WO2017123117A1 - Device for intensive energy-efficient drying and heat processing - Google Patents

Abstract

A device for the intensive drying of materials via pressurized superheated steam which is formed from moisture in the materials to be dried, and which circulates in the device between heaters and a drying chamber by means of steam jet pumps. Removed moisture steam is heated and sent to drive a turbine, which turbine is protected from contamination by using a separated heat exchanger in which clean steam is generated by cooling and condensing the moisture steam. A portion of the condensed steam is sent to a water pump, which increases pressure to a level higher than the pressure in the drying chamber, and, following evaporation and superheating, said steam is used in the steam jet pumps for circulating the steam used for drying, for transporting material within the chamber, and for other such needs, thus replacing a mechanical/electrical drive. The device operates by supplying heaters/superheaters with heat, which is derived, for instance, from burning a portion of the dried material, or from another source of hot media.

Description

 Title of invention

 Intensive energy-saving drying and heat treatment device

Technical field

 The object of the invention relates to devices for intensive drying and heat treatment of wet materials with superheated steam under pressure. First of all, the device is intended for drying biofuels, lignite, various organic waste, agricultural products and animal husbandry, when they are used in energy as fuel, in order to improve its quality, as well as in preparing biofuels for further processing - pelletization (production of fuel pellets ), torrefaction (torrefaction - heat treatment up to 250 ° С with imparting hydrophobicity to the fuel), pyrolysis and gasification. Intensive drying and heat treatment, which are carried out in a gas-tight chamber with superheated steam under pressure significantly higher than atmospheric, does not create uncontrolled atmospheric emissions, in comparison with traditional methods of drying and processing combustible organic matter, therefore the device can also be effectively used in preparation for the thermal destruction of anthropogenic and other types of waste.

 State of the art

Analogues of the specified device are many in the patent literature. For example, patent application [EP 1466131A1 (WO 03/052336 A1), inventor Christensen, Apparatus for Drying a Particulate Product with Superheated Steam, 2003]. Here, the drying chamber is under a pressure of 0.2 - 0.5 MPa, feed devices with a shutter, such as a screw or a lock, are used to enter the material for drying (i.e. raw materials), an unloading device also with a shutter (screw or Gateway). Drying steam circulates in the chamber due to a mechanical flow inducer at tedding wet mass is also mechanically driven. The circulating steam passes through a heating heat exchanger. The heat generated by the steam is expended on the evaporation of moisture from the feed. The drained mass is discharged. The resulting pair of low parameters can be disposed of.

The main disadvantage of this type of intensive drying methods is the energy loss of the heat of the phase transition during the evaporation of the moisture removed. Let us turn to solutions in which the energy of vapor evaporated under pressure significantly higher than atmospheric is used to drive a heat engine — a steam turbine, or gas turbine unit operating according to a scheme with steam injection (the common abbreviation of this scheme is STIG), and where the additional work of steam in significantly compensates for the heat consumption for drying. Corresponding technical solutions are described in [US Patent No.3946495, A. Osdor, 1976], [Batenin V.M. and Kovbasyuk V.I., On the technology of efficient use of wet fuels, Thermophysics of high temperatures, vol. 53 N ° 3, 2015, p. 475-477] and [V. Kovbasyuk, Energy-Saving Drying and its Application, Thermal Engineering Volume 62, N-> 9, 2015, pp. 673-677]. The last of these works describes the use of a separation heat exchanger to produce pure steam for a turbine due to the energy of steam generated in the drying chamber. This work can be considered as a prototype of the invention. The problem of these solutions is the selection of suitable methods for organizing the most intensive drying process in the chamber, which does not require too complicated equipment and significant costs of mechanical energy. Based on the experience of traditional drying of biofuels for their effective use in connection with the world trend to reduce CO2 emissions, where the fluidized bed technology has shown the highest efficiency over the past decade, it is necessary to ensure such regimes in drying devices with steam energy output to the turbine drive ( should consider such a regime energy saving). However, this technology is based on the use of intensive purging of the material to be drained with hot coolant, which is, firstly, difficult to organize in a high pressure chamber on superheated steam, and secondly, such a purge requires additional energy.

 Disclosure of invention

 Nevertheless, it is proposed to make changes to the design of the intensive energy-saving drying device, which will allow very effective implementation of the regimes with a wet mass purge with superheated steam, such as bubbling, fluidized bed treatment or in a gushing mode in a steam stream. In this case, it is fundamentally possible to even reduce the cost of mechanical energy for the specified processing of wet material.

 To achieve these goals, it is proposed:

1. A device for intensive energy-saving drying and heat treatment, containing a gas-tight chamber for superheated steam under pressure, with a shut-off device for introducing wet masses, with a device for moving the drained material in the chamber, with circulation of the superheated steam in the drying device, its heating in an external heat exchanger, and evaporation moisture in direct contact of superheated steam with a wet mass, with a device for outputting the dried mass through an unloading device with a shutter, and the removal of part of the steam corresponding to the vapor moisture on the heating side of the separation heat exchanger, where, after taking heat for heating and evaporating clean water along the heated side to get working steam to the turbine drive, the condensed moisture vapor is discharged to the drain, with the difference of a drying device, which is from the condensed material path of the material part of the condensate is supplied through an additional pipeline to the pump, which increases the pressure in the line behind the compressor significantly higher than the average pressure in chamber, and this moisture is supplied to an additional heat exchanger for evaporation and overheating, from where higher pressure steam enters the device through its distribution system in the chamber for bubbling, and / or the creation of a fluidized or gushing layer.

