prevent them from moving upstream into the Medway catchment and beginning the long and complex life cycle of the European eel. The 0.25 m/s approach velocity could be achieved by using only half of the existing intake, with the other half blocked up using a concrete stop-log.

GoFlo Screens were awarded the contract to supply and assist with the installation of the eel screens at this location, by Trant / BTU Utilities Ltd.

The site is particularly complicated because it is in use 24/7, and cannot be turned off for more than a day or two before disruption to Burham Water Supply Works would occur. Coupled with this, the site cannot be de-watered, so would have to be installed by divers in water that is 4.5 metres deep, with very low underwater visibility. The new GoFlo screens are too large to fit inside the existing concrete structure, so had to be accommodated outside of the existing concrete structure, in a prefabricated stainless steel ‘intake box’ that sits on the existing underwater concrete apron.

GoFlo designed and manufactured the GoFlo screens, intake box, walkways and debris trough. Everything had to be designed to be simple and modular so that the underwater elements could be installed by divers. The elements supplied by GoFlo are shown below along with the basic specification:

• Screen drive: 2.2 kW 3-phase WIMES-spec motor / gearbox
• Maximum bar spacing: 2 mm
• (Single) screen mesh area 4.652 m2
• Angle of inclination (from horizontal): 72.5°
• Construction material: 304 Stainless Steel

GoFlo 3D CAD model of the proposed screens, Intake Box and Walkways

Proposed Design

The overall design of the system was developed collaboratively between the main contractor (Trant / BTU), the client (Southern Water), Atkins Global who were the M&E designers working for Trant / BTU and GoFlo Screens. GoFlo also worked closely with Commercial and Specialised Diving Ltd to incorporate their ‘diver design friendly’ feedback into the design to make it easier for the divers to install, which was especially important considering it would be installed in the middle of winter.

Some of the debris, including a motorbike, removed from the intake by the divers

Before the detailed design could begin, the intake and apron area in front had to be cleared of silt and debris. Once in the water the divers found a tangled mess of silt, fishing line, a large quantity of steel railing, two motorbikes, a pushbike and various other debris! Once the debris was cleared, a detailed site survey was undertaken to determine how flat the apron was, the exact profile of the vertical concrete piers which the GoFlo intake box would fix onto (a special 5-metre-long profile gauge was manufactured to achieve this), and check how far the apron extended out into the river. A number of differences were found between the original construction drawings from the 1960’s and what was actually built. Following the site survey, a detailed 3D model of the intake was constructed in Inventor software which formed the basis of the GoFlo design.

The principle of the GoFlo design was a modular construction, comprising of:

• A Fixing Frame that fixed to the concrete structure and was used as a template for drilling the fixing holes.
• A sacrificial ‘measuring frame’ which bolted to the Fixing frame to allow all of the key levels to be measured (hence adjusted) from above-water.
• 2 x Intake Box sides which bolted to the Fixing Frame (assembled above-water, after the Fixing Frame fixing holes had been drilled and the Fixing frame removed).
• The standard GoFlo Baseplate and Pivoting Frame (guide rails), 2 off.
• The standard GoFlo screen(s).
• Course debris screen / walkway that integrated with the Intake box / debris trough and return channel.

The modules were pre-assembled in our workshop to ensure that everything fitted together, prior to arrival on-site. The individual items, and the complete assembly are shown below.

The Fixing Frame

The Measuring Frame, which was temporary and fixed to the Fixing Frame

An Intake Box side (two required)

Baseplate and Pivoting Frame

Course debris screen

The walkway assemblies

Debris trough and return channel, with covers

The completed design

The whole design was based on simplifying the works on site, particularly in regard to making the works as straightforward as possible for the divers. Key design features include:

a) Two reference brackets installed on the above-water concrete upstand, which provided two precise reference points for the Fixing Frame to locate onto at top end.

Reference brackets fixed to existing concrete structure

Fixing Frame in position against existing structure

b) The Fixing Frame, which once positioned acted as a drilling template for all of the fixings into the concrete structure. At each fixing position there is an 18.5 mm diameter hole, to allow an 18 mm masonry drill bit to pass through which was used as a guide for drilling. These 18 mm diameter holes, once the Fixing frame was removed, had Hilti HKD-SR stainless-steel M16 fixings installed.

c) For precise positional adjustment, the Fixing frame had 2 x M16 height adjusting bolts close to the toe of the intake apron, 2 x M16 stand-off adjusting bolts at the bottom of the vertical and two temporarily-fixed Adjustment Blocks at the bottom of the vertical frame members to allow the frame to be pushed / pulled both laterally and longitudinally, and once in position locked in that position for the fixings to be drilled. These were removed once the Intake box was finally installed.

