FI100191B - Method for producing fuel from organic sludge and / or biowaste - Google Patents

Description

100191 METHOD FOR PRODUCING FUEL FROM ORGANIC SLUDGE AND / OR BIOWAST

The invention relates to a process for the production of fuel from organic sludge and / or biowaste, in which process the sludge is dried to reduce the moisture content to at least 55%, more preferably to 50%. In particular, paper and pulp mills as well as deinking plants produce huge amounts of so-called zero fiber sludge, which is currently an environmental problem. 10 To date, this sludge has been taken to landfill at a dry matter content of 30-40%, which is not an ecologically good solution. Zero fiber sludge has not been able to be composted.

Communities currently collect household biowaste and 15 produce another type of organic sludge at their treatment plants, although several methods have been developed for environmentally friendly treatment. Most commonly, the slurry is dried by a suitable method to 25-30% dry matter so that it can be composted. The most commonly used open composting is slow and requires large 20 areas.

. In Finland, industry annually produces about 800,000 tonnes of municipal sludge in dry matter, which corresponds to 2 million tonnes. tons .wet sludge. The communities produce 150,000 tons of sludge in '25 dry matter, equivalent to 1 mil j. tons of wet sludge.

\ \! : <·: To date, sludge has been incinerated with considerable auxiliary energy. In practice, the incineration of sludge is its destruction • ·% *. \ V among the actual fuel. For industrial sludges «« · • * · ·; 30 The main problem is low, even negative calorific value and high ash content. Of these, negative calorific value • *. ......

is naturally associated with high energy losses and power plant capacity constraints. Due to the incineration of sludge, it is not possible to obtain full power from the power plant within part of the power of sludge destruction. This capacity shortfall may be 20% of the nominal capacity of the power plant on an annual basis.

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Biowaste and municipal sludge are preferably not incinerated because the bacteria they contain cause some kind of hy-40 hygiene problem in their treatment, secondly 2,100,191 odor problems arise in the treatment, thirdly the high nitrogen content of biowaste and sludge is high, which is reflected in . In addition, there are heavy metals in the municipal sludge, which, however, according to the last 5 studies, remain in the ashes.

The object of the present invention is to eliminate the above-mentioned problems. The present invention solves the further treatment of biowaste and sludge in an economical and environmentally friendly manner. The characteristic features of the method according to the invention are set out in the appended claims.

The tunnel composting plant developed for sludge and biowaste is in practice a fairly efficient dryer, in which the drying energy 15 is obtained from the heat generated in the composting. The moisture content of the compost can be adjusted as desired by adjusting the composting time. For example, the Dutch VAM takes biowaste compost out of the plant at 30% humidity. This dry mass is not suitable as fuel due to the risk of explosion. The moisture content of the fuel should be about 50%.

The above disadvantages can be eliminated by tunnel composting as follows: '25 - Humidity can be adjusted as desired, eg 50%.

- The calorific value in the composted pulp corresponds almost to peat.

• ♦ · · · · I! ** - Odors are eliminated.

• · * - Bacteria die and the sludge is sterilized during the composting * ··%: ·· ’: · * · process.

• ·. * 30 - The appearance of the fuel resembles peat.

- Nitrogen emissions are reduced because nitrogen is removed as ammonia during composting. Ammonia is recovered with a water scrubber and can be sold as a fertilizer.

- The quantities of pulp to be treated are reduced, as mixing is not required.-..-: 35 combustion peat is not required (eg 10,000 tn of sludge '·; 8,000 tn of fuel comes. When mixing peat and sludge, the pulps should be treated from 80,000 to 100,000 m3.: Y: - The activity is year-round.

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The sludge contains some heavy metals, but they remain in the ash based on the combustion tests performed. The amount of heavy metals is so small that it does not affect the usability of the ash, for example as a fertilizer.

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Higher ash content is also not a problem, as the share of sludge fuel would be very small in the total amount of fuel, for example in Jyväskylä (IVO's Rauhalahti power plant) 3 - 4%.

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In the following, the invention will be described with reference to the accompanying figures, which show a tunnel composting plant according to the invention.

15 Figure 1 shows a tunnel composting plant connected to a power plant as a logistic system.

Figure 2 shows the air and water circulation diagram of the tunnel composting plant itself.

20 In Fig. 1, the reference number (1) generally denotes a tunnel assembly: ·· post office with mass ramps (2) with a ramp in addition to the tunnel silos (3) itself, as well as the required number of open piles (4.1 and 4.2) in the driven loading area.

'' The plant naturally includes a machine part for operating tunnel composting silos.

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'Biowaste and sludge are brought to these cars by their own cars (15 and 16) ««. I in the reserved stalls (2.1). Peat and bark mass are well suited for storage outdoors in their own heaps, here (4.1 and J · l «« ··?: ·:: 30 4.2). Instead of complex conveyors, one or more wheel loaders (8) with a mixing bucket (8.1) are used in the tunnel composting plant.

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Zero fiber sludge is composted by mixing.:, - .: 35 municipal sludge to start composting.

