DK201170613A - A dischager and a method for removing solid material from a reactor in wich a process is progressing under pressure of a gas - Google Patents

Abstract

A discharger serves for in a number of operational steps removing material from a reactor in which a process is progressing under pressure of a gas. The discharger (D) has an inlet (IN) for in a first operational step letting the material into the discharger at one pressure and an outlet (OU) for in a finally operational step letting the material out of the discharger at a lower pressure. The operational steps ifl between are adapted to secure that the outlet pressure is lower than the inlet pressure. By means of the discharger according to the invention can material easily, quickly and safely be removed from a reactor producing high-pressure gas.

Description

The invention relates to a discharger adapted to cyclic discharge portions of a material from a reactor in which a process is progressing under pressure of a gas. The discharger comprises an inlet for allowing gas and material from the reactor to enter the discharger at the start of a cycle and an outlet through which the material is leaving the discharger at the end of the cycle.

The invention also relates to a method for by means of the discharger of the invention cyclic discharging portions of material from a reactor.

The invention further relates to the use of the discharger and of the method of the invention.

The material to be discharged can be pieces of solid material such as ash or slag, viscous materials such as tar, liquid materials such as water or combinations of such materials.

As an example only of a reactor in which a process is progressing under pressure of a gas can be mentioned a gasifier for gasifying carbonaceous raw material such as fossil fuels, biomass or waste gasified at high pressures such as 81 bars and high temperatures such as 700 ° C while producing combustible gas and incombustible residuals, such as ash and slag.

Said residuals need to be removed from the gasifier since the gasification process would otherwise come to a standstill or at least no more would be able to function in a satisfactory way.

However, removing the residuals from the gasifier is a difficult task, which could be dangerous too owing to the high temperature and high pressure of the process carried out in the gasifier.

It is therefore necessary to decrease the pressure of gas before letting residuals from the process in a gasifier out of a discharger and that is necessary also regarding other kinds of rectors in which a process is progressing under pressure of a gas.

During the years many attempts have been made to solve the serious problem mentioned above by decreasing the pressure before discharging material from a reactor.

Thus, from US application 4463686 an upright apparatus for dry removing hot residues from a gasification of coal in a gasifier is known. The apparatus is connected to the lower region of the gasifier via a constricted throat. The residues are cooled in different ways during downward passage of the apparatus. This known technique is more or less dangerous to use since the residues are discharged without previously decreasing the pressure. DE application 4032747 discloses a sluice for wet removing residues such as ash and slag from a gasifier. The sluice consists of an upper and lower compartment separated by a central valve. The upper compartment is moreover equipped with an upper valve between the gasifier and the upper compartment while the lower compartment is equipped with a lower valve between the lower compartment and a recipient.

The sluice functions in such a way that the residues are first filled into the upper compartment after which the upper valve is closed and a throttle valve opened to reduce the pressure in the upper compartment to a certain level.

The central valve is opened when this level is achieved so that the residues fall into a volume of water in the lower compartment after which the central valve is closed and a throttle valve opened to reduce the pressure in the lower compartment to a desired level .

The lower valve is opened when this level is achieved so that the water with the residues falls into a receiver for the residuals.

This sluice suffers from the problem that it is very voluminous and therefore expensive at the same time as it has a low capacity owing to the fact that decreasing the high pressure in the gasifier to e.g. The ambient pressure is a slow process when it takes place by means of throttle valves.

Another problem is that it is difficult, time consuming and costly to separate the water from the ash.

The above-mentioned disadvantages of the prior art dischargers for removing material from a reactor in which a process is progressing under pressure of a gas are, according to the invention, remedied by, in a first aspect of the invention providing a discharge of the child mentioned in the opening paragraph which in an inexpensive way easily, quickly and safely is capable of drying material from a process carried out in a reactor under pressure while at the same time decreasing the pressure and compaction the material, in a second aspect of the invention a discharger of the child mentioned in the opening paragraph which has a simple and inexpensive structure, in a third aspect of the invention providing a discharger of the child mentioned in the opening paragraph which has a compact structure, in a fourth aspect of the invention a discharger of the child mentioned in the opening paragraph which has a large capacity, in a fifth aspect of the invention providing a metho d for by means of a discharger of the child mentioned in the opening paragraph removing material from a reactor, in which a process is progressing under pressure of gas, in such a way that the pressure is decreased.

