WO2014106667A2

WO2014106667A2 - Method for the solvolysis of aqueous organic suspensions and solutions to form concentrated, aqueous, black-liquor-like and/or salt-like solutions of organic compounds

Info

Publication number: WO2014106667A2
Application number: PCT/EP2014/050172
Authority: WO
Inventors: Thomas Müller; Patrick Von Hertzberg; Stefan Bothur
Original assignee: Patrick Von Hertzberg, Stefan Bothur Und Thomas Müller Rechteverwertung Gbr
Priority date: 2013-01-07
Filing date: 2014-01-07
Publication date: 2014-07-10
Also published as: WO2014106667A3; DE102013100081A1

Abstract

The invention relates to a method for processing water-containing waste and raw materials, said method having the following steps: combining the wastes to be processed with an aqueous, alkaline solution to form a reaction mixture, in order to produce the circulating stream; heating the reaction mixture to a temperature range of between 140°C and 250°C and a pressure of between 2 bar and 12 bar to produce at least one aqueous, where necessary organic phase, a gas phase and where necessary a solid phase; conducting the gas phase out of the reactor; where necessary separating the organic and aqueous constituents of the gas phase, particularly by means of a rectification column, particularly if organic excipients are used; compressing the aqueous phase; removing ammonia and other undesired constituents from the vapour; cooling the vapour produced in the heat exchanger (6) or in the double-casing reactor such that a condensate is produced and at the same time the heat is output to the product circuit (35), water being evaporated out of the product; removing the condensate from the process after the physical heat of the condensate has been output via the heat exchanger (33) to the inflowing starting materials (1 and 2).

Description

The invention relates to a process for the treatment of water-containing waste and raw materials, such as liquid manure, digestate, sewage sludge, hereinafter referred to as "liquid manure " called.

The treatment of very highly water-containing raw materials such as manure, sewage sludge or similar. is a big problem because these raw materials must first be pre-dried or dehydrated. The dewatering of very hydrous, organic waste or raw materials is - according to the prior art - by separation methods such as:

• centrifugation

• filtration

• Ion exchanger

· Evaporation / convection drying

- often in combination with each other - carried out.

In the field of manure / digestate treatment, no process or combination of processes has been widely accepted. The technical challenges of evaporation of such substances are due in particular to the four problem groups:

1. Slurry foams heavily during evaporation. The cause is on the one hand, the formation of vapor / gas bubbles by evaporation or gas separation (eg NH3, C02), on the other hand by the presence of surface-active substances that greatly reduce the surface tension of the water. 2. For indirect heat transfer, the heat exchanger surfaces are polluted by crusting. This crusting is caused in particular by denaturation processes of proteins and the associated coagulation at the interface.

3. The condensate contains a high proportion of ammonia / ammonium. In pig slurry in the order of 1-2% by mass. The condensate can i.d.R. can not be introduced into the sewage system without nitrogen separation.

4. The energy consumption during evaporation is only possible with low-cost waste heat with purely thermal evaporation with more than 600 kWh / m ^{3 of} liquid manure. If this is not available, then this amount of energy is too high for economic evaporation. So you have to work with heat pump processes (usually vapor recompression). Such processes are practically about 5% of the amount of energy that must be applied in purely thermal evaporation.

The object of the invention is to provide a method which can be used for processing highly water-containing raw materials such as manure, sewage sludge.

The above problems are avoided by combining a solvolysis process according to DE200810055508 in connection with a heat pump principle realized by mechanical vapor compressors. As a result, very strongly water-containing organic raw materials and waste materials of solvolysis according to DE200810055508 are accessible.

The object of the invention is therefore achieved by the features of patent claim 1.

The independent claims represent advantageous embodiments.

The object of the method according to the invention is that organic components of the waste are treated by solvolysis, so that they are subsequently present in at least one liquid phase. At the same time, the water content of the product is significantly reduced compared to the starting material. According to the method DE 200810055508, the wastes are combined in a reactor with an aqueous, alkaline solution and an essentially water-insoluble organic auxiliary to form a reaction mixture. As the aqueous phase, hereinafter also referred to as a phase containing the water-soluble organic molecules. The organic phase is a phase that is substantially immiscible with the aqueous phase.

