RU2171777C1 - Method of preparing granular sulfur - Google Patents

Abstract

FIELD: chemical industry enterprises that product sulfur as final product. SUBSTANCE: sulfur is cooled and granulated when contacted with cooling agent such as water at 2-65 ^o C. Cooling agent is sprayed by means of nozzles and is directed towards drop stream of sulfur. Nozzles are disposed at angle of 10-90 ^o C. Range of heights is selected proceeding from complete crystallization of sulfur column of water curtain is formed, and dusting of sulfur is thus avoided. Amount of water being fed is batched and calculated according to formula. Invention makes it possible to solve problem of optimally selecting cooling agent, amount and method of feeding it into cooling zone. EFFECT: more efficient preparation method. 3 cl, 1 dwg, 1 ex

Description

 The invention relates to the field of chemical industry and can be used in enterprises receiving sulfur in the form of finished products.

 Air granulation of sulfur is known. ("Sulfur Natural Gas Processing Technology", Handbook M .: Nedra. 1993, pp. 114-115.) During air granulation, the molten sulfur is fed to a disperser located in the upper part of the granulator, which is a cylindrical tower 30 - 90 m high Expiring from the dispersant, droplets of liquid sulfur in free fall are cooled by an upward flow of air and crystallize. Air for cooling sulfur is supplied to the lower part of the granulator tower and is vented by a fan through the louvre grilles from the upper part. Finished products are removed from under the granulator tower.

The method has the following disadvantages:
- high capital costs during the construction of the granulator;
- a sophisticated system for cleaning exhaust gases from sulfur dust;
- explosion and fire hazard of the method.

 There is also known a method of water granulation ("Technology of processing sulfur dioxide", Handbook M .: Nedra 1993, S. 109-111.). In this method, molten liquid sulfur enters a dispersant located in the upper part of the granulator tank, where water is continuously supplied. Drops of liquid sulfur fall into the water and cool, turning into granules. The lower part of the tank goes into a cone with an outlet and a water trap through which the pulp, consisting of water and sulfur granules, is discharged from the granulator tank. Cooling and granulation occur in the thickness of the circulating water layer.

The method has the following disadvantages:
- the resulting sulfur granules have increased fragility due to the high cooling rate;
- granules are obtained in an irregular shape;
- the need for a moisture separation device;
- the need for the completion of finished products;
- the presence of interrelated technological parameters that require tight control.

 The closest adopted for the prototype is a method of steam granulation of sulfur according to auth. 1640105, IPC 5 C 01 B 17/02. In the proposed method, steam is used as a refrigerant. Liquid sulfur flows out of the dispersant located in the upper part of the granulator tank. As you move along the height of the tower, sulfur streams are cooled by an ascending stream of moist saturated steam and solidify. In this case, all the moisture contained in the steam is completely evaporated, dry steam is removed from the upper part of the granulator tank to the separator. Next, the steam is sent to the heat exchanger, where its required temperature and humidity are reached, and sent to the lower part of the granulator tank for reuse.

The method has the following disadvantages:
- a constant increase in the acidity of steam circulating in a closed circuit, which will negatively affect the condition of the equipment and the acidity of the finished product;
- the process is going on in hot mode, which entails increased requirements for equipment and safety standards for maintenance personnel;
- high energy consumption to produce steam.

 The present invention solves the problem of the optimal choice of a cooling agent, the amount and method of its supply to the cooling zone. As a result of solving this problem, energy-intensive, explosive and fire hazardous operations of the granulation process are eliminated and the installation of granulation is structurally simplified.

