Triton Power

Year Founded: 2017
Headquarter Location: Yorkshire, UK
Industry: Oil & Gas / Industrial
Website: www.tritonpower.co.uk
Company Profile:
Triton Power is a private independent power generation company with a total capacity of 1.35GW, supplying electricity to the UK wholesale market through its power stations. The company plays a key role in maintaining energy security by providing reliable power when renewable generation is insufficient, with the capacity to supply electricity to up to half a million UK homes.

At Deeside Power Station, Hughes and Salvidge were appointed Principal Contractor by Triton Power in 2021 to deliver a £2.7m programme of works involving the dismantling of the HRSG structure, twin 65m chimneys, boilers, top-hung LP/MP/HP vessels, and two large cooling towers.

The project required extensive enabling works, engineered lifting operations and careful separation from the live gas turbine building, with demolition carried out in a controlled east-to-west sequence using crawler cranes and high-reach excavators to ensure structural stability, safety and efficient material processing throughout.

The HRSG was constructed of a steel frame with external cladding to the external envelope. Within the confines of the external frame there was a large steel A-frame structure which provided support to the chimney stacks. The columns and horizontal beams also provided support to the top hung boiler. To the rear of the boiler there was a further steel frame with multiple platforms which housed the LP, MP and HP vessels which were also top hung from the steel frame.
The bay closest to the GT building was a cantilevered steel frame with external cladding supported from the steel frame where the vessels were housed. Two identical boilers were contained within the structure. Works were carried out working east to west.

Enabling Works

To undertake the deconstruction of the HRSG structure required the use of a High Reach Excavator and a Crawler Crane. Works commenced from the eastern elevation with the grass verge stripped of topsoil and stockpiled ready for later relaying on completion.

With the topsoil stripped, geotextile membrane was laid and a working mat formed. This was approx. 400mm thick across the area and was rolled in 200mm layers. On completion, plate bearing tests were undertaken to ensure the ground was suitable for the crawler crane and high reach to operate from.
The roadway between the grass verge and the structure was protected throughout using road plates.

Chimney Stack Removal

Works commenced with the removal of the two chimneys by crawler crane. All lifts were carried out with lifting plans/Appointed Person and RAMS created and approved prior to works commencing.
The chimneys were 65m in height and had a plate thickness range from 8mm thick at the top to 20mm thick at the base. The chimney was supported by a large structural steel A-frame and supported at a height of 32.73m from its collar. The chimney was constructed in 3 sections and the top 2 were removed by crane. The top two sections were joined on flanges and the bottom section secured to the steel frame and concealed underneath the external envelope of the HRSG so a section of the roof needed removing prior to this section being removed. The external makeup of the chimney was unknown so investigation work was undertaken at low level to determine the build-up.

Operatives accessed the chimneys via a 70m truck-mounted boom hoist to carry out the enabling works to the chimney. Operatives used a combination of hand/power tools tethered to the basket to undertake these works and expose the flanges to the two sections to be lifted.
With the flanges exposed and lifting eyes confirmed. Slingers attached the chains to the 4 lifting points of the chimney. Once slung, operatives used oxy/propane cutting equipment to cut above the first securing flange at approx. height 52.9m in height. Operatives cut the external plate to isolate the top section.

Once the last section was cut, the crane slightly raised the section to confirm its isolation from the lower sections. Operatives in the basket then manoeuvred away from the lift to a safe area, out of the way of the lift path. The section was lifted to ground floor level and processed by excavators with shear attachments.

With the first section removed, the same process repeated at level 39.5m. With the top two sections removed, the lower section of the chimney was secured below roof level. This section was lifted down once the roof structure was removed.

HRSG Structural Demolition and Separation

With the chimneys removed, works commenced on the separation from the gas turbine building. Initially our ZX870 excavator high reach de-clad the eastern elevation to allow light into the structure and remove a section of roof sheets to the northern side. The end bay nearest the separation line was left in place until a crane mat was in position to provide protection to the GT Building.

With the eastern elevation de-clad and the section of roof removed, operatives accessed the box gutter between the GT building and HRSG to form a separation. The cladding above the GT building was secured in position by screwing into the steel work which was cantilevered from the HRSG steel frame.

The external cladding was removed in sections using a combination of mechanical and hand removal. The crane mat was in position throughout these works. The excavator grabbed the cladding, working top down, lifting and lowering the cladding down to slab level.

Operatives split the cladding through the bay being left using a reciprocating saw so the bay remaining was undisturbed and remained secure. Our ZX870 high reach excavator then removed the steel frame on the eastern elevation.

With the external envelope removed, the cantilevered section steelwork was reduced. This section of framework was dismantled by slinging the sections to the crane, then hot cutting. Due to it being cantilevered, the steelwork was removed bottom up, maintaining the stability at all times.
With the 3 steels removed the high reach removed the steel rafters. Following removal of the rafters, the remaining section of the chimney was lifted down. The steel frame and vessels were then reduced.

This structure contained 3 vessels, LP, MP and HP. LP and MP weighed approx. 10t each and the HP vessel weighed 44t. All the vessels were top hung so sections of the steelwork were lifted out along with the vessel. Slinging arrangements were within the lifting plan produced by the Appointed Person.

The LP and MP vessel were removed using the onsite crawler crane. Due to the weight of the HP vessel a separate mobile crane was used to lift the vessel to ground level to be further processed.
Prior to the lifts taking place, operatives accessed the platforms and completed separation works using reciprocating saws. With the vessels removed, the steel frame was cut down by a high reach excavator leaving the rear steel goalpost frame in place.

With the chimney removed, taking the loading from the A frame structure, this was reduced.
With the A-frame section removed, the high reach excavator commenced removal of the boiler. The high reach excavator initially removed the remaining section of flue between the chimney and where the main boiler started with the horizontal tubing. With this section removed, the machine removed the lower section of the boiler. Due to the tubes being top hung, the machine removed the tubes working bottom up.

Following removal of the steels, the boiler frame was removed, leaving the western A-frame in place due to it providing support to the next bay of the roof. This was reduced by a combination of hand/crane and by mechanical means. The main structural steels are too large to cut with the machine so these were lifted out by the crane in sections with operatives isolating sections.

The next bay of the structure was the bay between the two boilers which had horizontal steel work spanning between the vessel steel of both boilers. Prior to removal of the next bay, a further separation from the GT Building was required. The machine de-clad the roof section to expose the steel rafters and the crane mat was in position when working close to the GT Building.

The cantilevered steels were removed by hand/crane before the steel rafters were removed by mechanical means. With the rafters removed, the remaining section of the vessel structure was reduced by mechanical means. The remaining A-frame section was reduced along with the central steelwork connecting the two boilers.

Cooling Towers

Both cooling towers were constructed of tanalised timber frame with packing and aluminium shutters. One of the towers measured 130 l/m in length with 8no fan cowls and the other 90 l/m with 6no fan cowls. Each had a height of approx. 12m. Through the centre of the structures ran a channel which varied in depth through to the sump located in between the cooling towers on the southern end.

Works commenced from the northern elevation using a 50t excavator fitted with a rotational grapple attachment. The excavator worked top down on one tower at a time initially de-cladding the structure and stockpiling the sheets. The excavator then removed the fan cowl from the first bay, lifting and lowering to ground floor level in sections. Once removed, the timber frame structure was reduced a bay at a time, working top down. The timber was removed in sections and stockpiled ready for later disposal.

The aluminium shutter doors were sporadic and were removed as the works progressed through the structures.