CN107532380B

CN107532380B - Method and apparatus for increasing the solids content of raw material, control device, installation for processing raw material and paper mill

Info

Publication number: CN107532380B
Application number: CN201680024697.3A
Authority: CN
Inventors: 于尔根·米尔克; 赫尔曼·施瓦茨
Original assignee: Siemens AG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2015-05-08
Filing date: 2016-04-26
Publication date: 2020-01-17
Anticipated expiration: 2036-04-26
Also published as: WO2016180627A1; CN107532380A; EP3271509A1; EP3091123A1; BR112017023372A2; EP3271509B1; BR112017023372B1

Abstract

The invention relates to a method, a device and a facility for increasing the solids content in raw material (1), in particular for increasing the solids content of black liquor (1) in the production of pulp for paper production, preferably an evaporation device, a control device and a paper machine for black liquor, having a plurality of vessels (G1, G2, G3, G4, G5) and at least one heat pump (WP, WP'), wherein thermal energy (Delta Q) for acting on the raw material (1) is provided for increasing the solids content. The starting material (1) is conveyed from the first container (G1) to at least one further container (G2, G3, G4) to the last container (G5). At least one heat pump (WP, WP ') is advantageously used to transport thermal energy (Δ Q) into at least one tank (G1, G2, G3, G4, G5) and at least one heat pump (WP, WP') extracts thermal energy (Δ Q) from a reserve tank (R) and/or from one of the tanks (G1, G2, G3, G4, G5). Thus, advantageously, a higher solids content of the raw material can be achieved.

Description

Method and apparatus for increasing the solids content of raw material, control device, installation for processing raw material and paper mill

Technical Field

The invention relates to a device for increasing the solids content in raw material, in particular for increasing the solids content of black liquor, preferably a black liquor evaporation device, comprising a plurality of vessels, wherein for increasing the solids content thermal energy is provided for acting on the raw material, wherein a passage of the raw material from a first vessel to a last vessel via at least one further vessel is provided.

The invention further relates to a method for increasing the solids content in raw material, in particular for increasing the solids content of black liquor in the production of pulp, preferably for evaporating black liquor, wherein the raw material is passed through a first container, then at least one further container, and then a last container, wherein thermal energy is applied to the raw material in order to increase the solids content.

In addition, the invention relates to a control device, a plant for processing raw materials and a paper mill.

Background

Such raw material is for example black liquor. Black liquor is precipitated when making pulp. Pulp is the initial product in the manufacture of paper. The large amount of lignin-containing water obtained by decomposing wood is called black liquor. Furthermore, the black liquor contains dissolved inorganic salts, such as sodium sulphide and magnesium oxide. The black liquor is advantageously removed (evaporated) from most of the water for energy extraction and the (solid) organic constituents of the black liquor (especially lignin and its derivatives) are subsequently burnt.

According to the current state of the art, black liquor is evaporated by means of (water) steam, wherein the black liquor is passed successively through a vessel, in which the solids content is continuously increased. The black liquor originating from the decomposition process is also called dilute lye and has a solids content of 10 to 15%. The purpose is as follows: the solids content of the black liquor is increased to approximately 80% after passing through the equipment used to increase the solids content.

DE 69520366T 2 describes a method and an apparatus for the sealed evaporation of black liquor.

US 5,509,977 describes the conversion of black liquor into gaseous matter which is subsequently burned in a recovery furnace and where a large amount of heat energy is provided.

Finally, EP 0334398 a2 describes a method for reducing deposits in a plant for evaporating a sulfidic liquid, in which the temperature in the individual stages of evaporation is reduced.

The defects of the prior art are as follows: the solids concentration of the black liquor after evaporation is also always not high enough for efficient and low harmful substance combustion.

Disclosure of Invention

The object of the invention is therefore: a method and an apparatus are provided which are capable of further increasing the solids content of the raw material.

