JPS6023487A - Viscosity-reducing agent for coal-water slurry having high concentration - Google Patents

Abstract

PURPOSE:To provide a viscosity-reducing agent for coal-water slurry having high concentration, lowered slurry viscosity and improved fluidity and safety suitable for the transport with a pump, by using sodium lignin sulfonate and a polyphosphoric acid salt as essential components. CONSTITUTION:The objective viscosity-reducing agent contains, as essential components, (A) usually 5-95wt% (preferably 20-80%) sodium lignin sulfonate and (B) usually 95-5% (preferably 80-20%) polyphosphoric acid salt (e.g. sodium pyrophosphate, sodium tripolyphosphate, potassium polymetaphosphate, etc.). The component A can be produced by the sulfonation of wood chips.

Description

[Detailed description of the invention] The present invention relates to a thinner for coal-water slurries.

More particularly, it relates to a thinning agent for dispersing pulverized coal in water to provide a highly concentrated coal-water slurry that can be pumped.

In recent years, due to the depletion of oil resources, the use of coal has been reconsidered.
There are various ways to use it.

However, unlike oil, coal is a solid and cannot be transported by pump. For this reason, various methods are being considered for pulverizing coal and dispersing it in water to form a water slurry. Also,
In the second stage of "coal gasification," attempts are being considered to supply coal to the gasification reactor in the form of a water slurry.

However, with the current technology, as the coal concentration increases, the viscosity of the coal increases significantly and there is no flow rate, making pumping difficult. On the other hand, lowering the coal concentration lowers transportation efficiency, requires a dehydration step before combustion, and coal gasification has many problems, such as the inability to obtain a sufficient reaction temperature.

JP-A No. 57-96090 describes that organosulfonic acid earth metal salts and organosulfonic acid earth metal salts are used in combination with alkali metal buffer salts as a pH adjuster to adjust the slurry p)I to 5 to 8. The earth metal sulfonic acid has a weak viscosity-reducing effect, partly because of its small dissociation into water, and even if an alkaline buffer salt is used in combination, it is not possible to increase the concentration. Although the details will be described later, it was not possible to produce a practically usable slurry using these chemicals.

The present inventors fluidized a highly concentrated coal-water slurry,
We have conducted extensive research into the viscosity reducing agent for coal-water slurries that enables pumping, and with the addition of a small amount, the viscosity of coal-water slurries can be significantly reduced, resulting in coal that can be transported by pump even at high coal concentrations. Successfully developed a viscosity reducing agent that provides water slurry.

Coal used in the coal-water slurry of the present invention includes anthracite, bituminous coal, sub-bituminous coal, lignite, and cleaned versions thereof, but any coal may be used. In addition, the particle size of the coal in the water slurry may be any particle size as long as it is powder, but since the pulverized coal currently burned in thermal power plants is 70% by weight or more of 200 mesh pass, this particle size is This is a guideline for the particle size of pulverized coal. However, the thinner of the present invention is not affected by particle size and exhibits excellent effects on coal powder of any particle size.

Cleaned coal is coal from which inorganic substances, such as ash and sulfur, have been removed. As a method for cleaning coal, for example, Oil Aggl
There are methods such as on method (hereinafter referred to as OA method), flotation method, and heavy liquid separation method. However, methods other than these may be used and are not particularly limited.

Regarding the OA method, after dry or wet pulverization of coal, a water slurry is prepared, and if necessary, an appropriate amount of oil with a surfactant added thereto is added, or after the oil is cordoned into the coal in advance, a water slurry is prepared. By adjusting and stirring, the organic content of the coal is coagulated using the oil that selectively wets the organic content of the coal as a binder, taking advantage of the difference in wettability of the organic content of the coal and the inorganic content to oil and water.

On the other hand, since inorganic substances have a weak affinity with oil, they are liberated in water, so if water is separated from the aggregated coal, the inorganic substances can be removed at the same time. OA method coal
The coal concentration in the water slurry is usually 10-50% by weight.