Close up of the baseplate of the Fixing Frame, showing the leveling bolts

Temporary adjustment blocks used for positioning the Fixing Frame

d) The Fixing Frame was designed to stand-off the concrete by a nominal distance of 20 mm to allow for unevenness in the concrete structure. This gap was taken-up at each fixing point using a stainless-steel shim stack. The height of the required shim stack was measured after the fixings holes had been drilled, but before the Fixing frame was removed so that the shim stacks for each fixing point could be pre-prepared. Fine adjustment was still possible by adding / removing shims later as required.

e) Once the fixing holes had been drilled (see b) above), the Fixing frame was removed, then the Intake Box sides bolted on, the GoFlo Baseplates and Pivoting frames attached. This allowed the whole Intake box to be lifted in as an assembled unit and fixed in place using the pre-prepared fixings and shim stacks. Apart for the minor adjustments to levels, this saved a lot of complex underwater assembly work.

The assembled Intake Box with the GoFlo screen Baseplates and Pivoting Frames installed

f) Once the Intake Box was fixed in position, the Course debris screen and Walkway were fixed onto the Intake box, then the GoFlo Screens were installed.

So, that was the principle – now let’s looks at the actual installation!

Construction

The photos below show the actual parts being installed on site. Bear in mind that the water is 4.5 metres deep, and the GoFlo screen 6.1 metres long. The first photo shows the Fixing Frame lying on its back, having the Measuring Frame bolted to it prior to being lifted in. The second photo shows the assembled Fixing Frame and Measuring Frame being lifted into position. You can see that the river was very high after several days of heavy rain.

Fixing Frame and Measuring Frame being assembled

Fixing Frame and Measuring Frame being lifted into the intake – note the very high water levels!

The Fixing Frame and Measuring Frame in position, ready for the fixing holes to be drilled. The mild steel Measuring Frame was sacrificial, but provided above-water horizontal references for a spirt level, which was essential during levelling.

Once the drilling was completed, the Fixing Frame and Measuring Frame were removed from the water, then the Intake Box Sides, GoFlo screen Baseplates and Pivoting Frames assembled together.

Fixing Frame and Measuring Frame in position

The Intake Box being assembled prior to final installation

The fully assembled Intake Box

Lifting the assembled Intake Box into the intake with a 60-tonne crane

The Intake Box in position and being bolted to the concrete by the divers (which took several days).

The assembled Intake Box attached to the concrete structure.

Next the Course Bar screen was lifted into position, closely followed by the GoFlo Screens. GoFlo Screens are lifted in vertically, and use the Pivoting Frames as guide rails to guide the screen precisely onto the Baseplate.

Lifting the course bar screen into the Intake Box

Lifting the first GoFlo screen into the Intake Box

Starting to look complete with both GoFlo screens installed and the framework for the outer walkway.

Fitting the front part of the walkway structure onto the Intake Box

Then the access ramp for the walkway was installed and the Debris Trough.

Completed walkway structure attached to the Intake Box

The screens are designed to discharge the collected debris into a dedicated trough behind the screens. The trough is made from stainless steel (as are the screens, Intake Box & Course Bar Screen). The trough has a high back to catch the spray (2.5 bar water pressure) that is emitted from the screen spray-bars behind the mesh belt.

Each screen has a spray bar with multiple nozzles fed by a remote water booster pump located inside the main building. Debris on the surface of the screen mesh as it rotates falls off as it runs over the top sprockets, while any remaining ‘sticky’ debris is blasted off by water the jets from the inside of the screen and into the trough.

Fitting the Debris Trough and return channel

The spray boom assembly which fits inside the screen mesh

The Debris Trough includes a dedicated water feed (10 litres / second) to flush collected material back into the river downstream of the screens.

The debris flushing flow pipework underneath the Debris Trough

The green fence posts are to support the security fence to protect the public from the machinery.

Security fencing being fitted

10 cm bar-spaced Course Debris Screen protects the GoFlo screens from large object damage, and keeps swimmers out. Due to the proximity of the screens to the footpath and the possibility of ice formation in winter months, a fully enclosed debris trough was required to confine the spray mist. The covers are hinged to enable full unrestricted access to the trough.

View from the-screens, looking out towards the river

The lids covering the debris trough

Further lids covering the debris return channel

The completed installation, inside the security fencing

The completed installation, looking upstream

Completed installation: Neat and unabtrusive to towpath and river traffic.

The completed installation, also looking upstream

Download case study for the Springfield (Southern Water) GoFlo screen project.

The post Springfield (Southern Water) appeared first on Goflo.

