DE2258256C3 - Process for the preparation of a solid fire extinguishing composition - Google Patents

Description

Lichen size distribution can easily by appropriate way mixtures of the product and from ! ^ position of the working conditions of the spray dry fire extinguishing agents, which are opposite to the Reaklings device can be controlled. tion participants are inert, such. B. Potassium Chloride

In the spray drying process it is advisable to produce dicyandiamide or potassium sulphate, or avenge active substances for evaporation and heating as solid substances, for example sand, fluorspar, barium-dried particles, by producing sulphate, gypsum or aluminum oxide, iiä hot gas introducing iu the Spntzkammer, ie in this way, very intimate mixtures are sustainer gas, which is heated to a temperature which for th. these are especially useful when the mixture GFC evaporation of the solvent is required having a higher bulk density than the original B has been found that suitable temperatures, ie, io Liehe product that the added solid has a, for example, 200 to 1000 C, preferably 300 to particle density of more than 1, "g / cm ³ the #X) ° C, for the inlet gas In order to have sufficient aqueous liquid, one or more liquid heats can be transferred to the reactants. that can be mixed (this creates a

ί I The flow rate of the material through solution) or which are immiscible (the spray chamber is preferably created in such a way that an emulsion is made, 15 emulsion), where the water is the main component that the temperature of the gas at the outlet forms 40 to nente For example, aqueous alcohol 300 ⁰ C, for example 100 to 160 ⁰ C, in particular 125 mixtures can be used. The lower alcohols up to 15O ⁰ C is. These values are close to the temperatures at which the reactants are preferred for the purpose of easy evaporation.

Desirably heated to give good yields ao The reaction used for the process Achieve product. participants are urea and a carbonic acid salt

The hot gas can consist of one or more gases as defined above for sodium or potassium, which are found in the air. Air itself is Potassium bicarbonate is preferred as its use is the most convenient gas, although any stable gas containing this salt will result in a product that can be superiorly converted. It is an advantage if a> 5 fire-extinguishing properties. The proportions higher concentration, for example a concentration of the reaction part can essentially tration of 1 to 10 percent by volume, of carbon dioxide equimolar amounts of bicarbonate and urea is present in the evaporation atmosphere, because this creates a smaller excess of bicarbonate, higher yields of the desired product, for example up to 1.25: 1, is preferred. When empirical formula MCgN ₄ H ₃ O ₃ can be obtained. If, on the other hand, carbonates are used, then a

The higher carbon dioxide concentration can preferably be achieved in excess urea, for example in a urine-expedient manner by having a material-carbonate molar ratio of 1.5 to 3.5: 1. as a hot atmosphere in which the solution or the total weight of the aqueous liquid

Sludge of the reactant injected added reactant is preferably so is used, air, which is replaced by a pure gas or 35 large, that just barely has a usable mobility has been heated by an oil flame. This is achieved by the resulting slurry or solution Driving is of course preferred if one is. Appropriate amounts are from 10 to 80 Genoch higher concentration of carbon dioxide required percent by weight of reaction participants, based on the is appropriate, for example if a hydroxide weighs the solution or slurry. So are is used in order to achieve the carbonic acid salt reaction time- 40, for example, preferred amounts of 10 g of urea and to produce takers in situ. 20 g of potassium bicarbonate in 100 g of water and also

It is also an advantage if some water vapor, higher concentrations, such as. B. 50 g urea and preferably 10 to 30 percent by volume, in the ratio 100 g potassium bicarbonate to 100 g water. The steaming atmosphere is present. Although some aqueous mixture of the reactants is prepared before this water by the evaporation of an aqueous 45 preferably at room temperature, but the liquid composition is formed, extra mixture can also be added before the evaporation heated water in the form of steam if necessary to maximize the reactants on _{who (} j _en . to dissolve, with the use of bicarbonates

In one embodiment of the invention, care should be taken that excessive heating Procedure, the two reactants 50 are avoided.

