Industrial Calcination Apparatus

Abstract

The present application describes an industrial calciner for particulate material, wherein the industrial calciner comprises: a calcination vessel; and a gas supply system in fluid communication with the calcination vessel, the gas supply system configured to supply a flow of calcination gas to the calcination vessel, wherein the industrial calciner further comprises at least one electric heater configured to heat the calcination gas, the industrial calciner further comprising at least one humidity modifier and a humidity control system for controlling the output of the at least one humidity modifier. Use of the industrial calciner and a method of calcining particulate material with the industrial calciner are also described.

Claims

1. An industrial calciner for particulate material, wherein said industrial calciner comprises: a calcination vessel; and a gas supply system in fluid communication with said calcination vessel, said gas supply system configured to supply a flow of calcination gas to said calcination vessel, wherein said industrial calciner further comprises at least one electric heater configured to heat said calcination gas, wherein said industrial calciner further comprises at least one humidity modifier and a humidity control system for controlling the output of said at least one humidity modifier.

2. The industrial calciner of claim 1, wherein said at least one electric heater is located within said gas supply system.

3. The industrial calciner of claim 1, wherein said calcination vessel comprises a grinder for reducing the size of the particulate material.

4. The industrial calciner of claim 1, wherein said gas supply system comprises a heat exchanger and/or heat pump configured to extract heat energy from the calcination gas leaving the calcination vessel.

5. The industrial calciner of claim 4, wherein said heat exchanger and/or heat pump is configured to heat at least a portion of the calcination gas before it enters the calcination vessel.

6. The industrial calciner of claim 1, wherein said industrial calciner comprises a heating control system configured to the output of the at least one electric heater.

7. The industrial calciner of claim 1, wherein said humidity control system comprises at least one humidity sensor.

8. The industrial calciner of claim 1, wherein said industrial calciner comprises a pressure control system configured to control the pressure within the industrial calciner.

9. The industrial calciner of claim 1, wherein said industrial calciner comprises an airflow control system for controlling the airflow through the industrial calciner.

10. The industrial calciner of claim 1, wherein said industrial calciner further comprises a filter unit, wherein said filter unit is configured to remove calcined particulate matter from said calcination gas.

11. The industrial calciner of claim 1, wherein said industrial calciner is configured to recirculate at least a portion of said calcination gas.

12. The industrial calciner of claim 1, wherein said industrial calciner comprises a plurality of electric heaters.

13. (canceled)

14. A method of calcining particulate material, the method comprising the steps of: providing the industrial calciner of claim 1; providing gypsum; placing the gypsum into said calcination vessel; exposing the particulate material to heat from the at least one electric heater; and calcining the particulate material.

15. The industrial calciner of claim 6, wherein said heating control system comprises at least one temperature sensor.

16. The industrial calciner of claim 8, wherein said pressure control system comprises at least one pressure sensor.

17. The industrial calciner of claim 9, wherein said airflow control system comprises at least one airflow sensor.

Description

DETAILED DESCRIPTION

[0043] Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

[0044] FIG. 1 is a diagram of an industrial calciner in accordance with the first aspect of the present invention.

[0045] With reference to FIG. 1, there is illustrated an industrial calciner 100 for particulate material comprising a calcination vessel 101. In the following description, the industrial calciner 100 is illustrated for use with raw gypsum for the production of calcium sulphate hemihydrate, a principle component in gypsum boards and panels. However, it is envisaged that the particulate matter to be calcined is not particularly limited.

[0046] The calcination vessel 101 comprises an upper portion with a particulate inlet 102 at a first end 101a and a cylindrical portion at a second end 101b. It is envisaged, that in further embodiments, the upper portion may be frustoconical. The industrial calciner 100 further comprises a feed-in unit 103 arranged to feed particulate material into the calcination vessel 101. The feed-in unit 103 is located at the first end 101a of the calcination vessel 101. The feed-in unit 103 comprises an inlet for deposition of particulate material, such as gypsum, into the feed-in unit 103 and a feeder for feeding the particulate material into the calcination vessel 101 via the particulate inlet 102. It is envisaged that the feeder may be any suitable feeder, for example a chain feeder or a weigh belt feeder.

