BioCycle September 2007, Vol. 48, No. 9, p. 51
A West Virginia farm in the Chesapeake Bay Watershed is testing a gasification system designed to produce three million BTUs/hour of heat.
AT A farm in the Chesapeake Bay Watershed in Wardensville, West Virginia, Josh Frye raises 800,000 broilers annually. Frye Poultry had two significant ongoing challenges: 1) What to do with the 1,000 tons/year of manure from the poultry houses that has to be trucked out of the watershed to be land applied; and 2) How to better manage mortalities.
A friend told Frye about a pilot project at Southern Illinois University that was testing the gasification of turkey litter. Frye agreed to go with his friend to visit the commercially-sized test unit, built and operated by Coaltec Energy USA, Inc., located at Coal Research Park at the university. There wasn’t that much to actually observe – just the material going in and ash coming out of the test unit. Portholes enabled viewing the swirling orange gasses inside as a steady flow of litter was being gasified. Frye quickly recognized how the technology could benefit his broiler operation, and began working with Coaltec to pursue installation of a similar unit at Frye Poultry.
Coaltec submitted a proposal in 2006 for funding through the Natural Resource Conservation Service’s Conservation Innovation Grant for the project. The company was successful in obtaining the grant to install a gasifier that would run on raw chicken litter, with the addition of the farm’s mortalities. Frye was composting the mortalities, which was labor-intensive and created an element of risk of spreading disease if the composting process was not properly completed.
Operations at the farm consist of flocks that have a 6-week cycle with approximately 100,000 birds per flock. There are three houses with about 20,000 square feet of floor space per house. After each flock leaves the farm, Frye “crusts out” the houses – scraping the top layer of manure from the floor. There is no bedding used, so this product is 100 percent manure. There is typically a three percent mortality rate, which equals about 24,000 birds/year to be disposed.
GASIFIER INSTALLATION AND START-UP
After site work was completed – including building a road and a 30-foot by 50-foot concrete pad for the system – the gasifier was delivered on March 19, 2007. The modular system was in place by the end of the day, ready for coupling to the ducting system. By day three, the system was running. The gasifier – a 36-square foot system – can consume about 1,000 lbs/hour of manure. It requires a propane feed line for the two start-up burners; the electrical service was initially just a 100-amp breaker from one of the chicken house services. Due to the addition of ash and feed conveyors, the service was upgraded to a 200-amp service. The system has a roto-phase unit in the control room to convert 110-volt single-phase power to 3-phase power.
The energy generated by the gasifier system heats one of Frye’s three Class A broiler houses. The other two houses, which will be placed on the system when the research component is finished, are being used as a control group. West Virginia University researchers will assist in the monitoring and testing required to validate the project’s findings. It can produce 3 MMBTU/hr of energy, enough for the entire poultry operation.
A new air distribution system was installed in the ‘test’ poultry house as part of the project. The air is pushed through steel ducting into the house and then it runs the entire 500-foot length of the house through a perforated nylon sock that allows for even distribution without high velocities or temperature swings. Positive air pressure is provided into the house and is used to force air out. This enables significant air changes to supply fresher air into the house without the current system of exhaust fans and intake louvers that are fraught with breakdown and cleaning issues.
There also is an important benefit to bird health, as the heat produced from the gasification of the poultry litter replaces the need to use the old radiant brood heaters fueled by propane. Approximately eight-tenths of a gallon of water moisture is emitted for each gallon of propane burned, contributing to the formation of ammonia – a limiting factor to successful poultry husbandry. Research has shown that high levels of ammonia are extremely detrimental to bird health, resulting in decreased productivity and feed conversion. Benefits to bird health are being monitored under this grant project.
Gasification is a staged oxidation process. The reactions take place in a refractory lined primary gasification chamber and an oxidation/temp control chamber. Coaltec has the U.S. marketing rights for the Westwood Energy Systems, Inc. gasifiers. A WESI-36 is used at Frye Poultry. It is a two-stage system consisting of a reaction bed area including a propane start-up burner; an ash removal section and standard removal conveyor; and an oxidizer/temperature control section complete with another propane start-up burner. The propane burners are used to heat the fuel bed during initial start up and also to prevent smoking from the stack as the system is getting up to operating temperature.
The target fuel is gasified into producer gas in the primary gasification chamber. It is an oxygen starved (fuel rich) chamber that promotes the production of CO, CH4 and H2 at a relatively low temperature, typically ranging from 1,000 to 1,400°F. A small amount of CO2 is created in the chamber to provide energy for the gasification process. As the amount of moisture increases in the fuel, additional CO2 has to be produced to maintain the target temperatures. This balance is accurately maintained by controlling the air/fuel ratio in the primary chamber.
The resulting “producer gas” is ducted to the oxidation chamber where high temperature oxidation and combustion of the gases, as well as air dilution to desired temperature, takes place. The chamber is a cylinder with staged air added in a directional manner, creating a spinning reaction that promotes an even blending of the combustible producer gas with additional air. As the gas reacts, it produces heat energy; air is added to keep the temperature within the target range. Variable Frequency Drive (VDF) fans and air valves are controlled by temperature and provide exactly enough air for complete oxidation of the producer gas, plus enough dilution air to maintain target temperatures. The completely reacted gas is then sent to the customer’s energy application.
The system is relatively clean, and while the emissions are somewhat fuel dependent, they are typically within regulatory limits. The gasifier is essentially using a heat exchanger to take the heat from the system and convert it to clean hot air. The energy from the unit can be used to supply a multitude of downstream applications – steam, power, chilling, etc. At this time, the unit is not being directly coupled to any type of direct-fired engine. The gas contains about 145 BTU/cu. ft., a low-grade gas.
Coaltec has completed multiday test firings on a variety of fuels including wet distillers grain, ethanol mash, turkey litter, corn stover, dairy manure, plastic, paper sludge, recycled oil filters, refuse derived fuel (sorted municipal waste), construction debris and various grades of coal. The testing has provided analysis and data needed to design gasification systems capable of successfully utilizing these fuels. Multiple characteristics are evaluated when investigating potential fuels. Some fuels that alone are not suitable for use, e.g., don’t have enough energy and can be blended with higher energy content fuels to make a good fuel. Typically, the final fuel mixture must contain at least 3,500 BTU/pound to have enough energy to operate the system. Michael McGolden, CEO of Coaltec, believes that in most instances, using a locally available fuel with a zero, low-cost or even negative-cost fuel on-site where the energy can be used to benefit the customer directly is the best application for the company’s gasification systems.
At Frye Poultry, the gasifier system installed is designed to provide about 3 million BTU/hr. of heat, equivalent to the maximum output of all of the existing propane heaters currently in all three houses. Based on initial calculations, it is believed this system will supply enough energy for six houses. The resulting ash from gasification is about 30 percent of the weight of the original dry weight of the fuel. The product is very high in phosphorus, potassium and calcium and has a value as a fertilizer component.
Barbara Gaume is with Coaltec Energy USA, Inc. and can be reached at firstname.lastname@example.org.