где c_c - весовая теплоемкость серы;
m_c - масса охлаждаемой серы;
T_н ^с - начальная температура жидкой серы на входе;
T_кр ^с - температура кристаллизации серы;
T_ф ^с - конечная температура серы;
r_c- теплота плавления серы;
c_в - весовая теплоемкость воды;
m_в - масса охлаждающей воды;
T_н ^в - начальная температура воды;
T_ф ^в - конечная температура воды;
r_п - теплота парообразования воды.The essence of the proposed method lies in the fact that the sulfur supplied to the dispersant is cooled and granulated upon contact with a cooling agent - water at a temperature of 2-65 ^o C. The difference of the proposed technical solution is that the water, which is a refrigerant, is sprayed with nozzles and sent to side of the sulfur droplet stream at an angle of 10 - 90 ^o . Nozzles are placed around the drop droplets of liquid sulfur. The height interval at which the nozzles are installed is selected based on the degree of complete crystallization of sulfur droplets. This creates a column of water curtain, eliminating the dusting of sulfur cooled down to the level of granulation. The amount of water supplied dosed is calculated by the formula

where c _c is the weight heat capacity of sulfur;
m _c is the mass of the cooled sulfur;
T _n ^s - the initial temperature of liquid sulfur at the inlet;
T _cr ^{with the} temperature of crystallization of sulfur;
T _f ^s - final sulfur temperature;
r _c is the heat of fusion of sulfur;
c _in - weight heat capacity of water;
m _in - the mass of cooling water;
T _n ⁱⁿ - the initial temperature of the water;
T _f ⁱⁿ - the final temperature of the water;
r _p - the heat of vaporization of water.

 The drawing shows a diagram of a granulator.

 The process is carried out in a granulator, which is a hollow body 1, in the upper part of which there is a dispersant 2, to which liquid sulfur 3 is supplied, flowing out of it by a droplet stream 4. The steam collector 5 is designed to remove excess steam. On the side surface of the granulator body, there are water cooling nozzles 6, to which water is supplied to the cooling zone 7, and humidification nozzles 8, to which water is supplied to moisten the sulfur granules 9. Granular sulfur 10, as it accumulates in the lower part of the granulator, is discharged to the warehouse storage.

 Example.

To implement the granulation process of the proposed method, liquid sulfur 4 with a melting point of 135 ^o C is fed into a dispersant 2 located in the upper part of the granulator body 1. From the dispersant 2, drops of liquid sulfur 3, being in a free fall in the granulator body, fall into the cooling zone 7 and freeze to form granules. The cooling zone is created by nozzles 6, to which water is supplied at a temperature of 2 - 65 ^o C. The nozzles 6 are installed along the perimeter of the housing 1 in the zone of granule fall to the level of their complete crystallization (to a temperature of not more than 100 ^o C). The nozzles 6 are located on the side surfaces of the granulator body 1 and are directed towards the dropping drop of sulfur 4. The atomized water from the nozzles installed at an angle of 10 - 90 ^° creates a continuous water curtain that penetrates the thickness of the stream of sulfur droplets and exposes it to cooling. As a result of heat transfer, water turns into steam, the excess of which is discharged through the collector 5 and is sent for disposal. If necessary, the sulfur granules are additionally moistened with water supplied to the humidification nozzles 8, which eliminates the explosion and fire hazard during loading and unloading.

 Granular sulfur 10 is collected in the lower part of the granulator and in the form of finished products goes to the warehouse.

The amount of water supplied to the cooling zone is determined by the formula derived from the heat balance equation
Q _c = Q _c + Q _p ,
where Q _with - the amount of heat of liquid sulfur at the inlet;
Q _in - the amount of heat of water at the inlet;
Q _p - the amount of heat of steam at the outlet.

In this case, Q _c = Q _ochl1 ^s + Q _to ^s + Q _okhl2 ^s ,
where Q _cool1 ^s is the amount of heat during cooling of liquid sulfur from T _n ^s (initial temperature) to T _k ^s (crystallization temperature);
Q _to ^with - the amount of heat during crystallization of sulfur;
Q _cool2 ^s - the amount of heat during cooling of sulfur from T _to ^s to T _f ^s (final temperature),
then: Q _cool1 ^s + Q _to ^s + Q _cool2 ^s = Q _to + Q _p
Precondition: cooling is lossless and all water passes into the steam, which is removed from the cooling zone.

