CN1160418A

CN1160418A - Method and device for reducing water content of water-contg. brown coal

Info

Publication number: CN1160418A
Application number: CN95195219A
Authority: CN
Inventors: H·巴尔德赫莱
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-27
Filing date: 1995-09-26
Publication date: 1997-09-24
Also published as: DE59504443D1; FI971271A0; EP0784660A1; DE4434447A1; PL319381A1; EP0784660B1; FI971271A; CZ79597A3; AU3609695A; WO1996010064A1; JPH10506145A; HUT77187A; AU695187B2; TR199501177A2

Abstract

The invention concerns a method of reducing the water content of water-containing granular brown coal involving the application of heat energy and pressure to the material spread out in a bed. The brown coal is subjected to mechanically applied initial surface pressure at a level below the maximum surface pressure which occurs in the process, while thermal energy is imparted to the brown coal by steam, which heats the coal and condenses. The surface pressure is then raised without any further steam being supplied to a level (at least 2.0 MPa) at which the water held in the heated brown coal is forced out.

Description

Reduce the method and apparatus of the moisture in the moisture brown coal

The present invention relates to the material (coal) that heat energy and pressure act on horizontal distribution is gone up method and apparatus with the water-content that reduces aqueous particulate shape brown coal.

Having of disclosing in the past only is used for peaty use mechanical pressure and heat energy reduces fossil oil water-content method.Mud coal is a minimus natural fuel on the geology, and its feature is the moisture that contains up to 85-95%.Different with brown coal, mud coal also contains a certain amount of Mierocrystalline cellulose, so water only depends on faint power to combine with solid matter, thereby, just can remove the overwhelming majority's water with simple squeezing.A kind of these class methods in DE-PS 3 59 440, have been disclosed.The dewatering that this patent has been described mud coal etc. at first carries out precompressed to the material that will dewater, and with the plunger press material is pressed into thin layer, eliminate pressure after, material is placed under the high pressure steam, carry out last pressurization subsequently.The step of this method particularly important is that material is placed steam, is subjected to the chamber of containing material of press plunger boundary, owing to regain plunger, the material in it expands and the chamber of making expansion, thereby can make the cake piece of compression loose by this effect of steam.Because the ship cake piece is loose, the high pressure steam that above-mentioned steps is supplied with is easy to facilitate the path in the ship cake piece and pushes loose material open, can make a large amount of steam by again material there not being the passage of influence thereby form in material.By the precompressed of carrying out in the cold conditions of material, from material, discharge the expressible water of cold conditions, this water exists in a large number as surface water in mud coal.Yet, must be carefully guaranteeing under excess pressure, not carry out precompressed, otherwise the solid compressed cake piece that forms, as no further step, steam is difficult to pass through.

With regard to brown coal dehydrations, must imagine in the brown coal and do not contain free-water.Water can not cold conditions be squeezed out with the molecular conformation bonding in brown coal.

The moisture of brown coal is up to 65 weight %.When at the power plant burning brown coal, must be directly quite a large amount of brown coal of usefulness or with a large amount of heat energy transpiring moistures in the combustion gas.Used energy depends on water-content, can be up to 22%.If before burning, carry out effective dry and dehydration reduces moisture in the raw material brown coal, just can reduce the energy consumption of this respect.In addition, owing to the result of upstream drying step, can reduce the size of the boiler and the downstream unit in power station.For the brown coal with high-moisture change into electric energy, by the total efficiency in the energy favourable upstream measure that the dewaters raising greatly power station.

The method and apparatus that reduces water-content in the brown coal has been arranged, in the patent of " brown coal 39 (1987), the 3rd volume, 46-57 page or leaf " and " brown coal 39 (1987), Volume Four, 78-87 page or leaf " and citation therein, described these method and apparatus.These methods of mentioning have by the heated drying method of evaporation with to the hot evaporation (Flei β ner) that feeds superheated vapour in precharge to the brown coal in the autoclave of about 3.0MPa.Jia Re brown coal after taking out, move into a moisture-free coal warehouse from autoclave in this way, by the brown coal after the dehydration of secondary ventilation cooling heat, and carry out redrying.

