The Moss gasifier is a two stage updraft atmospheric unit that produces low BTU syngas in the primary chamber and then ignites the gas in our thermal reactor low excess air ignition system. Moss combustion systems are capable of meeting the most stringent U.S. air emission regulations by implementing our superior design and control technologies to provide the required results. Syngas burns cleanly into water vapor and carbon dioxide. Moss is a leading supplier of solid fuel gasifier type combustion systems for the industrial market. The advantage of gasification is that using syngas is more efficient than direct combustion of the original fuel - more of the energy contained in the fuel is extracted. Moss specializes in solid fuel gasifiers systems capable of gasifying wood, various biomass fuels (i.e., shelled corn, wheat, corn stover, peanut, oat, coconut and rice hulls, pecan shells, sugarcane bagasse) and municipal solid waste (MSW). Our syst ems prov ide envi ronmenta l and energy recover y solution s thro ugh the use ofsuperior combustion. Moss provides engineeri ng, procure ment and construct ion services (EPC) assu rin g succ essf ul soli d fuel fired gasi fica tion base d proj ect inst alla tions. Our turnkey installations begin at fuel unloading and end at the tip of the stack. In today’s emission and regulatory environment, Moss provides innovative solutions by providing adva nced cont rol syst ems, flex ible fuel del iver y and stor age syst ems and pro perl y selected emission equipment to meet our customer’s most stringent requirements. Our advanced technological and manufacturing capabilities to ensure our customer’s requirements for the most adGasification is a thermo-chemical process that generates a fuel rich gas. Two processes take place in the Moss gasifier in order to produce a useable gas. In the fir st stage, pyrolysis releases the vol atile components of the fuel at temperatur es below 1100°F (593°C). The by-product of pyrolysis, which is not vaporized, is calle d char and con sis ts mai nly of fix ed carbo n and ash . In the secon d sta ge ofgasif ica tio n, the car bon remain ing aft er pyrolys is is eit her react ed wit h steam or combusted with ambient air, mixture of ambient air with recirculation air (FGR) or pure oxygen. Gasification with air results in a nitrogen rich low BTU gas. Gasification utilizing pure oxygen results in a higher quality mixture of carbon monoxide and hydrogen with virtually no nitrogen. Gasification with steam produces a hydrogen and carbon dioxide rich synthetic gas called syngas. Usually the exothermic reaction between carbon and oxygen provides the heat energy required to drive the pyrolysis and char gasification reactions.vanced gasification system are met. Thermal NOx accounts for the majority ofNOx formed (typically in the range of 80 to 95%) when firing gaseou s fuels. The majority of NOx reduction control technologies are directed toward lowering thermal NOx. The use of steam injection to reduce peak flame temperatures has been used for years; however, the drawback to this process is the cost to produce the steam, not being able to use it in the plant and the effect on the boiler’s overall efficiency. It has been fou nd tha t al ter nate met hod s of thermal NOx contr ol, suc h as sta ged combustion and flue gas recirculation, could provide the required NOx reductions with a much lower capital and operating cost impact. Cleanup technologies such as Selective Non Catalytic Reduction (SNCR) systems can lower NOx by 40-45%; however in cases where NOx reductio n has to exceed 90%, the se techniques alone are not always adequ ate. The use of flue gas cleanup tec hnologies, such as Selective Catalytic Reduction (SCR), has demonstrated the ability to achieve NOx reductions in excess of90%. The drawbacks to these systems are the high capital cost of implementing them and their continued operational costs. Moss designs NOx emissions reduction technology on solid fuel boilers through the use of a combination of combustion techniques such as flue gas recirculation (FGR), fuel-air staging and/or steam injection into our thermal reactor (overfire air system) providing a method to achieve lower NOx emission levels without the cost and complexity of flue gas cleanup systems. Flue gas recirculation mixes The gasification process was originally developed in the 1800s to produce a low BTU gas for lighting and cooking in towns and small cities. Utility supplied electricity and natural gas later replaced town gas for these applications, but the gasification process has been
Transcript
8/7/2019 gasifiction
http://slidepdf.com/reader/full/gasifiction 1/10
The Moss gasifier is a two stage updraft atmospheric unit that produces low BTU syngasin the primary chamber and then ignites the gas in our thermal reactor low excess airignition system. Moss combustion systems are capable of meeting the most stringentU.S. air emission regulations by implementing our superior design and controltechnologies to provide the required results. Syngas burns cleanly into water vapor andcarbon dioxide. Moss is a leading supplier of solid fuel gasifier type combustion systems
for the industrial market. The advantage of gasification is that using syngas is moreefficient than direct combustion of the original fuel - more of the energy contained in thefuel is extracted. Moss specializes in solid fuel gasifiers systems capable of gasifyingwood, various biomass fuels (i.e., shelled corn, wheat, corn stover, peanut, oat, coconutand rice hulls, pecan shells, sugarcane bagasse) and municipal solid waste (MSW). Oursystems provide environmental and energy recovery solutions through the use of superior combustion. Moss provides engineering, procurement and construction services(EPC) assuring successful solid fuel fired gasification based project installations. Ourturnkey installations begin at fuel unloading and end at the tip of the stack. In today’semission and regulatory environment, Moss provides innovative solutions by providingadvanced control systems, flexible fuel delivery and storage systems and properlyselected emission equipment to meet our customer’s most stringent requirements. Ouradvanced technological and manufacturing capabilities to ensure our customer’srequirements for the most adGasification is a thermo-chemical process that generates a