The addition of the organic auxiliary (for example aliphatic hydrocarbons) is optional and is indicated in particular when components such as elastomers, polyolefins or the like are to be expected in the raw material. The reaction mixture is heated to a temperature range between 140 ° C to 250 ° C and placed under a pressure between 3 bar and 12 bar, so that at least one aqueous, organic phase, a gas phase and optionally a solid phase and (when using organic auxiliaries ) arise a floating non-polar, organic phase.

Contrary to DE 200810055508, the gas phase is removed from the reactor, compressed, condensed out, depleted of gases, re-evaporated by venting, again condensed out and then removed from the process.

As advantageous alkaline solutions, those have been found which contain the inorganic carbonates. The potassium carbonate solution has proven to be particularly advantageous.

The alkaline carbonate solutions are preferably saturated. The organic auxiliaries are preferably lubricating oils, motor oils, aliphatic hydrocarbons or the like. The organic adjuvants are preferably inert to the alkaline solution.

The organics, ie the organic constituents which are predominantly dissolved in the organic adjuvant and do not have sufficient vapor pressure to be carried out with the drag vapor, are predominantly nonpolar and float on the alkaline solution since their density is smaller than that of the alkaline Solution. The discharge of this floating phase is preferably carried out when the entire solution is pumped or pumped into other containers, is. The solution can be pumped via a 3-way valve depending on their conductivity in separate containers.

1. By adding potassium carbonate (2) or an aqueous solution of potassium carbonate to the liquid raw material (e.g., manure) (1), many surface-active substances are chemically changed under the basic conditions and under the influence of temperature, so that their surface activity decreases. Nevertheless, a strong foaming is still observed. The foam of the freshly flowing slurry / potassium carbonate solution (9) is mixed with the circulation of the reaction mixture, from line (35). The mass flow of the circulation is large against that of the incoming fresh material. As a result, after the mixing of the two partial streams, this is a very concentrated, aqueous solution of predominantly organic potassium salts, which is less prone to foaming than a weakly concentrated solution. Upon entry of this mixture in the caused by the activity of the stirrer Trombe in the stirred tank (8) remaining foam is promptly pulled so inside the liquid that it collapses quickly. Since statistically about as much water is expelled by evaporation from the stirred tank, as is added to water, the concentration in the stirred tank remains constantly high. By the now occurring solvolysis, i. the degradation of organic polymer compounds towards smaller compounds, which are usually carboxylates, and under the influence of pressure, the foaming is greatly suppressed. In order to prevent individual scraps of foam entrained in the vapor stream from entering the vapor compressor (12) or the condensate (3), a centrifugal separator (19) is installed in the vapor line. The collapsed foam, so the resulting liquid is returned to the stirred tank (8).

2. The solvolysis described under point 1 prevents the formation of deposits by converting the organic compounds into water-soluble substances. 3. In the steam storage (15, 25) high temperatures prevail, thereby the solubility of the ammonia under these conditions is very low. This can be deliberately drained via the valve (16). It makes sense to release the pressure until the pure water vapor pressure has set. In addition, optional air or other gases (13) can be supplied for stripping.

4. The mechanical vapor recompression by the compressor (12) is a heat pump. At low temperature differences between the stirred tank (8) and the steam accumulator (15, 25) only about 5% of the amount of energy of the heat of evaporation in the form of mechanical energy is required.

The steam storage is a simple pressure vessel filled with steam and water. This pressure vessel is not heated from the outside as in a Dampfspeicherlok, but the pressure is so far increased by the heat of condensation, resulting from the condensation of the vapor on the template, that then the re-evaporation can be realized.

The invention will now be explained in more detail with reference to FIG.

Fig. 1 shows a system in which the inventive method can be performed.

From the products manure and alkali, preferably a potassium hydroxide or potassium carbonate, particularly preferably potassium carbonate in a saturated aqueous solution (hereinafter called alkali) is prepared in a semi-batch process, a black liquor similar product.