The difficulty that adopts these methods to reduce the moisture in the brown coal in extensive power station is that equipment requirements and/or energy consumption are all very high owing to require high brown coal throughput.In hot dewatering,, fail industrialization so far although compare its specific energy consumption with heated drying lower.The shortcoming of heat dehydration is especially to continuous operation, must the applying pressure lock or rotary valve and high-pressure pump to brown coal reinforced and blowing.And, this hot dewatering, the saturated-steam temperature of the steam that its heating brown coal are required must be corresponding with the required high pressure phase of atmosphere of pressurizeing.

The objective of the invention is to avoid the defective in these methods by reducing the equipment of energy consumption and use.The feature of claim 1 of the present invention is used to reach this purpose.

By this heat/mechanical dehydration method, with less heat energy consumption and mechanical energy consumption, continuous or periodical operation can successfully make the brown coal dehydration.Under initial surface pressure, heating brown coal layer can cause physics and chemical action, makes that the bonded water molecules gets loose in the coal.Water just can flow out with liquid state from the kapillary of coal and space, and is easy to squeezing.Compare with the heated drying method, saved the required energy of vaporize water.

Compare with known hot dewatering, the most basic advantage of method of the present invention is not need pressure lock, valve or high-pressure pump in brown coal and dehydration continuous charging of brown coal and the blowing.Thereby eliminated the factor that may become source of trouble and cause dehydration operate continuously difficulty.According to the design of the inventive method, the saturated-steam temperature of input steam is lower than the saturated-steam temperature under the maximum surface pressure.And, because the filteration of brown coal layer and low saturated-steam temperature, solids content in the squeeze water and COD and BOD ₅The ratio of value is lower than the value of currently known methods.

The method according to this invention has satisfied the general requirement of industrialization dewatering, but low as cost of investment, floor space is little, the reliability height of high yield continuous operation, operation and equipment, to meet environmental protection requirement, process cost and energy consumption low.

In the operation before the rising surface pressure, must the even heating material, because the filter cake that material forms under initial surface pressure like this has uniform resistance to the steam that imports, and makes steam pass through material equably.Vapour pressure can have the identical order of magnitude of corresponding mechanical pressure such as 0.4MPa.

In order to make the material under present method adaptation specified conditions easily, when squeezing, can change the surface pressure, particularly pressure boost of brown coal.Confirmed that in this case, it is favourable to select maximum surface pressure to be at least about 2MPa.

Condensation when avoiding steam to enter material, it is overheated that steam needs.At least it is overheated 10 ℃ to want.Because overheated, even steam imports by conduit etc. the time and also condensation can not take place in advance.

In order to make steam high energy be arranged to material, material preferably is ground into the particle of the most about 20 millimeters granularity before its horizontal distribution.By preheated material, carry out the required energy of this method and can also reduce.For this purpose, can utilize the water that from material, squeezes in used heat or this method also to can be used as waste heat source.

For the advantageous conditions to effect that imports steam and the possibility of fully squeezing will be provided, material will distribute with the form of layer, and such center line average makes the pressure layer center line average after exerting pressure be at least about 0.2 meter.If brown coal make in this way, this means pressurization before, the scope of the center line average that distributes with the form of layer is approximately 0.4-1 rice.Confirm that after the pressurization, the pressure layer height of generation is the highest to be about 0.6 meter.

Will carry out this method as far as possible rapidly, preferably the mode that acts on consistently on the material with surface pressure is carried out.

Because the particulate state brown coal at wedge and applying under the initial surface pressure, disperse with the form of layer, finally form evenly filling, it is with the surface of uniform drag effect in the vapour stream exhibition bed of heating.