The object is achieved by the device according to the invention and by the method according to the invention. Furthermore, the object is achieved by a control device according to the invention, by a plant according to the invention and by a paper mill according to the invention.

Raw material is understood here to be a suspension or solution of material in a liquid, for example black liquor.

However, here further, the starting material can also be understood as other aqueous residues which have organic compounds which can be more effectively burnt after the removal of the liquid for energy production.

By way of example, the organic constituents of the waste water (e.g. sludge) can likewise be used for the extraction of energy by means of the invention. In addition, by means of the invention, inorganic constituents can be recovered from the raw material.

A heat pump is understood to mean a device which transfers thermal energy from one reservoir or one container to another container or to a reservoir, wherein the temperature of the reservoir or container into which the thermal energy is transferred can be higher than the temperature in the container or reservoir from which the thermal energy originates.

Instead of a heat pump, a heat exchanger can also be used. The heat exchanger is used for: the thermal energy of the higher temperature container/reservoir/material is transferred to the lower temperature container or material.

The term vessel in this context is understood to mean a reaction vessel, a kettle, a short-tube evaporator, a long-tube evaporator, a falling-film evaporator or a pressure kettle. The container preferably has an inlet and an outlet, wherein the starting material is introduced into the container through the inlet and removed again from the container through the outlet. The individual vessels are connected to one another by means of pipes, wherein the vessels also have further inlet and outlet openings for the heat carrier.

The first container is understood here to be the container which is first penetrated by the starting material. The raw material is then passed through a further container. Finally, the raw material passes through the final container.

The heat carrier, in particular water vapor, passes through the container in the same direction as the raw material. The heat transfer medium can also be passed through the vessels in a parallel manner, i.e. a respective portion of the heat transfer medium is assigned to a respective one of the vessels. In each case, thermal energy is transferred from the heat carrier to the starting material. The raw material is heated by the transferred thermal energy and a part of the liquid of the raw material is evaporated. The evaporated part of the raw material can be separated from the raw material and the solids content is therefore higher after the container passed through.

The heat carrier preferably passes first through the first vessel, then through the further vessels and finally through the last vessel. In a further advantageous embodiment of the device or of the method, the heat transfer medium is passed through the container in the opposite direction. The heat transfer medium can also be guided in parallel through the vessel.

In an advantageous embodiment, the heat transfer medium is used to supply thermal energy to the raw material. A heat carrier is generally understood to mean a substance having a high temperature which is suitable for transporting thermal energy, in particular via a heat exchanger, to a container.

It is also possible to: through which the heat carrier and/or the raw material are passed for another pass. For example, the heat carrier with the highest temperature is used for heating this one vessel through which the raw material neither passes first nor last. After this vessel, a further vessel is subjected to the heat carrier in a serial and/or parallel flow direction.

Advantageously, the starting material is first passed through the first container, then through at least one further container up to the last container. In each container that is passed through, the solids content of the raw material is increased. Thus, the low concentration (e.g. 10% to 20%) solids content is further enhanced by evaporating more water or other liquid in each vessel so that after leaving the last vessel the raw material has a solids content of more than 70%.

The (at least one) heat pump serves to increase the temperature of the raw material and/or the heat carrier in the at least one container, in particular to exceed the temperature of the heat carrier and/or the raw material.

By using a heat pump it is possible to: increasing the temperature in the vessel or vessels to such an extent that the increase in the solids content of the raw material can be carried out more efficiently.

The thermal energy for further increasing the solids content of the raw material in one container is here either taken from another subsequent container or taken from a reserve, for example a reserve of excess thermal energy from another processing step of the raw material.

The method is characterized in that: thermal energy is introduced into the at least one tank by means of at least one heat pump, and the at least one heat pump extracts thermal energy from a reserve and/or one of the tanks. In the process described herein, the effect of thermal energy on the raw material is also used to increase the solids content by reducing the specific gravity of the liquid in the raw material.