The oil used in the OA method is crude oil or various fractions obtained from crude oil, such as kerosene, light oil, A heavy oil, B heavy oil, C heavy oil, etc., tar or shale oil, ethylene cracked residue, or various blended oils, and is generally used as a fuel. Mineral oils such as oils used as oils, lubricating oils, and cleaning oils. Water-insoluble oils such as benzene, toluene, xylene, and animal and vegetable oils may also be used, but among these, heavy oils such as C heavy oil and tar residue oil are particularly preferred because they are inexpensive. It is generally sufficient to use this oil in an amount of 3% or less by weight of the coal in the coal-water slurry to be treated for mineral removal.

In addition, the flotation coal washing method is an existing coal washing method in which a very small amount of oil is added to the pulverized coal-water slurry and foamed by stirring.
Generate floss. This method is also similar to the OAA method, in which the organic components of coal adhere to the froth oil film, but the inorganic components are liberated in the water and can be separated from the organic components of coal.

The oils used in the flotation method are terpineol, tar, heavy fuel oil, carbon heavy oil, light oil, and kerosene.

It is common to remove inorganic substances weighing more than several tens of pounds by weight from coal by the Goh method.

If coal cleaned in this way is used, the effect of the additive of the present invention is significantly superior to that of coal that has not been cleaned, and a coal-water slurry with several points higher concentration can be obtained. In addition to this effect, when cleaned coal is used, boiler corrosion during combustion is suppressed, and ash removal equipment is used.

Benefits 1 to 1 are very large, such as reducing the burden on desulfurization equipment.

Next, the thinner used in the coal-water slurry of the present invention is a thinner for high-concentration coal-water slurry used to reduce the viscosity of the coal-water slurry and improve fluidity and stability. It is characterized by containing (a) monohelium ligninsulfonate and (b) polyphosphorus hydrochloric acid as essential components.

The component (a), sodium ligninsulfonate, is
It is obtained by sulfonating wood chips, and it is a modified sodium lignin sulfonate that undergoes hydrolysis, oxidation, desulfonation, demethylation, etc. during the chemical treatment process, and condensation through condensation reactions. Refers to sodium ligninsulfonate, etc.

The polyphosphate which is the component (b) refers to one containing two or more P (oxidation number 5) and having a P-0-P bond.

Specifically, there are 1-lium pyrophosphate, sodium 1-helipolyphosphate, 1-lium polymetaphosphate, potassium pyrophosphate, potassium tripolyphosphate, potassium polymetaphosphate, and the like.

The thinner of the present invention contains at least one of the above components (a) and (b), and the blending ratio is (a) 5-95% nail shape, b) 95-95% nail shape. 5% by weight, preferably (a) 20-80% by weight, (b) 80% by weight
~20% by weight.

The amount of the thinner of the present invention added is 0.000 to the coal-water slurry. O1-5.0% by weight, preferably 0.03-2.
It is 0% by weight, and excellent effects are exhibited with this added amount. The fluidity limit of a coal-water slurry varies depending on the type and particle size of the coal, but in general, unless a thinner is added,
It loses fluidity when the coal concentration is around 50% by weight, but if the viscosity reducing agent of the present invention is added, the viscosity decreases significantly, so it has fluidity even when the coal concentration is 61% by weight or higher.
It is something. When using even cleaner coal, the coal concentration increases by several points, generally 3 to 10
points increase.

The thinner of the present invention can also be used in combination with other surfactants.

Regarding the method for producing coal-water slurry and the method for adding a thinner, there are two methods: dry pulverizing coal in advance and then mixing a thinner into an aqueous solution; How to add coal, water,
Any method can be used, such as adding a thinning agent and mixing the coal while pulverizing it, or using cleaned coal instead of coal in each method.

The thinning agent of the present invention is characterized by the combined use of organic and inorganic high molecular weight dispersants, 1-lium ligninsulfonate and polyphosphate.

The reason why these drugs are so effective is that
Sodium salt of ligninsulfonic acid has a relatively large dissociation in water, but due to its special structure, it is strongly adsorbed to the surface of a single particle, and then electrostatic factors prevent the particles from agglomerating and form secondary particles. Stabilize. At the same time, it is thought that the dispersion by the electrostatic repulsion of the polyphosphate exhibits a remarkable synergistic effect, producing an excellent viscosity-reducing effect that would be unimaginable if each of them were used alone.

Moreover, when using the thinner of the present invention, slurry = p +-
1 is written in Japanese Unexamined Patent Application Publication No. 57-96090.
It is larger than the neutral range of 8. In other words, (b) of the present viscosity reducing agent
It is believed that the component plays the role of a dispersant, imparting a strong charge and producing an excellent synergistic effect with component (a), completely independent of pH adjustment.