(preferably with stirring) with water or a convenient and preferred procedure

mixed aqueous liquid, so that essentially for the implementation of the method according to the invention The total amount of at least one of the reactants, if spray drying is carried out, is m participant dissolves. It can be shown schematically for the following of the drawing, which the on-spraying be advantageous if both reac- 55 order of the various components of the used dissolve tion participants, but provided the device represents.

Particle size of the undissolved solid particles is solutions or slurries ^ of the individual

not larger than the droplet size (which, for example, reactants are in each of the wise 10 to 500 μ), a slurry tank A and B. You can mix and mung the one reactant in solution and 60 to an atomizer C. in which the other in suspension contains the spray drying, is to be carried out for the active chamber D. Hot air or carrying out the procedure alone are also suitable. Its hot gas mixture, which comes from the heater ti The aqueous liquid is preferably water, is only inserted at / in the spray dryer, but it can also be an aqueous solution or suspension Gas flow to outlet E and through the cyclones such as B. Solids, which are advantageously passed into separators F ₁ and F _t . The solids will be incorporated into the final product, e.g. B. finely separated from the gases and vapors, whereby the distributed silicon dioxide, as a flow aid, is collected on these solids in the funnel G , while

the gases and vapors that escape at K will either be. The products of the inventive

driven to the atmosphere or to the heater H in each case contain a predominant one

be returned. Amount of compound MC ₂ N ₂ H ₃ O ₃ , where M is Na

Alternatively, a mixture of the reaction or K stands, which is represented by a strong flamua

participants in the tank B , namely can demonstrate the extinguishing effect. The inventive

neither in the form of a dry powder nor as products made in accordance with these are therefore vigorous

Mix with a liquid. The reactive fire extinguishing agent.

participant mixture is in a water stream from the the above described as desirable

Tank A calibrated to find a suitable solution or actions can also be carried out

To produce slurry, which in the spray dryer io to the storage qualities and the later flow-

is introduced. Powder characteristics after storage

The solid product that will improve after evaporation.

Certain Embodiments of the Invention, Exemplary The invention is illustrated by the following examples

wise when using a spray drying process explained in more detail,

rens, is collected, provided the concentration is 15

of the urea is below 5 percent by weight and the B e i s ρ i e 1 1 Particle size is suitable without further treatment

can be used as dry fire extinguishing powder. At a solution and a slurry of caanders Embodiments of the invention lium bicarbonate and urea in water were prepared a treatment of the product is provided, with the two reactants in for example, desires to either grind the 1.15: 1 ratio. The solution Product up to a mean particle size between contained a concentration of 18.1 percent by weight 10 and 50 μ, preferably 20 to 40 μ, or the ex-bicarbonate and a concentration of 9.5 weight traction of the free urea using one percent urea while the slurry solvent washing process. In an alternative 35 32.0 weight percent bicarbonate and 16.8 weight percent Solvent washing processes cannot contain percent urea

Set free urea and by-products such as the solution and the slurry have now been released. B. carbonates and cyanates, thereby largely Weil separately spray-dried with a spray being removed from the product by bringing it into contact with heated air used with a diameter of 1.8 m, preferably air 30. This spray dryer had an electrical earth of at least 5% carbon dioxide and at least 10% heater and a disk atomizer. Contains water vapor The cleaning process can be carried out (either intermittently or continuously) Table I indicated inlet and and the solid product can be achieved through the air or other outlet temperatures. The residence time to a temperature in the range from 30 to in the spray dryer was approximately 18 seconds. 250 ^° C., preferably in the range from 80 to 160 ^° C., the product was analyzed. It had the composition given in Table I below, in particular in the range from 90 to 140 ^{° C. when heated.}

Table I.

