RU2721560C1 - Production method of fuel granules from frozen peat - Google Patents

Abstract

FIELD: peat industry.

SUBSTANCE: invention is intended for peat industry and can be used in production of fuel granules (pellets) from frozen peat. Frozen peat, peat moisture content of 50 % and less (see Fig. 1) is transported along the winter snow passage to its processing point (production hall). Peat is chopped in the frozen state in the grinder. Then milled peat is subjected to convective drying with hot air till moisture content is 20 % and additional grinding (particle diameter 3–5 mm) in drying drum. Temperature of incoming dry air into drum is 200–250 °C, and output temperature is 120–130 °C. Duration of drying process makes 9–23 minutes. From the drying drum particles of peat with temperature of 110 °C enter the chamber, where by air blowing from the production shop with temperature of 23 °C, are cooled to temperature of 30–32 °C. Further, cooled peat particles are moved to a granulator (pelletizer), where during pressing and forcing through perforated annular matrix, peat fuel pellets with diameter of 8 mm are produced. In process of pressing and production of granules, peat temperature increases and reaches 38–43 °C. Then pellets are laid in open mesh trays and stored at normalized parameters of internal air of production workshop 23 °C and relative humidity 50 % (ambient temperature). During storage peat fuel granules moisture drops to 10–12 %. After that pellets are packed. Air coming out of drying drum with temperature of 120–130 °C and air from cooling zone of granules with temperature of 72–75 °C together are supplied to heat exchanger used for heating of production shop, and then discharged into atmosphere.

EFFECT: high efficiency of the process of producing peat fuel granules by using raw lump raw material of lump peat.

1 cl, 1 dwg

Description

Technical field

The invention relates to a method for producing peat granules. The invention is intended for the peat industry and can be used in the manufacture of fuel pellets (pellets) from frozen peat.

State of the art

A known method of producing granular peat [1], in which milled peat is crushed, dried to a moisture content of 20 to 40% (by weight) and granulated in granulators.

The disadvantage of this method is the lack of a process for cooling the granules after drying, before the granulation process, during which the temperature of the granules increases even more, which complicates the process of laying and packing for storage.

A known method for the production of granular peat [2], including the excavation of peat, dehydration of the milled peat to a moisture content of 68 - 75% by natural drying in spread, granulation of peat, harvesting into folding units and subsequent drying of granules on the slopes of folding units under a transparent coating preventer. At the same time, granular peat is lined on slopes of 1.5 - 2.0 layers at an average daily temperature of at least + 5 ° C and effective volatility of at least 1 kg / (m ² · day). The preventer is placed on dry land or an undeveloped technological site with a degree of drainage of at least 7 J / kg.

The disadvantage of this method is the long duration of the process.

A known method [3] for producing granular peat for household needs, including preliminary drainage of the peat deposit, excavation of the peat mass from the reservoir with its simultaneous grinding to a particle size of 1 to 10 mm, granulation, drying of granules in the field, and cleaning granules into folds units. Preliminary drainage of the peat deposit is carried out to a moisture content of 80 - 82% using an open drainage network with standard dimensions of the drainage channels for the upper deposits. Peat is excavated by milling a peat deposit to a depth of 300-500 mm, followed by granulation of peat to a granule size of 25-40 mm. The granules are dried to a harvesting humidity of 33 - 40%.

The disadvantage of this method is the use of deposits of only high peat, the need to create an open drainage network of drainage channels for preliminary drainage of the peat deposits, drying granules in the field on the surface of the peat deposits, high harvesting humidity of peat granules.

Closest to the claimed invention is a method for the production of granular peat mixtures [4] (prototype), including the extraction and transportation of raw materials of high humidity to the plant, separate bunkering, preparation of peat mixtures, granulation, drying of granules to a conditional moisture content of 10 - 18%, packaging and shipping finished products to the consumer. Raw materials are extracted with a moisture content of 67 - 72% and 45 - 55% by a milling method with separate cleaning and warehousing according to a two-product technological scheme; before preparing peat mixtures, foreign inclusions, including hemp, are separated from the milling raw materials by pneumatic separation, and the peat is additionally crushed to no coarseness more than 5 mm, at the same time heating in suspension to 70 - 95 ° С with steam-air flow with heat recovery. Next, a peat mixture with desired consumer properties is prepared on the basis of various peat and additives by dosing with a mixer to a homogeneous mass, which is then dried to a conditional humidity. After that, the mass is granulated by extrusion molding, and the resulting granules, with a diameter of 5 - 25 mm, after drying to standard humidity and cooling by blowing with air to a temperature close to the environment, are transferred to the packaging or long-term storage zone. To heat the feedstock use the heat of the gas-vapor stream after cooling the granules. The granules are dried by using a low-grade heat carrier from an external source.