Aerial view of Sandown intake and pump house

Sandown pumping station, looking upstream

Along with many other water intakes throughout the UK, Southern Water had to upgrade the water intake screens to be compliant with the Eel Regulations, which meant a bar-spacing that did not exceed 2 mm and an approach velocity that did not exceed 0.25 m/s. The existing intake structure was built in the early 1980’s and consisted of interlocking steel sheet pile walls, capped with a concrete slab. Manholes on top of the slab provided access to the sump pumps, valves and pipe/cable ducts. The river bed in front of the structure is a flat concrete slab, which could provide a good base for the eel screens to sit on if needed.

Concrete slab on top of the sheet-pile pump and valve enclosure

Sheet-pile walls that make up the pump enclosure

View inside the pump chamber, looking at the sheet piling adjacent to the river. Below the waterline is the 0.2 m high x 3 m wide slot where the river water is drawn through.

View inside the pump enclosure, showing sheet pile walls

Close-up of intake drawing showing ‘letterbox’ slot

The existing intake did not have any screening; hence fish, eels and other objects could potentially enter the pump chamber.

CMDP (Costain MWH Delivery Partner) were the main contractor for the project, and GoFlo worked closely with them from the early design stages to the final commissioning to ensure an optimal solution was developed.

With a maximum abstraction flow rate of 0.278 m³/ second, the approach velocity through the existing intake slot in the sheet pile wall would exceed the maximum specified in the Eel Regulations. This meant that would it would not be possible to install the GoFlo screens inside the existing pump building and would have to be installed externally to the existing building.

An added complication was that the intake could not be shut down for more than 8 hours without severely disrupting the water supply to the Isle of White, which would not be acceptable, so the solution had to be designed to be installed into a working intake using divers.

GoFlo had a similar issue at another Southern Water site (Springfield), and for that site designed a fabricated ‘intake box’ system that could be installed by divers. This system worked well, so the principle was used for Sandown, even though the water depth at Springfield was 4.5 metres, whereas at Sandown it is typically only 600 mm.

The width of the screens at 3.55 metres has been determined by the minimum depth of water in the river (0.438 metres) while still having to meet the 0.25 m/s approach velocity under the Eel Regulations while abstracting the maximum flow rate.

Site Survey

The design process started with a detailed survey of the intake area. As is the case with many sheet-pile structures, nothing was exactly plumb or square, so because the fabricated Intake Box we would have to manufacture had to fit perfectly, first time, we had to enter the river and make plywood templates that fitted the profile of the existing structure perfectly. At the same time a detailed level-survey was conducted on the river bed concrete slab. We took the wooden templates away and turned them into precise profile data points that could be used to build an accurate 3D model of the existing structure in our CAD system. Based on that, we could design the Intake Box to fit perfectly.

Design

Due to how the in-pans and out-pans of the sheet piling were positioned, the bolted connections onto the Intake Box at the upstream end was on an out-pan and at the downstream end on an in-pan, so the left and right-hand intake box sides being different widths (1560mm & 1450mm).

Intake Box Side Drawing

Plan drawing showing new Intake Box attached to existing sheet-pile structure

The Intake Box is a stainless steel fabricated box made up of the two sides and a baseplate that were assembled into a finished box on-site. The structure is designed to be a rigid structure so it could support the screens in the inclined ‘operating’ and vertical ‘service’ positions. The Intake Box structure also had the walkways fixed to it, which in turn have the security fencing fixed to them, so had to be designed to be very strong.

A course bar screen with 50 mm bar-spacing was incorporated into the intake box, just upstream of the screens. This bar screen will protect the fine GoFlo screen meshes from large debris which could deform or puncture the screen face during flood flow conditions, but also keep any swimmers away from the moving parts!

An advantage of having the screens perpendicular to the river flow will reduce the possibility of the bar screen collecting debris; the river passing flow tending to pull material away from the bars.

Drawing of Intake Box with Course Bar Screen attached to upstream face.

Drawing showing GoFlo screens, debris trough and Intake Box attached to existing structure

The debris captured by the screens is returned to the river via the debris trough and return channel, but about five metres downstream, so the likelihood of material being pulled back into the screens is minimised.

The walkway structure incorporates davit sockets and removable winches. The winches are used for pulling the screens from their inclined ‘operating’ position to the vertical ‘service’ position. From here, the screen’s motor/gearbox and drive system can be accessed safely. Should a motor need to be taken off the screen, a portable davit can be mounted in a dedicated floor socket and the motor lifted up and over the handrail onto a trolley for transport away from the area.

Complete 3D model of proposed GoFlo system attached to the historic structure

Installation

This started with the river bank and floor being cleared of any silt and stones etc. Next, the Intake Box was assembled, including adding some temporary diagonal braces to keep the sides and baseplate square and to prevent the structure flexing during lifting. Once the Intake Box was in the river and fixed in position the diagonal braces were removed.

