A method for optimizing the composition of cold box inlet raw gas

Abstract

This invention belongs to the field of cryogenic device process optimization, specifically a method for optimizing the composition of the feed gas at the cold box inlet. This method primarily replaces the dehydrated purified gas with nitrogen from the dehydration tower, thereby preventing nitrogen accumulated in the dehydration tower during the regeneration phase from entering the cold box along with the feed gas. This method is simple and low-cost, effectively reducing the impact of nitrogen accumulated during the regeneration process on the composition of the feed gas at the cold box inlet, thereby ensuring stable cold box operation.

Description

Technical Field

[0001] The invention belongs to the field of process optimization of cryogenic devices, and in particular relates to a method for optimizing the components of raw gas at a cold box inlet. Background Art

[0002] Producing LNG by separating methane from coke oven gas through cryogenic separation technology is an economical and safe production process. However, the cryogenic separation device has very strict requirements on the water content in the raw gas. Generally, a dehydration device is added at the inlet of the cold box. The saturated water in the raw gas is removed by the molecular sieve in the dehydration device. At the same time, the molecular sieve in the dehydration device is regenerated with nitrogen, so that the molecular sieve can be reused. However, during the operation of the device, it was found that when the molecular sieve enters the adsorption state after regeneration, the nitrogen left by the molecular sieve during the regeneration process will enter the cold box along with the raw gas, causing the raw gas composition entering the cold box to fluctuate, affecting the safe and stable operation of the cold box. Summary of the Invention

[0003] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for optimizing the composition of the raw gas at the cold box inlet, thereby preventing the nitrogen accumulated in the dehydration tower during the regeneration stage from entering the cold box along with the raw gas, causing changes in the composition of the raw gas at the cold box inlet.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for optimizing the components of raw gas inlet of a cold box, comprising a dehydration tower A, a dehydration tower B, a dehydration tower C, a raw gas inlet valve 1A, a raw gas inlet valve 1B, a raw gas inlet valve 1C, a raw gas outlet valve 2A, a raw gas outlet valve 2B, a raw gas outlet valve 2C, a cold regeneration gas inlet valve 3A, a cold regeneration gas inlet valve 3B, a cold regeneration gas inlet valve 3C, a cold regeneration gas outlet valve 4A, a cold regeneration gas outlet valve 4B, a cold regeneration gas outlet valve 4C, a hot regeneration gas inlet valve 5A, a hot regeneration gas inlet valve 5B, a hot regeneration gas inlet valve 5C, a hot regeneration gas outlet valve 8A, a hot regeneration gas outlet valve 8B, a hot regeneration gas outlet valve 8C, a pressure charging valve 6A, a pressure charging valve 6B, a pressure charging valve 6C, a pressure relief valve 7A, a pressure relief valve 7B, and a pressure relief valve 7C. The raw gas enters the dehydration tower A, the dehydration tower B, the dehydration tower C through a pipeline via the raw gas inlet valve 1A, the raw gas inlet valve 1B, and the raw gas inlet valve 1C, respectively. C, and then enter the cold box through the raw gas outlet valve 2A, raw gas outlet valve 2B, and raw gas outlet valve 2C respectively; the hot nitrogen in the regeneration gas heater enters the dehydration tower A, dehydration tower B, and dehydration tower C respectively through the hot regeneration gas inlet valve 5A, hot regeneration gas inlet valve 5B, and hot regeneration gas inlet valve 5C, and then is sent to the flare through the hot regeneration gas outlet valve 8A, hot regeneration gas outlet valve 8B, and hot regeneration gas outlet valve 8C respectively; the cold nitrogen enters the dehydration tower A, dehydration tower B, and dehydration tower C respectively through the cold regeneration gas inlet valve 3A, cold regeneration gas inlet valve 3B, and cold regeneration gas inlet valve 3C, and then enters the regeneration gas heater through the cold regeneration gas outlet valve 4A, cold regeneration gas outlet valve 4B, and cold regeneration gas outlet valve 4C respectively; the purified gas enters the dehydration tower A, dehydration tower B, and dehydration tower C respectively through the charging valve 6A, charging valve 6B, and charging valve 6C, and then is sent to the flare through the pressure relief valve 7A, pressure relief valve 7B, and pressure relief valve 7C respectively.

