Technology

 

Overview on contents

  • ORC CHP plants
  • Steam CHP plants
  • Agro Small heating devices
  • Taylor-made plant design for various customers
  • District heating
  • Pelletizing
  • Food processing industry
  • Wood processing industry



Agro-biomass technology

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Due to their special properties (high chlorine content, low ash melting point) agricultural fuels require special combustion technology. Here Danish companies are outrider because they have now over 20 years of experience in this field.

 

 

For a long time the use of straw as a renewable fuel stayed more or less concentrated in Denmark. Nowadays the shortage of wood based fuels and their increasing prices enforces the search for alternatives. Since agro fuels are widely unused and are broadly available for reasonable prices the straw burning technology spreads out in many other countries nowadays with an increasing pace. So a Danish company build over 25 plants in the last 5 years only in China.

 

 

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Until now most of the suppliers of these plants have offered either very big (70.000 tons of straw and more) or rather inefficient units. This slowed down the development in Europe because of the following reasons:
  • It is nearly impossible to secure enough fuels for the big plants on a long term basis without involving hundreds of suppliers.
  • The huge amount of heat produced by the bigger plants makes them infeasible.
  • The low electrical output of the smaller plants makes them infeasible.

 

This is the reason why AGROPOWER developed the following new plant concepts with a Danish straw boiler company:
  • CHP on ORC basis (700kW – 1.000kW)
  • CHP on steam basis (2.500 – 3.000kW)

 

All these systems can be supplied by the Danish vendor as turn-key solutions.

 

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In this graph you can see the potential electrical and thermal production of these plants and the demand of agricultural land. These new developed units combine high efficiency with smaller plants sizes on a very competitive price. Moreover the combustion can be fed with many different fuels (straw, corn cobs, wood chips, chicken litter, etc.) – only the in-feed section must be modified.

 

So they are perfectly suitable for the energy production out of agro-fuels because:
  • It is easy to contract the needed fuel amount. There are even farms, which could supply these plants with their own straw production.
  • The transport and fuel cost decrease. The flexibility of the combustion eases the fuel supply, too
  • The flexibility in the duel use makes even more sites interesting for these plants.
  • The heat use is more flexible and we have developed many possible solutions (pelletizing, green house, stables, district heating or cooling, etc.).
  • The investment can be managed even alone by big farmers.

ORC CHP plants

The ORC technology is well known for many years and has proven their reliability in many years of operation. We combined this technology with the well proven straw combustion from our Danish partner. The system can also be combined with drying units to increase the overall efficiency especially by using wood.

 

 

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ORC 6

Agro-biomass 

Field demand 

 Power production

Hot water production

Wheat straw  2.500 ha  617 kW  2.600 kW
 Corn straw  1.000 ha   2.600 kW
 Corn cobs 3.100 ha  2.600 kW
 Short rotation 350 ha  1.800 kW

ORC 7

Agro-biomass 

Field demand 

 Power production

Hot water production

Wheat straw  3.000 ha 700 kW   3.000 kW
 Corn straw  1.200 ha   3.000 kW
 Corn cobs 4.200 ha  3.000 kW
 Short rotation 420 ha  2.100 kW

ORC 10

Agro-biomass 

Field demand 

 Power production

Hot water production

Wheat straw  4.000 ha  1000 kW  4.200 kW
 Corn straw  1.600 ha   4.200 kW
 Corn cobs 5.600 ha  4.200 kW
 Short rotation 560 ha  2.900 kW

In multi-fuel system agro-biomass can be combined. Different intake-systems needed.

 

Steam CHP plants

 

technology agropower energy

Here our Danish partners scaled down the high efficiency of bigger steam CHP plants and combined it with their well proven straw combustion technology. The plant has several devices to minimize the heat loss and increase the efficiency. Therefore the boiler drain is used to pre-heat the condensate and the feed water is preheated with steam from the turbine, too. The live steam parameters are optimized for highest power output without facing corrosion problems at the super heaters (special design).