The Intake Box was fixed down to the concrete apron using stainless steel M16 resin-fixed anchors, and to the vertical sheet pile wall by drilling a tapping M12 bolted fixings. Installing such a structure in a flowing river was a hazardous operation, especially with divers in the water to guide it into position, drill and install the fixings into the wall and river bed. Underwater visibility was very poor due to unseasonal heavy rainfall and increased river flow. The divers had to be in constant radio contact with the dive support team on the bank. The divers also had a live video feed to the team in the control room so they could be guided to the fixing locations.

Lifting the Intake Box into the river

Lifting the first of the GoFlo screens into the Intake Box

Once the Intake Box was fixed in place the two GoFlo screens were lifted into position. This is a relatively quick operation due to the integrated ‘pivoting frame’, which are guide rails allowing the screen to be lifted in vertically and accurately guide the screen into position, even when the intake is flooded with zero visibility.

At this point the screens were connected to a temporary control panel and a wooden debris trough was constructed to allow the screens to be put into operation. The screens had to be put into service immediately because of the looming deadline to make the Intake Eel Regulations compliant.

The first screen in position on the Intake Box

Both GoFlo screens in position in the Intake box

A few months later the walkways, debris trough and security fencing were fitted, which all bolted directly to the intake box. The assembly was all designed in detail using 3D CAD software by GoFlo, then the constituent parts laser-profiled and CNC folded, finally being welded together. The walkways were installed in two days, and the debris trough in a similar time, which is testament to the accuracy of the design and fabrication undertaken by GoFlo.

Completed GoFlo screen installation

Download case study for the Sandown (Southern Water) GoFlo screen project.

The post Sandown (Southern Water) appeared first on Goflo.

Cressbrook Hydropower uses GoFlo Screens – Customer Testimonial

Cressbrook Hydro installed a GoFlo travelling screen in 2018 to automatically remove debris from the hydropower intake. After 3 years of operation, what does the owner and hydropower operator, Stephen Morrison, think of their performance so far ? We asked him, and this is what he told us. Another happy Hydropower customer !

“We chose to install a pair of 6mm GoFlo screens fitted in our river based hydropower intake to provide fully automated screening, in order to reduce downtime and maintain maximum head, for maximum power generation.

The installation was a straight forward process, assisted on site by an experienced GoFlo engineer. The screens were in and running smoothly without any issues and have continued that way over the first few years of service. They have performed well over a range of conditions, from severe frosts to heatwaves and during high flooding. The installation is in an area highly populated with deciduous trees and the screens have coped well during autumn, at various flow rates and river levels.

The fully automated system has resulted in little or no downtime due to debris and therefore helped power generation. It required a period of time to get to know the particular traits of the river, at different times of year, in order to choose the right settings, but GoFlo were always quick to help in the process. Monitoring and adjustments are easy thanks to remote access to the control panel, a webcam and the range of settings available.

We are pleased with our decision to install GoFlo screens and continue to receive help and support from the GoFlo team if we need it.”

The post Cressbrook Hydropower and GoFlo – Customer Testimonial appeared first on Goflo.

Water intake at the Templeborough Biomass Power Plant

In the spring of 2017, GoFlo Screens was hired by Interserve to design, manufacture and install one of its travelling water intake screen systems for the brand new Templeborough Biomass Power Plant, located in south Yorkshire.

The 41 MW biomass plant will generate electricity using waste wood. The plant will supply approximately 78,000 homes with green power, saving roughly 150,000 tonnes CO₂ per year. The biomass plant is one of a number of similar schemes built or under construction within the UK.

The power plant will make use of a single GoFlo travelling screen, located at the water intake for the cooling towers. This will screen a designated amount of water from the adjacent river. High power pumps will then pump the screened water to the biomass plants cooling towers.

This is the first time that a GoFlo travelling screen has been installed for use at a power station, but this reflects its use as a product that can be utilised across a wide range of industrial, agricultural and energy sector water abstraction applications.

The installed screen measures 1.2 metres in width by 3.9 metres in length and it is positioned at a relatively steep angle of 60 degrees. The screen will operate on a continual basis, given that the cooling towers will require a constant supply of cold, screened water. The GoFlo screen specification is standard, including remote control and monitoring and is integrated into the control system of the power plant. The screen motor is an IP67 specification and is therefore designed to be fully submersible for a short period in the (unlikely) event of a flood.

Installed GoFlo screen – looking down.

Water intake structure at Templeborough.

More information about the Templeborough Biomass Power Plant can be found at www.templeboroughbiomass.com.

The post Templeborough Biomass Power Plant commissions GoFlo travelling screen appeared first on Goflo.