Solution slurry

Inlet ^{temperature, 0} C 310 310 325 325 320 230

Exit temperature, ⁰ C 140 145 140 145 135 140

Analysis of the product

in percent by weight:

KC ₄ N ₄ H ₈ O ₈ 70 77 70 79 73 77

KCNO - 0.5 - 1.2 0.6

Urea 4.0 1.6 4.7 1.4 5.0

was carried out, mixed with the combustion products of the Example 2 flame and contained a higher proportion

of carbon dioxide and water vapor than normal air

Solutions of potassium bicarbonate and urea 60 The yield of effective fire extinguishing material with four different concentrations and ratios- CKC ₄ N ₄ H ₃ O ₃ ) and the amount of potassium cyanate hoist, which were labeled A, B, C and D, by-products and the free Urea was prepared and assayed in a syringe dryer. The values are based on a diameter of 76 cm, the following tables being given. The teflchen size residence time in the spray dryer is 7 seconds. The distribution of the product was very narrow. 88% of the particles of hot air that went into the dryer were 8 to 12 µm in diameter. Because the largest particles formed when heated through direct contact with a gas flame had a diameter of 15 μ.

310 310 325 140 145 140 70 77 70 - 0.5 4.0 1.6 4.7

305 310 360 255 300 D. 300 350 350 375 150 150 150 130 130 1.0 130 130 140 140 65.8 57.5 63.3 60.5 76.0 18.0 62.5 71.5 73.5 75.0 0.1 0.1 0.1 - 0.1 10.0 0.1 0.1 0.2 0.2 3.6 4.3 4.3 9.5 7.8 8.5 6.2 4.5 5.3 ure dei ' Solutions in water: A. B. C. 1.10 1.15 1.20 18.10 18.10 18.20 9.7 9.5 9.1

7 8

Table II

Composition of the solution *)

B CAADBB

Inlet temperature, ⁰ C outlet temperature, ⁰ C

Analysis of the product
in percent by weight:

KQN ₂ H ₃ Os,

KCNO

urea

I bicarbonate / urea molar ratio

I potassium bicarbonate, weight percent

ι urea, percent by weight

B e i s η i e 1 3 fluidized bed apparatus were brought into contact. the

j P various concentrations of carbon dioxide and products were produced according to the invention, steam and also temperature and residence time, and analyzed and typically contained: as are given in Table III. From the chemical analysis of the products obtained it can be seen that 55 to 70% KC ₂ N ₂ H ₃ O ₃ , the concentration of KC ₂ H ₂ H ₃ O ₃ in all cases (with 2 to 10% free urea, with the exception of one Case) in the fluidized bed treatment, 2 to 5% potassium carbonate. over 70% and usually even over 80% is increased t 3o. The amount of free urea and Ka-The free urea and potassium carbonate are left to acceptable levels in the finished product, which is to be reduced as a fire extinguishing agent, and furthermore no potassium cyanate compound is to be used. Provided that sufficient carbon dioxide has been reduced to an acceptable level and water is present, it forms with the impurities that the product reacts on contact with air and causes a decomposition of the carbon dioxide and steam all in one active compound KC ₂ N ₂ H ₃ O ₃ to prevent.

Table III

Sample no.

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Temperature of the solids:

Heated 130 as a single batch rapidly at entry from room temperature in 2 minutes

_än At exit 130 130

Ii; Composition of the air:

§H volume percentage COg 11 10

05 138 138 130 134 110 120 115 95 95 120 134 0 10 10 0 5 20th 5 10 5 5 0 10 30th 20th 0 20th 5 45 30th 25th 0 15th 0 20th 40 90 90 90 90 27 30th 40 40 60 30th 80

Percentage by volume steam 34 35 Dwell time (minutes) 30 50

composition
of the product:

Percentage by weight 77 75 78 80 84 84 85 58 85 83 82 84 89 -

KQN ₄ H ₈ O ₄

Percentage by weight 0.3 0 0 0 0.1 0 0 0.3 0.1 0.2 3.9 1.1 0.1 0 ,:

urea

Weight percent KCN 0000000000 1.2 000 weight percent K ₈ CO ₃ - - 5.2 - - - - 0.8 0.4 0 _r 4 0 _? 5 0.4 3.5 -

Remarks;

Sample 14 was made in a continuous process and as a result the solids were prior to entry the fluidized bed is heated

(-) means no analysis was performed.