For this purpose, depending on the organic dry matter content of the manure by the pump (39) or (40) alkali and manure are metered to each other. In this case, a mixing ratio of 1: 1 - 3: 1, preferably 2: 1 wipe TOC (organic carbon content) and adjust potassium. The thus prepared mixture is preheated in the heat exchanger (33) to a temperature of 80-190 ° C, preferably to about 160 ° C. In this case, due to the water vapor pressure and the formation of fission gases such as ammonia and C0 ₂ an increased pressure. In the line (9), the admixture of the product circulating flow takes place. Since the product recycle stream is a concentrated solution of predominantly organic salts and the mass flow of the recycle stream is a multiple of the feed mass stream, the ion concentration of the mixture is close to the ion concentration of the recycle stream. As a result of this high ion concentration, the vapor pressure of the mixture is greatly reduced from the vapor pressure of pure water. The mixture results in a partial recondensation of the previously formed water vapor and an increase in temperature.

The mixture is then added to the eye of the stirring by stirring in the stirred tank (8). In the stirred tank, a pressure of 2-5 bar (abs.), Preferably about 3 bar is set. The equilibrium temperature is then between 160 and 190 ° C.

As already mentioned, as a result of the colligative properties of the ions in the solution, the water vapor pressure is far below the vapor pressure which pure water would have at this temperature. The vapor above the solution, which is also mixed with fission gases such as ammonia and C0 ₂ , is superheated steam.

This vapor is removed from the stirred tank (8) via the line (9) and passed into a centrifugal separator (19). There, entrained scraps of foam are separated from the gas / vapor stream. The foam is destroyed so that the liquid can be passed through the bottom of the centrifugal separator (19) back into the stirred tank. The gas / vapor stream is fed via the line (20) to the vapor compressor (12).

There, the pressure of the gas / vapor stream is increased. It is preferred in the compressor or immediately after the compressor water, fed by pump (18) to inject, so that it does not come to a polytropic state change, but a saturated steam with a temperature of 40 Kelvin higher, preferably max. 10 Kelvin higher than the temperature in the stirred tank (8) is formed. The saturated steam thus shown is alternately directed into the steam reservoirs (15) and (25), respectively. There, the vapor condenses as long as the temperature of the water reservoir in the steam reservoirs is below the steam temperature. Thus, the latent heat is first converted into physical heat and stored in this form. If the temperature in the water reservoir of the steam accumulator no longer rises, the steam is directed into the other steam accumulator. For this, the valves (11) and (31) are actuated. The storage of the steam is mainly for the reason that gases such as ammonia and C0 ₂ , which dissolve only slightly in the water at high temperatures, can be expelled in concentrated form. Thus, these gases are blown off in each case via the valves (16) and (26) and fed to a further processing, for example to ammonium sulfate.

In addition, optional compressed air or other gases (13) can be injected into the steam storage tank to further discharge ammonia.

When the stripping process is completed, steam is passed through the opening of the valve (14) or (32) into the heat exchanger (6), which heats the product circulation. This max. as long as steam by post-evaporation in the heat exchanger (6) until the temperature in the respective steam storage is equal to the temperature in the stirred tank (8). The condensate condensed and cooled after the passage of the heat exchangers (6) and (33) contains only a small amount of ammonia. The remaining ammonia is sorbed by the ion exchanger when passing through an ion exchange column (cation exchanger), so that pure water is obtained as the end product.

The ion exchangers are regenerated with acid (e.g., sulfuric acid) to recover ammonium fertilizer.

When so much manure has been evaporated that the residue fills the container to its maximum level, the supply of manure and alkali is interrupted and valve (41) is closed. Furthermore, the circulation of the reaction mixture (35) is interrupted by switching off the pump (34). In order to achieve a sufficient residence time in the solvolysis, the process is continued until the solvolysis is completed. For this purpose, steam is passed from the steam reservoirs (15, 25) or, in the alternative, from the steam generator (22) into the stirred tank. The pressure in the stirred tank (8) is now increased to the pressure of the vapor accumulator (15, or 25). As a result of the colligative properties of the ions in the Reaction mixture increases the temperature in the stirred tank (8) to the vapor pressure equilibrium. As a result of the formation of fission gases such as ammonia, which come from the hydrolysis of proteins or their building blocks, the amino acids, the pressure would rise further, but the gas / vapor mixture is discharged through the vapor compressor again and with the vapor as above described procedure. The final product (4) formed after solvolysis - the suspension of an aqueous solution of organic salts and inorganic, sparingly soluble components, such as calcium zoates, is removed via the valve (24).

After that, the process can start over. The initial heating of the reaction mixture takes place via the steam generator (22).