• * The nitrogen content can be reduced by mixing wood chips in the slurry, which improves air circulation inside the pulp. The amount of peat (or other carbon source) to be added is kept so small that 4,100,191 composting starts and stays in place, but it is not enough to sequester nitrogen, so that the nitrogen mostly escapes as ammonia gas with the exhaust air to the scrubber.

5 The tunnel composting plant according to Figure 1 up to the power plant's fuel silo operates logistically in a very simple way. All intermediate transports and mass mixing take place with the wheel loader (8) and its mixing bucket (8.1). Since the tunnel composting plant is in operation for about 10 days, in the case of three 10 silos, an external contractor can be used about every three days to mix the feedstocks into the mixing funnel (2.2), emptying the composted pulp from one tunnel silo into the power plant receiving silo (9.1). tunnel silo 15 with new fresh pulp. The tunnel composting plant itself operates automatically and does not require continuous manning at all.

This type of plant provides significant logistical benefits (low investment costs), even if fertilizer is produced instead of fuel or the pulp is further landfilled.

A typical compostable pulp mixture contains 25 to one part of zero fiber slurry, dry matter content 30 to 40%. : - 1/4 proportion of bio-sludge, dry matter 12 - 30% (and / or • · * * * 'bio-waste). - peat 0,5 m3 / ton of zero fiber sludge and 4 · # ((*** · "·· - bark 0,5 my ton of zero fiber sludge i t j ·· ···: ·:: 30 • · · ·

The drier the zero fiber sludge, the less is needed «· · li; excipients. In any case, composting zero fiber sludge • «:: *! ·· 'requires nutrients. In many places, the ratios of the amounts of industrial zero-fiber sludge and municipal sludge and waste are appropriate, // .: 35 suitably for tunnel composting.

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Composting the zero-fiber slurry as shown already provides: A: in itself a great benefit regardless of the further treatment of the pulp.

5 100191

The fuel produced by tunnel composting replaces a significant amount of peat and can be burned in plants suitable for peat combustion. The available fuel can be compared to peat in terms of calorific value as follows: 5 - zero-fiber sludge-based fuel is 1.5 MWh / ton sewage sludge-based fuel is 2.2 - 2.5 MWh / ton peat 2.8-3 MWh / ton

Fuel made from zero-fiber sludge corresponds to a calorific value of 10 shell pulp.

According to Figure 2, the main components of the tunnel composting plant (1) are, in addition to silos (3) with an air-conditioned base (3.1), a scrubber (5) and a biological air purifier (6) for exhaust gases. In addition, the plant needs piping for gas circulation to circulate air in the silos. In normal operation, the supply air is drawn in by the fans (12.1) through the heater (5.1) and blown into the air distribution base (3.1) in the tunnel silo (3). Exhaust air is blown into the scrubber (5) by means of a blower (12.2). This gives the heat needed by the heater (5.1). An electric heater (11) is only required for starting. Sewage water with nitrogen compounds is discharged through a sewage well (7) into a sewer or collected in a container and applied as a nutrient, e.g. to a field. When preparing the fertilizer, this would ultimately be applied to the finished mass. whereby the nitrogen compounds would return to the fertilizer.

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Claims (5)

1. Process for the production of fuel from organic sludge and / or bio waste using tunnel composting (1), 5. The process for the sludge is dried to reduce the moisture content to at least 55%, most preferably 50% using excipients, such as peat and bark which carbon cold to pour the compost into threads, and in which process the pulp is composted by mechanical air circulation (12.1, 12.2), characterized in that during the composting the amount of the excipients is regulated so that the composting itself starts, but the nitrogen does not bind to the pulp when the carbon source ends without discharge from the mass as a gaseous compound, which is bound by washing (5) of the gases emitted from the composting and by purifying the gases emitted from the circulation by biofiltration (6). 2. A process according to claim 1 when using zero-fiber sludge from a paper or cellulose plant or a decolorization plant, characterized in that sludge from community effluent is mixed in; .; 3. A method according to claim 1 or 2, characterized in that the air taken into the mechanical air circulation of the tunnel composting is preheated with heat supplied from the scrubber. % * «♦ · • V ·» i i • · · * .v · ' 4. A method according to any of claims 1-3, characterized in that the tunnel composting is realized with such a logistical system consisting of l./30 - the transport of the starting materials to intermediate collection piles (4.1, ΐ ·) «! 4.2, 4.3) on an executable loading support, - several tunnel silos with drivable loading support, · (- one or more wheel loaders (8) having a mixing bucket (8.1), the wheel loader (8) taking the starting materials from the intermediate storage hoists using its mixing bucket, fill and empty the tunnel silos Process according to Claim 4, characterized in that the dried fuel and treated pulp are discharged from the tunnel silo with the wheel loader (8) directly to the fuel silo (9.1) of the power plant (9) or other intermediate storage space. »M *« ► ··· * · »··« · «ai · · • · · · ·« · · · · · * 0 · · «» «* ·« »I · • ·« • · * • · * • · * V «· 4 oxygen • .11 * l J * I * · • 0 * I. • * · t • lii •. I t. · •• tl