JPS649360B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims at heating low-grade coal, such as lignite, in which moisture is released in liquid form when heated in an atmosphere where moisture cannot evaporate (hereinafter referred to as a non-evaporation atmosphere), in a non-evaporation atmosphere. After that, the dehydration method further evaporates and lowers the water content by reducing the pressure of the atmosphere. Specifically, the liquid dehydrated product is separated and isolated from the hot water consisting of separated water and condensed water, and the depressurization operation is performed separately. Concerning dehydration methods.

In this specification, the term "low-grade coal" refers to 1. low-grade coals such as sub-bituminous coal and lignite (coal with a low degree of coalification); 2. coal analogues such as lignite, peat, and grass coal (with a low degree of coalification). 3. Coal source materials such as plants and their decayed materials (organic solids that are assumed to transform into coal when subjected to coalification) More simply, it is defined as ``a porous organic solid that loses water in liquid form when heated in an atmosphere where water cannot evaporate.''

In general, flash drying methods and indirect heating drying methods have been conventionally used in various industrial fields to dehydrate organic solids such as lignite. However, in these prior art techniques, dehydration is carried out by evaporating water, which has disadvantages such as high heat consumption and pulverization of the dehydrated product. Therefore, the development of alternative technologies has been underway for some time.

By the way, when a high-moisture porous organic solid that has not been fully coalized, such as lignite, is heated in a non-evaporating atmosphere, physical and chemical changes similar to natural coalification occur, It is known that water contained in the pores of these solid materials is released in liquid form. As a dehydration method utilizing this liquid dehydration phenomenon, there is a method of heating lignite in a saturated steam atmosphere (hereinafter referred to as saturated steam dehydration method).

An example of a practical application of this technology is a lignite dehydration method in which multiple pressure vessels of the same shape are subjected to batch treatment with time lags in the treatment process, as disclosed in Austria Patent No. 190490. For example, the first
The figure is a system diagram showing an example of saturated steam dehydration method.
Processing is performed in the procedure shown in FIG. This processing process will be briefly described as follows. The same suffix is given to pressure vessels and their accessories to distinguish them from other pressure vessels.

After charging the lignite to be dehydrated at atmospheric pressure into the pressure vessel 1a and preheating it (the preheating procedure is as follows:
(Saturated steam is supplied from an external steam source 11 through the pipe line 3a, and the temperature is increased to perform liquid dehydration. The hot water mixed with the condensed water of the saturated steam generated at this time and the water dehydrated from the lignite passes through the drain plate 8a and passes through the pipe line.
4a and is stored in the hot water reservoir 2a. The pressure vessel 1a and the hot water reservoir 2a, which are in a high pressure state after completing the heating process, are placed in the upper space of the pressure vessel 1a, for example, in a pressure vessel (not shown) adjacent to the pressure vessel 1b, which is in a low pressure state and is in the preheating process. Steam (steam in the containers 1a, 2a, and steam generated from lignite residual moisture and hot water) is supplied through a pipe line 5a and a pipe line 10, one end of which faces the tank. and,
This steam preheats this pressure vessel (not shown). Thereafter, the pipe line 5a is shut off, and residual heat water is supplied to the pressure vessel 1b into which the coal has just been charged through the pipe line 6b, and the pressure is lowered to atmospheric pressure. At the same time, pressure vessel 1b
is preheated by this hot water. In this depressurization process, the remaining moisture in the lignite is reduced by evaporation and drying, while the steam and hot water are used as a preheating source for the dehydrated lignite in another pressure vessel to recover its retained heat.

In such a saturated steam dehydration method, the steam generated from the hot water reservoir 2a during the depressurization process ascends the lignite layer in the pressure vessel 1a through the pipe 4a and flows out from the pipe 5a. It has the disadvantage that moisture is reabsorbed by the lignite layer, reducing the dehydration rate. That is,
In conventional depressurization operations, the pressure vessel loaded with lignite, which evaporates and dehydrates residual water, and the hot water reservoir, which stores hot water used as a preheating source, remain in communication and are depressurized as one unit. As a result, the cooled lignite surface is partially formed, and the steam generated from the hot water condenses there and absorbs moisture into the lignite, reducing the dewatering efficiency.

The present invention aims to solve the above problems of the conventional saturated steam dehydration method. More specifically, the method for dehydrating organic solids using the above-mentioned batch processing method involves liquid dehydration using saturated steam heating and evaporation dehydration using reduced pressure without transporting the organic solids, which are low-rank coal, sealed in a pressure vessel. It also solves the problems of the dehydration method described above, in which the hot water generated during liquid dehydration by saturated steam heating is used as a preheating source, separated from lignite, and stored in a reservoir. This is what I am trying to do. That is, the depressurization operation of the pressure vessel in the saturated steam dehydration method using the batch processing method is carried out so that the dehydration rate does not decrease due to condensation of the steam generated from the hot water storage device, and moreover, heat is effectively recovered from this hot water. The purpose is to provide a dehydration method.