Fig. 2 describes a plant for a further embodiment in which water is removed by a multi-stage evaporation.

This embodiment is particularly preferred when the solutions of organic salts produced in the solvolysis are energetically utilized by combustion. As in the manure o.ä. Raw materials contained amount of chemical energy (calorific value of the organic substance) is usually not sufficient to apply the energy necessary for simple evaporation, the evaporation must be cascaded in stages, so that the heat of condensation of each previous stage can be used as heat of vaporization. The number of possible stages depends essentially on the initial temperature, the temperature intervals between the stages and the temperature of the last stage. When choosing the initial temperature, it should be noted that the organic salts are not yet thermally decomposed and that the equilibrium pressures resulting from the temperature and concentration do not lead to very high costs of the apparatus. The temperature intervals between the stages are essentially determined by the degree of overheating of the steam and the size of the heat exchanger surfaces. Heavily superheated steam can only release its heat of condensation when it has reached the saturated state (saturated steam temperature) associated with its pressure. Here it is important to optimize between the advantages of a high concentration and the disadvantages of the large temperature intervals between the column stages by strong overheating of the steam. This optimization can be realized by a product return from the last stage to the first stage. The reflux ratio determines the concentration, or the concentration gradient in the apparatus.

The temperature of the last stage is determined by the temperature level of the heat reuse or by the solubility of the ammonia. At high temperatures, ammonia dissolves only poorly in water, so that the small amounts which can then be dissolved in the condensate can be removed via ion exchangers. Another limit for the last temperature is the solubility of alkali salts. The solubility is very temperature dependent, concentrated solutions can only be displayed at high temperatures. Especially against the background of an energetic use of the organic salt solutions, a high concentration - and thus a low water content - plays a decisive role.

The evaporation plant is explained in more detail in FIG. 2:

The raw material 46 is introduced via the pump 48 in the system. About the metering pump 49, the alkali 47 is metered. In this case, a fixed ratio (proportional dosing) can be set, or a control loop (which compares the temperature and pressure values in the reactor with the temperature-pressure-concentration characteristic map) can be set up. The mixture of substrate and alkali is now preheated in the heat exchanger 54, at the same time the condensate is cooled from the evaporator stages.

The preheated mixture then enters the Solvolysereaktor 55, in which the organic polymers of the substrate are converted into water-soluble, salt-like compounds. The high salt concentration and the resulting density of the liquid in the reactor (<1.6 kg / l) cause floating of the not yet converted by solvolysis in water-soluble compounds organic matter. On the other hand, inorganic compounds such as calcium phosphates (density 3.14 kg / l) freed from their organic matrix sediment and can be separated by a downstream hydrocyclone. Thereafter, these substances are further processed to fertilizer or other products. The freed from the inorganic material flow leaves the hydrocyclone through the dip tube in the pump 66, which conveys the material flow in the heat exchanger 64 of the forced circulation evaporator. The actual evaporation takes place in the expansion vessel 65, since in the heat exchanger Grand of heavy edracks the liquid a higher pressure than in the tank 65 prevails. Most of the unevaporated liquid is returned to the solvolysis reactor. This occurs preferably tangentially in the Solvolysereaktor, so that the entire liquid is rotated in the reactor and the reaction mixture is moved. About the overflow valve 99 is derived from the Solvolysereaktor over the liquid accumulating gas mixture of ammonia, C02 and water vapor. This is then - together with the gases which are removed through the overflow valves 72, 81 and 88 from the heat exchangers - cooled to below 35 ° C, so that forms an aqueous solution of ammonium bicarbonate, which collected in the container 93 and ultimately there is removed. The ammonium bicarbonate can then be processed centrally or, for example, ammonium sulfate fertilizer (with the aid of gypsum) or otherwise marketed.