The disadvantages of the method are: the non-use of the thermal potential of the coolant from an extraneous source used for drying the granules, the complexity of the process, which increases capital and operating costs.

Disclosure of the invention.

The objective of the invention is to increase the efficiency of the production process of peat pellets through the use of frozen raw sod peat for processing with a moisture content of 50% or less.

The moisture content of peat in the summer, spring and autumn periods of the year is 87 - 90%, however, in winter, when peat is taken from a depth of at least 2.5 m, its moisture content is in the range 56 - 60%. When peat is folded into towers or toboggan vehicles, with the formation of drying figures with a height of at least 2 m, which are taken out of the production area, where they are subjected to intensive low-temperature weathering and freeze-drying, the moisture content of peat drops to 50% or less, which is established by actual studies on Mitoginsky peat deposit (Ust – Bolsheretsky municipal district of Kamchatka Krai) in 2016. This makes peat extraction in the winter period the most rational. In addition, in the winter season, it is possible to extract raw peat in hard-to-reach or even inaccessible deposits for development in the summer.

The technical result of the claimed invention is to reduce operational, capital costs and cost of produced peat fuel pellets.

This is achieved by the fact that peat with a moisture content of 50% or less, extracted in the winter season, is delivered to the place of its processing (production workshop), where it is crushed in a frozen state, subjected to convection drying with air to a moisture content of 20% for 9-23 minutes, and additional grinding to a particle diameter of 3 - 5 mm in a drying drum. For drying, hot dry air with a temperature of 200 - 250 ° C is used. After drying, peat particles with a temperature of 110 ° C are air-cooled to a temperature of 30 - 32 ° C, and then transferred to a granulator (pelletizer), where peat pellets with a diameter of 8 are obtained by pressing and forcing through a perforated ring matrix (diameter) mm Granules (pellets) are placed in open mesh pallets and stored at normalized parameters of the internal air of the production workshop. During storage, the moisture content of peat pellets is reduced to 10-12%. The air leaving the drying drum with a temperature of 120 - 130 ° C, as well as the air from the cooling zone of the granules, passing together through the heat exchanger used to heat the production hall, are discharged into the atmosphere.

Compared with the prototype of the invention, where additional operations are used, such as pneumatic separation and heating of peat raw materials during the grinding process, in the present invention due to the low humidity delivered to the processing site of peat, it is better to be ground, does not require heating, as in the prototype. In view of this, the duration of the thermal operation is significantly reduced, as the most energy-intensive and affecting the cost of the product. In addition, in the claimed invention applied restorative in the production hall, which will also reduce energy costs for the production of 1 kg of the finished product. Drying of peat granules in a drying drum to a moisture content of 20% is due to jamming of peat in a perforated ring matrix when peat pelleting with a moisture content of up to 15% [5].

Description of the drawings.

In FIG. 1 shows a scheme for producing peat granules from frozen peat.

The implementation of the invention.

The invention contains a list of technological operations: transportation of ice-cream peat, grinding peat in a frozen state, convection drying and grinding, air cooling of peat particles, production of granules (pellets), storage of granules in a production workshop, packaging.

The invention works as follows.