The novel and unique features wherein these and further advantageous aspects of the invention are achieved consists in the fact that the discharger comprises at least one first compartment which is connected to the inlet via a first opening and to the outlet via a second opening, a first piston which is displaceable to-and-fro between the first and second opening is placed in said at least first compartment, a first valve for opening and closing the first opening and a second valve for opening and closing the second opening, at least one second compartment which at one end is connected to the first compartment via a third opening while the other end of the second compartment is closed, a second piston displaceable to-and-fro between the third opening and another position is placed in said at least second compartment , a third valve for opening and closing the third opening, and a fourth valve for opening and closing the outlet.

In addition, the material to be removed from the reactor can be safely and easily discharged into a receiver, which may be another reactor or the environment.

The discharger of the invention can, for being securely, effectively and precisely operated, comprise a first actuator for displacing the first piston in the first compartment and a second actuator for displacing the second piston in the second compartment and a control unit for in such a way controlling the first and second actuators and the first, second and third valves also that a portion of material and of gas at the process pressure are let into the discharger via the inlet for each cycle and that said portion of material is let out of the discharger via the outlet at a lower gas pressure than the process pressure.

The control unit can, according to the invention, be a computer with a program representing the sequences of motions which the pistons have to carry out during each cycle, and the discharger can, according to the invention, be moreover equipped with instruments for measuring the pressures in the compartments and the displacement of the pistons in the compartments and be adapted to signal the measuring results as input to the computer for currently adjusting the program of this in agreement with said measuring results.

Furthermore, it is advantageously obtained that the discharger all the time is functioning optimally even if the quantities and conditions of the material to be removed are changed rapidly.

According to the invention for each cycle, the discharger can be operated in steps starting with the step of letting a portion of material and gas at the process pressure into the first compartment via the inlet and ending with the step of letting said portion of material out of the discharger via the outlet whereby the steps in between are adapted to ensure that the pressure at the end of the cycle is lower than at the start of the cycle so that the material can advantageously be discharged without any risk.

The first step can, according to the invention, be carried out by opening the first opening while the second, third and fourth opening are closed whereby gas and material to be discharged from the reactor is entering the first compartment of the discharger.

According to the invention, the second step can be carried out by partially closing the first opening and displacing the first piston forwards in the first compartment while the second, third and fourth opening are closed.

Furthermore, it is achieved that the introduced material is pushed along the first compartment simultaneously with being compressed to a larger density and that most of the gas is advantageously pressed back to the process through the partially open first opening.

According to the invention, the third step can be carried out by fully or partially opening the third opening between the first and second compartments while the first, second and fourth opening are closed.

It is also achieved that that gas and possibly also some material are flowing through this fully or partially open third opening from the first compartment, where the gas pressure is at the level of the process pressure in the reactor, to the second compartment where the gas pressure is lower whereby the gas pressure in the first compartment decreases while the gas pressure in the second compartment increases.

The fourth step can, according to the invention, be carried out by fully or partially opening the second opening and displacing the first piston further forwards while the first, third and fourth opening is closed causing the compacted material to fall down into the closed outlet.

According to the invention, the fifth step can be carried out by displacing the first piston backwards in the first compartment and partially closing the second opening while the first, third and fourth openings are closed whereby the gas in the first compartment is expanded so that the the gas pressure in this compartment is decreased and the gas pressure in the outlet is increased to the same level.

The sixth step can, according to the invention, be carried out by opening the fourth opening while the first, second and third openings are closed resulting in the material leaving the discharger through the open outlet at a pressure which has been decreased during the previous operational steps.

According to the invention, the seven step can be carried out by opening the third opening between the first and second compartments while the first, second and fourth openings are closed whereby the gas pressure in the first compartment is increased and the gas pressure in the second compartment is decreased until the gas pressure in the two compartments is at the same level.

The eight step can, according to the invention, be carried out by opening the third opening, and displacing the second piston forwards in the second compartment while the first, second and fourth openings are closed whereby gas and material introduced into the second compartment from the first compartment during the third operational step are pressed back to the first compartment through the open third opening.

The ninth step can, according to the invention, be carried out by displacing the second piston backwards in the second compartment while the first, second and third openings are closed so that the gas pressure in the second compartment is reduced to a low level.

The tenth step can, according to the invention, be carried out by opening the first opening while the second, third and fourth openings are closed whereby the pressure in the first compartment is increased to the process pressure and the discharger then is brought into position for starting and a new cycle.