The control device is advantageously used for controlling and/or regulating the method described here, wherein the sensors are provided for determining the temperature in the vessels, the temperature of the heat carrier, the solids content of the raw material and/or the pressure value in the respective vessel, and wherein the control device is provided for controlling and/or regulating the at least one heat pump as a function of the temperature, the solids content of the raw material, the pressure value in the respective vessel.

The sensor transmits the determined value to the control device via the engineering data connection. The control device preferably adjusts the delivery of thermal energy for the heat carrier and/or for the raw material in view of the determined value according to an algorithm that maximizes the solids content after the raw material has passed through the vessel. The control device can be integrated into a control system of a facility, in particular of a paper mill or a part thereof.

In an advantageous embodiment of the device, the reserve is excess thermal energy which accumulates during the production or processing of the raw material. The reserve can be used as a storage of thermal energy.

Advantageously, not only is energy saved by the invention, but also the possibility is provided to increase the solids content when evaporating the raw material.

With an increased solids content, the combustion of the black liquor residue results in less sulphur dioxide in the combustion exhaust gases.

In a further advantageous embodiment, the heat pump transports the thermal energy through the individual containers in a direction opposite to the direction of travel of the raw material.

The heat pump transports a portion of the thermal energy, for example, from the last container to the penultimate container. In this case, the heat pump can extract a portion of the thermal energy from the heat carrier and/or a portion of the thermal energy from the raw material.

In addition, the heat pump and/or the further heat pump can transfer heat from the at least one container into the at least one further container.

By means of this embodiment, the temperature of at least one of the containers can be increased, and the solids content of the starting material can be increased further by means of the device.

In a further advantageous embodiment of the system, the vessels are provided for increasing the solids content of the starting material in steps, wherein the temperature of the starting material and/or the heat transfer medium is higher in the first vessel than in the last vessel.

The gradual reduction of the temperature in the vessel consists in the transfer of thermal energy (by means of a heat carrier) to the raw material in the vessel. When the solids content of the raw material is increased in a vessel, thermal energy is extracted from the heat transfer medium. The heat carrier is transferred from the first container into a further container, wherein thermal energy is also extracted from the heat carrier in the further container, and the solids content of the starting material is further increased by means of the extracted thermal energy.

The temperature of the raw material in the last container traversed by the raw material is therefore lower than in the first container, where the raw material is heated by means of the "unconsumed" heat carrier.

It is therefore advantageous: the heat energy is transferred to the individual containers in such a way that the solids content is increased as efficiently as possible.

In a further advantageous embodiment of the device, the heat pump is provided for transporting thermal energy from the last container into the further container. In particular, the container that passes through before the last container is provided as a further container. This embodiment of the device makes it possible to: the temperature increase is achieved in the vessel before the last vessel is passed through by: i.e. heat energy is extracted from one or the previous container and transferred to the respective other container. An effective increase in the solids content of the raw material can be achieved by increasing the temperature at which the heat energy is transported.

In this embodiment, it is also advantageously possible to obtain an extremely high solids content of the starting material by means of a limited number of containers, for example five containers.

In a further advantageous embodiment of the device, the device has at least one sensor and a control device, wherein the control device and/or the sensor is/are provided for controlling and/or regulating the supply of thermal energy into the at least one container.

Advantageously, the at least one heat pump is controlled or regulated by means of the control device such that the solids content is increased during the limited transport of thermal energy. The sensor is used in particular for determining the solids content of the raw material in the container, for determining the temperature of the raw material and/or the heat carrier in one of the containers, for determining the pressure of the raw material and/or the heat carrier in the container.

By means of a possible solution of the control according to the parameters previously implemented, an efficient use of thermal energy can be used for increasing the solids content of the raw material. In particular in the case of a limited reserve of thermal energy, the control device is advantageous for using the thermal energy as efficiently as possible.

The control or regulation of the at least one heat pump by means of the control device can be carried out by comparing the transferred thermal energy with a simulation. In this case, for example, methods for increasing the solids content of the starting material are simulated, and the results of the simulation form the basis for controlling or regulating the heat pump.

