DD298454A7 - METHOD FOR THE CORROSION INHIBITION OF NITROGEN FLUID SUBSTANCES - Google Patents

Abstract

The invention relates to a process for the corrosion inhibition of nitrogen liquid fertilizers, in particular ammonium nitrate-urea solutions. The aim and object of the invention is to provide a reliable corrosion protection both Transportvorgaengen, z. B. in pipelines as well as in storage facilities z. B. in tanks using low-cost carbon steel. According to the invention, the nitrogen fluid fertilizer compositions are comprised of 40 to 90% Alkylphosphorsaeuremono / diester, 3 to 20% Alkylammoniumverbindungen alkoxylated Alkylphosphorsaeuremono / diester, 5 to 40% AlkylbenzensulfonsÄure and 3 to 20% of polyhydric aliphatic alcohols or polyalcohols or derivatives thereof, in amounts of 50 to 600 mg / l added.

Description

Il

R ₁ O- (CH ₂ -CHR ₂ -O) _n -P

0 O "

R ₁ O- (CH ₂ -CHR ₂ -O) _n "

R ₁ O- (CH ₂ -CHR ₂ -O) _n

P-O

in the

R ₁ = alkyl radicals having 10 to 20 carbon atoms or alkylphenol radicals having 8 to 15 carbon atoms in the alkyl chain

Π2 ⁼ HjCH ₃ , C2H5

R ₃ = alkyl radicals having 1 to 5 and 16 to 18 C atoms, wherein the molar ratio of the short-chain to

the long-chain alkyl radicals 1: 1 to 3: 1 is η = number of moles of the attached alkylene oxides of 3 to 20 and the molar

Phosphoric acid mono / diester ratio is 1: 3 to 3: 1, 5 to 40% of alkylbenzene sulfonic acid with Ci ₀ - to C ₁₃ -alkyl radicals 3 to 20% of polyhydric aliphatic alcohols and / or polyalcohols and / or their

Derivatives is added.

2. Ancestors according to item 1, characterized in that the substance combination in amounts of 50 to 600m, g / l is used.

Field of application of the invention

The invention relates to a process for the corrosion inhibition of nitrogen liquid fertilizers, in particular ammonium nitrate-urea solutions.

Characteristic of the known technical solutions

Aqueous nitrogen liquid fertilizers preferably consist of the main components ammonium nitrate and / or urea and / or ammonia and water. They have a high corrosivity towards materials of low chemical resistance, which in addition to a strong material attack in a strong discoloration of Düngemitteiiösung, especially when using carbon steel noticeable. In addition to a reduction in the quality of the fertilizer solution due to turbidity and discoloration, this also means a deterioration of the application properties due to the formation of precipitates and flocculations of the corrosion products as sludge. Due to the enormous corrosiveness, either chemically resistant materials are used for ammonium nitrate-urea solutions or corrosion inhibitors are added when using materials with low chemical resistance. Known corrosion inhibitors are dicyandiamide, chromates and dichromates, free ammonia, borates, arsenic compounds, copper compounds, carbonates, alkali metal hydroxides, ammonium thiocyanate, phosphates, thiosulfates, metal aminocomplexes, glyconic acid, lignosulfonates. These corrosion inhibitors cause a more or less good material protection with respect to a superficial material removal. For practical use, they are either relatively expensive, z.T. toxic, acting only in relatively high concentrations or prone to foaming the fertilizer solution. The known inhibitors are further distinguished by the fact that they have a preferred anticorrosion effect in a quiescent or agitated medium. Depending on the prevailing technology in the transhipment and transport process to the customer (pipelines or tank storage and tank car transport), such a corrosion inhibition may be sufficient, but in a technology both larger transport operations, eg through pipelines, and long storage, e.g. B. in stacking tanks, necessary, is the

Corrosion protection inadequate, since the corrosion protection is carried out in stationary or moving medium according to different mechanisms and is not provided by the previously known inhibitors simultaneously. The result is a corrosive attack either in the pipelines or the storage tanks or transport containers with the described negative Qualitätsboelnflussungen the fertilizer solution.

Object of the invention

The aim of the invention is to propose a process for the corrosion inhibition of nitrogen liquid fertilizers, which ensures reliable corrosion protection during transport and storage operations of nitrogen liquid fertilizers.

Explanation of the essence of the invention

The invention has for its object to use a combination of substances, which shows a high inhibiting effect both at rest and in the moving medium at low user concentration, is well dosed and the quality of the nitrogen liquid fertilizer is not adversely affected.