The invention will be explained in greater detail below, giving further advantageous features and technical effects and showing the successive operations steps of an exemplary embodiment with reference to the drawing, in which

FIG. 1 shows a cross section of the discharger according to the invention in a first operational step,

FIG. 2 shows the same in a second operational step,

FIG. 3 shows the same in a third operational step,

FIG. 4 shows the same in a fourth operational step,

FIG. 5 shows the same in a fifth operational step,

FIG. 6 shows the same in a sixth operational step,

FIG. 7 shows the same in a seventh operational step,

FIG. 8 shows the same in an eight operational step,

FIG. 9 shows the same in a ninth operational step, and

FIG. 10 shows the same in a tenth operational step.

The discharger of the invention is adapted to remove material from a reactor in which a process is progressing under pressure of a gas.

In the following detailed description of the invention it is assumed by way of example that the reactor is a gasifier (not shown) for gasifying carbonaceous material such as fossil fuels, biomass and waste at high temperature and under high pressure.

During the process in the gasifier combustible gas is produced and also incombustible residues in the form of ash and slag, which in this example are discharged to the environment at ambient pressure.

However, it is noted that the residues within the scope of the invention may be discharged to any suitable receivers and at the same or different pressure than the ambient pressure.

The residues in this case are solid material. The pressure therefore is to be understood as the pressure of the gases which simultaneously with the residues will enter the discharger from the inlet during operation.

Discharging residues from a gasifier or other such reactors which is being in progress at high pressures is difficult and could be dangerous too unless the pressure is decreased at least substantially before the residues are let out to a receiver, e.g. the environment.

The discharger of the invention is therefore adapted to cyclic removal of residues from a gasifier in such a way that the pressure of gases entering the discharger simultaneously with the residues is decreased for each cycle to a sufficiently low pressure.

The discharger D of the invention shown in FIG. 1 - 10, comprises an inlet IN for allowing gas and portions PO of residues from the process in the gasifier to enter the discharger at the start of a cycle and an outlet OU through which the residues are leaving the discharger at the end of the cycle.

The discharger further comprises a first compartment Cl, which is connected to the inlet IN via a first opening 01 and to the outlet OU via a second opening 02. A first piston PI is slideable placed in the first compartment Cl and a first actuator A1 serves for displacing the first piston PI to-and-fro in the first compartment Cl during operation.

The discharger also comprises a second compartment C2, which at one end is connected to the first compartment via a third opening 03 while the other end of the second compartment is closed. A second piston P2 is slideably placed in the second compartment C2 and a second actuator A2 serves to displace the second piston P2 to-and-fro in the second compartment C2 during operation. A first valve VI serves for during operation to open and close the first opening 01 between the first compartment Cl and the inlet IN. In this case, the valve VI consists of a compartment C3 with a piston P3 actuated during operation by an actuator A3. A second valve V2 serves to open and close the second opening 02 during operation between the first compartment Cl and the outlet OU. The valve V2 consists of a compartment C4 with a piston P4 actuated during operation by an actuator A4. A third valve V3 serves for opening and closing the opening 03 between the first compartment C1 and the second compartment C2 during operation. The valve V3 consists of a compartment C5 with a piston P5 actuated during operation by an actuator A5. A fourth valve V4 serves for during operation to close the opening 04 of the outlet for thereby hindering the portion PO of residues ASH to leave the outlet OU and to open the opening 04 for allowing the portion PO of residues ASH to leave the outlet OU.

The compartments 03, 04 and 05 of the valves VI, V2 and V3 are debouching all in the first compartment Cl.

Each of the valves VI, V2 and V3 can be of any other suitable kind within the scope of the invention e.g. be a disc valve.

The fourth Valve V4 is such a disc valve but can be within the scope of the invention of any other kind, e.g. of the kind shown above in the form of valves VI, V2 and V3.

As mentioned above, the gas pressure in an operating gasifier is very high and in the example described below as high as 81 bars. This high pressure needs to be reduced to about one bar during the residues passing through the discharger from the inlet to the outlet since the residues in this case are discharged to the environment where the pressure is only the atmospheric pressure.

The reduction of the starting pressure takes place by displacing the pistons PI and P2 to-and-fro in their respective compartments Cl and 02 in such a way that the pressure in successive operational steps is changed until the pressure in the outlet has been one bar.

The first of these operational steps of a cycle is shown in fig. 1 where valve VI has opened the first opening 01 between the inlet IN and the first compartment Cl while the second, third and fourth opening, 02, 03 and 04 are closed whereby gas and a portion PO of residues ASH in the form of ash and slag to be discharged from the gasifier (not shown) is entering the first compartment.