From the forced circulation of the first evaporator stage, a partial flow is diverted via valve 67, which is forwarded in each case to the subsequent cascades. Previously, however, part of the physical heat of the liquid is returned to the product return in the heat exchangers 68 and 76, respectively. This is necessary so that about the same amounts of water are evaporated in the respective forced-circulation evaporator stages. However, the product stream leaving the final evaporator stage does not flow quantitatively via valve 79 into the return to the first evaporator stage, because a product stream is branched off via valve 80 which is brought to its final concentration in the steam-heated double wall container 60 (possibly with stirring) and represents the main product. In addition to the double wall container 60, which is heated via the steam line 62, and the heat exchanger 64 of the forced circulation evaporator of the first stage is heated directly with steam from a steam generator. Preferably, this vapor is produced by combustion of the product 59. In this combustion, the alkali is recovered. The second and third evaporator stage is heated by the vapors 84 and 85 of the respective previous evaporator stage. The vapor 86 is condensed for reuse 89 (eg steam for heating purposes) on the circuit moved by pump 87. The condensates from the heat exchangers 71, 100 and 101 are freed after cooling in the heat exchanger 54 in the ionic diver 51 from the last ammonium residues and via valve 52 - which ensures the necessary back pressure to Systemdrack - as pure water 53 from the Process discharged. In order to keep the ammonia / ammonium loads with which the ion exchanger is charged low, it is condensed at high temperatures, as already mentioned above. In addition, CO 2 (92), which is also used as a reactant for the formation of ammonium bicarbonate, is used in excess and used in the driven by pump 94 circuit 92 as the stripping gas. Via the valves 74, 96 and 97, the stripping gas is introduced into the containers 71, 100 and 101. In place of pure CO 2, flue gas can also be used, but then the nitrogen and other gases must always be removed from the cycle.

The condensate 63, which comes from the steam of the steam generator is returned as feed water.

LIST OF REFERENCE NUMBERS

1. liquid, organic raw or waste material (for example manure)

2. Alkali, preferably potassium carbonate as concentrated, aqueous solution

3. Condensate / pure water

4. Product (Black liquorice, concentrated, aqueous solution of organic, mainly salt-like compounds)

5. Ammonia / water vapor mixture with high ammonia concentration for further processing (for example to ammonium sulphate)

6. Heat exchanger for recovering the physical heat of the condensate

7. ion exchange column

8. stirred tank

9. Feedstock to the reactor

10. Steam line to the centrifugal separator

11. Valve Vapor Compressor / Steam Inlet Steam Storage (15)

12th vapor compressor

13. stripping gas

14. Valve steam outlet from steam storage (15)

15. Steam storage

16. Valve ammonia / vapor mixture outlet

17. ammonia / steam line 18. Feedwater pump for vapor compressor

19. centrifugal separator

20. Immersion tube with steam line to the vapor compressor

21. Compressor for stripping gas

22nd steam generator

23. Valve for regulating the system pressure in the condensate section / condensate outlet

24. Valve for product outlet (black liquor)

25. Steam storage

26. Valve steam outlet from steam storage (25)

27. Valve for feed water

28. Valve for feed water

29. Valve for stripping gas inlet in steam accumulator (15)

30. Valve for stripping gas inlet in steam accumulator (25)

31. Valve Vapor Compressor / Steam Inlet Steam Storage (25)

32. Valve steam outlet from steam storage (25)

33. Heat exchanger slurry preheating

34. Pump for product circulation stirrer / heat exchanger

35. Product circulation line Stirring tank / heat exchanger

36. Valve for steam for direct heating of the reaction mixture

37. Steam line entil for introducing steam into heat exchanger (6) umpe for introducing liquid manure osierpumpe for the introduction of alkali entil supply line of liquid, organic raw or waste lkali, preferably potassium carbonate as concentrated, aqueous solution pump for raw material pump for alkali shut-off valve ion exchange column valve to regulate the system pressure in condensate section / condensate outlet condensate / pure water heat exchanger - raw material preheating / condensate cooling Solvolysereactor floating layer hydrocyclone sediment for further processing product (black liquor-like, concentrated, aqueous solution of organic, mainly salt-like compounds) Product container (heated) for setting the final concentration 61. Steam generator

62. Steam partial flow to the heating jacket of the product container

63. Condensate to the feedwater pump of the steam generator

64. Heat exchanger for heating the first evaporator stage

65. expansion tank of the forced circulation evaporator of the first evaporator stage

66. Circulation pump of the forced circulation evaporator of the first evaporator stage

67. Dosing valve for supply to the second evaporator stage

68. Heat exchanger product return / feed to the second evaporator stage

69. Expansion tank of the forced circulation evaporator of the second evaporator stage 70. Circulation pump of the forced circulation evaporator of the second evaporator stage