Advantageously, a constantly constant high solids concentration can be ensured by means of this embodiment.

In an advantageous embodiment of the method, the heat energy is transferred from the last container to the penultimate container. The penultimate container is understood to be the container through which the starting material passes before entering the last container.

In a further advantageous embodiment of the method, a heat pump is used to transfer thermal energy from a reserve into the container, in particular into the container which is finally traversed by the raw material. The further heat pump can optionally transfer thermal energy from the last tank and/or the reserve to at least one further tank, in particular the penultimate tank.

This advantageous embodiment achieves a significant increase in the temperature of one of the containers and thus an increase in the solids content of the raw material.

Drawings

The invention will be described and elucidated with reference to the drawings. The drawings illustrate different embodiments of the invention. It shows that:

figure 1 shows a block diagram of an apparatus for increasing the solids content of a raw material,

figure 2 shows a first variant of this first device,

figure 3 shows a view of the temperature in the respective container according to a first configuration,

figure 4 shows a view of the temperature of the device according to a first variant,

figure 5 shows a second variant of the device,

fig. 6 shows a third variant of the device and

fig. 7 shows the resulting temperatures in the respective containers for a third variant of the apparatus.

Detailed Description

Starting from the fact that the heating medium D passes through the vessels G1, G2, G3, G4, G5 in the same direction as the starting material 1.

Fig. 1 shows a block diagram of an apparatus P for increasing the solids content of a raw material 1. The device P shown here is based on the current state of the art. The raw material 1, especially black liquor, is transferred to a first vessel G1. The temperature of the raw material 1 is increased in the first container G1 by means of the heat carrier D. In vessel G1, a temperature T1 was present. By increasing the temperature T1 of the raw material 1, a part of the liquid is evaporated from the raw material 1. The raw material 1 with increased solids content is then transferred to a second container G2 and separated from the evaporated liquid. In the second vessel G2, a temperature T2 was present. In the second container G2, the temperature T2 of the starting material 1 is also increased by means of the heat transfer medium D. In the container G2, a part of the liquid is also evaporated from the raw material 1 and the solid content of the raw material 1 is further increased. The subsequent vessels G3, G4, G5 also serve the same purpose, i.e. to further increase the solids content of the raw material 1. In order to efficiently use the thermal energy transferred by heat carrier D into vessels G1, G2, G3, G4, G5, heat carrier D is introduced, for example, into first vessel G1, wherein heat carrier D is immediately transferred from first vessel G1 into second vessel G2, thereafter into third vessel G3, thereafter into fourth vessel G4 and so on. The possible direction of travel of heat carrier D through vessels G1, G2, G3, G4, G5 is symbolized by the interrupted (double-headed) arrow. Therefore, another direction of travel of heat medium D through vessels G1, G2, G3, G4, and G5 can be considered, which is not conventional. The thermal energy Δ Q is transferred from the heat carrier D to the raw material 1, for example, by means of a heat exchanger which is arranged in the vessel. Such a heat exchanger for transferring the thermal energy aq of the heat carrier to the raw material is present in each vessel G1, G2, G3, G4, G5, however symbolically shown in this and in subsequent figures in the second vessel G2.

The transfer of the thermal energy Δ Q can also be carried out by direct contact of the heat carrier D with the raw material 1. The heat exchanger is only shown symbolically in the container G2.

In the evaporation of the liquid from the raw material 1, the part of the thermal energy Δ Q that is introduced into the vessels G1, G2, G3, G4, G5 by the heat carrier D is "consumed". The temperature T1 of the heat carrier therefore decreases gradually from the first container G1 via the second container G2 to the last container G5. Although the solids content of starting material 1 is not increased to an optimum value by this reduction in temperature from T1 via T2, T3, T4 up to temperature T5 in fifth vessel G5, the thermal energy of heat carrier D is nevertheless effectively utilized.