The pressure in the first compartment Cl is 81 bars now. In the second compartment C2, the pressure is 0.1 bar, which low pressure was generated during the operational step 9 of the previous cycle. The pressure in the outlet OU is 1 bar since the opening 04 of the outlet OU has been opened during the operational step 6 of the previous cycle for letting a portion PO of the residues ASH out of the outlet OU while the opening 02 between the first compartment Cl and the outlet OU is closed.

The second of the operational steps is shown in fig. 2 where the first valve VI partially closed the first opening 01 and the second, third and fourth openings 02, 03 and 04 are closed. The first piston Pi is moreover displaced forwards in the first compartment Cl during whish most of the gas is pressed back into the inlet through the only partially open first opening 01 and the portion PO of the residues ASH is compressed to a larger density.

The gas is able to pass the only partially open first opening 01 into the inlet IN while the residues ASH, at least in all essentials, are not able to pass in the opposite direction from the inlet IN.

The pressure in the first compartment Cl still is 81 bars, in the compartment C2 0.1 bar and in the outlet OU 1 bar.

The third of the operational steps is shown in fig. 3 where the third valve V3 partially opens the third opening 03 between the first and second compartments Cl and C2 while the first, second and fourth openings 01, 02 and 04 are closed, resulting in that gas at the pressure of 81 bar in the first compartment

Cl is flowing through the partially opened third opening 03 into the second compartment C2 where the pressure is 0.1 bar whereby the pressure in both compartments Cl and C2 is equalized to 8 bar. The pressure in the outlet OU is still 1 bar.

The gas can easily flow through the third opening 03 even if it is partially open only but not the residues ASH so that very little of this material if any is passed into the second compartment C2 simultaneously with the gas.

The fourth of the operational steps is shown in fig. 4 where the second valve V2 has opened the second opening 02 while the first, third and fourth opening 01, 03 and 04 are closed and the first piston PI has been displaced further forwards causing the portion PO of residues ASH to fall down into the closed outlet OU.

The pressure in the first compartment Cl and the outlet OU by equalizing the second opening 02 has been equalized to 2 bars while the pressure in the second compartment is still 8 bars.

The fifth of the operational steps is shown in fig. 5 where the second valve V2 partially closed the second opening 02 while the first, third and fourth openings are closed and the first piston PI is displaced backwards in the first compartment Cl.

The pressure in the first compartment Cl and the outlet OU by equalizing the second opening 02 has been equalized to 1 bar while the pressure in the second compartment is still 8 bars.

The sixth of the operational steps is shown in fig. 6 where the second valve V2 fully closed the second opening 02 while the first and third openings are closed and the fourth valve V4 has opened the fourth opening 04 resulting in the portion PO of the residues ASH falling out through the open outlet OU to the environment at ambient pressure. The pressure in the first compartment 1 is 1 bar and in the second compartment C2 is still 8 bar.

The seventh of the operational steps is shown in fig. 7 where the third valve V3 has opened the third opening 03 between the first and second compartments Cl and C2 while the first, second and fourth openings 01, 02 and 04 are closed whereby the gas pressure in the first compartment is increased and the gas pressure in the second compartment is decreased until the gas pressure in both compartments is 5 bars. The pressure in the outlet is still 1 bar.

The eight of the operational steps are shown in fig. 8 where the second piston P2 is displaced forwards in the second compartment 02 while the second opening 03 is open and the first, second and fourth openings are closed whereby gas and residues if any are pressed over into the first compartment Cl through the open third opening 03. The pressure in the first and second compartments Cl and 02 is both 9 bars and in the outlet 1 bar.

The ninth of the operational steps is shown in fig. 9 where the second piston P2 is displaced backwards in the second compartment 02 while the first, second and third openings 01, 02 and 03 are closed whereby the gas pressure in the second compartment 2 is decreased to 0.1 bar.

The tenth of the operational steps is shown in fig. 10 where the first valve has opened the first opening while the second, third and fourth openings have been closed whereby the pressure in the first compartment Cl is increased to the process pressure and the discharger then is ready for starting the next cycle.

The specifications of the above described exemplary embodiment of the discharger D of the invention were:

Diameter mm Stroke mm

Piston PI 400 700

Piston P2 500 1500

Piston P3 600 700

Piston P4 500 700

Piston P5 500 1600

Pressure difference between inlet and outlet 80 bars.

Cycle time 60 sec.

Mass flow 4-6 t / h in dependence of the material density.

