JPH0433994A - Recovery of ammonium carbonate from process drain of partially coal-oxidizing oven - Google Patents

Abstract

PURPOSE:To recover ammonia components as ammonium carbonate by partially oxidizing coal, separating the first drain, heating the first drain to separate an easily volatile gas component, separating the second drain from the volatile gas component and subjecting the second drain to a stripping treatment, etc. CONSTITUTION:Coal is partially oxidized in a combustion oven to generate a gas component containing at least CO, CO2 and H2. The gas component is cooled and the produced first drain is separated. The drain is heated to strip an easily volatile gas component, which is cooled to produce the second drain. The second drain is subjected to a stripping treatment to remove H2S from the aqueous solution, thereby recovering ammonium carbonate.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a method for converting ammonia components into carbonic acid from process drain generated in the process of partially oxidizing coal to produce CO-containing synthesis gas, reducing gas, fuel gas, etc. This invention relates to a method for recovering ammonium.

[Prior Art] A partial oxidation method in which coal is combusted with oxygen in the presence of water vapor in a combustion furnace to generate a gas containing CO1CO2 and H2 is conventionally known.

The gas containing Co, CO2, and H2 generated by this partial oxidation method is used as synthesis gas, reducing gas, fuel gas, etc.

A conventional coal partial oxidation method will be explained with reference to FIG.

Coal as a raw material is put into a mill 1 together with water, and is pulverized into a slurry. This slurry is stored in a slurry tank 2 and sent to a combustion furnace (gasification furnace) 10 via a charge pump 3 and a slurry heater 4.

A combustion chamber 5 is formed in the upper part of the combustion furnace 10 . The lower part of the combustion furnace 10 is a gas cleaning chamber 6, and the combustion chamber 5
communicates with the gas cleaning chamber 6 via the throat portion 7.

Water is filled in the gas cleaning chamber 6 to a halfway height, and a cylindrical dip tube 8 and a draft tube 9 are coaxially provided so that their lower ends are submerged in the water.

Although not shown, a quench ring is provided for supplying water to the upper inner peripheral surface of the dip tube 8 and forming a water belly on the inner peripheral surface.

The gas taken out from the gas outlet 11 provided in the combustion furnace 10 is sent to the CO conversion furnace 14 via the scrubber 12 and the heat exchanger 13, where CO2 is converted (reduced) to CO. The gas taken out from the heat exchanger 13
The waste heat is then sent to the waste heat boiler 15, where it is cooled down. Boiler 1
The drain generated in step 5 is separated by a separator 16, and is supplied to the scrubber 12 via a pump 16a.

The gas component from the separator 16 is cooled by a condenser 17, and the resulting drain (primary drain) is separated by a separator 18. Gas components from separator 18 are taken out as process gas. After the primary drain is heated in a heat exchanger 19, it is sent to a heavy-duty stripper 20, heated by a steam heater 21, and stripped.

The gas components generated by the stripper 20 are cooled by a condenser 22, and the resulting drain (secondary drain) is separated from H2S and CO2 by a separator 23 and returned to the mill 1. The residue of the heavy carbon cheap stripper 20 is transferred to the heat exchanger 19,
It is supplied to the scrubber 12 via a cooler 24 and a pump 25.

[Problems to be Solved by the Invention] In the above-mentioned conventional method for partial oxidation of coal, the secondary drain after heavy coal stripping is returned to the mill 1. It contains a considerable amount of H2S and NH3, and there was a problem that H2S and NH3 leaked into the atmosphere around Mill 1. Further, when the secondary drain is returned to the mill 1, there has been a problem that the secondary drain affects the slurry properties of the coal, making it difficult to increase the slurry concentration.

[Means for Solving Problem 8] The method for recovering ammonium carbonate from the process drain of a coal partial oxidation furnace of the present invention involves partially oxidizing coal in a combustion furnace to produce a gas containing at least Co, CO2 and H2. a step of cooling this gas and separating the resulting primary condensate; a step of heating this primary condensate to strip easily vaporizable gas components; a step of cooling the stripped gas components and separating the resulting primary condensate; The process of separating the secondary drain, and stripping this secondary drain with CO2 gas to remove H2
This method includes the steps of expelling S from the aqueous solution and separating and recovering the remaining ammonium carbonate.

[Function] According to the present invention, ammonium carbonate can be recovered from the secondary drain.

[Example] FIG. 141 is a system diagram explaining the example method.

In this embodiment, the secondary drain from the separator 23 is introduced into the H2S stripper 26, which consists of a tray column, a packed column, etc., and is stripped by CO2 blown in from the blowing line 27. Note that in this embodiment, the steam heater 2
8 heats the drain to promote stripping.

The gas generated by the stripping is cooled in the condenser 29 and then introduced into the separator 3o. The drain separated by the separator 30 is returned to the stripper 26 as reflux, and H2S and CO2 are taken out and sent to the sulfur recovery process.

The drain (tertiary drain) that is the stripping residue of the stripper 26 is almost pure ammonium carbonate water, is cooled in a condenser 31, purified in a final purifier 32, and then stored in a tank 33.

The other steps are the same as those shown in FIG.

Next, specific examples will be described.

Coal was partially oxidized according to the steps shown in FIG. 1 under the following conditions, and ammonium carbonate was recovered.

Coal feed amount 62500kg
/h water feed amount 38300
kg/h oxygen feed amount 39000
Amount of NHs extracted from Nd/h separator 14
3J/h Primary H2S amount taken out from separator 28k
g/h Primary C02 amount taken out from separator 509 kg
/h Secondary H2S amount taken out from separator 28kg/
Secondary CO2 amount taken out from h separator 218kg/h
The results of elemental analysis of coal are as follows.

Cfi7.9w t% H5,3w t% N 1. Ow t% S 4.9w t% Ash 14.8w t% Others 6.1w t% The above describes the recovery of ammonium carbonate in process drain produced by partial oxidation of coal, but Similar results are obtained for partial oxidation of .

[Effects] As described above, according to the method of the present invention, ammonia produced as a by-product in the coal partial oxidation process can be recovered as ammonium carbonate. Furthermore, since no condensate is returned to the mill, the atmospheric environment around the mill is improved and the slurry properties in the mill are improved.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the method of the embodiment, and FIG. 1iS2 is a system diagram showing the conventional method. 10... Combustion furnace (gasifier), 20... Heavy coal cheap stripper, 26... H2S stripper.

Claims (1)

[Claims] (1) Partially oxidize coal in a combustion furnace to at least
a step of generating a gas containing O, CO_2 and H_2; a step of cooling this gas and separating the generated primary drain; a step of heating this primary drain to strip easily vaporizable gas components; A process of cooling the generated gas components and separating the generated secondary drain, and stripping the secondary drain with CO_2 gas to remove H
A method for recovering ammonium carbonate from a process drain of a coal partial oxidation furnace, comprising the steps of expelling _2S from an aqueous solution and separating and recovering ammonium carbonate.