Method for producing cellulose carbamate

Patent metadata

Field	Value
Publication number	US-11584804-B2
Application number	US-201917057938-A
Country	US
Kind code	B2
Filing date	May 21, 2019
Priority date	May 22, 2018
Publication date	Feb 21, 2023
Grant date	Feb 21, 2023

Abstract

A method for controlling discharges of nitrogen compounds in the production of cellulose carbamate (CCA). Microcrystalline cellulose is produced from chemical pulp produced at a pulp mill, such that the chemical pulp is subjected to acid hydrolysis at an elevated temperature to form microcrystalline cellulose (MCC) and hydrolysate, and the MCC is reacted with urea to produce cellulose carbamate whereby ammonia is released. The microcrystalline cellulose production and the cellulose carbamate production are integrated into the pulp mill having a flue gas system such that carbon dioxide from the flue gases is reacted with released ammonia to produce urea, which is used in the carbamate production.

First claim

The invention claimed is:

1. A method for controlling discharges of nitrogen compounds while producing cellulose carbamate, the method comprising:
microcrystalline cellulose is produced from chemical pulp produced at a pulp mill as the chemical pulp is subjected to acid hydrolysis to form the microcrystalline cellulose and hydrolysate, and
reacting the microcrystalline cellulose with urea to produce cellulose carbamate during which ammonia is released,
wherein the microcrystalline cellulose production and the cellulose carbamate production are integrated to the pulp mill having a flue gas system that handles flue gases, wherein carbon dioxide from flue gases is reacted with the released ammonia to produce the urea, which is used in the carbamate production.

2. The method according to claim 1 , wherein the flue gas system is attached to a lime kiln, and the carbon dioxide is obtained from flue gases produced in the lime kiln.

3. The method according to claim 1 , wherein the released ammonia is used to neutralize hydrolysate and/or acidic wastewater from the production of the microcrystalline cellulose.

4. The method according to claim 1 , further comprising feeding at least a portion of nitrogen containing wastewater from the production of the cellulose carbamate to an evaporation plant which concentrates the nitrogen containing wastewater to produce dry nitrogen fertilizers.

5. The method according to claim 1 , further comprising conveying nitrogen containing wastewater from the production of the cellulose carbamate to a wastewater treatment plant of the pulp mill to be used as a nutrient.

6. The method according to claim 1 , wherein hydrolysate and/or acidic wastewater from the microcrystalline cellulose production is used to neutralize wastewater from the cellulose carbamate production.

7. The method according to claim 1 , wherein the chemical pulp is a bleached fibrous cellulosic wood pulp.

8. The method according to claim 1 , wherein the step of reacting the microcrystalline cellulose with the urea includes dosing the microcrystalline cellulose having a dry matter content in a range of 40% to 70% before being dosed with the urea, and the dosage of the urea is in a range of 4% to 10% of the dry matter content of the microcrystalline cellulose.

9. A method comprising:
treating, in a pulp mill, chemical pulp with acid hydrolysis which yields microcrystalline cellulose and hydrolysate;
reacting, in a microcrystalline cellulose plant integrated with the pulp mill, the microcrystalline cellulose with urea to produce cellulose carbamate and ammonia;
extracting carbon dioxide from a flue gas flowing through a flue gas system in the pulp mill; and
reacting the carbon dioxide with the ammonia, in a cellulose carbamate plant integrated with the microcrystalline cellulose plant and the pulp mill, to produce the urea to be reacted with the microcrystalline cellulose.

10. The method of claim 9 , wherein the acid hydrolysis is at a temperature in a range of 130 to 160 degrees Celsius.

11. The method according to claim 9 , wherein the flue gas system is associated with a lime kiln, and the carbon dioxide is obtained from flue gases produced in the lime kiln.

12. The method according to claim 9 , wherein the released ammonia is used to neutralize hydrolysate and/or acidic wastewater from the production of the microcrystalline cellulose.

13. The method according to claim 9 , further comprising feeding at least a portion of nitrogen containing wastewater from the production of the cellulose carbamate to an evaporation plant which concentrates the nitrogen containing wastewater to produce dry nitrogen fertilizers.

14. The method according to claim 9 , further comprising conveying nitrogen-containing wastewater from the production of the cellulose carbamate to a wastewater treatment plant of the pulp mill to be used as nutrient.

15. The method according to claim 9 , wherein hydrolysate and/or acidic wastewater from the microcrystalline cellulose production is used to neutralize wastewater from the cellulose carbamate production.

16. The method according to claim 9 , wherein the chemical pulp is a bleached fibrous cellulosic wood pulp.

17. The method according to claim 9 , wherein the step of reacting the microcrystalline cellulose with the urea includes dosing the microcrystalline cellulose having a dry matter content in a range of 40% to 70% before being dosed with the urea, and the dosage of the urea is in a range of 4% to 10% of the dry matter content of the microcrystalline cellulose.

Assignees

• Andritz Oy

Inventors

• Kantola Jukka
• Råmark Hannu
• Valta Kyösti
• Vanhatalo Kari

Classifications

• C07C273/04

  from carbon dioxide and ammonia · CPC title

• C08B15/02

  Oxycellulose; Hydrocellulose; {Cellulosehydrate, e.g. microcrystalline cellulose} · CPC title

• C08B15/06 Primary

  containing nitrogen {, e.g. carbamates} · CPC title

• C05B3/00

  Fertilisers based essentially on di-calcium phosphate (C05B11/00 takes precedence) · CPC title

• C05C11/00

  Other nitrogenous fertilisers · CPC title