Cressbrook Mill, Derbyshire

Jo Haddon of GoFlo Screens Ltd recently met with a team from the Environment Agency National Fisheries Service at the Cressbrook Mill hydropower scheme, located in Derbyshire. The National Fisheries Service acts to maintain the health and well-being of England’s fisheries and associated recreational and economic benefits.

The aim of the meeting was to demonstrate the utility, innovation and potential benefits of GoFlo self-cleaning water screens to a delegation of Environment Agency officials. The emphasis of the meeting was not commercial, but rather a neutral information sharing process with a focus upon the technical, regulatory and economic benefits of installing GoFlo self-cleaning water screens across a broad range of applications, including those within the energy, water utility and agricultural sectors.

Cressbrook GoFlo Screen in assembly

New hydraulic motor system

The site visit included a detailed presentation by Jo Haddon about key aspects of the GoFlo screens, with an emphasis upon key and unique design features, screen specification variations, installation procedures, monitoring and control, maintenance requirements and potential applications. The presentation also provided key data about the recently installed Cressbrook Mill screen.

The Fisheries team were shown a new development of the GoFlo screen in which a hydraulic, rather than an electric, motor is employed. The benefits of this include reduced levels of noise, less visual impact due to its smaller size, as well as being more tolerant to flooding. The new developments reflect GoFlo’s drive for continued innovation in order to meet ever tighter compliance standards.

The Environment Agency Fisheries team were also shown first-hand the screen at the site of the 100 KW Cressbrook Mill hydropower scheme (installed by Renewables First), in order to compliment the theoretical briefing offered during the presentation. Attendees were invited to ask questions relating to all aspects of the GoFlo screen.

Overall the Cressbrook visit was deemed to be very successful. As a regulatory organisation, the Environment Agency and associated specialists like to be objectively kept up to speed on products which demonstrate technical innovation and regulatory compliance.

The post Environment Agency National Fisheries Service meet GoFlo at Hydropower site appeared first on Goflo.

Maximising the generating capacity of a Cornish hydropower scheme using the GoFlo self-cleaning water intake screen.

The Kenningstock Mill hydropower scheme is an exemplar project demonstrating the benefits of combining modern hydropower technology with a GoFlo self-cleaning water intake screen.

Collaboration

Gloucestershire based Renewables First, who specialise in the feasibility, consenting, design and construction of low and high head hydropower systems throughout the UK and overseas, was hired in order to implement the hydropower component of the scheme. GoFlo Screens Ltd, a company borne out of Renewables First, was later commissioned to design, manufacture and install one of their innovative self-cleaning water intake screens, in order to meet stringent eel screening regulations and boost the energy capture from the turbine. Working collaboratively, both company’s project managed all stages of the scheme from feasibility, through to the design and consenting stages, installation and final commissioning.

Scheme details

The Kenningstock Mill scheme is located at Camelford in Cornwall. The hydropower component comprises a 25 kW Crossflow turbine, with a calculated annual generation of 107,454 kWh per year, enough to power the equivalent of 25 UK homes and displacing 53,727 Kg/CO₂ per year.

Kenningstock Mill crossflow hydro turbine

Kenningstock control system

The self-cleaning water intake screen was manufactured and installed by Gloucestershire based, GoFlo Screens Ltd. The installation comprises one screen unit with a width of 0.9 m and a length of 4.1 m. The screen is equipped with a fine mesh in order to provide fish and eel screening and to comply with environmental regulation. The screen is designed to accommodate a maximum flow rate of 0.6 m³/s and was designed to fit into the recently installed 25 kW hydro scheme. Prior to the GoFlo screen being installed at Kenningstock Mill, water was abstracted via a drum screen intake system into a penstock forebay header tank which fed a 24 ” penstock, approximately 30 m in length. The water was then transferred through to a Francis turbine (now replaced) for hydroelectric generation before transferring through the outfall tunnel and re-joining the watercourse. Following installation of the 25 kW Crossflow turbine and since becoming aware of the innovative design features of the GoFlo travelling screen, the site owners replaced the drum screen with the GoFlo system.

Intake drum screen previously used

Intake drum flow mechanism

Lifting the GoFlo screen into position

The GoFlo travelling water screen in position

Why use a self-cleaning screen at this site?

The requirement for a very fine screen mesh makes the Kenningstock site an ideal location for the GoFlo self-cleaning screen due to its excellent eel screening design. In response to tightening eel screening regulations, manufacturers of water intake screens have developed ever-finer screen meshes in order to protect aquatic life. Whilst good for wildlife, ever-finer screen mesh requirements present a significant problem for hydropower systems because as the screens become finer they increasingly get clogged with debris which renders the hydro system inoperable or operating inefficiently.