[0006] Furthermore, the dehydration tower A, dehydration tower B and dehydration tower C are connected in parallel, and in one cycle, each of them sequentially experiences three operating states: adsorption state, heat regeneration state and cold cooling state;

[0007] When the dehydration tower A is in the adsorption state, open the raw gas inlet valve 1A and the raw gas outlet valve 2A, and the raw gas enters the dehydration tower A through the raw gas inlet valve 1A. After the saturated water in the raw gas is removed, it enters the cold box as the purified gas through the raw gas outlet valve 2A.

[0008] In the hot regeneration state, close the raw gas inlet valve 1A and the raw gas outlet valve 2A, open the hot regeneration gas inlet valve 5A and the hot regeneration gas outlet valve 8A, and the hot nitrogen in the regeneration gas heater regenerates the dehydration tower A through the hot regeneration gas inlet valve 5A, and then is sent to the flare through the hot regeneration gas outlet valve 8A;

[0009] In the cold cooling state, close the hot regeneration gas inlet valve 5A and the hot regeneration gas outlet valve 8A, open the cold regeneration gas inlet valve 3A and the cold regeneration gas outlet valve 4A, and the cold nitrogen passes through the cold regeneration gas inlet valve 3A to cool the dehydration tower A, and then passes through the cold regeneration gas outlet valve 4A to the regeneration gas heater;

[0010] The dehydrated purified gas replaces the nitrogen in the dehydration tower A. Close the cold regeneration gas inlet valve 3A and the cold regeneration gas outlet valve 4A, open the pressure valve 6A, and pressurize the dehydration tower A with purified gas. After the pressure reaches 0.3 MPa, close the pressure valve 6A and open the pressure relief valve 7A to relieve the pressure of the dehydration tower A to normal pressure. Repeat this operation twice to replace the nitrogen in the dehydration tower A.

[0011] After the above process, the dehydration tower A completes a complete cycle, and the dehydration tower A enters the adsorption state again to enter the next cycle.

[0012] The operating status of dehydration tower B and dehydration tower C is the same as that of dehydration tower A.

[0013] Compared with the prior art, the present invention provides a method for optimizing the composition of the raw gas at the cold box inlet. The method has a simple process flow and low cost, and effectively prevents the nitrogen accumulated in the dehydration tower during the regeneration stage from entering the cold box along with the raw gas, causing changes in the composition of the raw gas at the cold box inlet, thereby ensuring the stability of the cold box operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of a method for optimizing the composition of the cold box inlet feed gas. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] Example