fuel rich gas. Two processes take place in the Moss gasifier in order to produce a useablegas. In the first stage, pyrolysis releases the volatile components of the fuel attemperatures below 1100°F (593°C). The by-product of pyrolysis, which is not vaporized,is called char and consists mainly of fixed carbon and ash. In the second stage of gasification, the carbon remaining after pyrolysis is either reacted with steam orcombusted with ambient air, mixture of ambient air with recirculation air (FGR) or pureoxygen. Gasification with air results in a nitrogen rich low BTU gas. Gasification utilizingpure oxygen results in a higher quality mixture of carbon monoxide and hydrogen withvirtually no nitrogen. Gasification with steam produces a hydrogen and carbon dioxiderich synthetic gas called syngas. Usually the exothermic reaction between carbon andoxygen provides the heat energy required to drive the pyrolysis and char gasificationreactions.vanced gasification system are met. Thermal NOx accounts for the majority of NOx formed (typically in the range of 80 to 95%) when firing gaseous fuels. The majorityof NOx reduction control technologies are directed toward lowering thermal NOx. Theuse of steam injection to reduce peak flame temperatures has been used for years;
however, the drawback to this process is the cost to produce the steam, not being ableto use it in the plant and the effect on the boiler’s overall efficiency.
It has been found that alternate methods of thermal NOx control, such as stagedcombustion and flue gas recirculation, could provide the required NOx reductions with amuch lower capital and operating cost impact. Cleanup technologies such as SelectiveNon Catalytic Reduction (SNCR) systems can lower NOx by 40-45%; however in caseswhere NOx reduction has to exceed 90%, these techniques alone are not alwaysadequate. The use of flue gas cleanup technologies, such as Selective CatalyticReduction (SCR), has demonstrated the ability to achieve NOx reductions in excess of 90%. The drawbacks to these systems are the high capital cost of implementing themand their continued operational costs.
Moss designs NOx emissions reduction technology on solid fuel boilers through the use
of a combination of combustion techniques such as flue gas recirculation (FGR), fuel-airstaging and/or steam injection into our thermal reactor (overfire air system) providing amethod to achieve lower NOx emission levels without the cost and complexity of flue gascleanup systems.
Flue gas recirculation mixes
The gasification process was originally developed in the 1800s to produce a low BTU gasfor lighting and cooking in towns and small cities. Utility supplied electricity and naturalgas later replaced town gas for these applications, but the gasification process has been
8/7/2019 gasifiction
http://slidepdf.com/reader/full/gasifiction 2/10
utilized for the production of synthetic chemicals and fuels since the 1920s. The Mossgasification combustion system is a two (2) stage process design that gasifies (producessyngas) in the primary chamber and ignites the syngas in a secondary chamber (Mossthermal reactor) producing a clean efficient flue gas that can be used in a boiler, dryer,kiln or any heat exchanger process requirement. Our gasifier system is capable of burning various wood or biomass fuels that are low or high in moisture. Ash fusiontemperature, ash, BTU and moisture content are a few of the fuels components that we
always consider when evaluating the fuel to be burned. The Moss gasifier designpromotes safety first and is far superior to most others when burning dry fuel because of the way fuel is augured into the chamber and the way that underfire air is introducedinto the grate assembly. Our gasifier design also helps prevent a "blow back" fromoccurring that may cause a fire in the fuel storage facility. Safety in a dry fuel applicationis always a major concern for Moss design personnel. Not all combustion chamberdesigns can burn dry fuels safely.
Our system provides superior combustion technology with multi-zone grate underfire air,multi-port overfire air system, providing high turndown capabilities powered by ourcustom designed combustion control system. Moss has several grate assembly designswhich allows our engineers to choose the correct system for the fuel to be burned. Manyfactors including ash, moisture and BTU content, ash fusion temperatures, whether thesystem is automatic ash removal or manual, etc., determine the proper grate system for
the application. Moss also provides several proven techniques in our gasifiers thatpromote clean and fuel rich syngas. Because of our low pressure fan and air distributionwithin the grate, the Moss gasifier minimizes particulate carryover from the secondaryphase of the combustion chamber. Since ash and unburned particles are less likely tobecome airbo
The Moss automated fuel feed metering bin system, with variable speed drive, providesfuel input based upon steam, heat or temperature demand. Once fuel is augered fromthe metering bin, it is discharged into a single or multiple gasifier infeed augers. Theinfeed augers distribute the fuel over the entire gasifier hearth ensuring a completelycovered grate assembly (a grate that is not covered with fuel can cause a blow torcheffect – possibly causing clinkering or burning on the grate). The infeed augers areprovided with a rotary air lock and heat sensors when burning dry fuel (this is optional onwet wood systems).