Screen blockages and reduced flow are the primary cause of turbine downtime or poor performance at most hydro sites. Blocked screens lead to significant losses of income if they aren’t quickly unblocked.

Intake screen-cleaning systems have been commonplace for years and come in a range of shapes and sizes, but they all begin to struggle as the bar-spacing reduces and ever-finer debris gets trapped and requires removal. Not so with the GoFlo travelling screen.

GoFlo screen scooping up leaf debris at the intake

The GoFlo automatic self-cleaning intake screen ensures that you meet environmental regulations, such as the Eel Regulations, whilst also greatly increasing the energy yield and therefore hydropower income generated by your system. Combining hydropower technology with the GoFlo self-cleaning screen is a win-win situation. Although the annual energy capture of the Kenningstock scheme was originally calculated to be 107,454 kWh per year, the later addition of the GoFlo screen will significantly improve the energy capture of the scheme by up to 20 %.

GoFlo travelling water screen design – an attractive proposition

But what is it about the GoFlo screen design that makes it an attractive proposition for hydropower sites? As well as the economic benefits outlined above, the eel screening provided by these screens enable compliance with stringent fish and eel regulations. They offer long-term reliability and permanently clean operation.

Screen maintenance requirements are straightforward and low cost. The screens are visually unobtrusive and are equipped with a remote monitoring and control system. Furthermore, the screens are easily installed using purpose-designed hinged (pivoting) mounting frames that are securely fixed to the concrete inlet structure. The screens are simply lowered into the pivoting frames from a vertical position. Once secure within the frames, the screens were then tilted to their specified running position. The motors used to power the screens at Kenningstock are located well above the level of the screen. However, they are fully rated to withstand full submersion in the event of flood conditions.

How it works

Once installed and operable, the screen remains stationary until integrated pressure sensors on the upstream and downstream sides detect a head loss across the screen, which triggers a cleaning cycle. Clearing debris is achieved by the screen mesh rotating, pulling trapped debris out of the water and dumping it into a flushing trough on the downstream side. Debris that doesn’t freely fall off is blasted off with a spray boom that sprays outward from inside the mesh. Once debris is in the flushing trough, a pumped water supply which runs whenever the screen mesh rotates washes the debris down the trough back to the watercourse, downstream of the system. This is considered best practice for naturally-derived debris, because decaying leaves and natural debris comprise the base of the food chain in aquatic ecosystems. This all happens automatically and is tied into the control system.

To see a GoFlo screen in operation, go to GoFlo TV at gofloscreens.co.uk/features-and-options/goflo-tv/

GoFlo Sophisticated Control System

Granular system operational and control settings provide for optimisation of the system when environmental and seasonal characteristics of the watercourse change. The scheme at Kenningstock incorporates the sophisticated GoFlo monitoring and control feature enabling full remote control of the system. The control and monitoring system is equipped with a mobile device interface, meaning that it can be monitored and controlled from anywhere with a suitable internet connection.

Integrated day / night camera

A high quality day and night vision CCTV camera is installed overlooking your GoFlo screen. You can view this via the built-in web interface to allow you to check for problems that require addressing or just look at how well GoFlo is doing at keeping your intake screen free of debris!

Another satisfied customer

Below is a testimonial from our client:

“Having taken over my aunt’s converted watermill in Cornwall in 2011, we inherited what must have been one of the first hydro schemes installed in the South-West. The first decision we had to make was whether to update the existing scheme, based around a reconditioned Francis turbine installed in the 1970s, or replace it with a more efficient modern turbine. We commissioned Renewables First to carry out a feasibility study and the results were not unexpected. An updated Francis turbine, even with the river in flood, would only ever operate at 50% of capacity because of the limitations of the site. Guided by them, we took the decision to install a new 25 KW cross-flow turbine made in the South-West by Ecowave.

We tasked the Renewables First team with using as much of the existing infrastructure as possible while keeping civil engineering work to a minimum – not an easy job given the restricted nature of the site. The result was a resounding success. The technical skills shown by the team and their dedication to delivering the scheme on time and to the highest possible standards was outstanding.
In the spring of 2016 we reached a decision that the pre-existing screen used to prevent leaves, wood and fish from passing through the turbine, was no longer fit for purpose. We had no hesitation in asking Renewables First’s sister company, GoFlo Screens, to design and build a new automated filter screen to sit in the leat across the entrance of the penstock. This was installed in the autumn. After a few minor adjustments, we now have a modern hydro scheme, capable of operating in all conditions, throughout the year.

We would have no hesitation in recommending Renewables First to anyone contemplating the installation of a small-scale, hydro-electric scheme.”

Made in the UK

The GoFlo travelling screen system was developed by experienced hydro engineers based in the UK. One of the greatest benefits of using a GoFlo travelling screens, aside from UK content, is the exceptional customer focussed UK based support available to ensure the system is operating efficiently and trouble free over its lifetime.