Depending on the direction of travel of heat carrier D and/or starting material 1, heat carrier D can be initially transferred into fifth container G5, thereafter into fourth container G4, and so on, until it is transferred into first container G1. In this case, the temperature is increased from the first container G1 to the fifth container G5, and further the solid content of the raw material 1 is also gradually increased.

Fig. 2 shows a first variant of the device P shown in fig. 1. In plant P in fig. 2, raw material 1 also passes immediately through first container G1, second container G2 up to fifth container G5, and in each container G1, G2, G3, G4, G5 there are temperatures T1, T2, T3, T4, T5 (associated with the respective container), that is to say there is a first temperature T1 in first container G1, a second temperature T2 in second container G2 and so on. Depending on the direction of travel of heat carrier D, the temperature of starting material 1 and/or heat carrier D increases from first container G1 to last container G5, or the temperatures decrease from first container G1 to fifth container G5.

In this case, the heat pump WP, which is used to efficiently use the heat carrier for increasing the solids content of the raw material 1, transfers the thermal energy Δ Q from the fourth container G4 into the fifth container G5 or from the fifth container G5 into the fourth container G4 as the heat carrier D travels through. By transferring the thermal energy Δ Q, the temperature T4 in the fourth vessel is reduced and the temperature T5 in the fifth vessel G5 is increased, or vice versa, depending on the transport direction of the heat carrier Δ Q. By transporting the thermal energy Δ Q, the content of solids in the raw material 1 is increased, wherein in one of the containers G4, G5 more liquid is evaporated from the raw material 1 and thus the solids content of the raw material 1 can be increased significantly by means of extended facilities compared to the current prior art.

The control device SE is used to control the heat pump WP and is connected to sensors S, in particular temperature sensors S, which determine the temperature in the fourth container G4 and the temperature T5 in the fifth container G5.

Fig. 3 shows the trend of the temperature of the raw materials in the containers G1, G2, G3, G4, G5. Here, a first temperature T1 is present in the first container G1. In addition, a second temperature T2 is present in the second container G2, and so on. The figure shows the temperature profile of the heat transfer medium D and/or the raw material 1 without the use of a heat pump WP. Here, the temperatures T1, T2, T3, T4, T5 continuously drop between the vessels. By guiding heat medium D through vessels G1, G2, G3, G4, G5, it is also possible to obtain corresponding further versions of temperatures T1, T2, T3, T4, T5.

Fig. 4 shows a view of the temperatures T1, T2, T3, T4, T5 of the device P according to the first variant. In particular, fig. 4 shows the effect of the heat pump WP on the temperature in the fourth vessel G4 and the fifth vessel G5. The thermal energy Δ Q transferred from the fifth vessel G5 into the fourth vessel G4 causes a drop in the temperature T5 in the fifth vessel G5 at the same time as the temperature T4 in the fourth vessel G4 increases.

The solids content of the raw material in container G4 is significantly increased by this temperature transfer, so that a slight increase in the solids content of raw material 1 in fifth container G5 is also overcompensated for. The transfer of thermal energy aq is illustrated by the arrow from the last bar (the last bar symbol representing the temperature T5 in the fifth container G5) to the penultimate bar (the penultimate bar symbol representing the temperature T4 in the fourth container G4). The temperature increase in the fourth container G4 is symbolized by the hatched area.

Fig. 5 shows a second variant of the device P. In this case, a further heat pump WP' is used to transfer thermal energy Δ Q from the fourth tank G4 to the third tank G3 or vice versa. Similarly to the first variant shown in fig. 2, in the second variant, a heat pump WP is likewise shown between the fourth tank G4 and the fifth tank G5. The two possible directions of transport of the thermal energy Δ Q are indicated by arrows pointing in two directions. There are several possibilities to combine the transport of thermal energy Δ Q by different transport directions. It is possible to: thermal energy delta Q

From the fifth container G5 and the third container G3 into the fourth container G4,

from the fifth container G5 into the third container G3 via the fourth container G4, or

From the third container G3 into the fifth container G5 via the fourth container G4.