In addition, if you use clean coal that has been deashed, the effect will further increase.During deashing, the ash, which is highly hydrophilic and has fine particles with a large surface area, is removed. This is because the thinner of the present invention effectively acts on the coal surface, which has improved viscosity, thereby making it possible to increase the coal concentration.

The thinner of the present invention has an excellent effect of stably dispersing coal in water, and even if it is left standing for a long period of time, for example, one month, it does not cause water separation and maintains a homogeneous coal-water slurry. There is.

Thus, the thinner of the present invention is preferably 0.01 to 5.0% by weight, preferably 0.03 to 2.0% by weight, based on the coal-water slurry.
Addition of 0% by weight can significantly reduce the viscosity of a coal-water slurry and create a highly concentrated coal-water slurry that can be pumped.

Examples are shown below. In the examples, percentages are by weight.

Example 1 Into an aqueous solution containing a predetermined amount of the thinner shown in Table 1,
Coal pulverized to 0 mesh 80% pass is added at room temperature with stirring to prepare a coal-water slurry of a predetermined concentration. The viscosity of this slurry is measured at 25° C., and the fluidity is also observed. Furthermore, this slurry was poured into a 500mQ cylinder to a height of 18c11, and the slurry was heated for 1 month.
After placing the top layer (1cm from the top) and the bottom layer (1cm from the bottom)
Measure the coal concentration in cm).

The test results are shown in Table 2. As shown in Table 2, when the thinner of the present invention is added, the viscosity is 1000 to 2600 (2P) even at a coal concentration of 64 to 70%, and the fluidity is extremely good.

In addition, even after the slurry has been allowed to stand for one month, there is almost no sedimentation of the coal, and it is very stable. On the other hand, when a general anionic surfactant is added or no thinner is added, the viscosity is 20' at a coal concentration of 50%.
, 0OOcP or more, and there is no flow at all.

In addition, when component (a) or component (b) is added alone,
When a general inorganic salt is used as a pI-] regulator in component (a), the thinning effect is extremely weak, and the coal concentration is 6.
At 0%, the viscosity is around 20°000 cP, and there is no flow at all.

Example 2 A clean coal-water slurry of a predetermined concentration is prepared in the same manner as in Example 1 using cleaned coal. The coal efficiency is 80% pass of 200 mesh. The viscosity of this slurry was measured at 25°C, and the fluidity was also observed. After this slurry was allowed to stand for one month, the coal concentrations in the upper and lower layers were measured in the same manner as in Example 1.

The thinners of the present invention used in the test are shown in Table 1. The test results are shown in Table 3.

As shown in Table 3, when the thinner of the present invention is added to the cleaned coal-water slurry, the viscosity is 1200 to 2700 cP even when the coal concentration is 68 to 70%, and the slurry has a low viscosity and good fluidity. In addition, the slurry is extremely stable with almost no coal settling even after it has been allowed to stand for one month.

In contrast, adding a general anionic surfactant or
In the case where no thinning agent is added, the viscosity is 20,000 cP or more at a coal concentration of 50%, and there is no flow at all.

In addition, when component (a) or component (b) is added alone,
When a common low molecular weight inorganic salt is used as a pH adjuster in component (a), the thinning effect is extremely weak, and at a coal concentration of 60%, the viscosity is around 20.0.00 cP, and there is no flow at all.

Claims (3)

[Claims] (1) A thinning agent for highly concentrated coal-water slurry used to lower the viscosity of coal-water slurry and improve fluidity and stability, the agent comprising: (a) lignin sulfonic acid 1- A thinning agent for coal-water slurry, characterized in that it contains as essential components a polyphosphate and (b) a polyphosphate. (2) The blending ratio of component (a) and component (1)) is (a) 5 to
95% by weight, (b) 95-5%, preferably (a)
2 C1-80% by weight, (b) 80-20% by weight, the thinner for coal-water slurry according to claim (1). (3) A thinning agent for coal-water slurry according to claims (1) and (2) for use in a coal-water slurry having a coal concentration of 61' or higher. (/l) The thinner for coal-water slurry according to any one of claims (1) to (3), wherein the coal is cleaned coal.