John M. Sweeten

FIXED-BED GASIFICATION OF FEEDLOT MANURE AND POULTRY LITTER BIOMASS

The U.S. cattle industry is a

PARTICLE SIZE DISTRIBUTION OF CATTLE FEEDLOT DUST EMISSION

175 billion industry with an estimated 100 million cattle. About 10 million head of these cattle are in feedlots producing harvestable manure. At the same time, the U.S. poultry industry is the world’s largest producer and exporter of poultry meat. Not surprisingly, one outcome is the production of a large quantity of manure byproducts, with approximately 60 million tons of dry harvestable animal manure produced annually from confined livestock and poultry. This article describes a method of extracting energy from feedlot manure or poultry litter biomass either individually or combined with each other. High-ash (approximately 45% dry weight basis) feedlot biomass (HFB) and poultry litter biomass (HLB) were gasified in a 10 kW (thermal) fixed-bed, counter-current atmospheric pressure gasifier to generate a mixture of combustible gases that could be further burned to generate heat. This article discusses the effect of the biomass particle size on the composition of the product gas leaving the gasifier, the temperature profiles in the fixed bed, and the ash fusion of HFB and HLB during gasification. Air-blown gasification of the biomass fuels yielded a low-Btu gas with a higher heating value of 4.4 ±0.4 MJ/m3 and an average product gas composition (dry basis) of H2: 5.8 ±1.7%, CO: 27.6 ±3.6%, CH4: 1.0 ±0.5%, CO2: 6.7 ±4.3%, and N2: 59.0 ±7.1%. The overall average equivalence ratio was 2.82 ±0.43 on a dry ash-free basis. The experimental results also show that high-alkaline content fuels, such as HLB (Na2O + K2O = 16.7% of ash), can be gasified by blending with lower-alkaline content fuels, such as HFB (6.0%), to reduce agglomeration in the fuel bed without significantly affecting the heating value of the product gas. The gasification of HLB and HFB yields a low-Btu gas that can be combusted to generate heat for steam or power generation. The process has potential for reducing transportation costs for traditional cropland-based manure application in some regions.

Combustion of cattle feedlot manure for energy production

The cattle feedlot industry is under increased scrutiny and regulatory involvement at state and national levels with regard to particulate matter (PM) emissions from fugitive sources. Concentrations of total suspended particulate matter (TSP) and PM less than 10 micrometers (PM10) aerodynamic equivalent diameter (AED) were measured, using high volume samplers and Sierra Andersen samplers, respectively. Particle size distributions of dust captured on sampler filters were measured with a Coulter Counter model TAII. Mass median diameters for high volume and PM10 samplers averaged 9.5 ± 1.5 and 6.9 ± 0.8 µm (AED), respectively. Three cattle feedlots (17,000 to 40,000 head capacity) in the Southern Great Plains were used in the study.

Thermo-Chemical Conversion Analysis on Dairy Manure-Based Biomass Through Direct Combustion

Abstract Beef cattle feedlot manure containing 14–18% moisture, 16–42% ash, and 12 400–14 950 kJ/kg heat content was successfully combusted in a fluidized bed combustion (FBC) unit, operated in recirculating bed mode when temperatures were 620 ± 28°C. Higher temperatures in conventional FBC mode caused slagging and ash fouling. Beef cattle feedlot manure may be a useful fuel for on-site energy production.

Odor intensities at cattle feedlots in nuisance litigation

Growing rates of manure produced from large dairies and repeated application of manure on the same parcels of land have increased concerns for the environmental quality of nearby streams and watersheds. This paper deals with energy conversion analysis using a “black box” approach of supplying flushed dairy biomass (DB), combusting the DB solids, exhausting the combustion products to the atmosphere, returning liquid water back to the stall and thus eliminating (ideally) the need for lagoons and land applications. Minimum allowable moisture and ash percentages, as well as heat outputs and flame temperatures are presented for a DB direct firing system. Fuel analyses yield that flushed DB contained 93% moisture (%M), 3% ash (%A), 4% combustibles (%Cb), and a dry, ash free higher heating value, HHV DAF = 20,505 kJ/kg while separated DB solids contained 81%M, 2%A, 17%Cb, and HHV DAF = 20,494 kJ/kg. In order to fire separated DB solids in a combustor or furnace, the solids must have a minimum combustible percentage to vaporize all moisture in the fuel and burn at a minimum prescribed flame temperature. For example, DB containing 70%M requires 9.74%Cb to vaporize all moisture and produce gaseous products of combustion at 373 K, but requires 17.82%Cb to burn in a regenerative combustor with a flame temperature of 1200 K. Separated solids that are pressed in an auger to 70%M (3%A and 27%Cb) can burn at 1200 K with exhaust temperatures of up to 1130 K and a minimum required regenerative heat exchanger effectiveness of 15%. Pressed solids can thus be fired in a boiler, where the remaining separated liquid (waste water) can be used as boiler water. Depending on the boiler pressure and the %M of the original flushed manure, the pressed solids can only release about 30% of the required heat to vaporize the remaining waste water. However, pressed DB solids can be blended and fired with drier fuels to vaporize almost all the waste water. The low quality steam produced from the waste water may be used in thermal processes on the farm.

