Water boilers

Water boilers

KNS boilers at GRASO are constantly developed in order to obtain the cleanest and the most environmentally-friendly combustion of straw. The units manufactured are a new generation of boilers that meets these requirements. Low temperature water boilers are designed for the preparation of hot water for heating purposes, namely heating of accommodation, office space, workshop, plant and production facilities, farms, dryers, plastic tunnels, greenhouses, etc.

The boilers can be used anywhere where it is possible to use renewable and waste fuels, often inutilely lost. Water boilers can only be used in open system installations protected according to PN-91/B-024413 “Heating and heat engineering. Protection of open system water heating installations. Requirements” not exceeding a pressure of 0.15 MPa, i.e. 1.5 bar (15 m of water column).

BASIC SERIES OF TYPES OF MANUFACTURED KNS STRAW-FIRED 200-1000 BOILERS


Details Unit KNS -200 KNS -250 KNS -300 KNS -400 KNS -500 KNS -750 KNS -1000
Power rating * kW 200 250 300 400 500 750 1000
Surface of heated room ** m2 1200 1400 1800 2200 2800 4200 5600
( poorly insulated 60)
(well insulated - 40W ) m2 1800 2100 2500 3400 4200 6300 8400
h- 3m
Fuel consumption *** kg / h ~ 60 ~ 80 ~ 90 ~ 120 ~ 165 ~ 225 ~ 350
( Average)
Boiler heating surface m2 27 35 40 53 68 87 120
Water capacity m3 3 08.mar 03.kwi 6 08.lip 05.sie 05.wrz
Combustion time *** h 3 3 3 3 05.lut 05.lut 3
Fuel load pc 1 bale fi 120x120 1 block 200x120 x80 fi 1bale 150x120 2 bales 120x120 fi 2 bales fi 150x120 2 bales fi 150x120 3 bales fi 150x120
Boiler weight without water kg 3400 4500 5500 7000 9000 10000 12000
Operating pressure MPa 0.15 0.20
Required exhaust draft Pa 50 40 50 55 55 65 75
Chimney height m 12 14 14 15 16 17 18
Chimney section fi ~ 350 ~ 400 ~ 400 ~ 450 ~ 500 About 600 ~ 700
Thermal efficiency % 75do80
Minimum return temperature oC 50
Maximum flow temperature oC 90
Accumulation tank capacity ( 60l/1kW ) l ~ 12000 ~ 15000 ~ 18000 ~ 24000 ~ 30000 ~ 45000 ~ 60000
Boiler length mmA 2100 2800 2600 3800 3800 3800 4900
( without fan )
Boiler width mmB 1600 1700 2000 1800 2100 2100 2100
Boiler height mmH 2200 2200 2550 2300 2600 2800 2900

A BRIEF DESCRIPTION OF THE MACHINE

Research on the construction of boilers has led to the development of boilers with a so-called counter-current combustion system, where thermal efficiency reaches 75-85%. Such boilers have two combustion chambers. Straw is loaded into the first chamber where it undergoes gasification (primary combustion). The second chamber is the proper combustion chamber where the combustion of gases takes place. The fan forces air into the boiler. The air is divided into two streams: primary and secondary. The primary stream is directed to the chamber with the burning straw. There the process of gasification of the straw takes place with the insufficient amount of oxygen, and the resulting gas containing mainly CO and other combustible organic components is directed in counter-current to the space where it meets the secondary air stream providing the sufficient amount of oxygen for combustion. This is the place where CO and CO2 are mixed together and organic compounds are burnt. Exhaust is directed to the heat exchanger and then to the chimney. To ensure a good straw combustion process, excess air of 25-50% should be provided. The optimal and completely clean combustion of straw is obtained only when all the gases are burnt which takes place at a temperature of about 850°C. The boilers are equipped with a control system that measures the temperature of straw combustion according to which it controls the flow of fresh air for combustion.

Through the use of a so-called accumulation tank we provide the continuous supply of Thermal Energy. Boilers manufactured by our Company require minimum operation and maintenance. KNS boilers are not subject to Technical Inspection and registration at the Inspectorate of Technical Inspection.


FUEL

The basic fuel for firing KNS water boilers is straw with a moisture content of up to 15% in the form of bales with dimensions of fi150x120 cm. Alternatively, bales, for example, with dimensions of fi120x120 cm or blocks with dimensions of 40x50x80 cm can be used.

The combustion of straw with higher moisture will reduce the thermal efficiency of the boiler and substantially accelerate the wear of the boiler and the chimney. The combustion of straw with a moisture content of above 30% is energetically unacceptable and economically unjustified. In the case of the use of alternative fuels, such as chips, pieces of wood, the boiler efficiency may decrease.



ADVANTAGES:

  • efficiency of about 80-85%,
  • cheap fuel (straw, hay, etc.) 4 kg straw= 1 litre of heating oil
  • easy operation
  • compact design
  • environmentally-friendly combustion of straw