Claims (16)

1. A discharger is adapted to cyclic discharging portions (PO) of a material (ASH) from a reactor in which a process is progressing under pressure of a gas, which discharger (D) comprises an inlet (IN) for allowing gas and material (ASH) from the reactor to enter the discharger (D) at start of a cycle and an outlet (OU) through which the material (ASH) is leaving the discharger (D) at the end of the cycle, characterized in that the discharger (D) comprises, at least one first compartment (Cl) which is connected to the inlet (IN) via a first opening (01) and to the outlet (OU) via a second opening (02), a first piston (Pi) which displaceable to-and-fro between the first and second opening (01, 02) is placed in said at least first compartment (Cl), a first valve (VI) for opening and closing the first opening (01) and a second valve (V2) for opening and closing the second opening (02), at least one second compartment (C2) which at one end is connected to the first compartment (Cl) via a third opening (03) while the other end of the second compartment (C2) is closed, a second piston (P2) which displaceable to-and-fro between the third opening (03) and another positioning is placed in said at least second compartment (C2), a third valve (V3) for opening and closing the third opening (03), and a fourth valve (V4) for opening and closing the outlet (OU) .

2. A discharger according to claim 1, characterized in that the discharger (D) comprises a first actuator (Al) for displacing the first piston (PI) in the first compartment (Cl) and a second actuator (A2) for displacing the second piston (P2) in the second compartment (C2).

3. A discharger according to claim 2, characterized in that the discharger (D) comprises a control unit for in such way controlling the first and second actuator (Al, A2) and the first, second and third valve (VI, V2, V3) too that a portion (PO) of material (ASH) and of gas at the process pressure are let into the discharger (D) via the inlet (IN) for each cycle and that the portion (PO) of material (ASH) is let out of the discharger (D) at a lower gas pressure via the outlet (OU).

4. A discharger according to claim 1, 2 or 3, characterized in that each of the valves (VI, V2, V3) is formed as a piston (P3, P4, P5) displaceable placed in each their compartment (C3, C4, C5) .

5. A method for by means of the discharger (D) according to claims 1-4 cyclic discharging portions (PO) of material (ASH) from a reactor in which a process is progressing under pressure of a gas, characterized in that the method comprises a series of operational steps carried out for each cycle starting with the step of letting a portion (PO) of material (ASH) and gas at the process pressure into the first compartment (Cl) via the inlet (IN) and ending with the step of letting the material (ASH) out of the discharger (D) via the outlet (OU) whereby the steps in between are adapted to secure that the pressure at the end of the cycle is lower than at the start of the cycle.

6. A method according to claim 5, characterized in that the starting step is carried out by opening the first opening (01) while the second, third and fourth openings (02, 03, 04) are closed.

7. A method according to claim 5 or 6, characterized in that the second step is carried out by partly closing the first opening (01) and displacing the first piston (PI) forwards in the first compartment (Cl) while the second, third and fourth openings (02, 03, 04) are closed.

8. A method according to claim 5, 6 or 7, characterized in that the third step is carried out by fully or partly open the third opening (03) between the first and second compartment (Cl, C2) while the first, second and fourth openings (01, 02, 04) are closed.

9. A method according to any of the claims 5-8, characterized in that the fourth step is carried out by fully or partly open the second opening (02) and displacing the first piston (PI) further forwards while the first, third and fourth openings (01, 03, 04) are closed .

10. A method according to any of the claims 5-9, characterized in that the fifth step is carried out by partly closing the second opening (02) and displacing the first piston (PI) backwards in the first compartment (Cl) while the first, third and fourth openings (01, 03, 04) are closed.

11. A method according to any of the claims 5 - 10, characterized in that the sixth step is carried out by opening the fourth opening (04) while the first, second and third openings (01, 02, 03) are closed.

12. A method according to any of the claims 5 - 11, characterized in that the seventh step is carried out by opening the third opening (03) between the first and second compartments (Cl, C2) while the first, second and fourth openings (01, 02, 04) are closed.

13. A method according to any of the claims 5 - 12, characterized in that the eight step is carried out by displacing the second piston forwards in the second compartment (C2) while the third opening (03) is open and the first, second and fourth openings (01, 02, 04) are closed .

14. A method according to any of the claims 5 - 13, characterized in that the ninth step is carried out by closing the third opening (03) and displacing the second piston backwards in the second compartment (C2) while the first, second, third and fourth openings (01, 02, 03, 04) are closed.

15. A method according to any of the claims 5 - 14, characterized in that that the tenth step is carried out by opening the first opening (01) while the second, third and fourth openings (02, 03, 04) are closed.

16. A use of the discharger (D) according to claim 1-4 and/or of the method according to claim 5-14 for removing pieces of solid material, viscous materials, liquid materials or combinations of such materials from a reactor in which a process is progressing under pressure of a gas .