The multi-zone grate underfire air system provides the flexibility to burn different fuelsfrom low to high moisture. The convenient external hand valves allows for the properamount of air to be distributed into the areas where combustion occurs inside thegasifier chamber. The total amount of underfire air is metered by a variable speed drivethat is connected to the underfire air fan assembly and is controlled by the system PLC.This unique design controls the underfire air throughout the combustion chamber tomaximize syngas production. Our gravel grate system is unique to the combustionsystem industry and provides superior underfire air distribution to the fuel with minimummaintenance required. In addition to our gravel grate assembly for our gasifier systems,we provide cast iron, reciprocating grate, refractory with stainless steel nozzles andrefractory tile grate assemblies to meet your specific application and preference.
The gasifier infeed auger(s) gradually pus
The Moss PLC solid fuel control system uses the latest technology and software thatallows you to operate your system around the clock safely with minimum to nosupervision. This system is the heart of our gasification system technology for any boiler,dryer, kiln or heat exchanger process. The Moss combustion system design is suppliedwith a panelview screen to provide you with a high quality view of the systems operatingparameters. All necessary lights, switches, power supplies, modem, variable frequencydrives, etc. are a standard with our system. This sophisticated device reads actions asthey occur within the system and translates them in a logical manner so the systemreacts properly. This control system is easy to use, provides exceptional safety featuresand provides the system operator with invaluable information about the systems
8/7/2019 gasifiction
http://slidepdf.com/reader/full/gasifiction 3/10
operation and can direct the operator to the exact location of problems drasticallyreducing downtime.
The Moss PLC control system offers the following features and benefits:
• A Variety of Fuel Types: Four different fuel settings can be preprogrammedinto the PLC, which modifies the fuel feed and air input automatically. This is doneby simply turning the switch on the front door of the control panel to the desired
fuel setting for the fuel being burned.
• Fan to Fuel Control: The operator has full access to use the panel viewscreen to change the underfire air fan or fuel feed variable frequency drive HZsettings for each of the four (4) biomass fuel settings.
• Password Protected: A four (4)-digit group of numbers must be entered on akeypad in the setup parameters of the control system in order to make changes tothese parameters. This protects the system from unauthorized changes.
• Alarm Log Status: Indicates if a fault has occurred since the alarm counterwas last reset. The operator can display a special alarm screen, which details thesource o
Installation services are available for installation of the gasifier system. This includes allrequired mechanical erection, piping, electrical wiring and design engineering. Moss
provides single source responsibility, including if desired by the Owner a completegasifier facility including building and foundations.
Our mechanical/electrical/structural installation crews are experienced in the properinstallation and startup/training of the gasifier facility. Our work scope has includedgeneral building and concrete construction, structural steel, system erection, pipingfabrication and installation, material storage and conveying systems, electrical/controlwiring, ductwork/breeching and process instrumentation. Our project team provides ahigh level of planning that assures our customers their project meets the specifiedcompletion time sched
Experimental investigations of long stick wood gasificationin a bottom lit updraft fixed bed gasifier
Submitted by A. Saravanakumar on Thu, 2008-07-17 06:01Last updated November 04, 2008
Experimental investigations of long stick wood gasification in a bottom lit updraft
fixed bed gasifierA. A. Saravanakumar, Spray Engineering Devices Limited, Noida, Uttar Pradesh,
India, July 17, 2008
Long Stick Reactor
Based on the experience of the gasifier users on the efforts and energy for wood chip
preparation in a typical gasifier, we have embarked on the development of a gasifiersuitable to work with long stick woody biomass as the feed materials. In the context
of the impact of gasifiers, as decentralized energy delivery devices such anapproach, it is hoped, would be an attractive option in rural areas both in domestic
and industrial sectors. In the present paper in the gasifier operation, there is a fixedquantity of char that is combusted to gasify a fixed amount of wood, and the gasifier
does not operate in a steady state manner. In this present work, focus is made onthe development of a gasifier using long sticks of wood as feed materials. With this
concept, a 10 kW thermal output power gasifier is designed and constructed. The gasand airflows can be converted to the air/fuel ratio, the most important aspect of
gasifier operation. The air/fuel ratio shows operation in a combustion mode at startup, a gasification mode for the middle part of the run and a charcoal gasification
mode at the end of the run. Since the interest here is exploring and validating of thisconcept, a bottom lit updraft gasifier is designed mainly to look at the gas yield and
other favourable factors and to use this gas so obtained for thermal applications. Therate of feed was between 9 and 10 kg/h and continuous operation for 5 h was made
in a couple of runs to study the performance. In this paper we report the salientfeatures of our efforts and results, yielding a gasifier efficiency of 73%.