Here, the control device SE (not shown) can also control or regulate the use of the heat pump WP and the further heat pump WP' by means of the (temperature) sensor S. For an improved overview, reference is made here to the control device shown in fig. 2.

The solids content of the raw material 1 can be increased still further by means of a further heat pump by means of the illustrated apparatus P. The control device SE controls or regulates, for example, the heat pumps WP, WP'. The transport direction of the thermal energy Δ Q can also be controlled or regulated by the control device SE. Advantageously, however, for the sake of simplicity, not shown, the containers G1, G2, G3, G4, G5 are provided with sensors S, or at least the containers G3, G4, G5 that transport thermal energy Δ Q into/out of them are provided with sensors S.

Fig. 6 shows a third variant of the device P. A third variant of the plant P has a heat pump WP for increasing the temperatures T4, T5 in the fourth tank G4 and the fifth tank G5 and, if appropriate, a further heat pump WP'. In this case, the heat pump WP or the heat pumps WP, WP' (or also the heat exchangers) transfer the thermal energy Δ Q from the reserve R into the respective tank G4, G5. This embodiment of the device P is particularly advantageous in that the temperatures T4, T5 are controlled in a simple manner by means of a control device SE, which is connected to a sensor S for determining the temperatures T4, T5. A steam kettle or a source of exhaust gas, such as a paper mill, can be used as reserve R. The sensor S can also be assigned to a further container for determining relevant variables (temperature, pressure, solids content, chemical composition).

Fig. 7 shows, in analogy to fig. 4, the effect of the heat pump (or heat exchanger) WP, WP' used in this way on the temperature profile of the raw material 1 in the respective vessel G1 to G5. Similar to fig. 4, a view of temperatures T1, T2, T3, T4, T5 in the respective containers G1, G2, G3, G4, G5 is shown. By transferring thermal energy Δ Q into the fourth container G4 and the fifth container G5, an increase in the temperature T4, T5 in the penultimate container G4 and the last container G5 is shown. The temperature increase of the heating medium D and/or the starting material 1 is symbolized by the corresponding hatching. The thermal energy Δ Q delivered from the reserve R, which is the basis for the temperature increase, is symbolized by the shaded arrows.

It is clear to the person skilled in the art that: the embodiment shown in fig. 6 can be combined with the embodiment of fig. 2 and/or the embodiment of fig. 5. Furthermore, the heat pump/heat exchanger can also supply thermal energy from the reserve R to the further containers G1, G2, G3. The heat exchanger is extremely well suited for transferring thermal energy from the reserve R into the penultimate container G4 or the last container G5.

In summary, the invention relates to a method and a device P for increasing the solids content in raw material 1, in particular for increasing the solids content of black liquor 1 in the production of pulp for paper production, preferably an evaporation device for black liquor, having a plurality of vessels G1, G2, G3, G4, G5 and at least one heat pump WP, WP', wherein thermal energy Δ Q for acting on raw material 1 is provided for increasing the solids content. The starting material 1 is conveyed from the first container G1 to at least one further container G2, G3, G4 to the last container G5. The at least one heat pump WP, WP 'is advantageously used to transport thermal energy Δ Q into the at least one container G1, G2, G3, G4, G5 and the at least one heat pump WP, WP' extracts thermal energy from the reserve R and/or thermal energy Δ Q from one of the containers G1, G2, G3, G4, G5. Thus, advantageously, a higher solids content of the starting material 1 can be achieved.