 

 

 

 

 

 

 

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High efficiency power plant

Agro-biomass

 Field demand

Power production

Hot water Production

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Wheat straw  8.000 ha 2.470 kW
-
2.970 kW
 6.500 kW
Corn straw  3.100 ha  6.500 kW
Corn cobs  11.000 ha  6.500 kW
Short rotation  1.100 ha  4.500 kW

 

Another advantage of this system is the flexibility of the produced heat. It can be hot water or steam at adjustable temperature and pressure levels. This is important for many industries, which require steam as a heating source (i.e. food processing industry, etc).

 

AGRO Small heating devices

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350 kW
650 kW
950 kW

The perfect heating solution for farms

  • Suitable for grain drying and heating of stables, greenhouses, etc
  • Flexible use of AGRO fuels
  • Easy to use and cost effective
  • Huge water storage allows over night heating without fuel handling
  • 100% automatic control with start-up / support oil burner
  • Turn-key solution

COST SAVING

COST SAVING

FUEL COST*

HEATING COST

Straw 25 €/t  0,8 Cent/kWh
Wood 35 €/t  1,5 Cent/kWh
Natural gas 0,25 Cent/m³  2,8 Cent/kWh
LPG 75 Cent/l  8,3 Cent/kWh
Heating oil 115 Cent/l  12,8 Cent/kWh

* Source: EU statistics December 2012

 

Alternative biomass input material

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1x Rectangular straw bale
Max. Dimension:
d= 1,2 x 1,2 x 2,5m
Weight ~500kg

 

 

 

 

 

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2 x round straw bales
Max. Dimension:
d =1,5m / B = 1,2m
Weight ~2x 300kg

 

 

 

 

 

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Fire wood / logs
Max. Dimension: L = 2,5m

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1. Stack
2. ID fan
3. Fly ash extraction
4. OPTION: Multi cyclone
5. Flue gas duct
6. Secondary air
7. Primary air
8. Ignition burner
9. Straw bale
10. Water storage tank
11. Combustion chamber
12. Profiled steel plates
13. Insulation
14. Flue gas box
15. Fire tubes
16. Turning chamber
17. Temperature Control damper
18. Furnace gate
19. Expansion tank

 

 

 

 

 

ACCUMULATION CAPACITY

 

350 kW

650 KW

950 kW

Bales 2,0 – 2,4MWh
5,7 – 6,9 h
2,0 – 2,4MWh
3,1 – 3,7 h
 2,0 – 2,4MWh
2,1 – 2,5 h
Water tank* 3,1 MWh
8,9 h
5,0 MWh
7,7 h
6,3 MWh
6,6 h
Max. time without
bale feed-in
14,6 – 15,7 h 10,8 – 11,4 h  8,7 – 9,2 h

* Water tank is integrated in the concept. Calculations basis on temperature drop from 105°C to 50°C.

 

Taylor-made plant design for various customers

We design the agro-biomass plant according to the energy needs of the customer and the availability of local biomass resources.

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Heat use opportunities

District heating

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Many CHPs are connected to district heating nets. A problem in this case is the low heat consumption during the summer time (~ 10 – 20% of the winter). Therefore profitable CHPs either need a big heating net with additional heating units for the winter time or industrial customers in the net with all year consumption.

 

Anyhow district heating nets are the most important heat consumer for CHPs and this field will even increase in the future. Even in SEE the potential is very high since even smaller cities have district heating nets (in Romania i.e. about ¼ of all households are connected). The following table shows that the projected CHP plants are feasible even for smaller cities.

 

 

Heating demand household

Feasible city sizes* 

Country

 kWh/m²

kWh/person

ORC10

sCHP30

SEE 390 kWh/m² 7.800 >9.000 >12.000
Germany 140 kWh/m² 5.600 >12.000 >19.000

* … Estimate: 1/3 of the people are connected to the district heating net.

 

The heat sale can be increased if cooling power is generated in the summer time (i.e. for logistic centers, etc.). This is technically possible with well proved absorption mashines.

