UI Steam Plant Measurement Systems

The goal of the project is to measure and record the primary fuel variables for the wood fired boiler at the UI Energy Plant. The measurements can be used as inputs to automate the wood fired boiler combustion controls. Mass fuel flow of the wood chips, moisture of the wood chips, mass air flow, air temperature and air moisture flowing into the boiler are all necessary to optimize combustion.

=Problem Definition= The objective of our capstone project as Rolling Timber II is an extension of previous work with the intent of generating an operating lab prototype that can enable full-scale implementation in the UI Steam Plant.

Team Rolling Timber I (the previous team) was able to design and build a prototype sensor for mass fuel flow and fuel moisture content. These sensors will need to be refined and then a measurement and verification process can either prove or deny the design concept. Additionally, the measurement of mass air flow, temperature and moisture content will need to be developed.

Background
The University of Idaho Steam Plant produces steam for heating and campus buildings and sidewalks, as well as chilled water from a lithium bromide system. Steam is primarily produced in a boiler burning sawmill waste known as hog fuel.

The wood fired boiler at the University of Idaho is driven by the combustion of wood fuel and air. Mass fuel flow of the wood chips, moisture of the wood chips, mass air flow, air temperature and air moisture flowing into the boiler are all necessary to optimize combustion. Operation and control of biomass boilers has been primarily done by plant operators manually.

Although some of these measurements may seem easy to accomplish, the measurement of the fuel mas flow and the fuel moisture content in real time has been identified as the biggest challenge. To this end, Mr. Scott Smith sponsored our capstone team, Rolling Timber ll, to investigate and develop measurement systems for the mass flow rate of fuel and air into the firebox, as well as the moisture content of the fuel.

Deliverables
As of 2018, the woodchip boiler consumes approximately $ 1,000,000 per year in fuel. This is a significant savings over alternative fuels (e.g. natural gas), but could be further improved by implementation of a feedback control system to more efficiently supply fuel and combustion air.

Currently, excess fuel is supplied to the firebox of the boiler. Mr. Scott Smith, the Steam Plant Manager, estimates that approximately a 5-15 % reduction in fuel consumption could be achieved by implementation of a feedback control system, reducing operating costs and improving air quality in the City of Moscow. In addition to these tangible benefits, no other known wood-fired boiler has yet implemented comprehensive feedback control system, so implementation of this type of steam at the UI Steam Plant would be a breakthrough in biomass boiler technology.

=Highlights of the previous team's work=

Control system and automation are required for the three important variables in the UI Steam Plant.

1. Mass flow rate of wood chips

2. Moisture content of wood chips

3. Mass flow rate of air.

The previous team (Rolling Timber I) was be able to finish:

1. Design and build the prototype of mass flow sensor for wood chips

2. Design and build the prototype of moisture sensor ...Purchage the off-the-shelf moisture sensor (WCMT-HGT)







=Design Concepts Considered= We have two major concepts for design.

1: Design for the prototype-scale testing

2: Design for the actual implementation in the plant (full-scale)

Now we are in the phase 1 as of July-9 in 2018, which is designing for the prototype-scale testing. By end of this summer 2018, we will start designing the full scale for the implementation in the plant.

Possible Designs for the implementation in the plant


Here are our first ideas of implementing the measurement plate for calculating the mass of the fuel and the reasons behind each design.

1-idea(1) is having a plate inside the throat. - less fabrication. - Free fall technique.

2-idea(2) is cutting a part of what is originally exist for and expanding the throat. - more space inside the throat to avoid clogging. - Free fall technique.

3-idea(3) cutting a small part at the corner of the bin and implement the measurement plate. - less fabrication - will tend to use alternative technique since free fall will not work for this design.



We combined idea (1 and 3) for # reasons: - less fabrication. - by adding the sliding plate in the top will increase the probability of falling the fuel above the measurement plate.

After meeting the client: idea (2) win. - easy for future maintenance. - safer place for the load cell, away from the heat. - easy to replace load cell if needed.
 * But we have a new challenge there is an I-Beam, part of the plant structure. We are limited to 5 inches in width.



Functional Specifications
※It is fine to use modified unit such as lbs/min or lbs/s, however, lbs/hr is a unit which is usually used in the plant.

※Source of woodchips: Cedar, Pine, and Fir  (These are available in this area)

Mechanical Specifications
Spatial Requirements

Implementation of devices (our design) should be require little to no modification to the existing system in the plant.

•The available space within the throat is 9” wide × 84” long × 26” long. (for mass flow sensor of wood chips)

•Round duct – 24” diameter (for mass flow sensor of air)

•Rectangular duct – approximately the same cross-sectional area as the round duct (for mass flow sensor of air)

Materials for the prototype

Mild Steel is preferred by our client.

=Testing=

Load Cell Testing
Our initial testing has been done with load cells we plan on using for measuring the mass flow rate of wood chips into the fire. For testing we are using a simple OpAmp circuit to boost the signal output by the load cells.

Basic Simulink Setup


We are running this boosted signal into Simulink for now just to see if the load cells are consistent enough and have the sensitivity we need for this application. Using this setup we conducted simple tests by placing mass on the load cells. With these basic tests we think the current load cells will be acceptable to continue testing.

Testing Equipment
Testing Equipment will be developed by our client, Mr. Smith Scott by July-9th (Mon). Testing of our prototype with circuits and software is planned in Week 5 (July-9 ~ July-13)



=Final Design=

=Team Members= {| width="80%" border="0"

=Additional Documentation=

Project Schedule

Gantt Chart



Budget



Meeting Minutes

Meeting Time (Summer 2018)

1- Group meeting everyday (2 hours)

2- Meeting with clients and instructor every Tusday at 11:00 am