Power Generation Facility Ash Loadout Upgrades

A power generation facility in Northeast Wyoming was looking to upgrade their ash loadout building to test a new process to increase efficiency in the ash removal process.

Ash being a dry particulate waste product generated as a result of solid fuel combustion is disposed of by burying it in an open pit. At a power generation facility, proper disposal of the ash waste is one of the final steps required to deliver electricity in an environmentally friendly manner. The United States Environmental Protection Agency (EPA) and the Wyoming Department of Environmental Quality (WYDEQ) regulate the amount of airborne particulate in and around industrial facilities.

A challenge with handling the ash waste, which was addressed through this project, was the material handling process, specifically in the transportation from the power generation facility to the disposal site. Due to the characteristics of the ash, the dry particulate matter can become suspended in the air, especially on windy days. To combat this, water is added to the ash waste to form a heavier, paste-like product that is not affected by the wind. While adding water to the ash waste is a simple process, maintaining the correct ratio, especially when handling 20,000 pounds of material presents its own challenges. A couple of the challenges being that if the water quantity is insufficient, the waste product remains dry and susceptible to the wind. Whereas, if the water quantity is too great, the process has used too much water which increases operational costs.

To mitigate these challenges, the facility purchased a new mixing unit for the ash loadout building. The new mixing unit would offer benefits over the original unit by having load cells on the legs that will help determine the amount of waste material present and the amount of water needed to achieve the determined ratio. The new mixing unit would also have a vertical paddle style, designed to achieve a more consistent mixture. In addition, remote observation and controls would be present, that would allow the waste/water ration to be fine-tuned from the control room to compensate for the changing environmental factors.

JBW was hired to assist with the mechanical and structural engineering scopes of work for this project. The mechanical engineering scope included rerouting water lines from the existing water supply lines and modifying the ash hopper in the building to match the inlet on the new mixing unit. The structural engineering scope included analyzing the existing building floor and superstructure to ensure these were within allowable limits under the increased operating loads.

While the project produced great results in the end, it was not without its hardships. One obstacle we encountered in the project was that the original mixer was square, while the new mixer was round and had a larger capacity. The discharge chute for the round mixer is larger than the original and was also in a different location on the floor. To overcome these obstacles, a model of the original superstructure was created to determine the location of the new discharge chute and the load cells. The structural capacity of the new and existing beams was checked, and modifications were made to existing beams and connection plates to accommodate the new loads.

Another hurdle faced was that the record drawings indicated the steel used for the superstructure was from overseas sources with little published data about the type and strength of the material. The JBW team reviewed the limited information available and used engineering judgement to determine which assumptions could be safely incorporated in the design.

A final constraint that the team contended with was that the allowable construction timeline available was 2 weeks, which included time at the beginning of the project for the plant shutdown procedures and time at the end for plant startup procedures. In order to contend with this, JBW had personnel on call throughout the entire project, and on-site at the contractor’s request to ensure that design questions and changes were addressed quickly and efficiently.

While the project faced its own set of constraints and challenges, JBW’s team of engineers were able to use their expertise to overcome these obstacles and remove barriers. Understanding the facilities’ needs and need to maintain compliance, JBW was able to provide engineering services that allowed the facility to upgrade their systems that would help maintain efficiency and reduce overall operational costs.