According to the invention the object is achieved in that the nitrogen liquid fertilizers a combination of substances consisting of 40 to 90%, preferably 60 to 80%, Alkylphosphorsäuremono / diester, with a C ₈ - to C, ₀ -alkyl radical which may be straight-chain or branched, wherein the molar ratio Alkylphosphorsäuremono-: Alkylphosphorsäurediester = 1: 1 to

10: 1, preferably 1.5: 1 to 4: 1, is 3 to 20%, preferably 5 to 10%. a mixture of alkylammonium compounds alkoxylated

Aikylphosphorsa'uremono / diester of the general formula

R ₁ O -

- CHR ₂ -

+ NH-

- ^R

R ₁ O * (CH ₂ - CHR ₂ - O) _n R.

- (CH ₂ - CHR ₂ -

- O

^NH 3 - ^R 3

in the

Ri = alkyl radicals having 10 to 20 carbon atoms or alkylphenol radicals having 8 to 15 carbon atoms in the alkyl chain

Π2 - H, CH3, C2H5

R ₃ = alkyl radicals having 1 to 5 and 1 β to 18 C atoms, wherein the molar ratio of the short-chain to the

langkettigenAlkylresten'i: 1 to 3: 1 is η = number of moles of the deposited alkylene oxides from 3 to 20

wherein the molar phosphoric acid mono / diester ratio is 1: 3 to 3: 1

5 to 40%, preferably 10 to 20% of alkylbenzenesulfonic acid (C ₁₀ - to C, ₃ -alkyl radical)

From 3 to 20%, preferably from S to 10%, of polyhydric aliphatic alcohols and / or polyalcohols, such as propanediols, butanediols, hexanediols and triols, trishydroxymethylpropane, polyalkylene glycols and / or their derivatives, such as alkylpolyalkylene glycols and the like

 is added.

The combination of substances described causes in the concentration range of 50 to 600 mg / l, preferably 80 to 300 mg / l, nitrogen liquid fertilizers very good corrosion protection both during transport operations, eg. As in pipelines as well as warehouses, z. In tanks. It can be metered with commercial metering devices in a simple manner in the fertilizer solution. There is no negative impact on the quality of the fertilizer solution

 The invention will be explained in more detail in the following embodiment.

embodiment

Into an ammonium nitrate-urea liquid fertilizer of the composition 30% urea, 40% ammonium nitrate, 30% water and traces of free ammonia were subjected to alternation of the corresponding additives alternately St 38 carbon steel sheets St38 alternately a rest or movement phase (rotary motion with 1 m / s) to simulate the practical conditions of transport or storage. Overall, the sample plates were in motion for 48 hours at room temperature and at rest for 144 hours.

In order to assess the effectiveness of the additives, the weight change of the sample was used to determine the linear removal VI. The protective value was after

S = 100x

Vl without additive - V _L with additive Vl without additive

calculated.

The assessment of the Ί rübungs- and Discoloration as an indication of the quality of the fertilizer solution was determined by measuring the light transmittance of the ammonium nitrate-urea liquid fertilizer sample at 400 μηι in 5-cm cuvettes.

additive concentration material d. additive in mg / l without addition _ A 1000 » B 750 · C 200 D 200 e 200 F 200

V _L S light transmission in mm / s in% in%

2.35 0 2

0.23 90 62

1.08 54 53

0.25 89 78

0.96 59 55

0.28 88 74

0.04 98 92

* Concentration according to the application rate applied in practice

Experiments A and B serve as comparative experiments and characterize the known prior art. Experiments C bis E serve to demonstrate the combination effect of the solution according to the invention. A Diammone phosphate B lignosulfonate C 2-Ethylhexylphosphorsäuremono / diester mixture having a phosphoric acid mono / diester ratio of 5: 3 D butyl-ZOctadecylammoniumalkylpolyglykoletherphosphorsäuremono / diester

molar butyl / octadecyl ammonium ratio 2: 1

- alkyl chain CiobisCu

- degree of ethoxylation π = 9

Phosphoric acid mono / diester ratio 2: 1 E dodecylbenzene sulphonic acid

F substance combination consisting of 75% by weight of additive C, 6.5% by weight of additive D, 12% by weight of dodecylbenzenesulphonic acid and 6.5% by weight of butanediol (1.3)

Claims (1)

Invention claim: 1. A process for the corrosion inhibition of nitrogen liquid fertilizers, in particular ammonium nitrate-urea solutions, characterized in that the SticKstoffflüssipdüngemittel a combination of substances consisting of From 40 to 90% of monoalkylphosphonic acid monoesters having a C ₆ to C ₁₀ alkyl radical which may be straight or branched, the molar ratio being Alkyl phosphoric acid mono-: Alkylphosphorsäurediester 1: 1 to 10: 1 is 3 to 20% of a mixture of alkyl ammonium compounds alkoxylated Alkylphosohorsäuremono / diester of the general formula