A Newly Completed Windscreen Installation at APEX, Las Vegas, Nevada, for LADWP – Los Angeles Department of Water and Power

Description

This order came from LADWP for a large ACC – 5 modules wide x 6 streets long. The objective was to improve performance during windy conditions. The installation includes perimeter and cruciform screens. Galebreaker completed the project in 14 days. It is one of the largest orders we have received for a single ACC. M60 mesh fabric was used throughout which can withstand wind speeds of up to 120mph.

LADWP is the largest municipal utility in the United States, serving over four million residents and businesses in Los Angeles and surrounding communities. LADWP can currently deliver a maximum of 7,880 megawatts of power.

The Challenge

Located 35 miles outside of Las Vegas, Nevada, the original structure stretched roughly 200 x 240 feet and stood 117 feet tall. The heat exchangers of the air cool condenser and the 34 foot diameter fans are supported by a steel frame, with the columns being designed for axial load only. In the original design, wind is not factored in the steel design because the wind would flow right by the steel members, given it was an open structure. However a redesign was required as the wind was flowing by too fast and not being captured by the air cool condenser, resulting in huge inefficiencies for the client since the unit was being under-utilised.

For the remediation, Kipcon were tasked with re-evaluating all of the original members and coming up with a cost effective solution to increase the efficiency of the air cool condenser. Working on the project Mitch Frumkin, President of Kipcon Engineering looked to the technology of Galebreaker Industrial for a solution.

He turned to Galebreaker’s patented Wind Screen consisting of a woven polyester fabric with a PVC coating captures the wind and supplies the units with a steady air flow. This would however create a set of challenges in that the structure was never designed to take such wind loads. Mitch would have to reinforce the structure after installation of wind screens all around the exterior of the frame. When wind flows toward the screen, the two adjacent columns feel that lateral load as well as the tensile force from the cables pulling in from the deflection of the screen.

These two new loads put some of the retrofit columns into biaxial bending, something that Mitch was able to analyze and design for using SkyCiv 3D, when he couldn’t find the capability elsewhere. “I was looking for a program that needed comprehensive 3D capabilities,” Mitch reflects, “now I use it extensively and I love it!
Mitch was able to quickly identify and single out columns, beams and bracing that needed to be retroactively supported.

Project Details

Located 35 miles outside of Las Vegas, Nevada, the original structure stretched roughly 200 x 240 feet and stood 117 feet tall. The heat exchangers of the air cool condenser and the 34 foot diameter fans are supported by a steel frame, with the columns being designed for axial load only. In the original design, wind is not factored in the steel design because the wind would flow right by the steel members, given it was an open structure. However a redesign was required as the wind was flowing by too fast and not being captured by the air cool condenser, resulting in huge inefficiencies for the client since the unit was being under-utilised.

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How it was Designed

Mitch started off by modelling the entire structure, with the load of the air cool condenser. During the modeling of the original structure, Mitch took advantage of some easy-modelling functionality such as repeating; creating a single frame line and duplicating it over the number of bays in the structure. He found that the color differentiation of the members shown in the wireframe version of the 3D space to be clear and concise. Once the model was constructed, Mitch took full advantage of the hide tool to have a closer look at a single frame line to verify and ensure accuracy between the analytical SkyCiv 3D model and to include in his reports. Once the problem areas were identified, Mitch used the seamless integration between the SkyCiv 3D module and the SkyCiv Member Design Module to aid in his final design efforts. An unsung feature that was prominent in his deliverables to the client were the thorough and in-depth member design reports generated through the SkyCiv Member Design module.

Chuck Amstutz (Maintenance Manager at APEX) mentioned that over the weekend they had some heavy winds at APEX. Normally the south side fans trip under these conditions, but with the windscreens, the fans didn’t trip. This demonstrates an improvement in reliability. When we have the results of the planned thermal performance assessment later this year I have confidence that we will see a reduction in back pressure and a gain in performance.

Kit Lai San, Project Engineer in February 2018

View a gallery of images here.