(0) means "nothing found"; d. L · that it is less than 0.01%

Sample 8 initially contained ποτ 52% RCAH ₄ Q ₁ . . «-» ««.

out ö20 / ä

Example 4

A solution or slurry was made up of urea and either potassium carbonate or potassium bicarbonate prepared in water and in a hot gas stream in that used in Example 2 Device injected. The total weight of the reactants in the solution or slurry was equal to the weight of the water. The proportions of the reactants who used Temperatures and the analyzes of the products are shown in Table IV.

In three cases (samples 4, 5 and 6) it should be noted that other salts in addition to the reactants in

the slurry which had been spray dried were incorporated. The other salts appeared chemically unchanged in the finished product. The free urea and potassium carbonate were present in some product samples at a higher concentration than is desired for a fire extinguishing powder. However, the active compound KC ₂ N ₂ H ₃ Oj is present in a good yield. The impurities could if desired by cleaning

ίο be removed in a fluidized bed, as in the example 5 is described. It is usually necessary to reduce the product to an acceptable particle size of, for example to grind an average of 20 to 40 μ in order to be used as fire extinguishing powder.

Table IV

Sample no.

Molar ratio of the reaction part
recipient:
Potassium carbonate to urea
Urea to potassium carbonate 1.15: 1 2: 1 3: 1 1: 1.1 1: 1.1 1: 1.1 Hot gas stream:
Water vapor, volume percentage
Inlet gas temperature, ⁰ C 5
380 5
380 5
380 5
380 5
380 0
320 Exit gas temperature, ⁰ C 140 140 140 140 140 140 Addition to the solution - slurry
before spray drying Nothing Nothing Nothing BaSO ₄ KCl K ₂ SO ₄ Analysis of the product:
Weight percent KC ₂ N ₂ H ₃ O ₃
Free urea
KCN
K ₂ CO, 70
3.0
0
2.4 65
3.2
0.1
13.3 69
10.3
0.1
5.0 68
4.6
0 66
3.0
0 52
15th
0 additive BaSO ₄
20th KCl
20th K ₂ SO ₄
20th

(0) means nothing found, that is, less than 0.01%.
(-) means no analysis was performed.

Example 5

A solid mixture containing 1.2 moles of potassium bicarbonate and 1 mole of urea was stirred with methanol to make a slurry containing 20 weight percent total solids. It was observed that the urea dissolved slightly, but that the bicarbonate remained largely undissolved in the methanol. The slurry was atomized in a spray dryer, was passed through the air at a temperature of 280 ⁰ C at a rate sufficient that an exit temperature of 80 ° C was obtained. The product obtained after evaporation of the methanol was heated to a temperature of 130 ° C. for 20 minutes in air containing 10% by volume of water vapor.

The finished product was found to contain only 2% free urea and approximately 50% of the active fire extinguishing agent KQN ₃₁ H ₃ O ₃ , the remainder being mainly potassium bicarbonate.

