Alkalifying and diluting device for preventing sample blasting boiling of kjeldahl nitrogen determination instrument and method

Abstract

The invention discloses an alkalifying and diluting device for preventing sample blasting boiling of a kjeldahl nitrogen determination instrument and a method. The device comprises a digestion tube, a distilling flask communicated with the interior of the digestion tube is installed at an opening formed in the top of the digestion tube, the top of the distilling flask is connected with a condenser in series and then connected with a titration cylinder, the distilling flask is further provided with an alkaline liquid inlet and a water inlet which are connected with an alkaline pump and a water pump respectively, and the water pump and the alkaline pump are controlled by a control device. According to the device, the blasting boiling and alkaline pump crystallizing problems are solved, and the determination precision of the kjeldahl nitrogen determination instrument is improved.

Description

technical field [0001] The invention discloses an alkali adding and diluting device and method for preventing samples of a Kjeldahl azotometer from bumping. Background technique [0002] During the working process of the Kjeldahl nitrogen analyzer, it is necessary to dilute the digestive juice with water and add alkali to make it alkaline; generally, the automatic Kjeldahl nitrogen analyzer and the fully automatic Kjeldahl nitrogen analyzer are all disposable after setting the amount of alkali and dilution. Add the set alkali addition amount and dilution amount into the digestive tube; there is a serious problem in this, because the Kjeldahl nitrogen analyzer needs to use concentrated sulfuric acid to decompose and digest the sample during the sample digestion process, and the test uses are all analytically pure grades above 99.999% Concentrated sulfuric acid is used as a strong oxidant, if water or a strong base is added to the concentrated sulfuric acid, the strong acid wi...

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Problems solved by technology

[0002] During the working process of the Kjeldahl nitrogen analyzer, it is necessary to dilute the digestive juice with water and add alkali to make it alkaline; generally, the automatic Kjeldahl nitrogen analyzer and the fully automatic Kjeldahl nitrogen analyzer are all disposable after setting the amount of alkali and dilution. Add the set alkali addition amount and dilution amount into the digestive tube; there is a serious problem in this, because the Kjeldahl nitrogen analyzer needs to use concentrated sulfuric acid to decompose and digest the sample during the sample digestion process, and the test uses are all analytically pure grades above 99.999% Concentrated sulfuric acid is used as a strong oxidant, if water or a strong base is added to the concentrated sulfuric acid, the strong acid will quickly release a large amount of heat energy when it encounters water or a strong base, and the liquid in the digestive tube will boil rapidly; due to the Kjeldahl nitrogen determination Due to the limitation of the height of the instrument, the released heat energy will break through the limitation of the distillation bottle and enter the titration cylinder, resulting in huge errors in the test results.

[0003] In addition, the Kjeldahl nitrogen analyzer generally uses a self-priming pump to pump lye into the machine to automatically complete the liquid addition operation. Due to constraints such as cost and volume, self-priming pumps generally choose diaphragm pumps, flow pumps and other pumps. These pumps are generally due to the crystallization of sodium hydroxide, and the crystallization blocks the pump diaphragm, one-way valve and other components, resulting in the alkali pump not being able to inhale the lye normally. Once the pump is clogged by crystallization, although there is no damage to any mechanical parts, it is only necessary to simply clean the casing, but it still requires on-site service by the manufacturer's service personnel, which seriously delays the customer's test and increases the cost burden of the manufacturer. , the problem of alkali pump crystallization has always plagued the development of Kjeldahl nitrogen analyzers. Regardless of the original ideas of domestic manufacturers and foreign manufacturers, they mainly focus on the selection and improvement of pumps, and many of them customize some chambers with larger chambers or diaphragms. The solution to the sealing problem caused by not being easily blocked by particles cannot fundamentally solve this problem

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