In the present invention, low-rank coal is sealed in a pressure vessel, heated directly with saturated steam to dehydrate it into a liquid state, and the hot water generated at this time is separated from the low-rank coal and stored in a reservoir. In the method of evaporating and dehydrating the residual moisture of the low-rank coal by reducing the pressure in the pressure vessel with the low-rank coal sealed therein, the pressure vessel containing the low-rank coal and the reservoir storing hot water are separated and isolated. This is a method for heating and dehydrating low-rank coal, which is characterized by reducing the pressure.

In a preferred embodiment, the pressure vessel and the reservoir are simultaneously communicated with another separate pressure vessel containing low-rank coal, so that saturated steam discharged from the pressure vessel and discharged from the reservoir The present invention is characterized in that the saturated steam and hot water are used as preheating sources for heating and dehydrating the low-rank coal sealed in the other separate pressure vessels.

Additionally, in a preferred embodiment, the pressure reduction of the pressure vessel containing the low-rank coal is completed in a shorter time than the pressure reduction of the hot water reservoir, and while the hot water reservoir is performing the remaining pressure reduction. A feature of the system is that dehydrated low-rank coal is discharged from the pressure vessel.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a partial system diagram of an embodiment of the present invention, and FIG. 4 is a dehydration process diagram. In addition,
Portions that overlap with those of the prior art shown in FIG. 1 are given the same reference numerals and explanations are omitted. 31a is a pipe line connecting the steam recovery pipe 10 and the hot water storage device 2a, and has a valve 35a. Numerals 32a and 33a are conduits connecting the upper and lower parts of the pressure vessel 1a and the conduit 31a, respectively, and valves 30a and 33a are respectively connected to the conduit 31a.
It has 4a.

With the above configuration, the present invention performs coal injection, preheating, heating and depressurization, and coal discharge operations in the same manner as the prior art, but the preheating and depressurization operations are performed in the following three stages. The explanation will be given from a state in which the pressure vessel 1a finishes its heating process and starts depressurizing. First, by shutting off the valve 35a, the hot water reservoir 2a is closed.
After isolating from the pressure vessel 1a, the valves 30a, 3
4a is opened, and steam is introduced into another pressure vessel (not shown) adjacent to the pressure vessel 1b through the steam recovery pipe 1 to evaporate and dehydrate the remaining moisture of the lignite in the pressure vessel 1a, and at the same time, the steam is introduced into the pressure vessel (not shown) adjacent to the pressure vessel 1b. Preheat. Next, the valves 30a and 34a are closed to hold the pressure vessel 1a airtight, while the valve 35a is opened to allow steam evaporated from the hot water in the hot water reservoir 2a to pass through the pipes 31a and 10 to the pressure vessel 1a. Steam is introduced into the same pressure vessel into which it is preheated, and at the same time, the pressure of the hot water storage vessel 2a is reduced. Conventionally, these two depressurization (preheating) operations were performed at once by integrating the pressure vessel and the hot water reservoir.

Next, the residual hot water in the hot water reservoir 2a is sent to the adjacent pressure vessel 1b through the pipe line 6b, and the pressure reduction is completed. In parallel with this depressurization operation of the hot water reservoir 2a,
The pressure vessel 1a is connected to the pipes 32a, 10, 31b, 3
2b to the pressure vessel 1b to evaporate the residual water content of the lignite. In this way, the heat of the steam from the pressure vessel 1a can be recovered, and the steam from the hot water storage device 2a is less likely to enter the pressure vessel 1a, so there is no problem like the conventional method. Further, after the pressure vessel 1a is communicated with the pressure vessel in the preheating process and the pressure is reduced, air is immediately released to the outside through the pipe 9a without communicating the pressure vessel 1b as described above, and the pressure is rapidly reduced to atmospheric pressure. The inventors have confirmed through experiments that more effective dehydration can be achieved by doing so.

FIG. 5 is a partial system diagram of another embodiment of the present invention, and FIG. 6 is a dehydration process diagram thereof. The steam recovery piping 10 connects the upper part of the pressure vessel 1a and the valve 42.
a and a pipe 45a having a hot water reservoir 2a and a valve 46a, respectively. The lower part of the pressure vessel 1a is connected to the upper part of the attached hot water reservoir 2a by a pipe line 44a having a valve 42a, and to the upper part of the pressure vessel 1b, which is connected to the hot water recovery pipe 6b, by a valve 48a. The connection is made through a conduit 43a having a conduit 43a.