Add steam with suitable manner, make brown coal be heated to treatment temp at the condensing zone of steam, steam is in the plane that in fact is parallel to laminar surface, and arrives layer with the plane vertical diffusion.The steam input should be arranged in this manner, and when condensing zone reached the outer edge on surface, all material layer was heated.By this way, do not need complicated safety guard, just can avoid the leakage of steam.And can be effectively provide and make the material can outside effusive wall to material layer.

Utilization has the flowing property of layer of specified particle size layer and the advantage that produces for the precompression of carrying out this method by it, can successfully carry out the relevant brown coal of optimizing different collieries the dewater required treatment temp and the modification of rate of heating.This point can be by having the coal seam that low granularity coal forms, or when carrying out this method according to claim 20 with board-like press, by the coal seam that corresponding precompression layer changes, the resistance to flow that changes its tectum and/or bottom obtains.

Available continuous press carries out this method continuously with the pressurization that depends on the position, or intermittently carries out this method with board-like press with the pressurization that depends on the time.

Conveying belt is provided at the suitable equipment that continuous press on carry out continuous processing with the material of horizontal distribution and at it by double belt press that the material layer area surrounded increases the input field of compression and a plurality of steam input nozzles with accepting by having up and down.Having up and down, the double belt press of conveying belt can be used for as the continuous production chipboard.As in DE-A 40 10308, having disclosed this class double belt press.

In order to emit the water of squeezing with the suitable way of output, the conveying belt of lower floor of so at least double belt press has the through hole of the water that can draw squeezing.The upper strata conveying belt should be able to be regulated height, and the pressure transmission element that can regulate pressure is arranged.Like this, this double belt press just can be applicable to various operational conditions.

Also in order to add hot conveyer belt by further providing heat energy to solid matter.

In order to carry out this method with interval type, preferably use board-like press, board-like press has the wedge of the material that a pressure head and acceptable level distribute, and wedge should have the aperture that can import steam and the outlet of squeeze water at least.

When using flat press,, preferably also add thermal head and wedge for the material of giving this mode provides heat energy.

Method of the present invention and above-mentioned equipment also are applicable to the dehydration of mud coal and sewage mud.

With following reference and explanation embodiment the present invention is described.In the accompanying drawing

Fig. 1 provides the double belt press as continuous flow press,

Fig. 2 provides the flat press that is used to squeeze the operation of anterior diastema formula,

Fig. 3 provides the flat press in the press operation identical with Fig. 2.

Fig. 1 points out brown coal warehouse 1, and the brown coal of precomminution to decide granularity are wherein arranged.The steam of hot coal or the surface of hot water input tube or heat exchanger can be connected to coal warehouse 1 in advance.The brown coal of precomminution are distributed to the conveying belt of lower floor 2 that is illustrated by the broken lines by layer from coal bunker, and conveying belt of lower floor 2 is carried coal with direction shown in the arrow.The top of the conveying belt of lower floor 2 of double belt press as shown in the figure is a upper strata conveying belt 3, and it also dots (press belt) advances by the direction shown in the arrow, its speed and conveying belt 2 couplings.8 direction diminishes distance between the conveying belt 2 and 3 along the input field, and the pressure in coal seam 4 is raise.According to input and its water-content of brown coal,, can regulate the height of conveying belt 3 in its whole transmission process by the power that applies by pressure transmission element 5.A plurality of steam feed nozzles 6 in the emperipolesis coal seam 4 shown in the figure orbicular spot are housed between conveying belt 2 and 3, and the outlet aperture of steam feed nozzle is positioned at input field 8, and the pressure in coal seam is lower than the maximum surface pressure on conveying belt 2 and 3 herein.The steam that discharges from steam feed nozzle 6 gives coal with its heat, its condensation then.Owing to the steam distributing nozzle of many different lengthss and height has been installed, can have been guaranteed the suitable uniform heating in coal seam 4.