The post Case Study: Kenningstock Hydropower System with GoFlo Travelling Screen appeared first on Goflo.

Energy Efficiency Award for GoFlo Screens.

GoFlo Screens Ltd was recently “Highly Commended” within the Small Scale Project Of The Year category of the Energy Efficiency & Healthy Homes Regional Awards 2017. The award relates to the design, supply and installation of its innovatively designed self-cleaning water intake screen at the Kenningstock Mill 25 KW hydropower scheme.

The project involved the design, supply and installation of an effective automated water intake screening system. This supplemented a hydro refurbishment project, which routinely experiences river debris partially blocking the inflow of water. The site required fine screening (2 mm) to comply with fish and eel regulations.

The efficiency of the new screening system at Kenningstock Mill hydro project, Camelford, Cornwall, affects a renewable energy yield improvement of 21,490 kWh per year, equivalent to meeting the annual electricity needs of approximately 5 British homes.

All suppliers were local to the South West Region. Screen manufacturer GoFlo, and panel suppliers, Stroud Switch Gear, alongside A.D. Taylor Fabricators, are all based in Gloucestershire. The civil contractor, Mark Andrews Ltd, and electrical contractor, John Wood Electrical, are based in Cornwall.

The Kenningstock Mill hydropower scheme, installed by Renewables First (sister company of GoFlo Screens Ltd) was recently retrofitted with a GoFlo self-cleaning travelling water screen, as a way to significantly reduce the time associated with screen debris management, given that the hydro site location is prone to water debris from nearby tree cover. As well as massively reducing maintenance time, the self-cleaning water intake screen will also optimise the rate of flow to the hydro turbine, thus increasing turbine output and income generation. Indeed, the screen affects an efficiency improvement for the hydro-system of approximately 20% more renewable energy.

The travelling water screen was manufactured and installed by Gloucestershire based, GoFlo Screens Ltd. The installation comprises one screen unit with a width of 0.9 metres and a length of 4.1 metres. The screen is equipped with a fine mesh in order to protect fish and comply with environmental regulation. The screen is designed to accommodate a maximum flow rate of 0.6 m2 per second. The unit was designed to fit into the already up and running Kenningstock Mill hydro scheme, which comprises a 25 kW Crossflow turbine.

The post GoFlo scheme “Highly Commended” at 2017 South West Regional Energy Efficiency Awards appeared first on Goflo.

The GoFlo travelling water screen at the Cochwillan hydropower scheme.

The Cochwillan hydropower scheme is an exemplar project demonstrating the benefits of combining hydropower with innovative water screening technology.

Partners

Gloucestershire based Renewables First, who specialise in the feasibility, consenting, design and construction of low and high head hydropower systems throughout the UK and overseas, was hired by Carter Jonas land agents (acting on behalf of Penrhyn Energy Ltd) for their consultancy, design and installation procurement services for the hydropower component of the Cochwillan scheme.

GoFlo Screens Ltd, a sister company of Renewables First, was commissioned to design, manufacture and install their innovative GoFlo travelling water screen, in order to meet stringent eel screening regulations and boost energy capture from the turbine.

Working collaboratively, the two company’s project managed all stages of the scheme from feasibility, through to the design and consenting stages, installation and final commissioning.

Scheme details

The 90kW Crossflow turbine at Cochwillan.

The GoFlo travelling water screen at the hydro intake.

The scheme is located in North Wales on the Afon Ogwen on the Penrhyn Estate, Cochwillan. The installation comprises a 90 kW Crossflow hydro turbine, exploiting a net head of 8 metres and a maximum flow rate of 1.59 cubic metres per second. The water intake is located adjacent to an old weir and the turbine is located on land within a natural meander of the river. The GoFlo self-cleaning screen is located at the intake and is a modular system consisting of two screens located directly next to each other. With each of the two screens measuring 1.5 metres in width by 4.5 metres in length, the total screened area amounts to 13.5m2. Given that the site is in close proximity to the sea, the water intake screen needed to comply with the strict screening rules under the Eel Regulations – hence a screen mesh with a 3 mm bar-spacing was specified.

Why use a self-cleaning screen at this site?

The Cochwillan GoFlo self-cleaning screen with very fine 3mm bar spacing for eel reg compliance.

The requirement for a very fine screen mesh makes the Cochwillan site an ideal location for the GoFlo self-cleaning screen. In response to tightening eel screening regulations, manufacturers of water intake screens have developed ever-finer screen meshes in order to protect aquatic life. Whilst good for wildlife, ever-finer screen mesh requirements present a significant problem for hydropower systems because as the screens become finer they increasingly get clogged with debris which renders the hydro system inoperable or operating inefficiently.

