METHOD AND APPARATUS FOR THE MANUFACTURING OF NON-ENERGENT BIOCOAL WITH THERMAL TREATMENT

Abstract

A method and an apparatus for manufacturing, with thermal treatment, biocoal which is non-energent, such as functional as a heat sink, by using a conveyor arrangement housed in an essentially Thompson Converter type process space. A to-be-processed feedstock is conveyed in the process space with the conveyor arrangement, which is closed relative thereto, in a longitudinal direction of the process space. A pyrolysis gas, generated from the to-be-processed feedstock present inside the conveyor arrangement as a result of heat transferring from the process space thereto, is conducted into a combustion chamber included in the process space for burning the gas, a thereby generated flue gas being removed from the process space by a discharge arrangement and a resulting non-energent biocoal being removed from the conveyor arrangement for further processing.

Claims

1. A method for manufacturing, with thermal treatment, biocoal which is non-energent, such as functional as a heat sink, said method comprising introducing a to-be-processed feedstock with supply elements into the interior of a conveyor arrangement, which is present in a Thompson Converter type process space and closed relative thereto, for moving the to-be-processed feedstock in the process space in a longitudinal direction of the process space, whereby a pyrolysis gas, generated from the to-be-processed feedstock present in the conveyor arrangement as a result of heat transferring thereto from the process space, is conducted away from the conveyor arrangement for burning the same in a combustion chamber of the process space, a resulting flue gas being removed from the process space by way of a discharge arrangement and a produced non-energent biocoal being removed from the conveyor arrangement with discharge elements for further processing, whereby the pyrolysis gas is burned with a most preferably continuously operating gas burner arrangement and heat transfer for the conveyor arrangement in the process space is conducted with substantially direct radiation from a flame of the gas burner arrangement and from walls of the combustion chamber, and whereby the pyrolysis gas is conducted within the conveyor arrangement in a counterflow relative to the longitudinal direction of the process space towards a supply end of the conveyor arrangement for transferring the heat present in the pyrolysis gas into the to-be-processed feedstock moving in the longitudinal direction of the process space and for delivering the cooled pyrolysis gas to the gas burner arrangement, characterized in that the amount of PAH compounds contained in the to-be-produced non-energent biocoal is reduced/eliminated by means of water vapor by supplying water into the interior of the conveyor arrangement, the water being conducted into the interior of the conveyor arrangement from its discharge end for carrying the vapor flow, jointly with the pyrolysis gas, in a counterflow relative to the longitudinal direction of the process space towards the conveyor arrangement's supply end.

2. The method according to claim 1, characterized in that pyrolysis gas to be produced is removed in the longitudinal direction of the process space prior to supplying the to-be-processed feedstock.

3. The method according to claim 1, characterized in that the to-be-produced non-energent biocoal is cracked and cooled by the action of water vapor prior to its removal from the conveyor arrangement.

4. The method according to claim 1, characterized in that the to-be-processed feedstock is treated in the process space with the conveyor arrangement, which is at excess pressure relative thereto and provided with the supply and discharge elements that are substantially gastight relative to the environment.

5. The method according to claim 1, characterized in that the supply of additives into the non-energent to-be-produced biocoal is implemented by admixing with the water to be delivered into the conveyor arrangement.

6. An apparatus for manufacturing non-energent biocoal with thermal treatment, said apparatus including: supply elements for introducing a to-be-processed feedstock into the interior of a conveyor arrangement present in and closed relative to a Thompson Converter type process space for moving the to-be-processed feedstock in the process space in a longitudinal direction of the process space, a flow arrangement for conducting a pyrolysis gas, generated from the to-be-processed feedstock present in the conveyor arrangement as a result of heat transferring thereto from the process space, away from the conveyor arrangement for burning the same in a combustion chamber of the process space, a discharge arrangement for removing a resulting fuel gas from the process space, discharge elements for the removal of a produced non-energent biocoal from the conveyor arrangement for further processing, and a most preferably continuously operating gas burner arrangement for burning the pyrolysis gas, whereby the heat transfer for the conveyor arrangement in the process space is adapted to occur with substantially direct radiation from a flame of the gas burner arrangement and from walls of the combustion chamber, and whereby the pyrolysis gas is conducted within the conveyor arrangement in a counterflow towards a supply end of the conveyor arrangement for transferring the heat present in the pyrolysis gas into the to-be-processed feedstock moving in an opposite direction and for delivering the cooled pyrolysis gas to the gas burner arrangement, characterized in that the apparatus includes a supply arrangement for conducting water into the interior of the conveyor arrangement, for reducing/eliminating by means of water vapor the amount of PAH compounds contained in the to-be-produced non-energent biocoal, said supply arrangement being adapted to conduct the water essentially to a discharge end of the conveyor arrangement for carrying the vapor flow, jointly with the pyrolysis gas, in a counterflow relative to the longitudinal direction of the process space towards the conveyor arrangement's supply end.

7. The apparatus according to claim 6, characterized in that the supply arrangement is adapted to discharge the to-be-produced pyrolysis gas in the longitudinal direction of the process space prior to supplying the to-be-processed feedstock.

8. The apparatus according to claim 6, characterized in that it comprises a conveyor arrangement, which is housed in the process space, is at excess pressure relative thereto, and is provided with the supply and discharge elements substantially gastight relative to the environment.

Description

[0021] In a further preferred embodiment, the transport capacity of a conveyor arrangement 3, such as one or more screw conveyors 3a, can be changed in the longitudinal direction s of the process space especially for reducing the layer thickness of the to-be-processed feedstock x from the supply end I of the conveyor arrangement 3 towards its discharge end II. Hence, the conveyor arrangement 3 is preferably implementable e.g. with a screw conveyor 3a provided at its upstream end with smaller pitch and at its downstream end with a larger pitch.