8 cause following chemistry and physical process with the heat effect simultaneously of rising pressure in the input field, and during this period, the colloidal structure of brown coal and the character of water change:

Physical process:

-even heating coal particle,

Breaking of-capillary pipe structure is accompanied by:

-plastifying brown coal volumetric shrinkage,

-texture of coal fixed,

-from the capillary pressure liquid water of squeezing out, by:

-with the expansion of water in the reduction coal of viscosity,

-because the result of front chemical process changes surface properties (wetting ability-hydrophobicity),

-remove and to deash, an alkali metal salt and become favourable particularly.

Chemical process:

Carbonic acid gas is emitted in the degraded of-oxygen-containing functional group,

-cause the thermolysis of brown coal, emit methane and higher molecular weight hydrocarbon.

Following factor has determined the dehydration of brown coal substantially:

-throughput or bed height,

-brown coal granularity,

-brown coal water-content,

-pressure,

-temperature,

-the residence time.

By the pressure or the temperature of the conveying belt 3 of regulating height and the superheated vapour of importing, but the setup parameter pressure and temperature is as the function of brown coal throughput, granularity and moisture.In first treatment zone (input field 8), pressurizeed in coal seam 4 by on conveying belt 3, applying the mechanical force that increases continuously.After reaching maximum surface pressure (it must be stipulated), fixed coal seam 4 enters following treatment zone, at there, is kept constant or is only slightly changed by upper strata conveying belt 3 applied pressures.The effect of the temperature of pressure and rising makes free and the water that discharges can 4 squeezings from the coal seam, and by conveying belt 2, also has the through hole 7 (through-holes) on the conveying belt 3 sometimes, discharges in one or more stages.The hot water of discharging by through hole 7 or the shunting of this water can be used for the preheating of brown coal.

Reach decide coal after the dehydration of water-content, arrive biobelt press terminal and discharge, be divided into the piece of pre-sizing by an equipment, and send it to pulverizer by the particular approach on the continuous conveyor, be crushed to the burning or the required granularity of vaporizing.

The flat press that Fig. 2 points out has wedge 9 and pressure head 10.Wedge 9 only is placed on the

bearing

11 and 12 with the sketch signal.Pressure head 10 be suspended on by the pressure assembly that do not provide among the figure raise or the plunger 13 that reduces on.The design of this press basically with former field in identical.

Wedge 9 is bathtub constructions, so solid material 14 can be therein with horizontal distribution.Wedge 9 and pressure head 10 have

water outlet

15 and 16,

steam inlet hole

21 and 22, and like this, in the flat press of sealing as shown in Figure 3, steam can enter solid material 14, and the water of discharge can be derived.By

groove

17 and 18,23 and 24, with

water outlet

15 and 16,

steam inlet hole

21 and 22 is connected to the bottom of wedge 9 and the end of pressure head 10, thereby the water of squeezing can flow out, and steam can enter solid material 14.

All placed a very

thin sieve

19 and 20 in the bottom of wedge 9 and the end of pressure head 10, sieve can allow water or steam pass through, but can prevent that solid material from entering

groove

17 and 18,23 and 24, so wedge and pressure head can not stop up.

Fig. 3 be flat press among Fig. 2 at the figure of off-position, pressure head 10 descends compression solid material 14 to wedge 9.When initial pressure on solid material 14 was lower than peak pressure, steam led into by steam that

hole

21 and 22 enters solid material 14, heat solid material 14.By pressure head 10 on solid material 14 effectively applied pressure be increased to peak pressure subsequently, squeeze out in the solid material 14 water that exists, and discharge by outlet 15 and 16.Can be with reference to the method for 1 pair of front of figure and result's explanation.

Because quite low installation cost, aforesaid method is suitable for the power station of particularly large-scale burning brown coal.And, using this method in the factory that uses brown coal, can increase as the density calorific value of moisture-free coal with the function of raw material brown coal water-content ratio, therefore can more effectively transport brown coal.

Claims

1. the material (coal) that heat energy and pressure are acted on horizontal distribution is gone up the method with the water-content that reduces aqueous particulate shape brown coal, it is characterized in that it is

A) machinery applies the initial surface pressure that is lower than in the treating processes the maximum surface pressure that can produce on brown coal, at this moment, provides heat energy with steam to brown coal, itself condensation behind the steam heating brown coal.