[0017] like Figure 1As shown, this embodiment provides a method for optimizing the components of the raw gas inlet of the cold box, including dehydration tower A, dehydration tower B, dehydration tower C, raw gas inlet valve 1A, raw gas inlet valve 1B, raw gas inlet valve 1C, raw gas outlet valve 2A, raw gas outlet valve 2B, raw gas outlet valve 2C, cold regeneration gas inlet valve 3A, cold regeneration gas inlet valve 3B, cold regeneration gas inlet valve 3C, cold regeneration gas outlet valve 4A, cold regeneration gas outlet valve 4B, cold regeneration gas outlet valve 4C, hot regeneration gas inlet valve 5A, hot regeneration gas inlet valve 5B, hot regeneration gas inlet valve 5C, hot regeneration gas outlet valve 8A, hot regeneration gas outlet valve 8B, hot regeneration gas outlet valve 8C, charging valve 6A, charging valve 6B, charging valve 6C, pressure relief valve 7A, pressure relief valve 7B, pressure relief valve 7C, the raw gas enters the dehydration tower A and dehydration tower C through the pipeline via the raw gas inlet valve 1A, raw gas inlet valve 1B, and raw gas inlet valve 1C respectively. B, dehydration tower C, and then enter the cold box through the raw gas outlet valve 2A, raw gas outlet valve 2B, and raw gas outlet valve 2C respectively; the hot nitrogen in the regeneration gas heater enters the dehydration tower A, dehydration tower B, and dehydration tower C through the hot regeneration gas inlet valve 5A, hot regeneration gas inlet valve 5B, and hot regeneration gas inlet valve 5C respectively, and then is sent to the torch through the hot regeneration gas outlet valve 8A, hot regeneration gas outlet valve 8B, and hot regeneration gas outlet valve 8C respectively; the cold nitrogen is sent to the flare through the cold regeneration gas inlet valve Door 3A, cold regeneration gas inlet valve 3B, cold regeneration gas inlet valve 3C enter dehydration tower A, dehydration tower B, dehydration tower C respectively, and then pass through cold regeneration gas outlet valve 4A, cold regeneration gas outlet valve 4B, cold regeneration gas outlet valve 4C to enter the regeneration gas heater respectively; the purified gas enters dehydration tower A, dehydration tower B, dehydration tower C respectively through charging valve 6A, charging valve 6B, charging valve 6C, and then passes through pressure relief valve 7A, pressure relief valve 7B, pressure relief valve 7C to be sent to the flare respectively.

[0018] The dehydration tower A, dehydration tower B and dehydration tower C are connected in parallel, and in one cycle, each of them sequentially experiences three operating states: adsorption state, thermal regeneration state and cold cooling state;

[0019] When the dehydration tower A is in the adsorption state, open the raw gas inlet valve 1A and the raw gas outlet valve 2A, and the raw gas enters the dehydration tower A through the raw gas inlet valve 1A. After the saturated water in the raw gas is removed, it enters the cold box as the purified gas through the raw gas outlet valve 2A.

[0020] In the hot regeneration state, close the raw gas inlet valve 1A and the raw gas outlet valve 2A, open the hot regeneration gas inlet valve 5A and the hot regeneration gas outlet valve 8A, and the hot nitrogen in the regeneration gas heater regenerates the dehydration tower A through the hot regeneration gas inlet valve 5A, and then is sent to the flare through the hot regeneration gas outlet valve 8A;

[0021] In the cold cooling state, close the hot regeneration gas inlet valve 5A and the hot regeneration gas outlet valve 8A, open the cold regeneration gas inlet valve 3A and the cold regeneration gas outlet valve 4A, and the cold nitrogen passes through the cold regeneration gas inlet valve 3A to cool the dehydration tower A, and then passes through the cold regeneration gas outlet valve 4A to the regeneration gas heater;

[0022] The dehydrated purified gas replaces the nitrogen in the dehydration tower A. Close the cold regeneration gas inlet valve 3A and the cold regeneration gas outlet valve 4A, open the pressure valve 6A, and pressurize the dehydration tower A with purified gas. After the pressure reaches 0.3 MPa, close the pressure valve 6A and open the pressure relief valve 7A to relieve the pressure of the dehydration tower A to normal pressure. Repeat this operation twice to replace the nitrogen in the dehydration tower A.

[0023] The operating status of dehydration tower B and dehydration tower C is the same as that of dehydration tower A.

[0024] The above description is only a preferred embodiment of the present invention, but does not limit the scope of protection of the patent of the present invention. Any technical solution obtained by equivalent replacement or equivalent transformation should fall within the scope of protection of the present invention.