71. Heat exchanger for heating the second evaporator stage

72. Overflow valve for ammonia / C02 / water vapor mixture

73. Condensate drain valve

74. C02 / stripping gas inlet in second evaporator stage

75. Dosing valve for feed to the third evaporator stage

76. Heat exchanger product return / feed to the third evaporator stage

77. Pump for product return in first evaporator stage

78. Expansion tank of the forced circulation evaporator of the third evaporator stage

79. Dosing valve for product return to the first evaporator stage

80. Product flow to the container 60 81. Overflow valve for ammonia / C02 / water vapor mixture

82. Circulation pump of the forced circulation evaporator of the third evaporator stage

83. Condensate drain valve

84. Brüdenleitung to the heat exchanger of the forced-flow evaporator of the second evaporator stage

85. Brüdenleitung to the heat exchanger of the forced-flow evaporator of the third evaporator stage

86. Brüdenleitung to the heat exchanger of the heat after-use

87. Recirculation pump for heat reuse 88. Excess flow valve for ammonia / C02 / water vapor mixture

89. Heat consumer o the cooling tower

90. Heat consumer or cooling tower

91. C02 refill

92. C02 stripping gas circulation 93. Ammonium bicarbonate solution container

94. compressor for stripping gas circulation

95. Condensate drain valve

96. C02 / stripping gas inlet in second evaporator stage

97. C02 / stripping gas inlet in the third evaporator stage 98. Discharge of ammonium bicarbonate solution 99. Overflow valve for ammonia / C02 / water vapor mixture

100. Heat exchanger for heating the third evaporator stage

101. Heat exchanger for heating the reuse 89

Claims

claims

A process for the treatment of hydrous waste and raw materials, comprising

the steps of: a) combining the waste to be treated with an aqueous alkaline solution to form a reaction mixture to produce the recycle stream; b) heating the reaction mixture to a temperature range between 140 ° C to 250 ° C and a pressure between 2 bar and 12 bar to produce at least one aqueous, optionally an organic phase, a gas phase and optionally a solid phase; c) removing the gas phase from the reactor; d) optionally separating the organic and aqueous components of the gas phase,

in particular by a rectification column, in particular when using organic auxiliaries; e) densification of the aqueous phase; f) removal of ammonia and other undesirable constituents from the vapor; g) cooling the resulting vapor in the heat exchanger (6) or in the jacketed reactor so that a condensate is formed, and at the same time the heat to the product circulation (35) is discharged, wherein water is evaporated from the product; h) removal of the condensate from the process after the physical heat of the

Condensate via the heat exchanger (33) was discharged to the influent starting materials (1 and 2).

2. The method of claim 1, wherein the step e) by a mechnical

Vapor compressor.

3. The method of claim 2, wherein the compression in step e) by supplying the

aqueous components of the gas phase via the line (20) the vapor compressor, whereby the pressure of the entire gas phase is increased.

4. The method of claim 3, wherein after being fed into the compressor, the water is injected in the compressor or immediately after the compressor, so that a saturated steam having a temperature of at most 40 Kelvin higher, preferably max. 10 higher than the temperature in the stirred tank (8) is formed.

5. The method of claim 1, wherein the Verdi chting in step e) is carried out by Cascade Verdapfer.

6. The method according to any of Anspürche 1-5, wherein in step f) is additionally stripped of ammonia by injecting compressed air or other gases into the vapor storage.

The process of claim 1 or 2, wherein the cooled condensate from step h) is passed through an ion exchange column.

A process for treating hydrous waste and raw materials according to any one of claims 1-7, wherein the hydrous waste and raw materials such as e.g. Manure, digestate or sewage sludge or similar, water-containing mixtures containing organic constituents are.

9. The method according to any one of the preceding claims, wherein the flow of the incoming fresh material is mixed with the circulating stream.

10. The method according to any one of the preceding claims, wherein the mass flow of the circulation large compared to the flow of the incoming fresh material.

11. The method according to any one of the preceding claims, wherein the ratio of the

Mass flow of the circulation compared to the flow of fresh incoming material in

Ratio of 100: 1 to 20: 1 is set.

12. The method according to any one of the preceding claims, wherein a centrifugal separator (19) is installed in the steam line.

13. The method according to any one of the preceding claims, wherein the from

collapsed foam resulting liquid is returned to the stirred tank.