B) subsequently, no longer import steam, surface pressure is increased to 2.0MPa at least, make the moisture content in the brown coal after the heating be squeezed out.

2. the method for claim 1, its feature is that also this concrete mechanical pressure load is and the same order of magnitude of corresponding vapor pressure.

3. as the described method of arbitrary claim in claim 1 or 2, its feature also is can change the surface pressure, particularly pressure boost on the brown coal (4,14) in treating processes.

4. as the described method of arbitrary claim among the claim 1-3, its feature is that also steam is superheated vapour.

5. method as claimed in claim 4, its feature also are to want overheated 10 ℃ at least.

6. as the described method of arbitrary claim among the claim 1-5, its feature is that also brown coal (4,14) before its horizontal distribution, are crushed to the most about 20 millimeters granularity earlier.

7. as the described method of arbitrary claim among the claim 1-8, its feature also is brown coal (4,14) before it distributes with laminar, by the used heat preheating.

8. method as claimed in claim 7, its feature are that also employed waste heat source is the water that squeezes out from brown coal (4,14) in the treating processes.

9. as the described method of arbitrary claim among the claim 1-8, its feature is that also brown coal (4,14) are that stratification distributes, and the pressure layer center line average that pressurization back, coal seam produces is at least about 0.2 meter.

10. the height maximum after method as claimed in claim 9, its feature also are to pressurize is about 0.6 meter.

11. as the described method of arbitrary claim among the claim 1-10, its feature also is to apply continuously surface pressure on brown coal.

12. as the described method of arbitrary claim among the claim 1-11, its feature is that also the initial surface pressure of selecting is at least 0.2MPa, brown coal is formed fill, so that the steam that flows through bed face is had uniform resistance.

13. as the described method of arbitrary claim among the claim 1-12, its feature also is the plane condensing zone that the steam of importing should be able to make the heating of brown coal occur in to be parallel to bed face, this condensing zone advances to the coal seam with the direction perpendicular to bed face.

14. as the described method of arbitrary claim among the claim 1-13, its feature also is in order to obtain condensing zone propulsive optimum velocity in the coal seam, the maximum particle size of the coal in about 1/10th thickness of coal seam is limited in about 2 millimeters, so that resistance to flow increases apart from the bed face distance with bed.

15. as the described method of arbitrary claim among the claim 1-14, its feature also is to obtain the resistance to flow along with the variable in distance of distance bed face, applies the surface pressure of about 1MPa in advance at the cold volume that is equivalent to about 1/10th maximum bed heights.

16. as the described method of arbitrary claim among the claim 1-15, its feature also is

A) a kind of have a up and down double belt press of conveying belt (2,3) and input field (8), is used to accept the brown coal (4) of horizontal distribution and the compression of increase thereof,

B) (Fig. 1) by the many steam feed nozzles (6) in the input field (8) of bed (4) encirclement.

17. according to the equipment of claim 16, it is characterized in that on conveying belt of lower floor (2), having at least through hole (7), be used to discharge the water of squeezing.

18., it is characterized in that upper strata conveying belt (3) can regulate height, and the pressure transmission element (5) of adjustable pressure arranged according to the equipment of arbitrary claim in claim 15 or 16.

19., it is characterized in that to add hot conveyer belt (2,3) according to the equipment of arbitrary claim among the claim 16-18.

20. carry out equipment according to the described method of arbitrary claim among the claim 1-15, it is characterized in that flat press has pressure head (10) and wedge (9), wedge (9) is accepted the brown coal (14) of horizontal distribution, air inlet port (21 for input steam is arranged on the pressure head (10) at least, 22), at least be useful on the outlet (15,16) (Fig. 2,3) of the water that discharge squeezes out from brown coal (14) on the wedge (9).

21. equipment as claimed in claim 20, its feature also are to add thermal head (10) and/or wedge (9).