 2. The device according to claim 1, in which a steam ejector is used as a stimulator of steam circulation, and the pressure steam specified in claim 1 is supplied to it as an ejection gas.

 Brief Description of the Drawing

 The proposed circuit of the device is presented in figure 1. Positions in the figure: 1 - input of material for drying; 2 - input gateway; 3 - drying chamber; 4 - pipeline heating steam drying; 5 - ejector of circulation of drying steam driven by high pressure steam; 6 - output of heating gases from a heat exchanger of steam heating; 7 - section heating steam drying heating gases; 8 - section heating high pressure steam; 9 - input heating gases; 10 is a line of a high pressure steam distributor with input nozzles in a drying chamber; 1 1 - auger withdrawal of dried material; 12 - drainage gateway of dried material; 13 - conclusion of the material after drying; 14 - high pressure pump supplying part of the steam condensate to evaporation and overheating; 15 - heating section of the separation heat exchanger, where there is cooling and condensation of moisture vapor from the drying chamber; 16 - a device for draining cooled condensate; 17 —heated section of the separation heat exchanger — steam generator of a heat engine; 18 is a design of a heat engine using drying steam to produce mechanical energy (a steam turbine or mixer at the inlet of a gas turbine installation using a circuit with steam injection into a turbine).

 The principle of operation of the device

The device operates as follows. Wet material is introduced under pressure by a screw or through a gateway to the inlet of the drying chamber. Further options are possible. If the material is drying or processing represented by large fragments, overheated steam is blown through a layer of such material for initial drying, after which it is easier to grind, for example, with a jaw crusher, directly in this chamber. If the material, on the contrary, is waterlogged, before entering the chamber it can be mixed with a part of the previously dried mass, and superheated steam is bubbled through a layer of such clumping material. Sufficiently drained mass is easier to grind by various methods, in particular, to a high degree of dispersion. The corresponding device can also be placed in the chamber. Grinding is done so that the small size of the crushed particles contributes to their effective heating, and a high specific surface would contribute to better evaporation of the moisture of the particles. This "geometric" factor is convenient to use just when using high temperature steam jets when blowing, considering that mechanical energy is practically not consumed. The work of “pushing” an incompressible fluid until it evaporates in the heating heat exchanger is extremely small compared to the work of expanding high-pressure steam and is usually neglected. The use of high-pressure steam jets allows the use of ejectors instead of mechanical flow drivers for circulating drying steam in heat and overheat heat exchangers. This is the basis for the creation of a fluidized bed regime during drying or heat treatment in this device. This is the main technical effect of the intensification of the use of such a drying device. An alternative use of high pressure pure water, additionally introduced into the drying device, to create a steam reduces the risk of salt deposition during the generation of such steam, but this additionally loads the system with moisture, which will have to be removed, and poses the problem of obtaining such water. Possibility of implementation

 Let us consider several characteristic engineering solutions for the implementation of such devices of intensive energy-saving drying and heat treatment.

 1. The geometry of the drying and heat treatment chamber. High thermomechanical loads on the body are fundamentally better opposed by the cylindrical structure, and for its horizontal placement, the steam injection system for bubbling should be located along its lower inner generatrix, with a total steam flow above the wet material in the cylinder cavity. For a vertical arrangement, the sparging steam inlet is located at the bottom, and also, in order to maintain intense heat transfer, through the side inlets. It may be useful to install a pulsating (e) flow interrupter (s) in the steam injection line to the bubbler, which should suppress the formation of “fistulas” and “bubbles” that impair heat transfer and probably reduce the need for material mixing. Tilting the camera can allow material to move from entry to exit.

 2. The design of the indicated type of drying chamber may consist of several cylindrical elements assembled in serial or parallel links, interconnected by transport sections for loading material and steam from inlet to outlet, moreover, the heating sections of the drying steam can be autonomous or combined, and for transport screw conveyors may be used.

 3. During drying, the characteristics of the material usually change greatly, and to optimize the process it may be useful to include any of the known material crushing / grinding apparatus directly in one of the drying sections, bearing in mind the placement of the corresponding mechanical drive from the outside.

 Industrial applicability

The implementation of the invention is based on the use of well-known in the technique of means, elements of equipment and structures when used as intended. The only unaffected issue of the operation of the presented device is the procedure for starting and bringing it to the calculated mode. Obviously, for this it is enough to ensure the production of steam at startup of the entire system.

Claims

Device for intensive energy-saving drying and heat treatment  1. A device for intensive energy-saving drying and heat treatment, containing a gas-tight chamber for superheated steam under pressure, with a shut-off device for introducing wet masses, with a device for moving the drained material in the chamber, with circulation of the superheated steam in the drying device, its heating in an external heat exchanger, and evaporation moisture in direct contact of superheated steam with a wet mass, with a device for outputting the dried mass through an unloading device with a shutter, and the removal of part of the steam corresponding to the vapor moisture on the heating side of the separation heat exchanger, from where, after taking heat to heat and evaporating clean water along the heated side to get working steam to the turbine drive, the condensed moisture vapor is discharged to the drain, with the difference of the drying device, which is from the condensed moisture path of the material part of the condensate is supplied through an additional pipeline to the pump, which increases its pressure significantly above the average pressure in the chamber, and this moisture is supplied to the additional heat exchanger for evaporation and overheating a, where a higher pressure steam enters the device through its distribution system in the chamber sparging, and / or creation of a fluidized or spouted bed. 2. The device according to claim 1, in which a steam ejector is used as a stimulator of steam circulation, and the pressure steam specified in claim 1 is supplied to it as an ejection gas. 8 SUBSTITUTE SHEET (RULE 26)