A GoFlo screen removing debris from the hydro intake area.

Screen blockages and reduced flow are the primary cause of turbine downtime or poor performance at most hydro sites. Blocked screens lead to significant losses of income if they aren’t quickly unblocked.

Intake screen-cleaning systems have been commonplace for years and come in a range of shapes and sizes, but they all begin to struggle as the bar-spacing reduces and ever-finer debris gets trapped and requires removal. Not so with the GoFlo screen.

The GoFlo automatic self-cleaning intake screen ensures that you meet environmental regulations, such as the Eel Regulations, whilst also greatly increasing the energy yield and therefore hydropower income generated by your system. Combining hydropower technology with the GoFlo self-cleaning screen is a win-win situation. The annual energy capture of the Cochwillan scheme is calculated to be 487 MWh in an ‘average flow’ year, equivalent to powering 111 UK homes and producing an annual CO2 emissions saving of 243,642 kg. Without the GoFlo screen, the energy capture would be significantly less.

GoFlo travelling water screen design – an attractive proposition

But what is it about the GoFlo screen design that makes it an attractive proposition for hydropower sites? As well as the economic benefits outlined above, the screens enable compliance with stringent fish and eel regulations. They offer long-term reliability and permanently clean operation. Screen maintenance requirements are straightforward and low cost. The screens are visually unobtrusive and are equipped with a remote monitoring and control system. Furthermore, the screens are easily installed using purpose-designed hinged (pivoting) mounting frames that are securely fixed to the concrete inlet structure. The screens are simply lowered into the pivoting frames from a vertical position. Once secure within the frames, the screens were then tilted to their specified running position. The motors used to power the screens at Cochwillan are located well above the level of the screen. However, they are fully rated to withstand full submersion in the event of flood conditions.

How it works

Once installed and operable, the screen remains stationary until integrated pressure sensors on the upstream and downstream sides detect a head loss across the screen, which triggers a cleaning cycle. Clearing debris is achieved by the screen mesh rotating, pulling trapped debris out of the water and dumping it into a flushing trough on the downstream side. Debris that doesn’t freely fall off is blasted off with a spray boom that sprays outward from inside the mesh. Once debris is in the flushing trough, a pumped water supply which runs whenever the screen mesh rotates washes the debris down the trough back to the watercourse, downstream of the system. This is considered best practice for naturally-derived debris, because decaying leaves and natural debris comprise the base of the food chain in aquatic ecosystems. This all happens automatically and is tied into the control system.

To see a GoFlo screen in operation, go to GoFlo TV.

Remote control

Example screen shot of the remote control function.

Screen shot.

The GoFlo travelling water screen can be controlled both manually (in-situ) or remotely. The scheme at Cochwillan incorporates the sophisticated GoFlo monitoring and control feature and includes a camera for remote viewing. The control and monitoring system is equipped with a mobile device web interface, meaning that it can be controlled from anywhere. The Cochwillan control system communicates purely via the 4G network so that it can be controlled remotely.

Day / night camera

A high quality day and night vision CCTV camera is installed overlooking your GoFlo screen. You can view this via the built-in web interface to allow you to check for problems that require addressing or just look at how well GoFlo is doing at keeping your intake screen free of debris!

Remote Alarms

All critical alarms show in the web interface and can also be emailed automatically to email address embedded into the system, or sent to your phone via an SMS message. As an extra option, the GoFlo team can also monitor your system for critical alerts and take any action necessary to clear the alarms.

Satisfied Customer

Below is a testimonial from our client:

“The team at Renewables First provided us initially with clear and concise review of a partially planned project providing an alternative design.

Following approval and their appointment to the project we found the firm very reliable and all members of the team throughout the process easy to work with, and they worked well alongside independently appointed civils contractors.

Subsequently in relation to the ongoing running of the scheme they have been very helpful, always easily contactable via phone or email, providing technical support to resolve any problems or answer any queries.”

Suzanna Williamson MRICS
Surveyor

For and on behalf of Carter Jonas LLP

Find out more

Here’s how you can find out more about the GoFlo travelling water screen. If you are at the design stages of a hydropower scheme or already an existing site owner, use the Additional Hydropower Income Calculator to determine the potential increase in income that could be achieved by using a GoFlo system. More generally, the use of GoFlo screens is not exclusive to hydropower systems. They can also be used in many other contexts, including agricultural and industrial abstraction, water utility works and power plants. You may also be interested in using the Pricing Calculator to give you an idea of the budget required. If this appeals complete the Measuring Up Guide and submit more details about your site.

The post Maximising the benefits hydropower technology using innovative GoFlo travelling screen technology appeared first on Goflo.