[0022] It is further possible to implement the air supply for a gas burner arrangement 7, such as for one or more parallel gas burners 7a, with a separate combustion air fan. On the other hand, it is further possible, in connection with the gas burner 7a, to also preferably make use of e.g. an ejector fan for sucking the pyrolysis gas y by way of an ejector nozzle into the gas burner.

[0023] In a further preferred embodiment, it is also possible with a method of the invention to process mutually dissimilar feedstocks x, w by bringing the same, as indicated e.g. in the attached process flow chart, into the conveyor arrangement by separate supply elements 1a, the feedstocks delivered therefrom blending with each other while being pushed by the screw conveyor 3a towards the process space. In this context, it is naturally also possible to proceed in such a manner that various feedstocks are mixed with each other in a separate mixing space and delivered with a single supply element into the conveyor arrangement 3.

[0024] In yet another preferred embodiment, there is executed in the process space a nitrogen reduction, carried out e.g. with a so-called SNCR (Selective Non-catalytic Reduction) method, by using an additional nozzle arrangement is for supplying the combustion chamber 4 with an ammonia-containing medium, such as urea spray, aqueous ammonia solution or the like. By placing the aforementioned nozzle arrangement at a point marking the end of a gas flame burning zone, the medium sprayed by way of the nozzle arrangement evaporates, whereby the resulting ammonia is blended and has time to effect on flue gases long enough for a meaningful nitrogen reaction. Additionally, in a method of the invention, there is further ensured, preferably e.g. with a lambda sensor, that the combustion is permanently provided with excess air.

[0025] In a further preferred embodiment of the invention, the supply of additives into the non-energent to-be-produced biocoal x′ is implemented by admixing with the water z to be delivered into the conveyor arrangement 3.

[0026] On the other hand, the invention relates also to an apparatus for implementing the aforementioned method, the apparatus including: [0027] supply elements 1a for introducing a to-be-processed feedstock x into the interior of a conveyor arrangement 3 present in and closed relative to a Thompson Converter type process space 2 for moving the to-be-processed feedstock x in the process space 2 in a longitudinal direction s of the process space, [0028] a flow arrangement 8 for conducting a pyrolysis gas y, generated from the to-be-processed feedstock x present in the conveyor arrangement 3 as a result of heat transferring thereto from the process space, away from the conveyor arrangement for burning the same in a combustion chamber 4 of the process space, [0029] a discharge arrangement 5 for removing a resulting fuel gas y′ from the process space, [0030] discharge elements 1b for the removal of a produced non-energent biocoal x′ from the conveyor arrangement for further processing, and [0031] a most preferably continuously operating gas burner arrangement 7 for burning the pyrolysis gas y,

[0032] whereby the heat transfer for the conveyor arrangement 3 in the process space 2 is adapted to occur with substantially direct radiation from a flame of the gas burner arrangement 7 and from walls of the combustion chamber 4. In addition, the flow of the pyrolysis gas y within the conveyor arrangement 3 takes place in a counterflow towards a supply end I of the conveyor arrangement for transferring the heat present in the pyrolysis gas into the to-be-processed feedstock x moving in an opposite direction s and for delivering the cooled pyrolysis gas y to the gas burner arrangement 7. The apparatus further includes a supply arrangement 1c for conducting water z into the interior of the conveyor arrangement 3, for reducing/eliminating by means of water vapor z′ the amount of PAH compounds contained in the to-be-produced non-energent biocoal x′, the supply arrangement 1c being adapted to conduct the water into the interior of the conveyor arrangement 3 essentially to a discharge end II of the conveyor arrangement for carrying a vapor flow z′, jointly with the pyrolysis gas y, in the longitudinal direction s of the process space towards the conveyor arrangement's supply end I.

[0033] Referring to the attached process flow chart, it is in a preferred embodiment of the invention that a discharge pipe 1a′ for pyrolysis gas is disposed in a longitudinal direction upstream of the to-be-processed feedstock supply arrangement 1a. In the attached process flow chart there is further presented a supply arrangement 1e for delivering water mist into the pyrolysis gas y′ for adjusting its moisture and temperature. In addition, the apparatus preferably includes a cooling arrangement 1d for cooling the produced non-energent biocoal x′ with a water/water vapor circulation implemented preferably on the counterflow principle.

[0034] In a further preferred embodiment of the apparatus, it comprises a conveyor arrangement 3, which is housed in the process space 2, is at excess pressure relative thereto, and is provided with the supply and discharge elements 1a, 1b substantially gastight relative to the environment, the benefits associated therewith having already been described above.

[0035] It is obvious that the invention is not limited to the embodiments presented or described above, but can be varied within the basic concept of the invention so as to comply with given intended uses and applications. Accordingly, it is first of all clear that, with regard to the combustion process, the method can be conducted by making use of per se conventional control technology and automation e.g. with oxygen analyzers and temperature sensors needed in the combustion of pyrolysis gas and/or by using e.g. a preheating burner. Respectively, for the processing of to-be-processed feedstock it is possible to provide the screw conveyor arrangement with necessary monitoring arrangements for enabling optimal carbonization and final temperature e.g. by stepless regulation of the screw conveyor arrangement's operation. It is naturally possible that the apparatus applying a method of the invention be preferably further provided e.g. with optical flame monitoring analyzers and e.g. with a “torch tube” 12 according to the drawings, which is connected to the conveyor arrangement and by which the pyrolysis gas can be released, if necessary, by combustion with a separate burner, the torch tube thereby functioning as a relief valve enabling a rapid emergency switch-off of the apparatus.