Claims

1. A device (P) for increasing the solids content in a raw material (1), having a plurality of containers, wherein thermal energy (Δ Q) is provided for acting on the raw material (1) in order to increase the solids content, wherein a passage of the raw material (1) from a first container (G1) via at least one further container to a last container (G5) is provided, characterized in that at least one heat pump (WP, WP ') is provided for transporting thermal energy (Δ Q) into at least one container, and at least one heat pump (WP, WP ') extracts the thermal energy from a reserve (R) and/or extracts the thermal energy (Δ Q) from one of the containers, wherein the heat pump (WP, WP ') transports thermal energy (Δ Q) counter to the direction of the passage of the raw material (1).

2. An apparatus (P) according to claim 1, characterized in that the apparatus is used for increasing the solids content of black liquor in the manufacture of pulp for papermaking.

3. The apparatus (P) according to claim 1, characterized in that it is an evaporation apparatus of black liquor.

4. Plant (P) according to claim 1, characterized in that said reserve (R) is the excess thermal energy of the adjacent facilities.

5. The plant (P) according to any one of claims 1 to 4, characterized in that the solid content of the raw material (1) is gradually increased in the containers by means of thermal energy, and the temperature (T1) of the raw material (1) is higher in the first container (G1) than in the last container (G5).

6. Plant (P) according to any one of claims 1 to 4, characterized in that said heat pump is provided for transporting thermal energy (Δ Q) from said last container (G5) into at least one further container.

7. Plant (P) according to claim 5, characterized in that said heat pump is provided for transporting thermal energy (Δ Q) from said last container (G5) to at least one further container.

8. The plant (P) according to any one of claims 1 to 4, characterized in that a heat carrier (D) is provided for conveying the thermal energy (Δ Q) to the raw material.

9. A plant (P) according to claim 7, characterized in that a heat carrier (D) is provided for the transfer of thermal energy (Δ Q) to the raw material.

10. An apparatus (P) according to any one of claims 1 to 4, further having at least one sensor (S) and a control device (SE), characterized in that the control device (SE) and/or the sensor (S) is/are provided for controlling and/or regulating the delivery of thermal energy (Δ Q) into at least one of the containers.

11. An apparatus (P) according to claim 9, further having at least one sensor (S) and a control device (SE), characterized in that the control device (SE) and/or the sensor (S) is/are provided for controlling and/or regulating the delivery of thermal energy (Δ Q) into at least one of the containers.

12. A method for increasing the solids content in a raw material (1), wherein the raw material (1) is first passed through a first vessel (G1), then through at least one further vessel and finally through a last vessel (G5), wherein thermal energy (Δ Q) is applied to the raw material (1) in order to increase the solids content, characterized in that thermal energy (Δ Q) is introduced into at least one vessel by means of at least one heat pump (WP, WP '), and that at least one of the heat pumps (WP, WP ') extracts the thermal energy (Δ Q) from a reserve (R) and/or from one of the further vessels, wherein the heat pump (WP, WP ') transports the thermal energy (Δ Q) counter to the direction of travel of the raw material (1).

13. The method according to claim 12, characterized in that the method is used for increasing the solids content of black liquor in the manufacture of pulp for papermaking.

14. The method according to claim 12, characterized in that the method is a method for evaporating black liquor.

15. Method according to any of claims 12-14, characterized in that thermal energy (Δ Q) is transported from the last container (G5) into one of the other containers.

16. A control device (SE) for controlling and/or regulating the method according to any one of claims 12 to 15, characterized in that sensors (S) are provided for determining the temperature in a vessel, the temperature of a heat carrier (D), the solids content of the raw material (1), and/or the pressure value in each of the vessels, and that the control device (SE) is provided for controlling and/or regulating at least one of the heat pumps (WP, WP') depending on the temperature, the solids content of the raw material (1), and the pressure value in each of the vessels.

17. A plant for processing raw material, the plant having an apparatus according to any one of claims 1 to 11 and/or a control device according to claim 16.

18. The installation according to claim 17, characterized in that the installation is an installation for evaporating black liquor.

19. A paper mill having the facility of claim 17 or 18.

20. The paper mill of claim 19, wherein the paper mill is an integrated pulp and paper mill.