 

Pelletizing

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In the last years a high number of wood pelletizing and briquetting plants have been build. These processes are very energy consuming because the material has to be dried first. Therefore pelletizing and CHP plants are a common combination in many countries.

 

 

 

 

 

 

 

 

The following table shows that the pelletizing industry needs quite high energy amounts:

 

Plant size*

 Heat demand

Feasible plant sizes

30.000 t ~ 4.8MW ORC10, sCHP30
60.000 t ~ 9.6 MW sCHP50
90.000 t ~ 14.4 MW sCHP80
120.000 t ~ 19.2 MW sCHP100

* … pellets production.

 

Another advantage in this constellation is the possibility to use a good portion of low temperature energy in the process, which can be produced by heat recovery systems in the flue gases of the CHP. The rest of the heating energy has to be supplied as hot water.

 

Moreover AGROPOWER developed a concept where the classical wood pelletizing can be combined with the production of AGRO pellets from feeding plants as alfalfa. This concept is optimized for bigger farms, which then can use the heat all year long for grain drying, feeding pellets production, stable / green-houses heating, etc.

 

Food processing industry

The food processing industry consumes a lot of energy in the following fields:

  • Process steam for sterilization
  • Heating energy – now mostly steam / can partly be changed to hot water
  • Cooling energy – now mostly electricity / can partly be changed to hot water
With the increasing energy prices more and more companies in this field changed their heat supply to biomass. This trend will continue in the future and provides interesting opportunities.

 

Example I - diaries

 

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Now a day most dairy farms are only running with steam (~ 5bar). With minor investments in the production the biggest portion of this energy can be supplied with hot water, too. Another big potential is to switch the production of cooling power to the CHP plant.

 

The following table provides a rough estimation of the energy demand in diaries (heating and part of cooling) on the basis of two reference plants. It can be seen that even medium sized diaries are interesting for CHPs.

 

 

 

Plant size*

 Heat demand

Feasible plant sizes

150.000 t ~ 4.8MW sCHP30
300.000 t ~ 9.6 MW sCHP30
450.000 t ~ 14.4 MW sCHP50

* … processed milk in tons of an integrated diary farm.

 

 

Example II - breweries

 

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The following table provides a rough estimation on the energy demand of breweries (heating and cooling). It shows that these facilities should have at a production of at least 500.000hl.

 

 

 

 

 

 

 

Plant size*

 Heat demand

Feasible plant sizes

250.000 hl ~ 1.7MW Too small
500.000 hl ~ 3.4 MW sCHP30
750.000 hl ~ 5.1 MW sCHP30

* … produced beer in hl.

 

Wood processing industry

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Since the presented CHPs can also be fed with wood based biomass this industry offers interesting possibilities for these plants, too. In general these plants offer good conditions to place CHP plants, because they produce their own fuel and can use the heat in the own process.

 

In Southeast Europe the wood processing industry broke down with the fall of communism and left back old fashioned and quite inefficient plants. But in the last years more and more international investors build top modern facilities in these countries. So the wood processing industry is still developing very well in these countries offering good opportunities for CHP plants, too.

 

The following table gives an overview of the fuel production and the heat demand of saw mills. It can be seen that these plants can supply much bigger CHPs than they would need to fulfill their own heat demand. This offers interesting possibilities for co-operations to supply heat to other consumers (i.e. cities, etc.).



Plant size*

 Fuel demand

Heat demand

50.000 m³ 6.75 MW ORC10 1.0 – 1.5 MW ORC7
100.000 m³ 13.5 MW sCHP30 1.9 – 3.1 MW ORC7
250.000 m³ 33.7 MW sCHP80 4.7 – 7.7 MW sCHP30
500.000 m³ 67.5 MW sCHP160 9.3 – 15.3 MW sCHP80

* … processed m³ of saw logs in saw mill.

 

Other heat consuming industries

Beside the mentioned industries there are many other production branches with an interesting demand of heating.