T _n ^s - the initial temperature of liquid sulfur - 135 ^o C;
T _cr ^{with the} temperature of crystallization of sulfur - 119 ^o C;
T _f ^s - the final temperature of sulfur in the cooling zone is 100 ^o C;
T _n ⁱⁿ - the initial temperature of the water - 35 ^o ;
T _f ^{in the} final water temperature (double point) - 100 ^o C.

Wherein
Q _{cool 1} ^s = s _s m _s (T _n ^s - T _cr ^s );
Q _c ^c = r _c m _c ;
Q _cool2 ^s = c _c m _c (T _cr ^s - T _f ^s );
Q _in = c _in m _in (T _n ⁱⁿ -T _f ⁱⁿ );
Q _p = r _p m _in ,
where с _с - weight heat capacity of sulfur - 1 kJ / kg • deg;
m _s - mass of cooled sulfur - in accordance with the capacity of the installation;
T _n ^s - the initial temperature of liquid sulfur at the inlet is 135 ^o C;
T _cr ^{with the} temperature of crystallization of sulfur - 119 ^o C;
T _f ^{with the} final temperature of sulfur - 100 ^o C;
r _s - heat of fusion of sulfur - 40 kJ / kg;
c _in - weight heat capacity of water - 4.19 kJ / kg • deg;
m _in - the mass of cooling water - is derived by the formula;
T _f ⁱⁿ - the final temperature of the water is 100 ^o C;
T _n ⁱⁿ - the initial temperature of the water is 35 ^o C;
r _p - the heat of vaporization of water - 2265 kJ / kg

Then: c _c m _c (T _n ^s -T _cr ^s ) + r _c m _c + c _c m _c (T _cr ^s - T _f ^s ) = c _in m _in (T _n ⁱⁿ -T _f ^c ) + r _n m _c . Substituting the initial data and solving the resulting equation for m _in , we get:
1 • m _c (135-119) +40 m _c +1 • m _c (119-100) = 4.19 • m _in • (35 - 100) + 2263 • m _in
m _in = m _s • 0.033,
where 0,033 is the dimensionless coefficient for the given input parameters of sulfur and water.

Thus, for cooling liquid sulfur with a mass of 1 t (1000 kg) with an initial temperature (T _n ^s ) of 135 ^° C to a granulation temperature of a final sulfur temperature (T _f ^s ) of 100 ^° C, the following amount of water is required: 1000 kg • 0.033 = 33 kg of water. Heat losses to the environment were not taken into account.

The proposed method of granulation of sulfur allows you to:
- reduce capital costs during the construction of the granulator;
- eliminate the explosion and fire hazard of the process by creating a column of water curtain (at an initial temperature of the cooling agent 2 - 65 ^o C);
- reduce energy costs that were necessary to obtain steam as a cooling agent;
- get the final product of high quality in dry form with the necessary humidity, excluding its explosion and fire hazard during transportation;
- to ensure ease of use of the granulator.

Claims (3)

1. The method of producing granular sulfur, including the supply of liquid sulfur to the granulator, cooling and granulating it in contact with a cooling agent, characterized in that as a cooling agent, water directed towards the droplet stream is sprayed with nozzles which are disposed around the droplet drop droplet sulfur to their full crystallization and create a column of water curtain, which is a cooling zone, and the steam formed during the cooling process is diverted to disposal, and the amount of water supplied to onu cooling, determined by the formula

where c _c is the weight heat capacity of sulfur;
m _c is the mass of the cooled sulfur;
T _n ^c - the initial temperature of liquid sulfur at the inlet;
T _cr ^c is the temperature of crystallization of sulfur;
T _f ^c - final sulfur temperature;
r _c is the heat of fusion of sulfur;
c _in - weight heat capacity of water;
m _in - the mass of cooling water;
T _n ⁱⁿ - the initial temperature of the water;
T _f ⁱⁿ - the final temperature of the water;
r _p - the heat of vaporization of water. 2. The method according to claim 1, characterized in that the temperature of the cooling agent is 2 - 65 ^o C. 3. The method according to claim 1, characterized in that the nozzles are directed towards the droplet stream of sulfur at an angle of 10 - 90 ^o .