Project Details: Home

 

  • Background
  • Safety

Project Description:

The goal of this project is to design, build, and optimize a high efficiency biomass gasifier for home power production. This gasifier will be designed to run on a variety of pelletized biomass sources. Gasifier technology is already quite developed, however, less work has been done surrounding optimizing small scale gasification for personal use.

Project Requirements

The gasifier design shall:

  1. - Have an outer body temperature cooler than 120oF, in accordance with OSHA standards
  2. - Include safety measures to prevent injury due to flammable and hazardous gases and high operating temperatures such as a flame arrestor, insulation, and a flame guard
  3. - Have clear labels on each component of the gasifier that the customer interacts to improve ease of use and safety
  4. - Produce between 4 to 6 kW of synthesis gas fuel credit
  5. - Produce high quality synthesis gas to be used in an internal combustion engine (<100 mg tar per cubic meter of synthesis gas while operating at steady-state (Chopra & Jain, 2007))
  6. - Fit though an eight foot high garage door so that the gasifier can be transported outside for testing
  7. - Not release appreciable amounts of synthesis gas to the environment during testing by maximizing complete combustion of the synthesis gas
  8. - Be free from leaks
    1. - Be operated outside in a well-ventilated area to avoid hazardous buildup of carbon monoxide gas

Major Milestones

  • Completion of Project Proposal Feasibility Study (PPFS) - Dec 9
  • Completion of initial design - Jan 6
  • Construction of prototype - Jan 13
  • Testing and optimization of prototype - Mar 3
  • Construction of revised prototype - Mar 24
  • Testing and optimization of revised prototype - Apr 28
  • Presentation at Senior Design night - May 10
  • Completion of Final Report - May 19

We are taking every effort to ensure that our project is as safe as possible. That being said, we are producing a product gas of carbon monoxide and hydrogen, which is both poisonous and flammable. This product will be safe, but operation will require caution and our design must take into account any safety concerns.

Hazardous Operations Q&A

Question 1: What if the flame travels down the flare tube?
Answer: A flame arrestor will be installed just prior to the flare. This will act as a heat sink, which will prevent ignition beyond this device.

Question 2: What if the entire reactor bursts into flames?
Answer: The venturi vacuum will be immediately inactivated. The compressed air valve for this will be located far enough away from the reactor so that it can be shut down despite the fire. A fire extinguisher and several 5 gallon buckets of water will also be kept near the reactor during operation to douse the flames.

Question 3: What if the reactor gets too hot?
Answer: The venturi vacuum will be inactivated, preventing oxygen from being fed, effectively cooling the combustion zone of the reactor.

Question 4: What if carbon monoxide or hydrogen gas leaks out of the reactor?
Answer: The reactor will be welded to prevent leaks and the reactor will be operated under a vacuum, so gas cannot leak out. If the reactor does happen to leak, air will leak in, rather than synthesis gas leaking out. Additionally, a carbon monoxide detector will be kept nearby to monitor atmospheric carbon monoxide levels. If the alarm goes off, the team will shut the reactor down by turning off the vacuum and dousing the biomass with water. The team will then exit the area and allow the carbon monoxide to dissipate before re-entering.
Question 5: What if there is too much or too little air?
Answer: If there is too much air, the gasifier will produce more carbon dioxide and water, rather than carbon monoxide and hydrogen. This will cause the reactor to get too hot, in which case, the answer for question 3 will be implemented.  If there is too little air, the reactor will shut itself down because it will not be hot enough to sustain the endothermic chemical reactions.

Question 6: Where will the gasifier be operated?
Answer: The gasifier will be operated outside of the garage door at the back of the engineering building. The team will ensure that there are no people or cars within a 10 meter radius of the operating area.

Question 7: Will the device be left running unattended?
Answer: The device will always be monitored by at least two people.  The operating area is in close proximity to the teams senior design station so the team will be able to monitor the gasifier while it is running.

Question 8: Can the gasifier explode?
Answer: The gasifier operates under a slight vacuum so during normal operation there is little likelihood of an overpressure scenario. However, if water entered the reactor there is the possibility of a steam explosion. We have carefully designed the steam feed to prevent the possibility of liquid water from entering the reactor. Additionally, in the event of an overpressure scenario the top plate of the reactor has been designed to lift off and relieve pressure before damage is done to the reactor body.

Question 9: How long after shutdown must the gasifier remain stationary.
Answer:  After the gasifier is shut down the reaction inside the gasifier will soon cease and within minutes the gasifier can be safely moved inside the engineering building where it will be stored.

Question 10: What would happen if the synthesis gas valve were accidentally closed?
Answer: Because the vacuum is generated on the back-end of the pilot plant, closing a valve after the reactor will cut off the vacuum to the reactor, effectively shutting down the reactor.

Question 11: How hot is the outside of the gasifier insulation?
Answer: The outside of the gasifier’s insulation should be less than 100 Degrees Fahrenheit.

Question 12: What would happen if the GC sample vial were removed before the sampling valves were closed?
Answer: The sample vial will be connected to the main piping with needle valves, which will limit synthesis gas flow to the atmosphere. A carbon monoxide detector will be present in the event that this valve is left open and atmospheric carbon monoxide levels become dangerous.

Question 13: What if the flare is extinguished?
Answer: A propane torch will be used to provide a pilot light during startup and if at any time the flame goes out.

Question 14: What if the synthesis gas produced is outside the flammability range?
Answer: The synthesis gas will never be near the UFL because the reactor uses an air feed, so it is diluted with nitrogen gas. The team is aware of the LFL, and will monitor this closely until a better understanding of the reactor’s operation is obtained. In a worst case scenario, the gas will be too dilute to ignite at the flare and the reactor will be immediately shut down.