Even with the above configuration, as in the previous example,
During the pressure reduction operation, the pressure vessel and the hot water reservoir are isolated and the pressure is reduced separately. For example, pressure vessel 1a,
When depressurizing the hot water reservoir 2a, immediately after heating is completed, the valve 47a of the pipe line 44a is closed, and the pressure vessel 1a is opened by opening the valve 48a.
The lignite in the pressure vessel 1b is communicated with the adjacent pressure vessel 1b via the pressure vessel 3a to evaporate residual moisture in the lignite in the pressure vessel 1a and preheat the brown coal in the newly charged lignite in the lb. Note that the valve 42a remains closed. In this example, steam from the hot water reservoir 2a is recovered in parallel with the pressure reduction of the pressure vessel 1a. That is, the conduit 45
Steam is introduced into another pressure vessel (not shown) through a and 10. Therefore, since the hot water is not held as in the previous example, the contact time with the lignite becomes relatively long, and the heat amount of the hot water can be effectively utilized. The pressure vessel 1a performs the above operations to reduce the pressure to atmospheric pressure, and then discharges the product charcoal. On the other hand, after the hot water in the hot water storage device 2a generates steam and recovers heat by the above-mentioned operation, the hot water is introduced into the preheated pressure vessel 1b through the hot water recovery piping 6b as in the conventional method. further preheat the brown coal. According to this procedure, there are pressure vessels that must be preheated and depressurized, and there is no need to provide a hold period, so the operation can be continued without waste.

Furthermore, research by the inventors has revealed that the dehydration rate can be improved if the pressure is rapidly reduced by, for example, opening the pressure vessel on the preheating side to the atmosphere. However, opening to the atmosphere from the initial stage of depressurization results in a large amount of heat loss due to the dissipation of steam, so conventionally, the atmosphere is opened to the atmosphere immediately before the coal is discharged when the temperature has decreased. Therefore, the rate of pressure reduction is slow. According to the present invention, only the pressure vessel on the pressure reduction side communicates with the pressure vessel on the preheating side and the hot water reservoir, and the amount of steam generated in the pressure vessel on the pressure reduction side is small, so that the pressure is rapidly reduced to a low pressure. Even if it is opened to the atmosphere after or during this operation, there is an advantage that the amount of heat lost is small.

As described above, according to the present invention, since the depressurization operation of the organic solid is performed separately from the hot water, the steam generated from the hot water is not re-absorbed by the organic solid, and the dehydration rate is improved. . In addition, since depressurization operations can be performed independently, each with a different main purpose: evaporation dehydration for organic solids and heat recovery for hot water, for example, organic solids can be quickly and quickly removed from hot water. Thermal efficiency is also improved because the pressure can be reduced by gradually bringing it to equilibrium.

[Brief explanation of drawings]

Fig. 1 is a partial system diagram showing an example of the saturated steam dehydration method, Fig. 2 is a dehydration process diagram, Fig. 3 is a partial system diagram of an embodiment of the present invention, and Fig. 4 is a dehydration process diagram. , FIG. 5 is a partial system diagram of another embodiment of the present invention, and FIG. 6 is a dehydration process diagram thereof. 1a, 1b...pressure vessel, 2a, 2b...hot water reservoir.

Claims (1)

[Scope of Claims] 1. Low-rank coal is sealed in a pressure vessel and is directly heated with saturated steam to dehydrate it into a liquid state, and the hot water generated at this time is separated from the low-rank coal and stored in a reservoir. Then, in the method of depressurizing the pressure vessel with the low-rank coal sealed therein to evaporate and dehydrate the residual moisture of the low-rank coal, the pressure vessel containing the low-rank coal and the reservoir storing hot water are separated and isolated. A method for heating and dehydrating low-rank coal, which is characterized by heating and depressurizing the coal. 2 simultaneously communicating the pressure vessel and the storage vessel with another separate pressure vessel containing low-rank coal;
Utilizing the saturated steam discharged from the pressure vessel and the saturated steam and hot water discharged from the storage vessel as preheating sources for heating and dehydration of the low-rank coal sealed in the other separate pressure vessel. A method for heating and dehydrating low-rank coal according to claim 1, characterized in that: 3. The depressurization of the pressure vessel filled with low-rank coal is completed in a shorter time than the depressurization of the hot water reservoir, so that water is dehydrated from the pressure vessel while the hot water reservoir is depressurizing the remaining amount. 3. A method for heating and dehydrating low-rank coal according to claim 1 or 2, wherein the low-rank coal is discharged.