Example 1

Frozen peat with a moisture content of 50% or less is transported along the winter snowy passage to the place of its processing (production workshop). In the workshop, peat is crushed in a frozen state, in a rotary disk chopper to dimensions (length, width, height) - 10 × 10 × 10 mm. Next, the ground peat is subjected to convection drying with hot air to a moisture content of 20% and additional grinding (particle diameter 3 - 5 mm) in a drying drum. The temperature of the incoming dry air in the drum is 250 ° C, and the outlet 120 - 130 ° C. The duration of the drying process is 9 to 12 minutes. From a drying drum, peat particles with a temperature of 110 ° C enter the chamber, where they are cooled to a temperature of 30 - 32 ° C by blowing air from a production workshop with a temperature of 23 ° C. The air temperature at the outlet of the cooling chamber of peat granules 72 - 75 ° C. Then, the cooled peat particles are transferred to a granulator (pelletizer), where in the process of pressing and forcing through a perforated ring matrix, peat fuel granules (pellets) with a diameter of 8 mm are obtained. In the process of pressing and obtaining granules, the temperature of peat increases and reaches 38 - 43 ° C. Then the pellets are placed in open mesh pallets and stored for normalized parameters of the internal air of the production workshop at 23 ° C and a relative humidity of 50% (ambient temperature). During storage, the moisture content of peat pellets is reduced to 10-12%. After the pellets are packed. The air leaving the drying drum with a temperature of 120 - 130 ° C, as well as the air from the cooling zone of the granules with a temperature of 72 - 75 ° C, together enter the heat exchanger used to heat the production hall, and then are discharged into the atmosphere.

Example 2

Frozen peat with a moisture content of 50% or less is transported to the processing site, crushed, subjected to convection drying and additional grinding, cooled, pressed according to Example 1, however, the temperature of the incoming dry air into the dryer drum is 200 ° С, and the temperature of the outlet air is 120 ° С, the duration of the drying process increases and is 19 - 23 minutes.

Example 3

Frozen peat with a humidity of 50% or less is transported to the processing site, crushed, subjected to convection drying and additional grinding, cooled, pressed according to examples 1 and 2, however, the temperature of the incoming dry air into the drum is 180 ° C, and the output temperature is 110 ° C, the duration of the process drying increases and is 28 - 30 minutes The temperature of the peat granules after drying in a drum is 100 ° C. With such a high duration of drying, the continuity of technological operations is violated. The moisture content of peat particles increases to 30% at the outlet of the drying drum, which will increase the duration of drying in open mesh pallets by the air of the production workshop.

Example 4

Frozen peat with a moisture content of 50% or less is transported to the processing site, crushed, subjected to convection drying and additional grinding, cooled, pressed according to Example 3, however, the temperature of the peat particles exiting the dryer drum is 85 ° C and the duration of the drying process is 21 min. With this production method, the moisture content of peat particles after drying is 32 - 36%, which will increase the drying time in open mesh pallets by the air of the production workshop.

The invention is simple to implement and can be applied on standard equipment. The experiments conducted in order to obtain peat fuel pellets in certain parts of the technological process of the claimed invention prove its industrial applicability.

Sources of information

1. SU 664988, publ. 05/30/1979. Bull. No. 20.

2. SU 1745947, A1, publ. 07/07/1992. Bull. Number 25.

3. RU 2103511, C1, publ. 01/27/1998 (Date of patent termination: 07/11/1998).

4. RU 2018672, C1, publ. 08/30/1994 (Date of patent termination: 01/12/2004).

5. SU 1747466, A1, publ. 07/15/1992. Bull. No. 26.

Claims (1)

Method for the production of fuel pellets from frozen peat, including transportation, grinding, drying, granulation, cooling by blowing with air to a temperature close to ambient temperature, moving to a long-term storage or packaging zone, characterized in that frozen peat with a humidity of 50% or less, extracted in the winter season, it is delivered to the place of its processing, where it is crushed in a frozen state, subjected to convection drying with air to a moisture content of 20% for 9-23 minutes and additional grinding to a particle diameter of 3-5 mm in a drying drum, where it is used for drying hot dry air with a temperature of 200 - 250 ° С, from where peat particles with a temperature of 110 ° С come to cooling to a temperature of 30 - 32 ° С and then move to a granulator (pelletizer), where during pressing and punching through a perforated ring matrix peat is obtained fuel granules (pellets), with a diameter of 8 mm, which are placed in open mesh p pallets are stored at normalized parameters of the internal air of the production workshop, where during storage the moisture content of peat pellets is reduced to 10 - 12%, while the air leaving the dryer drum with a temperature of 120 - 130 ° C, as well as the air from the pellet cooling zone, passing together through the heat exchanger used to heat the production hall, are discharged into the atmosphere.

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