[0047] The feed-in unit 103 comprises a first motor M1 and a particulate feed-in control system for controlling the rate of particulate material feed-in of the feed-in unit 103. In this way, the speed of deposition of particulate matter into the calcination vessel 101 can be controlled.

[0048] The calcination vessel 101 comprises a grinder 104, located at the second end 101b of the calcination vessel 101, for reducing the size of the particulate material. The grinder 104 comprises a grinder motor M2 and a grinding control system for controlling the rate of grinding of the particulate material. In this way, the rate of grinding and consequently the size of the particulate material within the calcination vessel 101 can be controlled.

[0049] The industrial calciner 100 further comprises a gas supply system 105 in fluid communication with the calcination vessel 101. The calcination vessel 101 comprises a fluid inlet 106 located at the second end 101b of the calcination vessel 101. The gas supply system 105 is configured to supply a flow of calcination gas to the calcination vessel 101 via the fluid inlet 106.

[0050] The gas supply system 105 comprises a heating vessel 107 and an air inlet A. The air inlet A is in fluid communication with the heating vessel 107 and is arranged to supply ambient air to the heating vessel 107 from a fresh air source. The gas supply system 105 further comprises a first fan 115 for assisting flow of air via the air inlet A into the heating vessel 107.

[0051] The industrial calciner 100 comprises a plurality of electric heaters 108 configured to heat the calcination gas. The plurality of electric heaters 108 are located within the heating vessel 107 of the gas supply system 105. The calcination gas is formed in the heating vessel 107 and comprises air supplied via the air inlet A that is heated by the plurality of electric heaters 108.

[0052] In this embodiment, raw gypsum deposited into the feed-in unit 103 is fed into the calcination vessel 101 and is subsequently ground by the grinder 104 to reduce the size of the gypsum particles. The ground gypsum is thus located at the second end 101b of the calcination vessel 101. Calcination gas is then supplied to the calcination vessel 101 from the gas supply system 105 via the fluid inlet 106, such that the calcination vessel 101 contains both the ground gypsum and the heated calcination gas. In this way, the particulate material is exposed to heat from the plurality of electric heaters 108 via the heated gas.

[0053] The process of heating the ground gypsum with the calcination gas calcines the gypsum such that calcium sulphate hemihydrate is formed in the calcination vessel 101. This process results in calcined particulate matter being mixed in the calcination gas within the calcination vessel 101. The calcination gas, comprising calcined particulate matter, then rises to the first end 101a of the calcination vessel 101 under thermodynamic principles.

[0054] The calcination vessel 101 is in fluid communication with a filter unit 111 that is configured to remove calcined particulate matter from the calcination gas. The calcination vessel 101 comprises a fluid outlet 110 located at the first end 101a, and the calcination gas exits the calcination vessel 101 via the fluid outlet 110. The calcination gas then passes through the filter unit 111, wherein the calcium sulphate hemihydrate particles are removed from the calcination gas. In this way, the calcined gypsum can be collected from the industrial calciner 100 for further use.

[0055] The industrial calciner 100 is configured to recirculate at least a portion of the calcination gas. The filter unit 111 is in fluid communication with the gas supply system 105 such that calcination gas exiting the filter unit 111 after extraction of the calcined gypsum can re-enter the gas supply system 105. The recirculated calcination gas re-enters the heating vessel 107 and mixes with the calcination gas entering the heating vessel 107 via the air inlet A. As such, there is a lower quantity of air from the air inlet A demanded by the industrial calciner 100 due to the recirculation of gas previously used in the calcination process. The plurality of electric heaters 108 heat the mix of inlet gas and recirculated gas within the heating vessel 107 to the desired temperature. The industrial calciner 100 is configured such that it may continuously calcine particulate material such that a continuous calcination process is provided.

