product description p 201.2 vee grate mk 2– a...

DGA Co Ltd, Tel. No: 02 674 3077; E mail : [email protected]; www.dga.co.th

Main features of the new DGA VEE Grate are :-

Cast Iron Grate Bars on cooled frame for good temperature resistance andlow wear

No moving parts in the airbox so high preheat temperatures. Up to 350 Ccan be used.

Water cooling by low pressure and temperature water from Deaerator No fixed pipes to break. Design uses flexible hoses with isolators so can be

changed with boiler on load. Intermittent vibration action to reduce impact on surrounding structures High amplitude low frequency action gives good directional stability to

movement Low vibrating mass to reduce loads on driving gear springs and structure High quality spring steel leaf springs installed outside the air box for longevity. Zone control to air flow under the grate for combustion control Flexible air bellows installed outside the boiler enclosure for easy change

out of fabric bellows. High temperature fabric bellows to isolate vibration. May be used for staged combustion when arranged with a secondary air

system similar to BFB system Grates can be arranged in multiple sections which are joined together with

a fuel tight connector. This allows each section to be vibrated independently. In theory the furnace can be as wide as required to fire the largest furnace Usually ground mounted the Vee grate can be elevated as shown in diagram.

When ground mounted the grate or grates can be withdrawn from the boiler.

VEE GRATE in large industrial Boiler

SUPPORT STEEL

COMBUSTION AIR

SUPPORTSTRUCTUREIN STEEL ORCONCRETE

WETASH

SYSTEM

FURNACE

VIBRATIONUNIT

C/W INAND OUT

PRODUCT DESCRIPTION P 201.2

VEE GRATE Mk 2– A Vibrating Combustion Grate

End View of the VEE Grate. Shownground mounted in an ERK boiler



End view of the VEE Grate showsthe method of installing the grates side byside to allow them to fire any size boiler.

The design ensures that the vibrated massis the minimum compatible with structuralstrength which is provided by the spaceframe construction. This ensures that thevibration is minimised on even the largestgrates.

Elevated on a structure some vibration maybe felt though the boiler when the drive isoperating, but careful design of thestructure and footings minimises the impactof the vibration.

Intermittent vibration, and vibration of eachunit separately ensures that the effects aretemporary.

The VEE Grate has been developed from earlierversions which are in regular use in SE Asia for

the combustion of Biomass fuels, from palmwaste to rice husk.

The increased size of the grate andthe location at ground level

allows grate to be easilyremovable for maintenance.

This unit is for a 30 tn/hDGA Eckrohr boiler

The NEW DGA Vee GrateWill fire the DGA Eckrohr boilersFrom 10 to 55 tn/h with superheat


DGA Vibrating Combustion Grates have been developed as a grate capable of firingall biomass solid fuels, from palm oil waste through wet bark and wood wastes to cleanwood chip and even bituminous coal

Fuel SpreadingFuel is spread through the flames already established on the grate to cause ignition ofthe incoming fuel. The ignited fuel lands on the grate adding to the established fuel bed,and the action of the grate moves the whole fuel bed towards the front of the grate wherethe ash discharge conveyor is located.

Gentle WearThe vibrating action of the grate moves the fuel bed gently down the grate with littlewear to the grate surface. The vibrating causes the fuel to be spread to an even depth onthe grate and together with the air drafting dislodges the ash particles from the live fuel.Denser ash falls as bottom ash to the ash discharge conveyor.

High Air PreheatBecause there are no moving or rotating parts in the combustion airbox high levels of airpreheat are available to allow combustion of even very wet biomass fuel.

Handles sticky fuelsThe combustion deck of the grate is water cooled in order to stop fuels from sticking tothe grate during combustion and also to retain the physical strength of the constructionmaterial.

Low Vibrated massAttention has been given to reducing the overall vibrated mass so the grate is builtaround a space frame in light clad material. In order to reduce the impact of the vibration.

Good CombustionCombustion of solid fuel is the major part of the design of this grate so it has beendesigned for good distribution of combustion air, injected at optimum pressure forgood air:solid mixing on the grate..

High Thermal RatingUp to 2 MW/m2 is available for most biomass fuels. This reduces to ~ I MW/m2 withlow calorific value low reactivity coals

High EfficiencyThe main feature of the grate is that it forms the heart of a modern high efficiency firingsystem, that is able to burn a variety of biomass fuels, sized for < 80 mm particleswith good fuel burn out ie low carbon in ash, even when fired at low excess air.Standard grates are available to operate at 45% excess air and with staged aircombustion this can reduce to ~ 30 % excess air.





This picture was shot through the peepholeof a furnace whilst the boiler was firingat high load on Palm Empty Fruit Bunch

The stack was clear.

Vee Grates are supplied by :-

DGA Co Ltd315/344 Soi Wat Po ManSathupradit Rd, YannawaBangkok, Thailand

Other Equipment

Ancillary Equipment that may be supplied with the Vee Grate is :-

• Spreader Stokers for Biomass. These are also used for wastematerials such as RDF.

• Mechanical Spreaders for coal and lump biomass• Variable screw feeders for biomass and or solid fuel• Wet ash discharge conveyors• Vibrating sequence Control

The range of grates available currently spans from 7 MW thermal to 175 MW thermal. Thisis the equivalent of firing steam boilers rated from 10 to 200 tn/h of steam.

More than 30 Vee Grates are operating primarily on Mackenzie Boilers for use in theirPalm Oil Boilers and latterly on boilers supplied by Bangkok Industrial Boilers of Thailand.

The Vee grate has been installed on boilers through Malaysia, Indonesia and Thailand.Recent projects have been quoted in Africa and Cambodia.



product description p 201.2 vee grate mk 2– a...

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