Claims

1. A method for optimizing the composition of the cold box inlet raw gas, characterized in that: It includes dehydration tower A, dehydration tower B, dehydration tower C, raw gas inlet valve 1A, raw gas inlet valve 1B, raw gas inlet valve 1C, raw gas outlet valve 2A, raw gas outlet valve 2B, raw gas outlet valve 2C, cold regeneration gas inlet valve 3A, cold regeneration gas inlet valve 3B, cold regeneration gas inlet valve 3C, cold regeneration gas outlet valve 4A, cold regeneration gas outlet valve 4B, cold regeneration gas outlet valve 4C, hot regeneration gas inlet valve 5A, hot regeneration gas inlet valve 5B, hot regeneration gas inlet valve 5C, hot regeneration gas outlet valve 8A, hot regeneration gas outlet valve 8B, hot regeneration gas outlet valve 8C, charging valve 6A, charging valve 6B, charging valve 6C, pressure relief valve 7A, pressure relief valve 7B, pressure relief valve 7C. The raw gas enters dehydration tower A, dehydration tower B and dehydration tower C respectively through the pipeline via the raw gas inlet valve 1A, raw gas inlet valve 1B and raw gas inlet valve 1C, and then passes through the raw gas inlet valve 1A, raw gas inlet valve 1B and raw gas inlet valve 1C respectively. The feed gas outlet valve 2A, the raw gas outlet valve 2B, and the raw gas outlet valve 2C enter the cold box; the hot nitrogen in the regeneration gas heater enters the dehydration tower A, dehydration tower B, and dehydration tower C respectively through the hot regeneration gas inlet valve 5A, the hot regeneration gas inlet valve 5B, and the hot regeneration gas inlet valve 5C, and then is sent to the torch through the hot regeneration gas outlet valve 8A, the hot regeneration gas outlet valve 8B, and the hot regeneration gas outlet valve 8C respectively; the cold nitrogen enters the dehydration tower A, dehydration tower B, and dehydration tower C respectively through the cold regeneration gas inlet valve 3A, the cold regeneration gas inlet valve 3B, and the cold regeneration gas inlet valve 3C, and then enters the regeneration gas heater through the cold regeneration gas outlet valve 4A, the cold regeneration gas outlet valve 4B, and the cold regeneration gas outlet valve 4C respectively; the purified gas enters the dehydration tower A, dehydration tower B, and dehydration tower C respectively through the charging valve 6A, the charging valve 6B, and the charging valve 6C, and then is sent to the flare through the pressure relief valve 7A, the pressure relief valve 7B, and the pressure relief valve 7C respectively; The dehydration tower A, dehydration tower B and dehydration tower C are connected in parallel, and in one cycle, each of them sequentially experiences three operating states: adsorption state, thermal regeneration state and cold cooling state; When the dehydration tower A is in the adsorption state, open the raw gas inlet valve 1A and the raw gas outlet valve 2A, and the raw gas enters the dehydration tower A through the raw gas inlet valve 1A. After the saturated water in the raw gas is removed, it enters the cold box as the purified gas through the raw gas outlet valve 2A. In the hot regeneration state, close the raw gas inlet valve 1A and the raw gas outlet valve 2A, open the hot regeneration gas inlet valve 5A and the hot regeneration gas outlet valve 8A, and the hot nitrogen in the regeneration gas heater regenerates the dehydration tower A through the hot regeneration gas inlet valve 5A, and then is sent to the flare through the hot regeneration gas outlet valve 8A; In the cold cooling state, close the hot regeneration gas inlet valve 5A and the hot regeneration gas outlet valve 8A, open the cold regeneration gas inlet valve 3A and the cold regeneration gas outlet valve 4A, and the cold nitrogen passes through the cold regeneration gas inlet valve 3A to cool the dehydration tower A, and then passes through the cold regeneration gas outlet valve 4A to the regeneration gas heater; The dehydrated purified gas replaces the nitrogen in the dehydration tower A. Close the cold regeneration gas inlet valve 3A and the cold regeneration gas outlet valve 4A, open the pressure valve 6A, and pressurize the dehydration tower A with purified gas. After the pressure reaches 0.3 MPa, close the pressure valve 6A and open the pressure relief valve 7A to relieve the pressure of the dehydration tower A to normal pressure. Repeat this operation twice to replace the nitrogen in the dehydration tower A. The operating status of dehydration tower B and dehydration tower C is the same as that of dehydration tower A.

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