[0056] Alternatively, the calcination gas may exit the industrial calciner 100 into the external environment via an exhaust outlet 112. A first valve 114 regulates the quantity of calcination gas exiting the industrial calciner 100 via the exhaust outlet 112 allowing the quantity of calcination gas recirculated to be controlled. The flow of calcination gas exiting the filter unit 111 is assisted by a second fan 117 located adjacent the filter unit 111. The second fan 117 assists the flow of calcination gas for both recirculation and emission to the external environment.

[0057] The gas supply system 105 also comprises a heat exchanger 118 configured to extract heat energy from the calcination gas leaving the calcination vessel 101. While a heat exchanger 118 is depicted in the present embodiment, the use of a heat pump is also envisaged either alone or in combination with a heat exchanger. The heat exchanger 118 is configured to heat at least a portion of the calcination gas before it enters the calcination vessel 101. In this way, the industrial calciner 100 has a lower resource demand and an improved efficiency as thermal energy is recovered and re-used.

[0058] The industrial calciner 100 comprises a pressure control system for controlling the pressure within the industrial calciner 100. The pressure control system comprises a pressure sensor PT located within the industrial calciner 100 to measure the pressure between the calcination gas entering the calcination vessel 101 and the calcination gas exiting the industrial calciner 100 via the exhaust outlet 112. The industrial calciner 100 is configured to control the pressure control system in response to the measurement of the pressure sensor PT.

[0059] The industrial calciner 100 further comprises a heating control system for controlling the output of the plurality of electric heaters 108. The heating control system comprises a temperature sensor TT located within the industrial calciner 100 configured to measure the temperature of the calcination gas exiting the calcination vessel 101. The heating control system comprises a computer processor configured to control the plurality of electric heaters 108 to maintain a heating parameter within a desired range, in part by controlling the electricity input to the plurality of electric heaters 108. The heating control system modifies the operation of at least one electric heater of the plurality of electric heaters 108 if the temperature measured by the temperature sensor TT falls outside of a desired range.

[0060] The industrial calciner 100 further comprises a humidity modifier and a humidity control system for controlling the output of the humidity modifier. The humidity control system comprises a humidity sensor located within the industrial calciner 100 configured to measure the humidity within the calcination vessel 101 and the humidity control system is configured to control the humidity modifier in response to the measurement of the humidity sensor. The humidity control system comprises a computer processor configured to control the humidity modifier to maintain a humidity parameter within a desired range and the humidity modifier can both increase and reduce the humidity within the industrial calciner 100.

[0061] Both the temperature control system and the humidity control system are configured to issue an alert if each of the temperature parameter and the humidity parameter respectively fall outside the desired ranges. The issuance of each alert is recorded within the temperature control system and the humidity control system respectively. In this way, the calcination conditions within the industrial calciner 100 can be monitored and a log of periods of unfavourable conditions is built.

[0062] The industrial calciner 100 further comprises an airflow control system for controlling the output of the humidity modifier. The airflow control system comprises a first airflow sensor FT located within the industrial calciner 100 to measure at least one characteristic of airflow of the calcination gas exiting the filter unit 111. The airflow control system further comprises a second airflow sensor FT′ located within the industrial calciner 100 to measure at least one characteristic of airflow of the calcination gas entering the industrial calciner 100. The airflow control system is configured to control the airflow through the industrial calciner 100 in response to the measurement of the first airflow sensor FT and/or the second airflow sensor FT′.

[0063] In this way, pressure, temperature, humidity and airflow characteristics within the industrial calciner 100 can be more closely controlled and optimised calcination conditions can be provided. Controlled humidity of the calcination conditions within the calcination vessel 101 allows the industrial calciner 100 to operate over both a wider temperature and wider humidity range. Additionally, use of the plurality of electric heaters 108 improves the characteristics of the calcined gypsum particles as improved control and precision of the calcination conditions allows for optimisation of particle size as well as a reduction in under-calcination and over-calcination of the particulate matter.