Combustion-Fuel Properties of Manure or Compost from Paved vs. Un-paved Cattle Feedlots

Abstract Odor intensity was measured around two cattle feedlots to evaluate better their impact on surrounding residents. Odor measurements were made by multiple observers using a Scentometer. Observed odor intensities were reproducible. Within a feedlot, odor intensities up to 120 DT were measured. Downwind 1 km or more values of 3 DT or less were typical. Odor intensity measurements were useful as an objective description of downwind conditions under a variety of climatic conditions.

Field Measurement of Ambient Odors with a Butanol Olfactometer

Research was conducted to determine the effects of feedlot surfacing materials (soil vs. coal-ash paved) and partial composting on feedlot biomass (FB) characteristics for use in thermochemical energy conversion involving reburn or co-firing with coal or lignite. FB was harvested from 12 fly ash-paved pens and 6 soil-surfaced pens and was windrow-composted. Higher heating value (HHV) before composting was more than twice as high for manure from paved (LA-FB) vs. soil-surfaced (HA-FB) pens, and ash content dry matter basis was 66% lower for FB from paved (20.2%) vs. un-paved pens (58.7%). Partial composting (51-55 days) reduced HHV by 2-20% to 5,704 BTU/lb (at 19.6% moisture) and 2,230 BTU/lb (at 17.0% moisture) for low-ash (LA-FB-PC)/paved pens and high-ash (HA-FB-PC)/un-paved pens, respectively.

Feedlot Biomass Co-firing: A Renewable Energy Alternative for Coal-fired Utilities

ABSTRACT A1-butanol olfactometer was used to measure ambient odor intensities at feedlots, meat packing and rendering plants, oil refineries, and other sources. The ambient odor intensities determined by odor panels using the butanol olfactometer were equivalent to 1.25 and 56.6 ppm of 1-butanol vapor in air. The precision of ambient odor measurements was within one-half step on the butanol scale. The method is precise enough for most odor investigations and abatement research.

Odor Intensities at Cattle Feedlots

The swiftly growing feedlot industry in the United States upshots in the production of manure from one or more animal species in excess of what can safely be applied to farmland, in accordance with nutrient management plans. Disposal of the vast quantity of manure produced as a by-product of the cattle feeding industry is one of the major operating tasks of the industry. Aside from the traditional means of disposal as fertilizer, an alternative and attractive way of overcoming this threat is to develop processes that make use of manure as an energy resource. In the present study, the feasibility of using manure as a fuel in existing coal fired power plants is considered and appropriately termed Feedlot Biomass (FB). The technology of co-firing coal: feedlot biomass facilitates an environment friendly utilization of animal waste for the production of valuable power/steam concurrently addressing the renewable energy, groundwater contamination, and greenhouse gas concerns. Co-firing tests were performed at the Texas A&M University 30 kWt (100,000 Btu/h) laboratory-scale facility. The trials revealed the enhanced combustion of the blends. The NO emissions were less for the blend even with higher nitrogen content of FB, as compared to coal.

RESPONSE OF SEVEN CROPS AND TWO SOILS TO APPLICATION OF BEEF CATTLE FEEDYARD EFFLUENT

ABSTRACT ODOR intensities measured at two cattle feedlots in Texas ranged from 1.5 to 170 dilutions to threshold (DT), which covers the measurement range of the Barnabey-Cheney Scentometer. The average odor reading at the surface of a 4000 head feedlot, determined by monitoring four randomly selected pens for 7 mo, was 31 DT. The run-off settling basin and retention pond averaged 68 and 46 DT. Half of the odor intensities were more than 23 DT, which exceeds the odor standards in several states. Odor intensities were diluted to 1.5 to 2 DT within 380 to 500 m (1250 to 1650 ft) downwind of the feedlot. At a 12,000 head feedlot, calcium ben-tonite was fed as a ration supple-ment at the following levels: 0.0, 0.8 and 2.0 percent. The 2 percent ben-tonite treatment resulted in a reduction in odors. Bentonite also improved average daily gain of cattle during the first 21 days.