1 sheet of drawings

■ f. 'S

Claims (2)

for the procedure to be effective. However, claims: a greater solution effect is preferred. For example, a solution that is sufficient, a Prepare 1. A process for preparing a solid fire solution containing at least 10 weight extinguishing composition which comprises a compound containing 5 percent of a reactant The Verder empirical formula MC ₄ N ₈ H ₃ O ₃ (wherein M are performed for drive can thus wirtschafthcher, potassium The greater the dissolving effect, since the smaller the volume of liquid required to bring the reaction of potassium or sodium into contact in the presence of a participant, the greater the dissolving effect, since the smaller the volume of urea with a carbonic acid salt marked ίο can be steamed. net that the reaction takes place in a solution or the liquid can be aqueous or not Slurry is carried out in webhcr of the aqueous liquid, and it can also be AnSeU of the reactants 10 to 80 Ge around a single liquid or around one percent by weight questioned, whereby the solution or composition containing one or more liquids, act as a slurry by atomizing or spraying. Examples of liquids are alcohols procedure introduced into a reaction chamber (preferably methanol or ethanol), ether alcohol at which a temperature prevails that the (e.g. Cellusolve), hydrocarbons (pre-solvent preferably evaporates aromatic hydrocarbons), nitriles 2. The method according to claim 1, characterized (preferably acetonitrile), amides (preferably Dizeichnet that as a solvent water or ao methylformamide), sulfoxides and sulfones. This preliminary Solvent is used. Examples are given only because of the low Boiling points selected For better results, the liquid should be one that has a considerable proportion of one or both reaction The participant can dissolve, but it is not necessary that a complete resolution of even just one of the reac The DT-OS 16 21 713 describes a procedure for participant participation. The used solution-preparation of a solid fire-extinguishing composition, medium can only be effective as a solvent at an elevated temperature, and for example the MC ₁ NjH ₃ Oa (where M for potassium or sodium 30 urea melted at the reaction temperature » teht) contains, by reacting urea with and with a solvent, in which crystalline a carbonic acid salt of potassium or sodium. Urea does not dissolve easily, be miscible. the The solids reaction that occurs is a preferred liquid is an aqueous slow co-operation Reaction; the procedure described there. In particular, water itself is preferred, takes several hours to complete. A 35 The fluid can be improved in various ways This procedure can be found in the Addresses to Collaborate Respondents-DT-OS 19 06 767. In the latter case, the menzubringen. For example, a solution or Reaction in the presence of steam from a slurry of a reactant to led, in certain cases the reaction mixture also added to another reaction participant 1 to 10 percent by weight of water is added, or the liquid can be mixed with a mixture of , can be placed before the mixture is stirred on the solid reactants to give a Reaction temperature is brought. This will create dissolution or slurry. at a substantial abbreviation of the reaction is achieved a preferred method is a reaction part- It has been shown, however, that this method, too, is completely resolved, preferably preferably not the desired high reaction rate- 45 the urea, which in aqueous media extremely and that it is also soluble in terms of the. The process control is still in need of improvement. The evaporation stage is preferably in a The present invention was based on the object of ^{running temperatures above 100 °} C. in order to create such an improved process for the process. to be carried out quickly. However, you can also use it The object is achieved according to the invention by 50 compositions at lower evaporation in a process of the type specified, which temperatures are produced, for example, characterized in that the conversion in temperatures in the range of 40 to 100 ° C, with a solution or slurry also carried out reduced Pressures to aid in whichever portion of the reactant vaporization can be used.
10 to 80 percent by weight, with the solution being 55. In the process according to the invention, the solution or slurry is introduced into a reaction chamber by atomization or spraying by atomization or or slurry of liquids and reacting spraying, in which there is a temperature that the Lö- divided into fine droplets. The spray can then evaporate on solvent. directed or even better in a heated surface The carbonic acid salt can be injected a carbonate, a bi-60 hot atmosphere. At the last carbonate, a sesquicarbonate or a mixture of it ren process, which are called "spray drying", or it can be in situ from the union of a net, the droplets are during the ver-hydroxide kept at a distance from sodium or potassium with a carbon vapor stage, the solid dioxide can be produced. Product is formed in a particulate form. That's how it is The extent of the solvent action of reaction spray drying is a particularly preferred measure mediums can be pretty small. For example, to carry out the method according to the invention, a solvent action that gives a solution, an added benefit of the spray drying method only 1 percent by weight of a reactant is that the particle size and the